Converter station multi-harmonic source quantitative traceability method

Abstract

The invention relates to converter station harmonic traceability, in particular to a converter station multi-harmonic source quantitative traceability method, which comprises the following steps of: monitoring the operation state of a passive filter bank, and respectively and synchronously acquiring a group of power supply bus harmonic voltage phasors, each power transmission line harmonic current phasor and a passive filter bank harmonic current phasor before and after the state switching of the passive filter bank; calculating an equivalent harmonic source parameter of each power transmission line according to the harmonic voltage phasors of the power supply bus, the harmonic current phasors of each power transmission line and the harmonic current phasors of the passive filter bank before and after the state switching of the passive filter bank; calculating a power supply bus harmonic voltage calculation value according to the equivalent harmonic source parameter of each power transmission line, performing error calculation on the power supply bus harmonic voltage calculation value and a power supply bus harmonic voltage measurement value at a corresponding moment, and performing data filtering on the equivalent harmonic source parameter of each power transmission line according to an error calculation result; the technical scheme provided by the invention can effectively overcome the defect that accurate quantitative traceability is difficult to carry out on the converter station multi-harmonic source.

Description

Technical Field

[0001] The invention relates to harmonic tracing of a converter station, and in particular to a quantitative tracing method for multiple harmonic sources of a converter station. Background Art

[0002] With the large-scale grid connection of new power equipment, power transmission and transformation equipment, and high-voltage nonlinear loads such as renewable energy power generation, high-voltage DC converter stations, electrified railways, and urban rail transit, the types and number of harmonic sources in the power grid have increased significantly, and the problem of excessive harmonics has gradually penetrated from the distribution network to the transmission network, posing a serious threat to the safe and stable operation of the converter station. Therefore, for the transmission network, especially the converter station, it is of great significance to carry out harmonic quantitative tracing of the converter station for harmonic management and to ensure the safe and stable operation of the converter station. The converter station harmonic tracing belongs to a typical centralized multi-harmonic source scenario. The core problem of its harmonic quantitative tracing is to construct an accurate Norton equivalent model of the converter station, that is, to obtain the harmonic impedance and harmonic current source of each transmission line.

[0003] At present, in terms of harmonic impedance calculation, the research directions at home and abroad are mainly to use the fluctuation method and regression method for solution. Among them, the fluctuation method uses the sign of the ratio of the harmonic voltage fluctuation to the harmonic current fluctuation at the PCC to estimate the harmonic impedance on the system side. Its core idea is to believe that the bus harmonic voltage fluctuation at the PCC is completely caused by the harmonic current fluctuation on the user side. The essence of the regression method is to use the linear correlation between the bus harmonic voltage and the current amplitude of each harmonic source to quantify the contribution rate of each harmonic source line based on the regression coefficient.

[0004] In terms of harmonic current source calculation, there is relatively little research on the value of harmonic current sources by scholars at home and abroad. The existing methods mainly use the measured harmonic current at the line connection point instead of the harmonic current theoretically generated by the line harmonic source for quantitative tracing.

[0005] The calculation method of the above harmonic impedance and harmonic current source needs to meet an assumed premise in practical application, that is, the harmonic impedance on the user side is much larger than the harmonic impedance on the system side, so as to use the current measurement value of the grid connection point of the harmonic source equivalent circuit to replace the actual emission current of the harmonic source for quantitative tracing. However, the transmission network where the converter station is located does not meet the assumed premise that the harmonic impedance on the user side is much larger than the harmonic impedance on the system side, which leads to the aggravated coupling degree of the harmonic current between the transmission lines, resulting in a large difference between the harmonic current measurement value of the grid connection point of each transmission line in the converter station and the actual emission current of its harmonic source, affecting the accuracy of quantitative tracing of multiple harmonic sources in the converter station. Therefore, how to realize accurate quantitative tracing of multiple harmonic sources of each transmission line of the converter station based on the bus harmonic voltage and the harmonic current of each transmission line grid connection point is a key technical problem that needs to be solved urgently. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for quantitatively tracing the multi-harmonic sources of a converter station, which can effectively overcome the defect of the prior art that it is difficult to accurately and quantitatively trace the multi-harmonic sources of a converter station.

