Balanced And Unbalanced Grid Photovoltaic Microgrid Control Strategy Research

Nowadays, with serious environmental pollution and energy shortages exacerbated distributed photovoltaic technology because of its ease of installation, flexible operation and so on, more and more widely used. This paper studies two aspects:control and unbalanced state of the PV inverter at grid voltage balance.First introduced the background of photovoltaic power generation, generation at home and abroad as well as the status of PV inverter in the case of balanced and unbalanced grid voltage control research status policy. According to a mathematical model of the PV array simulation model to analyze the output characteristics of the light array, introduces several common method of controlling the maximum power (MPPT), we propose a AFSA Based MPPT control method. Then a mathematical model PV inverter grid voltage equilibrium introduced selection filter method, introduced PQ grid when the PV inverter control strategy, when net from sagging (Droop) control strategy, a mathematical model of each strategy. Finally, the simulation in MATLAB/Simulink simulation platform, verify their control strategy superiority.Introduces the grid voltage unbalance, voltage unbalance of the definition, the mathematical model of PV inverters in the grid voltage unbalance. Analysis of the lock-in technique in the PV inverter, using DSOGI-PLL control technology as herein lock method, the lock-in technique simulation. Introduction PV inverter grid voltage unbalance when the instantaneous power theory, this theory can be seen through the PV inverter power production caused by fluctuations of the PV array DC voltage fluctuations when the grid voltage unbalance. When not balanced against the impact caused by the PV inverter grid voltage unbalance, in the stationary coordinate system, the control method rotating coordinate system and the natural coordinate system, analyzes their advantages and disadvantages, and finally adopt a relatively easy control voltage and current double closed-loop feed-forward before decoupling control strategy, an analysis of how to extract the positive and negative sequence components of voltage and current, the last in MATLAB/Simulink simulation platform simulation photovoltaic inverter control strategy in the grid voltage imbalance.