133 / 2022-03-14 02:54:41

Field-circuit coupled simulation of core grounding current of a VSC transformer

transformer,Electric field,circuit

Purpose/Aim

The structure and operating conditions of VSC transformer are different from those of power transformer and converter transformer. Compute the grounding current of the core and clamp accurately is helpful to evaluate the operation status of transformer.

Experimental/Modeling methods

A method for computing the earthing current of a transformer is proposed. Firstly, a geometric model is established to characterize each metal structure in the transformer. Secondly, a finite element model of electrostatic field is established and the partial capacitance matrix is calculated. The circuit simulation model of the transformer can be obtained from the partial capacitance matrix, by which the grounding current can be computed.

Results/discussion

The VSC transformer core ground shield is grounded through the clamp, so the clamp grounding current is greater than the core. The computed grounding currents of the core and clamp are 18 and 274mA respectively, which are basically close to the measured results of 18 and 258mA.

Conclusions

The grounding current of transformer core and clamp is mainly capacitive current. With a larger size of core and higher the voltage of inner winding, grounding current is greater.