On the Design of Grid-Side Inverter Voltage Controllers

Grid-side inverter voltage controllers are commonly designed based on the dynamics of the output filter. While the dynamics of the coupling inductance is sometimes also taken into account, the grid dynamics are almost always neglected. However, as the neglected interplay of the controllers through the grid can be crucial, a stable overall power system can not be guaranteed. To address this problem, we derive a sufficient condition for the stability of the overall system which can be considered during the common decentralized design procedure. We propose a new, simpler control structure for voltage control, which has more degrees of freedom than the conventional control structures. Based on an exemplary microgrid, we demonstrate how the control parameters can be designed decentrally using our stability condition. Simulations finally show that the decentrally designed controllers indeed yield a stable and robust overall system. Our results can also be applied in order to ascertain the stability of energy networks consisting of coupled microgrids.