CN113708343A - Stator grounding protection method and device for salient pole generator and electronic equipment - Google Patents

Stator grounding protection method and device for salient pole generator and electronic equipment Download PDF

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Publication number
CN113708343A
CN113708343A CN202010442320.8A CN202010442320A CN113708343A CN 113708343 A CN113708343 A CN 113708343A CN 202010442320 A CN202010442320 A CN 202010442320A CN 113708343 A CN113708343 A CN 113708343A
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generator
zero
sequence voltage
neutral point
stator
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CN113708343B (en
Inventor
陈俊
季遥遥
王光
张琦雪
郭自刚
徐杰
房康
徐金
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NR Electric Co Ltd
NR Engineering Co Ltd
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NR Electric Co Ltd
NR Engineering Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/06—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric generators; for synchronous capacitors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/175—Indicating the instants of passage of current or voltage through a given value, e.g. passage through zero
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines
    • G01R31/346—Testing of armature or field windings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
    • H02H3/162—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems
    • H02H3/165—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems for three-phase systems
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

Abstract

The application provides a stator grounding protection method for a salient pole generator, which comprises the following steps: acquiring measurement data comprising machine end three-phase voltage, machine end three-phase current, machine end zero-sequence voltage and neutral point zero-sequence voltage; respectively calculating reactive power of the generator, a third harmonic amplitude of zero-sequence voltage at the generator end, a third harmonic amplitude of zero-sequence voltage at a neutral point and third harmonic ratio values of zero-sequence voltage at the generator end and the neutral point according to the measurement data; when the generator is connected to the grid and generates reactive power, if the third harmonic ratio value of the zero-sequence voltage of the generator end and the neutral point is larger than a set first fixed action threshold, determining that the stator is in ground fault; and after the generator is connected to the grid, when the reactive power is absorbed, if the third harmonic ratio value of the zero sequence voltage of the generator end and the neutral point is greater than a set floating action threshold, determining that the stator is in ground fault. Aiming at the phase-in operation stage, a floating action threshold which is automatically raised along with the increase of reactive power is adopted, so that the reliability of stator ground protection is improved.

Description

Stator grounding protection method and device for salient pole generator and electronic equipment
Technical Field
The application relates to the field of relay protection of power systems, in particular to a stator grounding protection method and device for a salient pole generator, electronic equipment and a computer readable medium.
Background
Damage to the ground insulation by the generator stator windings will cause a single phase earth fault. Single-phase earth faults are the most common type of fault for generators. In order to ensure safe and stable operation of the generator set, the fundamental zero sequence voltage stator ground protection is usually matched with the third harmonic voltage ratio stator ground protection to form 100% ground fault protection of the generator stator winding. The grounding protection of the fundamental wave zero sequence voltage stator is in response to the grounding fault within 85% of the generator end, and the grounding protection of the third harmonic voltage ratio stator is in response to the grounding fault within 25% of the generator neutral point.
When the salient pole generator, such as a water turbine, has inductive reactive power, the longitudinal shaft armature reaction can play a role in assisting the magnetism of third harmonic, so that third harmonic of terminal zero sequence voltage and third harmonic of neutral point zero sequence voltage are increased. Therefore, the third harmonic of the zero-sequence voltage of the generator set is greatly influenced by the reactive power. When the generator set is in the phase-entering operation stage, the third harmonic of the zero-sequence voltage at the generator end and the third harmonic of the zero-sequence voltage at the neutral point are increased, and the voltage ratio value of the third harmonic of the zero-sequence voltage at the generator end and the neutral point is also synchronously increased. Moreover, the deeper the phase advance, the larger the third harmonic voltage ratio value of the zero sequence voltage of the machine end and the neutral point is, so that the reliability of the third harmonic voltage ratio stator ground protection is reduced, and even the false alarm or false tripping of the third harmonic voltage ratio stator ground protection occurs.
