Synchronized electric meter having an atomic clock

Smart electric meters configured to perform fast, time-synchronized electrical energy measurements at the consumer-level are disclosed herein. In some embodiments, a smart electric meter includes circuitry configured to measure an electrical value at a location of an end user in a power system. The smart electric meter can further include an atomic clock configured to output a timing signal, and a controller configured to receive (a) the measured electrical value from the circuitry and (b) the timing signal from the atomic clock. The controller can further (a) process the electrical value to generate meter data and (b) generate a time tag based on the timing signal. Then, the controller can associate the time tag with the meter data to generate time-tagged meter data.

TECHNICAL FIELD

The present technology generally relates to a smart electric meter having an atomic clock for time synchronizing meter data.

BACKGROUND

An electric meter is a device that measures the amount of electrical energy consumed by residential, commercial, or industrial customers. Traditional electric meters are installed at customers' premises for billing purposes. To obtain the data recorded by such traditional electric meters, a technician must visit the physical location of the electric meter. Such traditional electric meters are gradually being replaced by “smart” electric meters, which can measure electrical energy consumption and also communicate that information between the meter and a central system for billing and monitoring. For example, the U.S. Energy Information Administration reported in December 2017 that almost half of all U.S. electricity customer accounts have smart meters.

In addition to billing and monitoring, it is expected that smart meter data will be increasingly utilized in the management of distributed energy resources (e.g., photovoltaic cells) and controllable loads (e.g., smart consumer appliances). However, current consumer-level smart electric meters record data with large time intervals (e.g., record hourly and report daily) and low quality (e.g., including data incompleteness and loss), bringing significant constraints to their utilization for monitoring and control.

Some distribution and transmission substations on the electric grid include phasor measurement units (PMUs) that allow for higher-precision electrical energy sampling. However, PMUs rely on the Global Positioning System (GPS) to time synchronize electrical phasor measurements. Such GPS-based measurement devices require a connection with a GPS antenna and are susceptible to random GPS loss and cyber-attacks.

DETAILED DESCRIPTION

The present technology is generally directed to electric meters configured to (i) continuously measure electrical quantiles such as voltage, current, power, etc., at the location of an end user in a power system, (ii) calculate meter readings based on the measured electrical quantities, and (iii) time-stamp/tag the meter readings to time synchronize the meter readings. In some embodiments, an electric meter configured in accordance with the present technology can include an atomic clock configured to provide a precise timing signal for use in time-stamping the meter readings. In some embodiments, the atomic clock can be a chip-scale atomic clock that is ultra-low power, compact in size, and low noise. In some embodiments, a plurality of the electric meters can be distributed within a power system (e.g., a grid power system) to provide a synchronized real-time indication of electrical quantities across the power system.

In one aspect of the present technology, the electric meter is configured to time synchronize measured electrical values based on a timing signal from the atomic clock rather than from a conventional GPS-based timing signal. Accordingly, the electric meter need not include a GPS antenna or corresponding wiring as in conventional smart electric meters. This arrangement can improve (i) the ease of installation, (ii) the maintainability, and (iii) the simplicity of the electric meter as compared to conventional electric meters. For example, the electric meter need not be installed in a location that has an unobstructed view of GPS satellites. Moreover, the electric meter can be more stable/reliable as it is not susceptible to random GPS loss or GPS cyber-attacks—which can seriously impact the time synchronization and measurement accuracy of conventional GPS-based devices.

Specific details of several embodiments of the present technology are described herein with reference toFIGS. 1-3. However, the present technology may be practiced without some of these specific details. In some instances, well-known structures and techniques often associated with electric power systems, electric meters, voltage/power calculations, etc., have not been shown/described in detail so as not to obscure the present technology. The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific embodiments of the disclosure. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section.

FIG. 1is a block diagram of a smart electric meter100configured in accordance with some embodiments of the present technology. The electric meter100can be installed at the location of an end user in a power system (e.g., grid power system) such as a residential home, apartment building, individual apartment or unit within the apartment building, housing complex (e.g., small house community), individual house in the housing complex, commercial building, industrial building, etc., and is configured to measure electrical quantities/values such as voltage, current, power, etc. In general, the electric meter100is configured to perform fast time-synchronized electrical energy measurements at the consumer-level. As such, the electric meter100can be referred to as a time-synchronized electric meter.

