Power generator and power generator auxiliary monitoring

A generator monitoring system and method includes a plurality of sensors (12) disposed within a generator enclosure (18) to sense health conditions of a generator (10) housed within the enclosure. The sensors are interconnected to provide a single communication path (14) for allowing communication with the plurality of sensors. A monitoring device (16) outside the generator enclosure receives health condition information from each of the plurality of sensors via the single communication path. A sensor may be disposed within the generator enclosure to detect particulates emitted from a monitored portion (e.g., 52) of the generator housed within the enclosure. A sensor may be disposed proximate a bus bar connection (130) of the generator to sense a health condition of the bus bar connection and generate corresponding health condition information provided to the monitoring device.

FIELD OF THE INVENTION

This invention relates generally to power generators, and, in particular, to monitoring conditions of the power generator and bus bar connections of the generator.

BACKGROUND OF THE INVENTION

Large power generators are monitored to detect health conditions of the generator to identify failures that may need to be remedied before the condition causes damage to the generator that may require considerable downtime to repair. For example, a generator part having an abnormally high temperature may be indicative of an incipient failure of the part. Thermocouples mounted at strategic locations on the generator have been used to monitor certain parts of the generator to detect abnormal temperatures. For example, generator stator bars may be cooled by internal channels conducting cooled pressurized hydrogen or water therethrough. Failures in a bar may be detected by monitoring a temperature differential of the pressurized hydrogen or water entering and exiting a channel, such as by disposing a thermocouple at the inlet and outlet of the channel.

Monitoring conditions of such generators may be complicated by the need to enclose the cooled generator within gas tight hermetic enclosures, such as in the case of hydrogen cooled generators. Complex particulate sensors, such as generator condition monitors (GCM) available from Environment One Corporation, mounted outside generator enclosures have been used to extract gas samples from within the enclosure to detect particulates within the gas indicative of a generator component experiencing abnormally high heating. For applications on air cooled generators, such systems typically include blower, vacuum pumps, switching valves, humidification system water supplies and filtering system and tend to be expensive and difficult to maintain.

DETAILED DESCRIPTION OF THE INVENTION

One of the challenges of monitoring generators and generator busses (in particular, hydrogen cooled generators housed in gas tight, hermetic enclosures) is the need to penetrate the enclosure with a communication link, such as wire or fiber optic, to provide communication with sensors disposed within the enclosure. However, each enclosure penetration may become a source of a sealing failure of the enclosure. Furthermore, the need to have numerous detectors mounted at strategic location relative to the generator may require routing of many separate wires throughout the generator and providing enclosure penetrations for each of the wires. For example, in a typical generator application, 24 to 48 wires connected to thermocouples must be routed through the generator and passed through the enclosure to a monitoring system outside the generator. The monitoring system must process each of the signals received from the thermocouples to determine if a failure condition of the generator is indicated relative to a location of the thermocouple. Monitoring of particulates in a cooling fluid flowing around an enclosed generator to determine presence of an overheating condition has proven to be expensive to implement. For example, multi-port collection systems that transport fluid samples to a single monitor, such as GCM system, typically blend the fluid samples together and thus require a highly sensitive detection system due to the dilution of the samples as a result of blending. The inventors of the present invention have developed an innovative monitoring system that overcomes these and other problems associated with conventional generator monitoring systems.

FIG. 1is a schematic cross sectional view of a power generator10including a plurality of sensors12having a single communication path14to a monitoring device16. One or more sensors12may be disposed within a generator enclosure18to sense a plurality of health conditions of the10generator housed within the enclosure18. In a hydrogen cooled embodiment, the enclosure18may include a cylindrical shape, while in the case of an air cooled generator, the enclosure18may include a “house” shape. The plurality of sensors12may be positioned at certain locations, such as spaced around stator end turns46, to monitor a condition of the generator10near the location. The sensors12may be interconnected to provide the single communication path14for allowing communication with the plurality of sensors12. The monitoring device16may reside outside the generator enclosure18and receives health condition information from each of the plurality of sensors12via the single communication path14through a single penetration19of the enclosure18.

