Study of TCSC as an agent in deregulated power system operation.

摘要

In this dissertation, an important Flexible AC Transmissions Systems (FACTS) device, namely the Thyristor Controlled Series Capacitors (TCSC) is investigated. Modeling of TCSC for various simulation studies as well as some important issues related to the location and control of this device in order to enhance power systems static security against contingencies are studied.; The Least Squares Prediction-Correction (LSPC) algorithm has been successfully employed for estimating time-varying parameters of dynamic systems. In this dissertation, this method is employed for the estimation of power system frequency and voltage phasors during emergency conditions. The mathematical derivation of the method is presented and its application to power systems is demonstrated through examples. The firing angle and fundamental equivalent impedance are two crucial parameters of TCSC. A discrete-time model for the TCSC is developed and a tracking estimator based on this model is used to track the firing angle dynamically. The fundamental equivalent impedance of the TCSC is then solved based on the already developed model of the TCSC. These estimates facilitate effective control of the TCSC during daily operation.; Next, the problem of locating the TCSCs in a given power system is considered. A criterion called the “Single Contingency Sensitivity (SCS)” index, associated with a given branch, is defined for this purpose. This value is used to compute a ranking index for all concerned branches. Then, the problem of installing TCSCs to guarantee full observability of power flows under single-contingencies is investigated. The required number and location of TCSCs for a given set of contingencies are derived. Moreover, an optimization problem is formulated and applied to find an optimal setting for the installed TCSCs in case of considered contingencies in a power system. Elimination of the branch overloads and minimization of the unwanted loop flows during single-contingencies are accomplished via the solution of this optimization problem. These proposed methods for optimally locating TCSCs and setting their parameters are intended to improve the static system security and reduce power losses.; Simulations that are carried out using Alternative Transients Program (ATP) are used to evaluate the performance of the LSPC algorithm and the discrete-time tracking estimator, both of which are implemented in Matlab. The IEEE 14-bus and 118-bus test systems are used in simulations related to the illustration of optimal location and parameter setting of TCSCs for static security enhancement.