基于优化分裂基FFT算法的APF谐波检测策略

有源电力滤波器(APF)是一种具备动态谐波抑制和无功补偿功能的新型电力电子装置，对电流谐波实时准确快速检测是决定APF性能的一个重要环节。快速傅立叶变换(FFT)是目前应用广泛的谐波检测方法。然而，传统FFT算法计算复杂、存在时间延迟、实时性差、容受电网电压波形畸变或频率波动的影响，影响谐波检测的准确性和效率，降低APF的补偿效果和综合性能。由此，本文提出一种基于分裂基FFT算法的APF谐波检测与补偿策略，通过蝶形运算对偶序号输入使用基-2算法，对奇序号输入使用基-4算法，比传统基-2算法减少10%以上运算量，比传统基-4算法减少2%以上运算量，可有效降低FFT算法复杂程度，增强谐波检测实时性；采用汉宁窗对分裂基FFT算法进行优化，提升谐波检测精度与抗干扰能力，保证APF谐波检测与补偿效果和整体性能。通过三相四线制APF样机实验验证了所提谐波检测与补偿策略的正确性和有效性，在负载突变的情况下，重新到达新稳态的调节时间可缩短约25%。

The harmonic detection strategy for APF based on the optimized split-radix FFT algorithm

The active power filter (APF) is a new type of power electronic device with the functions of dynamic harmonic suppression and reactive power compensation. The accurate and rapid detection of current harmonics in real time is an important part of determining the performance of APF. The fast Fourier transform (FFT) is a widely used harmonic detection method. However, the conventional FFT algorithm is complicated in calculation, has time delay, poor real-time performance, and is easily affected by grid voltage waveform distortion or frequency fluctuation, which affects the accuracy and efficiency of harmonic detection, thereby reducing the compensation effect and comprehensive performance of APF. Therefore, this paper proposes an APF harmonic detection and compensation strategy based on split-radix FFT algorithm. Through butterfly operation, the radix-2 algorithm is used for the input of even numbers, and the radix-4 algorithm is used for the input of odd numbers, effectively reducing the complexity of the FFT algorithm, enhancing the real-time detection of harmonics. The split-base FFT algorithm is optimized by using Kaiser window to improve the harmonic detection accuracy and anti-interference ability of harmonic detection, ensuring the harmonic detection and compensation effects and overall performance. The correctness and effectiveness of the proposed harmonic detection strategy are verified by the three-phase four-wire APF prototype experiment, and the conditioning time to re-reach the new steady-state can be shortened by 25% in the case of sudden load changes.