Stable memory in substation automation: a case study

In high voltage substations, electromagnetic interference results in transient faults. Typically, hardware stable storage devices are used to stabilise data, to store status information of the controller and to protect the application against these faults. A case study of electric substation automation introduced a controller distributed on a parallel architecture and substituted the stable storage device by a fault-tolerant software implementation of stable memory. This allows the application to stabilise data to ensure its integrity. Based on the combination of temporal and spatial redundancy, it tolerates permanent faults in memory and transient faults affecting computation, input and memory devices. Transient faults lead to extra cycles before data is stabilised; permanent faults can be masked or lead to reconfiguration. The flexibility of the software architecture allows to fine-tune parameters according to application´s needs. This enhances reusability in wide automation areas. Evaluation confirms the suitability of the software solution during typical disturbances.