Single-phase earth fault position judgment method and system, terminal equipment and storage medium

Abstract

The invention discloses a single-phase earth fault position judgment method and system, terminal equipment and a storage medium. The method comprises the following steps: acquiring an alternating-current side phase voltage, an alternating-current side phase current, a direct-current side voltage and a direct-current side current signal of a current converter end; calculating according to the direct-current side current signal to obtain a fundamental component and a direct-current component at the direct-current side connecting neutral bus of the current converter end; judging whether a fundamental component condition is met or not according to the fundamental component and a preset fundamental component threshold value, and obtaining a first judgment result; judging whether a direct current component condition is met or not according to the alternating current side phase voltage, the alternating current side phase current, the direct current side voltage and the direct current component to obtain a second judgment result; obtaining a current converter end fault judgment result and an opposite-side converter fault judgment result according to the first judgment result and the second judgment result; and performing grounding protection action according to the current converter end fault judgment result and the opposite-side converter fault judgment result. According to the invention, the efficiency of protection action is improved.

Description

Technical Field

[0001] The present invention relates to the field of power systems and related technical fields, and in particular to a method, system, terminal equipment and storage medium for determining the location of a single-phase grounding fault. Background Art

[0002] In the flexible DC transmission system based on modular multilevel converter (MMC), the bipolar wiring method is widely used due to its high efficiency and reliability. This wiring method allows the zero potential reference point to be directly drawn from the DC neutral bus, which facilitates the stable operation of the system. When a single-phase grounding fault occurs on the threshold side of any end of the system, a DC component will appear in the AC current at the fault end, the AC current at the non-fault end on the opposite side will decrease, and the DC component of the bridge arm current will disappear. It is necessary to quickly identify the location of the single-phase grounding fault on the threshold side of the flexible DC system, so as to eliminate the short-circuit current impact and bridge arm overvoltage of the flexible DC system, so as not to affect the safe operation of the entire DC power grid.

[0003] The existing conventional protection strategy for single-phase grounding faults on the threshold side of bipolar flexible DC systems focuses on the identification of the fault end. Generally, differential protection is used at the fault end, and the signal is transmitted to the non-fault end through communication equipment so that the non-fault end protection can cooperate to remove the fault. Considering that the transmission of signals from the fault end to the non-fault end by communication equipment is affected by the environment and takes a certain amount of time, it is impossible to quickly identify the fault location and thus the non-fault end protection cannot act quickly. Summary of the invention

[0004] The embodiments of the present invention provide a single-phase grounding fault location determination method, system, terminal device and storage medium, which can effectively solve the problem that the prior art cannot quickly identify the fault location and thus cannot enable the non-fault end protection to act quickly.

[0005] An embodiment of the present invention provides a single-phase grounding fault location determination method, which is applicable to a converter of a single-phase grounding fault location determination system; the single-phase grounding fault location determination system comprises a plurality of converters; the DC side of the converter is connected to a neutral bus;

[0006] The method for determining the position of a single-phase grounding fault comprises:

[0007] Obtaining the AC side phase voltage, AC side phase current, DC side voltage and DC side current signals at the current converter end;

[0008] Perform Fourier calculation according to the DC side current signal to obtain a fundamental frequency component and a DC component at the DC side of the current converter end connected to the neutral bus;

[0009] According to the fundamental frequency component and a preset fundamental frequency component threshold, determining whether a fundamental frequency component condition is met, and obtaining a first determination result;

[0010] Determine whether a DC component condition is met according to the AC side phase voltage, the AC side phase current, the DC side voltage, and the DC component, and obtain a second determination result;

[0011] According to the first judgment result and the second judgment result, obtaining a current converter-side fault judgment result and an opposite-side converter fault judgment result;

[0012] The ground protection action is performed according to the fault judgment result of the current converter end and the fault judgment result of the opposite converter end.

[0013] Furthermore, the single-phase grounding fault location determination system is a bipolar topology, DC side neutral bus grounding system;

[0014] The AC side of the converter of the single-phase ground fault location judgment system is connected to the AC power grid through a converter transformer; the DC side of the converter is connected to the primary side of the current transformer at the neutral bus; the secondary side of the current transformer is connected to the relay protection device;

[0015] The converter transformer is used for power conversion and power transmission with the AC power grid;

[0016] The AC power grid is used to provide power supply;

[0017] The current transformer is used for current measurement and relay protection;

[0018] The primary side of the current transformer is used to transmit the high current to the secondary side of the current transformer;

[0019] The secondary side of the current transformer is used to convert the high current on the primary side into a low current used by the load;

[0020] The relay protection device is used to cut off faults.

