Anay Waghale, Pacific Northwest National Laboratory: Hello, everyone. My name is Anay Waghale, and this presentation focuses on LED streetlights and their susceptibility to power quality issues.

US electric grid is changing rapidly, from a centralized grid to a distributed one. This is mainly due to high penetration of renewable resources. This is also changing our energy consumption patterns and resulting in increased ramps during peak hours, causing operational resiliency and reliability issues on the grid.

Physical infrastructure adds to these issues because A, it was not designed for the newer distributed grid and B, it's aging. Most of the transmission and distribution lines were constructed in the 1950s and '60s with a 50-year life expectancy, which they have either reached or exceeded.

Now as the grid is changing, our loads are changing as well. Cities and electric utilities are adopting LED technology predominantly because of their longer life, lower energy consumption, and improved lighting quality.

Most of these streetlights are directly powered from their distribution network, meaning they're exposed to all power line disturbances. Even though these LED streetlights use a driver which can accept a wide range of input voltages, performance outside of this range varies and is difficult to predict. This unknown performance, along with increasing deployment of LED streetlights, makes it important to identify and address any potential risk or shortcomings found in early market products.

So this research explores the performance of commercially available LED streetlights, when they are exposed to long duration under-voltage conditions.

To answer these research questions, 12 LED streetlights were exposed to 10 two-minute-long under-voltage conditions, from 120 to 60 volts. The test setup used for this research consisted of a programmable AC source to change the input voltage and an ANSI C12.1-compliant meter to measure power, current and power factor of the streetlights.

When these 12 LED streetlights were exposed to under-voltage conditions their performance varied from each other and were broadly classified in three groups based on their behavior, namely constant power, declining power or reduction in light output, and intermittent interruptions. From 120 to 90 volts, almost all streetlights maintained a constant power drop, showing immunity to voltage change.

However, as the voltage dropped below 90 volts, power draw for some streetlights started to drop. And some started exhibiting intermittent interruptions, like strobing or turning off. Number of streetlights exhibiting interruptions increased as the voltage dropped further. And at 60 volts, which was the lowest voltage condition that was tested, six out of 12 streetlights exhibited interruptions, another four exhibited a decline in power draw, and only two of the 12 maintained a constant power draw, showing complete immunity to under-voltage conditions.

This shows that LED streetlights are susceptible to under-voltages, and the performance varies across products. This suggests that the performance depends on driver, as well as luminaire design. Under-voltage conditions tested in this study are only sustained for two minutes, and duration longer than this can lead to performance issues, like overheating, equipment failure, et cetera.

Also, under-voltages are just one type of power quality issue, and performance radiation during other types of power quality issues can be completely different. Hence, it is hoped that the results and lessons learned from this study will motivate more research in this area, to find solutions to mitigate these resiliency issues and result in more reliable products.

I hope you liked this presentation. If you have any questions, email us and we will be more than happy to answer them. Thank you so much for your time and have a great rest of your day.