Harmonic Research Of The Distrbution Network With Distributed Generation

With the growing consumption of the electric power ,paying more attentions toenvironmental protection and the increasing demand of premium power quality, thedistributed generation has been concentrated and will be widely used in the future . Inthis paper, the occurrence, influence and elimination of harmonic in the distributionnetwork with distributed generation are discussed.The content contains:(1)The background, significance of distributed generation, characteristic of thedistribution network with distributed generation and development of harmonicresearch were analyzed and described in detail.(2)Harmonic resource, harmonic pollution and its elimination were analyzeddetailedly in the distribution network with distributed generation. According to thecharacteristics of distributed generation, this paper presents a new method thatcombines APF technology and distributed generation to solve these present harmonicproblems.(3)According to the demands of inverters in distributed generation systems, asmall signal model of inverters with APF function was built, and a proposed controlalgorithm that contained PI feedback and net voltage feed-forward was used indistributed generation systems. The simulation model and the proposed controlalgorithm were built by Matlab/Simulink, and the obtained simulation results showthat the proposed approach is effective and promising.(4) The parameters of power circuit and filter circuit are initiatively designed,and an inverter system with APF function was built. The programmes ofmulti-function inverters were achieved (used C language and assemble language) torealize full digital control. Based on ip-iq harmonic current measurement, a d-q axisharmonic measurement with a small computation was proposed for this system. Aadaptive phase-locked loop technique, which realized by hardware and softwaretogether, was used and achieved with DSP program. Base on the laboratorial system,the experiments in different working modes were accomplished. The results show thatthe inverter system with APF function can effectively reduce harmonic, enhancepower quality of power system.