Research on Integrated Parameter Measurement and Control System of Low Voltage Distribution Network

2. The Overall Design Of The System

According to the design requirements, in order to avoid interference of the strong signal on the weak signal, in the overall structure, it used three-layer circuit board. The overall structure of the system is shown in Figure 1.

Figure 1.

System summary composition

In order to meet the needs of a variety of performance, it used the following functional modules, Mainly, through the MCU to control and coordination, so as to achieve the function of each module, circuit diagram of the main circuit board shown in Figure 2. This design mainly includes the following modules:

Figure 2.

Schematic diagram of the main control circuit

• 1.

  AC signal conversion module: It converts the 220V AC voltage and 5A current of the distribution network into a small voltage and small current, and then transfers them to the special energy metering chip ATT7026. Alongside that, it also includes the design of the power supply part.

• 2.

  AC signal acquisition and processing module: it collects the AC signal and processing, and the measured parameters will be sent to the MCU through the SPI port. Then the calibration parameters passed by the MCU will be received through the SPI port.

• 3.

  System control module: the system control module sends the received parameters to the LCD display, and alarms in a timely manner if failure occurs in the monitoring process of the distribution network operation. On top of that, it sends the monitoring of information to the dispatch center through the RS485 communication. Additionally, this module will also complete the capacitor group switching through the reactive power compensation.