Converter station AC filter unbalance protection improvement method and device, and storage medium

Abstract

The invention discloses a converter station AC filter unbalance protection improvement method and device and a storage medium, and relates to the technical field of electrical equipment monitoring, and the method comprises the steps: determining the consistency of the rated voltage of a capacitor element and the actual operation voltage; calculating the reliable fusing energy of the internal fuse, and judging whether the fuse can be reliably fused or not when the single capacitor unit fails; optimizing an unbalanced III section protection constant value; delay tripping logic of an unbalanced protection IV section is added; and verifying the action correctness of the improved protection system in different damage scenes of the capacitor unit. By improving the unbalance protection logic of the AC filter of the converter station, the protection cannot be operated by mistake when the fuse cannot be fused in a fault of a single capacitor element, and the operation reliability of equipment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of AC filter unbalance protection, and specifically to an improved method, device and storage medium for AC filter unbalance protection in a converter station. Background Art

[0002] As a key technology to solve the problem of uneven energy distribution in China, the safe and reliable operation of UHV DC transmission projects is of crucial importance. The AC filter field in the DC transmission system not only filters out harmonics but also compensates for the reactive power consumed by the DC system. Usually, the reactive power consumed by a converter station is between 40% and 60% of the rated transmission power. The AC filters equipped in UHV converter stations also have a relatively large capacity. Faults will threaten the stable operation of the DC system, and unbalance protection faults are the most common.

[0003] Regarding the impact of unbalance protection faults on converter stations, combined with the unbalance protection action cases of AC filter banks in converter stations, adaptive analysis and protection optimization analysis research work on capacitor bank unbalance protection are carried out from different angles. The current technology simulates breakdown faults from the perspective of overvoltage and explains the basic principles of setting unbalance protection values. However, it basically does not consider the difference between the rated voltage and the actual operating voltage of the project, and there is still a lack of work in combining design specifications with actual on-site operating conditions. Moreover, the actual on-site equipment operating conditions are complex and diverse. In recent years, the unbalance protection actions caused by single capacitor elements are typical cases, which seriously affect the safe and stable operation of the DC and reduce the availability of equipment.

[0004] Therefore, there is an urgent need for an improved method for AC filter unbalance protection in a converter station to solve the problem that the tripping of the entire capacitor bank is caused by the failure of 1 or a small number of capacitor elements in a single capacitor unit. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and design an improved method, device and storage medium for AC filter unbalance protection in a converter station, effectively avoiding the tripping situation caused by the inability of the internal fuse to blow in a single capacitor element failure, improving the reliability of equipment operation, and providing a reference for setting the unbalance protection of AC filters in in-service converter stations.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0007] In the first aspect, the present invention provides an improved method for AC filter unbalance protection in a converter station, including:

[0008] Determine the consistency between the rated voltage and the actual operating voltage of the capacitor element;

[0009] Calculate the reliable fusing energy of the internal fuse and determine whether the fuse can reliably fuse when a single capacitor unit fails;

[0010] Optimize the setting value of the unbalance section III protection;

[0011] Add the time-delay tripping logic for the unbalance protection section IV;

[0012] Verify the action correctness of the improved protection system under different damage scenarios of the capacitor unit.

[0013] As a further technical solution of the present invention, the determination of the consistency between the rated voltage and the actual operating voltage of the capacitor element specifically includes:

[0014] Determine the rated voltage of the AC filter according to the nameplate parameters of the capacitor element;

[0015] Collect the actual operating voltage by acquiring the operating voltage data of the AC filter field;

[0016] Compare whether the deviation between the rated voltage and the actual operating voltage exceeds the set threshold.

[0017] As a further technical solution of the present invention, the calculation of the reliable fusing energy of the internal fuse and the determination of whether the fuse can reliably fuse when a single capacitor unit fails specifically include:

[0018] Calculate the lower limit value of the energy required for the fuse of a single capacitor element to fuse:

[0019] Q1 = 0.5×67L×S;

[0020] In the formula, Q1 is the fusing energy of the fuse of a single capacitor element, L is the length of the fuse; S is the cross-sectional area of the fuse;

[0021] Calculate the fusing energy when a single element in a single capacitor unit fails;

[0022] Q2 = 0.5CU 2 ;

[0023] In the formula, Q2 is the fusing energy when a single capacitor element fails, C is the capacitance value of the capacitor element; U is the effective value of the voltage borne by the capacitor element;

[0024] When Q1 < Q2, it is determined that the fuse of the single capacitor unit cannot reliably fuse.

