Pilot protection scheme for distribution network considering low voltage ride-through of inverter-interfaced distributed generators

摘要

According to the latest grid-connected standard, the failure of IIDG (inverter-interfaced distributed generator), represented by wind power and photovoltaic power, is characterized by strong nonlinear output. Therefore, the protection scheme based on the traditional fault characteristics is difficult to be applied to the distribution network with high permeability IIDG access. Based on the low voltage traversing operation characteristics of PQ control strategy IIDG, the work analyzed the distribution characteristics of positive sequence fault components in distribution network, and proposed a pilot protection scheme for distribution networks based on the comparison of current amplitudes on both sides of line. This scheme not only reduced the strict requirement of pilot protection for synchronous sampling of communication facilities, but also eliminated the influence of load current. Moreover, it had good practicability and economy without the protection and cooperation with other components. At the same time, in order to avoid the misoperation of amplitude ratio protection criterion for non-fault line due to the existence of unmeasured load branches, the distribution characteristics of node branch current abrupt changes were used to establish the auxiliary criterion for node-branch current mutation. It solved the action dead zone of the ratio protection criterion. Finally, the feasibility of the proposed protection principle was verified by DIgSILENT simulation. (c) 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.