Flexible direct-current power transmission system MMC sub-modules key element synchronous online monitoring method

Abstract

The invention relates to a flexible direct-current power transmission system MMC sub-modules key element synchronous online monitoring method. The method comprises the following steps that: S1, an MMC-HVDC system is constructed; S2, sensors are configured to acquire bridge arm voltage, bridge arm current and sub-module capacitor voltage; S3, a sub-module IGBT, diode and capacitor on-line monitoring mathematical model is constructed; S4, IGBT on-state voltage bias, diode on-state voltage bias, diode on-state resistance and a capacitor capacitance value are obtained online through a Kalman filtering algorithm; S5, estimated IGBT on-state voltage is calculated according to the IGBT on-state voltage bias and IGBT on-state resistance, and on-state voltage and on-state resistance are calculated;and S6, the obtained IGBT on-state voltage, the diode on-state voltage, the diode on-state resistance and the capacitor capacitance value are compared with set parameter threshold values, and aging identification and residual life estimation are carried out on sub-modules. With the method of the invention adopted, the synchronous on-line monitoring of semiconductor devices and capacitors in a monitoring MMC can be realized.

Description

technical field [0001] The invention relates to the field of monitoring of modularized multilevel converters, in particular to a method for synchronous on-line monitoring of key components of MMC sub-modules in a flexible direct current transmission system. Background technique [0002] Modular Multilevel Converter (MMC) has been widely used and developed in flexible DC transmission technology in recent years, and its reliability is related to the safe and stable operation of the entire flexible DC transmission system. Each bridge arm of the MMC is formed by cascading multiple sub-modules, the number of which is huge, and the performance of each device in the sub-module determines whether the converter operates normally. The long-term operation of the IGBT module used in the MMC sub-module will cause material fatigue and aging under the impact of thermal cycles, such as aluminum leads, soldering layer breakage or falling off; the capacitors in the sub-module usually use meta...

AI Technical Summary

Problems solved by technology

[0004] (1) Only pay attention to the aging degree of IGBT or capacitor, without synchronous online monitoring of the parameters of all components of the sub-module, separate monitoring will increase the input cost and increase the burden of computer memory;

[0005] (2) It is necessary to use a large number of sensors to obtain electrical quantities, which increases the cost of configuration equipment and reduces the reliability of the MMC system;

[0006] (3) IGBT on-state voltage is not used as the basis for aging judgment, and the influence of its own junction temperature needs to be considered

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