Short Term Hydro-Thermal Scheduling Using Backtracking Search Algorithm

1. Introduction

Hydrothermal scheduling (HTS) is one of the important optimization problem, and it is solved using different optimization techniques. Recently different optimization techniques have been implemented in an advanced power system area to solve different problems. The objective of the hydrothermal scheduling problem is a task of allocation of power among different committed generating units for the fulfillment of demand power of scheduled period with minimum generation cost and fulfillment of generating constraints of different generating units. HTS problem consists of complex and nonlinear characteristics with various types of constraints. Hydro and thermal power are considered to the fulfillment of demand power of scheduled period for the problem, HTS. The thermal power plant has low installation cost but high running cost. The hydropower plant has high installation cost but low running cost. The integrated operation of the hydro and thermal plants in the same grid has become more economical. The main goal of the hydrothermal scheduling problem is to determine the water releases from each reservoir of the hydro system at each stage so that the operating cost is minimized along the scheduling period. Literature survey shows that over the past years, HTS problem was solved using various types of optimization technique. Over the past years, HTS problems have been solved using various mathematical optimization techniques. Such classical optimization techniques have some drawbacks which require a longer time to yield optimal results.

	Emission coefficients of thermal unit		Number of hydro generating units
	Fuel cost curve coefficients of thermal unit		Load demand at time m
	Power generation coefficients of jth hydro unit	,	Minimum and maximum power generation limits for hydro unit
Dlj	Water transport delay from reservoir lth to jth reservoir		Transmission loss at time m
	Total fuel cost of the thermal units	,	Minimum and maximum power generation limits for thermal unit
	inflow rate of jth reservoir at time		Power generation of thermal unit at time m
	Number of time intervals i.e., scheduling period		Power generation of jth hydro unit at time m
NT	Number of thermal generating units		Water discharge rate of jth hydro reservoir at time m
	Minimum and maximum water discharge rate for jth hydro reservoir		Water storage volume of jth hydro reservoir at the beginning of time m
	Number of upstream hydro generating plants directly above the jth hydro reservoir		Minimum and maximum water storage volume of the jth hydro reservoir
	Spillage discharge rate of the jth reservoir at time m