CN116106696A - Ring main unit partial discharge on-line monitoring device and method based on electric field coupling - Google Patents
Ring main unit partial discharge on-line monitoring device and method based on electric field coupling Download PDFInfo
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Abstract
The invention belongs to the technical field of ring main unit partial discharge on-line monitoring, and particularly relates to an electric field coupling-based ring main unit partial discharge on-line monitoring device and method; the device comprises metal coupling pieces arranged on the cable surface of the inlet and outlet end of the ring main unit, wherein each phase of metal coupling piece is connected with the input end of a corresponding phase passive high-pass filter by a wire, the output end of each phase of passive high-pass filter is connected with the input end of a corresponding phase signal conditioning circuit, and the power ground end of each phase of passive high-pass filter is connected with the ground; the output end of each phase of the phase conditioning circuit is connected with the input end of the corresponding phase high-speed analog-to-digital conversion circuit; the output end of each phase of high-speed analog-to-digital conversion circuit is connected with the input end of the field programmable gate series module; the field programmable gate series module is connected with a corresponding interface of the microprocessor module; the invention does not need expensive sensors and is not influenced by environmental noise during measurement, and meanwhile, the partial discharge information in the cable connector at the inlet end of the ring main unit can be accurately measured.
Description
Technical Field
The invention belongs to the technical field of ring main unit partial discharge on-line monitoring, and particularly relates to an electric field coupling-based ring main unit partial discharge on-line monitoring device and method.
Background
The Ring Main Unit (Ring Main Unit) is a group of electric equipment (high-voltage switch equipment) which is arranged in a metal or nonmetal insulating cabinet body or is made into an assembled interval Ring Main power supply Unit, and the core part of the Ring Main Unit adopts a load switch and a fuse, so that the Ring Main Unit has the advantages of simple structure, small volume, low price, capability of improving power supply parameters and performance, power supply safety and the like. The system is widely used in power distribution stations of load centers such as urban residential communities, high-rise buildings, large public buildings, factory enterprises and the like and box-type substations; the ring main unit is often made into an assembly interval type in an urban power supply system, and is important switching equipment of the ring main unit. Along with the increasing of the electric power demands of China, the usage amount of the ring main unit increases, so that the ring main unit adopts a miniaturized design, the internal structure of the ring main unit is more compact, and the inter-phase insulation distance in the ring main unit is reduced. The electric field intensity of different components in the ring main unit has difference, and once the electric field intensity of the part exceeds the breakdown field intensity, the part can generate partial discharge. At present, the monitoring method of partial discharge in the ring main unit uses a super-high frequency method and an ultrasonic method, and the super-high frequency method and the ultrasonic method are used for acquiring the internal discharge information of the ring main unit through a high-frequency probe and an ultrasonic probe which are arranged outside the ring main unit, so that the measuring result is greatly influenced by environmental background noise and is high in price.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide an on-line monitoring device and method for partial discharge of a ring main unit based on electric field coupling.
The purpose of the invention is realized in the following way: the ring main unit partial discharge on-line monitoring device based on electric field coupling comprises a metal coupling sheet arranged on the surface of a cable at the inlet and outlet end of the ring main unit, wherein the metal coupling sheet comprises an A-phase metal coupling sheet, a B-phase metal coupling sheet and a C-phase metal coupling sheet which are respectively corresponding to each phase of cable, each phase of metal coupling sheet is connected with the input end of a corresponding phase passive high-pass filter by a wire, the output end of each phase of passive high-pass filter is connected with the input end of a corresponding phase signal conditioning circuit, and the power ground end of each phase of passive high-pass filter is connected with the ground; the output end of the signal conditioning circuit of each phase is connected with the input end of the corresponding phase high-speed analog-to-digital conversion circuit; the output end of each phase of the high-speed analog-to-digital conversion circuit is connected with the input end of the field programmable gate series module; the field programmable gate series module is connected with a corresponding interface of the microprocessor module; the input end of the man-machine interaction module is connected with the I/O port of the output end of the microprocessor module; the input end of the FLASH memory module is connected with the I/O port of the output end of the microprocessor module; the input end of the RS485 module is connected with a communication interface corresponding to the microprocessor module; the output end of the RS485 module is connected with the input end of the 4G communication module; the power supply module is respectively connected with the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module, the FLASH storage module, the RS485 module and the 4G communication module corresponding to the power supply interfaces to provide working power for the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module and the FLASH storage module.
