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The following topics are dealt with : power quality parameter; power distribution reliability; power system modeling and simulation; electricity market; distributed generation interconnection; electromagnetic compatibility; energy efficiency; power grids; power quality measurement; and electrical power converter.
Different approaches to limiting the levels of electromagnetic pollution in the electrical networks are discussed. Overview of the main principles used as basis for IEC EMC standards, CIS Standard 13109-97 and IEEE Standard 519-1992 is presented. Time-varying nature of the electromagnetic processes behavior in power systems is highlighted and expressions for power quality indices based on spectral...
The recent awareness about fossil fuels and the environment has arisen more sustainable alternatives regarding means of transport. The first alternative of green transport has been hybrid vehicles. This kind of vehicles reduces significantly the CO2 emission but not totally. Nowadays, the current trend is the utilization of a unique motor for vehicle. i.e. an electrical motor. It seems that the electric...
This paper presents the domains where subharmonic ferroresonant oscillations can occur. To calculate these domains the mathematical modeling of voltage transformer inductance is used. The proposed domains can be applied successfully to avoid subharmonic ferroresonance in high-voltage electrical substations.
Resonance is a phenomenon that occurs in electrical power systems of all voltage levels. The necessary and sufficient conditions are the framework of scenarios where resonance develops. The capacitors of electrical networks are linear elements. Nevertheless, the inductances may be both type: linear and nonlinear (with ferromagnetic core). Only one resonance steady state may appear in a linear circuit...
Nowadays, a controlled electric drives (ED) are widely used in different fields of industry. Well-known that about 10 per cent of all electric power is consumed by controlled ED. In an asynchronous drive with valve cascade converter-asynchronous-valve cascade (AVC), the smooth start and speed control of the phase-wound rotor motor are realised. However, the frequency converter as a part of electric...
Power factor correction of the facilities requires a design that is able to compensate for reactive power demand as well as for harmonic currents injected by the equipment into power supply system. In the circumstances many of industrial supply systems consist of a combination of tuned filters and a capacitor bank. Investigation of interaction between capacitor banks and harmonic filters within an...
In the paper a model of a digital flickermeter and results of simulation tests have been presented. Conditions of the digital flickermeter construction as well as new methods for improving the Pst calculation have been described.
This paper focus on the problem of locating single-phase faults in mixed distribution electric systems, with overhead lines and underground cables, using voltage and current measurements at the sending-end and sequence model of the network. Since calculating series impedance for underground cables is not as simple as in the case of overhead lines, the paper proposes a methodology to obtain an estimation...
The trend towards higher line kVA ratings and the permanently increase of the short-circuit contribution to a system leads to unacceptable high short-circuit currents. Reliable and economic protection against these high short-circuit currents is provided by the IS-limiter. In case of a short-circuit-fault this fast-acting switching device triggers a small charge to open the main conductor, which is...
Operation of thyristor-controlled locomotives in the single-phase industrial AC electrified railway systems causes overvoltages and power quality degradation on the traction substation. These factors affect substation electrical equipment significantly and premature failure may be occurred due to insulation breakdown. For example, the frequently occurring insulation breakdowns of electrical equipment...
Interharmonics represent those electrical signals whose frequencies are not integer multiples of the supply fundamental frequency. They correspond to electrical components that are not synchronized with the systems fundamental frequency; due to this fact, they have a more destructive impact than harmonics on the elements of the power system. International organizations like IEC and IEEE International...
Power quality distortions such as voltage unbalance and harmonics are usually present in power supply systems (PSS) simultaneously. These distortions have effect upon the most consumers' and PPS' equipments in the similar way and lead to the power losses rise, overheating and reduction of operation life of electrical equipments. Meanwhile electromagnetic compatibility (EMC) standards set limits of...
The paper deals with analysis of electric power quality ratings in installation of an arc furnace with a battery of passive LC filters and a tracking static VAr compensation. On the basis of recorded waveforms of voltages and currents in individual circuits of an internal autonomous power network during cast process we evaluated waveforms of the electric power. Experiments were conducted for the on...
This paper presents calculation of the apparent power of electric circuits with switching elements and various loads in single-phase systems. Attention is paid to the difference between such fundamental concepts as ldquothe electromotive force (EMF) of a voltage sourcerdquo and ldquothe input voltage of an electric circuitrdquo causing the electric current to flow. On that ground, an analysis of apparent...
The development of a power quality (PQ) benchmarking model is presented. Practical results are discussed to motivate the need of adding value to recorded PQ data by means of benchmarking PQ performance. The importance, science and methodology of cleaning up recorded sag and swell data per site and per region is demonstrated. Benchmarking of voltage distortion, unbalance and magnitude regulation is...
One of the key objectives of DERlab Network of Excellence is the development of internationally acceptable test and certification procedures for distributed energy resources (DER)-components and systems connection and operation, which could be proposed to European standardisation bodies. Interconnection of inverters to the electrical grid has been identified as a key issue for the wide integration...
Growing competition on goods and utilities markets forces dramatic search for production costs reductions. Electricity costs are the principle cost components in steel industry. In many cases, it is even the main cost of the whole production. One of the main way of the electricity cost minimization is hourly load forecasting. In this paper the algorithm of hourly electricity load forecasting for Polish...
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