Development Of A Device For Metering Harmonic Energy In Electric Power System Based On DSP

With the development of power electronics, harmonics have become a potential threat to the secure, stable and economic operation of power system and have greatly influenced the surrounding electrical atmosphere. Harmonics are thought to be a public harm to the power network and hinder the development of power electronics technology. Aside from threatening the secure use of electrical apparatus, harmonics, especially the orientation of harmonic current, seriously influences the accuracy of power measurement. Most measurement equipments today, which are designed based on basic wave, can not measure harmonics. Therefore, the equipment that can accurately measures the power of both basic wave and harmonics is in urgent need so that it can lay the foundation of coming up with necessary regulations to control harmonics and fine the harmonic source.The development of DSP has provided a powerful technological support for designing such equipment. The design in this paper uses circuits to sample the data of both voltage and current, DSP to FFT the data to get the values of harmonic voltage and current, and algorithm to get the power of harmonics. The software development adopts blocking design method. The hardware includes four parts: preposed circuit, sampling circuit, DSP circuit and display circuit. The software includes four parts: main program, FFT program, power algorithm program.It has been proved by experiment that by the error-compensating, the equipment can accurately figure out the power of harmonics in power networks. The accuracy is in grade 0.2. By further improvement, it will have a promising future.