Research Of The Control Of Dynamic Voltage Restorer Of Distribution Network

In recent years, with the continuous development of science and technology, the dependence of the society on electrical energy is stronger, meanwhile, the requirements to the power quality are increasingly high. However, as distribution network connected with the client, whose power quality is directly related to the normal operation of the sensitive load or not. Especially electrical loads controlled by computer and microprocessor are largely put into use in distribution system, the interferences of these loads to the distribution network are more sensitive than traditional electromechanical equipment. Therefore, the requirement to the distribution network is also higher.The paper based the mechanism of dynamic voltage restorer of distribution network, established its dynamic mathematical model, and studied its compensation methods. Aiming at the temporal requirements of the dynamic voltage restorer in distribution network, we improved the voltage signal detection algorithm, on base of the analysis of traditionally based on instantaneous reactive power theory of instantaneous voltage dq detection algorithm, Aiming at the its shortcomings, and proposed an improved version of the dq detection algorithm. The simulation results verified that the improved algorithm can well satisfy the demand of the dynamic voltage restorer of distribution network. Aiming at low damping and insufficient margin of the traditional voltage, current single closed-loop control system, also this system was not sensitive to disturbances such as harmonic and meanwhile load adaptability was so poor weak, we designed a kind of double closed loop control strategy, namely voltage is outer loop controlled variable, current is used as inner control, designed the block diagram of the whole system. Finally, we obtained the inner relationship among the system output, input and disturbance, by properly selecting parameters of each link, the system can not only compensating voltage drop, but also can effectively compensate the original edge and voltage waveform distortion caused nonlinear load voltage, which improved the stability margin of the system, the dynamic response speed, etc. Finally, the computer simulation results verified that the detection algorithm and the control strategy were effective.