Methodology of capacity calculation

Below is information on the principles of determining available capacity in given entry and exit zones from the transmission system.

IIS applies definitions consistent with Regulation (EC) No 715/2009 of the European Parliament and of the Council of 13 July 2009 on conditions for access to the natural gas transmission networks (hereinafter European Union Regulation) and Regulation of the Ministry of Economy of 2 July 2010 on the operation of the transmission system (hereinafter ME Ruling) and consistent with Transmission Network Code (TNC).

General Principles:

Determination of technical capacities is performed with application of a mathematical model and projection of the transmission network using tools for hydraulic calculations - SIMONE. Calculations are performed with the use of algorithms defined by the manufacturer.
In analyses, loads on particular points are considered on the basis of concluded Transmission Contracts and the awarded (Capacity Allocation) as well as the concluded Connection Agreements. In the hydraulic analyses, for the adopted network load, TSO analyses system operation, taking into consideration transmission network integrity and operational requirements. In this way, taking account of capacities at entry points, available compression station and transmission system operating parameters, TSO defines the capacity which can be offered on continuous basis at given exit points while meeting the minimum pressure requirement defined for given exit point.

Technical capacity designates the maximum continuous capacity which can be offered by the transmission system operator to network users, in consideration of system integrity and transmission network operational requirements.
Technical capacity at individual physical exit points which are part of a given point proper (hereinafter zone) is not synonymous with technical capacity of that zone.
Change of contracted volumes in one zone could reflect on technical capacities of the remaining zones.
According to the Regulation of the Ministry of Economy of 2 July 2010 on the operation of the transmission system, in the event of changes in earlier operating requirements or technical parameters of installation or network facilities, for applicants from Group A and B sub-group II, it is necessary to define the system entry point through which fuel for transmission will be introduced to the system.
 Technical capacity (or available capacity) can be verified after the system entry point is defined.

Contracted capacity designates the capacity which transmission system operator allocated to a network user under a Transmission Contract.
Allocated (i.e. contracted) capacity within the meaning of definition (715/ Article 2 point 19) does not take into account the concluded connection contracts.

Available capacity designates the portion of technical capacity which is unallocated and at the given moment is available in the system.
Available capacity at any physical exit point of a given zone is limited by the capacity of station technical-measurement system, with additional consideration of local limitations presented by line elements (limited diameters of connector gas pipelines).
Available capacity at any physical exit point of a given zone is not synonymous with available capacity of that zone.

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