[0021] Furthermore, the calculation of the fundamental frequency component threshold includes:

[0022] Determine the DC side neutral bus current value according to the DC side current signal;

[0023] The fundamental frequency component threshold is calculated according to the DC side neutral bus current value and a preset ratio.

[0024] Further, the first judgment result includes: satisfying the fundamental frequency component condition and not satisfying the fundamental frequency component condition;

[0025] According to the fundamental frequency component and a preset fundamental frequency component threshold, determining whether a fundamental frequency component condition is met, and obtaining a first determination result, including:

[0026] Comparing the fundamental frequency component with a preset fundamental frequency component threshold;

[0027] In the case where the fundamental frequency component is greater than a preset fundamental frequency component threshold, determining that the first judgment result satisfies the fundamental frequency component condition;

[0028] In a case where the fundamental frequency component is not greater than a preset fundamental frequency component threshold, it is determined that the first judgment result is that the fundamental frequency component condition is not met.

[0029] Further, the second judgment result includes: satisfying the DC component condition and not satisfying the DC component condition;

[0030] According to the AC side phase voltage, the AC side phase current, the DC side voltage, and the DC component, it is determined whether a DC component condition is met to obtain a second determination result, including:

[0031] Calculating a DC component judgment value according to the AC side phase voltage, the AC side phase current, the DC side voltage and a preset current reliability coefficient;

[0032] Comparing according to the DC component and the DC component judgment value;

[0033] In a case where the DC component is less than the DC component judgment value, determining that the second judgment result satisfies the DC component condition;

[0034] In a case where the DC component is not less than the DC component judgment value, it is determined that the second judgment result is that the DC component condition is not satisfied.

[0035] Further, according to the first judgment result and the second judgment result, a current converter-side fault judgment result and an opposite-side converter fault judgment result are obtained, including:

[0036] When the first judgment result satisfies the fundamental frequency component condition and the second judgment result satisfies the DC component condition, it is determined that the current converter valve side is a non-fault position and the opposite converter valve side is a ground fault position;

[0037] When the first judgment result is that the fundamental frequency component condition is satisfied, and the second judgment result is that the DC component condition is not satisfied, determining that the current converter valve side is a ground fault position, and the opposite converter valve side is a non-fault position;

[0038] When the first judgment result is that the fundamental frequency component condition is not satisfied, and the second judgment result is that the DC component condition is satisfied, it is determined that the current converter valve side is a non-fault position, the opposite converter valve side is a non-fault position, and, except for the current converter valve side and the opposite converter valve side, other valve sides have ground faults;

[0039] When the first judgment result is that the fundamental frequency component condition is not satisfied, and the second judgment result is that the DC component condition is not satisfied, it is determined that the current converter valve side is a non-fault position, and the opposite converter valve side is a non-fault position.

[0040] As an improvement of the above solution, another embodiment of the present invention provides a single-phase ground fault location determination device, comprising a plurality of converters; the DC side of the converter is connected to a neutral bus;

[0041] The single-phase grounding fault position determination system comprises:

[0042] The system data acquisition module is used to obtain the AC side phase voltage, AC side phase current, DC side voltage and DC side current signals at the current converter end;

[0043] A component calculation module, used for performing Fourier calculation according to the DC side current signal to obtain a fundamental frequency component and a DC component at the DC side of the current converter end connected to the neutral bus;

[0044] A first judgment module, used to judge whether a fundamental frequency component condition is met according to the fundamental frequency component and a preset fundamental frequency component threshold, and obtain a first judgment result;

[0045] A second judgment module is used to judge whether a DC component condition is met according to the AC side phase voltage, the AC side phase current, the DC side voltage and the DC component, and obtain a second judgment result;

[0046] A fault result determination module, used for obtaining a current converter-side fault determination result and an opposite-side converter fault determination result according to the first determination result and the second determination result;

[0047] The system protection module is used to perform grounding protection action according to the current converter-side fault judgment result and the opposite-side converter fault judgment result.