The metal coupling sheet is made of aluminum foil or copper foil, and is wrapped on the surface of the cable in a winding manner; the passive high-pass filter adopts a high-pass Ethernet transformer with the band-pass frequency of 100kHz-100MHz, and the model is HR601680.
The signal conditioning circuit adopts an AD8065 voltage feedback amplifier to convert an alternating current signal of +/-5V output by the passive high-pass filter into 1-3V; the high-speed analog-to-digital conversion circuit adopts a high-speed analog-to-digital converter with the model of AD9226, and utilizes 50MHz sampling frequency to perform A/D conversion, and the partial discharge voltage is not lower than mV level.
The field programmable gate series module adopts an FPGA chip with the model of IS61WV20488BLL-10 TI; the microprocessor module adopts a microcontroller with the model of STM32F407ZGT 6.
The man-machine interaction module adopts a high-definition resistor screen with the model of TJC4827X543_011, the resolution of the touch screen is 480 multiplied by 272, the working voltage is 4.65V-6.5V, the UART serial port is used for communicating with the microprocessor module, and the man-machine interaction interface is displayed through a TJC4827X543_011 liquid crystal display.
The power supply module adopts a HIECUBAEC/DC power supply module with the model of HE05P15LRN, converts 220VAC into 5V DC, and converts 5V into 3.3V by using an LM1117-3.3V low-voltage-drop voltage-stabilizing chip; the FLASH memory module adopts a W25Q64 chip with the capacity of 64Mb, and adopts an electric erasing and writing electric gate, changes the state after being electrified, and fixes the state when not electrified.
The RS485 module adopts an isolated RS-485 module; the 4G communication module adopts a 4G DTU with the model of USR-G780V 2, realizes a bidirectional transmission function by converting RS232/485 into 4G, and supports 4G full network communication.
The main interface of the man-machine interaction module comprises a selectable partial discharge selection sub-interface, a parameter setting sub-interface, an equipment electric quantity sub-interface and a partial discharge history sub-interface, wherein the partial discharge selection sub-interface comprises an A-phase waveform, a B-phase waveform, a C-phase waveform, an A-phase frequency spectrum, a B-phase frequency spectrum and a C-phase frequency spectrum sub-interface which can be selected and inquired, and the parameter setting comprises a selectable time setting sub-interface and an address setting sub-interface.
The ring main unit partial discharge on-line monitoring method based on electric field coupling uses the ring main unit partial discharge on-line monitoring device based on electric field coupling, and comprises the following steps:
firstly, initializing the whole system of the device, wherein the software design of a partial discharge high-speed acquisition part is realized by a microprocessor module and a field programmable gate series module together, the microprocessor module controls the field programmable gate series module to acquire partial discharge signals, and the field programmable gate series module and a high-speed analog-to-digital conversion circuit work together to acquire the partial discharge signals; the field programmable gate series module stores the acquired partial discharge signals in an external SRAM, then sends acquisition completion instructions to the microprocessor module, and transmits the partial discharge data to the microprocessor module through FSMC communication; after the microprocessor module processes the data, deducing the occurrence of partial discharge; when the partial discharge pulse waveform is acquired, a fast Fourier transform program is called in a microprocessor module to process the waveform to obtain a partial discharge spectrum, and the partial discharge waveform or the partial discharge spectrum can be selectively displayed on a man-machine interaction module; the acquisition of partial discharge signals of one phase is completed through the steps, then a microprocessor module sends an instruction to a field programmable gate series module, the steps are repeated to complete the acquisition of partial discharge signals of the other two phases, and finally the acquisition of three-phase partial discharge signals can be realized; after the data are stored, the monitored partial discharge data are transmitted to a server by utilizing the 4G communication module, and the database can be called in a background management system to check the partial discharge data.
