Memory locking fault identification and failure protection optimization processing method and system

Abstract

The invention discloses a memory locking fault identification and failure protection optimization processing method and system, and relates to the technical field of power system relay protection, and the method comprises the following steps: S1, obtaining the secondary side current information of each branch current transformer in real time; s2, based on the current information, calculating a sampling current variable quantity of a three-phase current value of each branch; and S3, identifying abnormal data based on the sampling value of each branch at the current moment and the sampling value at the half-wavefront moment, and calling locking failure protection or opening failure protection based on an abnormal identification result. According to the invention, abnormal data identification is carried out based on the sum of the sampling value at the current moment and the sampling value at the half-wave front moment of each branch and the backward difference characteristic thereof, so that branch sampling value data abnormity can be correctly identified, maloperation of a bus protection device is effectively prevented, and an intelligent processing method for sampling data at the abnormal moment is adopted. The reliability of bus protection under the working condition of abnormal sampling data is better improved, and safe and stable operation of a power system is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection of power systems, and in particular to a method and system for optimizing memory lockout fault identification and failure protection processing. Background Art

[0002] Relay protection devices are the first line of defense for power grid safety. When a system or equipment failure endangers the safety of the power grid, the correct action of the relay protection device can minimize the damage to the power equipment itself and reduce the impact on the safe power supply of the power system. If the relay protection device does not act correctly (including refusal to act and false action), it will cause great harm to the power system. With the rapid development of the power system, the scale of the power grid continues to grow, and the network structure of the power system is becoming increasingly complex. The reliability of relay protection devices is particularly important for the safe and stable operation of the power system.

[0003] The sampling data in the secondary protection device of the power system is an important source of device data and an important basis for judging the action of the protection device. If the sampling value fluctuates due to abnormalities such as the AC module and memory soft errors of the protection device, it will cause the protection device to malfunction and cause serious power accidents. Therefore, the relay protection device must reliably identify the correctness of the sampling value and adopt corresponding optimization processing methods to improve the reliability of relay protection and ensure the safe and stable operation of the power grid.

[0004] At present, some scholars have proposed to judge data anomalies based on data quality (AD sampling anomaly flag for conventional stations, sampling status flag for intelligent stations). When there is a sampling anomaly flag, the differential protection is locked. When there is no sampling anomaly flag and only one current fluctuates (zero-sequence quantity increases or current has a sudden change), the waveform characteristics are integrated to identify data anomalies. When it is identified as sampling data anomalies, if the system fails, multiple judgment criteria are used to intelligently handle the action behavior under abnormal conditions. According to actual needs, different processing solutions can be selected, such as locking differential protection or tripping the abnormal unit first. The above research focuses on the impact of data anomalies on differential protection.

[0005] If no processing is done on the sampling value fluctuations caused by abnormalities such as memory soft errors, the current calculated by the protection device will inevitably be greater than the failure protection setting value, which is likely to cause the failure protection to malfunction. When the data sampling is abnormal, the faulty component may not return. If no measures are taken, the scope of the circuit breaker failure protection malfunction and refusal to operate is particularly large. At present, the mainstream method of handling data anomalies is relatively simple. When the data state is abnormal, the protection function is locked, and the impact of data anomalies on the failure protection function is ignored.

[0006] For example, Chinese patent number CN202011454503.8 discloses a method and system for improving the reliability of data interaction at the internal output of a relay protection device. This method solves the problem of relay protection device memory soft errors causing protection misoperation by adding a three-out-of-two redundant mutual check method for key memory data, a key data pointer CRC check method, and a CPU and FPGA output interaction method. However, this method requires a certain number of identical action output marks to be output after the fault action, and the action output judgment is complex. There is a possibility of misjudging the fault action output, and it is difficult to ensure the judgment accuracy. Summary of the invention

[0007] Based on this, it is necessary to provide a memory lock fault identification and failure protection optimization processing method and system to address the above technical problems.

[0008] In a first aspect, the present invention provides a method for memory lock fault identification and failure protection optimization processing, the method comprising the following steps:

[0009] S1, real-time acquisition of secondary current information of each branch current transformer;

[0010] S2. Calculate the sampling current change of the three-phase current value of each branch based on the current information;

[0011] S3. Based on the sampling values ​​of each branch at the current moment and the sampling values ​​at the half-wave front moment, abnormal data is identified, and based on the abnormal identification results, the locking failure protection or the opening failure protection is called.

[0012] Furthermore, the current information includes: the sampling values ​​of each branch at the current moment, the sampling values ​​of each half-wave moment, the sampling values ​​of each branch at one point before the current moment, the sampling values ​​of each branch at half-wave moment before the current moment, the sampling values ​​of each branch two weeks ago at the current moment, and the sampling values ​​of each half-wave moment two weeks ago at the current moment.

[0013] Furthermore, the calculation formula for calculating the sampling current change of the three-phase current value of each branch is:

[0014]

[0015] In the formula, Indicates branch m The current change at the current sampling point k of the phase current; Indicates branch m The sampling current value of the current sampling point k of the phase current; Indicates branch m The current sampling value of the previous two-cycle points corresponding to the current sampling point k of the phase current; Indicates phase A, phase B or phase C of three-phase current; N indicates the number of two-cycle sampling points.

