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1、上海交通大学硕士学位论文工频试验设备计算机控制系统姓名：饶强申请学位级别：硕士专业：高电压与绝缘技术指导教师：赵刚20090101I工频试验设备计算机控制系统 工频试验设备计算机控制系统 摘 要 摘 要 交流耐压试验是交流电气设备最重要的试验项目，是考验被试品绝缘承受交流电压能力的有效方法。它能有效地发现绝缘缺陷，对保证设备安全运行具有重要意义。工频耐压试验一般采用试验变压器来获得高电压。国家标准 GB/T 16927.11997 对试验电压的波形与容许偏差有明确的规定，要求试品上的电压跟踪预期电压时间曲线，并且试验电压的测量值应保持在规定值%1以内；同时对试验程序也有明确的要求。实际工程中手
2、动控制难以跟踪其电压时间曲线，也难以控制调压器的升降压速度，所以我们有必要开发一套工频试验变压器计算机控制系统。 本系统采用 PLC 作为主要的控制元件，通过友好、强大基于 PC的用户操作界面实现对 PLC 控制，进而控制系统耐压过程，同时对试验电压电流等主要参数进行测量并实时显示在 PC 屏幕上。以前也开发过类似的系统，不过存在一个很主要的问题系统刷新率太慢，大约 2 至 3 秒才能刷新一次，这是由于 PLC 与 PC 通信速率过慢所导致的。所以本文主要完成以下工作：PLC 与 PC 直接通过串口通信的软件实现； PLC 软元件的规划以及用梯形图程序控制系统耐压过程；图像实时显示系统全局状态
3、和系统耐压状态；用户操作界面的具体规划和设计。由于考虑到工频试验回路可能发生串联谐振，所II以本文进一步证明了接触调压器非线性特征，并根据文献给出了仿真中可用的模型。 接着，本文设计了一个测试系统刷新率的方案并做了实验，结果证明效果不错，至少能达到每秒两次的刷新率。另外，笔者还在实验室建立了模拟试验电路，目的是检验系统能否作到对耐压试验的自动控制。结果证明该系统能够按照试验人员的要求，绘制电压时间曲线并让试品上的电压跟踪曲线同时实时显示此时电压的瞬时值；安装在电路中的电压电流继电器和快速保护装置能够在异常时刻切断电路以保证设备的安全；用户操作界面能够实时显示系统各关键参数，同时能实现其设计的功
4、能。最后，本文对现有系统的局限性做了一些说明，提出了研究的方向，希望能有更进一步的发展。实验的成功证明了该系统能够满足工程设计的要求，能够应用于实际工程中。 关键词：关键词：工频试验，交流耐压，计算机控制系统，PLC，人机界面 IIICOMPUTER-BASED CONTROL SYSTEM OF POWER FREQUENCY TEST EQUIPMENTS ABSTRACT AC Withstand Voltage test is the most important test item to AC electric equipments, is a valid method of try
5、ing out the ability of the insulation withstanding AC voltage of tested object. It can effectively discover the defect in insulation and has an important value on guaranteeing the safe operation of equipments. Power frequency withstand voltage test commonly acquires high voltage by testing transform
6、er. National standard GB/T 16927.1-1997 has a definitive prescript on the waveform and the tolerance of testing voltage, requesting the voltage on the tested object follows up the anticipative voltage-time curve and that the measured value on testing voltage must maintain between 99% and 101% to the
7、 prescriptive value. At the same time the standard also has a definitive prescript on the testing process. In actual projects it is difficult for hand control to follow up the voltage-time curve and control the speed of step-up and step-down for voltage regulator. So it is necessary for us to design
8、 a computer-based control system of power frequency testing transformer. The system chooses PLC as the main control element, realizing the IVcontrol of PLC through the friendly and powerful human-computer interface based on PC, further controlling the withstand voltage process of system. At the same
9、 time the testing voltage and the testing current .etc the main parameter is measured and is displayed on PC s screen. Someone also designed a similar system ago, but there is a main problem that the refreshing rate of system is so slow, refreshing about 2 to 3 seconds every time. This is because th
10、e communication speed between PLC and PC is so slow. So the article mainly has completed the next jobs: software realization of communication between PLC and PC directly through PC s serial port; programming for soft elements in PLC and design for ladders to control the withstand voltage process of
11、system; design for images displaying the global state of system and withstanding voltage state of system; detailed programming and design for the interface of users operation. Because considering that power frequency test circuit in test may occur series resonance, the article further proves the non
12、-linear feature of variable voltage transformer and gives an available model for simulation according to the reference. In succession the article design a scheme for testing the refreshing rate of system and has done the experiment. The outcome proves that it has an good effect on the system and rea
13、ches the refreshing rate of 2 times per second. In addition, the author has established a simulative testing circuit in lab, in order to verify if the system can control the Vwithstand voltage test process or not. It proves that the system can plot voltage-time curve in the opinion of the requiremen
14、ts of experimentalist, and makes the voltage on the tested object follow up the voltage-time curve, at the same time displaying the instantaneous value of current voltage. The voltage relay and the current relay installed in circuit and the quick-speed protection equipment can cut off the circuit at
15、 an abnormal time to guarantee the security of equipments. The human-computer interface can display all the key parameters of system, realizing the designed function. At last, the article makes a declaration of the localization of this system and puts the direction of research forward, in the hope o
16、f the further development in this system. The success in test proves that the system has reached the requirements of project design and it can be applied in actual projects. KEY WORDS: power frequency test, AC withstand voltage, computer based control system, Programmable logic Controller， human-computer interface 工频试验设备计算机控制系统 上海交通大学硕士学位论文 1第一章 引言 第一章 引言 1.1 工频交流耐压试验计算机控制系统 1.1.1 课题背景 1.1 工频交流耐压试验计算机控制系统 1.1.1 课题背景 电力系统中的各种电气设备在运行时， 除承受交流或直流的工作电压以外，还非常有可能
