两种电网谐波分频检测方法的对比

Comparison of Two Harmonic Detection Methods with Separate Frequency

为分析不同电网谐波检测方法的特点,介绍了基于瞬时无功功率的谐波分频检测法和基于最小二乘法的谱估计谐波分频检测法,仿真分析、比较两种方法的结果表明前者能够瞬时检测到谐波分量,实时性很好,但检测结果包括的幅值和相位信息不能分离开来;而后者可离线计算特定次谐波,实时性较强,算法也较简单,不但能算出谐波幅值,还能求出其相位,且和采样起始时刻没有关系,但是此方法要求采样严格的与基波过零同步。

Proliferation of power electronics loads, such as variable speed motor drives, AC to DC rectifier and static power supplies, has degraded power quality in power transmission/distribution systems due to harmonics and reactive power. LC single tuned passive power filter has some intrinsic shortcomings in filtering performance. After 80s,customers pay more attention to harmonic pollution problem, with the rapid development of power electronic technology, active power filter technology as well as the steady improvement of high-voltage devices such as GTR, GTO, IGBT. Active power filter application on harmonic suppression and reactive power compensation has made great development, however, an important drawback of active power filter is its high rating and so-caused high cost, which restricts the application of active power filter. Generally, the rating of active power filter is about 1/3 of the load rating when only used for compensating harmonics and will be much bigger when used to compensate reactive power simultaneously. The present harmonic detection methods have different characteristics. This paper firstly introduces harmonic detection of separate frequency based on instantaneous reactive power theory and spectrum estimation, then simulation analysis is made to the two methods. Research show that ip. ig algorithm based on instantaneous reactive power theory can detect harmonic component instantaneously and has good real-time characteristics. But the detection results include both amplitude and phase information that cannot be separated; The one based on spectrum estimation can make off-line computation to certain orders of harmonics and the real-time characteristics is stronger than that of FFT, the algorithm is simpler than that of FFT; It can figure out the amplitude as well as the phase value, but this method requires the synchronization sampling of the fundamental wave in zero pass.