Glossary

Term	Acronym	Definition
Open Remedial Actions Optimizer	OpenRAO	Open-source project aiming at providing an efficient solution for electrical power systems’ Coordinated Capacity Calculation, Local Security Analysis and Coordinated Security Analysis
Calculation with Scalable and Transparent OptimiseR	CASTOR	Non-costly remedial actions optimiser
Transmission System Operator	TSO	Entity entrusted with transporting energy in the form of natural gas or electrical power on a national or regional level, using fixed infrastructure.
Remedial Action Optimisation	RAO	Provides an optimal selection of remedial actions to handle overloads on network elements (CNECs) in contingency situations (outages)
Individual Grid Model	IGM	The grid model of a specific TSO
Common Grid Model	CGM	The “merged” grid models of multiple TSOs into one grid model
Critical Branch	CB	An important network element with regards to grid security and market exchanges
Critical Outage	CO	A probable event consisting in the loss of 1 or more elements on the grid. Also refers to a contingency.
Critical Branch - Critical Outage	CBCO	Critical Branch monitored after a Critical Outage (same as CNEC)
Critical Network Element	CNE	A monitored Critical Network Element (can be a CB)
Critical Network Element & Contingency	CNEC	Critical Network Element monitored after a critical Contingency (can be a CBCO)
Contingencies, Remedial Actions and other Constraints	CRAC	File model containing COs, CNECs, and remedial actions
Phase Shift Transformer	PST	Transformer that can be used to control the power flow on lines
Remedial Action	RA	Action on the network performed to reduce constraints on CNECs
Linear Remedial Action	LRA	Types of remedial actions considered to have a linear effect on flows (e.g. changing the angle of a PST, the set-point of an HVDC, the set-point of a generation unit)
Preventive Remedial Action	PRA	Remedial action performed on the N-state (i.e before any contingency)
Automatic Remedial Action	ARA	Remedial action triggered automatically without any human intervention after a contingency (also called SPS)
Curative Remedial Action	CRA	Remedial action performed by human activation after a contingency
Remaining Available Margin	RAM	For a CNEC, the remaining flow margin between its actual flow and the maximum flow allowed
Net Transfer Capacity	NTC	Capacity calculation method providing a unique capacity value per frontier by disregarding other bidding zones’ electrical impact
Flow-Based	FB	Capacity calculation method providing a capacity value for each CNEC by taking into account all bidding zones’ electrical impact
Generation and Load Shift Keys	GLSK	Provides net position variation mapping rules to a network’s generators and loads
Power Transfer Distribution Factors	PTDF	Indicates the incremental change in real power that occurs on transmission lines due to real power transfers between two regions
Regional Coordination Center	RCC	Perform tasks of regional relevance in the system operation region (SOR) where they are established, such as, in particular: coordinated capacity calculation, coordinated security analysis and creating common grid models
iTesla Internal Data ModeL	IIDM	The PowSyBl native grid format (see on PowSyBl)
Union for the Co-ordination of Transmission of Electricity	UCTE	The UCTE-DEF (UCTE Data Exchange Format) format is an exchange format specified by the UCTE, for the exchange of grid model among its members
Common Grid Model Exchange Specification	CGMES	An IEC technical specification (TS 61970-600-1, TS 61970-600-2) based on the IEC CIM (Common Information Model) family of standards
Capacity Allocation & Congestion Management	CACM	Methods for calculating how much capacity can market participants use on cross border lines without endangering system security
Regional Security Coordinators	RSC	Evolved into Regional Coordination Centres (RCCs) in July 2022
European Network of Transmission System Operators for Electricity	ENTSO-E	Association for the cooperation of the European transmission system operators (TSOs)
Mixed-Integer Linear Programming	MILP	Optimisation problem in which some of the variables are constrained to be integers, while others are allowed to be non-integers. The objective function is linear with respect to the variables.
Temporary Admissible Transmission Loading	TATL	Admissible load on a CNEC after a contingency in a restricted time frame
Permanent Admissible Transmission Loading	PATL	Admissible load on a CNEC (before or after a contingency) in a steady state
Minimum Margin	MM	The minimum flow margin among all CNECs
Minimum Relative Margin	MRM	Minimum Margin (MM) divided by the sum of PTDFs (sum of zone-to-zone PTDFs on the given CNEC)
Common Information Model	CIM	File format standards developed by ENTSO-E in line with TSO requirements