Ultrahigh-speed differential quick-break protection method and device for converter transformer

Abstract

The invention relates to an ultra-high-speed differential quick-break protection method and device for a converter transformer, and belongs to the technical field of converter transformers. If adjacent sampling points of the converter transformer meet the condition that the current differential current instantaneous value variable quantity reaches a preset first current threshold value used for judging whether abrupt change current is generated in a circuit or not, the abrupt change current is generated in the circuit; if so, starting a first broadening time; according to the differential current instantaneous value variable quantity and a preset differential quick-break current value, first time period point extraction judgment is carried out; according to the absolute value variable quantity of the voltage instantaneous value and a preset first voltage threshold value used for judging whether the converter transformer is being charged or not, comprehensive voltage out-of-limit judgment in a second time period is carried out; and in the first broadening time, in response to the condition that the criterion of point extraction judgment in the first time period is met and the criterion of comprehensive voltage out-of-limit judgment in the second time period is not met, determining that the converter transformer has a fault, triggering a protection action, quickly identifying the fault and acting an outlet.

Description

Technical Field

[0001] The present invention relates to an ultra-high-speed differential quick-break protection method and device for a converter transformer, belonging to the technical field of converter transformers. Background Art

[0002] Converter transformers are the core equipment of DC transmission converter stations. As UHV converter stations connect to ever-higher AC grid voltages, the stresses on DC converter transformers from both AC and DC currents continue to increase. In recent years, numerous explosions have occurred due to internal faults within the converter transformers. Severe internal damage to the converter transformer can quickly generate high-energy arcs, accumulating energy and potentially causing explosions.

[0003] Transformer differential protection is the primary protection for transformers, primarily used to protect against various phase-to-phase short-circuit faults occurring within the windings and on the lead-out lines of dual- or triple-winding transformers. It can also be used to protect against single-phase turn-to-turn short-circuit faults. Traditional differential protection often uses a full-cycle Fourier transform algorithm or a half-cycle Fourier transform algorithm to calculate the effective value. However, because both algorithms capture sampled data using a sliding time window, a time window of at least 10ms is required to trigger the protection action for the instantaneous, rapid increase in fault current caused by severe faults within the converter transformer, resulting in slow fault clearance. Summary of the Invention

[0004] The object of the present invention is to provide an ultra-high-speed differential quick-trip protection method and device for a converter transformer, so as to solve the problem of slow and untimely fault handling of the converter transformer.

[0005] To achieve the above objectives, the present invention provides, on the one hand, an ultra-high-speed differential fast-trip protection method for a converter transformer, comprising:

[0006] If the adjacent sampling points of the converter transformer all meet the following conditions: the instantaneous value change of the current differential current reaches a preset first current threshold for determining whether a sudden current change occurs in the circuit, then the first stretching time is started;

[0007] A first time period sampling judgment is performed based on the instantaneous value change of the differential current and the preset differential quick-break current value; a second time period comprehensive voltage over-limit judgment is performed based on the absolute value change of the instantaneous voltage value and the preset first voltage threshold for judging whether the converter transformer is charging;

[0008] In the first extension time, in response to the criterion of the first time period sampling judgment being met and the criterion of the second time period comprehensive voltage over-limit judgment being not met, it is determined that a fault occurs in the converter transformer and a protection action is triggered.

[0009] Furthermore, according to the instantaneous value change of the differential current and the preset differential quick-break current value, the first time period sampling judgment is performed through the following steps:

[0010] Determine all sampling points and their instantaneous value changes of differential current within a first time period;

[0011] A comparison is performed between the corresponding instantaneous value change of the current differential current and the differential quick-break current value at all sampling points in the first time period.

[0012] Furthermore, the criterion for the sampling point judgment is that more than half of all the sampling points in the first time period satisfy the following condition: the instantaneous value change of the current differential current is greater than a preset differential quick-break current value.

