Exploring benefits of controllable series compensators in power systems

摘要

This thesis examines the benefits of the controlled series compensation (reactance and phase angle control) of transmission lines for improving power system performance. Part I is concerned with the study of the controlled series compensation power flow control in the steady state. The impact of the controlled series compensation is studied through developing injection and quadratic models. The sensitivity of active power flows with respect to series compensation is analyzed. The power flow control problem is formulated and a solution based on the Newton's method is proposed. A concept of feasible line flow region, which shows a region for existence of the power flow control solution is presented. The power flow control problem using discrete controllers is analyzed and a method for optimization of the controller step size for a given line flow tolerance is proposed. Part II deals with the use of the controllable components for improving the stability of power systems with regard to electromechanical oscillations. The influence of load characteristics and transmission line loading on the damping effects of the controllable components is investigated. The impacts of the controllable series compensation and controllable shunt compensation on damping of inter-area and local modes are analyzed through the study of the eigen-structure of the linearized study system. Enhancement of large and small disturbance stability by using a switched series capacitor is proposed based on using a fuzzy logic controller.