Body capacitance electric field powered device for high voltage lines

Devices that couple to high voltage transmission lines obtain power themselves using the body capacitance of an element of the devices. The devices generate a comparatively lower voltage from the current flowing between the high voltage line and the element of the device that generates the body capacitance. The devices can be used to operate sensors that monitor the transmission lines or parameters of the power distribution system, such as current, line temperature, vibration, and the like. The devices can also be used as indicators, such as aircraft warning lights, information signs, etc. In addition, the devices can operate as RF transmission/reception or repeater devices, radar devices, mesh networking nodes, video/audio surveillance, sound emitting devices for scaring animals, drones that traverse the power line, etc. Because the devices operate in response to line voltage rather than current, the devices are reliable even in low current conditions.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to devices operative to be coupled to high voltage electric power lines.

2. The Relevant Technology

Typically when it is necessary for a power company to transmit electrical power over long distances, it is transmitted at relatively high voltages. These high voltages are often much higher than the voltages used by customers of the electric power. When a voltage greater than 1 kilovolt (kV) and less than 40 kV is used for a particular power line, the power line is typically referred to as a distribution line. When a voltage greater than 40 kV is used, the power line is typically referred to as a transmission line. Transmission lines are generally used to transmit larger amounts of power over greater distances than distribution lines.

When a producer of electric power wants to connect to the electric grid, a connection can be made at either distribution line or transmission line level depending on the capacity of the producer's generating plant. Increasingly, due to deregulation in the power industry, the producer's generating plant is not owned by the same company as the transmission and distribution lines the plant will connect to. These types of producers are often referred to as independent power producers (IPPs). Since the power lines and the generating plant are not owned by the same company, it becomes much more important to accurately determine the amount of power the plant is feeding into the electrical grid through the transmission or distribution lines. Even when the generating plant and the power lines are owned by the same company, it is often advantageous to accurately monitor the amount of power being fed into the electrical grid.

IPPs will often only produce power when the demand for power is such that it is economical to do so. Therefore some IPPs may only produce power for a small percentage of time during a year. When the IPP is not feeding power into the grid, its generators are normally shut down and the IPP actually draws power from the electrical grid. The amount of power drawn from the grid in this situation is usually much smaller than when the IPP is generating power. A power usage by the IPP that is only 1/1000thof its power generation capability or less is quite possible when the plant is idle. It is often desirable that the IPP be accurately billed for the energy it consumes during idle periods and accurately compensated for energy generated during active periods.

It is desirable for the energy meter and other instrumentation monitoring the flow of power to and from the producer to accurately measure both the power usage when the producer is idle and the power production when the producer is operating. This means that accurate energy metering and monitoring over a wide dynamic range such as 1000 times may be necessary. The energy metering and monitoring is often done at grid level voltages. Therefore, the voltage does not vary greatly (perhaps by +/−10% of its nominal value). This means that the wide variation in power flow seen by the energy metering and monitoring equipment is primarily due to the variation in current.

An energy meter capable of measuring over a wide dynamic range of current is described in U.S. patent application Ser. No. 10/341,079 to Hyatt et al. and entitled “Energy Device with an Extended Dynamic Range on Current Readings” which is incorporated herein by reference.

Using an energy meter with a wide dynamic range capability for current is part of the solution for accurately monitoring the flow of power to and from a producer. Energy meters for this type of application are typically connected through external current and voltage sensors. At least the current sensors themselves should also have a wide dynamic range. Optical current sensors such as those described in the document entitled “OPTICAL TECHNOLOGY: A NEW GENERATION OF INSTRUMENT TRANSFORMER” by Klimek published in Issue 2/2003 of Electricity Today have often provided the largest dynamic range. These sensors are often mounted on large insulator stacks and weigh 100 s of kilograms.

The installation costs for sensors mounted to high voltage transmission lines may often be significant. In fact, the installation cost may be more than the cost of the sensor itself in some cases. Some of the reasons for this include the large size and weight of the sensors and the downtime that is experienced when installing, re-installing or replacing a defective sensor. Most of the weight and size of many of these sensors is the insulator used to isolate the sensor from ground and support the sensor.

Another consideration that must be taken into account when accurately accounting for energy produced and consumed by a producer is that the instrumentation may have to be regularly calibrated to ensure accuracy. This means that the sensors may be regularly un-installed and sent for calibration while a replacement sensor is installed. This results in the install/re-install costs as well as significant shipping costs due to the weight of the sensors. This recalibration interval may be approximately every three years and the install-reinstall costs for a single sensor may be in the neighborhood of $100,000 US.

Sensors that power themselves using the magnetic field generated by the current flowing through the line they are monitoring are also available. One such device is described in U.S. Pat. No. 4,799,005 to Fernandes entitled “Electrical Power Line Parameter Measurement Apparatus and Systems, Including Compact, Line-Mounted Modules”. Although this device may enable decreased install-reinstall costs, but because it is powered from the magnetic field generated by the current flowing through the line it is measuring, it may not be usable when the line current varies over a wide dynamic range. This is due to the fact that the magnetic field generated at low current may not be adequate to generate enough power to power the device or the current transformer (“CT”) and associated circuitry used to power the device may be too complex or expensive to be practical.

High voltage electric power lines criss-cross the landscape. These lines pass over waterways, valleys, highways, through and around cities, etc. They are sometimes visible to observers on the ground. They are sometimes not particularly visible to aircraft. This is especially a problem where they cross vast expanses such as over valleys or waterways where there is a long distance between support towers. Transmission line support structures are often illuminated with obstruction lights through the employment of low voltage AC mains distribution power supply means and standard red incandescent obstruction light fixtures as specified by the Federal Aviation Advisory Circular 150/5345-43E. Identification of the actual transmission line catenary wires is often limited to the suspension of passive, brightly painted spheres. These afford little aeronautical identification at nighttime or under conditions of reduced visibility.

Recent technical advances have resulted in the ability to attach obstruction lighting directly to high voltage transmission line wires through a number of self-powering means not requiring connection to an external power source. Federal Aviation Advisory Circular AC 70/7460-1K now provides guidelines detailing the use of direct catenary wire obstruction lighting. U.S. Pat. No. 5,448,138 entitled “Aeronautical obstruction light” describes a device capable of direct obstruction illumination that extracts power through magnetic coupling using a coupling coil mounted in proximity of the power line. P and R Technologies of Beaverton, Oreg., offer a number of self-powered transmission line obstruction markers. Their SpanFlash™ series of transmission line markers employ a magnetic field power supply that requires a minimum of 50 Amperes for correct operation combined with a gas discharge lighting solution. This technique does not work when transmission line currents fall below a lower limit that results in insufficient magnetic field to support adequate power generation. Many transmission lines, particularly those coming from independent power producers, experience wide operating current ranges depending on load conditions.

