A Supplemental Control for Dynamic Voltage Restorers to Improve the Primary Frequency Response of Microgrids

Distribution utilities around the world have begun deploying dynamic voltage restorers (DVRs) to improve the power quality for end-use consumers. While these devices normally operate to improve power quality, the sensing and control they use can be leveraged to provide additional operation benefits. This paper describes a supplemental control for DVRs that enables them to improve the primary frequency response of microgrids through regulating voltage-dependent loads. The control strategy has been tested on a commercially available DVR to demonstrate the practicality. Furthermore, to examine the impacts on full-size, medium-voltage microgrids that typically have thousands of nodes, an electromechanical model of the DVR has been developed and compared with experimental results. Simulation in a modified, islanded IEEE 8500 Node Test Feeder with 15 DVRs shows that the supplemental control can effectively improve the primary frequency response of microgrids. From the industry application perspective, the proposed supplemental control expands the functionality of DVRs from only improving power quality to including frequency regulation. Therefore, the DVRs deployed in microgrids not only can compensate for voltage disturbances, but also can stabilize the system frequency.