基于本地测量的微网逆变器离/并网功率精确和统一控制

在包含多微源的微网系统中,微源逆变器输出功率的精确控制和离/并网运行模式下控制目标的自动切换对于微网电压和频率的稳定以及潮流的控制都具有重要意义。在下垂控制的基础上,提出了基于本地测量的自适应双虚拟阻抗和功率补偿导纳控制方法,消除了不同类型线路阻抗引起的功率耦合,改善了离网时负载分配的准确性。同时,通过提出一种自适应的电压补偿方法,实现了分布式电源离/并网运行的统一控制,并改善了离网时的电能质量和并网时输出功率的跟踪精度。通过建立离/并网模式下逆变器的小信号模型,对控制器参数进行了优化设计。仿真和实验结果验证了理论分析的正确性和所提出的控制方法的有效性。

Accurate Power Control and Unified Control of Converters for Microgrid Based on Local Measurement

In a microgrid with multi-microsources, precise output power control and seamless transition of micro-source converters between grid-connected and islanding operation modes are of great significance for the stability of voltage and frequency and the power flow control in a microgrid. The control method of adaptive dual virtual impedances and power compensation conductance based on local voltage and current measurement is proposed, by which active and reactive power control for voltage source inverters (VSIs) can be decoupled and the VSIs can share loads proportionally to their capacity in the islanding mode. Meanwhile, a voltage compensation mechanism is embedded in the droop control, which can refine the power quality in the islanding mode, power control quality in the grid-connected mode, and realize unified control of the microgrid. Furthermore, the parameters of the proposed controller are optimized with small signal models in both grid-connected and islanding modes. Simulation and experiment results have verified the proposed control method. This work is supported by National Basic Research Program of China (973 Program) (No. 2009CB219708), National Natural Science Foundation of China (No. 51077033) and Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) of China (No. 201301111110005).