A high-precision fault inversion method with automatic feedback without static error

Abstract

The present invention discloses a high-precision fault inversion method with automatic feedback without static error. The method comprises the following steps: setting preset short circuit, grounding and anti-false operation fault scenarios, applying high-fidelity voltage and current signals on the primary side through software and hardware control, verifying the fault analysis, processing function and performance of the intelligent switch, and verifying the fault processing capability of a single device. At the hardware level, the fault inversion test system transfers the load side impedance to the source side through impedance transmission, controls the current using current feedback, drives a large current MOS tube to generate a nonlinear voltage to drive the load loop to obtain a high-precision primary signal through a fast-response automatic feedback control circuit without static error, and then obtains a high-precision measurement result by using a 2-way multi-channel high-precision synchronous sampling measurement method. At the software level, for steady-state signals, the primary output signal is sampled in real time, and the voltage, current and power sources are compensated and corrected according to the load difference of the switch to be tested. For transient signals, the voltage, current and power sources are periodically calibrated and adjusted for amplitude and phase in segments according to the current output range.

Description

Technical Field

[0001] The invention relates to a high-precision fault inversion method without static error and automatic feedback, belonging to the technical field of primary and secondary integrated switchgear detection. Background Art

[0002] At present, in the detection of integrated primary and secondary switchgear, the standard range of current measurement is 0-1000A, and the standard range of voltage measurement is 0-11kV, and transient faults need to be tested and analyzed at the same time. Primary side fault injection requires accurate simulation of current, voltage amplitude, phase and transient characteristics in a wide range, so the current and voltage injected by existing detection equipment cannot be continuously adjusted. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a high-precision fault inversion method without static error automatic feedback to solve the technical problems existing in the prior art.

[0004] The technical solution adopted by the present invention is: a high-precision fault inversion method with automatic feedback without static error, the method is: setting preset short circuit, grounding and anti-false operation fault scenarios, applying high-fidelity voltage and current signals on the primary side through software and hardware control, verifying the fault analysis, processing functions and performance of the intelligent switch, and verifying the fault handling capability of a single device. At the hardware level, the fault inversion test system transfers the load side impedance to the source side through impedance transfer, and controls the current using current feedback. Through a fast-response automatic feedback control circuit without static error, a large current MOS tube is driven to generate a nonlinear voltage to drive the load loop to obtain a high-precision primary signal, and then a 2-way multi-channel high-precision synchronous sampling measurement method is used to obtain a high-precision measurement result; at the software level, for steady-state signals, the primary output signal is collected in real time, and the voltage, current and power sources are compensated and corrected according to the load differences of the switch to be tested; for transient signals, the voltage, current and power sources are regularly calibrated and adjusted for amplitude and phase in segments according to the current output range.

[0005] Preferably, the high-fidelity voltage and current signals applied on the primary side are applied using a voltage and current power source, the voltage and current power source is connected to a voltage and current booster, the voltage and current booster is connected to the switch to be tested through a high-voltage cable, the high-voltage cable connected to the switch to be tested recovers the injected current and voltage through a voltage transformer and a current transformer, the recovered voltage and current are fed back to the voltage and current power source, and the voltage and current power source performs closed-loop real-time adjustment.

[0006] Preferably, the above-mentioned 2-way multi-channel high-precision synchronous sampling measurement method: the voltage and current signals of the circuit of 16 channels are converted into AC input signals with an amplitude of -5V to +5V through a voltage transformer and a current transformer, and then filtered by a low-pass filter circuit, and the filtered signal is synchronously sampled and held by a sampling / holding circuit to be converted into a discrete signal. The sampling / holding circuit adopts a synchronous sampling and time-sharing conversion method, that is, a circuit composed of two 8-channel synchronous sampling and synchronous holding A / D converters is adopted. The first stage of the circuit adopts a low zero drift amplifier circuit, and the second stage adopts a low-pass filter follower. At each sampling point, the A / D converter must perform A / D conversion on multiple channels separately, calculate the phase difference of each channel point, and use frequency measurement and tracking phase-locked method to synchronize the 2-way A / D sampling again.

