Cooperative Congestion Control in Power Grid Communication Networks
Real-time guarantees (end-end latency deadlines and critical data loss rate) of PMU flows can be violated when transient congestion occurs in the NASPInet. Such traffic congestion can be caused by variable compression of the PMU data or other sensory data; by increased sending rates of real-time (RT) PMU flows because of unexpected critical events/observations in their sensory space; or by changing demands by control centers due to extended power grid state analysis. The goals of this activity were to provide a Cooperative Congestion Control (CCC) framework to be used in the NASPInet, to protect the real-time guarantees of the PMU flows during transient instability periods, and to utilize the cooperative nature of the nodes in the NASPInet and the flows that originate from the same substation. The CCC framework we created offers multiple service class queuing, cooperative real-time flow scheduling and BW reassignment, and cooperative coordination and back pressure approaches among neighboring nodes to counter the transient congestion state. The CCC framework includes an overlay router/phasor gateway design and a congestion notification protocol. It has an adapter unit that is the primary component where the BW reassignment algorithm and cooperative coordination protocol reside. The CCC framework made it possible to achieve real-time guarantees of the PMU flows during the transient instability period (between the 40th and 100th seconds).