A single-phase ground fault location determination method and system, a terminal device, and a storage medium

Abstract

The application discloses a single-phase ground fault position judgment method, system, terminal equipment and storage medium, and the method comprises the steps of acquiring the AC side phase voltage, AC side phase current, DC side voltage and DC side current signal of the current converter end; calculating the fundamental component and DC component at the neutral bus of the DC side of the current converter end according to the DC side current signal; judging whether the fundamental component condition is met according to the fundamental component and the preset fundamental component threshold value to obtain a first judgment result; judging whether the DC component condition is met according to the AC side phase voltage, AC side phase current, DC side voltage and DC component to obtain a second judgment result; obtaining the fault judgment result of the current converter end and the fault judgment result of the opposite converter according to the first judgment result and the second judgment result; and performing ground protection action according to the fault judgment result of the current converter end and the fault judgment result of the opposite converter. Through implementation of the application, the efficiency of protection action is improved.

Description

Technical Field

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

[0002] In flexible DC transmission systems based on modular multilevel converters (MMC), bipolar connection is widely used due to its high efficiency and reliability. This connection method allows a zero-potential reference point to be directly drawn from the DC neutral bus, facilitating stable system operation. When a single-phase ground fault occurs on the threshold side of either end of the system, a DC component will appear in the AC current at the fault end, while the AC current at the non-faulty 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 ground fault on the threshold side of the flexible DC system to eliminate short-circuit current surges and bridge arm overvoltages, thus preventing any impact on the safe operation of the entire DC grid.

[0003] Existing conventional protection strategies for threshold-side single-phase-to-ground faults in bipolar flexible DC systems focus on fault location identification. Generally, differential protection is used at the fault location, and the signal is transmitted to the non-faulty location via communication equipment, enabling the non-faulty location protection to coordinate its operation and clear the fault. However, considering that signal transmission from the faulty to the non-faulty location is affected by environmental factors and takes time, it is difficult to quickly identify the fault location, thus hindering the rapid operation of the non-faulty location protection. Summary of the Invention

[0004] This invention provides a method, system, terminal device, and storage medium for determining the location of a single-phase grounding fault, which can effectively solve the problem that existing technologies cannot quickly identify the fault location, thus preventing the non-faulty end protection from operating quickly.

[0005] One embodiment of the present invention provides a method for determining the location of a single-phase ground fault, applicable to the converter of a single-phase ground fault location determination system; the single-phase ground fault location determination system includes several converters; the DC side of the converter is connected to the neutral bus.

[0006] The method for determining the location of a single-phase ground fault includes:

[0007] Acquire the current AC phase voltage, AC phase current, DC voltage, and DC current signals at the converter terminal;

[0008] Fourier transform is performed on the DC-side current signal to obtain the fundamental frequency component and DC component at the current converter terminal DC side connected to the neutral bus.

[0009] Based on the fundamental frequency component and the preset fundamental frequency component threshold, determine whether the fundamental frequency component condition is met, and obtain the first determination result;

[0010] Based on the AC phase voltage, AC phase current, DC voltage, and DC component, determine whether the DC component condition is met, and obtain the second determination result.

[0011] Based on the first judgment result and the second judgment result, the current converter fault judgment result and the opposite converter fault judgment result are obtained;

[0012] Based on the current fault diagnosis results at the converter end and the fault diagnosis results at the other converter end, grounding protection action is performed.

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

[0014] The AC side of the converter in the single-phase ground fault location determination 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; and the secondary side of the current transformer is connected to the relay protection device.

[0015] The converter transformer is used for power conversion and 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 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 disconnect the fault.

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

[0022] Determine the DC-side neutral bus current value based on the DC-side current signal;

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

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

[0025] Based on the fundamental frequency component and a preset fundamental frequency component threshold, determine whether the fundamental frequency component condition is met to obtain a first determination result, including:

[0026] The comparison is made based on the fundamental frequency component and a preset fundamental frequency component threshold.

[0027] If the fundamental frequency component is greater than a preset fundamental frequency component threshold, the first judgment result is determined to satisfy the fundamental frequency component condition;

[0028] If the fundamental frequency component is not greater than the preset fundamental frequency component threshold, the first judgment result is determined to be that the fundamental frequency component condition is not met.

