An Improved digital multi-resonant controller for 3 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"><mml:mi>ϕ</mml:mi></mml:math> grid-tied and standalone PV system under balanced and unbalanced conditions

With the exponential penetration of Photovoltaic (PV) plants into the power grid, advanced current controllers should be employed in grid-tied power converters in order to efficiently inject high quality current synchronized with the grid voltage. This research presents the modeling and design of a digital multi-resonant controller to feed-in high quality current. The novelty lies in designing the control in a superior manner to conventional techniques. As an outcome, practical engineers discover an easy, fast, robust, and accurate control method. The proposed 5-kVA PV system can inject active and reactive power effectively while staying resilient to imbalance scenarios. Synchronization is accomplished via a synchronous reference frame (SRF) based phase locked loop (PLL) that performs effectively even with distorted and nonideal grids. The practicality and efficacy of the developed controller is verified both in simulation (PSIM and code composer studio) and Hardware in Loop (HIL) via Typhoon 402 and TMS32F28335 experiments. The devised controller is evaluated in both grid-connected and standalone modes under a wide range of disturbances, distortions, and non-ideal conditions. The simulation and HIL results validate the robustness, fastness, resilience, and effectiveness of the proposed controller compared with a well-tuned conventional proportional resonant (PR) controller.