Positioning identification performance detection system of fault positioning device based on space magnetic field

Abstract

The invention belongs to the technical field of non-contact distributed fault positioning device detection of a power transmission line, and particularly discloses a positioning identification performance detection system of a fault positioning device based on a space magnetic field. The system comprises a magnetic field generating device, a power frequency current source and a double-path pulse signal source, the magnetic field generating device is used for generating a magnetic field so as to generate a large and high-uniformity power frequency and pulse space magnetic field for the to-be-tested device; the power frequency current source device is used for simulating different working condition currents; the double-path pulse signal source is used for generating waveform parameter and double-path time difference controllable pulse electromagnetic signals so as to realize performance verification of the to-be-tested device. According to the scheme, the technical problems of low judgment accuracy and poor positioning precision caused by the fact that the magnetic field performance of an existing non-contact fault positioning device is not detected are solved.

Description

Technical Field

[0001] This invention belongs to the technical field of non-contact distributed fault location device detection for power transmission lines, specifically relating to a fault location device location and identification performance testing system based on spatial magnetic field. Background Technology

[0002] Non-contact fault monitoring terminals are deployed on the towers below the three-phase conductors to collect in real time the power frequency magnetic field signal, spatial electric field signal, traveling wave magnetic field signal, and traveling wave electric field signal generated by the three-phase conductors in the surrounding space during a fault. A data center is wirelessly connected to the non-contact fault monitoring terminals to acquire these signals. It then performs effective signal optimization and reconstruction on the power frequency magnetic field signal and spatial electric field signal to obtain the fundamental magnetic field signal and fundamental electric field signal, which are used to determine whether a fault has occurred on the line. If a fault has occurred, the fault point is further located using the traveling wave magnetic field signal and traveling wave electric field signal; otherwise, the line is fault-free. Installation requires no power outage, significantly improving the applicability of distributed fault location technology and ensuring the stable operation of transmission lines.

[0003] The magnetic field-type non-contact power distribution network fault location device is a new type of technical equipment for accurately determining the location of faults in transmission lines. Traditional methods rely on manual inspection, which is time-consuming. This device can achieve high-precision fault location and identification of typical fault types within a length range of 300 meters.

[0004] The device operates based on the principle of space magnetic field detection: the transient current caused by the line fault will generate a local magnetic field signal in space, and the sensor will capture abnormal waveforms covering tens of Hz to hundreds of kHz in a preset frequency band.

[0005] Distributed fault location technology, especially monitoring devices based on non-contact sensing (such as magnetic fields), has been widely used and developed in high-voltage / ultra-high-voltage transmission lines in recent years due to its significant advantages such as no power outage installation, flexible deployment, and precise fault location. This technology involves distributing monitoring terminals on towers to capture in real time the power frequency magnetic / electric field signals generated around the conductor at the moment of a fault (for fault detection) and traveling wave magnetic / electric field signals (for precise fault location).

[0006] However, this technology is highly dependent on the long-term stability and measurement accuracy of the front-end non-contact magnetic field sensor. Devices from different manufacturers inevitably exhibit variations in performance (such as sensitivity, frequency response, linearity, and directivity). If the magnetic field sensor performance is not rigorously tested, it can easily lead to: 1) Fault omission / false alarm: Unable to accurately identify abnormal power frequency signals, missing faults or generating false alarms.

[0007] 2) Deterioration / failure in positioning accuracy: Distortion in traveling wave signal measurement leads to increased fault location error or even failure, seriously affecting fault repair efficiency and power grid safety. Summary of the Invention

[0008] The purpose of this invention is to provide a positioning and identification performance testing system for fault location devices based on spatial magnetic fields, so as to solve the technical problems of low judgment accuracy and poor positioning precision caused by the lack of verification of the magnetic field performance of existing non-contact fault location devices.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A fault location identification performance testing system based on a spatial magnetic field includes: a magnetic field generator, a power frequency current source, and a dual-channel pulse signal source; the magnetic field generator is used to generate a magnetic field to produce a large and highly uniform power frequency and pulsed spatial magnetic field for the device under test; the power frequency current source is used to simulate current under different operating conditions; the dual-channel pulse signal source is used to generate waveform parameters and dual-channel time-difference controllable pulse electromagnetic signals to realize the performance verification of the device under test.

[0010] Preferably, the magnetic field generating device employs a multi-stage Helmholtz coil array.

