谐波测量作为研究谐波问题的出发点，成为人们研究谐波首要面对的课题。基于傅里叶变换的谐波测量得到广泛的应用，然而这种方法要求整周期同步采样，否则会产生频谱泄漏和栅栏效应。 针对以上问题，本文在研究分析的基础上, 提出一种改进的同步采样法——变频采样法。造成频谱泄漏的原因是采样频率和实际信号频率不一致，基于此原因本文提出了实时改变采样频率实现同步采样的方法。这种方法是采样点数固定不变，采样频率通过测量电网的实际频率得到，这样产生的同步偏差将小于固定间隔采样引起的同步偏差。该采样法的关键是要根据所测数据准确计算电网实际频率，同时本文给出一种实时计算电网频率的方法。 接着用matlab对实时计算电网频率算法进行了仿真，结果表明这种方法能快速、准确得到信号的频率。同时还对变频采样法在频率波动的情况下进行了仿真，结果表明该算法通过实际电网的频率进行采样，能大大减少同步误差，改善采样效果。对通过增加采样点减少栅栏效应进行了探讨。最后设计了一种基于TMS320LF2407和ADS8364的电网谐波检测系统，给出了系统的总体设计、硬件设计和软件设计，并在上位机上实现了谐波检测算法在的具体应用。

As the starting point of research harmonic question , harmonic measurement becomes first subject on study harmonics. The harmonics measurement based on Fourier Transform has been used widely,but it may appear the deviation (sampling synchronous deviation) because of the fluctuation of signal frequency.The deviation will lead to spectral leakage and picket fence effect which will degrade the accuracy of harmonics determination. To the above question, the new Synch-sampling——frequency adjustment sampling method——is proposed on the basis of the study. This method is the sampling frequency no longer a fixed, but it calculated by the real frequency of power grid. The key problem in the new AC sampling method is the precise measurement of the signal frequency. So it introduces a simple、reliable way which can be used in real-time conditions to calculate the signal frequency. Then the real-time calculate signal frequency algorithms solved with matlab. The results showed that method can quickly to Measure accurately the signal frequency. second, the frequency adjustment sampling method is solved with matlab when the frequency of electric network flutters. The results showed that frequency adjustment sampling method can reduce the synchronous deviation，and improve sampling effect. Finally, a high performance electric harmonic monitoring device is introduced which is based on TMS320LF2407 processor. the design of hardware frame,the development flow of DSP signal sampling program and signal processing program in this paper. A harmonic System Based on java is developing in this paper.