[0007] Preferably, the voltage and current signals of the above-mentioned 16-channel circuit are collected by a multifunctional standard meter capable of collecting 2 channels with a total of 16 channels, each channel including 4U channels and 4I channels. The multifunctional standard meter samples the analog signals of 2 channels and 16 channels, and calculates various voltages, currents and powers.

[0008] Preferably, the first 8-channel analog signal has a voltage range of 0-456V, is sampled by resistor voltage division, the output end is connected to the amplifier OP2177 follower, and the analog switch is used to switch the gear, and sent to AD for simultaneous sampling; the current range is 0-20A, which is converted into a small current signal through a current transformer, the small current signal is 0-20mA, and the small current signal is converted into a voltage signal through a sampling resistor, and the analog switch is used to switch the gear, and finally sent to AD for simultaneous sampling; the second 8-channel analog signal has a voltage range of 0-10V, uses a differential input, is output by the amplifier OP2177, is sent to an instrument amplifier with gain to process the signal, and finally is sent to AD for simultaneous sampling.

[0009] Preferably, the processed signals of the first 8-channel and the second 8-channel are sent to the AD sampler, and the AD sampler uses CPLD and DSP to control two ADs; after the AD sampler processes the signal, the sampling data is sent to the CPLD cache through a high-speed serial bus to reach the cache capacity, and the DSP reads out the 16-channel sampling data collected by the DSP at one time, and simultaneously calculates the voltage, current, power and harmonics.

[0010] Preferably, the above-mentioned boost current booster includes a booster and a current booster; the low-voltage side of the booster is connected to the voltage signal output by the power source, one end of the high-voltage side is connected to the input port of the switch to be tested, and the other end is connected to the ground; the output end of the current booster is in line with the primary side voltage and current of the switch to be tested, and the output end of the current booster is connected to the switch to be tested using a high-voltage isolation current conversion device.

[0011] Preferably, the transformer primary side of the current conversion device is wound with N turns, and the secondary side is a copper rod passing through the core, and the voltage between the front and rear stages of the transformer is proportional to the number of turns.

[0012] Beneficial effects of the present invention: Compared with the prior art, the present invention can realize accurate simulation of a large range of measurement ranges (current, voltage amplitude, phase and transient characteristics) in primary-side fault injection, and realize continuous adjustment of the injected current and voltage, effectively solving the problem that the injected current and voltage of the existing detection equipment cannot be continuously adjusted. For transient signals, amplitude and phase calibration and adjustment are regularly performed in segments according to the current output range to ensure that the amplitude, phase, response time and other performance of the primary output signal are reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The schematic diagram of the booster and current raiser of the present invention;

[0014] Figure 2 This is the block diagram of the dual-channel synchronous sampling measurement system.

[0015] Figure 3 This is a schematic diagram of the standard table access detection system. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0017] Example 1: Figure 1-Figure 3 As shown in the figure, a high-precision fault inversion method without static error automatic feedback is provided. The method comprises the following steps: setting preset short circuit, grounding and anti-false operation fault scenarios, applying high-fidelity voltage and current signals on the primary side through software and hardware control, verifying the fault analysis, processing function and performance of the intelligent switch, and verifying the fault processing capability of a single device. At the hardware level, the fault inversion test system transfers the load side impedance to the source side through impedance transfer, and controls the current by current feedback. Through a fast-response static error-free automatic feedback control circuit, a large current MOS tube is driven to generate a nonlinear voltage to drive the load loop to obtain a high-precision primary signal, and then a 2-way multi-channel high-precision synchronous sampling measurement method is used to obtain a high-precision measurement result. At the software level, for steady-state signals, the primary output signal is sampled in real time, and the voltage, current and power sources are compensated and corrected according to the load difference of the switch to be tested. For transient signals, the voltage, current and power sources are periodically calibrated and adjusted in segments according to the current output range to ensure that the amplitude, phase, response time and other performance of the primary output signal are reliable.

