CN113708343B - 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 PDFInfo
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- CN113708343B CN113708343B CN202010442320.8A CN202010442320A CN113708343B CN 113708343 B CN113708343 B CN 113708343B CN 202010442320 A CN202010442320 A CN 202010442320A CN 113708343 B CN113708343 B CN 113708343B
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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
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- 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
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- 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
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- 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
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- 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
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- 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
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- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Eletrric Generators (AREA)
- Protection Of Generators And Motors (AREA)
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; calculating reactive power of the generator, machine end zero sequence voltage third harmonic amplitude, neutral point zero sequence voltage third harmonic amplitude and machine end and neutral point zero sequence voltage third harmonic ratio value according to the measurement data; when the generator is connected with the grid and generates reactive power, if the ratio value of the zero sequence voltage third harmonic of the machine end and the neutral point is larger than a set first fixed action threshold, determining that the stator is in ground fault; and when the generator is connected with the grid and absorbs reactive power, if the ratio value of the zero sequence voltage third harmonic of the machine end and the neutral point is larger than a set floating action threshold, determining that the stator is in ground fault. And in the phase advance operation stage, a floating action threshold which is automatically lifted along with the increase of reactive power is adopted, so that the reliability of the grounding protection of the stator is improved.
Description
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 of the generator stator windings will cause single-phase ground faults. Single-phase-to-earth faults are the most common type of faults for generators. In order to ensure safe and stable operation of the generator set, the fundamental zero sequence voltage stator grounding protection is matched with the third harmonic voltage ratio stator grounding protection to form 100% grounding fault protection of the generator stator winding. The fundamental wave zero sequence voltage stator ground protection reflects the ground fault within 85% of the generator end, and the third harmonic voltage ratio stator ground protection reflects the ground fault within 25% of the generator neutral point.
When salient pole generators, such as water turbines, carry inductive reactive power, the longitudinal axis armature reaction plays a role in assisting the magnetic potential of the third harmonic, so that the third harmonic of the zero sequence voltage at the machine end and the third harmonic of the zero sequence voltage at the neutral point are increased. Therefore, the magnitude of the third harmonic of the zero sequence voltage of the generator set is greatly influenced by reactive power. When the generator set is in a phase advance operation stage, the machine end zero sequence voltage third harmonic and the neutral point zero sequence voltage third harmonic are increased, and the machine end and the neutral point zero sequence voltage third harmonic voltage ratio value are synchronously increased. Moreover, the deeper the phase advance, the larger the value of the third harmonic voltage ratio of the zero sequence voltage at the machine end and the neutral point is, which causes the reliability of the third harmonic voltage ratio stator grounding protection to be reduced, and even causes the situation of false alarm or false tripping of the third harmonic voltage ratio stator grounding protection.
Disclosure of Invention
The application aims to provide a stator grounding protection method for a salient pole generator, which is characterized in that the running state of a generator set is subjected to sectional treatment, and a floating action threshold technology which is automatically lifted along with the increase of reactive power is adopted for a phase-entering running stage, so that the reliability of the stator grounding protection of the third harmonic voltage ratio of the generator set under the phase-entering running is improved.
According to an aspect of the present application, there is provided 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;
calculating reactive power of the generator, machine end zero sequence voltage third harmonic amplitude, neutral point zero sequence voltage third harmonic amplitude and machine end and neutral point zero sequence voltage third harmonic ratio value according to the measurement data;
when the generator is connected with the grid and generates reactive power, if the calculated zero sequence voltage third harmonic ratio value of the machine end and the neutral point is larger than a set first fixed action threshold, judging that the stator of the generator set is grounded;
and when the generator is connected with the grid and absorbs reactive power, if the calculated zero sequence voltage third harmonic ratio value of the machine end and the neutral point is larger than a set floating action threshold, judging that the stator of the unit is grounded.
According to some embodiments of the application, the protection method further comprises:
after the ground fault of the stator of the unit is judged, the unit acts on a signal or acts on tripping after a period of time delay.
According to some embodiments of the application, the protection method further comprises:
and before grid connection of the generator, if the calculated zero sequence voltage third harmonic ratio value of the machine end and the neutral point is larger than a set second fixed action threshold, judging that the stator of the generator set is grounded.
