Distortion Currents Detecting Method Based On Adaptive Linear Neural Network

Active power filter is an advanced power electronic device, which can be used for integrated compensating harmonic. Compared with some conventional measures, active power filter has many advantages and favorable prospects. Because of the characteristics, real time and accurate compensation, it is possible to take full advantage of digital signal processing and control technologies. If so, not only can the functions of active power filters be optimized, but also the performances of active power filters can be improved significantly. But it is difficult to adjust circuit parameters when loads or power conditions are changed. And the realization of the instantaneous reactive power with analog circuit needs large numbers of multiplicative implements, which cause the cost very expensive.Firstly, this paper discusses harmonic, harmonic control technologies and the application of active power filter in harmonic control, Because of the disadvantages of the instantaneous reactive power theory, the paper introduced another detecting methodof distortion currents-a detecting method of distortion currents based on adaptivelinear neural network.Secondly, the paper introduced adaptive linear neural networktheory , the nuclear algorithm-LMS algorithm, the theory of adaptive noisecounteracting and proposed detecting methods. On the base of theoretical analysis, a large number of simulations are developed, and the results show that the method has many advantages, such as real time, high accuracy, adaptability to load currents can make up the disadvantages of the instantaneous reactive power theory, the algorithm of this detecting method is also simple and easy to realize and modulate. But it needs two or three periods to follow the power system, the dynamic response is slow.Finally, the paper proposed an improved detecting method of distortion currents based on adaptive linear neural network.In this method, "u" is variable, it can vary between two values, when the system is in the process of dynamic response we choose "u" the bigger value, which can expedite the dynamic response; but when the system is in the process of steady condition we choose "u" the smaller one, which can ensure the detecting precision. The simulation show that the improved method is much more improved than the general in many aspects such as detecting distortion currents, harmonic currents, or the adaptive following ability to load currents, it is indeed a good method in detecting distortion currents.