The single communication path14may include a bus architecture interconnecting each of the sensors12that provides power and communication capability. For example, an E-plex compatible two wire bus architecture available from ED & D, Incorporated, may be used to provide communications and power to the sensors12. The sensors12may be configured as separately addressable nodes on a bus20so that information, such as sensor data and module status, on the bus20intended for a specific sensor12may be identified by the sensor's address, and information and data being provided by the sensor12to the bus20may be source identified by the sensor's address. Using such a bus architecture, it is believed that as many as one thousand sensors12may be attached to the bus20while still providing the single communication path14through, for example, a single penetration54of the enclosure18.

In an aspect of the invention shown inFIG. 2, the sensor20may include a detector22generating a signal24responsive to a health condition of the generator10. For example, the detector22may include a thermocouple, responsive to a temperature of generator cooling gas or water discharge, or a component proximate the thermocouple, generating a voltage signal responsive to the temperature. Other detectors may include an ion current detector for detecting particulates, an acoustic detector for detecting abnormal sound levels, a radio frequency detector for detecting abnormal RF pulses (e.g., arcing and/or partial discharge), an infrared radiation detector for detecting heat emissions, or an ozone detector for detecting arcing.

In an aspect of the invention, each sensor12may include a processor26processing the signal24received from the detector22to generate health condition information based on the signal24. For example, the processor26may include an analog to digital converter that converts the analog value of temperature to a digital representation for bus20transmission. The processor26may be configured for evaluating a voltage signal provided by a thermocouple to determine if the voltage exceeds a predetermined level, such as may be stored in a look-up-table in memory28, indicative of an abnormal health condition of a monitored portion or component of the generator10. Information generated by the processor26, such as health condition information, may be stored in a memory28for later retrieval and/or may be provided to a transmitter30for making the information available on a bus20and accessible by the monitoring device16shown inFIG. 1.

In an aspect of the invention, a sensor12including an IR detector may be positioned near the rotor48and synchronized with the rotor's revolution for sensing heat emissions of components, such as connector bars or end rings of the rotor48. For example, sensors12used for monitoring connector bars may provide raw, or relatively unprocessed, data to the monitoring device16which then processes the raw data from each of the sensors monitoring the connector bar temperature over time to detect relatively small temperature changes in a single stator bar. For example, data from each of the individual sensors12may need to be analyzed over a sufficiently long period of time because such bars may have a relatively large and variable common temperature changing pattern which needs to be removed to detect a relatively small effect of a bar temperature condition indicative of failure. In this case, the monitoring device16may need more processing power than if the monitoring device16were used to simply display information indicative of data processed individually by the respective sensors12.

The processor26of the sensor12may provide all the heath condition information to the monitoring device16via the bus20, or may limit the health information provided, such as by limiting the heath information to information indicative of an abnormal condition, such as a failure condition. Information may be processed at the sensor12to reduce an amount of information needed to be provided to the external monitoring device16to indicate abnormal health condition. For example, the sensor12may filter acquired data, perform self testing and providing status of the sensor12, and provide an alarm signal based on processed data. In one embodiment, the sensor12may process the signal24to simply provide an alarm signal to notify the monitoring device16that a failure condition has occurred. Accordingly, the monitoring device16acts as simple display device. In applications such as stator bar temperature monitoring and generator cooling air monitoring, for example, of particulates suspended in the cooling air, each sensor12may preprocess the information before sensing it to the monitoring device12for display.

Advantageously, an amount of information needed to be transmitted from the respective sensors12may be substantially reduced, since only preprocessed information need be sent back, there is no as well as reducing processing requirement on the monitoring device16because preprocessing is performed locally at the sensor12. In another aspect of the invention, the transmitter30may also be configured as a transceiver to receive information from the bus20, such as sensor programming information, operating programs, and testing instructions issued by the monitoring device16.

In another aspect of the invention, the task of processing data gathered by each sensor12may be shifted to the monitoring device16, instead of the sensor12performing the processing task locally, so that the monitoring device16acts as a data processor and display device. For example, in the case of monitoring stator bar cooling hydrogen or cooling water, temperatures provided by each of the sensors12monitoring these conditions may need to be accumulated, such as in the monitoring device16, to determine a temperature deviation from a mean temperature of the accumulated temperatures. Accordingly, relatively small temperature changes that may be indicative of a failure condition may be sensed sooner than if each temperature from each sensor12is monitored separately.

