Roadmap To Zero Misoperations

In 2019, Eversource aimed to limit system misoperations and to set a goal of zero misoperations. At the time, Eversource had a rolling five-year average misoperation rate of 16%. This drew significant attention and questioning from senior Company leadership, which set a goal of zero misoperations. Protection and Control (P&C) Engineering was tasked with leading the initiative. To facilitate this goal, we held a cross-functional team workshop with guidance on industry experience from our external partners to identify causes of transmission system protection misoperations and to strategize on how to reduce their occurrence, driving as close as possible to zero misoperations. The investigators reviewed misoperations for three years leading up to 2019 to develop recommendations for actions that might be applied to address root causes. For each misoperation, the actions that could help reduce or eliminate the risk of further occurrences were tagged. The investigators assigned a per-unit effectiveness to each misoperation – this means that if the tagged actions were taken and the related processes were in effect, the resulting per unit value expressed what portion of future misoperations of the same nature could we expect to avoid. Considering the misoperation data, the investigators identified that the root causes for protection misoperations go beyond the protection settings and engineering specifics. Eversource identified the following major categories of activities with opportunity to reduce risk of protection misoperations: Engineering Design, Relay Settings, Equipment Failure, Construction Issues, and Maintenance including Testing & Commissioning. With 89 misoperations tabulated over three years, the investigators concluded that an estimated 59.5 of 89 future similar misoperations could be avoided – close to two thirds of them. The investigators underscore that, to achieve this result, the recommended actions must have been taken, having achieved effective operation of a substantial group of new processes and systems. This is a major undertaking that requires time and effort. This paper intends to summarize the investigation efforts, the recommended actions, the implementation efforts initiated, and finally a review of Eversource misoperation performance and experience since this initiative.