Design And Research Of Power Quality On-line Monitoring System

Electricity application degree is a main symbol of the level of a nation’s development. Generally, with the power system in the running voltage, frequency and the degree of the deviation of nominal value, as the important indicators of measuring the power quality. Nowadays, the level of domestic research on the power quality management has fallen behind developed countries, the problem on the power quality has reached the point where it cannot be ignored, to make the management of power quality more effective, people have to get the firsthand material of the power quality. So the research and development on the power quality online monitoring system has a broad application prospect.Treated the power quality as the research object, this paper studied six indicators of the steady-state power quality related measurement method, focused on the method of window between harmonic which based on FFT, inter-harmonics analysis, took advantage of the Lab VIEW software platform to achieve the power quality online monitoring system.Based on the analysis of the different window FFT methods and solving power harmonic and inter-harmonics accuracy defects in practice, by the Lab VIEW simulation graph and data, the influence of the window FFT method of frequency spectrum leakage was less than the direct FFT method, by taking the use of different window FFT methods, the paper got different results on the accuracy analysis. The seven order Blackman window-Harris had the best effect on improving the accuracy of the signal analysis.This paper presented a overall design scheme of the power quality monitoring system. The system contained three parts, data acquisition module, power quality analysis module and data storage module. The system measured the effective value of current voltage, frequency, three-phase imbalance degree of harmonics, voltage flicker, voltage harmonic, the real-time measurement and power, and it also given the corresponding program block diagram. The system can collect real-time data record to the hard disk for subsequent data analysis, and friendly interface, can expand sex strong, rich, low cost, etc. Paper expounds the development work of the power quality online monitoring system which based on the virtual instrument technology, the use of producer-consumer structure, multithreaded programming technology, modular system design ideas. The paper also completed the measurement analysis, simulation, data management, and other modulars’design. Made the system can record the real-time analysis of signals, ensure the integrity of the data and the efficiency of the data analysis. What’s more, because of the help of the modular design concept, the system’s expansion is easy to come true.This paper adopted LabVIEW with harmonic analysis module and ordered7Blackman window-Harris FFT transform method of combining the harmonics of inter-harmonics analysis, each module of the system was tested, and through the simulation signal in voltage flicker and wave interference, to verify the system’s anti-jamming capability. By the study of the simulation measurement of power quality indicators, and the error analysis, the simulation results meet the national grade A standard measurement instrument. According to the experimental data analysis, the power quality online monitoring system is effective and feasible.