[0016] Further, based on the sampling values ​​of each branch at the current moment and the sampling values ​​at the half-wave front moment, identifying abnormal data, and based on the abnormal identification result, calling the locking failure protection or the opening failure protection includes the following steps:

[0017] S31, calculating the sum of the sampling values ​​of each branch at the current moment and the sampling value at the half-wave front moment, which is defined as the sampling sum at the current moment. If the absolute value of the sampling sum at the current moment is greater than the sampling abnormality threshold value, the normal standard waveform is excluded, and step S32 is executed;

[0018] S32, judging whether the current sampling sum of each branch is greater than K times the current sampling value of each branch, if so, excluding the tail current and the attenuated DC component, and executing step S33;

[0019] S33, calculating the sum of the sampling values ​​of each branch at the previous point of the current moment and the sampling value before the half-wave at the previous point of the current moment, which is defined as the previous point sampling sum. If the difference between the previous point sampling sum and the current moment sampling sum is greater than the sampling abnormality threshold value, executing step S34;

[0020] S34, calculate the sum of the sampling values ​​of each branch two weeks before the current moment and the sampling values ​​before the half-wave two weeks before the current moment, and define it as the sampling sum of the previous two weeks. If the difference between the sampling sum of the previous two weeks and the sampling sum of the current moment is greater than the sampling abnormality threshold, it is defined that the data of the branch is abnormal, the failure protection function is locked, and step S35 is executed;

[0021] S35. Detect the fault signal of the power system, and based on the fault abnormality diagnosis, open the failure protection function, and trip the abnormal branch and other branches in turn.

[0022] Further, detecting the fault signal of the power system, and based on the fault abnormality diagnosis, opening the failure protection function, and sequentially tripping the abnormal branch and other branches include the following steps:

[0023] S351, if the power system has not failed and the busbar protection device has not received the start failure input signal, no processing is performed; if the power system has failed, the protection is activated, the start failure input signal is closed, and step S352 is executed;

[0024] S352, the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment is included in the calculation of the current data of the data abnormal branch. If the zero-sequence current, phase current or phase current mutation quantity meets the judgment condition at this time, step S353 is executed;

[0025] S353, open the failure protection function, first trip the data abnormal branch, and delay the preset time to trip all other branches connected to the bus.

[0026] Further, the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment before is included in the calculation of the current data of the data abnormal branch includes the following steps:

[0027] S3521, taking the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment into the calculation process of the phase current of the data abnormal branch;

[0028] S3522. The sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment is included in the calculation process of the zero-sequence current of the data abnormal branch.

[0029] Furthermore, the calculation formula for including the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment before into the calculation process of the phase current of the data abnormal branch includes:

[0030]

[0031]

[0032]

[0033] In the formula, Indicates the effective value of the current of phase A, phase B and phase C of the data abnormal branch m; Indicates the branch m at sampling point i Phase current; represents the sinusoidal phase coefficient; Represents the cosine term coefficient; N′ represents the number of sampling points per cycle is 24; k represents the current sampling point.

[0034] Furthermore, the sum of the sampling value of the data abnormal branch at the current moment and the sampling value before the half-wave moment is included in the calculation formula of the zero-sequence current of the data abnormal branch:

[0035]

[0036] In the formula, Indicates the effective value of zero-sequence current of data abnormal branch m; Indicates the effective value of the phase A current of the data abnormal branch m; Indicates the effective value of the B-phase current of the data abnormal branch m; Indicates the effective value of the C-phase current of the data abnormal branch m.

[0037] Furthermore, the determination conditions satisfied by the zero-sequence current, phase current or phase current mutation amount include:

[0038]

[0039]

[0040]

[0041] In the formula, Indicates the effective value of zero-sequence current of data abnormal branch m; Indicates the effective value of the current of phase A, phase B and phase C of the data abnormal branch m; Indicates the current change of the φ phase current at the current sampling point k of the data abnormal branch m; I set0 It indicates the zero-sequence current threshold of data abnormal branch m; Iset indicates the three-phase current mutation threshold of data abnormal branch m; In indicates the rated value of the secondary side of CT, which is 1A or 5A according to the on-site CT model.

[0042] In a second aspect, the present invention further provides a memory lock fault identification and failure protection optimization processing system, the system comprising:

[0043] Current monitoring module, used to obtain the secondary side current information of each branch current transformer in real time;

[0044] A variation calculation module is used to calculate the sampled current variation of the three-phase current values ​​of each branch based on the current information;

[0045] The protection optimization module is used to identify abnormal data based on the sampling values ​​of each branch at the current moment and the sampling values ​​at the half-wave moment before, and to call the lock failure protection or open failure protection based on the abnormal identification results.

[0046] Furthermore, the current information includes: the sampling values ​​of each branch at the current moment, the sampling values ​​of each half-wave moment, the sampling values ​​of each branch at one point before the current moment, the sampling values ​​of each branch at half-wave moment before the current moment, the sampling values ​​of each branch two weeks ago at the current moment, and the sampling values ​​of each half-wave moment two weeks ago at the current moment.

