A single-phase ground distance protection scheme based on compensated cosine volume

The existence of large transition resistance in high-voltage transmission lines easily causes the distance protection to refuse to act or to act incorrectly, which brings great challenges to the safe and stable operation of the power system. To eliminate the effect of transition resistance on distance protection, a single-phase ground distance protection scheme based on the compensated cosine volume is proposed. Firstly, the expression of cosine angle compensation is given by analyzing fault point voltage and voltage cosine volume at protection. Second, the voltage cosine volume ratio when a fault occurs to the boundary value of the voltage cosine volume during normal operation is calculated. The angle between the voltage cosine volume and fault voltage is used to construct the compensation initiation factor. Then, the compensation quantity is solved by multiplying the ratio, the compensation initiation factor, and the line impedance angle. Finally, the compensation quantity is substituted into the cosine angle compensation expression to compensate for the cosine volume and construct a novel distance protection criterion. Matlab/Simulink is used to verify the proposed scheme is not affected by transition resistance, fault location, and operating conditions, and can accurately identify single-phase ground faults with high tolerance to transition resistance.