Single intraday coupling (SIDC)
Single intraday coupling (SIDC) is an implicit cross-zonal capacity allocation mechanism which collects orders for each bidding zone from wholesale market participants and matches them continuously into contracts to deliver electricity while respecting cross-zonal capacity and allocation constraints, and is available in the intraday market timeframe once the day-ahead market allocation process has taken place.
According to Article 2(27) of the Regulation establishing a Guideline on Capacity Allocation and Congestion Management - the CACM Regulation (Regulation on market coupling) 'single intraday coupling' means the 'continuous process where collected orders are matched and cross-zonal capacity is allocated simultaneously for different bidding zones in the intraday market'.
Single intraday coupling enables continuous cross-border trading across Europe, i.e. it allows for orders entered by market participants for continuous matching in one bidding zone to be matched by orders analogously submitted by market participants in any other bidding zone within the project’s scope as far as transmission capacity is available.
The implementation of a single intraday coupling with implicit continuous cross-zonal capacity allocation, as laid down in the CACM Regulation, is expected to increase liquidity, because participants will have access to a larger portfolio of bids and offers to meet their balancing needs. Annual Report of the ACER and CEER on the Results of Monitoring the Internal Electricity and Gas Markets in 2016 (Electricity Wholesale Markets Volume) published in October 2017 mentioned (p. 49) that cross-zonal capacity was used more efficiently in 2016 in the intraday timeframe on borders where the capacity was allocated by using implicit allocation methods (61% of efficiency) as opposed to explicit or other allocation methods (40%). Nevertheless, the said Report of October 2017 assessed that the level of utilisation of cross-zonal capacity in the intraday timeframe remained low in 2016. According to Article 8(1) of the CACM Regulation all TSOs in EU Member States electrically connected to another Member State must participate in the single intraday and day-ahead coupling.
The SIDC solution is based on a common IT system with one Shared Order Book (SOB), a Capacity Management Module (CMM) and a Shipping Module (SM). Functionalities of the CMM and SOB modules are explained in the NEMO Committee document “Continues Trading Matching Algorithm” of February 2020.
The CMM provides the functionality for managing and allocating available transmission capacity between all areas in the underlying power transmission network. When cross-border trades are concluded, the required cross-border capacity is implicitly allocated in the CMM. Explicit market participants can directly access the CMM to transmit explicit capacity requests.
The SOB module contains the basic functionality for continuous trading, like order entry, order management and order matching. Tradable electricity contracts are automatically generated in the SOB module and made available for trading based on a predefined trading schedule. The XBID solution enables multiple power exchanges to connect to the central SOB module. Traders cannot connect to the SOB directly, instead, they connect to one or more trading solutions of power exchanges (NEMOs). Orders on contracts tradable in XBID, which are entered into a trading solution of a power exchange, are transmitted to the SOB, where they can be matched against each other. SOB always performs these matches regardless whether the orders were entered in the same bidding zone or in different bidding zones and regardless of the power exchange that transmitted the orders – provided that a match is possible.
The SOB module maintains a consolidated order book across all participating bidding zones and NEMOs, based on available transmission capacity between bidding zones.
SIDC algorithm's ownership
It is noteworthy, ACER Recommendation of 20 December 2021 on reasoned amendments to the Capacity Allocation and Congestion Management Regulation (Annex 1a, draft Recital 25) proposed changes to a wide range of topics, including market coupling governance and operations. In particular, ACER recommended that Transmission System Operators (TSOs) and Nominated Electricity Market Operators (NEMOs) should, to increase the transparency of price formation, regularly publish the fundamental data on the use of electricity infrastructure and prices, including also algorithms used to calculate single day-ahead and intraday coupling results.
According to the ACER:
- the source code of these algorithm needs to be considered as being a good of public interest that should be available to all interested public;
- to achieve this, the the Market Coupling Operator (MCO) should obtain ownership of these algorithms with procurement from either existing owners or new providers, while avoiding any double compensation of possible historical costs already paid by network users for these algorithms.