Disclosure of Invention
The method for protecting the stator ground of the salient pole generator improves the reliability of the third harmonic voltage ratio stator ground protection under the in-phase operation of the generator set by carrying out sectional processing on the operation state of the generator set and adopting a floating action threshold technology which is automatically raised along with the increase of reactive power aiming at the in-phase operation stage.
According to an aspect of the present application, there is provided a stator ground protection method for a salient pole generator, characterized by comprising:
acquiring measurement data comprising machine end three-phase voltage, machine end three-phase current, machine end zero-sequence voltage and neutral point zero-sequence voltage;
respectively calculating reactive power of the generator, a third harmonic amplitude of zero-sequence voltage at the generator end, a third harmonic amplitude of zero-sequence voltage at a neutral point and third harmonic ratio values of zero-sequence voltage at the generator end and the neutral point according to the measurement data;
when the generator is connected to the grid and generates reactive power, if the calculated third harmonic ratio value of the zero-sequence voltage of the generator end and the neutral point is larger than a set first fixed action threshold, determining that the generator set stator has a ground fault;
and after the generator is connected to the grid, when the reactive power is absorbed, if the calculated third harmonic ratio value of the zero sequence voltage of the generator end and the neutral point is greater than a set floating action threshold, determining that the generator set stator has a ground fault.
According to some embodiments of the application, the protection method further comprises:
and after the grounding fault of the stator of the unit is judged, the signal is acted or the tripping is acted after a period of time delay.
According to some embodiments of the application, the protection method further comprises:
and before the generator is connected to the grid, if the calculated third harmonic ratio value of the zero sequence voltage of the generator end and the neutral point is larger than a set second fixed action threshold, determining that the generator set stator has a ground fault.
According to some embodiments of the present application, obtaining measurement data of the generator including a generator-end three-phase voltage, a generator-end three-phase current, a generator-end zero-sequence voltage, and a neutral-point zero-sequence voltage comprises:
acquiring the three-phase voltage at the generator end through a voltage transformer at the generator end;
obtaining the three-phase current at the generator end through a current transformer at the generator end;
obtaining the zero sequence voltage at the generator end through an opening triangle of a voltage transformer at the generator end;
and acquiring the neutral point zero sequence voltage through a neutral point grounding transformer secondary load tap.
According to some embodiments of the application, calculating reactive power, machine end zero sequence voltage third harmonic amplitude, neutral point zero sequence voltage third harmonic amplitude, machine end and neutral point zero sequence voltage third harmonic ratio values of the generator from the measurement data, respectively, comprises:
and calculating the reactive power, the third harmonic amplitude of the zero-sequence voltage at the machine end and the third harmonic amplitude of the zero-sequence voltage at the neutral point by adopting a Fourier algorithm according to the measurement data.
According to some embodiments of the present application, the machine-side and neutral zero-sequence voltage third harmonic ratio value is calculated according to the following formula:
Figure BDA0002504617390000031
k is a third harmonic ratio value of zero-sequence voltage of the machine end and a neutral point; u shapeS0The third harmonic amplitude of the zero sequence voltage at the generator end; u shapeN0The third harmonic amplitude of the neutral zero sequence voltage is obtained.
According to some embodiments of the present application, the method for setting the first fixed motion threshold comprises:
and setting according to the third harmonic ratio value of the zero sequence voltage of the maximum machine end and the neutral point calculated according to the measured data under the condition of normal operation after the generator is connected to the grid.
According to some embodiments of the present application, the floating action threshold is calculated according to the following equation:
Figure BDA0002504617390000032
wherein, Kset3Threshold for said floating; kset2A first fixed motion threshold; krelThe reliability coefficient is generally 2-10; q is the reactive power of the generator, and the absorbed reactive power is negative; pNThe rated active power of the generator.
According to some embodiments of the present application, the method for setting the second fixed motion threshold comprises:
and setting according to a third harmonic ratio value of zero-sequence voltage of a maximum machine end and a neutral point calculated according to the measured data before the generator is connected to the grid.