[0047] Furthermore, the protection optimization module includes: a first calculation module, a sampling judgment module, a second calculation module, a third calculation module and an abnormal protection module;

[0048] Among them, the first calculation module is used to calculate the sum of the sampling values ​​of each branch at the current moment and the sampling value at the half-wave front moment, which is defined as the sampling sum at the current moment. If the absolute value of the sampling sum at the current moment is greater than the sampling abnormality threshold value, the normal standard waveform is excluded;

[0049] The sampling judgment module is used to judge whether the current sampling sum of each branch is greater than K times the current sampling value of each branch. If so, the tail current and the attenuated DC component are excluded;

[0050] The second calculation module is used to calculate the sum of the sampling values ​​of each branch at a point before the current moment and the sampling value before the half-wave at a point before the current moment, which is defined as the sampling sum of the previous point. If the difference between the sampling sum of the previous point and the sampling sum of the current moment is greater than the sampling abnormality threshold value, the third calculation module is called;

[0051] The third calculation module is used to calculate the sum of the sampling values ​​of each branch two weeks before the current moment and the sampling values ​​before the half-wave two weeks before the current moment, which is defined as the sampling sum of the previous two weeks. If the difference between the sampling sum of the previous two weeks and the sampling sum of the current moment is greater than the sampling abnormality threshold, the data of the branch is defined as abnormal, and the protection function is locked out;

[0052] The abnormal protection module is used to detect fault signals of the power system, and based on the fault abnormality diagnosis, open the failure protection function and trip the abnormal branch and other branches in turn.

[0053] Furthermore, the abnormal protection module includes: a fault diagnosis unit, a sampling and counting unit, and a trip protection unit;

[0054] The fault diagnosis unit is used to: if the power system does not fail and the busbar protection device does not receive the start failure input signal, no processing is performed; if the power system fails, the protection is activated and the start failure input signal is closed;

[0055] The sampling and counting unit is used to count the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment into the current data calculation of the data abnormal branch. If the zero-sequence current, phase current or phase current mutation quantity meets the judgment condition at this time, the tripping protection unit is called;

[0056] The tripping protection unit is used to open the failure protection function, first tripping the data abnormal branch, and then delaying the preset time to trip all other branches connected to the bus.

[0057] Furthermore, the sampling and counting unit includes: a phase current counting unit and a zero-sequence current counting unit;

[0058] The phase current counting unit is used to count the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment before into the phase current calculation process of the data abnormal branch;

[0059] The zero-sequence current counting unit is used to count the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment before into the zero-sequence current calculation process of the data abnormal branch.

[0060] The beneficial effects of the present invention are as follows: the present invention collects the current information of each branch in real time based on the busbar protection, calculates the change of each branch current, judges whether the sampling value has undergone a mutation, and identifies abnormal data based on the sum of the sampling value of each branch at the current moment and the sampling value at the half-wave front moment and its backward differential characteristics. If the data is abnormal, the failure protection is locked. When it is identified as data abnormality, the power system fails, the protection action starts the failure input signal closure, and the sampling data characteristics at the abnormal moment are taken into account for optimization processing; this method can correctly identify the abnormality of branch sampling value data, effectively prevent the busbar protection device from malfunctioning, and at the same time adopt an intelligent processing method for sampling data at abnormal moments, which better improves the reliability of busbar protection under abnormal sampling data conditions and ensures the safe and stable operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0062] Figure 1 is a flow chart of a memory lock fault identification and failure protection optimization processing method according to an embodiment of the present invention;

[0063] Figure 2 It is a logic flow diagram of a memory lock fault identification and failure protection optimization processing method according to an embodiment of the present invention;

[0064] Figure 3 It is a logic diagram of judging abnormal branch sampling data of a bus protection device according to an embodiment of the present invention (taking branch 1 as an example);

[0065] Figure 4 It is a logic diagram of the busbar protection device according to an embodiment of the present invention for judging whether the branch failure current condition is satisfied (taking branch 1 as an example);

[0066] Figure 5 It is a logic diagram of a method for optimizing the process of failure and reopening when the sampling current of a busbar protection device is abnormal according to an embodiment of the present invention (taking branch 1 as an example);

[0067] Figure 6 The invention is a system principle block diagram of a memory lock fault identification and failure protection optimization processing system according to an embodiment of the invention. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0069] See also Figure 1 , provides a memory lock fault identification and failure protection optimization processing method, the method comprising the following steps:

[0070] S1. Obtain the secondary side current information of each branch current transformer in real time.

[0071] In the description of the present invention, the current information includes: the sampling value of each branch at the current moment Each sampling value before half wave The sampling value of each branch before the current moment The sampling value of the half-wave moment before the current moment The sampling values ​​of each branch two weeks ago at the current moment And the sampling value of half wavefront time of two weeks before the current moment

[0072] S2. Based on the current information, calculate the sampling current change of the three-phase current value of each branch.

[0073] In the description of the present invention, the calculation formula for calculating the sampling current change of the three-phase current value of each branch is:

[0074]

[0075] In the formula, Indicates branch m The current change at the current sampling point k of the phase current; Indicates branch m The sampling current value of the current sampling point k of the phase current; Indicates branch m The current sampling value of the previous two-cycle points corresponding to the current sampling point k of the phase current; Indicates phase A, phase B or phase C of the three-phase current; N indicates the number of two-cycle sampling points, that is, 48.

