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摘要
A current differential protection has a good selectivity and sensitivity. However, the access of the inverter-interfaced distributed generators (IIDGs) and the branch loads has changed the fault characteristics of distribution networks, which increases the risks of the false or failure operations for the existing current differential protection of distribution networks. Based on the fault equivalence model of the PQ-IIDGs and the branch loads, this paper investigates the magnitude characteristics of the positive-sequence currents and their phase characteristics of the fault components, taking the relative positions of the fault points, the T-connected IIDGs and the branch loads as the datum point. An adaptive double-proportional-restraint-coefficients-based differential protection using the positive-sequence current amplitude and the fault-component phase is proposed. The reliability and sensitivity of the proposed protection criterion are analyzed using the amplitude and the phase planes. The effectiveness of the proposed method is validated by the PSCAD/EMTDC simulation. Results show that the scheme has a good adaptivity to different fault types, locations and fault resistances without being affected by the access of the IIDGs and the branch loads. ? 2024 Power System Technology Press.
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