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。
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.
引文
[1]胡春海,邹晓红,王玉田.光纤荧光温度传感器用于高压设备温度在线监测的研究[J].工业仪表与自动化装置,2004,(5):53-54.
[2]巩宪锋,衣红钢,王长松,等.高压开关柜隔离触头温度监测研究[J].中国电机工程学报,2006,26(1):155-158.
[3] Huang Xiping, Wang Xin, Qiang Wen. Development of On-line Monitoring Equipment of Medium Voltage Switchgear [J].The Eighth International Conference on Electronic Measurement and Instruments, 2007, (3): 388-392.
[4] Theocharous, E.Differential Absorption distributed Thermometer [J].IEE Conference Publication, 1983, (221):10-12.
[5] Thermo Physieaminima.Thermoelectric infrared sensors (thermopiles) for remote temperature measurements [J].PerkinElmer Company, 2000,(4):140-143.
[6]张家伟.变电站高压开关柜接点温度在线监测系统研究[D].北京:华北电力大学,2005.
[7]孙剑.高压开关柜触点温度在线监测仪设计[D].北京:北京化工大学,2008.
[8]苑舜.高压开关设备状态监测与诊断技术[M].北京:机械工业出版社,2001.
[9]徐予生.Fiber optic sensor technology handbook [M].北京:电子工业出版社出版,1987.
[10]陈振生,王嘉.基于Zigbee技术的高压开关触点温度在线监测技术[J].电工电气,2010,(5):44-46.
[11]廖雪松.高压开关柜在线温度监测系统的研究[D].南昌:南昌大学,2007.
[12]张越.高压开关温度在线监测技术的研究[D].秦皇岛:燕山大学,2001.
[13]费万民,吕征宇,耿福江,等.高压开关触点和母线温度在线检测与监视系统[J].电力系统自动化,2004, 28(3):86-89.
[14]陈振生.智能高压开关设备的在线监测技术[J].电力设备,2008, 9(3):5-8.
[15] L.Balgard,L.Lundin.Monitoring Primary Circuit Temperature and Breakers Condition in MV Substations [J].ABB Review 1993,(3): 21-26.
[16] Kawai T,Takinami N,Chino T,et al. A new approach to cable fault location using fiber optic technology [J].IEEE Transaction on Power Delivery, 1995,10(1):85-91.
[17] Inoue N,Tsunekage T,Sakai S. Fault section detection system for 275 kV XLPE insulated cable with optical sensing technology [J].IEEE Transaction on Power Delivery,1995,10(3):1148-1151.
[18] Tayama H,Fukuda O,Inoue Y,et al. 6.6kV XLPE submarine cable with optical fiber sensors to detect anchor damage and defacement of wire armor [J].IEEE Transaction on Power Delicery,1995, 10(4):1718-1723.
[19]周剑利,郭建波,藤峰成.基于高压开关设备的光纤在线测温仪[J].微计算机信息(测控自动化),2005,21(7-1):142-143.
[20]肖文,崔瑜.光纤传感器系统中的功能光纤[J].光子学报,1997,29(1):41-45.
[21]王惠文,江先进.光纤传感技术与应用[M].北京:国防工业出版社.2001.
[22]潘向东.光纤传输光推动电流互感器的研究[D].秦皇岛:燕山大学,1998.
[23]彭吉虎,吴伯瑜.光纤技术及应用[M].北京:北京理工大学出版社,1995.
[24]王玉田,郑龙江.光电子学与光纤传感器技术[M].北京:国防工业出版社,2003.
[25]顾碗仪,李国瑞.光纤通信系统[M].北京:北京邮电大学出版社,1999.
[26]彭吉虎,吴伯瑜.光纤技术及应用[M].北京:北京理工大学出版社,1995.
[27]付文羽,彭世林.硅光电二极管在光电检测电路中的应用研究[J].许昌师专学报,2001,20(5):19-22.
[28]张国顺,何家祥,肖桂香.光纤传感技术[M].北京:水利电力出版社,1988.
[29]廖延彪.光纤光学[M].北京:清华大学出版社,2000.
[30]何希才.传感器技术及应用[M].北京:北京航空航天大学出版社,2004.
[31]王化祥,张淑英.传感器原理及应用[M].天津:天津大学出版社,2002.
[32]沈雷.CMOS集成电路原理及应用[M].北京:光明日报出版社,1986.
[33]张玉艳.光推动差动电容式油罐液位测量系统的研究[D].秦皇岛:燕山大学,2001.
[34]李远明,陈文涛.微弱光信号前置放大电路设计[J].电子元器件应用.2007,9 (8):51-53.
[35] Walt Jung,张乐锋译.Op Amp Applications Handbook[M].北京:人民邮电出版社,2009.
[36]严福兴.极微弱光电流测量电路的设计[J].武汉理工大学学报.2006,28(11):114-116.
[37]滕宪斌.船舶柴油机曲轴臂距差影响因素分析及数字显示测量仪研究[D].厦门:集美大学,2008.
[38]梅丽凤.单片机原理及接口技术[M].北京:清华大学出版社,2006.
[39]徐爱钧.智能化测量控制仪表原理与设计(第二版)[M].北京:北京航空航天大学出版社,2004.
[40]李昌禧.智能仪表原理与设计[M].北京:化学工业出版社,2005.
[41]魏敬和,张震宇.强电磁场中温度测量技术的研究[J].光电子技术,1998,18 (1):80-83.
[42]任稳拄,冯建华,王小英.高压测量系统的抗干扰性技术[J].高压电器,1999,1(4):21-23.
[43]朱军.发电厂高压开关状态检修研究[D].武汉:武汉大学,2004.
[44]孙宏军,张涛,王超.智能仪器仪表[M].北京:清华大学出版社,2007.
[45]凌志浩.智能仪表原理与设计技术[M].上海:华东理工大学出版社,2003.