Impact and improvement of Distributed Generation on voltage quality in Micro-grid

This paper illuminates some voltage quality problems caused by distributed generation (DG) in microgrid, including voltage fluctuation, voltage sag and voltage swell, voltage uplifted and harmonic resonance due to large capacity capacitor switching and so on. It studies the characteristic of these kinds of voltage quality problem and their impact on microgrid. According to these characteristics, this paper presents a method which depends on the type and structure of DG in microgrid to improve the voltage quality. The studies show that the penetration of DG in microgrid has beneficial improvement of system response to voltage disturbances. Rotating type DG can mitigate voltage fluctuation caused by rapidly changing loads due to its short circuit strength. Inverter type DG also has beneficial impact on voltage fluctuation if it has voltage regulation function. Simulation and analysis on a system model show that the proposed approach is effective and promising.