Characterization and impact of extreme forecast errors on power systems

Extreme events in the electrical power system, caused by the load and wind forecasting errors, can impact the power system infrastructure via two main avenues. The first avenue is a sudden and significant power unbalance exceeding reasonable operating reserve capacity. The second is a sudden increase of power flows on the system critical paths causing transmission violations. The challenge in managing these system unbalances is more significant for a stand-alone balancing area operation. The consolidation of balancing authorities into a single balancing area can offset the operating reserve problem, but this strategy enhances incremental power flows on the transmission interfaces, potentially leading to more unpredictable transmission congestion. This article evaluates the expectation of occurrence of extreme events due to forecast error extremes using California Independent System Operator and Bonneville Power Administration data. Having this type of information, independent system operators and operating utilities could be better prepared to address the extreme events by exploring alternative reserve options, such as wide-area control coordination, new operating procedures, and remedial actions.