基于分布反馈激光器的局部放电监测系统研究

Research on Partial Discharge Monitoring System Based on Distributed Feedback Laser

摘要:

电力设备的局部放电监测是发现设备的绝缘缺陷、维护电网安全运行的重要手段。文章基于分布反馈(DFB)激光器线宽窄、噪声低、相干长度长等优点,设计了一种用于局部放电监测的振动传感系统。系统采用粘接在悬臂梁上的DFB激光器作为传感头,利用光纤迈克尔逊干涉仪将DFB激光器波长变化转换为干涉仪的输出光强变化,采用相位生成载波(PGC)算法进行局部放电信号解调。设计并仿真分析了悬臂梁的振动响应特性,得到其一阶谐振频率为876Hz。研究了迈克尔逊干涉仪臂长差与系统灵敏度的关系。实验选取脉冲点火器作为局部放电源进行放电检测,验证了系统用于局部放电检测的可行性。结果表明,该系统能够检测到800~900Hz放电信号,灵敏度可达-74.67dB re rad/Pa。

Abstract:

Partial discharge (PD) monitoring is an important way to find the insulation defects of power equipment and maintain the safe operation of power grid. Based on the advantages of Distributed Feedback (DFB) laser, such as narrow line width, low noise and long coherence length, a vibration sensing system for partial discharge monitoring was designed. The DFB laser glued on the cantilever beam was used as the sensing head, the wavelength change of DFB laser was converted into the output intensity change of the interferometer by using the fiber Michelson interferometer, and the Phase Generated Carrier (PGC) algorithm was used to demodulate partial discharge signals. Cantilever was designed and vibration characteristics were simulated, and its first order resonant frequency was 876Hz. The relationship between the arm length difference of Michelson interferometer and the system sensitivity was studied. The pulse igniter was used as the partial discharge source for discharge detection, which verified the feasibility of the system for partial discharge detection. The results show that the system can detect the discharge signal of 800~900Hz with the sensitivity of -74.67dB re rad/Pa.