Algorithm of Digital Phase-Sensitive Short-Circuit Protection Based on dq Coordinate Transformation

In coal mines, phase-sensitive short-circuit protection is one of most common methods to protect power supply line by distinguishing between short-circuit current and starting current, but it is difficult to avoid false operation by hardware technology to catch power factor angle on the influence of in-situ environment and device characteristics. In this paper, a new method is proposed to calculate power factor angle by dq coordinate transformation, which can successfully detect the zero-crossing of voltage and current, and avoid the false operation of phase-sensitive short-circuit protection.