Constant Power Generation Method For Grid-Connected Photovoltaic Systems With Fast Response Under Dynamic Irradiance Condition

In this paper, an improved constant power generation (CPG) method is proposed for grid-connected photovoltaic (PV) systems with the fast response under dynamic irradiance condition. Because the penetration level of PV system is rapidly increasing in the power grid, the grid codes have been revised to limit feed-in power, which requires CPG methods. However, conventional CPG methods have the limitation in slow converging speed due to a number of iterations. Therefore, they have large power overshoot and undershoot resulting in the overloading of grid. To figure it out, the proposed CPG method directly estimates the constant power point to converge without voltage steps and decision-making processes. Then, the fast response under dynamic irradiance condition can be achieved with the minimized tracking error. The operating principle of proposed CPG method is firstly explained in detail. Thereafter, its performance is analyzed and compared with that of conventional CPG methods by simulation test.