Research On Key Technology Of Photovoltaic Grid-connected Inverter With APF

Energy and environment are two major problems which the world are facing nowadays. As its unique advantages, photovoltaic grid-connected power generation by using solar energy have become the focus in the world. However, nonlinear and impact load are emerging constantly in the power grid, influencing the quality of electric energy seriously, active power filter(APF) happens to solve this problem effectively. In order to integrated the function of photovoltaic grid connected and shunt active power filtering much better, implementation photovoltaic grid power generation and effectively improve the quality of power grid at the same time, To solve the problem of low utilization rate of the photovoltaic grid inverter in weak light conditions, so research on photovoltaic grid inverter is deep real meaning.This article is intended for Photovoltaic grid inverter in the process of grid-connected power generation equipment utilization rate is low and the harmonic and reactive power problems, introduced the structure and working principle of photovoltaic grid power generation system and active power filter, find out the similarity on the two devices in the structure, function and control methods. The system scheme that implement Photovoltaic power generation and active filtering in the same set is introduced. Then go into more detail on two key links of current detection and current tracking control during the implementation process of active power filter in the photovoltaic grid inverter.In the synthesis of current detection, this paper improve on the ip-iq method of instantaneous reactive power theory. Through the simulation analysis, the ip-iq method is more accurate when the voltage waveform distortion. And introduced ipv in active current detection, to improved stability of the DC voltage. For the synthesis of instruction current may exceed current inverter switch set the allowed maximum or inverter rated current value, using the method based on capacity constraints to control synthetic current.To implement the system security and stability operation.The current tracking control is one of the key technologies in this paper research, In order to achieve better control of the current track, by combining the each advantages of hysteresis and voltage space vector technology, the double hysteresis SVPWM current control strategy is used to output optimal voltage vector quickly to control the on-off switch tube so that the current error is limited within wide range. The technology achieves decreases the switching frequency, at the same time, improve the rapid response of the system of compensation current and the system efficiency.Finally, Simulation study is carried out on the platform of MATLAB/SIMULINK and validates the proposed strategy, which will show that the system structure and key control strategy is feasible and effective.