Research On The Parallel Hybrid Active Power Filter Of Large Capacity

The harmonic pollution is becoming more and more serious and the demand of reactive power is increasing in the power network day by day because of the widespread application of non-linear power electronic installations. It also creates the power factor of system to be very low and brings the extra burden to the power network and influences power supply quality and the movement security. The Active Power Filter (APF) which is a kind of new dynamic electronic installation, can suppress the harmonic and compensate the reactive power. The harmonic and reactive power which has variational frequency and size, can be compensated by the APF. The APF can also make up the insufficiency of the tradition compensating method, and obtain better compensation characteristics comparing to the passive network. At present, the APF has become a hot discussion to "eliminate the pollution" of power system.At present, the single active Power filter can not meet the power system's objective requests of harmonic suppression and reactive power compensation with complication, low cost and large capacity, because of the limitation of the power electronic technology, series-parallel technology, and cost and so on. Therefore, according to the advantages and shortcomings of the active power filter and the passive network, the union of active power filter and passive network, which could supply superiority to each other, is an effective way to deal with the development and application of active power filter.This thesis introduces the related concept, production mechanism, research significance of harmonics and reactive power, and the present researching situation of harmonic suppression, reactive power compensation and APF, besides, the principle and compositions of APF are elaborated, and each kind of series-parallel APF is classified and compared in detail. Three harmonic current detecting methods based on the instantaneous reactive power theory are analyzed with emphasis, and the simulation comparison is carried on in the MATLAB. On this foundation, the parallel hybrid active power filter which has changed connection points is combined with the parallel capacitor banks to form the large capacity parallel hybrid active power filter, so as to increase the system's capacity of harmonic suppression and reactive power compensation, to enhance the power factor, to reduce the compensation capacity of APF and to reduce the cost. The single harmonious passive filter, parallel capacitor banks and output filter are designed in this thesis. The capacity, the filter characteristic and the stability in different control mode of the large capacity system are theoretically analyzed in detail.Finally, on the base of simulation of harmonic source, harmonic detection, and parallel hybrid active power filter which has changed connection points in the different control mode, the optimum complex control way is elected to simulate the parallel hybrid active power filter of large capacity by MATLAB simulation software. As a result, simulation and the theoretical analyses proved that the method is feasible and effective.