Transient voltage and current rapid protection method, system, equipment and medium

Abstract

The invention discloses a transient voltage and current rapid protection method, system and device and a medium, and belongs to the technical field of power distribution network transient voltage and current protection, and the method comprises the steps: obtaining an analog signal through a sensing module, and carrying out the analog signal processing through a main control module; the main control module carries out filtering elimination on the digital signal after digital conversion by using an FPGA (Field Programmable Gate Array); and the main control module executes range adjustment, fault detection and protection control based on the filtered data, drives the parallel protection module to protect the element and records the system state. According to the transient voltage and current rapid protection method, the sensing module acquires signals, the master control module performs isolation conditioning and digital conversion, the FPGA performs parallel real-time filtering to eliminate interference, the self-adaptive range and multi-parameter fault accurate criterion is adopted, and an optical coupler isolation driving protection element is adopted. Microsecond-level high-speed response and high-reliability protection are achieved, fault expansion is effectively prevented, and equipment safety is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transient voltage and current protection of power distribution network, and particularly relates to a transient voltage and current fast protection method, system, device and medium. BACKGROUND

[0002] The existing training is generally carried out in a "non-live" environment, which makes the operating personnel often appear psychological tension and action deformation in the actual operation process, and is extremely likely to cause personal electric shock and cause personal injury accidents.

[0003] The live operation of the power distribution network is significantly different from the operation of the extra-high voltage transmission line. The operation of the extra-high voltage transmission line is characterized by large electric field intensity of the operation space and long operation distance, and the operating personnel need to wear isolation clothes for operation and operate on the equipotential place of the transmission line to ensure the personal safety of the operating personnel. The live operation of the power distribution network does not require the operating personnel to wear isolation clothes, and only necessary protective measures are needed. Since the spatial distance of the three-phase conductor is small, if the operating personnel operates improperly, personal electric shock may occur, two-phase short circuit or single-phase grounding short circuit of the three-phase conductor may occur, and ultimately personal injury accidents may occur. In addition, the traditional mechanical switch cannot meet the requirement of fast cutting due to the slow response time (usually between 10-20 ms). SUMMARY

[0004] In view of the above problems, the present application is proposed.

[0005] Therefore, the present application aims to solve the technical problems of slow response speed, weak anti-interference ability, single fault criterion and poor adaptability of the transient voltage and current protection system in the prior art.

[0006] To solve the above technical problems, the present application provides the following technical scheme: a transient voltage and current fast protection method, comprising, The analog signal is obtained by the sensing module, and the analog signal processing is performed by the main control module. The main control module filters the digital signal after digital conversion by using FPGA. The main control module performs range adjustment, fault detection and protection control based on the filtered data, drives the parallel protection module protection element and records the system state.

[0007] As a preferred scheme of the transient voltage and current fast protection method, the main control module comprises isolation, conditioning and digital conversion in the analog signal processing. The analog signal is obtained by the sensing module, and the analog signal processing is performed by the main control module. The main control module filters the digital signal after digital conversion by using FPGA. The main control module performs range adjustment, fault detection and protection control based on the filtered data, drives the parallel protection module protection element and records the system state. The CT secondary current signal and the divider secondary voltage signal are isolated and converted to output a differential signal. The signal conditioning circuit performs preliminary filtering and amplitude adjustment on the differential signal; Meanwhile, the fusion algorithm is used to detect whether the boost system has ground fault or phase-to-phase fault.

[0008] As a preferred scheme of the transient voltage and current fast protection method, the digitization conversion comprises analog-digital conversion on the conditioned analog signal. The sampling rate is set, and the converted digital data is output to the digital filter through the interface; The high-frequency PWM driving signal is generated, isolated through the protection isolation driving circuit, and used to drive the protection element to perform the protection action; The boost system operation information is displayed, and the fault information is recorded.

[0009] As a preferred scheme of the transient voltage and current fast protection method, the filtering and elimination of the digitized digital signal by the FPGA comprises construction of a finite impulse response digital filter by the FPGA in a parallel manner. The FPGA reads the channel data from the ADC and adopts the edge-receiving and filtering strategy. The filtering calculation performs the multiplication and addition operation in parallel by the DSP unit of the FPGA.

[0010] As a preferred scheme of the transient voltage and current fast protection method, the main control module comprises a selection of a main control chip, a setting of a peripheral interface, a three-phase voltage divider for voltage division processing, and a setting of a potentiometer adjustable circuit. The voltage signal after voltage division is further conditioned by the board hardware circuit, including filtering and amplitude limiting. The low-voltage side three-phase CT selects a current transformer to collect three-phase current, adopts an overcurrent protection circuit to send an alarm signal and take protection measures when the current exceeds the range of the CT, and sets a programmable threshold adjustment circuit. An external AD chip is selected, a sampling rate and a cycle sampling are set, the AD chip carries out synchronous sampling, the current and voltage change conditions are detected by comparing the instantaneous value of the current cycle with the instantaneous value of the previous cycle, a dead zone of ±15 degrees is set at the zero-crossing position, and the misjudgment caused by signal fluctuation at the zero-crossing position is eliminated by combining a hardware circuit and a software algorithm; The wide-range voltage is collected by combining a high-voltage isolation transformer and a variable-ratio voltage dividing circuit, switching between low voltage and high voltage is carried out by switching the voltage dividing ratio, a harmonic filter circuit is added, a low-pass filter and a band-pass filter are combined, high-frequency harmonics and interference signals of a set frequency are filtered out, and only the fundamental wave and useful low-order harmonics are allowed to pass.

[0011] The preferred technical scheme in the embodiment of the application has the beneficial effects that: through a plurality of hardware and software measures (such as a potentiometer adjustment, threshold comparison, overcurrent protection, synchronous sampling, and dead zone setting), the measurement accuracy of the voltage and current signals and the accuracy of the protection action are improved, and misjudgment is effectively reduced.

[0012] As a preferred scheme of the transient voltage and current fast protection method, the main control module further comprises a multi-parameter criterion method using normal system three-phase voltage as a parameter adjustment basis, and using a hardware-synthesized zero sequence voltage and three-phase current as a criterion, the three-phase voltage is synthesized by a hardware circuit to obtain the zero sequence voltage, and the three-phase current signal is introduced into the main control chip, and a plurality of algorithms are used in the main control chip to comprehensively consider the relationship between the voltage and the current. A start button is arranged, the system starts running by triggering the start button, a parameter adjustment circuit is designed, the phase and amplitude of the three-phase voltage and current are compensated and adjusted by adjusting a potentiometer or using a digital potentiometer, the main control chip adjusts the parameters of the coefficient setting circuit according to the actual measurement condition by outputting a corresponding control signal through a DAC. The three-phase voltage is synthesized by a hardware circuit to obtain the zero sequence voltage, the three-phase voltage signals are added and divided by 3 by a summing circuit composed of an operational amplifier and resistors and capacitors to obtain the zero sequence voltage, a control relay or an analog switch is used for switching control, the main control chip outputs a corresponding control signal to control the on-off of the control relay or the analog switch to switch different voltage dividing circuits and measurement channels according to the working voltage level of the system.

[0013] The preferred technical scheme in the embodiment of the application has the beneficial effects that: the multi-parameter criterion and the hardware-synthesized zero sequence voltage are used, the parameter adjustment circuit and the switching control are combined, and the reliability of fault detection and the adaptability of the system to different voltage levels are enhanced.

[0014] As a preferred embodiment of the transient voltage and current fast protection method described in this invention, the main control module further includes a main control chip that outputs a corresponding control signal through an optocoupler isolation circuit to drive the trigger circuit of the thyristor, and at the same time, an overcurrent and overvoltage protection circuit is set. Two input channels are configured: one for receiving external control signals and the other for receiving a reset signal from the PLC. When the system malfunctions or needs to be restarted, the PLC sends a reset signal, which is then introduced to the main control chip via hardware circuitry to restore the system to its initial state. The input circuitry uses optocoupler isolation technology to electrically isolate external signals from the main control chip. One output channel is configured to control the boost system. When the system detects a fault or requires boost operation, the main control chip outputs a corresponding control signal through the output circuitry to drive the boost system to perform the boost operation. The output circuitry uses relays or power transistors as switching elements. An automatic delay reset circuit can be set with a delay time of 50ms. When the system detects that the fault has been cleared, the delay timer will start automatically and send a reset signal after 50ms to restore normal operation.

