A Feasible Zone Analysis Method with Global Partial Load Scanning for Solving Power Flow Coupling Models of CCHP Systems

Abstract

Heat exchanger systems (HXSs) or heat recovery steam generators (HRSGs) are commonly used in 100 kW to 50 MW combined cooling, heating, and power (CCHP) systems. Power flow coupling (PFC) is found in HXSs and is complex for researchers to quantify. This could possibly mislead the dispatch schedule and result in the inaccurate dispatch. PFC is caused by the inlet and outlet temperatures of each component, gas flow pressure variation, conductive medium flow rate, and atmosphere condition variation. In this paper, the expression of PFC is built by using quadratic functions to fit the nonlinearity of thermal dynamics. While fitting the model, the environmental condition needs prediction, which is calculated using phase space reconstruction (PSR) Kalman filter. In order to solve the complex quadratic dispatch model, a hybrid following electricity load (FEL) and following thermal load (FTL) mode for reducing the dimension of dispatch model, and a feasible zone analysis (FZA) method are proposed. As a result, the PFC problem of CCHP system is solved, and the dispatch cost, investment cost, and the maximum power requirements are optimized. In this paper, a case in Jinan, China is studied. The PFC model is proven to be more precise and accurate compared with traditional models.