In search for common ground: how an automatic turbine system supports operator work.
ABSTRACT Motivation -- The use of automation technology tends to steadily increase in a wide range of applications. With this comes a demand to design systems that support team play among human operators and automation to avoid problems related to monitoring work. Research approach -- The study was performed as a field study using semi-structured interviews and observations. Findings/Design -- The initial interview and observation results indicate that generally accepted research in the field of human-automation interaction is valid in the studied nuclear power control room context. The work shows the benefit of studying human joint activity to improve interface design that supports human-automation collaboration. Take away message -- Further research in the area of human-automation cooperation in control rooms is needed. A possible way for development of a design basis is to examine human-human cooperation and extract useable design guidelines.
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ABSTRACT: This paper presents several nonisolated semi-Z-source inverters for a single-phase photovoltaic (PV) system with low cost and doubly grounded features. These semi-Z-source inverters employ the Z-source/quasi-Z-source network and only two active switches to achieve the same output voltage as the traditional voltage-fed full-bridge inverter does. The two active switches of the semi-Z-source inverter are controlled complementarily. Different from the traditional single-phase Z-source/quasi-Z-source inverter, shoot-through zero state is not applicable to the semi-Z-source inverter. The input dc source and the output ac voltage of the semi-Z-source inverter share the same ground, thus leading to less leakage ground current advantages over other nondoubly grounded inverters, such as voltage-fed full-bridge inverter. This is a preferred feature for nonisolated grid-connected inverters, especially in PV application. A revised nonlinear sinusoid pulse width modulation method for a semi-Z-source inverter is also proposed. By using this method, desired duty cycle can be generated to output the sinusoidal voltage. Other dc–dc converters with similar voltage gain curve, which can also be used as a single-phase inverter, are also discussed and summarized. A single-phase semi-Z-source inverter prototype is built; experimental results are provided to verify and demonstrate the special features of the proposed circuit.IEEE Transactions on Power Electronics 12/2011; 26(12):3514-3523. DOI:10.1109/TPEL.2011.2148728 · 5.73 Impact Factor
Article: Y-Source Impedance Network[Show abstract] [Hide abstract]
ABSTRACT: This letter introduces a new versatile Y-shaped impedance network for realizing converters that demand a very high-voltage gain, while using a small duty ratio. To achieve that, the proposed network uses a tightly coupled transformer with three windings, whose obtained gain is presently not matched by existing networks operated at the same duty ratio. The proposed impedance network also has more degrees of freedom for varying its gain, and hence, more design freedom for meeting requirements demanded from it. This capability has been demonstrated by mathematical derivation, and proven in experiment with an example of a single-switch dc–dc converter.IEEE Transactions on Power Electronics 03/2014; 29(7):3250-3254. DOI:10.1109/TPEL.2013.2296517 · 5.73 Impact Factor
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ABSTRACT: This study presents a novel three-level neutral-point-clamped quasi-Z-source inverter in the single-stage buck-boost multilevel inverter family. The topology was derived by combining the properties of the quasi-Z-source network with those of a three-level neutral point clamped inverter. It features such advantages as low voltage stress of the switches, single-stage buck-boost power conversion, continuous input current, short-circuit withstandability and low total harmonic distortion of the output voltage and current. The authors present a steady state analysis of the topology along with a special modulation technique to distribute shoot-through states during the whole fundamental period. Component design guidelines for a single-phase case study system are described. All the findings have been confirmed by simulations and experiments. The topology could be recommended for applications requiring continuous input current, high input voltage gain and enhanced quality of the output voltage.IET Power Electronics 02/2015; 8(1):1-10. DOI:10.1049/iet-pel.2013.0904 · 1.32 Impact Factor