BRIEF SUMMARY OF THE INVENTION

According to one of various aspects of the invention, an apparatus couples to a power line carrying a high AC line voltage. The apparatus has a conductive body with a body capacitance. The apparatus further has a power supply with at least two input terminals, including a first input terminal coupled to the conductive body and a second input terminal coupled to the power line. The power supply is coupled with electronic circuitry and converts power flow between the conductive body and the power line into a supply of power for the electronic circuitry at a voltage that is substantially lower than the high AC line voltage.

As further described herein, the invention also has other aspects that convert power flow between a conductive body and a power line into a supply of power for electronic circuitry. The present invention is defined by the following claims, and nothing in this summary should be taken as a limitation on those claims. Further aspects and advantages of the invention are discussed below in conjunction with the preferred embodiments.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS

The invention relates to devices that are attachable to high voltage transmission lines and power themselves by generating a comparatively lower voltage from the current flowing between the high voltage line and the body capacitance of an element of the device. One class of devices are sensors. Sensed parameters may include current, line temperature, vibration (due to arcing, corona or other effects), strain/tension (due to ice, wind loading, conductor breakage, tower collapse, etc.), electric field (which is indicative of the steady state and transient voltage on the line), lightning detection (transient or optical), etc. Another class of devices are indicators. Indicators may include aircraft warning lights, information signs, etc. Other devices include RF transmission/reception or repeater devices (such as for use with wireless phones), radar devices, mesh networking nodes, video/audio surveillance, sound emitting devices for scaring animals, drones that traverse the power line, etc. A common component of all these devices relates to the power supply energy source means for generating the comparatively lower voltage required for operation of the device.

As described in greater detail herein, the voltage required for operation of the device is substantially lower than the high AC line voltage. For example, the lower voltage associated with operation of the device is typically less than 100 Vdc. In many examples, a voltage of no more than 12 Vdc is required to operate the sensors, indicators, or other electronic components used in the devices described herein. In contrast, the high AC line voltage can range, for example, from 10 kVac to over 1000 kVac. A typical transmission line has high voltage of 230 kVac line to line (three phase) or 132.8 kVac line to Earth.

Prior art self-powered transmission line sensors, particularly for current measurement, come in a variety of forms as discussed above employing various transducer topologies and data transmission methods. Being self-powered provides an obvious benefit from an installation and high voltage (“HV”) isolation standpoint. In many cases the powering energy comes from a variety of magnetic field methods whereby power is extracted through magnetic induction; typically through the use of a magnetic core and secondary winding clamped axially about the transmission line conductor. The primary difficulty with these methods is the reliance on sufficient line current required to produce sufficient magnetic field strength over some defined and wide dynamic range. At low line currents, for instance the line magnetization current of an idle IPP generating plant, it would be difficult to provide the energy required to power the sensor and its associated electronics (microprocessor, RF link, etc). If the line current is below a critical threshold then the sensor may cease to function completely. One constant is line voltage, which is generally always available. In general, when the voltage disappears in situations other than those associated with short lived transients, the line powering current also disappears and, therefore, there is no longer a need to measure many of the parameters.

Examples of the invention make use of the fact that a metallic or other conducting body (of arbitrary shape) has a body-to-earth capacitance through which an electric current can flow. The current and resulting voltage may be electronically converted to current and voltage levels usable for electronic device energy requirements without requiring a physical connection between two high voltage potentials, which could violate conditions of desirable electrical isolation.

The following description and figures describe various example devices that may be mounted to or form part of an electrical transmission line and derive operating power from the line. Each example device contains a power supply module generally referred to as element108, and each variation of the power supply module is referred to as element108a,108b,108c, etc. It is important to understand that each variation of the power supply module108may be interchangeable within the various example devices and still meet the objectives of the invention.

Referring now toFIG. 1, a high voltage transmission line attachable device (“HVTLAD”)100mountable as a part of a high voltage transmission line is depicted. The HVTLAD100includes a cylindrical sensor body1that is formed from a conductive material (such as aluminum) casing having conductive end pieces5distributed radially and axially about a centrally located transmission conductor10that extends through the cylindrical sensor body1and beyond the conductive end pieces5. The transmission conductor10is supported by and extends through two electrically insulating support bushings15in such a way to be mechanically connected but galvanically isolated from the electrically connected cylindrical sensor body1and conductive end pieces5.

The transmission conductor10further includes end piece cable clamps20or other means for clamping the HVTLAD100in line with a power line conductor and allowing mechanical and electrical connection in a power transmission line system. It is appreciated that the transmission conductor10and cable clamps20are sized appropriately for the line current, tension, and interfacing requirements of a particular transmission line installation. Inclusion of strategically located and sized conductive toroidal corona rings30may prevent unwanted corona discharge in areas where small radius of curvatures dictate their placement. The size of the corona rings30is determined by the transmission line operating voltages and they are typically included at transmission line voltages over approximately 100 kVac. These toroidal corona rings30may be in galvanic and mechanical contact with the cylindrical sensor body1and conductive end pieces5and, apart from their corona reducing effect, provide additional body capacitance. Additional corona shields35may be fitted on the two ends of the transmission conductor10. It is appreciated that the general geometry of the complete sensor body is not limited to the cylindrical shape described but may be of other shapes. It will be appreciated that body capacitance is a function of shape as well as surface area and the preferable shape for a given application is dictated primarily by the AC line operating voltages and spacing requirements. A completely spherical metallic sensor body such as those described below may be employed with similar performance without departing from the general operation as described.

The cylindrical sensor body1houses a power supply module108a. Within the power supply module108a, transformer T136has a primary connection with Np turns connected between the transmission conductor10and the cylindrical sensor body1. The cylindrical sensor body1is galvanically connected to the conductive end pieces5and toroidal corona shields30. It is appreciated that the transmission conductor10is electrically isolated from the rest of the HVTLAD100through the insulator bushings15and that the transmission conductor10operates at high AC voltage levels with respect to earth ground. A small AC primary current Ip37flows through the primary winding into the cylindrical sensor body1as the result of the total body capacitance of the complete HVTLAD100and the high voltage on the transmission conductor10. A typical high AC line voltage value ranges from 10 kV to over 1000 kVac with a typical transmission line value used for this discussion of 230 kVac line to line (three phase) or 132.8 kVac line to Earth.

