Exploiting the Operational Flexibility of Wind Integrated Hybrid AC/DC Power Systems

Due to inherent uncertainty and volatility, large-scale wind power integration brings new challenges to the flexible operation of power systems. It calls for more flexibility not only from the generation side but also from the grid side, especially the hybrid HVAC/HVDC transmission grid. This paper proposes to exploit potential flexibility by controlling power flows through HVDC by the merits of its flexible regulation capability, as well as HVAC transmission switching (TS). To synergistically schedule them with generator units, a security-constrained economic dispatch (SCED) model for wind integrated hybrid AC/DC power system is presented to realize the co-optimization of generation and TS. Wherein, multiple uncertainties (wind power fluctuation and generator failure) are considered, and the linear power flow model of the DC grid is adopted. Then the model is transformed into a two-stage (normal state optimization and corrective dispatch verification) robust optimization (RO) model for iterative solution by the aid of the column-and-constraint generation (C&CG) algorithm. Case studies on the modified IEEE 14-bus and IEEE 118-bus systems show that TS can assist HVDC to optimize power flow distribution and provide more flexibility, meanwhile optimizing HVDC transmission power and TS can greatly reduce the operating cost of the whole system.