Collaborative Optimisation of Frequency Regulation Capability and Power Schedule for HVDC Interconnected Asynchronous Systems

The high voltage DC links are required to provide frequency regulation support to alleviate frequency concerns of multi-area asynchronous power systems. However, the inter-area DC frequency support capabilities lack coordination with the intra-area frequency regulation resources of sub-grids under the existing scheduling mode, which may lead to frequency safety issues after power disturbance. To address this issue, this paper proposes a collaborative scheduling optimisation model, where the DC droop factors are set as scheduling variables and periodically allocated in coordination with the frequency regulation capabilities and power scheduling plan of each sub-area. Several types of power disturbances, including the intra-area disturbances as well as the inter-area DC blocking disturbances, are considered. The RoCoF and frequency deviation of all sub-networks under these disturbance scenarios are constrained in the proposed model. Case studies show that the frequency safety can be guaranteed and the asynchronous power system would benefit from the improved operational flexibility.