[0015] The preferred technical solution in the embodiments of the present invention has the following beneficial effects: by using optocoupler isolation, input-output channels and automatic delay reset circuit, the system achieves safe control, reliable reset and fast self-recovery, thereby improving the overall stability.

[0016] Another objective of this invention is to provide a rapid protection system for transient voltage and current.

[0017] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a transient voltage and current fast protection system, comprising: a sensing module, a main control module, and a parallel protection module; The sensing module is connected to the low-voltage side line and the high-voltage side line. It transforms the high-voltage voltage and low-voltage side current into voltage and current parameters with lower amplitudes. The transformed voltage and current parameters are then input into the main control module for sampling, measurement, and calculation. The main control module receives voltage and current parameters from the sensing module, determines whether a personal electric shock fault has occurred in the boost system based on the voltage and current parameters, and drives the parallel protection module to operate when a fault is determined to have occurred. The main control module also notifies the booster system to trip the upstream and downstream switchgear when a fault occurs; The parallel protection module is a power electronic switch connected in parallel on the line between the low-voltage power supply and the low-voltage side of the step-up transformer. It receives and executes the action commands from the main control module.

[0018] The application provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and wherein the processor implements the steps of the transient voltage and current fast protection method when executing the computer program.

[0019] The application provides a computer readable storage medium, which stores a computer program, wherein the computer program implements the steps of the transient voltage and current fast protection method when executed by a processor.

[0020] The application has the beneficial effects that the voltage and current analog signals are collected in real time by the sensing module, and are isolated, conditioned and digitized converted by the main control module, so that the original signals are electrically isolated, the noise is preliminarily filtered and the signals are standardized, the signal quality and system safety are improved, the digital signals are executed real-time filtering by the parallel architecture of the FPGA, the fast elimination of transient interference is realized by the receiving and filtering strategy and the acceleration of the multiply-add operation of the DSP unit, the protection response time is shortened to the microsecond level, and the misjudgment rate is significantly reduced, the adaptive range adjustment and multi-parameter fault detection are executed by the main control module based on the filtered data, the programmable threshold circuit, the zero sequence voltage synthesis and the zero-crossing dead zone setting are used to realize the accurate discrimination of the wide-range voltage, ground fault and inter-phase fault, the system applicability, protection sensitivity and reliability are improved, the protection elements are driven by the optical coupling isolation, the state is recorded, the automatic delay reset function is combined, the fast and safe protection action and system self-recovery are realized, the expansion of the fault is effectively limited, the safety of the equipment is ensured, and the downtime is reduced, and the high-speed, accurate and high-reliability transient protection overall solution is formed by the steps. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1 The overall flowchart of the transient voltage and current fast protection method provided by an embodiment of the application.

[0023] Figure 2 The connection relationship diagram of the transient voltage and current fast protection device and the boost system provided by an embodiment of the application.

[0024] Figure 3A main control module block diagram of a transient voltage and current fast protection method is provided for an embodiment of the present application.

[0025] Figure 4 A micro current / voltage converter and filter circuit of a transient voltage and current fast protection method is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor should fall within the scope of protection of the present application.

[0027] Embodiment 1, refer to Figure 1 For an embodiment of the present application, the embodiment provides a transient voltage and current fast protection method, comprising: S100, acquiring an analog signal through a sensing module and processing the analog signal through a main control module; S200, filtering and eliminating the digital signal after digital conversion by the main control module using FPGA; S300, performing range adjustment, fault detection and protection control based on the filtered data by the main control module, driving the parallel protection module to protect the elements and recording the system state; It should be noted that the existing power system protection device, when facing the fast-changing fault signals such as transient overvoltage and impulse current, has the problem of using software sequential execution of protection algorithm, long calculation and decision delay, which is difficult to meet the demand of microsecond-level fast protection. The traditional analog filtering or software digital filtering method is easy to introduce phase delay in the signal conditioning stage, and cannot perform parallel and real-time processing on multi-channel data, which affects the accuracy of fault judgment. The protection logic often relies on a single voltage or current threshold, is easily disturbed by harmonics and noise to produce misoperation or refusal, and is difficult to adapt to the dynamic adjustment demand of system operation state change.

[0028] Therefore, in view of the above problems, through the steps of S100-S300, the present application constructs a set of high-speed hardware processing flow with FPGA as the core. The method realizes the acceleration of the whole process from signal acquisition, real-time filtering to fault judgment by replacing software serial execution with hardware parallel processing; and by introducing multi-parameter fusion criterion and adaptive parameter adjustment mechanism, the speed, reliability and adaptability to different operating conditions of the protection are significantly improved, so as to realize the fast and accurate isolation of transient faults.

[0029] Embodiment 2, refer to Figure 1For an embodiment of the present application, the embodiment provides a transient voltage and current fast protection method, comprising: In the embodiment of the present application, the analog signal is acquired by the sensing module in S100, and the analog signal processing is performed by the main control module, including the following steps S101-S102: Considering the strict requirements of the fast protection device on data processing and real-time control, an STM32F407 in the high-performance and low-power ARM Cortex-M4 series chip is selected as the main control chip. The chip has strong computing power, and is based on the ARM Cortex-M4 core, has a main frequency of up to 168MHz, and can quickly execute complex algorithms and logical judgments. At the same time, it has rich peripheral interfaces, including multiple timers, serial ports, SPI, I2C, etc., which can be easily connected and communicated with various sensors, communication modules and actuators, and meet the diversified needs of the fast protection device in data acquisition, processing and control.

[0030] In the embodiment of the present application, S101, isolation, conditioning and digital conversion; In the embodiment of the present application, isolation includes the following steps A1-A2: A1, acquiring analog signals by the sensing module, and communicating with the real-time digital filter to obtain filtered voltage and current sample values; A2, the low-voltage CT secondary signal and the voltage divider secondary voltage signal are respectively isolated and converted to a differential signal within 1.4V (RMS) by a micro-current / voltage converter and a micro-PT; In an alternative embodiment, the isolation of S101 can be that the sensing module acquires analog signals, which are directly input to an optical isolator for electrical isolation. The optical isolator converts the analog signals into optical signals, and then restores them into analog signals. The isolated analog signals are sent to the real-time digital filter for filtering processing to obtain voltage and current sample values, and output to a differential signal range within 1.4V (RMS).

[0031] In another alternative embodiment, the isolation of S101 can also be that the sensing module acquires analog signals, which are converted into digital signals by an analog-to-digital converter (ADC). The digital signals are electrically isolated by a digital isolator (such as a magnetic or capacitive coupling isolator) to ensure signal safety. The isolated digital signals are directly sent to the main control module for digital filtering and processing, and finally output the required voltage and current sample values.

[0032] In the embodiment of the present application, digital conversion includes the following steps B1-B2: B1, the CT secondary current signal and the divider secondary voltage signal are isolated and converted, and a differential signal is output; the signal conditioning circuit performs preliminary filtering and amplitude adjustment on the differential signal; and a fusion algorithm is used to detect whether a ground fault or an inter-phase fault occurs in the voltage boosting system.

[0033] After preliminary filtering and amplitude adjustment by the signal conditioning circuit, the signal is sent to an ADC special chip for AD conversion. Figure 4 .

