【作者】 李洪涛；

【导师】 崔博文；

【作者基本信息】 集美大学 ， 轮机工程， 2011， 硕士

【摘要】 近年来普遍使用的小车开关柜的开关触点经常因接触不良,接触电阻增大,而出现触点温升过高,甚至烧毁,造成停电的现象,这种情况在大电流开关柜中更为突出。因此,对开关柜的触点温度在线监测具有十分重要的工程意义。由于高压绝缘和强电磁干扰等问题,普通的测温方法无法应用于此领域。本课题设计了一个光/电混合式测温系统,利用光纤的传输特性实现高压隔离传输,同时还对探头电路进行了低功耗设计,可以利用锂电池对其进行长期供电,从而解决在高压环境下不能从外部埋入电线进行供电的难题。本文首先对基本光电器件的特性进行了分析,合理选择了光纤、光源和光电探测器及其之间的耦合方式,设计了一个有效的光纤传输系统。在温度信号采集端,系统根据实际要求选用了无源的热敏电阻作为传感器,对整个测温探头电路全部采用CMOS微功耗集成芯片进行了低功耗设计,其中包括温度-脉冲频率调制电路的设计、脉冲宽度调制电路的设计和光源驱动电路的设计,最后还对整个探头电路的功耗进行了核算;在温度监测仪表端,设计了光电二极管前置放大电路,把光纤传输的光信号转换为同频率的电压信号,然后经过滤波整形处理,通过六通道测温切换电路送入单片机进行计数,最后实现通道转换、温度液晶显示、超温报警等功能;在软件方面,系统编制了数据采集、液晶显示、报警温度上限设置和数据线性化处理等子程序,满足了系统温度采集的各种功能的需要。本文还研究了在高电压、强电磁场的环境下如何保证系统的可靠性,提出了有效的绝缘和抗干扰措施。本课题在实验室现有的条件下,对整个温度采集和光纤传输系统的实现进行了测试,并采用恒温箱设置的温度对系统测量的温度进行了校验,结果表明:本课题所研制的高压开关柜触点温度在线监测系统温升越限报警准确,通道转换及温度显示反应速度较快,测温误差在±1 oC以内。更多还原

【Abstract】 With widespread of dyadic handcart switchgear recently, it often happened that the switch contact temperature rising, even burning down to power failure owing to the touch head poor contact and the increasing contact resistance. This situation is more common in switchgear with large current. Therefore, it has very important project significance to monitor switch contact temperature in switchgear online. Normal temperature measurements cannot be applied in this area because of the issues of high voltage insulation and strong electromagnetic interference. In the thesis,a light / electric hybrid temperature measurement system has been designed,taking advantage of characteristics of optical fiber transmission to achieve high voltage isolation, a low-power sensor circuit has also been designed, so it is impossible to solve the problems that cannot get power supply from buried wires external in the high voltage situation by using a lithium battery to supply power enduring.The basic characteristics of optoelectronic devices have been analyzed at first, choosing the optical fiber,light source,photo detectors and the coupling between each of two ,and an effective optical fiber transmission system is designed.In the temperature acquisition system, thermistors were used in the system and the micro-power CMOS integrated chip was used for low-power design in the whole temperature sensor circuit. The complete temperature sensor circuit includes temperature Pulse-Frequency modulation circuit, pulse width modulation circuit and the light source drive circuit. In the end, the power loss of entire sensor circuit is calculated in the thesis.In the temperature monitoring measuring system, the photodiode pre-amplification electric circuit has been designed, and fiber optic transmission’s light signal has been transformed into the same frequency voltage signal. Then the frequency voltage signal is sent to the monolithic integrated circuit to count through six-channel switching circuit which can control the signal channel, and the temperature is displayed via liquid crystal display, overtemperature alarm is realized. In software aspect, subroutines of he data acquisition, liquid crystal display, warning temperature upper limit, data linearization have been programmed for temperature gathering.This article also paid much attention to system’s reliability under high voltage and strong electromagnetic field environment, and the effective insulation and anti-jamming measures have been proposed.The temperature gathering and the optical fiber transmission system designed in this thesis has been conducted pilot testing under the laboratory existing condition, and the temperature measurement system have been rectified by setting the temperature of the thermostat. The testing results showed that the temperature online measuring system for measuring the temperature of switch contacts in the switchgear under high voltage has accurate warning for temperature arising over set limit, fast channel conversion and response speed.更多还原