Time domain distance protection of new energy transmission line grounding fault considering the phase difference of zero sequence current on both sides of the fault point

The fault current in new energy power supply presents weak feedback, strong controllability and a large number of interharmonics. This leads to decline in the reliability of existing power frequency distance protection. Time-domain distance protection mainly establishes the fault distance based on the equation, and is less affected by the short-circuit current characteristics of new energy. This paper proposes an improved time domain distance protection scheme for new energy transmission lines that takes into account the phase difference of zero sequence current on both sides of the fault point. This is to address the issue of significant deviation in the calculation of fault distance caused by the influence of distributed capacitance on the phase of zero sequence current when the new energy transmission line is long. First, taking into account the influence of the phase difference of the zero sequence current on both sides of the fault point, the transition resistance is equivalent to the transition impedance. Then, by writing the fault circuit equation and finding the fault distance, a protection criterion is formed. Finally, based on a large number of simulation experiments using PSCAD/EMTDC, it is verified that the time-domain distance protection scheme proposed in this paper has only a small error in calculating the fault distance, and can be well applied to scenarios where new energy is transmitted through medium to long distance AC lines. © 2023 Power System Protection and Control Press. All rights reserved.