A relay protection method and device

Abstract

The embodiment of the present invention discloses a relay protection method and device, which comprises: obtaining the maximum load current of the line, the voltage and current of a preset protection section in the line before a fault occurs, and the fault voltage and fault current of the preset protection section after a fault occurs; determining the tripping action current according to the voltage and current, the fault voltage and the fault current of the preset protection section before a fault occurs, and determining the overcurrent protection current according to the maximum load current; and controlling the state of the relay in the line according to the fault current, the tripping action current and the overcurrent protection current. The relay protection method and device provided by the embodiment of the present invention can improve the reliability of relay protection.

Description

Technical Field

[0001] The embodiments of the present invention relate to relay protection technology, and in particular to a relay protection method and device. Background Art

[0002] In the power system, since the operation mode of the power grid is relatively complex and in a frequently changing state, in order to ensure the safe and reliable operation of the power system, it is necessary to strengthen the maintenance in daily use. The application of relay protection devices can avoid the risks caused by power system failures and maintain the safety of power equipment. As the power system has higher and higher requirements for fault troubleshooting and isolation, the performance requirements for relay protection devices are also getting higher and higher.

[0003] At present, the existing relay protection method usually calculates the setting value of the relay protection offline, and performs relay protection on the power system through the relay protection device according to the calculated setting value. During the operation of the power system, the setting value rarely changes; and when the setting value does not meet the actual relay protection requirements, it is usually necessary to manually modify the setting value multiple times, which affects the reliability of the relay protection. Summary of the invention

[0004] The embodiments of the present invention provide a relay protection method and device to improve the reliability of relay protection.

[0005] In a first aspect, an embodiment of the present invention provides a relay protection method, including:

[0006] Obtain the maximum load current of the line, the voltage and current of the preset protection section in the line before a fault occurs, and the fault voltage and fault current after a fault occurs in the preset protection section;

[0007] Determine the tripping current based on the voltage and current before the fault occurs in the preset protection section, the fault voltage and the fault current, and determine the overcurrent protection current based on the maximum load current;

[0008] Control the state of the relay in the circuit according to the fault current, tripping current and overcurrent protection current.

[0009] Optionally, the tripping action current is determined according to the voltage and current before the fault occurs in the preset protection section, the fault voltage and the fault current, including:

[0010] Determine the comprehensive impedance Zs based on the voltage and current before the fault occurs in the preset protection section, the fault voltage and the fault current;

[0011] Determine the potential Es based on the comprehensive impedance, fault voltage and fault current;

[0012] According to the comprehensive impedance and potential, the tripping action current Iop is determined.

[0013] Optional, Wherein, Umg(1) is the fault voltage component, Umg(1)=Uf(1)-Um, Img(1) is the fault current component, Img(1)=If(1)-Im, Uf(1) is the positive sequence component of the fault voltage, If(1) is the positive sequence component of the fault current, Um and Im are the voltage and current before the fault occurs in the preset protection section respectively; Es=Uf+Zs×If; wherein Uf is the fault voltage and If is the fault current.

[0014] Optional, Among them, Krel is the first reliability coefficient, Kd is the fault coefficient, and Zl is the line impedance.

[0015] Optionally, the state of the relay in the circuit is controlled according to the fault current, tripping current and overcurrent protection current, including:

[0016] When the fault current is greater than or equal to the tripping action current, the control relay trips for quick-break protection;

[0017] When the fault current is less than the tripping action current, if the fault current is greater than or equal to the overcurrent protection current, the control relay will trip for overcurrent protection.

[0018] Optionally, obtaining the voltage and current of a preset protection section in the line before a fault occurs, and the fault voltage and fault current of the preset protection section after a fault occurs, includes:

[0019] Obtain the voltage and current before a fault occurs in a preset protection section of the line;

[0020] When it is determined that a fault occurs in the preset protection section, a fault voltage and a fault current of the preset protection section are obtained.

[0021] Optionally, the tripping action current is determined according to the voltage and current before the fault occurs in the preset protection section, the fault voltage and the fault current, including:

[0022] If the voltage transformer in the line is broken, the tripping action current at the last setting time that was pre-stored will be used as the current tripping action current.

[0023] Optionally, the overcurrent protection current is Iop', Among them, Ihmax is the maximum load current, Kk is the second reliability coefficient, Kzg is the self-starting coefficient, and Kh is the return coefficient.

