Multi-Objective Short-Term Hydro-Thermal Scheduling Using Meta-Heuristic Approaches

1. Introduction

Multi-objective short-term hydrothermal scheduling (MOHTS) is a vital organizing task in operation of the power system. Usually, hydro-thermal power system scheduling is more complex than thermal system scheduling. The bordering manufacture price of hydroelectric plants is insignificant, but one of the important problems is usage of available water. The cost of thermal generation is increased if they are present alone in the power system. However, the presence of large number of hydroelectric plants with a set of constraints coupled in proper time periods to maximize power generation from hydroelectric plants may decrease the cost. Economic load dispatch (ELD) is an optimization approach in the thermal power system which try to schedule power generation according to the load demand from the power plant. Conventionally, the hydrothermal power systems are worked in such a way that the total fuel cost is reduced with optimal power generation by both hydro and thermal power plant.

In our research work, we want to schedule the power generating units in such a way that’s why manufacturing cost is minimized. Load demand is circulated among generating units in ELD (Wood & Wollenberg, 1994; Happ, 1997; Chowdhury & Rahman, 1990; Liu & Cai, 2005) problem which will satisfy generation limit, prohibited operating zone, ramp rate, etc., considering transmission loss at every time interval such that the over-all cost is minimum. Fossil fuel produces various pollutants, like nitrogen oxides, carbon dioxide, sulfur oxides, etc., into the atmosphere at the time of generation of electricity from thermal power plant. The power companies have to assured standards concerning about the emission levels of pollutants for the strict government guidelines on ecological protection. As a responsible citizen, we must try to clean the air from different poisonous gasses. By European Clean Air Act Amendments of 1990 and similar acts by Japanese governments and others, show their concern by the management rules (Yalcinoz, Altun & Hasan, 2002). The awareness due to the increasing anxiety over contaminants, society bothers apposite and safe electric power must get in low price but in lower level of pollution. Newly, ELD problem has been incorporated by emission dispatch (CEED) problem (Roy, Ghoshal & Thakur, 2010a; Roy, Ghoshal & Thakur, 2010b; Zhang, Luh & Zhang, 1999); where many researchers consider emission as an additional constraint or second objective function with minimize the cost economy. For the instance of short-term hydro-thermal load managing, it is typically expected that the water volume entrances essential to encounter the load necessities and load demand are recognized through certainty. The several restrictions that cannot be disrupted HTS is a complicated decision-making process. Water discharge rate, hydraulic continuity restriction, lower and upper bounds of the reservoir volumes, water spillage, effective capacity limits of hydro plant etc., constraints makes the HTS problem as a complex optimization problem whose viable solution space is enormous.

Numerous optimization algorithms for mathematics are applied to the hydrothermal scheduling problem (Zhang, Luh & Zhang, 1999; Al-Agtash, 2001). Several classical methods, such as decomposition approach (DA) (Pereira & Pinto, 1983), dynamic programming (DP) (Yang & Chen, 1989), linear programming (LP) (Mohan, Kuppusamy & Khan, 1992), non-linear programming (Gul et al., 2019) and progressive optimality algorithm (Turgeon, 1981) have been deployed to solve the HTS problem. DP faces dimensionality problem in multi-dimensional search space. Other algorithms also have different kinds of obstacles like fall into local optima instead of the global optima in multi-dimensional search space, low convergence rate etc.