Probabilistic estimation of propagation of unbalance in distribution network with asymmetrical loads

Abstract

This paper develops a method for the statistical estimation of the level of voltage unbalance in networks when asymmetrical loads exist. Voltage unbalance causes overheating problems and efficiency reductions in power systems, which result in additional economic costs for both Distribution Network Operators (DNOs) and consumers. Therefore, given the parameters of a specific network, if the range of voltage unbalance level can be estimated, improvements can be undertaken accordingly. This paper employs three-phase full Newton-Raphson load flow to derive online power flow parameters and symmetrical components of relevant network quantities to derive the voltage unbalance level. By using both specified asymmetrical loads and normally distributed asymmetrical loads, the possible range of voltage unbalance level for a selected bus of a simple network is indicated. The simulations are performed on model of a real 24-bus network to validate proposed methodology. (6 pages)