[0034] The ADC conversion uses a domestic LHA7878SGLB special ADC chip, which has a wide dynamic range, an expandable data transmission rate, and an internal fault detection monitor. It has a high-impedance input, supports direct connection with a resistance divider network or a voltage transformer to measure line voltage or connection with a current transformer or a Rogowski coil to measure current. The LHA787X has a flexible input multiplexer on each channel, which is independently connected to an internally generated signal to achieve testing, temperature, and fault detection. Fault detection can be performed internally in the device, which uses an integrated comparator with a digital-to-analog converter (DAC) controlled trigger level, with a data rate of up to 128kSPS. A complete analog front-end (AFE) solution is packaged in an LQFP-64 package and rated for an industrial temperature range of -40°C to +105°C.

[0035] B2, since the present application does not care about high-frequency signals of tens of kHz (high-frequency signals relative to power frequency), the sampling rate of the ADC is finally determined to be 32kSPS, i.e. 640 points per cycle (160 valid sampling data points in 5ms), with a sampling interval of 31.25us, providing a basis for fault detection in 5ms. After synchronous conversion of the ADC, the digital data is sent to the FPGA through the high-speed SPI interface for real-time filtering.

[0036] In an alternative embodiment, the digital conversion of S101 can be to select an ADS8588S ADC chip, which has a maximum sampling rate of 16kSPS, a relatively narrow dynamic range, and fewer input channels. In S101, the analog signal is obtained through the sensing module, and after isolation conversion and signal conditioning circuit, it is sent to the ADS8588S for AD conversion. The sampling rate is set to 16kSPS, i.e. 320 points per cycle (80 valid sampling data points in 5ms), with a sampling interval of 62.5us, and the converted digital data is output to the digital filter through the SPI interface. However, due to the reduction in sampling rate, the time resolution decreases, and the high-frequency signal acquisition capability is insufficient, which may miss transient fault characteristics.

[0037] In another alternative embodiment, the digitization conversion of S101 can also be to select an AD7656 multi-channel ADC chip, which supports multi-channels but switches the channels one by one for sampling through an internal multiplexer, rather than synchronous sampling. In S101, the CT secondary current signal and the divider secondary voltage signal are sent into the AD7656 after isolation conversion. The sampling rate is set to 32kSPS, but due to the multiplexer switching, the sampling time points of the channels are not consistent, which introduces phase error. The converted digital data is output to the digital filter through a parallel interface or SPI, but the channel switching delay causes the data stream to be non-synchronous, and the digital filter needs to additionally process the synchronization problem, increasing the computational complexity.

[0038] In the embodiment of the application, S102, the analog signal after conditioning is subjected to analog-to-digital conversion; the sampling rate is set, and the converted digital data is output to the digital filter through an interface; a high-frequency PWM driving signal is generated, which drives the protection element to perform a protection action after isolation through a protection isolation driving circuit; and the running information of the boost system is displayed, and the fault information is recorded.

[0039] The analog signal has been subjected to a first-stage hardware analog filtering, which can only filter out high-frequency interference above 5MHz. To further filter out high-frequency interference, secondary filtering is required. However, there is a limit to the performance of an analog filter, and the phase delay of a high-order filter can reach several ms, even exceeding the 5ms protection time limit required by the application. Therefore, the second filtering is performed by a digital filter.

[0040] A digital filter is a commonly used tool in signal processing, which is used for filtering and processing digital signals. Common digital filters can be divided into two categories: finite impulse response (FIR, Finite Impulse Response) filters and infinite impulse response (IIR, Infinite Impulse Response) filters.

[0041] An FIR filter is a linear time-invariant system, and its output only depends on the current and past finite input values: An FIR filter has a natural stability feature due to its non-feedback structure, and has strong stability; it only needs to use symmetric coefficients to achieve linear phase, and its operation process only involves addition and multiplication, which accordingly requires more orders (meaning more calculations) to achieve better filtering effect, and consumes more storage and resources.

[0042] An IIR filter not only depends on the current and past inputs, but also depends on the past outputs.

[0043] Its mathematical expression is: wherein, is the FIR filter output value, is the IIR filter output value, is the total number of current and past input values, M is the total number of past output values, is the coefficient representing the output feedback part, the feedback coefficient; is the coefficient representing the FIR filter weight; As can be seen from the mathematical expression, the y[n-k] part on the right side of the equation represents the output of the IIR filter related to the past output, i.e. feedback is needed, which can produce an infinite length impulse response. Due to its feedback characteristics, special attention needs to be paid to the pole position during design to prevent the filter from being unstable; this feedback also brings benefits, making the IIR filter can achieve sharp (ideal) filtering effect with smaller order.

[0044] From the perspective of amplitude only, the application can apply the IIR filter for filtering to ensure real-time performance, but since the phase delay of the IIR filter is not fixed, the phase characteristics of the voltage and current involved in the application are also important fault criteria, so only the FIR filter with linear phase delay can be selected.

[0045] FIR filtering can also be achieved by using a master MCU, but the general MCU works in series, and the high-order FIR filtering of a single channel may take up to several ms (related to the order of the FIR filter), and in the case of multiple channels, the filtering delay will be much more than 5 ms, which obviously cannot be applied.

[0046] Artix-7 is a low-power and high-performance FPGA series of 28nm process launched by Xilinx (now AMD), suitable for cost-sensitive and certain resource-demanding embedded applications. XC7A100T is a mid-to-high-end model in the Artix-7 series, providing a rich variety of logic resources and DSP units, widely used in digital signal processing, high-speed acquisition, communication and control systems.

[0047] XC7A100T is suitable for use as a processing core for medium-to-high-speed data channels, and has good cost performance in synchronous sampling, FIR filtering and other applications. Using FPGA to implement FIR filter has the following advantages compared to MCU / DSP and other methods: FPGA can perform multiple multiply-add operations in parallel, significantly improving processing speed, and can easily be expanded to multiple channels and different filter orders; there is no operating system intervention, clock-driven processing, suitable for real-time control and high-speed response occasions; Artix-7 provides 240 DSP units, which is very suitable for 64-order FIR; MCU only needs to process the filtered results, simplifying the system architecture; further improving the filtering throughput.

[0048] At the sampling rate of 32kSps*8 channels, the MCU cannot complete the 64-order filtering process per channel, while the FPGA can complete the parallel processing task within dozens of clock cycles, taking no more than 1us, realizing real-time filtering.

[0049] The FPGA controls the clock and chip selection in the SPI host mode, reads data from the LHA7878SGLB, parses the frame header, synchronization word and channel data by using a hardware state machine, automatically pulls 8-channel data (192 bits) in each sampling period, caches them to the FIFO, and adopts the edge-receiving-edge-filtering strategy to further improve real-time performance.

[0050] After the 8-channel data filtering is completed, the data are stored in the FPGA internal RAM cache, the MCU communicates with the FPGA through the FSMC parallel interface to read the channel data for further calculation.

[0051] In an optional embodiment, a simplified FIR filter with a lower order is used, the host module realizes a low-order FIR filter (such as 32 orders) by using the FPGA, the FPGA performs a finite impulse response digital filter in a parallel manner, but the order is reduced, the filtering effect is poor, the high-frequency interference cannot be completely filtered out, the signal-to-noise ratio is reduced, the FPGA reads the channel data from the ADC and adopts the edge-receiving-edge-filtering strategy, but due to the low order, noise may be left in the filtering output, increasing the risk of misjudgment, the filtering calculation performs multiplication and addition operations by using the DSP unit of the FPGA, but the multiplication and addition operations are reduced, the processing speed is fast but the filtering performance is reduced, which may affect the reliability of fault detection, and therefore the filter in the embodiment of the application is used for operation.

[0052] In the embodiment of the application, the host module in S200 filters and eliminates the digital signal converted by using the FPGA, including the following steps S201-S203: S201, the FPGA performs a finite impulse response digital filter in a parallel manner; S202, the FPGA reads the channel data from the ADC and adopts the edge-receiving-edge-filtering strategy; S203, the filtering calculation performs multiplication and addition operations in parallel by using the DSP unit of the FPGA.

