# Microgrid Cyber-Security: Review and Challenges toward Resilience
## 4 Perspective-Based Interventions Addressing Cyber Attacks  
### Microgrid Communication  
Being a cyber-physical system, microgrids inherent equally advantages and disadvantages of the combined systems. Communication network is essential to effectively incorporate many of desired features of the smart grid, such as the distributed automated system, distributed energy resource protection, islanding, and the display of network state and performance. Standard communication problems also appear in microgrids, as it suffers from incompatibility between different types of heterogeneous communication technologies [13], besides the increasing reliance on Wi-Fi and internet-based communications, which are more susceptible to cyber interference but still essential for ancillary services related to microgrids, such as weather forecast data, fuel prices,  
Figure 3: Modern basic structure of a microgrid. peak hours, etc. [13]. Taking into consideration the expanding amount of data transferred between microgrid's components, different connected microgrids, or with an external centralized control and monitoring point, upon the design of the control structure. Satellite data (GPS) might also be a sort of communicated signals under danger in synchronous microgrid with phasor measurement units (PMUs). On the other side, intrusion detection, firewall, and other selected solutions from the traditional security measures against rudimentary attacks targeting conventional data networks can also be included in smart microgrid applications [33]. While some prefer to leave the power generation control network isolated from the public network as a countermeasure against cyber contingencies, the leverage of open transmission protocols and computers with common operating systems that performed as intelligent electronic devices (IED) cannot be neglected nor eliminated today. Especially with essential improvements on automation efficiency and control system costs [16]. As an attempt to study and simulate the influence of an attacked communication network on electric power systems, earlier efforts went to model the attacks as a time delay to be accounted within the control loop, a subject that has been widely explored even outside the scope of cyber-attacks. For example, in an islanded microgrid, the authors in [34] have examined the communication delay limits beyond which we might risk having instability issues. They proposed an impact mitigation approach that revolves around gain scheduling for PI (proportional-integral) used in the secondary frequency controller that can be adopted in other microgrids as long as they can be modeled in the same small-signal model. However, these assumptions on the nature of attack impacts are oversimplified and do not fully cover the new debouching aspect of joint cyber-physical models [35; 36]. Others argue on the matter of communication latency's impact on microgrid control on the first place, building on an example that puts out shreds of evidence on having an inconspicuous and highly nonlinear relationship of delay rates between the source causing the delay and the resulting delays in the networks [37]. They also state the fact that, except for the simplest of cases, deriving tight bounds between delays, or other relevant metrics such as loss rates, is nearly impossible, especially when the models' analytical accuracy declines as the network size grows from single-hop settings to relay networks. Taking the communication problem to a larger extent, a Cyber-Physical Power System (CPPS), ref. [38] digs into what might be a better communication configuration in terms of preventing a cascading failure, and in a comparison, based on transmission efficiency threshold values, they find that double-star communication networks perform better than the mesh communication networks. Preventing cascading failure in cyber-physical power systems (CPPS) through a comprehensive analysis of the mechanisms and dynamical characteristics of interdependent networks was also the focus of the research presented in [2].