Evaluation, practice and remarks on the IEC 61000-3-2 standard

This paper describes an evaluation,interpretation and discussion of the IEC61000-3-2standard [1]. Since January 2001, this standard isapplied. Some of the directives mentioned in thisreference are liable to interpretations, test conditionsare not well defined and warm up conditions areneglected (except for lamps). In practice, a lot ofsingle phase [2] as well as three phase non linear loadsdo not comply with the standard. All tested devicesshow bad power quality parameters. Using an IEC fullcompliant programmable power source and poweranalyzer, several test set ups are analyzed, withrespect to the IEC61000-3-2 standard.The paper presents some important remarks andconclusions, based on measurements on several singlephase non linear loads

Impact of harmonic voltage distortion on the voltage sag behavior of adjustable speed drives

The behavior of adjustable speed drives under voltage sag conditions and supplied form non-sinusoidal voltage waveforms has received little attention in recent years. This paper shows that voltage harmonic distortion has a major impact on the drive behavior. The impact of voltage sag conditions, including harmonics is represented by means of voltage tolerance curves. To overcome the impact, a fast field weakening control scheme for field oriented induction motor drives is analyzed

Advanced nonlinear modelling techniques for switched reluctance machines

This paper gives an overview of different modelling techniques to describe the nonlinear behaviour of both saturated switched reluctance machine (SRM) and power electronic converter. The current research contributes by comparing the de-coupled single-phase superposition method (lookup-tables) with a coupled analysis between drive model in Matlab/Simulink® and finite element model of the SRM motor. Experimental characterization techniques as well as finite element techniques are used to obtain the single-phase flux-linkage data. Transient electromagnetic analysis using the finite element method,coupled with a drive model and optimization strategy in Matlab/Simulink®, results in a more accurate SRM modelling. These results are more accurate because the mutual coupling between different phases is taken into account. Using this direct coupling, a complete analysis of the motor behaviour (local saturation, iron losses, …) can be modelled with the finite element software, keeping the complex drive and control strategy in Matlab/Simulink®.At every time step of the discrete solver, data is exchanged between the drive model and the coupled electric circuit of the finite element analysis.Simulation results are compared with measurements offlux-linkage, torque, phase current and iron losses. Pro’s and contra’s of the coupled and de-coupled modelling technique are discussed

Measuring line parameters of multiconductor cables using a vector impedance meter

In the present paper, a method to measure the parameters of a multiconductor transmission line is given. The method is accurate, straightforward and only needs a single vector impedance meter or equivalent. The method has been applied for frequencies in a range from 20 kHz up to 30 MHz

Total harmonic current of a large number of non-linear single phase loads

The cumulative harmonic currents of a large number of non-linear single phase loads, particularlyPC’s and monitors, are investigated experimentally. In reference [1], it is shown, by means of ananalytical model, that there is a significant attenuation of the current harmonics above the third when alarge number of such loads is considered. In this paper, the simulation results are verified bymeasurements

Modeling of the behavior of AC undervoltage relays during voltage dips

This paper proposes a dynamic model for the behavior of an AC undervoltage protection relay during voltage dips. The behavior is expressed by means of standardized voltage tolerance curves and highly depends on the point on-wave (phase angle) of the dip initiation. Using the model, it can be explained that AC undervoltage relays are much more sensitive to voltage dips of e.g. 50% Urated than to short interruptions (0% Urated), caused by the magnetic behavior. The model takes into account the electrical, magnetic and mechanical system equations. An experimental set-up with a programmable power source as dipgenerator is build to validate the model. Finally, a complete weaving machine is represented to analyze the influence towards voltage dip immunity by adding an undervoltage protection relay

Learning Agent for a Heat-Pump Thermostat With a Set-Back Strategy Using Model-Free Reinforcement Learning

The conventional control paradigm for a heat pump with a less efficient auxiliary heating element is to keep its temperature set point constant during the day. This constant temperature set point ensures that the heat pump operates in its more efficient heat-pump mode and minimizes the risk of activating the less efficient auxiliary heating element. As an alternative to a constant set-point strategy, this paper proposes a learning agent for a thermostat with a set-back strategy. This set-back strategy relaxes the set-point temperature during convenient moments, e.g. when the occupants are not at home. Finding an optimal set-back strategy requires solving a sequential decision-making process under uncertainty, which presents two challenges. A first challenge is that for most residential buildings a description of the thermal characteristics of the building is unavailable and challenging to obtain. A second challenge is that the relevant information on the state, i.e. the building envelope, cannot be measured by the learning agent. In order to overcome these two challenges, our paper proposes an auto-encoder coupled with a batch reinforcement learning technique. The proposed approach is validated for two building types with different thermal characteristics for heating in the winter and cooling in the summer. The simulation results indicate that the proposed learning agent can reduce the energy consumption by 4-9% during 100 winter days and by 9-11% during 80 summer days compared to the conventional constant set-point strategyComment: Submitted to Energies - MDPI.co

Computer-supported laboratory for production-oriented electrotechnical systems

At the electrical engineering department of the K.U.Leuven an education research project was started in October 1997. The target is to develop a powerful environment to teach students to solve practice-oriented problems as they will encounter them in industry furtheron in their career. In order to give a wide use to the developed environment, a close collaboration has been established with three polytechnical engineering institutes. Self-dependence has to be stimulated by creating possibilities for real “hands-on experience”. Such an educational environment implicates time-problems, high investment costs and last but not least safety restrictions. The project contributes to the solution of these problems by using simulation- and softwareenvironments, without loosing the real hands-on feeling