A Novel Pilot Protection for HVDC Transmission Lines Based on Model Error Function

In order to solve the problems in existing protection for high voltage direct current (HVDC) transmission lines, such as insufficient sensitivity for main protection and slow operation for backup protection, a novel pilot protection for HVDC transmission lines based on model error function is proposed in this paper. In the principle, through analyzing the fault component networks, external fault is equivalent to a capacitance model, while the internal fault is equivalent to a inductance model. Taking capacitance model as a benchmark, the model error function was defined to describe the degree of consistency between actual fault data and the benchmark. When an external fault occurs, fault data agree with the capacitance model and model error equals zero. When an internal fault occurs, fault data do not agree with the capacitance model and model error does not equal zero. According to this, a protection criterion is constructed. Theoretical analysis and simulation show that the new principle, not affected by transition resistance and line distributed capacitance current, can identify internal faults and external faults reliably and rapidly.