Short-term hydrothermal scheduling of power systems with a pumped hydro plant using the local variation approach

Abstract

In light-load seasons, the operational planning problem of hydrothermal scheduling with a pumped hydro plant for the next day's demand in a power system is concerned with the determination of generation schedules for the hydro, thermal and pumped hydro plants to meet the daily system demand so that the total fuel cost of the thermal plants over the day is minimized subject to the operating constraints associated with the thermal, hydro and pumped hydro plants as well as the security constraints. The security constraints include network security constraints and the generator outage induced security constraint. This paper presents a new problem formulation by including the generator outage induced security constraint on water storage level to operate the pumped hydro plant as a spinning reserve unit and a method for the selection of the initial trajectory for the pumped hydro plant. The effective algorithm used comprises a judicious combination of the participation factor method and the linear programming method. The algorithm is very effective in enforcing security constraints and gives an optimal generation/pumping schedule which can be readily implemented for the next day. A comparison of results obtained with and without the outage induced security constraint is made on a nine-bus system.