[0008] (II) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] A method for quantitatively tracing multiple harmonic sources in a converter station comprises the following steps:

[0011] S1, monitor the operating status of the passive filter group, and synchronously collect a group of power supply bus harmonic voltage phasors, each transmission line harmonic current phasors and passive filter group harmonic current phasors before and after the passive filter group state is switched;

[0012] S2. Calculate the equivalent harmonic source parameters of each transmission line according to the power supply bus harmonic voltage phasor before and after the passive filter group state switching, the harmonic current phasor of each transmission line and the harmonic current phasor of the passive filter group;

[0013] S3. Calculate the power supply bus harmonic voltage calculation value according to the equivalent harmonic source parameters of each transmission line, and perform error calculation with the power supply bus harmonic voltage measurement value at the corresponding time, and perform data filtering on the equivalent harmonic source parameters of each transmission line according to the error calculation result;

[0014] S4, repeat S1 to S3 until the equivalent harmonic source parameters of N groups of transmission lines corresponding to the N-times passive filter group state switching within the monitoring period are obtained;

[0015] S5. Calculate the contribution rate of each transmission line to the harmonic voltage of the power supply bus during a single passive filter group state switching process, and calculate the average contribution rate of each transmission line to the harmonic voltage of the power supply bus during N passive filter group state switching processes within the monitoring period.

[0016] Preferably, the operating state of the passive filter group is monitored in S1, and a group of power supply bus harmonic voltage phasors, harmonic current phasors of each transmission line and harmonic current phasors of the passive filter group are synchronously collected before and after the passive filter group state is switched, including:

[0017] When the passive filter group is monitored to have its kth state switching, synchronous sampling is performed to obtain the power supply bus harmonic voltage phasors before and after the passive filter group state switching. Harmonic current phasors of each transmission line before and after the passive filter bank state switching And the harmonic current phasors of the passive filter group before and after the passive filter group state switching

[0018] Wherein, h is the harmonic order, b is the mark before the passive filter group state is switched, a is the mark after the passive filter group state is switched, m is the transmission line number, m∈{1,2,...,M}, M is the number of transmission lines, and the measurement direction of the current transformer is based on the outgoing power supply bus as the reference direction.

[0019] Preferably, when synchronously collecting a group of power supply bus harmonic voltage phasors, each transmission line harmonic current phasor and passive filter group harmonic current phasor:

[0020] In order to avoid the influence of excitation inrush current during the state switching of the passive filter group, that is, to ensure that the changes of harmonic voltage phasors and harmonic current phasors are completely caused by the impedance changes of the passive filter group, synchronous sampling is started at the zero crossing point of the fundamental voltage of phase A 1 second before the state switching of the passive filter group to obtain the power supply bus harmonic voltage phasor before the state switching of the passive filter group. Harmonic current phasors of each transmission line and passive filter bank harmonic current phasors

[0021] Synchronous sampling starts at the zero-crossing point of the fundamental voltage of phase A 2 seconds after the passive filter group state is switched to obtain the power supply bus harmonic voltage phasor after the passive filter group state is switched. Harmonic current phasors of each transmission line and passive filter bank harmonic current phasors

[0022] Among them, the value range of T1 and T2 is 300ms~500ms.

[0023] Preferably, in S2, according to the power supply bus harmonic voltage phasor before and after the passive filter group state switching, the harmonic current phasor of each transmission line and the harmonic current phasor of the passive filter group, the equivalent harmonic source parameters of each transmission line are calculated, including:

[0024] S21, calculating the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group according to the power supply bus harmonic voltage phasor and the passive filter group harmonic current phasor before and after the passive filter group state is switched;

[0025] S22, according to the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group, respectively calculating the harmonic impedance parallel value between the passive filter group and the system before and after the passive filter group state is switched;

[0026] S23, according to the harmonic current phasors of each transmission line before and after the passive filter group state switching, combined with the parallel value of the harmonic impedance calculated in S22, calculate the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line.

[0027] Preferably, in S21, according to the power supply bus harmonic voltage phasors and the passive filter group harmonic current phasors before and after the passive filter group state switching, the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group are calculated, including:

[0028] S211. Use the following formula to calculate the harmonic impedance value of the passive filter group:

[0029]

[0030] Among them, Z LC,h,k,b is the harmonic impedance value of the passive filter group h before the kth state switching, Z LC,h,k,a is the hth harmonic impedance value of the passive filter group after the kth state switching;

[0031] S212, using the following formula to calculate the system harmonic impedance value corresponding to the passive filter group during the k-th state switching process:

[0032]

[0033] Among them, Z S,h,k is the system hth harmonic impedance value corresponding to the passive filter group during the kth state switching process.

[0034] Preferably, in S22, according to the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group, the harmonic impedance parallel value between the passive filter group and the system before and after the passive filter group state is switched is calculated respectively, including:

[0035] The following formula is used to calculate the parallel value of the harmonic impedance between the passive filter group and the system before and after the state switching:

[0036]

[0037] Among them, Z P,k,b is the harmonic impedance value Z of the passive filter group h before the kth state switching LC,h,k,b And the system h-order harmonic impedance value Z S,h,k The parallel value of the harmonic impedance between P,k,a is the harmonic impedance value Z of the passive filter group after the kth state switching LC,h,k,a And the system h-order harmonic impedance value Z S,h,k The parallel value of the harmonic impedance between them.

