FUEL-COST MINIMIZATION FOR BOTH REAL-POWER AND REACTIVE-POWER DISPATCHES

The fuel cost formula is developed for optimal real- and reactive-power dispatch for the economic operation of power systems. The problem is decomposed into a P-optimization and a Q-optimization module, where both modules use the same fuel cost objective function resulting in the optimal load flow. The control variables are generator real-power outputs for the real-power module; and generator reactive-power outputs, shunt capacitors/reactors and transformer tap settings for the reactive-power module. The constraints are the operating limits of the control variables, power-line flows and busbar voltages. The optimization problem is solved using the gradient projection method (GPM) for the quadratic objective function and linear constraints. The GPM allows the use of functional constraints without need of penalty function or Langrange multipliers.