Grid Code

The aim of the Grid Code is to provide information for market participants as well as rules which establish:

  • the minimum technical, design and operational requirements for connection to and utilisation of the transmission system,
  • the conditions for the provision of ancillary and transmission services.


These conditions are influenced by a large number of transmission system technical requirements including the rules for international cooperation within the UCTE interconnected area. The transmission system operator, the TSO, must take into account all these circumstances when creating the conditions for the connection and operation of transmission system users. Naturally, UCTE cooperation rules are constantly developing and could well be changed in the future and be subject to modification based on operational experience and the level of openness of the electricity market.

The fulfilment of the conditions defined by the Grid Code is not sufficient however to guarantee the safe and efficient operation of the transmission system. The Operating Instructions of the ČEPS Dispatch Centre represent a further stage in the formalisation of relations between the TSO and the user. The validity of the Operating Instructions is defined by the Czech power system dispatch order. This set of documents – the Grid Code together with the Operating Instructions is considered to be the minimum set of rules necessary for ensuring the secure and reliable operation of the transmission system.

GRID CODE (part I.; part II. chapter 1.,3.; part III.)


Part I. - Basic conditions for the utilisation of the transmission system 

The basic Grid Code document specifying its mission, the principles of its creation and the updating process. The competences of the TSO regarding UCTE interconnection are defined including a description of system services. The reader will find important information from various EU directives, the Energy Act, certain implementing regulations and network connection conditions. In addition, specification necessary data for TS operation and development is provided as well as a description of principal technical calculations and the relevant input data and a definition of the terminology employed in the Grid Code. 


Part II. - Ancillary services (AnS)

A description of the methodology employed for the determination of the total value of ancillary services required so as to ensure the reliable and secure operation of the Czech power system. Ancillary services are described (including details of their function and conditions for their provision). This part sets out the conditions for the granting and revocation of metering certification. A description of the methodology for the measurement and evaluation of particular AnS is provided and the conditions for tendering for AnS procurement and subsequent evaluation are defined. The concept of the electronic on-line operation of the Daily Market in AnS on the internet is outlined. A description is provided of how to obtain permission for performing different tests within the power system and the rules for the preparation and approval of such tests. 


Part III. - Provision of system and transmission services

A description of the transmission services market at both the national and international levels including the methodology employed for the determination of available marketable capacity and the organisation of auctions. An examination is made of the verification of the import, export and transit of power on interconnectors carried out in order to provide the technical verification of the feasibility of reliable transmission of all commercial transactions. This part concludes with a definition of the rules for providing documentation for the preparation of transmission system operation.


Part IV. - Development planning of the transmission system 

Sets out the development trends, intentions and goals of the TSO with regard to the further development of the transmission system and the measures to be employed in accomplishing them. This part contains an outline of the application procedure for the connection of new equipment to the transmission system. 


Part V. - Operational security and quality at the transmission level 

Describes the principles of the defence plan including the frequency plan, frequency load shedding and other measures to ensure against voltage and frequency deviations, overloading, cascade spreading after a failure and oscillation and loss of synchronism. The restoration plan is outlined here setting out strategy, priorities and responsibilities during the restoration of the power system after a black-out situation as well as the parameters for the quality of electricity delivered. 


Part VI. - Dispatch control 

The aim here is to familiarise transmission system users, especially those subordinated to control from the ČEPS Dispatch Centre, with the relevant operational procedures. In addition, this part describes the communication of information concerning accidents. 


Part VII. - Transmission system facilities

Concerns the basic technical requirements for high voltage equipment and the principles of operation and maintenance and provides a definition of control systems, trade metering and protection requirements. 


Part VIII. - Transmission system standards

A definition of the relevant standards