A station domain protection method and computer device

Abstract

The present invention belongs to the field of relay protection technology, and specifically relates to a station protection method and computer device. The method includes scheme 1 and / or scheme 2; the scheme 1 is: when the relay protection information between the transformer and the high-voltage side bus is missing, the protection delay of the low-voltage side circuit breaker when the fault direction is forward is modified to t set.H +Δt, and execute the protection logic according to the latest protection delay of the low-voltage side circuit breaker; the scheme 2 is: when the relay protection information between the transformer and the low-voltage side bus is missing, the protection delay of the high-voltage side circuit breaker when the fault direction is forward is modified to t set.L +Δt, and execute the protection logic according to the latest protection delay of the high-voltage side circuit breaker; t set.L The protection delay of the low voltage side line outgoing line; t set.H The invention solves the technical problem in the prior art that the fault clearing time of the substation area protection method is too long when information is missing.

Description

Technical Field

[0001] The present invention belongs to the technical field of relay protection, and in particular relates to a station area protection method and a computer device. Background Art

[0002] With the massive influx of new energy generators into the power system, the power system is becoming increasingly electronic. As a crucial component of the substation's first line of defense, the performance of substation protection is crucial to the safe and stable operation of the entire power grid.

[0003] Information loss mainly refers to the situation where the measuring element or merging unit cannot collect the system voltage and current due to a fault.

[0004] In recent years, with the expansion of new energy units and the complexity of power system operation, substation relay protection faces problems such as difficulty in determining the direction of nearby faults, difficulty in setting and coordination, and long fault clearing time when information is missing.

[0005] Substation line protection system Figure 1 As shown, the low voltage side line outgoing line (i.e. k M1 、k M2 and k M3 ) protection delay is t set.L And the fault direction is only toward the low voltage side; the high voltage side line outgoing line (i.e. k N1 、k N2 and k N3 ) protection delay is t set.H And the fault direction is only toward the high voltage side; k on both sides of the transformer M and k N are the protection devices of the circuit breakers on the low-voltage and high-voltage sides respectively. The fault direction can point to both sides; Δt is the protection delay increment of each line section. Under normal circumstances, if there is no information loss, when the fault direction points to the low-voltage side, k M Need to be k M1 Cooperation, k M The protection delay is t set.L +Δt;k N Need to be k M Cooperation, k N The protection delay is t set.L +Δt+Δt. If the low-voltage side information is missing, k N Unable to communicate with K M With the cooperation, at this time, k N The protection delay is t set.L +2Δt. The same applies when high-voltage side information is missing. However, such a protection delay setting value makes the fault clearing time too long when a forward fault occurs. Summary of the Invention

[0006] The purpose of the present invention is to provide a station area protection method and a computer device to solve the technical problem in the prior art that the fault clearing time of the station area protection method of a substation is too long when information is missing.

[0007] To solve the above technical problems, the present invention provides a technical solution for a station domain protection method, which includes solution 1 and / or solution 2;

[0008] The solution 1 is: when the relay protection information between the transformer and the high-voltage side bus is missing, the protection delay of the low-voltage side circuit breaker when the fault direction is forward is modified to t set.H +Δt, and execute the protection logic according to the latest protection delay of the low-voltage side circuit breaker;

[0009] The second solution is: when the relay protection information between the transformer and the low-voltage side bus is missing, the protection delay of the high-voltage side circuit breaker when the fault direction is forward is modified to t set.L +Δt, and execute the protection logic according to the latest protection delay of the high-voltage side circuit breaker;

[0010] t set.L The protection delay of the low voltage side line outgoing line; t set.H is the protection delay of the high-voltage side line outgoing line; Δt is the protection delay increment of each line section.

[0011] The beneficial effect of the above technical solution is that the technical solution of the station area protection method of the present invention belongs to an improved invention. When the measurement information on the low-voltage side is missing and the fault direction points to the transformer, the present invention makes the circuit breaker on the high-voltage side directly cooperate with the low-voltage side line outgoing line protection, and directly sets the protection delay of the circuit breaker on the high-voltage side to t set.L +Δt, compared with t in the prior art set.L A shorter +2Δt enables the protection device to operate earlier, shortening the protection delay and enabling faster fault clearing. When measurement information on the high-voltage side is missing, the same process as described above is employed. This invention solves the technical problem in prior art where substation-wide protection methods suffer from excessively long fault clearing times when information is missing.

