The Study Of Power Quality Realtime Monitor System Based On DSP

With the social progress and development, power quality problem is put forward; the issue of power quality has become a major subject of the power system. Both power supplier and electricity user have the responsibilities to guarantee quality of supply and to ensure safe and stable operation of power network. Therefore it is necessary to do long-term power quality monitoring on the coupling point of public as well as the main power unit, and furthermore to devide the responsibilities between the two sides. Research on power quality measurement methods and development of measuring instruments are of great theoretical significance and practical engineering value.This paper firstly studies the domestic and international development status of power quality monitoring devices,introduces a classification and definitions to the problems of power quality in detail,and then studies the measurement methods of the power quality indicators, focuses on the harmonic measurement methods based on FFT of synchronous sampling method. This paper provides theoretical basises and algorithms for power quality monitoring system research.Besides useful signal ,the power quality signal still contains a lot of noise. Only effective filtering noise signal, the accurate useful information to the power quality analysis can be obtained ,the conclusion of power quality analysis is reliable.The paper put forward wavelet neural network to filter the noise of power quality signal. This method can be used to adaptively selecting wavelet denoising decomposition layers and the wavelet denoising threshold. The simulation results show that this method can effectively remove power quality signal noise, and can better reserve power quality signal's information.On this basis, the paper designs and implements a real-time power quality monitoring system. The system is a virtual instrument based on advanced digital signal processor, ARM technology and GPRS network technology. It can achieve a long-term online operation,a real-time measurement and analysis,preservation and query of historical data. Compared with traditional instruments,this system gains advantages such as a friendly human-computer interface, a simple operation, a strong processing capability and a convenient expansion.Finally,the paper verified the measurement accuracy of the power quality monitoring system by experiment. Combining with the condition of laboratory , experiments of measurement was performed using this system.The experimental results show that the system has accurate measurement and stable operation which means the system has a good value in use.