[0076] S3. Based on the sampling values ​​of each branch at the current moment and the sampling values ​​at the half-wave front moment, abnormal data is identified, and based on the abnormal identification results, the locking failure protection or the opening failure protection is called.

[0077] In the description of the present invention, Figure 3 As shown, based on the sampling values ​​of each branch at the current moment and the sampling values ​​at the half-wave front moment, identifying abnormal data, and based on the abnormal identification result, calling the locking failure protection or the opening failure protection includes the following steps:

[0078] S31. Calculate the sum of the sampling values ​​of each branch at the current moment and the sampling value at the half-wave front moment, which is defined as the sampling sum at the current moment. If the absolute value of the sampling sum at the current moment is greater than the sampling abnormality threshold value, exclude the normal standard waveform and execute step S32.

[0079] Specifically, the calculation formula of the sum of the sampling values ​​of each branch at the current moment and the sampling value at the half-wave front moment (the sampling sum at the current moment) is:

[0080]

[0081] In the formula, It represents the sum of the sampling value of branch m at the current k moment and the sampling value at the half-wave front moment; Indicates the sampling value of each branch at the current moment; Represents the sampling values ​​at the half-wave front moment.

[0082] The determination conditions of the absolute value of the current sampling sum and the sampling abnormality threshold are:

[0083]

[0084] In the formula, I set1 It indicates the sampling abnormal threshold. Taking the sampling plug-in zero drift into consideration, the value is 0.05In, where In is the secondary rated value of the current.

[0085] S32, determine whether the current sampling sum of each branch is greater than K times the current sampling value of each branch. If so, exclude the tail current and the attenuated DC component, and execute step S33.

[0086] Specifically, the judgment condition of whether the current sampling sum is greater than K times the current sampling values ​​of each branch is:

[0087]

[0088] Where K is the proportionality coefficient, which is 0.9.

[0089] S33, calculate the sum of the sampling values ​​of each branch at the point before the current moment and the sampling value before the half-wave at the point before the current moment, which is defined as the sampling sum of the previous point. If the difference between the sampling sum of the previous point and the sampling sum of the current moment is greater than the sampling abnormality threshold value, execute step S34.

[0090] Specifically, the calculation formula of the sum of the sampling values ​​of each branch before the current moment and the sampling value before the half-wave before the current moment (the sampling sum of the previous point) is:

[0091]

[0092] In the formula, It is the sum of the sampling value of branch m at the point before the current k moment and its sampling value at the half-wave moment before; Indicates the sampling value of each branch at a point before the current moment; Indicates the sampling value half a wave ago before the current moment.

[0093] The judgment condition that the difference between the previous sampling sum and the current sampling sum is greater than the sampling anomaly threshold is:

[0094]

[0095] S34. Calculate the sum of the sampling values ​​of each branch two weeks before the current moment and the sampling values ​​before the half-wave two weeks before the current moment, which is defined as the sampling sum of the previous two weeks. If the difference between the sampling sum of the previous two weeks and the sampling sum at the current moment is greater than the sampling abnormality threshold, the data of the branch is defined as abnormal, the protection function is locked and failure is executed, and step S35 is executed.

[0096] Specifically, the calculation formula of the sum of the sampling values ​​of each branch two weeks before the current moment and the sampling values ​​before the half-wave two weeks before the current moment (the sum of the sampling values ​​of the previous two weeks) is:

[0097]

[0098] In the formula, It represents the sum of the two-wavefront sampling values ​​and the half-wavefront sampling values ​​of branch m at the current time k; Indicates the sampling values ​​of each branch two weeks ago at the current moment; Indicates the sampling value half a wave ago two weeks ago at the current moment.

[0099] The judgment condition that the difference between the sampling sum of the previous two weeks and the sampling sum at the current moment is greater than the sampling abnormality threshold is:

[0100]

[0101] S35. Detect the fault signal of the power system, and based on the fault abnormality diagnosis, open the failure protection function, and trip the abnormal branch and other branches in turn.

[0102] In the description of the present invention, Figure 4-Figure 5 As shown, detecting the fault signal of the power system, and based on the fault abnormality diagnosis, opening the failure protection function, and sequentially tripping the abnormal branch and other branches include the following steps:

[0103] S351. If the power system has not failed and the busbar protection device has not received the start failure input signal, no processing is performed; if the power system has failed, the protection is activated, the start failure input signal is closed, and step S352 is executed.

[0104] S352. The sum of the sampling value of the data abnormal branch at the current moment and the sampling value before the half-wave moment is included in the calculation of the current data of the data abnormal branch. If the zero-sequence current, phase current or phase current mutation amount meets the judgment condition at this time, execute step S353.

[0105] In the description of the present invention, the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave front moment is included in the calculation of the current data of the data abnormal branch, including the following steps:

[0106] S3521. The sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment is included in the calculation process of the phase current of the data abnormal branch.

[0107] In the description of the present invention, the calculation formula for including the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave front moment in the calculation process of the phase current of the data abnormal branch includes:

[0108]

[0109]

[0110]

[0111] In the formula, Indicates the effective value of the current of phase A, phase B and phase C of the data abnormal branch m; Indicates the branch m at sampling point i Phase current; represents the sinusoidal phase coefficient; Represents the cosine term coefficient; N′ represents the number of sampling points per cycle is 24; k represents the current sampling point.

