Environment and Electrical Engineering (EEEIC), 2010 9th International Conference on

Although the environmental issues are becoming more perceptive in the public opinion as well as the awareness and understanding from the governments and the stakeholders, the proposal of a taxation shift focus from labour productivity to resources and energy usage (as the environmental tax reform) effect is still to be proven. This paper gather information to support decision making of all stakeholders involved in making markets work for improvements in resource exploitation and environment (sustainability), innovation and competitiveness (economy) and employment (social welfare). View full abstract»

The paper describes some trends in electric power industry in Germany in view of potential competition in electricity generation. Some conclusions on the possible trends and risks are made. View full abstract»

This paper examines the role of renewable distributed generation in the context of energy security, using Poland as an example. View full abstract»

Modular inverters are suitable for grid integration of renewable power such as solar and wind with reduced power losses, improved power quality, and high reliability. Also, it allows the integration of renewable energy to the grid without the need for interfacing transformer. This paper investigates the dynamics behaviour of a five-level modular inverter connected to the grid when subjected to major transient events, such as loss of major load and AC faults. The paper uses the results obtained from the simulations conducted in Matlab-Simulink to demonstrate the resiliency of the modular inverters to major transient events. View full abstract»

In this paper, a novel and fast method for fault section identification in compensated series transmission lines based on the high frequency traveling wave has been proposed. The method uses the relation of magnitude and polarity between wavefronts of high frequency travelling waves induced by fault. For accurately and fast extracting polarity and magnitude of travelling wave, wavelet transform and modulus maxima are used. Validation of this method is carried out by PSCAD/EMTP and MATLAB simulations for typical 400 kV power system faults. Simulation results reveal high performance of the method. View full abstract»

Design and optimization of a hybrid power system is site specific. It depends mainly on the available of renewable sources and the load demand. Sizing of the components has significant influence on the system performance. Due to the weather dependant nature of renewable energy sources, a fossil fuel based constant-speed generator is an essential component in traditional hybrid power systems. However, the efficiency of this generator especially at light loads can be significantly improved by adopting a variable-speed operation. This paper presents a combined sizing and operation control programme that can be used with both traditional constant-speed generators as well as novel variable-speed generators. The programme uses the polynomial curve fitting for the fuel consumption characteristics of variable-speed generators. The accuracy of the calculations is verified by comparing with a well known renewable energy optimization package. View full abstract»

HYSTERESIS motors are self-starting synchronous motors that take advantage of the hysteresis characteristics of the magnetic materials. Robust structure, flat speed-torque characteristics, smooth operation and constant low starting current are the outstanding specifications of these machines. Nevertheless, low efficiency and low power factor are among the disadvantages of common hysteresis motors. Very recently, Coreless Dual Discs Hysteresis Motor (CDDHM) has been introduced to enhance the efficiency of the hysteresis motors. So far, design algorithm and impacts of the design parameters on the performance of the CDDHM have not been fully investigated. Conventional optimization algorithms commonly are employed to solve the linear problems and those are not easily applicable for design optimization of a hysteresis machine with a complicated, nonlinear and multi values model. These difficulties are mainly due to the fact that the output torque of a flat hysteresis motor is proportionally related to area of the hysteresis loops on volume of the rotor discs. This paper presents an initial design algorithm and then describes application of a genetic algorithm-based approach with all details solving successfully the maximum efficiency optimization problem of a CDDHM. The output power and efficiency obtained from theory is shown to be in good agreement with the measured values. View full abstract»

It was found that generation processes could be described in terms of a voltage parameter V10 and of a field parameter E10. In this paper a new electric field distribution E(x) in a space between the two electrodes is presented. Using a concept for allowed electron- hole transitions, the effect of the light on the electric field distribution and on the shape of current - voltage characteristic is determined. For a space charge distribution some new singular solutions are obtained. Also, a new negative resistance is determined. View full abstract»

The MCA8 supportive software was developed mainly for the purpose of the support of multi-criteria decision making in the field of electrical power engineering. The MCA8 offers six methods of multi-criteria analysis (MCA) for solving extensive multi-criteria decision making tasks. We can use this MCA8 software for comparison of the systems for storage of electrical energy gained from non-regulated renewable energy sources (RES). The problem with these sources, including wind and photovoltaic power plants, is their back-up. Storing the energy from these sources is an important precondition for the uninterrupted supply of electricity to consumers. View full abstract»

The large peak to average power ratio (PAPR) is widely believed as one of the most critical problem for OFDM systems and a lot of methods have been proposed to reduce PAPR. A new PAPR reduction method for the OFDM system by combining both clipping method and time domain statistical method has been proposed and investigated. The approach is very flexible and can work with arbitrary number of sub-carries without restriction on the type of modulation applied on them. Furthermore, there is no need for side information, and no loss in terms of data rate. Simulation results show that more than 6dB reduction in the PAPR value can be achieved using the proposed method. View full abstract»

