Linearisation method and control for series active power filter by means of pulse-width modulation

The increase of nonlinear loads in networks involves rises in harmonic currents, resulting in voltage distortion that can affect other sensitive loads. The series voltage compensators are the devices used to reduce voltage deformation in networks of nonnegligible impedance. The control technique of the series compensator is one factor which can improve the operation of the series compensator, in order to reduce voltage disturbances existing in the network. The control of devices controlled by PWM permits the use of classical linear strategies and nonlinear control. Initially, in the paper, the linear and discrete model of the voltage compensator is obtained by using an original linearisation method for systems controlled by PWM, which shows better behaviour than conventional methods. Then a control algorithm is developed in minimum time based on the linear model obtained. The control algorithm has been simulated and has subsequently been implemented in a laboratory prototype of the series compensator, giving very satisfactory results.