Simulation Study Of Static Var Generator In Photovoltaic System

Due to the rapid development of the global industrial economy, energy crisis and environmental pollution problems are becoming more and more serious on the earth. As one of the new energy solar energy,because of its unique advantage to become the ideal alternative energy has become one of the hot research in new energy development.With the continuous development of photovoltaic system,grid connected photovoltaic gradually universal and connected to the power system caused by the adverse effects has become increasingly obvious. Reactive power compensation is an important measure to improve the power quality of grid connected photovoltaic system to improve the stability of the system.The reactive power compensation device in the photovoltaic system is required when the fault occurs.The photovoltaic grid connected operation remains,but does not absorb the power input to the system reactive power to help restore the system from the grid.The excellent performance of the static var generator,it has become the main development direction of reactive power compensation devices in recent years.The characteristics of photovoltaic cells are analyzed with the three-phase photovoltaic grid connected generation system. The maximum power point tracking control and grid connected inverter control technology are introduced in detail. The simulation model is built in MATLAB. The model of each sub module is built which is the basis for analyzing the compensation effect of the static var generator in the normal operation and fault of the photovoltaic system. On the other hand,the static var generator(SVG) is the whole. The working principle is analyzed,the methods of reactive current detection and control strategy are analyzed in detail.By comparing the direct current and indirect current control and the control system is designed. The two phase rotating dq coordinate mathematical model is adopted. On the basis of this,the feed forward decoupling of the voltage and current is carried out in order to control the active and reactive power. Therefore,the structure of double loop negative feedback control based on voltage.The current is adopted to achieve the goal of stabilizing and controlling the voltage of the network with the DC side voltage. Because of three-phase short-circuit fault occurs,the traditional PI control of its corresponding parameters can not be changed.The corresponding effective regulation. The fuzzy control theory is introduced to improve the PI regulation which to improve the control effect of SVG reactive power compensation in three-phase short circuit.The final control method has the advantages of both fuzzy control and PI control,which can make or absorb reactive power in real time according to the change of load under different conditions.Finally,a whole simulation model of power grid with photovoltaic power generation system is built in MATLAB.Then the effects of reactive power compensation on different kinds of load are compared and analyzed. By comparing the simulation results with the simulation results,it is proved that the static var generator has a good dynamic compensation performance,which can effectively improve the power factor of the photovoltaic system and the voltage stability of the system node.