[0048] Furthermore, the single-phase grounding fault location determination system is a bipolar topology, DC side neutral bus grounding system;

[0049] The AC side of the converter of the single-phase ground fault location judgment system is connected to the AC power grid through a converter transformer; the DC side of the converter is connected to the primary side of the current transformer at the neutral bus; the secondary side of the current transformer is connected to the relay protection device;

[0050] The converter transformer is used for power conversion and power transmission with the AC power grid;

[0051] The AC power grid is used to provide power supply;

[0052] The current transformer is used for current measurement and relay protection;

[0053] The primary side of the current transformer is used to transmit the high current to the secondary side of the current transformer;

[0054] The secondary side of the current transformer is used to convert the high current on the primary side into a low current used by the load;

[0055] The relay protection device is used to cut off faults.

[0056] Another embodiment of the present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, a single-phase ground fault location determination method as described in the above embodiment is implemented.

[0057] Another embodiment of the present invention provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute a single-phase grounding fault location determination method described in the above embodiment.

[0058] By implementing the present invention, at least the following beneficial effects are achieved:

[0059] The present invention provides a single-phase grounding fault position determination method, system, terminal equipment and storage medium, wherein the method is applicable to a converter of a single-phase grounding fault position determination system; the single-phase grounding fault position determination system comprises a plurality of converters; the DC side of the converter is connected to a neutral bus; the method can obtain the AC side phase voltage, AC side phase current, DC side voltage and DC side current signals of the current converter end; perform Fourier calculation according to the DC side current signal to obtain the fundamental frequency component and DC component at the DC side of the current converter end connected to the neutral bus; determine whether the fundamental frequency component condition is met according to the fundamental frequency component and a preset fundamental frequency component threshold value, and obtain a first determination result; determine whether the DC component condition is met according to the AC side phase voltage, AC side phase current, DC side voltage and the DC component, and obtain a second determination result; determine the current converter end fault determination result and the opposite converter fault determination result according to the first determination result and the second determination result; perform grounding protection action according to the current converter end fault determination result and the opposite converter fault determination result. By collecting the DC side current signal at the current converter end and calculating the fundamental frequency component and the DC component, it is possible to determine whether a single-phase grounding fault has occurred in the converter on the current side and the opposite side based on the fundamental frequency component and the DC component. There is no need to communicate from the fault end to the non-fault end to implement protection action. The fault judgment results on the current side and the opposite side can be obtained directly, thereby improving the fault location identification on the current side and the opposite side on the system valve side and improving the efficiency of implementing protection actions. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a flow chart of a method for determining the location of a single-phase grounding fault provided by an embodiment of the present invention;

[0061] Figure 2 It is a schematic diagram of the installation of a protection device for a method for determining the location of a single-phase grounding fault provided by an embodiment of the present invention;

[0062] Figure 3 It is a judgment logic diagram of a method for judging the location of a single-phase grounding fault provided by an embodiment of the present invention;

[0063] Figure 4 It is a structural schematic diagram of a single-phase grounding fault location determination system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0065] See also Figure 1 , is a flow chart of a method for determining the location of a single-phase grounding fault provided by an embodiment of the present invention, the method is applicable to a converter of a single-phase grounding fault location determination system; the single-phase grounding fault location determination system comprises a plurality of converters; the DC side of the converter is connected to a neutral bus; the method comprises:

[0066] S1, obtaining the AC side phase voltage, AC side phase current, DC side voltage and DC side current signals at the current converter end;

[0067] Specifically, the single-phase grounding fault location determination system includes a two-terminal or multi-terminal flexible DC transmission network with several large-capacity converters, and the system is a bipolar topology and DC-side neutral bus grounding system. The current AC-side phase voltage at the converter end is U v , the AC side phase current is I v , the DC side voltage is U dc .