[0011] Preferably, the multi-stage Helmholtz coil array employs a gradient compensation coil group, including a main coil, a first-order compensation coil, a second-order compensation coil, and an active shielding coil. The main coil is used to generate a basic magnetic field, the first-order compensation coil is used to cancel the secondary gradient, the second-order compensation coil is used to cancel the quaternary gradient, and the active shielding coil is used to suppress end eddy currents.

[0012] Preferably, the above-mentioned magnetic field generating device is equipped with a magnetic field strength and waveform detection module, which, together with the control system, forms a PID closed-loop feedback control of magnetic field strength to achieve high-precision magnetic field control.

[0013] Preferably, the magnetic field center region of the above-mentioned magnetic field generating device is provided with a magnetic field strength and waveform detection module, which is used to measure the magnetic field strength in real time, perform variable parameter PID control in combination with the target field strength, output current, grid voltage and temperature, and adjust the magnetic field strength based on the control system to realize closed-loop feedback control of magnetic field strength.

[0014] Preferably, the magnetic field generating device is equipped with a lifting device for placing the device under test in the magnetic field center region of the magnetic field generating device, and all components in the magnetic field center region are made of non-magnetic materials.

[0015] Preferably, the aforementioned power frequency current source and the aforementioned dual-channel pulse signal source adopt an integrated cabinet for the dual-channel pulse signal source and power frequency current source. The generation of the pulse signal source is controlled by the time difference to simulate the transmission of pulse magnetic field signals at different locations, so as to realize the fault location performance verification of the device under test.

[0016] Preferably, the integrated cabinet for the dual-channel pulse signal source and the power frequency current source controls the power frequency current source to provide a 50 / 60Hz basic magnetic field, and controls the dual-channel pulse signal source to provide different types of fault simulation pulses, and the two signals achieve clock synchronization from the same source.

[0017] Preferably, the above-mentioned power frequency current source outputs a stable power frequency current based on IGBT all-digital inverter technology, with a harmonic distortion rate of <1%.

[0018] Preferably, the above-mentioned dual-channel pulse signal source is based on the trigger channel of FPGA combined with high-speed comparator to realize two independent adjustable nanosecond-level synchronous trigger circuits. The dual pulse signal sources perform PWM modulation and driving independently. Each pulse signal source includes an independent DAC, PID controller, and isolated SiC / GaN driving circuit.

[0019] In this invention, a magnetic field space with better uniformity is generated by a magnetic field generator, with uniformity better than 0.2dB in the core test area. The magnetic field has strong anti-interference ability and effectively cancels the interference of external magnetic fields and the influence of the test sample. At the same time, a standard magnetic field sensor is added for feedback correction. The positioning error test of the device under test is realized by using two magnetic field generators, and the fault type identification test of the device under test is realized by adjusting the pulse magnetic field parameters. This solves the technical problem of low judgment accuracy and poor positioning accuracy caused by the lack of magnetic field performance testing of existing non-contact fault location devices. It achieves the technical effect of testing the magnetic field performance of non-contact fault location devices to improve judgment accuracy and positioning accuracy. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a fault location device based on a spatial magnetic field for detecting its location identification performance in an embodiment of the present invention. Figure 2 This is a schematic diagram of the magnetic field generating device in an embodiment of the present invention; Figure 3 This is a schematic diagram of the integrated cabinet for dual-channel pulse signal source and power frequency current source in an embodiment of the present invention; Figure 4 This is a schematic diagram of the coil of the magnetic field generating device in an embodiment of the present invention; Figure 5 This is a schematic diagram of PID closed-loop control of magnetic field strength in an embodiment of the present invention. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not to a precise scale, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0022] It should be noted that, in order to clearly illustrate the content of this invention, several embodiments are provided to further explain different implementations of the invention. These embodiments are enumerated rather than exhaustive. Furthermore, for the sake of brevity, content mentioned in the preceding embodiments is often omitted in the following embodiments. Therefore, content not mentioned in the later embodiments can be referred to in the preceding embodiments.

[0023] Example 1 A fault location identification performance testing system based on a space magnetic field, such as... Figure 1 As shown, it includes: a magnetic field generator, a power frequency current source, and a dual-channel pulse signal source; the magnetic field generator is used to generate a magnetic field to produce a large and highly uniform power frequency and pulsed spatial magnetic field for the device under test; the power frequency current source is used to simulate current under different operating conditions; the dual-channel pulse signal source is used to generate waveform parameters and dual-channel time-difference controllable pulse electromagnetic signals to realize the performance verification of the device under test.