The electric meter100includes circuitry101configured to measure current, voltage, and/or other electric quantities at the location of the end user in the power system. In the illustrated embodiment, the circuitry101includes one or more (i) transducers102, (ii) rectifiers104, and (iii) regulators106. In other embodiments, the circuitry101can include more or fewer electronic components for measuring electrical quantities and filtering, processing, and/or otherwise conditioning the measured values/signals.

In some embodiments, the transducers102can include voltage transducers and current transducers that measure utility voltage and current values, respectively. More specifically, the transducers102can be configured to receive and sample high-power analog signals120(e.g., voltage and current signals) and to output lower-power analog signals121. In the illustrated embodiment, the rectifiers104receive the lower-power analog signals121from the transducers102and convert the lower-power analog signals121to digital signals. In some embodiments, the rectifiers104are further configured to filter out certain harmonics of the analog signals121. Accordingly, the rectifiers104can output filtered, digital signals122. In the illustrated embodiment, the regulators106receive the filtered digital signals122and are configured to (i) regulate the filtered digital signals122to standard digital signals123(e.g., 3.5 volt voltage signals, 5.0 volt voltage signals, etc.), and (ii) output the standard digital signals123to a controller110(e.g., a microcontroller). The controller110is configured to calculate meter data (e.g., meter readings) based on the pre-processed digital signals123. In some embodiments, the meter data includes one or more of real power, reactive power, power factor, and voltage root mean square (RMS).

In the illustrated embodiment, the electric meter100further includes an atomic clock108configured to generate a timing signal124and to output the timing signal124to the controller110. The timing signal124can be a pulse per second (PPS) signal. In some embodiments, the atomic clock108can be a chip scale atomic clock (CSAC) that keeps time based on the precise electromagnetic radiation (e.g., microwaves) emitted by electron spin transitions between two hyperfine energy levels in atoms (e.g., cesium atoms). Accordingly, the atomic clock108can provide the timing signal124independently and with high precision and stability. For example, time drift of the atomic clock108can be about900nanoseconds per day—equivalent to 3 milliseconds per 10 years—which allows the electric meter100to perform high-precision and time-synchronized measurements over a typical life span of the electric meter100(e.g., 10-15 years). In some embodiments, the atomic clock108can be relatively compact. For example, the atomic clock108can have a volume of less than about 17 cubic centimeters and a weight of less than about 35 grams. Moreover, in contrast to global positioning system (GPS) based time sources, the atomic clock108can provide the timing signal124without requiring an antenna and the associated cables for accessing an external GPS time signal. Moreover, the atomic clock108can operate at low power and low noise.

The controller110is configured to receive the timing signals124and to synchronize the meter readings based on the timing signals124. For example, the controller110can generate time tags at a specific sampling frequency (64 per second, 128 per second, etc.) and associate the time tags with the calculated meter data (e.g., “time-stamp”) the meter data. More particularly,FIG. 2is a schematic diagram illustrating the timing signal124and a signal228representing the calculated meter data in accordance with some embodiments of the present technology. In the illustrated embodiment, the timing signal124is a PPS signal having a plurality of sharply rising or abruptly falling edges229(“rising/falling edges229”). Referring toFIGS. 1 and 2together, the controller110can generate time tags for the signal228based on the rising/falling edges229of the timing signal124. In some embodiments, the form and/or mechanism of the timing signal124and the signal228can be based on, for example, an industry standard 2-wire bus protocol, such as an I2C protocol with acknowledge “ACK”.

Referring again toFIG. 1, the controller110can output (i) display signals125to a display112and (ii) time-tagged meter data signals126to a communication component114. The display112can be a liquid-crystal display (LCD) or other type of display and can be configured to receive the display signals125and to display the meter data thereon. The display112can display the meter data in real time, display aggregates of the meter data, historical meter data, etc. The time-tagged meter data signals126can include the measured meter data and the associated time tags. The communication component114is configured to receive the time-tagged meter data signals126and to convert the signals into frame data127(e.g., frames) according to a communication standard such as, for example, the American National Standards Institute (ANSI) standard C12.18 and/or the International Electrotechnical Commission (IEC) standard 61107. In some embodiments, the frame rate can be greater than about 64 frames per second, greater than about 128 frames per second, etc.

