The correctness of the cable sequence impedance parameters is directly related to the relay protection setting calculation. The sequence impedance parameter of the cable is affected by its laying method

and the positive zero sequence parameter is closely related to the grounding method of the sheath

protector

and return cable. Based on the classic Carson loop equation (Carson)

this paper proposes a method for calculating the positive zero sequence parameters of multi-circuit cables suitable for different grounding methods. The full-dimensional impedance matrix and sequence impedance calculation of the cable

combined with the electromagnetic transient software PSCAD/EMTDC modeling and simulation

verified the correctness and accuracy of the algorithm. Finally

the influencing factors of the cable sequence impedance parameters were studied. The results show that the positive sequence reactance is significantly reduced when the sheath is grounded at both ends. Different grounding methods result in significant differences in the zero sequence parameters. When the sheath is grounded at one end

the zero sequence parameters are significant. As the value increases

laying the return cable can appropriately reduce the zero-sequence parameter; when the cables are arranged in pin-shape

the distance between the return cable laying and the core is negatively correlated with the positive sequence resistance and positively correlated with the zero-sequence impedance; the change in soil resistivity does not affect the positive sequence parameters of the cable but only affects the zero sequence parameters under the single-end grounding of the sheath and the grounding of the return cable plus protector; when the two cables are connected in parallel

the zero-sequence parameters increase significantly under the single-end grounding of the sheath

and the zero-sequence parameters are basically unchanged under the double-end grounding of the sheath and the cross-connection grounding method. The degree of increase in the zero-sequence impedance under the return cable plus protector grounding method is related to the laying position of the return cable.