[0018] Preferably, the above-mentioned primary side applies high-fidelity voltage and current signals using a voltage and current power source, the voltage and current power source is connected to a voltage and current booster, the voltage and current booster is connected to the switch to be tested through a high-voltage cable, the high-voltage cable connected to the switch to be tested recovers the injected current and voltage through a voltage transformer and a current transformer, the recovered voltage and current are fed back to the voltage and current power source, the voltage and current power source performs closed-loop real-time adjustment, and the voltage recovered by the voltage transformer is connected to a high-precision three-phase standard meter as a benchmark for accuracy evaluation.

[0019] Voltage boosting principle (taking phase A as an example): Use a 10 / 0.22kV boost PT to connect the voltage signal Uan output by the power source to the low-voltage side. The output voltage on the high-voltage side is 10 / 0.22*Uan (kV). When the low-voltage side inputs 220V, the high-voltage side output can reach 10kV.

[0020] Preferably, the above-mentioned two-way multi-channel high-precision synchronous sampling measurement method includes a two-way synchronous sampling measurement system, such as Figure 2 As shown, the dual-channel synchronous sampling measurement system (multi-function standard meter) includes two 16 channels, a sampling board, a connecting board and a main board (ARM), each 8 channels (including 4U channels and 4I channels) are connected to a sampling board, the sampling board is connected to the connecting board, the connecting board is connected to the main board, the connecting board is also connected to the LCD conversion board and the front panel and the power board, the power board is connected to the power terminal, the main board is connected to the communication interface, the synchronous sampling measurement method is: the voltage and current signals of the 16-channel circuit are converted into AC input signals with an amplitude of -5V to +5V through the voltage transformer and the current transformer, and then A low-pass filter circuit is used to filter it, and the filtered signal is synchronously sampled and held through a sampling / holding circuit to turn it into a discrete signal. The sampling / holding circuit adopts a synchronous sampling and time-sharing conversion method, that is, a circuit composed of two 8-channel synchronous sampling and synchronous holding A / D converters. The first stage of the circuit adopts a low zero drift amplifier circuit, and the second stage adopts a low-pass filter follower. At each sampling point, the A / D converter must perform A / D conversion on multiple channels separately, calculate the phase difference of each channel point, and use frequency measurement and tracking phase-locked method to synchronize the 2-way A / D sampling again.

[0021] The design concept of synchronous sampling and time-sharing conversion can save costs. Only two 8-channel synchronous sampling and synchronous holding A / D converters are used. The first stage of the circuit adopts a low zero-drift amplifier circuit to improve the anti-interference ability of the input signal. The second stage adopts a low-pass filter follower to increase the output impedance and reduce the influence of the current in the circuit. At the same time, the angular difference caused by the phase of each channel affected by the resistance and capacitance is reduced. The present invention can achieve improved measurement accuracy and speed.

[0022] The multi-function standard meter is designed with a multi-channel accuracy test system in conjunction with the three-phase power to simulate actual working conditions on site and improve detection efficiency. The multi-function standard meter adopts dual high-speed processors and a large-scale logic array structure. The ADI 400MHz DSP combined with the CPLD is responsible for sampling and calculation, and the ARM is responsible for display and communication.

[0023] Preferably, the voltage and current signals of the above-mentioned 16-channel circuit are collected by a multifunctional standard meter capable of collecting 2 channels with a total of 16 channels, each channel including 4U channels and 4I channels. The multifunctional standard meter samples the analog signals of 2 channels and 16 channels, and calculates various voltages, currents and powers.

[0024] Preferably, the first 8 channels are analog large signals with a voltage range of 0-456V. They are sampled by high-precision resistor voltage division, and the output end is connected to the amplifier OP2177 to follow and increase the output impedance, and the analog switch is used to switch the gear, and the signals are sent to AD for simultaneous sampling; the current range is 0-20A, which is converted into a small current signal (0-20mA) by a current transformer, and then converted into a voltage signal by a sampling resistor, and the analog switch is used to switch the gear, and finally the signals are sent to AD for simultaneous sampling; the second 8 channels are analog small signals with a voltage range of 0-10V, and differential input is used to improve the anti-interference ability of the signal. The output impedance is increased by using the amplifier OP2177 output, and the signals are sent to an instrument amplifier with gain to process the signals, and the high-frequency clutter signals in the environment are filtered out, and finally the signals are sent to AD for simultaneous sampling; the 2-channel 16 analog channels use high-precision low-temperature drift devices to ensure that the adopted signals change less than 10ppm over time and temperature; the addition of a bandpass filter eliminates the influence of the environment on the signal, and ensures that the adopted accuracy of the instrument reaches 0.5%.

