毕业设计[论文]题目：雷电对变电站二次设备的电磁干扰分析

ude sources of interference require an isolation between the source and a potential victim that is equally broadband. The redesign required to accommodate broadband immunity measures, and the recognition that the procedures used to control the effects of a HEMP are applicable to the control of any broadband, high-amplitude source, led to an extensive review of existing interference control techniques and practices. If we postulate that interference control is a broadband electromagnetic separation between an objectional source and a potential victim, electromagnetic topology will provide practical insights and the necessary tools to solve interference problems pulse power source from the associated diagnostic instrumentation will not conflict with any other isolation techniques that might be used for the experiment. Electromagnetic topology results in an overall system approach to interference control, with high confidence in meeting expected performance requirements. The fundamental principle is simple: to achieve broadband electromagnetic isolation of a source and a victim, the two must be separated by a barrier that is effectively impervious to electromagnetic energy. Although such a statement may appear overly simple, a thorough understanding of the implications of this simple statement leads to a very effective and practical approach to the stated problem. First we define an ideal barrier and then examine the compromises found in practical barriers. Whatever steps we take to ameliorate the compromises in the real barrier will help to achieve the required isolation; whatever steps we take that exacerbate the compromises will be detrimental. In the next section, we describe the ideal barrier. Although simple in concept, a thorough understanding of the ideal barrier is necessary to understand the compromises in a real barrier. This description will also help to clarify commonly used and misused terms in interference control. We continue with a discussion of the practical barrier and compromises of its ideal character in three areas: diffusion, apertures, and penetrating conductors. An understanding of these compromises is basic to the design of an effective barrier. The final section in this lecture discusses the inconsistent techniques found most frequently in grounding and cable shield terminations. The topological principles will give clear guidance in these areas. Some simple laboratory experiments are described that illustrate these concepts. A summary of interference control principles and some corollaries conclude this section. The ideal barrier is a physically and topologically closed surface that completely encloses either the source or the victim. The surface must have infinite conductivity and finite thickness, with no apertures or wire penetrations. Such a barrier completely separates two volumes of space in the electromagnetic sense: no electromagnetic information can be transmitted from one side of the barrier to the other side. The latter statement merely underscores one of the limitations of the ideal barrier; no distinction is made between signal and noise. The primary reason the ideal barrier is so effective is because it is closed, not because it is made of a superconducting surface. We will illustrate this point below when we discuss diffusion in a practical barrier. Also note that a barrier and a shield are not the same, although a shield is usuall