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article
IEEE Transactions on Power Electronics > 2018 > 33 > 2 > 936 - 942
To regulate the dc-link voltage of three-phase ac/dc converters, an enhanced state observer-based controller is presented in this letter. The proposed controller, contrary to the traditional ones, does not require the dc-link current measurement and offers a “plug and play” capability, a rather high disturbance rejection ability and robustness against the dc-link capacitance parameter variation. The...
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IEEE Journal of Photovoltaics > 2018 > 8 > 1 > 110 - 117
ZnSnN2 (ZTN) has been proposed as a new earth abundant absorber material for photovoltaic (PV) applications. While carrier concentration has been reduced to values suitable for device implementation, other properties such as ionization potential, electron affinity, and work function are not known. Here, we experimentally determine the value of ionization potential (5.6 eV), electron affinity (4.1...
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Ocean Networks Canada submitted a proposal to Western Economic Diversification Canada (WED) in 2014 to develop ocean monitoring infrastructure using advanced sensing technologies in areas critical to BC's economic future, such as the proposed LNG facilities at Campbell River, and the ports of Kitimat and Prince Rupert. The proposed infrastructure included technology related to monitoring maritime...
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IEEE Transactions on Green Communications and Networking > 2017 > 1 > 4 > 551 - 562
The grid company enforces high penalties for the peak power demands of cloud data centers. These penalties result in high electricity bills that can be avoided by relying on the servers’ uninterruptible power supply (UPS) batteries as a source of energy during high-demand periods. This paper proposes a resource management framework that leverages the availability of UPS batteries to reduce the data...
article
IEEE Transactions on Industrial Electronics > 2017 > 64 > 12 > 9210 - 9220
The instantaneous average current sharing (IACS) control strategy ensures accurate transient and steady-state current sharing among uninterruptible power supply (UPS) modules connected in parallel, but is dependent on a communication backbone. This paper proposes a new IACS scheme that is more reliable and economically efficient. In the process of deriving this control scheme, two existing IACS schemes...
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We present a novel computational method for Multiple Sequence Alignment (MSA), a fundamental problem in computational biology. In contrast to other known approaches, our method searches for an optimal alignment — structurally and evolutionarily — by inserting or deleting gaps from a set of initial candidates in an efficient manner. Our method called a Universal Partitioning Search (UPS) approach for...
article
IEEE Transactions on Smart Grid > 2017 > 8 > 6 > 2702 - 2711
This paper presents experimental results of electric vehicle (EV) operation as an off-line uninterruptible power supply (UPS). Besides the traditional grid-to-vehicle and vehicle-to-grid modes, this paper presents an improved vehicle-to-home operation mode. This new operation mode consists of the detection of a power outage in the power grid and the change of the EV battery charger control to operate...
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An average power sharing control strategy for parallel operation of voltage source inverter (VSI) based modular Uninterruptible Power Systems (UPSs) is proposed in this paper. The presented method is based on a modified droop control. The proposed method conquers the drawback of conventional droop plus virtual impedance control, and at the same time some challenges in the real applications have been...
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Digital lifestyle with always-on connection to internet as well as the emergence of Internet of Things (IoT) throughout the world calls for reliable, concurrently maintainable data center and telecommunications systems. Thus, this need had pushed the limit of electrical and mechanical system, in particular power and cooling systems to provide reliable, economical and maintainable services. This requirements...
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Eco mode UPS will power the load with mains power supply directly when the quality of mains power supply is good. When the quality of mains power supply decreases Eco mode UPS will switch to double conversion mode rapidly to meet the requirement of power quality. Eco mode UPS has the highest efficiency and the highest reliability. Using Eco mode UPS is an important measure of data center energy saving,...
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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...
chapter
To address the active power feeding issue in the parallel Uninterruptible Power Supply (UPS) system, a DC-link Voltage Protection (DCVP) control strategy is proposed in this paper. The proposed control method only relies on local load information, which increases the system reliability and robustness. Moreover, virtual resistance based regulation strategies are proposed for solving the active power...
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A short-circuit fault protection strategy based on the direction of bus-side capacitor discharge current for a high-surety power supply, known as Super Uninterruptable Power Supply (Super UPS), is studied in this paper. It consists of multiple energy sources and storage components. All energy sources and storage components are connected to a common DC bus through converters in the system. If a short-circuit...
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This paper proposes a single-phase ac-dc-ac converter composed of a transformer and two three-leg converters connected in series. The proposed converter allows to feed the load voltage with sinusoidal voltages with constant amplitude and frequency and to operate with sinusoidal grid current with high power factor. Besides, the converter can be used to mitigate fundamental over-voltage and voltage...
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High reliability is extremely important for uninterruptable power supplies (UPS) such as those used in the modern data centers. It is necessary to comprehensively and precisely evaluate reliability of different UPS system's architectures before constructing the data center. In this paper, a novel reliability analysis and simulation tool for data center power distribution system is proposed. The basic...
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In this paper, a zero-voltage switching DC-AC inverter is designed and realized. The neutral point clamped topology and fix-frequency PWM control are used in the proposed inverter to implement a single-phase DC-AC inverter. Also, an auxiliary inductor and two auxiliary switches are adopted to achieve zero-voltage switching, which can improve the inverter efficiency. In this paper, the proposed DC-AC...
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DC distribution is emerging as a solution for data centers, however the optimal system architectures have not been established in the industry. This paper first reviews the most recent studies, products and activities of DC distribution in data centers. A hybrid AC and DC distribution architecture is introduced by using both 415V AC and 380V DC together to achieve the data center reliability requirements...
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To address the DC link voltage regeneration issue in parallel Uninterruptible Power Supply (UPS) system, a DC link voltage protection (DCVP) method through online virtual resistance regulation is proposed. The proposed control strategy is able to protect the DC link from overvoltage that may trigger the protection mechanism of the UPS system. Moreover, a current sharing control strategy by regulating...
chapter
In this paper, first, the existing frequency and voltage amplitude restoration control strategies are reviewed. Moreover, the proposed second order washout filter control strategy is proposed to enhance the dynamic response under load disturbance. The physical parameter of the proposed method is derived, and system stability for the system parameter is discussed. Finally, extensive simulation results...
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In stable electrical networks, such as the German one, the service of uninterruptible power supply (UPS) systems is only rarely called. Consequently the battery lifetime in this application is mostly restricted by calendar aging. The concept of multi-use describes here the delivery of additional services with a UPS during stable grid operation. The overall goal is to allocate the battery capacity...