According to some embodiments of the present application, the method for setting a delay time includes:
and setting according to the matching of the backup protection action time limit of the power grid system ground fault.
According to another aspect of the present application, there is provided a stator ground protection device for a salient pole generator, comprising:
the data measurement module is used for acquiring measurement data of the generator, wherein the measurement data comprises generator end three-phase voltage, generator end three-phase current, generator end zero-sequence voltage and neutral point zero-sequence voltage;
the data calculation module is used for calculating the reactive power of the generator, the third harmonic amplitude of the zero-sequence voltage at the generator end, the third harmonic amplitude of the zero-sequence voltage at the neutral point and the third harmonic ratio value of the zero-sequence voltage at the generator end and the neutral point respectively according to the measurement data;
the first judgment module is used for judging that the generator set stator ground fault occurs if the calculated third harmonic ratio value of the zero sequence voltage of the generator end and the neutral point is larger than a set first fixed action threshold when the generator is connected to the grid and generates reactive power;
and the second judgment module is used for judging that the generator stator ground fault occurs if the calculated third harmonic ratio value of the zero sequence voltage of the generator end and the neutral point is greater than a set floating action threshold when the generator is connected to the grid and absorbs reactive power.
According to some embodiments of the application, the protection device further comprises:
and the protection action module is used for acting on a signal or acting on tripping after a period of time delay after the grounding fault of the stator of the unit is judged.
According to some embodiments of the application, the protection device further comprises:
and the third judgment module is used for judging that the generator set stator ground fault exists if the calculated third harmonic ratio value of the zero-sequence voltage of the generator end and the neutral point is greater than a set second fixed action threshold before the generator is connected to the grid.
According to another aspect of the present application, there is provided an electronic device for stator ground protection of a salient pole generator, comprising:
one or more processors;
storage means for storing one or more programs;
when executed by the one or more processors, cause the one or more processors to implement the stator ground protection method described above.
According to another aspect of the present application, there is provided a computer readable medium having a computer program stored thereon, wherein the program when executed by a processor implements the stator ground protection method described above.
The stator ground protection method for the salient pole generator aims at the problem that false alarm or false tripping exists in the phase-in operation stage of a salient pole generator unit in the conventional third harmonic voltage ratio stator ground protection, and a sectional processing scheme and a floating action threshold technology are adopted for the third harmonic voltage ratio stator ground protection of the salient pole generator, so that the sensitivity of the stator ground protection under the normal operation condition of the unit is ensured, and the reliability of the ground protection under the phase-in operation of the unit is improved.
Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is apparent that the drawings in the following description are only some embodiments of the present application.
Fig. 1 shows a flow chart of a stator ground protection method according to an example embodiment of the present application.
Fig. 2 shows a flow chart of a stator ground protection method according to another example embodiment of the present application.
Fig. 3 is a schematic diagram illustrating an implementation process of a stator ground protection method according to an exemplary embodiment of the present application.
Fig. 4 shows a block diagram of a stator ground protection device according to an example embodiment of the present application.
Fig. 5 shows a block diagram of a stator ground protection device according to another example embodiment of the present application.
Fig. 6 shows a block diagram of electronics for salient pole generator stator ground protection, according to an example embodiment of the present application.
Detailed Description
Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals denote the same or similar parts in the drawings, and thus, a repetitive description thereof will be omitted.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the subject matter of the present application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the application.
It will be understood that, although the terms first, second, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first component discussed below may be termed a second component without departing from the teachings of the present concepts. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Those skilled in the art will appreciate that the drawings are merely schematic representations of exemplary embodiments, which may not be to scale. The blocks or flows in the drawings are not necessarily required to practice the present application and therefore should not be used to limit the scope of the present application.
The inventor finds that when the existing third harmonic voltage ratio stator ground protection method is adopted to carry out stator ground fault protection on the salient pole generator, because the existing third harmonic voltage ratio stator ground protection method adopts a fixed action threshold, the protection reliability is reduced when the salient pole generator is in an in-phase operation stage, and even false alarm or false tripping occurs.
