Online Transient Stability Assessment

With the advent of deregulation in the power industry and a lack of transmission investment, today’s power systems are operated much closer to their limits. Stressed system conditions mean that operators are faced with scenarios that never occurred in the past. Various critical decisions need to be taken in real time and this requires sophisticated software tools. One of the main issues that needs to be tackled deals with online dynamic security assessment and control. The objective of dynamic security assessment and control is to ensure that the system can withstand unforeseen contingencies and return to an acceptable steady state condition without transient instability or voltage instability problems. In this chapter, the application of a software tool that uses artificial intelligence (decision trees; DTs) is discussed. The approach is developed by training a set of trees based on simulations that are conducted offline. With advances in computer technology, it is now possible to create and store large databases that can be used to train agents. In this case, the agents are the DTs and the DT building procedure identifies critical attributes (CAs) and parameter thresholds. In order to evaluate stability limits in terms of critical interface flows and plant generation limits, the use of synchronized measurements from phasor measurement units (PMUs) has been proposed.