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In order to improve the reliability of Ultra HVDC transmission system, hierarchic control structure on UHVDC control system is discussed in this paper. Some special control requirements are introduced, compared with the conventional ??500 kV HVDC system. The special coordination control strategy of UHVDC for Balanced Operation of Dual 12-Pulse Converter Groups is proposed, A new fuzzy PI controller...
Because of the effect of weather and environment on photovoltaic (PV) array, it is hard to perform all round tests on equipment of pv generation system with the real PV array as test. So a novel pv array emulator system based on Zero-Voltage Zero-current Full-bridge converter with two diodes in series with lagging leg is put forward and a mathematical model of PV array, which use a linear model formed...
Along with environmental consciousness enhancement, conventional energy depletion, wind energy exploitation is expanding gradually due to the renewable merit, clean without any pollution and vast reserve features. Therefore, wind power generation (WPG) system equipped with Doubly Fed Induction Generators is emerging as mushroom. Larger rated capacity of power unit, the higher tower and the variable...
Because of the mutual electromagnetic effect between four-parallel transmission lines and various types of crossing-country faults, the fault calculation and analysis are faced with technical difficulties in practice. Based on the analysis of characteristics for four-parallel transmission lines, this paper decouples twelve phase components equation by the twelve sequence phase-mode transformation...
The calculation and analysis for the open conductors fault has important significance for the security and stability of power system normal operation. Based on the twelve sequence components method and the analysis of the characteristics for four-parallel transmission lines, this paper first introduces twelve phase components equation of four-parallel transmission lines and the fault points boundary...
Based on the theory of twelve sequence components, this paper analyzes the single circuit line fault characteristics of four-parallel transmission lines on the same tower. By use of the relationship of different amplitudes and phases between each sequence components, a new method is proposed for fault line selection of four-parallel transmission lines. The method is validated by a large amount of...
For differential unitary space-time modulation (DUSTM), the bit-error performance is affected by the type of labeling. In this paper, we used the Binary Switching Algorithm (BSA) to optimize the labeling of cyclic constructed DUSTM constellation. Instead of time-consuming simulation, we constructed an easily-calculated cost function to estimate the impact of different types of labeling on the bit-error...
Color weights of green(G) and red(R) are extracted from the color space RGB for color video image, and then are respectively converted to binary images, which are used in the following image matching. Methods of Large Diamond Search and Small Diamond Search are applied in template searching in the binary images with the values R and G. Method of block matching is used to obtain the motion vectors...
In order to acclimatize amphibious bio-crab robot to the amphibious environment better, a series-parallel structure of amphibious bio-crab robot is proposed, then we designed an amphibious bio-crab robot which use the modular worm and worm wheel transmission mechanism to achieve the transmission of the leg joint. A single leg and overall walking simulation model of amphibious bio-crab robot was established,...
Relay node placement is an important issue because it greatly affects the performance of wireless ad hoc sensor networks. The pervious works mainly pay attention on placing the minimum number of relay nodes to connect all the sensor nodes. But we find that this placement scheme may result in QoS reduction of the network, such as transmission delay, energy cost, etc. Therefore, this work studies the...
The economic crisis broke out in 2008 has strongly impacted global automotive industry. Whereas, under the support of Chinese automotive industry rejuvenation program, Chinese automotive industry has obtained giant favorable turn in 2009, and becomes the only country which could increase the automobile production and sales volume and get satisfied profits in the whole world. The program also emphasizes...
Based on analysis of the structure and control requirements of ice-storage air conditioning system, a distributed control system design was introduced. The hardware environment was mainly based on programmable logic controller (PLC), and a touching screen was also applied as the local platforms of SCADA ( supervisory control and data acquisition) ; The software were CX-Programmer 7.1 and EV5000 configuration...
A low frequency hydrophone with built-in amplifier was presented. It used cylinder piezoelectric ceramic as a sensing element, which had been embedded by polyurethane. When sound pressure was applied to the flexible cylinder, the piezoelectric ceramic transferred the sound pressure to electric charge. There was a preamplifier in the hydrophone. The sensitivity of the hydrophone can be controlled by...
When the system mathematical model and the noise statistical properties are not very accurate, the Kalman filtering will reduce the precision of filtering, and even lead to filter divergence.In view of this, adaptive filtering which based on the principle of Kalman filtering is proposed. By comparison experiment, it can be obtained that the adaptive filtering can achieve better filtering effect than...
In a HVDC transmission system, faults occur in the AC system can result in the variation of impedance-frequency characteristic of the HVDC converter. In this paper, an advanced switching function model of HVDC converter, which considers the effect of the interactions between the AC and DC system and the unbalanced operating conditions of the converter, is presented. Based on this model, a method for...
After a detailed analysis of the dynamic processes in the HVDC converter when asymmetric faults occur in the ac system, a sequence-component model of converter based on the advanced switching functions is present. Furthermore, a linear direct method of harmonic calculation is proposed. In this method, both the effect of the harmonic interaction between the ac and dc system and the dynamic processes...
Study on eco-environmental water requirement was of great significance in the planning and regulation of ecological water system, and the regional optimization of water resources. The river ecological water requirement is the core of the study. In this paper the meaning of eco-environmental water requirement and ecological status of lake are discussed. Based on the environmental flow of natural ecosystem,...
The framework for evaluation and adjustment workshop layout has been designed in the paper. The evaluation system according to the characters in the manufacturing process of aero-engine production has been constructed. The fuzzy-AHP method is put forward to evaluate workshop layout. In order to adjust workshop layout according to the schema optimized, the generic algorithm has been designed. At the...
The inner time-structure information is considered for the dynamic independent component analysis (DICA)model, and the new concept of innovation and corresponding algorithm are presented. When the innovation is applied in DICA, a new linear mixing model of innovation DICA (IDICA)can be obtained in which the assumptions of independence and non-Gaussianity for the basic ICA model are also satisfied,and...
Today, the scale of high performance computing (HPC) systems is much larger than ever. Some HPC systems consist of thousands or even tens of thousands of processors. The larger scale leads to a challenge that how to deal with process failures. The most important programming tool for HPC is MPI (message passing interface). There are some existing methods to deal with fault-tolerance, such as MPICH-V,...
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