A method and system for identifying the operating state of an AC filter bank in a converter station

Abstract

The present invention discloses a method and system for identifying the operating state of an AC filter bank in a converter station. The method includes: synchronously collecting the root mean square value of the fundamental voltage of the AC bus in the converter station, the root mean square value of the harmonic voltage of the concerned frequency, the root mean square value of the fundamental current of the AC filter bank, and the root mean square value of the harmonic current of the concerned frequency; calculating the fundamental impedance, the harmonic impedance of the concerned frequency, and the fundamental reactive power of the AC filter bank under the actual operating state; calculating the fundamental impedance, the harmonic impedance of the concerned frequency, and the fundamental reactive power of the AC filter bank under the preset operating state; comparing the fundamental reactive power, the fundamental impedance, and the harmonic impedance of the concerned frequency under the actual operating state and the preset operating state to determine the actual operating state of the AC filter bank. The advantages of the present invention are: realizing the accurate identification of the operating state of the AC filter bank in the converter station to clarify the cause of the abnormal harmonic level in the converter station.

Description

Technical Field

[0001] The present invention relates to the field of converter station operation, and particularly to a method and system for identifying the operation state of an AC filter bank in a converter station. Background Art

[0002] In a high-voltage DC converter station, to filter out a large amount of harmonics generated during the operation of the converter and compensate for the reactive power consumed by the DC control system, a certain number of filter banks need to be configured on the AC side. The converter that realizes AC-DC conversion absorbs a large amount of reactive power during operation, and the reactive power demand changes dynamically with the operation state of the converter. To ensure the stable operation of the system, the converter station needs to configure different types and quantities of AC filters, and change the operation state of the AC filter bank in an automatic switching manner to fully compensate for the reactive power absorbed by the converter. In this process, different combinations of AC filters may amplify non-characteristic harmonics to different degrees. To reveal the mechanism of non-characteristic harmonic amplification caused by the AC filter bank and quantify the influence of different types and quantities of AC filter combinations on non-characteristic harmonic amplification, it is necessary to accurately analyze the operation state of the AC filter bank in the converter station.

[0003] However, there is currently a lack of detailed records of the operation combinations and quantities of the AC filter banks in the converter station, making it difficult to accurately obtain relevant information, resulting in the inability to grasp the operation state of the AC filter bank when the harmonic level in the converter station is abnormal and the inability to establish a corresponding relationship between the two. For example, Chinese Patent Publication No. CN118841981A discloses a method for coordinated control of switching of an AC filter bank applicable to a CLCC converter station and a CLCC converter, which mainly controls the switching of the AC filter bank and cannot identify the operation state of the AC filter bank when the harmonic level in the converter station is abnormal. Therefore, how to make full use of monitoring data to accurately identify the operation state of the AC filter bank in the converter station to clarify the cause of the abnormal harmonic level in the converter station is a key technical problem that needs to be solved urgently at present. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to accurately identify the operation state of the AC filter bank in the converter station to clarify the cause of the abnormal harmonic level in the converter station.

[0005] The present invention solves the above technical problem by the following technical means: A method for identifying the operation state of an AC filter bank in a converter station, comprising:

[0006] S1. Synchronously collect the root mean square value of the fundamental wave voltage of the AC bus in the converter station, the root mean square value of the harmonic voltage of the concerned frequency, the root mean square value of the fundamental wave current of the AC filter bank, and the root mean square value of the harmonic current of the concerned frequency;

[0007] S2. Calculate the fundamental impedance, the harmonic impedance of the concerned frequencies, and the fundamental reactive power of the AC filter bank under the actual operating state based on S1;

[0008] S3. Collect the circuit topology and component parameters of the AC filter, and calculate the fundamental impedance and the harmonic impedance of the concerned frequencies of the AC filter bank under the preset operating state;

[0009] S4. Calculate the fundamental reactive power of the AC filter bank under the preset operating state according to the root mean square value of the fundamental voltage of the converter station AC bus and the fundamental impedance of the AC filter bank under the preset operating state;

[0010] S5. Compare the fundamental reactive power, the fundamental impedance, and the harmonic impedance of the concerned frequencies under the actual operating state and the preset operating state, and determine whether the preset operating state of the AC filter bank is consistent with the actual operating state. If not, re-preset the operating state and return to execute S3 to S5 until the actual operating state is consistent with the preset operating state, then obtain the actual operating state of the AC filter, thereby realizing the identification of the operating state of the AC filter bank.

