Harmonic On Power System Elimination Technologies

Today, power is a sort of important energy sources, it is widely used in many fields ofindustry,agriculture and national defence.With the development of electric power and electrontechnology, a number of the nonlinear loads and all kinds of commutating equipments arewidely applied in every walk of life, what they bring a mass of harmonic current make thecontent of harmonic increase in the power system and quality of power drop. So, it is urgent toeliminate harmonic and improve power quality.Recently,with the quickly development of power electronic technology, Active PowerFilter(APF) is being an important way to eliminate harmonic dynamically. It can outcome theinherent shortcomings of LC filters. APF is an advanced power electronic device, which canbe used for compensating harmonics, reactive power and negative sequence current.Compared with conventional LC filter, APF has advantages of real-time and accuracy. So APFhas foreground widely. but, in china, the studies and exploitations in APF are at its beginningstage, and large capacity mature products have not been coming out yet, so the studies in APFhave important significance.In this paper, we analyze the keys of APF——calculating the parameter of main circuit,harmonic current detecting and current tracking controlling. Neural network (NN) have thecharacteristic of detecting quickly, the emphasis is bring forward combining the neuralnetwork and auto adaptive harmonic current detecting based on the principle of noise eachother eliminating——the detecting method of neural network, it is applied detecting the totalharmonic current.At the same time, because of Redial Basis Function's (RBF)characteristics——smallcalculative quantity, fast convergence, without local minimal point, we apply RBF neuralnetwork to replace the traditional Back Propagation neural network, consisting a sort of newmethod for harmonic detecting——RBFNN's harmonic current detecting, and analyzing itsprinciple of filter, the structure of RBFNN and the arithmetic of adjustive weights.The methods of controlled PWM convertor are introduced, and detailedly analyze thedead-beat current method. At the same time, the method of controlled capacitance voltage atdirect current side is also analyzed.In order to verify the effect of RBFNN harmonic current detecting and controllingmethods, they are verified in the third part of this paper through the simulation of Matlab. Thesimulating results show their effect.The studies in this paper have some guidances and referrences on the exploitation of theactive power filter experimental system.