A transformer longitudinal differential protection false alarm prevention method, device, equipment and medium

Abstract

The application discloses a transformer longitudinal differential protection anti-misoperation method, device, equipment and medium, comprising the following steps: when detecting primary side current and secondary side current, calculating a differential current value by using the primary side current and the secondary side current; if the absolute value of the differential current value is greater than a preset current threshold value, recording a starting moment and calculating a plurality of action current absolute values in a preset criterion period from the starting moment by using the primary side current and the secondary side current according to a preset sampling period; calculating a plurality of action current slope absolute values corresponding to the plurality of action current absolute values; judging whether the action current absolute value and the action current slope absolute value meet a preset protection exit locking condition and recording an ending moment; if yes, and when the time difference between the starting moment and the ending moment is less than a preset time threshold value, locking the protection action exit. The problems that the transformer longitudinal differential protection anti-misoperation ability is low exist are solved.

Description

Technical Field

[0001] This invention relates to the field of transformer longitudinal differential protection technology, and in particular to a method, device, equipment and medium for preventing transformer longitudinal differential protection from malfunction. Background Technology

[0002] As people's living standards continue to improve, society's reliance on electricity is increasing, placing higher demands on the relay protection technology and management level of power systems. Transformers, as important electrical equipment widely used in power systems, are primarily protected by longitudinal differential protection when transformer winding faults occur.

[0003] Currently, existing transformer differential protection error prevention strategies mainly rely on the second harmonic braking principle, waveform discontinuity angle principle, and waveform asymmetry principle. However, since transformer inrush current can cause calculation errors in differential current criteria, and existing transformer differential protection error prevention mainly considers the tolerance of transformer inrush current and surge current, it does not adequately consider the saturation that occurs during normal transformer operation, resulting in low error prevention capability of transformer differential protection. Summary of the Invention

[0004] This invention provides a method, device, equipment, and medium for preventing transformer longitudinal differential protection from malfunction. It solves the technical problem that existing transformer longitudinal differential protection mainly considers the resistance to transformer inrush current and surge current, resulting in insufficient consideration of saturation that occurs during normal transformer operation, and thus low transformer longitudinal differential protection malfunction prevention capability.

[0005] This invention provides a method for preventing malfunctions in transformer longitudinal differential protection, comprising:

[0006] When the primary side current and the secondary side current are detected, the differential current value is calculated using the primary side current and the secondary side current;

[0007] If the absolute value of the differential current is greater than the preset current threshold, the start time is recorded and the absolute values ​​of multiple action currents within a preset criterion period from the start time are calculated using the primary side current and the secondary side current according to the preset sampling period.

[0008] Calculate the corresponding absolute values ​​of the slope of the multiple operating currents based on the multiple absolute values ​​of the operating currents;

[0009] Determine whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output blocking conditions and record the end time;

[0010] If the conditions are met, and the time difference between the start time and the end time is less than a preset time threshold, then the protection action exit is locked.

[0011] Optionally, the step of calculating the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected includes:

[0012] When the primary side current and the secondary side current are detected, the ratio of the secondary side current to the preset number of secondary side turns is calculated to determine the per-unit value of the secondary phase current;

[0013] Calculate the difference between the per-unit values ​​of the primary current and the secondary phase current to determine the differential current value.

[0014] Optionally, the step of recording the start-up time and calculating multiple absolute values ​​of operating current within a preset criterion period from the start-up time using the primary side current and the secondary side current according to a preset sampling period if the absolute value of the differential current is greater than a preset current threshold includes:

[0015] If the absolute value of the differential current is greater than the preset current threshold, record the start time;

[0016] Calculate the ratio of the primary current to the preset number of turns in the primary winding and the ratio of the secondary current to the preset number of turns in the secondary winding, respectively, to determine the per-unit value of the primary phase current and the per-unit value of the secondary phase current.

[0017] The difference between the per-unit value of the primary phase current and the per-unit value of the secondary phase current is calculated according to a preset sampling period, and the absolute values ​​of multiple operating currents within a preset criterion period from the start time are determined.

[0018] Optionally, the step of calculating the absolute values ​​of the slopes of the corresponding multiple operating currents based on the multiple absolute values ​​of the operating currents includes:

[0019] The absolute values ​​of the operating current in two adjacent preset sampling periods are selected from all the absolute values ​​of the operating current in sequence;

[0020] Calculate the difference between the absolute values ​​of the operating current in two adjacent preset sampling periods, and determine the corresponding absolute values ​​of the slope of multiple operating currents.

[0021] Optionally, the preset criterion period includes a preset first period and a preset second period, and the step of determining whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output blocking conditions and recording the end time includes:

[0022] The maximum value of the absolute value of the operating current and the maximum value of the absolute value of the operating current slope within the preset first cycle are selected respectively to determine the maximum value of the first operating current and the maximum value of the first operating slope.

