Application of synthetic relative measuring method based on IEEE1588 in on-line monitoring of dielectric loss angle

Since capacitive equipment is widely installed in power system, it is very important to assess the insulation condition of capacitive apparatus. Synthetic relative measuring method in on-line monitoring of dielectric loss angle is an effective measure, which can greatly overcome the shortcomings of the traditional method and improve the measuring accuracy. The paper proposes a general method to watch the insulation condition of the capacitive equipment by analyzing the trend of established failure judgment matrices. However, the method requires high sampling time synchronization precision for the reason that the order of angle deviation between the measured leakage currents can reach 10^-5 or 10^-6, so even only one microsecond sampling deviation may bring about great error up to 10^-2, so that the insulation condition of capacitive apparatus may be misjudged. Although some high-end GPS products can reach the time synchronization accuracy of sub microsecond, they need so much investment and are unsafe. In order to solve the problem, the paper proposes a low cost and IEEE1588-based time synchronization system implemented to reduce the measurement error caused by sampling time synchronization deviation between the different measured equipment. Time synchronization level of the IEEE1588-based system is nanosecond. Thus, the diagnostic accuracy of the proposed method is improved by IEEE1588-based system.