Dynamic models for transient stability analysis of transmission and distribution systems with distributed generation : an overview

Distributed Generation is increasing in nowadays power systems. Small scale systems such as photovoltaic, biomass or small cogeneration plants are connected to the distribution level, while large wind farms will be connected to the transmission level. Both trends lead to a replacement of large synchronous generators as the dominating generation technology. Up to now, transient stability of transmission systems has been analysed to a satisfactory degree of accuracy with a simplified representation of the distribution systems. In future, distributed generation will more and more influence the behaviour of the system. Stiff, inverter-based local generation technologies may improve the system stability; however, increasing electrical distances between large synchronous generators in operation will impede the system stability. These (and other) diverging effects have to be studied in detail. This overview paper summarises the latest findings and reveals future research questions. It is concluded that the accuracy and validity of the currently applied dynamic models for transient stability analysis of power systems with high penetration of DG should be further investigated.