Abstract:

With the increasing capacity of grid-connected PV systems, ancillary service such as voltage regulation at point of common coupling (PCC) is available from PV systems by controlling the amount of reactive power injected to the grid. This paper proposes an adaptive voltage control method of distribution systems with high-level PV penetration. The modelfree extremum seeking (ES) control algorithm is used to autotune the PI feedback gains of the voltage controller to respond dynamically to system changes. The PI gains of the voltage controller are updated online through the minimization of a cost function, which represents the voltage controller performance. The proposed ES-based adaptive voltage controller is tested in a distribution system model with a 5-MW PV system built in Matlab/Simulink. Simulation results show that compared with traditional PI controller, the proposed voltage controller can easily adapt to load changes and grid faults, thus improving the power system reliability and voltage stability.