Feedforward effect on the transient response during low voltage ride through

Abstract

Suitable control methods and strategies applied in Power Electronic converters are vital to interconnecting renewable energy sources within a microgrid and the utility grid. Grid codes and international standards are introducing new specifications according to the rapid changes the electric power systems are experiencing in the last decades. Therefore, developing, testing and upgrading the control methods to fulfil those new standards is essential. This paper focuses on the Low Voltage Ride Through (LVRT) capability applied in an industrial inverter connected to the grid through an LCL filter with a maximum admissible inverter-side current of 1.23 p.u. The main challenge is that the protective circuit shuts the inverter down once maximum current is exceeded (as a result of a sudden drop in grid voltage) and disconnects from the grid; hence making it not compliant with the standards. This paper investigates the effect of the Feedforward voltage loop on the inverter side peak current and suggests solutions to limit the current based on modifying the feedforward structure and tuning the controller parameters. Simulation results show a reduction in the inverter side current from 1.89 pu to 1.09.