CN118412822B - Method and system for eliminating ferromagnetic resonance of distribution network protected by three-phase isolation transformer - Google Patents
Method and system for eliminating ferromagnetic resonance of distribution network protected by three-phase isolation transformer Download PDFInfo
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- CN118412822B CN118412822B CN202410575741.6A CN202410575741A CN118412822B CN 118412822 B CN118412822 B CN 118412822B CN 202410575741 A CN202410575741 A CN 202410575741A CN 118412822 B CN118412822 B CN 118412822B
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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
- H02H7/04—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 transformers
- H02H7/05—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 transformers for capacitive voltage transformers, e.g. against resonant conditions
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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
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
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Abstract
The invention discloses a method and a system for eliminating ferromagnetic resonance of a power distribution network under the protection of a three-phase isolation transformer, which relate to the technical field of power control and have the technical scheme that: establishing a three-feeder power distribution network model with an isolation transformer arranged at the front end of a feeder; acquiring a zero sequence current signal generated during single-phase earth fault; performing high-frequency filtering treatment on the zero-sequence current signal; detecting step change in the zero sequence current signal after the high-frequency filtering treatment, and controlling the circuit breaker to be closed when the step change of the zero sequence current signal is detected, so as to connect the damping resistor to the voltage transformer; detecting the change condition of step change in the zero sequence current signal after the damping resistor is connected to the voltage transformer, and controlling the delay disconnection of the circuit breaker according to the change condition. According to the invention, after the power distribution network fault occurs, the damping resistor is connected to the voltage transformer to eliminate ferromagnetic resonance phenomenon, so that electric energy loss during non-fault period is avoided.
Description
Technical Field
The invention relates to the technical field of power control, in particular to a method and a system for eliminating ferromagnetic resonance of a power distribution network under the protection of a three-phase isolation transformer.
Background
In low-density population areas, the coverage rate of forest and grasslands is high, and the environmental meteorological conditions are severe. Some 10kV distribution lines or branch lines in the areas pass through grassland forests to supply power to distant resident settlement points, so that the distribution capacity is very small and is between tens of kilowatts and hundreds of kilowatts, meanwhile, the intrinsic safety level of equipment is poor, the operation and maintenance are very difficult, and the risk of initiating mountain fires after faults occur is very high. Through statistics, the single-phase ground fault probability is up to 60 percent, intermittent charge is accompanied, the temperature rapidly rises in a short time, and the forest fire is easy to trigger. And when the ground fault resistance is higher, the traditional ground fault treatment technology has low line selection accuracy.
Therefore, in the prior art, a three-phase isolation transformer is adopted to block the coupling association relation of the zero sequence network among 10kV feeder lines, so that the fault current of a non-fault element flowing through a fault point due to voltage lifting under the ground fault is reduced, the corresponding zero sequence current is obviously improved, and the single-phase ground fault is easier to identify. However, as the three-phase isolation transformer isolates each feeder line of the transformer substation into an independent small-sized sub-network, the capacitance to ground of each feeder line is reduced, and therefore the capacitance to ground on the feeder line is easier to generate ferromagnetic resonance with the voltage transformer after the single-phase ground fault is eliminated.
Therefore, how to study and design a method and a system for eliminating ferromagnetic resonance of a power distribution network under the protection of a three-phase isolation transformer, which can overcome the defects, is a problem which needs to be solved at present.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide the method and the system for eliminating the ferromagnetic resonance of the power distribution network under the protection of the three-phase isolation transformer, which are used for monitoring single-phase grounding faults based on zero-sequence current change, adopting morphological filtering to remove high-frequency components and taking the high-frequency components as input signals to a control module, controlling a circuit breaker between a voltage transformer and a ferromagnetic resonance elimination device by the control module according to the input signals, and automatically switching in a damping resistor on the voltage transformer after the power distribution network faults so as to eliminate the ferromagnetic resonance phenomenon, thereby avoiding electric energy loss in a non-fault period.
