Methodology to Decrease Packet Loss in IEC 61850 Substation Communication over Wireless 5G Communication

Wireless networks provide huge potential for power system communications as a flexible and cost-effective alternative. However, based on our previous tests with protection communication have indicated that the IEC 61850 based data packet sizes may not be optimal for wireless communication networks. Processing a vast amount of small data packets might also cause packet loss in the networking devices. To decrease packet loss at the power system communication networks, a methodology of combining the Ethernet packets of multiple Sampled Value messages has been tested in a pilot environment. Our methodology has been inspired by IEC 61869-9, in which there are preferably 2 or 6 Application Service Data Units (ASDUs) per frame. However, our methodology simply aggregates the Ethernet payloads of several packets instead of combining the redundant information on the ASDU level. This aggregation has been executed both vertically by combining consecutive packets and horizontally by combining packets of several merging units. The aggregation has been implemented with Rust low-level network programming language using the pnet library.

The methodology has been validated against wired and wireless reference measurements in our pilot environment. A protection use case is used as a realistic application, in which a virtual fault passage indicator uses directional overcurrent protection to indicate the fault locations. The experimental setup consists of multiple merging units, a smart substation control and protection device operating as an edge device, and a wireless 5G communication network, which is coupled with the HIL simulation at the switches and intelligent network appliances. The packet aggregation is implemented at the intelligent network appliances for both compressing at the sender and decompressing at the receiver. Therefore, the packets received by the substation automation devices are not impacted by the aggregation as it remains visible in the wireless communication network only.