Coordinated control strategy for improving inertial response and primary frequency modulation in wind power full DC system

Abstract

A coordinated control strategy for a variable-coefficient wind power full DC system to address problems such as reduced system inertia and insufficient frequency regulation abilities in the AC grid caused by the integration of wind power full DC systems is proposed. In terms of inertia response, the grid-side converter station adopts inertial synchronization control, while the DC-boost converter station adopts constant variable-ratio control to provide inertia support to the grid through DC capacitor and perceive the AC system frequency through the DC voltage on the low-voltage side. Additionally, a virtual inertia control scheme is introduced by adding a variable virtual inertia coefficient to the DC wind turbine (DCWT), enabling the wind power full DC system to have different equivalent inertia in different frequency response stages. As for frequency regulation, the DCWT operates in a load-reducing mode combining overspeed and variable-pitch control, adjusting its active power output through variable droop control. This approach fully utilizes the available capacity at different wind speeds, allowing the wind power full DC system to participate more effectively in frequency regulation. Simulation results demonstrate that this strategy improves the inertial response and primary frequency modulation of the power system after the integration of the wind-powered full DC system.

Keywords

• wind power full dc system
• dc capacitor
• dc wind turbine (dcwt)
• inertia response
• primary frequency modulation
• variable coefficient