Profit-based unit commitment of integrated CHP-thermal-heat only units in energy and spinning reserve markets with considerations for environmental CO2 emission cost and valve-point effects

For the purposes of lowering environmental emission cost and increasing economic profit, energy efficient combined heat and power (CHP) units can be integrated with conventional separate heat and power production units to meet heat and power demands. The goal of this study is to develop and examine a novel heuristic and deterministic optimization algorithm for solving the profit-based unit commitment (PBUC) problem for a generation company with integrated CHP-thermal-heat only system for (i) satisfying demands for heat and power, (ii) selling spinning reserve for power, (iii) reducing environmental CO2 emission cost, and (iv) accounting for valve-point effects for steam turbines. For validation, the developed optimization algorithm is applied to power systems examined in other studies for a 24 h operation period, where reduction of 2.54-5.86% in environmental CO2 emission and improvements of 2.91-5.67% in economic profit are achieved. When environmental CO2 emission cost and valve-point effects are considered, the utilization of CHP units in an integrated CHP-thermal-heat only system results in environmental CO2 emission reduction and economic profit improvement by and 29.45 and 15.41%, respectively, as compared with those resulting from operating thermal and heat only units separately.