Research of adaptive inverse control applied to microsources based on P-f droop characteristic

Aiming at the distributed generations (DGs) which have strong controllability or are equipped with energy storage devices when a microgrid is in islanded operation state, an adaptive inverse control strategy applied to active power conditioning based on P-f (active power versus frequency) droop characteristic is developed. Containing adaptive LMS (Least Mean Square) filter and P-f droop control module, and regarding the rated frequency as input and the active outputs of microsources as disturbances, this method adjusts P-f slope coefficient online for the frequency of microgrid to track the rated frequency. Given the situation that imbalance active power exists, this strategy can quickly contribute to the best P-f slope coefficient along the negative gradient direction according to the theory of steepest descent method, thus guaranteeing the frequency of microgrid maintain at the rated value and completing the distribution of imbalance active power between different microsources. Finally, with this control strategy applied to a two-DG system, simulation results from MATLAB/SIMULINK verify the strategy´s validity and feasibility.