An advanced current controller with reduced complexity and improved performance under abnormal grid conditions

Electricity grid regulations are frequently revised in order to accommodate the ever-increasing penetration of distributed renewable energy systems (RES). Interconnected RES are required to operate conditionally under normal and abnormal grid conditions. Furthermore, RES are required to have fault ride through (FRT) capability so that they can provide voltage and frequency support to the grid. The FRT operation may necessitate the injection of positive, negative or both sequence components of current. Therefore, appropriate control techniques are needed that can perform under all grid conditions (faults and harmonics) without violating the grid codes. A benchmarking comparison between two existing current control techniques motivated the proposal of a new current controller with an improved performance and lower computational complexity. The proposed controller allows accurate injection of pure sinusoidal positive, negative or both sequences currents under normal and abnormal grid scenarios. The proposed control strategy can work with considerably lower computational complexity and with improved response as compared to the two existing controllers.