[0024] In a second aspect, an embodiment of the present invention further provides a relay protection device, comprising:

[0025] A voltage and current acquisition module is used to obtain the maximum load current of the line, the voltage and current of the preset protection section in the line before a fault occurs, and the fault voltage and fault current after a fault occurs in the preset protection section;

[0026] An action current determination module is used to determine the trip action current according to the voltage and current before the fault occurs in the preset protection section, the fault voltage and the fault current, and to determine the overcurrent protection current according to the maximum load current;

[0027] The state control module is used to control the state of the relay in the circuit according to the fault current, tripping action current and overcurrent protection current.

[0028] Optionally, the action current determination module includes:

[0029] An impedance determination unit, used to determine a comprehensive impedance Zs according to the voltage and current before a fault occurs in a preset protection section, the fault voltage and the fault current;

[0030] A potential determination unit, used for determining the potential Es according to the comprehensive impedance, the fault voltage and the fault current;

[0031] The action current determination unit is used to determine the tripping action current Iop according to the comprehensive impedance and potential.

[0032] The relay protection method and device provided by the embodiment of the present invention obtain the maximum load current of the line, the voltage and current of the preset protection section in the line before the fault occurs, and the fault voltage and fault current after the preset protection section fails; determine the tripping action current according to the voltage and current, fault voltage and fault current of the preset protection section before the fault occurs, and determine the overcurrent protection current according to the maximum load current; thereby controlling the state of the relay in the line according to the fault current, tripping action current and overcurrent protection current. The relay protection method and device provided by the embodiment of the present invention controls the state of the relay in the line according to the fault current, tripping action current and overcurrent protection current, and can control the relay to perform quick-break protection tripping or overcurrent protection tripping, cut off the fault path, thereby achieving the purpose of relay protection, and no manual assistance is required, which can solve the problem of poor reliability caused by manual labor, thereby improving the reliability of relay protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flow chart of a relay protection method provided in Embodiment 1 of the present invention;

[0034] Figure 2 is a flow chart of a relay protection method provided in Embodiment 2 of the present invention;

[0035] Figure 3 is a flow chart of another relay protection method provided in Embodiment 2 of the present invention;

[0036] Figure 4 It is a structural block diagram of a relay protection device provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0038] Embodiment 1

[0039] Figure 1 1 is a flowchart of a relay protection method provided in Embodiment 1 of the present invention. This embodiment is applicable to aspects of relay protection of power systems. The method can be executed by a relay protection device. The device can be implemented in software and / or hardware. The device can be integrated into an electronic device with a relay protection function such as a computer. The method specifically includes the following steps:

[0040] Step 110: Obtain the maximum load current of the line, the voltage and current of a preset protection section in the line before a fault occurs, and the fault voltage and fault current of the preset protection section after a fault occurs.

[0041] Among them, the maximum load current of the line can be pre-stored in the relay protection device, the voltage and current before and after the fault occurs in the preset protection section of the line can be collected by the voltage sensor and the current sensor respectively, and the relay protection device can be electrically connected to the voltage sensor and the current sensor to obtain the voltage and current before and after the fault occurs in the preset protection section of the line.

[0042] Step 120: Determine the tripping current according to the voltage and current before the fault occurs in the preset protection section, the fault voltage and the fault current, and determine the overcurrent protection current according to the maximum load current.

[0043] Among them, the tripping action current is related to the voltage and current before and after the fault occurs in the preset protection section, the overcurrent protection current is positively correlated with the maximum load current, and accordingly, the overcurrent protection current is independent of the voltage and current before and after the fault occurs in the preset protection section. The size of the tripping action current and the overcurrent protection current affects the action of the relay in the line.

[0044] Step 130: Control the state of the relay in the circuit according to the fault current, the tripping current and the overcurrent protection current.

[0045] For example, when the fault current is greater than or equal to the tripping action current, the control relay performs quick-break protection tripping. When the fault current is less than the tripping action current, if the fault current is greater than or equal to the overcurrent protection current, the control relay performs overcurrent protection tripping. The execution time of quick-break protection precedes the execution time of overcurrent protection. Through the coordination of quick-break protection and overcurrent protection, when a fault occurs in the preset protection section of the line, the control relay performs quick-break protection tripping or overcurrent protection tripping to cut off the fault path, thereby achieving the purpose of relay protection.

