Object-oriented analysis and design of transient stability simulation for distributed power generation system

The designs of model abstraction and application abstraction of transient stability simulation for distributed power generation system are presented. The main classes are presented, which are called model classes, function classes and system integration classes. An AC/DC double layer bus-tree structure belongs to model classes for grouping elements of distributed generation system is presented, The DC bus tree structure includes subclasses of distributed sources and storages. The design scheme descries the double layer structure. In order to study the whole dynamic process of whole system, the digital simulation method capable of dealing with the stiff problem is integrated in function classes. With the efficiency and simpleness of calling mechanism for the functional functions of elements during computation, system integration classes are capable of considering the influence of typical microgrid operation modes which are grid-connected mode, island mode and grid-reconnected mode, etc, and capable of control the switchover from one mode to another mode.