Aiming at the problems in the prior art, the inventor provides a stator ground protection method for a salient pole generator, which is used for carrying out sectional processing on different operation stages of the generator, wherein the generator is in a phase-in operation stage, and fault judgment is carried out by adopting a floating action threshold technology, so that the reliability of stator ground protection is improved.
Fig. 1 shows a flow chart of a stator ground protection method according to an example embodiment of the present application.
As shown in fig. 1, the present application provides a stator ground protection method for a salient pole generator, comprising:
in step S110, measurement data including the machine-side three-phase voltage, the machine-side three-phase current, the machine-side zero-sequence voltage, and the neutral zero-sequence voltage are acquired. Specifically, in the process of obtaining the measurement data, the generator-end three-phase voltage can be obtained through a generator-end voltage transformer; obtaining the three-phase current at the generator end through a current transformer at the generator end; obtaining the zero sequence voltage at the generator end through an opening triangle of a voltage transformer at the generator end; and acquiring the neutral point zero sequence voltage through a neutral point grounding transformer secondary load tap.
In step S120, reactive power of the generator, third harmonic amplitude of zero-sequence voltage at the generator end, third harmonic amplitude of zero-sequence voltage at the neutral point, and third harmonic ratio of zero-sequence voltage at the generator end and the neutral point are calculated according to the measured data. After the measurement data are obtained, the reactive power, the third harmonic amplitude of the zero-sequence voltage at the machine end, the third harmonic amplitude of the zero-sequence voltage at the neutral point and the third harmonic ratio value of the zero-sequence voltage at the machine end and the neutral point can be calculated by adopting a Fourier algorithm according to the measurement data.
For example, the reactive power can be calculated by a fourier algorithm according to the terminal three-phase voltage and the terminal three-phase current. According to the zero sequence voltage of the machine end, the third harmonic amplitude of the zero sequence voltage of the machine end can be calculated by adopting a Fourier algorithm. Similarly, according to the neutral zero sequence voltage, the third harmonic amplitude of the neutral zero sequence voltage can be calculated by using a Fourier algorithm. The fourier algorithm may be a full-cycle fourier algorithm, a half-cycle fourier algorithm, a windowed fourier algorithm, or the like, but the application is not limited thereto.
The third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point is calculated according to the following formula:
Figure BDA0002504617390000071
k is a third harmonic ratio value of zero-sequence voltage of the machine end and a neutral point; u shapeS0The third harmonic amplitude of the zero sequence voltage at the generator end; u shapeN0The third harmonic amplitude of the neutral zero sequence voltage is obtained.
In step S130, when the generator is connected to the grid and generates reactive power, if the third harmonic ratio of the zero-sequence voltage of the generator end and the neutral point is greater than a first fixed action threshold, it is determined that the generator stator has a ground fault.
After the generator is connected to the grid, when the unit generates reactive power, the protection judgment condition of the generator third harmonic voltage ratio stator ground fault can be expressed as:
Figure BDA0002504617390000081
k is a third harmonic ratio value of zero-sequence voltage of the machine end and a neutral point; kset2Setting a maximum machine end and neutral point zero sequence voltage third harmonic ratio value calculated according to the measured measurement data after the generator is connected to the power grid and under the normal operation condition for the machine end and neutral point zero sequence voltage third harmonic ratio first fixed action threshold after the power grid is connected to the power grid; u shapeS0The third harmonic amplitude of the zero sequence voltage at the generator end; u shapeN0The third harmonic amplitude of the neutral zero-sequence voltage is obtained; q is the reactive power of the generator and sends out the reactive power, and the Q value is positive.
In step S140, when the generator is connected to the grid and absorbs reactive power, if the third harmonic ratio of the zero-sequence voltage of the generator end and the neutral point is greater than the set floating operation threshold, it is determined that the generator set stator has a ground fault.