[0013] Furthermore, based on the absolute value change of the instantaneous voltage value and a preset first voltage threshold for determining whether the converter transformer is being charged, the following steps are performed to determine whether the comprehensive voltage in the second time period exceeds the limit:

[0014] Determine the absolute value changes of all sampling points and their instantaneous voltage values within the second time period;

[0015] A comparison is performed between the absolute value change of the current instantaneous voltage value corresponding to all sampling points in the second time period and the first voltage threshold.

[0016] Furthermore, the criterion for judging whether the comprehensive voltage exceeds the limit is that three or more consecutive sampling points among all the sampling points in the second time period meet the following conditions: the absolute values of the current instantaneous voltage values are all greater than the first voltage threshold.

[0017] Furthermore, the value range of the first current threshold is 0.1I e -0.2I e , where I e is the rated current of the converter transformer.

[0018] Furthermore, the value range of the first voltage threshold is 0.1U e -0.2U e , where U e is the rated voltage of the converter transformer.

[0019] On the other hand, the present invention also proposes an ultra-high-speed differential quick-trip protection device for a converter transformer, comprising a processor, wherein the processor is used for the above-mentioned ultra-high-speed differential quick-trip protection method for a converter transformer.

[0020] The beneficial effects of the present invention are as follows: if adjacent sampling points of the converter transformer all meet the following conditions: the instantaneous value change of the current differential current reaches a preset first current threshold for judging whether a sudden current is generated in the circuit, the first expansion time is started; a first time period sampling judgment is performed based on the instantaneous value change of the differential current and a preset differential quick-break current value; a second time period comprehensive voltage over-limit judgment is performed based on the absolute value change of the instantaneous voltage value and a preset first voltage threshold for judging whether the converter transformer is charging; within the first expansion time, in response to the criterion of the first time period sampling judgment being met and the criterion of the second time period comprehensive voltage over-limit judgment being not met, it is determined that a fault has occurred in the converter transformer and a protection action is triggered, thereby realizing the use of instantaneous values as the judgment basis for different criteria, avoiding the influence of the slow increase of calculation results caused by the full-cycle Fourier algorithm or the half-cycle Fourier algorithm, achieving ultra-high-speed differential quick-break protection, more rapid fault identification and action output, and ensuring the safe and stable operation of the converter transformer equipment and the direct current transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of an ultra-high-speed differential quick-trip protection method for a converter transformer proposed by the present invention;

[0022] Figure 2 This is a logical diagram of an ultra-high-speed differential quick-trip protection method for converter transformers proposed by the present invention in an actual application scenario;

[0023] Figure 3 This is a waveform diagram of the protection action triggered by the ultra-high-speed differential fast-trip protection method for converter transformers proposed by the present invention when a serious internal fault of the converter transformer occurs in an actual application scenario;

[0024] Figure 4 This is a waveform diagram of the voltage and current of the converter transformer when an excitation inrush current is generated in the system in an actual application scenario of an ultra-high-speed differential quick-trip protection method for a converter transformer proposed by the present invention. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0026] The inventive concept of the present invention is that, in order to quickly respond and trigger a protection action when a converter transformer fails, parameters such as the instantaneous value of the differential current and the instantaneous value of the voltage of the converter transformer are used to simultaneously perform a judgment on whether a first current threshold value has been reached, a sampling judgment in a first time period, and a comprehensive voltage over-limit judgment in a second time period, thereby improving the response speed of converter transformer faults in the system and avoiding the impact of the slow increase in calculation results caused by the full-cycle Fourier algorithm or the half-cycle Fourier algorithm.

[0027] Method Specific Implementation 1:

[0028] like Figure 1 FIG. 1 is a flow chart of an ultra-high-speed differential quick-trip protection method for a converter transformer proposed by the present invention, wherein the method includes step S11, step S12 and step S13. Specifically:

[0029] Collect the three-phase current on the grid side, the three-phase current on the valve side, and the three-phase voltage on the grid side of the converter transformer; calculate the instantaneous value change of the differential current by phase based on the three-phase current on the grid side and the three-phase current on the valve side; calculate the absolute value change of the voltage by phase based on the three-phase voltage on the grid side.

