Multi-variable H-infinity Robust Control Applied to Primary Frequency Regulation in Microgrids with Large Integration of Photovoltaic Energy Source

In this paper, different control strategies are presented for primary frequency regulation in a diesel-photovoltaic-supercapacitor hybrid power generation system. Firstly, a classical control approach is proposed as a reference. Then, a robust control design based on H-infinity control theory is applied to the studied system. Starting from given certain desired performances, Linear Matrix Inequalities (LMI) are used to solve the H-infinity controller design problem. In the second step, several modeling uncertainties are included and mu-analysis is carried out to determine the maximum variation range of each uncertainty for which the system is still stable and desired performances are met. Numerical simulation results show the effectiveness of the H-infinity robust control strategy when compared with the classical control strategy used for this type of hybrid power generation system.