CN204203344U - A kind of resonance overvoltage monitoring device - Google Patents

Abstract

The utility model relates to a resonance overvoltage monitoring device. Including a microcontroller, a communication module for communicating with the master station, a sampling chip for sampling voltage signals, a voltage conversion circuit, a front-end voltage transformer set on a 10kV or 35kV bus and a power supply for powering the entire device circuit; the microcontroller is connected to the sampling chip through the SPI serial communication interface, and is connected to the front-end voltage transformer through the sampling chip and the voltage conversion circuit, and the microcontroller is also connected through the USART serial communication interface It is connected with the communication module; the power supply circuit includes a filter module, a step-down module, a rectifier module and a voltage stabilization module connected in sequence, and the input end of the filter module is connected to a 220V AC power supply. The utility model has a simple circuit structure, is easy to implement, is convenient for practical application and popularization, and has broad market prospects.

Description

A resonant overvoltage monitoring device

technical field

The utility model relates to a resonance overvoltage monitoring device.

Background technique

In the small current grounding system of distribution network, the ferromagnetic resonance of voltage transformer is a common fault. When a certain impact disturbance occurs, the resulting transient impact process will excite ferromagnetic resonance between the PT and the capacitance of the three-phase wires to the ground, resulting in system overvoltage and PT overcurrent. At present, in order to suppress ferromagnetic resonance, the voltage on the secondary side of the PT is monitored and collected, the waveform is judged and identified in the main power distribution station, and finally the resonance is eliminated by connecting a damping resistor in series.

At present, there are few optional terminals for monitoring PT resonance overvoltage in the market, and the processing speed of the single-chip microcomputer used is not fast enough, the sampling rate is low, and the function is single. It is not easy to expand the function of the monitoring device, and it is also not suitable for use. In order to realize complex algorithms, it is difficult to meet the needs of the development of distribution network automation construction.

Contents of the invention

The purpose of the utility model is to provide a resonant overvoltage monitoring device with simple circuit structure and easy realization.

In order to achieve the above purpose, the technical solution of the utility model is: a resonant overvoltage monitoring device, including a microcontroller, a communication module for communicating with the master station, a sampling chip for sampling voltage signals, a voltage conversion circuit, The front-end voltage transformer set on the 10kV or 35kV bus and the power supply circuit used to supply power to the entire device; the microcontroller is connected to the sampling chip through the SPI serial communication interface, and the sampling chip and the voltage conversion circuit It is connected with the front-end voltage transformer, and the microcontroller is also connected with the communication module through a USART serial communication interface; the power supply circuit includes a filter module, a step-down module, a rectifier module and a voltage stabilization module connected in sequence, The input end of the filtering module is connected to a 220V AC power supply.

In the embodiment of the utility model, the microcontroller adopts the STM32F407VGT6 chip.

In the embodiment of the utility model, the voltage conversion circuit includes a closed-loop Hall voltage sensor, and the closed-loop Hall voltage sensor adopts HCV-10E.

In the embodiment of the utility model, the sampling chip adopts AD7606.

In the utility model embodiment, described communication module is GPRS module, and this GPRS module adopts ME3000 V2.

In the embodiment of the utility model, the voltage stabilizing module adopts a two-way voltage stabilizing chip LM2596, which is used to convert the DC voltage output by the rectifying module to 5V and output a 4.2V DC voltage for powering GPRS, wherein, The 5V DC voltage is converted to 12V and 3.3V by switching power supply and 3.3V regulator chip respectively.

Compared with the prior art, the utility model has the following beneficial effects:

1. The utility model adopts the high-performance and low-cost STM32F407VGT6, which has high sampling rate and high sampling accuracy, and provides good support for analyzing and responding to PT resonance overvoltage in the distribution network;

2. Through the GPRS communication network, the scheme is easy to implement, with high transmission reliability, stable communication, convenient on-site installation, and reduces the need to lay separate communication lines; realize remote PT resonance overvoltage monitoring; when PT overvoltage occurs, the monitoring device can timely alarm and upload The data reduces the workload, improves the automation level, provides a good foundation for the staff to analyze the data, and ensures the safe and stable operation of the equipment. The development of the utility model has strong practical significance and practical value.

Description of drawings

Fig. 1 is a functional block diagram of a resonant overvoltage monitoring device of the present invention.

