Electric Springs for Reducing Power Imbalance in Three-Phase Power Systems

Electric springs have been used previously in stabilizing mains voltage fluctuation in power grid fed by intermittent renewable energy sources. This paper describes a new three-phase electric spring circuit and its new operation in reducing power imbalance in the three-phase power system of a building. Based on government energy use data for tall buildings, the electric loads are classified as critical and noncritical loads so that building energy model can be developed. The proposed electric spring is connected in series with the noncritical loads to form a new generation of smart loads. A control scheme for such smart loads to reduce power imbalance within the building's electric power system has been evaluated initially with an experimental prototype and then in a system simulation study. The results have confirmed the effectiveness of the new three-phase electric springs in reducing power imbalance and voltage fluctuation, making the building loads adaptive to internal load changes and external mains voltage changes.