[0112] S3522. The sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment is included in the calculation process of the zero-sequence current of the data abnormal branch.

[0113] In the description of the present invention, the calculation formula for including the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave front moment in the calculation process of the zero-sequence current of the data abnormal branch is:

[0114]

[0115] In the formula, Indicates the effective value of zero-sequence current of data abnormal branch m; Indicates the effective value of the phase A current of the data abnormal branch m; Indicates the effective value of the B-phase current of the data abnormal branch m; Indicates the effective value of the C-phase current of the data abnormal branch m.

[0116] In the description of the present invention, the determination conditions satisfied by the zero-sequence current, phase current or phase current mutation amount include:

[0117]

[0118]

[0119]

[0120] In the formula, Indicates the effective value of zero-sequence current of data abnormal branch m; Indicates the effective value of the current of phase A, phase B and phase C of the data abnormal branch m; Indicates the current change of the φ phase current at the current sampling point k of the data abnormal branch m; I set0 Indicates the zero-sequence current threshold of the data abnormal branch m; I set It indicates the three-phase current mutation threshold of the data abnormal branch m. In indicates the rated value of the secondary side of CT, which is 1A or 5A according to the on-site CT model.

[0121] S353, open the failure protection function, first trip the data abnormal branch, and delay the preset time to trip all other branches connected to the bus.

[0122] See also Figure 6 , and also provides a memory lock fault identification and failure protection optimization processing system, the system comprising:

[0123] The current monitoring module 1 is used to obtain the secondary side current information of each branch current transformer in real time.

[0124] The variation calculation module 2 is used to calculate the sampled current variation of the three-phase current value of each branch based on the current information.

[0125] The protection optimization module 3 is used to identify abnormal data based on the sampling values ​​of each branch at the current moment and the sampling values ​​at the half-wave front moment, and to call the lock failure protection or the open failure protection based on the abnormal identification result.

[0126] In the description of the present invention, the current information includes: the sampling values ​​of each branch at the current moment, the sampling values ​​of each half-wave moment, the sampling values ​​of each branch at one point before the current moment, the sampling values ​​of half-wave moment at one point before the current moment, the sampling values ​​of each branch two weeks before the current moment, and the sampling values ​​of half-wave moment two weeks before the current moment.

[0127] In the description of the present invention, the protection optimization module 3 includes: a first calculation module (not shown in the figure), a sampling judgment module (not shown in the figure), a second calculation module (not shown in the figure), a third calculation module (not shown in the figure) and an abnormal protection module (not shown in the figure).

[0128] Among them, the first calculation module is used to calculate the sum of the sampling values ​​of each branch at the current moment and the sampling value at the half-wave front moment, which is defined as the sampling sum at the current moment. If the absolute value of the sampling sum at the current moment is greater than the sampling abnormality threshold value, the normal standard waveform is excluded.

[0129] The sampling judgment module is used to judge whether the current sampling sum of each branch is greater than K times the current sampling value of each branch. If it is greater, the tail current and the attenuated DC component are excluded.

[0130] The second calculation module is used to calculate the sum of the sampling values ​​of each branch at the point before the current moment and the sampling value before the half-wave at the point before the current moment, which is defined as the sampling sum of the previous point. If the difference between the sampling sum of the previous point and the sampling sum of the current moment is greater than the sampling abnormality threshold value, the third calculation module is called.

[0131] The third calculation module is used to calculate the sum of the sampling values ​​of each branch two weeks before the current moment and the sampling values ​​before the half-wave two weeks before the current moment, which is defined as the sampling sum of the previous two weeks. If the difference between the sampling sum of the previous two weeks and the sampling sum at the current moment is greater than the sampling abnormality threshold, the data of the branch is defined as abnormal and the protection function is locked out.

[0132] The abnormal protection module is used to detect fault signals of the power system, and based on the fault abnormality diagnosis, open the failure protection function and trip the abnormal branch and other branches in turn.

[0133] In the description of the present invention, the abnormal protection module includes: a fault diagnosis unit, a sampling and counting unit, and a trip protection unit.

[0134] The fault diagnosis unit is used to do nothing if the power system does not fail and the busbar protection device does not receive the start failure input signal. If the power system fails, the protection is activated and the start failure input signal is closed.

[0135] The sampling and accounting unit is used to include the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment before into the current data calculation of the data abnormal branch. If the zero-sequence current, phase current or phase current mutation meets the judgment conditions at this time, the tripping protection unit is called.

[0136] The tripping protection unit is used to open the failure protection function, first tripping the data abnormal branch, and then delaying the preset time to trip all other branches connected to the bus.

[0137] In the description of the present invention, the sampling and counting unit includes: a phase current counting unit and a zero-sequence current counting unit.

[0138] Among them, the phase current counting unit is used to count the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment before into the phase current calculation process of the data abnormal branch.

[0139] The zero-sequence current counting unit is used to count the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment before into the zero-sequence current calculation process of the data abnormal branch.

