Effects of DC Voltage control strategy on voltage response on multi-terminal HVDC following loss of a converter station

Multi-terminal High Voltage Direct Current (MTDC) based on Voltage Source Converter is the most appropriate technology for Supergrid. The traditional reliability and availability related to outages as to transient reliability related to performance during and recovery after temporary faults and disturbances requires be evaluated. This paper shows the effects of DC Voltage control strategy on the dynamic behavior of bus voltages at multi-terminal HVDC following a lost of a converter station. Two different dc voltage control method are simulated in this paper: voltage margin method and voltage-droop method. Time-domain simulations on simple test system using DigSILENT
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PowerFactory™ are used to evaluate the response of AC/DC bus voltage considering sudden converter-station disconnection. Results demonstrate when two converters on the MTDC operate with DC voltage droop characteristic; it appears a “collaborative scheme” for the DC voltage support, sharing the task of controlling the DC voltage. The main contribution of this paper is to demonstrate the voltage margin control is capable to survive a converter outage just if this converter is operating on constant power mode.