  This paper discusses a consensus-based alternating direction method of
multipliers (ADMM) approach to solve the multi-area coordinated
network-constrained unit commitment (NCUC) problem in a distributed manner. Due
to political and technical difficulties, it is neither practical nor feasible
to solve the multi-area coordination problem in a centralized fashion, which
requires full access to all data of individual areas. In comparison, in the
proposed fully-distributed approach, local NCUC problems of individual areas
can be solved independently, and only limited information is exchanged among
adjacent areas for facilitating multi-area coordination. Furthermore, as
traditional ADMM can only guarantee convergence for convex problems, this paper
discusses several strategies to mitigate oscillations, enhance convergence
performance, and derive good-enough feasible solutions, including: (i) A
tie-line power flow based area coordination strategy is designed to reduce the
number of global consensus variables; (ii) Different penalty parameters \r{ho}
are assigned to individual consensus variables and are updated via certain
rules during the iterative procedure, which would reduce the impact of initial
values of \r{ho} on convergence performance; (iii) Heuristic rules are adopted
to fix certain unit commitment variables for avoiding oscillations during the
iterative procedure; and (iv) An asynchronous distributed strategy is studied,
which solves NCUC subproblems of small areas multiple times and exchanges
information with adjacent areas more frequently within one complete run of
slower NCUC subproblems of large areas. Numerical cases illustrate
effectiveness of the proposed asynchronous fully-distributed NCUC approach, and
investigate key factors that would affect its convergence performance.