The communication component114is further configured to transfer the frame data127to a local or remote receiver, data concentrator, controller, etc., via a wired or wireless communication path.FIG. 3, for example, is a schematic diagram illustrating a portion of a power system330including a receiver332communicatively coupled to a plurality of the electric meters100(identified individually as electric meters100a-100n) configured in accordance with some embodiments of the present technology. Referring toFIGS. 1 and 3together, the electric meters100can each transmit the frame data127including time-synchronized measurements of electrical quantities local to the electric meters100to the receiver332. The receiver332can aggregate the frame data127and provide a real-time or near real-time measurement of electrical quantities across the power system330. By time-synchronizing the sampling processes for the electric meters100based on the precise timing signal124generated by each of the atomic clocks108, the receiver332can synchronize the measurements from each of the electric meters100—which may be widely geographically dispersed (e.g., hundreds of miles apart)—to provide a synchronized data set that captures the dynamics of the power system330. In some embodiments, the power system330can include one or more controllers that allow for near-real time or real-time control, monitoring, etc., of distributed energy resources (DERs), controllable loads (e.g., smart appliances), and/or other electric components based on the synchronized data set. Accordingly, the electric meters100of the present technology can provide near real-time or real time situational awareness of the power system330that enables improved monitoring and control of components within the power system330.

Referring again toFIG. 1, the electric meter100is configured to time synchronize measured electrical values based on the timing signal124from the atomic clock108rather than from a conventional GPS-based signal. Accordingly, the electric meter100need not include a GPS antenna or corresponding wiring as in conventional smart electric meters. In one aspect of the present technology, this improves (i) ease of installation, (ii) maintainability, and (iii) simplicity of the electric meter100as compared to conventional electric meters. For example, the electric meter100need not be installed in a location that has an unobstructed view of GPS satellites. Moreover, the electric meter100is more stable/reliable as it is not susceptible to random GPS loss or GPS cyber-attacks—which can seriously impact the time synchronization and measurement accuracy of conventional GPS-based devices. In another aspect of the present technology, the electric meter100can be efficiently integrated into existing systems as it can be compatible with existing meter standards, (e.g., ANSI C12.18 and IEC 61107), and is low-power, low-noise compact, and easy to install.

In some embodiments, the atomic clock108and/or the associated circuitry of the controller110can be embodied in a separate device (e.g., a “time synchronization module”) that can be communicatively coupled to an existing electric meter for providing time synchronization of the electrical values measured by the electric meter. Accordingly, in some embodiments the time synchronization module can be retrofit (e.g., in a “plug and play” configuration) with existing electric meters. For example, such a time synchronization module including the atomic clock108can receive measured electrical values from the electric meter and output time synchronized values, as described in detail above. In some embodiments, such a time synchronization module can be located at a position remote from the associated electric meter.

The computing systems (e.g., network nodes or collections of network nodes) on which the smart electric meters and the other described systems may be implemented may include a central processing unit, input devices, output devices (e.g., display devices and speakers), storage devices (e.g., memory and disk drives), network interfaces, graphics processing units, cellular radio link interfaces, global positioning system devices, and so on. The input devices may include keyboards, pointing devices, touch screens, gesture recognition devices (e.g., for air gestures), head and eye tracking devices, microphones for voice recognition, and so on. The computing systems may include high-performance computing systems, cloud-based servers, desktop computers, laptops, tablets, e-readers, personal digital assistants, smartphones, gaming devices, servers, and soon. For example, the simulations and training may be performed using a high-performance computing system, and the classifications may be performed by a tablet. The computing systems may access computer-readable media that include computer-readable storage media and data transmission media. The computer-readable storage media are tangible storage means that do not include a transitory, propagating signal. Examples of computer-readable storage media include memory such as primary memory, cache memory, and secondary memory (e.g., DVD) and other storage. The computer-readable storage media may have recorded on them or may be encoded with computer-executable instructions or logic that implements the smart meters and the other described systems. The data transmission media are used for transmitting data via transitory, propagating signals or carrier waves (e.g., electromagnetism) via a wired or wireless connection. The computing systems may include a secure cryptoprocessor as part of a central processing unit for generating and securely storing keys and for encrypting and decrypting data using the keys.

The smart electric meters and the other described systems may be described in the general context of computer-executable instructions, such as program modules and components, executed by one or more computers, processors, or other devices. Generally, program modules or components include routines, programs, objects, data structures, and so on that perform tasks or implement data types of the smart meters and the other described systems. Typically, the functionality of the program modules may be combined or distributed as desired in various examples. Aspects of the smart meters and the other described systems may be implemented in hardware using, for example, an application-specific integrated circuit (“ASIC”) and/or field programmable gate array (“FPGA”).

