基于i p-i q理论的改进型谐波检测方法

Study on Improved Harmonic Detection Method Based on i p-i q Theory

针对传统的i p-i q谐波检测方法使用低通滤波器难以实现检测精度与速度平衡的问题,提出了一种使用LMS自适应滤波器与电流平均值法的串联使用代替低通滤波器的方法。为了解决传统定步长LMS算法无法兼顾收敛速度与稳态误差的矛盾,设计了一种改进的基于双曲正弦函数的变步长LMS算法。算法通过使用误差信号的时间均值估计p(n)与参数‖T‖2控制步长因子,减小稳态误差,并引入α(n)对双曲正弦函数的取值进行限制,加快收敛速度;最后通过串联电流平均值模块进一步提高检测精度与速度。使用Matlab软件进行仿真试验,试验结果表明:改进方法在检测精度与速度方面较传统的i p-i q谐波检测方法有较大提升,验证了方法的有效性、可行性。

The traditional i p-i q harmonic detection method is difficult to achieve the balance of detection accuracy and speed by using low-pass filter,so a new method using LMS adaptive filter and current average method in series instead of low-pass filter is proposed.In order to solve the contradiction between convergence speed and steady-state error in the traditional fixed-step LMS algorithm,an improved variable-step LMS algorithm based on hyperbolic sinusoidal function is designed.The algorithm uses p(n)that the time mean estimation of the error signal and parameter‖T‖2 to control the step size factor to reduce the steady-state error.Then,introducingα(n)to limit the value of the hyperbolic sinusoidal function to accelerate the convergence speed.Finally,concatenating current averaging module to further improve the detection accuracy and speed.Simulation test is carried out with MATLAB software,and the simulation results show that the improved method is greatly improved compared with the traditional i p-i q harmonic detection method in terms of detection accuracy and speed,which verifies the effectiveness and feasibility of the method.