Studies On Power Quality Conditioner Based On SCES

With the increasing importance of power quality and continuous development of Supercapacitor technology, it exhibits broad prospect to utilize SCES ( Supercapacitor Energy Storage) for the power quality improvement. In this dissertation, one king of SCES based power quality conditioner is analyzed and studied systematically.Parallel-processing topology of main circuit is determined according to the functional demands of the studied system. In the designed system, SCES is utilized as energy storage component, Non-isolated bidirectional Buck-Boost DC/DC converter is utilized as DC voltage converter component, voltage source converter(VSC) is used to accomplish DC/AC converter. The main function of the system are to eliminate the influences of source voltage sags, asymmetry and flicker on load voltage, and to restrain the influences of unsymmetrical load on supply current. Based on the characteristics of SCES, the operating principle of the system is established. The active power as well as reactive power of the DC/AC converter is regulated to stabilize the load voltage when the source voltage sags occur.The system mathematic model is established, by which the system control strategy with decoupling and feedforward compensation of d/q components under synchronous rotating coordinate system is studied.Software Phased-locked Loop (SPLL) and effect of its restraint on aberrant voltage are discussed.After being extended and modified, the said control method is adapted to other functions of the converter.A simulation platform of the proposed system structure and control method is developed by using Simulink of the Matlab. Simulation results are provided to show effectiveness of the topology and control strategy.