Energy saving dispatch with complex constraints: Prohibited zones, valve point effect and carbon tax

This paper presents an energy saving dispatch (ESD) strategy, based upon the optimal power flow (OFF) model, considering complex constraints, such as prohibited operating zones, the valve point effect of generation units and the carbon tax of a power grid. With these constraints, the OPF problem becomes more difficult to resolve, and it needs to be dealt with by a more accurate and reliable optimization algorithm. In this paper, an improved group search optimizer (GSO), namely the group search optimizer with intraspecific competition and levy walk (GSOICLW), is adopted to tackle this problem. It is more biologically realistic than GSO, in which intraspecific competition (IC) and levy walk (LW) are incorporated in the original GSO. IC and LW of GSOICLW are capable of achieving superior balance between global and local searching, i.e., GSOICLW maintains GSO's global searching ability to avoid entrapping in local optima while improves local searching near the global optima. The standard IEEE 30-bus power system is employed to carry out the simulation study to test GSOICLW, which is subsequently compared with other evolutionary algorithms (EAs). Simulation results show that GSOICLW outperforms other EAs used in this research and also provides accurate and reliable optimization results in dealing with the OPF problem for ESD. (C) 2014 Elsevier Ltd. All rights reserved.