[0030] According to the instantaneous value change of the differential current obtained by phase calculation, step S11 is judged for each of the three phases. Specifically, in step S11, if the adjacent sampling points of the converter transformer all meet the following conditions: the instantaneous value change of the current differential current reaches the preset first current threshold for judging whether a sudden current is generated in the circuit, the first widening time is started; it should be noted that if any phase of the three phases meets the judgment content of step S11 (the judgment content is: the adjacent sampling points of the converter transformer all meet the following conditions: the instantaneous value change of the current differential current reaches the preset first current threshold for judging whether a sudden current is generated in the circuit), the first widening time can be started. The value range of the first current threshold is 0.1I e -0.2I e , preferably 0.1414I in the embodiment of the present invention e , where I e is the rated current of the converter transformer. Of course, the first current threshold will be selected according to different transformer states and different circuit conditions, but it is necessary to ensure that by comparing the change in the instantaneous value of the differential current with the first current threshold, the first expansion time can be quickly started when a sudden change occurs in the circuit, so as to monitor whether there is a sudden current in the circuit.

[0031] While step S11 is being executed, step S12 is also performed. Specifically, in step S12, a first time period sampling judgment is performed based on the instantaneous value change of the differential current and the preset differential quick-break current value. Here, the first time period sampling judgment refers to extracting all sampling points within the first time period, and comparing the instantaneous value change of the differential current with the preset differential quick-break current value for each sampling point. The preset differential quick-break current value is a point flow threshold used for quickly judging faults in differential protection, and the differential quick-break current value is greater than the first current threshold.

[0032] When the converter transformer is charging or the AC system fault is restored and an excitation inrush current is generated, the AC voltage will start to change before the AC current, and the instantaneous value of the AC voltage will rise rapidly. In order to avoid the current malfunction caused by the charging of the circulating transformer or the recovery of the AC system fault, step S12 also performs a comprehensive voltage over-limit judgment in the second time period based on the absolute value change of the instantaneous voltage value and the preset first voltage threshold for judging whether the converter transformer is charging; the value range of the first voltage threshold is 0.1U e -0.2U e In the embodiment of the present invention, the first voltage threshold is preferably 0.1U e , where U e is the rated voltage of the converter transformer.

[0033] Here, the instantaneous value change of the differential current used for judgment in step S11 and step S12 is derived from the instantaneous value change of the differential current in the same phase among the three phases, but the change in the absolute value of the instantaneous value of the voltage used for judgment in step S12 can be derived from the same phase among the three phases or from the different phases among the three phases.

[0034] In step S13, in response to the fact that the criterion for the first time period sampling judgment is satisfied and the criterion for the second time period comprehensive voltage over-limit judgment is not satisfied within the first extension time, it is determined that a fault has occurred in the converter transformer and a protection action is triggered. It should be noted that if, within the first extension time, the criterion for the first time period sampling judgment is not satisfied and the criterion for the second time period comprehensive voltage over-limit judgment is not satisfied, the judgment of step S11 will be restored at the end of the first extension time, that is, the judgment of steps S11 and S12 will be repeated.

[0035] Through steps S11 to S13, the circuit where the converter transformer is located is judged by the sudden change quantity startup, the first time period sampling judgment, and the second time period comprehensive voltage over-limit judgment, so as to realize the ultra-high-speed differential quick-break protection of the converter transformer, quickly cut off the fault, and ensure the safe and stable operation of the converter transformer equipment and the DC system.

[0036] In a preferred embodiment of the present invention, sampling and calculation are preferably performed at 32 points per cycle during acquisition, and calculation is performed every 0.625ms; the three-phase current on the grid side of the converter transformer, the three-phase current on the valve side, and the three-phase voltage on the grid side are collected, and the instantaneous value change of the differential current is calculated based on the grid side current and the valve side current phase; the absolute value change of the instantaneous value of the three-phase voltage is calculated based on the grid side voltage phase. Preferably, the instantaneous value change of the differential current at sampling point a0 and sampling point a1 both reaches 0.1414I e, and sampling points a0 and a1 are adjacent sampling points, indicating that a sudden current has occurred in the current circuit, initiating a 20ms stretch (i.e., the first stretch time). Simultaneously, within the first time period of 3.125ms, sampling points a0, a1, a2, a3, and a4 are present. Comparisons are made between sampling points a0-a4 regarding the corresponding instantaneous change in differential current and the differential quick-break current value. Within the second time period of 1.875ms, sampling points b0, b1, and b2 are present. Comparisons are made between sampling points b0-b2 regarding the corresponding instantaneous absolute change in voltage and the first voltage threshold. Sampling points a0-a4 are derived from the current value of phase A; sampling points b0-b2 are derived from the voltage value of phase B.