[0023] The maximum value of the absolute value of the operating current and the maximum value of the absolute value of the operating current slope within the preset second cycle are selected respectively to determine the maximum value of the second operating current and the maximum value of the second operating slope.

[0024] Compare the maximum value of the first operating current with the maximum value of the second operating current to determine the first comparison result;

[0025] Compare the maximum slope of the first action with the maximum slope of the second action to determine the second comparison result;

[0026] Determine whether the first comparison result and the second comparison result meet the preset protection exit locking conditions and record the end time.

[0027] Optionally, if the absolute value of the differential current is less than the preset current threshold, or if the time difference between the start time and the end time is greater than the preset time threshold, then the process jumps to the step of calculating the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected.

[0028] If the conditions are not met, the unlocking protection action will proceed.

[0029] Optionally, after the step of determining whether the first comparison result and the second comparison result meet the preset protection exit interlocking conditions and recording the end time, the method includes:

[0030] If the maximum value of the first operating current is greater than the maximum value of the second operating current and the maximum value of the first operating slope is greater than the maximum value of the second operating slope, then it is determined that the first comparison result and the second comparison result satisfy the preset protection output blocking condition and the end time is recorded.

[0031] If the maximum value of the first operating current is less than the maximum value of the second operating current or / and the maximum value of the first operating slope is less than the maximum value of the second operating slope, then it is determined that the first comparison result and the second comparison result do not meet the preset protection output blocking conditions and the end time is recorded.

[0032] A second aspect of the present invention provides a transformer longitudinal differential protection anti-malfunction device, comprising:

[0033] The current detection module is used to calculate the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected.

[0034] The start-up criterion module is used to record the start-up time and calculate multiple absolute values ​​of action current within a preset criterion period from the start-up time using the primary side current and the secondary side current according to a preset sampling period if the absolute value of the differential current value is greater than a preset current threshold.

[0035] The current slope calculation module is used to calculate the corresponding absolute values ​​of multiple operating current slopes based on the multiple absolute values ​​of the operating current.

[0036] The interlocking judgment module is used to determine whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output interlocking conditions and record the end time.

[0037] The interlocking module is configured to interlock the protection action output if the time difference between the start time and the end time is less than a preset time threshold.

[0038] A third aspect of the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the transformer differential protection anti-malfunction method as described in any of the preceding claims.

[0039] The fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, it implements the transformer differential protection anti-malfunction method as described in any of the preceding claims.

[0040] As can be seen from the above technical solutions, the present invention has the following advantages:

[0041] When primary and secondary currents are detected, a differential current value is calculated using the primary and secondary currents. If the absolute value of the differential current is greater than a preset current threshold, the start time is recorded, and multiple absolute values ​​of operating currents within a preset criterion period from the start time are calculated using the primary and secondary currents according to a preset sampling period. Multiple absolute values ​​of operating current slopes are calculated based on these multiple absolute values. It is determined whether the absolute values ​​of the operating current and the absolute values ​​of the operating current slopes meet preset protection output blocking conditions, and the end time is recorded. If they meet the conditions, and the time difference between the start time and the end time is less than a preset time threshold, the protection output is blocked. This solves the technical problem that existing transformer differential protection mainly considers the withstand of transformer inrush current and surge current, resulting in insufficient consideration of saturation during normal transformer operation and low transformer differential protection error prevention capability. It effectively improves the error prevention capability of transformer differential protection and has no requirements for discontinuity angle and waveform asymmetry, and is unaffected by changes in waveform discontinuity angle and asymmetry. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart of the steps of a transformer longitudinal differential protection anti-malfunction method provided in Embodiment 1 of the present invention;

[0044] Figure 2 This is a flowchart illustrating the steps of a transformer longitudinal differential protection anti-malfunction method provided in Embodiment 2 of the present invention;

[0045] Figure 3 This is a flowchart illustrating an application example of a transformer longitudinal differential protection anti-malfunction method provided in Embodiment 2 of the present invention.

[0046] Figure 4 This is a structural block diagram of a transformer longitudinal differential protection anti-malfunction device provided in Embodiment 3 of the present invention. Detailed Implementation

[0047] This invention provides a method, device, equipment, and medium for preventing transformer longitudinal differential protection from malfunction, which addresses the technical problem that existing transformer longitudinal differential protection mainly considers the resistance to transformer inrush current and surge current, resulting in insufficient consideration of saturation that occurs during normal transformer operation and thus low transformer longitudinal differential protection malfunction prevention capability.

[0048] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] Please see Figure 1 , Figure 1 The flowchart illustrates the steps of a transformer longitudinal differential protection anti-malfunction method provided in Embodiment 1 of the present invention.

[0050] This invention provides a method for preventing malfunctions in transformer longitudinal differential protection, comprising:

[0051] Step 101: When the primary side current and the secondary side current are detected, the differential current value is calculated using the primary side current and the secondary side current.

[0052] It should be noted that the primary and secondary currents are detected in real time, and the differential current value is calculated in real time using the primary and secondary currents.