[0012] Furthermore, the fault direction is determined based on the relationship between the degree of similarity between the calculated voltage drop and the measured voltage drop and a similarity setting value: if the degree of similarity is greater than the similarity setting value, the fault direction is considered to be positive;

[0013] The calculated voltage drop is a voltage drop calculated based on the measurement of the three-phase current; the measured voltage drop is a voltage drop obtained based on the measurement of the three-phase voltage.

[0014] Furthermore, the similarity degree is a similarity coefficient, and the calculation formula of the similarity coefficient is:

[0015]

[0016] Among them, u js (t) is the calculated voltage drop at time t; u cl (t) is the measured voltage drop at time t; r(u js (t),u cl (t)) is the similarity coefficient between the calculated voltage drop and the measured voltage drop; N is the data window length for calculating the similarity coefficient; is the average calculated voltage drop within the data window; is the average measured voltage drop within the data window.

[0017] Furthermore, when the substation adopts the Yd11 connection method, the calculated voltage drop and measured voltage drop on the low voltage side are:

[0018]

[0019]

[0020] Among them, u jsa (t),u jsb (t),u jsc (t) is the calculated voltage drop of each phase at time t; u cla (t),u clb (t),u clc (t) is the voltage drop of each phase measured at time t; i a (t), i b (t), i c (t) is the current value of each phase on the system side of the protection installation at time t; R x 、L x 、M x are the resistance, self-inductance and mutual inductance from the protection installation to the system power supply converted to the low-voltage side; u sa (t),u sb (t),u sc (t) is the voltage value of each phase at time t; u a (t),u b (t),u c (t) is the voltage value of each phase measured at the protection installation at time t; k is the transformer ratio.

[0021] Furthermore, when the substation adopts the Yd11 connection method, the calculated voltage drop and measured voltage drop on the high voltage side are:

[0022]

[0023]

[0024] Among them, u jsa (t),u jsb (t),u jsc (t) is the calculated voltage drop of each phase at time t; u cla (t),u clb (t),u clc (t) is the voltage drop of each phase measured at time t; i a (t), i b (t), i c (t) is the current value of each phase on the system side of the protection installation at time t; R X 、L X 、M X They are the resistance, self-inductance and mutual inductance from the protection installation to the system power supply; u sa (t),u sb (t),u sc (t) is the voltage value of each phase of the power system at time t; u a (t),u b (t),u c (t) is the voltage value of each phase measured at the protection installation at time t.

[0025] Furthermore, the following method is used to determine whether the relay protection information between the transformer and the high-voltage side bus is missing: if the duration of at least one analog sampling value information of the station interval from the transformer to the high-voltage side bus not being received exceeds the set time threshold, it is considered that the relay protection information from the transformer to the high-voltage side bus is missing.

[0026] Furthermore, the following method is used to determine whether the relay protection information between the transformer and the low-voltage side bus is missing: if the duration of at least one analog sampling value information of the station interval from the transformer to the low-voltage side bus not being received exceeds the set time threshold, it is considered that the relay protection information from the transformer to the low-voltage side bus is missing.

[0027] Furthermore, the method also includes: if there is no information loss in the relay protection information between the transformer and the high-voltage side bus and the transformer and the low-voltage side bus, the protection of the low-voltage side circuit breaker and the high-voltage side circuit breaker is restored with a delayed protection.

[0028] Furthermore, according to the latest protection delay of the low-voltage side circuit breaker, the protection logic is as follows: if the protection criterion of the low-voltage side circuit breaker is met and the duration of the fault direction being in the forward direction exceeds the protection delay of the low-voltage side circuit breaker, the low-voltage side circuit breaker will trip;

[0029] According to the latest protection delay execution logic of the high-voltage side circuit breaker, if the protection criterion of the high-voltage side circuit breaker is met and the duration of the fault direction being forward exceeds the protection delay of the high-voltage side circuit breaker, the high-voltage side circuit breaker will trip.

[0030] The present invention also provides a technical solution for a computer device: a computer device comprising a processor, wherein the processor is configured to execute the computer program to implement the steps of the station domain protection method described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a line system architecture diagram of a substation in the prior art;

[0032] Figure 2 A method flow chart of an embodiment of a station domain protection method of the present invention;

[0033] Figure 3 This is a schematic diagram of information loss on the high-voltage side of a line system in an embodiment of a station area protection method of the present invention. DETAILED DESCRIPTION

[0034] When the measurement information on the low-voltage side is missing and the fault direction points to the transformer, the present invention makes the circuit breaker on the high-voltage side directly cooperate with the low-voltage side line outgoing line protection, and directly sets the protection delay of the circuit breaker on the high-voltage side to t set.L +Δt, compared with t in the prior art set.L The +2Δt is shorter, so that the protection device can act in advance, the protection delay is shorter, and the fault can be cleared quickly. The present invention solves the technical problem in the prior art that the fault clearing time of the substation area protection method is too long when information is missing.