According to some embodiments of the application, obtaining measurement data of the generator including machine side three-phase voltage, machine side three-phase current, machine side zero sequence voltage, neutral point zero sequence voltage includes:
acquiring the three-phase voltage of the machine end through a machine end voltage transformer;
acquiring the three-phase current of the machine end through a machine end current transformer;
acquiring the machine end zero sequence voltage through an opening triangle of a machine end voltage transformer;
and obtaining the neutral point zero sequence voltage through a neutral point grounding secondary load tap.
According to some embodiments of the application, calculating reactive power of the generator, machine side zero sequence voltage third harmonic amplitude, neutral point zero sequence voltage third harmonic amplitude, machine side and neutral point zero sequence voltage third harmonic ratio value according to the measurement data respectively includes:
and calculating the reactive power, the machine end zero sequence voltage third harmonic amplitude and the neutral point zero sequence voltage third harmonic amplitude by adopting a Fourier algorithm according to the measurement data.
According to some embodiments of the application, the machine side and neutral point zero sequence voltage third harmonic ratio value is calculated according to the following formula:
k is the third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point; u (U) S0 The amplitude of the third harmonic is the zero sequence voltage at the machine end; u (U) N0 Is the third harmonic amplitude of the zero sequence voltage of the neutral point.
According to some embodiments of the application, the method for setting the first fixed action threshold includes:
and under the condition of normal operation after grid connection of the generator is avoided, setting is carried out according to the calculated third harmonic ratio value of the maximum machine end and the neutral point zero sequence voltage according to the measured data.
According to some embodiments of the application, the floating action threshold is calculated according to the following formula:
wherein K is set3 Thresholding said float; k (K) set2 Is a first fixed action threshold; k (K) rel Taking 2-10 as a reliable coefficient; q is the reactive power of the generator, and the absorbed reactive power is negative; p (P) N Rated for active power of the generator.
According to some embodiments of the application, the method for setting the second fixed action threshold includes:
and before grid connection of the generator is avoided, setting is carried out according to the calculated third harmonic ratio value of the zero sequence voltage of the maximum machine end and the neutral point according to the measured data.
According to some embodiments of the present application, the method for setting a delay includes:
and setting according to the cooperation of the backup protection action time limit of the ground fault of the power grid system.
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 obtaining measurement data of the generator, wherein the measurement data comprise machine end three-phase voltage, machine end three-phase current, machine end zero sequence voltage and neutral point zero sequence voltage;
the data calculation module is used for respectively calculating reactive power of the generator, machine end zero sequence voltage third harmonic amplitude, neutral point zero sequence voltage third harmonic amplitude and machine end and neutral point zero sequence voltage third harmonic ratio value according to the measurement data;
the first judging module is used for judging that the stator of the unit has a ground fault if the calculated third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point is larger than a set first fixed action threshold when reactive power is generated after the generator is connected;
and the second judging module is used for judging that the stator of the unit has a ground fault if the calculated third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point is larger than a set floating action threshold when the reactive power is absorbed after the generator is connected.
According to some embodiments of the application, the protection device further comprises:
and the protection action module is used for judging that after the grounding fault of the stator of the unit, the protection action module acts on a signal or acts on tripping after a period of time delay.
According to some embodiments of the application, the protection device further comprises:
and the third judging module is used for judging that the stator of the unit has a grounding fault if the calculated zero sequence voltage third harmonic ratio value of the machine end and the neutral point is larger than a set second fixed action threshold before the generator is connected.
According to another aspect of the present application, there is provided an electronic apparatus for stator ground protection of a salient pole generator, comprising:
one or more processors;
a storage means for storing one or more programs;
when the one or more programs are executed by the one or more processors, the one or more processors are caused 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 stored thereon a computer program, characterized in that the program, when executed by a processor, implements the stator ground protection method described above.
The stator grounding protection method for the salient pole generator aims at the risk of false alarm or false tripping in the phase advance operation stage of the existing third harmonic voltage ratio stator grounding protection of the salient pole generator, and adopts a segmentation processing scheme and a floating action threshold technology for the third harmonic voltage ratio stator grounding protection of the salient pole generator, so that the sensitivity of the stator grounding protection under the condition of normal operation of the generator is ensured, and the reliability of the grounding protection under the phase advance operation of the generator is improved.
