The Power System Static Stability Analysis Based On The Comprehensive Dynamic Equivalence Method

In recent decades,because of the power system network is constantly increasing,the power system instability led to a number of large area power outage.The voltage stability analysis of power system is more important and complicated.The power system static stability is an important factor of system safety and stable operation.So we need to conduct more in-depth research on the stability of power system static.This paper uses the analysis of scattered dynamic equivalent method to study the power system stability.The comprehensive dynamic equivalent method was proposed,by introducing current auxiliary variable and flow equations.Voltage stability analysis is greatly simplified.The necessary condition when the load power of the PQ node in power systems achieves limit transmission is that the comprehensive dynamic equivalence impedance mode is equal to load static equivalent impedance mode by using analysis method of complex variable voltage stability problem.The impedance model margin index that is used to assess the voltage stability was proposed.The necessary condition when the angle stability of the PV node in power systems achieves limit transmission is that the comprehensive dynamic equivalence resistance mode is equal to load static equivalent resistance mode by using analysis method of complex variable voltage stability problem.The power coefficient was transformed into the resistance margin and the resistance margin that was used to evaluate angle stability was proposed through the analysis of power system Angle characteristic curve(P-?features).The power system voltage stability and Angle stability are analyzed based on the basic principle of general nonlinear equations take extreme value.The analysis of scattered dynamic equivalent method was proposed by the wave equation of power injection variables to calculate the derivative based on the trend of the equation dynamic characteristics of node power injection systems is considered and the chain derivative method of compound function.This method was used to calculate the system dynamic parameters of equivalent circuit.Then the impedance model margin of the voltage stability and the resistance margin of the angle stability were calculated.When the power system voltage stability and the angle stability reach limit state,the impedance modulus margin and theresistance margin are zero.The conclusion shows that the impedance modulus margin(the resistance margin)as the judgment system voltage stability(the angle stability)index is correct.The impedance model margin is a visual indicator of voltage stability.According to the size,the voltage stability of power system load node can be sorted.It has the very high value to control voltage stability at the weakest node.The resistance margin has the nonlinear nature.The monitoring of the resistance margin does not require the system to global information.It has high application online value.The methods of this paper are verified correct by the simulation calculation of the impedance model margin and the resistance margin under different load levels in IEEE14 and IEEE30 node system.