Effective Inertial Response With New Coordinated Control for Multiple WPPs

This paper proposes a new coordinated control for multiple wind power plants (WPPs) based on two stepwise inertial control (SIC) methods to effectively release the kinetic energy of the permanent magnet synchronous generators (PMSGs) and improve their inertial response. When a large disturbance occurs, the conventional SIC method increases the output power from the PMSG instantly to arrest the frequency nadir (FN). However, in low wind speed conditions, it may not be able to provide a sufficient inertial response. Therefore, the proposed coordinated control applies the new SIC method to some WPPs by decreasing the output power from their PMSGs for a short period before increasing it. This results in initially accelerating the rotor speed of the PMSGs and reserving their releasable kinetic energy. This means that they are ready to extract more powers without causing the over-deceleration (OD) problem. Also, the proper selection of two SIC methods for multiple WPPs is able to prevent the rate of change of frequency (RoCoF) from increasing. The effectiveness of the proposed coordinated control is verified with several case studies on the IEEE benchmark 39-bus test system. The results show that it effectively improves the frequency stability of the power system without raising the RoCoF in various conditions. Moreover, this enhancement becomes more apparent when the penetration level of wind power is high.