The Ternary Analytical Method On Static Voltage Stability

The electrical power system stability has always been the primary problem concerned by researchers. This problem becomes more and more complex with the large scale of power system and development of power market. Analysis on angle stability and voltage stability are the two main aspects of power system stability, which have been developed over years. The angle stability analysis and control does have reached an upper level, however, there are still insufficiencies in voltage stability on its mechanism and methods of monitoring and control as well as the relationship between angle stability and voltage stability. The research on voltage stability is subsequently blocked especially by the uncertainty of the selection and parameters of load model as well as the operation variables of the dynamos. Therefore, for monitoring and control of voltage stability, it is still challengeable and of great significance to implement profound research on the mechanism so as to construct an on-line index of voltage stability.The shortcoming of using voltage and power to describe the voltage critical state is analyzed and the load impedance angle is introduced for the critical point of voltage. The ternary analysis method of voltage V, power P and load impedance angleφis established. And the ternary V -φand P -φspace analysis method is formed. The space V -φand P -φis used to describe voltage critical state and the curves for V cr-φand Pm ax-φare obtained. The changing property for V -φand P -φspace of voltage critical state is analyzed. The voltage stability space is built. Comparison analysis between voltage changes in V -φ, P -φspace and common curves, the criterion of impedance modul is made. And it is a good supplement to the space analysis method. They are the three spaces of the ternary analysis method. Simulation results testify the validity and correctness of this method.The equivalent parameter estimation and on-line voltage stability index at weak buses of network side based on phasor measurement is presented. The varying properties for local nodal voltage and current are analyed theoretically. The method of using local nodal voltage and current change to estimate equivalent impadence...