[0046] The relay protection method provided in this embodiment obtains the maximum load current of the line, the voltage and current of the preset protection section in the line before the fault occurs, and the fault voltage and fault current after the preset protection section fails; determines the tripping action current according to the voltage and current, fault voltage and fault current of the preset protection section before the fault occurs, and determines the overcurrent protection current according to the maximum load current; thereby controlling the state of the relay in the line according to the fault current, tripping action current and overcurrent protection current. The relay protection method provided in this embodiment controls the state of the relay in the line according to the fault current, tripping action current and overcurrent protection current, and can control the relay to perform quick-break protection tripping or overcurrent protection tripping, cut off the fault path, thereby achieving the purpose of relay protection, and, without manual assistance, can solve the problem of poor reliability caused by manual labor, thereby improving the reliability of relay protection.

[0047] Embodiment 2

[0048] Figure 2 1 is a flow chart of a relay protection method provided in Embodiment 2 of the present invention. This embodiment is applicable to aspects of relay protection of power systems. The method can be executed by a relay protection device. The device can be implemented by software and / or hardware. The device can be integrated into an electronic device with relay protection function such as a computer. The method specifically includes the following steps:

[0049] Step 210: Obtain the maximum load current of the line, and the voltage and current of the preset protection section in the line before a fault occurs.

[0050] Among them, the maximum load current of the line can be pre-stored in the relay protection device, the voltage and current of the preset protection section in the line can be collected by the voltage sensor and the current sensor respectively, and the relay protection device can be electrically connected to the voltage sensor and the current sensor to obtain the voltage and current of the preset protection section in the line before a fault occurs.

[0051] Step 220: When it is determined that a fault occurs in the preset protection section, a fault voltage and a fault current of the preset protection section are obtained.

[0052] Specifically, a common fault judgment method can be used to determine whether a preset protection section has a fault. For example, when the voltage and / or current of the preset protection section changes suddenly and the corresponding value exceeds the preset threshold, it can be determined that the preset protection section has a fault.

[0053] Step 230: Determine the comprehensive impedance Zs according to the voltage and current before the fault occurs in the preset protection section, the fault voltage and the fault current.

[0054] in, Umg(1) is the fault voltage component, Umg(1)=Uf(1)-Um, Img(1) is the fault current component, Img(1)=If(1)-Im, Uf(1) is the positive sequence component of the fault voltage, If(1) is the positive sequence component of the fault current, Um and Im are the voltage and current before the fault occurs in the preset protection section, respectively.

[0055] Step 240: Determine the potential Es according to the comprehensive impedance, the fault voltage and the fault current.

[0056] Among them, Es=Uf+Zs×If, Uf is the fault voltage, and If is the fault current.

[0057] Step 250: Determine the tripping current Iop according to the comprehensive impedance and potential.

[0058] in, Krel is the first reliability coefficient, Kd is the fault coefficient, Zl is the line impedance, and the specific values ​​of the coefficients in the formula can be set according to the actual situation and are not limited here. Specifically, the fault coefficient Kd can be adaptively determined by the fault type identification algorithm. If the BC phase of the transformer connected to the line is short-circuited, there is m is a coefficient, usually ranging from 4 to 8. is the phase current mutation amount.

[0059] In addition, when it is determined that the voltage transformer in the line is broken, the tripping action current at the last setting that is pre-stored can be used as the current tripping action current.

[0060] Step 260: When the fault current is greater than or equal to the tripping current, the relay is controlled to perform quick-break protection tripping.

[0061] Specifically, since the overcurrent protection is performed after a certain delay of the quick-break protection, the fault current is first compared with the tripping action current, so that when the quick-break protection condition is met, that is, the fault current is greater than or equal to the tripping action current, the relay can be controlled in time to perform quick-break protection tripping and quickly cut off the fault path.

[0062] Step 270: When the fault current is less than the tripping action current, if the fault current is greater than or equal to the overcurrent protection current, the relay is controlled to trip for overcurrent protection.

[0063] Among them, the overcurrent protection current is Iop', Ihmax is the maximum load current, Kk is the second reliability coefficient, usually 1.2, Kzg is the self-starting coefficient, Kzg>1, Kh is the return coefficient, Kh≥0.5. The specific values ​​of the above coefficients can be determined according to actual conditions and are not limited here.

[0064] Specifically, the tripping action current Iop and the overcurrent protection current Iop' can be adjusted in real time. In the process of the relay protection device controlling the relay, Iop and Iop' can be adjusted in real time according to the calculation formula of the tripping action current Iop and the overcurrent protection current Iop' to obtain updated setting values. There is no need to manually modify the setting values ​​multiple times, thereby improving work efficiency.

[0065] In one embodiment, Figure 3 : is a flow chart of another relay protection method provided in the second embodiment of the present invention, and the relay protection method specifically comprises the following steps:

[0066] Step 1: Assign values ​​to the first reliability coefficient Krel and the line impedance Zl.