[0037] If, within the 20ms width, the criterion requirements for the single-point judgment are met within the first time period of 3.125ms, and the criterion requirements for the comprehensive voltage over-limit judgment are not met within the second time period of 1.875ms, it indicates that a serious fault has occurred in the converter transformer and the protection action is triggered; if, within the 20ms width, the following are not obtained: the criterion for the single-point judgment is met and the criterion for the comprehensive voltage over-limit judgment is not met, then after the 20ms width ends, the calculation and judgment of the instantaneous value change of the differential current and the absolute value change of the instantaneous value of the voltage at the sampling point are re-performed.

[0038] Method Specific Implementation Method 2:

[0039] Following the above embodiment of the present invention, in step S12, based on the instantaneous value change of the differential current and the preset differential quick-break current value, the following steps are performed to perform a first time period sampling judgment:

[0040] Determine all sampling points and their instantaneous value changes of the current differential current within the first time period; here, the instantaneous value change of the current differential current at each sampling point is the difference between the instantaneous value of the current differential current and the instantaneous value of the differential current one cycle ago, wherein the instantaneous value of the differential current is calculated by the vector sum of the currents on the valve side and the grid side.

[0041] A comparison is performed between the instantaneous value change of the current differential current and the differential quick-break current value at all sampling points within the first time period. Here, the criterion for the sampling point determination is that more than half of all sampling points within the first time period satisfy the following condition: the instantaneous value change of the current differential current is greater than the preset differential quick-break current value, that is, more than half of all sampling points satisfy the following formula:

[0042] I op -I op.-T >I set ;

[0043] Among them, I opis the instantaneous value of the current differential current; I op.-T is the instantaneous value of the differential current one cycle ago; I set It is the differential speed determination value.

[0044] For example, within the first time period of 3.125ms, there are sampling points a0, a1, a2, a3, and a4, and the instantaneous value change of the current differential current and I set If there are 3 or more sampling points among the 5 sampling points (sampling point a0-sampling point a4) that satisfy the current instantaneous value change of differential current greater than I set , it means that the criterion requirement of the sampling point judgment is met within the first time period of 3.125ms. This criterion is used to determine whether a serious fault occurs in the transformer.

[0045] Method Specific Implementation 3:

[0046] Following the above embodiment of the present invention, in step S12, based on the absolute value change of the instantaneous voltage value and the preset first voltage threshold for determining whether the converter transformer is charging, the following steps are performed to determine whether the comprehensive voltage in the second time period exceeds the limit:

[0047] Determine the absolute value changes of all sampling points and their instantaneous voltage values within the second time period; here, the absolute value change of the instantaneous voltage value of each sampling point is the difference between the current instantaneous voltage value and the instantaneous voltage value of one cycle before.

[0048] For all sampling points in the second time period, a comparison is performed between the absolute value change of the current instantaneous voltage value and the first voltage threshold value. Here, the criterion for judging whether the comprehensive voltage exceeds the limit is that three or more consecutive sampling points among all sampling points in the second time period meet the following conditions: the absolute value of the current instantaneous voltage value is greater than the first voltage threshold value, that is, three or more consecutive sampling points among all sampling points meet the following formula:

[0049] |U|-|U -T |>0.1U e ;

[0050] Among them, U is the instantaneous value of the current voltage; U -T is the instantaneous value of voltage before one cycle; U e is the rated voltage.