The technical aim of the invention is realized by the following technical scheme:
In a first aspect, a method for eliminating ferromagnetic resonance of a power distribution network under protection of a three-phase isolation transformer is provided, which comprises the following steps:
Establishing a three-feeder power distribution network model with an isolation transformer arranged at the front end of a feeder;
acquiring a zero sequence current signal generated during single-phase earth fault;
Performing high-frequency filtering treatment on the zero-sequence current signal;
Detecting step change in the zero sequence current signal after the high-frequency filtering treatment, and controlling the circuit breaker to be closed when the step change of the zero sequence current signal is detected, so as to connect the damping resistor to the voltage transformer;
Detecting the change condition of step change in the zero sequence current signal after the damping resistor is connected to the voltage transformer, and controlling the delay disconnection of the circuit breaker according to the change condition.
Furthermore, the zero sequence current signal is subjected to high-frequency filtering treatment by morphological filtering.
Furthermore, the expression of the high-frequency filtering processing of the zero sequence current signal by adopting morphological filtering is specifically as follows:
wherein N r represents a zero sequence current signal after filtering high-frequency noise; i 0 denotes the zero sequence current signal; beta represents a three-point line type structural element in morphological filtering; expansion and erosion operations of β to signal I 0 in morphological filtering are shown, respectively.
Further, the expansion operation expression of β to the signal I 0 in the morphological filtering is specifically:
Wherein I 0b represents a subset of I 0 that is aligned with β; A mirrored set representing β; beta x represents a sub-structural element of structural element beta at a specific position x;
The corrosion operation expression of beta to the signal I 0 in the morphological filtering is specifically as follows:
Wherein I 0b represents a subset of I 0 that is aligned with β; beta x denotes a substructure element representing the structural element beta at a specific position x.
Further, the damping resistance is not smaller than a preset lower limit value, and a calculation expression of the preset lower limit value is as follows:
wherein R represents a preset lower limit value of the damping resistor; u S represents the rated voltage of the secondary side of the voltage transformer; k represents a factor between 0.25 and 1; p t denotes the rated output power of the voltage transformer; p m denotes the power required for the voltage transformer measurement.
Further, if the change condition of the step change is that the signal with the step change is detected to disappear, the circuit breaker is controlled to be disconnected after delaying for a first preset time;
If the change condition of the step change is that the signal with the step change is detected not to disappear and the step change is continuously generated for a plurality of times, the circuit breaker is controlled to be opened after a second preset time is delayed.
Further, the second preset time is longer than the first preset time.
In a second aspect, a ferromagnetic resonance elimination system of a power distribution network under the protection of a three-phase isolation transformer is provided, and the system is used for implementing the ferromagnetic resonance elimination method of the power distribution network under the protection of the three-phase isolation transformer according to any one of the first aspect, and the method comprises a three-feeder power distribution network with an isolation transformer and a voltage transformer model;
the voltage transformer model is provided with a current acquisition module, a filtering module, a control module, a relay, a damping resistor and a voltage transformer, wherein the damping resistor is connected with the voltage transformer through the relay;
The current acquisition module is used for acquiring a zero sequence current signal generated when the single-phase earth fault occurs;
the filtering module is used for performing high-frequency filtering processing on the zero-sequence current signal;
The control module is used for detecting step change in the zero sequence current signal after the high-frequency filtering processing, and controlling the circuit breaker to be closed when the step change of the zero sequence current signal is detected, so as to connect the damping resistor to the voltage transformer;
And the circuit breaker is used for detecting the change condition of step change in the zero sequence current signal after the damping resistor is connected to the voltage transformer and controlling the delay disconnection of the circuit breaker according to the change condition.
In a third aspect, a computer terminal is provided, which includes a memory, a processor and a computer program stored in the memory and executable on the processor, where the processor implements the method for removing ferromagnetic resonance of a power distribution network under protection of a three-phase isolation transformer according to any one of the first aspects when the program is executed by the processor.
