Synchronous Generator Emulation Control Strategy for Voltage Source Converter (VSC) Stations

The voltage source converter (VSC) station is playing a more important role in modern power systems, but the dynamic behavior of the VSC station is quite different from that of the synchronous generator. This paper presents the synchronous generator emulation control (SGEC) strategy for the VSC-HVDC station. The SGEC strategy is divided into the inner control loop and the outer control loop. The inner controller is developed for fast current and voltage regulations. An inertia element is introduced into the frequency-power droop to determine the command reference of the frequency, and the inertia response and the primary frequency regulation are emulated. In addition, the secondary frequency regulation can be achieved by modulating the scheduled power in the SGEC strategy. The time-domain simulation results demonstrate the VSC station with the proposed control strategy can provide desired frequency support to a low-inertia grid. Therefore, the SGEC strategy provides a simple and practical solution for the VSC station to emulate the behavior of a synchronous generator.