Frequency Compensation Control Strategy of Energy Storage in the Wind-energy storage Hybrid System for Improving Frequency Response Performance

With the increasing penetration of renewable energies into power system, the lower inertia problem has been the shackle to the system operation. For improving the system transient stability, enabling wind turbine generators (WGs) to provide temporarily frequency support has been required by grid operators. However, due to the mechanical characteristic, the frequency response performance of WG is not satisfactory. Considering the fast response characteristic of the energy storage (ES), Using ES to help in improving the frequency support of WGs is a new prospective application. Limited to the energy storage capacity, existing frequency supporting control strategies that using the ES to improve wind turbine frequency response cannot fully compensate in whole frequency response process. Enlarging the capacity of ES may significantly increase the investment cost of Wind-ES hybrid system. To overcome these problems, this paper investigates the possibility and financial benefits of large-scale ES configuration in the Wind-ES hybrid system. The analysis results demonstrates that using the ES into electric market as frequency response resource could make large-scale ES configuration possible. Based on potential large-scale ES configuration scenarios, a frequency compensation control strategy for ES of Wind-ES hybrid system is proposed in this paper to compensate whole frequency response process of WGs. The case study shows that the proposed strategies could significantly improve the frequency response performance of WG.