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The answer to global problems challenging energy sector was to use more efficiently local alternative (non-conventional fossil fuel or renewable) energy resources. In power systems, the use of renewable energy (RE) based distributed generation (DG) has increased considerably all over the world; the presence of DG units at distribution voltage level determines the transition from traditional passive...
The trend of generating power at distribution voltage level, known as distributed generation, is thought to be the future of energy generation, as it is environmental friendly and brings many advantages especially for electricity consumers. The paper presents the study of a real Romanian weak distribution network; the microgrid, comprising a transformer and the associated feeders, supplies single-...
The paper tackles an issue that concerns both the suppliers and consumers of electric energy: power losses in distribution power networks. On the other hand, the harmonic pollution in power networks has become a permanent issue, and in many situations along with the unbalance determines a steady state that is unbalanced and non-sinusoidal. In the design and exploitation stage the power engineers calculate...
Modeling of electrical networks elements (electric lines and transformers) during steady state operation is based on the following suppositions: a) supply voltage system is balanced; b) currents are sinusoidal and form a balanced system of phasors; c) network parameters are constant; d) running state is permanent and stationary. These hypotheses can be correctly applied for single-phase and positive...
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...
This paper deals with the use of a set of indicators defined within a symmetrical component-based framework to study the characteristics of the Steinmetz compensation circuit in the presence of waveform distortion. The Steinmetz circuit is applied to obtain balanced currents in a three-phase system supplying a single-phase load. The circuit is analyzed without and with harmonic distortion of the supply...
The paper presents a new technique to mitigate the voltage unbalance in LV distribution grids using distributed generation (DG). Usually, public LV networks supply many single phase consumers; in this case, the unbalanced line currents produce the unbalance of standard symmetrical supply voltage system. This voltage system negatively influences other three-phase loads operating in the same system,...
Daylighting has become a more important feature of recent constructions due to the sustainable design movement, and suitable lighting controls provide building operators with the means to manage the way lighting energy is used in buildings more efficiently. Unfortunately, classic control systems, based on continuous dimming present some difficulties to adjust their performances to the rapid changes...
Power quality has become an important issue for electric power engineering. Nowadays, the distribution electric networks have unbalanced operating regimes, mainly produced by the great number of single-phase loads. Unbalanced line currents produce unbalanced voltage drops on the three phases of the supply system. Consequently, the voltage system within the supply network will become unbalanced. Voltage...
The sustainable development concept has revived the interest for daylighting as any day lit area has very promising energy-saving opportunities; according to some specialists, the potential energy savings can exceed 40%. However, daylight is a dynamic source of lighting, i.e. the illuminance from the sky is not constant, and the variations in daylight can be quite large depending on season, location...
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