[0038] Preferably, in S23, according to the harmonic current phasors of each transmission line before and after the passive filter group state is switched, combined with the harmonic impedance parallel value calculated in S22, the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line are calculated, including:

[0039] S231. When calculating the equivalent harmonic current source phasor and harmonic impedance value of transmission line m, the harmonic current phasors of other transmission lines are added together as the generalized transmission line:

[0040]

[0041] in, is the sum of the hth harmonic current phasors of the transmission lines except the transmission line m before the kth state switching, is the sum of the hth harmonic current phasors of all transmission lines before the kth state switching,

[0042] is the sum of the hth harmonic current phasors of the transmission lines except the transmission line m after the kth state switching, is the sum of the hth harmonic current phasors of all transmission lines after the kth state switching, M is the number of transmission lines;

[0043] S232. Use the following formula to calculate the equivalent harmonic current source phasor and harmonic impedance value of transmission line m, that is, the Norton equivalent parameter of transmission line m:

[0044]

[0045] in, is the equivalent hth harmonic current source phasor of transmission line m during the kth state switching process, Z S,h,m,k is the hth harmonic impedance value equivalent to the transmission line m during the kth state switching process;

[0046] S233, repeat S231 to S232 until the equivalent harmonic current source phasors and harmonic impedance values ​​of all transmission lines in the k-th state switching process, that is, the Norton equivalent parameters of all transmission lines, are calculated.

[0047] Preferably, in S3, according to the equivalent harmonic source parameters of each transmission line, the power supply bus harmonic voltage calculation value is calculated, and the error calculation is performed with the power supply bus harmonic voltage measurement value at the corresponding moment, and the equivalent harmonic source parameters of each transmission line are filtered according to the error calculation result, including:

[0048] Since the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line before and after the passive filter group state switching are the same, the contribution rate of the equivalent harmonic source of each transmission line to the power supply bus harmonic voltage before and after the passive filter group state switching is the same. Here, the calculation is performed based on the state before the passive filter group switching:

[0049] S31. Use the following formula to calculate the power supply bus harmonic voltage value:

[0050]

[0051] in, is the calculated value of the hth harmonic voltage of the power supply bus before the kth state switching;

[0052] S32, use the following formula to calculate the harmonic voltage of the power supply bus The error calculation is performed with the measured value of the power supply bus harmonic voltage at the corresponding time:

[0053]

[0054] Among them, ε k,b is the calculated value of the hth harmonic voltage of the power supply bus before the kth state switching Relative to the sampling obtained before the kth state switching power supply bus harmonic voltage phasor The error rate of

[0055] S33, when |ε k,b |>β, it is considered that the errors of the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line in the kth state switching process are large, and the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line in this state switching process are removed;

[0056] Wherein, β is a preset threshold value, and its value range is 5% to 10%.

[0057] Preferably, in S5, the contribution rate of each transmission line to the harmonic voltage of the power supply bus during a single passive filter group state switching process is calculated, and the average contribution rate of each transmission line to the harmonic voltage of the power supply bus during N passive filter group state switching processes within the monitoring period is calculated, including:

[0058] S51. The contribution rate of the transmission line m to the power supply bus harmonic voltage during the nth state switching process is calculated using the following formula:

[0059]

[0060] Among them, C U,h,m,n is the contribution rate of the equivalent harmonic current source of transmission line m to the hth harmonic voltage of the power supply bus during the nth state switching process, for exist The projection angle on is the hth harmonic current source phasor equivalent to the transmission line m during the nth state switching process, is the sum of the equivalent h-th harmonic current source phasors of all transmission lines during the n-th state switching process, M is the number of transmission lines, n is a subset of k;

[0061] S52. The following formula is used to calculate the average contribution rate of the transmission line m to the power supply bus harmonic voltage during the N-time passive filter group state switching process during the monitoring period:

[0062]

[0063] in, is the average contribution rate of the harmonic current source equivalent to the transmission line m to the hth harmonic voltage of the power supply bus during the nth state switching process, and N is the total number of state switching of the passive filter group that meets the data error requirements during the monitoring period;

[0064] S53, repeat S51 to S52 until the average contribution rate of all transmission lines to the power supply bus harmonic voltage during the N-times passive filter group state switching process within the monitoring period is calculated.