The body capacitance, with respect to the Earth surface at transmission line heights is in the picofarad (“pF”) range with a typical value for this discussion being 50 pF when the cylindrical sensor body1is about 1 meter long and 30 centimeters in diameter. The geometry of the HVLTAD100, combined with the sensor height above the earth ground plane and the proximity of other conductors such as towers and other transmission conductors (other phase conductors) combine to determine the exact body capacitance. It is important to note that the exact body capacitance is not important provided that it is high enough to establish a sufficient operating primary current Ip37and that the reflected load impedance as presented at the primary winding of transformer T136due to power supply loading is of high enough value to allow sufficient voltage division across the primary winding and effective body capacitance series connection.

The magnitude of primary current Ip37is determined by the transmission line voltage applied to the transmission conductor10and the reactive impedance of the total body capacitance at the particular line frequency (typically 50 or 60 Hz for most transmission lines deployed throughout the world) employed. For illustrative purposes, a body capacitance of 50 pF translates to a reactive impedance of 53 Megaohms at 60 Hz. This results in a reactive primary current Ip37of 132.8 kVac/53e6 equaling 2.5 mA RMS. The potential difference developed across the primary winding of transformer T136is small in relation to the transmission conductor10potential (>132 kVac) with respect to earth ground and may be neglected in the calculation of primary current Ip37flow. The potential difference developed across the primary winding of transformer T136(and thus the potential between the transmission conductor10and the body of the HVTLAD100) is kept small in relation to the transmission conductor10potential due to the clamping action of an active device such as Zener diodes D1and D241as described below.

Transformer T136may be constructed using a tape wound toroidal design and may employ very low-loss core materials in order to reduce primary magnetization currents to levels below the available driving primary current Ip37in order to achieve usable transformer action. It may also be designed with inter-winding capacitances kept to minimal levels. Transformer T136functions as a step down transformer where the ratio of Np/Ns is greater than 1. As an example, a turns ratio of 80 is used but it is appreciated that other turns ratios may be employed. Primary current Ip37induces a secondary current Is40that is rectified through diode bridge DB142and charges capacitor C144. The negative output of diode bridge DB142is connected to system ground43, which is galvanically bonded to the shielded electronics housing60which is also galvanically connected to cylindrical sensor body1. This forms the “system” ground for all electronic circuitry. In this manner the transmission conductor10maintains a voltage differential with respect to the cylindrical sensor body1equal to the primary winding voltage developed across transformer T136. Capacitor C144voltage builds up to a level of +12 Vdc, at which point, the secondary Zener diodes D1and D241clamp the secondary voltage to provide shunt regulation of the +12 Vdc supply voltage45. The Zener diode clamping action limits transformer T136secondary voltage to approximately 12.7 volts peak-to-peak. Transformer T136, through turns ratio Np/Ns transforms the clamped secondary voltage to approximately 1200 volts peak-to-peak at the primary winding. In this manner the high primary voltage of transformer T136, combined with low primary current, is converted to a low voltage at higher current operable to energize sensor electronics.

Inverter/Switcher block46may be provided to supply multiple outputs required by sensor electronics. It operates from the single, 12 Vdc supply voltage45. It is appreciated that other voltage levels and combinations may be required for particular sensing applications without departing from the spirit of the invention. It is also appreciated that other secondary windings and rectifier circuitry could be added to transformer T136in order to reduce the dependency on electronic switch mode voltage conversion circuitry.

A Gas Discharge Tube50may be provided to limit the primary voltage of transformer T136under transient line conditions due to possible lightning strikes or other short duration line events. The Gas Discharge Tube50is characterized by having low inter-electrode capacitance (typically 1 pF), which is advantageous in order to prevent the diversion of body capacitive current from the transformer primary winding. It will be appreciated that other types of transient suppression devices may also be used.

A current transducer65is shown coupled to the transmission conductor10. The current transducer65may have wide dynamic range covering from 100 mA RMS to over 2000 Arms (in the example although many other current ranges are possible). Suitable current sensing topologies include traditional toroidal magnetic core types, actively compensated zero flux types (active CTs), Hall effect, optical current transducers (a component of optical CTs), and Rogowski coils with each having certain advantages or disadvantages including accuracy, cost, weight, dynamic range, and useable bandwidth. An actively compensated core type may be employed when the high accuracy is required for revenue applications. A Rogowski coil may be employed when a high current dynamic range and/or high bandwidth is required for certain protective applications.

The output of the current transducer65is an analog signal that may require amplification and signal conditioning performed by the analog circuitry66. This module may include selectable analog gain blocks under auto-ranging processor control. The analog output of the analog circuitry66may be connected to the Alias Filter and A/D module67which removes frequency components above ½ the sampling or Nyquist rate. The A/D converter digitizes the analog signal at the sample rate (for example 256 samples/second) and provides the digital information to the Processor module68. The Processor Module68controls the analog circuitry66and Alias Filter and A/D Conversion67modules while processing and packetizing the A/D samples stream. The processor module68communicates with the RF data link transceiver69, which is used to transmit the acquired current waveform to the coupled ground based receiver (not shown) where the waveform may be processed for power measurement or power quality information. The RF data link transceiver69may operate at VHF and higher frequencies and employ a robust modulation and error correction method to provide reliable and secure telemetry data in real time. In addition, the RF data link transceiver69and/or processor module68may implement encryption and/or authentication schemes to make it difficult to tamper with the data being transmitted and/or received.

The RF data link transceiver69is coupled to the antenna76through a reactive matching network75formed from L1and C2. The purpose of matching network75is to effectively impedance match the output of the RF data link transceiver69to the antenna76and maintain the DC or low frequency potential of the exposed antenna76at the potential of the shielded electronics housing60. Other inductances, capacitances, transmission line stubs, and/or transformer matching circuitry may be used to achieve similar functionality. The circuitry shown75is essentially a high pass filter with inductor L175maintaining the zero DC and low frequency (50/60 Hz) potential of the antenna76with respect to the shielded electronics housing60common potential.

Cylindrical sensor body1may be split vertically into two separate sections that are insulated from one another. The first section may be used as previously described to derive operating power for the device. The second section may be used to sense the voltage on the transmission conductor10by monitoring current flow from the transmission conductor10to the body capacitance of the second section. A second transducer may thus be provided to supply an analog signal indicative of voltage in transmission conductor to analog circuitry66. In this manner, processor68may directly calculate power parameters such as watts flowing through the transmission conductor due to the local availability of both current and voltage signal information before transmitting the data. Additionally, it may be possible to derive the voltage on the transmission conductor10by monitoring the primary current Ip37flow and using appropriate signal processing without the addition of the second section.

Additional transducers may also be interfaced to processor68and powered by inverter/switcher block46. These additional transducers may include vibration, tension, temperature (both for the conductor and ambient temperature), lightning detector and other types of transducers.

