Equivalent simulation calculation modeling method for modularized multi-level converter

Abstract

The invention relates to an equivalent simulation calculation modeling method for a modularized multi-level converter. The modularized multi-level converter is composed of six bridge arms. Every two bridge arms form a phase unit. Each bridge arm is formed by connecting a cascade sub-module and a bridge arm reactance L in series. Each sub-module comprises an insulation gate double-pole thyristor IGBT1, an insulation gate double-pole thyristor IGBT2, a diode D1, a diode D2 and a capacitor C. Each insulation gate double-pole thyristor and one diode are connected in an anti-parallel mode for forming a switching component branch. According to the equivalent simulation calculation modeling method, equivalence is carried out on the sub-modules of the modularized multi-level converter and Dommel equivalent calculation models for the bridge arms, and additional switching component processing is adopted for solving the problem that the switching-on state of a switch tube changes during two simulation moments in the locking phase of the modularized multi-level converter. According to the modeling method, the calculation amount in the simulation operation can be reduced by reducing the number of variable impedance branches in the electromagnetic transient simulation calculation, and therefore simulation of the modularized multi-level converter is efficient, and the calculation result is stable and reliable.

Description

technical field [0001] The invention relates to a high-efficiency simulation modeling method for a modular multilevel converter, belonging to the technical field of power transmission and distribution. Background technique [0002] For the sake of sustainable development, using renewable energy such as solar energy and wind energy to generate electricity has become the development direction of the future power system. These power generation methods have the characteristics of being far away from the main grid and fluctuating greatly over time. The flexible DC transmission system is based on Voltage Source Converter (Voltage Source Converter, VSC) and Pulse Width Modulation (Pulse Width Modulation, PWM) technology to invert DC voltage into AC voltage with controllable amplitude and phase, and can independently and quickly Controlling the transmitted active power and reactive power greatly enhances the flexibility of power transmission and becomes the most potential power tra...

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Problems solved by technology

It has been proposed in the literature that a controllable voltage source can be used to replace the output voltage of the sub-module in the modular multilevel converter, and a controllable current source can be used to connect the sub-module circuit. However, this method does not consider the delay problem in the numerical calculation. , the value used by the controllable voltage and current source in the decoupling method is not the calculated value in the current solution step but the calculated value obtained in the previous step, which will artificially make the voltage and current of the bridge arm equivalent circuit The solution of is decoupled in time, leading to model instability under dynamics

In some literature, the modular multilevel converter is equivalent to a capacitor with controllable output voltage and current, ignoring the difference in the capacitance of each sub-module, so this model cannot be used to verify the voltage balance algorithm

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