Shielding failure is one of key problems of UHV transmission lines. Considering the high operating voltage and high tower of UHV transmission lines, the inception criterion of upward leader is proposed in this paper. ...
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To coordinately consider the economy and security of the system during reactive voltage control, a multi-objective reactive power optimization model is proposed. Apart from the conventional economic objective, the new...
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The paper “Principle and Model for Regional Allocation of Carbon Emission from Electricity Sector” is focused on the hot issue of carbon allocation problem,while the research scope is restricted to electricity *** a...
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The paper “Principle and Model for Regional Allocation of Carbon Emission from Electricity Sector” is focused on the hot issue of carbon allocation problem,while the research scope is restricted to electricity *** authors propose a fair allocation principle considering the social contribution and environmental cost of electricity *** to the allocation principle,a novel model and concept of carbon flow tracing is presented to satisfy the requirements based on electricity flow tracing methodology,which traces the sources of regional electricity imports to determine the carbon allocation reasonably.
In this paper, we examine a resonant capacitor current feedback (RCCF) self-oscillating resonant inverter from nonlinear point of view. By adopting a four-stage equivalent model, we derive the soft-switching dead time...
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The large-size planar DC bus bar is widely used in high power converters, whose stray parameters are significantly affected the converter reliability and performance. Taking the example of an actual 315kW/400V inverte...
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The large-size planar DC bus bar is widely used in high power converters, whose stray parameters are significantly affected the converter reliability and performance. Taking the example of an actual 315kW/400V inverter, the design, simulation and analysis for its bus bar stray parameters is described in detailed. Being different from the conventional method that considers the bus bar conductor as an entirety, an improved method is proposed in this paper, which separates the bus bar into several segments and evaluates the influence of stray parameters in each segment to the power semiconductor devices respectively. Therefore, this improved method can provide support for the more accurate and effective design and optimization of bus bar. In addition, two different structure of bus bar are implemented in the actual inverter, the comparison and analysis of experiment results for both structures proves the validity of the proposed method.
Formulation of day-ahead operation schedule for large-scale power grid requires security validation, including static security, dynamic and transient stability. It is an important and basic task for day-ahead security...
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The Electromagnetic Compatibility (EMC) is a major issue for the truck crane designing, due to the large dimension. The conducted disturbance sources of truck crane was measured under stable conditions, the time domai...
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Partial discharge (PD) monitoring plays an important role in the online maintenance of the gas insulated switchgear (GIS). In recent years, the ultra high frequency (UHF) method for PD detection arouses great interest...
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ISBN:
(纸本)9781467310192
Partial discharge (PD) monitoring plays an important role in the online maintenance of the gas insulated switchgear (GIS). In recent years, the ultra high frequency (UHF) method for PD detection arouses great interest of many researchers because of the high sensitivity and anti-interference capability. The coupling of UHF signal is the key to the detection of partial discharge in GIS. The structure size of GIS has great impacts on the PD signal, because the cutoff frequency of the high order mode of the electromagnetic (EM) wave depends on the diameters of the inner conductor and enclosure. In this paper, the influence of the inner conductor diameter is investigated by varying the center conductor size. The inner coupler is adopted to receive the partial discharge signal, and two types of PD sources are tested in the experiment. Firstly, the amplitude and the duration of the time domain signal and the frequency spectrum are focused, and their variations with the size of inner conductor are analyzed. Besides that, In order to research the changes of the TEM mode component and the high order mode component, low pass (LP), band pass (BP) and high pass (HP) filters are applied to process the PD signals, and the cumulative energy rates are calculated to indicate the energy distribution. In addition, a simulation using the FDTD method is conducted for comparison with the experimental results, and it indicates that the results of experiment and simulation are almost consistent.
To increase efficiency is an essential target in photovoltaic (PV) powergeneration system. The losses of the whole system consist of several parts. This paper focuses on the losses of the hard-switching devices. An i...
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ISBN:
(纸本)9781467323277
To increase efficiency is an essential target in photovoltaic (PV) powergeneration system. The losses of the whole system consist of several parts. This paper focuses on the losses of the hard-switching devices. An improved method to calculate the device losses is proposed. And influences of different factors like DC link voltage, input power, switching frequency and power factor on the losses are considered. Then this paper compares the losses of conventional two-level inverter and of diode-clamped three-level inverter to provide the evaluation of power losses under different working conditions. This is helpful to design and optimize a certain PV inverter. Calculating results based on an actual three phase 10kW PV inverter are presented.
By taking into account the real-time measurement with low redundancy and of only partial current in distribution systems and referring to the quasi-real-time current measuring data of the metering system, the current ...
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