Yi Fei Wang

A Dynamic Reactive Power Compensation Method of Super High-Power and High-Voltage Motor

According to the low power factor and low running efficiency, a dynamic reactive power compensation method of the super high-power and high-voltage motor is proposed in this paper. The following works have been done in the study: topology of the dynamic reactive power compensation device; principle of the dynamic reactive power compensation method; control system of the dynamic reactive power compensation device; implementation of the dynamic reactive power compensation method. The amount of reactive power compensation can be adjusted smoothly and dynamically in the process of the super high-power and high-voltage motor soft-starting. The research of this paper has laid a theoretical foundation for this compensator in industrial applications. The novel design is characterized by flexible parameter setting, excellent soft starting performance of the super high-power and high-voltage motor and bright prospect in application.

A Novel Parameter Optimization Platform of Dynamic Reactive Power Compensator for Composite Power Load

Reactive power compensation is one of the effective means to improve the quality of voltage, reduce loss and save energy. How to make full use of the inductance converter and capacitance banks and to make them cooperative run, is the key of industrialization for the dynamic reactive power compensator for the composite power load. Therefore, a novel parameter optimization platform of the dynamic reactive power compensator for the composite power load is designed in this paper. The following works have been done in the study: reactive power variation characteristic of the composite power load and power factor requirements, capacity calculation and parameter adjusting method of the dynamic reactive power compensator, and a novel parameter optimization platform of the dynamic reactive power compensator for the composite power load. The research has laid a theoretical foundation for this dynamic reactive power compensator in industrial applications.

Comparative Analysis of Davenport Wind Spectrum and Kaman Wind Spectrum in the Towering Structural Design

To the Yangtze River a long-span transmission tower as an example, this paper makes a comparative analysis on the davenport wind spectrum and kaman wind spectrum, using two different wind spectrum calculation of wind-induced response of the structure. Obtained the conclusions that kaman wind spectrum of considering vertical correlation get greater wind-induced response in a large span transmission tower engineering.

Welding Residual Stress Numerical Simulation of Guyed Mast Earplate Welded Joint

Fatigue damage of guyed mast earplate welded joint is one of the main failure forms of guyed mast under wind load, and the welding residual stress is a important influence on fatigue performance of the welded joints, therefore, accurate welding residual stresses assessment of earplate welded joint is of great significance to the research on fatigue performance of guyed mast earplate welded joint under wind load. In this paper, welding temperature field of earplate welded joint was simulated by using thermal finite element method and the gauss heat source was used as thermal input. Then, welding residual stress of earplate welded joint was simulated by using thermal elastic-plastic finite element method and the temperature field results were used as the load. The welding temperature field simulation results better reflect the locality of heating, mobility of heat source and instantaneity of heating and cooling process during the welding process. The welding residual stress simulation results show that the residual stress peak of earplate welded joint reaches the yield strength of material, and appears at the dangerous point of earplate welded joint under structural external load. This point under influence of the welding residual stress and structure load is likely to be fatigue crack initiation location.

A Novel Integration Method with Stabilizing Voltage and Frequency, UPS, Intelligent Charging for Mobile Power Supply

A novel integration method with stabilizing voltage and frequency, UPS, intelligent charging for mobile power supply has been proposed in this paper. Process of the advanced method can be divided into four steps, including the generating electricity, outputting stabilizing voltage and frequency, UPS, intelligent charging. The following works have been done in the study: the principle of the integration method, the topological structure of integration system, the Implementation of the integration method. According to the principle of the integrated method, the integrated system can be developed. The system can be realized functions, such as the generating electricity, outputting stabilizing voltage and frequency, UPS, intelligent charging and so on. By the system, the high precision voltage amplitude and frequency is supply to outdoor load, and the UPS state is maintained.

Development of a Soft Starter with Current-Limiting, Reactive Power Compensation and Harmonic Filtering

Aimed at the high starting current, low power factor and low running efficiency, a novel soft starter with current-limiting, reactive power compensation and harmonic filtering is developed in this paper. The following works have been done in the study: the research of topological structure, the design of hardware and software of the control system, the validation of experimental result. It has been successfully applied to the fans load of 10kV, 19000kW, and got better effects, and satisfies the characteristics of the current-limiting and reactive compensation during this motor starting. It can also realize the power harmonic filtering after the motor soft starting, improve the whole starting performance, save energy and keep the grid voltage stable, with easy engineering implementation and high cost performance.

Dynamic Analysis of Power Transmission Tower Collapse with Wind Load

Transmission tower collapses in adverse weather conditions now and than,which always accompanied thunderstorm.The simulation of transmission collapse under downburst wind load is studied. The tower is modeled as an assembly of beamcolumn elements,fournode isoparametric curved element,and prestressed pole unit simulation insulator,using bilinear restoring force model to formulate the material nonlinear.Simulated downburst wind load time history samples,apply it as external load to the established transmission tower model.Analysis of transmission tower know that transmission towers destroyed in the lower part of the body of the Tower, compressive failure modes in the beam , causing transmission towers final collapse.

Transmission Tower Collapse Analysis with Wind Load Based on LS-DYNA

Large span transmission tower is the lifeline of electricity transmission，Its collapse destroyed will causes adverse to the social and economic effects，The mechanism of the power transmission tower collapsed caused peoples attention.The analysis is based on LS-DYNA program，explicit beam161 beam element is adopted to establish the finite element model for transmission towers，Analyses the collapse process of transmission tower and its failure mode with downburst load.

Fatigue Life Numerical Prediction of Butt Welded Plate under Cyclic Loading

Fatigue failure of welded structure has been highly concerned in structural engineering field. At present, the numerical simulation method has been actively applied on fatigue life prediction of welded structures. In this paper, welding residual stress of a butt welded plate was simulated by thermal elastic-plastic finite element method, and welding residual stress relaxation behavior under overload was analyzed. Then, the fatigue life of the welding plate under cyclic loading was numerically predicted with considering the welding residual stress and welding residual stress relaxation, and the result was compared with that calculated according to current steel structures design code of China. The results show that, considering fatigue reliability, the fatigue life calculated based on design formulas of the steel design code is more conservative, and numerical method for fatigue life prediction of welded structures, considering the welding residual stress and welding residual stress relaxation, is a feasible method.

Research on a Novel Soft Starting Method of Super High-Power and High-Voltage Motor

The supper high-power and high-voltage motors are characterized by high staring current, low power factor and a large number of higher harmonic currents. Under different loads, the parameters such as the staring current, reactive power consumption, and harmonic current, are nonlinear, variable and coupling. Therefore, a novel soft starting method of super high-power and high-voltage motor is presented in this paper, to achieve quick and smooth motor starting; keep the power factor and the 5th harmonic current in permitted ranges. The following works have been done in the study: design the structure, analyze the principle and advance a cooperative control method of the system to integrate voltage-adjusting, current-limiting, dynamic compensation and harmonic filtering. The soft starter of super high-power and high-voltage motor developed with this method has been successfully applied to the fans load of 10kV, 21000kW, and got the better effect.