The invention has the beneficial effects that: the invention discloses an electric field coupling-based ring main unit partial discharge on-line monitoring device, which comprises metal coupling sheets arranged on the surfaces of cables at the inlet and outlet ends of a ring main unit, wherein each metal coupling sheet comprises an A-phase metal coupling sheet, a B-phase metal coupling sheet and a C-phase metal coupling sheet which correspond to each phase of cable respectively, each phase of metal coupling sheet is connected with the input end of a corresponding phase passive high-pass filter through a wire, the output end of each phase of passive high-pass filter is connected with the input end of a corresponding phase signal conditioning circuit, and the power ground end of each phase of passive high-pass filter is connected with the ground; the output end of the signal conditioning circuit of each phase is connected with the input end of the corresponding phase high-speed analog-to-digital conversion circuit; the output end of each phase of the high-speed analog-to-digital conversion circuit is connected with the input end of the field programmable gate series module; the field programmable gate series module is connected with a corresponding interface of the microprocessor module; the input end of the man-machine interaction module is connected with the I/O port of the output end of the microprocessor module; the input end of the FLASH memory module is connected with the I/O port of the output end of the microprocessor module; the input end of the RS485 module is connected with a communication interface corresponding to the microprocessor module; the output end of the RS485 module is connected with the input end of the 4G communication module; the power supply module is respectively connected with the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module, the FLASH storage module, the RS485 module and the 4G communication module corresponding to the power interfaces to provide working power for the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module and the 4G communication module; the software design of the partial discharge high-speed acquisition part is jointly realized by a microprocessor module and a field programmable gate series module, the microprocessor module controls the field programmable gate series module to acquire partial discharge signals, and the field programmable gate series module and the high-speed analog-to-digital conversion circuit jointly work to acquire the partial discharge signals; the field programmable gate series module stores the acquired partial discharge signals in an external SRAM, then sends acquisition completion instructions to the microprocessor module, and transmits the partial discharge data to the microprocessor module through FSMC communication; after the microprocessor module processes the data, deducing the occurrence of partial discharge; when the partial discharge pulse waveform is acquired, a fast Fourier transform program is called in a microprocessor module to process the waveform to obtain a partial discharge spectrum, and the partial discharge waveform or the partial discharge spectrum can be selectively displayed on a man-machine interaction module; the acquisition of partial discharge signals of one phase is completed through the steps, then a microprocessor module sends an instruction to a field programmable gate series module, the steps are repeated to complete the acquisition of partial discharge signals of the other two phases, and finally the acquisition of three-phase partial discharge signals can be realized; after the data are stored, the monitored partial discharge data are transmitted to a server by utilizing a 4G communication module, and a database can be called in a background management system to check the partial discharge data; according to the ring main unit partial discharge on-line monitoring device and method based on electric field coupling, the metal sheet arranged on the surface of the cable at the inlet and outlet ends of the ring main unit is utilized, the electric field coupling principle is utilized, the metal sheet and the cable inner conductor, and two serially connected distributed capacitances formed between the metal sheet and the ground are utilized, then the series impedance voltage division principle is utilized, the discharge information in the high-voltage cable is obtained through the metal sheet, an expensive sensor is not needed, the influence of environmental noise is avoided during measurement, and meanwhile, the partial discharge information in the cable joint at the inlet end of the ring main unit can be accurately measured.
Drawings
Fig. 1 is a diagram of an overall structure of an on-line monitoring device for partial discharge of a ring main unit based on electric field coupling.
Fig. 2 is a schematic diagram of a principle of the ring main unit partial discharge on-line monitoring device based on electric field coupling according to the present invention, wherein the principle is that a metal coupling sheet obtains a partial discharge signal.
Fig. 3 is a schematic diagram of a passive high-pass filter of the ring main unit partial discharge on-line monitoring device based on electric field coupling.
Fig. 4 is a schematic diagram of connection between a passive high-pass filter, a signal conditioning circuit and a high-speed analog-to-digital conversion circuit of the ring main unit partial discharge on-line monitoring device based on electric field coupling.
Fig. 5 is a schematic diagram of a communication model of an on-line monitoring device FPGA and an STM32 of ring main unit partial discharge based on electric field coupling.
Fig. 6 is a schematic diagram of an online monitoring method of partial discharge of a ring main unit based on electric field coupling.
Fig. 7 is a schematic diagram of a man-machine interaction module display interface of the ring main unit partial discharge on-line monitoring device based on electric field coupling.
FIG. 8 is a schematic diagram of the flow of inquiring peak voltage by the device and method for monitoring partial discharge of the ring main unit on line based on electric field coupling.
