# Microgrid Cyber-Security: Review and Challenges toward Resilience
## 1 Introduction  
The sustainable flow of energy, or in other words, energy security, in the field of electrical supply systems, does not always rely on the physical availability of resources. Today's technical challenges are extended to include the constant equilibration of demand-supply systems in terms of electricity quality and cyber security. Upgrading the electrical network has not been as dynamic as it should be. With technology being implemented in almost every area of our modern life and smart applications growing in scope and complexity, the power sector makes its steps towards the smart grid at a pace of an extreme cautiousness. The bidirectional flow of power and information generated and monitored by highly advanced types of equipment and mechanisms signifies the new generation of the energy networks. Smart grids are expected to deliver tangible progress to our conventional power systems on both aspects of efficiency and reliability, all together with integrating the maximum share of renewable resources reinforced by distributed intelligent and demand-side management techniques [1; 2]. Changes will give the consumers and prosumers a wider range of choices and accord them with the possibility to actively participate in the optimizing operation of the system, by means of providing them with detailed instructions on how to better use their supply and act as authorized partners. Smart grid benefits can also be extended to enrich the coupled economic sector through reducing operational costs and losses, generating new job opportunities, and reformulating the face of the energy market with time-based pricing and a more accurate speculation of demand and response profiles [3], in a time where electricity price forecasts have become a fundamental input and an important tool for decision-making mechanisms of the energy service provider companies. But yet, the complexity level of the actual power networks and the critical role that it plays in every domain form a double-edged challenge--especially when the introduced technologies might itself be the source of threat. New types of communication and data-management systems must handle not just the different emerging media trends and smart equipment (e.g., computer-based or microprocessor-based), it also needs to cope with existing legacy systems [4] in a manner that is adjustable to scalability and above all, resistant to cyber intrusion [5]. To this end, smart grids have to come as a complementary solution and not an eliminating or excluding one. These technical uncertainties, plus the additional investment costs, have evoked the political reluctance practiced by energy operators against this shift. Europe has been working on energy transition and smart grids since 2005, starting by creating the smart grid technology platform which has set the year 2020 as a horizon to complete the process [2]. There were also several initiatives that carried out the development of experimental testbeds for smart grids solutions which aimed to highlight the most critical challenges and potentials accompanied by this evolution and their influence on the European power systems. Nevertheless, a further and more holistic analysis that is based on a profound technical understanding of each individual system architecture and basically includes the impact of both social and economic aspects on such heterogeneous systems, is yet to be accomplished in order to be able to trade-off between the existing approaches and pilot experiences, choosing a unique and valid experience that is suitable to be scaled up and replicated [6]. On the other hand, a very promising approach to overcome the majority of previous issues appears through energy communities, in which current grid problems are managed in a coordinated way such that avoiding costly network reinforcement along with maintaining aspired values of the smart grid.