Online Probabilistic Security Risk Assessment Implementation at China Southern Power Grid Towards Smart Control Center

China Southern Power Grid Company (CSG) and eMIT, LLC recently developed and implemented an online risk-based security assessment system-Probabilistic Security Risk Assessment (PSRA). PSRA calculates the probability of undesirable events in the transmission system and evaluates their corresponding severities. PSRA combines the probability measure of each undesirable event with the consequence measure into a single reliability index-Probabilistic Loss of Load Index (PLLI). When PSRA determines the system condition to be insecure, it optimally re-dispatches the generation to ensure the system goes back to the secure region. Under emergency conditions, when generation re-dispatch alone is not enough, load shedding will be enforced to bring the system back to the secure region. The salient aspect of PSRA is automatic application of program-determined remedial actions inclusive of load curtailment. Weak point analysis is developed and used to identify the buses and branches that are most vulnerable. A novel method is developed to visualize the Probabilistic Loss of Load Index, which makes it easy for the system operators to make decisions within a shorter time period. Online implementation of PSRA is also discussed and it is concluded that the proposed probabilistic reliability analysis is much more accurate than traditional methods and it provides system operators the capability to make faster trade-off decisions between economy and technical constraints.