Definitions

Capacity Calculation Region (CCR)

The geographic area in which the coordinated capacity calculation is applied.

Capacity Mechanism (CM)

A temporary non-market measure to ensure the achievement of the necessary level of resource adequacy by remunerating resources for their availability, excluding measures relating to ancillary services or congestion management.

Core Region (also Core Capacity Calculation Region)

Capacity calculation region as defined in ACER’s Definition of the Capacity Calculation Regions in accordance with Article 15(1) of the Commission Regulation (EU) 2015/1222 of 24 July 2015 establishing a Guideline on Capacity Allocation and Congestion Management and which covers France, Germany, Belgium, the Netherlands, Luxembourg, Austria, Poland, the Czech Republic, Slovakia, Hungary, Romania, Slovenia and Croatia.

Demand-Side Response (DSR)

The change of electricity load by final customers from their normal or current consumption patterns in response to market signals.

Energy Not Served (ENS) [GWh/year]

– For a single node, the energy which is not supplied during a single Monte Carlo sample/simulation year due to the demand in the node exceeding the combination of available resource capacity and electricity imports. For a geographical area with multiple nodes, ENS is the total energy not surved of all its nodes. A null ENS suggests that there are no adequacy concerns.

Expected Energy Not Served (EENS) [GWh/year]

For a given geography, the mathematical average of the ENS calculated over the total number of Monte Carlo sample/simulation years.

Explicitly Modelled Systems

Electric systems which are modelled in detail, i.e. electric systems which are an integral part of the European power system and for which System Operations Guideline (SO GL) article 81 or article 106 is applicable. These systems shall be modelled by considering each element of the probabilistic model set in this methodology. Inverse of non-explicitly modelled systems.

Flow-Based (FB) approach/model

A capacity calculation method in which energy exchanges between bidding zones are limited by power transfer distribution factors and available margins on a critical network element.

Flow-Based Market Coupling (FBMC)

A mechanism to couple different electricity markets, increasing the overall economic efficiency, while taking into account the available transmission capacity between different bidding zones using the FB approach/model.

Forced Outage (also Unplanned Outage)

State of a resource capacity when it is unavailable in the power system and the outage was not planned in advance. These outages include breakdowns and any other unforeseen unavailabilities. Inverse of planned outage.

Frequency Containment Reserves (FCR) (also primary reserves)

The active power reserves available to contain system frequency after the occurrence of an imbalance.

Frequency Restoration Reserves (FRR) (also secondary reserves)

The active power reserves available to restore system frequency to the nominal frequency and, for a synchronous area consisting of more than one load-frequency control area, to restore power balance to the scheduled value. They can either be triggered automatically following a TSO’s signal (aFRR) or manually (mFRR).

I-SEM

Stands for Integrated Single Electricity Market, a wholesale electricity market where electricity is traded in bulk across the island of Ireland.

Loss of Load Duration (LLD) [h/year]

For a single node, the number of hours during which the node experiences ENS during a single Monte Carlo sample/simulation year. For a geographical area with multiple nodes, LLD is the number of hours during which at least one node of the area experiences ENS during a single Monte Carlo sample/simulation year. A null LLD suggests that there are no adequacy concerns.

Loss of Load Expectation (LOLE) [h/year]

For a given geography, the mathematical average of the Loss of Load Durations over the total number of Monte Carlo sample/simulation years.

National Trends Scenario

A scenario considering projected demand and supply forecasts, including best estimates on likelihood of retirement, mothballing, new-build of generation assets and measures to reach energy efficiency, and considering the state of the grid in line with the Ten-Year Network Development Plan (TYNDP) and most recent national development plans.

Net Transmission/Transfer Capacity (NTC) approach/model

A coordinated capacity calculation method based on the principle of assessing and defining ex ante a maximum energy exchange between adjacent bidding zones. In contrast to the FB approach, capacity allocation takes place entirely ex ante the market clearing.

Non‑explicitly Modelled Systems (also implicitly modelled systems)

Electric systems which are not modelled except for their import/export time series with explicitly modelled systems.

Non-renewable Energy Sources

Energy from non-renewable sources, namely oil, natural gas, coal, sewage treatment plant gas and nuclear energy. Inverse of renewable energy sources.