Fig. 2 is an application block diagram of the resonant overvoltage monitoring device of the present invention.

Fig. 3 is a functional block diagram of the power supply circuit of the present utility model.

Fig. 4 is a schematic diagram of the utility model power supply circuit.

Fig. 5 is a pin connection diagram of the sampling chip of the present invention.

Fig. 6 is a pin connection diagram of the microcontroller of the present invention.

Fig. 7 is a pin connection diagram of the GPRS module of the present invention.

detailed description

Below in conjunction with accompanying drawing, the technical solution of the utility model is described in detail.

A resonant overvoltage monitoring device of the present invention includes a microcontroller (using STM32F407VGT6 chip), a communication module for communicating with the master station (the communication module is a GPRS module, and the GPRS module adopts ME3000 V2), and A sampling chip for sampling voltage signals (adopting AD7606), a voltage conversion circuit, a front-end voltage transformer set on a 10kV or 35kV bus, and a power supply circuit for supplying power to the entire device; the microcontroller communicates through the SPI serial interface Connected to the sampling chip, and connected to the front-end voltage transformer through the sampling chip and the voltage conversion circuit, the microcontroller is also connected to the communication module through the USART serial communication interface; the power supply circuit includes sequentially Connected filter module, step-down module, rectifier module and voltage stabilizing module, the input end of the filter module is connected to 220V AC power supply.

The voltage conversion circuit includes a closed-loop Hall voltage sensor, and the closed-loop Hall voltage sensor adopts HCV-10E.

The voltage stabilizing module adopts two-way voltage stabilizing chips LM2596, which are used to convert the DC voltage output by the rectifying module to 5V and to output the 4.2V DC voltage for powering GPRS, wherein the 5V DC voltage is passed through the switching power supply and the DC voltage respectively. The 3.3V regulator chip converts to 12V and 3.3V voltage.

In order to better describe the utility model, the specific working principle of the utility model will be described in detail below in conjunction with the hardware circuit of the utility model and the existing software. It should be noted that the part related to the software description is not the protection content of the utility model.

As shown in Figure 1 , the resonant overvoltage monitoring terminal of the utility model includes a voltage conversion circuit 2 , a sampling chip 3 , a microcontroller 4 , a communication module 5 , and a power supply 6 . The microcontroller 4 is connected to the sampling chip 3 through an SPI serial communication interface, and the microcontroller 4 is connected to the communication module 5 through a USART serial communication.

The three-phase voltage and zero-sequence voltage signal 1 of the secondary side of the front-end voltage transformer PT (connected to the 10kV or 35kV bus) are input to the device. The voltage is converted into mA-level current through the closed-loop Hall voltage transformer HCV-10E, and then the voltage is obtained by flowing through the measuring resistor RM, and the voltage signal (between -10V~+10V) is sent to the sampling chip 3 . The sampling chip 3 converts the analog voltage quantity into a digital quantity, and the microcontroller 4 reads the analog-to-digital conversion value by means of SPI serial communication, and judges whether overvoltage occurs. If it is judged to be overvoltage, start the communication module 5, send data and upload the sampled voltage signal to the host computer (remote monitoring computer) via the communication module 5 (GPRS module).

The microcontroller 4 initiates a voltage conversion every 0.1 ms and stores the data in its own buffer. After each collection of 0.02s, the overvoltage judgment is made on the data. Data buffer up to 4800 16-bit data.

It can be seen from attached drawings 3 and 4 that the power input is a 220V AC power supply, first through the front-end filter and protection circuit to prevent lightning overvoltage or overvoltage intrusion waves in the power grid, and eliminate common-mode interference and filter out high-frequency harmonics The wave component is then stepped down by the transformer to the AC voltage of 6V, and then through the uncontrollable rectification circuit, the capacitor filter circuit, and the two-way voltage regulator chip LM2596 to obtain DC 5V and 4.2V. Among them, 4.2V is used as the power supply of the GPRS module. The 5V voltage is raised to ±12V by the switching power supply DY05D12-2W as the power supply for the closed-loop voltage Hall sensor HCV-10E, and then raised to 12V by the switching power supply DY05S12-1W as the power supply for the relay output, and then dropped by the LM1117-3.3 voltage regulator chip. Up to 3.3V is used as the power supply of the main control board, which is used for the microcontroller, communication module and LED operation indication. The power supply of sampling chip AD7606 is composed of 2.5V, 3.3V and 5V. The 2.5V voltage is obtained by stepping down the 3.3V through the precision voltage regulator chip ADR421.

