Ice accretion on high voltage power lines is a severe problem for power network and it can cause insulator flashover, wire breakage and tower falling down. In the present work, hydrophobic aluminum cable steel reinfor...
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ISBN:
(纸本)9781424494682
Ice accretion on high voltage power lines is a severe problem for power network and it can cause insulator flashover, wire breakage and tower falling down. In the present work, hydrophobic aluminum cable steel reinforced was prepared with a simple chemical etching and modified with a fluoroalkylsilane (FAS) coating. Only partial area of the hydrophobic sample was covered by some isolated ice crystal and form long icicle gradually when it was sprayed by supercooled water droplet under low temperature condition. As for the common aluminum cable steel reinforced, an intact ice layer was frozen on its surface quickly when it was tested under the same condition. The experimental results suggested that the hydrophobicity can affect the ice accretion process of the aluminum cable steel reinforced. The etched sample modified with FAS coating has a better hydrophobicity which resulted the supercooled water droplet not to be adhered to the aluminum surface easily, so ice accretion can be mitigate. The common aluminum sample was hydrophilic, therefore it can be wetted by supercooled water droplet easily and an intact ice layer was frozen quickly.
Distributed generation (DG) technology has drawn increasing attention for its tremendous benefits to customers, utilities and the environment. Furthermore, microturbine based power generation has become the most promi...
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Distributed generation (DG) technology has drawn increasing attention for its tremendous benefits to customers, utilities and the environment. Furthermore, microturbine based power generation has become the most promising DG for its excellent record of improving system stability and economy. In this paper we develop a complete mathematic model, which includes the microturbine, a permanent magnet synchronous generator (PMSG), a three-phase bridge AC to DC rectifier, a boost converter and a DC to AC inverter. The simulated microturbine generation system (MTGS) model is a single shaft type with controlsystems and capable of regulating its output power in grid-connected mode. Also, the design and modeling of a MTGS which is suitable for isolated operation are explained with the ability of electronic controls that maintains the output voltage at their prescribed levels. Different load conditions are applied to the MTGS for evaluation of the validity and practicability of the model. Simulation studies have been carried out in PSCAD/EMTDC under different load conditions. Simulation results testify that the MTGS developed from this model can produce predictable results with these control methods.
As an important component of distribution network, micro-grid is the necessarily development trend for future. Micro-grid has greatly improved the random problems of distributed generation (DG). However, DGs, the powe...
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As an important component of distribution network, micro-grid is the necessarily development trend for future. Micro-grid has greatly improved the random problems of distributed generation (DG). However, DGs, the power electronic equipments inevitably bring about power quality problems, especially voltage flicker and harmonics. This paper tries to study the operating regulations of micro-grid in order to find out the generating mechanism and propagation characteristic of power quality problems. Taking the photovoltaic (PV) system for an example, the micro-grid simulation model has been set up. The experiments show that an appropriate control strategy coordinating every part can improve the power quality of micro-grid greatly. This paper finds out the factors affecting power quality and their harm degrees, explaining the reasons of power quality problems. Coordinating every unit, this paper set up an optimal control strategy and proper parameter settings, trying to improve power quality of micro-grid to the largest extent.
With the deepening reform to power industries, powersystems are going to gradually open the demand side and the power consumers have to face the changes of their role in the market, and make a preliminary long-term f...
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With the deepening reform to power industries, powersystems are going to gradually open the demand side and the power consumers have to face the changes of their role in the market, and make a preliminary long-term forecasting for the electricity prices. In order to consider the relations between the spot market and the long-term contract market, this paper builds a multi-electricity price grey model to comprehensive forecast the prices of the 2 markets; further researches the structure of the background value, and improves the multi-electricity price grey model; and introduces the residual error, the related grade, the mean variance ratio and the little probability of error as test indexes. The test results show that the multi-electricity price grey forecasting model and its improved model have better accuracy, and the improved model has stronger adaptability and extends the application range.
Distributed generation (DG) that uses renewable energy sources has an unstable output and this can negatively affect existing electric powersystems. In order to reduce above impact, we need to develop an energy contr...
