Voltus filed a complaint with FERC against MISO on Dec. 11 asking it to require the RTO to allow the replacement of customers who sign up as load-modifying resources (LMRs) in the Planning Reserve Auctions (EL25-37). 

Aggregators like Voltus can sign up customers to provide demand response and clear that capability in the capacity market, but then those customers could go out of business or otherwise be unable to supply the capacity when needed, the company told the commission. When that happens, aggregators need to be able to replace the resource with another customer facility to provide the contracted DR. 

“Generators that become unavailable can be replaced, and there is no reason to treat LMRs differently,” Voltus said. 

Voltus argued that MISO’s tariff as written does not treat LMRs differently, and it expressly permits such replacements. MISO used to interpret it that way until a tariff change in 2022. 

“An apparently unintended consequence of that change is that MISO believes the tariff no longer authorizes MISO to permit an aggregator to replace an LMR that cleared the capacity market but is no longer available, even though a similarly situated generator may be replaced,” Voltus said. “A generator may even use a demand response resource as a replacement resource, but in the circumstance where a demand response resource becomes unavailable, MISO does not allow for its replacement.” 

The 2022 change requires that generators be replaced after a prolonged outage, but Voltus said its “plain language” does not implicate replacing customers supplying DR. 

“There is not any discussion of such disparate treatment sufficient to provide notice to market participants,” Voltus said. “In short, if the 2022 tariff amendment had the effect attributed by MISO, it appears to have been inadvertent. Because the plain language of the amendment leaves plenty of room for an interpretation that no such change occurred, the commission should confirm that no such change did occur.” 

If FERC finds MISO’s interpretation to be correct, then the commission should order a change in wording to reinstate LMRs’ ability to be replaced because the current practice wrongfully omits useful resources from the reliability equation, the company argued. 

“MISO deems LMRs useful enough to replace generation,” Voltus said. “There can be no good reason why such a useful resource should not be afforded the right to be replaced itself.” 

PRAs are run in April for delivery years that start June 1, and LMRs can bid into the auctions as zonal resource credits (ZRCs). 

The new rule was meant to require that generators that are offline for more than 31 days be replaced, which MISO felt was necessary as the PRA shifted to a seasonal construct. After the amendment went into effect, MISO cited a sentence from it as the basis for its interpretation that LMRs could not be replaced: “A planning resource may not transfer its performance requirements by replacing the cleared ZRCs with uncleared ZRCs other than in the case of suspension, retirement, catastrophic generator outage, or full or partial generator planned outages that may exceed 31 days in the season.” 

While the reasoning for replacing resources is focused on generators, Voltus said the “plain meaning” of the terms “retirement” and “suspension” should be applied to the customer sites backing LMRs. DR is one of the last resources MISO operators use to prevent load shedding, so the more of it available means they can better respond to emergency conditions, it argued.