Novel pilot protection based on time-domain model identification for wind power integration

To adapt to fault characteristics of week infeed, rich harmonics and frequency deviation of wind power system, a novel pilot protection principle based on model recognition in time-domain is proposed in this paper. Differential voltage and current of two line terminals conform to capacitance model at external fault state, but do not conform at internal fault state. A correlation coefficient is defined to describe capacitance model. When the correlation coefficient is close to 1, the fault is external, otherwise is internal. Thus protection criterion is formed. Since the criterion is achieved in time-domain, the novel pilot protection is not impacted by fault characteristics of week infeed, large harmonic and frequency deviation of wind power system. Since full electrical quantities are adopted, the proposed scheme is free from unstable impedance influence of wind power system. PSCAD simulation of wind power integration verifies effectiveness of the proposed principle.