Optimization of Dispatching Electricity Market with Consideration of a Solar-Assisted Coal-Fired Power Generation System

Abstract

This study investigates the multi-objective optimization of load dispatch of a solar-assisted coal-fired power generation system. The improved environmental/economic load dispatch model considers coal consumption, NO x emissions, and power purchase cost. The singular weighted method is utilized to solve this multi-objective and multi-constraint optimization problem. A power system that includes five power generators, one of which is retrofitted to a solar-assisted coal-fired unit, is also analyzed. It can be concluded that the loads of solar-assisted coal-fired units are higher than the original coal-fired unit, and with the increase of solar radiation, the gap between the loads of two units also increases. In addition, after retrofitting, the coal consumption, the NO x emission, and power costs of units reduce by about 2.05%, 0.45%, and 0.14%, respectively. From the study on the on-grid power tariff, where the tariff drops from 16.29 cents/kWh to 3.26 cents/kWh, NO x emissions drop from 12.31 t to 11.28 t per day, a reduction of about 8.38%. The cost of purchasing electricity decreases from $ 2,982,161.8 to $ 2,020,505.0 per day, a decrease of 32.25%. Therefore, when both coal-fired units and solar-assisted coal-fired units exist in a region, the use of solar-assisted coal-fired power generation units should be prioritized.Energies 2019, 12, 1284 2 of 16 157(2) When the temperature of the feed water out of the oil-water heat exchanger is lower than 158 that of the original second heater but higher than that of the original third heater. The feed water 159 enters the second heater. This mode is shown in (b) position. 160(3) When the temperature of feed water out of the oil-water heat exchanger is lower than that of 161 the original first heater but higher than that of the original second heater. The feed water enters the 162 first heater. This mode is shown in (c) position. 163(4) When the temperature of feed water out of the oil-water heat exchanger is higher than that 164 of the original first heater. The feed water enters the boiler. This mode is shown in (d) position.165 3. Methodology 166Under certain constraints, multi-objective optimization aims to have more than one goal to 167 achieve an optimal solution. One of the easiest ways to obtain the optimal solution is called standard 168 quantization or the singular weighted method. A weight is assigned to each target. All the targets 169 with their own weights are positioned together, and then the problem is solved under the same 170 constraints of the original problem. The obtained solution is a solution to the original problem (called 171 the Pareto solution). The weight arrangement is constantly changed; hence, different optimal