[0053] In an optional embodiment, the filtering elimination in S201 can use MCU software to realize the FIR filter, the host MCU reads the multi-channel digital signals from the ADC chip through the SPI interface and buffers the data in the internal RAM, the MCU realizes the FIR filter by using the software algorithm, processes the sampling data channel by channel through the loop execution of multiplication and addition operation; the filter coefficients are pre-stored in the Flash and loaded into the register during the calculation, since the MCU is a serial processing, the filter calculation is sequentially performed on each channel, and the result is stored back to the RAM after completion for subsequent fault judgment. The calculation delay is reduced through the optimization code, but the overall processing is still based on the single core of the MCU.

[0054] In another optional embodiment, the filtering elimination in S201 can also use a dedicated DSP chip to realize the FIR filter, the dedicated DSP chip is introduced as a co-processor, communicates with the host MCU through parallel or SPI interface, the DSP chip directly reads the digital signals from the ADC, uses the hardware multiplication and accumulation unit to perform the multiplication and addition operation of the FIR filter in parallel, supports multi-channel pipeline processing, the DSP internally integrates multiple calculation units and can simultaneously process multiple data points, the filtered data is transmitted to the shared memory through the DMA, and then read by the host MCU, the filter coefficients are stored in the in-chip memory of the DSP, and the FIR filter of fixed order is realized by configuring the filter library of the DSP.

[0055] In the embodiment of the application, the host module performs range adjustment, fault detection and protection control based on the filtered data in S300, drives the parallel protection module to protect the elements and records the system state, including the following steps S301-S302: S301, select the host chip, set the peripheral interface at the same time, use the three-phase voltage divider for voltage division processing, set the potentiometer adjustable circuit, adjust the potentiometer to make the voltage signals after three-phase voltage division consistent before entering the subsequent circuit; The voltage signals after voltage division are further conditioned including filtering and limiting through the board hardware circuit, at the same time, a threshold comparison circuit is set to compare the conditioned voltage signals with the preset threshold, when the voltage signal exceeds the threshold, the corresponding level signal is output as a criterion for the host chip to judge; The low-voltage side three-phase CT selects the current transformer to collect three-phase current, uses the overcurrent protection circuit to send an alarm signal and take protective measures when the current exceeds the range of the CT, and sets a programmable threshold adjustment circuit, the host chip outputs the corresponding voltage signal through the digital-to-analog converter DAC according to the current data during normal operation to adjust the reference voltage of the threshold comparison circuit, and uses the three-phase current as a criterion to trigger the protection action when any phase current exceeds the adjusted threshold; An external AD chip is selected, a sampling rate and a cycle sampling are set, the AD chip is synchronously sampled, a current and a voltage are detected by comparing an instantaneous value of a current cycle with an instantaneous value of a previous cycle, a dead zone of ±15° is set at a zero-crossing point, and a misjudgment caused by signal fluctuation at the zero-crossing point is eliminated by combining a hardware circuit and a software algorithm; The wide-range voltage is collected by combining a high-voltage isolation transformer and a variable-ratio voltage dividing circuit, switching between low voltage and high voltage is performed by switching a voltage dividing ratio, a harmonic filter circuit is added, a low-pass filter and a band-pass filter are combined, high-frequency harmonics and interference signals of a set frequency are filtered out, and only a fundamental wave and useful low-order harmonics are allowed to pass through.

[0056] S302, normal system three-phase voltage is taken as a basis for parameter adjustment, a multi-parameter criterion method is adopted, a hardware-synthesized zero sequence voltage and three-phase current are taken as criteria, three-phase voltage is synthesized by a hardware circuit to obtain a zero sequence voltage, three-phase current signals are introduced into a main control chip, and a multi-algorithm is used in the main control chip to comprehensively consider the relationship between voltage and current; A start button is set, the system starts running by triggering the start button, a parameter adjustment circuit is designed, a three-phase voltage and current phase and amplitude are compensated and adjusted by adjusting a potentiometer or using a digital potentiometer, a main control chip outputs a corresponding control signal through a DAC according to actual measurement, and parameters of a coefficient setting circuit are adjusted; A hardware circuit is used to synthesize three-phase voltage to obtain a zero sequence voltage, an adder circuit composed of an operational amplifier and resistors and capacitors is used to add three-phase voltage signals and divide by 3 to obtain a zero sequence voltage, a control relay or an analog switch is used for switching control, a main control chip outputs a corresponding control signal according to a working voltage level of the system to control the on-off of the control relay or the analog switch to switch different voltage dividing circuits and measurement channels.

[0057] S303, a main control chip outputs a corresponding control signal through an optocoupler isolation circuit to drive a silicon-controlled trigger circuit, and an overcurrent and overvoltage protection circuit is set; Two incoming channels are set, one is used to receive external control signals, and the other receives a reset signal given by a PLC; when the system fails or needs to be restarted, the PLC sends a reset signal, the reset signal is introduced into the main control chip through a hardware circuit to make the system return to an initial state, an incoming circuit uses optocoupler isolation technology to electrically isolate external signals from the main control chip; one outgoing channel is set to control a boost system, when the system detects a fault or needs to be boosted, the main control chip outputs a corresponding control signal through the outgoing circuit to drive the boost system to perform a boost operation, and the outgoing circuit uses a relay or a power transistor as a switching element; The automatic delay reset circuit is arranged, the delay time can be set as 50 ms, when the system detects that the fault is removed, the delay timer is automatically started, and after 50 ms, a reset signal is automatically sent to restore normal operation.

[0058] The specific implementation is as follows. 1. The main control module design scheme of the 4-10kV transient voltage and current fast protection series device is as follows: 1) Selection of main control chip: considering the strict requirements of the fast protection device on data processing and real-time control, an STM32F407 in the ARMCortex-M4 series chip with high performance and low power consumption is selected as the main control chip. The chip has strong computing power, is based on the ARMCortex-M4 core, has a main frequency of up to 168 MHz, and can quickly execute complex algorithms and logical judgments. At the same time, it has rich peripheral interfaces, including multiple timers, serial ports, SPI, I2C, etc., which can be easily connected and communicated with various sensors, communication modules and execution mechanisms, and meet the diversified needs of the fast protection device in data acquisition, processing and control.

[0059] 2) Three-phase voltage acquisition circuit: input range and voltage division processing: for the acquisition of three-phase voltage (0-420V), considering the subsequent application to different voltage levels such as 10kV (100 / 1), 110kV, 500kV (1000 / 1) and single-phase grounding and phase-to-phase short circuit measurement, a high-precision and high-voltage three-phase voltage divider is used for voltage division processing. In order to eliminate the error caused by the inconsistency of the three-phase voltage divider, a potentiometer adjustable circuit is set in the hardware circuit. By adjusting the potentiometer, the voltage signals after three-phase voltage division are made consistent before entering the subsequent circuit, ensuring the accuracy of acquisition.

[0060] Signal conditioning and threshold setting: the voltage signal U0 after voltage division is further conditioned by the board hardware circuit, including filtering, limiting and other processing, to remove noise and prevent overvoltage damage to the subsequent circuit. At the same time, a threshold comparison circuit is set in the hardware circuit, which compares the conditioned U0 with the preset threshold. When U0 exceeds the threshold, the corresponding level signal is output as a criterion for the main control chip to judge.

[0061] 3) Three-phase current acquisition circuit: CT selection and current acquisition: the low-voltage side three-phase CT selects a current transformer with a transformation ratio of 500 / 5, which is used to acquire 0-5A three-phase current. Since the instantaneous value may exceed the range, an overcurrent protection circuit is used in the hardware design. When the current exceeds the range of the CT, an alarm signal is sent in time and appropriate protection measures are taken to prevent damage to the CT.

[0062] Automatic adjustment of overcurrent threshold: To realize the automatic adjustment of overcurrent threshold according to normal conditions, a programmable threshold adjustment circuit is designed in the hardware circuit. The main control chip outputs the corresponding voltage signal through the DAC (digital-to-analog converter) according to the current data during normal operation, adjusts the reference voltage of the threshold comparison circuit, and thus realizes the automatic adjustment of the overcurrent threshold. Taking three-phase current as the criterion, when any phase current exceeds the adjusted threshold, the protection action is triggered.