[0053] In this embodiment of the invention, the primary side current and the secondary side current are detected in real time, and the differential current value is calculated in real time using the primary side current and the secondary side current.

[0054] Step 102: If the absolute value of the differential current is greater than the preset current threshold, record the start time and use the primary side current and secondary side current to calculate the absolute values ​​of multiple action currents within the preset criterion period from the start time according to the preset sampling period.

[0055] It should be noted that the absolute value of the differential current is compared with a preset current threshold. The start time is recorded only when the start criterion is met—that is, only when the absolute value of the differential current is greater than the preset current threshold. Then, the absolute values ​​of multiple operating currents within the preset criterion period from the start time are calculated using the primary and secondary currents according to a preset sampling period. The preset criterion period refers to a time interval for calculating the absolute values ​​of multiple operating currents. Each start time is an integer multiple of 20ms; for example, the start time is 40ms. After the start returns, if the start criterion is met again, the process restarts. In this embodiment of the invention, the preset current threshold, preset sampling period, and start criterion can be set as needed and are not specifically limited here.

[0056] Furthermore, the triggering criterion is:

[0057]

[0058] In the formula, I is the absolute value of the differential current. set This is the preset current threshold.

[0059] In this embodiment of the invention, if the absolute value of the differential current is greater than a preset current threshold, the start time is recorded and the absolute values ​​of multiple action currents within a preset criterion period from the start time are calculated using the primary side current and the secondary side current according to a preset sampling period.

[0060] Step 103: Calculate the absolute values ​​of the slopes of the multiple operating currents based on the absolute values ​​of the multiple operating currents.

[0061] In this embodiment of the invention, multiple absolute values ​​of the slope of the corresponding operating current are calculated based on multiple absolute values ​​of the operating current.

[0062] Step 104: Determine whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output blocking conditions and record the end time.

[0063] In this embodiment of the invention, it is determined whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output blocking conditions and the end time is recorded.

[0064] Step 105: If the conditions are met, and the time difference between the start time and the end time is less than the preset time threshold, then the protection action output is blocked.

[0065] It should be noted that, in this embodiment of the invention, the preset time threshold is set to 40ms.

[0066] In this embodiment of the invention, if the condition is met, and the time difference between the start time and the end time is less than a preset time threshold, then the protection action output is locked.

[0067] In this embodiment of the invention, when primary and secondary currents are detected, the differential current value is calculated using the primary and secondary currents. If the absolute value of the differential current value is greater than a preset current threshold, the start time is recorded, and the absolute values ​​of multiple operating currents within a preset criterion period from the start time are calculated using the primary and secondary currents according to a preset sampling period. The absolute values ​​of multiple operating current slopes are calculated based on these absolute values. It is determined whether the absolute values ​​of the operating currents and the absolute values ​​of the operating current slopes meet the preset protection output blocking conditions, and the end time is recorded. If they meet the conditions, and the time difference between the start and end times is less than a preset time threshold, the protection operation output is blocked. This solves the technical problem that existing transformer differential protection mainly considers the withstand of transformer inrush current and surge current, resulting in insufficient consideration of saturation during normal transformer operation and low transformer differential protection error prevention capability. This invention effectively improves the error prevention capability of transformer differential protection and has no requirements for discontinuity angle and waveform asymmetry, and is unaffected by changes in waveform discontinuity angle and asymmetry.

[0068] Please see Figure 2 , Figure 2 This is a flowchart illustrating the steps of a transformer longitudinal differential protection anti-malfunction method provided in Embodiment 2 of the present invention.

[0069] This invention provides a method for preventing malfunctions in transformer longitudinal differential protection, comprising:

[0070] Step 201: When the primary side current and the secondary side current are detected, calculate the ratio of the secondary side current to the preset number of secondary side turns, and determine the per-unit value of the secondary phase current.

[0071] It should be noted that the preset number of secondary turns refers to the number of turns in the secondary winding of the transformer. Taking the primary current as I1, the turns ratio conversion operation is performed on the secondary current, that is, the ratio of the secondary current to the number of turns in the secondary winding is calculated to obtain the per-unit value of the secondary phase current I2.

[0072] In this embodiment of the invention, when the primary side current and the secondary side current are detected, the ratio of the secondary side current to the preset number of secondary side turns is calculated to determine the per-unit value of the secondary phase current.

[0073] Step 202: Calculate the difference between the per-unit values ​​of the primary current and the secondary phase current to determine the differential current value.

[0074] It should be noted that the primary current I1 and the per-unit value of the secondary phase current I2, i.e., I1-I2, are calculated to obtain the differential current value, and the absolute value of the differential current value is compared with the preset current threshold.

[0075] In this embodiment of the invention, the difference between the per-unit values ​​of the primary current and the secondary phase current is calculated to determine the differential current value.

[0076] Step 203: If the absolute value of the differential current is greater than the preset current threshold, record the start time and use the primary side current and secondary side current to calculate the absolute values ​​of multiple action currents within the preset criterion period from the start time according to the preset sampling period.

