Techniques of Tracing the Unreliability Contributions of HVDC Transmission System Components

Generally, HVDC transmission system has a quite complex structure with a large number of components. As is well known, each component has a different impact on the system reliability. The technique of determining the contribution of each component to the system unreliability can be used to identify the system weak parts and provide a useful tool for the decision-making on HVDC system operation and planning processes. This paper proposes an unreliability-tracing principle based on the proportional sharing principle (PSP), and an unreliability-tracing model for HVDC transmission systems. The PSP was used in this model twice based on the sub-system division scheme. In the unreliability-tracing process of the sub-system, the contribution of each component to a sub-system unreliability index can be calculated using the PSP. In the unreliability-tracing process of the whole system, the contribution of each sub-system to the system unreliability can also be calculated using the PSP. The contribution of each component to the system unreliability can be obtained by combining the two contribution results. The case study indicated that the proposed technique can distribute the HVDC transmission system reliability index to components or sub-systems impartially and reasonably, and it can also be used to identify the system weak parts.