[0024] As an optional implementation, the magnetic field generator employs a multi-stage Helmholtz coil array.

[0025] As an optional implementation, the multi-stage Helmholtz coil array employs a gradient compensation coil group, including a main coil, a first-order compensation coil, a second-order compensation coil, and an active shielding coil. The main coil is used to generate the basic magnetic field, the first-order compensation coil is used to cancel the secondary gradient, the second-order compensation coil is used to cancel the quaternary gradient, and the active shielding coil is used to suppress end eddy currents.

[0026] As an optional implementation, the magnetic field generator is equipped with a magnetic field strength and waveform detection module, which, together with the control system, forms a PID closed-loop feedback control of the magnetic field strength to achieve high-precision magnetic field control.

[0027] Optionally, the magnetic field generator is not limited to using a multi-stage Helmholtz coil array, equipped with a PID closed-loop feedback control system, to generate an adjustable uniform steady-state / alternating magnetic field with an effective value of 0.1-thousands of A / m.

[0028] Optionally, the control system, acting as the brain of the fault location identification performance testing system based on the space magnetic field, is not limited to coordinating the work of all signal sources, and its core tasks include, but are not limited to: Send start / stop and parameter setting commands to the power frequency current source; Send trigger commands to the dual-channel pulse signal source to precisely control the trigger time, relative delay Δt, and all pulse parameters (amplitude, rise time, width, polarity, waveform) of the two pulses. A synchronization trigger signal is sent to the device under test (DUT) to inform it of the test start time or pulse injection time, ensuring that the device can accurately record and locate the "fault" event. This synchronization signal must be strictly synchronized with the applied pulse signal. Receive feedback information (such as positioning results and measurement data) from the device under test. The control system is not limited to running dedicated control software on a computer and transmitting and communicating data through interfaces such as USB and LAN.

[0029] As an optional implementation, the magnetic field generator is equipped with a magnetic field strength and waveform detection module in the magnetic field center area. This module is used to measure the magnetic field strength in real time, perform variable parameter PID control in combination with the target field strength, output current, grid voltage and temperature, and adjust the magnetic field strength based on the control system to achieve closed-loop feedback control of the magnetic field strength.

[0030] Optionally, the magnetic field strength and waveform detection module adopts FFT analysis function, with a frequency range covering 1Hz-400kHz. Different frequency signals are captured through different bandwidths to achieve faster measurement. At the same time, the fiber optic interface allows for remote control, and the measurement results are not affected by external interference.

[0031] As an optional implementation, the magnetic field generator is equipped with a lifting device for placing the device under test in the magnetic field center region of the magnetic field generator. All components in the magnetic field center region are made of non-magnetic materials.

[0032] As an optional implementation, the power frequency current source and the dual-channel pulse signal source adopt an integrated cabinet of dual-channel pulse signal source and power frequency current source. The generation of the pulse signal source is controlled by the time difference to simulate the transmission of pulse magnetic field signals at different locations, so as to realize the fault location performance verification of the device under test.

[0033] As an optional implementation, the integrated cabinet of dual-channel pulse signal source and power frequency current source controls the power frequency current source to provide a 50 / 60Hz basic magnetic field, and controls the dual-channel pulse signal source to provide different types of fault simulation pulses, and the two signals are synchronized with the same source clock.

[0034] As an optional implementation, the power frequency current source outputs a stable power frequency current based on IGBT all-digital inverter technology, with a harmonic distortion rate of <1%.

[0035] Optionally, the power frequency current source is based on IGBT fully digital inverter technology, which outputs a stable power frequency current (50Hz) through a program, with a harmonic distortion rate of <1%.

[0036] As an optional implementation, the dual-channel pulse signal source is based on the trigger channel of the FPGA combined with the high-speed comparator to realize two independent adjustable nanosecond-level synchronous trigger circuits. The two pulse signal sources perform PWM modulation and driving independently. Each pulse signal source includes an independent DAC, PID controller, and isolated SiC / GaN driving circuit.

[0037] The dual-channel pulse signal source uses a high-precision timing control unit, supports ns-level delay synchronization, and generates two independent adjustable pulses (pulse width 0~1000ms, minimum step size 0.1μs).