After the generator is connected to the grid, when the unit is in the phase-in operation stage, the protection judgment condition of the third harmonic voltage ratio stator ground fault of the generator can be expressed as:
Figure BDA0002504617390000082
k is a third harmonic ratio value of zero-sequence voltage of the machine end and a neutral point; kset3A third harmonic voltage ratio floating action threshold is set for the zero sequence voltage at the machine end and the neutral point of the phase-entering operation stage; u shapeS0The third harmonic amplitude of the zero sequence voltage at the generator end; u shapeN0The third harmonic amplitude of the neutral zero-sequence voltage is obtained; krelThe reliability coefficient is generally 2-10; q is the reactive power of the generator, and when the reactive power is absorbed, the Q value is negative; pNRated active power for the generator; kset2The third harmonic voltage ratio of the zero sequence voltage of the machine end and the neutral point after grid connection is the first fixed action threshold.
From the above-mentioned determination conditions, the threshold K of the floating operationset3Instead of a fixed value, it automatically rises as the reactive power increases. The action threshold is associated with the absorbed reactive power, so that the phenomenon of false alarm or false tripping caused by adopting a fixed action threshold can be solved.
Fig. 2 shows a flow chart of a stator ground protection method according to another example embodiment of the present application.
According to some embodiments of the present application, there is also provided a stator ground protection method, including, in addition to the steps shown in fig. 1:
in step S150, before the generator is connected to the grid, if the third harmonic ratio of the zero-sequence voltage at the generator end and the neutral point is greater than a second fixed action threshold, it is determined that the generator set stator has a ground fault.
Before the generator is connected to the grid, the protection judgment condition of the third harmonic voltage ratio stator ground fault of the generator can be expressed as follows:
Figure BDA0002504617390000091
k is a third harmonic ratio value of zero-sequence voltage of the machine end and a neutral point; kset1Setting a third harmonic voltage ratio value of a maximum machine end and a neutral point zero sequence voltage calculated according to the measured data before the generator is connected to the grid according to a second fixed action threshold of the third harmonic voltage ratio before the grid is connected; u shapeS0The third harmonic amplitude of the zero sequence voltage at the generator end; u shapeN0The third harmonic amplitude of the neutral zero sequence voltage is obtained.
In step S160, after the ground fault of the stator of the unit is determined, a delay is performed to act on a signal or act on a trip. After the stator ground fault is judged according to the judgment conditions in the steps, in order to be matched with the ground fault backup protection of the power grid system, the stator ground fault can be operated to give an alarm through a signal after a period of time delay, or operated to trip to cut off the fault. Therefore, the period of time delay is matched and set according to the backup protection action time limit of the power grid system ground fault.
Fig. 3 is a schematic diagram illustrating an implementation process of a stator ground protection method according to an exemplary embodiment of the present application.
U in the figureS0The third harmonic amplitude of the zero sequence voltage at the generator end; u shapeN0The third harmonic amplitude of the neutral zero-sequence voltage is obtained; kset1A second fixed action threshold that is a third harmonic voltage ratio before grid connection; kset2A first fixed action threshold being a third harmonic voltage ratio after grid connection; q is the reactive power of the unit, and is positive when the reactive power is sent out and is negative when the reactive power is absorbed; krelThe reliability coefficient is generally 2-10; pNRated active power for the generator; t is the protection action delay.
As shown in fig. 3, in the stator ground protection method provided by the present application, a stator ground protection fault of a unit can be determined by three determination conditions, which are:
when the unit is not connected to the grid, and the third harmonic ratio value U of the zero-sequence voltage of the generator end and the neutral pointS0/UN0Greater than Kset1If so, judging that the judgment condition is met;
when the unit is connected to the grid and generates reactive power, namely Q is more than or equal to 0, and the generator end is connected with the generator endThird harmonic ratio value U of neutral point zero sequence voltageS0/UN0Greater than Kset2If so, judging that the judgment condition is met;
when the unit is connected to the grid and absorbs reactive power, namely Q is less than 0, and the third harmonic ratio value U of zero-sequence voltage of the machine end and the neutral pointS0/UN0Greater than (1+ K)rel*|Q|/PN)*Kset2When the judgment result is positive, the judgment condition is judged to be satisfied.