In a fourth aspect, a computer readable medium is provided, on which a computer program is stored, the computer program being executable by a processor to implement a method for cancelling ferroresonance in a power distribution network under protection of a three-phase isolation transformer according to any one of the first aspects.
Compared with the prior art, the invention has the following beneficial effects:
1. According to the method for eliminating ferromagnetic resonance of the power distribution network under the protection of the three-phase isolation transformer, disclosed by the invention, the single-phase grounding fault is monitored based on zero-sequence current change, the high-frequency component is removed by adopting morphological filtering and is used as an input signal to the control module, the control module controls the circuit breaker between the voltage transformer and the ferromagnetic resonance elimination device according to the input signal, and the damping resistor can be automatically connected to the voltage transformer after the power distribution network fault occurs so as to eliminate the ferromagnetic resonance phenomenon, so that the electric energy loss in a non-fault period is avoided;
2. The invention establishes a simulation model of the distribution network in a remote area, restores the actual running situation of the network under the single-phase earth fault, and simulates and analyzes the influence of the isolation transformer on the ferromagnetic resonance phenomenon generated after the single-phase earth fault of the distribution network is eliminated.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:
FIG. 1 is a schematic diagram of a three-feeder distribution network model in an embodiment of the invention;
FIG. 2 is a schematic diagram of a voltage transformer model in an embodiment of the invention;
FIG. 3 is a flow chart of the operation of the control module in an embodiment of the invention;
FIG. 4 is a schematic diagram showing the results of current and voltage waveforms of the B phases of three feeder lines in the case of cutting off after 0.1s for 0.1s when the B phase of the feeder line 2 is in single-phase ground fault in the embodiment of the present invention;
FIG. 5 is a schematic diagram showing the results of current and voltage waveforms for phase B of three feeders after eliminating isolation transformers on feeders 1, 2 in an embodiment of the present invention;
FIG. 6 is a schematic diagram showing the results of current and voltage waveforms of the three feeder B phases before the ferroresonant cancellation device is enabled after the isolation transformers on the three feeders are eliminated in an embodiment of the present invention;
FIG. 7 is a schematic diagram showing the results of current and voltage waveforms of the B phases of three feeders after the ferroresonant cancellation device is activated after the isolation transformers on the three feeders are eliminated in an embodiment of the present invention.
Detailed Description
For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.
It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly or indirectly connected to the other element.
It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are merely for convenience in describing and simplifying the description based on the orientation or positional relationship shown in the drawings, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
Example 1: the method for eliminating the ferromagnetic resonance of the power distribution network under the protection of the three-phase isolation transformer is realized by the following steps.
Step one: a three-feeder distribution network model with an isolation transformer arranged at the feeder front end is built as shown in fig. 1. PT in fig. 1 is a voltage transformer with a ferroresonance cancellation device, as shown in fig. 2.
It should be noted that, after the isolation transformer is added to the front end of the feeder, frequency division resonance in ferromagnetic resonance is very easy to be caused by single-phase grounding faults, which are the most common faults in the power distribution network. And when the isolation transformer is not added to the front end of the feeder line, the single-phase grounding fault does not cause ferromagnetic resonance.
Step two: and acquiring a zero sequence current signal generated during single-phase earth fault.
Step three: and performing high-frequency filtering treatment on the zero-sequence current signal.
The high-frequency oscillation condition can occur due to zero-sequence current generated during faults, and the follow-up control can be influenced. Thus, morphological filtering is used to filter out the high frequency components before they are input as input signals.
The expression of the zero sequence current signal for high-frequency filtering treatment by adopting morphological filtering is specifically as follows:
wherein N r represents a zero sequence current signal after filtering high-frequency noise; i 0 denotes the zero sequence current signal; beta represents a three-point line type structural element in morphological filtering; expansion and erosion operations of β to signal I 0 in morphological filtering are shown, respectively.
