To ensure stability, security, and protection of electrical equipment from the damage the suitable coordination must be made in interconnected networks. In this paper, the nonlinear multivariable optimization techniques have been used with different performance indexes: Sequential quadratic programming (SQP), Sequential quadratic programming legacy (SQP-Legacy), Interior-Point and Active-Set for IEEE- 8 bus test system.  This system consists of twenty-eight protective relays divided into fourteen directional overcurrent relays (DOCR) and fourteen distance relays (DR). It has been tested in the ETAP environment to obtain three-phase short circuit current at the near and far end faults and operating time for all DOC relays for near-end fault as well as test the second zone time for distance relays (TZ2) with pilot signal (WP)and without pilot signal (WOP) of the proposed algorithm was used to reduce overall operating time of DOC relays and obtain optimal values for time multiplier setting (TMS) and TZ2 with the different coordination time interval (CTI) between main and backup relays. The simulation results were validated in ETAP program prove that the effectiveness of the Active-Set to minimize the TMS and TZ2 for the system.<em> </em>

Transmission and distribution lines are the most parts in power systems affected by faults during their operation. Therefore, it is required to maintain suitable coordination between all the protection relays is used to protect them during faults. In this paper, a genetic algorithm (GA) is utilized to solve the coordination problems of the directional overcurrent relays (DOC) in interconnected systems. GA is used to obtain the optimum time multiplier setting (TMS) of these relays. A comparison has been made with previous work in literature to show the efficiency and accuracy of the proposed algorithm and the total operatination time of DOC in the network has been minimized. The results confirm the superior performance of the proposed algorithm and these results have been validated by using an electric transient and analysis program(ETAP).

This paper aims to design and building a New Multifunction Relay (MFR) by using the Arduino MEGA. It is used to provide protection against many abnormal conditions that may occur in the power system. The MFR contains two functions: firstly, are designing an inverse Overcurrent relay, and the other is an Over/Under voltage Relay based on the IEC 60255-151 standard and IEEE 1159 standard respectively. The GUI is designed by using the MATLAB environment to provide a platform of the relay. The proposed MFR showed accuracy results, Low costs, fast response, and very small error rate.

Protection relays play an important role in the power systems to maintain stability, reliability, selectivity, and security for the power systems. In this paper, genetic algorithm (GA) optimization technique with pilot protection (PP) and without pilot protection (WPP) has been used to obtain proper coordination and the optimum value of transmission lines protection relays between distance relays (DRs) and directional overcurrent relays (DOCRs), as well as the critical case for fails in high voltage circuit breaker (HVCB) during faults, so using breaker failure relays (BFRs) for IEEE-8 bus system. The main aim of the used PP to reduce the overall time of DOCRs. A comparison is made with previous work in literature to show the efficiency and accuracy of the proposed algorithm with PP and the total operation time of DOCRs in the network is minimized.