Development of Model for Load Frequency Control in Power System with Large-scale Integration of Renewable Energy

Due to large-scale renewable energy installation, frequency regulation is becoming more important and more difficult in power system. Battery energy storage system (BESS) is the one solution to this problem. It is assumed that effectiveness of installing BESS into power systems depends on its generation mix and control systems of frequency regulation. However, the optimal size of BESS has been discussed without consideration of supply demand control in the power system, especially under the large-scale renewable energy installation. If variable generations, such as photovoltaic power (PV) generation and wind turbine (WT) generation are largely integrated into the grid, load frequency control (LFC) is required to compensate not only short-term fluctuation but long-term fluctuation which is conventionally dealt with by economic dispatching control (EDC) because of the uncertainty of the uncertainty of the PV and WT output. Therefore, the way of LFC and EDC should be revised under such circumstances, and then, the value of BESS should be analyzed in consideration of this change of control system. First of all, the new coordination method of EDC and LFC is proposed to deal with the large-scale installation of PV and WT generation. Next, the effectiveness of the proposed method in terms of frequency regulation is verified by numerical simulation. Moreover, the optimal size of BESS is analyzed based on the proposed EDC and LFC systems. Numerical simulation shows the effectiveness of the proposed EDC and LFC system and the cost benefits of the use of BESS for LFC.