Impact of Reactive-Power Optimization on Voltages in a Power System

The parameters of voltages in a power system are essential element of evaluation of power quality. The paper deals with deviations of voltage magnitudes from the predetermined values. One of the ways of reducing the mentioned deviations is reactive power optimization. At the beginning of the paper, dependence of the voltage magnitude at the end of the branch on reactive power flow on this branch is considered. Proper determination of reactive power flow on the branch enables decreasing the difference between voltage magnitudes at the ends of this branch. Performing reactive power optimization, one can find such reactive power flows in a power system, that nodal-voltage magnitudes are increased and at the same time the difference between maximum and minimum value of nodal-voltage magnitudes in a power system decreases. In the paper, correlation between changes of system active-power loss and a voltage-oriented index, to be effect of the reactive-power optimization, are also investigated. It is evident that for most of the cases of power system operation, that correlation is strong. So, in a reactive power optimization process, the similar voltage effect can be achieved, when the objective function is system active-power loss as well as when this function is the considered voltage-oriented index.