Comparison of FPGA based control strategies (DDSRF-PI vs. State-Space Control) for grid connected inverters under grid disturbances

Measurement results in the TestLab Power Electronics at Fraunhofer ISE show that many manufacturers of utility-scale PV inverters have problems to control the current under grid disturbances generated by the low voltage ride through (LVRT) test facility. Therefore a statespace control approach has been evaluated which shows better behaviour than the state-of-the- art DQ-PI-control. The algorithms were implemented on an FPGA platform instead of the widely used Microprocessors to reduce computation delay. Results show, that an FPGA based control platform increases the flexibility for different control techniques and overall controller performance which is verified by measurements under real conditions.