[0051] For example, within the second time period of 1.875ms, there are sampling points b0, b1, and b2, and the sampling points b0, b1, and b2 are continuous sampling points; the absolute value change of the instantaneous voltage value of each sampling point (sampling point b0-sampling point b2) and the absolute value change of 0.1U e(first voltage threshold) If the absolute value change of the instantaneous voltage value of sampling point b0-sampling point b2 is greater than 0.1U e , it means that the criterion requirement of comprehensive voltage over-limit judgment is met within the second time period of 1.875ms. If any one / two / three of the absolute value changes of the instantaneous voltage values of sampling point b0-sampling point b2 are not greater than 0.1U e , it means that the criterion requirement for comprehensive voltage over-limit judgment is not met within the second time period of 1.875ms.

[0052] Method Specific Implementation Method 4:

[0053] When a serious fault occurs inside a converter transformer, the instantaneous value of the fault current can reach a fixed value within 2 to 3 ms. Conventional differential quick-trip protection schemes are limited by the Fourier window calculation algorithm for effective values, requiring a time window of at least 10 ms, or half a cycle, for protection to operate. This results in relatively slow fault removal, increasing the risk of converter transformer damage or explosion. To address the above issues, the present invention proposes an ultra-high-speed differential quick-trip protection method for converter transformers. By collecting the three-phase current on the grid side, the three-phase current on the valve side, and the three-phase voltage on the grid side of the converter transformer, the method completes the judgment of the sudden change triggering criterion, the dynamic small window sampling criterion (i.e., the sampling criterion), and the comprehensive voltage over-limit criterion. Combining these criteria, the method achieves rapid output of the ultra-high-speed differential quick-trip protection for the converter transformer within 4 to 6 ms.

[0054] Specific: such as Figure 2 The figure shows a logic diagram of the proposed ultra-high-speed differential quick-trip protection method for converter transformers in practical application scenarios. A device with a 1.6K sampling rate is used to collect the three-phase current on the grid side, the three-phase current on the valve side, and the three-phase voltage on the grid side of the converter transformer. The instantaneous change in the differential current between the grid-side current and the valve-side current is calculated on a phase-by-phase basis, and the absolute change in the instantaneous value of the three-phase voltage is calculated on a phase-by-phase basis. The 1.6K sampling rate device performs sampling and calculations at 32 points per cycle, performing one calculation every 0.625ms. The change is calculated by subtracting the current data collected with the data collected one cycle ago.

[0055] 2) Calculate the instantaneous change in differential current at each sampling point by phase. When the instantaneous change in differential current in a phase is greater than 0.1414 times the rated current (i.e., the first current threshold) and meets the conditions for two consecutive execution cycles (i.e., two consecutive sampling points collected at 0.625ms), it is considered that the mutation trigger criterion meets the conditions, and the start widening is 20ms (the first widening time) to monitor whether there is current in the circuit. The instantaneous change in differential current greater than 0.1414 times the rated current can be expressed by the following formula:

[0056] I op -Iop.-T >0.1414I e ;

[0057] Among them, I op is the instantaneous value of the current differential current; I op.-T is the instantaneous value of the differential current one cycle ago; I e is the rated current of the converter transformer.

[0058] 3) Calculate the instantaneous value change of the differential current at each sampling point in phase, preferably continuously opening a dynamic small window (i.e., a time period that can collect 5 sampling points) of 5 execution cycles (i.e., five consecutive sampling points collected at 0.625ms). If there are 4 execution cycles within the dynamic small window range that meet the instantaneous value change of the differential current greater than the differential speed determination value, it is considered that the sampling criterion of the dynamic small window is met. The instantaneous value change of the differential current greater than the differential speed determination value can be expressed by the following formula:

[0059] I op -I op.-T >I set ;

[0060] Among them, I op is the instantaneous value of the current differential current; I op.-T is the instantaneous value of the differential current one cycle ago; I set It is the differential speed determination value.

