Voltage Preventive Control Strategy Based on the Optimization of Wind Farms Power Factor

Given that wind farms are required to contribute to ancillary services, this paper proposes a preventive control strategy to improve the static voltage stability margin (VSM) of the power system by controlling the power factor from a previously selected set of wind farms. The selected group of wind farms is determined by calculating a PF sensitivity index that indicates the wind farms that most positively affect the VSM. The optimal PF regulation of this group of wind farms is then obtained by applying an optimal power flow (OPF) to maximize the distance from the current operating point to the maximum loading point (MLP). The dispatch of active and reactive powers of conventional fossil fuel and hydroelectric power plants is also considered control variables in the proposed optimization problem. The method is validated using a real test system, based on Northeast subsystem of the Brazilian interconnected power system with a high share of wind power considering different scenarios. The results show the applicability of the proposed voltage preventive control strategy, indicating the sets of effective actions in terms of PF regulation of wind farms, as well as the optimal dispatch of active and reactive powers of conventional power plants that must be taken to improve the static VSM of the system.