Determine the reliable generating capacity of power systems with high HVDC penetration considering both stability and ancillary service requirements

Abstract: In China, the increasing amount of electricity imported from high voltage direct current (HVDC) transmission systems in some provinces has led to the retirement of local units. Lack of local generating capacity is adverse to the stability of system frequency and the adequacy of ancillary services. This study proposes a practical method to determine the minimum requirement of generating capacity (which is called the reliable generating capacity, RGC) in the sink side of a power grid. The relation between the minimum system frequency and the generating capacity is theoretically analysed. Based on simulation results, a function that determines RGC under a certain frequency drop constraint can be specified by data fitting. Meanwhile, the requirement of ancillary services (such as peak regulation, automatic generation control, and reserves) on typical days also imposes a floor constraint on the generating capacity. So the relation between generating capacities and ancillary services is also explored. Finally, the overall RGC value is the maximum of the above two aspects. A case study in East China Power Grid proves the effectiveness of the proposed method. The result can be used as a reference for power system planning and operation.