[0061] 4) Calculate the absolute value change of the instantaneous three-phase voltage at each sampling point. When the absolute value change of any phase voltage is greater than 0.1 times the rated voltage (i.e., the first voltage threshold) for three consecutive execution cycles, it is considered that the comprehensive voltage over-limit criterion is met. At this time, it indicates that there is an excitation inrush current in the circuit. To allow the excitation inrush current to decay, the second expansion time of 30 seconds is started after the comprehensive voltage over-limit criterion is met. The following formula represents the absolute value change of the voltage greater than the first voltage threshold:

[0062] |U|-|U -T |>0.1U e ;

[0063] Among them, U is the instantaneous value of the current voltage; U -T is the instantaneous value of voltage before one cycle; U e is the rated voltage.

[0064] 5) If 2) and 3) are satisfied and 4) is not satisfied (wherein, the instantaneous current value of the sampling point where 2) and 3) are satisfied is derived from the instantaneous current value of the same phase, and the instantaneous voltage value of the sampling point where 4) is not satisfied may be derived from the same phase or from the opposite phase as the instantaneous current value of the sampling point where 2) and 3) are satisfied; and the judgment result that 3) is satisfied and 4) is not satisfied must be obtained within the first extension time), then it is determined that a serious fault has occurred inside the converter transformer, and the ultra-high-speed differential quick-trip protection is immediately activated.

[0065] At the same time, the above steps 2), 3) and 4) are steps for simultaneous judgment, that is, the sudden change start criterion, the dynamic small window sampling criterion and the comprehensive voltage over-limit criterion are judged at the same time without any order of judgment.

[0066] As can be seen, the present invention collects the grid-side three-phase current, valve-side three-phase current, and grid-side three-phase voltage of the converter transformer to implement the sudden change trigger criterion, dynamic small window sampling criterion, and comprehensive voltage over-limit criterion. Combining these criteria, ultra-high-speed differential quick-trip protection for the converter transformer is achieved. Its main features are as follows: 1. When a serious fault occurs within the converter transformer, the instantaneous value of the differential current rises rapidly. The change in the instantaneous value of the differential current is used to implement the sudden change trigger criterion and dynamic small window sampling criterion. 2. When a serious fault occurs within the converter transformer, the instantaneous value of the AC voltage drops rapidly. The change in the absolute value of the instantaneous value of the AC three-phase voltage is used to implement the comprehensive voltage over-limit criterion.

[0067] Device specific implementation 1:

[0068] Another aspect of the present invention further provides an ultra-high-speed differential quick-trip protection device for a converter transformer, the device comprising a processor configured to execute the above-mentioned ultra-high-speed differential quick-trip protection method for a converter transformer.

[0069] like Figure 3 As shown, a waveform diagram of the ultra-high-speed differential quick-trip protection method for converter transformers proposed in the present invention triggering protection action when a serious fault occurs inside the converter transformer in an actual application scenario, wherein "TDP_D_FASTTRIP" is the ultra-high-speed differential quick-trip action signal, and "TDP_D_TRIP2" is the traditional differential quick-trip action signal. When a serious fault occurs inside the converter transformer, the instantaneous value of the fault current rises rapidly. The sudden change trigger criterion and the dynamic small window sampling criterion identify the fault within 5ms. The ultra-high-speed differential quick-trip protection acts quickly, shortening the action time by about 50% compared with the traditional differential quick-trip.

[0070] like Figure 4As shown, a waveform diagram of the voltage and current of the converter transformer when an excitation inrush current is generated in the system in an actual application scenario of an ultra-high-speed differential quick-trip protection method for a converter transformer proposed by the present invention is shown, wherein "TDP_D_FASTTRIP" is the ultra-high-speed differential quick-trip action signal, and "TDP_D_TRIP2" is the traditional differential quick-trip action signal. The charging of the converter transformer generates an excitation inrush current greater than the differential quick-trip set value, the AC voltage changes before the AC current, and the instantaneous value of the AC voltage rises rapidly. The comprehensive voltage over-limit criterion can lock the ultra-high-speed differential quick-trip protection to prevent false tripping. The traditional differential quick-trip protection has no anti-locking measures after reaching the set value, which may cause false tripping.