[0025] As a further technical solution of the present invention, the optimization of the setting value of the unbalance section III protection; specifically includes: changing the setting value of the unbalance section III protection from tripping when the number of faulty elements reaches 7 to tripping when the number of faulty elements reaches 8.

[0026] As a further technical solution of the present invention, the addition of the time-delay tripping logic for the unbalance protection section IV; includes:

[0027] When the unbalance coefficient is detected to be in the critical range of 7 - 8 damaged capacitor elements, start the delay timer;

[0028] Continuously monitor the unbalance coefficient during the delay time of the delay timer;

[0029] If the unbalance coefficient still satisfies the critical range of 7 - 8 damaged capacitor elements after the end of the delay time, trigger a trip signal.

[0030] Furthermore, the delay time of the delay timer is set to 7 seconds, and this duration ensures that the unfused fuse accumulates sufficient fusing energy.

[0031] As a further technical solution of the present invention, verifying the action correctness of the improved protection system under different damage scenarios of the capacitor unit includes:

[0032] When 1 - 7 capacitor monomers in the capacitor unit are damaged, the protection does not act;

[0033] When 8 - 14 capacitor monomers in the capacitor unit are damaged, it acts immediately or after a delay;

[0034] When 15 capacitor monomers in the capacitor unit are damaged, delay tripping is achieved through the logic of section IV.

[0035] In a second aspect, the present invention provides an improved device for unbalance protection of an AC filter in a converter station, including:

[0036] A data acquisition unit to determine the consistency between the rated voltage and the actual operating voltage of the capacitor element;

[0037] A fusing calculation unit to calculate the reliable fusing energy of the internal fuse and determine whether the fuse can reliably fuse when a single capacitor unit fails;

[0038] An optimization unit to optimize the setting value of the unbalance section III protection;

[0039] A delay control unit to add the delay tripping logic of the unbalance protection section IV;

[0040] A verification unit to verify the action correctness of the improved protection system under different damage scenarios of the capacitor unit.

[0041] In a third aspect, the present invention provides a computer - readable storage medium storing a computer program, characterized in that when the program is executed by a processor, the steps of an improved method for unbalance protection of an AC filter in a converter station are performed.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] Based on determining whether the rated voltage of the capacitor assembly is consistent with the actual operating voltage, the present invention improves the AC filter unbalance protection on the basis that the actual operating voltage of the capacitor assembly is consistent with the rated voltage. By calculating the reliable fusing energy of the capacitor assembly, it is judged whether the fuse can reliably fuse when a single capacitor in the capacitor unit fails; when the fuse cannot reliably fuse when a single capacitor fails, the setting value of the unbalance section III protection is optimized; and the time-delay tripping logic of the unbalance protection section IV is added; finally, the action correctness of the improved unbalance protection system under different damage scenarios of the capacitor unit is verified. By improving the unbalance protection logic of the AC filter in the converter station, the present invention realizes that the protection will not malfunction when the fuse cannot fuse within a single capacitor element failure, improving the reliability of equipment operation. Description of the Drawings

[0044] Figure 1 It is a flowchart of an improved method for AC filter unbalance protection proposed by the present invention;

[0045] Figure 2 It is a flowchart for determining the consistency between the rated voltage and the actual operating voltage of the capacitor element proposed by the present invention;

[0046] Figure 3 It is a series-parallel circuit topology diagram inside a capacitor assembly proposed by the present invention;

[0047] Figure 4 It is an equivalent circuit diagram of the capacitor assembly proposed by the present invention;

[0048] Figure 5 It is an improved unbalance section III protection logic diagram proposed by the present invention;

[0049] Figure 6 It is an added unbalance section IV protection logic diagram proposed by the present invention;

[0050] Figure 7 It is a structural diagram of an improved device for AC filter unbalance protection proposed by the present invention. Detailed Embodiments

[0051] The following describes the specific embodiments of the present invention in conjunction with the drawings and embodiments:

[0052] It should be noted that the structures, colors, ratios, sizes, etc. illustrated in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the implementable conditions of the present invention. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed by the present invention.

