Multi-terminal UHVDC Transmission System Security Assessment and Coordinated Optimal Operational Strategy

As the renewable energy sources have been envisaged as a major source of energy generation for future, ultra-high-voltage DC (UHVDC) transmission system is playing an increasingly important role in transmitting huge amount of renewable power to the load center. The uncertainty of wind energy together with the risk of UHVDC faults posts great challenges in the secure operation of interconnected inter-regional power systems. In view of these challenges, the security assessment of UHVDC system considering uncertain wind output is proposed in this paper. First, we perform short-term wind output prediction based on Gaussian Process Regression (GPR). Second, we useMonte Carlo simulation to obtainwind power loss expectations, and then obtain different N - 1 contingency scenarios. Third, we proposed an optimal operational strategy in the presence of the above contingences, by coordinatingAGCandAVCof each region of the inter-connected power system to eliminate over-limits of frequency, voltage, current and transmission capacity. Case studies with modified IEEE 14-bus system and a synthetic Chinese power grid show that the coordinated optimal operational strategy is able to ensure the frequency security, voltage stability, and the secure operation of the interconnected power system.