空气局部放电衍生物气体生成规律的研究

分解气体分析法通过检测故障产生的气体组分诊断设备故障,是检测电力设备故障的重要方法,在一些应用场合具有不可替代的作用。然而目前该方法只在绝缘油、SF6等绝缘介质的场合有应用,对于空气这一最重要的绝缘介质少有应用。本文搭建空气局部放电过程模拟实验平台及气体产物检测系统,研究放电衍生物气体生成规律。分别采用两种检测方式对气体产物进行检测,结果显示O_3、NO、NO_2为空气放电的主要产物;在放电强度较低时,空气放电主要分解产物为O_3,放电强度进一步增大可以检测到氮氧化物NO和NO_2的产生,且臭氧O_3浓度远大于氮氧化物气体浓度;对于封闭空间,随着放电时间增长分解产物浓度增加,但趋向饱和,且随着施加电压增大,气体产物浓度增加;而在相同放电电压下,空气相对湿度变化对气体产物含量有明显影响,O_3、NO_2的浓度在相对湿度为18%时高于相对湿度为25%和44%时的值;而NO的浓度在相对湿度为44%时高于相对湿度为18%和25%时的值,同时差异较小。

Study of air by-products formation characteristics under corona discharge

Decomposition gas analysis method (DGAM) which detects faults by measuring the decomposition gases under electrical fault is an important way for the faults detection,and is irreplaceable in some situations.However,it can be used only in oil or SF6 insulated equipment.Few applications have been found in air insulated condition.To build up a gas analysis method based on air by-products,the air by-products formation characteristics under corona discharge are studied by experiment simulation.A needle-plate corona discharge model and decomposition gases measuring system are established.The decomposition gases are detected under different discharge condition.The results show that O3,NO2 and NO are the main stable by-products;and O3 is the initial product when discharge is weak and there are NO2 and NO generated when discharge becomes stronger.The concentration of O3 is much higher than NOx.In a closed vessel,the concentration of by-products gases increases with discharge time,and tends to be saturated.Besides,higher voltage corresponding to bigger gases concentration.At the same voltage the influence of the relative humidity of air to by-products gases is obvious.The concentration of O3 and NO2 is higher at 18％ than at 25％ and 44％;the concentration of NO however is lower.