The conducting silicon rubber was highly stressed by means of voltage impulses in order to investigate the electric behaviour of this material. A specific value of electric load-carrying capacity was observed. Below this value material exhibits resistive character and constant electrical properties, however, above this value the material is damaged and can not be used in practical application. The explanation of the cause of damage and the influence of positive temperature coefficient (PTC-effects) has been proposed. View full abstract»

In this paper the voltage division over the interrupter units of a high voltage circuit breaker without grading capacitors is investigated. A method of measuring capacitances and earth capacitances is presented. High voltage tests were made. View full abstract»

The paper briefly summarizes the classification of three-phase electric systems and explains the Fortescue theory. It also includes a description of measuring apparatus, created with the use of virtual instrumentation, which was used for measurements at a railway transformer substation. The paper includes the results of unbalance measurements at the transformer substation of Railway Infrastructure Administration. View full abstract»

The thermally stimulated current discharge method (TSDC) and deep level transient spectroscopy (DLTS) have been used to study defects in indium doped Cd_0.91Mn_0.09Te. The measurements were performed within a temperature range of 80K-300K. The TSDC measurements reveal the presence of six traps. For the dominant traps, activation energies of 0.11 eV, 0.25 eV, 0.27 eV and 0.4eV were obtained. DLTS studies yield the presence of five majority electron traps. The activation energy was determined unambiguously for three out of the observed traps as 0.25eV, 0.27eV and 0.39eV. The agreement among the activation energies obtained by both methods is satisfactory implying the complementary character of both techniques. View full abstract»

The insulated oil is used in electricity as a medium for cooling and dielectric in transformers, for cooling and extinguishing the arc in switches, etc. Operating conditions of electrical equipment affect properties of insulated oil causing their aging. Some aspects of electromagnetic field influence on the oxidation of insulating oil are listed below. View full abstract»

The paper investigates the appliance of an optimization routine to establish best offshore windfarm layout, in terms of chosen cost function. An introduction to windfarm layout problem is given. Wake effect, turbine spacing and infarm wind distribution are covered. Sample Matlab program results are provided and commented on. View full abstract»

In wireless sensor networks where the nodes are equipped with limited energy sources, energy consumption is a crucial parameter of each part of a node activity. This paper deals with node localization based on received signal strength (RSS). The signal power at receiving node is influenced by several stochastic factors. To eliminate so called RSS uncertainty, several measurements of signal strength must be performed to get the value to be used in distance calculation. Multiple packet transmission means bigger energy consumption during distance estimation. This paper presents the analysis of energy consumption during the signal strength measurement with respect to the accuracy of RSS estimation. View full abstract»

The installation of distributed generation (DG) introduces challenges to distribution systems operation. The distribution network operator needs to schedule DG outputs considering some constraints, such as DG characteristics, reactive power control mode of generators, automatic voltage regulation, compensator and power quality standard, etc. Based on an optimal power flow model, this paper proposes a dispatch model for DG embedded distribution systems. The model is proposed basing on energy prices, weather forecasting and load forecasting. The objective is to minimize the electricity supply cost of the distribution company. The proposed model is tested in the 33-buse system. The results show that DisCo's cost and losses of the distribution system can be reduced by enhancing system operation flexibility. View full abstract»

This paper proposes a hybrid exciter for the standalone wind turbine driven induction generator. It consists of one set of fixed capacitor bank and a voltage source inverter connected in parallel at the stator terminals of the generator. The inverter provides the necessary variable component of lagging reactive power to the induction generator so that nominal output voltage is obtained even at lower speeds and higher loads. The dc bus voltage of inverter is maintained using the combination of a bidirectional dc-dc converter and a battery. The battery is used as a complementary energy source to minimise the impact of the fluctuations in the wind power on the connected load. The scheme has reduced control complexity because the inverter is operated with a fixed PWM and hence the control is restricted mainly to switching the bi-directional dc-dc converter. There is no need for a position or a speed sensor. The complete system is modeled and simulated in the MATLAB/Simulink environment. Simulation results validate the proposed power generation scheme as a viable alternative for remote areas. View full abstract»

Cordoba is an inland province of southern Spain. This paper presents the quantity of power that will be necessary to install for covering the electrical consumption of Cordoba's population. Multicriteria has been the followed method with selection of criteria and options for the new and renewable energy technologies assessment based on the analysis and synthesis of parameters under the information deficiency method. View full abstract»

Partial shading of photovoltaic (PV) modules can affect a wide variety of plants ranging from utility-sized solar trackers to residential building-integrated PV, resulting in lower energy production yields. The traditional series-parallel interconnection scheme of solar arrays is sensitive to disparate solar irradiation levels on modules of the plant. By using alternative topologies, the effects of unavoidable partial shade can be decreased. In this paper, module interconnections inside a PV array are modified to reduce mismatch losses caused by partial shading. Results from a measurement campaign on a 2.2kW plant carried out on Jaén University's campus using various interconnection schemes are presented. View full abstract»