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Distributed generation (DG) that uses renewable energy sources has an unstable output and this can negatively affect existing electric powersystems. In order to reduce above impact, we need to develop an energy controlsystem to control the output through individual DG installed in a micro-grid. First, this paper designs a grid-connected Photovoltaic (PV) system and introduces the operation principle of the various parts as well with the control strategy of the power flow. The design of energy storage is of great significance as the output power of PV cells array is greatly affected by the light intensity and the temperature change. Then, it uses the battery as the energy storage device and designs the charge-discharge control strategy according to the characteristics of the battery. Finally it verifies the feasibility of the energy storage control strategy through the simulation models which is built based on the PSCAD/EMTDC platform.
Least square support vector machines (LS-SVM) can solve small sample nonlinear multi-classification problem well, so it is applicable to the power transformer fault diagnosis by dissolved gas analysis (DGA), however t...
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Least square support vector machines (LS-SVM) can solve small sample nonlinear multi-classification problem well, so it is applicable to the power transformer fault diagnosis by dissolved gas analysis (DGA), however the selection of parameters c and σ2 greatly impacts the diagnosis result, thus the optimized selection of these parameters is necessary. In this paper, the improved genetic algorithm (IGA) is applied to the optimized selection of c and σ2. The initial population of IGA is randomly generated by coding mechanism, in this way, the search space can be quickly expanded and the diversity of individuals in the populations can be stabilized, thus both global search ability and convergence speed can be effectively improved. The LS-SVM optimized by IGA is applied to fault diagnosis by multi-sets of chromatographic data of transformer oil and the result shows that optimizing LS-SVM by IGA, the optimized selection of c and σ2 can be implemented effectively and the accuracy of power transformer fault diagnosis can be improved.
Digital based data processing and protection and controlsystem along with digital communication networks introduces new structures for substation protection and controlsystems and new methods for intelligent protect...
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Digital based data processing and protection and controlsystem along with digital communication networks introduces new structures for substation protection and controlsystems and new methods for intelligent protection and controlsystems. This paper presents a unique vision for the future integration of protection and controlsystems. Firstly, the basic concept and configuration of the developed protection and controlsystems for smart substation is introduced. The features and functions of integrated protection and controlsystems for smart substation are then discussed and compared with that of the traditional substation in detail.
Distributed generation (DG) injects new vigor into the powersystem, but it sometimes brings unfavorable factors influencing the power quality of distribution network. In this paper, the dynamic Voltage Restorer (DVR)...
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Distributed generation (DG) injects new vigor into the powersystem, but it sometimes brings unfavorable factors influencing the power quality of distribution network. In this paper, the dynamic Voltage Restorer (DVR) is introduced to the distribution network to improve the power quality. In view of that the detection of voltage compensation is the key factor that influences the effect of voltage compensation, a voltage direct detection method based on mathematical morphology is proposed. Firstly, the positive-sequence voltage with harmonics can be extracted by the instantaneous sequence-component decomposer. And then the harmonics is filtered by mathematical morphology filter. Lastly, the control variable of voltage compensation needed by DVR can be calculated from the voltage direct-detecting algorithm. The simulation results show that this method has the characteristics of favorable accuracy, real-time performance and simplicity, and assures the voltage quality of load side after compensation by DVR.
Considering the operation of microgrids (MGs) composed of distributed generations (DGs) and loads, a service restoration model aiming at the restoration of the most load with giving priority to the important load powe...
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Considering the operation of microgrids (MGs) composed of distributed generations (DGs) and loads, a service restoration model aiming at the restoration of the most load with giving priority to the important load power supply is built. On the basis of the proposed hierarchical control strategy, this paper builds up a multi-agent system (MAS) for service restoration of microgrid. Accordingly, the special functions and control strategies of each agent are discussed in detail. A simulation example of a particular microgrid based on the multi-agent system is performed to demonstrate that the efficiency and reliability of the microgrid can be improved by using MAS.
Combined with the characteristics of conventional distribution network planning, this article proposed a new power distribution network planning optimization method that based on the minimum life cycle cost (LCC) to d...
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Combined with the characteristics of conventional distribution network planning, this article proposed a new power distribution network planning optimization method that based on the minimum life cycle cost (LCC) to decide distribution network planning scheme. The life cycle cost calculation model for distribution network planning scheme is made on the premise that the power network operate safely and steadily, in order to obtain the minimum life cycle cost (LCC) as the objective function and use the multi-particle swarms cooperative optimization algorithm to optimize the distribution network path planning, while according to comparative analysis of different layout patterns of switch with LCC to obtain the minimum LCC planning scheme. Finally, the feasibility and effectiveness of the method are verified by the result of applying it to a test system.
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