When any one of the above judgment conditions is satisfied, the stator protection action of the third harmonic voltage ratio is carried out after a protection delay t.
Fig. 4 shows a block diagram of a stator ground protection device according to an example embodiment of the present application.
According to an example embodiment of the present application, there is also provided a stator ground protection device 400 for a salient pole machine, comprising: the system comprises a data measurement module 410, a data calculation module 420, a first judgment module 430 and a second judgment module 440. Wherein:
and the data measurement module 410 is used for acquiring measurement data of the generator, including the generator-end three-phase voltage, the generator-end three-phase current, the generator-end zero-sequence voltage and the neutral-point zero-sequence voltage. The machine end three-phase voltage can be obtained through a machine end voltage transformer; the three-phase current at the generator end can be obtained through a current transformer at the generator end; the zero sequence voltage at the generator end can be obtained by an opening triangle of a voltage transformer at the generator end; the neutral point zero sequence voltage can be obtained through a neutral point grounding transformer secondary load tap.
And the data calculation module 420 is used for calculating the reactive power of the generator, the third harmonic amplitude of the zero-sequence voltage at the generator end, the third harmonic amplitude of the zero-sequence voltage at the neutral point and the third harmonic ratio value of the zero-sequence voltage at the generator end and the neutral point respectively according to the measurement data. The reactive power can be calculated by a Fourier algorithm according to the three-phase voltage at the generator end and the three-phase current at the generator end. The third harmonic amplitude of the zero-sequence voltage at the machine end and the third harmonic amplitude of the zero-sequence voltage at the neutral point can be calculated by a Fourier algorithm according to the zero-sequence voltage at the machine end and the zero-sequence voltage at the neutral point. And the third harmonic ratio value of the zero-sequence voltage of the machine end to the neutral point is the ratio of the third harmonic amplitude of the zero-sequence voltage of the machine end to the third harmonic amplitude of the zero-sequence voltage of the neutral point.
The first judging module 430 is configured to, when the generator is connected to the grid and generates reactive power, determine that a ground fault of the stator of the generator set occurs if the calculated third harmonic ratio of the zero-sequence voltage of the generator end and the neutral point is greater than a set first fixed action threshold. And the first fixed action threshold is set according to a third harmonic ratio value of zero sequence voltage at a maximum machine end and a neutral point calculated according to the measured data after the generator is connected to the grid and under the normal operation condition.
And the second judging module 440 is configured to, when the generator is connected to the grid and absorbs reactive power, judge that the generator set stator ground fault occurs if the calculated third harmonic ratio of the zero-sequence voltage of the generator end and the neutral point is greater than a set floating action threshold. Wherein the floating action threshold is calculated according to the following formula:
Figure BDA0002504617390000111
wherein, Kset3Is the floating action threshold; kset2A first fixed motion threshold; krelThe reliability coefficient is generally 2-10; q is the reactive power of the generator, and the absorbed reactive power is negative; pNThe rated active power of the generator.
Fig. 5 shows a block diagram of a stator ground protection device according to another example embodiment of the present application.
According to another embodiment of the present application, the stator ground protection device 400 provided by the present application may further include a third determination module 450 and a protection action module 460 in addition to the modules described in fig. 4.
And a third determining module 450, configured to determine that the generator set stator has a ground fault if the calculated third harmonic ratio of the zero-sequence voltage at the generator end and the neutral point is greater than a second fixed action threshold before the generator is connected to the grid. And the second fixed action threshold is used for setting a third harmonic ratio value of zero-sequence voltage at a maximum machine end and a neutral point calculated according to the measured data before the generator is connected to the grid.
And the protection action module 460 is used for acting on a signal or acting on tripping after a period of time delay after the stator ground fault of the unit is judged. And the section of time delay is matched and set according to the backup protection action time limit of the power grid system ground fault.
Fig. 6 shows a block diagram of electronics for salient pole generator stator ground protection, according to an example embodiment of the present application.