[0068] In a preferred embodiment of the present invention, the single-phase ground fault location judgment system is a bipolar topology, DC side neutral bus grounding system; the AC side of the converter of the single-phase ground fault location judgment system is connected to the AC power grid through a converter transformer; the DC side of the converter is connected to the primary side of the current transformer at the neutral bus; the secondary side of the current transformer is connected to the relay protection device; the converter transformer is used to perform power conversion and power transmission with the AC power grid; the AC power grid is used to provide power supply; the current transformer is used for current measurement and relay protection; the primary side of the current transformer is used to transmit high current to the secondary side of the current transformer; the secondary side of the current transformer is used to convert the high current of the primary side into a low current used by the load; the relay protection device is used to cut off the fault. When the current transformer is working, it converts the large current on the primary side into a small current on the secondary side for measurement. In order to facilitate measurement, protection and control, the current needs to be converted into a uniform amount, and this connection can achieve electrical isolation.

[0069] S2, performing Fourier calculation according to the DC side current signal to obtain the fundamental frequency component and the DC component at the DC side of the current converter end connected to the neutral bus;

[0070] Specifically, a current transformer is installed at the neutral busbar on the DC side of the converter to sample the DC side current signal, and then the DC side current signal is subjected to Fourier calculation to obtain the fundamental frequency component I at the DC side of the current j-th converter end connected to the neutral busbar. gnd1 And the DC component I gnd0 The Fourier algorithm is to filter out various frequency components in a continuous signal through Fourier transform.

[0071] S3. judging whether a fundamental frequency component condition is met according to the fundamental frequency component and a preset fundamental frequency component threshold, and obtaining a first judgment result;

[0072] Preferably, the calculation of the fundamental frequency component threshold comprises:

[0073] Determine the DC side neutral bus current value according to the DC side current signal;

[0074] The fundamental frequency component threshold is calculated according to the DC side neutral bus current value and a preset ratio.

[0075] In a preferred embodiment of the present invention, the fundamental frequency component threshold ε is 1%<ε<10% of the neutral bus current on the DC side under normal operation, that is, ε is the maximum measurement error of the current at the neutral bus on the DC side under normal operation.

[0076] Specifically, the first judgment result includes: satisfying the fundamental frequency component condition and not satisfying the fundamental frequency component condition;

[0077] According to the fundamental frequency component and a preset fundamental frequency component threshold, determining whether a fundamental frequency component condition is met, and obtaining a first determination result, including:

[0078] Comparing the fundamental frequency component with a preset fundamental frequency component threshold;

[0079] In the case where the fundamental frequency component is greater than a preset fundamental frequency component threshold, determining that the first judgment result satisfies the fundamental frequency component condition;

[0080] In a case where the fundamental frequency component is not greater than a preset fundamental frequency component threshold, it is determined that the first judgment result is that the fundamental frequency component condition is not met.

[0081] In a preferred embodiment of the present invention, it is determined whether the fundamental frequency component condition is satisfied, that is, it is determined whether the fundamental frequency component is greater than a preset fundamental frequency component threshold value. In other words, it is determined whether the fundamental frequency component of the current at the neutral bus on the DC side of the converter is too large, that is: |I gnd1 |>ε. In the case where the fundamental frequency component is greater than the preset fundamental frequency component threshold, that is, |I gnd1|>ε, it is determined that the first judgment result satisfies the fundamental frequency component condition; when the fundamental frequency component is not greater than the preset fundamental frequency component threshold, that is, |I gnd1 |≤ε, it is determined that the first judgment result does not meet the fundamental frequency component condition.

[0082] S4. Determine whether a DC component condition is met according to the AC side phase voltage, the AC side phase current, the DC side voltage, and the DC component, and obtain a second determination result;

[0083] Specifically, the second judgment result includes: satisfying the DC component condition and not satisfying the DC component condition;

[0084] According to the AC side phase voltage, the AC side phase current, the DC side voltage, and the DC component, it is determined whether a DC component condition is met to obtain a second determination result, including:

[0085] Calculating a DC component judgment value according to the AC side phase voltage, the AC side phase current, the DC side voltage and a preset current reliability coefficient;

[0086] Comparing according to the DC component and the DC component judgment value;

[0087] In a case where the DC component is less than the DC component judgment value, determining that the second judgment result satisfies the DC component condition;

[0088] In a case where the DC component is not less than the DC component judgment value, it is determined that the second judgment result is that the DC component condition is not satisfied.