Fig. 9 is a schematic diagram of a partial discharge data reading flow in the SRAM of the ring main unit partial discharge on-line monitoring device based on electric field coupling according to the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The ring main unit partial discharge on-line monitoring device based on electric field coupling is shown in fig. 1, and comprises metal coupling sheets arranged on the cable surface of the inlet and outlet end of the ring main unit, wherein each metal coupling sheet comprises an A-phase metal coupling sheet, a B-phase metal coupling sheet and a C-phase metal coupling sheet which are respectively corresponding to each phase of cable, each phase of metal coupling sheet is connected with the input end of a corresponding phase passive high-pass filter through a wire, the output end of each phase of passive high-pass filter is connected with the input end of a corresponding phase signal conditioning circuit, and the power ground end of each phase of passive high-pass filter is connected with the ground; the output end of the signal conditioning circuit of each phase is connected with the input end of the corresponding phase high-speed analog-to-digital conversion circuit; the output end of each phase of the high-speed analog-to-digital conversion circuit is connected with the input end of the field programmable gate series module; the field programmable gate series module is connected with a corresponding interface of the microprocessor module; the input end of the man-machine interaction module is connected with the I/O port of the output end of the microprocessor module; the input end of the FLASH memory module is connected with the I/O port of the output end of the microprocessor module; the input end of the RS485 module is connected with a communication interface corresponding to the microprocessor module; the output end of the RS485 module is connected with the input end of the 4G communication module; the power supply module is respectively connected with the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module, the FLASH storage module, the RS485 module and the 4G communication module corresponding to the power supply interfaces to provide working power for the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module and the FLASH storage module.
The metal coupling sheet is wrapped on the surface of the cable in a winding way by adopting an aluminum foil or copper foil with the thickness of 0.1mm, and the discharge information in the high-voltage cable is obtained through the metal sheet by utilizing the electric field coupling principle and utilizing the distributed capacitance formed by the metal sheet, the cable inner conductor and the metal sheet and the ground which are connected in series; the passive high-pass filter adopts a high-pass Ethernet transformer with the band-pass frequency of 100kHz-100MHz, has the model of HR601680, can filter signals lower than 100kHz, can keep undistorted transmission partial discharge signals, and can play roles in signal isolation and low-frequency signal suppression.
The signal conditioning circuit adopts an AD8065 voltage feedback amplifier to convert an alternating current signal of +/-5V output by the passive high-pass filter into 1-3V; the high-speed analog-to-digital conversion circuit adopts a high-speed analog-to-digital converter with the model of AD9226, utilizes 50MHz sampling frequency to perform A/D conversion, and has partial discharge voltage not lower than mV level, 12-bit precision can meet the sampling precision of partial discharge signals, the AD9226 adopts a multi-stage differential pipeline structure with error correction logic, and accurate 12-bit data can be acquired under the sampling rate of 65 Msps.
The field programmable gate series module adopts an FPGA chip with the model of IS61WV20488BLL-10TI, which IS a 2 Mx 8 high-speed CMOS static RAM chip, and the ring main unit partial discharge on-line monitoring device acquires 1.5 Mbyte partial discharge data once, and the chip can meet the requirement; the microprocessor module adopts a microcontroller with the model of STM32F407ZGT6, has low cost and high performance, has the refreshing frequency of 3300W pixels/second, is suitable for a system needing to be used in an FPU or a DSP, has abundant I/O port peripheral pins, and can meet the requirements of industrial control; the STM32 reads partial discharge data in the SRAM by means of the FPGA, the reading efficiency can be accelerated by using FSMC communication, and the FSMC is a flexible static memory controller which can change AHB transmission signals into an adaptive peripheral protocol and accords with the timing condition of accessing the peripheral. FSMC manages 1GB memory, and is equipped with 4 banks connected with external memory, each Bank has separate chip select signals and separate timing configuration, and FSMC supports various memory types. The LPM macro module in the FPGA is used for generating an SRAM and an FSMC logic control circuit, the memory controller FSMC in the STM32 is used, and the data transmission between the STM32 and the FPGA cooperative controller is completed by adopting an independent address mode of an FSMC parallel bus.
When the STM32 is in communication with the FPGA, the FPGA can be regarded as an external SRAM of the STM32, so that the configuration requirement of the FPGA is similar to that of the external SRAM, the SRAM is controlled by a NOR Flash of the FSMC, and the STM32 uses a non-multiplexing mode of a GPIO port.
The SRAM IS mainly used for a second-level cache, data with higher use frequency IS copied in the second-level cache, a CPU can be accessed quickly, the SRAM uses a transistor to finish data storage operation, an SRAM chip selected in the device IS IS61WV20488BLL-10TI, in the SRAM, a storage array arranged in a matrix mode IS surrounded by a decoder and an interface circuit connected with external signals, and in order to reduce the whole area of the chip and facilitate data access, the storage array adopts a rectangular or matrix mode. Only one SRAM is needed in the ring main unit partial discharge on-line monitoring device, so that the CE level is set low, and the writing operation of the SRAM can be realized by converting the high level and the low level of WE.
SRAM writing step:
(1) Determining writing information according to the address bus;
(2) Transmitting data to be written through a data bus;
(3) Activating a CS selection chip;
(4) Activating WE tells the SRAM to write.
