Case Study: Revised Engineering and Testing Practices Resulting From Migration to IEC 61850

Replacing hardwired connections with digital communications over Ethernet requires new engineering and testing practices. PPL Electric Utilities Corporation (PPL) recently designed, installed, and tested a new high-voltage substation using next-generation relay and control equipment. This next-generation substation (NGS) is based on networked Ethernet intelligent electronic devices (IEDs) communicating via IEC 61850. This paper discusses the new technical design details of networking IEDs over Ethernet, but also, and more importantly, it discusses how engineering, installation, and testing practices had to change to accommodate the new technology. PPL methodically replaced their previous protection and control design with a design that provides more functionality while migrating to IEC 61850 communications from multiple IED vendors. In the end, over 50 percent of the hardware, 60 percent of the hardwired connections, many disparate programmable devices, and several software programs were eliminated. New testing techniques were developed to test IEC 61850 communications, and wiring drawings were replaced with GOOSE messaging tables so that test technicians could identify the endpoints of the “virtual” wires. The NGS implementation required completely new communication design methods, IED configuration, verification testing, and system commissioning. This paper describes PPL’s process of developing best engineering practices for substation protection, integration, control, monitoring, metering, and testing. A discussion of these engineering practices and how they evolved provides valuable insight to engineers considering using one or more of the IEC 61850 protocols for peer-to-peer protection and automation or client/server methods for integration and automation. Lessons learned were associated not only with new technology but also with new procedures, such as how test technicians selectively block signals that communicate over Ethernet without physically disconnecting the IED from the network. The paper also discusses PPL’s creation of a project team consisting of representatives from engineering, operations, standards, and relay testing to collectively resolve concerns associated with system testing, future expansion, and maintenance of this design.