[0011] Further, S1 includes:

[0012]

[0013]

[0014]

[0015]

[0016] In the formula, is the th voltage time-domain discrete signal of the synchronous sampling of the converter station AC bus, is the th current time-domain discrete signal of the th group of AC filter banks, is the root mean square value of the fundamental voltage of the converter station AC bus; is the root mean square value of the th harmonic voltage of the converter station AC bus; is the root mean square value of the fundamental current of the th group of AC filter banks; is the th group of AC filter banks th harmonic current root mean square value; is the number of sampling points for 10 cycles of the voltage or current waveform time-domain discrete signal; is the number of the time-domain discrete signal, and the value range is ; is the number of the AC filter bank group; is the harmonic order; is the imaginary unit; is the natural constant; represents taking the modulus value of the phasor.

[0017] Furthermore, S2 includes:

[0018] Taking the ratio of the root mean square value of the fundamental voltage of the converter station AC bus to the root mean square value of the fundamental current of the th group of AC filter banks as the fundamental impedance of the th group of AC filter banks under the actual operating state; the root mean square value of the th harmonic voltage of the converter station AC bus to the th group of AC filter banks th harmonic current root mean square value ratio as the th group of AC filter banks th harmonic impedance; three times the product of the root mean square value of the fundamental voltage of the converter station AC bus and the root mean square value of the fundamental current of the th group of AC filter banks as the fundamental reactive power of the th group of AC filter banks under the actual operating state.

[0019] Furthermore, S3 includes:

[0020] Collect the circuit topology and component parameters of the converter station AC filter, and preset the operating state of the AC filter bank, then

[0021]

[0022]

[0023] In the formula, is the fundamental impedance of the th group of AC filter banks under the preset operating state; is the th group of AC filter banks th harmonic impedance; is the fundamental impedance of the th type of AC filter; is the th type of AC filter th harmonic impedance; is the th group of AC filter banks th type of AC filter preset total number of operations; is the number of the AC filter type, is the total number of AC filter types.

[0024] Furthermore, S4 includes:

[0025] The square of the three times the RMS value of the AC bus fundamental voltage of the converter station is equal to the The ratio of the fundamental impedance of the AC filter group is used as the first Fundamental reactive power of AC filter group.

[0026] Furthermore, S5 includes:

[0027] The preset commissioning state and the actual commissioning state The absolute value of the difference between the fundamental reactive power of the AC filter group and the actual operation state The fundamental reactive power ratio of the AC filter group is used as the fundamental reactive power difference change rate. ; The first The difference between the fundamental impedance of the AC filter group and the actual operation state The ratio of the fundamental impedance of the AC filter group is taken as the The change rate of the fundamental impedance difference of the AC filter group ; The first AC filter group The difference between the subharmonic impedance and the actual operation state AC filter group The ratio of subharmonic impedance is taken as the AC filter group Subharmonic impedance difference change rate ;

[0028] like and and , then The actual operation status of the AC filter group is consistent with the preset operation status; if or or , then The actual operation status of the group AC filter is inconsistent with the preset operation status, among which, The threshold value of the difference change rate is set.

[0029] The present invention also provides a converter station AC filter group operation status identification system, comprising:

[0030] A data acquisition module is used to synchronously collect the RMS value of the fundamental voltage of the AC busbar of the converter station, the RMS value of the harmonic voltage of the concerned frequency, the RMS value of the fundamental current of the AC filter group, and the RMS value of the harmonic current of the concerned frequency;

[0031] The actual operation data calculation module is used to calculate the fundamental impedance, the harmonic impedance of the concerned frequencies, and the fundamental reactive power of the AC filter bank under the actual operation state based on the data acquisition module;

[0032] The first preset operation calculation module is used to collect the circuit topology and component parameters of the AC filter, and calculate the fundamental impedance and the harmonic impedance of the concerned frequencies of the AC filter bank under the preset operation state;

[0033] The second preset operation calculation module is used to calculate the fundamental reactive power of the AC filter bank under the preset operation state according to the root mean square value of the fundamental voltage of the AC bus of the converter station and the fundamental impedance of the AC filter bank under the preset operation state;

[0034] The state identification module is used to compare the fundamental reactive power, the fundamental impedance, and the harmonic impedance of the concerned frequencies under the actual operation state and the preset operation state, and judge whether the preset operation state of the AC filter bank is consistent with the actual operation state. If not, the preset operation state is reset, and the process returns to execute the first preset operation calculation module to the state identification module until the actual operation state is consistent with the preset operation state, then the actual operation state of the AC filter is obtained, so as to realize the identification of the operation state of the AC filter bank.

