基于瞬时电流分解的谐波电流检测方法研究

Harmonic Currents Detecting Method Based on Decomposition of Instantaneous Current

通过坐标变换进行数学推导,指出dq0坐标系下的瞬时电流id、iq、i0均可分解成直流分量和交流分量相叠加的形式,阐明各分量在三相系统中的物理意义,导出基于瞬时电流分解的谐波电流检测方法的原理和实现。通过对坐标变换过程的分析,指出当被检测电流中含有零序分量时没有必要在坐标变换前剔除零序分量,坐标变换时也没有必要考虑零轴。本文提出的谐波电流检测方法原理简单、物理过程清晰,只用到一次坐标变换和反变换,计算量小,用数字方法实现时编程简单、延时短、实时性好。理论分析和仿真结果表明该方法是正确有效的。

Performing a mathematical derivation of the coordinate transformation in detail, this paper indicates that all of the three variables id iq and io in dqO coordinates can be decomposed into DC components and AC components and illustrates the physical meaning of all the components under abc coordinates. Furthermore, this article presents the principle and the implementation of the harmonic currents detecting method based on decomposition of instantaneous current. By analyzing the process of the coordinate transformation, it is indicated in this paper that it is not necessary to eliminate the zero-sequence component from the currents specified before carrying out the coordinate transformation and it is not necessary either to considerate the O-axis in coordinate transformation. The proposed method of harmonic detecting has a simple principle and a clear physical process, and only needs coordinate transformation and inverse coordinate transformation once, requiring less computation, simple program, short delay when carried out by digital methods. It is demonstrated by theoretical analysis and simulation results that this method of harmonic current detecting iscorrect and valid.