Integrated Optimization And Dynamic Characteristic Research On Microturbine-based Cooling, Heating And Power System

The distributed energy system, which has advantages in energy saving, environmental protection and high safety, etc, becomes an effective way to ease the energy crisis, reduce the environmental pollution and greenhouse gas emissions, and realize the strategy of sustainable development. As an important development direction of distributed energy system, Microturbine-base Cooling, Heating and Power system (MGT-CCHP system) is one of the best ways to provide small distributed energy with clean, reliable and high quality, and multiple-use. A number of thorough studies have been made on the static performance of the MGT-CCHP system, however, there is still lack of knowledge on its dynamic mechanism, control rules and optimization performance, leading to some difficulties in its planning, design and operation. In this paper, a numerical environment for dynamic characteristics simulation, control system design and integrated optimization of the MGT-CCHP system is established, and a systematic and thorough research is done on dynamic mechanism, control rules and optimization performance of MGT-CCHP system in numerical simulation approach.Aiming at the requirements of model precision and convenient solution in the optimal configuration of MGT-CCHP system, the paper presents a new modeling method of integrated characteristic of the MGT-CCHP system, based on 3E static off-design models of the equipment. An optimal configuration model reflecting the energy consumption, the economic cost and the pollutant emission characteristics of the MGT-CCHP system in off-design conditions is established, which improves the accuracy and precision of optimal configuration results. The calculation problem of configuration optimization is decomposed into the feasible schemes selection and the operation strategy optimization. A predetermined strategy of the schemes selection is proposed based on the structural forming and the load matching, avoiding an explosive growth of the numbers of configuration schemes as well as improves the qualities of the feasible schemes. The equal incremental operation optimization method is presented for solving the operation optimization problem of the MGT-CCHP system with multi-equipment multi-load coupled.The paper puts forward a modeling method with modularization, generalization, and partition lumped, and mechanism, which can overcome the limitation of equipment structures and combining forms of the MGT-CCHP system and meet the requirements of the model generalization as well as the model precision. Mathematical models for the dynamic characteristics of the recuperator-adjustable MGT-CCHP system in single-structure and multi-structure are established for the first time. Based on the platform of Matlab/Simulink, the paper puts forward the predetermined and solution method for the complex model with distribution parameters, differential equations with strong coupling containing differential terms and a set of differential and algebraic equations. Secondary modeling of MGT-CCHP system is realized and the dynamic numerical simulation environment of MGT-CCHP system is built, offering an important platform for the study of the dynamic and characteristic and mechanism of MGT-CCHP system.The MGT-CCHP system including an 80kW recuperator-adjustable microturbine and a 425kW double-effect LiBr-H2O absorption chiller is statically designed and dynamically simulated. Through the disturbance simulation experiments of main regulating variables, the paper quantitatively and qualitatively analyzes the dynamic characteristic of the equipment and the MGT-CCHP system in single-structure and multi-structure deeply. Variations of main parameters as well as dynamic coupling relationships among parameters have been revealed.The paper presents a method to simplify the dynamic mechanism model of MGT-CCHP system and constructs the transfer function model which is suitable for CCHP system control design. It provides an important reference for the control modeling of the MGT-CCHP system with flexible structure and variable design parameters. The paper studies on the coordinated control problem of the recuperator-adjustable MGT-CCHP system in single-structure and multi-structure. Using the exhaust temperature of microturbine as a key parameter, the paper presents a decomposition compensation strategy and realizes the coordinated control of the single-structure MGT-CCHP system based on the multi-variable frequency domain design method. Based on the input and output energy balance of the main gas pipe, the paper designs the closed-loop control of multi-structure MGT-CCHP system and realizes the coordinated operation of microturbine group and Libr-H2O absorption chiller group.A new general linear matrix model for the operation optimization of the grid connected MGT-CCHP system without energy storage is established by mix logic dynamic modeling method. The model properly reflects the complex coupling characteristics of the multi-equipment integration and the multi-load generation. Considering operation load limits and on-off logic of the equipment, the model can be used to study the system operation characteristics under the combination of load sequence strategies and target strategies. Through the optimization example, the paper analyzes the performance of the model and the CHP unit operation characteristic when tracking load demand in the economic goal driven. Furthermore, the paper also discusses the optimal operation rules of the MGT-CCHP system in the economic strategy, the energy efficiency strategy, and the environmental protection strategy as well as the comprehensive strategy.