有源电力滤波器的自适应谐波电流检测方法研究

发布时间：2018-08-20 19:25

【摘要】：有源电力滤波器(Active Power Filter, APF)因其能实时、动态地跟踪补偿谐波和无功电流,已成为目前治理谐波污染最有效的手段。然而,提高APF的性能的必要前提是实现快速并精确的谐波电流或畸变电流检测。本文通过总结国内外谐波电流检测方法,并以傅氏级数和自适应滤波算法为理论基础,对谐波电流或畸变电流的自适应检测算法进行了理论研究。本文首先给出了基于自适应噪声对消技术(ANCT)和基于Adaline的两种自适应谐波电流检测模型的基本原理,并分析了两种模型在相同自适应算法的条件下的检测性能、缺陷和适用范围,以及不同算法对相同模型的检测性能的影响。其结果表明：在相同算法的条件下,两种模型的收敛速度一致,后者的稳态误差小(理论上可以为0)但计算量较大,前者只适用于APF的谐波检测环节,而后者还可用于评估电能质量；不同算法对相同模型检测性能的影响由算法的固有性能决定。另外,本文也介绍了基于ANCT的谐波电流检测模型应用在三相电路中的基本原理。其次,通过分析并总结基于LMS的谐波电流检测算法和现有的一些变步长LMS谐波电流检测算法的缺点,本文提出了基于改进的箕舌线函数的变步长LMS自适应畸变电流检测算法。该算法采用误差信号(即当前时刻负载电流与滤波器输出的差)与参考输入信号的瞬时互相关的时间均值估计来消除畸变电流对步长更新的干扰,并通过改进的箕舌线函数来调节该算法的步长。因此,在保证动态响应时间不增大的前提下,该算法具有更小的稳态误差,并且当负载电流发生突变时,该算法也有较强的跟踪能力。然后,针对LMS和RLS算法在谐波检测中的缺点,本文提出了加权LMS自适应畸变电流检测算法。在相同稳态误差的条件下,该算法的收敛速度比LMS算法更快,并且对于突变的负载电流,该算法也比RLS算法有更好的跟踪能力,这是因为该算法的权值更新不受畸变电流的干扰。此外,该算法的计算复杂度居于LMS和RLS算法之间。通过执行单相电路和三相电路的畸变电流检测的计算机仿真,验证了本文所做的工作。
[Abstract]:Active power filter (Active Power Filter, APF) has become the most effective method to control harmonic pollution because of its real-time and dynamic tracking and compensating harmonic and reactive current. However, fast and accurate detection of harmonic current or distortion current is necessary to improve the performance of APF. In this paper, based on the theory of Fourier series and adaptive filtering algorithm, the adaptive detection algorithm of harmonic current or distortion current is studied theoretically by summing up the detection methods of harmonic current at home and abroad. In this paper, the basic principles of two adaptive harmonic current detection models based on adaptive noise cancellation technique (ANCT) and adaptive harmonic current detection model based on Adaline are presented, and the detection performance, defects and application range of the two models under the same adaptive algorithm are analyzed. And the effect of different algorithms on the detection performance of the same model. The results show that the convergence rate of the two models is the same under the condition of the same algorithm, the steady-state error of the latter is small (theoretically it can be 0) but the calculation is large, the former is only suitable for the harmonic detection of APF. The latter can also be used to evaluate power quality, and the influence of different algorithms on the performance of the same model is determined by the inherent performance of the algorithm. In addition, this paper also introduces the basic principle of harmonic current detection model based on ANCT in three-phase circuit. Secondly, by analyzing and summarizing the shortcomings of the harmonic current detection algorithm based on LMS and some existing LMS harmonic current detection algorithms with variable step size, this paper proposes a variable step size LMS adaptive distortion current detection algorithm based on the improved tongue line function. In this algorithm, the error signal (i.e. the difference between the current load current and the output of the filter) and the time mean of the instantaneous cross-correlation between the reference input signal and the current load current are used to eliminate the interference of the distortion current to the update of the step size. The step size of the algorithm is adjusted by the improved tongue line function. Therefore, without increasing the dynamic response time, the algorithm has a smaller steady-state error, and it also has a strong tracking ability when the load current changes. Then, aiming at the shortcomings of LMS and RLS algorithms in harmonic detection, a weighted LMS adaptive distortion current detection algorithm is proposed in this paper. Under the same steady state error condition, the convergence speed of the algorithm is faster than that of the LMS algorithm, and the algorithm has better tracking ability than the RLS algorithm for the sudden load current. This is because the weight update of the algorithm is not disturbed by the distorted current. In addition, the computational complexity of the algorithm is between LMS and RLS. The work done in this paper is verified by the computer simulation of detecting the distortion current of single-phase circuit and three-phase circuit.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM933.1

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