[0035] Further, the data acquisition module is also used for:

[0036]

[0037]

[0038]

[0039]

[0040] Wherein, is the th voltage time-domain discrete signal of the synchronous sampling of the AC bus of the converter station, is the th current time-domain discrete signal of the th group of AC filter banks, is the root mean square value of the fundamental voltage of the AC bus of the converter station; is the rd harmonic voltage root mean square value of the AC bus of the converter station; is the root mean square value of the fundamental current of the th group of AC filter banks; is the th group of AC filter banks rd harmonic current root mean square value; is the number of sampling points of 10 cycles of the voltage or current waveform time-domain discrete signal; is the number of the time-domain discrete signal, and its value range is ; is the number of the AC filter groups; is the harmonic order; is the imaginary unit; is the natural constant; represents taking the modulus value of the phasor.

[0041] Furthermore, the actual operation data calculation module is also used for:

[0042] taking the ratio of the root mean square value of the fundamental voltage of the converter station AC bus to the root mean square value of the fundamental current of the th group of AC filter banks as the fundamental impedance of the th group of AC filter banks under the actual operation state; the root mean square value of the th harmonic voltage of the converter station AC bus to the root mean square value of the th group of AC filter banks th harmonic current as the th group of AC filter banks th harmonic impedance under the actual operation state; three times the product of the root mean square value of the fundamental voltage of the converter station AC bus and the root mean square value of the fundamental current of the th group of AC filter banks as the fundamental reactive power of the th group of AC filter banks under the actual operation state.

[0043] Furthermore, the first preset operation calculation module is also used for:

[0044] collecting the circuit topology and component parameters of the converter station AC filter, and presetting the operation state of the AC filter banks, then

[0045]

[0046]

[0047] where is the fundamental impedance of the th group of AC filter banks under the preset operation state; is the th group of AC filter banks th harmonic impedance; is the fundamental impedance of the th type of AC filter; is the th type of AC filter th harmonic impedance; is the th group of AC filter banks th type of AC filter preset total operation number; is the number of the AC filter type, is the total number of the AC filter types.

[0048] Further, the second preset commissioning calculation module is further configured to:

[0049] Take the ratio of the square of three times the root mean square value of the fundamental wave voltage of the AC bus of the converter station to the fundamental wave impedance of the th group of AC filter banks in the preset commissioning state as the fundamental wave reactive power of the th group of AC filter banks in the preset commissioning state.

[0050] Further, the state identification module is further configured to:

[0051] Take the ratio of the absolute value of the difference between the fundamental wave reactive power of the th group of AC filter banks in the preset commissioning state and the actual commissioning state to the fundamental wave reactive power of the th group of AC filter banks in the actual commissioning state as the fundamental wave reactive power difference change rate ; Take the ratio of the difference between the fundamental wave impedances of the th group of AC filter banks in the preset commissioning state and the actual commissioning state to the fundamental wave impedance of the th group of AC filter banks in the actual commissioning state as the fundamental wave impedance difference change rate of the th group of AC filter banks ; Take the ratio of the difference between the th harmonic impedances of the th group of AC filter banks in the preset commissioning state and the actual commissioning state to the th harmonic impedance of the th group of AC filter banks in the actual commissioning state as the th harmonic impedance difference change rate of the th group of AC filter banks ;

[0052] If and and , then the actual commissioning state of the th group of AC filter banks is consistent with the preset commissioning state; if or or , then the actual commissioning state of the th group of AC filters is inconsistent with the preset commissioning state, where is the threshold of the set difference change rate.

[0053] The advantages of the present invention are:

[0054] (1)On the one hand, in one aspect of the present invention, the fundamental impedance, the harmonic impedance of the concerned frequencies, and the fundamental reactive power of the AC filter bank under the actual operation state are obtained by using the voltage and current data monitored in real time by the AC filter bank of the converter station. On the other hand, according to the topologies and component parameters of all types of AC filters in the converter station, the fundamental impedance and the harmonic impedance of the concerned frequencies of the AC filter bank under the preset operation state are calculated. According to the root mean square value of the fundamental voltage of the AC bus of the converter station and the fundamental impedance of the AC filter bank under the preset operation state, the fundamental reactive power of the AC filter bank under the preset operation state is calculated. Finally, based on the rate of change of the difference between the actual operation state and the preset operation state, the operation combination of the AC filter bank is identified, and the accurate identification of the operation state of the AC filter bank of the converter station is realized. When the actual operation state of the AC filter is inconsistent with the preset operation state, it indicates that the preset operation state of the AC filter does not conform to the actual operation state, and the preset operation state needs to be reset. Repeat steps S3, S4, and S5 until the actual operation state is consistent with the preset operation state, so as to clarify the actual operation state of the AC filter bank of the converter station. After identifying the actual operation state, it is beneficial to analyze the causes of the abnormal harmonic levels in the converter station subsequently.

