In the UHVDC filter coupling loop

the suspended filter capacitor and the supported filter capacitor have great difference in seismic response characteristics under earthquakes

whose seismic performance needs to be further studied. Based on a suspended UHVDC filter coupling loop and a supported UHVDC filter coupling loop

the finite element models of two types of UHVDC filter coupling loop are established and analyzed using three-dimensional seismic time history analysis method to compare the seismic performance of two types of filter capacitors in terms of the response of displacement

internal force and acceleration. The result shows that the horizontal displacement of the suspended filter capacitor at the junction with the bus is larger than that of the supported one

and the peak acceleration appears at the bottom layers in the suspended filter capacitor and top layers in the suspended one. The internal force safety factor of the suspended filter capacitor satisfies the recommended value of the specification and has a large margin. It has a higher displacement response in the horizontal direction which exhibits the feature of a tensile cable. The phenomenon of elastic rebound at the bottom layer of the insulators of the suspended filter capacitor should be the main focus under earthquakes. The internal force safety factor of the supported filter capacitor exceeds the recommended value. Though it has a lower displacement response in the horizontal direction which exhibits the feature of a cantilever strut. The bottom pillar insulators require better material strength to bear the highest root stress and should also be the key position under earthquakes.