Increasing Flexibility of Combined Heat and Power Systems Through Optimal Dispatch With Variable Mass Flow

In combined heat and power systems, varying mass flow can better make use of the heating system’s 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 integer variables without compromising on accuracy. Subsequently, a novel decomposition method is proposed to solve the resulting optimization model with bilinear constraints. Namely, the original optimization model is decomposed into a lower-level convex sub-problem with the fixed mass flow and a simple upper-level problem to search for the optimal mass flow. Numerical tests show that the proposed method can achieve lower generation costs than existing variable mass flow dispatch methods with outstanding computational efficiency.