[0055] (2)When there is a lack of detailed records of the operation combination and quantity of the AC filter bank in the converter station and it is difficult to accurately obtain them, this method makes full use of the monitoring data to accurately identify the operation state of the AC filter in the converter station, providing reliable support for revealing the mechanism of non - characteristic harmonic amplification caused by the AC filter bank, quantifying the influence of different types and quantities of AC filter combinations on non - characteristic harmonic amplification, and clarifying the causes of the abnormal harmonic state in the converter station. Description of the Drawings

[0056] Figure 1 It is a flowchart of a method for identifying the operation state of an AC filter bank in a converter station disclosed in an embodiment of the present invention;

[0057] Figure 2 It is a schematic diagram of the positions of voltage and current sampling points in a method for identifying the operation state of an AC filter bank in a converter station disclosed in an embodiment of the present invention;

[0058] Figure 3 It is a schematic diagram of the positions of voltage and current sampling points in an experimental case of a method for identifying the operation state of an AC filter bank in a converter station disclosed in an embodiment of the present invention;

[0059] Figure 4(a) and Figure 4(b) are respectively the circuit topologies of the HP3 filter and the HP12 / 24 filter in a method for identifying the operation state of an AC filter bank in a converter station disclosed in an embodiment of the present invention. Detailed Embodiment

[0060] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0061] Embodiment 1

[0062] As Figure 1 shown, Embodiment 1 of the present invention provides a method for identifying the operation state of the AC filter bank in a converter station. Based on the fact that the actual operation state of the AC filter bank in the converter station (i.e., the operation combinations of different types of AC filters) is not clear, only the fundamental impedance, harmonic impedance, fundamental reactive power, etc. can be obtained from the measured voltage and current. Therefore, it is necessary to preset the operation state (i.e., preset the operation combinations of AC filters), calculate the fundamental impedance, harmonic impedance, and fundamental reactive power through the measured voltage and the inductance, capacitance, and resistance of the AC filter; compare the fundamental impedance, harmonic impedance, and fundamental reactive power under the preset operation state with those under the actual operation state to identify the actual operation state of the AC filter bank. After identifying the actual operation state, based on the actual operation state, reveal the mechanism of non-characteristic harmonic amplification caused by the AC filter bank and quantify the influence of different types and quantities of AC filter combinations on non-characteristic harmonic amplification. The method proposed by the present invention specifically includes the following steps:

[0063] S1. Synchronously collect the root mean square value of the fundamental voltage of the AC bus in the converter station, the root mean square value of the harmonic voltage of the concerned frequency, the root mean square value of the fundamental current of the AC filter bank, and the root mean square value of the harmonic current of the concerned frequency; The detailed process of S1 is as follows:

[0064] As Figure 2 shown, synchronously sample the th voltage time-domain discrete signal of the AC bus in the converter station and the th current time-domain discrete signal of the th group of AC filter banks, where is the number of the time-domain discrete signals of the sampled voltage and current waveforms, and is the number of the AC filter bank groups. Convert the sampled signals from the time-domain representation to the frequency-domain representation through the discrete Fourier transform, and set the window width to 10 cycles. The specific calculation formula is as follows:

[0065]

[0066]

[0067] ​

[0068]

[0069] In the formula, is the root mean square value of the fundamental voltage of the AC bus of the converter station; is the AC bus of the converter station root mean square value of the nth harmonic voltage; is the root mean square value of the fundamental current of the nth group of AC filter banks; is the nth group of AC filter banks root mean square value of the nth harmonic current; is the number of sampling points for 10 cycles of the time-domain discrete signal of the voltage or current waveform; is the number of the time-domain discrete signal, and the value range is ; is the number of the AC filter bank group; is the harmonic order; is the imaginary unit; is the natural constant; means taking the modulus value of the phasor.

[0070] S2. Calculate the fundamental impedance, the concerned frequency harmonic impedance, and the fundamental reactive power of the AC filter bank under the actual operation state; The detailed process of S2 is as follows:

[0071] Calculate the fundamental impedance, the nth harmonic impedance, and the fundamental reactive power of the nth group of AC filter banks under the actual operation state. The specific formulas are as follows: In the formula,

[0072]

[0073]

[0074]

[0075] In the formula, is the fundamental impedance of the nth group of AC filter banks under the actual operation state; is the nth group of AC filter banks under the actual operation state is the nth group of AC filter banks under the actual operation state nth harmonic impedance; is the fundamental reactive power of the nth group of AC filter banks under the actual operation state. is the fundamental reactive power of the nth group of AC filter banks under the actual operation state is the fundamental reactive power of the nth group of AC filter banks under the actual operation state.

