A noniterative optimized algorithm for shunt active power filter under distorted and unbalanced supply voltages

In this paper, a single-step noniterative optimized algorithm for a three-phase four-wire shunt active power filter under distorted and unbalanced supply conditions is proposed. The main objective of the proposed algorithm is to optimally determine the conductance factors to maximize the supply-side power factor subject to predefined source current total harmonic distortion (THD) limits and average power balance constraint. Unlike previous methods, the proposed algorithm is simple and fast as it does not incorporate complex iterative optimization techniques (such as Newton-Raphson and sequential quadratic programming), hence making it more effective under dynamic load conditions. Moreover, separate limits on odd and even THDs have been considered. A mathematical expression for determining the optimal conductance factors is derived using the Lagrangian formulation. The effectiveness of the proposed single-step noniterative optimized algorithm is evaluated through comparison with an iterative optimization-based control algorithm and then validated using a real-time hardware-in-the-loop experimental system. The real-time experimental results demonstrate that the proposed method is capable of providing load compensation under steady-state and dynamic load conditions, thus making it more effective for practical applications.