Instead of using an RF data link transceiver69, an RF transmitter may be used. In addition, the RF data link transceiver69may be replaced with a laser, fiber optic or other optical data transceiver or transmitter. This has the advantage of being extremely directional and therefore it is much more difficult to jam or tamper with the signal. RF has the advantage of being less susceptible to obstructions such as airborne particulates, fog, or objects physically blocking the signal path.

Processor68may be equipped for reception of an accurate time base. This time base may come from the RF data link transceiver69or may come from a separate time source such as a global positioning system (GPS) receiver. These may include a disciplined phase locked master clock oscillator. This allows the processor68to accurately timestamp the time of conversion of the A/D sample data that is to be transmitted through the RF data link transceiver69. In addition, A/D sampling may be synchronized to the time source such that for instance sampling may start at a given time boundary (such as even second). This allows the accurate computation of power parameters (such as kW, kVAR, kVA, power factor, symmetrical components, etc.) by the ground based transceiver or computer/intelligent electronic device attached thereto. It also allows for comparison of phase calculations resulting from the sampling of multiple HVTLADs100. A GPS receiver may also provide the location of the HVTLAD100to the processor68. The location of the HVTLAD100may be transmitted through the RF data link transceiver69to a remote device, such as a computer, that is not physically coupled with the HVTLAD100. The location may include the elevation of the sensor which may be useful in detecting transmission line sag due to broken insulators, overheated conductors, etc. Alternatively, the HVTLAD may comprise a radar or other altimeter for elevation determination. In addition, the location may include longitude and latitude information which may ease commissioning costs due to the fact that the location of the HVTLAD can be correlated with the expected location at the remote device. For instance, it may not be strictly necessary to record the location that any given HVTLAD is installed since the HVTLAD can transmit its location and other configuration information to a remote device. This may be valuable when determining grid stability as described below.

HVTLAD100may be constructed in “clamp-on” form. In this case, transmission conductor10is the transmission line of a power system. Cylindrical sensor body1may be constructed in a manner operable to split horizontally as oriented inFIG. 1and may be placed over the transmission line and clamped together. In this case, cable clamps20and additional corona shields35may not be provided.

Referring now toFIG. 2, a second example of the HVTLAD100is shown. This example of the HVTLAD100includes three component sections; an electric field energy source102, overhead wire conductive support tube107, and electronic obstruction light beacon module104.

The electric field energy source102includes a conductive sphere106, preferably made with aluminum or other electrically conductive material, and a tubular conductive support tube107that extends through the conductive sphere106, and is coupled to both ends of the conductive sphere106through insulators188. The conductive support tube107is therefore galvanically isolated from the conductive sphere106. It is appreciated that the conductive support tube107is at the high electric potential of the transmission line105to which the complete HVTLAD100is attached through a clamp110or other attachment means which makes electrical and mechanical contact with the transmission line105. Variations of the clamp110as depicted in theFIGS. 2,3and8, may be required for affixing the HVTLAD100to varying transmission line cable sizes and configurations including single, dual, and quad high voltage line configurations. A curved feature114of the conductive support tube107allows positioning of the HVTLAD100directly over and centered on the transmission line105wire (s) in order to reduce the rotational torque applied by the clamp110.

Referring now toFIG. 3, the electric field energy source102further includes a power supply module108mounted to the conductive support tube107within the conductive sphere106. Input connection to the power supply module is provided through wire connection112made to the galvanically isolated conductive sphere106and a second wire connection109made to the conductive support tube107that allows the power supply module to be coupled to the transmission line105through the conductive support tube107and clamp1110. The power supply module108common or effective “ground” connection is made through the second wire connection109. The positive DC output is provided to a multi-conductor wire cable1111that is routed through the conductive support tube107to the electronic obstruction light beacon module104. The multi-conductor wire cable111may additionally carry a serial communications link connection138between the power supply microcontroller U1130and the obstruction light controller150. The conductive support tube107provides the negative or circuit common “ground” return path through second wire connection109.

It will be appreciated that many modifications of the location of the various components in the HVTLAD100are possible without departing from the spirit and scope of the invention. For instance, in this example, power supply module108may be placed within electronic obstruction light beacon module104with appropriate wire connection(s) to conductive sphere106through conductive support tube107.

Two examples of the power supply module108b,108cwithin the conductive sphere106are presented. The first embodiment utilizes a magnetically coupled technique while the second embodiment employs a switch-mode flyback topology. In both examples, the power supply module108functions to convert the low level capacitive reactive AC current flowing between the high voltage transmission line105and the galvanically isolated conductive sphere106into a low voltage +12 Vdc supply voltage45of higher current capability suitable for powering the electronic obstruction light beacon module104and power supply module108electronics. The power supply module108may provide +12 Vdc with a continuous power level of 1.3 watts when connected to a 230 kV ac transmission line. Higher line voltages result in increased power availability. A 740 kV ac transmission line may produce in excess of 4 watts of continuous power availability when utilizing a conductive sphere106of 1 meter in diameter having a free space capacitance of approximately 50 pF as defined by equation:
C=4·π·Eo·r,where C=capacitance in Farads, Eo=8.85×10−12C2/(N*m2), and r=the radius of the sphere in meters.

Referring now toFIG. 4, a second example of the power supply module108bis shown. Transformer T136has a primary connection with Np turns connected between the conductive support tube107and the galvanically isolated conductive sphere106. It is appreciated that the conductive support tube107is additionally galvanically coupled to the transmission line105through a clamp110. A small AC primary current Ip37flows through the primary winding into the conductive sphere106as the result of the total body or “free space” capacitance of the conductive sphere106and the high voltage transmission line105potential. A typical high AC line voltage value ranges from 10 kV to over 1000 kVac with a typical transmission line value used for this discussion being 230 kVac line to line or 132.8 kVac line to neutral (earth) potential. The conductive sphere106capacitance at transmission line heights is in the picofarad range with a typical value for this discussion being approximately 50 pF for a conductive sphere106of three feet in diameter. The limiting lower value of “free space” capacitance for a conductive sphere is provided by the equation shown above with capacitance being proportional to the radius of the conductive sphere. The conductive sphere106capacitance, as “seen” by the transmission line105and the connected and energized conductive support tube107, has a lower “free space” limit established by the equation, but is also affected by the height above the earth ground plane and the proximity of other conductors such as towers and other transmission conductors.

It is important to note that the exact capacitance of the conductive sphere106is not particularly important provided that it is high enough to establish a sufficient operating primary current Ip37and that the reflected load impedance as presented at the primary winding of transformer T136, due to power supply loading, is of high enough value to allow sufficient voltage division across the primary winding of transformer T136winding and conductive sphere106effective capacitance series connection. Higher or lower power levels may simply be achieved by adjusting the size and therefore capacitance, of the conductive sphere106.