[0089] In a preferred embodiment of the present invention, it is determined whether the DC component condition is satisfied, that is, it is determined whether the DC component is less than the DC component judgment value. In other words, it is determined whether the DC component of the current at the neutral busbar connected to the DC side of the converter is too small, that is: |I gnd0 |<kI set2 , The preset current reliability coefficient k ranges from 0<k<1. The DC component judgment value < kI is calculated based on the AC side phase voltage, the AC side phase current, the DC side voltage and the preset current reliability coefficient. set2 , according to the DC component and the DC component judgment value. In the case where the DC component is less than the DC component judgment value, that is, |I gnd0 |<kI set2 , determine that the second judgment result satisfies the DC component condition; when the DC component is not less than the DC component judgment value, that is, |I gnd0 |≥kI set2, determine that the second judgment result does not meet the DC component condition.

[0090] S5. Obtaining a current converter-side fault judgment result and an opposite-side converter fault judgment result according to the first judgment result and the second judgment result;

[0091] Specifically, according to the first judgment result and the second judgment result, obtaining the current converter end fault judgment result and the opposite converter fault judgment result includes:

[0092] When the first judgment result satisfies the fundamental frequency component condition and the second judgment result satisfies the DC component condition, it is determined that the current converter valve side is a non-fault position and the opposite converter valve side is a ground fault position;

[0093] When the first judgment result is that the fundamental frequency component condition is satisfied, and the second judgment result is that the DC component condition is not satisfied, determining that the current converter valve side is a ground fault position, and the opposite converter valve side is a non-fault position;

[0094] When the first judgment result is that the fundamental frequency component condition is not satisfied, and the second judgment result is that the DC component condition is satisfied, it is determined that the current converter valve side is a non-fault position, the opposite converter valve side is a non-fault position, and, except for the current converter valve side and the opposite converter valve side, other valve sides have ground faults;

[0095] When the first judgment result is that the fundamental frequency component condition is not satisfied, and the second judgment result is that the DC component condition is not satisfied, it is determined that the current converter valve side is a non-fault position, and the opposite converter valve side is a non-fault position.

[0096] In a preferred embodiment of the present invention, when |I gnd1 |>ε and |I gnd0 |<kI set2 When both conditions are met, it is determined that the i-th converter valve side is in a non-fault position and the opposite converter valve side is in a single-phase grounding fault position. gnd1 |≤ε and |I gnd0 |≥kI set2 When |I gnd1 |>ε and |I gnd0 |≥kI set2 When |I gnd1 |≤ε and |I gnd0 |<kI set2 When the current converter side and the opposite converter are operating normally, a ground fault occurs on the AC side of the other end valve. gnd1 |≤ε and |I gnd0 |<kI set2When MMC1 on the front side and MMC3 on the opposite side are operating normally, MMC2 or MMC4 on the other side has a ground fault. Figure 2 As shown, MMC1 and MMC3 are on opposite sides of each other, and similarly, MMC2 and MMC4 are on opposite sides of each other.

[0097] S6. Perform ground protection action according to the current converter-side fault judgment result and the opposite-side converter fault judgment result.

[0098] In a preferred embodiment of the present invention, the protection logic is as follows Figure 3 As shown in Figure 1, when no single-phase grounding fault occurs on the valve side of all converters in the two-terminal or multi-terminal flexible DC grid, the fundamental frequency component of the current at the neutral bus on the DC side is zero, and the amplitude of the fundamental frequency component of the current at the neutral bus on the DC side calculated by the relay protection is |I gnd1 | will not be greater than the maximum measurement error, and its DC component always exists and is greater than the setting value, so the protection will not make a misjudgment. When a single-phase grounding fault occurs on the valve side of other ends except the converter on the opposite side, the operating state of this side is not affected by the fault. Similar to the above situation, the fundamental frequency component amplitude of the current at the neutral busbar on the DC side calculated by the relay protection |I gnd1 | will not be greater than the maximum measurement error, the DC component always exists and is greater than the set value, and the protection will not be misjudged. When a single-phase grounding fault occurs on the valve side of the converter on this side, the neutral bus grounding point on the DC side forms a short-circuit path with the fault point, and a short-circuit current flows through the neutral bus on the DC side of the converter, which is equal to the sum of the currents of the non-fault phase bridge arms of the converter. At this time, the fundamental frequency component of the current on the neutral bus on the DC side exists, and its amplitude |I gnd1 | will be greater than the maximum measurement error, but the DC component of the current at the neutral busbar on the DC side is too large and greater than the set value, so the protection will not misjudge. When a single-phase grounding fault occurs on the valve side of the converter on the opposite side, a fundamental frequency component appears in the current at the neutral busbar on the DC side of the converter on this side, and its amplitude |I gnd1 |It is related to the system angular frequency, bridge arm inductance, submodule capacitance, and AC line voltage, but is always greater than the maximum measurement error. Due to the reduction of DC power on the line, the DC component of the current at the neutral bus on the DC side of the converter is smaller, so the protection can operate correctly.

