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1、基于TMS320F2812的SF6气体参数在线监测系统宋锦刚1，马宏忠2（1. 江苏财经职业技术学院机电系, 江苏淮安 223003; 2. 河海大学电气工程学院, 江苏南京 210098;）摘要：介绍了一种基于快速数字信号处理芯片TMS320F2812和压力、温度及相对湿度传感器的SF6气体密度和微水含量在线监测方法。详细讨论了SF6气体密度、微水含量与温度、压力的关系，并给出了硬件框图及相应模块的接口电路设计和监测单元的部分软件实现。数据处理模块采用TMS320F2812芯片，充分发挥了其强大的数字信号处理能力，速度快，精度高。另外，丰富的片内资源有效地简化了设计的复杂性，增强了系统的电磁
2、兼容性，降低了设计成本，从而使得该系统具有较好的应用前景。关键词：SF6气体；在线监测；数字信号处理器中图分类号：TP277 文献标识码：B0 引言近年来SF6断路器在高电压领域得到了越来越广泛的应用。然而SF6断路器在运行时，不可避免地会发生设备内SF6气体向外泄漏而导致密度下降的现象。有关统计资料表明，在SF6断路器的故障中，由SF6气体泄漏引发的故障约占38%1。而在SF6气体泄漏的同时，设备外部潮气也会渗透进设备内部，引起设备内SF6气体中微水含量的增加。当SF6气体中微水含量过高时，会使高压电器设备运行存在安全隐患，主要表现为：SF6气体在电弧作用下的分解物遇水时会发生化学反应生成具
3、有强腐蚀性的HF和H2SO3等，会腐蚀损坏绝缘件，并随SF6气体一同向外泄漏，危害人体健康，还增加了环境中的温室效应；在温度降低时SF6中的水蒸汽可能形成凝露，使绝缘件表面绝缘强度显著降低甚至出现闪络。按照GB/T8905-1996六氟化硫电气设备中气体管理和检测导则规定，在电气设备充气前和运行中必须对SF6气体进行质量监督和管理，保证电气设备的安全运行。1 SF6气体密度在线监测方法工程实际中，SF6气体密度的直接监测是不易实现的，通常是转化为对压力的监测。但即便是密度恒定时，SF6气体的压力也要随温度发生变化。因此，为了准确反映压力变化是由于漏气而非温度改变引起的，就必须通过适当的修正方法
4、，使压力指示仪表无论外界温度如何改变，示数始终为对应20的标准压力，并将该值等效为气室内SF6气体的密度值以便与参考值比较。由上分析可知，SF6气体密度在线监测系统需要采集温度和压力2个特征量，并对这2个特征量进行适当修正，从而实现在线监测。修正运算公式利用的是最常用的SF6气体状态参数方程，即Beattie-Bridgman方程2： 式中 -SF6气体实时压力，Mpa；T-温度，K；-密度，。2 SF6气体微水含量在线监测方法SF6气体微水含量在线监测系统需要采集湿度、温度和压力3个特征量。通常工业现场是采用温度为20时的SF6气体的湿度值作为微水含量的参照标准。因此，为了使测量结果具有可比
5、较性，需要应用公式(4)、(5)、(6)对所测量的相对湿度值进行修正，以便与参考值进行比较，从而实现在线监测3。 (4) (5)式中-实时饱和水汽压，Pa；-空气的热力学温度，K；-水的三相点温度，K。 式中-相对湿度；-实时水蒸气分压力，；含义同前式。-实时含水量，；含义同前式。-修正到20时的微水含量，；-修正到20时的SF6气体压力，；-20时的水蒸汽饱和压力（可以取2336），。3 SF6气体参数在线监测系统的硬件实现SF6气体参数监测系统由每台断路器上配装的SF6气体参数监测单元和一台PC构成。PC作为上位机接收每台SF6断路器在线监测单元的上传数据，负责全站SF6气体参数的监测和管
6、理。上位机和SF6气体参数在线监测单元之间通过RS485总线实现采集数据和控制命令的传输与通信。每个SF6气体参数在线监测单元硬件结构主要包括数据采集模块、数据处理模块、数据传输模块和辅助功能模块。其中数据采集模块主要包括传感器、A/D转换芯片；数据处理模块主要由DSP构成；数据传输模块主要包括串口通信驱动芯片；辅助功能模块主要包括报警、闭锁、显示电路及电源电路。监测单元硬件框图如图1。图1 SF6断路器在线监测单元硬件框图3.1 数据处理模块数据处理模块选用美国TI公司32 bit定点 TMS320F2812芯片，TMS320F2812是TI公司面向工业控制领域推广应用的32位定点DSP芯片
7、。它既具有数字信号处理能力，又具有事件管理能力和嵌入式控制功能，适用于有大批量数据处理的测控场合，如工业自动化控制等4,5。3.2 数据采集模块温度传感器选用美国AD公司生产的单片集成两端感温电流源器件AD590。湿度传感器选用法国Humirel公司的HM1520湿敏传感器。为拆装方便，将湿度传感器探头安装在设备取气口外的在线监测测量的腔体中，这样通过取气腔体与被测气体的自扩散相连通。压力传感器选用量程为，型号为CYB13M的压力传感器。A/D转换芯片选用ADS8364芯片，该芯片采用模拟和数字电源，内部有可以采用的缓冲，因此可以和F2812直接接口而无须电平转换。TMS320F2812的Mc
8、BSP与ADS8364的连接如图2所示6,7。图2 ADS8364与TMS320F2812接口电路3.3 数据传输模块PC与TMS320F2812采用RS485串行通信模式。驱动芯片选用Maxim公司生产的MAX3160型收发器8，接口电路如图3。图3 TMS320F2812的串行通信接口电路4 SF6气体参数在线监测系统的软件实现监测系统的软件设计主要包括各功能模块初始化程序、数据采集程序、SF6气体密度、微水含量修正程序、串口通信程序以及上位机程序等。其中图4给出的是在线监测单元的主程序流程，图5给出的是SF6气体密度、微水含量的计算和修正程序流程。图4在线监测单元主程序流程 图5 SF6
9、气体密度、微水含量的计算和修正程序流程5 结论本文提出基于TMS320F2812的SF6断路器气体密度及微水含量在线监测方法。详细给出了监测系统的硬件实现及部分软件设计。该系统依靠TMS320F2812强大的数字信号处理能力，有效的保证了监测的实时性和准确性，试验表明使用效果良好。另外，由于芯片具有丰富的片内资源大大简化了系统软、硬件设计，增强了系统可靠性，降低了成本，因此该系统具有较好的应用前景。参考文献1 刘亚芳.国内外高压SF6断路器运行状况及维修策略综述.电力设备,2002.2 方可行.断路器故障与监测.北京:中国电力出版社,2002.3 李艳秋,江秀臣,曾奕.SF6气体微水含量在线监
10、测方法及其软件实现.华东电力,2006,34(3).4 Texas Instruments.TMS320F28x DSP Event Manager (EV) Reference Guide. 2003:1205 Texas Instruments.TMS320F28x DSP Serial Peripheral Interface (SPI) Reference Guide. 2003.6 Texas Instruments. ADS8364 data manual.20047 Texas Instruments. Interfacing the ADS8364 to the TMS320F
11、2812 DSP.20028 +3.0V to+5.5V，1A，RS-232/RS-485/422 Multi protocol TransceiversZ.Maxim, 2000作者简介：马宏忠（1962）男，汉族，博士，教授，硕士研究生导师，主要研究方向：电气设备状态监测与故障诊断；宋锦刚，男，讲师，硕士研究生，研究方向：电气设备状态监测与故障诊断，E-mail： hhusjg；On-Line Monitoring System of SF6 Gas Parameters Based on TMS320F2812SONG Jin-gang1, MA Hongzhong2 (1. Jiang
12、su Vocational and Technical College of Finance & Economics, Huaian 223003, China; 2. Hohai University, Nanjing 210098, China; )Abstract: An on-line monitoring method of SF6 gas density and humidity is proposed, which is based on TMS320F2812, temperature, pressure and humidity sensors. The relationsh
13、ip among density, temperature and pressure is analyzed in detail. The relevant hardware diagram and partial software implementation is also discussed in detail. The digital signal processing capability is fully displayed by DSP TMS320F2812. It has high speed and accuracy. In addition, abundant resou
