Distribution voltage quality at Hydro-Quebec: an integrated approach to control under voltage, overload and losses

This article discusses the latest planning techniques used by Hydro-Quebec Distribution. These practices are now internal standards used to support distribution planning engineers when studying distribution lines. It proposes a global approach where not only under voltage problems are considered but also overload and excessive losses. Since these three aspects are all related to the interaction of the current and the conductor resistance, the causes and the solutions of each problem are generally similar. This is why these problems should all be analyzed together. By using this global approach, it is easier to identify optimal solutions for the network. Moreover, it is sometimes possible to identify a single solution, which allows the correction of more than one problem or provides a significant loss reduction. This integrated voltage control approach is a logical sequence of applying different techniques (load transfer, load balancing, power factor correction, replacing or adding conductors, adding voltage regulators, etc) to improve the voltage quality, as well as to reduce overload and losses. Costs of each technique are considered to optimize the solution process. The optimal solution is obtained by a step by step approach covering all aspects of distribution voltage quality improvement. Capital-intensive techniques like converting the voltage level of the network and adding new feeders or substations are not considered in this paper. These options generally need more advanced economic studies and should be part of the strategic long-range planning of the network.