[0053] Meanwhile, terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear narration and are not used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationships shall also be regarded as the scope of implementation of the present invention without substantial change in technical content.

[0054] Aiming at the problems that the AC filter unbalance protection function in the converter station does not match the actual operating conditions on site, etc., the present invention solves the problems of misoperation of the protection when the internal fuse cannot be blown in the case of a single capacitor element failure and the inability to distinguish between the 3-string / 15-parallel structure caused by the internal fuse of a single capacitor element failure and the 3-string / 15-parallel structure caused by the actual damage of 1 string / 15 parallel by improving the setting threshold of the traditional unbalance III protection and adding the unbalance IV protection logic.

[0055] As Figure 1 shown, the present invention provides an improved method for AC filter unbalance protection in a converter station, including:

[0056] Step 101, determining the consistency between the rated voltage of the capacitor element and the actual operating voltage;

[0057] Step 102, calculating the reliable fusing energy of the internal fuse and judging whether the fuse can be reliably fused when a single capacitor unit fails;

[0058] Step 103, optimizing the setting value of the unbalance section III protection;

[0059] Step 104, adding the time-delay tripping logic of the unbalance protection section IV;

[0060] Step 105, verifying the action correctness of the improved protection system under different damage scenarios of the capacitor unit.

[0061] In the embodiment of the present invention, first, by selecting the actual operating voltage of the AC filter field and the voltage specified in the bidding technical specification, it is judged whether the two voltages are consistent; on the basis that the actual operating voltage of the capacitor assembly is consistent with the rated voltage, the AC filter unbalance protection is improved. By calculating the reliable fusing energy of the capacitor assembly, it is judged whether the fuse can be reliably fused when a single capacitor in the capacitor unit fails; when a single capacitor unit is damaged, it is calculated whether the series fuse energy can be reliably fused; when the fuse cannot be reliably fused when a single capacitor fails, the unbalance coefficient is calculated and the setting value of the unbalance protection section III of the AC filter bank is optimized; the tripping is changed from 7 elements breakdown to 8 elements breakdown to avoid misoperation of the protection; when 15 capacitors in the same group are damaged at the same time, the logic and setting value of the unbalance protection section IV of the AC filter bank are added to avoid refusal of the protection; finally, the action correctness of the improved unbalance protection system under different damage scenarios of the capacitor unit is verified.

[0062] The capacitor assembly of the AC filter unbalance protection of the converter station includes 4 groups of capacitor units. Each capacitor unit is composed of 15 capacitors in parallel, and each capacitor is connected in series with an internal fuse. See Figure 2 , by improving the AC filter unbalance protection logic of the converter station, the present invention realizes that when the internal fuse cannot be blown in case of a single capacitor element failure, the protection will not malfunction, thus improving the operation reliability of the equipment; by adding the unbalance section IV protection logic, the present invention realizes the purpose of distinguishing between the 3-series / 15-parallel structure caused by the failure of the internal fuse in a single capacitor element and the 3-series / 15-parallel structure caused by the actual damage of 1 series / 15 parallel, and avoids the problem that the extreme condition of 15 elements being damaged simultaneously cannot be recognized.

[0063] See Figure 3 , in step 101, to determine the consistency between the rated voltage of the capacitor element and the actual operating voltage, it specifically includes:

[0064] Step 111, determine the rated voltage of the AC filter according to the nameplate parameters of the capacitor element;

[0065] Step 112, collect the field operating voltage data of the AC filter to obtain the actual operating voltage;

[0066] Step 113, compare whether the deviation between the rated voltage and the actual operating voltage exceeds the set threshold.

[0067] The present invention determines the rated voltage of the AC filter according to the nameplate parameters of the capacitor element and the tender technical specification; collects the field operating voltage data of the AC filter of the converter station, analyzes and obtains the actual operating voltage; determines whether the rated operating voltage of the selected AC filter field of the converter station is consistent with the actual voltage.

