Dispatch Balancing and Constraints

Dispatch

Dispatch means the sending of instructions by the Control Centres in EirGrid and SONI to power generators, demand side units, interconnectors or pumped storage plant about their times, fuel, manner of operation or output.

Dispatch Balancing Costs

Dispatch Balancing Costs refers to a number of payments related to how generators are instructed. They include Constraint Payments, Uninstructed Imbalance Payments and Generator Testing Charges. The Transmission System Operators (TSOs) are responsible for forecasting and managing Dispatch Balancing Costs.

The costs are recovered through the Imperfections Charge, which is levied on suppliers in the Single Electricity Market (SEM) by SEMO. The Imperfections Charge also recovers the net cost of energy imbalances and Make Whole Payments.

Constraint Payments

The Transmission Operators work to ensure supply of power and system security to customers across the system in real time. That means they may have to dispatch or call in some power generators differently from the schedule in the wholesale power market. This is because of the technical realities of operating a dynamic and fast-changing power system, such as preventing overloads or maintaining enough generation reserve. It may also arise because of generator testing.

Where power stations are run differently from the market schedule, it is termed “constraint”. Subject to the Trading and Settlement Code and Firm Access, Constraint payments keep generators financially neutral for the difference between the market schedule and what actually happened when generating units were dispatched.

Generators can be constrained ‘on’ or ‘up’, if the market schedule indicated they were to be run at lower levels than actually happened. Or they could be constrained ‘down’ or ‘off’ in they were to be run at a higher level than happened in reality. There is always an overall net cost to the system associated with constraints.

Market Modelling Assumptions

Because of mathematical limitations, approximations and assumptions, the market schedule will not always be technically feasible. This is because it can take longer for power stations to increase output to link up with the power system (synchronise).

Uninstructed Imbalance Payments

All dispatchable generation is required to follow instructions from the control centres within practical limits to ensure the safe and secure operation of the power system. Failure to do so will lead to increased costs or major system problems. This is the reason the Uninstructed Imbalance Payments mechanism, as set out in the Trading and Settlement code, provides economic signals to ensure that dispatchable generation follows its instructions within acceptable practical limits.

Firm Access Quantities

The level of “firm” access to the transmission network relates to financial conditions around a generator’s output. Firm Access means that if the output on to the grid by a particular generator is changed by the Transmission Operator (known as ‘constraint’), then it may be eligible for financial compensation as set out in the Trading & Settlement Code. 

Firm Access is linked to Associated Transmission Reinforcements – this is where upgrades or new infrastructure are planned by the Transmission System Operator. In advance of Firm Access being available, some generators may opt to connect to the system on a “non firm” basis. In this instance, if the output of the generator is changed by the Transmission Operator, the generator will not receive financial compensation as set out in the Trading & Settlement Code.

As the transmission system has developed and new generators have applied to connect, Firm Access studies have been carried out. The following are relevant documents in relation to these studies.

The following documents details the results of our FAQ and ATR Review:

Firm Access Quantity and Associated Transmission Reinforcement Review Briefing Note Published November 2016 and Presentation

The following document details the results for all Gate 3 wind projects:

Results from EirGrid FAQ Analysis for Gate 3 published October 2013

The following document details the results for all Gate 3 Non-Wind projects:

Results from EirGrid FAQ Analysis for Gate 3 Non-Wind published October 2013

The following document details the results for all eligible Non-Group Processing Approach (Non-GPA) projects:

Results from EirGrid FAQ Analysis for Non-GPA projects published October 2013

Those transmission reinforcements assumed to be completed in the period 2012-2020 and included in the study models used for the 2012-2020 FAQ analysis are detailed in the following document:

Transmission Reinforcements Assumed Complete 2012-2020

The technical assumptions underpinning the Gates 1-3 & Eligible Non-GPA FAQ analysis (commenced in August 2012) are available here:

FAQ Analysis for Gate 3 and eligible Non-GPA Projects -Technical Assumptions

An information note which sets out the basis upon which changes in modelling assumptions may affect the determination of FAQs, and subsequently ATRs, during EirGrid’s ITC Program analysis are catered for can be found here:

Application Of Changes In Modelling Assumptions To The ITC Analysis

The results of the original FAQ analysis for Gate 3 projects, completed in January 2010, are available at the following link:

Gate 3 Firm Access Quantities (published January 2010)

Gate 1 and Gate 2 Firm Access Quantities

Following the CER’s direction in June 2011 (CER/11/102) and the publication of the initial Gate 1 and Gate 2 Firm Access Quantities Results in 2011, EirGrid re-evaluated the Gate 1 and Gate 2 Firm Access Quantities to determine if there is any incremental levels of transmission firm access for generators ahead of the completion of a generator’s full complement of Associated Transmission Reinforcements.

