Response Characteristics of the UHV Supporting Capacitor Subjected to Bidirectional Earthquakes

Supporting capacitors are the basic components of the filters in the UHV substation. However, this type of capacitor is vulnerable during the past earthquakes, for its dozens of tons mass, and relatively brittle insulators. In this study, modal properties and seismic responses of a typical UHV supporting capacitor were analyzed, based on a finite element model. Results indicate that seismic responses of the first translational mode of the capacitor in the two horizontal orthogonal directions are predominant, and the torsion effect can be ignored during the bidirectional earthquake. To further investigate the effect of the bidirectional earthquake, 7 ground motions with different field properties were adopted to calculate the unidirectional and bidirectional responses of the capacitor. Comparison between these two types of responses suggests the combined effect of the bidirectional earthquake can be fully considered by calculating the maximum unidirectional responses of the first translational mode based on a simplified response spectrum method, and multiplying the responses by an amplification factor. Taking both the calculation results and current seismic code in consideration, it is recommended that the amplification factors of the displacement responses and the stress responses related to the insulators are recommended as 1.15 and 1.20 respectively.