A Discrete State-Space Control Scheme for Dynamic Voltage Restorers

Abstract

This paper presents a discrete state-space controller using state feedback control and feed-forward decoupling to provide a desirable control bandwidth and control stability for dynamic voltage restorers (DVR). The paper initially discusses three typical applications of a DVR. The load-side capacitor DVR topology is preferred because of its better filtering capability. The proposed DVR controller offers almost full controllability because of the multi-feedback of state variables, including one-beat delay feedback. Feed-forward decoupling is usually employed to prevent disturbances of the load current and source voltage. Directly obtaining the feed-forward paths of the load current and source voltage in the discrete domain is a complicated process. Fortunately, the full feed-forward decoupling strategy can be easily applied to the discrete state-space controller by means of continuous transformation. Simulation and experimental results from a digital signal processor-based system are included to support theoretical analysis.

Control of Parallel Connected Three-Phase PWM Converters without Inter-Module Reactors

“…To optimize the PI controller gains of a sampled data system in the continuous time domain, it is necessary to determine an equivalent continuous time model that considers the delay time (T d ) produced by the sampling process and the algorithm computation time [18], [19]. The design objective in such an exercise is to maximizes the controller gains (K p and K i ) with the desired phase margin (ϕ m ) while the forward path open loop gain tracks through unity [20].…”