The results from this analysis are available in the documents below:

Results from EirGrid FAQ Analysis for Gate 1 published December 2012

Results from EirGrid FAQ Analysis for Gate 2 published October 2013

The following documents detail the results of the FAQ analysis for Gate 1 and Gate 2 which was completed in 2011:    

Gate 1 Firm Access Quantities (published December 2011)

Gate 2 Firm Access Quantities (published December 2011)

For further information on how Firm Access Quantities are calculated and some related information, please refer to Section 2 of the Frequently Asked Questions Documents below.

Frequently Asked Questions

An audit of the results of EirGrid’s initial FAQ analysis for Gate 3 was carried out by consultants appointed by EirGrid in accordance with the CER direction CER/08/260.

The audit report can be viewed by clicking on the link below:

ITC Programme Audit - Final Report

Associated Transmission Reinforcements (ATRs)

Associated Transmission Reinforcements (ATRs) are new or upgraded transmission infrastructure projects. They are associated with a generation project and which must be complete to release a generation project’s FAQ allocation.  To achieve firm access in the Single Electricity Market, the generation project must be connected via its permanent connection as well as its ATRs being complete.

EirGrid publishes ATR status reports on its website on a quarterly basis so that generators can track the status of the ATRs associated with their generation project(s).

The latest Quarterly ATR Status Updates are at the links below.  The Quarterly ATR Status Update should be read along with with the latest Statement of FAQ & ATRs for your generation project.  The first column of dates is the assumed completion date for each ATR.  The freeze date for these assumed completion dates was July 2012. The second column of dates shows the latest update on the completion date or scheduled completion date of each ATR.

Where the scheduled FAQ date for a generation project changes as a result of a change to the scheduled completion date or the completion of an ATR for that generation project, the customer is notified in writing by their System Operator


ATR Status Updates:

Q3 2017 ATR Status Update - published 01-11-17

Q2 2017 ATR Status Update - published 31-Jul-17

Q1 2017 ATR Status Update - published 27-Apr-17

Q4 2016 ATR Status Update - re-published 16-Mar-17

Q3 2016 ATR Status Update - published 28-Oct-16

Q2 2016 ATR Status Update - published 29-Jul-16

Updates for previous years can be found in our Library section.

An Information Note on the sequencing of transmission projects is available here.

Short Circuit Driven Deep Reinforcement Associations (SCRs)

Short Circuit Reinforcements (SCRs) are important in connecting generators who have contracts with EirGrid.

They refer to transmission infrastructure or equipment which is to be replaced prior to the connection of a generator or demand customer and give information on planning and progress. The links below represent the latest list of Short Circuit Reinforcements (SCRs) related to connecting generators.

As of the 2017 Q2 Quarterly web update, all SCRs are now complete. Therefore there will be no further quarterly updates until new SCRs are identified. Where new SCRs are identified, the Quarterly SCR Status Updates will be reinstated.

Q2 2017 SCR Status Update - published 31-Jul-17

Q1 2017 SCR Status Update - published 27-Apr-17

Q4 2016 SCR Status Update - published 27-Jan-17

Q3 2016 SCR Status Update - published 28-Oct-16

Q2 2016 SCR Status Update - published 29-Jul-16

Q1 2016 SCR Status Update - published 29-Apr-16

Q4 2015 SCR Status Update - published 01-Feb-16

Q3 2015 SCR Status Update - published 30-Oct-15

Following a full review of SCRs by EirGrid, each customer received an updated Statement of SCRs associated with their generation project on the 20 June 2014. The Quarterly SCR Website Update lists the SCRs associated with generation projects and the latest status of those SCRs.

The Quarterly SCR Website Update should be read in conjunction with the latest Statement of SCRs for your generation project and shows the latest status on the completion date or scheduled completion date of each SCR as at the 30 June 2015. Any change to the scheduled completion date of a SCR in a subsequent Quarterly SCR Website Update will be highlighted in orange.  

If you expect to be in a position to connect before the scheduled completion date of the Short Circuit Reinforcements associated with your generation project, please contact us at contractmanagement@eirgrid.com.