Hardi Hoimoja

Residential electricity consumption and loads pattern analysis

This article analyses household electricity consumption in Estonia. Energy consumption of workday and holiday by loads is discussed. The final part describes the evaluation of feasibility of common investments

Analysis of Household Electricity Consumption Patterns and Economy of Water Heating Shifting and Saving Bulbs

Analysis of Household Electricity Consumption Patterns and Economy of Water Heating Shifting and Saving Bulbs This article analyses household electricity consumption based on an object in Estonia. Energy consumption of workday and holiday by loads (including high and low tariff energy consumption) is discussed. The final part describes the evaluation of profitability of common investments of consumption shifting and replacing inefficient devices with more efficient ones. Additionally it describes shifting problems and shifting equipment profitability in real-time tariff system.

Energy saving possibilities in the industrial robot IRB 1600 control

The paper presents the approaches for electric energy saving possibilities and electricity consumption characteristics in the modern industrial robots together with practical examples concerning robot programming and positioning. The paper is based on measurements, made in the laboratory of Tallinn University of Technology with an industrial robot IRB 1600.

Grid reactive power compensation by using electric vehicles

Along this paper, it will be presented how the Electric Vehicle (EV) bidirectional chargers can help the Distribution Grid. In addition to the battery charge and the Vehicle-to-Grid functions (V2G), the reactive power can be compensated according to an established reactive power reference. A three-phase bidirectional inverter connected with a DC link to a DC/DC bidirectional converter is utilized in the topology. The different modifications that are needed in the control algorithm and in the power stage are determined. Simulation results are shown, which prove how the reactive power is being compensated and the saturation of the reactive current is used to keep the power under predefined limits.

Survey of loss minimization methods in tram systems

This paper analyzes energy flows, conversions and losses in tram systems. Proposals for improvement of the efficiency of tram systems by the help of energy storage modules are described. In addition, such advanced methods of energy efficiency improvement as load sharing, real-time traffic management and Ecodriving are discussed.

An application - a web-based electrical drives laboratory: Objectives, structure and experiments

Modern information and communication technologies have changed the concept of laboratory experiment practice and learning the related theories. New terms like ¿e-learning¿, ¿remote laboratories¿, ¿virtual learning environments¿, etc. have emerged. To follow the mainstream and improve practical aspects of education, remotely controlled electrical drives laboratories have been designed at Tallinn University of Technology (TUT) where students can make experiments on real objects. Designing a remote laboratory presumes finding solutions to problems regarding technical, didactic, security and financial requirements as well as the integration into a wider distant learning environment. These requirements provide a basis for laboratory structures and methodology to be explained in this paper.

E-laboratory in the field of electrical drives

Modern information and communication technologies have changed the concept of conducting laboratory experiments and learning the theories behind them. New terms like ldquodistant learningrdquo, ldquoremote laboratoriesrdquo, ldquovirtual learning environmentsrdquo etc have emerged. To follow the mainstream and improve practical aspects of given education, the TUT has started designing its own remotely controlled electrical drives laboratories where students can make experiments on real objects. Designing a remote laboratory presumes finding solutions to problems regarding technical, didactic, security and financial requirements as well as the integration into a wider distant learning environment. These requirements give a basis for laboratory structures and methodology.

Slip control upgrades for light-rail electric traction drives

Many obsolete drives such as a rheostat, contactor or camshaft-contact controlled DC motor drives have often poor dynamic properties in insufficient adhesion conditions. Light-rail vehicles running in many cities already have switched-mode traction drives with thyristor-based or IGBT-based converters that often lack high quality slip, antilock or creep control. Switched-mode converter based multi-motor drives could be partially upgraded to microcontroller-based control. This paper presents and analyses some approaches to be used for performance, efficiency and safety improvement.

Power factor correction with vehicle-to-grid STATCOM implementation

The paper describes the connection of an electric vehicle to the utility grid and using the vehicle as a part of it. A new topology is presented and verified with experimental and simulation results. The experimental schematic allows to correct power factor of the grid, by using the part of the vehicle traction system. Basically it presents a portable STATCOM solution with a battery or hybrid energy storage system. By implementing the vehicle-to-grid conception, the EV/HEV become a part of the electric grid, bringing new features and benefits. Ability to use plug-in vehicles allows making the electric grid more “smart”. With more powerful vehicles, such as trucks or locomotives, the portable power solutions could be achieved. Results presented in paper are theoretical and experimental proof of upgrade possibilities of EV/HEV infrastructure and on-board architectures. There is no complex modernization required for plugging the EV/HEV to the grid. Moreover, the present powertrains can be updated.

A battery cell balancing method with linear mode bypass current control

A study of a novel control method for a battery cell equaliser, based on the shunting transistor method is presented. The method allows cell balancing in both battery operating modes, recharging and driving modes. To verify the applicability of the method, computer simulation was conducted analysing how the system balances during a driving period, by following a real current profile measured from a real REVAi driving. The obtained results show how at the end of the driving period the system is already balanced, allowing a subsequent high speed charge and avoiding a later equalisation stage. Finally, the integration of the balancing system into a higher level system, based on a multiport converter topology is discussed.