Research On Power Quality Problem Of Grid-Connected Photovoltaic Generation System

With the rapidly development of the global photovoltaic technology, and traditional fossil energy decreasing, more and more photovoltaic power will be connected to the existing grid. Different to traditional generation technology, it is affected by the outside environment, the intermittent and uncertainty of photovoltaic power output, and combined to the grid by the power electronic device, and other reasons brings new features of power quality to grid. So study the power quality of gird-connected photovoltaic generation system will play an import role.Through studying the structure, operating characteristics and control strategy of grid-connected photovoltaic generation system, this paper analyzed the power quality problems and the influence factors, and attention is paid to the grid-connected photovoltaic generation system about common-mode current and voltage sag. This paper adopts the space vector pulse width modulation (SVPWM) algorithm study the common-mode current, through analyzing the system parameters, we put forward the control scheme of optimal parameters based on SVPWM algorithm. But for the voltage sag, we build the simulation platform on voltage sag based on the engineering model of photovoltaic array, and analyze the problem of voltage sag in grid-connected photovoltaic generation system by Monte Carlo method. As the result of the research, this model is more close to reality, and the result of the study can provide a certain reference value for grid-connected photovoltaic power generation system.Finally, when photovoltaic power connected to grid, we will consider more factors, and power quality as one of the key factor, so this paper has proposed the permeability of photovoltaic power based on power quality, and gives the calculation process of permeability by a simulation example. As the result of the research, this method can be taken as a reference for network planning.