[0065] (III) Beneficial effects

[0066] Compared with the prior art, the method for quantitatively tracing the source of multiple harmonics in a converter station provided by the present invention has the following beneficial effects:

[0067] 1) This method is completely based on the busbar harmonic voltage and the harmonic current of each transmission line connection point to quantitatively trace the source of multiple harmonic sources in the converter station, without the need to build a complex power grid model, which is convenient for engineering application;

[0068] 2) This method calculates the calculated value of the power supply bus harmonic voltage based on the equivalent harmonic source parameters of each transmission line, calculates the error with the measured value of the power supply bus harmonic voltage at the corresponding time, and uses mathematical statistics methods to reduce the random error caused by a single measurement, avoiding the harmonic quantitative tracing divergence caused by the large error of the equivalent harmonic source parameters;

[0069] 3) Based on the statistics of long-term and multiple passive filter group state switching processes, the contribution rate of each transmission line to the power supply bus harmonic voltage is comprehensively evaluated, which can realize the quantitative tracing of harmonics on a long-term scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0071] Figure 1 It is a schematic diagram of the process of the present invention;

[0072] Figure 2 It is a schematic diagram of the sampling point positions before and after the passive filter group state switching in the present invention;

[0073] Figure 3 A comparison diagram of the calculated value of the power supply bus harmonic voltage and the measured value of the power supply bus harmonic voltage at the corresponding moment in an embodiment of the present invention;

[0074] Figure 4 A diagram showing the error calculation result between the calculated value of the power supply bus harmonic voltage and the measured value of the power supply bus harmonic voltage at the corresponding moment in an embodiment of the present invention;

[0075] Figure 5 It is a schematic diagram of the contribution rate of each transmission line to the power supply bus harmonic voltage during the N-th passive filter group state switching process within the monitoring period in an embodiment of the present invention. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0077] A quantitative tracing method for multiple harmonic sources in converter stations, such as Figure 1 As shown, S1, monitor the operating status of the passive filter group, and synchronously collect a group of power supply bus harmonic voltage phasors, each transmission line harmonic current phasors and passive filter group harmonic current phasors before and after the passive filter group state is switched;

[0078] S2. Calculate the equivalent harmonic source parameters of each transmission line according to the power supply bus harmonic voltage phasor before and after the passive filter group state switching, the harmonic current phasor of each transmission line and the harmonic current phasor of the passive filter group;

[0079] S3. Calculate the power supply bus harmonic voltage calculation value according to the equivalent harmonic source parameters of each transmission line, and perform error calculation with the power supply bus harmonic voltage measurement value at the corresponding time, and perform data filtering on the equivalent harmonic source parameters of each transmission line according to the error calculation result;

[0080] S4, repeat S1 to S3 until the equivalent harmonic source parameters of N groups of transmission lines corresponding to the N-times passive filter group state switching within the monitoring period are obtained;

[0081] S5. Calculate the contribution rate of each transmission line to the harmonic voltage of the power supply bus during a single passive filter group state switching process, and calculate the average contribution rate of each transmission line to the harmonic voltage of the power supply bus during N passive filter group state switching processes within the monitoring period.

[0082] In S1, the operating status of the passive filter group is monitored. Before and after the passive filter group state is switched, a group of power supply bus harmonic voltage phasors, harmonic current phasors of each transmission line and harmonic current phasors of the passive filter group are synchronously collected, such as Figure 2 As shown, including:

[0083] When the passive filter group is monitored to have its kth state switching, synchronous sampling is performed to obtain the power supply bus harmonic voltage phasors before and after the passive filter group state switching. Harmonic current phasors of each transmission line before and after the passive filter bank state switching And the harmonic current phasors of the passive filter group before and after the passive filter group state switching

[0084] Wherein, h is the harmonic order, b is the mark before the passive filter group state is switched, a is the mark after the passive filter group state is switched, m is the transmission line number, m∈{1,2,...,M}, M is the number of transmission lines, and the measurement direction of the current transformer is based on the outgoing power supply bus as the reference direction.

[0085] In the technical solution of the present application, when synchronously collecting a group of power supply bus harmonic voltage phasors, each transmission line harmonic current phasors and passive filter group harmonic current phasors:

[0086] In order to avoid the influence of excitation inrush current during the state switching of the passive filter group, that is, to ensure that the changes of harmonic voltage phasors and harmonic current phasors are completely caused by the impedance changes of the passive filter group, synchronous sampling is started at the zero crossing point of the fundamental voltage of phase A 1 second before the state switching of the passive filter group to obtain the power supply bus harmonic voltage phasor before the state switching of the passive filter group. Harmonic current phasors of each transmission line and passive filter bank harmonic current phasors

[0087] Synchronous sampling starts at the zero-crossing point of the fundamental voltage of phase A 2 seconds after the passive filter group state is switched to obtain the power supply bus harmonic voltage phasor after the passive filter group state is switched. Harmonic current phasors of each transmission line and passive filter bank harmonic current phasors

[0088] Among them, the value range of T1 and T2 is 300ms~500ms.

