A unit fault location circuit
By designing a fault location circuit for the generator set and utilizing voltage and zero-sequence current measurements combined with a data processing unit, the problem of inaccurate single-phase grounding fault location in the generator set was solved, achieving accurate location and efficient maintenance, and improving the safety and reliability of the generator set.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SANXIA JINSHAJIANG YUNCHUAN HYDROPOWER DEV CO LTD
- Filing Date
- 2025-05-09
- Publication Date
- 2026-06-30
AI Technical Summary
Existing methods for locating single-phase ground faults in generator sets cannot accurately distinguish the fault location, resulting in an excessively large location range and low maintenance efficiency. Electromagnetic transformer measurements are affected by the position and arrangement of the three-phase conductors, leading to inaccurate measurements and installation difficulties.
Design a unit fault location loop, which measures voltage waveform and zero-sequence current through voltage acquisition elements and current acquisition elements, and uses fault location elements combined with signal transmission interface and data processing unit to achieve accurate fault location. The system includes voltage transformers, optical current transformers, data conversion and merging units, FPGA chips and ARM microprocessors.
It enables accurate location of single-phase grounding faults, narrows the fault range, improves maintenance efficiency, and enhances the safety and reliability of generator sets. The optical current transformer is not affected by the spatial arrangement of conductors, and its measurement is accurate and easy to install.
Smart Images
Figure CN224436533U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of generator set maintenance technology, and in particular to a generator set fault location circuit. Background Technology
[0002] Single-phase ground faults are the most common type of fault in generator sets. After a fault occurs, it causes an imbalance in the three-phase voltage to ground at the generator terminals, generating zero-sequence voltage and zero-sequence current, triggering the fundamental zero-sequence voltage protection. However, generator sets are typically equipped with a main transformer, excitation transformer, and high-voltage transformer connected in parallel with the generator. If a single-phase ground fault occurs in these transformers or busbars, it will also trigger the fundamental zero-sequence voltage protection, but it cannot distinguish the location of the single-phase ground fault. Conventional methods for locating single-phase ground faults in generator sets mainly rely on the phasor relationship between the fundamental zero-sequence voltage and the three-phase voltage at the generator terminals. However, this method cannot distinguish faults located in different areas such as the generator body, the high-voltage side of the excitation transformer, the low-voltage side of the main transformer, the high-voltage side of the high-voltage transformer, and the busbars. This results in an excessively large fault location range and low maintenance efficiency.
[0003] In existing technologies, electromagnetic current transformers are mainly used to measure zero-sequence current. However, this method suffers from problems such as inaccurate measurement and installation difficulties. The main reason is that the measurement of electromagnetic current transformers is affected by the position and asymmetrical arrangement of the three-phase conductors. Therefore, it is necessary to study a unit fault location circuit that can accurately and quickly distinguish the location of single-phase grounding faults, effectively narrowing the fault location range, improving maintenance efficiency, and saving manpower and resources. Utility Model Content
[0004] The purpose of this section is to outline some aspects of the embodiments of this utility model and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of this section, the abstract and the title of this utility model. Such simplifications or omissions shall not be used to limit the scope of this utility model.
[0005] Given that conventional generator single-phase grounding protection systems cannot distinguish fault locations, resulting in an excessively large fault location range and low maintenance efficiency; and that electromagnetic current transformers are affected by the position and arrangement of the three-phase conductors, leading to inaccurate measurements and installation difficulties.
[0006] Therefore, the technical problem to be solved by this utility model is to design a device that can effectively distinguish fault locations, measure accurately, and is easy to install to meet the needs of the existing working environment.
[0007] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a unit fault location circuit, comprising,
[0008] The voltage acquisition element measures and acquires the voltage waveform signals at the generator terminals and the low-voltage side of the main transformer;
[0009] The current acquisition element measures and acquires the zero-sequence currents at the generator terminal side, the excitation transformer high-voltage side, the main transformer low-voltage side, and the high-voltage transformer high-voltage side.
[0010] The fault location element achieves data transmission by connecting to the wiring terminals of the current acquisition element through the signal transmission interface.
[0011] As an improvement to this utility model
[0012] Voltage acquisition components include three-phase voltage transformers at the generator terminals and three-phase voltage transformers on the low-voltage side of the main transformer;
[0013] The generator terminal three-phase voltage transformer is connected to the generator at the first end and to the generator terminal circuit breaker at the last end.
[0014] The first end of the three-phase voltage transformer on the low-voltage side of the main transformer is connected to the main transformer, and the last end is connected to the circuit breaker at the generator terminal.
[0015] The three-phase voltage transformers at the generator terminals and the three-phase voltage transformers on the low-voltage side of the main transformer are respectively connected to the fault location element.