The man-machine interaction module adopts a high-definition resistor screen with the model of TJC4827X543_011, the resolution of the touch screen is 480 multiplied by 272, the working voltage is 4.65V-6.5V, the UART serial port is used for communicating with the microprocessor module, and the man-machine interaction interface is displayed through a TJC4827X543_011 liquid crystal display.
The power supply module adopts a HIECUBAEC/DC power supply module with the model of HE05P15LRN, converts 220VAC into 5V DC, and converts 5V into 3.3V by using an LM1117-3.3V low-voltage-drop voltage-stabilizing chip; the FLASH memory module adopts a W25Q64 chip with the capacity of 64Mb, and adopts an electric erasing and writing electric gate, changes state after being electrified, and is fixed after not electrified, and the stored data of the FLASH memory module cannot be lost after the system is powered off, so that the FLASH memory module is suitable for storing software programs. The erasing period of the W25Q64 can reach 10W times, the data can be stored for 20 years, and the FLASH program is called to run when the FPGA is powered on.
The RS485 module adopts an isolated RS-485 module; the 4G communication module adopts a 4G DTU with the model of USR-G780V 2, realizes a bidirectional transmission function by converting RS232/485 into 4G, supports 4G full network communication, has the characteristics of high speed and low delay, and most importantly, the module can realize edge acquisition, cloud acquisition and cloud data transfer, can realize soft and hard integrated systematic solution through someone cloud, provides equipment monitoring, remote configuration, remote upgrading and automatic positioning, and is suitable for data communication between an online monitoring device and a background management system.
The main interface of the man-machine interaction module comprises a selectable partial discharge selection sub-interface, a parameter setting sub-interface, a device electric quantity sub-interface and a partial discharge history sub-interface, wherein the partial discharge selection sub-interface comprises an A-phase waveform, a B-phase waveform, a C-phase waveform, an A-phase frequency spectrum, a B-phase frequency spectrum and a C-phase frequency spectrum sub-interface which can be selected and inquired, and the parameter setting comprises a selectable time setting sub-interface and an address setting sub-interface; the current time and the address can be adjusted through the set sub-interface, and the thresholds of the partial discharge waveform and the frequency spectrum can be adjusted in the partial discharge selection interface.
The electric field coupling-based ring main unit partial discharge on-line monitoring method uses the electric field coupling-based ring main unit partial discharge on-line monitoring device, and the working flow is shown in figure 6, and the method comprises the following steps:
firstly, initializing the whole system of the device, wherein the software design of a partial discharge high-speed acquisition part is realized by a microprocessor module and a field programmable gate series module together, the microprocessor module controls the field programmable gate series module to acquire partial discharge signals, and the field programmable gate series module and a high-speed analog-to-digital conversion circuit work together to acquire the partial discharge signals; the field programmable gate series module stores the acquired partial discharge signals in an external SRAM, then sends acquisition completion instructions to the microprocessor module, and transmits the partial discharge data to the microprocessor module through FSMC communication; after the microprocessor module processes the data, deducing the occurrence of partial discharge; when the partial discharge pulse waveform is acquired, a fast Fourier transform program is called in a microprocessor module to process the waveform to obtain a partial discharge spectrum, and the partial discharge waveform or the partial discharge spectrum can be selectively displayed on a man-machine interaction module; the acquisition of partial discharge signals of one phase is completed through the steps, then a microprocessor module sends an instruction to a field programmable gate series module, the steps are repeated to complete the acquisition of partial discharge signals of the other two phases, and finally the acquisition of three-phase partial discharge signals can be realized; after the data are stored, the monitored partial discharge data are transmitted to a server by utilizing the 4G communication module, and the database can be called in a background management system to check the partial discharge data.
The principle of the metal coupling sheet for obtaining partial discharge signals is shown in fig. 2, the electric field coupling principle is utilized, a capacitor C1 formed by the metal sheet and an inner conductor of the cable and a stray capacitor C2 formed between the metal sheet and the ground are connected in series, and then the series impedance voltage division principle is utilized, so that the discharge information in the high-voltage cable is obtained through the metal sheet.
The capacitive reactance Xc1 of C1 is:
the capacitive reactance Xc2 of C2 is:
the two capacitive reactance forms a voltage division attenuation to the input signal, so that the amplitude of the output signal can be reduced, the capacitive reactance of the capacitor is related to the capacitance value and the frequency, and since the frequency of the signal passing through each capacitor in the capacitive voltage division circuit is the same, only the values of C1 and C2 affect the capacitive reactance.