The expansion operation expression of beta to the signal I 0 in morphological filtering is specifically as follows:
Wherein I 0b represents a subset of I 0 that is aligned with β; A mirrored set representing β; beta x denotes a substructure element of the structural element beta at a specific position x.
The corrosion operation expression of beta to the signal I 0 in morphological filtering is specifically as follows:
wherein I 0b represents a subset of I 0 that is aligned with β; beta x denotes a substructure element of the structural element beta at a specific position x.
Step four: and detecting step change in the zero-sequence current signal after the high-frequency filtering treatment, and controlling the circuit breaker to be closed when the step change of the zero-sequence current signal is detected, so as to connect the damping resistor to the voltage transformer.
The damping resistance in fig. 2 is not smaller than a preset lower limit value, and the calculation expression of the preset lower limit value is:
wherein R represents a preset lower limit value of the damping resistor; u S represents the rated voltage of the secondary side of the voltage transformer; k represents a factor between 0.25 and 1; p t denotes the rated output power of the voltage transformer; p m denotes the power required for the voltage transformer measurement.
Step five: as shown in fig. 3, after the damping resistor is connected to the voltage transformer, detecting the change condition of step change in the zero sequence current signal, and controlling the delay of the circuit breaker to be opened according to the change condition.
Specifically, if the change condition of the step change is that the signal with the step change disappears is detected, the circuit breaker is controlled to be opened after delaying for a first preset time; if the change condition of the step change is that the signal with the step change is detected to be not disappeared and a plurality of step changes are continuously generated, the circuit breaker is controlled to be opened after the second preset time is delayed.
The second preset time is longer than the first preset time, for example, the first preset time is 2s, the second preset time is 12s, and the multiple step changes can be more than 5 continuous step changes.
In order to verify the effectiveness of the present invention, the system shown in fig. 1 is used as a simulation system, and three feeder lines are named as a feeder line 1, a feeder line 2 and a feeder line 3 from left to right. All simulated ground fault resistances in the present invention were set to 5kΩ. First, the effect of the isolation transformer on the system was verified, and the ferroresonance cancellation transpose was not enabled in the simulation system shown in fig. 1. At 0.1s, single-phase ground fault occurs in phase B of feeder 2, which is cut off after 0.1 s. The current and voltage waveforms of phase B of the three feeders are shown in fig. 4.
As can be seen in fig. 4, the B phase of the feed line 2 undergoes ferromagnetic resonance after fault removal. And the generated fault current and fault voltage cannot propagate to other feeder lines due to the existence of the isolation transformer.
And deleting the isolation transformers on the feeder lines 1 and 2, and performing simulation experiments again according to the working conditions, wherein the waveforms of the B-phase currents and the B-phase voltages of the three feeder lines are shown in figure 5.
It can be seen in fig. 5 that if there is no isolation transformer between the feeders 1, 2, fault currents, voltages will propagate randomly between the feeders.
The effectiveness of the ferromagnetic resonance elimination device provided by the invention is further verified. In the process, in order to facilitate observation and control of variables, the isolation transformers on the three feeder lines are first deleted for simulation. At 0.1s, a single phase ground fault occurs in phase B of feeder 2 for 0.1s. The waveforms of the current and voltage of the B phase of the three feeder lines before and after the ferromagnetic resonance elimination device is started are shown in fig. 6 and 7.
As can be seen from fig. 6 and 7, after the ferromagnetic resonance elimination device provided by the invention is started, resonance phenomenon is obviously improved, and the state before the fault is recovered soon after the single-phase grounding fault is removed.
Example 2: the system for eliminating the ferromagnetic resonance of the power distribution network under the protection of the three-phase isolation transformer is used for realizing the method for eliminating the ferromagnetic resonance of the power distribution network under the protection of the three-phase isolation transformer, and comprises a three-feeder power distribution network with the isolation transformer and a voltage transformer model as shown in fig. 1 and 2.
