Online monitoring of transformer neutral point groundingReliability centered condition based maintenance is the development trend of power equipment maintenance, which has been practically applied in Western Europe, North America, and many domestic power grid companies have also installed related equipment and software systems. Due to differences in offline testing conditions and equipment operating conditions, existing preventive tests suffer from issues such as missed, early, or false reporting of accidents. At the same time, the cost of preventive testing is high and the losses from power outages are significant.

1Online monitoring of transformer neutral point groundingMeasurement refers to the use of sensing technology and microelectronics technology to monitor transformers in operation, obtain various physical quantities that reflect the operating status, analyze and process them, predict the operating status of transformers, and provide alarms and fault diagnosis when necessary. In order to minimize the further expansion of faults and prevent serious accidents, guide the maintenance timing of transformers, and provide real-time data and important reference basis for condition based maintenance. Therefore, online monitoring is the link and technical means for transitioning from preventive maintenance to condition based maintenance.

IIOnline monitoring of transformer neutral point groundingTechnical Status:
Through fault mode analysis, the online monitoring projects for transformers mainly include dissolved gas measurement and analysis (DGA) in oil, partial discharge measurement (PD), and contact wear of on load switches.

IIIOnline monitoring of transformer neutral point groundingchoice:
Any change in the plan or economic investment must consider how much benefits can be increased or how much reliability can be improved. So now, various power departments have shifted from cost free online monitoring projects in the late 20th century to carefully considering the comprehensive benefits such as input-output ratio and reliability of online monitoring projects in different situations.
So, whether to adopt an online monitoring scheme, which parameters to monitor online, and which type of online monitoring system to use, all need to follow the principle of seeking truth from facts: based on the actual situation of each transformer and the failure rate of different components on the transformer, carefully study what kind of detection scheme can be adopted to ensure operational reliability and improve economy.
Firstly, it is necessary to classify the level of transformers based on whether they require online monitoring. The classification level needs to consider the following factors:
(1) The importance of transformers in the power grid involves the economic losses and social impacts of power outages for power supply users;
(2) The degree of aging of transformers and the probability of danger occurring, i.e. the level of danger.