Digital/Physical Hybrid Simulation Method Based on NI-PXI for Hierarchical Control Strategy of Micro-grid

As to the islanded micro-grid composed of multi-voltage source type micro-sources, a hierarchical control strategy based on the droop control of micro-sources is proposed. On the primary control level, the power of the isolated system is automatically allocated between micro-sources. On secondary control level, the no-load frequency and voltage of droop curve characteristics are adjusted by micro-grid energy management system (MGEMS) to improve power quality. On tertiary control level, the power and droop gain of droop characteristics at rated set point are coordinated by MGEMS to achieve economic operation of micro-grid. A digital/physical hybrid simulation scheme based on NI-PXI (PCI Extensions for Instrumentation, PXI) of micro-sources is proposed, and a real-time modeling and simulation method based on NI VeriStand is realized in this paper. In the end, a digital/physical hybrid simulation platform for hierarchical control based on NI-PXI is built in National Wind Power Grid Integration R&D(Testing)Center, and the validity of hierarchical control strategy is verified based on the digital/physical hybrid simulation experiment for hierarchical control of micro-grid.