The connection principle of the passive high-pass filter, the signal conditioning circuit and the high-speed analog-to-digital conversion circuit is shown in fig. 4, the input voltage range of the VIN pin of the AD9226 is between 1 and 3V, and the voltage of the partial discharge signal exceeds the range after amplification and can reach-5V to +5V, so that a voltage attenuation circuit is connected behind a network transformer to raise the voltage to 1V to 3V. The voltage attenuation circuit is realized by selecting a voltage feedback type amplifier AD8065, the working noise is low, the input impedance is high, the voltage attenuation circuit is suitable for the working environment of a ring main unit, a voltage dividing circuit is formed by RD4 and RD5, the equal proportion of-5V to +5V is reduced to-0.5V to +0.5V, then the reference voltage +2V provided by an AD9226 pin VREF is inverted to-2V through a TL072 low-noise JFET input operational amplifier, and then the voltage is converted to-5V to +5V to 1-3V through a differential amplifying circuit formed by AD8065, so that the AD9226 can normally work to realize the analog-digital conversion of partial discharge signals after the VIN input voltage of the AD9226 is met.
When the microprocessor module performs spectrum analysis on partial discharge, a fast Fourier transform method is adopted, the method essentially intercepts part of long-section signal data, however, partial discharge is an aperiodic signal, the partial discharge has contingency, the waveform of the partial discharge is irregular, the intercepted signal cannot reach integral multiple of an original signal, and because the spectrum range of the partial discharge signal is very wide and the spectrum is very complex, the spectrum leakage phenomenon is easy to occur, so that the measured data has very large errors with actual results, the window function can reduce the problem caused by the spectrum leakage, the spectrum analysis relates to the frequency point distribution of the signal, but the amplitude precision of each frequency point does not need to be particularly accurate, so that the Hanning window function can eliminate the leakage effect and improve the measurement precision when reducing the calculated amount for 4096 data frequency domain conversion.
As shown in FIG. 5, the FPGA and STM32 communication model stores 150 tens of thousands of data in the ring main unit partial discharge on-line monitoring device, each data is 8 bits, and the FSMC selects a data line multiplexing mode due to the limited I/O ports of the FPGA. When FSMC_NADV is at high level, signals transmitted by the data line are used as data lines, when FSMC_NADV is at logic 0, the signals transmitted by the data lines are used as address signals, FSMC_A [20:16] and FSMC_D [15:0] are address bits, the data bits are FSMC_D [7:0], RST_FPGA is a reset signal in FPGA, and channel [1:0] can determine what path of ADC data is transmitted, READY indicates that the FPGA finishes acquisition of partial discharge data, and STM32 can realize high-speed data communication with the FPGA after completion.
The flow of inquiring the peak voltage is shown in fig. 8, the ring main unit partial discharge on-line monitoring device acquires 500k data within 10ms, and in the face of such huge data volume, the system cannot process rapidly, but in consideration of timeliness of on-site real-time monitoring, the accuracy of the acquired partial discharge data is kept, 4096 data around the voltage peak can be selectively processed, the storage address of the 4096 data in the SRAM can be searched, after the address is found, the 4096 partial discharge voltage data in the SRAM is read through the STM32, and the partial discharge data in the SRAM is read as shown in fig. 9.
SRAM reading step:
(1) Sending a bit address to be read from an address bus to an address pin;
(2) Activating CS pins to select an SRAM chip;
(3) The active OE pin tells the SRAM to perform read operation;
(4) And transmitting the data corresponding to the address through a data bus.