[0063] 4) External AD sampling circuit - AD chip selection: AD7606 is selected as the external AD chip, which has 8-channel synchronous sampling function, fast sampling speed, and can meet the real-time requirements of the system for data acquisition. Its sampling rate is temporarily set to 100k, 16k data per cycle, 8-channel simultaneous sampling, and 32k data per two cycles.

[0064] Synchronous sampling and comparison: AD7606 realizes 8-channel synchronous sampling, ensuring that the collected three-phase voltage and three-phase current data accurately correspond at the same time. The instantaneous value of the current cycle is compared with that of the previous cycle to detect the changes in current and voltage. A dead zone of ±15° is set near the zero-crossing point, and the combination of hardware circuit and software algorithm is used to avoid false judgments caused by signal fluctuations near the zero-crossing point, ensuring accurate fault detection within 5ms.

[0065] 5) Wide range of voltage acquisition and harmonic processing - wide range of voltage acquisition: To meet the acquisition needs of different voltage levels such as 10kV (100 / 1), 110kV, 500kV (1000 / 1), a combination of high-voltage isolation transformer and variable-ratio voltage divider circuit is used in hardware design. By switching different voltage division ratios, flexible switching between low and high voltage is realized, ensuring accurate voltage signal acquisition under different voltage levels.

[0066] Harmonic processing: Considering the influence of harmonics on voltage acquisition, a harmonic filter circuit is added in the hardware circuit. A combination of low-pass filter and band-pass filter is used to filter out high-frequency harmonics and specific frequency interference signals, allowing only the fundamental wave and useful low-order harmonics to pass through, improving the accuracy and stability of voltage acquisition.

[0067] 6) Multi-parameter criterion and parameter adjustment circuit - multi-parameter criterion synthesis: Taking normal system three-phase voltage as the basis for parameter adjustment, the method of multi-parameter criterion is used, and the synthesized zero sequence voltage U0 and three-phase current are used as the criterion. Through the hardware circuit, the three-phase voltage is synthesized to obtain the zero sequence voltage U0, and the three-phase current signal is introduced into the main control chip. In the main control chip, multiple algorithms are used to consider the relationship between voltage and current, such as power factor, active power, and reactive power, to make fault judgments and improve the accuracy and reliability of fault identification.

[0068] Adjusting and starting circuit: Set a start button, after adjusting the voltage, trigger the system to start running through the start button. At the same time, in order to facilitate system debugging and parameter setting, the parameter adjusting circuit is designed, which can be connected with the host computer through the serial port or other communication interface to realize online adjustment and optimization of system parameters.

[0069] 7) Phase and amplitude coefficient setting circuit - to solve the problem of inconsistent three-phase voltage divider ratio, phase and amplitude coefficient adjustment circuit is set in the hardware circuit. By adjusting the potentiometer or using digital potentiometer, the phase and amplitude of three-phase voltage and current are compensated and adjusted, so that the collected signals are more accurate and consistent. The main control chip can output corresponding control signals through DAC according to the actual measurement situation, adjust the parameters of the coefficient setting circuit, and realize automatic calibration and compensation.

[0070] 8) Hardware synthesized zero sequence and measurement range switching - hardware synthesized zero sequence: three-phase voltage is synthesized to obtain zero sequence voltage by using hardware circuit. The adder circuit composed of operational amplifier and resistor-capacitor elements adds three-phase voltage signals and divides by 3 to obtain zero sequence voltage U0. This hardware synthesis method has the advantages of fast response speed and good real-time performance, and can accurately reflect the zero sequence voltage of the system in time.

[0071] Measurement range switching: To realize the switching of measurement range between low voltage and high voltage, relay or analog switch is used for switching control in hardware design. The main control chip outputs corresponding control signals according to the working voltage level of the system to control the on-off of the relay or analog switch, switch different voltage dividing circuits and measurement channels, and ensure accurate measurement under different voltage levels.

[0072] 9) Silicon controlled rectifier control circuit - silicon controlled rectifier selection: three groups of anti-parallel silicon controlled rectifiers are selected to control the on-off of the circuit. Silicon controlled rectifier has the advantages of high voltage resistance, large current, fast switching speed, etc., which can meet the control requirements of the system for high-power load.

[0073] Control circuit design: The main control chip outputs corresponding control signals through the optocoupler isolation circuit to drive the trigger circuit of the silicon controlled rectifier. The trigger circuit uses pulse transformer or special trigger chip to provide accurate trigger pulse for the silicon controlled rectifier, and controls the conduction and turn-off of the silicon controlled rectifier. At the same time, overcurrent and overvoltage protection circuits are set in the silicon controlled rectifier control circuit to ensure the safe and reliable operation of the silicon controlled rectifier.

[0074] 10) Open-in and open-out circuit - Open-in circuit: Set up 2 open-in channels, one for receiving external control signals such as start, stop, reset signals, and the other for receiving reset signals from PLC. When the system fails or needs to be restarted, PLC sends a reset signal, which is introduced into the main control chip through the hardware circuit, so that the system returns to the initial state. The open-in circuit uses optical coupling isolation technology to electrically isolate the external signal from the main control chip, improving the system's anti-interference ability and reliability.

[0075] Open-out circuit: Set up 1 open-out channel to control the boost system. When the system detects a fault or needs to boost, the main control chip outputs the corresponding control signal through the open-out circuit to drive the boost system to operate. The open-out circuit uses a relay or power transistor as a switching element to ensure reliable control of the boost system.

[0076] 11) Automatic delay reset - Set up an automatic delay reset circuit in the hardware design, with a delay time of 50ms. When the system detects a specific condition (such as fault removal), it automatically starts the delay timer and sends a reset signal after 50ms to restore normal operation. This automatic delay reset function can prevent the system from frequent resets during fault moments, improving system stability.

[0077] The design of the invention revolves around the main control chip STM32F407, focusing on the collection of three-phase voltage and three-phase current, external AD sampling, wide-range voltage collection and harmonic processing, multi-parameter criterion and parameter adjustment, phase and amplitude coefficient setting, hardware synthesis zero sequence and measurement range switching, open-in and open-out, PLC reset and delay, and silicon-controlled silicon control, etc. Through reasonable hardware circuit design and selection, the fast protection device can accurately and quickly collect and process electrical signals to achieve reliable protection of the power system.

[0078] 2, 5-35kV-110kV transient voltage and current fast protection device main control module design scheme: 1) Main control chip selection - Considering the stringent requirements of fast protection devices for data processing and real-time control, the STM32F407 chip in the ARMCortex-M4 series with high performance and low power consumption is selected as the main control chip. This chip has strong computing power, based on the ARMCortex-M4 core, with a main frequency of up to 168MHz, capable of quickly executing complex algorithms and logical judgments. At the same time, it has a rich set of peripheral interfaces, including multiple timers, serial ports, SPI, I2C, etc., which can easily connect and communicate with various sensors, communication modules and actuators, meeting the diverse needs of fast protection devices in data acquisition, processing and control.

[0079] 2) Three-phase voltage acquisition circuit - input range and voltage division processing: for the acquisition of three-phase voltage (0-420V), considering the subsequent application to different voltage levels such as 10kV (100 / 1), 110kV, 500kV (1000 / 1) and single-phase grounding and phase-to-phase short-circuit measurement, a high-precision, high-voltage three-phase voltage divider is used for voltage division. To eliminate the error caused by the inconsistency of the three-phase voltage divider, a potentiometer adjustable circuit is set in the hardware circuit. By adjusting the potentiometer, the voltage signals after three-phase voltage division are consistent before entering the subsequent circuit, ensuring the accuracy of the acquisition.