[0016] As an improvement to this utility model
[0017] The current acquisition element includes a primary sensing unit, a transmission optical cable, and an acquisition unit;
[0018] The transmission optical cable connects the primary sensing unit and the acquisition unit;
[0019] The acquisition unit collects the optical signals from the light source and the primary sensing unit, and inputs them to the fault location element through the wiring terminals.
[0020] As an improvement to this utility model
[0021] The acquisition unit includes a coupler, a phase modulator, a detector, and a demodulation circuit;
[0022] One end of the coupler is connected to the phase modulator, and the phase modulator is connected to the demodulation circuit to realize the transmission and processing of the light source optical signal;
[0023] One end of the coupler is connected to the detector to realize the optical signal conversion and transmission of the primary sensing unit, which is then sent to the demodulation circuit for processing.
[0024] As an improvement to this utility model
[0025] A primary sensing unit includes a waveplate, sensing fiber, reflector, insulating frame, and fixing components;
[0026] The tail of the reflector and the sensing fiber are fixedly connected, and the sensing fiber is coiled on the insulating frame.
[0027] The reflector is fixedly connected to the tail of the sensing fiber and its spatial position coincides with that of the waveplate.
[0028] As an improvement to this utility model
[0029] Current acquisition elements include excitation transformer acquisition elements, high-voltage transformer acquisition elements, generator body acquisition elements, and low-voltage side acquisition elements of the main transformer.
[0030] The excitation transformer acquisition element, the high-voltage transformer acquisition element, the generator body acquisition element, and the low-voltage side acquisition element of the main transformer are respectively connected to the fault location element.
[0031] As an improvement to this utility model
[0032] The fault location element includes a data conversion and merging unit, which contains a signal conditioning circuit.
[0033] The output of the signal conditioning circuit is connected to a multiplexer to transmit signals from the acquisition unit.
[0034] The output port of the multiplexer is connected to the input port of the ADC.
[0035] As an improvement to this utility model
[0036] The digital output of the ADC is connected to the input port of the FPGA chip;
[0037] The FPGA chip processes data and connects to the input of the data merging circuit via a data bus.
[0038] The output of the data merging circuit and the algorithm microprocessor are connected via a data bus.
[0039] As an improvement to this utility model
[0040] The algorithm microprocessor is configured to connect to the ARM microprocessor via a high-speed output interface;
[0041] The ARM microprocessor's output port is connected to the display via a data bus;
[0042] The ARM microprocessor output port is additionally connected to an RS485 interface for external data transmission.
[0043] The beneficial effects of this utility model are as follows: the system can accurately determine the location of a single-phase grounding fault, narrow the fault location range, improve maintenance efficiency, and enhance the safety, reliability, and economy of the generator set. The optical current transformer is not affected by the spatial arrangement of the conductor and the imbalance of the magnetic field, and can accurately measure the zero-sequence current. It has a wide measurement range and no saturation problem. The insulating frame of the primary sensing unit can be designed according to the size and arrangement of the three-phase conductors of the protected generator set. There are no strict requirements on the shape, size, and arrangement of the conductors, which facilitates installation and maintenance. Attached Figure Description
[0044] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Among them:
[0045] Figure 1 This is a connection planning diagram of the unit fault location circuit in this utility model.
[0046] Figure 2 This is a hardware architecture diagram of the current acquisition element in the unit fault location circuit of this utility model.
[0047] Figure 3 This is a diagram showing the sequence of components used in the fault location circuit of the generator unit in this utility model. Detailed Implementation
[0048] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.
[0049] Example 1
[0050] Reference Figure 1 This embodiment provides a unit fault location circuit.
[0051] Voltage acquisition element 1 is connected in the system circuit to measure and acquire voltage waveform signals at the generator terminal and the low-voltage side of the main transformer. Voltage acquisition element 1 uses a corresponding voltage transformer and is set at the required detection location.
[0052] The current acquisition element 2 includes four corresponding optical current transformers. The four optical current transformers measure the zero-sequence currents on the generator terminal side, the excitation transformer high-voltage side, the main transformer low-voltage side, and the high-voltage transformer high-voltage side, respectively. The zero-sequence currents measured by each transformer are introduced into the fault location element 3 through the wiring terminal set between the current acquisition element 2 and the fault location element 3 to realize data transmission.
[0053] The fault location element 3 receives each zero-sequence current and simultaneously collects the zero-sequence voltage on the generator terminal side and the zero-sequence voltage on the low-voltage side of the main transformer. Based on the zero-sequence direction criterion, it detects the fault location.
[0054] The corresponding module responsible for fault determination within fault location element 3 will determine the fault location based on the calculated data. If the fundamental components of the zero-sequence voltage and zero-sequence current satisfy the following formula during the fault, it can be determined as an in-zone grounding fault; otherwise, it is an out-of-zone grounding fault.
