基于Blackman-Nuttall窗改进FFT校正的新型三相动态谐波电能表设计

针对电网动态谐波检测与电能计量的急切需求,建立了改善动态谐波FFT频谱泄漏和旁瓣效应的基于Blackman-Nuttall窗三谱线改进FFT校正的谐波电能计量方法,提出了ADS1178+TMS320C6745+K60架构的新型三相动态谐波电能表的设计和研究方案,详细介绍了多通道、高采样率、同步采样ADC的数据采集和调理电路单元,以及以高性能浮点DSP芯片TMS320C6745为核心的电网信号数据处理电路单元,提出了基于牛顿插值的动态谐波电能计量的误差校正方法。实验与测试表明,新型三相谐波电能表的基波有功功率相对误差≤0. 1%,基波无功功率相对误差≤1%,2次～21次谐波电压幅值相对误差≤0. 6%、谐波电流幅值相对误差≤0. 7%、谐波相位误差≤0. 5°,符合国家标准GB/T 14549-93中的A类谐波测量仪器相关精度要求。

Design of a new three phase dynamic harmonic power meter based on Blackman-Nuttall window and improved FFT correction

In order to meet the urgent needs of power grid dynamic harmonic detection and power metering, a harmonic power metering method based on Blackman-Nuttall window tri-spectral line is proposed to improve the spectrum leakage and sidelobe effect of dynamic harmonic FFT. A new three-phase harmonic power meter scheme based on ADS1178+TMS320C6745+K60 is proposed. The data acquisition and conditioning circuit unit of multi-channel, high sampling rate and synchronous sampling ADC and the grid signal data processing circuit unit with high performance floating-point DSP chip TMS320C6745 as the core are introduced in detail. The error correction method of dynamic harmonic energy metering based on Newton interpolation is also presented. The new three-phase harmonic energy meter developed on this basis has the following characteristics: the fundamental active power measurement error is less than 0.1%, the fundamental reactive power measurement error is less than 1%, the 2-21 harmonic voltage measurement error is less than 0.6%, the harmonic current measurement error is less than 0.7%, and the harmonic phase measurement error is less than 0.5 degrees, which meet the relevant accuracy requirements of the Class A harmonic measuring instruments in the standard GB/T 14549-93.