Sensitivity-based optimal reliability design of AC/UHVDC systems

摘要

In this study, a sensitivity-based optimal reliability design (ORD) model of the AC/UHVDC (ultra-high-voltage DC) system is proposed. The model can be used to adjust the reliability parameters of the replaceable AC equipments and UHVDC components to satisfy the pre-specified system reliability while minimising the total cost. The corresponding sensitivities provide references to identify the non-coherency equipments and to adjust the reliability parameters while avoiding the repeated calculation of the system reliability. To realise the proposed ORD model, the optimal power flow model considering the unbalanced operation mode of the UHVDC is proposed, and the incremental transition rate of the UHVDC is derived, thus to quantify the system reliability indices. Combined with the sensitivity model of the UHVDC itself, the state probability is used to connect the reliability indices at the system level and the UHVDC components' parameters, obtaining a direct solution of the corresponding sensitivities. The numerical results based on the modified IEEE reliability test system (RTS) test system are provided to validate the feasibility and accuracy of the proposed models.