The voltage transformer model is provided with a current acquisition module, a filtering module, a control module, a relay, a damping resistor and a voltage transformer, wherein the damping resistor is connected with the voltage transformer through the relay.
The current acquisition module is used for acquiring a zero sequence current signal generated during single-phase earth fault; the filtering module is used for performing high-frequency filtering processing on the zero-sequence current signal; the control module is used for detecting step change in the zero sequence current signal after the high-frequency filtering processing, and controlling the circuit breaker to be closed when the step change of the zero sequence current signal is detected, so as to connect the damping resistor to the voltage transformer; and the circuit breaker is used for detecting the change condition of step change in the zero sequence current signal after the damping resistor is connected to the voltage transformer and controlling the delay disconnection of the circuit breaker according to the change condition.
The invention also discloses a computer terminal which comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor realizes the method for eliminating the ferromagnetic resonance of the power distribution network under the protection of the three-phase isolation transformer as described in the embodiment 1 when executing the program.
The present invention also describes a computer readable medium having a computer program stored thereon, the computer program being executed by a processor to implement the method for canceling ferroresonance of a power distribution network under protection of a three-phase isolation transformer as described in embodiment 1.
Working principle: according to the method for eliminating ferromagnetic resonance of the power distribution network under the protection of the three-phase isolation transformer, disclosed by the invention, the single-phase grounding fault is monitored based on zero-sequence current change, the high-frequency component is removed by adopting morphological filtering and is used as an input signal to the control module, the control module controls the circuit breaker between the voltage transformer and the ferromagnetic resonance elimination device according to the input signal, and the damping resistor can be automatically connected to the voltage transformer after the power distribution network fault occurs so as to eliminate the ferromagnetic resonance phenomenon, so that the electric energy loss in a non-fault period is avoided; the invention establishes a simulation model of the distribution network in a remote area, restores the actual running situation of the network under the single-phase earth fault, and simulates and analyzes the influence of the isolation transformer on the ferromagnetic resonance phenomenon generated after the single-phase earth fault of the distribution network is eliminated.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (9)
1. The method for eliminating the ferromagnetic resonance of the power distribution network under the protection of the three-phase isolation transformer is characterized by comprising the following steps of:
Establishing a three-feeder power distribution network model with an isolation transformer arranged at the front end of a feeder;
acquiring a zero sequence current signal generated during single-phase earth fault;
Performing high-frequency filtering treatment on the zero-sequence current signal;
Detecting step change in the zero sequence current signal after the high-frequency filtering treatment, and controlling the circuit breaker to be closed when the step change of the zero sequence current signal is detected, so as to connect the damping resistor to the voltage transformer;
Detecting the change condition of step change in a zero sequence current signal after the damping resistor is connected to the voltage transformer, and controlling the delay disconnection of the circuit breaker according to the change condition;
If the change condition of the step change is that the signal with the step change is detected to disappear, the circuit breaker is controlled to be disconnected after delaying for a first preset time;
If the change condition of the step change is that the signal with the step change is detected not to disappear and the step change is continuously generated for a plurality of times, the circuit breaker is controlled to be opened after a second preset time is delayed.
2. The method for eliminating ferromagnetic resonance of power distribution network under protection of three-phase isolation transformer according to claim 1, wherein the zero sequence current signal is subjected to high-frequency filtering treatment by morphological filtering.
3. The method for eliminating ferromagnetic resonance of power distribution network under protection of three-phase isolation transformer according to claim 2, wherein the expression of performing high-frequency filtering treatment on the zero-sequence current signal by adopting morphological filtering is specifically as follows:
wherein N r represents a zero sequence current signal after filtering high-frequency noise; i 0 denotes the zero sequence current signal; beta represents a three-point line type structural element in morphological filtering; expansion and erosion operations of β to signal I 0 in morphological filtering are shown, respectively.
