Minimum Energy Compensation Strategy and Characteristic Analysis for Dynamic Voltage Restorer

The minimum energy compensation strategy and its characteristic for Dynamic Voltage Restorer (DVR) considering the equipment´s voltage limitation are discussed. The strategy when the injection voltage is under or especially above the voltage limitation is proposed. And the detailed expressions of the strategy which show that the compensation effect is influenced by three factors - magnitude of the system voltage sag (or swell), power factor of load and limitation value of the compensation voltage were given. The compensation characteristic that DVR could operate in zero, minimum or voltage limitation minimum active power exchange state if the three factors satisfy certain relations was analyzed. Last, the quantitative curves of the compensation characteristic were given. The analysis results will be helpful to compensation strategy design and engineering practice for DVR.