High performance control of a single-phase shunt active filter

Shunt active power filters are devices connected in parallel with nonlinear and reactive loads which are in charge of compensating these characteristics in order to assure the quality of the distribution network. This work analyzes the dynamics of boost-converter used as an active filter and proposes a control system which guarantees closed-loop performance (power factor close to 1 and current harmonics compensation). Proposed controller is hierarchically decomposed in two control loops, one in charge of shaping the current and the other in charge of assuring the power balance. Differently from other works both control loops are analytically tuned. The work describes both the analytical development and the experimental results showing the good performance of the closedloop system.Peer Reviewe

Comparison of different repetitive control architectures: synthesis and comparison. Application to VSI Converters

Repetitive control is one of the most used control approaches to deal with periodic references/disturbances. It owes its properties to the inclusion of an internal model in the controller that corresponds to a periodic signal generator. However, there exist many different ways to include this internal model. This work presents a description of the different schemes by means of which repetitive control can be implemented. A complete analytic analysis and comparison is performed together with controller synthesis guidance. The voltage source inverter controller experimental results are included to illustrative conceptual developmentsPeer ReviewedPostprint (published version

A passive repetitive controller for discrete-time finite-frequency positive-real systems

This work proposes and studies a new internal model for discrete-time passive or finite-frequency positive-real systems which can be used in repetitive control designs to track or to attenuate periodic signals. The main characteristic of the proposed internal model is its passivity. This property implies closed-loop stability when it is used with discrete-time passive plants, as well as the broader class of discrete-time finite-frequency positive real plants. This work discusses the internal model energy function and its frequency response. A design procedure for repetitive controllers based on the proposed internal model is also presented. Two numerical examples are included.Peer Reviewe

Non-uniform sampling in digital repetitive control systems: An LMI stability analysis

Digital repetitive control is a technique which allows to track periodic references and/or reject periodic disturbances. Repetitive controllers are usually designed assuming a fixed frequency for the signals to be tracked/rejected, its main drawback being a dramatic performance decay when this frequency varies. A usual approach to overcome the problem consists of an adaptive change of the sampling time according to the reference/disturbance period variation. This report presents a stability analysis of a digital repetitive controller working under time-varying sampling period by means of an LMI gridding approach. Theoretical developments are illustrated with experimental results

A new passive repetitive controller for discrete-time finite-frequency positive-real systems

This work proposes a new repetitive controller for discrete-time finite-frequency positive-real systems which are required to track periodic references or to attenuate periodic disturbances. The main characteristic of the proposed controller is its passivity. This fact implies closed-loop stable behavior when it is used with discrete-time passive plants, but additional conditions must be fulfilled when it is used with a discretetime finite-frequency positive-real plant. These conditions are analyzed and a design procedure is proposed.Peer Reviewe

A repetitive controller for discrete-time passive systems

This work proposes and studies a new repetitive controller for discrete-time systems which are required to track or to attenuate periodic signals. The main characteristic of the proposed controller is its passivity. This fact implies closed-loop stable behaviour when it is used with discrete-time passive plants. The work also discusses the energetic structure, the frequency response and the time response of the proposed controller structure. Some examples are included to illustrate its practical use

Odd-Harmonic Digital Repetitive Control of a Single-Phase Current Active Filter

Shunt active power filters have been proved as useful elements to correct distorted currents caused by nonlinear loads in power distribution systems. This work presents an all-digital approach, based on the repetitive control technique, for their control. In particular, a special digital repetitive plug-in controller for odd-harmonic discrete-time periodic references and disturbances is used. This approach does not introduce high gain at those frequencies for which it is not needed, and thus it improves robustness. Additionally, the necessary data memory capacity is lower than in traditional repetitive controllers. The design is performed for the particular case of single-phase shunt active filter with a full-bridge boost topology. Several experimental results are also presented to show the good behavior of the closed-loop system.Peer Reviewe

UDE-based controller equipped with a multiple-time-delayed filter to improve the voltage quality of inverters

In this paper, a two-degrees-of-freedom control algorithm based on uncertainty and disturbance estimator (UDE), aimed to minimize the total harmonic distortion of inverter output voltage is proposed, possessing enhanced robustness to base frequency variations. A multiple-time-delay action is combined with a commonly utilized low-pass UDE filter to increase the range of output impedance magnitude minimization around odd multiples of base frequency for enhanced rejection of typical single-phase nonlinear loads harmonics. Marginal robustness improvement achieved by increasing the number of time delays is quantified analytically and revealed to be independent of delay order. The performance of the proposed control approach and its superiority over two recently proposed methods is validated successfully by experimental results

Digital Repetitive Control of a Three-Phase Four-Wire Shunt Active Filter

Shunt active power filters have been proved as useful elements to correct distorted currents caused by nonlinear loads in power distribution systems. This paper presents an all-digital approach based on a particular repetitive control technique for their control. Specifically, a digital repetitive plug-in controller for odd-harmonic discrete-time periodic references and disturbances is used for the current control loops of the active filter. This approach does not introduce a high gain at those frequencies for which it is not needed and, thus, improves robustness of the controlled system. The active power balance of the whole system is assured by an outer control loop, which is designed from an energy-balancing perspective. The design is performed for a three-phase four-wire shunt active filter with a full-bridge boost topology. Several experimental results are also presented to show the good behavior of the closed-loop system.Peer Reviewe

Control repetitivo impar de alto orden de un rectificador monofásico: operación a frecuencia variable

Controlled rectifiers are electronic power devices aimed at reducing the harmonic pollution in electrical networks caused by the power conversion process. The main goal is to obtain a sinusoidal shape current in phase with the voltage network. Although Proportional Integral controllers are widely used for the current control loop, they do not provide high performance results. On the contrary, Resonant and Repetitive Control are techniques with remarkable results on this area. However, their main drawback is the lost of performance due to frequency changes in the exogenous signal. In this work, the implementation of an Odd Harmonic High Order Repetitive Controller is proposed for the rectifier current loop. The odd harmonic characteristic of this compensator makes possible to obtain a computational burden that is very similar to the one obtained by conventional repetitive controllers with the advantage of increase the robustness against frequency variations. Experimental results show the high performance obtained even when the network frequency does not match the designed nominal frequency.Los rectificadores de potencia controlados son dispositivos utilizados con el fin de minimizar la contaminación armónica producida en las redes eléctricas durante el proceso de conversión de la potencia. El objetivo es obtener una corriente de entrada sinusoidal en fase con el voltaje de la red. Aunque es extenso el uso del control Proporcional Integral en el lazo de corriente, no es posible lograr altos desempeños con estos compensadores. Por otro lado, el Control Repetitivo y el Control Resonante son técnicas mediante las cuales se logran resultados excepcionales. La desventaja de estas estrategias de control es la gran pérdida de desempeño en el sistema cuando la frecuencia de lared se desvía de su valor nominal. En este artículo, se propone el uso de un Controlador Repetitivo Impar de Alto Orden para el lazo de corriente del rectificador. Este controlador se diseña para obtener una señal sinusoidal de corriente y rechazar los armónicos impares introducidos en el sistema. Al atacar sólo los armónicos impares, el costo computacional de su implementación resulta muy similar al del controlador repetitivo convencional, con la ventaja de proporcionar robustez ante cambios en la frecuencia de la red. Los resultados experimentales muestran el alto desempeño del compensador aún cuando la frecuencia de la red se desvía del valor nominal de diseño