# Internet of Things for Modern Energy Systems: State-of-the-Art, Challenges, and Open Issues
## 1 Introduction
This means, that based on the application and the needs, an energy system should be modeled not only in every single aspect, but also in an integrated framework. In [3], it has been mentioned that there is no great effort about the integration of communication systems and power systems, which leads to some unreal simulation. Figure 1: Energy system scheme including electrical, thermal, and communication infrastructures. Talking about IoT, integration of all subsystems is important because IoT is a matter of communication among smart objects, regardless of their category. In this manner, co-simulation is proposed in some attempts [12; 13; 14; 15]. For example, in [12], a well-integrated simulation considering both the power system and communication system is presented to find a cost-effective communication system for MGs avoiding a steep learning curve between the mentioned two parts. In [13], a framework is presented for co-simulation of energy systems using a middleware which helps to get the benefits of standard software like MATPOWER 6.0, which is an open-source Matlab-based simulation package, Mosaik, which is a co-simulation framework for smart grids, etc. In this manner, different analyzing models in steady-state and transient mode can be considered in a unified framework. In [14], a co-simulation model taking into account events in both power and communication simulations is designed to minimize synchronization delay error. In [15], a centralized co-simulation architecture is designed to model power and communication system of an energy system. In this manner, PSCAD/EMTDC, which is a power simulation software, is used to simulate the transient part of the power system, Optimized Network Engineering Tool (OPNET) is hired to simulate communication network, and Cyber Physical Java Simulator is used as an interface between the mentioned platforms. This centralized co-simulation is used for testing protection behavior of MGs. Mostly, a framework or architecture should be defined in advance to specify the domain of each application in every subsystem. To make it clear, let us consider a Smart Home (SH) environment where a wireless local area networking based on WiFi communication is used. In such system, devices should not only follow the communication requirements based on the IEEE 802.11 standards, but also meet the required electrical specifications at the low-voltage distribution network (e.g., IEC 60038). In a higher level, a communication infrastructure based on wired LAN, WLAN, WiMaX, or optical fiber can be used to form a Wide-Area Measurement System (WAMS) [16; 17]. To date, there has also been a lot of effort on IoT and its application in fields like healthcare, SHs, etc. [2; 18; 19]. However, there are many challenges in this area. In [18], it has been mentioned that, as new concepts like Cyber Physical Systems (CPSs) and IoT are introduced into energy systems, security of the system is threatened by cyber-attacks. The other challenge mentioned in [19] is how to connect different devices developed by different protocols and standards in a single IoT platform. In [20], authors discussed challenges in Energy Internet from the software viewpoint. In addition, different aspects of implementing the IoT into energy systems such as tool-vendor's and programmer's perception are discussed, physical constraints are not considered and explained. In [21], a great effort has been done in order to assess different challenges such as security, power management, sensing challenges, etc. of the Energy Internet. Although some recommendations are introduced in order to overcome the aforementioned challenges, modern power systems challenges such as different system architectures and integration of the various energy types are not discussed in detail in this review paper. In [22], the main issues in IoT-based energy systems are introduced, yet no specific recommendation is introduced.