中文摘要：

提出一种改进的数字化变电站级联网络时延上界计算方法，从级联系统末端开始逐步细化数据流，逐步求取其后端级联系统对级联入口数据流的服务曲线，达到了“只需考虑单次突发”的效果。运用多种方法对采用交换式以太网环形拓扑构建数据采集网和GOOSE网合并的变电站过程总线网络进行计算，结果表明所提出的方法比采用上级离开曲线即下级到达曲线思路的方法更有效。

英文摘要：

An improved method is proposed to calculate the upper-bound of cascaded network delay in digital substation,which refines the data streams from the extremity of cascaded networks to derive the service curve of the following network to the input data streams of the previous network,with the effect of ＂pay bursts only once＂. The substation process bus network with ring topology of switched Ethernet,which incorporates the data acquisition network with the GOOSE network,is taken as an example to calculate the upper-bound of cascaded network delay by different methods. Results show that the proposed method is more effective than the methods based on the assumption that the departure curve of previous network is the arrival curve of following network.