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

[0030] Based on the AC phase voltage, AC phase current, DC voltage, and DC component, determine whether the DC component condition is met to obtain a second determination result, including:

[0031] The DC component judgment value is calculated based on the AC phase voltage, the AC phase current, the DC voltage, and the preset current reliability coefficient.

[0032] The comparison is made based on the DC component and the DC judgment value;

[0033] If the DC component is less than the DC component judgment value, the second judgment result is determined to satisfy the DC component condition;

[0034] If the DC component is not less than the DC component judgment value, the second judgment result is determined to be that the DC component condition is not met.

[0035] Further, based on the first judgment result and the second judgment result, the current converter-side fault judgment result and the opposite-side converter fault judgment result are obtained, including:

[0036] If the first judgment result is that the fundamental frequency component condition is met and the second judgment result is that the DC component condition is met, then the current converter valve side is determined to be a non-fault position and the opposite converter valve side is a ground fault position.

[0037] If the first judgment result is that the fundamental frequency component condition is met, and the second judgment result is that the DC component condition is not met, then the current converter valve side is determined to be a ground fault location, and the opposite converter valve side is a non-fault location.

[0038] If the first judgment result is that the fundamental frequency component condition is not met, and the second judgment result is that the DC component condition is met, then the current converter valve side is determined to be a non-fault position, the opposite converter valve side is determined to be 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] If the first judgment result is that the fundamental frequency component condition is not met, and the second judgment result is that the DC component condition is not met, then the current converter valve side is determined to be a non-fault position, and the opposite converter valve side is determined to be a non-fault position.

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

[0041] The single-phase ground fault location determination system includes:

[0042] The system data acquisition module is used to acquire the AC side phase voltage, AC side phase current, DC side voltage, and DC side current signals at the current converter terminal.

[0043] The component calculation module is used to perform Fourier calculation based on the DC-side current signal to obtain the fundamental frequency component and DC component at the current converter terminal DC side connected to the neutral bus.

[0044] The first judgment module is used to determine whether the fundamental frequency component condition is met based on the fundamental frequency component and the preset fundamental frequency component threshold, and to obtain the first judgment result.

[0045] The second judgment module is used to determine whether the DC component condition is met based on the AC side phase voltage, AC side phase current, DC side voltage and the DC component, and to obtain the second judgment result.

[0046] The fault result determination module is used to obtain the current converter-side fault judgment result and the opposite-side converter fault judgment result based on the first judgment result and the second judgment result;

[0047] The system protection module is used to perform grounding protection actions based on the current fault judgment results of the converter and the fault judgment results of the converter on the opposite side.

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

[0049] The AC side of the converter in the single-phase ground fault location determination 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; and the secondary side of the current transformer is connected to the relay protection device.

[0050] The converter transformer is used for power conversion and 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 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 disconnect the fault.

[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. When the processor executes the computer program, it implements a single-phase grounding fault location determination method as described in the above embodiments.

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

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

[0059] This invention provides a method, system, terminal device, and storage medium for determining the location of a single-phase ground fault. The method is applicable to converters in a single-phase ground fault location determination system. The single-phase ground fault location determination system includes several converters. The DC side of each converter is connected to a neutral bus. The method acquires the AC phase voltage, AC phase current, DC voltage, and DC current signals at the current converter terminal. Fourier transform calculations are performed on the DC current signals to obtain the fundamental frequency component and DC component at the DC side of the current converter terminal connected to the neutral bus. Based on the fundamental frequency component and a preset fundamental frequency component threshold, a first determination result is obtained by determining whether the fundamental frequency component condition is met. A second determination result is obtained by determining whether the DC component condition is met based on the AC phase voltage, AC phase current, DC voltage, and the DC component. A fault determination result for the current converter terminal and a fault determination result for the opposite converter terminal are obtained based on the first and second determination results. Ground fault protection actions are performed based on the current and opposite converter fault determination results. By acquiring the DC-side current signal at the current converter terminal and calculating the fundamental frequency component and DC component, it is possible to determine whether a single-phase ground fault has occurred on the current side and the opposite side of the converter based on the fundamental frequency component and the DC component. It is not necessary to communicate from the faulty end to the non-faulty end to realize the protection action. The fault judgment results on the current side and the opposite side can be obtained directly, thereby improving the identification of the fault location on the current side and the opposite side of the system valve side and improving the efficiency of implementing protection actions. Attached Figure Description

[0060] Figure 1 This is a flowchart illustrating a method for determining the location of a single-phase grounding fault according to an embodiment of the present invention.

