Transformerless three-phase on-line UPS with high performance

Kim, E.-H.; Kwon, Jung-Min; Kwon, Bong-Hwan

doi:10.1049/iet-pel:20070422

Cited by 38 publications

(16 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The parallel operation of multiple Voltage Source Converters (VSC) was widely investigated by researchers, with the aim to realize Uninterruptible Power Supply (UPS) [8] or self-sustaining micro-grids. In case of micro-grid, the grid stability must be guaranteed by the control strategy of the connected VSCs, that have to cooperate for a smart managing of the distributed energies sources; a feature that is not envisaged by existing grid-connected converters.…”

Section: State Of Art Of Micro-grid Conceptsmentioning

confidence: 99%

Analysis of the frequency‐based control of a master/slave micro‐grid

Buticchi

Carne

Barater

et al. 2016

IET Renewable Power Generation

View full text Add to dashboard Cite

Renewable energy penetration in the low-voltage grid faces several limitations due to the current grid topology. Master/slave micro-grids could help solving these issues, by offering additional services to the grid, such as the power management of the distributed power energy sources.In some cases, the power produced by the distributed energy sources exceeds the local consumption of the low-voltage grid. The consequent reverse power flow can be either dangerous (for the medium voltage) or impossible (for a micro-grid with limited storage). The droop characteristic of commercial inverter can be exploited to avoid this behavior. However stability problems can arise due to a low phase-locked-loop (PLL) bandwidth. This paper investigates the stability of this solution depending on the bandwidth of the PLL of the distributed power generation sources. I. INTRODUCTIONThe distributed power generation systems (DPGS) became more and more important over the last few years. Their increasing popularity has been driven by the use of renewable energy sources and the rising costs of the energy distribution, leading to modifications of the electric grid. Among the renewable energy sources employed in this framework, photovoltaic (PV) is receiving a great attention. PV systems can be divided into island-grid (or stand-alone), where the converters supply local loads, and grid-connected, where the power produced by the panels is transferred to the electrical grid.In general, grid-connected systems have been preferred to stand-alone ones, since the mains can compensate the energy production oscillations due to the variable nature of the PV source. As a consequence a great number of distributed low power sources have been connected to the LV grid in the last years, leading in some case to grid stability problem such as: transformer reverse power flow, voltage rise, unexpected islanding operations, sympathetic tripping, etc.[1], [2].To partially mitigate these problems, standards have recently imposed to grid-connected inverters to vary their output power in function of the instantaneous value of grid voltage and frequency (CEI-021 [3]). In fact, when in a LV grid the amount of energy from installed distributed sources is comparable to the loads' consumption, particular care must be taken to manage conditions of high imbalance between power generation and energy demand. Therefore, grid-connected systems have to limit their output power to face the cases of low local consumption. For PV systems an example is that of summer months in south European regions, when to an high PV energy production may not correspond an equivalent local demand [4]. This paper investigates the stability of a micro-grid where a frequency control is adopted to manage the power balance [5]- [7]. The basic assumption is that the frequency of the micro-grid can be changed (fully-decentralized micro-grid or smart-transformer micro-grid) to interact with the distributed sources. The novelty of the proposed approach is that standard current-controlled grid-connected ...

show abstract

Section: State Of Art Of Micro-grid Conceptsmentioning

confidence: 99%

Analysis of the frequency‐based control of a master/slave micro‐grid

Buticchi

Carne

Barater

et al. 2016

IET Renewable Power Generation

View full text Add to dashboard Cite

show abstract

“…Three-phase UPSs found commercially and in scientific work are based, with slight variations, on a classical topology employing two-level PWM converters [4][5][6][7]. Despite being able to maintain power quality on both the mains side and the load side, its efficiency is limited due to the large switching losses in the electronic switches.…”

Section: Introductionmentioning

confidence: 99%

Design of an Highly Efficient AC-DC-AC Three-Phase Converter Using SiC for UPS Applications

2018

View full text Add to dashboard Cite

With the constant increase of energy consumption in the world, the efficiency of systems and equipment is becoming more important. Uninterruptible Power Supply (UPS) is an equipment that provides safe and reliable supply for critical load systems, that is, systems where a supply interruption can lead to economical or even human losses. The Double Conversion UPS is the most complete UPS class in terms of load protection, regulation, performance, and reliability, however, it has lower efficiency and higher cost because of its high number of power converters. Silicon Carbide devices are emerging as an opportunity to construct power converters with higher efficiency and higher power density. The main purpose of this work is to design a three-phase AC-DC-AC converter using Silicon Carbide for Double Conversion UPS applications. The aim is to maximize efficiency and minimize volume and mass. The methodologies to size and choose the main hardware components are described in detail. Experimental results obtained with the prototype prove the high efficiency and high power density achievable with Silicon Carbide Metal Oxide Semiconductor Field Effect Transistor (MOSFETs).

show abstract

“…Generally, the CM component suppression strategies are based on the converter architecture [10]- [12], modulation strategy [13], [14], and CM filter [15], [16] [19], the wye connection point of the AC side filter capacitors [13], and connection of the DC-link capacitor midpoint and wye point of AC filter capacitors [20], [21], were proposed to be used as neutral line for three-leg converter. The neutral line can also be supplied by an additional leg [13], [22].…”

Section: Introductionmentioning

confidence: 99%

“…A passive CM filter can be composed of a CM inductor [23], [24], AC side bypass LRC filter [7], [20], [25] and DC-side bypass filter [26]. For the CM inductor filter, when the converter is voltage control, the voltage quality is determined by the CM current, and consequently, in three-leg converter four-wire system, the filter is non influential when the AC grid is no loads or with light loads, as it will be explained in the following.…”

Section: Introductionmentioning

confidence: 99%