Impact of STATCOM on the voltage stability of HVDC terminating at location having low SCR

This paper investigates the voltage support of the advanced static var compensator (STATCOM) connected to a high voltage direct current (HVDC) inverter terminating at AC locations having low short circuit ratio (SCR). In this paper, mathematical models of STATCOM in its different operating conditions are proposed, combination with which, the influence of STATCOM on the HVDC operating characteristics are analyzed in detailed by maximum power curve and voltage stability index methods. Coordinated control strategies between HVDC and STATOM are put forward, which involves the processes of HVDC power scheduling, long duration after ac faults processes. STATCOM can restrict the voltage fluctuation range and enlarge the stable operation range. The electromagnetic simulation results indicate that a STATCOM with the enough capacity to reduce the temporary over voltage (TOV) level can effectively support HVDC to operate in a larger range, and run more stability.