Meta Heuristic Search for Multi Objective Generation Scheduling of Electric Power Systems

Abstract

In an interconnected power system, the demand of power from all the agriculture, commercial, industrial and domestic consumers needs to be fulfilled with security and reliability. The organization of power system includes integrated operation of generation, transmission, distribution and control system. Further, the control of complex power system is very important due to economical and environmental constraints. The strict requirements of consumers imposed necessity for higher level of system planning along with economic operation of power system, minimum impact of environment in case of fossil fuel power generation plants, minimization of transmission losses. These are some of the key objectives for economically effective performance of power system network to be achieved. The optimization problems are known as economic load dispatch problem (single objective) and combined environmental and economic dispatch problem (multi-objective) in which, the objective is to minimize fuel cost, minimize emission of gaseous pollutants while satisfying all equality and inequality constraints. Mathematically, a simple economic load dispatch problem is expressed as a quadratic function for the fuel cost of a thermal power generating unit. It is defined as the minimization of this fuel cost function for each generating unit so that fuel cost of entire power generating plant has to be reduced and all practical limitations must be satisfied. These restrictions may include fulfillment of power demand and power losses, minimization of power losses, valve point loading effect, prohibited operating zones and ramp rate limits. The discontinuities and non-linearities in input/output characteristics are represented as constraints of real optimization problems. Valve point effect is modeled as a recurring rectified sinusoidal function which makes a complex fuel cost function. The feasible solution must lie within the defined minimum or maximum active power limits and is known as inequality constraint. Further, Transmission losses should be minimized, which are the part of equality constraint. The prohibited operating zones are defined in input and output characteristics of generator and these zones must be avoided for better operation. The operating range of power generation is further restricted within defined operating periods in case of ramp rate limits. newline