Modified simplex method for economic evaluation of transmission expansion projects

Abstract

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.

輸電網規劃項目評估是電力系統規劃決策中的重要一環,精確的評估需要考慮眾多因素。當前電力市場環境賦予其更多新的特點,使輸電網規劃項目評估更加復雜。針對這種情況,美國加州獨立系統調度機構(ISO)提出了一個用于輸電項目經濟評估方法學(TEAM)的基本框架,在這個框架中,從用戶、發電廠商、輸電網所有者或運行部門,以及全社會的角度出發,定義了4項經濟評估指標。文中基于這個框架結構,采用改進單純形法,通過發掘評估指標相對系統負荷變化具有近似分段線性的規律,對這一系列的經濟指標進行了估算。在規劃階段原始數據極為有限的情況下,這種估算方法能夠對各項評估指標進行快速、準確的估算,相對于傳統的逐小時詳細仿真計算方法優勢顯著。文中算例對3節點和修改后的IEEE 14節點系統進行了指標估算,結果表明,文中提出的基于改進單純形法的輸電網規劃項目評估方法是有效的,具有一定的實用價值。