The electric field energy source102body geometry is not limited to spherical shapes but may include other geometries such as toroidal, cylindrical and planar topologies or combinations thereof. InFIG. 2, the electric field energy source102is shown hanging below the transmission line105wire(s) but may also be located in other positions or electrically combined in parallel with other conductive bodies in order to increase total body capacitance and power generation capability. The electric field energy source102may also be of tubular shape, positioned coaxially either completely or partially around but insulated from the transmission line105wire(s) as shown inFIG. 1. The selection of the geometry of the electric field energy source102at high transmission line potentials is normally be influenced more by attempting to prevent corona discharge and radio interference through the use of sufficient radii of curvature in order to reduce electric field intensities to non-ionizing levels. A three foot diameter conductive sphere106mounted below the catenary transmission line wire(s) as shown inFIG. 2may provide sufficient capacitance and corona rejection for up to 500 kV line to line potentials while additionally providing a passive visual Federal Aviation Administration painted (orange and white) obstruction marker.

The magnitude of primary current Ip37is determined by the transmission line voltage applied to the conductive support tube107and the reactive impedance provided by the total body capacitance on the conductive sphere106at the particular line frequency (typically 50 or 60 Hz) employed. For illustrative purposes, a body capacitance of 50 pF translates to a reactive impedance of −j53 Megohms at 60 Hz. This results in a reactive primary current Ip21of 132.8 kVac/−j53e6 equaling j2.5 mA RMS. The potential difference developed across the primary winding of transformer T136is small in relation to the conductive support tube107potential (>132 kVac) and therefore may be neglected in the estimation of primary current Ip37flow. The potential difference developed across the primary winding of transformer T136(and thus the potential between the conductive sphere106and the rest of the body of the HVTLAD100) is kept small in relation to the transmission line105potential due to the clamping action of an active device such as Zener diodes D1and D241as described below.

In order to reduce primary magnetization current to a level significantly below the available driving primary current lip37it may be necessary to use a transformer T136incorporating a tape wound toroidal design employing low-loss magnetic core material to achieve useable transformer action. Conventional silicon-steel power transformers suffer from core losses that may result in magnetization current well above the available driving primary current Ip37source. A representative transformer may be wound on a Magnetics Incorporated 50100-4F Supermalloy™ toroidal tape wound core. Other low loss core materials; such as MetGlas™ and Permalloy™ may be used, particularly at higher transmission line voltages which translate into higher driving primary current Ip37levels. Transformer T136functions in the step down configuration where the ratio of Np/Ns is greater than 1. As an example, a turns ratio of 80, with 10,000 primary turns and 125 secondary turns, may used but it is appreciated that other turns ratios may be employed to obtain different output voltage levels and current levels. A high number of primary turns is employed on the primary winding of transformer T136in order to simultaneously support a high primary voltage, a flux level optimized for low core loss, and a small magnetic core cross section.

Primary current Ip37induces a secondary current Is40that is rectified through diode bridge DB142and charges capacitor C144. The negative output of diode bridge DB142is connected to system ground43, which is galvanically bonded to the conductive support tube107through second wire connection109. This forms the “system” ground for all electronic circuitry in both the power supply module108band electronic obstruction light beacon module104. In this manner the conductive support tube107maintains a voltage differential with respect to the conductive sphere106equal to the primary winding voltage developed across transformer T136. Capacitor C144voltage builds up to a level of +12.7 Vdc, at which point the secondary 12 Volt Zener diodes D1and D241clamp the secondary AC voltage to provide shunt regulation of the +12 Vdc supply voltage45. The Zener diode clamping action limits transformer T136secondary AC voltage to approximately 12.7 volts peak-to-peak of clipped sinusoidal waveshape. Transformer T136, through turns ratio Np/Ns transforms the clamped secondary voltage to approximately 1016 volts peak-to-peak across the primary winding. In this manner the high primary voltage of transformer T136, combined with low primary current Ip37, through transformer action, is converted to a lower secondary voltage at higher secondary current Is 40 levels operable to power additional power supply module108band electronic obstruction light beacon module104electronics. Zener diodes D1and D241are of the power variety as they must be able to dissipate the full power supply output when the power supply module108bis unloaded. Diode Bridge DB142utilizes Schottky diodes in order to minimize diode potential drops and maximize system efficiency. A Gas Discharge Tube50may be provided to limit the primary voltage of transformer T136under transient line conditions due to possible lightning strikes or other short duration line events. Alternatively other types of transient suppression devices may be used. It is appreciated that other power supply configurations are possible including using different turns ratios, clamping voltages means, multiple secondary output windings and configurations and various other component substitutions without departing from the spirit of the invention.

The remaining power supply module108bcircuitry is provided for storage of energy and communication of energy data to the electronic obstruction light beacon module104. The +12 Vdc supply voltage45is reduced to 5 Vdc through regulator127to power microcontroller U1130having internal RAM, ROM, A/D, Digital I/O, and communications ports. Diode D3and1Farad (or other value) capacitor C2128provide the microcontroller U1130with +12 Vdc supply voltage45outage “ride-through” capability allowing continuous control operation during load fault and transient events associated with high energy capacitor bank132and battery135charging. A Hall effect or other DC current sensor129provides power supply current data to microcontroller U1130. Resistive divider R1and R2131divides the +12 Vdc supply voltage45providing voltage level information to the A/D input channel of microcontroller U1130. The power supply module108bis additionally provided with a backup battery135, charge control133and activation switch136all operating under microcontroller U1130management. The backup battery135provides continuous electronic obstruction light beacon module104power under conditions of transmission line 105 voltage sag or failure. Alternatively a super capacitor or other energy storage device may be used instead of backup battery135.

The power supply module108bmay additionally include a high energy capacitor bank132having a combined total capacitance of 8.3 Farads which translates into 600 joules of energy storage at the supply level of +12 Vdc supply voltage45. This high level of energy storage can be used for short term backup power in the event of transmission line 105 voltage sag or failure. The low impedance level afforded by the high energy capacitor bank132additionally provides high peak power reservoir capacity suited for intermittent (such as required for a flashing LED beacon array) high peak energy demand applications. Capacitors having values in the 0.1 to 50 Farad range combined with low effective series resistance suitable for high energy discharge rates are a relatively new technology. Representative types include the Cooper Industries Aerogel™ 50 Farad, 2.5 volt capacitor, part number B1840-2R5506 and, for even higher energy storage, the Maxwell Technologies BCAP0013 450 Farad, 2.5 volt capacitor.

