Optimal voltage regulation in middle-low voltage distribution network

To improve the voltage profile and reduce the power loss in middle-low voltage distribution network, an optimal voltage regulation method is presented with adjusting transformer taps and capacitors. The heaviest and the lightest load operating conditions are used in the optimization process for wide range of load variation. A membership function is set to evaluate the voltage quality, and the influence of uncertain data on optimization results can be decreased. The voltage quality evaluation is a part of the objective function, thus the voltage constraint is changed from a restriction into an objective. That is, "to ensure voltage profiles eligible" is converted into "to regulate voltage profiles as good as possible". Compensation sites are determined by the sensitivities. The combinational problem is solved by a Tabu search technology. The results of a practical network, improved voltage profile and reduced power loss, shows that this method is effective in wide-range of load-variation in a year by adjusting a few transformer taps and capacitors annually.