Study On A Shunt Hybrid Active Power Filter

With the rapid development of social economy, a large number of power electronic devices are placed in power grid, which creates sound economic profits as well as harmonics for grid. Harmonics, not only negatively affects the normal working of electrical facilities, but also brings about potential risks for the security of power grid and the economic functioning. One of an important way of eliminating harmonics is to install a filter. The traditional way is to adopt the LC passive filter. However, the filtering results of this kind of filter are largely affected by the change of system impedance, and it can only eliminate the harmonics of given order. Additionally it will probably produce the resonance with the system, which leads to the enlargement of harmonic current and makes the passive filter be burned down because of the overload. The active power filter (APF) is able to excellently overcome the limitations of the passive filter, so that it has become more and more concerned. However, most substations have to carry out the reactive power compensation while they are eliminating harmonics. If the AFP is adopted to compensate large-capacity reactive power, it is required that the APF should have large capacity. As a result, on one hand the costs of installing the filtering device are huge; on the other hand it is technologically difficult to implement the large-capacity APF because the installing capacity of the APF is limited by the capacity of switch device.The paper presents a hybrid active power filter (HAPF) installing APF and a LC injected circuit in series, and then connecting them in parallel with passive filter ,which fully combines the merits of APF and passive filter but discards the defects of the two. Especially, many factories and mines have extensively installed groups of capacitance to compensate reactive power so as to enhance the power factor, and parts of power consumers even adopt the passive filter to compensate harmonics. However, due to the change of the grid or equipment, a lot of problems are produced. But the HAPF decreases the second investment of the compensating system, increases the price versus performance ration, and achieves the aim of multifunctional compensation.This paper, on the basis of profoundly studying the topology model of the...