[0077] Furthermore, step 203 may include the following sub-steps:

[0078] Step S31: If the absolute value of the differential current is greater than the preset current threshold, record the start time.

[0079] In this embodiment of the invention, if the absolute value of the differential current is greater than a preset current threshold, the start-up time is recorded.

[0080] Step S32: Calculate the ratio of the primary current to the preset number of turns in the primary winding and the ratio of the secondary current to the preset number of turns in the secondary winding, and determine the per-unit value of the primary phase current and the per-unit value of the secondary phase current.

[0081] The preset primary winding turns refer to the number of turns in the primary winding of the transformer.

[0082] It should be noted that both the primary and secondary currents are phase currents. If the primary or secondary current is found to be not a phase current, the absolute value of the operating current is calculated using the value of the phase current measurement point. Both the primary and secondary currents are converted into per-unit values ​​of phase current. That is, the per-unit values ​​of the primary and secondary phase currents are determined by calculating the ratio of the primary current to the number of turns in the primary winding and the ratio of the secondary current to the number of turns in the secondary winding.

[0083] In this embodiment of the invention, the ratio of the primary current to the preset number of turns in the primary winding and the ratio of the secondary current to the preset number of turns in the secondary winding are calculated respectively to determine the per-unit value of the primary phase current and the per-unit value of the secondary phase current.

[0084] Step S33: Calculate the difference between the per-unit value of the primary phase current and the per-unit value of the secondary phase current according to the preset sampling period, and determine the absolute values ​​of multiple operating currents within the preset criterion period from the start time.

[0085] It should be noted that, according to the preset sampling period, the per-unit value of the primary phase current is subtracted from the per-unit value of the secondary phase current. That is, the difference between the per-unit value of the primary phase current and the per-unit value of the secondary phase current is calculated according to the preset sampling period to determine the absolute values ​​of multiple operating currents within the preset criterion period from the start time.

[0086] In this embodiment of the invention, the difference between the per-unit value of the primary phase current and the per-unit value of the secondary phase current is calculated according to a preset sampling period, and the absolute values ​​of multiple operating currents within a preset criterion period from the start time are determined.

[0087] Step 204: Calculate the absolute values ​​of the slopes of the multiple operating currents based on the absolute values ​​of the multiple operating currents.

[0088] Furthermore, step 204 may include the following sub-steps:

[0089] Step S41: Select the absolute values ​​of the operating current from two adjacent preset sampling periods among all the absolute values ​​of the operating current.

[0090] It should be noted that the absolute values ​​of the operating current in two adjacent preset sampling periods are selected sequentially from all the absolute values ​​of the operating current within the preset criterion period.

[0091] In this embodiment of the invention, the absolute values ​​of the operating current in two adjacent preset sampling periods are selected from all the absolute values ​​of the operating current.

[0092] Step S42: Calculate the difference between the absolute values ​​of the operating current in two adjacent preset sampling periods, and determine the absolute values ​​of the slopes of the corresponding multiple operating currents.

[0093] It should be noted that the absolute values ​​of multiple operating current slopes are determined by calculating the difference between the absolute values ​​of the operating current in every two adjacent preset sampling periods. The sign operator for calculating the difference between the absolute values ​​of the operating current in two adjacent preset sampling periods is:

[0094]

[0095] In the formula, The absolute value of the slope of the operating current. Let be the absolute value of the operating current at time t. Let Δt be the absolute value of the operating current in the sampling period adjacent to the absolute value of the operating current at time t, where t is a discrete time series and Δt is the sampling period.

[0096] Furthermore, the sign operator for calculating the difference between the absolute values ​​of the operating current in two adjacent preset sampling periods can also be defined as the absolute value of the average operating current slope over multiple preset sampling periods. That is, the sign operator for calculating the absolute value of the average operating current slope over two adjacent preset sampling periods is:

[0097]

[0098] In the formula, This represents the absolute value of the slope of the average operating current. The absolute value of the slope of the operating current. To and The absolute value of the operating current slope in adjacent sampling periods.

[0099] In this embodiment of the invention, the difference between the absolute values ​​of the operating current in two adjacent preset sampling periods is calculated to determine the corresponding absolute values ​​of multiple operating current slopes.

[0100] Step 205: Determine whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output blocking conditions and record the end time.

[0101] It should be noted that the preset criterion period includes a preset first period and a preset second period. The preset protection output blocking conditions are then determined based on the absolute value of the operating current and the absolute value of the operating current slope within the preset first period and the absolute value of the operating current and the absolute value of the operating current slope within the preset second period, and the end time is recorded.

[0102] Furthermore, step 205 may include the following sub-steps:

[0103] Step S51: Select the maximum value of the absolute value of the operating current and the maximum value of the absolute value of the operating current slope within the preset first cycle, and determine the maximum value of the first operating current and the maximum value of the first operating slope.

