基于嵌入式系统的非同步采样高精度谐波检测

电网工频时变将导致固定采样率下的非同步采样现象，降低谐波检测精度。A类谐波测量仪器通过硬件锁相克服了该问题，但高昂的价格使其难以广泛应用于实际工程。在嵌入式系统中通过合理的算法校正非同步采样结果，实现谐波的准确测量，能够有效降低设备成本。首先分析频谱泄漏抑制条件与多点变换谐波测量算法特性，研究不同变换点数对频谱的影响，推导在不同采样条件下的最佳变换点数选择式。其次提出优先计算基波及低次奇次谐波频率的平均参考工频优化算法，进一步改善了整体计算效果。最后在STM32嵌入式系统上实现了算法。模拟数据计算及LED灯谐波检测实验结果均验证了在非同步采样下，基于该算法的嵌入式系统谐波测量的高精度性与高可靠性。

High precision harmonic detection in non-synchronous sampling based on an embedded system

Time-varying power frequency will cause a non-synchronous sampling phenomenon at a fixed sampling rate and will reduce harmonic detection accuracy. Class A harmonic measuring instruments overcome this problem through hardware phase locking, but their high price makes it difficult for them to be widely used in actual engineering. Achieving accurate harmonic detection by correcting non-synchronous sampling results through reasonable algorithms on the embedded system can reduce equipment costs effectively. First, spectral leakage suppression conditions and multipoint transformation harmonic measurement algorithm characteristics are analyzed, and the influence of different transformation points on the spectrum is studied, and the optimal conversion point selection formula for different sampling conditions is derived. Second, an average reference power frequency optimization algorithm is proposed by prioritizing the calculation of fundamental and low odd harmonic frequency to further improve the overall calculation effect. Finally, the algorithm is implemented on the STM32 embedded system. The simulation data calculation and the experimental results of LED lamp harmonic detection verify the high precision and reliability of the harmonic measurement in the embedded system based on this algorithm in non-synchronous sampling.