Microcontroller U1130provides charge control of the high-energy capacitor bank132through field effect transistor (“FET”) switches Q1, Q2, and Q3of FET bank134. When not charged, the high-energy capacitor bank132may appear as a low impedance short circuit which may require controlled charging particularly when the driving +12 Vdc supply voltage45has limited current capability. Microcontroller U1,130through current (by DC current sensor129) and voltage (by resistive divider R1and R2131) measurement determines, in real time, the available supply current that may be safely directed to charging the high-energy capacitor bank132without causing a significant voltage loss in +12 Vdc supply voltage45or detrimental transient condition. Resistors R3and R4140, through FET switches Q1and Q2of FET bank134provide a means of variable rate charging depending on the calculated available supply current. FET switch Q3of FET bank134is turned on after the high-energy capacitor bank is fully charged effectively placing a low impedance between capacitor bank132and system ground43. Capacitor bank is then capable of providing short term high peak power capability. A serial communications link138is provided to allow energy data and control information to be passed between the power supply module microcontroller U1130and the obstruction light microcontroller U2171(FIG. 6). Battery135charge information, supply current (measured by DC current sensor129), +12 Vdc supply voltage45, and supply module temperature from temperature sensor141may be transmitted via the RF data link transceiver69to a remote location for alarm and diagnostic purposes. Detection of transmission line 105 voltage failure is also possible by monitoring Isense supply current (through DC current sensor129). If it drops to zero or reverses direction as the result of powering current for the microcontroller U1130flowing from the energy storage means instead of the transformer T136then a transmission voltage failure is indicated and this status may be forwarded via the RF data link transceiver69.

Referring now toFIG. 5, a third example of the power supply module108cis shown. A small AC primary current Ip37flows through diode bridge rectifier DB2150charging capacitor C3151. AC primary current Ip37flows as the result of the total body or “free space” capacitance of the galvancially isolated conductive sphere106and the high voltage transmission line105potential in a manner similar to that detailed in the previous examples of the power supply module108. The DC voltage developed across capacitor C3151increases to approximately +1000 Vdc on high voltage dc supply153at which time high voltage Zener diodes D4and D5152clamp the AC input voltage effectively limiting the maximum dc switch-mode supply input voltage to +1000 Vdc. The potential difference developed across the high voltage Zener diodes D4and D5152(and thus the potential between the conductive sphere106and the rest of the body of the HVTLAD100) is kept small in relation to the transmission line105potential due to the clamping action of the high voltage Zener diodes D4and D5152.

Bootstrap circuitry154initially provides startup power for the switch-mode controller155, reverting to a high impedance state after transformer switching action successfully begins providing low voltage output163. MOSFET Q4is initially biased into conduction through a positive gate to source potential provided by Zener diode D6and resistor R6. Switch-mode controller155supply filter capacitor C4156is charged through Q4and R5until a low voltage threshold is reached at which point the switch-mode controller155begins switching action. Capacitor C4156stores energy to provide sufficient startup time until switch-mode action provides operating voltage through the auxiliary power winding157of flyback transformer T2158and rectifier D7159.

After a finite start-up time the low voltage output163stabilizes and switch-mode controller155pulls the gate voltage of MOSFET Q4low which effectively removes the bootstrap circuitry154from loading the high voltage dc supply153line. Resistor R6remains in circuit but is of high value as to limit power consumption. The topology shown is representative of the flyback switch-mode method of dc-to-dc conversion. High voltage MOSFET Q5160is turned fully on or off at a high switching frequency (greater than 10 KHz) in response to voltage and current feedback signals in order to regulate the +12 Vdc supply voltage45. Flyback transformer T2158primary winding161is switched directly across the high voltage input when high voltage MOSFET Q5160is turned on. Current linearly ramps up in the primary winding storing an amount of magnetic energy per cycle defined by the equation: E=½·Lp·Ipk2, where Lp is the primary inductance and Ipk is the peak primary current.

When high voltage MOSFET Q5160is turned off, the secondary windings (auxiliary power winding157and secondary winding162) commutate or “flyback” and return the stored energy into filter capacitor C4156and capacitor C144through rectifiers D7and D6168, respectively. This switch-mode action repeats at a high frequency, which allows the use of small, and inexpensive low loss ferrite cores for flyback transformer T2158. Switching action is regulated on a cycle-by-cycle basis with control provided by the switch-mode controller155such that the +12 Vdc supply voltage45is maintained at a constant value. Switching action control, on a cycle-by-cycle basis, is provided by comparing the feedback line164to an internal reference combined with monitoring of Ipk165. If the feedback line164exceeds the internal threshold then switching action is terminated. Feedback is provided by auxiliary power winding157rectified output. Switching action is also terminated on a cycle-by-cycle basis if Ipk165of primary winding161exceeds a preset level resulting from the voltage developed across resistor R7166. A snubber RC diode network167is provided to reduce transformer T2primary winding 161 voltage switching peaks in order to prevent damage of high voltage MOSFET Q5160. The described switch-mode power supply represents the “flyback” topology. It is appreciated that other switch-mode topologies may be employed to reduce the high dc voltage supply153down to a lower +12 Vdc supply voltage45compatible with solid-state electronics including forward mode buck, push-pull, half-bridge, and full bridge conversion. The remaining power supply module108ccircuitry including microcontroller, energy storage, and communications means functions similarly as previously described in the second example of the power supply module108b.

Referring now toFIG. 6, the electronic obstruction light beacon module104is shown. The electronic obstruction light beacon module104electronics are housed in a conductive metallic enclosure176, which is galvanically and mechanically coupled to the conductive support tube107and bonded181to system ground43. Power for the electronic obstruction light beacon module104is provided by the power supply module108through multi-conductor wire cable111. Multi-conductor wire cable111is routed through the conductive support tube107. The low voltage +12 Vdc supply voltage45provides power for the electronic obstruction light beacon module104. Microcontroller U2171operates on +5 Vdc derived from the +12 Vdc supply voltage45and a 5V regulator180. This allows continued operation under decreasing +12 Vdc supply voltage45levels as the result of transmission line105voltage loss. Note that the +12 Vdc supply voltage45level is maintained by the high energy capacitor bank132and/or battery135combination under conditions of transmission line105loss. It is appreciated that, under conditions of transmission line105loss, the +12 Vdc supply voltage45level decays at a rate determined by the effective load impedance and energy capacity of the high energy capacitor bank132and/or battery135combination.