Additional aspects and advantages of the 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 application.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present application.
Fig. 1 shows a flow chart of a stator ground protection method according to an exemplary embodiment of the application.
Fig. 2 shows a flowchart of a stator ground protection method according to another example embodiment of the application.
Fig. 3 illustrates a schematic diagram 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 application.
Fig. 5 shows a block diagram of a stator ground protection device according to another example embodiment of the application.
Fig. 6 shows a block diagram of an electronic device for salient pole generator stator ground protection, according to an illustrative embodiment of the present application.
Detailed Description
Example embodiments are described more fully below with reference to the accompanying drawings. However, the exemplary embodiments may 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 the example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, 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 application may be practiced without one or more of the specific details, or with other methods, components, devices, steps, etc. In other instances, well-known methods, devices, implementations, or operations are not 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 element. Accordingly, a first component discussed below could be termed a second component without departing from the teachings of the present inventive concept. As used herein, the term "and/or" includes any one of the associated listed items and all combinations of one or more.
Those skilled in the art will appreciate that the drawings are schematic representations of example embodiments and may not be to scale. The modules or flow paths in the drawings are not necessarily required to practice the application and therefore should not be taken to limit the scope of the application.
The inventor discovers that when the existing third harmonic voltage ratio stator grounding protection method is adopted to perform stator grounding fault protection on the salient pole generator, because the existing third harmonic voltage ratio stator grounding protection method adopts a fixed action threshold, the protection reliability is reduced and even false alarm or false tripping occurs when the salient pole generator is in a phase-advance operation stage.
Aiming at the problems in the prior art, the inventor provides a stator grounding protection method for a salient pole generator, which is used for carrying out sectional treatment on different operation stages of the generator, wherein the generator is in a phase-entering operation stage, and a floating action threshold technology is adopted for fault judgment, so that the reliability of stator grounding protection is improved.
Fig. 1 shows a flow chart of a stator ground protection method according to an exemplary embodiment of the application.
As shown in fig. 1, the stator grounding protection method for a salient pole generator provided by the application comprises the following steps:
in step S110, measurement data including machine side three-phase voltage, machine side three-phase current, machine side zero-sequence voltage, and neutral point zero-sequence voltage are obtained. Specifically, in the process of acquiring the measurement data, the machine-side three-phase voltage can be acquired through a machine-side voltage transformer; acquiring the three-phase current of the machine end through a machine end current transformer; acquiring the machine end zero sequence voltage through an opening triangle of a machine end voltage transformer; and obtaining the neutral point zero sequence voltage through a neutral point grounding secondary load tap.
In step S120, reactive power of the generator, 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 value are calculated according to the measurement data. After the measurement data are obtained, a Fourier algorithm can be adopted to calculate the reactive power, the machine end zero sequence voltage third harmonic amplitude, the neutral point zero sequence voltage third harmonic amplitude and the machine end and neutral point zero sequence voltage third harmonic ratio value according to the measurement data.
For example, the reactive power can be calculated by a fourier algorithm from the machine side three-phase voltage and the machine side three-phase current. And calculating the third harmonic amplitude of the zero sequence voltage at the machine end by adopting a Fourier algorithm according to the zero sequence voltage at the machine end. Similarly, the third harmonic amplitude of the neutral point zero sequence voltage can be calculated by adopting a Fourier algorithm according to the neutral point zero sequence voltage. The fourier algorithm may be a full-cycle fourier algorithm, a half-cycle fourier algorithm, a windowed fourier algorithm, or the like, which is not limited thereto.
The machine end and neutral point zero sequence voltage third harmonic ratio value is calculated according to the following formula:
k is the third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point; u (U) S0 The amplitude of the third harmonic is the zero sequence voltage at the machine end; u (U) N0 Is the third harmonic amplitude of the zero sequence voltage of the neutral point.
And in step S130, when reactive power is generated after the generator is connected, if the zero sequence voltage third harmonic ratio value of the machine end and the neutral point is larger than a set first fixed action threshold, judging that the stator of the machine set is grounded.