[0080] Signal conditioning and threshold setting: the voltage signal U0 after voltage division is further conditioned by the board hardware circuit, including filtering, limiting and other processing, to remove noise and prevent overvoltage damage to the subsequent circuit. At the same time, a threshold comparison circuit is set in the hardware circuit to compare the conditioned U0 with the preset threshold. When U0 exceeds the threshold, the corresponding level signal is output as a criterion for the main control chip to judge.

[0081] 3) Three-phase current acquisition circuit - CT selection and current acquisition: the low-voltage side three-phase CT selects a current transformer with a transformation ratio of 500 / 5 for acquiring 0-5A three-phase current. Since the instantaneous value may exceed the range, an overcurrent protection circuit is used in the hardware design. When the current exceeds the range of the CT, an alarm signal is sent in time and appropriate protective measures are taken to prevent damage to the CT.

[0082] Automatic adjustment of overcurrent threshold: to realize the automatic adjustment of the overcurrent threshold according to normal conditions, a programmable threshold adjustment circuit is designed in the hardware circuit. The main control chip adjusts the reference voltage of the threshold comparison circuit by outputting the corresponding voltage signal through the DAC (digital-to-analog converter) according to the current data during normal operation, thereby realizing the automatic adjustment of the overcurrent threshold. The three-phase current is used as a criterion. When the current of any phase exceeds the adjusted threshold, the protection action is triggered.

[0083] 4) External AD sampling circuit - AD chip selection: AD7606 is selected as the external AD chip. This chip has 8-channel synchronous sampling function, fast sampling speed, and can meet the real-time requirements of the system for data acquisition. Its sampling rate is temporarily set to 100k, 16k data per cycle, 8 channels are sampled simultaneously, and 32k data per cycle is expected.

[0084] Synchronous sampling and comparison: The AD7606 realizes 8-channel synchronous sampling, ensuring that the collected three-phase voltage and three-phase current data accurately correspond at the same time. The instantaneous value of the current cycle is compared with that of the previous cycle to detect changes in current and voltage. A dead zone of ±15° is set near the zero crossing point to avoid misjudgment due to signal fluctuations near the zero crossing point through the combination of hardware circuit and software algorithm, ensuring accurate judgment of fault conditions within 5ms.

[0085] 5) Wide range voltage acquisition and harmonic processing - Wide range voltage acquisition: To meet the acquisition needs of different voltage levels such as 10kV (100 / 1), 110kV, 500kV (1000 / 1), a combination of high-voltage isolation transformers and variable-ratio voltage divider circuits is used in the hardware design. By switching different voltage division ratios, flexible switching between low and high voltages is achieved, ensuring accurate voltage signal acquisition at different voltage levels.

[0086] Harmonic processing: Considering the influence of harmonics on voltage acquisition, a harmonic filter circuit is added to the hardware circuit. A combination of low-pass filters and band-pass filters is used to filter out high-frequency harmonics and specific frequency interference signals, allowing only the fundamental wave and useful low-order harmonics to pass through, improving the accuracy and stability of voltage acquisition.

[0087] 6) Multi-parameter criterion and parameter adjustment circuit - Multi-parameter criterion synthesis: Using the normal system three-phase voltage as the basis for parameter adjustment, the multi-parameter criterion method is used, with the hardware-synthesized zero sequence voltage U0 and three-phase current as the criterion. The three-phase voltage is synthesized by the hardware circuit to obtain the zero sequence voltage U0, and the three-phase current signal is introduced into the main control chip. In the main control chip, multiple algorithms are used to consider the relationship between voltage and current, such as power factor, active power, and reactive power, for fault judgment, improving the accuracy and reliability of fault identification.

[0088] Parameter adjustment and start-up circuit: A start button is set to trigger the system to start running after the voltage is adjusted. At the same time, to facilitate system debugging and parameter setting, a parameter adjustment circuit is designed, which can be connected to the host computer through a serial port or other communication interface to realize online adjustment and optimization of system parameters.

[0089] 7) Phase and amplitude coefficient setting circuit - To solve the problem of possible inconsistency of three-phase voltage dividers, a phase and amplitude coefficient adjustment circuit is set in the hardware circuit. By adjusting the potentiometer or using a digital potentiometer, the phase and amplitude of the three-phase voltage and current are compensated and adjusted to make the collected signals more accurate and consistent. The main control chip can output corresponding control signals through the DAC to adjust the parameters of the coefficient setting circuit, realizing automatic calibration and compensation.

[0090] 8) Hardware synthetic zero sequence and measurement range switching - Hardware synthetic zero sequence: The three-phase voltage is synthesized to obtain the zero sequence voltage by using hardware circuit. The three-phase voltage signals are added and divided by 3 by the adder circuit composed of operational amplifier and resistor-capacitor elements to obtain the zero sequence voltage U0. The hardware synthesis method has the advantages of fast response speed and good real-time performance, and can accurately reflect the zero sequence voltage condition of the system in time.

[0091] Measurement range switching: To realize the measurement range switching between low voltage and high voltage, a relay or an analog switch is used for switching control in the hardware design. The main control chip outputs the corresponding control signal according to the working voltage level of the system to control the on-off of the relay or the analog switch, switch different voltage division circuits and measurement channels, and ensure accurate measurement under different voltage levels.

[0092] 9) Silicon controlled rectifier control circuit - Silicon controlled rectifier selection: Three groups of anti-parallel silicon controlled rectifiers are selected to control the on-off of the circuit. The silicon controlled rectifier has the advantages of high voltage resistance, large current, fast switching speed, etc., which can meet the control requirements of the system for high-power load.

[0093] Control circuit design: The main control chip outputs the corresponding control signal through the optocoupler isolation circuit to drive the trigger circuit of the silicon controlled rectifier. The trigger circuit uses a pulse transformer or a special trigger chip to provide accurate trigger pulses for the silicon controlled rectifier to control the conduction and turn-off of the silicon controlled rectifier. At the same time, an overcurrent and overvoltage protection circuit is set in the silicon controlled rectifier control circuit to ensure the safe and reliable operation of the silicon controlled rectifier.

[0094] 10) Input and output circuit - Input circuit: Two input channels are set, one for receiving external control signals such as start, stop, reset, etc. and the other for receiving the reset signal given by the PLC. When the system fails or needs to be restarted, the PLC sends a reset signal, which is introduced into the main control chip through the hardware circuit, so that the system returns to the initial state. The input circuit uses optocoupler isolation technology to electrically isolate the external signal from the main control chip, improving the anti-interference ability and reliability of the system.

[0095] Output circuit: One output channel is set to control the boost system. When the system detects a fault or needs to boost, the main control chip outputs the corresponding control signal through the output circuit to drive the boost system to perform the boost operation. The output circuit uses a relay or a power transistor as a switching element to ensure reliable control of the start and stop of the boost system.

[0096] 11) Automatic time delay reset - Set the automatic time delay reset circuit in the hardware design, the delay time can be set to 50ms. When the system detects certain conditions (such as fault removal), automatically start the delay timer, after 50ms automatically send reset signal, make the system return to normal operation. The automatic time delay reset function can avoid the system frequent reset in the fault moment, improve the stability of the system.

[0097] The hardware design is based on the main control chip STM32F407. It is designed in detail for the collection of three-phase voltage and three-phase current, external AD sampling, wide range voltage collection and harmonic processing, multi-parameter criterion and parameter adjustment, phase and amplitude coefficient setting, hardware synthesis zero sequence and measurement range switching, input and output, PLC reset and delay, and silicon controlled rectifier control. Through reasonable hardware circuit design and selection, it ensures that the fast protection device can accurately and quickly collect and process electrical signals, and realizes reliable protection of the power system.

[0098] 3. Main control module design scheme of 6-220kV-500kV transient voltage and current fast protection device series: 1) Selection of main control chip - Considering the strict requirements of fast protection device on data processing and real-time control, STM32F407, a high-performance and low-power chip in ARMCortex-M4 series, is selected as the main control chip. The chip has strong computing power, based on ARMCortex-M4 core, with a main frequency of up to 168MHz, which can quickly execute complex algorithms and logical judgments. At the same time, it has rich peripheral interfaces, including multiple timers, serial ports, SPI, I2C, etc., which can easily connect and communicate with various sensors, communication modules and actuators, meeting the diversified needs of fast protection device in data acquisition, processing and control.

