Research on a Fault Location Method for a Pole-to-Pole Short-Circuit Fault in an LCC-MMC Hybrid DC Transmission System

Abstract

When a pole-to-pole short-circuit fault occurs in an LCC-MMC hybrid DC transmission system, the fault characteristics are affected by the distributed capacitance and the transition resistance that cause a dead zone in the fault location and poor accuracy in determining the fault location. In view of this, this paper proposes a fault location method for the LCC-MMC hybrid DC transmission system. By analyzing the fault characteristics of the rectifier station and inverter station, the fault circuit equation of the rectifier side is analyzed, and the relationship between the fault distance and the transition resistance is deduced. The fault circuit of the inverter side is isolated by blocking CDSM-MMC, which can clear the fault current on the inverter side and thus eliminate the influence of the transition resistance. The steady-state fault information of the LCC DC outlet is used to eliminate the effect of distributed capacitance and achieve an accurate fault location. The LCC-MMC hybrid DC transmission system model is built on the PSCAD / EMTDC simulation platform. Simulation results show that the proposed fault location method can effectively avoid the transition resistance and distributed capacitance influences and thus obtain high fault location accuracy. Moreover, an accurate fault location can be achieved with a narrow fault data window length.

Keywords

• Hybrid DC transmission system
• fault location
• fault characteristics
• blocking