[0104] It should be noted that the sign operator for selecting the maximum value of the absolute value of the operating current or the absolute value of the operating current slope within the preset period is:

[0105]

[0106] In the formula, The maximum value of the absolute value of the operating current or the absolute value of the operating current slope within the preset period; It is the set of absolute values ​​of operating current or absolute values ​​of operating current slope within a preset period; T1 is the start time of the preset period, and T2 is the end time of the preset period. It is the absolute value of the operating current or the absolute value of the operating current slope at time T1+Δt.

[0107] In this embodiment of the invention, the maximum value of the absolute value of the operating current and the maximum value of the absolute value of the operating current slope within a preset first cycle are selected respectively to determine the maximum value of the first operating current and the maximum value of the first operating slope.

[0108] Step S52: Select the maximum value of the absolute value of the operating current and the maximum value of the absolute value of the operating current slope within the preset second cycle, and determine the maximum value of the second operating current and the maximum value of the second operating slope.

[0109] In this embodiment of the invention, the maximum value of the absolute value of the operating current and the maximum value of the absolute value of the operating current slope within a preset second cycle are selected respectively to determine the maximum value of the second operating current and the maximum value of the second operating slope.

[0110] Step S53: Compare the maximum value of the first operating current and the maximum value of the second operating current to determine the first comparison result.

[0111] The first comparison result includes either the first operating current maximum value being greater than the second operating current maximum value, or the first operating current maximum value being less than the second operating current maximum value.

[0112] It should be noted that the maximum absolute value of the operating current in the preset first cycle is compared with the maximum absolute value of the operating current in the preset second cycle, that is, the maximum value of the first operating current and the maximum value of the second operating current are compared.

[0113] In this embodiment of the invention, the maximum value of the first operating current and the maximum value of the second operating current are compared to determine the first comparison result.

[0114] Step S54: Compare the maximum slope of the first action with the maximum slope of the second action to determine the second comparison result.

[0115] The second comparison result includes either the maximum slope of the first action being greater than the maximum slope of the second action, or the maximum slope of the first action being less than the maximum slope of the second action.

[0116] It should be noted that the maximum value of the absolute value of the operating current slope within the preset first cycle and the maximum value of the absolute value of the operating current slope within the preset second cycle are compared, that is, the maximum value of the first operating slope and the maximum value of the second operating slope are compared.

[0117] In this embodiment of the invention, the maximum value of the first action slope and the maximum value of the second action slope are compared to determine the second comparison result.

[0118] Step S55: Determine whether the first comparison result and the second comparison result meet the preset protection exit locking conditions and record the end time.

[0119] The preset protection exit locking conditions include anti-false alarm criterion C1 and anti-false alarm criterion C2.

[0120] It should be noted that the false positive criterion C1 is:

[0121]

[0122] In the formula, This is the maximum value of the first operating current;

[0123] T0 represents the maximum value of the second operating current; T0 is the start-up time.

[0124] Furthermore, the false positive prevention criterion C1 can also be defined as:

[0125]

[0126] In the formula, k1 is the first error prevention coefficient.

[0127] The criterion for preventing false positives, C2, is:

[0128]

[0129] In the formula, This represents the maximum slope of the first action.

[0130] T0 represents the maximum slope of the second action; T0 is the start time.

[0131] Furthermore, the false positive prevention criterion C2 can also be defined as:

[0132]

[0133] In the formula, k2 is the second error prevention coefficient.

[0134] Furthermore, based on the first comparison result and the second comparison result, it is determined whether the preset protection exit locking condition is met and the end time is recorded.

[0135] In this embodiment of the invention, it is determined whether the first comparison result and the second comparison result meet the preset protection exit locking conditions and the end time is recorded.

[0136] Step S56: If the maximum value of the first operating current is greater than the maximum value of the second operating current and the maximum value of the first operating slope is greater than the maximum value of the second operating slope, then determine that the first comparison result and the second comparison result satisfy the preset protection output blocking condition and record the end time.

[0137] It should be noted that if the first comparison result is that the maximum value of the first operating current is greater than the maximum value of the second operating current and the second comparison result is that the maximum value of the first operating slope is greater than the maximum value of the second operating slope, then the first comparison result is judged to satisfy the anti-misoperation criterion C1 and the second comparison result is judged to satisfy the anti-misoperation criterion C2.

[0138] In this embodiment of the invention, if the maximum value of the first operating current is greater than the maximum value of the second operating current and the maximum value of the first operating slope is greater than the maximum value of the second operating slope, then it is determined that the first comparison result and the second comparison result satisfy the preset protection output blocking condition and the end time is recorded.

[0139] Step S57: If the maximum value of the first operating current is less than the maximum value of the second operating current or / and the maximum value of the first operating slope is less than the maximum value of the second operating slope, then it is determined that the first comparison result and the second comparison result do not meet the preset protection output blocking conditions and the end time is recorded.