[0099] 2) Voltage acquisition circuit - signal conditioning and threshold setting: the voltage signal after voltage division is further conditioned by the board hardware circuit, including filtering, amplitude limiting and other processing, to remove noise and prevent overvoltage damage to the subsequent circuit. At the same time, threshold comparison circuit is set in the hardware circuit, which compares the conditioned signal with the preset threshold. When the temporary drop exceeds the threshold, the corresponding level signal is output as the criterion for the main control chip to judge.

[0100] 3) Three-phase current acquisition circuit - CT selection and current acquisition: the CT on the low-voltage side is selected to have a transformation ratio of 1000 / 5, which is used to collect 0-5A three-phase current. Since the instantaneous value may exceed the range, an overcurrent protection circuit is used in the hardware design. When the current exceeds the range of CT, an alarm signal is sent in time and appropriate protection measures are taken to prevent damage to CT.

[0101] Automatic adjustment of overcurrent threshold: To realize the automatic adjustment of overcurrent threshold according to normal conditions, a programmable threshold adjustment circuit is designed in the hardware circuit. The main control chip outputs the corresponding voltage signal through the DAC (digital-to-analog converter) according to the current data during normal operation, adjusts the reference voltage of the threshold comparison circuit, and thus realizes the automatic adjustment of the overcurrent threshold. Taking current as the criterion, when the current exceeds the adjusted threshold, the protection action is triggered.

[0102] 4) External AD sampling circuit - AD chip selection: ADS131M02 is selected as the external AD chip, which has 2-channel synchronous sampling, differential input and 24-bit sampling accuracy, and the maximum sampling speed is 64ksps, which can meet the real-time requirements of the system for data collection. Its sampling rate is temporarily set to 64ksps, the sampling interval is about 16us, one cycle samples 3200 points of data, and two cycles are expected to sample 6.4k data. A dead zone of ±15° is set near the zero crossing point, and through the combination of hardware circuit and software algorithm, the misjudgment caused by signal fluctuation near the zero crossing point is avoided, and the fault condition is accurately judged within 5ms.

[0103] 5) Wide range collection and harmonic processing - ADS131M02 as external AD chip, with programmable gain function, up to 8 levels of gain, through switching different AD gain, to ensure accurate collection of voltage and current signals under different operating voltages.

[0104] Harmonic processing: Considering the influence of harmonics on voltage collection, a harmonic filter circuit is added in the hardware circuit. A combination of low-pass filter and band-pass filter is used to filter out high-frequency harmonics and specific frequency interference signals, allowing only the fundamental wave and useful low-order harmonics to pass through, improving the accuracy and stability of voltage collection.

[0105] 6) Multi-parameter criterion and parameter adjustment circuit - Multi-parameter criterion synthesis: Taking system voltage as the basis for parameter adjustment, voltage and current are used as criteria. In the main control chip, multiple algorithms are used to consider the relationship between voltage and current, such as power factor, active power, and reactive power, to make fault judgments and improve the accuracy and reliability of fault identification.

[0106] Parameter adjustment and start-up circuit: A start button is set, which triggers the system to start running after the voltage is adjusted. At the same time, to facilitate system debugging and parameter setting, a parameter adjustment circuit is designed, which can be connected to the host computer through a serial port or other communication interface to realize online adjustment and optimization of system parameters.

[0107] 7) Phase and amplitude coefficient setting circuit - set the phase and amplitude coefficient adjustment circuit in the hardware circuit. By adjusting the potentiometer or using digital potentiometer, the phase and amplitude of voltage and current are compensated and adjusted, so that the collected signal is more accurate and consistent. The main control chip can output corresponding control signal through DAC according to the actual measurement situation, adjust the parameter of coefficient setting circuit, realize automatic calibration and compensation.

[0108] 8) Measurement range switching - measurement range switching: to realize the measurement range switching between low voltage and high voltage, use relay or analog switch for switching control in hardware design. The main control chip outputs corresponding control signal according to the working voltage level of the system, controls the on-off of the relay or analog switch, switches different voltage division circuits and measurement channels, and ensures accurate measurement under different voltage levels.

[0109] 9) Silicon controlled rectifier control circuit - silicon controlled rectifier selection: select a group of anti-parallel silicon controlled rectifiers for controlling the on-off of the circuit. Silicon controlled rectifier has the advantages of high voltage resistance, large current, fast switching speed, etc., which can meet the control requirements of the system for high-power load.

[0110] Control circuit design: the main control chip outputs corresponding control signal through optical coupling isolation circuit to drive the trigger circuit of silicon controlled rectifier. The trigger circuit uses pulse transformer or special trigger chip to provide accurate trigger pulse for silicon controlled rectifier, control the on-off of silicon controlled rectifier. At the same time, set overcurrent and overvoltage protection circuit in silicon controlled rectifier control circuit to ensure the safe and reliable operation of silicon controlled rectifier.

[0111] 10) Input and output circuit - input circuit: set 2 input channels, one for receiving external control signals such as start, stop, reset, etc. One receives the reset signal given by PLC. When the system fails or needs to restart, PLC sends a reset signal, which is introduced into the main control chip through the hardware circuit, so that the system returns to the initial state. The input circuit uses optical coupling isolation technology to electrically isolate the external signal from the main control chip, improving the anti-interference ability and reliability of the system.

[0112] Output circuit: set 1 output channel to control the boost system. When the system detects a fault or needs to boost, the main control chip outputs corresponding control signal through the output circuit to drive the boost system to perform boost operation. The output circuit uses relay or power transistor as switching element to ensure reliable control of the start and stop of the boost system.

[0113] 11) Automatic time delay reset - set the automatic time delay reset circuit in the hardware design, the delay time can be set to 50ms. When the system detects a specific condition (such as fault removal), automatically start the delay timer, after 50ms automatically send reset signal, make the system return to normal operation. The automatic time delay reset function can avoid the system frequent reset in the fault moment, improve the stability of the system.

[0114] The hardware design is developed around the main control chip STM32F407, and detailed design is made for the collection of three-phase voltage and three-phase current, external AD sampling, wide range voltage collection and harmonic processing, multi-parameter criterion and parameter adjustment, phase and amplitude coefficient setting, hardware synthesis zero sequence and measurement range switching, input and output, PLC reset and delay, and silicon controlled rectifier control. Through reasonable hardware circuit design and selection, it is ensured that the fast protection device can accurately and quickly collect and process electrical signals, and realize reliable protection of the power system.

[0115] Embodiment 3, refer to Figures 2-4 For an embodiment of the present application, the above is a schematic scheme of the transient voltage and current fast protection method. It should be noted that the technical scheme of the transient voltage and current fast protection system belongs to the same concept as the technical scheme of the transient voltage and current fast protection method described above. The details of the technical scheme of the transient voltage and current fast protection system in this embodiment are not described in detail, and can be referred to the description of the technical scheme of the transient voltage and current fast protection method.

[0116] The embodiment provides a transient voltage and current fast protection system, which includes a sensing module, a main control module, and a parallel protection module, and the connection relationship with the boost system is as shown in Figure 2 .

[0117] The sensing module is connected to the low-voltage side circuit and the high-voltage side circuit, and converts the high-voltage voltage and the low-voltage side current into voltage and current parameters with lower amplitude. The converted voltage and current parameters are input to the main control module for sampling, measurement, and calculation.

[0118] The main control module receives the voltage and current parameters from the sensing module, determines whether the boost system has a personal electric shock fault according to these key parameters, and drives the parallel protection module to act when a fault is determined.

[0119] The parallel protection module is a power electronic switch, which is connected in parallel between the low-voltage power supply and the low-voltage side of the boost transformer, receives the action instruction from the main control module, and executes it.

