本文提出利用滑動模式控制(Sliding mode control)來設計電力系統穩定器( PSS)。電力系統穩定器可利用最佳線性調整來設計,但利用此方法會造成設計上的耗費及減少可靠度。因此,我們提出只利用需要的狀態變數之控制設計,如角頻率及轉矩角。為了解決此問題,我們使用最佳化分離式設計將系統分離成數個子系統,再利用最佳降階法將每個子系統轉換成由發電機之角速度及轉矩角組成之二階系統,再經由滑動模式控制尋找每個子系統發電機適當的控制信號,以抑制整體系統負載變化。最後應用此方法於雙機無限匯流排電力系統,並與其他設計法比較。 This paper addresses a new approach for sliding mode control to design the power system stabilizers (PSS). The design of a PSS can be formulated as an optimal linear regulator control problem. However , implementing this technique requires the design of estimators. This increases the implementation and reduces the reliability of control system. These reasons, therefore, favor a control scheme that uses only some desired state variables, such as torque angle and speed. To deal with this problem, we use the optimal reduced models to reduce the power system model into two state variables system by each generator and use sliding mode control to find control signal of each generator, moreover, use optimal decentralized stabilizer to achieve control each generator. The advantages of the proposed method are illustrated by numerical simulation of the two machines-infinite-bus power systems.