Total Transfer Capability Assessment of Multi-Infeed HVDC Links Considering Frequency Stability Requirements

Total transfer capability (TTC) is an important security index for the daily scheduling and operation of multi-infeed HVDC links. With the massive infeed of HVDC links, a huge power shortage will occur in the receiving grid following the worst case HVDC bi-pole blocking. In this case, the frequency of the receiving grid will drop sharply, and even causes excessive amounts of load shedding. To mitigate this operating risk, a novel method for TTC assessment of multi-infeed HVDC links is proposed in this paper. Firstly, an optimization-based TTC evaluation model is built by explicitly considering frequency stability requirements of the multiHVDC infeed system, in which synergistic under-frequency arrest strategies are taken into account to deal with the worstcase HVDC bi-pole blocking. Then, an analytical target cascading (ATC) based algorithm is developed to solve this problem. Case study on the modified RTS-79 system demonstrates the effectiveness of the proposed method.