IREMA is dealing with more than 150 power plants in the wholesale electricity market. During the power system restructuring process, many power plants have been privatized and some new privately owned power plants have been commissioned.

The ownership of the sellers (power plants) are depicted below.

Overview of the Day-Ahead Market

IREMA has a pool market acting a Day-ahead Market (DAM). The DAM is a forward market in which hourly clearing prices are calculated for each hour of the next operating day based on the generation bids, power system and generation unit constraints. In this structure, the market operation is implemented competitively based on a single- sided auction. In this regard, the market operator procures the energy on behalf of the buyers. The ISO aggregates the generation bids and clears the auction based on the sellers' bids and the system requirements, such as the load level, the reserve margin and etc. In this structure, the competition is established between sellers.

IREMA uses a pay-as-bid mechanism for the DAM clearance. Power system constraints, transmission system topology, fuel data, and the sellers' bids demonstrate the prices in the DAM through an optimization problem (security constrained unknit commitment-SCUC). The SCUC software determines the auction winners, minimizes the energy cost, meets the constraints and results an hourly dispatching schedule for each hour of the next operating day. The resulting Day-ahead hourly schedule represents binding financial commitments to the market participants.

Bidding & Operations Time Line

The day-ahead scheduling/bidding timeline for IREMA consists of the following time frames:

10:00 — Day-ahead Market bidding period closes.

All bids and availability declaring must be submitted to market between 9:00 o'clock, three days prior to the operating day until 10:00 on the day before the operating day.

14:00 — Day-ahead Market declared capacity modifications closes.

Participants can make restrictions on the power plant by modification of the declared power before 14:00 on the day before the operating day. At 14:00, the market operator begins to run the DAM clearing software (SCUC) to determine the hourly commitment schedules and the prices for the DAM. In this regard, the input information including the bilateral contracts, energy exchange trades, load forecasting, maintenance schedule, must run units list, and hydropower units schedule are loaded in the DAM clearing software. The day-ahead clearing results in the resource commitment profile that satisfies the fixed demand, while minimizing the total production cost (subject to a suite of constraints.

20:00 — Day-ahead Results posting.

Market operator up-loads the day-ahead hourly schedules in the Electricity Market Information System (EMIS). It also makes these results available in downloadable files, via the Iran Grid Management Company (IGMC) web-site.

(D-1 refers to the day before the delivery of the power)