Optimal Generation Scheduling Approach Applied to the Transmission Grid of Uganda for Enhanced Performance and Cost Reduction

Abstract

Generation scheduling involves determination of startup and shutdown times and power outputs of all generating units at each time step, over a specified period. The scheduling of electricity production from power producers in Uganda is carried out by considering only the type of generation plants available to ensure demand-supply balance and that the power system remains stable. There is need to develop a generation scheduling procedure that not only maintains the power system in equilibrium but also maximizes utilization of available plants, minimizes both electricity production and transmission costs while reducing bulk network constraints. This paper presents an alternative generation scheduling protocol, applied to the 132kV bulk network of Uganda. The protocol starts with a short-term load forecast to establish the demand. Optimum hourly power plant outputs were determined by solving a four-plant optimal power flow problem whose objective function is an aggregation of generator cost functions subjected to active grid constraints in MatLab-PSAT. Assessment of scheduling results revealed significant reduction in cost of generating and transmitting bulk power attributed to improved plant utilization. The bulk network performance was enhanced as exhibited by improved node voltage regulation, reduction in bulk network loss and improved transmission capacity usage as per load flow analysis results obtained using DIgSILENT Power Factory software 15.1.