Adaptability Analysis of Asynchronous Interconnected LCC-HVDC with Additional Frequency Control Strategy

Two AC systems that are asynchronously interconnected will have the problem of lack of mutual support ability due to blocking the sharing of frequency modulation resources. In order to improve the frequency response characteristics of the asynchronous interconnected system, an additional frequency control strategy (AFC) with line commutated converter based HVDC (LCC-HVDC) participation is proposed. The strategy improves the transient characteristics of the system frequency response by adding frequency-var additional control. And the strategy also improves the voltage stability of the grid frequency regulation process by adding voltage-var additional control and adjusting the switching mode of the AC filter in LCC-HVDC. Finally, an equivalent model is built in PSCAD/EMTDC. The adaptability of LCC-HVDC to the proposed additional frequency control strategy is analyzed by a case study.