[0055]
[0056] In the formula, arg is the function for extracting the phase angle of the phasor. It is the fundamental phasor of the zero-sequence voltage. Let θ be the fundamental phasor of the zero-sequence current. set1 θ set2 These are the lower and upper threshold limits for the phase angle difference between the zero-sequence directional current and voltage, respectively. g0 I is the effective value of the fundamental frequency of the zero-sequence voltage. g0 U is the effective value of the fundamental frequency of the zero-sequence current. 0set For the zero-sequence voltage setting, I 0set The zero-sequence current is set to a fixed value.
[0057] Taking a generator as an example, only when the generator terminal zero-sequence current I g0 Zero-sequence voltage U at the terminal g0 The phase angle difference between them is in θ set1 θ set2 Between, and simultaneously the zero-sequence voltage U g0 and zero-sequence current I g0 Each is greater than the corresponding fixed value U 0set and I 0set In the case of a fault, it can be determined that the grounding fault is within the generator area (i.e., the generator side of the generator terminal current acquisition element); otherwise, it can be determined that the fault is not within the generator area.
[0058] Example 2
[0059] Reference Figures 1-2 This embodiment is based on the previous embodiment, and differs from the previous embodiment in that:
[0060] The voltage acquisition element 1 includes a generator terminal three-phase voltage transformer 11 and a main transformer low-voltage side three-phase voltage transformer 12. The two voltage transformers are used to measure the generator terminal voltage and the main transformer low-voltage side voltage, respectively. In the circuit, the main transformer low-voltage side three-phase voltage transformer 12 is connected to the main transformer at its start end and to the generator terminal circuit breaker at its end. The generator terminal three-phase voltage transformer 11 is connected to the generator at its start end and to the generator terminal circuit breaker at its end, thus fulfilling their respective functions.
[0061] The generator terminal three-phase voltage transformer 11 and the main transformer low-voltage side three-phase voltage transformer 12 are respectively connected to the fault location element 3, so that the fault location element 3 can calculate and determine the specific location based on the zero-sequence voltage and subsequent zero-sequence current.
[0062] The current acquisition element 2 is sequentially connected to a primary sensing unit 21, a transmission optical cable 22, and an acquisition unit 23. The transmission optical cable 22 serves to connect the primary sensing unit 21 and the acquisition unit 23.
[0063] A primary sensing unit 21 is fitted around the required primary conductor. A data acquisition unit 23 provides the light source and calculates the primary current, while simultaneously transmitting the calculated primary current to the fault location element 3. The beginning of the transmission optical cable 22 is connected to the data acquisition unit 23, and the end is connected to the primary sensing unit 21. The data acquisition unit 23 can collect the optical signals provided by the light source and the optical signals input from the primary sensing unit 21, and input them to the fault location element 3 via terminals for subsequent calculations and judgments.
[0064] The acquisition unit 23 includes a coupler, a phase modulator, a detector, and a demodulation circuit. The light source generates a suitable optical signal, and the coupler transmits this signal to the phase modulator connected at one end. The optical signal returned by the primary sensing unit 21 is transmitted to the detector via the optical fiber cable 22 and the coupler. The detector receives the optical signal transmitted by the coupler, converts it into an electrical signal, and sends it to the demodulation circuit for calculation. The demodulation circuit applies a modulation signal to the phase modulator and performs demodulation calculations, ultimately calculating each zero-sequence current.
[0065] The primary sensing unit 21 includes a waveplate 211, a sensing fiber 212, a reflector 213, an insulating frame 214, and a fixing member 215. The reflector 213 and the tail of the sensing fiber 212 are fixedly connected. The insulating frame 214 is looped around the outside of the primary conductor. The sensing fiber 212 is coiled on the insulating frame 214 to form N concentric sensing fiber loops, where N ranges from 1 to 1000. The reflector 213 is fixed to the tail of the sensing fiber 212. The beginning and end of the primary sensing unit 21 are connected to 215 to ensure that the spatial position of the reflector 213 coincides with that of the waveplate 211.
[0066] Example 3
[0067] Reference Figures 1-3 This embodiment is based on the previous embodiment, and differs from the previous embodiment in that:
[0068] The current acquisition element 2 includes the excitation transformer acquisition element 24, the high-voltage transformer acquisition element 25, the generator body acquisition element 26, and the low-voltage side acquisition element 27 of the main transformer; the four acquisition elements are connected to the fault location element 3.
[0069] The data conversion and merging unit 31 is responsible for receiving analog signals from the four current acquisition elements 2 and performing signal conditioning and conversion. The signal conditioning circuitry within the data conversion and merging unit 31 may include filter circuits, amplifier circuits, isolation circuits, etc., to eliminate noise, improve signal quality, and protect circuit safety.
