光储直流微电网系统的阻抗优化策略及分层稳定化控制方法研究

DC Micro-grid system including PV power generation and energy storage is taken as the research object in this project. Facing the system stabilization problem caused by the worse matching among the dynamic system impedances, equivalent circuit is built, real-time impedance relationship, controller structures and its parameters of each equipment, and essential circuit characteristics of power sources are analyzed, gradational stabilization control method is studied by means of virtual impedance technology. As for the wide-frequency band disturbance problem caused by the complicated loads connected with DC bus, operation principle of virtual capacitor string is discussed, the coupling feature and mathematic calculation basis are analyzed, and engineering process method of differential control and distributed implement method are studied. According to the coupling feature of nonlinear inductor for the current control loop, the novel control method of inductance current based on the model of sampling data is presented, linearization of parasite inductance parameter and quantitative optimization method are analyzed. In order to improve stability margin during the operation, dynamic nonlinear mathematic model of the whole system is built, the conditions of system stabilization including the impedance and power ranges are studied, gradational stabilization control method about impedance optimization and energy management is discussed. The above conclusions are looked upon as the basis of this project, the adaptability of the impedance optimization technique is analyzed, the theoretical analysis and control basis are carried out to improve the system stabilization in the DC microgrid system including PV power generation and energy storage.

项目以光储直流微电网系统为对象，针对系统阻抗动态匹配不佳引入的系统稳定性问题，建立系统的等效电路结构模型，分析系统实时阻抗关系以及各组网单元控制器结构、参数及源介质状态的本质电路结构属性，结合虚拟阻抗优化技术研究系统的分层稳定控制方法。针对复杂负载向母线引入的宽频带扰动问题，研究虚拟电容支路的作用机理，分析其耦合结构特征与定量依据，并讨论其微分控制特质的工程化与分布式实现方法。针对电流环控制器的非线性感抗耦合特征，结合依据变换器混合采样数据模型实现的电感电流新型控制算法，研究电源层寄生电感参数的线性化与定量优化方法。为提高系统整体在动态运行下的稳定裕度，建立系统整体的动态非线性数学模型，分析使系统稳定化的阻抗与功率条件，研究电源层阻抗优化与负载层能量管理的分层稳定化控制技术。以上述研究结论为基础，研究虚拟阻抗优化方法的适用性，为直流微电网系统的稳定化运行提供理论与技术基础。

光储直流微电网作为分布式发电的一种典型能量配置结构获得业界普遍关注，其中的阻抗优化与匹配、系统的综合稳定性评价与优化是该领域的重要研究方向。课题由光储直流微电网系统的阻抗模型研究入手，探索了控制器结构、控制器参数、分布式源介质特征等对组网电力电子系统的等效输出阻抗的综合作用机理，并据此建立了系统的阻抗模型，为采用阻抗分析法对微电网系统运行稳定裕度的定量或定性评价奠定了模型基础。由此，课题讨论了从优化控制器进而优化分布式电力电子装置等效输出阻抗特征的可行性与有效性。通过对储能变换器的控制实施相位补偿控制进而等效优化了等效输出感抗以及扩展了下垂电阻的选取范围，并且改善了控制系统的参数适应性；课题也讨论了通过优化储能双向变换器控制方法对公共直流母线电容进行虚拟扩容的等效电容优化方法，进而增强了系统整体的稳定运行裕度。通过对并网接口电路实施高频阻尼控制，改善了并网接口电路的稳定裕度，进而改善了其作为系统电源层电路的等效输出阻抗。另外，课题也讨论了数字控制延迟对并网接口电路稳定性的作用机理，并采用相位补偿控制器及其优化以应对数字控制延迟对系统的控制带宽以及稳定裕度的影响，并讨论了其对系统等效输出阻抗的作用特征。通过以上研究，一方面为该领域的研究提供了模型基础与参考控制方法，另外，也将研究成果应用在了其它相关工业领域，并获得一定的产业价值与经济效益，进而也验证了研究内容与研究结果的科学价值与工业应用价值。