Solution to security constrained lossy economic power dispatch problem for a power system area including limited energy supply thermal units using modified subgradient algorithm based on feasible values

In this paper, a security constrained power dispatch problem for a lossy electric power system area including limited energy supply thermal units is modeled in such a way that the modified subgradient algorithm based on feasible values (F-MSG algorithm) can be used to solve it. This model considers bus voltage magnitudes and phase angles, off-nominal tap ratios (once there are off-nominal tap changing transformers in the power system) as independent variables. Load flow equations are added to the model as equality constraints. Power system transmission loss is inserted into the optimization model via those load flow equations. Unit generation constraints, transmission line capacity constraints, bus voltage magnitude constraints, off-nominal tap ratio constraints are added into the optimization problem as inequality constraints. We assume that limited energy supply thermal units are fueled under take-or-pay agreement. The F-MSG algorithm is tested on a fifteen-bus test system. The dispatch problem was also solved by other dispatch techniques that use pseudo spot price algorithm and genetic algorithm. Results obtained from the F-MSG algorithm and the other techniques are compared.