[0038] Specifically, the magnetic field generating device is not limited to, for example, Figure 2 As shown, a set consists of two units, each capable of generating a magnetic field simultaneously. It employs a multi-stage Helmholtz coil array, coupled with a high-precision magnetic field strength and waveform detection module to form a PID closed-loop feedback control. Internally, it includes a lifting device for placing the test object in the central area of ​​the magnetic field generator. All components within the central magnetic field area are made of non-metallic materials to avoid signal interference from the generated magnetic field.

[0039] Specifically, the integrated cabinet for dual-channel pulse signal sources and power frequency current sources is not limited to, for example... Figure 3 As shown, it includes a power frequency current source and a dual-channel pulse signal source, which can communicate with a host computer to apply current to the magnetic field generator. The control system is not limited to simultaneously outputting two types of excitation signals: the power frequency current source → providing a 50 / 60Hz basic magnetic field; and the dual-channel pulse signal source → injecting fault simulation pulses; the two signals are synchronized with the same clock source within the control system.

[0040] The fault location and identification performance testing system based on spatial magnetic field applies current excitation signals to two completely independent magnetic field generators through a dual-path pulse signal source and a power frequency current source. Two fault location devices are placed within the two magnetic field generators. The pulse signal source is controlled by a high-precision time difference to simulate the emission of pulsed magnetic field signals from different locations in a power line, thus verifying the performance of the non-contact fault location device. Verification Channel 1: The magnetic field generator receives power frequency + pulse signal → generates a mixed magnetic field → acts on the non-contact fault location device → its built-in magnetic field strength and waveform detection module transmits the measurement data back to the control system.

[0041] Verification Channel 2: The magnetic field generator receives the same power frequency + pulse signal → generates a magnetic field with the same parameters → applies it to the fault location device → its magnetic field strength and waveform detection module independently transmits the measurement data back to the control system.

[0042] Furthermore, the magnetic field generating device has high uniformity, and the generating coil is not limited to, for example, Figure 4As shown, taking 0.2 dB (with the center point as a reference, a 60% range, and the area being larger than the tested object) as an example, in terms of structure, a gradient compensation coil group is adopted, mainly including a main coil, a first-order compensation coil (diameter 1.15D, number of turns 18%), a second-order compensation coil (diameter 0.85D, number of turns 7%), and an end shielding coil (diameter 1.3D, number of turns 5%). A dynamic control method is adopted, which dynamically adjusts the current ratio of the compensation coil through real-time feedback of the spatial magnetic field gradient.

[0043] Dual-channel pulse sources enable high-precision pulse current triggering, not limited to nanosecond-level synchronous triggering circuits. The trigger channel, based on FPGA and a high-speed comparator, achieves hardware-level low latency (<5ns). It supports external trigger input / output, enabling sub-microsecond synchronization with external devices. Dual-channel independent PWM modulation and driving are employed, with each pulse source containing an independent DAC (16-bit+), PID controller, and isolated SiC / GaN driver circuit.

[0044] For magnetic field strength PID closed-loop control, it is not limited to, such as Figure 5 As shown, the thermal drift compensation value is determined based on a temperature sensor and a thermal drift compensator. Feedforward compensation calculations are then performed in the feedforward compensator, taking into account the target field strength, load current, and grid voltage. Magnetic field data from the magnetic sensor array is processed using a Kalman filter. Variable parameter PID control is then implemented using the feedforward compensation, followed by PWM control output generated by a PWM generator. Power compensation is then performed using a power amplifier to obtain the control output acting on the magnetic field coil, enabling closed-loop control of the magnetic field strength. By fusing multi-sensor data through a Kalman filter to estimate the true field strength, combined with a coil impedance feedforward model incorporating temperature-frequency coupling characteristics, and variable parameter PID control based on load phase angle identification, a field strength stability of ±0.1% is achieved.

[0045] When performing performance testing on a device under test, the following steps are not limited to: S1: Establish a line topology mapping model and calculate the magnetic field strength, time parameters, etc. at the target location; S2: The coil is driven by a dual-path pulse and a power frequency source to generate power frequency and different types of fault pulse magnetic fields respectively; S3: Non-contact distributed device (device under test) collects magnetic field measurement values ​​and timestamps of each node, performs fault identification and location, and obtains test data; S4: Calculate the amplitude error, time synchronization error, positioning error, and fault type identification accuracy of the test data obtained by the device under test using standard magnetic field strength, time difference, time parameters, etc.

