With increasing concerns of global warming and environmental change caused by the burning of fossil fuels, the operating paradigm of power system is shifting from minimum cost to minimum cost with minimum emission approach. Due to conflicting nature of economic and emission objectives, the generation scheduling becomes a multi-objective problem. In this paper, a multi-objective gravitational search algorithm (MOGSA) is used to provide Pareto optimal solutions which present the possible tradeoff between the cost and emission objectives of unit commitment (UC) problem. The MOGSA technique is used for solving the environmental and economic dispatch problem considering hydro, pump storage plant, wind farm and solar farm, with and without ramp rates. The simulation results demonstrate the effectiveness of the proposed approach in solving multi-objective UC problem.Cost coefficients of the ith generating unitEmission coefficients of the ith generating unitSystem load demand at hour t F T /E T Cost and emission over the scheduling horizon
G t Forecast solar radiation at hour t GstSolar radiation in the standard environmentSchedule state of ith thermal unit at hour t NT/NH Number of thermal/hydro units Ph k (t)Generation of kth hydro unit at hour t P i (t)Generation of ith thermal unit at hour t P (max, min),iMax and min output power of unit i P (max, min),P,G Max and min output power of PSP P i max (t) Max generation of ith thermal unit at hour t P i min (t) Min generation of ith thermal unit at hour t P PG (t)Pumping and generation of PSP unit at hour t P Sn (t) Rated power output of the PV generator P WT (t)Total actual wind generation at hour t P WN Rated wind power output TO k (t)Turbine out flow for reservoir k during hour t TO k(max/min) Max/min turbine water out flow for reservoir k SR(t)