The complex issue regarding congestion revenue allocation in CAISO’s Extended Day-Ahead Market (EDAM) continues to raise questions and cause some confusion for market participants, with a market expert reviewing possible solutions at an April 8 Western Energy Markets Governing Body meeting.
The issue is whether certain congestion revenues should be allocated to the balancing area in which the congestion revenue accrued, or to the neighboring EDAM balancing authority area where the transmission constraint is located, specifically in cases in which parallel — or loop — flows occur.
In March, CAISO launched an “expedited” initiative to address stakeholder concerns. The ISO plans to release a full proposal on the issue in the coming week. (See Fast-paced Effort will Address EDAM Congestion Revenue Issue.)
Under current EDAM market rules, Open Access Transmission Tariff (OATT) customers in one BAA will end up paying costs for congestion for parallel flows caused by binding transmission constraints in neighboring BAAs, CAISO market expert Susan Pope noted during the meeting. This requirement could make a system and its transmission users carry the costs of unexpected congestion.
OATT point-to-point (PTP) service is awarded without fully accounting for parallel flows, while management of infeasible OATT schedules today requires approaches such as curtailment of non-firm service and out-of-merit redispatch by the impacted BAA to manage congestion, Pope said.
“These congestion charges only occur when there are flows over binding constraints and the amount of the charges reflect the cost of managing the congestion on those constraints,” Pope said. “So, if the cost of managing the congestion isn’t that big, the charges aren’t going to be that big.”
There is strong justification for charging OATT customers for EDAM congestion costs, because the charges are tied to the marginal cost of redispatch to manage congestion on the binding constraints impacted by the OATT schedule, Pope added.
At an April 2 meeting on the subject, Anna McKenna, CAISO vice president of market design and analysis, also disputed the contention that EDAM’s existing congestion revenue framework is inherently flawed. (See EDAM Congestion Debate Builds Even as CAISO Moves to Address Issue.)
However, Pope said the ISO could address stakeholder concerns by redesigning EDAM to include an avenue for OATT customers to more fully hedge or otherwise manage EDAM congestion cost charges.
More specifically, EDAM could adopt use of congestion revenue rights (CRRs), which would provide OATT customers with a hedge against EDAM congestion charges. But the market design does not include CRRs, and CAISO would need to address core issues prior to including them, Pope said. Introducing CRRs would require new rules to establish transmission capability for CRRs while also enabling cost recovery for transmission service providers, she said.
In many RTOs and ISOs, such as NYISO, PJM, MISO and CAISO, OATT transmission reservations were infeasible when modeled, according to Pope’s presentation. Furthermore, RTOs with CRRs have required lengthy stakeholder processes to design the market rules for converting existing OATT service arrangements into CRR allocations, Pope said.
Despite these challenges, introducing CRRs for hedging EDAM congestion costs would “likely enable more efficient scheduling and decrease the cost of serving EDAM load,” Pope said. “But it will take time to design and implement CRRs when agreed upon by EDAM participants.”
In the meantime, a transitional approach is needed to address concerns about OATT transmission customers’ potential undue exposure to charges for parallel flow on binding constraints in other BAAs, Pope said.
One transitional solution is to enable PTP customers to “opt out” of EDAM settlements, which could allow them to avoid congestion charges under all grid conditions, such as by self-scheduling rights before or after EDAM without paying congestion charges, Pope said. But this approach could reduce efficiency and customer cost savings from EDAM and make it more difficult to maintain system reliability during stressed system conditions.
More Work Ahead
WEM Governing Body member John Prescott said the parallel flow congestion issue is “a very thorny problem.”
“But I appreciate the fact that everybody is rolling up their sleeves and, I hope, working in earnest to solve this problem,” Prescott said.
At the meeting, Alan Meck, principal market design analyst at Pacific Gas and Electric, asked if CAISO could break down the pros and cons of each possible solution to the matter.
“I think that I’m following this presentation, but it’s been kind of difficult,” Meck said. “It would be really helpful, I think, if you could add one additional slide synthesizing EDAM design pros and cons and where all of these different issues shake out.”
Pope reminded attendees that a good solution to the issue “is probably one that doesn’t make anybody happy.”
“If everybody’s complaining about something, that might be a good solution,” Pope said. “There’s a lot to gain by solving this problem. I just wanted to encourage everybody to sort of work together, be realistic and try to craft solutions.”
CAISO is on track to publish a full proposal on the topic on April 14, spokesperson Jayme Ackemann said. Whether the CAISO Board of Governors will vote on the proposal at its May meeting is still under consideration, she said.