[0068] In step 102, calculate the reliable fusing energy of the internal fuse and judge whether the fuse can be reliably blown when a single capacitor unit fails, specifically including:

[0069] Calculate the lower limit value of the energy required for the fuse of a single capacitor element to blow:

[0070] Q1 = 0.5×67L×S;

[0071] In the formula, Q1 is the fusing energy of the fuse of a single capacitor element, L is the length of the fuse; S is the cross-sectional area of the fuse;

[0072] Select the internal fuse model of the capacitor unit as CCP843Y6024, L = 152.4, S = 0.25. Then, the lower limit value Q1 of the energy required for the fuse of a single capacitor unit to blow is calculated as 169.67 J through the above formula.

[0073] Calculate the fusing energy when a single element in a single capacitor unit fails;

[0074] Q2 = 0.5CU 2 ;

[0075] Wherein, Q2 is the fusing energy for a single capacitor element failure, C is the capacitance value of the capacitor element; U is the effective value of the voltage borne by the capacitor element;

[0076] The capacitance of a single capacitor element is 9.426 μF, the operating range of the AC filter bus voltage is 775 - 790 kV, the voltage of a single capacitor is (447.46 - 456.12 kV) / 88 = 5.085 - 5.183 kV, and the voltage borne by a single capacitor element is calculated as (5.085 - 5.183 kV) / 4 = 1.2712 - 1.2958 kV.

[0077] By calculating the failure of a single element in a single capacitor unit of the converter station, the fusing energy Q2 is obtained as 106.62 J.

[0078] When Q1 < Q2, it is determined that the fuse of a single capacitor unit cannot be reliably fused. When the capacitor unit breaks down, the internal fuse cannot be reliably fused to play an isolation role.

[0079] In step 103, optimize the setting value of the unbalance section III protection; specifically including:

[0080] Calculated from step 102, the fusing energy of the internal fuse of a single capacitor unit does not reach the fusing energy, which will cause all 15 parallel capacitor elements to be short-circuited. At this time, the unbalance coefficient is greater than the unbalance coefficient when 7 units are damaged and less than the unbalance coefficient when 8 units are damaged, and the unbalance section III protection operates, resulting in misoperation of the protection.

[0081] Taking the capacitance values of each bridge arm of the upper bridge of the capacitor bank as an example, as Figure 4 shown, the upper bridge arms are C1 and C3 respectively; the lower bridge arms are C2 and C4 respectively, and the unbalance coefficient . Through Figure 2 the internal series-parallel structure of the capacitor assembly, the unbalance coefficients when each capacitor unit is damaged are calculated as shown in the following table:

[0082]

[0083] Now, modify the setting value of the unbalance section III protection from tripping immediately when the number of faulty capacitor elements reaches 7 to tripping immediately when the number of faulty capacitor elements reaches 8, so as to avoid the unbalance coefficient when the internal fuse of a single capacitor element cannot be fused. The modified unbalance section III protection logic is as Figure 5 shown.

[0084] In step 104, add the unbalance protection section IV delayed tripping logic; including:

[0085] When the unbalance coefficient is detected to be in the critical range where 7 - 8 units are damaged, start the delay timer;

[0086] Continuously monitor the unbalance coefficient during the delay time of the delay timer;

[0087] If the unbalance coefficient still meets the condition of being in the critical range where 7 - 8 units are damaged after the delay time ends, trigger the trip signal.

[0088] As can be seen from the optimized setting value of the third-stage unbalance protection in step 103, although the risk of misoperation of the protection when the internal fuse of a single capacitor element fails to blow is solved, it brings the risk of refusal of the short-circuit protection when 15 parallel capacitor units in the same group are damaged simultaneously with an extremely low probability. Therefore, the logic of the fourth stage of unbalance protection is designed to solve this problem. The logic of the fourth stage of unbalance protection includes: when the detected unbalance coefficient is greater than 7 and less than 8 capacitor units damaged, after a 7S delay, if this condition still holds, output the trip signal of the fourth stage of unbalance protection, otherwise reset. The added logic of the fourth stage of unbalance protection is as Figure 6 shown.

[0089] Among them, the delay time of the delay timer is set to 7 seconds, and this duration ensures that the unfused fuse accumulates enough fusing energy.

[0090] In step 105, verify the protection action conditions after different numbers of damaged capacitor units through the improved unbalance protection logic and setting values. Set the following scenarios:

[0091] Scenario 1: When 1 - 7 capacitor units are damaged, at this time the internal fuse blows / does not blow / partially blows, and the unbalance coefficient is less than the improved tripping coefficient, and the protection correctly does not operate.

