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A modular UPS system is generally presented as having a much higher level of availability than a monolithic, double conversion, on-line UPS system. However, there are different types of modular UPS systems available on the market, with varying degrees of reliability and availability. To represent the strengths and weaknesses of each architecture and accurately compare them to one another, a detailed...
This paper describes the structure, control and performance analysis of an alternative configuration of a low cost three-phase transformerless online UPS. The proposed UPS avoids the use of galvanic isolation and consists of a half-bridge rectifier, a battery bank, a half-bridge inverter, a split DC bus and an auxiliary circuit. The auxiliary circuit is composed of an inductor and a small rating switching...
Reliability is an essential role in electricity business as the demand is rising rapidly. Recently, Microgrid technologies have been implemented in the traditional centralized grid in order to mitigate the power disturbance. Many researchers have proposed different configurations of the Microgrid with a constitution of renewable energy sources such as Photovoltaic Plant, Wind Plant and back up supply...
This paper approaches the implementation of a control strategy with communication for three-phase four-wire VSI parallel connected, which is based on distributed control. The paper presents details of implementation of one control strategy that employs two loops, one voltage control and one parallelism control, all system is done on instantaneous values and the parallelism control shares only a voltage...
UPS provides emergency power when utility power is not available, so the reliability of UPS is more important than inverter drive systems. In this paper, a fault diagnosis system for UPS is proposed using FFT frequency analysis of output current of inverter side of UPS under linear and nonlinear load conditions. Software PLL for precise synchronization of one period sampling and double buffer memory...
In mission critical power installations, such as data centres, the use of double conversion UPS has been considered the best choice to date for protecting against power quality problems. Indeed, this UPS technology allows for a high level of load protection against any type of electrical disturbance of the network and isolation of the mains against the load's non linear behavior. The cost saving related...
The Internet business is rapidly growing in recent years, and therefore the installation of new electrical facilities and the expansion of existing facilities are increasing. However, there are two problems facing these facilities: How to secure installation space, and the increase in power consumption of the facilities. There is also a demand for compact, highly efficient power supply. As the input...
A parallel operation system of multiple UPS is used to increase power capacity of the system or to secure higher reliability at critical loads. In the parallel operation of UPS inverters, the load-sharing control to maintain the current balance between them is a matter of consequence. Because a UPS has low output impedance and quick response characteristics, in case of an unbalanced load inverter...
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