目前，电能在人们日常生活中的地位越来越重要，提高供电可靠性是供电系统面临的一项难题。变电站作为能源的集中和分散点，提高变电站的可靠性，是解决持续供电的问题的突破口。本论文针对此类问题，设计并开发出一套相对完整的监控系统，希望对解决此类问题有所帮助。 在理论上分析了两点成绩算法，傅立叶基数算法，结合变电站现场的实际工作状况，比较了两种算法的优缺点，决定采用傅立叶基数算法计算交流离散数字量的幅值、初相位和功率。 本文在分析监控对象的基础上，设计出系统硬件结构和软件。系统硬件由上位机、通信模块和下位机组成，本文主要设计了以89C51单片机为控制核心的下位机部分，主要包括8通道的A/D芯片的模数转换电路设计，RS232电平转换芯片构成通讯电路设计，6路开关量输出，4路开关量输入的数字量输入输出电路设计。软件方面，以vc++为设计平台，开发出通讯模块、实时曲线模块、历史曲线模块、数据报表模块、电气接线模块的等。论文同时也给出了硬件电路连接图和各个器件的使用方法，软件监控程序流程图和源程序。 本论文最后对监控软件功能进行了测试，以图片方式给出测试结果。本系统可靠、通用、适应性强，具有结构简单、易于扩展、操作方便、人机界面友好等特点。

At present, the electrical energy is getting more and more important in the people daily life. Enhancing the power supply reliability is a difficult problem for the power supply system . The substation is the spot of energy collection and distribution. Substation’s reliability may be question breach which is useful for continual power supplies. In view of this kind of question, a set of supervisory system is designed and developed, and we hope that it may be helpful for the problem. Two algorithms which are Fourier algorithm and two points algorithm have been analyzed theoretically.According to work condition and compared with two algorithm's good and bad points, Fourier algorithm that is used for caculating peak-to-peak value, the beginning of the phase and the power had been decided In view of monitoring object, the system hardware structure and software function were designed. The 89C51 MCU was the core of controlling. Gathering board was designed as the hardware platform. It mainly includes a 8 channel A/D chip, a RS232 chip which is useful for communication, circuit of digital input or output that was consist of 6 group digital outputs, 4 group digital inputs. On aspect of software, vc++ was take regard as platform. The communication module, the real-time curve module, the historical curve module, the data report form module and electrical wiring module were desigined. The diagram of hardware circuit connectionning and method of application for each component are gevin in the paper. the software monitor routine flow chart and the source program were finded Monitoring software was tested .the result would be showed in pictures. This system was reliable, easy to be expanded and operated .the man-machine interface was friendly.