M. Machmoum

A new analogical method of voltage perturbation extraction for series active power filters

This paper presents a new simple analogical method of supply voltage disturbances identification and the control of a series active filter (SAF) for voltage sag, imbalance and harmonics mitigation. A PID controller is proposed to regulate the injected voltage into the distribution system. The modelling and the simulation of the unit are realised thanks to the PSB tools of Matlab - Simulink. Simulation results are presented and discussed to show that all perturbations like as dips, harmonics ... can be removed from network voltage and confirm the effectiveness of the proposed series active power filter. Experimental results for a laboratory series active filter based on this analogical method are presented to verify the excellent performance of the proposed identification method and controller.

Stochastic study of line harmonic currents produced by rectifiers

The rise of the power level of the converters requires more and more accurate methods to evaluate the current harmonics. Two structures of variable speed drives are investigated and a comparison of their usual models is proposed. A probabilistic approach is employed to determine the influence of power variations on the line harmonic current. The estimated harmonics are confronted to measurements to valid the used method and to discuss its limitations.

A low voltage dynamic voltage restorer with self-charging capability

In this paper a three phase low voltage dynamic voltage restorer (DVR) with a capacitor DC-link will be presented. A proper charging strategy is chosen for charging the DC bus by DVR power converter. The proposed DVR is capable of removing the voltage harmonics (up to 23rd order) and short terms voltage dips very quickly. Voltage identification method and control strategy will be presented and the dynamical and steady state responses of the DVR for non-linear capacitive and inductive loads will be presented and discussed in detail.

Comparison of Control Methods for the Single-Phase Active Power Filter

Abstract Power electronic loads inject harmonic currents into the utility system. The active fl1tering is an atttactive way to compensate both harmonics and reactive power. In this paper, the control of a single-phase active power futer is studied. The control objectives are defmed formelly. For simplicity, only the case of ltarmonics compensation is considered. Different control methods such as high gain control (hysteresis, discrete proportional), pole placement, H 2 and H ∞ designs are reviewed and compared. Some of them are implemented to verify their efficiency.

Harmonics in multiple light dimmer systems

Static power converters have found a wide range of applications in all kind of industries. Even ships do not escape this technology and, consequently, to the problem of harmonics. The harmonic disturbances are very critical on a ship supply network because it is a local one and its impedance has a finite value. Therefore, the prediction of the harmonics level caused by static power converters may help to evaluate accurately the characteristics of the network devices to be installed, such as generators, powerlines, transformers etc.. The aim of this paper is to study the harmonics generated by a large number of light dimmers. Due to the randomness of the operating conditions of each dimmer, a statistical approach seems the most suitable in order to analyse the global behaviour of the system. A multiple single-phase dimmer installation and the influence of some parameters on the line current harmonics are investigated in a first part. Afterwards, the same study is applied to multiple single-phase dimmers supplied by a three phase network.<<ETX>>

Steady-state and stability analysis of a doubly-fed asynchronous machine supplied by a current controlled cycloconverter

The authors present a steady-state investigation of a doubly fed asynchronous machine (DFAM) supplied by a current-controlled cycloconverter (CCC) in the rotor and AC mains in the stator. The model of the DFAM is based on a space vector representation. A theoretical analysis and the characteristics at constant torque are presented. The DFAM is shown to behave like a nonsalient synchronous machine, and the exciting and stator currents are homologous in both machines. The analogy is confirmed by the stator-rotor current characteristics at constant torque and the reactive power flow in the DFAM. The transient performances and the dynamic stability are also analyzed. A stability investigation on a test machine shows the simplicity of the transfer function. For any perturbation, the system can be approximated by a second degree polynomial and is stable within a wide range of the load angle.<<ETX>>

Probability distributions of harmonic currents in multiple phase-controlled loads

A solution, based on a probabilistic approach, is used to obtain power system line harmonic currents generated by a large number of phase-controlled resistive loads. The influence of load number and the inductance of the power supply network are studied. The probability results are compared to classical diversity factors. Experiments have been achieved to verify the accuracy of simulation results.<<ETX>>