[0140] It should be noted that if the first comparison result is that the maximum value of the first operating current is less than the maximum value of the second operating current, or the second comparison result is that the maximum value of the first operating slope is less than the maximum value of the second operating slope, or if the first comparison result is that the maximum value of the first operating current is less than the maximum value of the second operating current, and the second comparison result is that the maximum value of the first operating slope is less than the maximum value of the second operating slope, that is, when the first comparison result does not meet the anti-false judgment criterion C1 or the second comparison result does not meet the anti-false judgment criterion C2, or when both the first comparison result and the second comparison result do not meet the anti-false judgment criterion C1 and the anti-false judgment criterion C2, then it is determined that the first comparison result and the second comparison result do not meet the preset protection output blocking conditions and the end time is recorded.

[0141] In this embodiment of the invention, if the maximum value of the first operating current is less than the maximum value of the second operating current and / or the maximum value of the first operating slope is less than the maximum value of the second operating slope, then it is determined that the first comparison result and the second comparison result do not meet the preset protection output blocking conditions and the end time is recorded.

[0142] Step 206: If the conditions are met, and the time difference between the start time and the end time is less than the preset time threshold, then the protection action output is locked.

[0143] It should be noted that if the first comparison result and the second comparison result meet the preset protection output blocking conditions, and the time difference between the start time and the end time is less than the preset time threshold, then the protection action output will be blocked.

[0144] In this embodiment of the invention, if the condition is met, and the time difference between the start time and the end time is less than a preset time threshold, then the protection action output is locked.

[0145] Step 207: If the absolute value of the differential current is less than the preset current threshold, or if the time difference between the start time and the end time is greater than the preset time threshold, then proceed to the step of calculating the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected.

[0146] It should be noted that if the absolute value of the differential current is less than the preset current threshold, or if the first comparison result and the second comparison result satisfy the preset protection output blocking condition and the end time is recorded, and the time difference between the start time and the end time is greater than the preset time threshold, then the process jumps to the step of re-judging whether the start criterion is met, that is, the process jumps to the step of calculating the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected.

[0147] In this embodiment of the invention, if the absolute value of the differential current is less than a preset current threshold, or if the time difference between the start time and the end time is greater than a preset time threshold, then the process jumps to the step of calculating the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected.

[0148] Step 208: If not satisfied, the unlocking protection action will exit.

[0149] It should be noted that if the first comparison result and the second comparison result do not meet the preset protection exit locking conditions, then the protection action exit is allowed, that is, the unlocking protection action exit is allowed.

[0150] In this embodiment of the invention, if the first comparison result and the second comparison result do not meet the preset protection exit blocking conditions, then the protection action exit is allowed.

[0151] Please see Figure 3 , Figure 3 This is a flowchart illustrating an application example of a transformer longitudinal differential protection anti-malfunction method provided in Embodiment 2 of the present invention.

[0152] When the anti-misoperation module is activated, it verifies whether the differential current meets the activation criterion S1 based on the program execution cycle. If the activation is met and S1 is satisfied, it checks whether the anti-misoperation criteria C1 and C2 are satisfied within the next 40ms. If the time exceeds 40ms, it restarts the check to see if S1 is satisfied. If C1 and C2 are satisfied within 40ms after S1 is satisfied, the protection output is blocked, and it is assumed that the differential current calculation is affected by interference such as inrush current. If C1 or C2 is not satisfied within 40ms after S1 is satisfied, the protection output is opened, allowing the protection to operate after meeting the operating conditions.

[0153] In this embodiment of the invention, when primary and secondary currents are detected, the differential current value is calculated using the primary and secondary currents. If the absolute value of the differential current value is greater than a preset current threshold, the start time is recorded, and the absolute values ​​of multiple operating currents within a preset criterion period from the start time are calculated using the primary and secondary currents according to a preset sampling period. The absolute values ​​of multiple operating current slopes are calculated based on these absolute values. It is determined whether the absolute values ​​of the operating currents and the absolute values ​​of the operating current slopes meet the preset protection output blocking conditions, and the end time is recorded. If they meet the conditions, and the time difference between the start and end times is less than a preset time threshold, the protection operation output is blocked. This solves the technical problem that existing transformer differential protection mainly considers the withstand of transformer inrush current and surge current, resulting in insufficient consideration of saturation during normal transformer operation and low transformer differential protection error prevention capability. This invention effectively improves the error prevention capability of transformer differential protection and has no requirements for discontinuity angle and waveform asymmetry, and is unaffected by changes in waveform discontinuity angle and asymmetry.

[0154] Please see Figure 4 , Figure 4 This is a structural block diagram of a transformer longitudinal differential protection anti-malfunction device provided in Embodiment 3 of the present invention.

[0155] The present invention provides a transformer longitudinal differential protection anti-malfunction device, comprising:

[0156] The current detection module 301 is used to calculate the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected.

