Frequency control approach by controlling output power of renewable energy sources considering the priority of power adjustment

In recent years, Renewable Energy Sources (RESs) had developed very fast. However, the RESs cause frequency deviation sharply and decrease the reliability of the power system. It is difficult to suppress the fluctuation only by the thermal generator since the increasing of the RESs is serious. It is necessary to consider the output power of the RESs to adjust the power fluctuation. Then, the maximum power of the RESs has benefit for both economic and environment. Hence, this paper proposes a frequency control approach by controlling the output power of RESs, considering the priority of power adjustment. At the beginning, the power deviation would be compensated by the thermal generator, battery and demand response as usual. However, in case of the output power of the thermal generator decreased to the limit, the proposed control method would be executed. In the proposed way, the output power of the RESs was controlled based on the system frequency information. As a result, the frequency deviation was suppressed by improving the supply-demand balance.