摘  要:随着国民经济的增长的需要，我国电网覆盖面积日益扩大，于此同时，对供电系统的稳定性要求也日益提高， 备自投作为提高稳定性的自动投入装置已成为研究的重要课题。

　　　针对此类问题，本设计采用智能可编程控制器（PLC）来解决。该文以屏边倮姑水电站为例进行设计，主要对此类小型电站的站用电源备自投的设计。该设计论述了课题研究的目的、意义即在设计过程中遇到的问题和解决方法与措施。

　　　该文详细介绍了针对倮姑水电站站用电源备自投的总体实现方案设计，重点是缺相检测和运用PLC解决交流继电器的逻辑控制设计。通过缺相检测方案的设计，解决了PLC输入采样问题，为PLC动作提供逻辑输入，根据继电器控制要求设计PLC的控制模块。设计主要成果有三相电源缺相检测回路及设备选取，控制模块中有主电路图设计、I/O分配表、PLC控制接线图、梯形图及程序及PLC的选型。本文设计备自投系统性能良好、实现自动控制要求、动作灵活、操作方便、故障率较低、维护简单方便，实时解决了倮姑水电站站用电源备自投空缺问题，并满足了控制稳定性要求。

关键词：可编程控制器（PLC）；备自投；自动控制

ABSTRACT:Summary with the growth needs of the national economy,China's power grid covering an area of growing, at the same time, increasing demands on stability of power supply system, win equipment as inputs to improve the stability of automatic devices have become an important research topic.

　　　 For this type of problem, this design uses intelligent programmable controller (PLC) as a solution. The case study of pingbian County  Kou hydropower station design, intended for such small power plants power automatic bus transfer station design.     

　　　 The design addresses the purpose, meaning that research problems and solutions encountered during the design process and measures. Which provides a detailed description of  Kou hydropower station with power into the overall solution design, focusing on the missing phase detection and application of PLC address AC relay logic control design. Through the design of phase detection scheme, solve the PLC input sampling issues, provide logic for the PLC input, according to the black-white control design of PLC control module. Main results have a three-phase power supply missing phase detection circuit design and equipment selection, design of main circuit diagram in the control module, I/O allocation table, PLC control wiring diagram, and PLC ladder diagram and procedure selection. This good performance, to achieve automatic control design of automatic bus transfer system requirements, flexibility, ease of operation, low failure rate, maintenance is simple and convenient, real time  Kou hydropower station with power automatic bus transfer vacancies and control stability requirements are met. 

Key words: programmable logic controllers (PLC); automatic bus transfer;       automatic control