[0157] The start criterion module 302 is used to record the start time and calculate the absolute values ​​of multiple action currents within the preset criterion period from the start time using the primary side current and the secondary side current according to the preset sampling period if the absolute value of the differential current is greater than the preset current threshold.

[0158] The current slope calculation module 303 is used to calculate the absolute values ​​of the slopes of multiple operating currents based on the absolute values ​​of multiple operating currents.

[0159] The interlocking module 304 is used to determine whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output interlocking conditions and record the end time.

[0160] The interlocking module 305 is used to interlock the protection action output if the conditions are met and the time difference between the start time and the end time is less than a preset time threshold.

[0161] Furthermore, the current detection module 301 includes:

[0162] The per-unit value determination submodule is used to calculate the ratio of the secondary current to the preset number of secondary turns when the primary current and secondary current are detected, and to determine the per-unit value of the secondary phase current.

[0163] The differential current calculation submodule is used to calculate the difference between the per-unit values ​​of the primary current and the secondary phase current to determine the differential current value.

[0164] Furthermore, the activation criterion module 302 includes:

[0165] The timing recording submodule is used to record the start time if the absolute value of the differential current is greater than a preset current threshold.

[0166] The ratio calculation submodule is used to calculate the ratio of the primary current to the preset number of turns in the primary winding and the ratio of the secondary current to the preset number of turns in the secondary winding, respectively, to determine the per-unit value of the primary phase current and the per-unit value of the secondary phase current.

[0167] The absolute value calculation submodule is used to calculate the difference between the per-unit value of the primary phase current and the per-unit value of the secondary phase current according to a preset sampling period, and to determine the absolute values ​​of multiple operating currents within a preset criterion period from the start time.

[0168] Furthermore, the current slope calculation module 303 includes:

[0169] The absolute value selection submodule is used to sequentially select the absolute values ​​of the operating current from two adjacent preset sampling periods among all the absolute values ​​of the operating current.

[0170] The difference calculation submodule is used to calculate the difference between the absolute values ​​of the operating current in two adjacent preset sampling periods and determine the absolute values ​​of the slopes of the corresponding multiple operating currents.

[0171] Furthermore, the locking module 304 includes:

[0172] The maximum current selection submodule is used to select the maximum absolute value of the operating current and the maximum absolute value of the operating current slope within the preset first cycle, respectively, to determine the maximum value of the first operating current and the maximum value of the first operating slope.

[0173] Select the slope submodule to select the maximum value of the absolute value of the operating current and the maximum value of the absolute value of the operating current slope within the preset second cycle, and determine the maximum value of the second operating current and the maximum value of the second operating slope.

[0174] The first comparison submodule is used to compare the maximum value of the first operating current and the maximum value of the second operating current to determine the first comparison result.

[0175] The second comparison submodule is used to compare the maximum value of the slope of the first action and the maximum value of the slope of the second action to determine the second comparison result.

[0176] The end time recording submodule is used to determine whether the first comparison result and the second comparison result meet the preset protection exit interlocking conditions and record the end time.

[0177] The judgment submodule is used to determine if the first comparison result and the second comparison result satisfy the preset protection output blocking conditions and record the end time if the maximum value of the first operating current is greater than the maximum value of the second operating current and the maximum value of the first operating slope is greater than the maximum value of the second operating slope.

[0178] The "Judgment Not Satisfied" submodule is used to determine that if the maximum value of the first operating current is less than the maximum value of the second operating current and / or the maximum value of the first operating slope is less than the maximum value of the second operating slope, then the first comparison result and the second comparison result do not satisfy the preset protection output blocking conditions and the end time is recorded.

[0179] Furthermore, it also includes:

[0180] The jump module is used to jump to the step of calculating the differential current value when the primary side current and secondary side current are detected if the absolute value of the differential current value is less than the preset current threshold or if the time difference between the start time and the end time is greater than the preset time threshold.

[0181] The unlocking module is used to trigger the unlocking protection action if the conditions are not met.

[0182] In this embodiment of the invention, when primary and secondary currents are detected, the differential current value is calculated using the primary and secondary currents. If the absolute value of the differential current value is greater than a preset current threshold, the start time is recorded, and the absolute values ​​of multiple operating currents within a preset criterion period from the start time are calculated using the primary and secondary currents according to a preset sampling period. The absolute values ​​of multiple operating current slopes are calculated based on these absolute values. It is determined whether the absolute values ​​of the operating currents and the absolute values ​​of the operating current slopes meet the preset protection output blocking conditions, and the end time is recorded. If they meet the conditions, and the time difference between the start and end times is less than a preset time threshold, the protection operation output is blocked. This solves the technical problem that existing transformer differential protection mainly considers the withstand of transformer inrush current and surge current, resulting in insufficient consideration of saturation during normal transformer operation and low transformer differential protection error prevention capability. This invention effectively improves the error prevention capability of transformer differential protection and has no requirements for discontinuity angle and waveform asymmetry, and is unaffected by changes in waveform discontinuity angle and asymmetry.

