Abstract
Voltage stability occurs when power systems suffered severe contingency or unpredicted load increasing. In order to quantity to voltage instability, the concept of the loading margin has been proposed to measure the distance from the current operating point to the voltage collapse point. This thesis will study preventive and enhancement control actions via the sequential linear programming(SLP) techniques enhance the load margin. The prototype simulation program for preventive control and enhancement control has been implemented in Matlab. The entire program consists of three tasks: First, the continuation power flow will be explored to obtain load margins for the base case and N-1 contingencies. The load margin sensitivity with respect to various control actions, such as active/reactive power generations, LTC transformer taps, shunt capacitors and loads shedding, will also be derived. In the second task, contingency ranking will be performed. The most severe cases will be chosen for studying preventive control and enhancement control. Finally, both preventive control and enhancement control problems will be formulated as SLP problems. Both IEEE 14-bus and 39-bus systems have been tested to validate our methods. Comparison studies between the proposed method and the commercial software VSA demonstrate that the proposed method can indeed find proper control actions preventive control and enhancement control problems.