After the generator is connected with the grid, when the unit generates reactive power, the protection discrimination condition of the third harmonic voltage ratio stator ground fault of the generator can be expressed as follows:
k is the third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point; k (K) set2 Setting a first fixed action threshold for the zero sequence voltage third harmonic ratio of the machine end and the neutral point after grid connection according to the maximum zero sequence voltage third harmonic ratio value of the machine end and the neutral point calculated according to the measured data under the condition of normal operation after grid connection of the generator is avoided; u (U) S0 The amplitude of the third harmonic is the zero sequence voltage at the machine end; u (U) N0 The third harmonic amplitude of the zero sequence voltage of the neutral point; q is reactive power of the generator, reactive power is generated, and Q value is positive.
And step S140, when the generator is connected with the grid and absorbs reactive power, if the zero sequence voltage third harmonic ratio value of the machine end and the neutral point is larger than a set floating action threshold, judging that the stator of the machine set is grounded.
After the generator is connected with the grid, when the unit is in a phase advance operation stage, the protection discrimination condition of the third harmonic voltage ratio stator ground fault of the generator can be expressed as follows:
k is the third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point; k (K) set3 Floating an action threshold for the zero sequence voltage third harmonic voltage ratio of the machine end and the neutral point in the phase advancing operation stage; u (U) S0 The amplitude of the third harmonic is the zero sequence voltage at the machine end; u (U) N0 The third harmonic amplitude of the zero sequence voltage of the neutral point; k (K) rel Taking 2-10 as a reliable coefficient; q is power generationReactive power of the machine, and when the reactive power is absorbed, the Q value is negative; p (P) N Rated active power for the generator; k (K) set2 And a first fixed action threshold is set for the third harmonic voltage ratio of the zero sequence voltage of the machine end and the neutral point after grid connection.
From the above-mentioned discrimination conditions, the floating threshold K set3 Not a fixed value, but automatically rises as reactive power increases. The action threshold is associated with the absorbed reactive power, so that the false alarm or false tripping phenomenon caused by adopting a fixed action threshold can be solved.
Fig. 2 shows a flowchart of a stator ground protection method according to another example embodiment of the application.
According to some embodiments of the present application, the present application further provides a method for protecting a stator from ground, including, in addition to the steps shown in fig. 1:
and step S150, before the generator is connected, if the zero sequence voltage third harmonic ratio value of the machine end and the neutral point is larger than a set second fixed action threshold, judging that the stator of the machine set is grounded.
The protection discrimination condition of the third harmonic voltage ratio stator ground fault of the generator before the generator is connected with the grid can be expressed as follows:
k is the third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point; k (K) set1 Setting 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 grid connection of the generator is avoided; u (U) S0 The amplitude of the third harmonic is the zero sequence voltage at the machine end; u (U) N0 Is the third harmonic amplitude of the zero sequence voltage of the neutral point.
After determining the ground fault of the stator of the unit, the signal is activated or the trip is activated after a delay in step S160. After the stator ground fault is judged according to the judging conditions in the steps, the stator ground fault can be acted on a signal to alarm or acted on a trip to cut off the fault after a period of time delay in order to cooperate with the ground fault backup protection of the power grid system. Therefore, the time delay is set according to the backup protection action time limit of the ground fault of the power grid system.
Fig. 3 illustrates a schematic diagram of a stator ground protection method according to an exemplary embodiment of the present application.
U in the figure S0 The amplitude of the third harmonic is the zero sequence voltage at the machine end; u (U) N0 The third harmonic amplitude of the zero sequence voltage of the neutral point; k (K) set1 A second fixed action threshold for the third harmonic voltage ratio before grid connection; k (K) set2 A first fixed action threshold for the third harmonic voltage ratio after grid connection; q is reactive power of the unit, positive when reactive power is generated, and negative when reactive power is absorbed; k (K) rel Taking 2-10 as a reliable coefficient; p (P) N Rated active power for the generator; t is the protection action delay.
