Long-Term Dynamics evaluation in restoring customer loads

A power system is in the normal state most of the time. A large disturbance may bring the system to the emergency state. If the disturbance is large enough, the system goes into outage state. Power System Restoration (PSR) following a complete or partial collapse, is the process of restoring power plants, re-energising the transmission networks, restoring customer loads and accomplishing this process as rapidly as possible without causing any further failure or equipment damage. In this paper, we explain modelling the loads, plants, and relays and dynamic load flow for simulation of Long - Term Dynamics (LTD). Further, one of important subject in load pickup, is dynamically calculation of load steps. Load pickup in small increments tends to prolong the restoration duration. With large increment, there is always the risk of falling into a frequency decline and recurrence of the system outage. In this paper a new method for dynamically calculation of load steps is presented. This method has capable of on-line guiding the operator for selecting suitable load steps. Simulation tests were carried out on 39-bus New England system, verify the effectiveness of the proposed method.