Press Release:
WPRC technical paper: “Challenges Encountered in the Operation Analysis and Settings of a Parallel Three-Terminal Line Application”
Ann Arbor MI, October 9: Electrocon International staff will be providing in-depth demonstrations of its CAPE software for protection engineering at the Western Protective Relay Conference in Spokane, Washington October 20-22.
Also, of particular interest, Jeffrey Pond, National Grid, will start the Tuesday morning conference program with the paper, “Challenges Encountered in the Operation Analysis and Settings of a Parallel Three-Terminal Line Application,” which describes an event experienced by National Grid: an over trip of a Directional Comparison Blocking (DCB) Scheme on a 115 kV double-circuit mutually coupled line for a transformer lightning arrestor failure on a parallel, three-terminal line with an identical DCB scheme. The post-fault investigation identified the root cause of the event as improper application of relay settings. The paper describes the review and testing process followed to adjust the settings before taking them back online, and addresses these resulting questions:
- How can a misapplication of relay settings be avoided in the future?
- If end-to-end relay testing of the scheme cannot be scheduled, what other methods can assure the protection engineer that the relay settings have been properly applied?
- What applications are available to help ensure that the relay settings are properly applied?
In answering these questions, the authors show the importance of each of the following:
- A network model with accurate representation of transmission lines, generators, transformers, and other components, in both the positive- and zero-sequence networks.
- Ability to model protective devices from different vendors in full detail, so that the actual comparator equations and internal logic, to the extent possible in a phasor-based environment, can be considered.
- Ability to model the protection system as an entity, rather than just as individual protective devices working by themselves. This uncovers communication scheme issues and other problems that might arise after the first circuit breaker has opened.
- Ability to perform periodic wide-area coordination and sensitivity reviews. This ensures that as the system changes, and new settings are computed, overall coordination objectives are still being met.
With protection simulation tools that meet these requirements, the protection engineer can be confident that the settings he or she has computed will work well in the field.
Contact us to request a copy of the technical paper.
About Electrocon International, Inc.
Based in Ann Arbor, Michigan, Electrocon International, Inc. develops and markets CAPE software for protection engineering. CAPE’s graphical network modeling and system simulation support automatic relay setting, detection of miscoordinated settings, and event analysis. CAPE’s is the largest and most detailed library of relay models available. With more detailed, more accurate models, protection engineers study real life conditions, perform wide-area reviews, predict protection system performance, and much more. Electrocon provides ongoing technical support and CAPE-related services for its customers all over the world, which include transmission utilities and engineering firms of all sizes.
Electrocon has been developing tools for computer-aided protection engineering since 1985, working with input from protection engineers from leading North American power utilities. CAPE’s original mission was to create a combined network and protection system model that would support automated relay setting and coordination checking. Today, with a master library of over 5,500 manufacturer-specific relay styles and supported by a true database management system, it is common to see CAPE network models of 2,000 to 10,000 buses and protection system models of 5,000 to 50,000 relays. Wide Area Coordination reviews have become a reality as one tool to improve overall power system reliability.
