基于2阶Hann自卷积窗的谐波电能高精度量测方法研究与实现

Research and implementation on the high-precision measuring method of harmonic electric energy based on 2-order Hann self-convolution window

分布式光伏发电根据全发电量进行补贴,无法约束其并网对配电网造成的高频次谐波污染和电压波动等电能质量问题。电能谐波含量是体现分布式光伏电能质量的因素之一,可作为并网电能定价的参考依据。为了对分布式光伏谐波电能进行快速、准确计量,文中采用2阶Hann自卷积窗及其双谱线插值校正算法,提出了一种低运算资源消耗的顺序型谐波计算流程,在其基础上优化设计了一种多级流水线型的谐波计算架构,大幅提升了加窗插值FFT的计算效率;考虑ADC量化误差,对2阶Hann自卷积窗及其双谱线插值校正算法的谐波分析效果进行仿真,提供了ADC位数、采样点数N与窗函数的选择依据。设计并开发了基于ZYNQ与LTC2358的谐波量测装置板卡样机。实验与测试结果表明,该样机的基波测量误差满足C级静止式有功电能表标准和0.5S级无功测量仪表检定标准的要求;此外,3~21次谐波测量误差满足A级谐波测量仪表检定标准的要求。

Distributed photovoltaic power generation is subsidized according to the total power generation,which has no binding force on the power quality problems such as high-frequency harmonic pollution and voltage fluctuation caused by its grid connection to the local network.Harmonic content of electric energy is one of quality factors of distributed photovoltaic power,which can be used as a reference for grid-connected electric energy pricing.In order to measure the harmonics of the distributed photovoltaic power accurately and quickly,the second-order Hann self-convolution window and its bispectral interpolation correction algorithm are chosen,and a workflow of the sequential harmonic calculation with low computing resources is present.Meanwhile,the architecture of multi-stage pipeline harmonic calculation is designed and optimized,which greatly improves the calculation efficiency of windowed interpolation FFT.Considering the quantization error of ADC,the harmonic analysis effect of the spectral line interpolation correction algorithm is simulated,and the determination of the ADC bit number,sampling point N and window function is provided.On this basis,the hardware architecture of the harmonic-energy measuring device based on ZYNQ and LTC2358 is given.Test results of a prototype show that its basic error meets the requirement of C-level static active energy meter standard and the 0.5S-level reactive power measuring instrument verification standard.In addition,the results of 3~21 harmonic measurement error show that its accuracy meets the requirement of the verification standard for A-level harmonic measuring instruments.