润色下面这段话本毕业设计论文是4300MW发电厂二期工程电气部分初步设计。全论文除了摘要、毕业设计书之外还详细的说明了各种设备选择的最基本的要求和原则依据。 变压器的选择包括：发电厂主变压器、高压备用变压器及高压厂用变压器的台数、容量、型号等主要技术数据的确定；电气主接线主要介绍了电气主接线的重要性、设计依据、基本要求、各种接线形式的优缺点以及主接线的比较选择并制定了适合本厂要求的主接线； 厂用电

This graduation thesis presents the preliminary design of the electrical part for the 4300MW power plant phase II project. In addition to the abstract and graduation design book, the thesis also provides detailed explanations of the basic requirements and principles for equipment selection. The selection of transformers includes determining the number, capacity, and model of the main transformer, high-voltage backup transformer, and high-voltage plant transformer. The electrical main wiring is introduced with emphasis on its importance, design basis, basic requirements, advantages and disadvantages of various wiring forms, and the comparison and selection of the main wiring, and a suitable main wiring for the plant's requirements is developed. The plant electrical wiring includes the overall requirements for the plant electrical wiring and the design of the plant busbar wiring. Short-circuit current calculation is the most important part, and this thesis provides a detailed introduction to the purpose, assumptions, general regulations, calculation of component parameters, network transformation, and calculation of various short-circuit points. The selection of high-voltage electrical equipment includes the principles and requirements for the selection of busbars, high-voltage circuit breakers, isolating switches, current transformers, voltage transformers, and high-voltage switchgear, and verification and product-related introductions are carried out for these devices. Based on the design principles and requirements of the high-voltage distribution device introduced in this thesis and the 500KV distribution device, it is decided to adopt a phase-split medium layout for this plant's design. The planning of relay protection and automatic devices includes general principles, automatic devices, general regulations, and protection of equipment such as generators, transformers, and busbars, while lightning protection for the power plant and substation mainly focuses on the design of lightning rods and surge arresters. Additionally, drawings (main wiring, plan view, cross-sectional view) and tables are included in appropriate locations in the thesis to facilitate reading, understanding, and application