Reliability unit commitment in the new ERCOT nodal electricity market

Comparison of advanced power system operations models for large-scale renewable integration

“…Centrally organized wholesale electricity markets, such as the ISO/RTO markets in the United States, perform their short-term operations scheduling based on the two-settlement system [1] comprising a day-ahead forward market (DAM) with hourly resolution and a real-time market (RTM) with 5-min dispatch period, complemented with a forward or intraday reliability unit commitment (RUC) [2,3]. DAM is a UC market model that clears energy and reserve quantities based on supply offers and demand bids with hourly resolution.…”

“…RUC is also a unit commitment model, which recommits units based on ISO load and wind power forecasts instead of participant orders. In some markets RUC is not allowed to de-commit units but can only commit additional units [2], while in others RUC may also de-commit resources for congestion relief [3].…”

“…• Frequently revised RUC, with hourly granularity, to adapt the commitment decisions based on most recent information on changing system conditions [3,4]. • Intraday rolling unit commitment with sub-hourly time resolution and scheduling horizons up to several hours [15] in order to recommit fast-start units.…”

“…The other two models are based on two distinct current US operator practices. The second model (b) is an operations model based on the concept of the current ERCOT practice [3,4,17], which from now on will be called "two-level model" and the third model (c) is an operations model based on the concept of the current CAISO practice [15,24], which from now on will be called "three-level model". Similar two-or three-level operations models have been introduced to several other North American RTO/ISO-type markets, such as MISO [25,26], PJM [19], etc.…”

Large-scale decentralized unit commitment

“…an ISO) determines prices to induce desirable system-level behavior. As a decomposition of the UC, our work is more analogous to, for example, the reliability UC (RUC) described in [19] conducted following the dayahead market clearing process. The analyses of [5,[7][8][9][10][11][12][13] study the revenue adequacy of market participants and describe pricing approaches to overcome inefficiencies.…”