[0183] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, modules, and sub-modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0184] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0185] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0186] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0187] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0188] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preventing maloperation of longitudinal differential protection of transformer energizing inrush, characterized in that, include: When the primary side current and the secondary side current are detected, the differential current value is calculated using the primary side current and the secondary side current; If the absolute value of the differential current is greater than a preset current threshold, the start-up time is recorded, and the absolute values ​​of multiple operating currents within a preset criterion period from the start-up time are calculated using the primary current and the secondary current according to a preset sampling period, including: If the absolute value of the differential current is greater than the preset current threshold, record the start time; Calculate the ratio of the primary current to the preset number of turns in the primary winding and the ratio of the secondary current to the preset number of turns in the secondary winding, respectively, to determine the per-unit value of the primary phase current and the per-unit value of the secondary phase current. The difference between the per-unit value of the primary phase current and the per-unit value of the secondary phase current is calculated according to a preset sampling period, and the absolute values ​​of multiple operating currents within a preset criterion period from the start time are determined. Calculate multiple absolute values ​​of operating current slopes based on multiple absolute values ​​of the operating current, including: The absolute values ​​of the operating current in two adjacent preset sampling periods are selected from all the absolute values ​​of the operating current in sequence; Calculate the difference between the absolute values ​​of the operating current in two adjacent preset sampling periods, and determine the corresponding absolute values ​​of multiple operating current slopes; Determine whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output blocking conditions and record the end time; If the conditions are met, and the time difference between the start time and the end time is less than a preset time threshold, then the protection action exit is locked.

2. The transformer energizing inrush longitudinal differential protection misoperation prevention method according to claim 1, characterized in that, The step of calculating the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected includes: When the primary side current and the secondary side current are detected, the ratio of the secondary side current to the preset number of secondary side turns is calculated to determine the per-unit value of the secondary phase current; Calculate the difference between the per-unit values ​​of the primary current and the secondary phase current to determine the differential current value.

3. The method for preventing malfunctions in transformer inrush current differential protection according to claim 1, characterized in that, The preset criterion period includes a preset first period and a preset second period. The step of determining whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output blocking conditions and recording the end time includes: The maximum value of the absolute value of the operating current and the maximum value of the absolute value of the operating current slope within the preset first cycle are selected respectively to determine the maximum value of the first operating current and the maximum value of the first operating slope. The maximum value of the absolute value of the operating current and the maximum value of the absolute value of the operating current slope within the preset second cycle are selected respectively to determine the maximum value of the second operating current and the maximum value of the second operating slope. Compare the maximum value of the first operating current with the maximum value of the second operating current to determine the first comparison result; Compare the maximum slope of the first action with the maximum slope of the second action to determine the second comparison result; Determine whether the first comparison result and the second comparison result meet the preset protection exit locking conditions and record the end time.

4. The method for preventing malfunctions in transformer inrush current differential protection according to claim 1, characterized in that, Also includes: If the absolute value of the differential current is less than the preset current threshold, or if the time difference between the start time and the end time is greater than the preset time threshold, then proceed to the step of calculating the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected. If the conditions are not met, the unlocking protection action will proceed.

5. The method for preventing malfunctions in transformer inrush current differential protection according to claim 3, characterized in that, After determining whether the first comparison result and the second comparison result meet the preset protection exit locking conditions and recording the end time, the following steps are included: If the maximum value of the first operating current is greater than the maximum value of the second operating current and the maximum value of the first operating slope is greater than the maximum value of the second operating slope, then it is determined that the first comparison result and the second comparison result satisfy the preset protection output blocking condition and the end time is recorded. If the maximum value of the first operating current is less than the maximum value of the second operating current or / and the maximum value of the first operating slope is less than the maximum value of the second operating slope, then it is determined that the first comparison result and the second comparison result do not meet the preset protection output blocking conditions and the end time is recorded.

6. A differential protection device for transformer inrush current, applied to the differential protection method for transformer inrush current as described in claim 1, characterized in that, include: The current detection module is used to calculate the differential current value using the primary side current and the secondary side current when the primary side current and the secondary side current are detected. The start-up criterion module is used to record the start-up time and calculate multiple absolute values ​​of action current within a preset criterion period from the start-up time using the primary side current and the secondary side current according to a preset sampling period if the absolute value of the differential current value is greater than a preset current threshold. The current slope calculation module is used to calculate the corresponding absolute values ​​of multiple operating current slopes based on the multiple absolute values ​​of the operating current. The interlocking judgment module is used to determine whether the absolute value of the operating current and the absolute value of the operating current slope meet the preset protection output interlocking conditions and record the end time. The interlocking module is configured to interlock the protection action output if the time difference between the start time and the end time is less than a preset time threshold.

7. An electronic device, characterized in that, The device includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the steps of the differential protection method for transformer inrush current as described in any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed, it implements the longitudinal differential protection method for preventing malfunctions of transformer inrush current as described in any one of claims 1-5.

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