Optimum dispatch of turbines in a low head hydropower plant for a given total flow rate and available variable head - A case study for moragahakanda power station in Sri Lanka

Abstract

Hydropower is an extremely valuable resource. There are two types of reservoir based hydropower stations with different main goals. Some are following the demand of the utility and others follow irrigation water requirements. Therefore, always power generation is not at full capacity, and most of the time turbines are at partial loads as well. By optimal hydropower generation and scheduling, great profits can be achieved for the company and also for the country. Therefore, the economical dispatch of hydropower generation provides great opportunities for electric utilities. Moragahakanda hydropower station generates electrical power as an outcome of the irrigation water requirement, decided by the Water Management Secretariat (WMS) which is headed by the Mahaweli Authority of Sri Lanka (MASL). This research presents a strategy for the optimum distribution of dispatched power among its available generating units. The objective is the maximization of the total power generation for a low-head hydropower plant under varying head and for a given total water discharge rate. Hydropower generation scheduling is a nonlinear programming problem. The nonlinearity is due to the generating characteristic of the hydro turbines, whose outputs are generally a nonlinear function of water discharge and net hydraulic head. This research work presents a method that takes into account both the nonlinear characteristic and the head loss effect. This development is done based on the Moragahakanda hydropower station and, MATLAB software has been used for building mathematical models and solving the optimization problem.