14、rces are integrated on the chip to optimize the system design efficiently, so the EMC capacity is enhanced and the cost of system is reduced. The system has good application prospect.Key words: SF6 gas; on-line monitoring; DSPEditors note: Judson Jones is a meteorologist, journalist and photographer
15、. He has freelanced with CNN for four years, covering severe weather from tornadoes to typhoons. Follow him on Twitter: jnjonesjr (CNN) - I will always wonder what it was like to huddle around a shortwave radio and through the crackling static from space hear the faint beeps of the worlds first sate
16、llite - Sputnik. I also missed watching Neil Armstrong step foot on the moon and the first space shuttle take off for the stars. Those events were way before my time.As a kid, I was fascinated with what goes on in the sky, and when NASA pulled the plug on the shuttle program I was heartbroken. Yet t
17、he privatized space race has renewed my childhood dreams to reach for the stars.As a meteorologist, Ive still seen many important weather and space events, but right now, if you were sitting next to me, youd hear my foot tapping rapidly under my desk. Im anxious for the next one: a space capsule han
18、ging from a crane in the New Mexico desert.Its like the set for a George Lucas movie floating to the edge of space.You and I will have the chance to watch a man take a leap into an unimaginable free fall from the edge of space - live.待添加的隐藏文字内容3The (lack of) air up there Watch man jump from 96,000 f
19、eet Tuesday, I sat at work glued to the live stream of the Red Bull Stratos Mission. I watched the balloons positioned at different altitudes in the sky to test the winds, knowing that if they would just line up in a vertical straight line we would be go for launch.I feel this mission was created fo
20、r me because I am also a journalist and a photographer, but above all I live for taking a leap of faith - the feeling of pushing the envelope into uncharted territory.The guy who is going to do this, Felix Baumgartner, must have that same feeling, at a level I will never reach. However, it did not s
21、top me from feeling his pain when a gust of swirling wind kicked up and twisted the partially filled balloon that would take him to the upper end of our atmosphere. As soon as the 40-acre balloon, with skin no thicker than a dry cleaning bag, scraped the ground I knew it was over.How claustrophobia
22、almost grounded supersonic skydiverWith each twist, you could see the wrinkles of disappointment on the face of the current record holder and capcom (capsule communications), Col. Joe Kittinger. He hung his head low in mission control as he told Baumgartner the disappointing news: Mission aborted.Th
23、e supersonic descent could happen as early as Sunday.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through
24、the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he
25、 crosses the boundary layer (called the tropopause), he can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet (22.7 miles/36.53 kilometers). Here, Fearless Felix will unclip. He will roll back the door.Then, I would assume, he will slowly step out onto som
26、ething resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, hell be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into t
27、he shallow end.Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop h
28、im completely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes its not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order t
29、o deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it wont. Baumgartner still will free fall at a speed that would cause you and me to
30、pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).It might not be the moon, but Kittinger free fell from 102,800 feet in 1960 - at the dawn of an infamous space race that captured the hearts of many. Baumgartner will attempt to break that record, a feat that boggles the mind. This is one of those monumental moments I will always remember, because there is no way Id miss this.
