Research And Design On The Quality Control Device For The Distribution Systems

The active power filter (APF) is considered to be the most effective way to manage the power grid harmonic wave compared with fixed passive filter at present, but its detection and control method are not the best.The APF model machine is developed totally, which is not only used to prove the detection and control algorithm refered by this paper but also can be used by other algorithm. And thus, it is very convenient to update the algorithm and system. For recently there is no complete APF system simulation, an complete APF simulation model is built, which is more of integrality and accuracy compared with blocking part simulation. What's more, the simulation code is very convenient to transplant to DSP platform. On the harmonic detection algorithm aspect, The discrete fourier transform (DFT) sliding window iterative based on coordinate transformation is put forward after comparing various kinds of algorithms. The simulation result proves that this algorithm is of fast detection speed and with less tracing error. On the harmonic current compensation aspect, harmonic current hysteresis controlling is popular in practice. But the APF machine produced this algorithm output waveform with more noise, moreover the IGBT switched with high frequency, this is bad to the grid compensation. For this phenomenon, a combined harmonic control algorithm is put out, which is combined with recursive integral PI algorithm and sliding-mode control algorithm. This combined control algorithm not only reduces the APF switch noise but also improve the robustness and accuracy.At present, it is not very convenient for the APF development and improvement for the machine should be put into practice to check the compensation result. So it is necessary to develop and harmonic power supply to simulate the real polluted grid, and it is flexible to produce any harmonic overlying the fundamental wave. The harmonic power supply is produced by the project, which reduced the APF construction cycle significantly.The lab APF model machine is designed and researched at the last part of the paper, with the core of digital control system based on DSP(TMS320F2812)+CPLD(EPM3256ATC144). The photographs and experiment waveforms are presented in the paper to prove the harmonic detection and control algorithms are correct.