Integrated Dispatch Model for Combined Heat and Power Plant With Phase-Change Thermal Energy Storage Considering Heat Transfer Process

Combined heat and power (CHP), with its limited flexibility, is one of the leading causes for the curtailment problem of variable renewable energy source (VRES) in Northern China. To increase the flexibility for CHP, thermal energy storage (TES) is considered to be an effective solution, and a phase-change TES demonstration pilot project is now being constructed in Northern China. Almost all the previous studies have modeled the TES device without considering the heat transfer process, which is a main constraint in thermal system analysis. Thus, in this contribution, we consider the heat transfer process for the phase-change TES device installed in a CHP plant based on the steam's three-stage heat transfer model and the entransy dissipation-based thermal resistance theory. An integrated electrical-thermal dispatch model concerning conventional thermal units, VRESs, and CHP units with phase-change TES device is given, and an iteration method for solving this nonlinear programming problem is proposed. Case studies show that it is vital to consider the heat transfer process in the modeling of CHP plant with phase-change TES device, and it has significant influence on the flexibility that the TES device can provide when the working conditions vary.