Adaptive Protection of Meshed and Radial Networks Considering Different System Topologies and States

The change in the topology and state of active distribution networks (ADNs) is one of the crucial challenges that might affect the protection schemes. The conventional protection schemes based on a static topology result in coordination constraint violations in other topologies due to the outage of upstream substations and distributed generation units. This paper proposes adaptive and combinational protection schemes considering all ADNs’ topologies and states. In the proposed combinational protection scheme one setting group is considered for all relays. The relay’s optimal settings are determined by solving one optimization problem, including all constraints corresponding to all topologies. Although the coordination constraint violations are reduced in the combinational protection scheme, the operating time of relays is increased due to the small feasible area of the optimization problem. Hence, proposing an adaptive protection scheme with different setting groups is beneficial. The number of coordination constraint violations is reduced in the proposed adaptive protection method, while the speed of the protection system is satisfying. The optimal selection of curves for the overcurrent relays is another contribution of this paper that has received less attention in the available research works. The proposed methods are tested on different test systems including 8-bus and 30-bus IEEE (meshed sub-transmission test systems), and IEEE 33-bus distribution test system (a radial ADN including charging stations for electric vehicles (EVs)). The obtained test results and comparison with other previously-reported strategies prove its accuracy, effectiveness, and authenticity.