In summary, the ring main unit partial discharge on-line monitoring device based on electric field coupling comprises a metal coupling sheet arranged on the surface of a cable at the inlet and outlet end of the ring main unit, wherein the metal coupling sheet comprises an A-phase metal coupling sheet, a B-phase metal coupling sheet and a C-phase metal coupling sheet which are respectively corresponding to each phase of cable, each phase of metal coupling sheet is connected with the input end of a corresponding phase of passive high-pass filter through a wire, the output end of each phase of passive high-pass filter is connected with the input end of a corresponding phase of signal conditioning circuit, and the power ground end of each phase of passive high-pass filter is connected with the ground; the output end of the signal conditioning circuit of each phase is connected with the input end of the corresponding phase high-speed analog-to-digital conversion circuit; the output end of each phase of the high-speed analog-to-digital conversion circuit is connected with the input end of the field programmable gate series module; the field programmable gate series module is connected with a corresponding interface of the microprocessor module; the input end of the man-machine interaction module is connected with the I/O port of the output end of the microprocessor module; the input end of the FLASH memory module is connected with the I/O port of the output end of the microprocessor module; the input end of the RS485 module is connected with a communication interface corresponding to the microprocessor module; the output end of the RS485 module is connected with the input end of the 4G communication module; the power supply module is respectively connected with the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module, the FLASH storage module, the RS485 module and the 4G communication module corresponding to the power interfaces to provide working power for the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module and the 4G communication module; the software design of the partial discharge high-speed acquisition part is jointly realized by a microprocessor module and a field programmable gate series module, the microprocessor module controls the field programmable gate series module to acquire partial discharge signals, and the field programmable gate series module and the high-speed analog-to-digital conversion circuit jointly work to acquire the partial discharge signals; the field programmable gate series module stores the acquired partial discharge signals in an external SRAM, then sends acquisition completion instructions to the microprocessor module, and transmits the partial discharge data to the microprocessor module through FSMC communication; after the microprocessor module processes the data, deducing the occurrence of partial discharge; when the partial discharge pulse waveform is acquired, a fast Fourier transform program is called in a microprocessor module to process the waveform to obtain a partial discharge spectrum, and the partial discharge waveform or the partial discharge spectrum can be selectively displayed on a man-machine interaction module; the acquisition of partial discharge signals of one phase is completed through the steps, then a microprocessor module sends an instruction to a field programmable gate series module, the steps are repeated to complete the acquisition of partial discharge signals of the other two phases, and finally the acquisition of three-phase partial discharge signals can be realized; after the data are stored, the monitored partial discharge data are transmitted to a server by utilizing a 4G communication module, and a database can be called in a background management system to check the partial discharge data; according to the ring main unit partial discharge on-line monitoring device and method based on electric field coupling, the metal sheet arranged on the surface of the cable at the inlet and outlet ends of the ring main unit is utilized, the electric field coupling principle is utilized, the metal sheet and the cable inner conductor, and two serially connected distributed capacitances formed between the metal sheet and the ground are utilized, then the series impedance voltage division principle is utilized, the discharge information in the high-voltage cable is obtained through the metal sheet, an expensive sensor is not needed, the influence of environmental noise is avoided during measurement, and meanwhile, the partial discharge information in the cable joint at the inlet end of the ring main unit can be accurately measured.
Claims (9)
1. Ring main unit partial discharge on-line monitoring device based on electric field coupling, it is including setting up the metal coupling piece on ring main unit business turn over line end cable surface, its characterized in that: the metal coupling pieces comprise A-phase metal coupling pieces, B-phase metal coupling pieces and C-phase metal coupling pieces which correspond to the cables of all phases respectively, the metal coupling pieces of all phases are connected with the input ends of the passive high-pass filters of all phases by wires, the output ends of the passive high-pass filters of all phases are connected with the input ends of the corresponding phase signal conditioning circuits, and the power ground ends of the passive high-pass filters of all phases are connected with the ground; the output end of the signal conditioning circuit of each phase is connected with the input end of the corresponding phase high-speed analog-to-digital conversion circuit; the output end of each phase of the high-speed analog-to-digital conversion circuit is connected with the input end of the field programmable gate series module; the field programmable gate series module is connected with a corresponding interface of the microprocessor module; the input end of the man-machine interaction module is connected with the I/O port of the output end of the microprocessor module; the input end of the FLASH memory module is connected with the I/O port of the output end of the microprocessor module; the input end of the RS485 module is connected with a communication interface corresponding to the microprocessor module; the output end of the RS485 module is connected with the input end of the 4G communication module; the power supply module is respectively connected with the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module, the FLASH storage module, the RS485 module and the 4G communication module corresponding to the power supply interfaces to provide working power for the signal conditioning circuit, the high-speed analog-to-digital conversion circuit, the field programmable gate series module, the microprocessor module, the man-machine interaction module and the FLASH storage module.
2. The electric field coupling-based ring main unit partial discharge on-line monitoring device as claimed in claim 1, wherein: the metal coupling sheet is made of aluminum foil or copper foil, and is wrapped on the surface of the cable in a winding manner; the passive high-pass filter adopts a high-pass Ethernet transformer with the band-pass frequency of 100kHz-100MHz, and the model is HR601680.
