Analysis of distance protection for transmission lines connected with electrochemical energy storage stations

Electrochemical energy storage stations (EES) have been rapidly applied in power systems. Their fault characteristics are influenced by inverter control strategies, which differ significantly from traditional synchronous power sources. Especially, EES can operate in two modes of charging and discharging, which makes their fault characteristics different from new energy sources such as wind and solar. A detailed study on the adaptability of phase-comparated distance protection (PCDP) in the transmission lines of EES are provided in the paper. Firstly, based on the technical specifications for connecting EES to the grid after faults, the fault characteristics of EES under different charging/discharging conditions were analyzed. Then, the influence of EES on the use of memory voltage based phase to phase distance protection components was explained in principle. A detailed analysis was conducted on the various factors affecting the performance of the EES side relay. Finally, the simulation model based on PSCAD verified the correctness of the analysis results. The results show that the theoretical analysis in this article is highly consistent with the simulation results. When the EES are in a charging state and a short circuit occurs in the outlet line, factors such as impedance setting, control strategy, and transition resistance will all affect the operating characteristics of the PCDP on EES side.