[0140] According to a specific embodiment of the present invention, the memory lock exception of branch 1 is taken as an example.

[0141] The present invention relates to a memory lock fault identification and failure protection optimization processing method, such as Figure 2 As shown, it mainly includes the following steps:

[0142] Step 1: Based on the existing traditional sampling and traditional tripping digital bus protection device AC plug-in, sampling is performed to obtain the secondary side current information of each branch current transformer CT in real time;

[0143] The sampling value of each branch at the current moment And the sampling value of half wave front The sampling value of each branch one point before the current time and its half-wavefront sampling value The sampling values ​​of each branch two weeks ago at the current moment and its half-wavefront sampling value

[0144] Step 2: Calculate the sampling current change of the three-phase current value of each branch:

[0145]

[0146] in, For branch m The current change at the current sampling point k of the phase current, is the A phase, B phase or C phase of the three-phase current, For branch m The sampling current value of the current sampling point k of the phase current, For branch m The current sampling point k of the phase current corresponds to the sampling current value of the two-cycle points in the previous cycle, where N is the number of two-cycle sampling points, i.e. 48.

[0147] Step 3: According to the characteristic that the sum of the current sampling value of the sine wave and the sampling value before the half wave is 0, calculate the sum of the current sampling value of the first branch and the sampling value before the half wave; if its absolute value is greater than the sampling abnormality threshold, exclude the normal standard waveform and go to step 4. The judgment condition that the absolute value of the sum of the current sampling value of the first branch and the sampling value before the half wave is greater than the sampling abnormality threshold is:

[0148]

[0149]

[0150] in, is the sum of the sampling value of branch m at the current k moment and the sampling value at the half-wavefront moment, I set1is the sampling abnormal threshold, taking into account the zero drift of the sampling plug-in, and the value is 0.05In, where In is the secondary rated value of the current.

[0151] Step 4: Using the characteristics of the current amplitude decreasing over time of the tail current and the attenuated DC component, determine whether the sum of the current sampling value of the first branch and the sampling value before the half-wave is greater than K times the current sampling value. If so, exclude the tail current and the attenuated DC component and proceed to step 5, which is specifically:

[0152]

[0153] Among them, K is the proportionality coefficient, and its value is 0.9.

[0154] Step 5: Calculate the sum of the sampling value of the first branch before the current moment and the sampling value before the half-wave moment; if the difference between the sum of the sampling value of the first branch at the current moment and the sampling value before the half-wave moment is greater than the sampling abnormality threshold, proceed to step 6, which is:

[0155]

[0156]

[0157] in, It is the sum of the sampling value of branch m at the point before the current k moment and its sampling value half a wave ago.

[0158] Step 6: To prevent the numerical fluctuation of the sampling branch and ensure reliability, calculate the sum of the two wavefront sampling values ​​of the first branch at the current moment and the sampling value at the half wavefront moment; if the difference between the sum of the sampling value of the first branch at the current moment and the sampling value at the half wavefront moment is greater than the sampling abnormality threshold, identify the data abnormality of the first branch, lock the failure protection function, and go to step 7, which is specifically:

[0159]

[0160]

[0161] in, It is the sum of the two wavefront sampling values ​​of branch m at the current time k and its half wavefront sampling value at the current time k.

[0162] Step 7: If the power system does not fail, the busbar protection device does not receive the start failure input signal and does not perform any processing; if the power system fails, the protection is activated, the start failure input signal is closed, and then go to step 8.

[0163] Step 8: According to the waveform characteristics after the memory is locked, the sum of the sampling value of the abnormal branch at the current moment and the sampling value at the half-wave moment is constant and has a large value. The sum of the sampling value of the first branch at the current moment and the sampling value at the half-wave moment is included in the calculation of the zero-sequence current and phase current of the first branch. If the zero-sequence current, phase current or phase current mutation conditions are met at this time, then go to step 9, which specifically includes the following operations:

[0164] Step 8.1, the sum of the current sampling value of the first branch and the sampling value before the half-wave is included in the calculation of the phase current of the branch with abnormal data, specifically:

[0165]

[0166]

[0167]

[0168] in, is the effective value of the current of phase A, phase B and phase C of the first branch, is the branch m at sampling point i Phase current; represents the sinusoidal phase coefficient; Represents the cosine term coefficient; N′ represents the number of sampling points per cycle is 24; k represents the current sampling point.

[0169] Step 8.2: The sum of the current sampling value of the first branch and the sampling value before the half-wave is included in the calculation of the zero-sequence current of the data abnormal branch.

[0170] Specifically:

[0171]

[0172] in, is the effective value of the zero-sequence current of the first branch, is the effective value of the A phase current of the first branch, is the effective value of the B phase current of the first branch, is the effective value of the C phase current of the first branch.

[0173] Step 8.3: The determination conditions that the zero-sequence current, phase current or phase current mutation quantity meets are:

[0174]

[0175]

[0176]

[0177] Among them, I set0 is the zero-sequence current threshold of the first branch, Iset It is the three-phase current mutation threshold of the first branch. It is set by the on-site operation and maintenance personnel according to the characteristics of the power grid. In represents the rated value of the secondary side of the CT, which is 1A or 5A according to the on-site CT model.