A series string of light emitting diodes (LEDs)182provides a high intensity, long life, solid-state light source, the output of which may be optically diffused through the employment of a polycarbonate lens system170. Alternatively other types of light emitting devices such as incandescent lamps, fluorescent lamps, etc. may be used. The polycarbonate lens system distributes the light substantially uniformly about approximately 360 degrees in azimuth and 90 degrees in elevation (from horizontal) in order to provide aeronautical visibility from all approach vectors. The series configuration of LEDs182is used to provide matched individual LED current which translates to uniform individual LED brightness. The series LEDs182are shown having five individual LEDs182in each bank. It is appreciated that configurations having more or less LEDs182can easily be accommodated through adjustment of the driving potential source levels. Two similar, high efficiency switch-mode constant current boost converters183are utilized to drive each string of series LEDs182with output drive184controlled in an on-off fashion through digital output185of micro-controller U2171. Resistors R8and R9186provide micro-controller U2171with an analog signal representative of the individual current in each string of series LEDs182which in turn provides an indication of LED functionality for diagnostic and alarm purposes. Having two separate LED light sources provides a degree of redundancy should an individual string of series LEDs182or constant current boost converter183fail.

An ambient light sensor177provides micro-controller U2171with ambient light condition data in order to make programmed light flash and intensity visibility adjustments.

A GPS receiver module173combined with GPS antenna172provides accurate time-of-day information through a serial data channel199to micro-controller U2171. This information may be used by micro-controller U2171to accurately time synchronize flashing of multiple electronic obstruction light beacon modules104in order to provide enhanced visibility of a lighted transmission line section. Time-of-day synchronization may also be used to vary flash patterns and/or intensities to accommodate day or night conditions. The GPS receiver module173may also provide an accurate high frequency clock193to the micro-controller U2171. This may be used as the operating clock for the micro-controller U2171. Alternatively, other types of time synchronization reception circuitry may be utilized to provide a time based to micro-controller U2171for flash synchronization.

RF data link transceiver69, combined with antenna76, provides a full duplex communications link between the micro-controller U2171and a control/monitoring station or other obstruction light(s). RF data link transceiver69may, for example, be a 900 MHz secure data transceiver. This communications link provides a means of remote alarm and diagnostic monitoring combined with program upload capability. It additionally provides for communications between multiple electronic obstruction light beacon modules104for flash synchronization purposes.

Flash time synchronization of multiple obstruction lights may be completely user specified in order to allow unique simultaneous or sequential strobe flashing combined with individually programmed flash rates and duty-cycles.

High pass filter elements189and190function to protect the input circuitry of the GPS receiver module173and RF data link transceiver69from DC and low frequency signals (such as 50 or 60 Hz) that may arise due to the high electric field potentials that exist in the proximity of the antenna elements. Low frequency and DC components are effectively “shunted” to the conductive metallic enclosure176, which in turn is connected to the system ground43while allowing the desired on channel frequency components to pass with little attenuation. The high pass filter elements189and190may utilize passive inductive, capacitive, and transmission line components.

Conductive toroidal ring191(FIG. 2) functions to reduce and displace the electric field intensities about the conductive metallic enclosure176and peripheral attachments including the GPS antenna172, antenna76, polycarbonate lens system170, and ambient light sensor177.

Referring now toFIG. 7, another example of the HVTLAD100is shown. This example includes a measurement module750and a current sensor805. The current sensor may be an active CT, a passive CT, a Rogowski coil, an optical CT, a Hall effect device, etc. The current sensor805senses the current flowing in a high voltage current carrying conductor810(such as a transmission line). The measurement module750includes electronics for measuring parameters such as voltage, current and temperature. This example of the HVTLAD100includes additional components described previously with respect to other examples of the HVTLAD100.

Referring now toFIG. 8, a combination electrical/mechanical block diagram of the measurement module750is shown. Some elements of the measurement module750are similar to those of the electronic obstruction light beacon module104therefore only differences are described hereafter.

The measurement module750includes a metallic (or other conductive material) plate740which is insulated by insulators735from the conductive metallic enclosure176. In the illustrated example, the metallic plate740is in the form of a dome, although this is not necessary. A first inherent capacitance710is formed between the metallic plate740and the conductive metallic enclosure176. A second inherent capacitance705is formed between the metallic plate740and the environment in a similar fashion as the conductive sphere106described previously. Resistor R20720is connected to the metallic plate740and in conjunction with resistor R21715forms a resistive divider capable of feeding an analog signal indicative of the voltage on metallic plate740to amplification circuitry730. Amplification circuitry730feeds a scaled version of this voltage to an A/D input of microcontroller U2171. This voltage is indicative of the voltage on high voltage current carrying conductor810due to the fact that inherent capacitances705and710form a capacitive divider between the conductive metallic enclosure176and an external reference such as ground or another phase conductor. Metallic (or other conductive material) electric field shields755in contact with conductive metallic enclosure176may be provided to shield the metallic plate740from stray electric fields.

Signal(s) indicative of current in the high voltage current carrying conductor are fed from the current sensor805to the amplification circuitry725through line745which passes through multi-conductor wire cable111. The output of amplification circuitry725is fed to an A/D input of microcontroller U2171.

Microcontroller U2171samples the signals from amplification circuitry725and730. These signals are indicative of voltage and current in the high voltage current carrying conductor810. The microcontroller U2171may timestamp these samples using time indications received from GPS receiver module173and transmit the timestamped signals to a receiving device through RF data link transceiver69. In addition, microcontroller U2171may make power calculations directly using the samples and transmit the results of these calculations through RF data link transceiver69. Some of the results of the power calculations may include power parameters such as rms current, rms voltage, watts, VARs, VAs, frequency, harmonics, phasors, etc.

During initialization, the microcontroller may also transmit appropriate calibration constants through RF data link transceiver69to a receiving device. This is so the receiving device can make accurate power calculations based on the samples if the samples are not individually calibrated by microcontroller U2171.

Referring now toFIG. 9an example grid stability monitoring system incorporating the HVTLAD100is shown. Various transmission lines905form a portion of an electric grid900. As known in the art, the remainder of the grid910consists of many transmission lines, distribution lines, transformers, substations, generators, loads and other electrical equipment (not shown). The transmission lines905serve to interconnect various parts of the grid. Various HVTLADs100are installed on the different transmission lines905and at different points on the same transmission lines905. The HVTLADs100transmit voltage and/or current information to local receiving stations920over wireless links921. The local receiving stations920in turn communicate at least one of voltage, voltage phase information, current, current phase information, power, frequency, etc. to a monitoring station930over communication links931.

