The analysis and improvement of voltage quality in the distribution system with distributed generation

Based on the analysis of voltage-power characteristics of the distributed power supply system (the distribution system with DG), it proposes the methods of using super capacitor energy storage and microturbine to smooth the fluctuations of DG to improve the voltage quality respectively. The method of improving voltage quality based on the super capacitor energy storage, can compensates for the fluctuations of DG quickly, ensuring the common output power of DG and super capacitor energy storage stable, thus ensuring the power balanced and voltage stable in the distributed power supply system. The approach to improve the voltage based on the microturbine, during the normal operation, the DG assumes the baseload of the feeder, and the microturbine assumes the remaining loads of the feeder and in hot standy state. When the fluctuations of DG caused by the variation of external environment happen, it can quickly smooth the fluctuations of DG by the control of microturbine generation system, making DG/microturbine a schedulable and stable power source, thus achieving the stable control of bus voltage. Taking the distributed power supply system with wind power as examples, the PSCAD-based simulations of the above two methods are performed respectively, and the simulation results show that when the output of wind power fluctuates, the proposed two methods both can improve the voltage quality of the distributed power supply system effectively; when the external faults occur, the system voltage fluctuations and voltage recovery time can be effectively reduced, which verifies the effectiveness and feasibility of the proposed methods. Finally, it discusses other measures and their characteristics for voltage quality improvement in the distributed power supply system currently, and looks into the future of voltage quality improvement in the distributed power supply system.