A Novel Simplified Space Vector Modulator based on Sliding Mode Control for three phase Shunt Active Power Filter

A simplified vector strategy for tracking the compensation current of a three-phase shunt active filter (SAPF) is proposed. SAPF consists of a semiconductor voltage inverter with fully controlled switches, a capacitive storage and a single-link RL filter. The difference in the speed of the dynamic system allows us to distinguish between a fast subsystem, in which the vector method of current control is actually used, and a slow subsystem, the function of which is to stabilize the constant voltage of the storage capacitor. The DC voltage of this capacitor is stabilized by a second-order sliding mode using a finite double-twisting algorithm. The first-order two-dimensional sliding mode is used to tracking the compensation current. The proposed algorithm uses the methods of projective geometry to unambiguously determine the mutual location of spatial vectors of voltages and errors of power supply currents. Since the algorithm does not have difficult mathematical operations for calculating inverse trigonometric functions, it is quite simple in technical implementation. The components of the space vector of equivalent control in a stationary coordinate system are calculated in real time. The choice of the desired output voltage vector of the SAPF inverter is determined by the location of the vector of equivalent control relative to the set of these stationary vectors. Estimation of signs of components of a two-dimensional vector of an error of tracking of current occurs with use of a quasi-stationary two-dimensional sliding surface. The algorithm uses the figure of permissible errors in the form of a circle with a radius equal to the desired value of the instantaneous deviation of each component of the stum from the reference value. A simulation model is built and the simulation results are analyzed.