针对直流微电网的分布式直流DVR系统研究

The DC microgrid based on distributed power and hybrid energy storage system has been used widely in such applications as aero-Space, shipbord, data centers and renewable energy generation system, thanks to its flexile system configuration, high-efficiency and high reliability energy conversion. The stability of the bus voltage is the key point for the DC microgrid stability. This project will focus on a family of DC dynamic voltage regulator(DVR) with hybrid energy storage and DC bus voltage control functions, to achieve the charge or discharge management of the energy storage units and the fast , smooth and high-precision control of the bus voltage. Firstly, the mechanism classification of the flicker, fluctuations and ripple generation for the DC bus voltage will be revealed, and the corresponding suppression measures will be proposed. Secondly, a set of mutiple input and bidirectional DC/DC converter topologies, based on the minimal three-port power cells and minimal topology cells, will be built, then the principle of its power flow bidirectional operation mechanism will be derived. Thirdly, the optimal control method for energy management strategy is developed based on the fuzzy control theory, to fulfill the charge or discharge of the storage cells and the regulation of the DC bus voltage. In addtion to the output current sharing among the paralleled converter, the improved master-slave current sharing method are improved based on the ZigBee communication. Finally, the validity of the proposed topology family and the control method will be verified by the prototype. This research will provide the theoretical and practical basis for the further development fo DC microgrid.

基于分布式电源和混合储能系统的直流微电网系统具有架构灵活、变换效率和可靠性高等优点，已广泛应用于航天、舰船、数据中心和新能源发电等区域供电领域。维持直流微电网稳定运行的核心是保证直流母线电压稳定，本项目拟开展一种集混合储能和直流母线电压控制功能为一体的直流动态电压补偿器研究，实现对储能单元充、放电管理和母线电压的快速、平滑控制。首先，分类研究直流母线电压闪变、波动及纹波产生机理，提出相应的抑制措施。其次，在最小三端口功率单元和基本拓扑单元基础上，结合交错并联、磁集成技术，探索多输入双向DC/DC变换器拓扑的统一构成规律，揭示其功率流双向运行机理。然后，提出一种基于模糊控制理论，兼顾储能充、放电与直流母线电压调节协同控制的能量管理策略，发展一种基于ZigBee的改进型民主主从控制的均流方法。最后，搭建平台验证拓扑和控制方法的有效性。研究成果将为直流微电网系统进一步发展提供理论和工程应用基础。

本项目提出了一种可以实现多种低压电源输入或者负载输出的高增益型DC-DC储能变换器拓扑，提出了采用交直流并网逆变器进行较平缓有功功率波动控制，采用基于上述多低压输入/输出变换器（以下简称DC-DVR）的直流微网内电压谐波、闪变控制方法。难点是拓扑的大功率、高效实现，以及并网逆变器与微网内DC-DVR之间的无通讯线协调控制。采用了基于开关电容的交错并联和磁集成技术，解决DC-DVR大功率实现问题。为了进一步解决各储能单元电气隔离需要，本项目提出了一种可以实现多输入隔离的软开关MI-BDC拓扑，深入研究了拓扑谐振软开关与输入输出之间的关系，提出了基于移相控制+PWM控制的混合控制算法，从而有效提高了拓扑软开关范围及转换效率。为了解决超级电容输出电压波动大的问题，实现变换器系统全负载范围的高效率，增加了4相交错并联双向Buck/Boost变换单元，采用磁集成技术与脱相控制技术，实现了变换器高效高功率密度特性。在理论研究与仿真分析基础上，搭建了5kW直流DVR样机系统。该系统基于所提出的MI-BDC拓扑，集成了锂电池和超级电容储能装置，采用模糊控制进行能量管理，采用单周期电流控制实现变换器的可靠运行，最终实现了400V直流母线电压波动抑制。.取得的成果有：1)已建成智能直流配用电实验平台，该平台可满足验证直流微电网稳定控制技术、交直流相互支撑、能量管理、电能质量综合治理技术、故障快速保护技术及其它各种高级应用的需要。2)实验室研制了1KW单输入的DC-DVR样机，输入电压范围：24-48VDC，输出400VDC，最高转换效率96.4%。3)实验室研制了5kW三端口直流DVR样机，最高转换效率93%。4）提出了基于并网逆变器接口电路和DC-DVR的直流母线电压协调控制方法。本项目共发表SCI期刊论文4篇，EI期刊论文1篇；已授权发明专利2项，已申请发明专利2项；培养已毕业博士生1名，已毕业硕士生5名。..