[0067] Step 2: Obtain the voltage and current of the preset protection section in the line before the fault occurs.

[0068] Step 3: Determine whether a fault occurs in the preset protection section; if yes, proceed to step 4; if no, continue to execute this step.

[0069] Step 4: Obtain the fault voltage and fault current Ik after a fault occurs in a preset protection section in the line.

[0070] Step 5: Determine whether the fault occurs in the rear section of the transformer; if yes, proceed to step 6; if no, proceed to step 7.

[0071] Step 6: Control the relay to exit quick-break protection.

[0072] Specifically, after executing step 6, directly execute step 11.

[0073] Step 7: Determine whether the voltage transformer in the line is disconnected; if yes, go to step 8; if no, go to step 9.

[0074] Step 8: Use the pre-stored tripping action current at the last setting as the current tripping action current.

[0075] Specifically, after executing step eight, directly execute step eleven.

[0076] Step nine: determine the comprehensive impedance Zs and the potential Es according to the first reliability coefficient Krel, the line impedance Zl, the voltage and current of the preset protection section before the fault occurs, and the fault voltage and fault current after the fault occurs.

[0077] Step 10: Determine the tripping current Iop based on the comprehensive impedance Zs and the potential Es.

[0078] Step 11: Determine the overcurrent protection current Iop' according to the maximum load current of the line.

[0079] Specifically, the specific process of determining the comprehensive impedance Zs and the potential Es as well as the tripping action current Iop and the overcurrent protection current Iop' may refer to the above steps 210 to 270, which will not be repeated here.

[0080] Step 12: determine whether Ik is greater than or equal to Iop; if yes, execute step 13; if no, execute step 14.

[0081] Step 13: Control the relay to trip for quick-break protection.

[0082] Step 14: determine whether Ik is greater than or equal to Iop'; if yes, execute step 15; if no, end.

[0083] Step 15: Control the relay to trip for overcurrent protection.

[0084] The relay protection method provided in this embodiment controls the relay to perform quick-break protection tripping when the fault current is greater than or equal to the tripping action current, and when the fault current is less than the tripping action current, if the fault current is greater than or equal to the overcurrent protection current, the relay is controlled to perform overcurrent protection tripping to cut off the fault path, thereby achieving the purpose of relay protection, and no manual assistance is required, which can solve the problem of poor reliability caused by manual labor, thereby improving the reliability of relay protection.

[0085] Embodiment 3

[0086] Figure 4It is a structural block diagram of a relay protection device provided in the third embodiment of the present invention, and the device includes a voltage and current acquisition module 310, an action current determination module 320 and a state control module 330; wherein, the voltage and current acquisition module 310 is used to obtain the maximum load current of the line, the voltage and current of the preset protection section in the line before a fault occurs, and the fault voltage and fault current after a fault occurs in the preset protection section; the action current determination module 320 is used to determine the tripping action current according to the voltage and current, fault voltage and fault current of the preset protection section before a fault occurs, and determine the overcurrent protection current according to the maximum load current; the state control module 330 is used to control the state of the relay in the line according to the fault current, the tripping action current and the overcurrent protection current.

[0087] Optionally, the action current determination module 320 includes: an impedance determination unit, a potential determination unit and a first action current determination unit; wherein the impedance determination unit is used to determine the comprehensive impedance Zs according to the voltage and current, fault voltage and fault current before the fault occurs in the preset protection section; the potential determination unit is used to determine the potential Es according to the comprehensive impedance, fault voltage and fault current; the first action current determination unit is used to determine the tripping action current Iop according to the comprehensive impedance and potential.

[0088] In one embodiment, the state control module 330 includes a first control unit and a second control unit; wherein the first control unit is used to control the relay to perform quick-break protection tripping when the fault current is greater than or equal to the tripping action current; the second control unit is used to control the relay to perform overcurrent protection tripping when the fault current is less than the tripping action current and the fault current is greater than or equal to the overcurrent protection current.

[0089] Preferably, the voltage and current acquisition module 310 includes a first acquisition unit and a second acquisition unit; wherein the first acquisition unit is used to acquire the voltage and current of a preset protection section in the line before a fault occurs; and the second acquisition unit is used to acquire the fault voltage and fault current of the preset protection section when it is determined that a fault occurs in the preset protection section.

[0090] Preferably, the action current determination module 320 includes a second action current determination unit, and the second action current determination unit is used to use the pre-stored tripping action current at the last setting as the current tripping action current if the voltage transformer in the line is broken.