The components of the sensor12may be contained within a single housing32(for example, a molded plastic housing) positioned within the generator enclosure18proximate a portion or component of the generator10, or a bus bar extending form the generator10, desired to be monitored. It is believed that sensors12may be configured to fit in housing32about the size of match box, allowing the sensors12to be positioned near portions of the generator having limited space or access. In another aspect depicted inFIG. 1, one or more detectors22may be mounted remotely from the housing32. Signals24from the respective detectors22may be fed back to the processor26of the sensor12. For example, one or more detectors22may be positioned within a cooling channel of a stator bar remote from the housing32.

The monitoring device16ofFIG. 1may provide an indication of the health condition of the generator10based on health condition information received from the plurality of sensors12with the enclosure18, such as a respective health condition of each component being monitored. For example, the monitoring device16may include a simple indicator34, such as visual indicator (LED, flashing light, etc.) and/or an audio indicator (bell, buzzer, verbal cue, etc.), to notify an operator of a health condition needing attention. The indicator34may include a video display screen, such as a touch screen, for interactively displaying the health information, for example, received from each of sensors12. The indicator34may include indicia indicative of an overall health of the system, or respective indicial corresponding to each of the sensor used for monitoring the generator10and related equipment such as a generator bus bar. The monitoring device16may simply display information received from each of the sensors12. For example, in the case of stator bar temperature monitoring, the indicator34of the monitoring device16may include the stator bar status, temperatures for each sensor12, status of each of the sensors12, an initialization screen, and a status of a the bus20. Analysis involving accumulated data from each of the sensors12may be performed in the monitoring device16, or the data gathered form each sensor12may be simply displayed at the monitoring device16and then forwarded to a power plant operation computer (not shown) for processing.

The monitoring device16may include processor36in communication with a memory38. The monitoring device16may also include a transceiver40, such as bus controller, for communication with the plurality of sensors12disposed inside the enclosure18via the single communication path14. The processor36may process received data, such as health condition information, to provide an appropriate indication to an operator via the indicator34. The transceiver40may also provide power to sensors12on the bus20from a bus power supply42, for example, using a power modulation technique according to the E-plex bus architecture. An I/O device44, such as a keyboard, may be provided to operate the monitoring device16and remotely program the sensors12. In an aspect of the invention, the I/O device may be incorporated into the indicator34such as by using a touch screen type display for the indicator34. The monitoring device16may be in communication with a plant computer such as via a network, such as the Internet, for remote access and viewing.

In another aspect of the invention shown inFIG. 3, the sensor12as shown inFIG. 2may be configured as one or more particulate sensing devices50disposed within an generator enclosure18, such as an air cooled generator, to detect particulates emitted from respective monitored portions52of the generator10housed within the enclosure16to detect an overheating condition. Each of the particulate sensing devices50may be configured as shown inFIG. 2, wherein the detector22includes an ion detector, such as is commonly used in a household smoke detector. The detector22detects particulates in a sample of a fluid, such as air flowing into the sensing device50from a portion52of the generator10. The particulate sensing device50may include processor26receiving the signal24from the detector22indicative of particulate concentration in a fluid sample. The processor26may then provide, via the transmitter30, health information, responsive to the signal24, to the monitoring device16disposed outside the generator enclosure18over the bus20. The monitoring device16may then provide an indication of a detected particulate concentration detected by the sensor22. In an aspect of the invention, the particulate sensing device50may also include a fluid sampler, such as one of the fluid sampler embodiments depicted inFIGS. 4-6, used to provide fluid samples to the detector22. Accordingly, the processor26may control and monitor operation of the fluid sampler. The particulate sensing devices50may be connected to the 20 bus, such as described earlier, to provide a single connection14to the monitoring device16.