[0076] S3. Collect the circuit topology and component parameters of the AC filter, and calculate the fundamental impedance and the impedance of the concerned frequency harmonics of the AC filter bank under the preset operating state. The detailed process of S3 is as follows:

[0077] Collect the circuit topology and component parameters of the AC filter in the converter station, and preset the operating state of the AC filter bank. Then

[0078]

[0079]

[0080] In the formula, is the fundamental impedance of the th group of AC filter banks under the preset operating state; is the th harmonic impedance of the th group of AC filter banks under the preset operating state; is the fundamental impedance of the th type of AC filter; is the th harmonic impedance of the th type of AC filter; is the preset total number of operations of the th type of AC filter in the th group of AC filter banks; is the number of the AC filter type, is the total number of AC filter types.

[0081] S4. According to the root mean square value of the fundamental voltage of the AC bus in the converter station and the fundamental impedance of the AC filter bank under the preset operating state, calculate the fundamental reactive power of the AC filter bank under the preset operating state. The detailed process of S4 is as follows:

[0082] According to the root mean square value of the fundamental voltage of the AC bus in the converter station and the fundamental impedance of the th group of AC filter banks under the preset operating state, theoretically deduce the fundamental reactive power of the th group of AC filter banks under the preset operating state. The calculation formula is as follows:

[0083]

[0084] In the formula, is the fundamental reactive power of the th group of AC filter banks under the preset operating state.

[0085] S5. Compare the fundamental reactive power, fundamental impedance, and harmonic impedance of the concerned frequencies under the actual operation state and the preset operation state, and determine whether the preset operation state of the AC filter bank is consistent with the actual operation state. If not, reset the operation state and return to execute S3 to S5 until the actual operation state is consistent with the preset operation state, then obtain the actual operation state of the AC filter, thereby realizing the identification of the operation state of the AC filter bank. The detailed process of S5 is as follows:

[0086] Calculate the rate of change of the difference in fundamental reactive power, fundamental impedance, and the impedance of the

[0087]

[0088]

[0089]

[0090] In the formula, is the rate of change of the difference in fundamental reactive power; is the rate of change of the difference in fundamental impedance of the th group of AC filter banks; is the th group of AC filter banks rate of change of the difference in harmonic impedance.

[0091] If and and , then the actual operation state of the th group of AC filter banks is consistent with the preset operation state; if or or , then the actual operation state of the th group of AC filters is inconsistent with the preset operation state. Among them, is the threshold of the set rate of change of the difference, and it is recommended to take values such as 5% and 10%. When the actual operation state of the th group of AC filter banks is inconsistent with the preset operation state, the operation state needs to be reset until the actual operation state is consistent with the preset operation state, then the actual combination of the AC filter is obtained.

[0092] To better introduce the present invention, the following is a detailed description through a specific experimental case:

[0093] The schematic diagram of the 500 kV AC yard wiring of a 1100 kV converter station is as shown in Figure 3As shown, a voltage measurement point is set at the 500 kV AC bus, and current measurement points are set at the output sides of three groups of AC filters. Synchronously collect the AC bus voltage of the converter station: , , ; The first group of AC filter banks: , , ; The second group of AC filter banks: , , ; The third group of AC filter banks: , , .

[0094] Calculate the first group of AC filter banks under the actual operation state: , , , ; The second group of AC filter banks: , , , ; The third group of AC filter banks: , , , .

[0095] Collect the circuit topologies and component parameters of the AC filters as shown in Figure 4(a), Figure 4(b) and Table 1. Figure 4(a) is a schematic diagram of a single-tuned filter (abbreviation: HP3), and Figure 4(b) is a schematic diagram of a double-tuned filter (abbreviation: HP12 / 24).

[0096] Table 1 AC filter component parameters

[0097]

[0098] The first group of AC filter banks includes two groups of HP12 / 24 and one group of HP3; the second group of AC filter banks includes three groups of HP12 / 24; the third group of AC filter banks includes three groups of HP12 / 24.

[0099] Calculate the fundamental impedance, 5th harmonic impedance, 7th harmonic impedance and fundamental reactive power of the first group, the second group and the third group of AC filter banks under the preset operation state, as shown in Table 2.

[0100] Table 2 AC filter parameters under the preset operation state

[0101]

[0102] Calculate the rate of change of the differences in fundamental reactive power, fundamental impedance, 5th harmonic impedance, and 7th harmonic impedance between the actual operating state and the preset operating state, as shown in Table 3.