[0025] Preferably, the processed signals of the first 8-channel and the second 8-channel are sent to an AD sampler, and the AD sampler uses CPLD and DSP to control two ADs to achieve sampling synchronization, and the synchronization phase error is less than 0.1us.

[0026] Preferably, the AD sampler processes the signal and then sends the sampled data to the CPLD cache through a high-speed serial bus to reach the cache capacity. The DSP reads it out at one time to reduce the DSP occupancy rate. The 16-channel sampled data collected by the DSP simultaneously calculates the voltage, current, power and harmonics to ensure that the data of each cycle is involved in the calculation, realizing seamless sampling and calculation functions. This not only improves the data accuracy of the instrument, but also improves the real-time performance.

[0027] Preferably, the data calculated by the DSP is sent to the ARM via a parallel bus, and the ARM collects the calculated data to realize digital display, graphic display, statistics, and analysis functions according to customer needs.

[0028] Preferably, the multifunctional standard meter is provided with an Ethernet communication interface and a serial communication interface, which is convenient for communicating with various types of instruments and meters. The Ethernet communication interface adopts an RJ45 interface, 10 / 100M adaptive, and the serial communication interface adopts RS232 / RS485, and its configuration parameters can be read and compared through the protocol to check whether the parameter settings are correct.

[0029] How to connect the multi-function meter to the test system Figure 3 As shown. The current and voltage signals injected into the switch on the high-voltage side are collected as reference signals; the current and voltage signals on the PT and CT sides are collected at the same time, and the ratio difference and angle difference are tested with high precision with the reference signal. This method reduces the accuracy requirements of the primary signal power source. As long as the source output remains stable, high-precision test results can be obtained, and automated testing can be achieved.

[0030] Preferably, the voltage booster and current booster comprises a voltage booster and a current booster; the low voltage side of the voltage booster is connected to the voltage signal output by the power source, one end of the high voltage side is connected to the input port of the switch to be tested, and the other end is connected to the ground, so that the switch to be tested can collect the primary voltage. The requirements of simulating high voltage lines are met; the output end of the current booster is in the same line with the primary side voltage and current of the switch to be tested, and the output end of the current booster is connected to the switch to be tested using a high voltage isolation type current conversion device.

[0031] Preferably, the transformer primary side of the current conversion device is wound with N turns, and the secondary side is a copper rod passing through the core, and the voltage between the front and rear stages of the transformer is proportional to the number of turns.

[0032] Current conversion principle of current booster: Since the voltage and current are on the same line on the primary side, a high-voltage isolated current conversion device must be used. In current conversion, the principle of energy conservation on the primary and secondary sides of the transformer is used. The primary side (IA, IN) is wound with 6 turns, and the secondary side is a copper rod passing through the core (equivalent to 1 turn of coil). The voltage before and after the transformer is proportional to the number of turns. Assuming that the primary voltage is 6U, the primary current is I initial, the secondary voltage is U, and the secondary current is I times, there is 6U*I initial=U*I times, that is, I times=6 I initial, and the current conversion is increased by 6 times (ideal situation). In fact, due to the existence of transformer leakage inductance, the efficiency of transformer energy transfer cannot reach 100%, and the primary current and secondary current cannot be transmitted according to the above-set parameters. Then, by adding a high-precision sampling CT to the copper rod, the current of the copper rod is monitored in real time and fed back to the power source. Through real-time adjustment of the closed loop, the output accuracy of the large current is guaranteed. At the same time, the output current of the high-precision sampling CT is connected to the high-precision three-phase standard meter as a benchmark for accuracy evaluation.

