Modeling the Effects of PWMSC and Fault Resistance on Ground Fault System in MV Distribution Line

摘要

A newly developed AC link converter based series compensation is a recent series Flexible Alternating Current Transmission System (FACTS) controller. The Pulse Width Modulated based Series Compensator (PWMSC) exploits the concept of the variable series reactance compensation which can modulate the impedance of a distribution line through applying a variation to the duty cycle (D) of a train of pulses with fixed frequency. This paper proposes a new approach for the calculation of short-circuit parameters in the presence of PWMSC. Using PWMSC results in an improvement of the system performance as it provides virtual compensation of distribution line impedance by injecting controllable apparent reactance in series with the distribution line. This work studies the impact of fault resistance (R_F) on the fault current calculations in case of a ground fault and a fixed fault location. The case study is for a medium voltage (MV) Algerian distribution line which is compensated by PWMSC in the 30 kV Algerian distribution power network. The analysis is based on symmetrical components method which involves the calculations of symmetrical components of currents and voltages, without and with PWMSC in both cases of maximum and minimum duty cycle value for capacitive and inductive modes. The paper presents theoretical analysis for the case study followed by simulation results which both reflect the improvement of system performance when PWMSC is deployed.