Coordinated Power Smoothing Method of Wind Turbine Considering ESS Degradation Cost

Abstract

Wind power (WP) has intermittency and fluctuating nature. It could result in significant impact on power system stability especially when the grid is small and WP penetration level is high. To mitigate this negative impact, energy storage system (ESS) can be considered as a solution. However, the cost of the ESS is still high and it could result in different degradation level according to different use of the ESS.In this paper, a coordinated control method of the wind turbine (WT) and the ESS reducing the total cost of generation is proposed. To optimize the cost of the generation, the power generation profit and ESS degradation cost are considered as a total cost. In the proposed method, the WT determines operating point considering the ESS degradation cost. For this purpose, the empirical model of ESS degradation cost is used for accounting operational cost of the ESS from charging and discharging behaviors. Moreover, the WT de-loaded operating point is decided by comparing the total cost including ESS operation cost and power loss cost resulting from de-loaded operation. After achieving desired de-loaded operation in case of severe WP fluctuation, the moving average method is used for mitigating WP fluctuation during de-loaded operation. The WT emulates the inertial response from this method reducing the power fluctuation. The overall performance of the proposed method was validated in MATLAB/Simulink by reducing the total cost of the operation, especially when there is high WP fluctuation.