[0071] After RTDS verification and dynamic model verification, the beneficial effects of the present invention are: it can identify serious faults inside the converter transformer more quickly than traditional converter transformer differential quick-break protection, quickly eliminate the faults, and ensure the safe and stable operation of the converter transformer equipment and DC system. For serious faults inside the converter transformer, it can achieve a fast exit of 4 to 6ms, which is about 50% shorter than the action time of traditional differential quick-break protection.

[0072] In summary, the present invention uses a dynamic small window algorithm for instantaneous values to collect the three-phase current on the grid side, the three-phase current on the valve side, and the three-phase voltage on the grid side of the converter transformer. The instantaneous value change of the differential current between the grid-side current and the valve-side current is calculated on a phase-by-phase basis to complete the judgment of the sudden change triggering criterion and the dynamic small window sampling criterion. The absolute value change of the instantaneous value of the three-phase voltage is calculated on a phase-by-phase basis to complete the judgment of the comprehensive voltage over-limit criterion. The above judgment results are combined to determine whether the protection is activated. This avoids the impact of the slow increase in calculation results caused by the Fourier full-cycle effective value or half-cycle effective value algorithm, and more quickly identifies faults and activates the output.

Claims

1. A converter transformer ultra-high-speed differential quick-break protection method, characterized in that: include: If the adjacent sampling points of the converter transformer all meet the following conditions: the instantaneous value change of the current differential current reaches a preset first current threshold for determining whether a sudden current change occurs in the circuit, then the first stretching time is started; A first time period sampling judgment is performed based on the instantaneous value change of the differential current and the preset differential quick-break current value; a second time period comprehensive voltage over-limit judgment is performed based on the absolute value change of the instantaneous voltage value and the preset first voltage threshold for judging whether the converter transformer is charging; In the first extension time, in response to the criterion of the first time period sampling judgment being met and the criterion of the second time period comprehensive voltage over-limit judgment being not met, it is determined that a fault occurs in the converter transformer and a protection action is triggered.

2. The ultra-high-speed differential quick-break protection method for converter transformers according to claim 1, characterized in that: According to the instantaneous value change of the differential current and the preset differential quick-break current value, the following steps are used to perform the first time period sampling judgment: Determine all sampling points and their instantaneous value changes of differential current within a first time period; A comparison is performed between the corresponding instantaneous value change of the current differential current and the differential quick-break current value at all sampling points in the first time period.

3. The ultra-high-speed differential quick-break protection method for converter transformers according to claim 2, characterized in that: The criterion for the sampling point judgment is that more than half of all the sampling points in the first time period meet the following conditions: the instantaneous value change of the current differential current is greater than the preset differential quick-break current value.

4. The ultra-high-speed differential quick-break protection method for converter transformers according to claim 1, characterized in that: Based on the absolute value change of the instantaneous voltage value and the preset first voltage threshold for determining whether the converter transformer is charging, the following steps are performed to determine whether the comprehensive voltage in the second time period exceeds the limit: Determine the absolute value changes of all sampling points and their instantaneous voltage values within the second time period; A comparison is performed between the absolute value change of the current instantaneous voltage value corresponding to all sampling points in the second time period and the first voltage threshold.

5. The ultra-high-speed differential quick-break protection method for converter transformers according to claim 4, characterized in that: The criterion for judging the comprehensive voltage over-limit is that three or more consecutive sampling points among all the sampling points in the second time period meet the following conditions: the absolute values of the current instantaneous voltage values are all greater than the first voltage threshold.

6. The ultra-high-speed differential quick-break protection method for converter transformer according to any one of claims 1 to 5, characterized in that: The value range of the first current threshold is 0.1I e -0.2I e , where I e is the rated current of the converter transformer.

7. The ultra-high-speed differential quick-break protection method for converter transformer according to any one of claims 1 to 5, characterized in that: The value range of the first voltage threshold is 0.1U e -0.2 U e , where U e is the rated voltage of the converter transformer.

8. An ultra-high-speed differential quick-break protection device for a converter transformer, characterized in that: The invention comprises a processor, wherein the processor is used to execute the ultra-high-speed differential fast-trip protection method for a converter transformer according to any one of claims 1 to 7.

Images