SIDC organisational set-up
ENTSO-E Market Report 2019 of August 2019 noted (p. 5, 19, 21) that the project since go-live in June 2018 included:
- 26 countries,
- 31 TSOs,
- 15 NEMOs,
- more than 15 million executed trades, in total.
The aforementioned TSOs and NEMOs cooperate under the agreement governing the SIDC - the intraday operational agreement (IDOA). This agreement rules the cooperation of TSOs and NEMOs regarding the establishment, amendment, and operation of the coupling. It was agreed by all TSOs and NEMOs of the EU Member States plus Norway but excluding Slovakian parties.
The signatory parties of the IDOA are as follows:
Affärsverket Svenska Kraftnät, Amprion GmbH, Augst - sprieguma tīkls, Austrian Power Grid AG, Britned Development Limited, National Power Grid Company Transe- lectrica S.A., ČEPS a.s., CREOS Luxembourg S.A, Croatian Transmission System Operator Ltd., Electricity System Operator EAD, Elering AS, ELES Ltd., Electricity Transmission System Operator, Elia System Operator SA/NV, Energinet Elsystemansvar A/S, EirGrid plc, Fingrid OYJ, Independent Power Transmission Operator S.A, Litgrid AB, Mavir Ltd., National Grid Interconnectors Limited, Polskie Sieci Elektroenergetyczne S.A., Red Eléctrica de España S.A.U., REN - Rede Eléctrica Nacional, S.A., RTE Réseau de Transport d’Electricité, SONI Limited, Statnett SF, TenneT TSO B.V, TenneT TSO GmbH, Terna - Rete Electrica Nazionale S.p.A, Transnet BW GmbH, and 50Hertz Transmission GmbH;
BSP Energy Exchange LLC, Croatian Power Exchange Ltd., EirGrid plc, EPEX SPOT SE, European Market Coupling Operator AS, EXAA Abwicklungsstelle für Energieprodukte AG, Gestore dei Mercati Energetici S.p.A, Hellenic Energy Exchange S.A., HUPX Hungarian Power Exchange Company Limited by Shares, Independent Bulgarian Energy Exchange, OMI, POLO ESPAÑOL S.A., Operator of Electricity Market S.A., Operatorul Pieţei de Energie Electrică şi de Gaze Naturale S.A., OTE a.s., SONI Limited, and Towarowa Giełda Energii S.A.
The SIDC contractual framework is complemented by:
- the TSOs only agreement: the TSOs cooperation agreement for intraday coupling (TCID),
- a NEMO only agreement: the all-NEMOs intraday operational agreement (ANIDOA), and
- local arrangements, which specify or complete the general principles described in the IDOA.
In the joint TSO-NEMO organisation, decisions are taken by all IDOA signatory parties at the intraday steering committee. The key service provider is Deutsche Börse AG. The complementary regional intraday auctions, as referred to in Article 63 of the CACM regulation and the post-coupling processes, including rights and obligations of CCPs, are outside the scope of the IDOA and are outlined in local arrangements.
The idea that the delivery of the European intraday market coupling should be based on the cross-border intraday (XBID) commercial solution was proposed by NEMOs to National Regulatory Authorities in the ‘All NEMO proposal for the Market Coupling Operator (MCO) Plan’ of 13 April 2017. The intention of this multi-NEMO solution was to bring together the whole European intraday continuous market. The implementation of the SIDC through the XBID project was successfully launched in its first phase on 12 June 2018. The implementation of the XBID project was considered as the formal start of the SIDC (the ACER’s stance in the Decision No 04/2018 of 24 April 2018 on all Transmission System Operators’ Proposal for Intraday Cross-Zonal Gate Opening and Intraday Cross-Zonal Gate Closure Times, p. 9), although it was not implemented on all bidding zone borders.
As from 12 June 2018 XBID has been delivering continuous trading of electricity across the following countries: Austria, Belgium, Denmark, Estonia, Finland, France, Germany, Latvia, Lithuania, Norway, The Netherlands, Portugal, Spain and Sweden. The SIDC second wave started as from 19 November 2019 (with first deliveries on 20 November 2019) and the following countries: Bulgaria, Croatia, Czech Republic, Hungary, Poland, Romania and Slovenia joined the continuous trading of electricity across the EU. Hence, as from 19 November 2019 a pan-European trading was in place across 21 countries coupled through the SIDC.