Unlike prior particulate detection systems, by placing the particulate sensors50at known locations within the enclosure18and proximate portions52of a generator10desired to be monitored, the portion52, or component located at the monitored portion52, of the generator10producing a particulate emission may be specifically identified. For example, by correlating the particulate information acquired to a location of the acquiring sensor50, the specific portion52of the generator10experiencing heating may be determined. In an embodiment of the invention, the sensor50may include a collector54comprising a plurality of inlet points56disposed proximate a corresponding plurality of different portions52of the generator10for collecting respective fluid samples and delivering the samples to the sensor50, so that the sensor50may monitor two or more different portions52of the generator10. Compared to known sampling systems that require relatively sensitive particulate detectors because of dilution of sampling air, relatively inexpensive, less sensitive detectors22may be used while still providing sufficient sensitive to detect overheating conditions.

In yet another embodiment, the detector22of the sensor50may be in communication with a fluid sampler, such as one of the fluid sampler embodiments depicted inFIGS. 4-6. The fluid sampler58shown inFIG. 4may include a first flow path60conducting a first portion74of a fluid78and a second flow path62conducting a second portion68of the fluid78in communication with the detector22positioned in communication with a detection chamber64. The detector22may be contained in a housing12and mounted below the detection chamber64. The second flow path62may include a filter66for filtering the second portion68of the fluid78passing therethrough. A flow controller70, such as a rotatable hollow cylindrical plug72, is operable to selectively allow the first portion74of the fluid78and a filtered portion76of the fluid78to flow through respective flow paths60,62to the detector22in the chamber64. The cylindrical plug72may include an orifice80positioned in a quadrant of the plug72to allow a fluid to flow into the orifice80and out of an end82of the plug72. The plug72may be rotated so that the orifice80aligns with one or the other flow paths60,62to selectively conduct either the first portion74or the filtered portion76to the detector22, or rotated to block a flow of either portion74,76. The rotation of the plug72may driven by a motor84, such as by a shaft encoded motor coupled to a gear reduction mechanism (not shown) to drive the plug72. In an embodiment, the motor84may be controlled by the processor26ofFIG. 2to move and confirm, such as optically, the position of the plug72. Motor power may be sourced from the bus20.

The positioning of the plug72may be described using a clock notation looking in the direction indicated by arrow86. Accordingly, a 12:00 position of the plug72indicates the orifice80is directed upward (perpendicularly outward from the page ofFIG. 4), a 3:00 position indicates the orifice80is oriented to direct the first portion74into the chamber64for particulate measurement, and a 9:00 position indicates the orifice80is oriented to direct the filtered portion76into the chamber64for particulate measurement. A sequence for measuring a fluid sample for particulates and comparing a particulate measurement to a filtered sample to verify a particulate measurement may include is:1. Positioning plug to 3:00 (chamber64receives unfiltered sample, e.g. first portion74)2. Positioning plug to 12:00 (chamber64is sealed, particulate measurement is made by sensor50)3. Positioning plug to 3:00 (chamber64receives a new sample)4. Positioning plug to 12:00 (chamber64is sealed, particulate measurement is made by sensor50)5. High particulate level is measured6. Positioning plug to 9:00 (chamber64receives filtered sample, e.g. filtered portion76)7. Positioning plug to 12:00 (chamber64is sealed, particulate measurement is made by sensor50)8. If no particulate is detected, high particulate level verified, alarm is issued9. Positioning plug to 3:00 (chamber64receives a new sample)10. Positioning plug to 12:00 (chamber64is sealed, particulate measurement is made by sensor50)

In another aspect of the invention, a flow monitoring device (not shown) may be disposed in the second flow path62, such as downstream of the filter66, for measuring an amount of the second portion68of the fluid78passing through the filter66to allow determining if the filter66is becoming clogged. For example, a downstream measured amount of flow of the second portion68may be compared to an upstream amount of flow of the second portion68measured by a second flow monitoring device disposed in the second flow path62upstream of the filter66to determine if the filter66is prohibitively restricting the flow of the second portion68flowing therethrough. In another aspect, a particulate producing element, such as a heating element, may be disposed in the fluid78upstream of the fluid sampler58to selectively introduce particulates into the fluid78, for example, to test the operation of the fluid sampler58and detector22in detecting particulates.

