基于虚拟同步发电机的微电网并网预同步研究

A Pre-Synchronization Method for Micro-grids Based on Virtual Synchronous Generators

针对多台虚拟同步发电机组成的微电网并网问题,提出了一种并网预同步控制方法。基于频率调节器、电压调节器和相位调节器的预同步单元对每台虚拟同步发电机进行控制,能使并网前微电网母线侧和电网侧电压幅值、频率和相位一致,减小微电网并网瞬间冲击电流的同时实现多台虚拟同步发电机的有功功率分配。理论分析验证了所提出的预同步方法对电网电压有很好的跟踪效果,仿真验证了其有效性。

To improve the voltage and frequency in micro-grid, the virtual synchronous generator control strategy was proposed for inverter control, which can emulate the behavior of synchronous generator, decrease rate of change of frequency and provide dynamic power support to grid. However,when virtual synchronous generators based micro-grids switch from islanded mode to grid-connected mode, inrush current may deteriorate the power quality of micro-grids. For this reason, a new pre-synchronization method for grid-connection of virtual synchronous generators based micro-grids was proposed. What＇ s more, the design of pre-synehronization unit was analyzed in detail. The pre-synchronization unit includes a frequency regulator, a voltage magnitude regulator and a phase regulator. By adding synchronization unit to each inverter respectively, micro-grid voltage can synchronize with grid voltage through the adjustment of inverters before connecting to the grid, and no inrush current is generated during pre- synchronization. The theory analysis and simulation resuhs show the validity of the proposed method.