[0178] Step 9: Open the failure protection function. At this time, the first branch will be tripped first, and all other branches connected to the bus will be tripped after a delay of 150ms.

[0179] To sum up, with the help of the above-mentioned technical scheme of the present invention, the present invention collects the current information of each branch in real time based on the bus protection, calculates the change of each branch current, judges whether the sampling value has a mutation, and identifies abnormal data based on the sum of the sampling value of each branch at the current moment and the sampling value at the half-wave front moment and its backward differential characteristics. If the data is abnormal, the failure protection is locked. When it is identified as data abnormality, the power system fails, the protection action starts the failure input signal closure, and the sampling data characteristics at the abnormal moment are taken into account for optimization processing; this method can correctly identify the abnormality of branch sampling value data, effectively prevent the bus protection device from malfunctioning, and at the same time adopt an intelligent processing method for sampling data at abnormal moments, which better improves the reliability of bus protection under abnormal sampling data conditions and ensures the safe and stable operation of the power system.

[0180] It should be understood that, although the steps in the flowchart of the accompanying drawings are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least a part of the steps in the flowchart of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps.

Claims

1. A method for memory lock fault identification and failure protection optimization processing, characterized in that: The method comprises the following steps: S1, real-time acquisition of secondary current information of each branch current transformer; S2. Calculate the sampling current change of the three-phase current value of each branch based on the current information; S3. Based on the sampling values ​​of each branch at the current moment and the sampling values ​​at the half-wave front moment, abnormal data is identified, and based on the abnormal identification results, the locking failure protection or the opening failure protection is called.

2. The method for memory lock fault identification and failure protection optimization processing according to claim 1, characterized in that: The current information includes: the sampling values ​​of each branch at the current moment, the sampling values ​​of each half-wave moment, the sampling values ​​of each branch at one point before the current moment, the sampling values ​​of each branch two weeks ago at the current moment, and the sampling values ​​of each half-wave moment two weeks ago at the current moment.

3. The method for memory lock fault identification and failure protection optimization processing according to claim 1, characterized in that: The calculation formula for calculating the sampling current change of the three-phase current value of each branch is: In the formula, Indicates branch m The current change at the current sampling point k of the phase current; Indicates branch m The sampling current value of the current sampling point k of the phase current; Indicates branch m The current sampling value of the previous two-cycle points corresponding to the current sampling point k of the phase current; Indicates phase A, phase B or phase C of three-phase current; N represents the number of two-wave sampling points.

4. The method for memory lock fault identification and failure protection optimization processing according to claim 2, characterized in that: The method of identifying abnormal data based on the sampling values ​​of each branch at the current moment and the sampling values ​​at the half-wave front moment, and calling the blocking failure protection or the opening failure protection based on the abnormal identification result comprises the following steps: S31, calculating the sum of the sampling values ​​of each branch at the current moment and the sampling value at the half-wave front moment, which is defined as the sampling sum at the current moment. If the absolute value of the sampling sum at the current moment is greater than the sampling abnormality threshold value, the normal standard waveform is excluded, and step S32 is executed; S32, judging whether the current sampling sum of each branch is greater than K times the current sampling value of each branch, if so, excluding the tail current and the attenuated DC component, and executing step S33; S33, calculating the sum of the sampling values ​​of each branch at the previous point of the current moment and the sampling value before the half-wave at the previous point of the current moment, which is defined as the previous point sampling sum. If the difference between the previous point sampling sum and the current moment sampling sum is greater than the sampling abnormality threshold value, executing step S34; S34, calculate the sum of the sampling values ​​of each branch two weeks before the current moment and the sampling values ​​before the half-wave two weeks before the current moment, and define it as the sampling sum of the previous two weeks. If the difference between the sampling sum of the previous two weeks and the sampling sum of the current moment is greater than the sampling abnormality threshold, it is defined that the data of the branch is abnormal, the failure protection function is locked, and step S35 is executed; S35. Detect the fault signal of the power system, and based on the fault abnormality diagnosis, open the failure protection function, and trip the abnormal branch and other branches in turn.

5. The method for memory lock fault identification and failure protection optimization processing according to claim 4, characterized in that: The method of detecting a fault signal of the power system, and based on the fault abnormality diagnosis, opening the failure protection function, and sequentially tripping the abnormal branch and other branches includes the following steps: S351, if the power system has not failed and the busbar protection device has not received the start failure input signal, no processing is performed; if the power system has failed, the protection is activated, the start failure input signal is closed, and step S352 is executed; S352, the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment is included in the calculation of the current data of the data abnormal branch. If the zero-sequence current, phase current or phase current mutation quantity meets the judgment condition at this time, step S353 is executed; S353, open the failure protection function, first trip the data abnormal branch, and delay the preset time to trip all other branches connected to the bus.

6. A memory lock fault identification and failure protection optimization processing method according to claim 5, characterized in that: The process of including the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave front moment into the calculation of the current data of the data abnormal branch comprises the following steps: S3521, taking the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment into the calculation process of the phase current of the data abnormal branch; S3522. The sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment is included in the calculation process of the zero-sequence current of the data abnormal branch.