The present application further provides an electronic device 700 for salient pole generator stator ground protection. The control device 700 shown in fig. 6 is only an example, and should not bring any limitation to the functions and the scope of use of the embodiments of the present application.
As shown in fig. 6, the control device 700 is in the form of a general purpose computing device. The components of the control device 700 may include, but are not limited to: at least one processing unit 710, at least one memory unit 720, a bus 730 that couples various system components including the memory unit 720 and the processing unit 710, and the like.
The storage unit 720 stores program codes, which can be executed by the processing unit 710 to cause the processing unit 710 to execute the methods according to the above-mentioned embodiments of the present application described in the present specification.
The storage unit 720 may include readable media in the form of volatile memory units, such as a random access memory unit (RAM)7201 and/or a cache memory unit 7202, and may further include a read only memory unit (ROM) 7203.
The storage unit 720 may also include a program/utility 7204 having a set (at least one) of program modules 7205, such program modules 7205 including, but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which, or some combination thereof, may comprise an implementation of a network environment.
Bus 730 may be any representation of one or more of several types of bus structures, including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.
The electronic device 700 may also communicate with one or more external devices 7001 (e.g., touch screen, keyboard, pointing device, bluetooth device, etc.), with one or more devices that enable a user to interact with the electronic device 700, and/or with any devices (e.g., router, modem, etc.) that enable the electronic device 700 to communicate with one or more other computing devices. Such communication may occur via an input/output (I/O) interface 750. Also, the electronic device 700 may communicate with one or more networks (e.g., a Local Area Network (LAN), a Wide Area Network (WAN), and/or a public network such as the internet) via the network adapter 760. The network adapter 760 may communicate with other modules of the electronic device 700 via the bus 730. It should be appreciated that although not shown in the figures, other hardware and/or software modules may be used in conjunction with the electronic device 700, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, among others.
Furthermore, the present application also provides a computer readable medium having stored thereon a computer program, characterized in that the program, when executed by a processor, implements the above-described stator ground protection method for a salient pole generator.
It should be understood that the above examples are only for clearly illustrating the present application and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of this invention may be made without departing from the spirit or scope of the invention.

Claims (15)

1. A stator ground protection method for a salient pole generator, comprising:
acquiring measurement data comprising machine end three-phase voltage, machine end three-phase current, machine end zero-sequence voltage and neutral point zero-sequence voltage;
respectively calculating reactive power of the generator, a third harmonic amplitude of zero-sequence voltage at the generator end, a third harmonic amplitude of zero-sequence voltage at a neutral point and third harmonic ratio values of zero-sequence voltage at the generator end and the neutral point according to the measurement data;
when the generator is connected to the grid and generates reactive power, if the third harmonic ratio value of the zero-sequence voltage of the generator end and the neutral point is larger than a set first fixed action threshold, determining that the generator set stator has a ground fault;
and after the generator is connected to the grid, when the reactive power is absorbed, if the third harmonic ratio value of the zero sequence voltage of the generator end and the neutral point is greater than a set floating action threshold, determining that the generator set stator has a ground fault.
2. The stator ground protection method according to claim 1, further comprising:
and after the grounding fault of the stator of the unit is judged, the signal is acted or the tripping is acted after a period of time delay.
3. The stator ground protection method according to claim 1, further comprising:
and before the generator is connected to the grid, if the third harmonic ratio value of the zero sequence voltage of the generator end and the neutral point is greater than a set second fixed action threshold, determining that the generator set stator has a ground fault.
4. The stator ground protection method of claim 1, wherein obtaining measurement data of the generator including a generator-end three-phase voltage, a generator-end three-phase current, a generator-end zero-sequence voltage, and a neutral zero-sequence voltage comprises:
acquiring the three-phase voltage at the generator end through a voltage transformer at the generator end;
obtaining the three-phase current at the generator end through a current transformer at the generator end;
obtaining the zero sequence voltage at the generator end through an opening triangle of a voltage transformer at the generator end;
and acquiring the neutral point zero sequence voltage through a neutral point grounding transformer secondary load tap.