[0091] The relay protection device provided in this embodiment and the relay protection method provided in any embodiment of the present invention belong to the same inventive concept and have corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the relay protection method provided in any embodiment of the present invention.

[0092] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A relay protection method, characterized in that: include: Obtaining the maximum load current of the line, the voltage and current of a preset protection section in the line before a fault occurs, and the fault voltage and fault current after a fault occurs in the preset protection section; Determine the tripping action current according to the voltage and current before the fault occurs in the preset protection section, the fault voltage and the fault current, and determine the overcurrent protection current according to the maximum load current; Controlling the state of a relay in a circuit according to the fault current, the tripping action current and the overcurrent protection current; The controlling the state of a relay in the circuit according to the fault current, the tripping action current and the overcurrent protection current comprises: When the fault current is greater than or equal to the tripping action current, controlling the relay to perform quick-break protection tripping; When the fault current is less than the tripping action current, if the fault current is greater than or equal to the overcurrent protection current, the relay is controlled to perform overcurrent protection tripping; The obtaining of the voltage and current of a preset protection section in the line before a fault occurs, and the fault voltage and fault current of the preset protection section after a fault occurs, comprises: Obtain the voltage and current before a fault occurs in a preset protection section of the line; When it is determined that the preset protection section has a fault, obtaining a fault voltage and a fault current of the preset protection section; Determine whether the fault occurs in the rear section of the transformer. If so, control the relay to exit the quick-break protection; if not, determine whether the voltage transformer in the line is disconnected; Determine whether the voltage transformer in the line is broken. If so, use the pre-stored tripping action current at the last setting as the current tripping action current; if not, determine the comprehensive impedance Zs and potential Es based on the first reliability coefficient Krel, line impedance Zl, voltage and current before the fault in the preset protection section, and fault voltage and fault current after the fault.

2. The relay protection method according to claim 1, characterized in that: The step of determining the tripping action current according to the voltage and current before the fault occurs in the preset protection section, the fault voltage, and the fault current comprises: Determine a comprehensive impedance Zs according to the voltage and current of the preset protection section before the fault occurs, the fault voltage and the fault current; Determining a potential Es according to the comprehensive impedance, the fault voltage and the fault current; The tripping action current Iop is determined according to the comprehensive impedance and the potential.

3. The relay protection method according to claim 2, characterized in that: Wherein, Umg(1) is the fault voltage component, Umg(1)=Uf(1)-Um, Img(1) is the fault current component, Img(1)=If(1)-Im, Uf(1) is the positive sequence component of the fault voltage, If(1) is the positive sequence component of the fault current, Um and Im are respectively the voltage and current before the fault occurs in the preset protection section; Es=Uf+Zs×If; wherein Uf is the fault voltage and If is the fault current.

4. The relay protection method according to claim 2, characterized in that: Among them, Krel is the first reliability coefficient, Kd is the fault coefficient, and Zl is the line impedance.

5. The relay protection method according to claim 1, characterized in that: The step of determining the tripping action current according to the voltage and current before the fault occurs in the preset protection section, the fault voltage, and the fault current comprises: If the voltage transformer in the line is broken, the tripping action current at the last setting time that was pre-stored will be used as the current tripping action current.

6. The relay protection method according to claim 1, characterized in that: The overcurrent protection current is Iop', Among them, Ihmax is the maximum load current, Kk is the second reliability coefficient, Kzg is the self-starting coefficient, and Kh is the return coefficient.

7. A relay protection device, controlled by the relay protection method according to any one of claims 1 to 6, characterized in that: include: A voltage and current acquisition module, used to acquire the maximum load current of the line, the voltage and current of a preset protection section in the line before a fault occurs, and the fault voltage and fault current after a fault occurs in the preset protection section; An action current determination module, used to determine the trip action current according to the voltage and current before the fault occurs in the preset protection section, the fault voltage and the fault current, and determine the overcurrent protection current according to the maximum load current; The state control module is used to control the state of the relay in the circuit according to the fault current, the tripping action current and the overcurrent protection current.

8. The relay protection device according to claim 7, characterized in that: The action current determination module comprises: An impedance determination unit, configured to determine a comprehensive impedance Zs according to the voltage and current before a fault occurs in the preset protection section, the fault voltage, and the fault current; A potential determination unit, configured to determine a potential Es according to the comprehensive impedance, the fault voltage and the fault current; An action current determination unit is used to determine the tripping action current Iop according to the comprehensive impedance and the potential.

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