The security of the electricity system


Smart Transmission Solutions


One of Terna's main needs is to make the transmission grid dynamic, i.e. capable of evolving rapidly and effectively with respect to scenarios that change quickly and unpredictably.

In the Development Plan, Terna has planned actions capable of ensuring, under various operating conditions, the electricity system’s needs for security, reliability and efficiency, maximizing the timely and flexible use of existing infrastructure and thus facilitating integration of growing production from renewable sources, including those not directly connected to the NTG.

Among these we can note:

  • installation of electrical equipment (PST - Phase Shifting Transformers) for power flow control on the High and Very High Voltage grids;
  • installation of synchronous condensers to improve the stability and operating security of the system;
  • installation of reactors and condensers for proper management of reactive power flows on the grid, with consequent cost reduction for the Dispatching Market;
  • use of high-capacity conductors to maximize the transport capacity of the existing lines also on the basis of the temperature (Dynamic Thermal Rating - DTR). The testing will make it possible to define types and standards for applying the method for the purposes of progressive implementation and diffusion on critical routes for high wind power production starting from the South and Sicily;
  • testing of diffused accumulation systems to maximize the exploitation of power from renewable sources and to improve the regulation of the High and Very High Voltage systems;
  • initiatives based on smart logics aimed at improving the prediction and control of distributed generation.

These solutions are generally characterized by reduced environmental impact (because they enable maximisation of existing asset use), and by implementation times and costs which are typically lower than those necessary for the creation of new network infrastructures (high voltage lines and stations).

Also regarding innovative solutions, the following initiatives are planned:

  • Participation in the GREEN-ME project (Grid integration of Renewable Energy sources in the North - Mediterranean): the project was presented to the European Commission, in the context of the Connecting Europe Facility, by Italian and French TSOs and DSOs (Distribution System Operators), and relates to the development of systems required to integrate distributed generation in an area stretching from the South of France to the Regions of Northern Italy. The project is conditional on the possible financing of the activities envisaged by the European Commission.
  • Improvement of the identification and control of the grid with digital systems: exploiting the potential of digital equipment to provide measurements directly for the analysis and monitoring of service quality.
  • Monitoring grids: the growing impact of renewable sources also on the distribution grids calls for data collection and modelling which would enable a more detailed view of the load/generation on distribution systems that operate with the transmission grid.


Ensuring the security of the Italian electricity system interconnected with the European grid is a sensitive task, which Terna performs through a series of actions determined by a scrupulous assessment of operating risks.

The objective is to maintain the risk of service outage within pre-established limits and mitigate the negative consequences of such events as much as possible, if they occur.


For Terna, preventing and containing operating risk means monitoring and protecting the physical integrity of its plants, preparing defence plans to limit malfunctions, preventive planning of operations, improving the capacity for real-time control, training operators, developing new methods in support of the process of planning and control, increasing the reliability of supporting resources, and coordinating management of the system interconnected with neighbouring TSOs.

The projects are set out in the Security Plan for the Electricity System, prepared by Terna and approved by the Ministry of Economic Development. The Plan, which in 2012 reached its ninth edition, is drawn up every year with a four-year planning period. In the various editions of the Plan the approach to the security of the electricity system has become increasingly complex.

In fact, the current structure of the Security Plan provides for eight subject areas relating to the activities of planning, control, regulation and protection, restarting and monitoring of the electricity system, as well as an area devoted to safe and optimal management of renewable resources.

The 2012 Plan also provides for projects aimed at managing the system under expected medium/long-term operation scenarios, characterized by important new elements, including increased production distributed from renewable sources.

To facilitate full integration of these sources and resolve critical security issues associated with them, new initiatives were provided for in this Plan which cover the creation and use of non-conventional systems for frequency regulation on the major islands based on electrochemical accumulation systems.

The main objectives achieved in 2012 were:

  • development of tools to forecast load and generation from renewable sources and to support decisions made ever closer to real time;
  • testing of methodologies for real-time security checks on the basis of the real environmental and operating conditions on a series of High Voltage lines, some of which are characterized by high wind power production;
  • introduction of mechanisms for defining and providing medium-term production capacity;
  • implementation of instruments and optimization procedures for coordinated voltage regulation;
  • launch of a new initiative for the use of non-conventional systems based on electrochemical accumulation for ultra-rapid frequency regulation on the Major Islands;
  • simulation and performance of the first test on restarting from abroad (France);
  • implementation of a project for congestion and stability control in the Southern Area which is particularly affected by distributed generation from renewable sources (integration of the new PST - Phase Shifting Transformers - in Foggia and Villanova).

In 2012 Security Plan investments amounted to 63 million euro.

The ninth edition of the Security Plan for the years 2012-2015 projects investments of approximately 242 million euro.