【作者】 杨帆；

【导师】 朱新坚；

【作者基本信息】 上海交通大学 ， 控制理论与控制工程， 2008， 博士

【摘要】 高温燃料电池/燃气轮机混合发电技术具有很高的发电效率和极低的污染物排放水平,在国内外引起广泛的关注。目前,该技术在国外还处于示范电站阶段,国内的相应研究才刚刚起步。本课题是在863工程项目“50kW天然气熔融碳酸盐燃料电池发电系统研究”和“燃料电池/燃气轮机混合动力系统研制”资助下完成的。在参考国内外混合发电系统研究经验的基础上,对熔融碳酸盐燃料电池/燃气轮机混合发电系统(MCFC/GT)进行结构设计、系统建模、动态仿真、性能分析、动态优化和分层控制,最终使设计出的系统在稳定、可靠而且高效运行的同时良好地满足负载的电能需求,为熔融碳酸盐燃料电池/燃气轮机混合发电系统提供必要的技术准备和理论指导。研究的具体内容和成果包括:1.建立了MCFC/GT混合发电系统动态数学模型。本文通过分析比较确定了MCFC和GT混合发电的底层循环式拓扑结构,并采用灵活的模块化建模方法建立该系统的动态模型。首先建立了面向MCFC/GT混合发电系统的简化集中参数型直接内重整熔融碳酸盐燃料电池(DIR-MCFC)模型。然后分别基于最小二乘和非线性最小二乘方法建立了燃气轮机的压气机模块和透平模块,根据质量守恒、热力学公式建立了转子模块、燃烧室模块、换热器模块以及旁通阀等。经仿真验证,该系统动态模型能够正确反映各种操作参数的动态变化和系统电能输出特性,可以作为系统仿真设计、性能分析和控制研究的有效工具。为实现动态优化和控制设计打下坚实的基础。2.研究了MCFC/GT混合发电的动态优化问题,并针对MCFC/GT混合发电系统动态优化问题提出了迭代遗传优化方法。本文针对复杂的动态优化问题,将迭代思想、平滑算子和改进了的遗传寻优操作相结合,设计改进的迭代遗传算法(Novel iterative genetic algorithm, NIGA),并首次利用NIGA智能寻优方法对混合系统进行动态优化的研究。对于NIGA算法,首先将变量离散化,用改进遗传优化算法搜索离散控制变量的最优解,然后在随后的迭代过程中将基准移到刚解得的最优值处,同时收缩控制变量的搜索域,使优化性能指标和控制轨线在迭代过程中不断趋于最优解。采用NIGA根据设计的目标函数离线计算出不同负荷下最优运行轨迹,避免了求解大规模的微分方程组问题,优化结果为以后混合发电系统实际应用中现场的工作人员提供操作指导或直接作为下层控制回路的设定值和系统的前馈输出值,进行闭环优化控制。3.提出并验证了MCFC/GT混合发电系统的分层控制设计。以建立的MCFC/GT混合发电系统的动态模型为对象,结合系统开环仿真分析结果及发电系统NIGA离线动态优化结果,完成系统稳定运行的控制设计。本文针对系统结构庞大、性能复杂且控制参数多的特点,提出具有基础层和监督层的分层控制策略。采用多输出支持向量机回归(Multi-output Support Vector Machine Regression ,MSVR)方法实现监督层、先进复合控制方法实现基础层。首先利用NIGA离线动态优化得到的数据建立基于多输出支持向量机的监督层,该监督层为MCFC/GT混合发电系统提供实时性的优化指导。实验表明基于MSVR的预测精度高于现有的基于神经网络和单输出支持向量机的函数估计方法。在基础控制层,采用分块简化再整合的设计方法,针对各输出参数响应特点,利用AZNPI对系统输出功率进行反馈调节、利用MCFC输出电压对燃料流量进行反馈调节、利用QDRNN-PID对燃烧室温度和MCFC温度进行解耦控制等。最后,将各部分内容按照分层控制设计方案连接起来,仿真验证了分层控制是合理的和有效的。在所设计的分层控制方案下混合发电系统能够跟随负载的电能需求,且具有较高的发电效率,透平入口温度和燃烧室温度及燃料使用率都能维持在系统要求的范围。更多还原

