K. Kuppusamy

Optimal short-term hydrothermal scheduling using decomposition approach and linear programming method

Abstract The operational planning problem of hydrothermal scheduling for the next days demand in a power system is concerned with the determination of generation schedules for hydro and thermal 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 and hydro plants as well as the network security constraints. This paper presents an effective algorithm which decomposes the problem into hydro and thermal subproblems and solves them alternatively. While the hydro subproblem is solved using a search procedure, the local variation method, the thermal subproblem is solved using the participation factors/Linear Programming method. The algorithm is very effective in enforcing security constraints and gives an optimal generation schedule which can be readily implemented for the next day. Results obtained from a 9-bus system and a 66-bus utility system demonstrate the effectiveness of the proposed algorithm.

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 days 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.

A FAST ALGORITHM FOR OPTIMAL HYDROTHERMAL SCHEDULING WITH CASCADED AND INDEPENDENT HYDRO PLANTS

ABSTRACT This paper presents a fast algorithm for solving the short-term hydrothermal scheduling problem in a power system consisting of cascaded plants with time delay and independent hydro plants. The operational planning of such problem is concerned with the determination of scheduling for hydro as well as thermal plants to meet the daily system demand with the objective of minimizing the total fuel cost of the thermal plants over the day subject to the relevant operating constraints associated with the thermal and hydro plants. The algorithm employs a fast and simple alternating solution approach for hydrothermal scheduling in which the hydro subproblem is solved using the method of local variation while the associated thermal subproblem is solved through a judicious combination of Successive Linear Programming (SLP) method and Participation Factor method. Many computational features are incorporated in the solution algorithm exploiting the inherent characteristic of the complex hydrothermal schedulin...

A simple and effective local variation algorithm for long-range hydrothermal scheduling

Abstract A simple and effective sequential method is presented for the long-range (one-year) hydrothermal scheduling problem. The dynamic optimization problem is decomposed into a sequence of static optimization problems by discretizing time span into a number of equal intervals. Methods based on the discrete maximum principle, dynamic programming and non-linear programming are available for solving this problem. In this paper, at each time interval, the hydro subproblem is solved using the method of local variation, while the associated thermal subproblem is formulated as a non-linear programming problem and solved by the lambda iteration method and/or through the use of participation factors of the thermal units. The results obtained by solving two different systems reveal the effectiveness of the method for practical application.