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Nowadays the amount of distributed generation (DG) units is increasing rapidly. Most dominant are combined heat and power (CHP) plants and wind turbines. At this moment, in most systems, there are no requirements defined for short-circuit behavior of such generators connected to the medium voltage grid. However in the future this situation will not be acceptable anymore, since with the present protection...
Photovoltaic (PV) penetration in the grid connected power system has been growing. Currently, PV electricity is usually directly sold back to the energy supplier at a fixed price nd subsidy. However, subsidies should always be a temporary policy, and will eventually be terminated. A question is raised whether grid-connected PV generation will be more beneficial by making biddings in power markets...
In the near future a significant amount of the consumed electrical energy will be generated by distributed generation (DG). Because of the small size these units are normally connected to the local distribution grid. Connection of DG changes the operation of the distribution grid. In order to minimize the effect of DG during grid disturbances some standards oblige immediate disconnection of DG-units...
This paper presents a novel control strategy to operate a low-voltage (LV) micro-grid in grid connected operation mode as well as autonomous operation mode. Depending on the inverter output impedance which is mainly resistive due to the LV cables a proper control strategy based on an unbalanced resistive droop approach is developed. The control strategy is verified by simulating fast changes of power...
Modern installations have become sensitive to power quality (PQ) related problems because more sophisticated devices with non-linear operating characteristics are often used there. On the contrary, most of these devices produce emissions that could decrease the PQ level of the network. It is becoming an increasing problem for the network operators to maintain good voltage quality because of the interactions...
A self-supporting residential area is seen as an alternative operational approach of power supply in low voltage (LV) networks. The intention of the new approach is to exploit the advantages of distributed generation (DG) and avoid the difficulties, that come with DG when implemented in the distribution network, by balancing power supply and demand efficiently in the area that can easily be controlled...
Due to the increase of distributed generation (DG) in the future it can become important to keep DG connected to the grid in order to maintain balance between consumed and generated electrical power. Keeping DG-units connected to the grid during a disturbance, the dynamic behavior of the DG-units becomes important. To guarantee after fault clearing stable operation of the DG-units, the protection...
Given the nature of electricity, every party connected to the power system influences voltage quality, which means that every party also should meet requirements. In this field, a sound coordination among technical standards (system-related, installation-related and product-related) is of paramount importance. Further, characteristics of currents (e.g. inrush currents, harmonic currents) should be...
Due to the increase of distributed generation (DG) in the future it can become important to keep DG connected to the grid in order to maintain the balance between consumed and generated electrical power. Keeping DG-units connected to the grid during a disturbance, the dynamic behavior of the DG-units becomes important. Protection schemes based on definite and inverse over-current are simulated and...
The transition from a conventional delivery system to a suitable robust distribution system is emerging to adapt with different possible scenarios of future development. This paper gives a particular vision of future grid with its main requirements. An investigation of suitable concepts and technologies which draw out attentions at the present has been carried out. They are discussed regarding mentioned...
Due to the liberalized energy market distributed generation, DG, is increasing. At this moment, most of the power produced by DG, is generated by CHP-plants and variable speed wind turbines. Integration of wind turbines have impact on several aspects of power systems such as power system stability, protection and power quality. This paper focusses on the effect of wind farms on power quality phenomena...
Excessive harmonic distortion has been reported in some distribution grids with a high number of photovoltaic inverters. In this paper, a simple model is introduced to describe the interaction between grid components and groups of inverters which can lead to amplification of harmonic voltages. The model is validated by using extensive measurements for several types of commercially available photovoltaic...
The increase of distributed power generation can result in equilibrium of local produced and consumed electrical energy. Power electronics and storage can transform networks in which such equilibrium exists into autonomously controlled networks. These networks remain part of the rest of the power grid. An example of such a network contains several MV feeders and their LV networks. One of the main...
Measurements during the last eight years show an increasing level of PIt, an indicator used for the flicker level. Furthermore, almost 50% of all technical customer complaints are flicker problems. The short-circuit power on the connection point is a very important parameter for controlling the fast voltage variations that lead to flicker. However, a high short circuit level can not be established...
Due to the increase of distributed generators (DG) in the public grid some parts, with high penetration of DGs, could be transformed into an autonomously operating micro grid. This paper will show how the grid of an existing Holyday park can be changed into an autonomous micro grid. An additional control system as well as additional storage systems and power electronics have to be implemented in order...
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