A number of factors may be considered when analyzing the stability of an electrical grid. One factor is voltage. In general, the closer the voltage at every given point in the grid is to the expected nominal voltage, the more stable the grid is. A second factor is voltage phase. In general, it is desirable to keep the relative voltage phase of all points in the transmission grid to within about 60-70 degrees of one another. In addition, if a discontinuity in voltage phase is detected, this may be an indication of grid instability. A third factor is frequency. In general, the closer the frequency at a given point in the transmission grid is to other points within the grid, the more stable the grid is. In the system shown inFIG. 9, due to the fact that the monitoring station930can receive at least one of these indications from the various HVTLADs100and these indications are accurately timestamped or time synchronized as described above, grid stability can be analyzed by either a user or a computer system within the monitoring station930. This may be done by display of the information from the HVTLADs100on a display in the monitoring station930and/or analysis within the computer system. An indication of grid stability is thus attained and if the grid is not sufficiently stable, mitigation activities can either manually or automatically be undertaken. As described above, each HVTLAD100may have a GPS receiver module173which provides position information. Alternatively, the HVTLAD100may have another type of RF based positioning and/or time synchronization receiver. By correlating this position information with information on where particular elements of the electrical grid900are located, the installation location of any given HVTLAD100may be determined without having to record the position of the HVTLAD100during installation. In addition, with position information from multiple HVTLADs100in the grid, a map of the grid including, the voltage, current, frequency, phase, etc. can be developed and/or displayed in the monitoring station930. The monitoring station930may not necessarily be operated by the same company or entity that owns the transmission grid itself.

Multiple HVTLADs100on a transmission line905may also be used for fault detection and/or location. Using the voltage and current samples taken by each HVTLAD100, the HVTLAD100, local receiving stations920or monitoring station930can calculate the impedance of the line seen by the HVTLAD100at each point on the transmission line905. This information can be used to triangulate the location of a fault or determine that power is flowing through an unexpected path. Alternatively, or in addition, analysis of the waveforms of voltage and or current seen by each HVTLAD100can be used for fault detection and/or location.

Having multiple HVTLADs100at various points on the transmission lines905of the electric grid900allows for the detection of congestion in the electrical grid900. For instance if a transmission line905is nearing its capacity, the price charged for use of that transmission line905by a producer or consumer of electricity may be increased. Alternatively or in addition, this information may be used to reroute power flow through a different path in the electrical grid. In a similar manner, if electricity flow is below the capacity of a given transmission line905by a given amount, the price charged for use of that transmission line905may be decreased or additional flow may be routed to that transmission line905. This functionality may be particularly valuable in a deregulated utility environment where the owners of the transmission lines905may not be the same as the owners of the generation facilities connected to the transmission lines905.

The antenna76on the HVTLAD100and/or the antenna in the local receiving stations920may be of directional type to reduce the likelihood of interference or tampering with the RF link between the two. A directional antenna focuses radio frequency energy emanating from said radio frequency transmitter. In addition, the shape of the HVTLAD100and/or position of corona rings30,191of the HVTLAD may also serve to shield antenna76from extraneous RF energy and prevent RF energy from the antenna76from propagating in certain directions.

It will be appreciated that although a few examples of the invention incorporating the power supply module108have been presented and described, many more examples of HVTLAD100devices are possible. The following sections discuss additional examples that have been conceived.

Mesh Network

A mesh network can be formed by mounting multiple HVTLADs100along a transmission line and on different transmission lines within appropriate proximity. Each HVTLAD100has an RF data link transceiver69which can communicate with adjacent HVTLADs100. With appropriate gateways to other networks, such as the Internet or an intranet, the HVTLADs100may provide for communication links across geography which may not already have such links.

Drone

By mounting appropriate mechanical and/or robotic hardware to the HVTLAD100, the HVTLAD100may be made operative to traverse the power line. For example, powered wheels may be mounted to the HVTLAD100and the HVTLAD100may no longer be clamped to the power line. The wheels may be appropriately attached to the power line and using the power provided by power supply module108, electric motor(s) may be driven to move the HVTLAD100along the power line. The drone HVTLAD100may be equipped with a video camera and thus be used to traverse the power line looking for faults in the line, insulators, towers, etc. or for general video surveillance. The drone HVTLAD100may also or alternatively be equipped with a vibrating motor, electronically driven hammer, etc. operative to vibrate or impact the power line at a given point in order to dislodge ice.

Display

The HVTLAD100may be equipped with a display such as an LED, LCD, etc. The display may be powered from the power supply module108. The display may be used to display advertising to persons near the HVTLAD100. Other displays include highway information signs, “Amber” alert messages etc. The display functionality of the HVTLAD100may be combined with the drone functionality to create a moving display.

Other Power Sources

Complementing the power supply module108, the HVTLAD100may have complimentary power sources such as solar panels, wind turbines, etc. When additional power is available from these sources, additional functionality of the HVTLAD100may be enabled.

In addition to the GPS receiver, the HVTLAD100may comprise additional satellite communication transceivers. In addition or alternatively, the HVTLAD100may comprise a power line carrier transceiver. These may enable the transmission or reception of sensor or other data (such as advertising content or drone movement directions).

Radar Warning

The HVTLAD100may comprise a transmitter or transceiver operative to trigger an aircraft's radar. This may be useful when fog or other obstructions prevent the pilot of the aircraft from seeing the light emitted by the HVTLAD100. In addition, the HVTLAD100may transmit warning tones on various RF frequencies for the same purpose.

Analog Radio

Although as described above, data indicative of voltage, current, power, etc. may be transmitted in digital form, this data may also be transmitted in analog form from the HVTLAD100to a local receiving station920.

Fiber Repeater

In new installations, it is common that transmission lines have fiber optic cables within them. The HVTLAD100may be used as a fiber optic repeater. The fiber optic signal may enter the HVTLAD100within the transmission conductor10as shown inFIG. 1and be amplified by appropriate circuitry within the HVTLAD before exiting the HVTLAD100.

Additional Sensors

The HVTLAD100may alternatively or in addition be supplied with other sensors. A first example of an additional sensor is a temperature sensor operative to determine the temperature of the power line. This sensor may use infrared technology and may provide an indication of overheating of the power line. A second example of an additional sensor is a vibration or acceleration sensor. This sensor may provide an indication of stress on the power line from wind, ice, earthquake, impact, etc. A third example of an additional sensor is strain or tension sensor operative to sense the tension within the power line. This may also be an indication of stress on the power line. A fourth example of an additional sensor is a humidity sensor. Humidity may be used as a parameter in determining the current carrying capacity of the power line. A fifth example of an additional sensor is an air quality sensor. This sensor may be used generally to provide information to a remote site or may be used in estimating the affect of air impurities on the power line (due to corrosion, etc.). A sixth example of an additional sensor is a sound sensor. This sensor may be used to provide information to a remote site of local sound level. A seventh example of an additional sensor is an atmospheric pressure sensor operative to provide such information to a remote site for various purposes.