Hardware Research And Implementation Of Power Quality On-line Monitoring Terminal

With the rapid development of national economy, the huge amounts of nonlinear and impact load have been used widely in the power system, which result in power pollution becomes more serious and have a major impact on the safe and stable operation of power system. The problem of power quality gets prominent and has draw common attention of electric power department and customers. It can provide the scientific bases for improving power quality, proposing control measures and making sure technical parameters of control equipments by on-line monitoring power quality. Therefore, it has important significance. This paper take power quality on-line monitoring terminal as object of study and the detail is shown as below.(1) The overall design scheme of power quality on-line monitoring terminal is proposed in this paper, which according to power quality national standard and considering cost and performance. This paper constructs the dual CPU hardware platform system based on DSP and ARM, while utilizing the high-speed digital signal processing ability of DSP and the perfect management capacity of MCU. The two processor task partition is clear and mutual cooperation, carries on the high-speed and reliable data communication through dual port RAM. And DSP mainly completes the field data gathering, and rapid calculation of power quality parameters. But MCU mainly completes such functions as real-time clock management, data storage, man-machine interaction and communication with the host computer.(2) During the course of hardware research and implementation of monitoring terminal, completed signal acquisition, DSP data processing, MCU control and management, expansion memory, human-computer interaction, communication interface and power supply modules circuit diagram and PCB design. The high-accuracy acquisition is achieved by 16-bit A/D, and the phase-locked loop synchronization control technology is used for tracking sampling frequency and inhibition spectrum leakage. DSP data processing using FFT algorithm based on the complex sequence, greatly reducing the amount of calculation and saving memory space. In data storage, the use of ferroelectric memory chip realizes power failure protection and its data can be reliable stored at least 10 years. Design of infrared, RS485 and GPRS communication interfaces, and proposed GPRS networking program.(3) In the terminal software design, has given the overall program design and data collection, data processing flow chart, has studied the TCP/IP protocol and method, and has given the GPRS module networking programming and the network correspondence flow.(4) The monitoring terminal has adopted a series of effective hardware and software anti-jamming measures, including the anti-surge design, anti-static design, PCB layout and watch-dog monitoring, which guaranteed it could stabilize and reliable work in the electromagnetic interference quite serious monitor scene.(5) According to the general design requirements for the terminal, carried out the sub-module and overall union debugging. Making use of FLUKE6130A power electrical energy quality standard source to detect the precision of fundamental wave and measuring error of harmonic voltage. The precision achieves A level standard of the pubic power network harmonic, and a major source of error is analyzed.This monitoring terminal has been put into practical operation in a power substation, which has the advantages of stable and reliable, high measurement accuracy and good real-time performance. It achieves the desired design goal and can satisfy the actual requirements of power quality on-line monitoring.