TSOs maintain operational security through operational planning processes and real-time operations. Operational planning starts over a year before real time as the TSOs define security criteria and undertake system stability studies. Clearly training staff so that they can operate the system safely and securely is also key. The TSOs continually update their plans and refine their analysis as the situation changes, and becomes clearer as real time approaches. They consistently look at system conditions; identify possible concerns and then actions to remedy these concerns.

In the interconnected transmission systems of Europe, there are numerous inter-dependencies and the TSOs must act in a coordinated way to ensure the security of their national systems and of the entire European system, 24 hours a day, and 365 days a year. This means that clear rules, effective communication and well-established processes are critical.

Ensuring that the lights stay on at all times is the primary goal of Europe’s transmission system operators (TSOs). This is a complex task, which requires a broad range of activities to be performed in an efficient and coordinated way. These activities, which take place at different stages, are termed operational security analysis and the goal of keeping the lights on is termed operational security.

The Network Code on Operational Security (NC OS) contains detailed content explaining the various actions and processes which TSOs need to follow to ensure operational security.

• It begins by defining the terms and dealing with the role of regulatory authorities.
• The code then identifies a series of different system states, which are important to identify which of the processes in the code will be applied when. It then moves on to set out operational security requirements, including how to manage short circuits, frequency control, power flows and how to undertake contingency analysis and dynamic stability analysis.
• The OS code then deals with the exchange of data, which is crucial to efficient operational security analysis.
• Finally, it deals with compliance and entry into force.

No. The requirements in the Network Code on Operational Security (NC OS) are based largely on existing practices and do not impose any additional costs on DSOs or on market players.

The NC OS – and for that matter all the network codes – apply to transmission system operators (TSOs), market participants, significant grid users and all other affected parties   In short, the code will apply to any party active in the European electricity system.  While the NC OS involves many requirements that apply specifically to TSOs, it also addresses obligations for generators.

This reflects the fact that for a system to work properly, close interactions between all parties in that system are needed. In the electricity sector, this means customers, distribution system operators (DSOs), TSOs and generators.  Each of these parties plays a role in supporting the system (for example generators can provide services that are vital to ensuring the stability of the grid) and so, different obligations are addressed to those parties.

The network codes build on a long tradition of developing common rules – often put in place at a regional level. Examples are the Nordic Grid Code and Operational Agreement and the Continental European Operational Handbook. These documents establish principles through which multiple TSOs work together to achieve a common objective. These experiences have been drawn on heavily while developing the operational network codes.

In the past, the “gentleman’s agreement” approach was sufficient to create a clear and functioning framework to ensure operational security.  The European electricity sector is changing at an unprecedented speed as markets develop; the generation mix changes and customers become more actively engaged.

These changes and the absolute criticality of operational security mean that legally binding requirements have now become necessary.  These rules move one step beyond optional collaboration and are core to fulfilling the TSOs’ mission of ensuring security of supply and to benefitting all EU citizens.

Because effective coordination between TSOs is a prerequisite for the completion of the European Internal Electricity Market (IEM) and for integrating large volumes of renewable energy generation, the NC OS will contribute to Europe’s energy policy objectives of decarbonising the energy sector and enhancing competition; as well as the third goal of enhancing security of supply.

All operational security limits are based on the capabilities of generators and demand facilities as defined in the Network Code on Requirements for Generators (NC RfG) and the Demand Connection Code (DCC).

Stakeholders have been involved in the NC OS throughout the development process and a number of workshops were organised with distribution system operators (DSOs) and other stakeholders in order to gather their opinions and to discuss concerns. Three workshops were organised with the DSOs technical expert group and four public stakeholder workshops.

A formal public consultation was held between September and October 2012, with over 1000 comments received.   Those comments were analysed and a significant majority of them were taken into account in the final draft version of the NC OS. A detailed analysis of stakeholders’ comments is in the supporting document for the NC OS. These comments were also reconsidered when ENTSO-E decided to work further on the network code in light of the ACER reasoned opinion.

NC OS can be seen as the foundation of operational security principles on which the methodologies, procedures and detailed technical principles for operational planning and scheduling (in the NC OPS) and the requirements for controlling frequency (in the NC LFCR) are built.