# Reducing Detrimental Communication Failure Impacts in Microgrids by Using Deep Learning Techniques
## 3 Link Loss Effects
### Impact of Link Failure on a Grid-Connected MG with Grid-Feeding Inverters  
In order to demonstrate the effects of communication link loss on the power regulation of a typical residential MG an experimental testbed was prepared and a test scenario was created. The rationale behind this test was to show how an external EMS that transmits power setpoints for the ESS, through the communication network, can contribute to a more desirable MG internal power balancing and minimize the PCC power exchange.  
In the setup, three grid-feeding 2.2 kW _dantfoss_ inverters were utilized with a shared DC link and an AC grid-connection point of common coupling (PCC). These inverters represent _consumption, PV production, and an ESS_ that is considered fully charged at the beginning of the day. In this experimental simulation consumption and PV generation profiles were synthetically generated (based on real data) at 1-minute resolution for a one-day time horizon.  
Figure 2: Secondary control for different types of inverters. (**a**) Grid-forming and VSI. (**b**) Grid-feeding and CSI. The values with a star superscript represent secondary control references.  
An external EMS that receives the power measurements from the inverters and calculates and transmits proper power references for the ESS is included in our testbed. This EMS is connected to the other devices through a message queuing telemetry transport (MQTT) communication structure that was created by using micro-python enabled microcontrollers [2]. A photo of this experimental testbed is provided in Figure 3.  
The PCC power and energy exchange results are numerically presented by comparing the normal scenario (with an operational communication system) with a no control scenario that emulates communication link loss. The results are illustrated in Figure 4. A comprehensive descriptions of the experimental setup including the communication infrastructure and the MG control algorithms are provided in a previously published research article by the authors [2].  
Table 2 summarizes the results, the first row represents 24 h energy values while the power exchange root mean square error (RMSE) indicators are provided in the second row. These RMSEs are calculated assuming that the ideal situation is zero PCC power exchange.  
As it can be observed the PV production (2.145 kWh) is not enough to meet the demand (\(-\)2.599 kWh) in the 24 h of the test period. In other words, internal energy balancing cannot be achieved without energy exchange with the stiff-grid or utilizing an operational ESS. In the ESS model used for this experiment [2], the initial state-of-charge (SoC) level was assumed to be one so that it can compensate for the energy deficit effectively.  
The forth and fifth columns of the table present the PCC energy exchange and power RMSE results for two scenarios of communication link down (PCC no control) and operational communication system that transmit ESS power references generated by the external EMS (PCC EMS). As it can be observed, if the communication link fails the daily PCC energy exchange that is (0.019 kWh) exported to the grid will be changed to (\(-\)0.455 kWh)  
Figure 3: Experimental setup.  
imported from the grid which represents a value of %104.2 increase. A similar affect of the link failure can be observed on power exchange RMSE values.