[0035] Example of the site domain protection method:

[0036] A station domain protection method, such as Figure 2 As shown, the method includes the following steps:

[0037] S1. Determine whether information is missing based on the collected electrical quantities and received signals. If information is missing, proceed to S2; if not, proceed to S3.

[0038] Specifically, this embodiment uses the following method to determine whether information missing occurs: collect the high / low voltage side interval sampling value information of the substation. When a certain analog sampling information is not received, the corresponding station interval sampling value timer increases a sampling interval time. If it is not satisfied, the corresponding station interval sampling value timer is set to 0; detect whether each station interval sampling value timer reaches the set value. When it reaches the set value, it is determined that information missing occurs in the corresponding station equipment.

[0039] S2. Determine whether information is missing on the high-pressure side or the low-pressure side. If information is missing on the high-pressure side, go to S4; if information is missing on the low-pressure side, go to S8.

[0040] S3, the protection delay setting value of the low-voltage side circuit breaker QF1 is restored; the protection delay setting value of the high-voltage side circuit breaker QF2 is restored, and go to S12.

[0041] S4, low voltage side circuit breaker QF1 protection delay setting value is changed to t set.H +Δt.

[0042] S5. Determine whether the protection criterion of the low-voltage side QF1 is met. If so, go to S6; if not, go to S13.

[0043] S6. Determine the fault direction. If it is forward, add a sampling interval to the low-voltage side timer and go to S7; if it is reverse, go to S13.

[0044] Specifically, this embodiment determines the fault direction on the low-voltage side according to the following method: based on the relationship between the similarity coefficient between the calculated voltage drop and the measured voltage drop and the similarity setting value: if the similarity coefficient is greater than the similarity setting value, the fault direction is considered to be forward; if the similarity coefficient is less than the similarity setting value, the fault direction is considered to be reverse.

[0045] Specifically, the calculation method for the calculated voltage drop and measured voltage drop on the low voltage side when the substation adopts the Yd11 connection method is:

[0046]

[0047]

[0048] Among them, u jsa (t),u jsb (t),u jsc (t) is the calculated voltage drop of each phase at time t; u cla (t),u clb (t),u clc (t) is the voltage drop of each phase measured at time t; i a (t), i b (t), i c (t) is the current value of each phase on the system side of the protection installation at time t; R x 、L x 、M x They are the resistance, self-inductance and mutual inductance from the protection installation to the system power supply converted to the low voltage side; the positive sequence impedance and negative sequence impedance from the protection installation to the system power supply are (L X -M X ),u sa (t),usb (t),u sc (t) is the voltage value of each phase at time t; u a (t),u b (t),u c (t) is the voltage value of each phase measured at the protection installation at time t; k is the transformer ratio.

[0049] S7. Determine whether the low-voltage side timer has reached the QF1 protection delay. If so, the protection is activated and a tripping command is issued to QF1, and the step ends. If not, go to S1.

[0050] S8, high voltage side QF2 protection delay setting value is changed to t set.L +Δt.

[0051] S9. Determine whether the high-voltage side QF2 protection criterion is met. If so, go to S10; if not, go to S14.

[0052] S10. Determine the fault direction. If it is forward, add a sampling interval to the high-voltage side timer and go to S11; if it is reverse, go to S14.

[0053] Specifically, this embodiment determines the high-voltage side fault direction in the following manner: based on the relationship between the similarity coefficient between the calculated voltage drop and the measured voltage drop and the similarity setting value: if the similarity coefficient is greater than the similarity setting value, the fault direction is considered to be forward; if the similarity coefficient is less than the similarity setting value, the fault direction is considered to be reverse.

