Design Of Low-voltage Distribution Network Monitoring Terminal Based On GPRS

With our country entering a new era of industrialization, the demand for power consumption continues to increase, the scale of the Low-voltage distribution network is also expanding year by year and the problem of using electricity safely appears especially important. At present, the load of distribution line has different types and their electrical characteristics are complex, especially the nonlinear electrical equipment with high-power which can easily cause the wire to age and bring fire and other serious disasters. Voltage instability will seriously interfere with the normal operation of industrial equipment and the economic loss is incalculable. In such a situation, the power sector needs a reliable intelligent monitoring system to collect data used for the management of the Low-voltage distribution network. The GPRS wireless communication technology is applied to send monitoring data, which can avoid laying communication lines on a large scale and achieve real-time monitor of the network status, so as to provide green, stable power supply for corporations and residents.This paper gives a new method for the design of Low-voltage distribution network Terminal, which is based on GPRS technology. It is consisted of two parts: data acquisition module and wireless module. The first part is used to collect the power parameters of distribution network for display, storage and distribution. Wireless module connects with gathering module through the RS232 serial port and finally the data is sent to operation center via the GPRS network. Compared with the traditional wired monitoring method, the wireless method has more merits and better application prospect. At present, the related monitoring products have appeared, but there are still lots of problems crying out for solution. In the face of this, the manufacturers require us to make improvements and rise up the quality of the products. Considering this point, we decide to implement three key technologies through our comprehensive analysis, which are used for the management of the distribution network (how to collect the power parameters with high precision, how to reply SMS automatically, how to link the GPRS network without break). In order to solve these problems, we design the intelligent terminal with the following advantages. (1) Based on the actual measurements, we select CS5463 chip with high-precision to collect data. It can get all kinds of power parameters through calculation. Compared with the similar chips, the CS5463 chip can provide more parameters and compensate for the temperature drift. (2) When the GPRS module receives a new short message, it is not stored in the memory of SIM card but output from the serial port directly, so as to read the message without waiting and reply automatically. (3) Making use of the newest technology of heartbeat-packets to keep GPRS module on line all the time and avoid connecting to the network repeatedly.In the hardware design, we choose STC90C58AD chip as the main processor, which has 4kB SDRAM, can accomplish to process short message and link to the GPRS network. The monitoring terminal also includes auxiliary circuit used for display, memory, clock, calendar and key control. Regarding software design, we mainly achieve the message encoding and decoding, use the AT command to complete the access of GPRS network without break and write the driving program of the functional circuit.