摘 要：随着我国国民经济的发展，电力负荷急剧加大，谐波损耗的问题也越来越受到人们的重视。谐波损耗能使发电、变电和用电设备效率降低。加速电力电缆绝缘老化，影响继电保护自动装置动作的准确性。对通信线路和控制信号造成电磁和射频干扰。在产生谐波的同时，还会引起电压波动、产生负序电流、功率因数偏低等危害电网和设备的不良影响。为了解决谐波问题，有必要设计一个谐波检测仪对谐波进行检测。68624

    本文首先阐述了谐波分析的原理，研究了FFT算法以及加窗插值的高精度改进算法。在此基础上本文以51单片机为核心，使用了包括电源模块、互感器单元、信号预处理模块、A／D采样电路、数据处理电路、键盘数码管显示模块进行设计。软件设计以傅里叶变换为主。系统程序采用模块设计，实现了谐波的实时监测。

毕业论文关键字：单片机，谐波检测，电源模块

Abstract ：With the development of China's national economy, power load increasing sharply, harmonic loss problems also more and more get people's attention. Harmonic loss can lower the efficiency of power generation, substation and power equipment. Accelerate the power cable insulation aging, affect the accuracy of the relay protection device automatically. The communication lines and control signal caused by the electromagnetic and radio frequency interference. In harmonics at the same time, still can cause voltage fluctuation, produce the harm such as negative sequence current, low power factor of power grid and equipment of the adverse effects. In order to solve the problem of harmonic, it is necessary to design a harmonic detector for detecting harmonic.

At first, this paper expounds the principle of harmonic analysis, studied the FFT algorithm and add window interpolation precision improved algorithm. On this basis, based on 51 single chip microcomputer as the core, the use of including power supply module, transformer unit, signal preprocessing module, data processing circuit and A/D sampling circuit, keyboard, digital tube display module design. Software design is given priority to with Fourier transform. System program design of module, realize the real-time monitoring of the harmonic.

Key words:MCU,harmonic detection,Power supply module

目  录

1 绪论 1

1.1谐波的概念及其危害 1

1.2谐波检测方法的研究现状及发展 1

1.3 本课题研究的背景和内容 3

2 谐波分析及测量原理 4

2.1 快速傅立叶变换的基本原理 4

2.2 加窗插值的FFT高精度算法 4

2.3 电网电参量的计算 7

2.4 各次谐波分量计算 8

2.5 小结 9

3 系统硬件设计 9

3.1系统总体硬件设计思想 9

3.2单片机芯片的选择 10

3.3电源模块 12

3.4电流电压采集电路模块 12

3.5信号预处理模块 14

3.6 A/D转换模块 15

3.7 数码管显示模块 17

3.8 键盘接口模块 18

3.9 外扩数据存储器及程序