Minutes Matter in the Energy Imbalance Market
An energy imbalance market (EIM) is a voluntary market that provides a sub-hourly economic dispatch of participating resources for balancing supply and demand every five minutes. One such market is the Western EIM, which the California Independent System Operator (CAISO) began operating on Nov. 1, 2014. CAISO claims the Western EIM enhances grid reliability and improves the integration of renewable energy, which leads to “a cleaner, greener grid.”
The Western EIM has grown from meager beginnings—initially optimizing only the CAISO and PacifiCorp balancing authority areas—to a footprint that now includes parts of eight states and a portion of British Columbia, Canada. It has 11 active participants, with Salt River Project and Seattle City Light entering the fold this year, and 10 more participants are slated to join by the end of 2022.
By all accounts, the market has been a huge success. From its launch through April 2020, CAISO reports the Western EIM has generated $919.69 million in gross benefits for its participants. However, participating in the market keeps power companies on their toes. The sub-hourly five-minute increment dispatch market means generating units need to hit their output targets consistently. If they don’t, the company must pay.
Challenges Hitting Targets
Arizona Public Service (APS) began participating in the Western EIM in October 2016. As a result, the company has benefited to the tune of more than $150 million, according to CAISO’s records. But until APS implemented a unit monitoring tool, managing power generation wasn’t always easy.
“Prior to the unit monitoring tool, compliance was managed off of our automatic dispatch, or dispatch screen, which basically consisted of a series of tables and a single graph,” Andre Norwood, senior engineer with APS, told POWER. “The problem we had with that was the operators found it a little bit cumbersome and difficult to do.”
Therefore, deviations were only being identified by the power traders or the balancing authority. They would in turn notify the generating units that dispatch instructions weren’t being followed consistently, which was a problem. Furthermore, APS wasn’t able to identify or correlate trends to different modes of operation, because it didn’t have the necessary data available to accomplish that task.
“From a marketing standpoint, our drive is to have the unit work within the parameters that we provide to the energy imbalance market and to our balancing area, and anytime the unit can’t achieve the targeted dispatch, then something out there is sub-optimal,” said Tim Rusert, director of Fuel Procurement and Resource Operations Support with APS. That can mean another unit is forced to start unexpectedly, which is costly and inefficient.
A Tool to Optimize Operation
That’s where the unit monitoring tool came in. KBC (a Yokogawa company) was implementing OSIsoft’s PI System for APS, so it was natural for the companies to work together on the tool.