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

[0062] Figure 3 This is a schematic diagram of the judgment logic of a single-phase grounding fault location determination method provided in an embodiment of the present invention;

[0063] Figure 4 This is a schematic diagram of a single-phase grounding fault location determination system provided in an embodiment of the present invention. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] See Figure 1 This is a flowchart illustrating a method for determining the location of a single-phase ground fault according to an embodiment of the present invention. The method is applicable to the converter in a single-phase ground fault location determination system. The single-phase ground fault location determination system includes several converters. The DC side of the converter is connected to the neutral bus. The method includes:

[0066] S1. Obtain the AC phase voltage, AC phase current, DC voltage, and DC current signals at the current converter terminal;

[0067] Specifically, the single-phase ground fault location determination system includes a flexible DC transmission network with two or more terminals connected to several large-capacity converters, and the system is a bipolar topology system with a grounded DC-side neutral bus. The current AC-side phase voltage at the converter terminal is U. v The AC 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 determination system is a bipolar topology system with a DC-side neutral bus grounding system. The AC side of the converter in the single-phase ground fault location determination system is connected to the AC power grid via a converter transformer. The DC side of the converter is connected to the primary side of a current transformer at the neutral bus connection point. The secondary side of the current transformer is connected to a relay protection device. The converter transformer is used for power conversion and 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 on the primary side into a low current for the load. The relay protection device is used to clear 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. To facilitate measurement, protection, and control, the current needs to be converted into a uniform quantity, and this connection also achieves electrical isolation.

[0069] S2. Perform Fourier calculation based on the DC side current signal to obtain the fundamental frequency component and DC component at the current converter terminal DC side connected to the neutral bus.

[0070] Specifically, a current transformer is installed at the DC-side connection to the neutral bus of the converter to sample the DC-side current signal. Then, Fourier calculation is performed on the DC-side current signal to obtain the fundamental frequency component I at the current j-th converter terminal DC-side connection to the neutral bus. gnd1 and DC component I gnd0 The Fourier algorithm uses Fourier transform to filter out the various frequency components in a continuous signal.

[0071] S3. Based on the fundamental frequency component and the preset fundamental frequency component threshold, determine whether the fundamental frequency component condition is met, and obtain the first determination result;

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

[0073] Determine the DC-side neutral bus current value based on the DC-side current signal;

[0074] The fundamental frequency component threshold is calculated based on 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 DC side neutral bus current under normal operating conditions, that is, ε is the maximum measurement error of the current at the DC side neutral bus under normal operating conditions.

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

[0077] Based on the fundamental frequency component and a preset fundamental frequency component threshold, determine whether the fundamental frequency component condition is met to obtain a first determination result, including:

[0078] The comparison is made based on the fundamental frequency component and a preset fundamental frequency component threshold.

[0079] If the fundamental frequency component is greater than a preset fundamental frequency component threshold, the first judgment result is determined to satisfy the fundamental frequency component condition;

[0080] If the fundamental frequency component is not greater than the preset fundamental frequency component threshold, the first judgment result is determined to be 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 met, that is, whether the fundamental frequency component is greater than a preset fundamental frequency component threshold. 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, i.e.: |I gnd1 |>ε。 When the fundamental frequency component is greater than a preset fundamental frequency component threshold, i.e. |I gnd1If |>ε, the first judgment result is determined to satisfy the fundamental frequency component condition; if the fundamental frequency component is not greater than the preset fundamental frequency component threshold, i.e. |I gnd1 If |≤ε, the first judgment result is determined to be that the fundamental frequency component condition is not met.

