直流微电网协调控制及其稳定性研究

DC microgrid which has the advantages of high reliability, high efficiency and easy to control has been becoming the main power supply of the future home and building. How to coordinate the DC microgrid's work modes between multiple units of distributed power generation and the energy storage device, achieving the bus voltage stability and power balance are the key issues of DC microgrid, the relationships between the bus voltage and the power of DC microgrid is analyzed in the applying project, the hierarchical control strategy has been proposed , which combines the hierarchical control and DC bus signal(DBS) control to achieve stable operation of the microgrid.the microgrid power control in grid mode and optimal control of distributed generation in island mode is achieved in this control strategy. On this basis, applying project researches the DC microgrid small signal stability problems. By the analysis of the relationship between the output impedance of each inverter and the different control methods each power generation interface convert, According to the Nyquist stability criterion derives total output impedance and circuit parameters about the DC microgrid stability of the law, to provide important reference for DC microgrid parameters design. Finally, a small DC microgrid has been established, through the design and commissioning of photovoltaic, wind power and energy storage. The correctness of the control strategy proposed is verified.

直流微电网以其可靠性高、效率高、便于控制等优点成为未来家庭和楼宇的主要供电架构。如何协调直流微电网中多个分布式发电单元、储能装置的工作方式，实现母线电压稳定和微电网功率平衡是直流微电网需要解决的关键问题。拟申请项目分析了母线电压和微电网功率之间的关系，提出了直流微电网的层次控制策略，将分层控制与直流母线信号控制（DC Bus Signaling, DBS）相结合，实现微电网并网时的功率控制和孤岛时分布式发电单元的优化控制，最终实现微电网的稳定运行。在此基础上，拟申请项目对该控制策略下的直流微电网小信号稳定性进行了研究，分析了各变换器输出阻抗之间的关系以及不同控制策略对变换器阻抗的影响，依据奈奎斯特稳定判据得出微源总输出阻抗和线路参数对直流微电网稳定性影响的规律，为直流微电网的参数设计提供参考依据。最后建立一个小型直流微电网，对风光及储能装置的协调控制及稳定性分析进行验证。

直流微电网以其可控性强、可靠性高等优点成为未来住宅和楼宇的主要供电架构，通常由并网变换器、分布式电源、恒功率负载及储能装置等组成，他们之间的协调控制及并联后的稳定性是直流微电网可靠运行的基础。针对传统控制策略的局限性，提出直流微电网层次化优化控制策略和一种阻性虚拟阻抗加补偿虚拟阻抗的改进下垂控制策略，实现微源的即插即用，提高直流微电网的可靠性及响应速度，解决传统电压-功率下垂控制无法降低负载低频功率扰动影响的问题。针对直流微电网中双向变换器采用阻抗比判据无法区分源、负载特性的问题，提出小信号并联阻抗分析方法，该方法分析了滤波参数对直流微电网小信号稳定性的影响规律，并利用一端口稳定性分析方法分析了直流微电网的系统稳定性；通过建立直流微电网分布式控制策略下的统一数学模型，采用李雅普诺夫直接法研究了直流微电网大信号稳定性的参数边界条件，并根据切换理论分析了模式切换对直流微电网稳定性的影响，为直流微电网的系统级设计提供了重要的参考依据。