【Abstract】 Fuel cell and gas turbine (FC/GT) hybrid power-generation system with high efficiency and low emissions has been focused and developed all over the world. In the world, the demonstration hybrid power plant has been developed. In China, fuel cell gas turbine hybrid system is still in the early research stages.The work is supported by the national 863 scientific project item“Analysis and control strategy for 50 kW-scale molten carbonate fuel cells power generation system”and“Molten carbonate fuel cells–gas turbine hybrid system”. According to some experiences on hybrid system in China and foreign countries, this dissertation realizes a molten carbonate fuel cell and gas turbine (MCFC/GT) hybrid power-generation system with good performances by simulation design, and makes it operate steadily by the integrated control, providing valuable instructions for developments and applications of hybrid power-generation technologies. The main achievements and contributions are summarized as follows:1. A dynamic model of MCFC/GT hybrid generation system is established. The topological structure of hybrid system based on bottoming mode is used by comparing with variable configurations. Firstly, the reduced lumped parameter DIR-MCFC mode is established. Then, based least square method and nonlinear least square method, the compressor module and turbine module are established respectively. The heat exchanger, catalytic oxidizer and bypass valve are modeled in several simulation modules according to the conservation law of mass and energy, and ideal gas law. At last, these separate modules are connected to build up the total MCFC/GT hybrid system dynamic model according to the designed topological structure. Simulation results show that, the model is able to and also enough to reflect all operating parameters and power output can be used in the simulation design, performance analysis and control research of the system. That lay a solid foundation for dynamic optimization and control research.2. The dynamic optimization problem is introduced in detail, and novel iterative genetic algorithm (NIGA) is proposed to solve the optimal operating trajectories for MCFC/GT hybrid generation system. The proposed algorithm is combined the iteration method and the novel genetic algorithm together. The algorithm is especially practical when the system’s gradient information is unavailable. For the algorithm, the control variables are discretized firstly and the novel genetic algorithm is used to search for the best solution of the discretized control variables. Next, the benchmark is moved to the acquired optimal values in the subsequent iterations and the searching space contracted at the same time, hence the optimization performance index and control profile could achieve the best value gradually through iterations.The algorithm is simple,feasible and efficient. It avoided the problem solving large-scale differential equation group. That will help workers on the spot manipulate the hybrid system in practical application or act as the set points and the feed forward control inputs in order to closed loop optimized control.3. The hierarchical control design is proposed and tested for molten carbonate fuel cell gas turbine hybrid generation system to operate steadily. In this dissertation, for the heavy structure, many performance parameters and complex characteristics, the hierarchical control scheme of MCFC/GT hybrid system based on Multi-output Support Vector Machine Regression (MSVR) supervisor is proposed. Advanced compound control method is the basical control. The setpoints and the values of feedforward control are obtained from MSVR. That is hierarchical control proposed in this dissertation. Optimal control results were successfully modeled and predicted by means of MSVR supervisor. This facilitates optimal feed forward control moves and set points under varying process conditions. The experiment is implemented to illustrate the superiority of the MSVR compared to neural network and SVR. The system operation is separated to some basic processes including system power, fuel utilization, combustion temperature and MCFC temperature to design and test local control strategies (AZNPI feed back power controller, fuel flow controller based on the voltage feed back and QDRNN-PID decoupling temperature controller )firstly. Then, these controlled processes are integrated to realize the ideal steady operation of MCFC/GT hybrid system under the step power loads. The simulation results illustrate the effectiveness of controllers. The hybrid system can track the desired power with high system efficiency and main system parameters are all satisfied with the real online control of the system.更多还原