[0082] S4. Based on the AC side phase voltage, AC side phase current, DC side voltage and the DC component, determine whether the DC component condition is met, and obtain the second judgment result;

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

[0084] Based on the AC phase voltage, AC phase current, DC voltage, and DC component, determine whether the DC component condition is met to obtain a second determination result, including:

[0085] The DC component judgment value is calculated based on the AC phase voltage, the AC phase current, the DC voltage, and the preset current reliability coefficient.

[0086] The comparison is made based on the DC component and the DC judgment value;

[0087] If the DC component is less than the DC component judgment value, the second judgment result is determined to satisfy the DC component condition;

[0088] If the DC component is not less than the DC component judgment value, the second judgment result is determined to be that the DC component condition is not met.

[0089] In a preferred embodiment of the present invention, it is determined whether the DC component condition is met, that is, 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 bus on the DC side of the converter is too small, i.e.: |I gnd0 |<kI set2 , The preset current reliability factor k has a value range of 0 < k < 1. The system power factor is calculated based on the AC phase voltage, AC phase current, DC voltage, and a preset current reliability coefficient, yielding a DC component judgment value <kI. set2 The DC component is compared with the DC component judgment value. If the DC component is less than the DC component judgment value, i.e., |I gnd0 |<kI set2 The second judgment result is determined to satisfy the DC component condition; if the DC component is not less than the DC component judgment value, i.e., |I gnd0 |≥kI set2The second judgment result is determined to be that the DC component condition is not met.

[0090] S5. Based on the first judgment result and the second judgment result, obtain the current converter end fault judgment result and the opposite converter fault judgment result;

[0091] Specifically, based on the first judgment result and the second judgment result, the current converter-side fault judgment result and the opposite-side converter fault judgment result are obtained, including:

[0092] If the first judgment result is that the fundamental frequency component condition is met and the second judgment result is that the DC component condition is met, then the current converter valve side is determined to be a non-fault position and the opposite converter valve side is a ground fault position.

[0093] If the first judgment result is that the fundamental frequency component condition is met, and the second judgment result is that the DC component condition is not met, then the current converter valve side is determined to be a ground fault location, and the opposite converter valve side is a non-fault location.

[0094] If the first judgment result is that the fundamental frequency component condition is not met, and the second judgment result is that the DC component condition is met, then the current converter valve side is determined to be a non-fault position, the opposite converter valve side is determined to be 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] If the first judgment result is that the fundamental frequency component condition is not met, and the second judgment result is that the DC component condition is not met, then the current converter valve side is determined to be a non-fault position, and the opposite converter valve side is determined to be a non-fault position.

[0096] In a preferred embodiment of the present invention, that is, when |I gnd1 |>ε and |I gnd0 |<kI set2 When both conditions are met, it is determined that the valve side of the i-th converter is in a non-fault position and the valve side of the converter on the opposite side is in a single-phase ground fault position. When |I gnd1 |≤ε and |I gnd0 |≥kI set2 When |I, the system runs normally; when |I gnd1 |>ε and |I gnd0 |≥kI set2 At that time, a ground fault occurs on the AC side of the current converter valve; when |I gnd1 |≤ε and |I gnd0 |<kI set2 At this time, both the current converter side and the opposite converter are operating normally, while a ground fault occurs on the AC side of other terminal valves. For example, when |I gnd1 |≤ε and |I gnd0 |<kI set2At this time, MMC1 on the current side and MMC3 on the opposite side are both operating normally, while MMC2 or MMC4 on other sides has a ground fault. For example... Figure 2 As shown, MMC1 and MMC3 are opposite to each other, and similarly, MMC2 and MMC4 are opposite to each other.

[0097] S6. Based on the current fault judgment result of the converter end and the fault judgment result of the converter on the other side, perform grounding protection action.