[0033] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A high-precision fault inversion method without static error automatic feedback, characterized in that: The method is: setting preset short circuit, grounding and anti-false operation fault scenarios, applying high-fidelity voltage and current signals on the primary side through software and hardware control, verifying the intelligent switch fault analysis, processing functions and performance, and verifying the fault handling capability of a single device. At the hardware level, the fault inversion test system transfers the load side impedance to the source side through impedance transfer, and controls the current using current feedback. Through a fast-response, zero-static error automatic feedback control circuit, a large current MOS tube is driven to generate a nonlinear voltage to drive the load loop to obtain a high-precision primary signal, and then a 2-way multi-channel synchronous sampling measurement method is used to obtain the measurement result; at the software level For steady-state signals, the primary output signal is collected in real time, and the voltage, current and power source performs compensation and correction according to the load difference of the switch to be tested; for transient signals, the voltage, current and power source periodically performs amplitude and phase calibration and adjustment in segments according to the current output range; the primary side applies high-fidelity voltage and current signals using a voltage and current power source, which is connected to a booster and current booster, which is connected to the switch to be tested through a high-voltage cable, and the high-voltage cable connected to the switch to be tested collects the injected current and voltage through a voltage transformer and a current transformer, and the collected voltage and current are fed back to the voltage and current power source, which performs closed-loop real-time adjustment; 2-way multi-channel synchronous sampling measurement method: the voltage and current signals of the 16-channel circuit are converted into an AC input signal with an amplitude of -5V to +5V through a voltage transformer and a current transformer, and then filtered by a low-pass filter circuit. The filtered signal is synchronously sampled and held through a sampling / holding circuit to become a discrete signal. The sampling / holding circuit adopts a synchronous sampling and time-sharing conversion method, that is, a circuit composed of two 8-channel synchronous sampling and synchronous holding A / D converters. The first stage of the circuit adopts a low zero drift amplifier circuit, and the second stage adopts a low-pass filter follower. At each sampling point, the A / D converter performs A / D conversion on multiple channels respectively, calculates the phase difference of each channel point, and uses frequency measurement and tracking phase-locked method to synchronize the 2-way A / D sampling again; The voltage and current signals of the 16-channel circuit are collected by a multifunctional standard meter that can collect 2 channels with a total of 16 channels. Each channel includes 4U channels and 4I channels. The multifunctional standard meter samples the analog signals of 2 channels with 16 channels and calculates various voltages, currents and powers. The first 8-channel analog signal has a voltage range of 0-456V. It is sampled through resistor voltage division, and the output end is connected to the amplifier OP2177 follower. The analog switch is used to switch the gear and send it to AD for simultaneous sampling. The current range is 0-20A, which is converted into a small current signal through a current transformer. The small current signal is 0-20mA. The small current signal is then converted into a voltage signal through a sampling resistor. The analog switch is used to switch the gear and finally sent to AD for simultaneous sampling. The second 8-channel analog signal has a voltage range of 0-10V. It uses differential input, is output by the amplifier OP2177, is sent to an instrument amplifier with gain to process the signal, and finally is sent to AD for simultaneous sampling. The processed signals of the first 8-channel and the second 8-channel are sent to the AD sampler, which uses CPLD and DSP to control two ADs. After the AD sampler processes the signal, it sends the sampled data to the CPLD cache through a high-speed serial bus to reach the cache capacity. The DSP reads out the 16-channel sampled data collected by the DSP at one time and calculates the voltage, current, power and harmonics at the same time. The booster and current booster includes a booster and a current booster; the low voltage side of the booster is connected to the voltage signal output by the power source, one end of the high voltage side is connected to the input port of the switch to be tested, and the other end is connected to the ground; the output end of the current booster is in the same line with the primary side voltage and current of the switch to be tested, and the output end of the current booster is connected to the switch to be tested using a high voltage isolation type current conversion device; The primary side of the transformer of the current conversion device is wound with N turns, and the secondary side is a copper rod passing through the core. The voltage between the front and rear stages of the transformer is proportional to the number of turns.

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