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The amount of photovoltaic (PV) generation that can be hosted by existing radial distribution feeders is inherently limited by system constraints and operating conditions. This paper discusses an analysis to determine the photovoltaic hosting capacity of an existing radial distribution feeder. This analysis also visualizes the location-dependence of hosting capacity, and tests the effectiveness of...
Most utilities use a standard small generator interconnection procedure (SGIP) process that includes a screen for placing potential PV interconnection requests on a fast track that do not require more detailed study. One common screening threshold is the 15% of peak load screen that fast tracks PV below a certain size. This paper performs a technical evaluation of the screen compared to a large number...
Future power distribution systems are expected to have large number of scale smart measuring devices and distributed generation (DG) units which would require real-time network management. Integration of single-phase DG and advanced metering infrastructure (AMI) technologies will add further complexity to the power distribution system which is inherently unbalanced. In order to alleviate the negative...
The connection of distributed generation (DG) to weak distribution networks is likely to cause voltage rise problems. At present, the voltage rise is usually mitigated by reinforcing the network but as the penetration level of DG increases also active voltage control methods need to be taken into use. Active voltage control has been a subject of extensive research in the past decade but the number...
Installation of a large number of small sources called distributed generation creates many problems in proper control of national (and European) power grid. At the same time new technologies especially power electronics and measurement data computing associated with smart grid allows to use better and conscious these distributed sources. This paper describes what problems the distributed generation...
Distributed generation causes new challenges in medium voltage networks. Especially voltage stability is becoming an issue. Conventional planning measures, like network expansion, can be used to address this challenge, but they should be planned with great care due to their high costs. Power factor control of distributed generators is an alternative to such measures. Therefore it should also be considered...
Distributed operation of microgrid architectures consists of energy management, power management, power electronics management, and fault detection and recovery. Centralized control of microgrids may be conceptually and practically infeasible due to questions of reliability and ownership. A Distributed Operating System architecture is proposed to manage power and computational resources within a smart...
An overview of existing power loss reduction calculation methods, varying in complexity and accuracy, is undertaken. Their strengths and weaknesses are compared. Additionally, an improvement is suggested as the negative correlation between wind generation and system load is underscored. A case study is performed to determine the performance of the suggested improvement. Results showed that considering...
A key feature of microgrid concept is the ability to operate in islanding mode. Under such operating scenario, the distributed generators within microgrid should form a high quality voltage supply for the load to sustain its normal operation. Power converters, the interface of renewable sources and energy storage systems, are an important component of microgrids. The size and the number of the power...
The National Renewable Energy Laboratory (NREL) conducts a variety of research in the area of hybrid power system integration and microgrids. NREL is studying hybrid (stand-alone) power systems incorporating photovoltaic power in the United States and assessing the characteristics and status of government-installed hybrid systems greater than 2 kW over the last 30 years. This research provides information...
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...
The amount of distributed generators in power distribution systems is evermore increasing, and the potential benefits and drawbacks are becoming clearer. The optimal management of Distributed Energy Resources (DER) in microgrids is essential to guarantee their best exploitation. Optimal operation allows to maximize their benefits, such as reduction of network energy losses, reduction of carbon emissions...
Renewable energy sources such as wind and photovoltaics (PV) have great potential for reducing fuel consumption in diesel-based mini-grids in remote communities. However, the fluctuating and intermittent nature of these sources can give rise to a number of problems in mini-grids with high penetration of non-dispatchable renewables with reduced or non-existent storage units. This paper proposes the...
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...
Summary form only given. The positive feedback-based anti-islanding scheme has become a common anti-islanding protection technique for inverter-based distributed generators (DGs). This paper investigates the scheme's impact on the small-signal stability of multiple inverter-based DGs installed in power distribution systems during grid-connected operation. The interactions among multiple-DGs due to...
The paper is intended to propose an optimal control strategy for autonomous micro-grids that focuses on the possibility to minimize the overall micro-grid operating cost, borne by the micro-grid operator in order to provide power distribution to customers, while minimizing the pollutants emissions and assuming that all the power made available by the renewable energy sources is injected into the micro-grid...
With development of sophisticated renewable energy technologies, paradigm shift of both power generation and power distribution is happening and happening fast. Compared with conventional power generation, renewable energy sources are installed to the utility grid in a distributed fashion, which may result in various power quality issues, such as unbalance voltage and harmonic voltage resonance. An...
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...
The state of the art in distribution system analysis is examined with respect to distributed generation (DG). The types of analysis required for DG evaluation are described briefly. Then 14 challenges with respect to this subject are described and areas ripe for further research are pointed out.
The DC micro grid has been used for power distribution in recent years. The wind turbine is one of the most comprehensively used power source in this kind of grid. It is connected to the DC grid by the AC/DC converter. In this paper, converter design methods are proposed for four types of wind turbine systems, the variable speed induction generation system, the fixed speed induction generation system,...
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