Research Of Power Quality Comprehensive Assessment And Prediction Of Harmonic Current

Electric Power as the backbone of modern civilization is the most widely used in modern society energy, and its application extent is one of the main signs that marked development level of a country. So the quality of electric power and the stability of power system affect the development of national economy. More and more electronic equipments are used in the power system. They are making many power quality problems when they improve productivity. These problems not only harm the electric equipments, but also threaten stability of power system. Therefore, it has important theoretical and practical significance to research on improving power quality, it can ensure the safe operation and of power supply system and the user’s electrical safety.This paper is based on power quality, around the power quality monitoring, comprehensive assessment and prediction of harmonic currents conduct the following work.A power quality detecting system based on LabVIEW is designed in this paper in order to have a thorough grasp of power quality, and thus provide the basis for improving power quality. Use three-phase power supply, with the fundamental signal, harmonic signal, and even white noise signal to simulate, simulation results show that this system can achieve the indicators of power quality monitoring, and it is a powerful tool for improving power quality.In order to evaluate power quality objectively and comprehensively, this paper is to the data of power quality analysis and monitoring system for study, a new power quality assessment method based on the improved extension of AHP has been proposed, and use actual data for checking, correlation analysis show that this method can distinguish the level of power quality, and can evaluate power quality qualitatively and quantitatively.Power system is a complicated nonlinear system, and current control of active power filter itself is a nonlinear control process. Therefore, three-phase bridge rectifier load is modeled as a harmonic source in this paper. Firstly, detect the harmonic currents, isolate the harmonic component of load current quickly and accurately, and analyze harmonic spectrum. Based on neural network can realize any nonlinear mapping, this paper design a RBF neural network predictive controller for active power filter to compensate the nonlinear load, in order to control the compensation current reference current tracking without time delay. Adopting branch and bound optimal algorithm to produce control value. Correlation simulation results prove that RBF neural network algorithm largely eliminated supply current and voltage harmonics, and could obtain good filtering effect. It has a good control effect of harmonic pollution.