A 3rd wave successful go-live was 5 October 2021 integrating Italy, which joined SIDC coupling on 21st September 2021. This way intraday trading has been extended across 23 countries coupled through SIDC.
The go-live on 21st September 2021 integrated the Northern Italian borders (IT-FR, IT-AT and IT-SI) as well as the Italian internal bidding zones borders into the already coupled intraday region.
Cross-border capacity on Italian borders is allocated, starting from 21st September 2021, both in the continuous trading through SIDC and in three intraday regional auctions (CRIDAs) involving IT-SI and IT-GR borders.
Interestingly, the intraday solution supports (and it is in line with the EU target model for an integrated intraday market) both:
- implicit continuous trading, as well as
- the explicit allocation on the French/German and Croatian/Slovenian borders (as requested by the respective National Regulatory Authorities).
Maximum and minimum clearing price limits for single intraday coupling
For the purposes of setting the clearing price limits for single intraday coupling the following definitions are used:
1. ‘harmonised maximum clearing price for SIDC’ means the maximum clearing price value, which is applied in all bidding zones which participate in SIDC; and
2. ‘harmonised minimum clearing price for SIDC’ means the minimum clearing price value, which is applied in all bidding zones which participate in SIDC.
The harmonised maximum clearing price limit for single intra day coupling was proposed by NEMOs to be set at + 9999 Euro/MWh, while the harmonised minimum clearing price limit for single intra day coupling was proposed to be set at - 9999 Euro/MWh (All NEMO’s proposal for harmonised maximum and minimum clearing prices for Single Intra Day Coupling in accordance with Article 54(2) of Commission Regulation (EU) 2015/1222 of July 2015 establishing a guideline on capacity allocation and congestion management, 14 February 2017). The above propositions have been approved by the ACER (Article 3 of the Annex I to the Decision No 05/2017 of 14 November 2017).
Moreover, in Article 4 of the said Annex ACER stipulated the criteria and process for establishing and amending maximum price for SIDC (see the box). In particular, the harmonised maximum clearing price for SIDC is to be amended in the event that harmonised maximum clearing price for single day-ahead coupling (SDAC) is increased above the harmonised maximum clearing price for SIDC. In such a case, the harmonised maximum clearing price for SIDC will also increase to be equal to the harmonised maximum clearing price for SDAC. Any such change must be implemented and applied at the same time that the harmonised maximum clearing price for SDAC is applied.
The NEMOs are required to transparently announce and publish the amended harmonised maximum clearing price for SIDC at least four weeks before its implementation and application in SIDC. In order to avoid strategic bidding between different market time horizons and consider decreasing flexibility of generation units due to technical restrictions, the clearing price limit for the intraday day market should always be higher than day-ahead (ENTSO—E‘s view quoted in the Annex II to the said ACER’s Decision 05/2017 -Evaluation of responses to the Public consultation on the proposal on harmonised maximum and minimum clearing prices).
On 24 May 2022 All NEMO Committee started public consultation on harmonized maximum and minimum clearing prices for for single intraday coupling and on 29 August 2022 the result paper was published. On 10 January 2023 the ACER adopted Decision No 02/2023 on the Nominated Electricity Market Operators proposal for the harmonised maximum and minimum clearing price methodology for the single intraday coupling.
