A Power Module Capacitor Voltage Balance Strategy Considering Input Frequency

Abstract

The invention discloses a power module capacitor voltage balancing strategy considering the frequency of input. After the valve control system receives the bridge arm voltage modulation wave, it calculates the number of power modules required to be input in this cycle according to the size of the capacitor voltage of the power module. And with 0, the total number of bridge arm power modules N SM , The number of power modules put into use in the last cycle N on_old In comparison, at the same time, refer to whether the bridge arm current is charging or discharging, combined with the input frequency, to finally determine the input power module. When the present invention realizes the balance control of the capacitor voltage of the power module, the two important parameters of the input frequency of the power module and the size of the capacitor voltage are comprehensively considered, and while meeting the DC voltage requirement, the power module can obtain an equal service life and reduce the maintenance cycle of the equipment .

Description

technical field [0001] The invention relates to flexible direct current transmission technology, in particular to a power module capacitor voltage balance strategy considering input frequency. Background technique [0002] Compared with conventional HVDC technology, due to its many advantages such as no need for reactive power compensation, no commutation failure problem, convenient adjustment of active power and power, low harmonic level, and suitable for multi-terminal HVDC systems, flexible HVDC related technologies have gained rapid development. Among them, the flexible direct current transmission system based on MMC (modular multilevel converter) topology is the most representative and technically superior. [0003] Such as figure 1 As shown, MMC is composed of six bridge arms, each of which is composed of N cascaded power modules (also known as sub-modules) and a series reactor. Typical power modules are divided into full-bridge power modules according to different st...

AI Technical Summary

Problems solved by technology

[0011] Aiming at the existing power module capacitor voltage balance strategy that only considers the size of the capacitor voltage and ignores the important defect that electronic devices have a certain switching life, the present invention provides a power module capacitor voltage balance strategy that considers the input frequency, and introduces the power The input frequency of modules considers the problem of capacitor voltage balance from two dimensions. While meeting the DC voltage requirements, the power modules can obtain an equal service life and reduce the equipment maintenance cycle.

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