  In combined heat and power systems, varying mass flow can better make use of
the heating system inertia to increase the flexibility of electric power
systems. This is challenging, however, due to integer variables and bilinear
constraints in existing optimal dispatch models. In this paper, we incorporate
an improved heat pipeline model to eliminate complexity from integer variables
without compromise on accuracy. Subsequently, the resulting optimal dispatch
model with bilinear constraints is solved by the proposed modified Generalized
Benders Decomposition method, which decomposes the optimal dispatch model into
a convex sub-problem with the fixed mass flow and a simple upper-level problem
searching for the optimal mass flow. Comparisons with existing benchmarks show
that the proposed method can achieve lower operation costs with outstanding
computational efficiency.
