NFLMS Algorithm for Solar PV-Battery Based Microgrid With Seamless Operation

This paper proposes a new control of a three phase solar PV-battery based microgrid. This microgrid has the capability of seamless transfer of power when the system mode of operation changes from grid connected mode to standalone mode and vice-versa. It provides an uninterruptible power to the load even in the absence of the grid and solar PV power. It also provides the power quality features at the point of common coupling (PCC) by mitigating the current harmonics drawn by the nonlinear load. The voltage source converter (VSC) works in a current controlled mode when the grid is present. However, in the absence of the grid, the VSC works in voltage controlled mode. In the current controlled mode, the normalized fractional least mean square (NFLMS) algorithm is used to estimate the load active fundamental component. An additional feed-forward term is used to improve the system dynamic in the inconsistent solar PV array output condition. In the voltage controlled mode, the synchronous rotating frame (SRF) based control algorithm is used to maintain the rated voltage across the load at rated frequency. An enhanced phase locked loop (EPLL) is used for the resynchronization process. The performance of the microgrid is validated by experimental results in various dynamics conditions.