With the rapid development of local generation and demand response

the active distribution network (ADN)

which aggregates and manages miscellaneous distributed resources

has moved from theory to practice. Secure and optimal operations now require an advanced situation awareness (SA) system so that operators are aware of operation states and potential risks. Current solutions in distribution supervisory control and data acquisition (DSCADA) as well as the distribution automation system (DAS) generally are not able to meet the technology requirements of SA. In this paper

the authors' participation in the project of developing an SA system as the basic component of a practical active distribution management system (ADMS) deployed in Beijing

China

is presented. This paper reviews the ADN's development roadmap by illustrating the changes that are made in elements

topology

structure

and control scheme. Taking into consideration these hardware changes

a systematic framework is proposed for the main components and the functional hierarchy of an SA system for the ADN. The SA system's implementation bottlenecks are also presented

including

but not limited to issues in big data platform

distribution forecasting

and security evaluation. Potential technology solutions are also provided.