计及纹波和谐波的M3C稳态特性建模与功率运行区间研究

Modeling of Steady-state Characteristics and Research on Power Operating Region of Modular Multilevel Matrix Converter with Ripple and Harmonic

明确模块化多电平矩阵变换器(M3C)的功率运行区间是制订运行方案的前提与基础,但由于M3C内部纹波和谐波特性建模困难,现有研究未能充分考虑它们对电气量峰值、有效值等指标的影响,导致计算结果不够精确。对此,提出面向M3C纹波和谐波耦合特性的dq域动态建模方法,并建立21维模型;进而,提出稳态运行点求解方法,并考虑网侧电流、调制比、桥臂电流有效值和子模块电容电压峰值约束,结合典型算例计算M3C功率运行区间;同时,针对电容电压峰值影响因素众多、计算困难的难题,提出近似计算方法;最后,提出拓展功率运行区间的建议。研究结果表明:所建模型具有较高精度;M3C的功率运行区间在重载时主要由网侧电流约束决定,在轻载时主要由子模块电容电压波动约束决定;抑制谐波环流有助于提升M3C功率运行区间;当M3C两侧无功功率较大且方向相反时功率运行区间下降。

It is a prerequisite and basis to define the power operating region of modular multilevel matrix converter(M3C).However,due to the difficulties in modeling the ripple and harmonic characteristics of the M3C,the existing research fails to fully consider the effects on the peak and root mean square(RMS)of the electrical volume,resulting in inaccurate calculation results.Therefore,this study proposes the dynamic modeling method of dq domain for M3C ripple and harmonic coupling characteristics,and establishes a 21-dimensional model.Then,it proposes the steady-state operation point solution method,and calculates the M3C power operation region with typical examples considering the constraints of grid side current,modulation ratio,RMS of bridge arm current and peak capacitance voltage of sub-modules.At the same time,the approximate calculation method is proposed to solve the problem of many factors affecting the peak capacitance voltage.Finally,some suggestions for expanding the power operation range are put forward.The research results show that the model has high precision.The power operating region of M3C is mainly determined by the current constraint of the grid side under heavy load,and by the capacitor voltage fluctuation constraint of the sub-module under light load.The suppression of harmonic circulation is helpful to improve the M3C power operating range.When the reactive power on both sides of the M3C is large and opposite in direction,the power operating range decreases.