Several aspects of the present technology are set forth in the following examples:

1. An electric meter, comprising:circuitry configured to measure an electrical value at a location of an end user in a power system;an atomic clock configured to output a timing signal; anda controller configured to—receive (a) the measured electrical value from the circuitry and (b) the timing signal from the atomic clock;process the measured electrical value to generate meter data;generate a time tag based on the timing signal; andassociate the time tag with the meter data to generate time-tagged meter data.

2. The electric meter of example 1 wherein the atomic clock is a chip-scale atomic clock.

3. The electric meter of example 2 wherein the chip-scale atomic clock has a volume of less than about 17 cubic centimeters.

4. The electric meter of example 2 or example 3 wherein the chip-scale atomic clock has a weight of less than about 35 grams.

5. The electric meter of any one of examples 1-4 wherein the timing signal is a pulse per second signal.

6. The electric meter of any one of examples 1-5, further comprising a communication component communicatively coupled to the controller, wherein the communication component is configured to (a) receive the time-tagged meter data and (b) convert the time-tagged meter data into frame data according to a communication standard.

7. The electric meter of any of any one of examples 1-6 wherein the time-tagged meter data includes at least one of real power, reactive power, power factor, and voltage root mean square.

8. The electric meter of any one of examples 1-7 wherein the electric meter does not include a global positioning system (GPS) antenna.

9. The electric meter of example 8 wherein the electric meter does not receive a GPS timing signal.

10. The electric meter of any one of examples 1-9 wherein the circuitry includes—a transducer configured to convert high-power analog electrical signals into lower-power analog signals;a rectifier electrically coupled to the transducer and configured to receive the lower-power analog signals and to convert the lower-power analog signals to digital signals; anda regulator electrically coupled to the rectifier and configured to receive the digital signals and to regulate the digital signals to standard digital signals, wherein the controller is electrically coupled to the regulator and configured to receive the standard digital signals and to process the standard digital signals to generate the meter data.

11. The electric meter of any one of examples 1-10 wherein the timing signal has a plurality of rising and sharply falling edges.

12. A method of synchronizing readings of an electric meter, the method com prising:receiving an electrical value measured at an electric meter at a location of an end user in a power system;generating, via an atomic clock, a timing signal;processing the measured electrical value to generate meter data;generating a time tag based on the timing signal; andassociating the time tag with the meter data to generate time-tagged meter data.

13. The method of example 12 wherein the time tag is one a plurality of time tags, and wherein the method further comprises:continuously receiving the electrical value measured at the electric meter at the location of the end user;generating the time tags at a selected sampling frequency; andsuccessively associating the time tags with the meter data to generate the time-tagged meter data.

14. The method of example 13 wherein the method further comprises converting the time-tagged meter data into a plurality of data frames according to a communication standard.

15. The method of example 14 wherein the method further comprises transferring the data frames to a remote receiver via a communication path.

16. A system for monitoring a power system, comprising:a plurality of electric meters each positioned at a location of an end user in the power system, wherein individual ones of the electric meters include—circuitry configured to continuously measure an electrical value at the location of the respective one of the end users in the power system;an atomic clock configured to output a timing signal; anda controller configured to—receive (a) the measured electrical value from the circuitry and (b) the timing signal from the atomic clock;process the measured electrical value to generate meter data; andtime stamp the meter data based on the timing signal;a receiver communicatively coupled to the electric meters and positioned at a location remote from the electric meters, wherein the receiver is configured to—receive the time-stamped meter data from the electric meters; andgenerate a measurement of an electrical quantity across the power system.

17. The system of example 16 wherein the receiver is further configured to time-synchronize the time-stamped meter data received from the electric meters.

18. The system of example 16 or example 17 wherein individual ones of the electric meters do not include a global positioning system (GPS) and do not receive a GPS time signal.

19. The system of any one of examples 16-19, further comprising a controller communicatively coupled to (a) the receiver and (b) at least one load of the power system, wherein the controller is configured to control the at least one load, based on the measurement of the electrical quantity, to reduce an overall load of the power system.

20. The system of any one of examples 16-19, further comprising a controller communicatively coupled to (a) the receiver and (b) at least one energy source of the power system, wherein the controller is configured to control the at least one energy source, based on the measurement of the electrical quantity, to supply power to the power system.