微电网并网理论的前提

Precondition of the gridding theory for a microgrid

随着微电源容量的增加以及微电网运行的可靠性日益增强,越来越多的分布式电源已经接入到大电网中,这样不可避免地会给大电网造成冲击。如何减小微电网并网切换时对大电网造成的影响,使其能够由孤岛模式平滑切换到并网运行模式成为重要的研究课题之一,尤其是对并网时刻的选取亟需从实际和理论两方面进行综合分析。笔者首先从理论上分析了微电网并网运行时所需满足的条件,并且以V/f控制方式的微电网为研究对象,建立了微电网模型。通过Simulink仿真软件对单机带负荷微电网进行并网仿真,论证理论的正确性,最终确定使微电网实现平滑切换的最优条件。

Along with the increase in capacity of the power grid and the improvement in operation reliability, more distributed powers have been accessed to the power grid, which will inevitably pose impact to the big net. So how to reduce the impact of a microgrid on the big net and then to achieve a smooth transition from the island mode to the parallel operation mode is an important research topic. It needs comprehensive analyses from practical and theoretical ways especially for the selection of grid time. Filstly, this paper theoretically analyzes the condition of microgrid parallel operation, and a microgrid model is established taking a microgid with a V/f control mode as a study object. Then a grid simulation on the micropower of a single generator with loads is carried out, which proves the conecaaess of the model. Finally, the optimal conditions are determined which can make the microgdd realize a smooth Iransition.