Switch-class device state evaluation method based on parameter on-line identification

Abstract

The invention discloses a switch-class device state evaluation method based on impedance parameter on-line identification. The switch-class device state evaluation method is suitable for switch-class devices in the 3 / 2 connection mode of a transformer substation. Real-time current data of the switch-class devices are used, actual operational data such as line currents and transformer currents inside the transformer substation are combined, resistance distribution conditions of the switch-class devices are identified, therefore, the resistance change conditions of the switch-class devices can be obtained, the abnormal resistance value condition caused by defects of the switch-class devices can be timely discovered, and the important reference basis is provided for device timely defect elimination. According to the switch-class device state evaluation method based on impedance parameter on-line identification, state evaluation on the switch-class devices can be dynamically carried out in an assisting mode, the operation is simple, computing is reliable, the operational cost is much lower than that of site detection testing, and the good adaptability and the good real-time performance are achieved. The switch-class device state evaluation method fills the blank in the field in China and provides a research thought for state maintenance of other high-voltage devices.

Description

technical field [0001] The invention relates to an online identification method for switch equipment parameters, which is used for online auxiliary diagnosis of whether the switch equipment has defects. It belongs to the field of power system parameter identification. Background technique [0002] In recent years, serious failures of 500kV circuit breakers and isolating switches in the power grid have occurred frequently, posing a greater threat to equipment, power grids and even personal safety. The contact resistance value of switch equipment is an important basis for characterizing its status. The contact resistance value higher than the normal value indicates that the equipment may have defects, such as the dynamic and static contacts not closing in place, the contact surface melting, the transmission connecting rod deviation, etc. Both problems can lead to increased contact resistance. However, there are many factors that affect the switch resistance. Since the switch...

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Problems solved by technology

The contact resistance value of switch equipment is an important basis to characterize its status. The contact resistance value higher than the normal value indicates that the equipment may have defects, such as the dynamic and static contacts not closing in place, the contact surface melting, the transmission connecting rod deviation, etc. Both problems can lead to increased contact resistance

[0004] 1. The measurement is periodic, and it is impossible to dynamically track the status of the equipment in real time

[0005] 2. When performing infrared measurement, if the current flowing through the device is small under the current operating mode and the device does not heat up obviously, it may be difficult to find the defect of the device

[0006] 3. The 500kV substation adopts 3 / 2 wiring. Due to the shunt effect of the switch in the series and other equipment, when the contact resistance value increases, the shunt flowing through the switch equipment decreases. Because the heat is proportional to the square of the current, it may cause defects. Fever is not obvious, making it difficult to find defects

[0009] 1. The contact resistance of a certain phase increases, resulting in an imbalance between the current of this phase and the other two phases, and at the same time, the distribution of power flow in the string of this phase changes

[0010] 2. The contact resistance of each phase of the switchgear increases, the current of each phase is unbalanced, and the power flow distribution in the string of each phase changes.

[0011] The resistance values ​​of the switches, switches, guide wires, joints and other equipment in each string of a 500kV substation are normally tens of micro-ohms. The phase-to-phase current is more or less unbalanced, and it is difficult to locate which switchgear has increased contact resistance only based on the unbalanced current in the string

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