[0098] In a preferred embodiment of the present invention, the protection logic is as follows: Figure 3 As shown, when no single-phase ground fault occurs on the valve side of any of the converters in a two- or multi-terminal flexible DC grid, the fundamental frequency component of the current at the DC side connected to the neutral bus is zero, and the amplitude of the fundamental frequency component of the current at the DC side connected to the neutral bus calculated by the relay protection is |I gnd1 The value will not exceed the maximum measurement error, and its DC component always exists and is greater than the setting value, so the protection will not misjudge. When a single-phase ground fault occurs on other valve sides besides the opposite converter, the operating status of this side is not affected by the fault. Similar to the above situation, the fundamental frequency component amplitude of the DC current connected to the neutral bus obtained by the relay protection calculation is |I gnd1 The DC component will always exist and exceed the set value, ensuring the protection will not misjudge. When a single-phase ground fault occurs on the valve side of the converter, the grounding point of the DC side neutral bus and the fault point form a short-circuit path. A short-circuit current flows through the DC side of the converter connected to the neutral bus, the magnitude of which is the sum of the currents of the non-faulty phase bridge arms of the converter. At this time, the fundamental frequency component of the current at the DC side connected to the neutral bus exists, and its amplitude is |I gnd1 The current at the DC side connected to the neutral bus will be larger than the maximum measurement error, but the DC component of the current will be larger than the setting value, so the protection will not misjudge. When a single-phase ground fault occurs on the valve side of the converter on the opposite side, the current at the DC side connected to the neutral bus of this converter will have a fundamental frequency component, the amplitude of which is |I gnd1 The current is related to the system angular frequency, bridge arm inductance, submodule capacitance, and AC line voltage, but it 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 phase voltage, AC phase current, DC voltage, and DC current signals of the current converter are acquired; Fourier transform calculations are performed on the DC current signal to obtain the fundamental frequency component and DC component at the DC side of the current converter connected to the neutral bus; based on the fundamental frequency component and a preset fundamental frequency component threshold, it is determined whether the fundamental frequency component condition is met, resulting in a first determination result; based on the AC phase voltage, AC phase current, DC voltage, and DC component, it is determined whether the DC component condition is met, resulting in a second determination result; based on the first determination result and the second determination result, the fault determination result of the current converter and the fault determination result of the converter on the opposite side are obtained; based on the fault determination result of the current converter and the fault determination result of the converter on the opposite side, grounding protection is performed. By acquiring the DC-side current signal at the current converter terminal and calculating the fundamental frequency component and DC component, it is possible to determine whether a single-phase ground fault has occurred on the current side and the opposite side of the converter based on the fundamental frequency component and the DC component. It is not necessary to communicate from the faulty end to the non-faulty end to realize the protection action. The fault judgment results on the current side and the opposite side can be obtained directly, thereby improving the identification of the fault location on the current side and the opposite side of the system valve side and improving the efficiency of implementing protection actions.

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

[0101] The system data acquisition module is used to acquire the AC side phase voltage, AC side phase current, DC side voltage, and DC side current signals at the current converter terminal.

[0102] The component calculation module is used to perform Fourier calculation based on the DC-side current signal to obtain the fundamental frequency component and DC component at the current converter terminal DC side connected to the neutral bus.

[0103] The first judgment module is used to determine whether the fundamental frequency component condition is met based on the fundamental frequency component and the preset fundamental frequency component threshold, and to obtain the first judgment result.

[0104] The second judgment module is used to determine whether the DC component condition is met based on the AC side phase voltage, AC side phase current, DC side voltage and the DC component, and to obtain the second judgment result.

[0105] The fault result determination module is used to obtain the current converter-side fault judgment result and the opposite-side converter fault judgment result based on the first judgment result and the second judgment result;

[0106] The system protection module is used to perform grounding protection actions based on the current fault judgment results of the converter and the fault judgment results of the converter on the opposite side.

[0107] Specifically, the system includes several converters; the DC side of each converter is connected to the neutral bus.

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

[0109] The AC side of the converter in the single-phase ground fault location determination 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; and the secondary side of the current transformer is connected to the relay protection device.

[0110] The converter transformer is used for power conversion and 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 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 disconnect the fault.

