key diagram meaning in English

概略原理图，解说图。

The paper presents a distribution analysis software platform which is developed combining computer graphical theory and oop ( object - oriented programming ) . the platform includes three modules , the graphics module , the database module and the computation module . the graphical module can draw the key diagram of power system ; the database module can save , browse and edit the data of power systems ; the computation module can compute the power flow
本文运用面向对象的程序设计方法结合计算机图形学的知识，开发了一套可视化配电网分析软件平台，它包括用于绘制电力系统结线图的图形模块、用于保存、浏览、修改电网数据信息的数据库模块和进行配电网潮流计算的计算模块。