Novel HVDC Transmission Line Protection Scheme Based on Current Differential

In the study of DC power lines protection performance; the shunt capacitance impact is not Significant as the frequency is zero in steady state condition. However, during system transients, faults, DC voltage fluctuation occurs and charging current flows onto the protected line from both terminals impacting the protection system, consequently, the influences of the charging and discharging current reasoned by the shunt capacitance must be considered. This paper suggests a new differential current protection scheme relying on compensating for capacitive current distributed along the length of the line solving the delay time problems for the currently used dc line current differential protection system. A monopolar 12-pulse HVDC test system is modeled using MATLAB, and different fault conditions are carried out to verify the success of the proposed algorithm. The simulation results demonstrate that the designed protection scheme accurately distinguishes between external and internal faults and well function with different fault location and impedance.