求助几篇英文学位论文

很感谢“旺点”为大家提供了一个相互帮助，相互学习的平台，今日由于需要几篇英文学位论文，现在向大家求助，希望能够帮忙啊，哈哈，具体信息如下：

1 A study of ferroresonance in distribution systems

· 【作 者】Coskerie; L. W.

· 【学位授予单位】University of Sydney

· 【学位名称】M.Eng.Sci.

2 Theory and practice of ferroresonance due to the single-phase switching of distribution transformers

· 【作 者】Baitch; Alexander.

· 【学位授予单位】University of N.S.W.

· 【学位名称】M.Eng.Sc.

3 A study of ferroresonance in distribution systems

· 【作 者】Coskerie; Leigh Wallace.

· 【学位授予单位】University of Sydney

· 【学位名称】M.Eng.Sc.

4 field testing,modelling and analysis of ferroresonance in a high-voltage power system

· 作 者】jacobson;david allan nils.

· 【学位授予单位】the university of manitoba(canada).

· 【学位名称】ph.d.

· 【导师姓名】menzies,r.w.

5.Study of the abnormal phenomena of capacitor voltage transformer (CVT) at Taiwan Power Company
Ke, Han.;

【作者单位】：The University of Texas at Arlington.

【学位】：Ph.D.

【授予年】：1996-01-01

【培养单位】：The University of Texas at Arlington.

【导师单位】：The University of Texas at Arlington.

【语种】：英语

【馆藏号】：AAI9634332

【分类号】：Engineering, Electronics and Electrical.; Energy.

【总页数】：126

【文摘】：

In a power system capacitor voltage transformer (CVT) is usually used to provide the low voltage replica of the high line voltage both in magnitude and phase for protective relays or meters. A large number of CVTs are installed in many substations in Taiwan Power Company (TPC) and have experienced abnormal phenomena while in operation. The problems of the CVTs involve the frequent firing or failure of the gas discharging tube in the CVT installed both in 345 KV and 161 KV systems. This dissertation has devoted to investigating the cause of the firing of the CVT's gas discharging tube.; Two possible causes to the problems are suspected. The first one is the ferroresonance. Ferroresonance, known as the result of the interaction between capacitor and saturable inductor, is able to produce sustained over-voltage and damage the devices. In this dissertation Electro-Magnetic Transient Program (EMTP) is used to study the mathematical model of the CVT provided by the manufacturer. The ferroresonance phenomena of CVT are observed by EMTP simulation, which shows that ferroresonance should not be the cause of the whole problems.; The second possible cause is the induced voltage. Any disturbance, for example switching operation or lightning, in a substation may result in strong induced voltage on the low voltage circuit. In this dissertation, the mathematical model of the induced voltage and program are developed and confirmed by the field tests of TPC. The program is proved to be a good tool for the simulation of the induced voltage. The simulations show that the induced voltage can be the cause of the tube's firing and recommendations are given to solve the problem.

6. The use of a magnetic model to analyze the load dependent behaviour of a power supply.
Lind, Magnus G. J.;

【作者单位】：The University of British Columbia (Canada).

【学位】：Ph.D.

【ISBN】：9780494198

【授予年】：2006-01-01

【培养单位】：The University of British Columbia (Canada).

【导师单位】：The University of British Columbia (Canada).

【语种】：英语

【馆藏号】：AAINR19895

【分类号】：Engineering, Electronics and Electrical.

【总页数】：165

【文摘】：

It has been known since the first half of the 1990s that power supplies based on the ferroresonant transformer technology are incompatible with certain more recent types of loads such as actively power factor corrected devices. This is an issue that still remains today. The objective of this thesis is to analyze whether a specific ferroresonant uninterruptible power supply, operating in line mode, can be controlled by a linear time-invariant controller. This work shows that whether the ferroresonant-based circuit can be compatible with the aforementioned type of load is dependent on the characteristics of the same.; The study includes a comprehensive nonlinear model of the controlled ferroresonant transformer also known as the controlled constant voltage transformer. Saturation is a normal mode of operation for this device. The level of detail includes winding resistances, core resistances, continuously nonlinear magnetizing inductances, tapped windings, and leakage inductances. A complete nonlinear state-space model of the power supply where the constant voltage transformer constitutes the major part is derived. The investigation encompasses stability evaluation of the device with several types of loads using a generalized approach.; For the analysis, the nonlinear system is converted into a linearized periodically time-varying system, which in turn is sampled by means of Poincare mapping to provide a discrete-time representation of the model. An analytical approach explains, in the discrete-time domain, why certain loads may be impossible to control by a linear time-invariant controller. The study emphasizes this type of controller since in general, with unknown loads, the assumption is that the controller should be relatively simple and less dependent on specific load parameters or specific type of loads.; To complement the theory, this work also proposes an approximate procedure that leads to an implementation of a practical feedback controller that stabilizes a specific actively power factor corrected load. Laboratory experiments show that, for line mode operation, the power supply can indeed be compatible with the aforementioned load.