[0089] In S2, the equivalent harmonic source parameters of each transmission line are calculated according to the power supply bus harmonic voltage phasors before and after the passive filter group state switching, the harmonic current phasors of each transmission line and the harmonic current phasors of the passive filter group, including:

[0090] S21, calculating the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group according to the power supply bus harmonic voltage phasor and the passive filter group harmonic current phasor before and after the passive filter group state is switched;

[0091] S22, according to the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group, respectively calculating the harmonic impedance parallel value between the passive filter group and the system before and after the passive filter group state is switched;

[0092] S23, according to the harmonic current phasors of each transmission line before and after the passive filter group state switching, combined with the parallel value of the harmonic impedance calculated in S22, calculate the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line.

[0093] 1) In S21, the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group are calculated according to the harmonic voltage phasor of the power supply bus and the harmonic current phasor of the passive filter group before and after the passive filter group state is switched, including:

[0094] S211. Use the following formula to calculate the harmonic impedance value of the passive filter group:

[0095]

[0096] Among them, Z LC,h,k,b is the harmonic impedance value of the passive filter group h before the kth state switching, Z LC,h,k,a is the hth harmonic impedance value of the passive filter group after the kth state switching;

[0097] S212, using the following formula to calculate the system harmonic impedance value corresponding to the passive filter group during the k-th state switching process:

[0098]

[0099] Among them, ZS,h,k is the system hth harmonic impedance value corresponding to the passive filter group during the kth state switching process.

[0100] 2) In S22, according to the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group, the harmonic impedance parallel value between the passive filter group and the system before and after the passive filter group state is switched is calculated, including:

[0101] The following formula is used to calculate the parallel value of the harmonic impedance between the passive filter group and the system before and after the state switching:

[0102]

[0103] Among them, Z P,k,b is the harmonic impedance value Z of the passive filter group h before the kth state switching LC,h,k,b And the system h-order harmonic impedance value Z S,h,k The parallel value of the harmonic impedance between P,k,a is the harmonic impedance value Z of the passive filter group after the kth state switching LC,h,k,a And the system h-order harmonic impedance value Z S,h,k The parallel value of the harmonic impedance between them.

[0104] 3) In S23, based on the harmonic current phasors of each transmission line before and after the passive filter group state is switched, combined with the harmonic impedance parallel value calculated in S22, the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line are calculated, including:

[0105] S231. When calculating the equivalent harmonic current source phasor and harmonic impedance value of transmission line m, the harmonic current phasors of other transmission lines are added together as the generalized transmission line:

[0106]

[0107] in, is the sum of the hth harmonic current phasors of the transmission lines except the transmission line m before the kth state switching, is the sum of the hth harmonic current phasors of all transmission lines before the kth state switching,

[0108] is the sum of the hth harmonic current phasors of the transmission lines except the transmission line m after the kth state switching, is the sum of the hth harmonic current phasors of all transmission lines after the kth state switching, M is the number of transmission lines;

[0109] S232. Use the following formula to calculate the equivalent harmonic current source phasor and harmonic impedance value of transmission line m, that is, the Norton equivalent parameter of transmission line m:

[0110]

[0111]

[0112] in, is the equivalent hth harmonic current source phasor of transmission line m during the kth state switching process, Z S,h,m,k is the hth harmonic impedance value equivalent to the transmission line m during the kth state switching process;

[0113] S233, repeat S231 to S232 until the equivalent harmonic current source phasors and harmonic impedance values ​​of all transmission lines in the k-th state switching process, that is, the Norton equivalent parameters of all transmission lines, are calculated.

[0114] In S3, the harmonic voltage calculation value of the power supply bus is calculated according to the equivalent harmonic source parameters of each transmission line, and the error calculation is performed with the measured value of the harmonic voltage of the power supply bus at the corresponding time, such as Figure 3 and Figure 4 As shown, data filtering is performed on the equivalent harmonic source parameters of each transmission line according to the error calculation results, including:

[0115] Since the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line before and after the passive filter group state switching are the same, the contribution rate of the equivalent harmonic source of each transmission line to the power supply bus harmonic voltage before and after the passive filter group state switching is the same. Here, the calculation is performed based on the state before the passive filter group switching:

[0116] S31. Use the following formula to calculate the power supply bus harmonic voltage value:

[0117]

[0118] in, is the calculated value of the hth harmonic voltage of the power supply bus before the kth state switching;

[0119] S32, use the following formula to calculate the harmonic voltage of the power supply bus The error calculation is performed with the measured value of the power supply bus harmonic voltage at the corresponding time:

[0120]

[0121] Among them, ε k,b is the calculated value of the hth harmonic voltage of the power supply bus before the kth state switching Relative to the sampling obtained before the kth state switching power supply bus harmonic voltage phasor The error rate of

[0122] S33, when |ε k,b |>β, it is considered that the errors of the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line in the kth state switching process are large, and the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line in this state switching process are removed;

[0123] Wherein, β is a preset threshold value, and its value range is 5% to 10%.