[0054] Specifically, the calculation method for the calculated voltage drop and measured voltage drop on the high voltage side when the substation adopts the Yd11 connection method is:

[0055]

[0056]

[0057] Among them, u jsa (t),u jsb (t),u jsc (t) is the calculated voltage drop of each phase at time t; u cla (t),u clb (t),u clc (t) is the voltage drop of each phase measured at time t; i a (t), i b (t), i c (t) is the current value of each phase on the system side of the protection installation at time t; R X 、L X 、M X They are the resistance, self-inductance and mutual inductance from the protection installation to the system power supply; usa (t),u sb (t),u sc (t) is the voltage value of each phase of the power system at time t; u a (t),u b (t),u c (t) is the voltage value of each phase measured at the protection installation at time t.

[0058] S11. Determine whether the high-voltage side timer has reached the QF2 protection delay. If so, the protection is activated and a tripping command is issued to QF2, and the step ends. If not, go to S1.

[0059] S12: The high / low pressure side timer is reset to zero and the step ends.

[0060] S13. The low-pressure side timer is reset to zero and the step ends.

[0061] S14: The high-voltage side timer is reset to zero, and the step ends.

[0062] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0063] like Figure 1 As shown in FIG, a schematic diagram of the system architecture of the station domain protection method of this embodiment is shown. Figure 3 As shown, when the high-voltage side information of the substation is missing and a high-voltage side busbar fault occurs, the substation protection method for dealing with the loss of electrical quantity information includes the following steps:

[0064] (1) Determine whether information loss occurs based on the collected electrical quantities and received signals: In this example, the interval sampling value timer setting value is set to 50ms. Since information loss occurs on the high-voltage side, the corresponding electrical quantity cannot be collected or the alarm information cannot be received within 50ms. Then, the abnormal interval sampling value position in the high-voltage side station or the alarm position of the equipment in the high-voltage side station is 1, and the abnormal equipment position in the high-voltage side station is 1, which can determine that information loss occurs.

[0065] (2) Determining whether information loss occurs on the high-pressure side or the low-pressure side: In this example, it is determined that information loss occurs on the high-pressure side.

[0066] (3) The delay setting value of QF2 protection on the high-voltage side is restored, and the delay setting value of QF1 protection on the low-voltage side is changed to t set.H +Δt. In this example, the protection delay of the high-voltage side line outgoing line is t set.H The protection delay increment Δt of each line section is 0s. Therefore, the protection delay setting value of QF1 on the low voltage side is changed from 1s to 0.5s.

[0067] In other embodiments, Δt may be set to 0.4s or 0.3s. Generally, Δt may be set within 0.3-0.5s.

[0068] (4) Determine whether the protection criteria of QF1 on the low-voltage side are met: After the busbar short-circuit fault occurs, the protection criteria of QF1 on the low-voltage side are met.

[0069] (5) Determine the fault direction: r set Set to 0.2, calculate u in real time js 、u cl , and then calculate r(u js ,u cl )≈1, because r(u js ,u cl )>r set , so it is judged to be a fault pointing to the high-voltage side, that is, a forward fault pointing to the transformer, and the timer is increased by 1.

[0070] (6) Determine whether the fault time has reached the QF1 protection delay: Since the high-voltage side protection is locked due to information loss, the fault persists and the fault is not eliminated before the delay setting value of the QF1 protection is reached. If the low-voltage side timer does not reach the QF1 protection delay, the next sampling time step is entered. After multiple accumulations, the timer reaches the QF1 protection delay, the protection is activated, and a trip command is issued to QF1, and the step ends.

[0071] Computer device embodiment:

[0072] A computer device includes a processor configured to execute a computer program to implement the steps of the above-mentioned station domain protection method. The specific station domain protection method has been described in sufficient detail in the above-mentioned station domain protection method embodiment and will not be repeated here.

[0073] The present invention has the following characteristics:

[0074] 1) The present invention can reliably identify the fault direction on the high / low voltage side of a substation where new energy is connected.

[0075] 2) The present invention can more quickly eliminate faults when electrical quantity information is missing.

[0076] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments without inventive effort, or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A station domain protection method, characterized in that: The method includes scheme 1 and / or scheme 2; The solution 1 is: when the relay protection information between the transformer and the high-voltage side bus is missing, the protection delay of the low-voltage side circuit breaker when the fault direction is forward is modified to t set.H +Δt, and execute the protection logic according to the latest protection delay of the low-voltage side circuit breaker; The second solution is: when the relay protection information between the transformer and the low-voltage side bus is missing, the protection delay of the high-voltage side circuit breaker when the fault direction is forward is modified to t set.L +Δt, and execute the protection logic according to the latest protection delay of the high-voltage side circuit breaker; t set.L The protection delay of the low voltage side line outgoing line; t set.H is the protection delay of the high-voltage side line outgoing line; Δt is the protection delay increment of each line section.