Planned outage

State of a resource capacity when it is not available in the power system and the outage was planned in advance. In contrast to forced or unplanned outage. These outages include maintenance, mothballing and any other unavailabilities that were planned in advance.

Renewable Energy Sources (RES) (also energy from renewable sources or renewable energy)

Energy from renewable non-fossil sources, namely wind, solar (solar thermal and solar photovoltaic) and geothermal energy, ambient energy, tide, wave and other ocean energy, hydropower, biomass, landfill gas, and biogas.

Replacement Reserves (also tertiary reserves)

Active power reserves available to restore or support the required level of FRR to be prepared for additional system imbalances, including generation reserves.

Reserve Capacity

The frequency containment reserves, frequency restoration reserves or replacement reserves that need to be available to the transmission system operator.

Target Year (TY)

A specific year analysed in MAF constituting a dependency of resource capacities, grid capacities and demand levels.

Thermal Generation

Production of electricity from thermal energy obtained from the conversion of primary energy sources, namely oil, natural gas, coal, nuclear energy, solar thermal, geothermal energy, biomass, landfill gas, sewage treatment plant gas, and biogas.

Unit Commitment and Economic Dispatch (UCED)

A mathematical optimisation problem which determines the commitment schedule of generation units and their level of generation in order to meet demand for every time step of the modelling horizon. The objective of the problem is to minimize operational cost while satisfying the operational constraints of the power system.

Unplanned Outage

See Forced Outage.

Value of Lost Load (VoLL) [€/MWh]

An estimation of the maximum electricity price that each end user type is willing to pay to avoid an outage.

Abbrevations

AD

Annual Demand

AHC

Advanced Hybrid Coupling

AYD

Average Yearly Demand

CCR

Capacity Calculation Region

CEE

Central-East Europe

CEP

Clean Energy Package

CHP

Combined Heat and Power

CM

Capacity Mechanism

CNEC

Critical Network Element and Contingency

CONE

Cost of New Entry

CWE

Central-Western Europe

DSR

Demand-Side Response

EENS

Expected Energy Not Served

EF

External Flow

ENS

Energy Not Served

EENS

Expected Energy Not Served

ENTSO-E

European Network for Transmission System Operators for Electricity

ERAA

European Resource Adequacy Assessment

ETRI

Energy Technology Reference Indicator

EUE

Expected Unserved Energy

EUPHEMIA

Pan-European Hybrid Electricity Market Integration Algorithm

EVA

Economic Viability Assessment

FB

Flow-Based

FBMC

Flow-Based Market Coupling

FO&M

Facilities, Operation and Management

FCR

Frequency Containment Reserve

FRR

Frequency Restoration Reserve

GSK

Generation Shift Key

HVAC

High-Voltage Alternating Current

HVDC

High-Voltage Direct Current

IEA

International Energy Agency

I-SEM

Integrated Single Electricity Market

LDC

Load Duration Curve

LLD

Loss of Load Duration

LOLE

Loss of Load Expectation

LOLP

Loss of Load Probability

LT

Long-Term

MAF

Mid-Term Adequacy Forecast

MC

Monte Carlo

MILP

Mixed Integer Linear Programming

MPD

Maximum Peak Demand

NGC

Net Generating Capacity

NTC

Net Transfer Capacity

OM

Outage Minutes

P2G

Power-to-Gas

P2H

Power-to-Hydrogen

P2X

Power-to-X

P50

50th Percentile

P95

95th Percentile

PECD

Pan-European Climate Database

PEMMDB

Pan-European Market Modelling Database

PRIMES

Price-Induced Market Equilibrium System

PST

Phase Shifting Transformer

PTDF

Power Transfer Distribution Factor

PV

Photovoltaics

RAM

Remaining Available Margin

RES

Renewable Energy Source

SAI

System Adequacy Indicator

SHC

Standard Hybrid Coupling

SVD

Singular Value Decomposition

TFEU

Treaty on the Functioning of the European Union

TSO

Transmission System Operator

TY

Target Year

TYNDP

Ten-Year Network Development Plan

UCED

Unit Commitment and Economic Dispatch

VoLL

Value of Lost Load

WACC

Weighted Average Cost of Capital

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