A Phase Capacitance Voltage Control Method Applied to Modular Multilevel Converter

Abstract

The invention discloses a phase capacitance voltage control method applied to a modularized multi-level converter, comprising the following steps: 1) obtaining the sub-module capacitance voltage and u in the phase of the converter ∑ , get the DC error signal u error ; 2) the DC error signal u error Perform low-pass filtering through a low-pass filter to remove the harmonic components and noise, and obtain the filtered DC error signal u error,LPF ; 3) The filtered DC error signal u error,LPF Send it to the proportional-integral controller, and send the output signal of the proportional-integral controller to the pole compensator, and then use the output of the pole compensator as the voltage adjustment command Δu * ; 4) The voltage adjustment command Δu obtained in step 3) * The final voltage command is obtained by adding it to the voltage command of the upper and lower bridge arms of the converter. This method can effectively control the phase capacitance voltage, improve the stability of the system, improve the dynamic performance of the dynamic system, and the calculation burden is small.

Description

technical field [0001] The invention belongs to the technical field of modular multilevel converters in power electronics, and relates to a phase capacitance voltage control method applied to modular multilevel converters. Background technique [0002] With the wide application of high-power power electronic conversion devices, multi-level conversion technology has been developed rapidly. Modular Multilevel Converter (MMC) is a novel multilevel voltage source converter. Since it was proposed in early 2000, it is easy to expand and assemble due to its modular characteristics. , and can obtain the advantages of high-quality output and high voltage level, it is a research hotspot in recent years, and it has obvious advantages in the field of medium and high voltage applications. At present, MMC has been widely used in the field of High Voltage Direct Current (HVDC), and many lines have been put into operation, such as the Trans Bay Cable project in the United States, the three...

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Problems solved by technology

Existing control methods, such as voltage outer loop + current inner loop, power outer loop + current inner loop, and pure voltage outer loop control methods all have certain defects: the control method based on the voltage outer loop does not take into account the sub-module capacitor voltage The fluctuations affect the operation of MMC; the power outer loop introduces additional calculation operations in the digital controller, which increases the system burden; the existence of the current inner loop limits the design of the MMC circulation controller, etc.

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