[0103] Table 3 Rate of change of difference parameters

[0104]

[0105] Let , then the first group of AC filter combinations is 1 group of HP12 / 24 + 1 group of HP3; the second group of AC filter combinations is 3 groups of HP12 / 24; the third group of AC filter combinations is 1 group of HP12 / 24.

[0106] Through the above technical solutions, on the one hand, the present invention uses the voltage and current data of the AC filter bank in the converter station monitored in real time to obtain the fundamental impedance, the harmonic impedance of the concerned frequencies, and the fundamental reactive power of the AC filter bank in the actual operating state; on the other hand, according to the topologies and component parameters of all types of AC filters in the converter station, it calculates the fundamental impedance, the harmonic impedance of the concerned frequencies, and the fundamental reactive power of the AC filter bank in the preset operating state. Finally, based on the rate of change of the difference between the two, it identifies the operating combinations and quantities of the AC filter bank. This method makes full use of the monitoring data to accurately identify the operating state of the AC filters in the converter station in the case where the operating combinations and quantities of the AC filter bank in the converter station lack detailed records and are difficult to accurately obtain, providing reliable support for revealing the mechanism of non-characteristic harmonic amplification caused by the AC filter bank, quantifying the influence of different types and quantities of AC filter combinations on non-characteristic harmonic amplification, and clarifying the causes of abnormal harmonic states in the converter station.

[0107] Embodiment 2

[0108] Based on Embodiment 1, Embodiment 2 of the present invention further provides a system for identifying the operating state of an AC filter bank in a converter station, including:

[0109] A data acquisition module for synchronously collecting the root mean square value of the fundamental voltage of the AC bus in the converter station, the root mean square value of the harmonic voltage of the concerned frequencies, the root mean square value of the fundamental current of the AC filter bank, and the root mean square value of the harmonic current of the concerned frequencies;

[0110] An actual operation data calculation module for calculating the fundamental impedance, the harmonic impedance of the concerned frequencies, and the fundamental reactive power of the AC filter bank in the actual operating state based on the data acquisition module;

[0111] A first preset operation calculation module for collecting the circuit topologies and component parameters of the AC filters and calculating the fundamental impedance and the harmonic impedance of the concerned frequencies of the AC filter bank in the preset operating state;

[0112] The second preset operation calculation module is used to calculate the fundamental reactive power of the AC filter bank under the preset operation state according to the root mean square value of the fundamental voltage of the AC bus of the converter station and the fundamental impedance of the AC filter bank under the preset operation state;

[0113] The state identification module is used to compare the fundamental reactive power, fundamental impedance, and harmonic impedance of the concerned frequency under the actual operation state and the preset operation state, and judge whether the preset operation state of the AC filter bank is consistent with the actual operation state. If not, the preset operation state is reset, and the process returns to execute the first preset operation calculation module to the state identification module until the actual operation state is consistent with the preset operation state, then the actual operation state of the AC filter bank is obtained, thereby realizing the identification of the operation state of the AC filter bank.

[0114] Specifically, the data acquisition module is further used for:

[0115]

[0116]

[0117]

[0118]

[0119] In the formula, is the root mean square value of the fundamental voltage of the AC bus of the converter station; is the AC bus of the converter station the root mean square value of the nth harmonic voltage; is the root mean square value of the fundamental current of the mth group of AC filter banks; is the mth group of AC filter banks the root mean square value of the nth harmonic current; is the number of sampling points for 10 cycles of the time-domain discrete signal of the voltage or current waveform; is the number of the time-domain discrete signal, and the value range is ; is the number of the AC filter bank group; is the harmonic order; is the imaginary unit; is the natural constant; represents taking the modulus value of the phasor.

[0120] Specifically, the actual operation data calculation module is further used for:

[0121] Taking the ratio of the root mean square value of the fundamental voltage of the AC bus of the converter station to the root mean square value of the fundamental current of the mth group of AC filter banks as the mth under the actual operation state Fundamental impedance of the AC filter bank; AC bus of the converter station The root mean square value of the harmonic voltage and the AC filter bank Ratio of the root mean square value of the harmonic current as the AC filter bank Harmonic impedance; Three times the product of the root mean square value of the fundamental voltage of the AC bus of the converter station and the root mean square value of the fundamental current of the AC filter bank as the fundamental reactive power of the AC filter bank under the actual operation state.