Decision of the Agency for the Cooperation of Energy Regulators No 05/2017 of 14 November 2017 on the Nominated Electricity Market Operators proposal for harmonised maximum and minimum clearing prices for single intraday coupling
Annex I - Harmonised maximum and minimum clearing prices for single intraday coupling in accordance with Article 54(1) of Commission Regulation (EU) 2015/1222 of 24 July 2015 establishing a guideline on capacity allocation and congestion management (CACM Regulation)
Harmonised maximum and minimum clearing prices for SIDC
1. The harmonised maximum clearing price for SIDC shall be +9999 EUR/MWh.
2. The harmonised minimum clearing price for SIDC shall be -9999 EUR/MWh.
Criteria and process for establishing and amending maximum price for SIDC
1. The harmonised maximum clearing price for SIDC in accordance with Article 3(1) shall be amended in the event that harmonised maximum clearing price for SDAC is increased above the harmonised maximum clearing price for SIDC pursuant to Article 4 of the Harmonised maximum and minimum clearing prices for single day-ahead coupling in accordance with Article 41(1) of Commission Regulation (EU) 2015/1222 of 24 July 2015 establishing a guideline on capacity allocation and congestion management. In such a case, the harmonised maximum clearing price for SIDC shall also increase to be equal to the harmonised maximum clearing price for SDAC. Any such change shall be implemented and applied at the same time that the harmonised maximum clearing price for SDAC is applied.
2. The NEMOs shall transparently announce and publish the amended harmonised maximum clearing price for SIDC at least four weeks before its implementation and application in SIDC.
3. The NEMOs shall, at least every two years, reassess the HMMCP, share this assessment with all market participants and consult it in relevant stakeholder forums organised in accordance with Article 11 of the CACM Regulation. A reassessment may also follow any amendment in accordance with paragraph (Error! Reference source not found.), if the NEMOs deem it appropriate.
Single Intraday Coupling Products
According to All NEMOs’ proposal of 14 February 2017 for products that can be taken into account by NEMOs in intraday coupling process in accordance with Article 53 of CACM Regulation the continuous trading matching algorithm is required to support the following products:
a) Hourly: the product supports trading in 24 power contracts, one for each hour of the day. The system automatically generates these contracts and makes them available for trading one day before the delivery day at a specified time.
b) Half-hourly: the product supports trading in 48 power contracts, one for each half-hour of the day. The system automatically generates these contracts and makes them available for trading one day before the delivery day at a specified time.
c) Quarter-hourly: the product supports trading in 96 power contracts, one for each 15-min slot of the day. The system automatically generates these contracts and makes them available for trading one day before the delivery day at a specified time.
d) Predefined blocks, being single-type aggregations of hourly, half-hourly or quarter-hourly contracts. Predefined blocks combine several contiguous contracts of a single type with a minimum of two, which must be executed together.
e) User defined blocks: other than predefined blocks, these are on-demand combinations of contracts defined by the user. The delivery period of user-defined blocks (user-defined market contracts) must always be coverable by multiple regular market contracts of the product and with consecutive delivery times.
On 29 April 2022 the NEMO Committee published the result paper of the public consultation on SIDC Products.
Intraday Cross-Zonal Gate Opening and Closure Times
The ACER Decision No 04/2018 of 24 April 2018 determined that the intraday cross-zonal market:
- shall open (Intraday Cross-Zonal Gate Opening Time (IDCZGOT)) at 15:00 market time day-ahead, and
- shall close (Intraday Cross-Zonal Gate Closure Time (IDCZGCT)) 60 minutes (30 minutes for Estonia-Finland border) before the start of the relevant market time unit.
Single intraday coupling may be opened to market operators and TSOs operating in Switzerland on the condition that the Swiss national law implements the main provisions of EU electricity market legislation and that there is an intergovernmental agreement on electricity cooperation between the EU and Switzerland (Annual Report of the ACER and CEER on the Results of Monitoring the Internal Electricity and Gas Markets in 2016 (Electricity Wholesale Markets Volume) published in October 2017, p. 43).
Legal framework for the single intraday market coupling
Detailed rules for the single intraday coupling are stipulated in Articles 51 - 68 and Recital 29 of the CACM Regulation - see box. Moreover, the policies and measures related to the roll-out of intraday market coupling should be described in the national climate and energy plans, the EU Member States are required to prepare under Article 3 of the Regulation of the European Parliament and of the Council on the Governance of the Energy Union.
