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Microgrids have been proposed in order to handle the impacts of Distributed Generators (DGs) and make conventional grids suitable for large scale deployments of distributed generation. However, the introduction of microgrids brings some challenges. Protection of a microgrid and its entities is one of them. Due to the existence of generators at all levels of the distribution system and two distinct...
The growing sophistication and complexity of power system control apparatus and systems plus the addition of new topological features such as distributed generation at the distribution level requires new test environments which can evaluate and optimise these systems prior to deployment in the real system. One such environment is described in this paper along with examples of its use in evaluating...
This paper presents the experience in loss of mains protections for distributed generation, during the start up of a synchronous generator of 12.5 MVA. Settings of ROCOFF and Vector Jump protective relaying are commented, as well as the good results obtained during test with utility company realized in a real islanding situation. ATP simulations were executed in several network configurations. Under...
The global demand for energy is increasing at a breathtaking pace. This sharp increase in world energy demand will require significant investment in new power generating capacity and grid infrastructure. Considering the present energy scenario and the degrading environmental conditions, distributed generation seems to be a promising option. Distributed Generation generally refers to small-scale electric...
The widespread of the Distributed Generation (DG) impacts the future development of modern electrical distribution systems that must to evolve towards Smart Grids. Fundamental topics of the Smart Grid context are the Distributed Voltage Automation and the Advanced Network Automation based on fast communication channels. In order to analyze the behavior of a network which evolves in Smart Grid, real...
Experience with connecting farm biogas generation to rural distribution feeders in Ontario has revealed several challenges with electrical protection. The biogas projects are small (<;500kW), synchronous, farm-based, and looking for an affordable protection solution involving the use of only low-voltage equipments. The utility feeders are generally at the 8.3kV and 12.5kV voltage levels, can involve...
The impact of distributed generation (DG) in a distribution network depends on the design of the protection system and the coordination between the different protective devices. This paper presents the main features of a library of protective devices implemented in an EMTP-type tool for power quality studies in distribution networks with distributed generation. The document discusses the present protection...
Distributed generation (DG) is gaining popularity in the United States and across the world. The Florida Public Service Commission recently passed rules encouraging the use of renewable resources. Integrating DG with the utility network poses challenges for anti-islanding schemes. These schemes detect islanding conditions and trip the DG. Fig. 1 shows a typical network configuration for DG installations...
Existing distribution networks have not been designed to accept extensive DG. The actual paradigm may change in the near future impelled by a word wide increasing of DG penetration in distribution grids. This paper presents the status and content of DG Spanish legislative documents. Fundamental considerations are first discussed, exclusively regarding the grid-interconnection requirement. This paper...
Experience with connecting farm biogas generation to rural distribution feeders has revealed that a particular costly barrier can be protection against unplanned islanding. When the size of the generation is small compared to the load on the feeder, the cost of anti-islanding protection is very small. However, once a certain size threshold is reached, alternative protection methods are required, and...
The capability of anti-islanding protection is a very important requirement for distributed generators (DG). A power line signaling based scheme for anti-islanding protection has been proposed in a companion paper. In the scheme, a signal generated by power electronics is injected from a central upstream location to the DG sites. The lack of a signal at the DG site indicates that the DG is islanded...
The impact of distributed generation (DG) on voltage sags in a distribution network depends on the design of the protection system and the coordination between the different protective devices. DG changes the radial nature of distribution systems and affects the performance of the protection system. This paper summarizes the impact of conventional synchronous machine-based DG on the present protection...
Protective relaying elements for wind farms, in particular, are sometimes characterized with different performance as compared with other ones used conventionally in power systems. Some factors including distributed generation concept, the own behavior of the Induction Generator (IG) and varying wind speed play basic roles for these situations. Current Limiting Fuses (CLFs) are commonly employed for...
A typical structure of electric power distribution networks is radial or a normally open-loop structure with a single supply path between the high-voltage supply substation and the end-consumers. The selectivity of a protection scheme for the radial network is generally achieved through time-coordination of different protection devices (relays, reclosers and fuses). However, future distribution networks...
This paper presents a methodology for integrated reliability evaluation of distribution and sub-transmission systems with the presence of distributed generation (DG) based on different energy sources. The methodology considers the possibility of DG connection at the High Voltage (HV) and Medium Voltage (MV) buses of the distribution substation, as well as along the MV distribution network. The uncertainty...
Distribution power system islanding will involve significant grid reconfiguration, especially if maximum flexibility of operation is to be achieved. Protection selectivity will be a challenge because of the associated changes in fault conditions, and is further complicated by distributed generator fault characteristics. This paper proposes a three-stage communication assisted protection selectivity...
Apart from the positive technical consequences, the increasing penetration of Distributed Generation (DG) units connected to the distribution network brings new requirements in the protection strategy. Grid disturbances at the transmission level can cause the unwanted disconnection of large amount of DG, leading to undesired power imbalances. This paper examines how transmission network faults can...
This paper deals with the protection system in distribution networks with distributed generation. It describes the dynamic influences of synchronous generators on the direction determination of protection relays during network disturbances. Therefore the dynamic behaviour of the measured electrical quantities during network disturbances is derived. A relay-model is implemented to study the behaviour...
As penetration of distributed generation (DG) increases at the distribution level, managing these systems effectively becomes increasingly challenging. One proposed way to manage these systems is through the adoption of microgrids. A microgrid is a distribution level network made of several loads and DG sources that operate as a single aggregate load or generation source. Microgrids can either operate...
This paper deals with a study regarding the impact of distributed generation in the Electric System of RGE - one of the electric utilities of Brazilpsilas Southern Region - specifically concerning the integration of small hydroelectric plants (SHP) to the power system. Control and protection systems parameters characteristics have been taken into account and field-tests data have been obtained for...
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