[0122] Specifically, the first preset operation calculation module is further configured to:

[0123] Collect the circuit topology and component parameters of the AC filter of the converter station, and preset the operation state of the AC filter bank, then

[0124]

[0125]

[0126] In the formula, Is the fundamental impedance of the AC filter bank under the preset operation state; Is the AC filter bank under the preset operation state Harmonic impedance; Is the fundamental impedance of the th type of AC filter; Is the th type of AC filter Harmonic impedance; Is the AC filter bank Preset total operation number of the th type of AC filter; Is the number of the AC filter type,

[0127] Specifically, the second preset operation calculation module is further configured to:

[0128] Take the ratio of the square of three times the root mean square value of the fundamental voltage of the AC bus of the converter station to the fundamental impedance of the AC filter bank under the preset operation state as the fundamental reactive power of the AC filter bank under the preset operation state.

[0129] Specifically, the state identification module is further configured to:

[0130] Take the absolute value of the difference between the fundamental reactive power of the th group of AC filter banks in the preset and actual operating states and divide it by the fundamental reactive power of the th group of AC filter banks in the actual operating state as the fundamental reactive power difference change rate ; take the ratio of the difference between the fundamental impedances of the th group of AC filter banks in the preset and actual operating states to the fundamental impedance of the th group of AC filter banks in the actual operating state as the fundamental impedance difference change rate of the th group of AC filter banks ; take the ratio of the difference between the th group of AC filter banks' th harmonic impedances in the preset and actual operating states to the th group of AC filter banks' th harmonic impedance in the actual operating state as the th group of AC filter banks' th harmonic impedance difference change rate ;

[0131] If and and , then the actual operating state of the th group of AC filter banks is consistent with the preset operating state; if or or , then the actual operating state of the th group of AC filters is inconsistent with the preset operating state, where is the threshold of the set difference change rate.

[0132] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for identifying the operation status of an AC filter group in a converter station, characterized in that: include: S1. Synchronously collect the RMS value of the fundamental voltage of the AC busbar of the converter station, the RMS value of the harmonic voltage of the concerned frequency, the RMS value of the fundamental current of the AC filter group, and the RMS value of the harmonic current of the concerned frequency; S2, based on S1, calculates the fundamental impedance, harmonic impedance of the concerned frequency and fundamental reactive power of the AC filter group under the actual operation state; S3, collecting the circuit topology and component parameters of the AC filter, and calculating the fundamental impedance and harmonic impedance of the concerned frequency of the AC filter group under the preset operation state; S4. Calculate the fundamental reactive power of the AC filter group in the preset operation state according to the RMS value of the fundamental voltage of the AC busbar of the converter station and the fundamental impedance of the AC filter group in the preset operation state; S5. Compare the fundamental reactive power, fundamental impedance, and harmonic impedance of the frequency of interest under the actual operation state and the preset operation state to determine whether the preset operation state of the AC filter group is consistent with the actual operation state. If not, reset the operation state and return to execute S3 to S5 until the actual operation state is consistent with the preset operation state. Then, the actual operation state of the AC filter is obtained, thereby realizing the identification of the operation state of the AC filter group.

2. A method for identifying the operation status of an AC filter group in a converter station according to claim 1, characterized in that: S1 includes: In the formula, The first A voltage time-domain discrete signal, For the AC filter group A current discrete signal in time domain, is the RMS value of the AC bus fundamental voltage of the converter station; AC busbar for converter station Subharmonic voltage RMS value; For the The RMS value of the fundamental current of the AC filter group; For the AC filter group Subharmonic current RMS value; The number of sampling points of 10 cycles of the discrete time domain signal of the voltage or current waveform; is the number of the discrete signal in the time domain, and its value range is ; is the number of AC filter groups; is the harmonic order; is an imaginary unit; is a natural constant; Indicates the modulus value of the phase quantity.

3. A method for identifying the operation status of an AC filter group in a converter station according to claim 1, characterized in that S2 include: The RMS value of the AC bus fundamental voltage of the converter station is The ratio of the fundamental current root mean square value of the AC filter group is taken as the first AC filter group fundamental impedance; AC busbar of converter station The RMS value of the subharmonic voltage is AC filter group The ratio of the root mean square value of the sub-harmonic current is taken as the first AC filter group harmonic impedance; three times the RMS value of the fundamental voltage of the AC busbar of the converter station and the The product of the root mean square value of the fundamental current of the AC filter group is taken as the first Fundamental reactive power of the AC filter group.

4. A method for identifying the operation status of an AC filter group in a converter station according to claim 1, characterized in that S3 include: Collect the converter station AC filter circuit topology and component parameters, preset the operation status of the AC filter group, then In the formula, The first Fundamental impedance of the AC filter group; The first AC filter group Subharmonic impedance; For the Fundamental impedance of the AC filter type; For the AC filter types Subharmonic impedance; For the AC filter group The total number of AC filter types that are expected to be put into operation; is the number of the AC filter type, is the total number of AC filter types.

