Non linear control of the UPQC for grid current and voltage improvement

The problem of controlling Unified power Quality Conditioners (UPQC) is addressed in presence of nonlinear loads. In this paper, a oriented control model for UPQC-load system, is developed. The control objective is threefold: (i) Compensating for the current harmonics and the reactive power absorbed by the nonlinear load; (ii) Compensating for the voltage harmonics and fluctuations; (ii) Regulating the inverter DC capacitor voltage. To this end, based on the UPQC model, a nonlinear controller is developed, using the backstepping technical design. Moreover, the controller is made adaptive for compensating the uncertainty on the switching loss power. The performances of the proposed adaptive controller are formally analyzed using tools from the Lyapunov stability and the averaging theory. The performances of the proposed controller is illustrated through simulation.