Applied Mechanics and Materials Vols. 543-547

Abstract: This paper discusses that the capacitive current is a must of producing arc grounding overvoltage, and the method and necessary to restrain arc grounding over voltage. It also explains the concept of capacitive current and arc suppression coil, and the test method and significance of measuring capacitive current. Based on the comprehensive field test and evaluation of 29 substations, it provides the correct selection of neutral point operation mode and gives a development direction to 10 kV power network neutral point grounding method of Fushun grid.

Abstract: Load forecasting is one of the important working of the power system, which plays a very significant role in various departments of power system operation. Load accurate scientific prediction can make power decision-making departments economically and reasonably to adjust generator, power line, which makes it more reasonable. This paper introduces the optimal combination forecast model, and organically combine with several electric load forecasting models by the weight, come to more accurate results, with higher prediction accuracy, and the relative error is small, it has some practical value.

Abstract: Global warming is a major reason for dramatic climate changes around the world. Among various renewable energy sources, solar energy is one of the most promising for environmental protection and natural resource scarcity resolution. With the technical advantages obtained from the semiconductor and TFT-LCD industries, the Photovoltaic (PV) industry in Taiwan can achieve a solid global position. Current PV products, however, still face a large obstacle due to high production cost and low PV conversion efficiency. An important source of competitive advantage, survival and renewal for firms in todays competitive market is successful new product development (NPD). PV firms need to carry out effective R&D in order to improve product quality and to obtain cost effectiveness. This research, thus, constructs a comprehensive model, which comprises fuzzy Delphi method (FDM) and quality function deployment (QFD), for implementing a NPD project for a PV manufacturer. The proposed model shall help designers to systematically consider relevant NPD information and reconcile tradeoffs among various performance characteristics in a fuzzy environment.

Abstract: A new kind of hydraulic transformer, called variable hydraulic transformer (VHT), has been proposed to control its load flow rate. The displacement characteristics of VHT are investigated in detail. The mathematic models are concluded and optimized. Matlab is used to simulate and calculate, finding that there are 5 controlled angles of the port plate that can help define displacement characteristics of VHT. The relationships between the displacement characteristics and the structure in VHT are shown. The results demonstrate the performance laws of VHT when the controlled angles of the port plate and of the swash plate change.

Abstract: As for the two main limitations as partial constringency and convergence hysteresis of Genetic Algorithms (GA), predatory search is introduced and Predatory Search Genetic Algorithms (PSGA) based on GA is designed to enhance the integrate ability of hunting. The concepts of fire support platform and target fitness are introduced, and fire power distribution model based on fire support fitness coefficient is built. The improved PSGA is applied to fire power and emulation experiment is done. The result of emulation shows the validity of the improved algorithm.

Abstract: In this paper, the author introduced resonance mechanism into the stability analysis of power system, established comprehensive mathematical model including units and power grids by considering the effects from generation side and line side. On this basis, the author simulated several typical disturbances to analysis by MATLAB SIMULINK. The result showed that the power oscillation will be caused when the natural frequency of the grid and the frequency of disturbances are same or similar, especially in multi-area interconnected power system. The disturbances from different units can produce a significant impact transient or sustained oscillation by superposition, endanger the stability of power system.

Abstract: A Full Hole-barrier Trench gate Insulated Gate Bipolar Transistor (FH-TIGBT) device structure is proposed for the first time. Compared with Carrier Stored Trench IGBT (CSTBT), which adds a carrier stored n layer between p base and n base in Trench IGBT (TIGBT), the new structure appends an n region located in the bottom of the trench gate. The result of Process and device simulations shows that the proposed device has lowered saturation voltage and larger capability of carrying current compared to either conventional trench IGBT or CSTBT. And the characteristics of turn-off time and breakdown voltage have negligibly changed. Further more, it has strongly positive temperature coefficient of on-state voltage, which means paralleling is very simple for the new device.

Abstract: Along with the development of power electronic technology, harmonic and reactive power problem for power system are increasingly serious. 3-phase Commutate System with DC/DC Converter is widely used power system, and its power factor generally very low. Circuit design can increase power factor and decrease THD for 3-phase Commutate System with DC/DC Converter , and then decrease the weight and volume . According to the simulation result ,we know that the 6kW DC/DC converter designed in this paper has lower THD , high PF . less weight , less volume and good steadiness , for example THD is less the 5%, and PF is greater than 95%.

Abstract: This paper applies the theory of expert system to analysis for relay protection action based on PAS. And it also summarizes various rules according to the experience of operating personals and relay protection personals for several years. All these rules are suitable for 110kV and 66kV regional networks. This paper not only analyzes three-phase current protection, zero-sequence current protection, distance protection etc, but also discusses some special situations such as under voltage lockout over-current protection for transformer, remote backup protection etc.

Abstract: This paper has designed an active power filter control system with dual digital signal processor (DSP) core, which meets the requirements of functional and intelligent design of the active power filter (APF), and improves the real-time performance efficiency of the controller. Firstly, the structure of the controller hardware system design process, as well as major hardware modules were analyzed in detail; Then in-depth analysis of AD conditioning circuit module, analog-to-digital converter module, dual-port RAM modules and fault detection circuit module as well as the dual DSP program process was introduced. Finally the real-time performance and accuracy of the designed controller was proved by the performance test.