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Quality Assurance in Power System Protection and Relay Settings

Authored by: Gregory Bee, Settings Engineer at Power Grid Engineering

The key to power system safety and reliability is properly designed and coordinated relay protection settings. Our relay settings engineers are experienced in finding the optimum balance between security and reliability, while also adhering to customer protection relay logic requirements and NERC standards. Along with designing protective relays, we also use a thorough and unique peer check and quality assurance process to ensure safety and grid reliability.

Power Grid Engineering helps our clients with transmission, substation, generation, and distribution line protection. Relay settings engineers use a combination of data to create the settings that our clients rely on for safety, stability, and reliability. Our engineers begin with client provided documents that depict equipment specifications. This includes company standards, project documents, drawings, and models. We review the drawings and materials provided to become familiar with the project and ensure the project aligns with expected protection practices. This includes high-level checks of the protection scheme to low-level cross-checks of the relay input and outputs. Next, our relay settings engineers create settings for these protection schemes using the utility’s standards and documents, supplementing with knowledge on protection systems. Then the settings engineer performs calculations and coordination studies using short circuit modeling software. During this time, the engineer completes the documentation while adhering to system protection best practices. Once settings are calculated, they are populated into relay settings files and the relay engineer will review his or her own work for errors.

After this initial review, the project is handed off to another experienced engineer to begin the QA process. They review the project, from project scope through the final settings, checking for general protection philosophy, documentation accuracy, and more specific company standards. Relay settings errors can range from specific engineering miscalculations to simple data entry or transcription missteps. Any of these errors can result in an incorrectly set relay. Our QA process adds an additional line of defense against errors to help ensure that the customer is getting a product they can trust. Our QA process also allows for another perspective on the project to understand if there is a better method to protect a piece of equipment. We utilize the QA process for our internal relay setting development projects as well as services offered for external projects developed by our clients.

During both the setting development and QA process, PGE internally documents notes, standards, preferences, and lessons-learned from our clients to build a unique overview of a company’s specific needs. This is part of PGE’s dedication to improving the relationship with our clients and the product we provide. These internal documents are reviewed and updated on a continuous basis. This internal documentation process ensures our team of engineers are all working from the same standard to provide a consistent product, while also improving quality and efficiency.

Protective relay settings are the final barrier of safety for electrical systems. But in order to take full benefit of these protective settings, you need to know they are done correctly. Our QA process sets us above the rest, allowing our clients to rest assured in the accuracy, quality, and reliability of their power systems protections.