[0120] In addition, the main control module also informs the boost system to trip the front and rear switch cabinets when a fault occurs.

[0121] The embodiment further provides an electronic device suitable for the transient voltage and current fast protection method, including a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to realize the transient voltage and current fast protection method proposed in the above embodiment.

[0122] The embodiment further provides a storage medium having a computer program stored thereon, and the computer program is executed by a processor to realize the transient voltage and current fast protection method proposed in the above embodiment.

[0123] The storage medium proposed in the embodiment belongs to the same inventive concept as the transient voltage and current fast protection method proposed in the above embodiment, and the technical details not described in the embodiment can be referred to the above embodiment, and the embodiment has the same beneficial effects as the above embodiment.

[0124] From the above description about the embodiments, those skilled in the art can clearly understand that the present application can be realized by means of software and necessary universal hardware, and of course can be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, and the computer software product can be stored in a computer readable storage medium, such as a floppy disk, a ROM, a RAM, a FLASH, a hard disk or an optical disk, etc., and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods of various embodiments of the present application.

[0125] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application, and although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and all of them should be covered in the scope of the claims of the present application.

Claims

1. A method for rapid protection against transient voltage and current, characterized in that: include, Analog signals are acquired through the sensing module and processed by the main control module. The main control module uses an FPGA to filter and eliminate the digital signals after digitization. The main control module performs range adjustment, fault detection and protection control based on the filtered data, drives the parallel protection module to protect the components and records the system status.

2. The transient voltage and current fast protection method as described in claim 1, characterized in that: The main control module includes, and the analog signal processing includes, isolation, conditioning, and digital conversion. The sensor module acquires analog signals and communicates with the real-time digital filter to obtain filtered voltage and current sample values. The secondary current signal of the CT and the secondary voltage signal of the voltage divider are isolated and transformed to output a differential signal; The signal conditioning circuit performs preliminary filtering and amplitude adjustment on the differential signal; At the same time, a fusion algorithm is used to detect whether a grounding or phase-to-phase fault has occurred in the boost system.

3. The transient voltage and current fast protection method as described in claim 2, characterized in that: The digital conversion includes performing analog-to-digital conversion on the conditioned analog signal; Set the sampling rate, and the converted digital data is output to the digital filter through the interface; A high-frequency PWM drive signal is generated, and after being isolated by a protection isolation drive circuit, it drives the protection element to perform protection action. Displays the operating information of the boost system and records fault information.

4. The transient voltage and current fast protection method as described in claim 3, characterized in that: The filtering and elimination of the digital signal after digitization using FPGA includes the construction of a finite impulse response digital filter in parallel using FPGA. The FPGA reads channel data from the ADC and employs a strategy of receiving and filtering simultaneously. The filtering calculation utilizes the FPGA's DSP unit to perform multiply-accumulate operations in parallel.

5. The transient voltage and current fast protection method as described in claim 4, characterized in that: The main control module includes selecting a main control chip, setting up peripheral interfaces, using a three-phase voltage divider for voltage division, and setting up a potentiometer adjustable circuit. By adjusting the potentiometer, the voltage signals after the three-phase voltage division are made consistent before entering the subsequent circuit. The voltage signal after voltage division is further conditioned by the board hardware circuit, including filtering and limiting. At the same time, a threshold comparison circuit is set to compare the conditioned voltage signal with a preset threshold. When the voltage signal exceeds the threshold, the corresponding level signal is output as a criterion for the main control chip to make a judgment. The low-voltage side three-phase CT uses a current transformer to collect three-phase current and adopts an overcurrent protection circuit. When the current exceeds the CT's range, an alarm signal is issued and protective measures are taken. At the same time, a programmable threshold adjustment circuit is set. The main control chip adjusts the reference voltage of the threshold comparison circuit by outputting the corresponding voltage signal through the digital-to-analog converter (DAC) based on the current data during normal operation. The three-phase current is used as the criterion. When any phase current exceeds the adjusted threshold, the protection action is triggered. Select an external AD chip, set the sampling rate and cycle sampling, the AD chip performs synchronous sampling, compares the instantaneous value of the current cycle with the instantaneous value of the previous cycle to detect changes in current and voltage, sets a dead zone of ±15° at the zero-crossing point, and eliminates misjudgments caused by signal fluctuations at the zero-crossing point through a combination of hardware circuits and software algorithms. Wide-range voltage acquisition is achieved by combining a high-voltage isolation transformer with a variable-ratio voltage divider circuit. Switching between low and high voltage is achieved by changing the voltage divider ratio. A harmonic filtering circuit is added, using a combination of low-pass and band-pass filters to filter out high-frequency harmonics and interference signals of a set frequency, allowing only the fundamental frequency and useful low-order harmonics to pass through.

6. The transient voltage and current fast protection method as described in claim 5, characterized in that: The main control module also includes a method that uses the normal three-phase voltage of the system as the basis for parameter adjustment, adopts a multi-parameter criterion method, uses the hardware-synthesized zero-sequence voltage and three-phase current as criteria, synthesizes the three-phase voltage to obtain the zero-sequence voltage through hardware circuit, and introduces the three-phase current signal into the main control chip. Multiple algorithms are used in the main control chip to comprehensively consider the relationship between voltage and current. A start button is set up to trigger the system to start running. At the same time, a parameter adjustment circuit is designed to compensate and adjust the phase and amplitude of the three-phase voltage and current by adjusting potentiometers or using digital potentiometers. The main control chip outputs corresponding control signals through DAC according to the actual measurement conditions to adjust the parameters of the circuit. The three-phase voltages are synthesized using hardware circuitry to obtain the zero-sequence voltage. An adder circuit composed of operational amplifiers, resistors, capacitors, and other components is used to add the three-phase voltage signals and divide them by 3 to obtain the zero-sequence voltage. Switching control is achieved using control relays or analog switches. The main control chip outputs corresponding control signals according to the system's operating voltage level to control the on / off state of the relays or analog switches, switching between different voltage divider circuits and measurement channels.

7. The transient voltage and current fast protection method as described in claim 6, characterized in that: The main control module also includes a main control chip that outputs corresponding control signals through an optocoupler isolation circuit to drive the trigger circuit of the thyristor, and at the same time, sets up overcurrent and overvoltage protection circuits. Two input channels are configured: one for receiving external control signals and the other for receiving a reset signal from the PLC. When the system malfunctions or needs to be restarted, the PLC sends a reset signal, which is then introduced to the main control chip via hardware circuitry to restore the system to its initial state. The input circuitry uses optocoupler isolation technology to electrically isolate external signals from the main control chip. One output channel is configured to control the boost system. When the system detects a fault or requires boost operation, the main control chip outputs a corresponding control signal through the output circuitry to drive the boost system to perform the boost operation. The output circuitry uses relays or power transistors as switching elements. An automatic delay reset circuit can be set with a delay time of 50ms. When the system detects that the fault has been cleared, the delay timer will start automatically and send a reset signal after 50ms to restore normal operation.

8. A transient voltage and current fast protection system, employing the transient voltage and current fast protection method as described in any one of claims 1 to 7, characterized in that, include: Sensing module, main control module, parallel protection module; The sensing module is connected to the low-voltage side line and the high-voltage side line. It transforms the high-voltage voltage and low-voltage side current into voltage and current parameters with lower amplitudes. The transformed voltage and current parameters are then input into the main control module for sampling, measurement, and calculation. The main control module receives voltage and current parameters from the sensing module, determines whether a personal electric shock fault has occurred in the boost system based on the voltage and current parameters, and drives the parallel protection module to operate when a fault is determined to have occurred. The main control module also notifies the booster system to trip the upstream and downstream switchgear when a fault occurs; The parallel protection module is a power electronic switch connected in parallel on the line between the low-voltage power supply and the low-voltage side of the step-up transformer. It receives and executes the action commands from the main control module.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the transient voltage and current fast protection method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the transient voltage and current fast protection method according to any one of claims 1 to 7.

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