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The common mode (CM) noise mechanism of totem-pole bridgeless PFC converter is analyzed in this paper. The conducted noise performance of a bridgeless totem-pole PFC converter using GaN HEMTs is investigated under experimental conditions: 230V ac input, 390V dc output, and 50kHz switching frequency. The CM noise located around the input voltage zero-crossing of the converter is noticed to be significant...
Demand for reliable, efficient mobile network services is increasing, as customers seek for more value-added services (VAS) from telecom operators. However, many operators still suffer from network outages as they do not have solutions in place that will detect and alert them of a problem even before it escalates. Network outages can be prevented through a comprehensive, intelligent monitoring system...
In this paper, stability analysis of a typical DC/DC Boost converter feeding a Constant Power Load (CPL) with and without a Battery Energy Storage (BES) is discussed and explained. CPLs, usually, cause instability issues for DC/DC converters due to their negative impedance characteristic. The state-space averaged model analysis of the converter is performed and stability regions of the converter while...
In recent years, storage batteries have been introduced to suppress fluctuations in the output power of renewable energy sources. The lifetime of batteries used in these systems varies based on the operational methods used. In this study, we investigated the effects of introducing a flywheel into a microgrid comprising photovoltaic equipment, batteries, and a load. The flywheel reduced the maximum...
Simulations of annual reduction in power consumption based on tests of the energy-saving effect of introducing the air-side economizer (direct outside air cooling) to data centers in Japan are reported. Effects of environmental factors on energy saving are compared for air-side economizer and conventional systems that use air conditioners for cooling. When the air-side economizer is used, weather...
This paper presents a harmonic current injection control for active islanding detection of grid-connected inverters. A standardized islanding detection method called frequency feedback method with step reactive power injection is used in the inverter system for islanding detection. After an islanding event, this method measures the change of voltage harmonic distortion and injects reactive power to...
In the power packet dispatching system, electric power is transferred with information tags attached physically. An application of the system to robots can enable flexible and efficient power management with a dynamically varying powerline connection between power sources and loads. In this paper, a numerical simulation verifies the achievement of a trajectory control of a manipulator by power packets...
A green base station with a cylindrical flexible photovoltaic (PV) module mounted to a telecommunication pole is developed. The present paper proposes a method for calculating the power output of the cylindrical flexible PV module mounted to a telecommunication pole and describes the effects of the setting position of the PV module and height to diameter ratio of the pole on its power output taking...
Reducing the power consumed by base stations is an urgent requirement. Our research shows that it is possible to reduce electricity consumption, especially peak loads, by predicting the power demands of base stations. This approach is implemented in the Green Power Controller, a technique developed for the Green Base Station which is the power system of base stations used for disaster relief and reducing...
The amount of energy consumed by data centers and telecom buildings is increasing annually due to the buildup and high-density arrangement of ICT equipment, which is needed to handle the rapid rise in traffic brought on by the spread of smartphones and advances in the Internet usage environment. At the same time, services that use ICT equipment are expected to provide high levels of reliability and...
Site infrastructure sharing is the trend of future base station construction. Telecom infrastructure operators require for smooth upgrading and low TCO when sharing sites power supply, spaces and operation management. This paper introduces a new integrated hybrid power supply system suitable for the site sharing requirements. It perfectly combines many functions together, such as energy generation,...
In this paper the behavior of a tower and its grounding system, subjected to a lightning, is faced. Finite difference time domain (FDTD) method has been chosen in order to study the non-linear time domain behavior of the system. The electromagnetic problem has been described by using two type of first order time derivative equations: Maxwell's equations and Telegraph equations. Aim of this work is...
This paper analyses the parameter dependence during the charging process of a Vanadium Redox Flow Battery (VRB) for a system-aware green data center which has distributed sources of energy production and amenable to flexible load scheduling. One of the key features of a flow battery is the ability to control the flow rate and current during the charging process. The flexibility however has a direct...
To reduce the life cycle cost of solar power plants, high conversion efficiency for inverters is necessary. The advantages of SiC MOSFETs include not only lower conduction loss but also the ability of high-speed switching. Lower switching loss is derived from high-speed switching. Especially with SiC MOSFETs, the tail current and switching recovery loss can be drastically reduced compared with Si...
A surge protective device (SPD) is used in low-voltage power systems to protect electrical equipment from surges induced by lightning. An SPD has a drawback that its impedance becomes low in case of SPD failure. This failure can cause not only the SPD, or other devices near it, to catch fire or make an upstream over current protection device (OCPD) operate unnecessary, and also can cause serious damage...
The Wide-Area Control and Operation System for stabilizing renewable energy generations utilizing averaging effect was proposed to reduce capacity of battery energy storage system and a demonstrative project supported by Ministry of Environment of Japan was conducted in order to verify effects of the proposed system. In this paper, concept and configuration of the system are introduced and verification...
This paper presents a simple and low cost PV simulator using diode characteristics for development of PV system. In order to reproduce characteristics of PV module, instead of huge digital data of I-V characteristics of PV module considering temperature dependence, a real diode is used in the proposed system. A low cost microcontroller that has a little amount of data memory is used to control the...
One of the important design issues of smart green buildings is to make use of energy, water and other resources efficiently. Improving the energy efficiency of buildings is an important step towards a more sustainable lifestyle, leading to significant cost savings for the residents. Wireless sensor network will be responsible for the majority of the growth in smart green building systems over the...
The prototypes of the appliance coupler for 400 Volts direct current power distribution system have developed and evaluated. Arc extinguishing and electric shock prevention functions are adopted for safety. Evaluation of load switching is performed with the prototypes and enough capability of arc extinguishing were observed. The prototype was made for confirmation of functions. So that, the shapes,...
We developed the alarm fuse for High Voltage Direct Current (HVDC) power system. It was realized stable breaking characteristics and low transient voltage by our specific know-how for interrupting DC voltage and unique shape of fuse element.
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