级联交流高频链双向变流器的模块化集成优化与分布式控制方法

The cascaded high-frequency AC linked converter topology has the benefits such as high frequency isolation, medium voltage accession, which would position it as a prime candidate for the large-scale energy storage applications. High efficiency, good flexibility, and fast dynamic response are the main requirements of the bidirectional energy storage converter. To meet these requirements, a theory system of integrated optimization and distributed control for the modular cascaded high-frequency AC linked bidirectional converter will be developed. A comprehensive modulation strategy will be developed by combining cascade multilevel and high-frequency AC linked converter, while the series-resonant high-frequency AC link has been proposed to be employed as module of cascaded converter, so that the switching loss can be reduced without changing the output harmonics. The three-phase cascaded system will be decoupled into three independent single-phase by optimal separation of zero-sequence component from current reference, which would help to increase the control flexibility of each phase, and the influence to the control target will be reduced. In addition, all modules of each-phase will be also fully decoupled by allocating the active and reactive power among the modules, which helps to increase the flexibility of the individual control. By applying the distributed control scheme, the active and reactive power control of the three-phase system can be converted to the voltage control of the individual module. Thus, the dynamic response and adaptive control ability of the system can be improved.

级联交流高频链具有高频隔离、中压并网等优点，适合于大功率大规模储能的应用场合。为满足储能对双向变流器高效、灵活和动态响应快的要求，本课题拟建立级联交流高频链双向变流器的模块化集成优化与分布式控制理论体系。课题研究交流高频链与级联多电平相结合的综合调制策略，并提出采用串联谐振交流高频链作为链节单元，以期在减小开关损耗的基础上保持输出谐波不变。课题拟结合最优指令电流零序分量分离的方法，将三相级联系统解耦为三个独立的单相系统以增加分相控制自由度，并尽可能减小对系统控制目标的影响。在分相控制的基础上，课题拟通过链节单元的功率分配，将单相链接解耦为独立的链节单元以增加分散控制自由度。通过采用基于分相和分散解耦的分布式控制，将三相级联系统的功率控制转换为单个链节单元的电压控制，从而提高了系统控制的动态响应速度和自适应控制能力。

级联交流高频链具有高频隔离、中压并网等优点，适合于大功率大规模储能的应用场合。为满足储能对双向变流器高效、灵活和动态响应快的要求，建立了级联交流高频链双向变流器的多模块耦合机理与分布式解耦控制理论体系。研究了级联交流高频链双向变流电路的控制方法；分析了交流高频链电路输出谐波特性，提出了级联交流高频链双向变流电路的综合调制策略，在减小开关损耗的基础上保持输出谐波不变；建立了电池故障下级联交流高频链双向变流电路的等效模型，分析了混合系统的稳定工作范围，提出了基于初始点设置的分散冗余控制方法，实现了链节间的功率分配；分析了三相级联交流高频链双向变流电路系统不对称故障下解耦控制条件，提出了基于电压源和电流源的分相解耦控制方法,提高系统控制的灵活度。通过采用基于分相和冗余的分布式解耦控制，实现了级联交流高频链系统的稳定高效安全运行。