## 1 Introduction  
The Energy Efficiency Directive (Directive 2012/27/EU of the European Parliament and of the Council of 25 October 2012 on energy efficiency, amending Directives 2009/125/EC and 2010/30/EU and repealing Directives 2004/8/EC and 2006/32/EC, OJ L 315, 14.11.2012, p. 1. ), as well as recent communications and proposals from the European Commission in the electricity sector, encourages Member States to deploy Smart Grids. Such transformation which will allow electricity network management to accommodate the growing levels of renewable energy sources foreseen by the European Union energy policy targets in the next decades. Indeed, the growing presence of intrinsically variable--and difficult to predict, renewable energy sources in the electricity network, leads to unstable conditions in terms of frequency and voltage, making the management between power generation and load consumption difficult. A smarter grid supervises and controls this problem ensuring safe, flexible and optimal operation of the system. A key challenge for the transition towards a digital energy is the interoperability between the components of the smart grid. In other words, the devices, systems and sub-systems of the electricity grid should be able to work together and exchange meaningful and understandable information to perform the functions they are supposed to accomplish. Interoperability is at stake for the fact that a single digital energy can be achieved from the convergence of many industrial actors, with different standards, culture and technical background (e.g., electricity, power electronics, home appliances, telecommunications, internet, etc.). A consequence of the multitude of players in the smart grids is that interoperability will not be achieved spontaneously, but it will have to be supported by dedicated policy, standards and technical instruments. Although interoperability has been recognised as a fundamental element for the modernisation of the electricity grid, testing interoperability of smart grids standards is still far from being commonly specified. For this reason, the European Interoperability Centre for electric vehicles and smart grids at the Joint Research Centre (JRC) has developed a systematic approach towards a unified European framework for developing smart grid interoperability tests [1]. Its main goal is to methodically verify the ability of given equipment under test to communicate effectively with other components. The availability of a methodology offers a systematic means to analyse any interoperation flaw against business and user requirements. Further analysis could then be performed to assess the reasons and impact of any flaws and propose potential solutions. The most critical enabler components of a smart grid are the smart meters, which are simple electronic devices that register real-time consumption and generation of electricity, in a household or an industry, and send the data to the electricity retailer for monitoring and billing. The rollout of smart meters in the European Union is massive, with the aim to rollout 200 million smart meters by 2020. The adoption of smart meters will allow consumers to benefit from the progressive digitalisation of the electricity market via a number of different functions including the access to dynamic electricity price contracts, opening up the possibility for consumers who produce their own energy to respond to change in prices and sell in an optimised way to the grid. Smart meters (SM) from the same neighbourhood are connected to a data concentrator, another popular component of the smart grids. The data concentrator (DC) is an electronic device providing communication capability with a large number of smart meters. The data concentrator can be configured to request periodic electricity information (power consumption, voltage, frequency, etc.) from each smart meter. There has been significant work done in the field of smart meters testing.