Study And Application Of Harmonic Elimination And Reactive Power Compensation For Low Voltage And High Current Rectifiers

With the electric power used widely, it has been a symbol of development and national power of country. Besides meeting the power requirement of industrial production, society and People's lives, power quality must be improved to enhance industrial production, scientific level and social civilization.As the main harmonic and reactive power sources in the grid, the research and control method of the rectifier is very important.Based on two different types of rectifiers in a large Copper Co., Ltd. in Hefei, this paper aims to research the technique and application of harmonic suppression and reactive compensation in the condition of low voltage and high current.Firstly, the generation of harmonic and reactive in power system is introduced, including the harmfulness and significance of control. Then, the measures and research status of harmonic elimination and reactive compensation are discussed, especially with power filter and reactive compensator etc.Secondly, this paper analyses two different types of rectifiers in detail with theory and simulation, and the harmonic content and power factor are obtained respectively. With the actual working conditions, two solutions combined passive power filter(PPF), active power filter(APF) and intelligent var compensator(IVC) are proposed, and the simulations of whole effect and harmonic current amplification are also carried out to verify the feasibility and practicability of the project.Thirdly, when the harmonic and reactive compensation system composed with APF and PPF work together, the control strategy and method have a great impact on filtering performance. Based on the discussion of operation principle with three control strategies and consideration of problem with different control strategies, this paper proposes a frequency division strategy and fast frequency division with no-error control method of APF. This method can resolve the problems of system stability and harmonic circumfluence which brought about by the parallel operation of APF and PPF, and it also has better filtering performance.Finally, due to the optimal design of parameters plays an important role in improving the performance of equipment, this paper proposes a series of parameters design which contain LC passive filter, APF main circuit and IVC capacitors. The design of hardware and software of APF and IVC are elaborated in detail, and the application condition is also given in this paper.It is proved that the design proposed in this paper can improve power factor and reduce the current distortion effectively. With low cost, easy maintenance and good operational aspect, it can bring remarkable economical and social benefits. At the same time, the design idea and engineering experience proposed in this paper can be popularized to other harmonic and reactive compensator, especially to the practical process of APF.