As shown in fig. 3, in the method for protecting a stator from the ground, the fault of the stator from the ground of the unit can be judged by three judging conditions, which are respectively:
when the machine set is not connected with the grid, and the zero sequence voltage third harmonic ratio value U of the machine end and the neutral point S0 /U N0 Greater than K set1 When the judgment condition is met;
when the machine set is connected with the grid and generates reactive power, namely Q is more than or equal to 0, and the zero sequence voltage third harmonic ratio value U of the machine end and the neutral point S0 /U N0 Greater than K set2 When the judgment condition is met;
when the unit is connected with the grid and absorbs reactive power, namely Q is smaller than 0, and the zero sequence voltage third harmonic ratio value U of the machine end and the neutral point S0 /U N0 Is greater than (1+K) rel *|Q|/P N )*K set2 When the judgment condition is satisfied.
When any of the above conditions is met, the third harmonic voltage ratio stator protection action is performed after a protection delay t.
Fig. 4 shows a block diagram of a stator ground protection device according to an example embodiment of the application.
According to an exemplary embodiment of the present application, the present application also provides a stator ground protection apparatus 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:
the data measurement module 410 is configured to obtain measurement data of the generator including an on-board three-phase voltage, an on-board three-phase current, an on-board zero-sequence voltage, and a neutral point zero-sequence voltage. The machine-side three-phase voltage can be obtained through a machine-side voltage transformer; the machine-side three-phase current can be obtained through a machine-side current transformer; the machine end zero sequence voltage can be obtained through an opening triangle of a machine end voltage transformer; the neutral point zero sequence voltage can be obtained through a neutral point grounding variable secondary load tap.
The data calculation module 420 calculates reactive power of the generator, machine end zero sequence voltage third harmonic amplitude, neutral point zero sequence voltage third harmonic amplitude and machine end and neutral point zero sequence voltage third harmonic ratio value according to the measurement data. The reactive power can be calculated through a Fourier algorithm according to the machine-side three-phase voltage and the machine-side three-phase current. The machine end zero sequence voltage third harmonic amplitude and the neutral point zero sequence voltage third harmonic amplitude can be calculated through a Fourier algorithm according to the machine end zero sequence voltage and the neutral point zero sequence voltage. The ratio value of the machine end zero sequence voltage third harmonic and the neutral point zero sequence voltage third harmonic is the ratio of the machine end zero sequence voltage third harmonic amplitude and the neutral point zero sequence voltage third harmonic amplitude.
And the first judging module 430 is configured to judge that the stator of the unit has a ground fault if the calculated third harmonic ratio value of the zero sequence voltage of the machine side and the neutral point is greater than a set first fixed action threshold when the reactive power is generated after the generator is connected. And the first fixed action threshold is set according to the maximum machine end and neutral point zero sequence voltage third harmonic ratio value calculated according to the measured data under the condition of normal operation after the generator is hidden from grid connection.
And the second judging module 440 is configured to judge that the stator of the unit has a ground fault if the calculated third harmonic ratio value of the zero sequence voltage of the machine side and the neutral point is greater than a set floating action threshold when the reactive power is absorbed after the generator is connected. The floating action threshold is calculated according to the following formula:
wherein K is set3 A threshold for the floating action; k (K) set2 Is a first fixed action threshold; k (K) rel Taking 2-10 as a reliable coefficient; q is the reactive power of the generator, and the absorbed reactive power is negative; p (P) N Rated for active power of the generator.
Fig. 5 shows a block diagram of a stator ground protection device according to another example embodiment of the application.
According to another embodiment of the present application, the stator grounding protection apparatus 400 provided by the present application may further include a third judging module 450 and a protection action module 460 in addition to the modules described in fig. 4.
And the third judging module 450 is configured to judge that the stator of the unit has a ground fault if the calculated zero sequence voltage third harmonic ratio value of the machine end and the neutral point is greater than a set second fixed action threshold before the generator is connected. And before grid connection of the generator is avoided, the second fixed action threshold is set according to the calculated maximum machine end and neutral point zero sequence voltage third harmonic ratio value according to the measured data.
The protection action module 460 is used for determining that the unit stator is in a ground fault, and then acts on a signal or trips after a delay. The time delay is set in a matched mode according to the backup protection action time limit of the ground fault of the power grid system.