4. The method for eliminating ferromagnetic resonance of power distribution network under protection of three-phase isolation transformer according to claim 3, wherein the expansion operation expression of β pair signal I 0 in morphological filtering is specifically:
Wherein I 0b represents a subset of I 0 that is aligned with β; A mirrored set representing β; beta x represents a sub-structural element of structural element beta at a specific position x;
The corrosion operation expression of beta to the signal I 0 in the morphological filtering is specifically as follows:
wherein I 0b represents a subset of I 0 that is aligned with β; beta x denotes a substructure element of the structural element beta at a specific position x.
5. The method for eliminating ferromagnetic resonance of power distribution network under protection of three-phase isolation transformer according to claim 1, wherein the damping resistance is not smaller than a preset lower limit value, and the calculation expression of the preset lower limit value is:
wherein R represents a preset lower limit value of the damping resistor; u S represents the rated voltage of the secondary side of the voltage transformer; k represents a factor between 0.25 and 1; p t denotes the rated output power of the voltage transformer; p m denotes the power required for the voltage transformer measurement.
6. The method for canceling ferroresonance of a power distribution network under protection of a three-phase isolation transformer according to claim 1, wherein the second preset time is longer than the first preset time.
7. The system is used for realizing the method for eliminating the ferromagnetic resonance of the power distribution network under the protection of the three-phase isolation transformer, and comprises a three-feeder power distribution network with the isolation transformer and a voltage transformer model;
the voltage transformer model is provided with a current acquisition module, a filtering module, a control module, a relay, a damping resistor and a voltage transformer, wherein the damping resistor is connected with the voltage transformer through the relay;
The current acquisition module is used for acquiring a zero sequence current signal generated when the single-phase earth fault occurs;
the filtering module is used for performing high-frequency filtering processing on the zero-sequence current signal;
The control module is used for detecting step change in the zero sequence current signal after the high-frequency filtering processing, and controlling the circuit breaker to be closed when the step change of the zero sequence current signal is detected, so as to connect the damping resistor to the voltage transformer;
And the circuit breaker is used for detecting the change condition of step change in the zero sequence current signal after the damping resistor is connected to the voltage transformer and controlling the delay disconnection of the circuit breaker according to the change condition.
8. A computer terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements a method for cancelling ferroresonance in a distribution network under protection of a three-phase isolation transformer according to any one of claims 1-6 when executing the program.
9. A computer readable medium having stored thereon a computer program, wherein the computer program is executed by a processor to implement a method for cancelling ferroresonance in a power distribution network under protection of a three-phase isolation transformer according to any one of claims 1-6.
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| US10222409B2 (en) * | 2013-03-29 | 2019-03-05 | Beijing Inhand Networks Technology Co., Ltd. | Method and system for detecting and locating single-phase ground fault on low current grounded power-distribution network |
| CN110445109B (en) * | 2018-05-04 | 2022-03-29 | 南京南瑞继保电气有限公司 | Method and device for rapidly eliminating ferromagnetic resonance of voltage transformer |
| CN114512969A (en) * | 2022-04-06 | 2022-05-17 | 李景禄 | Grounding fault processing method for resonance grounding power grid and direct-distribution resistance grounding power plant |
| CN115296263B (en) * | 2022-08-19 | 2023-05-16 | 云南电网有限责任公司曲靖供电局 | PID-regulated ferromagnetic resonance elimination method for voltage transformer with active matching resistor |
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| CN101242097A (en) * | 2008-03-11 | 2008-08-13 | 昆明理工大学 | Fault line selection method for small current grounding system based on zero-mode current measurement and simulation |
| CN103840437A (en) * | 2014-03-15 | 2014-06-04 | 李景禄 | Quick diagnostic and processing method of power distribution network ferromagnetic resonance and one-phase earth faults |
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