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There are many technical aspects and challenges at DG that are still not properly understood and addressed. Since most of these studies have to be carried out based on simulations, adequate static and dynamic models for DG units are required. The objective of this paper is the dynamic and static modeling of various DG technologies for stability analysis. These models allow studying systems with DGs...
An increased research on electric vehicles (EV) and plug-in hybrid electric vehicles (PHEV) deals with their flexible use in electric power grids. Several research projects on smart grids and electric mobility are now looking into realistic models representing the behavior of an EV during charging, including nonlinearities. In this work, modeling, simulation and testing of the demand profile of a...
Two-stage isolated converters for photovoltaic (PV) applications commonly employ a high-frequency transformer on the DC-DC side, submitting the DC-AC inverter switches to high voltages and forcing the use of IGBTs instead of low-voltage and low-loss MOSFETs. This paper shows the modeling, control and simulation of a single-phase full-bridge inverter with high-frequency transformer (HFT) that can be...
Based on experience with stability models for a variety of wind turbine generator (WTG) technologies, the paper describes numerical effects that are either a manifestation of modeling problems or may be inconsistent with real WTG behavior. Effects such as low-frequency and high-frequency oscillations, peaks in variables, noise, excessive sensitivity to numerical solution and questionable tripping...
Two oscillatory episodes took place in the Argentinean power system at 22:20 and 22:50, June 7th, 2008. The first one started when a 40 MVAr capacitors bank was disconnected and the second one started when a 500 kV line was disconnected. Both oscillatory episodes produced great variation of active and reactive power in several 330 kV and 500 kV power system nodes. At first sight, these oscillations...
This paper discusses a novel model, based on Activity-Based Costing, developed to analyze and predict energy usage in the manufacturing industry. In this approach, we have modified a cost management tool called Activity-Based Costing (ABC) to include environmental aspects along with costs metrics. A case study was performed on a General Motors (GM) manufacturing facility to evaluate Demand and Response...
Conventional transformers are typically heavy, bulky and expensive. Their size can be significantly reduced by increasing the frequency of operation which allows a higher utilization of the magnetic core. A model of a high-frequency distribution transformer using power electronics is presented in this paper. Its impact on a distribution system has been analyzed under different types of faults. Several...
This paper provides a review of the technical issues related to voltage flicker introduced by continuous operation of distributed wind generators. It outlines the impact of voltage flicker on distribution feeders and the sensitivity of lighting equipment to the introduced voltage changes. The paper details the flicker problems encountered upon the connection of wind power to distribution networks...
Results of a literature survey done on microgrids from conception to installation is presented. The purpose is to evaluate the current status, major obstacles and existing research efforts directed toward establishing functional microgrids within utility systems. This review paper covers technical issues associated with frequency control and re-synchronization associated with typical distributed energy...
Electric vehicle battery charger connected to the secondary distribution grid potentially raises power quality (PQ) concerns, thus the necessity of the analysis of its impact on the grid. Charger assembly consists of power electronic equipments that undergo fast switchings. It makes the device-level simulation very slow and impractical for PQ analysis and calls for an average model for the system...
Featured by its flexible and reliable operation microgrid has a great prospect for utilizing renewable resources. Electric vehicles can also help relieve the burden of energy supply and environment. Battery switch station (BSS) is an important solution to supply energy for electric vehicles. In this paper a new business model of microgrid-based BSS is proposed. According to battery and charger constraints,...
The power generation changes from conventional to renewable generators resulting in new challenges for the grid operators. One important aspect is reserve power. Due to fluctuating resources as wind and photovoltaics, the need for reserve power even increases. In this paper, it is studied, how tidal energy conversion systems can be controlled providing primary response. Thereby, the rotor speed is...
Grid level energy storage systems are a cornerstone of future power networks and smart grid development. Better energy storage systems are one of the last hurdles hindering the integration of renewable generation. There are currently many methods of implementing energy storage, ranging from pumped hydro storage to sodium-sulfur battery storage. All energy storage technologies share a common disadvantage...
Real-time electromagnetic transient simulation plays an important role in the planning, design, and operation of power systems. Inclusion of accurate and complicated models, such as the universal machine (UM) model and the universal line model (ULM), requires significant computational resources. This paper proposes a digital hardware emulation of the UM and the ULM for real-time electromagnetic transient...
Due to its unique topology, the Modular Multilevel STATCOM has many advantages but requires a sophisticated controller and puts higher requirements on simulation tools. To simulate the STATCOM in real-time is preferable because it enables hardware-in-the-loop test of the system in various scenarios including extreme fault conditions, which cannot be tested on a real STATCOM. This paper presents a...
Higher fault current levels due to additional interconnections to the power system have created an urgent need to limit fault current to manageable and safe values. Fault current limiters offer a unique solution to judiciously mitigate fault current, while maintaining the system's robustness, reliability, and stability. These circumstances prompted Southern California Edison (SCE) to provide a test...
There are rising challenges in installing High Voltage Direct Current (HVDC) to Tanzania power grid to significantly improve network controllability and system security. In addition, to expand generation capacity and to increase bulk power transmission capacity over long distances, feasibility study for installing HVDC in Tanzania power grid needs to be performed. Therefore, this paper presents the...
Solar PV (Photovoltaic) generators can be connected to a transmission system as a large scale installation or distributed across a distribution system close to load. Both types of solar PV projects utilize full converter model to connect to the grid, but may have different reactive power capabilities. The voltage and reactive power response of solar PV generators under both normal and outage conditions...
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