In another embodiment depicted inFIG. 5, a fluid sampler86may include an impulse valving arrangement wherein a fluid flow is controlled by a flow controller70such as a cylindrical plug88positioned within a cylindrical channel90comprising a first flow path92and a second flow path94in communication with the detector22positioned in a detection chamber96. The second flow path92may include a filter66for filtering a fluid passing therethrough. The plug88may be formed from a material, such as a ferrous material, responsive to an electromagnetic field, selectively formed for example, by an electromagnetic coil. The plug88may be translated by an electromagnetic force within the cylindrical channel90to selectively seal the first flow path92(position98indicated by dotted line depiction of plug88′), the second flow path92(position99indicated by plug88), or the chamber96(position100indicated by dotted line depiction of plug88″), respectively.

The plug88may by moved by selectively energizing left end coil102, center coil104, and right end coil106, by applying a magnetic force to translate the plug88. For example, by energizing the center coil104, the plug88moves to position100to seal the chamber96to measure a particulate level of a sample directed into the chamber96. The left end coil102is energized to move the plug88to position99to allow a first portion74of the fluid78to be sampled to flow to the chamber96, while the right end coil106is energized to move the plug88to position98to allow a filtered portion76of a second portion68of the fluid78to flow to the chamber96. The coils102,104,106may be controlled by the processor26ofFIG. 2to move and confirm the position of the plug88. Coil power may be sourced from the bus20. Power may be stored in capacitor (not shown) to provide impulse power to the coils102,104,106so that the coils102,104,106may be sequentially pulsed to move the plug88. A response of a coil102,104,106to a power pulse may be monitored, for example by processor26and used to verify that the plug88has moved to a desired position. A sequence for measuring a sample for particulates and comparing a particulate measurement to a filtered sample to verify a particulate measurement may include:1. Energize Right Coil106to position plug at position98(chamber96receives unfiltered sample, e.g. first portion74)2. Energize Center Coil104to position plug88at position100(chamber96is sealed, particulate measurement is made)3. Energize Right Coil106to position plug88at position98(chamber96receives new unfiltered sample)4. Energize Center Coil104to position plug88at position100(chamber96is sealed, particulate measurement is made)5. High particular level is measured5. Energize Left Coil102to position plug88at position99(chamber96receives filtered sample, e.g. filtered portion76)6. Energize Center Coil104to position plug88at position100(chamber96is sealed, particulate measurement is made.8. No particulate is detected, high particular level is verified, alarm is issued7. Energize Right Coil106to position plug88at position98(chamber receives new unfiltered sample)8. Energize Center Coil104to position plug88at position100(chamber96is sealed, particulate measurement is made).

In another embodiment depicted inFIG. 6, a fluid sampler108may include an impulse valving arrangement wherein a flow controller70includes two cylindrical plugs,110,112positioned within a cylindrical channel114comprising a first flow path118and a second flow path121. Each of the flow paths118,121of the channel114are in communication with the detector22positioned in a detection chamber116. The first flow path conducts the first portion74of the fluid flow78to the chamber116in communication with channel114. The second flow path121may include a filter66for filtering the second portion68of the fluid78passing therethrough. The plugs110,112include portions111,113, such as ferrous material portions, responsive to a magnetic field induced by respective coils pairs120,126. Each coil pair120,126includes an outboard coil122,128and an inboard coil124,130, respectively, to position the plugs110,112in the channel114on respective sides of the chamber116. Each plug110,112can be independently moved by the respective coil pairs120,126within the channel114to seal the chamber116(as indicated, for example, by the position of plug112) and to allow a fluid to flow along the respective flow paths118,121into the chamber116(as indicated, for example, by the position of plug110). Power may be stored in capacitor (not shown) to provide impulse power to the coils122,128,124,130so that the coils122,128,124,130may be sequentially pulsed to move the plugs110,112. A response of a coil122,128,124,130to a power pulse may be monitored, for example by processor26and used to verify that the plugs110,112have moved to a desired position. A sequence for measuring a sample for particulates and comparing a particulate measurement to a filtered sample to verify a particulate measurement may include:1. Energize outboard coil128to position plug110to allow first portion74to flow to chamber116(chamber116receives unfiltered sample)2. Energize inboard130and outboard coil128to move plug110in an inboard direction3. Energize inboard coil130to position plug110to seal chamber116(chamber116is sealed, particulate measurement is made)4. Energize inboard130and outboard coil128to move plug110in an outboard direction5. Energize outboard coil128to position plug110to allow second portion74to flow to chamber116(chamber116receives new unfiltered sample)

