Open-circuit fault diagnosis method for switching tube in half-bridge sub-module of MMC converter

Abstract

The invention discloses an open-circuit fault diagnosis method for a switching tube in a half-bridge sub-module of an MMC converter. The diagnosis method is composed of an event triggering program and an IGBT open-circuit fault diagnosis program. The IGBT open-circuit fault diagnosis program is started when the capacitive voltage of a certain half-bridge sub-module exceeds a threshold value interval set by the event triggering program; and when the capacitive current state observation value, the capacitive current theoretical value and the sub-module driving function Si of the half-bridge sub-module meet the conditions, the fault IGBT of the half-bridge sub-module can be accurately positioned. A sub-module capacitive current sensor does not need to be additionally added, and the method can be widely applied to existing MMC commercial products; capacitive current is observed in real time through a capacitive current state observer; the observation value of the capacitive current is symbolized through a symbolic function. By means of the method, the high anti-interference capacity is achieved for system parameter changes and sampling disturbance.

Description

technical field [0001] The invention belongs to the field of fault diagnosis of power electronic converters. Background technique [0002] Since there are dozens or even hundreds of IGBTs in MMC and IGBT faults account for 21% of the total faults of power converters, the fast and accurate diagnosis and location technology for IGBT open circuit faults is the key to ensure the stable operation of MMC. Among the existing fault diagnosis methods, the relevant literature proposes a fault diagnosis technology based on a capacitive voltage sensor, but this fault diagnosis technology requires additional sensors and detection circuits, thus resulting in a complex hardware circuit and an increase in cost; related papers propose Based on state observation methods such as Kalman filter and sliding mode observer, the relevant fault diagnosis methods can only locate specific sub-modules but cannot realize the positioning of specific IGBTs; fault diagnosis methods based on artificial intel...

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Problems solved by technology

Among the existing fault diagnosis methods, the relevant literature proposes a fault diagnosis technology based on a capacitive voltage sensor, but this fault diagnosis technology requires additional sensors and detection circuits, thus resulting in a complex hardware circuit and an increase in cost; related papers propose Based on state observation methods such as Kalman filter and sliding mode observer, the relevant fault diagnosis methods can only locate specific sub-modules but cannot realize the positioning of specific IGBTs; fault diagnosis methods based on artificial intelligence have also been proposed in related literature, but The calculation of the algorithm is huge, and it is impossible to realize real-time fault diagnosis and positioning in DSP; at the same time, the existing fault diagnosis methods are only limited to the specific MMC sub-module structure, and there are disadvantages such as poor algorithm portability

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