交直流混合微电网稳定运行控制

发布时间：2018-06-03 05:21

本文选题：交直流混合微电网 + 直流母线电压控制　；参考：《天津大学》2014年博士论文

【摘要】：交直流混合微电网中同时含有交流和直流母线，，可充分接纳不同类型分布式电源及储能系统，利用较少的能量变换装置分别满足直流和交流负荷需求，整个系统具备较高的能量转换效率、经济性和可靠性。稳定运行控制一直是微电网领域内的研究热点，本文围绕交直流混合微电网稳定控制的相关技术进行深入细致的研究，主要工作如下：（1）针对基于公共直流母线的分布式电源供电系统，研究了基于双向DC-AC变流器和基于双向DC-DC变流器的两种直流母线电压控制方式，提出诸如基于功率平衡及一阶微分环节相结合的改进电压环前馈补偿方法，DC-AC电流环死区补偿及DC-DC电流环稳态占空比补偿等解决措施。理论分析和实验结果均表明所提方法能有效抑制大扰动下直流母线电压冲击和波动，保证暂态时分布式电源供电系统功率动态平衡。（2）探讨了交直流混合微电网中直流母线电压控制问题，提出了基于非线性干扰观测器的直流母线电压控制方法。此外本文还详细分析了直流线路阻抗、直流母线电容量变化及直流侧DC-DC控制系统对所提出的直流母线控制方法的影响。理论分析和实验结果表明非线性干扰观测器的应用不仅能有效抑制暂态直流母线电压冲击，还可避免直流微电网中分布式电源的DC-DC控制系统和交直流微电网接口DC-AC控制系统间的高速通信，有利于直流微电网内分布式电源的扩展和即插即用。（3）为减小微电网并网与独立运行模式快速切换过程对微电网内分布式电源及重要负荷的暂态冲击，本文提出一种实现微电网两种运行模式平滑切换的主逆变电源控制策略。该策略包含主电源变流器控制状态平滑切换补偿算法和切换控制逻辑。理论分析和实验结果表明，该方法可以有效抑制切换过程中出现过压或过流现象，实现微电网运行状态的平滑过渡。（4）利用特征值理论深入分析和研究了主从控制模式下微电网独立运行时的稳定性问题。比较基于连续时间状态方程和离散时间状态方程两种建模方法对微电网稳定性分析的影响；分析了导致系统出现高频振荡失稳的主要影响因素；提出在主电源电压环电压反馈通道中加入基于二阶通用积分器的带通滤波器，能有效改善微电网的稳定性。
[Abstract]:The AC / DC hybrid microgrid contains both AC and DC bus, which can fully accept different types of distributed power generation and energy storage system, and use less energy conversion devices to meet the demand of DC and AC load, respectively. The whole system has high energy conversion efficiency, economy and reliability. Stable operation control has always been a research hotspot in the field of microgrid. This paper focuses on the related technologies of AC / DC hybrid microgrid stability control. The main work is as follows: 1) aiming at the distributed power supply system based on common DC bus, this paper studies two kinds of DC bus voltage control methods based on bidirectional DC-AC converter and bidirectional DC-DC converter. For example, an improved voltage loop feedforward compensation method based on power balance and first-order differential link is proposed to compensate DC-AC current loop dead-time and DC-DC current loop steady-state duty cycle compensation. The theoretical analysis and experimental results show that the proposed method can effectively suppress the DC bus voltage impulse and fluctuation under large disturbance and ensure the dynamic balance of power in the distributed power supply system during transient. 2) the DC bus voltage control problem in AC / DC hybrid microgrid is discussed, and a DC bus voltage control method based on nonlinear disturbance observer is proposed. In addition, the influence of DC line impedance, DC busbar capacitance change and DC side DC-DC control system on the proposed DC bus control method is analyzed in detail. The theoretical analysis and experimental results show that the nonlinear disturbance observer can not only effectively suppress the transient DC bus voltage impulse, It can also avoid the high speed communication between the DC-DC control system of distributed generation in DC microgrid and the DC-AC control system of AC / DC microgrid interface, which is beneficial to the expansion and plug and play of distributed generation in DC microgrid. 3) in order to reduce the transient impact of the fast switching process of microgrid grid-connected and independent operation mode on distributed generation and important load in microgrid, this paper proposes a main inverter power supply control strategy to realize smooth switching between two operation modes of microgrid. The strategy includes the control state smooth switching compensation algorithm and switching control logic of the main power converter. Theoretical analysis and experimental results show that this method can effectively suppress overvoltage or overcurrent in the switching process and realize smooth transition of the operation state of microgrid. 4) the stability of microgrid under master-slave control mode is analyzed and studied by using eigenvalue theory. The influence of two modeling methods based on continuous time state equation and discrete time state equation on the stability analysis of microgrid is compared, and the main influencing factors that lead to the instability of high frequency oscillation in the system are analyzed. A bandpass filter based on the second order general integrator is proposed to improve the stability of the microgrid in the main supply voltage loop voltage feedback channel.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM732

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