[0124] In S5, the contribution rate of each transmission line to the power supply bus harmonic voltage during the single passive filter group state switching process is calculated, such as Figure 5 As shown, the average contribution rate of each transmission line to the power supply bus harmonic voltage during the N-time passive filter group state switching process during the monitoring period is calculated, including:

[0125] S51. The contribution rate of the transmission line m to the power supply bus harmonic voltage during the nth state switching process is calculated using the following formula:

[0126]

[0127] Among them, C U,h,m,n is the contribution rate of the equivalent harmonic current source of transmission line m to the hth harmonic voltage of the power supply bus during the nth state switching process, for exist The projection angle on is the hth harmonic current source phasor equivalent to the transmission line m during the nth state switching process, is the sum of the equivalent h-th harmonic current source phasors of all transmission lines during the n-th state switching process, M is the number of transmission lines, n is a subset of k;

[0128] S52. The following formula is used to calculate the average contribution rate of the transmission line m to the power supply bus harmonic voltage during the N-time passive filter group state switching process during the monitoring period:

[0129]

[0130] in, is the average contribution rate of the harmonic current source equivalent to the transmission line m to the hth harmonic voltage of the power supply bus during the nth state switching process, and N is the total number of state switching of the passive filter group that meets the data error requirements during the monitoring period;

[0131] S53, repeat S51 to S52 until the average contribution rate of all transmission lines to the power supply bus harmonic voltage during the N-times passive filter group state switching process within the monitoring period is calculated.

[0132] In order to better introduce the present technical solution, a specific embodiment is described in detail below:

[0133] A 500kV substation has 10 500kV transmission lines and 1 passive filter bank branch. Figure 2 As shown. A total of 38 switching processes of the passive filter group were monitored within 168 hours. A group of power supply bus harmonic voltage phasors, harmonic current phasors of each transmission line and harmonic current phasors of the passive filter group were obtained by synchronous sampling 500ms before and 500ms after each switching. The equivalent harmonic current source phasors and harmonic impedance values ​​of the 10 transmission lines were calculated during each switching process, and then the power supply bus harmonic voltage calculation value of each switching process was calculated. The error was calculated by comparing it with the power supply bus harmonic voltage measurement value at the corresponding moment, as shown in Figure 3 and Figure 4 As shown in FIG. 1 , the preset threshold β is set to 10%, and the calculated equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line during the 38 switching processes meet the error requirements. The contribution rate distribution of the equivalent harmonic current source of each transmission line to the harmonic voltage of the power supply bus during the 38 switching processes is calculated, as shown in FIG. Figure 5 As shown, the contribution rate of each transmission line to the harmonic voltage of the power supply bus during the 38 switching processes is averaged, and the average contribution rates of the equivalent harmonic current sources of transmission lines 1 to 10 to the harmonic voltage of the power supply bus during the monitoring period are 2.61%, 2.17%, 29.9%, 16.13%, 15.87%, 14.24%, 8.79%, 5.05%, 1.65% and 3.58% respectively.

[0134] It can be seen that during the monitoring period, the equivalent harmonic current source of transmission line 3 is the dominant harmonic source causing the harmonic voltage of the power supply bus, and its average contribution rate to the 5th harmonic voltage of the power supply bus is 29.9%. Next, transmission line 4, transmission line 5 and transmission line 6 also have a large contribution rate to the 5th harmonic voltage of the power supply bus, with average contribution rates of 16.1%, 15.9% and 14.2% respectively, while the remaining transmission lines have little impact on the 5th harmonic voltage of the power supply bus, and their average contribution rates are less than 10%.