[0116] This invention provides a single-phase ground fault location determination system. The system data acquisition module acquires the AC phase voltage, AC phase current, DC voltage, and DC current signals at the current converter terminal. The component calculation module performs Fourier transform calculations based on the DC current signal to obtain the fundamental frequency component and DC component at the DC side connection to the neutral bus at the current converter terminal. A first judgment module determines whether the fundamental frequency component condition is met based on the fundamental frequency component and a preset fundamental frequency component threshold, obtaining a first judgment result. A second judgment module determines whether the DC component condition is met based on the AC phase voltage, AC phase current, DC voltage, and the DC component, obtaining a second judgment result. A fault result determination module obtains the current converter terminal fault determination result and the fault determination result of the opposite converter based on the first and second judgment results. Finally, a system protection module performs ground fault protection actions based on the current converter terminal fault determination result and the fault determination result of the opposite converter. By acquiring the DC-side current signal at the current converter terminal and calculating the fundamental frequency component and DC component, it is possible to determine whether a single-phase ground fault has occurred on the current side and the opposite side of the converter based on the fundamental frequency component and the DC component. It is not necessary to communicate from the faulty end to the non-faulty end to realize the protection action. The fault judgment results on the current side and the opposite side can be obtained directly, thereby improving the identification of the fault location on the current side and the opposite side of the system valve side and improving the efficiency of implementing protection actions.

[0117] It should be noted that the system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the system embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

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

[0119] 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. When the processor executes the computer program, it implements a single-phase grounding fault location determination method as described in the above embodiments. The terminal device may be a desktop computer, laptop, handheld computer, cloud server, or other computing device. The terminal device may include, but is not limited to, a processor and a memory.

[0120] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting various parts of the terminal device via various interfaces and lines.

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

[0122] Another embodiment of the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute a single-phase grounding fault location determination method as 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 executed by a processor, the computer program can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0124] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and 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 ground fault, characterized in that, A converter suitable for a single-phase ground fault location determination system; the single-phase ground fault location determination system includes several converters; the DC side of the converter is connected to the neutral bus. The method for determining the location of a single-phase ground fault includes: Acquire the current AC phase voltage, AC phase current, DC voltage, and DC current signals at the converter terminal; Fourier transform is performed on the DC-side current signal to obtain the fundamental frequency component and DC component at the current converter terminal DC side connected to the neutral bus. Based on the fundamental frequency component and the preset fundamental frequency component threshold, determine whether the fundamental frequency component condition is met, and obtain the first determination result; Based on the AC phase voltage, AC phase current, DC voltage, and DC component, determine whether the DC component condition is met, and obtain the second determination result. Based on the first judgment result and the second judgment result, the current converter fault judgment result and the opposite converter fault judgment result are obtained; Based on the current fault diagnosis results at the converter end and the fault diagnosis results at the other converter end, grounding protection action is performed; Specifically, based on the first judgment result and the second judgment result, the current converter-side fault judgment result and the opposite-side converter fault judgment result are obtained, including: If the first judgment result is that the fundamental frequency component condition is met and the second judgment result is that the DC component condition is met, then the current converter valve side is determined to be a non-fault position and the opposite converter valve side is a ground fault position. If the first judgment result is that the fundamental frequency component condition is met, and the second judgment result is that the DC component condition is not met, then the current converter valve side is determined to be a ground fault location, and the opposite converter valve side is a non-fault location. If the first judgment result is that the fundamental frequency component condition is not met, and the second judgment result is that the DC component condition is met, then the current converter valve side is determined to be a non-fault position, the opposite converter valve side is determined to be a non-fault position, and, except for the current converter valve side and the opposite converter valve side, other valve sides have ground faults. If the first judgment result is that the fundamental frequency component condition is not met, and the second judgment result is that the DC component condition is not met, then the current converter valve side is determined to be a non-fault position, and the opposite converter valve side is determined to be a non-fault position.

2. The method for determining the location of a single-phase ground fault as described in claim 1, characterized in that, The single-phase ground fault location determination system is a bipolar topology system with DC-side neutral bus grounding. The AC side of the converter in the single-phase ground fault location determination 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; and the secondary side of the current transformer is connected to the relay protection device. The converter transformer is used for power conversion and 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 on the primary side into a low current used by the load. The relay protection device is used to disconnect the fault.

3. The method for determining the location of a single-phase ground fault as described in claim 1, characterized in that, The calculation of the fundamental frequency component threshold includes: Determine the DC-side neutral bus current value based on the DC-side current signal; The fundamental frequency component threshold is calculated based on the DC-side neutral bus current value and a preset ratio.