[0099] By implementing this embodiment, the AC side phase voltage, AC side phase current, DC side voltage and DC side current signals of the current converter end are obtained; Fourier calculation is performed based on the DC side current signal to obtain the fundamental frequency component and DC component at the neutral bus of the DC side of the current converter end; based on the fundamental frequency component and the preset fundamental frequency component threshold, it is judged whether the fundamental frequency component condition is met to obtain a first judgment result; based on the AC side phase voltage, AC side phase current, DC side voltage and the DC component, it is judged whether the DC component condition is met to obtain a second judgment result; based on the first judgment result and the second judgment result, the current converter end fault judgment result and the opposite side converter fault judgment result are obtained; based on the current converter end fault judgment result and the opposite side converter fault judgment result, a grounding protection action is performed. By collecting the DC side current signal at the current converter end and calculating the fundamental frequency component and the DC component, it is possible to determine whether a single-phase grounding fault has occurred in the converter on the current side and the opposite side based on the fundamental frequency component and the DC component. There is no need to communicate from the fault end to the non-fault end to implement protection action. The fault judgment results on the current side and the opposite side can be obtained directly, thereby improving the fault location identification on the current side and the opposite side on the system valve side and improving the efficiency of implementing protection actions.

[0100] See also Figure 4 , is a structural diagram of a single-phase grounding fault location determination system provided by an embodiment of the present invention, comprising:

[0101] The system data acquisition module is used to obtain the AC side phase voltage, AC side phase current, DC side voltage and DC side current signals at the current converter end;

[0102] A component calculation module, used for performing Fourier calculation according to the DC side current signal to obtain a fundamental frequency component and a DC component at the DC side of the current converter end connected to the neutral bus;

[0103] A first judgment module, used to judge whether a fundamental frequency component condition is met according to the fundamental frequency component and a preset fundamental frequency component threshold, and obtain a first judgment result;

[0104] A second judgment module is used to judge whether a DC component condition is met according to the AC side phase voltage, the AC side phase current, the DC side voltage and the DC component, and obtain a second judgment result;

[0105] A fault result determination module, used for obtaining a current converter-side fault determination result and an opposite-side converter fault determination result according to the first determination result and the second determination result;

[0106] The system protection module is used to perform grounding protection action according to the current converter-side fault judgment result and the opposite-side converter fault judgment result.

[0107] Specifically, the system includes a plurality of converters; the DC side of the converters is connected to a neutral bus;

[0108] The single-phase grounding fault location determination system is a bipolar topology, DC side neutral bus grounding system;

[0109] The AC side of the converter of the single-phase ground fault location judgment system is connected to the AC power grid through a converter transformer; the DC side of the converter is connected to the primary side of the current transformer at the neutral bus; the secondary side of the current transformer is connected to the relay protection device;

[0110] The converter transformer is used for power conversion and power transmission with the AC power grid;

[0111] The AC power grid is used to provide power supply;

[0112] The current transformer is used for current measurement and relay protection;

[0113] The primary side of the current transformer is used to transmit the high current to the secondary side of the current transformer;

[0114] The secondary side of the current transformer is used to convert the high current on the primary side into a low current used by the load;

[0115] The relay protection device is used to cut off faults.

