大型火电厂低压厂用电系统快切技术的研究

发布时间：2018-05-10 08:03

本文选题：厂用电 + 快速切换　；参考：《华北电力大学(北京)》2017年硕士论文

【摘要】：随着我国电力行业的发展,火力发电厂的装机容量越来越大,对厂用电的供电的可靠性和连续性要求越来越高。虽然我国规定暗备用的低压厂用电源切换采用手动切换方式,但随着我国电力企业的“走出去”,为了满足国际上许多国家要求低压厂用电必须具有快速功能,低压厂用电快速切换的研究亦十分的必要。研究厂用电的工作母线失电残压变化情况,分析低压厂用电切换的条件,在最有利的时刻迅速完成切换操作,可以提高厂用电的安全可靠性和连续性,对整个电力系统的安全亦具有重大意义。本文研究内容主要有以下方面:大量阅读文献,搜集数据,对国内外快速切换的现状进行分析,阐述研究快切在低压厂用电应用的意义。因发电厂主要负荷为感应电动机,所以理论分析感应电动机的暂稳态运行状态,并且对火电厂的负荷分类、计算原则和方法进行分析,对感应电动机恢复供电后的自启动分类、校验方法进行介绍,对感应电动机允许自启动的最低电压和允许感应电动机群启动的工作母线的最低电压进行理论分析研究,对快速切换的原理及切换方式进行了研究与分析。本文以湄州湾厂用电为基准,应用实际电厂网络结构,采用实际电厂数据,应用ETAP仿真软件,搭建大型火电厂厂用电模型,主要仿真分析低压厂用工作母线失电后,工作母线残压的变化过程,根据快速切换的切换原理及现场运行状态,分析实际电厂低压厂用电中感应电动机负荷较多的五条母线的残压变化情况,分析低压快切可能遇到的问题。并仿真分析了切除部分小容量的感应电动机后,工作母线的残压变化情况,并仿真分析了快切的几种切换方式的暂态过程。对比切除部分小容量电动机前后的残压变化差异。为了确保低压厂用电的安全,本文采取逆变电源装置辅助实现低压厂用电的快速切换,在低压工作母线断电的瞬间,切除部分小容量的异步电动机,然后利用逆变电源给切离工作母线的小容量电动机单独供电,分析研究逆变电源的特性及其控制方式,控制逆变电路,使逆变装置的输出电压与备用电源一致,当快切装置成功动作,即备用电源成功给原工作母线供电后,则选择将小容量电动机再次投入工作母线,同时切除逆变电源,成功使用逆变装置辅助实现低压厂用电的快速切换,提高厂用电的连续性和可靠性。
[Abstract]:With the development of electric power industry in China, the installed capacity of thermal power plants is becoming larger and larger, and the reliability and continuity of power supply for auxiliary power are becoming more and more important. Although our country prescribes manual switching for low-voltage power supply switching, but with the "going out" of Chinese power enterprises, in order to meet the requirements of many countries in the world, low-voltage auxiliary power must have a rapid function. It is also necessary to study the fast switching of low voltage auxiliary power. By studying the variation of the residual voltage of the working busbar, analyzing the condition of the switching of low voltage, and completing the switching operation quickly at the most favorable time, the safety, reliability and continuity of the power supply can be improved. It is also of great significance to the safety of the whole power system. The main contents of this paper are as follows: reading a lot of literature, collecting data, analyzing the current situation of fast switching at home and abroad, and expounding the significance of research on the application of fast cutting in low voltage auxiliary power. Because the main load of power plant is induction motor, the transient steady state of induction motor is analyzed theoretically, and the load classification, calculation principle and method of thermal power plant are analyzed, and the self-starting classification of induction motor after restoring power supply is analyzed. The method of calibration is introduced. The minimum voltage of self-starting of induction motor and the minimum voltage of busbar of induction motor group are analyzed theoretically. The principle and mode of fast switching are studied and analyzed. In this paper, based on Meizhou Bay power plant, the actual power plant network structure, actual power plant data and ETAP simulation software are used to set up the power model of large thermal power plant. According to the switching principle of fast switching and the field operation state, the variation of the residual voltage of the induction motor with more load in the low voltage auxiliary power plant in the actual power plant is analyzed according to the changing process of the residual voltage of the working busbar. Analyze the problems that may be encountered in low pressure fast cutting. The variation of residual voltage of the bus after removing some small capacity induction motors is simulated and the transient process of several switching modes is simulated and analyzed. The difference of residual voltage before and after removal of partial small-capacity motor is compared. In order to ensure the safety of low voltage auxiliary power supply, this paper adopts the inverter power supply device to realize the fast switching of low voltage auxiliary power supply. At the moment of low voltage busbar power failure, some small capacity asynchronous motors are excised. Then the inverter is used to supply the small capacity motor which is cut off the busbar. The characteristics of the inverter and its control mode are analyzed and studied. The inverter circuit is controlled so that the output voltage of the inverter is the same as that of the standby power supply. When the quick cutting device is successfully operated, that is, the backup power supply successfully supplies the original busbar, then the small capacity motor is selected to be put into the working bus again, and the inverter power source is removed at the same time. The inverter device is successfully used to realize the fast switching of low voltage auxiliary power and to improve the continuity and reliability of the power supply.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM621

【参考文献】