very-fast transient overvoltage (VFTO)-related problems are raising growing concerns in China with the development of ultra-high voltage. The practice of fitting ferrite rings on gas-insulated switchgear busbars for V...
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Wind-photovoltaic-energy storage (ES) hybrid generating system has numerous reactive power sources. It is crucially important for coordinated control of these reactive power sources. According to the test results, the...
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The wide-band oscillation resulting from the interaction between power electronics and the power grid is increasingly evident to the power system. It is necessary to monitor the dynamic behavior of the wide-band oscil...
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Cause identification of single-line-to-ground fault in the distribution system is of great significance to the electric workers for fault isolation and rapid maintenance. The key of fault cause identification is to ac...
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Shielding failure of lightning is the key problem for safe operation of transmission lines. Compare to Electro-geometry Method, Leader Progress Method more suitable for lightning protection analysis because the physic...
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Shielding failure of lightning is the key problem for safe operation of transmission lines. Compare to Electro-geometry Method, Leader Progress Method more suitable for lightning protection analysis because the physical model is used instead of empirical formula. The relationship between amplitude of lightning current and other parameters, such as wires position, ground tilt angle, was analyzed.
Travelling-wave starting element is an integral part of the ultra high-speed protection. Existing design method depends on engineering experience, low accuracy in travelling-wave signal recognition, easy to trip frequ...
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Travelling-wave starting element is an integral part of the ultra high-speed protection. Existing design method depends on engineering experience, low accuracy in travelling-wave signal recognition, easy to trip frequently or refuse to trip. To solve these problems, through mass of starting signal simulation and analysis under different fault conditions, this paper focuses on the travelling-wave starting element and figures out the travelling-wave identification method. This paper summarizes the frequency and voltage characteristics of travelling-wave head, puts forward a new method in real-time travelling-wave fault identification. In addition, the analysis course included in this paper is a useful attempt that can be used in similar fault travelling-wave analysis.
Along with the increasing system capacity, large-scaled energy storage systems are supposed to be connected into 10kV or higher networks. Urban network has strict criterions on power quality of the power electronic de...
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Along with the increasing system capacity, large-scaled energy storage systems are supposed to be connected into 10kV or higher networks. Urban network has strict criterions on power quality of the power electronic devices connected. Moreover, the occupancy and noise of industrial frequency transformers also become restraints to the promotion of urban network energy storage. For that reason, this paper proposes a battery energy storage system based on cascaded dc-ac converter, dual active bridges, and a common dc bus. High frequency transformers are used to replace the industrial frequency transformer for insulation, and battery groups are connected to the common dc bus with respective dc-dc interfaces. This multilevel converter system is easy to modularize, easy to extend, and allows different kinds of batteries to work together. The main circuit and proper control system are designed, with the soft-switching condition and current control issues of the dual active bridge analyzed in detail. The simulation results from EMTDC model verify the operation principles and corresponding control strategies.
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.
Wireless power transfer (WPT) has been a research focus in recent decades. Based on magnetically-coupled resonant WPT (MCR-WPT), this paper made a comparison of two basic structures in MCR-WPT: the two-coil structure ...
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Wireless power transfer (WPT) has been a research focus in recent decades. Based on magnetically-coupled resonant WPT (MCR-WPT), this paper made a comparison of two basic structures in MCR-WPT: the two-coil structure and the four-coil structure. Their equivalent circuits were built. To illuminate the difference between these two structures, the input impedance, the transfer efficiency, and the load matching were studied and tested by experimental results. The conclusion is drawn that without reducing the transfer efficiency, the addition of the source coil and the load coil in the four-coil structure makes it easier to match the source and the load than the two-coil structure.
In order to avoid irrational reactive power flow and voltage distribution, the coordinated voltage controlsystem integrated for regional, provincial and prefectural control centers in China Southern power Grid is prop...
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