发电机组紫外成像仪介绍

1、Ofils proprietary materialCannot be used without Ofils explicit consentHV Rotating Machines高压旋转机高压旋转机Ofils proprietary materialCannot be used without Ofils explicit consentCIGRE Study Committee SC11, EG11.02, “Hydrogenerator Failures Results of the Survey“, (2003)2003年国际大电网研究委员会“水轮发电机故障调查结果”Statisti

2、cs of 1,199 Hydro Generators1,199部水轮发电机资料统计部水轮发电机资料统计Insulation failure is a significant root cause for the breakdown of high voltage rotating machines.绝缘故障是高压旋转机故障的主要根源Ofils proprietary materialCannot be used without Ofils explicit consentInterface Interface DustingDusting界面尘埃界面尘埃Slot Exit Slot Exi

3、t DustingDusting槽口尘埃槽口尘埃Slot Section Slot Section DustingDusting狭槽部分狭槽部分尘埃尘埃End Winding End Winding DustingDusting绕组末端绕组末端尘埃尘埃Connection Connection DustingDusting连接处尘埃连接处尘埃 SLOT DISCHARGE 狭槽放电狭槽放电 Occurs when the coils become loose, causing the winding capacitive charging current to be dissipated to

4、 ground through concentrated contact points. 发生在当线圈变松弛时，导致绕组 电容充电电流电流通过集中接触点从地从地 线被空耗掉线被空耗掉。 Left to continue, this phenomena will eventually compromise the ground wall insulation system and result in a winding failure to ground. 照此情形下去，这种现象最后将危危及主绝缘系统的安全及主绝缘系统的安全，并导致绕组绕组的地线故障故障。Ofils proprietary ma

5、terialCannot be used without Ofils explicit consentOfils proprietary materialCannot be used without Ofils explicit consentAny kind of conductive contamination from moisture or oil mixed with dust/dirt affects a machine as electrical tracking develops across the blocking or along the end arms. 当电子轨迹穿

6、越阻隔或沿臂端扩展，各种因潮湿或混杂灰尘混杂灰尘/污垢污垢的油类而形成的传导污染传导污染 会影响机器。The electrical tracking occurs since a conductive path between two adjacent coils of different potential is created, and often from different phases. 由于在在2个相邻的不同潜能线圈之间形成了传导路径个相邻的不同潜能线圈之间形成了传导路径，并且通常来自不同相线，电子轨迹轨迹因此就会出现。This means once the contaminati

7、on is removed, this corona activity will cease. 也就是说，一旦污染被清除污染被清除，电晕活动将会停止电晕活动将会停止。Left uncorrected, permanent phase-to-phase or phase-to-ground deterioration may occur and eventual failure of the ground-wall is possible. 留下错误的、永久性相线对相线或相线对地线恶化恶化，并可能造成主绝缘故障主绝缘故障。Ofils proprietary materialCannot be u

8、sed without Ofils explicit consentCorona Spots电晕点 Corona severity indication Photons/ Sec 电晕严重显示 光子/ 每秒 GE发电机发电机Ofils proprietary materialCannot be used without Ofils explicit consentVoltage 24Kv 电压24千伏 Voltage 31Kv 电压31千伏Corona Spots电晕点 Quantitative indication 量化显示Ofils proprietary materialCannot b

9、e used without Ofils explicit consent地点：以色列地点：以色列 Alon Tavor2003年年5月月20日正常操作电压下，发电机定子产生的弱电日正常操作电压下，发电机定子产生的弱电晕晕Ofils proprietary materialCannot be used without Ofils explicit consentThe Case 个案个案:Stress-Grading Systems in Hydro-Generators水轮发电机应力分级系统水轮发电机应力分级系统 (Hydro-Qubec 魁北克水利发电公司魁北克水利发电公司)Present

10、ed in 展示于展示于:Iris Rotating Machine ConferenceJune 2007, San Antonio, TX 22007年年6月在圣安东尼奥举办的爱丽丝旋转机会议月在圣安东尼奥举办的爱丽丝旋转机会议Priority 1 signs of the corona effect Ofils proprietary materialCannot be used without Ofils explicit consentTHE FAULT 缺陷缺陷Stress-Grading coatings controls the E field in stator end-wi

11、ndings 要点- 分级镀膜在定子终端绕组控制控制E场场Such coatings are tricky to design and implement. 这个镀膜对于设计和实用来说有些微妙。The white powder attack and decompose the insulating material. 白色粉末在攻击和分解绝缘材料。Inspections revealed white powder at the junctions and grading coatings in stator windings which results from surface dischar

12、ges. 检查显示显示位于接合处以及定子绕组分级镀膜上的白色粉末因表面放电而产生白色粉末因表面放电而产生。Such defects were even seen on stator windings with only 4 years of service. 这个缺陷甚至可以在仅服务服务4年年的定子绕组上发现。“Corrective action must be taken to remedy the deterioration before it becomes critical or breakdown. This entails shutting down generating unit

13、s, which is clearly undesirable in an increasingly competitive market for electricity sales”“必须采取改进措施在问题严重或故障发生之前消除恶化。以避免蒙受关闭发电装必须采取改进措施在问题严重或故障发生之前消除恶化。以避免蒙受关闭发电装置而造成损失，这在电力销售日益竞争激烈的市场是不期望看到的置而造成损失，这在电力销售日益竞争激烈的市场是不期望看到的”Signs of discharges on a winding after just 4 years of service一个服务4年绕组的放电迹象Ofi

