Study on voltage quality of distribution network with high penetration of DG

The combination of the grid and DG is considered as a main method which can save investment, reduce fossil energy consumption and improve the reliability and flexibility of the power system. However, the high penetration of DG will severely influence the distribution network. This paper studies a typical structure of distribution network, analyzes the principal theory and sets up the simulation model. The simulation analysis at different cases shows that in mid-voltage or low-voltage distribution network, the energy flow from DG is the essential reason incurring voltage quality problems. Moreover, the voltage quality problem mainly comes from the change of the real power due to the big impedance ratio R/X of the line. The voltage quality problem will be improved by injecting power to regulate voltage with the inverter-based DG. From the result of simulation analysis, this paper provides a method to improve voltage quality with the power electronic inverter of DG.