Dsp-based Single-phase Shunt Active Power Filter

In the modern power system, with the widespread application of various electronic devices which are non-linear, the quality of electricity supply has attracted much attention. These electronic devices which transfer harmonics into the power system have deteriorated the efficiency of power transmission. The harmonics pollution in electric system is much more serious. So it is more urgent to solve the problem of harmonics.The passive filter has been traditionally chosen to restrain harmonious wave, however, it has lots of disadvantages, such as filter characteristic being influencing by system parameters, only restraining given harmonious wave, possibly bringing shunt-wound resonance with the system and the increasing of harmonious wave current leading to overflow the system load, and those affect the effect of harmonious wave compensation.This paper intends to introduce a highly efficient new design of single-phase DSP (digital signal processor) based Active Power Filter(APF). The new system, able to detect and detach harmonic and reactive current, is based on the notion of instantaneous reactive power and Adaptive Noise Canceling Technology of the artificial neural network (ANCT , ANN) , capable of eliminating the troublesome harmonics generated by nonlinear loads with a Pulse-Width Modulation (PWM) rectifier topology.First, the basic principle of the parallel single-phase active filter is introduced in the paper. Then, the design of main hardware structure is presented, and the characteristics of the DSP TMS320F240 used in the power filter are also brought into a detailed discussion. The approach of i_p-i_q detection ,which is based on the theory of instantaneous reactive power, applies a FIR (Finite impulse response) digital low pass filter to fulfill an exact measure. The hysteresis current control method is applied to the PWM rectifier. Finally, the results of MATLAB simulation verifies the feasibility of the design.