4. The method for determining the location of a single-phase ground fault as described in claim 1, characterized in that, The first judgment result includes: satisfying the fundamental frequency component condition and not satisfying the fundamental frequency component condition; Based on the fundamental frequency component and a preset fundamental frequency component threshold, determine whether the fundamental frequency component condition is met to obtain a first determination result, including: The comparison is made based on the fundamental frequency component and a preset fundamental frequency component threshold. If the fundamental frequency component is greater than a preset fundamental frequency component threshold, the first judgment result is determined to satisfy the fundamental frequency component condition; If the fundamental frequency component is not greater than the preset fundamental frequency component threshold, the first judgment result is determined to be that the fundamental frequency component condition is not met.

5. The method for determining the location of a single-phase ground fault as described in claim 1, characterized in that, The second judgment result includes: satisfying the DC component condition and not satisfying the DC component condition; Based on the AC phase voltage, AC phase current, DC voltage, and DC component, determine whether the DC component condition is met to obtain a second determination result, including: The DC component judgment value is calculated based on the AC phase voltage, the AC phase current, the DC voltage, and the preset current reliability coefficient. The comparison is made based on the DC component and the DC judgment value; If the DC component is less than the DC component judgment value, the second judgment result is determined to satisfy the DC component condition; If the DC component is not less than the DC component judgment value, the second judgment result is determined to be that the DC component condition is not met.

6. A single-phase ground fault location determination system, characterized in that, It includes several converters; the DC side of each converter is connected to the neutral bus. The single-phase ground fault location determination system includes: The system data acquisition module is used to acquire the AC side phase voltage, AC side phase current, DC side voltage, and DC side current signals at the current converter terminal. The component calculation module is used to perform Fourier calculation based on the DC-side current signal to obtain the fundamental frequency component and DC component at the current converter terminal DC side connected to the neutral bus. The first judgment module is used to determine whether the fundamental frequency component condition is met based on the fundamental frequency component and the preset fundamental frequency component threshold, and to obtain the first judgment result. The second judgment module is used to determine whether the DC component condition is met based on the AC side phase voltage, AC side phase current, DC side voltage and the DC component, and to obtain the second judgment result. The fault result determination module is used to obtain the current converter-side fault judgment result and the opposite-side converter fault judgment result based on the first judgment result and the second judgment result; The system protection module is used to perform grounding protection actions based on the current fault judgment result of the converter end and the fault judgment result of the converter on the opposite side; The fault result determination module is used to obtain the current converter-side fault judgment result and the opposite-side converter fault judgment result based on the first judgment result and the second judgment result, including: If the first judgment result is that the fundamental frequency component condition is met and the second judgment result is that the DC component condition is met, then the current converter valve side is determined to be a non-fault position and the opposite converter valve side is a ground fault position. If the first judgment result is that the fundamental frequency component condition is met, and the second judgment result is that the DC component condition is not met, then the current converter valve side is determined to be a ground fault location, and the opposite converter valve side is a non-fault location. If the first judgment result is that the fundamental frequency component condition is not met, and the second judgment result is that the DC component condition is met, then the current converter valve side is determined to be a non-fault position, the opposite converter valve side is determined to be a non-fault position, and, except for the current converter valve side and the opposite converter valve side, other valve sides have ground faults. If the first judgment result is that the fundamental frequency component condition is not met, and the second judgment result is that the DC component condition is not met, then the current converter valve side is determined to be a non-fault position, and the opposite converter valve side is determined to be a non-fault position.

7. A single-phase ground fault location determination system as described in claim 6, characterized in that, The single-phase ground fault location determination system is a bipolar topology system with DC-side neutral bus grounding. The AC side of the converter in the single-phase ground fault location determination 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; and the secondary side of the current transformer is connected to the relay protection device. The converter transformer is used for power conversion and 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 on the primary side into a low current used by the load. The relay protection device is used to disconnect the fault.

8. A terminal device, characterized in that, The system includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements a method for determining the location of a single-phase ground fault as described in any one of claims 1 to 5.

9. 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, it controls the device containing the computer-readable storage medium to perform a single-phase grounding fault location determination method as described in any one of claims 1 to 5.

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