Fig. 6 shows a block diagram of an electronic device for salient pole generator stator ground protection, according to an illustrative embodiment of the present application.
The application also 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 be construed as limiting the function and scope of use of the embodiment 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 connecting the different system components, including the memory unit 720 and the processing unit 710, etc.
The storage unit 720 stores program codes that can be executed by the processing unit 710, so that the processing unit 710 performs the methods according to the above-described embodiments of the present application described in the present specification.
The memory unit 720 may include readable media in the form of volatile memory units, such as Random Access Memory (RAM) 7201 and/or cache memory 7202, and may further include Read Only Memory (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 or some combination of which may include an implementation of a network environment.
Bus 730 may be a bus representing 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.), one or more devices that enable a user to interact with the electronic device 700, and/or any device (e.g., router, modem, etc.) that enables the electronic device 700 to communicate with one or more other computing devices. Such communication may occur through an input/output (I/O) interface 750. Also, electronic device 700 may communicate with one or more networks such as a Local Area Network (LAN), a Wide Area Network (WAN) and/or a public network, such as the Internet, through network adapter 760. Network adapter 760 may communicate with other modules of electronic device 700 via bus 730. It should be appreciated that although not shown, other hardware and/or software modules may be used in connection with electronic device 700, including, but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, data backup storage systems, and the like.
Furthermore, the present application provides a computer readable medium having stored thereon a computer program, characterized in that the program, when executed by a processor, implements the above-mentioned stator ground protection method for a salient pole generator.
It is apparent that the above examples are only illustrative of the present application and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present application.
Claims (13)
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;
calculating reactive power of the generator, machine end zero sequence voltage third harmonic amplitude, neutral point zero sequence voltage third harmonic amplitude and machine end and neutral point zero sequence voltage third harmonic ratio value according to the measurement data;
when the generator is connected with the grid and generates reactive power, if the ratio value of the zero sequence voltage third harmonic of the machine end and the neutral point is larger than a set first fixed action threshold, judging that the stator of the generator set is grounded;
after the generator is connected with the grid, when the unit generates reactive power, the protection discrimination condition of the third harmonic voltage ratio stator ground fault of the generator can be expressed as follows:
wherein K is set2 Setting a first fixed action threshold for the third harmonic ratio of the zero sequence voltage of the machine end and the neutral point after grid connection according to the maximum value calculated according to the measured data under the condition of normal operation after grid connection of the generator is avoided; q is the reactive power of the generator, and when the reactive power is generated, the Q value is positive;
when the generator is connected with the grid and absorbs reactive power, if the ratio value of the zero sequence voltage third harmonic of the machine end and the neutral point is larger than a set floating action threshold, judging that the stator of the unit is grounded;
after the generator is connected with the grid, when the unit is in a phase advance operation stage, the protection discrimination condition of the third harmonic voltage ratio stator ground fault of the generator can be expressed as follows:
k is the third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point; k (K) set3 Floating an action threshold for the zero sequence voltage third harmonic voltage ratio of the machine end and the neutral point in the phase advancing operation stage; u (U) S0 The third harmonic amplitude of the zero sequence voltage at the machine end is set; u (U) N0 Third harmonic amplitude of the neutral point zero sequence voltage; k (K) rel The value is 2-10 as the reliable coefficient; q is the reactive power of the generator, and when the reactive power is absorbed, the Q value is negative; p (P) N Rated for active power of the generator.
2. The stator ground protection method of claim 1, further comprising:
after the ground fault of the stator of the unit is judged, the unit acts on a signal or acts on tripping after a period of time delay.
3. The stator ground protection method of claim 1, further comprising:
and before grid connection of the generator, if the zero sequence voltage third harmonic ratio value of the machine end and the neutral point is larger than a set second fixed action threshold, judging that the stator of the unit is grounded.
4. The stator ground protection method according to claim 1, wherein obtaining measurement data of the generator including machine side three-phase voltage, machine side three-phase current, machine side zero-sequence voltage, neutral point zero-sequence voltage, comprises:
acquiring the three-phase voltage of the machine end through a machine end voltage transformer;
acquiring the three-phase current of the machine end through a machine end current transformer;
acquiring the machine end zero sequence voltage through an opening triangle of a machine end voltage transformer;
and obtaining the neutral point zero sequence voltage through a neutral point grounding secondary load tap.