5. The method for identifying the operation status of the AC filter group of a converter station according to claim 1, characterized in that S4 include: The square of the three times the RMS value of the AC bus fundamental voltage of the converter station is equal to the The ratio of the fundamental impedance of the AC filter group is used as the first Fundamental reactive power of AC filter group.

6. A method for identifying the operation status of an AC filter group in a converter station according to claim 1, characterized in that S5 include: The preset commissioning state and the actual commissioning state The absolute value of the difference between the fundamental reactive power of the AC filter group and the actual operation state The fundamental reactive power ratio of the AC filter group is used as the fundamental reactive power difference change rate. ; The first The difference between the fundamental impedance of the AC filter group and the actual operation state The ratio of the fundamental impedance of the AC filter group is taken as the The change rate of the fundamental impedance difference of the AC filter group ; The first AC filter group The difference between the subharmonic impedance and the actual operation state AC filter group The ratio of subharmonic impedance is taken as the AC filter group Subharmonic impedance difference change rate ; like and and , then The actual operation status of the AC filter group is consistent with the preset operation status; if or or , then The actual operation status of the group AC filter is inconsistent with the preset operation status, among which, The threshold value of the difference change rate is set.

7. A converter station AC filter bank operation status identification system, characterized in that: include: A data acquisition module is used to synchronously collect the RMS value of the fundamental voltage of the AC busbar of the converter station, the RMS value of the harmonic voltage of the concerned frequency, the RMS value of the fundamental current of the AC filter group, and the RMS value of the harmonic current of the concerned frequency; The actual operation data calculation module is used to calculate the fundamental impedance, harmonic impedance of the concerned frequency and fundamental reactive power of the AC filter group under the actual operation state based on the data acquisition module; The first preset operation calculation module is used to collect the circuit topology and component parameters of the AC filter, and calculate the fundamental impedance and the harmonic impedance of the concerned frequency of the AC filter group under the preset operation state; The second preset operation calculation module is used to calculate the fundamental reactive power of the AC filter group in the preset operation state according to the RMS value of the fundamental voltage of the AC busbar of the converter station and the fundamental impedance of the AC filter group in the preset operation state; The state identification module is used to compare the fundamental reactive power, fundamental impedance, and harmonic impedance of the frequency of interest under the actual operation state and the preset operation state, and determine whether the preset operation state of the AC filter group is consistent with the actual operation state. If not, the operation state is reset, and the first preset operation calculation module is returned to the state identification module until the actual operation state is consistent with the preset operation state. The actual operation state of the AC filter is obtained, thereby realizing the operation state identification of the AC filter group.

8. The system for identifying the operation status of the AC filter group of a converter station according to claim 7, characterized in that: The data acquisition module is also used to: In the formula, The first A voltage time-domain discrete signal, For the AC filter group A current discrete signal in time domain, is the RMS value of the AC bus fundamental voltage of the converter station; AC busbar for converter station Subharmonic voltage RMS value; For the The RMS value of the fundamental current of the AC filter group; For the AC filter group Subharmonic current RMS value; The number of sampling points of 10 cycles of the discrete time domain signal of the voltage or current waveform; is the number of the discrete signal in the time domain, and its value range is ; is the number of AC filter groups; is the harmonic order; is an imaginary unit; is a natural constant; Indicates the modulus value of the phase quantity.

9. The system for identifying the operation status of the AC filter group of a converter station according to claim 7, characterized in that: The actual operation data calculation module is also used for: The RMS value of the AC bus fundamental voltage of the converter station is The ratio of the fundamental current root mean square value of the AC filter group is taken as the first AC filter group fundamental impedance; AC busbar of converter station The RMS value of the subharmonic voltage is AC filter group The ratio of the root mean square value of the sub-harmonic current is taken as the first AC filter group harmonic impedance; three times the RMS value of the fundamental voltage of the AC busbar of the converter station and the The product of the root mean square value of the fundamental current of the AC filter group is taken as the first Fundamental reactive power of the AC filter group.

10. The system for identifying the operation status of the AC filter group of a converter station according to claim 7, characterized in that: The first preset operation calculation module is also used for: Collect the converter station AC filter circuit topology and component parameters, preset the operation status of the AC filter group, then In the formula, The first Fundamental impedance of the AC filter group; The first AC filter group Subharmonic impedance; For the Fundamental impedance of the AC filter type; For the AC filter types Subharmonic impedance; For the AC filter group The total number of AC filter types that are expected to be put into operation; is the number of the AC filter type, is the total number of AC filter types.

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