Research On Composite Compensation Control Strategy For Buck Type Dynamic Capacitor

The widely use of motors, transformers and power electronic devices deteriorates power quality, while the demand of high power quality for industrial users are growing. Therefore the technology of reactive power compensation and harmonic suppression is getting more attention. Nowadays, Static Synchronous Compensator and Active Power Filter are put in use widely. Due to the high price and the poor quality of electrolytic capacitors, a novel cheaper and stable solution for reactive power compensation and harmonic suppression has come into being: Dynamic Capacitor(D-CAP).Based on Buck type DC-DC converter, this paper first introduces the basic topology of Buck type D-CAP. Then the working principle is analyzed, and a PI controller for reactive power compensation is adopted. For reactive power and harmonic composite compensation method, Even Harmonic Modulation(EHM) was introduced. And a virtual multi synchronous rotating dq coordinate transformation is built. Simulation model is established using MATLAB/SIMULINK software and above control strategy was verified through simulation results. Resonance problems found in the simulation was discussed, and a possible solution of resonance suppression was proposed.At last, an actual D-CAP experimental equipment is designed. Then a novel active snubber is introduced. The digital control system is based on DSP+CPLD. Finally, the open loop experimental results demonstrate the basic function of D-CAP, and the boot, shutdown and fault protection function are tested.