[0046] In this embodiment, a gradient-compensated multilayer Helmholtz coil generates a more uniform magnetic field space. Its winding distribution satisfies the magnetic field uniformity of ±0.2dB in the central region (central region Φ≥60cm), and the magnetic field has strong anti-interference capability, which can effectively cancel the interference of external magnetic fields and the influence of the test sample. A standard magnetic field sensor is added for feedback correction. An adaptive field strength control module based on Kalman filtering realizes closed-loop feedback control of magnetic field strength, thereby achieving precise magnetic field environment control of the device under test. A dual-channel high-precision pulse source is used, with an output delay difference of <100ns and supports power frequency / different types of pulse waveform injection, realizing positioning error and fault identification type testing.

Claims

1. A fault location identification performance testing system based on a space magnetic field for fault location devices, characterized in that, include: Magnetic field generator, power frequency current source, and dual-channel pulse signal source; A magnetic field generator is used to generate a magnetic field, thereby producing a large and highly uniform power frequency and pulsed spatial magnetic field for the device under test. Power frequency current source devices are used to simulate current under different operating conditions; A dual-channel pulse signal source is used to generate waveform parameters and dual-channel time-difference controllable pulse electromagnetic signals to achieve performance verification of the device under test.

2. The fault location identification performance testing system based on spatial magnetic field as described in claim 1, characterized in that, The magnetic field generating device uses a multi-stage Helmholtz coil array.

3. The fault location identification performance testing system based on spatial magnetic field as described in claim 2, characterized in that, The multi-stage Helmholtz coil array employs a gradient compensation coil group, including a main coil, a first-order compensation coil, a second-order compensation coil, and an active shielding coil. The main coil is used to generate a basic magnetic field, the first-order compensation coil is used to cancel the second-order gradient, the second-order compensation coil is used to cancel the fourth-order gradient, and the active shielding coil is used to suppress end eddy currents.

4. The fault location identification performance testing system based on spatial magnetic field as described in claim 1, characterized in that, The magnetic field generating device is equipped with a magnetic field strength and waveform detection module, which, together with the control system, forms a PID closed-loop feedback control of the magnetic field strength to achieve high-precision magnetic field control.

5. The fault location identification performance testing system based on spatial magnetic field as described in claim 4, characterized in that, The magnetic field generator is equipped with a magnetic field strength and waveform detection module in the magnetic field center area. This module is used to measure the magnetic field strength in real time, perform variable parameter PID control based on the target field strength, output current and temperature, and adjust the magnetic field strength based on the control system to achieve closed-loop feedback control of the magnetic field strength.

6. The fault location identification performance testing system based on spatial magnetic field as described in claim 1, characterized in that, The magnetic field generator is equipped with a lifting device for placing the device under test in the magnetic field center region of the magnetic field generator. All components in the magnetic field center region are made of non-magnetic materials.

7. The fault location identification performance testing system based on spatial magnetic field as described in claim 1, characterized in that, The power frequency current source and the dual-channel pulse signal source adopt an integrated cabinet for the dual-channel pulse signal source and the power frequency current source. The generation of the pulse signal source is controlled by the time difference to simulate the transmission of pulse magnetic field signals at different locations, so as to realize the fault location performance verification of the device under test.

8. The fault location identification performance testing system based on spatial magnetic field as described in claim 7, characterized in that, The integrated cabinet for the dual-channel pulse signal source and the power frequency current source controls the power frequency current source to provide a 50 / 60Hz basic magnetic field, and controls the dual-channel pulse signal source to provide different types of fault simulation pulses, and the two signals are synchronized with the same source clock.

9. The fault location identification performance testing system based on spatial magnetic field as described in claim 7, characterized in that, The power frequency current source outputs a stable power frequency current based on IGBT all-digital inverter technology, with a harmonic distortion rate of <1%.

10. The fault location identification performance testing system based on spatial magnetic field as described in claim 7, characterized in that, The dual-channel pulse signal source is based on the trigger channel of FPGA combined with high-speed comparator to realize two independent adjustable nanosecond-level synchronous trigger circuits. The two pulse signal sources perform PWM modulation and driving independently. Each pulse signal source includes an independent DAC, PID controller and isolated SiC / GaN driving circuit.

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