5. The stator ground protection method of claim 1, wherein calculating reactive power of the generator, third harmonic amplitude of zero sequence voltage at generator end, third harmonic amplitude of zero sequence voltage at neutral point, and third harmonic ratio of zero sequence voltage at generator end and neutral point respectively based on the measured data comprises:
and calculating the reactive power, the third harmonic amplitude of the zero-sequence voltage at the machine end and the third harmonic amplitude of the zero-sequence voltage at the neutral point by adopting a Fourier algorithm according to the measurement data.
6. The stator ground protection method according to claim 1, characterized in that the machine-end and neutral zero-sequence voltage third harmonic ratio value is calculated according to the following formula:
Figure FDA0002504617380000022
k is a third harmonic ratio value of zero-sequence voltage of the machine end and a neutral point; u shapeS0The third harmonic amplitude of the zero sequence voltage at the generator end; u shapeN0The third harmonic amplitude of the neutral zero sequence voltage is obtained.
7. The stator ground protection method according to claim 1, wherein the setting method of the first fixed action threshold comprises:
and setting according to the third harmonic ratio value of the zero sequence voltage of the maximum machine end and the neutral point calculated according to the measured data under the condition of normal operation after the generator is connected to the grid.
8. The stator ground protection method of claim 1, wherein the floating action threshold is calculated according to the following equation:
Figure FDA0002504617380000021
wherein, Kset3Is the floating action threshold; kset2A first fixed motion threshold; krelThe reliability coefficient is generally 2-10; q is the reactive power of the generator, and the absorbed reactive power is negative; pNThe rated active power of the generator.
9. The stator ground protection method according to claim 3, wherein the setting method of the second fixed action threshold comprises:
and setting according to a third harmonic ratio value of zero-sequence voltage of a maximum machine end and a neutral point calculated according to the measured data before the generator is connected to the grid.
10. The stator ground protection method according to claim 2, wherein the setting method of the period of time delay comprises:
and (4) setting according to the action time limit matching with the backup protection of the power grid system ground fault.
11. A stator ground protection device for a salient pole generator, comprising:
the data measurement module is used for acquiring measurement data of the generator, wherein the measurement data comprises generator end three-phase voltage, generator end three-phase current, generator end zero-sequence voltage and neutral point zero-sequence voltage;
the data calculation module is used for calculating the reactive power of the generator, the third harmonic amplitude of the zero-sequence voltage at the generator end, the third harmonic amplitude of the zero-sequence voltage at the neutral point and the third harmonic ratio value of the zero-sequence voltage at the generator end and the neutral point respectively according to the measurement data;
the first judgment module is used for judging that the generator set stator ground fault occurs if the calculated third harmonic ratio value of the zero sequence voltage of the generator end and the neutral point is larger than a set first fixed action threshold when the generator is connected to the grid and generates reactive power;
and the second judgment module is used for judging that the generator stator ground fault occurs if the calculated third harmonic ratio value of the zero sequence voltage of the generator end and the neutral point is greater than a set floating action threshold when the generator is connected to the grid and absorbs reactive power.
12. The stator ground protection device of claim 11, further comprising:
and the protection action module is used for acting on a signal or acting on tripping after a period of time delay after the grounding fault of the stator of the unit is judged.
13. The stator ground protection device of claim 11, further comprising:
and the third judgment module is used for judging that the generator set stator ground fault exists if the calculated third harmonic ratio value of the zero-sequence voltage of the generator end and the neutral point is greater than a set second fixed action threshold before the generator is connected to the grid.
14. An electronic device for stator ground protection of a salient pole generator, comprising:
one or more processors;
storage means for storing one or more programs;
when executed by the one or more processors, cause the one or more processors to implement the method of any one of claims 1-10.
15. A computer-readable medium, on which a computer program is stored, which, when being executed by a processor, carries out the method according to any one of claims 1-10.
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