Digital modular protection for grid-connected PMG-based WECSs with battery storage systems

This paper develops and tests a modular digital protection for interconnected permanent magnet generator (PMG)-based wind energy conversion systems (WECSs) with battery storage. The developed protection is constructed from digital relays (modules), each of which provides protection for a specific location of the PMG-based WECS and battery storage. Moreover, each module is featured with phaselet-based fault detection. The outputs of the developed protection are trip signals to operate circuit breakers in the PMG-based WECS, battery storage, and point-of-common-coupling. The modular digital protection is implemented for experimental testing on a 5 kW PMG-based WECS that has a 2.3 kW battery storage. Test results show that the developed protection can offer fast, accurate, and reliable responses to faults occurring in different parts of the tested WECS and battery storage. In addition, test results show that the modular digital protection has minor sensitivity to the location of faults, charge/discharge cycles of the battery storage, and/or levels of power delivery to the host grid.