Sensorless Nonlinear Control Strategy of the Single Phase Active Power Filters via Two-time Scale Singular Perturbation Technique

Abstract

This paper focuses on the problem of controlling single-phase shunt active power filters (APFs) operating in the presence of nonlinear and uncertain loads. The main difficult ies when controlling this kind of filter are the existence of a strong non-linearity of the system and state variables inaccessible to measurements. This paper proposes a double-loop cascade controller developed on the basis of the singular perturbation technique in order to meet t wo main control object ives: (i) the inner-loop is designed to compensate the harmonic and reactive currents absorbed by the nonlinear load enforcing power factor correction; (ii) the outer-loop is synthesized to regulate the inverter output capacitor voltage. The controller also includes two-time scale sliding mode observer to estimate the network voltage that is not accessible to measurement. In this work, the singular perturbation technique and averaging theory are used for a co mplete and rigorous formal analysis to describe the control system performances. The effectiveness of this approach has been successfully verified through computer simu lations using the Matlab/Simulink environment.

Advanced nonlinear controller of single‐phase shunt active power filter interfacing solar photovoltaic source and electrical power grid

“…Some of those works only considered the classical structure of SAPF without PV sources. 12,25,27 The present paper focuses on the control problem of a power system consisting of a SAPF and a couple of solar PV generators. The studied structure allows the integration of solar PV renewable energy sources.…”

“…Also, all the above‐mentioned works did not address the steady‐state analysis and closed‐loop stability. Some of those works only considered the classical structure of SAPF without PV sources 12,25,27 …”

“…As a matter of fact, controllers based on linearized model are only efficient in the neighborhood of the operating point and may not give a satisfactory performance under parameter variations and load disturbances. The use of the nonlinear averaged model in control design provides more consistent control activity guaranteeing global convergence of the system to the desired operating point and better protection for actuators 23‐25 . A Lyapunov design approach with an adaptive observer has been well discussed in Reference 26 for three‐phase SAPF to achieve PFC, without assuming the grid power characteristics to be a priori known.…”

“…The use of the nonlinear averaged model in control design provides more consistent control activity guaranteeing global convergence of the system to the desired operating point and better protection for actuators. [23][24][25] A Lyapunov design approach with an adaptive observer has been well discussed in Reference 26 for three-phase SAPF to achieve PFC, without assuming the grid power characteristics to be a priori known. In the same vein, a Lyapunov technique with Kalman observer of single-phase SAPF is discussed in Reference 12.…”