On-line power capacitor operation state monitoring method based on dielectric loss factor

Abstract

The invention provides an on-line power capacitor operation state monitoring method based on a dielectric loss factor, and belongs to the technical field of on-line substation equipment monitoring. The method is implemented through a parameter measurement unit and comprises the steps that 1001, operation starts; 1002, a voltage signal of a busbar is acquired; 1003, an operation voltage of a power capacitor is obtained; 1004-1005, a current signal I of a switch cabinet current transformer is obtained and decomposed; 1006, the dielectric loss factor is obtained; 1007, if the power capacitor is in a serious state, the step 1008 is executed, and if the power capacitor is not in the serious state, the step 1009 is executed; 1008, a trip instruction is sent; 1009, if the power capacitor is in an abnormal state, the step 1010 is executed, and if the power capacitor is not in the abnormal state, the step 1011 is executed; 1010, alarming is conducted; 1011, operation continues. By monitoring the power loss factor of the power capacitor in real time, the working state of the power capacitor is monitored, and safety working of the power capacitor and a complete high-voltage power capacity device is guaranteed.

Description

technical field [0001] The invention provides an online monitoring method for the operating state of a power capacitor based on a dielectric loss factor, and belongs to the technical field of online monitoring of substation equipment. Background technique [0002] The complete set of high-voltage power capacitors is the most traditional, the most widely used and the largest number of reactive power compensation equipment in the power system. The capacity of reactive power compensation equipment in my country is nearly 1 billion kvar, most of which are shunt capacitor complete sets, which are beneficial to the power system. Safe and stable operation can improve power quality, reduce power loss, increase the transmission capacity of transmission and distribution lines and power transformers, and play a very good role. The availability of capacitive reactive power compensation equipment has become an important technical index for power production management. [0003] The reacti...

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Problems solved by technology

[0003] The reactive power compensation device is arranged and installed separately in the substation. Generally, it is connected in parallel to the low-voltage busbar of the substation through a special switchgear. Whether it is put into use is determined according to the power factor of the power transformer or the voltage of the busbar. Because whether it is put into use does not directly cause power failure for users, but affects the power supply Reliability, there is a common problem of not paying enough attention to the safe and reliable operation of power capacitors. There are many management loopholes in installation, operation, testing, defect elimination, and maintenance. The actual operation shows that the accident rate of capacitors ranks first among all equipment in substations. The complete set of capacitors is useless. Due to various reasons, it cannot even be put into operation all year round. Its role has not been brought into play, which affects the economic operation of the system and the voltage quality.

[0004] Dielectric loss is an important indicator of the basic performance and state of the power capacitor dielectric. It can reflect the quality of the manufacturing process and raw materials as well as the state and level of safe operation. The specific performance is: (1) The capacitor is not well sealed and there is oil leakage , the moisture in the air enters the capacitor core, and the insulation of the capacitor element is reduced

The oil level drops, and even the capacitor lead wire or the upper end of the component leaks the oil surface, the active power loss of the power capacitor increases, and the capacitor runs hot

(2) The overload operation of power capacitors due to various reasons causes a significant increase in heat generation, accelerates the aging of the insulating medium, and increases the leakage current in the medium

(3) Due to the high field strength and high temperature operating conditions of the power capacitor, the insulation aging of the power capacitor is accelerated, and the dielectric breakdown discharges, resulting in thermal breakdown

(4) There are other insulation defects in the core of the power capacitor, or there is partial discharge inside the shell

All of the above problems will lead to changes in the dielectric factor of power capacitors

[0005] It can be seen from the above that it is very important to judge the operating state of the power capacitor by monitoring the change of the dielectric loss factor. The loss factor evaluates the working state of the power capacitor, so it is difficult to obtain the working state of the power capacitor in actual work, thus forming a large safety hazard

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