Constrained Optimization of Multicast Routing for Wide Area Control of Smart Grid

Wide area control (WAC) is highly desirable for maintaining the stability of large-scale smart grid. It requires the support of real-time data communications with low latency, which leads to the consideration of the multicast technique for routing of data packets of various measurements, control signals, and commands. While the feasibility of multicast in WAC communications has been investigated, there is a lack of a general framework to formulate and solve the multicast routing problem, particularly for WAC. To tackle this problem, this paper presents a systematic approach to constrained optimization of multicast routing in WAC over wide area networks (WANs) with a publish-subscribe architecture. To fulfil the requirements of real-time WAC communications, the optimization is formulated to minimize the end-to-end delay over WANs subject to bandwidth constraints. Then, the constrained optimization is solved theoretically by using Lagrangian Relaxation. The theoretic results are implemented in an iterative bandwidth-constrained minimum Steiner tree algorithm. Simulations are conducted to demonstrate the approach presented in this paper.