As shown in Figure 6, the MCU uses the STM32F407VGT6 microcontroller from STMicroelectronics. The microcontroller has a 32-bit CPU, a Cortex-M4 core, 100 pins, a 1MB program memory, a 192KB SRAM and a 4KB backup storage area, and three 10.5Mb/s USARTs Interface, three 37.5Mb/s SPI. It integrates single-cycle DSP instructions and FPU (floating point unit), supports the calculation of complex algorithms, and is conducive to fast and processing the voltage signal obtained by sampling.

As shown in Figure 1 and Figure 5, the sampling chip 3 uses AD7606 with 16-bit precision and 8-channel synchronous sampling. The conversion rate is up to 200kSPs. In the resonant overvoltage monitoring terminal of the utility model, there are 4 sampling inputs, which are respectively connected to the PT three-phase opening (the zero-sequence voltage is measured), and the A phase, B phase, and C phase of the secondary side. The main connections between the sampling chip AD7606 and the microcontroller 4 are data lines and control lines. Since this device adopts the SPI serial communication mode, the DB7 of the sampling chip 3 is connected to the SPI1_MISO single data line of the microcontroller 4, and the SPI communication needs a clock line, and the SPI1_SCK pin of the microcontroller 4 is connected to the SCK of the sampling chip 3 connection, thereby controlling the speed of reading data after AD conversion. The PC4 pin of the microcontroller 4 is connected with the CONVSTA and CONVSTB pins of the sampling chip 3 to control and start the AD conversion. The BUSY pin of the sampling chip 3 is connected to the PC3 pin of the microcontroller 4 as an external interrupt signal source, which is used to prompt the end of the AD conversion. OS0~OS2 of the sampling chip 3 are over-sampling mode pins. By configuring these three pins, the sampling rate of the sampling chip can be changed to realize the adjustment of the sampling rate. The PA7 pin of the microcontroller 4 is connected to the RESET pin of the sampling chip 3 to reset the sampling chip 3 . In addition, the measurement range of the input voltage can also be changed by changing the level connected to the RANGE pin of the sampling chip 3 . For example: if the RANGE pin is connected to a high level, the measurement range is -10V~10V; otherwise, the measurement range is -5V~5V.

As shown in Figure 7, the communication module 5 uses ZTE's ME3000 V2. It is used for the communication between the monitoring device and the remote monitoring computer. The microcontroller operates the communication module 5 with the AT command set. By establishing a TCP/IP link through China Mobile's GPRS network, the monitoring device can receive control commands from a remote monitoring computer, including functions such as threshold voltage setting, voltage calling, time synchronization, and active uploading of voltage data. It can be seen from accompanying drawings 1, 6 and 7 that the data interaction between the microcontroller 4 and the communication module 5 is realized through asynchronous serial communication, and the USART1_RX and USART1_TX of the microcontroller are respectively connected with the TXD and RXD of the GPRS module ME3000_V2, In order to achieve data interaction. The 28 and 30 pins of the GPRS module respectively control the incoming call, incoming text message indicator LED3 and control the network signal indicator LED2. Since LED3 is on at a high level, and when a text message is received, there will be a low level of 4-5s, so LED3 is off for 4-5s. The PB3 output level signal of the microcontroller is amplified by the transistor 9014 to control the reset pin RESET of the GPRS module; the PB4 pin is connected to the ON/OFF pin of the GPRS module to control the opening and closing of the communication module 5; the PD7 pin As the gate g input of the Si4435 chip (P-MOSFET), it controls the power supply V_MAIN of the GPRS module to be turned on and off. In addition, the data flow usage of the communication module is subject to payment, which needs to be realized through the SIM card. Therefore, the GPRS module needs to realize information interaction with the SIM card. The V_CARD pin of the GPRS module is used as the power supply to connect to the VCC of the SIM card; the UIM_RST pin is connected to the RST pin of the SIM card to realize the reset function; the UIM_CLK pin is connected to the CLK of the SIM card as a clock line for data reading and writing; UIM_DAT is used as a two-way reading and writing The data cable is connected to the DAT of the SIM card.

