Research on DVR Compensation Limit Considering the Influence of Power Distribution System Parameters

There is compensation limit for the series-and -shunt connected dynamic voltage restorer (DVR), which cannot fully compensate all voltage sag cases. To deeply discuss this problem, this paper establishes a voltage divider model for a voltage sag for 10kV power distribution system, and the Thevenin equivalent circuit and mathematical expression of the model are derived and analyzed before and after voltage sag. The relationship between DVR compensation capacity and power distribution system parameters is shown, and the principle for voltage sag compensation is revealed through the volt-ampere characteristic curve. It is pointed out that whether the sag voltage can be fully compensated by DVR or not depends on the intersection between source volt-ampere characteristic curve and load rated power curve. Then the maximum output power of equivalent source and corresponding DVR compensation limit are derived by mathematical methods. Finally, the correctness of the above theory is verified by simulation analysis.