Research On Power System Voltage Stability And Control

Development of modern power systems towards large scale power system, high voltage, and long-distance transmission plays an important role in economical use of energy, but also challenges the power system security. With several widespread system blackouts resulting from voltage collapse throughout the world in recent years, the problem of voltage stability has attracted persistent interests of researchers.In this dissertation we focus on two aspects: Singularity Induced Bifurcation (SIB) of power system DAE models, and High Side Voltage Control (HSVC), and some conclusion are derived.A) Based on bifurcation theory, a "single machine-constant power load" power system is studied to discuss the influence of excitation parameters (exciter-gain, excitation limit and voltage control point) on Singularity Induced Bifurcation (SIB).B) An efficient algorithm is developed to compute the closest direction to Singularity Induced Bifurcation by computing the left eigenvector of the Jacobian matrix of the algebraic part of DAE. To control power loads against this direction helps to keep a system away from SIB.C) Theoretically describes the effects of High Side Voltage Control (HSVC) on stabilities of a "one generator and one infinite bus" power system by the compensation of transformer impedance and the improvement of system damping. Eigenvalue analysis and step-by-step simulations show that HSVC can improve power system stabilities.D) Based on a simplified generator model, the eigenvalue analysis is performed on a single machine-constant power load system to study effects of the High SideVoltage Control (HSVC) on system voltage stabilities.E) Several problems, such as overvoltage, var sharing between units connectedtogether on a common bus, and cooperation of HSVC and LTC, are alsodiscussed.