7. The method for memory lock fault identification and failure protection optimization processing according to claim 6, characterized in that: The calculation formula for including the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave front moment in the calculation process of the phase current of the data abnormal branch includes: In the formula, Indicates the effective value of the current of phase A, phase B and phase C of the data abnormal branch m; It represents the sum of the sampling value of branch m at the current k moment and the sampling value at the half-wave front moment; Indicates the branch m at sampling point i Phase current. represents the sinusoidal phase coefficient; represents the cosine term coefficient; N′ means the number of sampling points in one cycle is 24; k represents the current sampling point.

8. The method for memory lock fault identification and failure protection optimization processing according to claim 7, characterized in that: The calculation formula for including the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave front moment in the calculation process of the zero-sequence current of the data abnormal branch is: In the formula, Indicates the effective value of zero-sequence current of data abnormal branch m; Indicates the effective value of the phase A current of the data abnormal branch m; Indicates the effective value of the B-phase current of the data abnormal branch m; Indicates the effective value of the C-phase current of the data abnormal branch m.

9. A memory lock fault identification and failure protection optimization process according to claim 8 The method is characterized in that The determination conditions satisfied by the zero-sequence current, phase current or phase current mutation amount include: In the formula, Indicates the effective value of zero-sequence current of data abnormal branch m; Indicates the effective value of the current of phase A, phase B and phase C of the data abnormal branch m; Indicates the current change at the current sampling point k of the φ phase current of the data abnormal branch m; I set0 Indicates the zero-sequence current threshold of the data abnormal branch m; I set Indicates the threshold of the three-phase current mutation of the data abnormal branch m; I n Indicates the CT secondary rating.

10. A memory lock fault identification and failure protection optimization processing system, used to implement the memory lock fault identification and failure protection optimization processing method according to any one of claims 1 to 9, characterized in that: The system includes: Current monitoring module, used to obtain the secondary side current information of each branch current transformer in real time; A variation calculation module is used to calculate the sampled current variation of the three-phase current values ​​of each branch based on the current information; The protection optimization module is used to identify abnormal data based on the sampling values ​​of each branch at the current moment and the sampling values ​​at the half-wave moment before, and to call the lock failure protection or open failure protection based on the abnormal identification results.

11. A memory lock fault identification and failure protection optimization processing system according to claim 10, characterized in that: The current information includes: the sampling values ​​of each branch at the current moment, the sampling values ​​of each half-wave moment, the sampling values ​​of each branch at one point before the current moment, the sampling values ​​of each branch two weeks ago at the current moment, and the sampling values ​​of each half-wave moment two weeks ago at the current moment.

12. The memory lock fault identification and failure protection optimization processing system according to claim 10, characterized in that: The protection optimization module includes: a first calculation module, a sampling judgment module, a second calculation module, a third calculation module and an abnormal protection module; The first calculation module is used to calculate the sum of the sampling values ​​of each branch at the current moment and the sampling value at the half-wave front moment, which is defined as the sampling sum at the current moment. If the absolute value of the sampling sum at the current moment is greater than the sampling abnormality threshold value, the normal standard waveform is excluded; The sampling judgment module is used to judge whether the current sampling sum of each branch is greater than K times the current sampling value of each branch. If so, the tail current and the attenuated DC component are excluded; The second calculation module is used to calculate the sum of the sampling values ​​of each branch at a point before the current moment and the sampling value before the half-wave at a point before the current moment, which is defined as the sampling sum at the previous point. If the difference between the sampling sum at the previous point and the sampling sum at the current moment is greater than the sampling abnormality threshold value, the third calculation module is called; The third calculation module is used to calculate the sum of the sampling values ​​of each branch two weeks before the current moment and the sampling values ​​before the half-wave two weeks before the current moment, which is defined as the sampling sum of the previous two weeks. If the difference between the sampling sum of the previous two weeks and the sampling sum of the current moment is greater than the sampling abnormality threshold, it is defined that the data of the branch is abnormal, and the protection function is locked out; The abnormal protection module is used to detect fault signals of the power system, and based on the fault abnormality diagnosis, open the failure protection function and sequentially trip the abnormal branch and other branches.

13. A memory lock fault identification and failure protection optimization processing system according to claim 12, characterized in that: The abnormal protection module includes: a fault diagnosis unit, a sampling and counting unit and a trip protection unit; The fault diagnosis unit is used to: if the power system does not fail and the busbar protection device does not receive the start failure input signal, no processing is performed; if the power system fails, the protection is activated and the start failure input signal is closed; The sampling and counting unit is used to count the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment into the calculation of the current data of the data abnormal branch. If the zero-sequence current, phase current or phase current mutation quantity meets the judgment condition at this time, the tripping protection unit is called; The tripping protection unit is used to open the failure protection function, first trip the data abnormal branch, and delay a predetermined time to trip all other branches connected to the bus.

14. A memory lock fault identification and failure protection optimization processing system according to claim 13, characterized in that: The sampling and counting unit includes: a phase current counting unit and a zero-sequence current counting unit; Wherein, the phase current counting unit is used to count the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave moment before into the phase current calculation process of the data abnormal branch; The zero-sequence current counting unit is used to count the sum of the sampling value of the data abnormal branch at the current moment and the sampling value at the half-wave front moment into the zero-sequence current calculation process of the data abnormal branch.

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