Introducing the Generator Scorecard: A Leap in Power Plant Performance Analysis

by Sandy Jenkins

Understanding the performance of power system generators is critical to making sure the lights stay on. Diagnosing issues with power supply can be tricky, but it’s important to know when issues occur and how they can affect power system stability so that the reliability and resilience of the grid is maintained. To that end, Pacific Northwest National Laboratory (PNNL), in collaboration with Bonneville Power Administration (BPA) and funded by the Office of Electricity and Solar Energy Technologies Office, have created a tool to make generator performance analysis easier. The innovative software tool is called the Generator Scorecard, and it aims to streamline the power plant evaluation process, making it more efficient and less time-consuming.

How Is the Generator Scorecard More Efficient?

Conventionally, evaluating a power plant's ability to control frequency and voltage requires detailed manual comparison of measured responses versus simulated ones. This model-based method, while effective, is time-consuming and labor-intensive. Each generator is evaluated one at a time using a small set of manually selected grid disturbances. Given the increasing number of Inverter-Based Resources (IBRs), such as solar or wind, a more efficient solution was necessary. Enter the Generator Scorecard. 

The Generator Scorecard is designed to automatically analyze power plant performance using data from Phasor Measurement Units (PMUs). The synchrophasors produced by PMUs are ideal for this application because they are reported 60 times per second (approximately 100 times as fast as conventional measurements), which is critical for automatically identifying and analyzing grid disturbances of interest. Synchrophasors are also time stamped using a common clock, typically using GPS satellites, which allows generators from across a wide area to be analyzed simultaneously. The Department of Energy’s Office of Electricity has been supporting work on new technologies that utilize advanced synchronized measurement systems like PMUs through efforts like this one and through the North American SynchroPhasor Initiative (NASPI).  

Key Features of the Generator Scorecard

The Generator Scorecard simplifies the power plant evaluation process by automating initial performance reviews and providing clear insights through a user-friendly interface. The tool uses three primary analytics:

• Frequency Response Measure (FRM): This analysis evaluates how well a power plant adjusts its active power output in response to changes in grid frequency.
• Voltage Response Measure (VRM): This quantifies a power plant's ability to adjust its reactive power output to maintain voltage levels.
• Voltage Schedule Tracking: This monitors how well a plant adheres to its prescribed voltage schedule, which varies depending on system load and time of day.

By processing PMU data, the Generator Scorecard provides feedback on power plant performance, easily identifying plants that excel or underperform in meeting frequency and voltage requirements. The tool features an intuitive Graphical User Interface (GUI) that makes it easy to navigate through extensive data. Power plants can be ranked from best to worst, allowing engineers to prioritize their focus. Both live and archived PMU data can be analyzed, providing flexibility in the types of analyses that can be performed.