Nevertheless, the ACER in its Monitoring report of 30 January 2019 on the implementation of the CACM Regulation and the FCA Regulation assessed (p. 5) that “[t]he design of the single intraday coupling, including the underlying capacity calculation, is not well defined in the CACM Regulation. The current development of different terms and conditions or methodologies in this area indicates that there is a significant risk that single intraday markets could be highly fragmented in terms of timeframes, design and geography. More clarity and harmonisation through the CACM Regulation would help mitigate this risk.”
Objectives of the continuous trading matching algorithm
1. From the intraday cross-zonal gate opening time until the intraday cross-zonal gate closure time, the continuous trading matching algorithm shall determine which orders to select for matching such that matching:
Results of the continuous trading matching algorithm
1. All NEMOs, as part of their MCO function, shall ensure that the continuous trading matching algorithm produces at least the following results:
1. No later than 18 months after the entry into force of this Regulation NEMOs shall submit a joint proposal concerning products that can be taken into account in the single intraday coupling. NEMOs shall ensure that all orders resulting from these products submitted to enable the MCO functions to be performed in accordance with Article 7 are expressed in euros and make reference to the market time and the market time unit.
Maximum and minimum prices
1. By 18 months after the entry into force of this Regulation, all NEMOs shall, in cooperation with the relevant TSOs, develop a proposal on harmonised maximum and minimum clearing prices to be applied in all bidding zones which participate in single intraday coupling. The proposal shall take into account an estimation of the value of lost load.
Pricing of intraday capacity
1. Once applied, the single methodology for pricing intraday cross-zonal capacity developed in accordance with Article 55(3) shall reflect market congestion and shall be based on actual orders.
Methodology for calculating scheduled exchanges resulting from single intraday coupling
1. By 16 months after the entry into force of this Regulation, the TSOs which intend to calculate scheduled exchanges resulting from single intraday coupling shall develop a proposal for a common methodology for this calculation.
Arrangements concerning more than one NEMO in one bidding zone and for interconnectors which are not operated by certified TSOs
1. TSOs in bidding zones where more than one NEMO is designated and/or offers trading services, or where interconnectors which are not operated by TSOs certified according to Article 3 of Regulation (EC) No 714/2009 exist, shall develop a proposal for cross-zonal capacity allocation and other necessary arrangements for such bidding zones in cooperation with concerned TSOs, NEMOs and operators of interconnectors who are not certified as TSOs to ensure that the relevant NEMOs and interconnectors provide the necessary data and financial coverage for such arrangements. These arrangements must allow additional TSOs and NEMOs to join these arrangements.
Provision of input data
1. Each coordinated capacity calculator shall ensure that cross-zonal capacity and allocation constraints are provided to the relevant NEMOs no later than 15 minutes before the intraday cross-zonal gate opening time.
Operation of single intraday coupling
1. By 16 months after the entry into force of this Regulation, all TSOs shall be responsible for proposing the intraday cross-zonal gate opening and intraday cross-zonal gate closure times. The proposal shall be subject to consultation in accordance with Article 12.
(a) maximises market participants' opportunities for adjusting their balances by trading in the intraday market time-frame as close as possible to real time; and
(b) provides TSOs and market participants with sufficient time for their scheduling and balancing processes in relation to network and operational security.
Delivery of results
1. All NEMOs performing MCO functions shall deliver the continuous trading matching algorithm results:
Calculation of scheduled exchanges resulting from single intraday coupling
1. Each scheduled exchange calculator shall calculate scheduled exchanges between bidding zones for each market time unit in accordance with the methodology established in accordance with Article 56.
Publication of market information
1. As soon as the orders are matched, each NEMO shall publish for relevant market participants at least the status of execution of orders and prices per trade produced by the continuous trading matching algorithm in accordance with Article 52(1)(a).
Complementary regional auctions
1. By 18 months after the entry into force of this Regulation, the relevant NEMOs and TSOs on bidding zone borders may jointly submit a common proposal for the design and implementation of complementary regional intraday auctions. The proposal shall be subject to consultation in accordance with Article 12.
3. For complementary regional intraday auctions, the methodology for pricing intraday cross-zonal capacity may differ from the methodology established in accordance with Article 55(3) but it shall nevertheless meet the principles provided for in Article 55(1).