14、ls proprietary materialCannot be used without Ofils explicit consentTHE PHENOMENON 现象现象When E field along the surface of the end-winding coating is higher than the dielectric breakdown field of air Corona will appear. 当沿着终端绕组镀膜的E场高过非传导性的空气绝缘，电晕就会出现。The local current density can be very high causing

15、it to burn. 局部电流密度会非常高，导致燃烧。This will cause the Corona to appear in the slot and may lead to breakdown of the ground- wall insulation. 这将导致电晕在狭槽出现，可能引发主绝缘故障。Corona will occur due to: scratches, chipped paint, inadequate spacing, miss-positioned RTD cable and more. 电晕的产生是因为：刮痕、漆面剥落、间隙过窄、错位RTD导线等。“Cor

16、ona will cause breakdowns inside the slot near the slot exit with marked signs”“电晕会在狭槽出口标注处导致故障电晕会在狭槽出口标注处导致故障”Ofils proprietary materialCannot be used without Ofils explicit consentCORRECTIVE ACTIONS 改正措施改正措施Testing ensures that defects did not slip in during assembly, PD measurements can be used t

17、o quantify the intensity of corona discharges at junctions. 检测可以确保在安装过程中摒弃缺陷，局部放电测量可以量化结合处的电晕放电强度。Using silicon carbide stress-grading tape instead of the paint used earlier. 用碳化硅应力-分级胶带来取代早期使用的上漆法。Spots with visible PDs must be repaired by sanding, cleaning or applying stress-grading paint. 可见放电点必须

18、通过打磨、清理或采用应力分级漆。signs of the corona effect 电晕效果的痕迹电晕效果的痕迹“Corona inception voltages as low as 5.2 kV were recorded at the stress-grading junction. 电晕的初始电压低至电晕的初始电压低至5.2 kV，记录在应力分级接合处。，记录在应力分级接合处。Such values are clearly unacceptable since bars on the phase side of the stator-winding are permanently s

19、ubjected to higher voltages”这个值很明显不能接受，因为定子绕组相线一侧的铁栅这个值很明显不能接受，因为定子绕组相线一侧的铁栅永远面对的是高压。永远面对的是高压。Ofils proprietary materialCannot be used without Ofils explicit consentRESULTS OF UV INSPECTION 紫外检测结果紫外检测结果Photographs were selected to clearly show defects. 选定照片清楚显示缺陷。选定照片清楚显示缺陷。Maintenance staff could t

20、hus assign a priority to each site showing signs of the Corona. 维修人员可以根据电晕痕迹的程度排定维修的优先次序。维修人员可以根据电晕痕迹的程度排定维修的优先次序。UV camera view of the corona discharge at the junction紫外成像仪观测接合处的电晕放电UV camera view of the corona discharge at the junction紫外成像仪观测接合处的电晕放电Ofils proprietary materialCannot be used without

21、 Ofils explicit consentRESULTS FROM VARIOUS INSPECTION MODES 各种检测模式结果各种检测模式结果Capacitive Coupler 电容耦合电容耦合Often impossible to detect the external discharge trigger threshold at the junction. 通常无法在接合处引发界限检测到外部放电。Cannot be used for simultaneous detection on several bars. 不能用于同时检测几条线管。Ultrasonic 超声波超声波Se

22、nsitive to both internal and external discharges. 对内部和外部放电都很敏感。Impossible to get close enough to distinguish between internal and external discharges. 无法接近区分内部和外部放电。 Detection from a distance greatly reduces the instruments spatial resolution. 远距离检测会极大降低仪器的空间解析度。Impossible to take simultaneous measu

23、rements on several bars. 无法同时检测几条线管。Ofils proprietary materialCannot be used without Ofils explicit consentRESULTS FROM VARIOUS INSPECTION MODES 各种检测模式结果各种检测模式结果Corona Probe electromagnetic 电晕电磁探测器电晕电磁探测器Detection is highly localized, covering an area of only 1 x 5 cm. 检测只限局部，覆盖范围只有1 x 5 cm。The dial

24、 gauge supplied with the probe could not detect corona discharges 与探测器一起提供的度盘式指示器不能侦测到电晕放电不能侦测到电晕放电Naked-eye 裸眼裸眼“Blackout test”, precise but requires for each set of bars, a 15-minute wait in complete darkness for the eye to become sensitive enough. “熄灯测试”，准确，但需要对每套线管进行侦测，在黑暗状态下需要等待15分钟使 眼睛足够敏锐。Ofi

25、ls proprietary materialCannot be used without Ofils explicit consentRESULTS FROM VARIOUS INSPECTION MODES 各种检测模式结果各种检测模式结果UV camera observations 紫外成像仪观测紫外成像仪观测 The most sensitive method and can be used to measure several bars simultaneously. 最灵敏的方法最灵敏的方法，可以用来同时检测几个狭长连线同时检测几个狭长连线。It is very safe sinc

26、e there is no need to be near the bars and it can be used under regular lighting conditions. 非常安全非常安全，因为不必靠近线管，而且可以在正常光线正常光线条件下使用。Observations must be made using a camera with adequate sensitivity to ultraviolet radiation of wavelengths shorter than 300 nm (UVB and UVC). 必须使用对短于300nm (UVB 和 UVC)波长的紫外辐射具有足够灵敏度足够灵敏度的成像仪观测。Testing 80 bars by batches of 7 to 10 bars takes about one-half day and is qu