PRP and HSR for Redundant Frames Discarding

Critical systems require zero recovery time when a failure occurs in a communications network. The soon to be implemented standard IEC 62439-3 defines the only two protocols, parallel redundancy protocol and high-availability seamless redundancy, which fulfill this requirement and ensure no frame loss in the presence of an error. These protocols also provide a hot-plugging capability, which allows elements to be added to or removed from the network without interrupting communications and the operation of the plant. The electricity sector has adopted these for power utility automation in the recently published IEC 61850-90-4.

The challenge is to obtain an efficient approach for use in electronic devices, capable of managing the characteristic duplicates, and circulating frames of these protocols, coupled with agile architectures capable of dealing with real-time processing requirements, fast switching times, high throughput, and deterministic behavior. The main contribution of this paper is the in-depth analysis it makes of network parameters imposed by the application of the protocols to power utility automation, and the proposition of a frame management system based on a segmented memory system that improves frame detecting time and uses the smallest memory required in order to resolve all the issues dealt with.