4. The competent regulatory authorities may approve the proposal for complementary regional intraday auctions if the following conditions are met:
Provisions relating to explicit allocation
1. Where jointly requested by the regulatory authorities of the Member States of each of the bidding zone borders concerned, the TSOs concerned shall also provide explicit allocation, in addition to implicit allocation, that is to say, capacity allocation separate from the electricity trade, via the capacity management module on bidding zone borders.
Removal of explicit allocation
1. The NEMOs concerned shall cooperate closely with the TSOs concerned and shall consult market participants in accordance with Article 12 in order to translate the needs of market participants linked to explicit capacity allocation rights into non-standard intraday products.
Provisions relating to intraday arrangements
1. Market participants shall ensure the completion of nomination, clearing and settlement related to explicit allocation of cross-zonal capacity.
Explicit requests for capacity
A request for explicit cross-zonal capacity may be submitted by a market participant only for an interconnection where the explicit allocation is applicable. For each request for explicit capacity the market participant shall submit the volume and the price to the capacity management module. The price and volume of explicit allocated capacity shall be made publicly available by the relevant TSOs.
Clearing and settlement
1. The central counter parties shall ensure clearing and settlement of all matched orders in a timely manner. The central counter parties shall act as the counter party to market participants for all their trades with regard to the financial rights and obligations arising from these trades.
Fundamentals of intraday cross-zonal capacity pricing
Basic elements for intraday cross-zonal capacity pricing, according to the ACER Decision No 01/2019 of 24 January 2019 on the methodology for pricing cross-border capacity in the intraday electricity markets, are as follows:
1. the pricing mechanism for cross-zonal capacity in the intraday timeframe is to be based on intraday auctions, as part of the SIDC, i.e. auction SIDC, and to complement the continuous SIDC;
2. the pricing of intraday cross-zonal capacity will be established by allocating the available cross-zonal capacity for the respective market time unit by intraday auctions using the marginal pricing principle;
3. the intraday auctions are to be organised as implicit auctions where collected orders are matched and cross-zonal capacity is allocated simultaneously for different bidding zones;
4. intraday auctions take into account all valid orders submitted for the respective auctions and determine a clearing price for the relevant bidding zones based on matched orders;
5. cross-zonal capacity is not allowed to be allocated to an intraday auction and continuous trading at the same time (for this purpose, the cross-zonal trade and cross-zonal capacity allocation within the continuous SIDC are temporarily suspended and during this suspension all the available cross-zonal capacity is allocated through the intraday auction), however, the intraday auction don’t have an impact on the continuous SIDC within bidding zones, for at least those bidding zones where more than one NEMO operates;
6. in case the TSOs are not able to provide the intraday cross-zonal capacity to an intraday auction, such capacity, when it becomes available, is allocated through the continuous SIDC;
7. in case an intraday auction is not able to allocate intraday cross-zonal capacity, such capacity is subsequently offered and allocated through the continuous SIDC;
8. the intraday auctions must allow at least 30 minutes of cross-zonal continuous trading for any given market time unit after the publication of the auction results;
8. the intraday auctions are to be implemented on all the bidding zone borders eligible to participate in the SIDC (this obligation applies to bidding zone borders regardless of whether they are already participating in the continuous SIDC or not).
The said ACER’s Decision established the following timing of intraaday auctions:
- one intraday auction is to be held on the day D-1 for all MTUs of the delivery day D, i.e. from the first auction MTU starting at 00:00 until the end of the delivery day D, with a deadline for bid submission at 15:00 market time D-1,
- one intraday auction is to be held on the day D-1 for all MTUs of the delivery day D, i.e. from the first auction MTU starting at 00:00 until the end of the delivery day D, with a deadline for bid submission at 22:00 market time D-1,
- one intraday auction is to be held on the delivery day D for all remaining MTUs of the delivery day D, i.e. from the first auction MTU starting at 12:00 until the end of the delivery day D, with a deadline for bid submission at 10:00 market time D.
REMIT reporting for order matching via the SIDC mini-auction