Power system stability assessment for current states of the system

A way of assessment of the transient stability reserve, using the trajectory of the dynamic transition, received by numerical integration of the dynamics equations for considered electric power system (EPS) at given disturbance, is reported. For each moment of time according to numerical solution of a transient process the Lyapunov function of energy type is calculated. By observation of its change in time the maximal value of potential energy is determined. It is compared with critical one, calculated as the nearest local maximum on the beam, going from a point of balance for post-emergency state in a direction of a found local maximum on a trajectory. This beam simulates increase of disturbance intensity, causing considered transient. Conservative model of EPS is used for assessment of the transient stability reserve, movement of ";mass centre"; is excluded from full movement of system, which the numerical decision gives, and stability on Lyapunov is considered only for mutual movement of machines. An error of calculation by offered method of limiting value of disturbance (the value of the shunt of nonsymmetrical short circuit) for the real power system is estimated about 4%. A procedure of transient stability assessment for current states of the system on the set of disturbances is offered. It uses ranking disturbanced states with the help of stability index (stability reserve). Checking steady state stability of power system is fulfilled by dynamic method.