A novel on-line UPS with universal filtering capabilities

Kamran, F.; Habetler, T.G.

doi:10.1109/63.668099

Cited by 113 publications

(29 citation statements)

References 6 publications

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“…possible as in series-parallel or delta conversion line-interactive UPS [3]- [6] at the expense of lower efficiency and extra size and cost due to the use of extra inverter and bulky transformer. However, this topology is still more efficient than classical on-line double conversion UPS because the complementary inverter has only to supply 10% to 20% of the UPS nominal power [7].…”

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Line-Interactive UPS for Microgrids

Abusara

Guerrero

Sharkh

2014

IEEE Trans. Ind. Electron.

162

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Abstract-Line interactive Uninterruptable Power Supply (UPS) systems are good candidates for providing energy storage within a microgrid to help improve its reliability, economy and efficiency. In grid-connected mode, power can be imported from the grid by the UPS to charge its battery. Power can also be exported when required, e.g., when the tariffs are advantageous. In stand-alone mode, the UPS supplies local distributed loads in parallel with other sources. In this paper, a line interactive UPS and its control system are presented and discussed. Power flow is controlled using the frequency and voltage drooping technique to ensure seamless transfer between grid-connected and stand-alone parallel modes of operation. The drooping coefficients are chosen to limit the energy imported by the USP when re-connecting to the grid and to give good transient response. Experimental results of a microgrid consisting of two 60kW line interactive UPS systems are provided to validate the design. Index Terms-Line interactive UPS, microgird, distributed generation. I. INTRODUCTIONO INCREASE reliability, energy storage systems within a microgrid are essential. Energy is stored while in grid-connected mode, when the microgrid's Distributed Generation (DG) systems produce excess power, to be used later to supply critical loads during power outages. In stand-alone mode, they can be used to boost the power supplied by the microgrid if the DG systems cannot meet the expected level of power. To meet these demands, the energy storage system needs to be able to work in grid-connected and stand-alone modes. In the latter mode of operation, the system needs to operate in parallel with other DG systems to meet the variable power demand of the load. More importantly, it needs to switch seamlessly between the two modes.Line interactive UPS systems are good candidates for providing energy storage within microgrids as they can be connected in parallel with both the main grid and local load. The classical topology of line interactive UPS systems [1], [2] is simpler, cheaper, more efficient and more reliable than the on-line double conversion UPS. This topology, however, does not provide voltage regulation to the load. Voltage regulation is M. A. Abusara was with Bowman Power Group, UK and now he is with the Renewable Energy Research Group, University of Exeter, Cornwall Campus, Penryn, TR10 9EZ, U.K. (e-mail: m.abusara@exeter.ac.uk).J. M. Guerrero is with the Department of Energy Technology, Aalborg University, 9220 Aalborg, Denmark (e-mail: joz@et.aau.dk).S. M. Sharkh is with the Electro-Mechanical Engineering Research Group, University of Southampton, Highfield Campus, Southampton, SO17 1BJ, U.K. (e-mail: suleiman@soton.ac.uk).possible as in series-parallel or delta conversion line-interactive UPS [3]-[6] at the expense of lower efficiency and extra size and cost due to the use of extra inverter and bulky transformer. However, this topology is still more efficient than classical on-line double conversion UPS because the complementary inverte...

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confidence: 99%

“…The active and reactive power flow between the UPS unit and the grid can be shown to be given by 3 sin…”

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confidence: 99%

Line-Interactive UPS for Microgrids

Abusara

Guerrero

Sharkh

2014

IEEE Trans. Ind. Electron.

162

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“…Thereby, active filter topologies have been used to compensate neutral harmonic currents (Quinn et al, 1992;Quinn et al, 1993;Thomas el al., 1996). Uninterruptible power supply (UPS) systems have enabled the improvement of power source quality, providing clean and uninterruptible power to critical loads such as industrial process controls, computers, medical equipment, data communication systems, and protection against power supply disturbances or interruptions (Oliveira da Silva et al, 2001;Kamran et al, 1995;Jeon et al, 1997, Cheung et al, 1996Lin et al, 1993). In (Lin et al, 1993) a threephase parallel processing UPS has been presented with harmonic and reactive power compensation, but the output voltages and the input currents cannot be controlled simultaneously.…”

Section: Introductionmentioning

confidence: 99%

“…In (Lin et al, 1993) a threephase parallel processing UPS has been presented with harmonic and reactive power compensation, but the output voltages and the input currents cannot be controlled simultaneously. Three-phase UPS systems with seriesparallel active power-line conditioning have been proposed using different control strategies (Oliveira da Silva et al, 2001;Kamran et al, 1995). In (Kamran et al, 1995) the three-phase UPS system was employed for three-wire systems, and in (Oliveira da Silva et al, 2001), albeit it can be employed for three-wire and four-wire systems, the UPS was used to feed a non-linear load composed by a threephase non-controlled rectifier, in which neutral currents do not exist.…”

Section: Introductionmentioning

confidence: 99%

“…Three-phase UPS systems with seriesparallel active power-line conditioning have been proposed using different control strategies (Oliveira da Silva et al, 2001;Kamran et al, 1995). In (Kamran et al, 1995) the three-phase UPS system was employed for three-wire systems, and in (Oliveira da Silva et al, 2001), albeit it can be employed for three-wire and four-wire systems, the UPS was used to feed a non-linear load composed by a threephase non-controlled rectifier, in which neutral currents do not exist. This paper presents a three-phase line-interactive UPS system with active series-parallel power-line conditioning capabilities using an SRF-based controller, for three-wire and four-wire systems in which three single-phase loads are fed.…”

Section: Introductionmentioning

confidence: 99%

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