[0116] The present invention provides a single-phase grounding fault position judgment system, which obtains the AC side phase voltage, AC side phase current, DC side voltage and DC side current signals of the current converter end according to the system data acquisition module; in the component calculation module, Fourier calculation is performed according to the DC side current signal to obtain the fundamental frequency component and DC component at the neutral bus of the DC side of the current converter end; in the first judgment module, according to the fundamental frequency component and a preset fundamental frequency component threshold, it is judged whether the fundamental frequency component condition is met to obtain a first judgment result; in the second judgment module, according to the AC side phase voltage, AC side phase current, DC side voltage and the DC component, it is judged whether the DC component condition is met to obtain a second judgment result; through the fault result determination module, according to the first judgment result and the second judgment result, the current converter end fault judgment result and the opposite side converter fault judgment result are obtained; finally, in the system protection module, according to the current converter end fault judgment result and the opposite side converter fault judgment result, a grounding protection action is performed. By collecting the DC side current signal at the current converter end and calculating the fundamental frequency component and the DC component, it is possible to determine whether a single-phase grounding fault has occurred in the converter on the current side and the opposite side based on the fundamental frequency component and the DC component. There is no need to communicate from the fault end to the non-fault end to implement protection action. The fault judgment results on the current side and the opposite side can be obtained directly, thereby improving the fault location identification on the current side and the opposite side on the system valve side and improving the efficiency of implementing protection actions.

[0117] It should be noted that the system embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the drawings of the system embodiment provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines. A person of ordinary skill in the art may understand and implement it without paying any creative effort.

[0118] Those skilled in the art can clearly understand that, for the sake of convenience and brevity, the specific working process of the system described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0119] Another embodiment of the present invention further provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor implements a single-phase ground fault location determination method as described in the above embodiment when executing the computer program. The terminal device may be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The terminal device may include, but is not limited to, a processor and a memory.

[0120] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the terminal device, and uses various interfaces and lines to connect various parts of the entire terminal device.

[0121] The memory can be used to store the computer program, and the processor realizes various functions of the terminal device by running or executing the computer program stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required for a function, etc.; the data storage area can store data created according to the use of the mobile phone, etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device or other volatile solid-state storage device.

[0122] Another embodiment of the present invention provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute a single-phase grounding fault location determination method described in the above embodiment.

[0123] The storage medium is a computer-readable storage medium, and the computer program is stored in the computer-readable storage medium. When the computer program is executed by the processor, the steps of each of the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium.

[0124] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for determining the location of a single-phase grounding fault, characterized in that: A converter suitable for a single-phase ground fault location determination system; the single-phase ground fault location determination system comprises a plurality of converters; the DC side of the converter is connected to a neutral bus; The method for determining the position of a single-phase grounding fault comprises: Obtaining the AC side phase voltage, AC side phase current, DC side voltage and DC side current signals at the current converter end; Perform Fourier calculation according to the DC side current signal to obtain a fundamental frequency component and a DC component at the DC side of the current converter end connected to the neutral bus; According to the fundamental frequency component and a preset fundamental frequency component threshold, determining whether a fundamental frequency component condition is met, and obtaining a first determination result; Determine whether a DC component condition is met according to the AC side phase voltage, the AC side phase current, the DC side voltage, and the DC component, and obtain a second determination result; According to the first judgment result and the second judgment result, obtaining a current converter-side fault judgment result and an opposite-side converter fault judgment result; The ground protection action is performed according to the fault judgment result of the current converter end and the fault judgment result of the opposite converter end.

2. A method for determining the location of a single-phase grounding fault according to claim 1, characterized in that: The single-phase grounding fault location determination system is a bipolar topology, DC side neutral bus grounding system; The AC side of the converter of the single-phase ground fault location judgment system is connected to the AC power grid through a converter transformer; the DC side of the converter is connected to the primary side of the current transformer at the neutral bus; the secondary side of the current transformer is connected to the relay protection device; The converter transformer is used for power conversion and power transmission with the AC power grid; The AC power grid is used to provide power supply; The current transformer is used for current measurement and relay protection; The primary side of the current transformer is used to transmit the high current to the secondary side of the current transformer; The secondary side of the current transformer is used to convert the high current on the primary side into a low current used by the load; The relay protection device is used to cut off faults.

3. A method for determining the location of a single-phase grounding fault according to claim 1, characterized in that: The calculation of the fundamental frequency component threshold comprises: Determine the DC side neutral bus current value according to the DC side current signal; The fundamental frequency component threshold is calculated according to the DC side neutral bus current value and a preset ratio.

