Multi-inverter UPS system with redundant load sharing control

Holtz, J.; Werner, Karl-Heinz

doi:10.1109/iecon.1989.69628

Cited by 12 publications

(7 citation statements)

References 3 publications

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“…Many factors and definitions are related to reliability (e.g., mean time to failure [MTTF], mean time between failures [MTBF], and mean time to repair [MTTR]). The MTTF is the expected value representing the return period of equipment failure [4]–[7]. It can be expressed mathematically as [8], , where E(t) is the expected value of time, and f(t) is the probability density function (pdf) for variable t. The MTTF is also referred to as the expected life.…”

Section: Reliability and Failure Functionsmentioning

confidence: 99%

Reliability Measurement for Mixed Mode Failures of 33/11 Kilovolt Electric Power Distribution Stations

2013

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The reliability of the electrical distribution system is a contemporary research field due to diverse applications of electricity in everyday life and diverse industries. However a few research papers exist in literature. This paper proposes a methodology for assessing the reliability of 33/11 Kilovolt high-power stations based on average time between failures. The objective of this paper is to find the optimal fit for the failure data via time between failures. We determine the parameter estimation for all components of the station. We also estimate the reliability value of each component and the reliability value of the system as a whole. The best fitting distribution for the time between failures is a three parameter Dagum distribution with a scale parameter and shape parameters and . Our analysis reveals that the reliability value decreased by 38.2% in each 30 days. We believe that the current paper is the first to address this issue and its analysis. Thus, the results obtained in this research reflect its originality. We also suggest the practicality of using these results for power systems for both the maintenance of power systems models and preventive maintenance models.

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Section: Reliability and Failure Functionsmentioning

confidence: 99%

Reliability Measurement for Mixed Mode Failures of 33/11 Kilovolt Electric Power Distribution Stations

2013

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“…Most integrated circuit rms-to-dc converters either explicitly or implicitly calculate the rms of a signal as LPF (6) where LPF denotes a low-pass filtering operation, typically using a first-or second-order filter. We will focus on the effects of computing the mean square using this technique-the rms value is merely the square root of this.…”

Section: Appendix a Rms-to-dc Conversionmentioning

confidence: 99%

Frequency-based current-sharing techniques for paralleled power converters

Perreault

Selders

Kassakian

1998

IEEE Trans. Power Electron.

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A new current-sharing technique for paralleled power converters, which is based on frequency encoding of the current-sharing information, is introduced. The approach has significant advantages over existing methods, including the ability to transformer isolate or eliminate current-sharing control connections. Operation of the current-sharing technique is analyzed, and the design and experimental evaluation of a three-cell prototype system are presented.

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“…Several inverter modules are operating at the same time to work as inverter stage of the online UPS system. Numbers of the parallel control technologies, such as centralized control [7], masterslave control [8], [9], averaged load sharing [10], allow the possibility of allowing inverter modules share both active power and reactive power of the load. Nevertheless, critical lines are mandatory in these control algorithms.…”

Section: Introductionmentioning

confidence: 99%

Modular <italic>Plug’n’Play</italic> Control Architectures for Three-Phase Inverters in UPS Applications

Zhang

Guerrero

Vasquez

et al. 2016

IEEE Trans. on Ind. Applicat.

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In this paper a control strategy for the parallel operation of three-phase inverters in a modular online uninterruptable power supply (UPS) system is proposed. The UPS system is composed of a number for DC/ACs with LC filter connected to the same AC critical bus and an AC/DC that forms the DC bus. The proposed control is designated in two layers, individual layer and recovery layer. In individual layer, virtual impedance concept is employed in order to achieve active power sharing while individual reactive power is calculated to modify output voltage phases to achieve reactive power sharing among different modules. Recovery layer is mainly responsible for guaranteeing synchronization capability with the utility and voltage recovery. With the proposed control, improved voltage transient performance can be achieved and also DC/AC modules are allowed to be plugged in and out flexibly while controlling the AC critical bus voltage. Detailed control architecture, regarding individual layer and recovery layer, are presented in this paper. Also an experimental setup was built to validate the proposed control approach under several scenarios-case study.

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Multi-inverter UPS system with redundant load sharing control

Cited by 12 publications

References 3 publications

Reliability Measurement for Mixed Mode Failures of 33/11 Kilovolt Electric Power Distribution Stations

Reliability Measurement for Mixed Mode Failures of 33/11 Kilovolt Electric Power Distribution Stations

Frequency-based current-sharing techniques for paralleled power converters

Modular <italic>Plug’n’Play</italic> Control Architectures for Three-Phase Inverters in UPS Applications

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