OPTIMAL CO-ORDINATION SYSTEM FOR OVER CURRENT, &EARTH FAULT PROTECTION RELAYS IN SEBETA-I SUBSTATION BY USING WHALE OPTIMIZATION ALGORITHM

Abstract

Protection and coordination of substation system networks is one of the most substantial issues in power systems. Over-current, earth fault relays, and differential protection are the systems’ most commonly used protective relays. The coordination of inverse time over-current relays is formulated as a linear programming problem. The optimization technique aims to minimize the relays’ time dial settings (TDS). The settings for this type of relay can be categorized into two current and time settings. The most significant variable in the optimal coordination of over current relays is the time multiplier setting (TMS). Protective relays are essential devices for electrical power protection systems. The choice of protection devices depends on the type and rating of the protected equipment. The primary function of the relay is to clear fault current flowing through the system at faults that have occurred in the protective line. This thesis focuses on optimal over-current, earth fault, and differential protection coordination schemes for the Sebeta-1 substations. The voltage level of this substation is 132KV, and it has eight low-voltage outgoing lines, two incoming feeders, two incoming power transformers, and two 132KV incoming lines. This substation system network is one of the oldest and most important substation system networks in Ethiopia’s electric power Addis Ababa region, and also the maximum load of the city is connected from this substation. However, their coordination is not properly coordinated, and networks based on this improper coordination, interruption of power is frequently a phenomenon in the network. The main reasons are the system is saturated, the network system is old, there is a short circuit current, an earth fault, overloading, and also improper coordination and protection of the distribution network. When faults occur in one line, they create a high over-current. Due to the higher load, more of the network lines are out of service due to faults in some parts of the network. Clearly, in this case, the number of interrupted customers rises, and accordingly, the power quality decays. From analyzing the obtained results, it has been found that the whale optimization technique provides the most globally optimum solutions at a faster convergence speed. This algorithm finds the best solutions out of all optimization solutions. Using MATLAB programming gets the best optimization results