绝缘油对变压器有载分接开关振动信号的影响

Effect of Insulation Oil on Vibration Signals of On-load Tap-changer of Power Transformer

为进一步理解和掌握绝缘油对变压器有载分接开关(on-load tap-changer,OLTC)切换过程中振动信号的影响,以某35 kV变压器OLTC为试验对象,分别对变压器油箱和OLTC油室内均有油、变压器油箱内有绝缘油和OLTC油室内无绝缘油、变压器油箱和OLTC油室内均无绝缘油3种状态下OLTC切换过程中的振动信号进行了测试。然后应用可调品质因子小波变换(tunable Q-factor wavelet transform,TQWT)将振动信号分解为多个复杂度不同的时间序列,经3次样条插值算法计算了各个时间序列的近似熵。结果表明,近似熵较好地度量了OLTC振动信号经TQWT分解后的时间序列的复杂度,OLTC油室内绝缘油的阻尼等降低了其切换过程中振动信号的复杂度,变压器油箱内绝缘油对振动信号的影响有限,但呈现随机性。研究结果可为基于OLTC机械状态的振动监测技术提供重要依据。

To better understand the effect of insulation oil on the vibration signals of on-load tap changer(OLTC) during the switch-over process, vibration signals of OLTC for a 35 kV power transformer are measured in three different states as follows: the insulation oil exists in both transformer tank and chamber for OLTC;the insulation oil exists in transformer tank and no oil exists in chamber for OLTC;the insulation oil exists in neither transformer tank nor chamber for OLTC. The tunable Q-factor wavelet transform(TQWT) is applied to decompose the measured vibration signals of OLTC into several time series with different complexity. The approximate entropy of each time series is calculated with the cubic spline interpolation algorithm. Calculated results show that the approximate entropy can be adopted to describe the com- plexity of each time series resulted from the TQWT. The complexity of vibration signals of OLTC are decreased by the damping of insulation oil in chamber for OLTC. The effect of insulation oil in transformer tank on the vibration signals of OLTC is limited and presents a feature of randomness. The results is of importance for the vibration monitoring technol- ogy of mechanical condition of OLTC.