Steps 1-5 are repeated until a particulate is measured in step 3. If a particulate level in excess of a certain threshold is measured in step 3, plug110is not moved from its position after step 3 (unfiltered sample flow is blocked), and the inboard coil124and outboard coil122controlling plug112are operated per steps 1-3 as described above to measure a filtered sample. If no particulate condition is found in the filtered fluid sample, a particulate alarm may be issued. The coils122,124,128,130may be controlled by the processor26ofFIG. 2to move and confirm the position of the plugs110,112. Coil power may be sourced from the bus20. The above steps may also include energizing both inboard coil124and outboard coil122between individual coil firings to affect smoother plug movement.

The sensors12as described above may be applied to iso-phase busses that transfer electrical energy from the generator to a step-up transformer that may be located more than 100 feet from the generator. In power generator installations, bus bars connecting the generator to a power grid and bus bar connections between sections of the bus bars are typically enclosed by a bus bar enclosure132prohibiting easy access for inspection. Typically, a bus bar connection130may include a plurality of flexible conducting straps136connecting internal bus bar conductors134together. Contact areas138between the straps136and the bus bar134may become compromised, such as by corrosion or loosening of a connection between the bus bar134and the strap136due to thermal cycling, resulting in heating of the connection130due to an increased contact resistance. The inventors have innovatively realized the resulting heating may be monitored and analyzed to detect a health of the connection130, such as by using an infrared radiation detecting sensor12positioned for receiving infrared radiation from the connection130.

As shown in the cross sectional view ofFIG. 7, one or more sensors12, such as the sensor12shown inFIG. 2, may be disposed proximate a bus bar connection130of a bus bar134of a generator to monitor a health condition of the bus bar connection130. Each sensor20may include a detector22, such as infrared radiation detector receiving an infrared radiation emission140from the bus bar connection130and generating a signal24responsive to a health condition of the bus bar connection130. The sensor20may include a processor26for processing the signal24received from the detector22to generate health condition information based on the signal24. The health condition information may be provided to a monitoring device16for displaying heath condition information. In an aspect of the invention, one or more sensors12may be connected to a bus20having a single communication path14to a monitoring device16for monitoring the conditions of the bus bar connection130. In aspect of the invention, the sensor12may be disposed on the bus bar enclosure132, such as by forming a hole in the enclosure to allow the detector22to receive the radiation emission140emitted from the connection130and attaching the sensor12to an external surface142of the enclosure132. A conducting wire mesh150may be installed over an opening152in the bus bar enclosure132to reduce electrical radiation, while still allowing infrared radiation to reach the detector22.

To monitor each of the respective straps136comprising the connection130, the infrared detector22may include a plurality of sensing zones144, each zone144configured to receive infrared radiation emitted from a respective connector strap136(or straps) comprising the bus bar connection130. For example, a lens146, such as a fresnel lens, may be used to focus a respective infrared radiation emission148from each of the respective connector straps136to the corresponding sensing zone144of the infrared detector22. In an exemplary embodiment, two or more sensors12are disposed on the bus bar enclosure132to ensure the each of the straps136can be viewed by the sensors12. Differences in temperature between respective straps136, or groups of straps136, may be analyzed, for example by processor26, to remove temperature differences common to all of the straps136. In other embodiments, the sensor12may include a detector for sensing a radio frequency emission, an ozone level, an acoustic emission, and/or an ultraviolet emission from the bus bar connection130. In a noise reduction aspect of the invention, respective infrared emissions from a plurality of connector straps136of the bus bar connection130may be sensed, and the sensed values of the respective infrared emissions may be normalized with respect to sensed values common among the respective infrared emissions, so that non-common differences among the straps136, such as one strap136experiencing more heating than the others, may be highlighted.