2. The station domain protection method according to claim 1, characterized in that: The fault direction is determined based on the relationship between the degree of similarity between the calculated voltage drop and the measured voltage drop and the similarity setting value: if the similarity is greater than the similarity setting value, the fault direction is considered to be positive; The calculated voltage drop is a voltage drop obtained by measuring the three-phase current and the impedance from the protection installation to the system side; the measured voltage drop is a voltage drop obtained by measuring the difference between the three-phase voltage and the system side voltage.

3. The station domain protection method according to claim 2, characterized in that: The similarity degree is the similarity coefficient, and the calculation formula of the similarity coefficient is: Among them, u js (t) is the calculated voltage drop at time t; u cl (t) is the measured voltage drop at time t; r(u js (t),u cl (t)) is the similarity coefficient between the calculated voltage drop and the measured voltage drop; N is the data window length for calculating the similarity coefficient; is the average calculated voltage drop within the data window; is the average measured voltage drop within the data window.

4. The station domain protection method according to claim 2 or 3, characterized in that: When the substation adopts the Yd11 connection method, the calculated voltage drop and measured voltage drop on the low voltage side are: Among them, u jsa (t),u jsb (t),u jsc (t) is the calculated voltage drop of each phase at time t; u cla (t),u clb (t),u clc (t) is the voltage drop of each phase measured at time t; i a (t), i b (t), i c (t) is the current value of each phase on the system side of the protection installation at time t; R x 、L x 、M x are the resistance, self-inductance and mutual inductance from the protection installation to the system power supply converted to the low-voltage side; u sa (t),u sb (t),u sc (t) is the voltage value of each phase at time t; u a (t),u b (t),u c (t) is the voltage value of each phase measured at the protection installation at time t; k is the transformer ratio.

5. The station domain protection method according to claim 2 or 3, characterized in that: When the substation adopts the Yd11 connection method, the calculated voltage drop and measured voltage drop on the high voltage side are: Among them, u jsa (t),u jsb (t),u jsc (t) is the calculated voltage drop of each phase at time t; u cla (t),u clb (t),u clc (t) is the voltage drop of each phase measured at time t; i a (t), i b (t), i c (t) is the current value of each phase on the system side of the protection installation at time t; R X 、L X 、M X They are the resistance, self-inductance and mutual inductance from the protection installation to the system power supply; u sa (t),u sb (t),u sc (t) is the voltage value of each phase of the power system at time t; u a (t),u b (t),u c (t) is the voltage value of each phase measured at the protection installation at time t.

6. The station domain protection method according to claim 1, characterized in that: The following method is used to determine whether the relay protection information between the transformer and the high-voltage side bus is missing: if the duration of not receiving at least one analog sampling value information of the station interval from the transformer to the high-voltage side bus exceeds the set time threshold, it is considered that the relay protection information from the transformer to the high-voltage side bus is missing.

7. The station domain protection method according to claim 1, characterized in that: The following method is used to determine whether the relay protection information between the transformer and the low-voltage side bus is missing: if the duration of at least one analog sampling value information of the station interval between the transformer and the low-voltage side bus is not received exceeds the set time threshold, it is considered that the relay protection information between the transformer and the low-voltage side bus is missing.

8. The station domain protection method according to claim 1, 6 or 7, characterized in that: The method further includes: if there is no information loss in the relay protection information between the transformer and the high-voltage side bus and the transformer and the low-voltage side bus, the protection of the low-voltage side circuit breaker and the high-voltage side circuit breaker is restored with a time delay.

9. The station domain protection method according to claim 1, characterized in that: According to the latest protection delay execution logic of the low-voltage side circuit breaker, the low-voltage side circuit breaker trips if the protection criteria of the low-voltage side circuit breaker are met and the duration of the fault direction being forward exceeds the protection delay of the low-voltage side circuit breaker; According to the latest protection delay execution logic of the high-voltage side circuit breaker, if the protection criterion of the high-voltage side circuit breaker is met and the duration of the fault direction being forward exceeds the protection delay of the high-voltage side circuit breaker, the high-voltage side circuit breaker will trip.

10. A computer device comprising a processor, characterized in that: The processor is configured to execute a computer program to implement the steps of the site domain protection method according to any one of claims 1 to 9.

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