4. A method for determining the location of a single-phase grounding fault according to claim 1, characterized in that: The first judgment result includes: satisfying the fundamental frequency component condition and not satisfying the fundamental frequency component condition; According to the fundamental frequency component and a preset fundamental frequency component threshold, determining whether a fundamental frequency component condition is met, and obtaining a first determination result, including: Comparing the fundamental frequency component with a preset fundamental frequency component threshold; In the case where the fundamental frequency component is greater than a preset fundamental frequency component threshold, determining that the first judgment result satisfies the fundamental frequency component condition; In a case where the fundamental frequency component is not greater than a preset fundamental frequency component threshold, it is determined that the first judgment result is that the fundamental frequency component condition is not met.

5. A method for determining the location of a single-phase grounding fault according to claim 1, characterized in that: The second judgment result includes: satisfying the DC component condition and not satisfying the DC component condition; According to the AC side phase voltage, the AC side phase current, the DC side voltage, and the DC component, it is determined whether a DC component condition is met to obtain a second determination result, including: Calculating a DC component judgment value according to the AC side phase voltage, the AC side phase current, the DC side voltage and a preset current reliability coefficient; Comparing according to the DC component and the DC component judgment value; In a case where the DC component is less than the DC component judgment value, determining that the second judgment result satisfies the DC component condition; In a case where the DC component is not less than the DC component judgment value, it is determined that the second judgment result is that the DC component condition is not satisfied.

6. A method for determining the location of a single-phase grounding fault according to claim 1, characterized in that: According to the first judgment result and the second judgment result, a current converter-side fault judgment result and an opposite-side converter fault judgment result are obtained, including: When the first judgment result satisfies the fundamental frequency component condition and the second judgment result satisfies the DC component condition, it is determined that the current converter valve side is a non-fault position and the opposite converter valve side is a ground fault position; When the first judgment result is that the fundamental frequency component condition is satisfied, and the second judgment result is that the DC component condition is not satisfied, determining that the current converter valve side is a ground fault position, and the opposite converter valve side is a non-fault position; When the first judgment result is that the fundamental frequency component condition is not satisfied, and the second judgment result is that the DC component condition is satisfied, it is determined that the current converter valve side is a non-fault position, the opposite converter valve side is a non-fault position, and, except for the current converter valve side and the opposite converter valve side, other valve sides have ground faults; When the first judgment result is that the fundamental frequency component condition is not satisfied, and the second judgment result is that the DC component condition is not satisfied, it is determined that the current converter valve side is a non-fault position, and the opposite converter valve side is a non-fault position.

7. A single-phase grounding fault location determination system, characterized in that: It includes several converters; the DC side of the converters is connected to the neutral bus; The single-phase grounding fault position determination system comprises: The system data acquisition module is used to obtain the AC side phase voltage, AC side phase current, DC side voltage and DC side current signals at the current converter end; A component calculation module, used for performing Fourier calculation according to the DC side current signal to obtain a fundamental frequency component and a DC component at the DC side of the current converter end connected to the neutral bus; A first judgment module, used to judge whether a fundamental frequency component condition is met according to the fundamental frequency component and a preset fundamental frequency component threshold, and obtain a first judgment result; A second judgment module is used to judge whether a DC component condition is met according to the AC side phase voltage, the AC side phase current, the DC side voltage and the DC component, and obtain a second judgment result; A fault result determination module, used for obtaining a current converter-side fault determination result and an opposite-side converter fault determination result according to the first determination result and the second determination result; The system protection module is used to perform grounding protection action according to the current converter-side fault judgment result and the opposite-side converter fault judgment result.

8. A single-phase grounding fault location determination system as claimed in claim 7, characterized in that: The single-phase grounding fault location determination system is a bipolar topology, DC side neutral bus grounding system; The AC side of the converter of the single-phase ground fault location judgment system is connected to the AC power grid through a converter transformer; the DC side of the converter is connected to the primary side of the current transformer at the neutral bus; the secondary side of the current transformer is connected to the relay protection device; The converter transformer is used for power conversion and power transmission with the AC power grid; The AC power grid is used to provide power supply; The current transformer is used for current measurement and relay protection; The primary side of the current transformer is used to transmit the high current to the secondary side of the current transformer; The secondary side of the current transformer is used to convert the high current on the primary side into a low current used by the load; The relay protection device is used to cut off faults.

9. A terminal device, characterized in that: It comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the processor executes the computer program, it implements a single-phase grounding fault location determination method as described in any one of claims 1 to 6.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute a single-phase grounding fault location determination method as described in any one of claims 1 to 6.

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