A computationally efficient current controller for simultaneous injection of both positive and negative sequences

Reducing the required processing time of current controllers used in grid side converter (GSC) of renewable energy systems (RES) allows to optimize the limited processing resources and at the same time minimize the cost of the processors required. In addition, the transient behavior of these controllers must be fast and with low overshoot for the GSC to support the grid during off-nominal grid conditions and according to the grid code requirements imposed. For a converter to respond accordingly, the injection of both positive and negative sequences of fundamental current under off-nominal grid conditions is necessary. The work presents a GSC current controller that meets all modern grid requirements expected. It has been developed by introducing two modifications to an existing current controller. Experiments and simulations have been performed to validate the operation of the proposed current controller in terms of complexity and performance. Consequently, the new current controller requires 22% less processing time and can achieve a faster and more accurate response in order to meet modern grid code requirements under off-nominal conditions.