中文摘要：

输电网规划项目评估是电力系统规划决策中的重要一环，精确的评估需要考虑众多因素。当前电力市场环境赋予其更多新的特点，使输电网规划项目评估更加复杂。针对这种情况，美国加州独立系统调度机构（ISO）提出了一个用于输电项目经济评估方法学（TEAM）的基本框架，在这个框架中，从用户、发电厂商、输电网所有者或运行部门，以及全社会的角度出发，定义了4项经济评估指标。文中基于这个框架结构，采用改进单纯形法，通过发掘评估指标相对系统负荷变化具有近似分段线性的规律，对这一系列的经济指标进行了估算。在规划阶段原始数据极为有限的情况下，这种估算方法能够对各项评估指标进行快速、准确的估算，相对于传统的逐小时详细仿真计算方法优势显著。文中算例对3节点和修改后的IEEE14节点系统进行了指标估算，结果表明，文中提出的基于改进单纯形法的输电网规划项目评估方法是有效的，具有一定的实用价值。

英文摘要：

In the deregulated electricity market, the economic assessment of transmission expansion projects becomes more complex. The interests of all market participants should be considered. A transmission economic assessment methodology （TEAM） is then proposed by California ISO （CAISO） to tackle this problem. This paper is built on the framework of TEAM and proposes an improved method to evaluate transmission expansion projects. A modified simplex method is developed and key load levels are defined, and thus the hour-by-hour simulation for the calculation of local marginal prices can be avoided. An LP optimization is conducted only when the condition of transmission congestion changes. Test results on the 3-node and the modified IEEE 14-node power systems show that the modified Simplex method gives timesaving evaluation of transmission expansion projects with good accuracy.