[0070] A multiplexer is used to transmit the conditioned analog signal to the analog-to-digital converter (ADC) in a time-division manner. Since the number of input ports of an ADC is limited, a multiplexer can effectively improve the utilization rate of the ADC. The digital output of the ADC is connected to the input port of an FPGA chip, which is responsible for processing the digital signal output by the ADC, including data filtering, feature extraction, and fault detection.
[0071] The data processed by the FPGA chip is connected to the input of the data merging circuit via the data bus. The data merging circuit is responsible for merging the data processed by the FPGA chip with the voltage data collected by the voltage acquisition element 1 to form a complete data packet, which is then sent to the algorithm microprocessor 32.
[0072] The algorithm microprocessor 32 is responsible for executing the fault location algorithm mentioned in Embodiment 1, determining the fault location based on current and voltage data, performing corresponding control operations, and transmitting the result information to the ARM microprocessor. The ARM microprocessor is responsible for the system's human-computer interaction and external data transmission, including controlling the display to show fault information and communicating with other devices via the RS485 interface.
[0073] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.
Claims
1. A unit fault location circuit, characterized in that: include, The voltage acquisition element (1) measures and acquires the voltage waveform signals at the generator terminals and the low-voltage side of the main transformer; The current acquisition element (2) measures and acquires the zero-sequence currents at the generator terminal side, the high-voltage side of the excitation transformer, the low-voltage side of the main transformer, and the high-voltage side of the high-voltage transformer. The fault location element (3) is connected to the wiring terminals of the current acquisition element (2) through the signal transmission interface to realize data transmission.
2. The unit fault location circuit according to claim 1, characterized in that: The voltage acquisition element (1) includes a three-phase voltage transformer (11) at the generator terminal and a three-phase voltage transformer (12) on the low-voltage side of the main transformer; The generator terminal three-phase voltage transformer (11) is connected to the generator at the first end and to the generator terminal circuit breaker at the last end. The three-phase voltage transformer (12) on the low-voltage side of the main transformer is connected to the main transformer at the first end and to the machine terminal circuit breaker at the last end; The generator terminal three-phase voltage transformer (11) and the main transformer low-voltage side three-phase voltage transformer (12) are respectively connected to the fault location element (3).
3. The unit fault location circuit according to claim 1, characterized in that: The current acquisition element (2) includes a primary sensing unit (21), a transmission optical cable (22), and an acquisition unit (23); The transmission optical cable (22) connects the primary sensing unit (21) and the acquisition unit (23); The acquisition unit (23) collects the light signals from the light source and the primary sensing unit (21) and inputs them to the fault location element (3) through the wiring terminal.
4. The unit fault location circuit according to claim 3, characterized in that: The acquisition unit (23) includes a coupler, a phase modulator, a detector, and a demodulation circuit; One end of the coupler is connected to the phase modulator, and the phase modulator is connected to the demodulation circuit to realize the transmission and processing of the light source optical signal; One end of the coupler is connected to the detector to realize the optical signal conversion and transmission of the primary sensing unit (21) and send it into the demodulation circuit for calculation.
5. The unit fault location circuit according to claim 4, characterized in that: The primary sensing unit (21) includes a waveplate (211), a sensing fiber (212), a reflector (213), an insulating frame (214), and a fixing element (215); The tail of the reflector (213) and the sensing fiber (212) are fixedly connected, and the sensing fiber (212) is coiled on the insulating frame (214). The reflector (213) is fixedly connected to the tail of the sensing fiber (212) and its spatial position coincides with that of the waveplate (211).
6. The unit fault location circuit according to any one of claims 1 to 5, characterized in that: The current acquisition element (2) includes the excitation transformer acquisition element (24), the high-voltage transformer acquisition element (25), the generator body acquisition element (26), and the low-voltage side acquisition element (27) of the main transformer; The excitation transformer acquisition element (24), the high-voltage transformer acquisition element (25), the generator body acquisition element (26), and the low-voltage side acquisition element (27) of the main transformer are respectively connected to the fault location element (3).
7. The unit fault location circuit according to claim 6, characterized in that: The fault location element (3) includes a data conversion and merging unit (31), and a signal conditioning circuit is provided in the data conversion and merging unit (31); The output of the signal conditioning circuit is connected to a multiplexer to transmit the signal from the acquisition unit (23); The output port of the multiplexer is connected to the input port of the ADC.
8. The unit fault location circuit according to claim 7, characterized in that: The digital output of the ADC is connected to the input port of the FPGA chip; The FPGA chip processes data and connects to the input of the data merging circuit via a data bus. The output of the data merging circuit and the algorithm microprocessor (32) are connected via a data bus.
9. The unit fault location circuit according to claim 8, characterized in that: The algorithm microprocessor (32) is configured with a high-speed output interface to connect to the ARM microprocessor (33); The output port of the ARM microprocessor (33) is connected to the display via a data bus; The output port of the ARM microprocessor (33) is additionally connected to an RS485 interface to participate in external data transmission.