[0135] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will 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 quantitatively tracing the source of multiple harmonics in a converter station, characterized by: The following steps are involved: S1, monitor the operating status of the passive filter group, and synchronously collect a group of power supply bus harmonic voltage phasors, each transmission line harmonic current phasors and passive filter group harmonic current phasors before and after the passive filter group state is switched; S2. Calculate the equivalent harmonic source parameters of each transmission line according to the power supply bus harmonic voltage phasor before and after the passive filter group state switching, the harmonic current phasor of each transmission line and the harmonic current phasor of the passive filter group; S3. Calculate the power supply bus harmonic voltage calculation value according to the equivalent harmonic source parameters of each transmission line, and perform error calculation with the power supply bus harmonic voltage measurement value at the corresponding time, and perform data filtering on the equivalent harmonic source parameters of each transmission line according to the error calculation result; S4, repeat S1 to S3 until the equivalent harmonic source parameters of N groups of transmission lines corresponding to the N-times passive filter group state switching within the monitoring period are obtained; S5. Calculate the contribution rate of each transmission line to the harmonic voltage of the power supply bus during a single passive filter group state switching process, and calculate the average contribution rate of each transmission line to the harmonic voltage of the power supply bus during N passive filter group state switching processes within the monitoring period.

2. The method for quantitatively tracing the source of multiple harmonics in a converter station according to claim 1 is characterized in that: In S1, the operating status of the passive filter group is monitored. Before and after the passive filter group state is switched, a group of power supply bus harmonic voltage phasors, harmonic current phasors of each transmission line and harmonic current phasors of the passive filter group are synchronously collected, including: When the passive filter group is monitored to have its kth state switching, synchronous sampling is performed to obtain the power supply bus harmonic voltage phasors before and after the passive filter group state switching. Harmonic current phasors of each transmission line before and after the passive filter bank state switching And the harmonic current phasors of the passive filter group before and after the passive filter group state switching Wherein, h is the harmonic order, b is the mark before the passive filter group state is switched, a is the mark after the passive filter group state is switched, m is the transmission line number, m∈{1,2,...,M}, M is the number of transmission lines, and the measurement direction of the current transformer is based on the outgoing power supply bus as the reference direction.

3. The method for quantitatively tracing the source of multiple harmonics in a converter station according to claim 2 is characterized in that: When synchronously collecting a group of power supply busbar harmonic voltage phasors, each transmission line harmonic current phasors and passive filter group harmonic current phasors: In order to avoid the influence of excitation inrush current during the state switching of the passive filter group, that is, to ensure that the changes of harmonic voltage phasors and harmonic current phasors are completely caused by the impedance changes of the passive filter group, synchronous sampling is started at the zero crossing point of the fundamental voltage of phase A 1 second before the state switching of the passive filter group to obtain the power supply bus harmonic voltage phasor before the state switching of the passive filter group. Harmonic current phasors of each transmission line and passive filter bank harmonic current phasors Synchronous sampling starts at the zero-crossing point of the fundamental voltage of phase A 2 seconds after the passive filter group state is switched to obtain the power supply bus harmonic voltage phasor after the passive filter group state is switched. Harmonic current phasors of each transmission line and passive filter bank harmonic current phasors Among them, the value range of T1 and T2 is 300ms~500ms.

4. The method for quantitatively tracing the source of multiple harmonics in a converter station according to claim 2 is characterized in that: In S2, the equivalent harmonic source parameters of each transmission line are calculated according to the power supply bus harmonic voltage phasors before and after the passive filter group state switching, the harmonic current phasors of each transmission line and the harmonic current phasors of the passive filter group, including: S21, calculating the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group according to the power supply bus harmonic voltage phasor and the passive filter group harmonic current phasor before and after the passive filter group state is switched; S22, according to the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group, respectively calculating the harmonic impedance parallel value between the passive filter group and the system before and after the passive filter group state is switched; S23, according to the harmonic current phasors of each transmission line before and after the passive filter group state switching, combined with the parallel value of the harmonic impedance calculated in S22, calculate the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line.

5. The method for quantitatively tracing the source of multiple harmonics in a converter station according to claim 4 is characterized in that: In S21, the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group are calculated according to the power supply bus harmonic voltage phasor and the harmonic current phasor of the passive filter group before and after the passive filter group state is switched, including: S211. Use the following formula to calculate the harmonic impedance value of the passive filter group: Among them, Z LC,h,k,b is the harmonic impedance value of the passive filter group h before the kth state switching, Z LC,h,k,a is the hth harmonic impedance value of the passive filter group after the kth state switching; S212, using the following formula to calculate the system harmonic impedance value corresponding to the passive filter group during the k-th state switching process: Among them, Z S,h,k is the system hth harmonic impedance value corresponding to the passive filter group during the kth state switching process.

6. The method for quantitatively tracing the source of multiple harmonics in a converter station according to claim 5, characterized in that: In S22, according to the harmonic impedance value of the passive filter group and the system harmonic impedance value corresponding to the passive filter group, the harmonic impedance parallel value between the passive filter group and the system before and after the state switching is calculated, including: The following formula is used to calculate the parallel value of the harmonic impedance between the passive filter group and the system before and after the state switching: Among them, Z P,k,b is the harmonic impedance value Z of the passive filter group h before the kth state switching LC,h,k,b And the system h-order harmonic impedance value Z S,h,k The parallel value of the harmonic impedance between P,k,a is the harmonic impedance value Z of the passive filter group after the kth state switching LC,h,k,a And the system h-order harmonic impedance value Z S,h,k The parallel value of the harmonic impedance between them.

