**10. GOOSE round trip latencies results and discussion**

GOOSE latencies was measured for the round trip GOOSE based LoM laboratory setup and results are presented. The status of the main supply DPST.ECPConn or the DRCS.ModOnConn data objects was monitored. If one from the above mentioned data object indicate or show "False" indication it signify the disconnection of the main supply from the electrical grid or the main supply is electrically connected to the grid but the connection is not in operation, respectively. In both cases there is LoM a situation and DERs must be disconnected or changed to the island operation mode. By publishing the main supply status within the multicast GOOSE message it is eventually distributed to all the subscribers and LoM situation is properly handled even with high penetration of DERs. According to the test scenarios 100 trials of DPST.ECPConn and DRCS.ModOnConn status changes had been made and published within GOOSE messages from the Opal-rt simulator. Different IEDs


**Table 1.**

*IEDs latency in millisecond.*

are subscribing to Opal-rt GOOSE messages and monitoring the status of the main supply. While, another GOOSE message are published from the subscriber IEDs upon receiving and processing the Opal-rt GOOSE. All the GOOSE messages are recorded with the IEDScout for the round trip analyzing purposes.

Different subscriber IEDs are inherently able to monitor other data objects from other LNs that may include in to the designed ICD file. These data object status may be used to observe and response to all the different changes in the main supply status, which enables also some advanced operational scenarios. From the above tested scenarios, LoM protection function and may other functionalities have been proven to be possible both with the newly introduced light-weight IEC 61850 FPGA and embedded microcontroller. According to the achieving, results different round trip times for the communication channel had slightly vary depending on the communication channel and receiving end IED. The results also behave according to normal distribution model, which was expected. Since there was no other traffic within the communication channel in this test, and GOOSE messages with high priority (4) and short packet length were used the Ethernet communication system turned out to have very high reliability. Using the normal distribution probability density function the mean of the round trip latency of the GOOSE messages latencies had been calculated as illustrated in **Table 1**.

From (1) round trip latency was for BBB 11.2 ms and FPGA 4.2 ms. Based on the results, it is clear that the FPGA is a more promising instrument with less round trip latency (4.2 ms) that could better be used for the smart grid or microgrid central controller. In addition, the round trip latency for the FPGA is less than the other IEDs in which that was expected. Since the FPGA has Dual-Core ARM Cortex™-A9 (925 MHz) processor as well as 10/100/1000 Mbps Ethernet with the high-speed bus to exchange data between the hard processor system (HPS) and FPGA whereas the BBB has AM335x 1GHz ARM® Cortex-A8, and 10/100 Mbps Ethernet.

Lastly, we recommend that it is the time indeed for the researcher to really start looking/implementing these developed light weight IEDs, standards and testing them, in a way that we can see where the system/standards vulnerabilities might lay/practically do real-time measuring/evaluating in order to evaluate the IEDs development and fall the standards knowledge gaps. Also, measure and improve the energy system resiliency [17].

#### **11. Conclusion**

In this chapter, the monitoring, control and protection solutions and their relevant communication system have been designed based on IEC 61850 and implemented on hardware platforms, FPGA, BeagleBoneBlack and commercial IEDs. The development process and performance of LoM monitoring and control scheme on a light weighted intelligent electronic device has been investigated. The performance of the IEDs has been evaluated through hardware-in-the-loop test in terms of communication latency, processing time, and finally the performance of control action. The FPGA has performed better compared to BeagleBonBlack and is more suitable for micro-grid central controller. It is worth to mention that such an open-source flexible light-weighted IED based on IEC 61850 can provide a base to advance research in the direction of (Micro)-grid automation and control.
