Voltage stability and thermal limit: Constraints on the maximum loading of electrical energy distribution feeders

The loading condition of distribution systems is assessed with respect to voltage stability as well as to thermal limit. Real networks of a distribution utility of Brazil are used in the tests performed. Results show that the maximum loading may be limited by voltage stability rather than by thermal limit. The paper shows the necessity of considering voltage stability as a new constraint on the operational loading of electrical energy distribution feeders, including the connection of new consumers. The voltage stability constraint should be considered in studies concerning distribution systems expansion. The new planning constraint may avoid the building of new lines and transformers which could never be fully used in systems already stressed by voltage stability.