Voltage control strategies for solid oxide fuel cell energy system connected to complex power grids using dynamic state estimation and STATCOM

In this paper, a novel Dynamic State Estimation-current feedback with STATCOM control scheme is proposed for the mitigation of voltage fluctuation of Solid Oxide Fuel Cell (SOFC) power station connected to the complex power grids during electrical faults. The proposed control scheme is compared to two existing control strategies and shows its superiority in alleviating voltage flickers and deviations as well as protecting the internal membranes of the fuel cells. Since SOFC internal dynamic states are able to closely reflect the transience and dynamic behavior of SOFC, using them in controller designs can generate better regulations of the state-related internal voltage of SOFC than other methods. STATCOM is also utilized in this study to mitigate the voltage oscillations induced by unavoidable voltage fluctuations during electrical faults. The power system with proposed control strategy is proven to be stable through linear analysis. The acquisition of the useful internal dynamic states is realized using unscented Kalman filter algorithm based state estimator. The success of incorporating estimated states into the development of control strategies is conducive to the designs and implementations of new control schemes for power systems and also the applications of interdisciplinary control theories.