Hybrid Protection and Control System for Distribution Substations in Power Utilities, Industries and Infrastructure

This paper describes a new `hybridized' approach [1] to substation protection and control systems for power distribution utilities, industries and infrastructure using the secondary system architecture. The Hybrid Protection and Control (HPC) system is based on a flexible distribution or even a replication of protection and control functions between devices at bay and substation levels via a highly-available and fast Ethernet network based on the IEC 61850 standard for substation communications. The system configuration comprises of dedicated merging units (MU) and/or numerical protection relays (PR) with merging unit capabilities for every feeder and a Centralized Protection and Control (CPC) unit. The desired levels of functional or physical redundancies can selected depending on the relative criticality of the feeders connected to the load centers or equipment in the network. The system solution integrates the contemporary substation secondary system and CPC unit(s), over a redundant IEC 61850 network. Besides running bay level functions for all feeders, the CPC unit also hosts advanced and complex intra or inter substation-wide functions and applications. This approach increases system flexibility, reliability and availability in distribution systems that makes it very exceptional. The approach can be well implemented in both green-field and brownfield projects. The main results show that the HPC approach aggregates benefits from both centralized and decentralized architectures with moderate changes in the secondary system.