Enhancing LVRT capability of single stage grid connected PV system in accordance with Indian grid code using proportional direct axis current control technique

In this work, a low voltage ride through (LVRT) scheme for a single-stage grid-connected photo voltaic (PV) system has been proposed to support the drooping point of common coupling (PCC) voltage profile during grid fault by supplying adequate reactive power in the form of quadrature axis current (I_q) to the grid, as per grid code. Since the current generated by the PV inverter increases during fault is dependent on the severity of the fault, the proposed model is designed to adjust the direct axis current (I_d) accordingly to restrict the inverter current within appreciable limits in order to ensure safe operation of the inverter system. The PV system is designed and run on various platforms with the proposed control logic to meet LVRT capability. Besides, the proposed algorithm works well to restrict inverter current within 1.5 per unit (pu) without necessitating any additional resources or causing the existing model's operation vulnerability. The proposed scheme also possesses good efficiency as it avoids any deliberate energy loss through other mechanisms, as it tunes Maximum Power Point Tracking (MPPT) operation according to the requirements, making the present scheme well suited for real-life applications.