Modular multilevel matrix converter bridge arm current decoupling method

Abstract

The invention discloses a modular multilevel matrix converter bridge arm current decoupling method, which comprises the following steps of: calculating a bridge arm current circulating component matrix; subtracting the bridge arm current circulating component matrix from a bridge arm current instantaneous value matrix I to obtain decoupled bridge arm current matrixes I1 and I2 containing only a single-frequency current component; mapping the decoupled bridge arm current matrixes I1 and I2 to synchronous rotating coordinate systems with frequencies f1 and f2 respectively to obtain the projection of the decoupled bridge arm current in the rotating coordinate systems and control the modular multilevel matrix converter according to the projection of the decoupled bridge arm current in the synchronous rotating coordinate systems to decouple the bridge arm current of the modular multilevel matrix converter. The method can avoid the mutual interference between the two subsystems on both sidesof the modular multilevel matrix converter and the independent active power and reactive power control.

Description

technical field [0001] The invention belongs to the fields of flexible power transmission technology, frequency division power transmission technology and new energy power generation, and relates to a bridge arm current decoupling method of a modular multilevel matrix converter. Background technique [0002] Wind power generation is one of the earliest and more mature technologies. The scale of wind farms is gradually expanding in the continuous development and application. However, the limitation of wind energy and land resources makes most wind farms located in remote areas far away from load or on the sea. With the continuous development of global offshore wind power, the development of offshore wind power gradually tends to be deep and far away. [0003] Under the background of offshore wind power going far and wide, the grid-connection method of offshore wind farms and onshore power grids will directly ensure the safety and economy of wind power grid-connected. On the ...

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Problems solved by technology

However, the modeling and control of M3C is more complicated than that of the MMC converter in flexible HVDC transmission, as shown in the following aspects: 1) M3C has 9 voltage degrees of freedom and 8 current degrees of freedom, making the control more difficult; 2) M3C is directly connected to two AC power grids with different frequencies, which means that the bridge arms of M3C will flow currents with two different frequency components, and the currents on both sides are directly coupled in the bridge arms, which occurs when the traditional dq rotation coordinate system is performed on the bridge arm currents. Interference occurs between different frequencies

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