Research On Three Phase Shunt Active Power Filter Based On Voltage Space Vector

This subject is a part of research on power grid harmonic suppression technology, which belongs to the Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20101402120004). With the extensive use of power electronic equipment, harmonic pollution has became more and more serious, power quality came down and different kinds of fault and accident happened continually. Traditional passive filter can only filter out some certain harmonics and highly depends on power grid impedance and components parameters. Compared with passive filter, the active power filter can dynamically compensate harmonic and reactive power, which has became the most effective way to solve harmonic pollution for its high detecting precision, good anti-interference performance and response performance.The harmonic detection and current tracking control method were introduced in this paper. Design hardware circuit and software program of three phase shunt active power filter system. The main contents are as follows:Described the harmonic damage, harmonic control technology, active power filter types, principle and development. The harmonic detection based on Unity Power Factor algorithm was studied. Adopted phase-locked loop to restrain the influence of voltage distortion, slipped-window integrator achieving low-pass filter to improve harmonic detecting rate and PI regulation to keep the stability of DC voltage.The current tracking control used Space Vector Pulse Width Modulation method. Meanwhile, the repetitive predictor was applied so as to improve real-time capability. Dead time and its effect of the switch tube in main circuit were analyzed. Then dead-time compensation was realized in the view of vector synthesis.Built a three phase shunt active power filter simulation model and selected circuit parameters, including APF capacity, AC interface inductance, DC capacitor and its voltage. Took simulation under the condition of stable load, mutagenic load and power distortion. The results showed the APF based on UPF harmonic detection and SVPWM current tracking control can bring down harmonic content to the national standard range.Set up the experimental platform of APF. Designed the control circuit to realize harmonic current detection and instruction current tracking, drive circuit to isolate and amplify PWM signals, and the corresponding protection circuit. Wrote software program, initializing F2812internal hardware resource, circularly executing keyboard scanning and processing procedures, embedding interrupt procedures which accomplish instruction current calculation and PWM pulse generation, etc. Experimented signal sampling and conditioning, zero crossing detection and phase-locked frequency multiplication, data fitting between sampling value and actual value, harmonic compensation. Then optimized and debugged the software and hardware configuration. Experimental results showed that the main harmonic in power grid can be compensated by this active power filter system. It can also be verified that the application of UPF detection and SVPWM tracking control in APF is feasible.