Study On Distributed Active Power Filter System

Along with the great development of power electronics and widely application with the power electronics equipment, there is a large amount of power harmonic in power system, it is a serious compromise in transmission quality of power system and the working safety of the electric equipment. Active filter which is an effective way to correct harmonic on the load's line, is already arising greatly attention and recognition. But the present researches just use one active filter for the harmonic created by one nonlinear load, it can not reach the perfect effect considering of the multi-harmonic source on the power line. So a new method of harmonic correcting which named the distributed active filter system is proposed in this thesis. The distributed active filter system is based on the active filter units, which are working together to correct the harmonic on the line, it is much better than just one active filter on the harmonic correcting effective, so it has a widely foreground and practicality value in project. The main tasks of the thesis are presented as follow:â‘ Analysis the different of using just one active filter and distributed active filter system on correction the harmonic on the power line in theory. It indicates that just using one active filter for correcting the harmonic created by the distributed harmonic source on the power line is really has some shortages. And it is proved by the simulation.â‘¡Analysis the mathematic model of the main circuit in active filter, design the main parameter based on the demand of harmonic correcting by active filter, and manage it in the later simulation.â‘¢Because the active filter is emplacing in different bus, and the position of each active filter units in distributed active filter system has a great influence on the harmonic correcting effective, so two rule about the best emplacing position is analyzed in theory, and it is proved by simulation results.â‘£A new current limited circuit is proposed, it analysis the harmonic current detecting after the harmonic detecting circuit, and reduce its value proportional when it's larger than the rated current of active filter, and ensuring the safely working and compensation effective. It is proved by the simulation results.