## 2 Revision of Literature  
To manage the entire microgrid more efficiently, it is necessary to install a metering, communication, and data processing system to allow semi-autonomous or autonomous operation. In this way, possible supply problems can be solved in a shorter period [9,10]. Within this field, we can find various communication technologies, such as Zigbee, WLAN/Wi-Fi, serial communication (Ethernet/RS-232), WiMAX, power line communication, GSM/GPRS, and DASH 7 smart [11]. Among them, the most used are the first mentioned, due to the security, reliability, and scope they offer [12, 13, 14, 15]. The implementation of one or another technology is influenced by the communication distance and the budget available for this component [16]. Independently of the communication technology chosen, every microgrid must have the following communication elements: a defined local communication structure, a hierarchical system of supervision, control and management of the different elements, and intelligent controllers for loads, consumption, and storage systems. As discussed above, a microgrid can operate either connected to the main distribution grid via the point of common coupling (PCC) or disconnected from it, in island mode. A stable and economically efficient mode of operation is required [16]. The microgrid is governed by a central controller (MGCC). It provides set point signals to the equipment controllers, such as generation systems, storage systems, and loads. The control system is responsible for regulating the operating voltage and frequency. It is also responsible for redistributing the load between the different distributed generation (DG) and storage elements, managing the flow with the main grid, and optimising operating costs. In order to control all the generation systems and consumption systems that make up the microgrid and to ensure stable operation and economic efficiency [17], it is necessary to have the installation of smart meters in each piece of the equipment (in case the device does not have an integrated measurement and communication system). The smart meters will monitor in real time different parameters such as voltage, current, power, consumption, etc. to know instantly the operating status, and the existence of any problem that may arise if communication with the generation and/or storage device that records all these parameters is impossible, or to monitor more parameters than those offered by the device. To transmit the data collected by the smart meters to an HMI (Human Machine Interface) in which users can read these data and send operating instructions, it is necessary to install another device. Arduino, which consists of a board with a microcontroller and open software, can be used for this purpose. This device can read the data collected by the Smart Meters, perform calculations if necessary, and send the results where the user wishes. Arduino can communicate with a Raspberry Pi [14; 18], a computer with a reduced board with which greater versatility and calculation power is achieved. Raspberry has Wi-Fi and Ethernet connectivity integrated in the board. These devices are responsible for collecting the data registered by Arduino and communicating all these values with other devices, platforms the user has established, and applications and/or local or online databases to store and visualize all those values. Users who want to collect historical data of all the parameters that the installed devices record, have two different options: the manual download when the device memory is full, or the automated sending to a database (normally in the cloud) [13; 19; 20; 21]. For everything to work, communication protocols (mentioned above) must be established between the different installed devices. The protocol selected differs for each case, device, and location. In order to manage all the equipment, it is necessary to display all the registers in an interface and allow the user to interact with each one of them.