Sliding Mode Control Techniques for Voltage Source Converters under Low-Voltage Ride-Through Scenarios

Abstract

The present paper evaluates different sliding mode control techniques for the negative-sequence current injection of voltage source converters under low-voltage ride-through scenarios. Under such scenarios those devices are required, from the grid code specifications, to inject reactive power to help mitigate voltage sag situations. The implicit unbalanced and faulted conditions of this scenario demands a robust enough control strategy to ensure system stability. The robustness requirements and the variety of scenarios justify the consideration of sliding mode for current control. However, the control method is also required to exhibit a smooth and rapid performance during steady-state operation conditions. Among the studied cases an adaptive super-twisting algorithm present better results for this application when considering long-term operation. The implementation of these control techniques might imply challenges on line protections. HiL application is discussed in order to assess the challenges and key considerations that need to be addressed.