[0092] Scenario 2: When 8 - 14 capacitor units are damaged, the internal fuse blows. At this time, the unbalance coefficient is greater than the improved tripping coefficient, and the protection correctly operates.

[0093] Scenario 3: When 8 - 14 capacitor units are damaged, the internal fuse does not blow / partially blows. At this time, the unbalance coefficient is less than the improved tripping coefficient, and the protection will not operate immediately. After a 7S delay, during this period, the fuse accumulates energy greater than the lower limit of the fusing energy, and the unfused internal fuse will blow. At this time, the unbalance coefficient is greater than the improved tripping coefficient, and the protection immediately operates.

[0094] Scenario 4: When 15 capacitor units are damaged, regardless of whether the internal fuse blows or not, at this time the unbalance coefficient is less than the improved tripping coefficient, and the protection will not operate immediately. After a 7S delay, during this period, the fuse accumulates energy greater than the lower limit of the fusing energy, and the unfused internal fuse will blow. At this time, the unbalance coefficient is greater than the improved tripping coefficient, and the protection immediately operates.

[0095] In combination with the application cases where the unbalance protection function does not match the actual engineering operation conditions, the present invention improves the unbalance protection method. By modifying the setting value of the third-stage unbalance protection from 7 trips of the faulty component to 8 trips, it can effectively avoid the situation where the internal fuse of a single capacitor component fails to melt during a fault. An additional fourth-stage unbalance protection logic is added to distinguish between the structure of 3 strings / 15 parallel units caused by the failure of the internal fuse of a single capacitor component and the structure of 3 strings / 15 parallel units actually damaged by 1 string / 15 parallel units, effectively avoiding the problem that the extreme condition of 15 components being damaged simultaneously cannot be recognized after the setting value is optimized, effectively improving the reliability of equipment operation, providing a reference for the setting of unbalance protection for AC filters in in-service converter stations, and having high application value.

[0096] Based on the actual case requirements of the unbalance protection for the AC filter field of UHV converter stations, the present invention improves the existing unbalance protection logic and setting values. The results show that the improved protection can avoid frequent misoperations of the unbalance protection, improve the availability of equipment, and ensure the safe and stable operation of AC filters.

[0097] See Figure 7 , the present invention provides an improved device for unbalance protection of AC filters in converter stations, including:

[0098] A data acquisition unit 201 to determine the consistency between the rated voltage and the actual operating voltage of the capacitor component;

[0099] A fuse melting calculation unit 202 to calculate the reliable melting energy of the internal fuse and judge whether the fuse can reliably melt when a single capacitor unit fails;

[0100] An optimization unit 203 to optimize the setting value of the third-stage unbalance protection;

[0101] A delay control unit 204 to add a fourth-stage unbalance protection delay tripping logic;

[0102] A verification unit 205 to verify the action correctness of the improved protection system under different damage scenarios of capacitor units.

[0103] The various change modes and specific examples of the method for discriminating the reliability of power grid monitoring alarm information in the foregoing embodiments are equally applicable to the device for discriminating the reliability of power grid monitoring alarm information in this embodiment. Through the foregoing detailed description of the method for discriminating the reliability of power grid monitoring alarm information, those skilled in the art can clearly know the device for discriminating the reliability of power grid monitoring alarm information in this embodiment. Therefore, for the sake of simplicity of the specification, it will not be elaborated herein.

[0104] In addition to the above methods and devices, embodiments of the present invention may also be computer program products, which include computer program instructions that, when run by a processor, cause the processor to execute the steps in the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above of this specification.

[0105] Furthermore, embodiments of the present invention may also be computer-readable storage media, on which computer program instructions are stored, and the computer program instructions, when run by a processor, cause the processor to execute the steps in the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above of this specification.

[0106] The computer-readable storage medium may adopt any combination of one or more readable media. The readable media may be a readable signal medium or a readable storage medium. The readable storage medium may, for example, include but is not limited to an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the readable storage medium include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0107] The basic principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, benefits, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, benefits, effects, etc. are essential for each embodiment of the present invention. Additionally, the specific details disclosed above are only for illustrative and easy-to-understand purposes and are not limitations. The above details do not limit the present invention to necessarily adopt the above specific details for implementation.

