Research On Detection And Control System Of Shunt Active Power Filter

The development of power electronic devices and a lot of fast power electronics technology is widely used in metallurgy,steel and chemical sectors,which leads that the harmonic pollution is worsening.The harmonic electrical equipment results in great harm to the power system.Active power filter is an advanced power electronic device,which can not only suppress harmonics but also compensate reactive power.It is a good solution to the problem of harmonic pollution.In this paper,the shunt active power filter is taken as the research object,and the detection and control system of shunt active power filter is designed.The main research works are as follows:(1)The basic principle of active power filter is analyzed.The mathematical model of active power filter is established according to the equivalent circuit connected to the power grid.The selection principle of DC bus voltage,capacitance and inductance is given based on the mathematical model and theoretical analysis.(2)Real time detection algorithm based on instantaneous reactive power theory is studied.p-q and ip-iq detection algorithm model is established using Matlab/Simulink.The simulation results show that the ip-iq detection algorithm has better detection performance whether the voltage is distortionless or distortion.The influence of the order and cut-off frequency on the detection accuracy and tracking speed is analyzed by simulation for the design of low pass filter.And the cut-off frequency and order of the low pass filter are determined.On the basis of this,a digital low pass filter is designed,which is satisfied to the requirement of detection accuracy and tracking speed.(3)The hysteresis current control algorithm based on space vector is studied.The model of active power filter has built using Matlab/Simulink.The result which is compared with traditional current tracking control algorithm shows that the hysteresis current control algorithm based on space vector has better compensation effect in the static load,the transient load and the voltage distortion conditions.The PI control method of DC voltage is also analyzed in this paper.The simulation results show that the capacitor voltage can be well stabilized at the reference value after the PI control link is added.(4)The software and hardware of detection and control system of shunt active power filter is designed based on DSP.The design of hardware includes power grid voltage and load current,compensation current sampling control,DC voltage isolation,synchronous sampling signal acquisition,anti aliasing low-pass filter and power module drive and fault output.The design of software includes power grid frequency calculation,AD sampling program design and ip-iq detection algorithm and the hysteresis current control algorithm based on space vector.To verify the effectiveness of the detection and control algorithm,the experimental platform has been set up on the basis of hardware and software design.The experimental results show that the detection and control system designed in this paper can effectively suppress harmonic and laid a solid foundation for the practical application of active power filter.