Optimal Overcurrent Protection for Industrial Medium Voltage Network.

Document Type : Research Studies

Authors

1 North Delta Electricity Distribution Company, El Mansoura, Egypt

2 Department of Electrical Power & Machines Engineering, Faculty of Engineering, Tanta University, Tanta, Egypt

Abstract

Abnormal condition and faults in power systems can cause power supply interruption and sometimes equipment damage. Hence, there is an increasing need for an effective protection scheme. In order to obtain a secure and reliable protection system, an effective coordination has to be satisfied between backup and primary protection devices. The main objective of this paper is to select the optimal settings of overcurrent relays that achieve the minimum operating time for relays when subjected to abnormal conditions or faults. The coordination process between overcurrent relays inside the network is accomplished considering detecting the fault and tripping the nearest circuit breaker to disconnect the affected area without affecting other areas. This paper investigates the protection requirement of switchgears in a practical power plant and design a coordination set for all circuit breakers and overcurrent relays in the low and medium voltage areas. In addition, both linear programming and genetic-algorithm methodologies are used to optimize the values of time dial setting for different operating scenarios of power plants so as to achieve the minimum operating times of overcurrent relays.

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