[0108] In addition, it should be understood that although this specification is described in accordance with embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment may also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An improved method for unbalance protection of AC filters in a converter station, characterized in that, Including: Determine the consistency between the rated voltage and the actual operating voltage of the capacitor element; Calculate the reliable fusing energy of the internal fuse and judge whether the fuse can reliably fuse when a single capacitor unit fails; Optimize the setting value of the unbalance section III protection; Add the time-delay tripping logic for the unbalance protection section IV; Verify the action correctness of the improved protection system under different damage scenarios of the capacitor unit.

2. An improved method for unbalance protection of AC filters in a converter station according to claim 1, characterized in that, The determination of the consistency between the rated voltage and the actual operating voltage of the capacitor element specifically includes: Determine the rated voltage of the AC filter according to the nameplate parameters of the capacitor element; Collect the operating voltage data of the AC filter field to obtain the actual operating voltage; Compare whether the deviation between the rated voltage and the actual operating voltage exceeds the set threshold.

3. An improved method for unbalance protection of AC filters in a converter station according to claim 1, characterized in that, The calculation of the reliable fusing energy of the internal fuse and the judgment of whether the fuse can reliably fuse when a single capacitor unit fails specifically includes: Calculate the lower limit of the energy required for the fuse of a single capacitor element to fuse: Q1 = 0.5×67L×S; In the formula, Q1 is the fusing energy of the fuse of a single capacitor element, L is the length of the fuse; S is the cross-sectional area of the fuse; Calculate the failure of a single element in a single capacitor unit to obtain the fusing energy; Q2 = 0.5CU 2 ; In the formula, Q2 is the fusing energy of a single capacitor element failure, C is the capacitance value of the capacitor element; U is the effective value of the voltage borne by the capacitor element; When Q1 < Q2, it is determined that the fuse of the single capacitor unit cannot reliably fuse.

4. An improved method for unbalance protection of AC filters in a converter station according to claim 1, characterized in that The optimization of the setting value of the unbalance section III protection; specifically includes: changing the tripping of the unbalance section III protection setting value from when 7 capacitor fault elements are reached to when 8 capacitor fault elements are reached.

5. An improved method for unbalance protection of AC filters in a converter station according to claim 1, characterized in that, The addition of the time-delay tripping logic for the unbalance protection section IV; includes: Start the time-delay timer when the detected unbalance coefficient is in the critical interval of 7 - 8 damaged capacitor elements; Continuously monitor the unbalance coefficient within the time delay of the time-delay timer; If the unbalance coefficient still satisfies the critical interval of 7 - 8 damaged capacitor elements after the time delay ends, trigger the tripping signal.

6. An improved method for unbalance protection of AC filters in a converter station according to claim 5, characterized in that, The time delay of the time-delay timer is set to 7 seconds.

7. An improved method for unbalance protection of AC filters in a converter station according to claim 1, characterized in that, The verification of the action correctness of the improved protection system under different damage scenarios of the capacitor unit includes: The protection does not act when 1 - 7 capacitor monomers in the capacitor unit are damaged; The protection acts immediately or after a time delay when 8 - 14 capacitor monomers in the capacitor unit are damaged; When 15 capacitor monomers in the capacitor unit are damaged, time-delay tripping is achieved through the section IV logic.

8. An improved device for unbalance protection of AC filters in a converter station, characterized in that, Adopt an improved method for unbalance protection of the AC filter in a converter station as described in any one of claims 1 - 7, including: A data acquisition unit to determine the consistency between the rated voltage and the actual operating voltage of the capacitor element; A fusing calculation unit to calculate the reliable fusing energy of the internal fuse and judge whether the fuse can reliably fuse when a single capacitor unit fails; An optimization unit to optimize the setting value of the unbalance section III protection; A time-delay control unit to add the time-delay tripping logic for the unbalance protection section IV; A verification unit to verify the action correctness of the improved protection system under different damage scenarios of the capacitor unit.

9. A computer-readable storage medium storing a computer program, characterized in that, When the program is executed by the processor, the steps of an improved method for unbalance protection of the AC filter in a converter station as described in any one of claims 1 - 7 are implemented.

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