| Abstract |
Distributed generation (DG) units increasingly become subject to grid codes requiring an active andreactive power control capability. Since voltage source converters (VSCs) represent a key componentin many DG units, accurate but simple models are crucial for analysing transient grid phenomena andto find adequate solutions that help to maintain a high power quality. This paper presents a simplifiedanalytical model of a grid-connected VSC, which covers the power flow from the primary energy source,over the DC link to the injected converter's output current for frequencies well below the converter'sswitching frequency. After modelling all relevant components of an open-loop power-controlled VSC,a model reduction is performed with special emphasis on the influence of DC link dynamics. Finally,the resulting model accuracy is validated and compared to its low-frequency approximation by means ofcomputer simulations and Bode plots, respectively. |