The communication protocol between the communication module 5 and the remote monitoring computer adopts the IEC60870-5-104 protocol. The protocol sets that when either of the communication parties does not receive or send any data for more than 4s, a test frame is sent to test the communication link, and if no reply is received, the link is immediately disconnected and reconnected.

The method of judging the occurrence of overvoltage is as follows: every 0.02s of sampling, the voltage value obtained by sampling is compared with the set threshold. When 10 data are greater than the set value, it is determined that overvoltage has occurred, otherwise it is determined that the voltage state is normal. When an overvoltage occurs, the voltage data is sent to the remote monitoring computer immediately, and the content is the waveform of the first two cycles and the waveform of the last 10 cycles of the overvoltage.

As shown in Figure 2, the resonant overvoltage monitoring terminal B of the present invention and the remote monitoring computer A equipped with corresponding monitoring and management software form a resonant overvoltage monitoring system. In terms of function, the remote monitoring computer obtains the information of each monitoring device through the GPRS network, analyzes the information, and displays it on the graphical interface. The staff can set the voltage threshold of each monitoring terminal on the monitoring computer, call the monitoring device to upload voltage data, view historical voltage data, display data waveforms, and export voltage historical waveforms.

An example of the working process of using the resonant overvoltage monitoring terminal of the present invention is as follows.

The monitoring device samples the input voltage at a frequency of 10kHz through the voltage sampling chip, and sends it to the microcontroller through the SPI serial bus. The microcontroller judges the collected voltage data. If an overvoltage occurs, it calls the communication module. The voltage waveform data of 12 cycles is packaged and sent to the remote monitoring computer with the communication protocol. The remote computer parses the data, scales it, and stores it in its own database. And the alarm information is displayed on the graphical interface to remind the staff. If there is no overvoltage, judge whether the data sent by the remote monitoring computer is received, if so, analyze the data, and perform corresponding actions according to the content of the data, such as modifying the voltage threshold of the monitoring device, etc. If the monitoring computer calls data to it, the data concentrator will pack the collected data according to the protocol, and transmit it to the monitoring computer through the GPRS network. After the monitoring computer receives the data, it will perform data analysis and scale conversion and store it in its own database. If it does not receive any data sent by any remote monitoring computer, it will judge whether it exceeds the set time, and if it exceeds, it will send a test frame to test the link status. At this time, the remote monitoring computer responds with a test confirmation frame to confirm that the communication link is normal. The staff can view the historical voltage data on the monitoring computer, and at the same time, they can manually call the operation of the monitoring device remotely.

The above are the preferred embodiments of the utility model, and all changes made according to the technical solution of the utility model, when the functional effect produced does not exceed the scope of the technical solution of the utility model, all belong to the protection scope of the utility model.

Claims (6)

1. A resonant overvoltage monitoring device, characterized in that it includes a microcontroller, a communication module for communicating with a master station, a sampling chip for sampling voltage signals, a voltage conversion circuit, and is arranged on a 10kV or 35kV bus The front-end voltage transformer and the power supply circuit used to supply power for the whole device; the microcontroller is connected to the sampling chip through the SPI serial communication interface, and is connected to the front-end voltage transformer through the sampling chip and the voltage conversion circuit connected, the microcontroller is also connected to the communication module through the USART serial communication interface; the power supply circuit includes a filter module, a step-down module, a rectifier module and a voltage stabilizing module connected in sequence, and the input terminal of the filter module Connect to 220V AC power supply. 2. A resonant overvoltage monitoring device according to claim 1, characterized in that: said microcontroller adopts STM32F407VGT6 chip. 3. A resonant overvoltage monitoring device according to claim 1, characterized in that: said voltage conversion circuit includes a closed-loop Hall voltage sensor, and the closed-loop Hall voltage sensor adopts HCV-10E. 4. A resonant overvoltage monitoring device according to claim 1, characterized in that: said sampling chip adopts AD7606. 5. A kind of resonant overvoltage monitoring device according to claim 1, characterized in that: the communication module is a GPRS module, and the GPRS module adopts ME3000 V2. 6. A resonant overvoltage monitoring device according to claim 1, characterized in that: the voltage stabilizing module adopts two voltage stabilizing chips LM2596, which are used to convert the DC voltage output by the rectifying module to 5V and use For the 4.2V DC voltage output for GPRS power supply, among them, the 5V DC voltage is converted into 12V and 3.3V voltage by switching power supply and 3.3V regulator chip respectively.