Defect monitoring apparatus and detection method for transformer oil conservator based on edge computing

A defect detection method for a transformer oil conservator based on edge computing, comprising the following steps:

• S1:
• monitoring, by a sensing terminal, the following data in real time:
• a breathing airflow rate of an oil conservator, an oil temperature of the oil conservator, an ambient temperature, a microwave transmitting power, and a microwave receiving power;
• S2:
• determining whether the oil conservator has a false oil level defect:
• calculating an actual oil level height D1 according to the microwave transmitting power and the microwave receiving power;
• sending, by an original oil level gauge (8) of the oil conservator, data information to an edge intelligent gateway;
• calculating, by the edge intelligent gateway, a difference between the actual oil level height D1 and a display value D of the original oil level gauge (8) of the oil conservator;
• and when the difference is greater than 3 cm, determining that the oil conservator has a false oil level defect;
• otherwise, determining that the oil conservator has no false oil level defect;
• wherein the data information of the original oil level gauge (8) is the display value D of the original oil level gauge (8);
• S3:
• sampling the real-time monitoring data, to form a breathing airflow rate curve;
• when a change in the ambient temperature is within 10° C. and a change in the oil temperature of the oil conservator is within 4° C., comparing a peak breathing airflow rate Vm of the oil conservator monitored in real time with an average peak breathing airflow rate Va of the oil conservator in the passing month under a same condition;
• if a difference is greater than or equal to 15%, performing step S4;
• otherwise, determining that the following four types of defects do not exist:
• capsule damage, partial blockage of a breathing circuit, leakage in the breathing circuit, or moisture impurities in a breathing tube;
• S4:
• when Vm≥1.2Va, th≤0.9tha, and tx≤0.9txa, determining that a capsule damage defect exists;
• wherein th is a single expiration duration monitored in real time, tx is a single inhalation duration monitored in real time, tha is an average single expiration duration in the passing month, and txa is an average single inhalation duration in the passing month;
• when Vm≤0.8Va, th≥1.1tha, and tx≥1.1txa, determining that a defect of partial blockage of the breathing circuit exists;
• when Vm≤0.8Va, |th−tha|<0.05tha, and |tx−txa|<0.05txa, determining that a defect of leakage in the breathing circuit exists;
• and
• when Vm≤0.85Va and an airflow rate zero-crossing number x0 of a single expiration and inhalation process increases by 2 times or more compared with an average airflow rate zero-crossing number xa0 in the passing month, determining that a defect of moisture impurities in a breathing tube exists;
• S5:
• calculating a comprehensive evaluation coefficient for defect detection of the oil conservator, to obtain defect severity;
• S6:
• when the defect severity is a general defect or a severe defect, sending, by the edge intelligent gateway, an evaluation result and corresponding data to an oil conservator defect monitoring cloud platform;
• and
• S7:
• sending, by the oil conservator defect monitoring cloud platform, an alarm command to a client terminal, which transformer operation and maintenance personnel access the oil conservator defect monitoring cloud platform through the client terminal.