7. The method for quantitatively tracing the source of multiple harmonics in a converter station according to claim 6 is characterized in that: In S23, the equivalent harmonic current source phasor and harmonic impedance value of each transmission line are calculated according to the harmonic current phasor of each transmission line before and after the passive filter group state is switched, combined with the harmonic impedance parallel value calculated in S22, including: S231. When calculating the equivalent harmonic current source phasor and harmonic impedance value of transmission line m, the harmonic current phasors of other transmission lines are added together as the generalized transmission line: in, is the sum of the hth harmonic current phasors of the transmission lines except the transmission line m before the kth state switching, is the sum of the hth harmonic current phasors of all transmission lines before the kth state switching, is the sum of the hth harmonic current phasors of the transmission lines except the transmission line m after the kth state switching, is the sum of the hth harmonic current phasors of all transmission lines after the kth state switching, M is the number of transmission lines; S232. Use the following formula to calculate the equivalent harmonic current source phasor and harmonic impedance value of transmission line m, that is, the Norton equivalent parameter of transmission line m: in, is the equivalent hth harmonic current source phasor of transmission line m during the kth state switching process, Z S,h,m,k is the hth harmonic impedance value equivalent to the transmission line m during the kth state switching process; S233, repeat S231 to S232 until the equivalent harmonic current source phasors and harmonic impedance values ​​of all transmission lines in the k-th state switching process, that is, the Norton equivalent parameters of all transmission lines, are calculated.

8. The method for quantitatively tracing the source of multiple harmonics in a converter station according to claim 4, characterized in that: In S3, the power supply bus harmonic voltage calculation value is calculated according to the equivalent harmonic source parameters of each transmission line, and the error calculation is performed with the power supply bus harmonic voltage measurement value at the corresponding time. According to the error calculation result, the equivalent harmonic source parameters of each transmission line are filtered, including: Since the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line before and after the passive filter group state switching are the same, the contribution rate of the equivalent harmonic source of each transmission line to the power supply bus harmonic voltage before and after the passive filter group state switching is the same. Here, the calculation is performed based on the state before the passive filter group switching: S31. Use the following formula to calculate the power supply bus harmonic voltage value: in, is the calculated value of the hth harmonic voltage of the power supply bus before the kth state switching; S32, use the following formula to calculate the harmonic voltage of the power supply bus The error calculation is performed with the measured value of the power supply bus harmonic voltage at the corresponding time: Among them, ε k,b is the calculated value of the hth harmonic voltage of the power supply bus before the kth state switching Relative to the sampling obtained before the kth state switching power supply bus harmonic voltage phasor The error rate of S33, when |ε k,b |>β, it is considered that the errors of the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line in the kth state switching process are large, and the equivalent harmonic current source phasors and harmonic impedance values ​​of each transmission line in this state switching process are removed; Wherein, β is a preset threshold value, and its value range is 5% to 10%.

9. The method for quantitatively tracing the source of multiple harmonics in a converter station according to claim 8, characterized in that: S5 calculates the contribution rate of each transmission line to the power supply bus harmonic voltage during a single passive filter group state switching process, and calculates the average contribution rate of each transmission line to the power supply bus harmonic voltage during N passive filter group state switching processes within the monitoring period, including: S51. The contribution rate of the transmission line m to the power supply bus harmonic voltage during the nth state switching process is calculated using the following formula: Among them, C U,h,m,n is the contribution rate of the equivalent harmonic current source of transmission line m to the hth harmonic voltage of the power supply bus during the nth state switching process, for exist The projection angle on is the hth harmonic current source phasor equivalent to the transmission line m during the nth state switching process, is the sum of the equivalent h-th harmonic current source phasors of all transmission lines during the n-th state switching process, M is the number of transmission lines, n is a subset of k; S52. The following formula is used to calculate the average contribution rate of the transmission line m to the power supply bus harmonic voltage during the N-time passive filter group state switching process during the monitoring period: in, is the average contribution rate of the harmonic current source equivalent to the transmission line m to the hth harmonic voltage of the power supply bus during the nth state switching process, and N is the total number of state switching of the passive filter group that meets the data error requirements during the monitoring period; S53, repeat S51 to S52 until the average contribution rate of all transmission lines to the power supply bus harmonic voltage during the N-times passive filter group state switching process within the monitoring period is calculated.

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