Modelling and optimization of a FACTS devices operated multi-objective optimal reactive power dispatch (ORPD) problem minimizing both operational cost and fuel emissions

Abstract

The study of modern power systems is complex and multi-dimensional with diverse constraints that are generally considered one at a time for seeking the optimal results for a specific set of goals. However, for a more realistic approach to problem solving, multiple goals are tackled simultaneously, optimizing a multi-objective problem. In this study, a multi-objective (MO) Flexible AC transmission system (FACTS) device incorporated in an optimal reactive power dispatch (ORPD) problem that has been developed considering these distinct objectives concurrently to formulate a ‘MO-ORPD-ELD-Emission-FACTS’ problem—the hourly cost of energy lost in transmission (from ORPD), generation cost (from economic load dispatch), the operational cost of FACTS devices such as static VAR compensator (SVC) and thyristor-controlled series capacitor (TCSC), and emissions of fossil fuel pollutants. The implementation technique is the Arithmetic Optimization Algorithm (AOA), and it is being tested on the standard IEEE 30, IEEE 57, and IEEE 118 bus systems. The fuzzy-based mechanism of Pareto optimality has been employed to determine the Best Compromising Solution (BCS) out of the set of Pareto solutions of the multi-objective problem. A specific case of load uncertainty has also been carried out for the larger IEEE 118 bus system with ten different variations of load demands for the same multi-objective function. The aim was to study the significance of the achieved results under the different loading conditions and compare the voltage profiles. The solutions obtained by AOA were observed to be the best and followed an ideal nature of Pareto optimality compared to the others. The incorporation of FACTS has significantly reduced the cost of economic load dispatch (ELD), the cost of energy loss, and fuel emissions, and with a much healthier voltage profile for all three test bus systems. The power loss has been reduced from 3.1129 MW to 2.8469 MW for the IEEE 30 bus system, from 11.366 MW to 10.0656 MW for the IEEE 57 bus system, and from 73.2977 MW to 64.2368 MW for the IEEE 118 bus system as obtained by the AOA. The IEEE 118 bus system showed the optimal overall operational cost and emission at 77.4 % loading, with a better voltage profile with the incorporation of FACTS devices.