Probability‐based seismic reliability assessment method for substation systems

Abstract

Summary Power systems play a key role in emergency rescue after an earthquake. Substations are among the most important components of a power system, so it is necessary to study their seismic reliability after an earthquake. Most studies, however, have focused on the seismic behavior of major electrical equipment or the reliability of the substation under ordinary operational conditions. The seismic reliability of substations as a system has not been thoroughly studied. This study proposes a new probability‐based method to evaluate the seismic reliability of complex engineering systems such as substations. The proposed method developed the state tree to construct a greatly simplified system model that enables the failure probability to be calculated for the whole system, with explicit consideration of correlations among various components. A typical 220/110/10‐kV substation was studied with this method, and the most critical components were identified.

Seismic risk analysis of electrical substations based on the network analysis method

“…Therefore, the effectiveness of the proposed method will not be affected by the selected component fragility parameters. The seismic fragility curve parameters of considered equipment components are collected from the literature, 28,30,32 and listed in Table 2. The corresponding seismic fragility curves of each component are shown in Figure 7.…”

“…[12][13][14][15][16][17] Currently, different performance indicators and system modeling approaches have been proposed and applied to evaluate the seismic performance and reliability of a substation, including the success path method, 18 the cut-set method, 19 the binary-state test approach, 20 the enumeration and conditional probability approach, [21][22][23] the fault tree and event tree analysis, 24,25 the graph theory, 26 the integrated sequential flow analysis method 27 as well as the state tree method. 28 Nevertheless, the methods for evaluating the seismic performance of a substation proposed in the literature have the following shortcomings.…”

“…2. Existing functionality metrics for a substation, such as the percentage of damaged equipment, 25,30 the percentage of damaged output lines, 22,23,27,28 and whether the predefined load demand of the selected power customer is satisfied, 19,24 are too general since the substation-level redundancy and configuration variations are not accounted for. Furthermore, the relationship between the substation functionality and the percentage of damaged components needs to be further assumed from experience.…”

“…Redundancy and power flow of the substation is considered in a simplified way by determining the substation functionality as the maximum percentage among different types of physically survival electrical bays. 28 However, whether each physically survival bay is working in further consideration of electrical connectivity is unknown, because the normal operation of an electrical bay is not only related to its structural state but also related to the state of the equipment component in its pre-and postsequence. As the state tree method 28 is essentially a sequential flow analysis method, 27 it is difficult if not impossible to consider the effect of the state of the subsequently connected equipment while determining whether the concerned equipment or bay ultimately participates in the substation system's operation.…”

“…Framework of the modular quantitative assessment method for seismic risk of substations state combinations in oversimplified models, which do not consider all electrical equipment components, leading to less accurate substation functionality predictions. 18,19,25,30 Grouping equipment components into macrocomponents, which preserve the functional relations and failure probabilities of the group of components, and combining the Monte Carlo method can be an available alternative, 21,27,28,32 yet a trade-off should be made between computational efficiency and the number of equipment macrocomponents considered.…”