The Research Of Detecting Method Of Voltage Sag And The Control Strategy Of Dynamic Voltage Restorer

As the advances of technology and increased of automation. The electrical equipment which is sensitive to power quality are more and more. Therefore the power users put forward higher requirements to the quality of power supply. Dynamic Voltage Restorer (DVR) can effectively solve the problems of transient voltage quality such as voltage sag, swell, short time harmonic in power system. Therefore, the study of DVR have Great theoretical and practical significance.Based on the analysis of the main circuit and principle of DVR, and according to the characteristic of low-voltage network, this paper confirms the main circuit of DVR which is voltage compensation based on phase. At the same time also studied the voltage compensation strategy for several common of DVR.Because of the detect section of voltage sag have a great impact for the compensation of DVR. This paper detailed analysis the three phase and single phase Voltage detection methods based on dq alternate method. A new filter, use a high cut off frequency low pass filter in series with a band stop filter make up, is proposed to resolve the contradictory problem of response time and detection accuracy in traditional low pass filter in detect. the theoretical analysis and simulation verification show that it have better response speed and detection accuracy,it can meet the needs of DVR voltage detection.A new control method, a model-free adaptive control,is proposed to resolve the steady-state error, insensitivity to the disturbance of power system, adaptive load is bad which is existed in feedforward control method of traditional, it only use the the data of load voltage and input voltage to determine the controller parameters, no need to establish the mathematical model of the system, Only by adjusting the parameters of a line, to achieve interference suppression system, the purpose of load voltage stability.simulation results show that this method than the feedforward control method has a higher stability margin, has good anti-interference ability and load adaptability, and its response time is relatively fast, can be used in DVR control system.