Critical Operation Characteristics of Offshore Wind Farm Integrated to Weak Receiving Systems by VSC-HVDC

Voltage source converter HVDC (VSC-HVDC) is a commonly used grid integration scheme for the offshore wind farm, and can be used to connect weak receiving systems. It is necessary to study the operation characteristics after integration. Therefore, the simulation models are established for the offshore wind farm integrated to weak receiving systems by VSC-HVDC. Based on the steady-state and stability security constrains, the paper considers the reactive power control scheme of the doubly fed wind induction generator (DFIG) and the influence of receiving systems impedance angle, and take the short circuit ratio (SCR) as the evaluation indicator of the receiving systems. And the critical short circuit ratio (CSCR) is obtained based on the different wind farm output. Then the the static stability with wind speed fluctuations as the disturbance and transient stability are simulated on the platform of DIgSILENT/PowerFactory. The results show that the SCR should be more than 1.6 when DFIG as the generator is integrated to weak receiving systems. At last, some compensation measures are given to reduce the CSCR, which can provide the guidance to actual projects.