3. The electric field coupling-based ring main unit partial discharge on-line monitoring device as claimed in claim 1, wherein: the signal conditioning circuit adopts an AD8065 voltage feedback amplifier to convert an alternating current signal of +/-5V output by the passive high-pass filter into 1-3V; the high-speed analog-to-digital conversion circuit adopts a high-speed analog-to-digital converter with the model of AD9226, and utilizes 50MHz sampling frequency to perform A/D conversion, and the partial discharge voltage is not lower than mV level.
4. The electric field coupling-based ring main unit partial discharge on-line monitoring device as claimed in claim 1, wherein: the field programmable gate series module adopts an FPGA chip with the model of IS61WV20488BLL-10 TI; the microprocessor module adopts a microcontroller with the model of STM32F407ZGT 6.
5. The electric field coupling-based ring main unit partial discharge on-line monitoring device as claimed in claim 1, wherein: the man-machine interaction module adopts a high-definition resistor screen with the model of TJC4827X543_011, the resolution of the touch screen is 480 multiplied by 272, the working voltage is 4.65V-6.5V, the UART serial port is used for communicating with the microprocessor module, and the man-machine interaction interface is displayed through a TJC4827X543_011 liquid crystal display.
6. The electric field coupling-based ring main unit partial discharge on-line monitoring device as claimed in claim 1, wherein: the power supply module adopts a HIECUBE AC/DC power supply module with the model of HE05P15LRN, converts 220V AC into 5V DC, and converts 5V into 3.3V by using an LM1117-3.3V low-voltage-drop voltage-stabilizing chip; the FLASH memory module adopts a W25Q64 chip with the capacity of 64Mb, and adopts an electric erasing and writing electric gate, changes the state after being electrified, and fixes the state when not electrified.
7. The electric field coupling-based ring main unit partial discharge on-line monitoring device as claimed in claim 1, wherein: the RS485 module adopts an isolated RS-485 module; the 4G communication module adopts a 4G DTU with the model of USR-G780V 2, realizes a bidirectional transmission function by converting RS232/485 into 4G, and supports 4G full network communication.
8. The electric field coupling-based ring main unit partial discharge on-line monitoring device as claimed in claim 1, wherein: the main interface of the man-machine interaction module comprises a selectable partial discharge selection sub-interface, a parameter setting sub-interface, an equipment electric quantity sub-interface and a partial discharge history sub-interface, wherein the partial discharge selection sub-interface comprises an A-phase waveform, a B-phase waveform, a C-phase waveform, an A-phase frequency spectrum, a B-phase frequency spectrum and a C-phase frequency spectrum sub-interface which can be selected and inquired, and the parameter setting comprises a selectable time setting sub-interface and an address setting sub-interface.
9. An online monitoring method for partial discharge of a ring main unit based on electric field coupling, which uses the online monitoring device for partial discharge of a ring main unit based on electric field coupling as set forth in any one of claims 1 to 8, comprising:
firstly, initializing the whole system of the device, wherein the software design of a partial discharge high-speed acquisition part is realized by a microprocessor module and a field programmable gate series module together, the microprocessor module controls the field programmable gate series module to acquire partial discharge signals, and the field programmable gate series module and a high-speed analog-to-digital conversion circuit work together to acquire the partial discharge signals; the field programmable gate series module stores the acquired partial discharge signals in an external SRAM, then sends acquisition completion instructions to the microprocessor module, and transmits the partial discharge data to the microprocessor module through FSMC communication; after the microprocessor module processes the data, deducing the occurrence of partial discharge; when the partial discharge pulse waveform is acquired, a fast Fourier transform program is called in a microprocessor module to process the waveform to obtain a partial discharge spectrum, and the partial discharge waveform or the partial discharge spectrum can be selectively displayed on a man-machine interaction module; the acquisition of partial discharge signals of one phase is completed through the steps, then a microprocessor module sends an instruction to a field programmable gate series module, the steps are repeated to complete the acquisition of partial discharge signals of the other two phases, and finally the acquisition of three-phase partial discharge signals can be realized; after the data are stored, the monitored partial discharge data are transmitted to a server by utilizing the 4G communication module, and the database can be called in a background management system to check the partial discharge data.
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| CN116400180A (en) * | 2023-05-17 | 2023-07-07 | 国网北京市电力公司检修分公司 | Partial discharge recognition system and method |
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| CN116400180A (en) * | 2023-05-17 | 2023-07-07 | 国网北京市电力公司检修分公司 | Partial discharge recognition system and method |
| CN116400180B (en) * | 2023-05-17 | 2023-11-14 | 国网北京市电力公司检修分公司 | Partial discharge recognition system and method |
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