A smart solution for a smart grid: Unbalanced reactive power compensation

Abstract

Reactive power flow control is now and will be in the future, the most effective method of optimizing the operating conditions of electricity transmission, distribution and utility networks. As a mean of implementing this method, most often can be found three phase capacitor banks installed in low and medium voltage, having the function of capacitive shunt compensation. A shunt unbalanced capacitive compensation, may lead, in addition to the reducing the reactive power flow, to the total or partly balance of the load on the three phases. When applied in a three-phase four-wire network, the unbalanced capacitive compensator has to contain two three-phase circuits: one in Δ connection to compensate the negative sequence component of the load and the other in Yn connection to compensate the zero sequence component. Balancing an active and reactive unbalanced load with such a compensator is difficult given that should be avoided the capacitive overcompensation on the positive sequence. The paper presents a method for optimizing the susceptances values components of an unbalanced capacitive compensator in terms of maximizing the load balancing and to avoid the capacitive overcompensation. To validate this method, the authors used Simulink and present the analysis results for the case of an unbalanced three-phase load, connected to a low voltage four-wire network. The authors then present a project of an industrial research with government funding, which aim to materialize as an experimental model, both the mathematical model and the optimization method for the capacitive susceptances values of an automatically unbalanced capacitive compensator designed to improve the power factor and load balancing in three-phase four-wire distribution networks.