An adaptive protection coordination strategy utilizing user-defined characteristics of DOCRs in a microgrid

Abstract

• The present study discusses about the user-defined characteristics of DOCRs as a proposed method. • Here near end and far end fault points have been considered for observing the effectiveness of the proposed approach over conventional approach. • Different contingencies like generation increase or decrease have been considered and the proposed coordination strategy has been observed for its effectiveness. • Hybrid GA-NLP algorithm has been utilized for implementing the relay coordination task and a comparative study with GA and NLP algorithms for proposed and conventional approach has been discussed. • Three test systems namely IEEE 6 bus, modified 14 bus and IEEE 30 bus has been utilized for validation of the proposed study. The value of plug setting (PS) as well as time multiplier setting (TMS) of Directional Overcurrent Relay (DOCR) is used to achieve the relay coordination conventionally. With the emergence of Numerical DOCR, four settings of the relay, namely, PS, TMS, A and B are utilized for the relay coordination. This numerical DOCR make the coordination strategy adaptive for any contingencies. In this paper, four setting coordination strategy is proposed for Grid connected and for different contingencies in the network topology considering near end and far end fault locations. This coordination problem is formulated and solved using Hybrid GA-NLP approach. The proposed strategy is validated on the meshed distribution system. It also investigates the impact of DG penetration. The proposed method is also compared with the conventional strategy. The relay coordination problem has been tested on the meshed distribution system of IEEE 6-bus, modified 14-bus and IEEE 30-bus test systems which are penetrated with synchronous based DGs. The computed results show that the user-defined approach of selecting inverse time relay characteristic has significant potential in minimizing the overall operating time of the Numerical based DOCR. Hence, making it an effective and reliable option for meshed distribution system with DG.