多源电力变换器与直流微网动态交互机理及控制研究

Multi-source Power Converter (MPC) can provide effcient power management over multiple sources and energy storages, and interact with dc micro-grids as the power source or storage. Due to the nonlinear and time varying nature of MPC system and the grid-tie electronic loads, undesired interactions exist among the input sources, as well as between the sources and the loads, which can be classified into three undesired phenomenons. 1. High output voltage ripple, 2. Cross-interference among input power stages, 3. Load side disturbance injection into the source side. This proposal treats the time varying nonlinear system as the multi-port networks, and conduct disturbance analysis of the interconnected sub-system on a system level. The outcome of this analysis will result s-domain closed-form expressions on dynamic interactions among state variables，as well as between control variables and state variables, which will reveal the principles of the dynamic interaction in such MPC-microgrid environment. With controllable steady state output voltage and power flow, the control algorithms are designed to suppress bus voltage dynamics due to the switching and load effects, to mitigate the channel cross-interference during dynamic power flow control; the final effort is applied to the integration of the individual control section into a structural form. The research proposal provides a theorectical basis of fast multi-variable switching-electronic system analysis and design, and sheds light on its further application in energy systems.

多源电力变换器（MPC）可以高效管理多种能源与储能装置，与直流微电网络进行能量交换。由于MPC与微网负载具有非线性时变特性，各输入源之间、负载与输入源之间均存在不良的动态交互，具体表现为：1.MPC输出电压扰动严重，2.动态功率潮流调节时各功率级相互干扰，3.负载扰动影响输入源。本项目采用非线性系统端口化的方法,在系统层面上研究互联的多变换器系统，以频域的解析形式描述多源电力变换器端口变量、控制变量的动态关联，分析多源电力变换器并入直流微网后变量之间的动态交互机理；同时，以稳态输出电压与功率潮流可控为约束条件，研究由开关输入效应与负载效应导致的输出电压扰动问题，动态功率潮流调节中的互扰问题，及其各控制功能的集成问题。本项目为快速多变量开关系统在能源领域的进一步研究与应用提供理论依据与设计思路。

针对多桥臂Buck/Boost型多端口变换器拓扑，提出了静态与动态的潮流调节控制结构。用开关平均法对多端口变换器进行了建模，在准电流控制模式下求解出输入通道之间互扰的传递函数并予以实验验证；设计了数字前馈网络用抑制各输入端口之间的不良交互。研究了输出电容上两倍网频扰动抑制的设计方法，利用多输入PWM载波移相的方法消除了微网直流母线高频纹波。最后利用分时与分频的方法对多端口变换器中不同时间尺度的电流环、电压环、光伏通道电压控制环、最大功率、载波移相闭环进行了集成。