For certain 35 kV shorter transmission line with neutral point not to earth directly

the imbalance of three-phase voltages of busbar is occurred due to serious asymmetry of three-phase capacitor parameters since capacitive voltage transformer is mounted in phase A. For this issue

the imbalance of 35 kV busbar voltage at 110 kV Tongxiang substation is taken as an example to find out the line causing imbalance of busbar voltage by way of switching operation. Then

various reasons causing imbalance of three-voltage is listed by brainstorming method. It is found that the reason of imbalance of 35 kV busbar voltage is due to asymmetry of three-phase capacitor parameters of capacitive voltage transformer in phase A in accordance with such series of abnormal signal as current and voltage etc. Finally

a PSCAD transient simulation model is set up and voltage variation of three-phase to ground of the system with arc suppression coil mounted at different steps

the change of operation mode and at different installation phase of voltage transformer are analyzed

and the result obtained can provide reference in solving the imbalance of threephase voltage of the system due to similar reasons.