5. The stator ground protection method according to claim 1, wherein calculating reactive power, machine side zero sequence voltage third harmonic amplitude, neutral point zero sequence voltage third harmonic amplitude, machine side and neutral point zero sequence voltage third harmonic ratio value of the generator, respectively, from the measurement data comprises:
and calculating the reactive power, the machine end zero sequence voltage third harmonic amplitude and the neutral point zero sequence voltage third harmonic amplitude by adopting a Fourier algorithm according to the measurement data.
6. The method of claim 1, wherein the method of setting the first fixed action threshold comprises:
and under the condition of normal operation after grid connection of the generator is avoided, setting is carried out according to the calculated third harmonic ratio value of the maximum machine end and the neutral point zero sequence voltage according to the measured data.
7. The method of claim 3, wherein the second fixed action threshold setting method comprises:
and before grid connection of the generator is avoided, setting is carried out according to the calculated third harmonic ratio value of the zero sequence voltage of the maximum machine end and the neutral point according to the measured data.
8. The method for protecting a stator ground according to claim 2, wherein the method for setting the one-stage delay comprises:
and (5) matching and setting according to the backup protection action time limit of the ground fault of the power grid system.
9. A stator ground protection device for a salient pole generator, comprising:
the data measurement module is used for obtaining measurement data of the generator, wherein the measurement data comprise machine end three-phase voltage, machine end three-phase current, machine end zero sequence voltage and neutral point zero sequence voltage;
the data calculation module is used for respectively calculating reactive power of the generator, machine end zero sequence voltage third harmonic amplitude, neutral point zero sequence voltage third harmonic amplitude and machine end and neutral point zero sequence voltage third harmonic ratio value according to the measurement data;
the first judging module is used for judging that the stator of the unit has a ground fault if the calculated third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point is larger than a set first fixed action threshold when reactive power is generated after the generator is connected;
after the generator is connected with the grid, when the unit generates reactive power, the protection discrimination condition of the third harmonic voltage ratio stator ground fault of the generator can be expressed as follows:
wherein K is set2 Setting a first fixed action threshold for the third harmonic ratio of the zero sequence voltage of the machine end and the neutral point after grid connection according to the maximum value calculated according to the measured data under the condition of normal operation after grid connection of the generator is avoided; q is the reactive power of the generator, and when the reactive power is generated, the Q value is positive;
the second judging module is used for judging that the stator of the unit has a ground fault if the calculated third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point is larger than a set floating action threshold when the reactive power is absorbed after the generator is connected;
after the generator is connected with the grid, when the unit is in a phase advance operation stage, the protection discrimination condition of the third harmonic voltage ratio stator ground fault of the generator can be expressed as follows:
k is the third harmonic ratio value of the zero sequence voltage of the machine end and the neutral point; k (K) set3 Floating an action threshold for the zero sequence voltage third harmonic voltage ratio of the machine end and the neutral point in the phase advancing operation stage; u (U) S0 The third harmonic amplitude of the zero sequence voltage at the machine end is set; u (U) N0 Third harmonic amplitude of the neutral point zero sequence voltage; k (K) rel The value is 2-10 as the reliable coefficient; q is the reactive power of the generator, and when the reactive power is absorbed, the Q value is negative; p (P) N Rated for active power of the generator.
10. The stator ground protection device of claim 9, further comprising:
and the protection action module is used for judging that after the grounding fault of the stator of the unit, the protection action module acts on a signal or acts on tripping after a period of time delay.
11. The stator ground protection device of claim 9, further comprising:
and the third judging module is used for judging that the stator of the unit has a grounding fault if the calculated zero sequence voltage third harmonic ratio value of the machine end and the neutral point is larger than a set second fixed action threshold before the generator is connected.
12. An electronic device for stator ground protection of a salient pole generator, comprising:
one or more processors;
a storage means for storing one or more programs;
when executed by the one or more processors, causes the one or more processors to implement the method of any of claims 1-8.
13. A computer readable medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the method according to any of claims 1-8.
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