基于构网型风电机组和二极管整流单元的海上风电场黑启动策略

Black Start Strategy of Offshore Wind Farm Based on Grid-forming Wind Turbines and Diode Rectifier Unit

基于构网型风电机组和二极管整流单元(diode rectifier unit,DRU)的中远距离海上风电送出方案具有技术经济性优势。由于DRU必须在交流电压支撑下才能工作,并且其功率传输具有单向性,因此DRU或陆上电网均无法启动海上风电场。在这种情况下,构网型风电机组可以作为海上风电场的黑启动电源。首先,介绍了2种构网型海上风电经DRU送出系统的拓扑。接着,阐明了构网型风电机组的结构和控制策略,分析了风电机组并网启动时的自同步过程。然后,研究了海上交流系统的无功功率平衡,提出了避免风电机组启动时无功功率过载的措施,在此基础上提出了海上风电场黑启动策略。最后,在PSCAD/EMTDC中搭建了中频构网型海上风电直流送出系统和低频构网型海上风电交流送出系统的电磁暂态仿真模型,对海上风电场黑启动过程进行仿真,风电场平稳启动的仿真结果验证了所提基于构网型风电机组的黑启动策略的有效性。

The medium-and long-distance offshore wind farm integration scheme based on grid-forming wind turbines(WTs)and the diode rectifier unit(DRU)has technical and economic advantages.Since the DRU must be supported by AC voltage and its power transmission is unidirectional,neither the DRU nor the onshore grid can start the offshore wind farms.In this case,the grid-forming WT can become the black start source for the offshore wind farm.Firstly,the topologies of two DRU-based offshore wind power integration systems are introduced.Secondly,the structure and control strategy of the grid-forming WT are elaborated,and the self-synchronization during the WT start process is analyzed.Then,the reactive power balance of offshore AC system is studied,and the measures to avoid reactive power overload when WTs starts are proposed.On this basis,the black start strategy of offshore wind farms is proposed.Finally,electromagnetic transient simulation models of the DC transmission scheme for medium-frequency grid-forming offshore wind power and the AC transmission scheme for low-frequency grid-forming offshore wind power are established in PSCAD/EMTDC to simulate the black start process of the DRU-based offshore wind farm.The simulation results verify the effectiveness of the proposed black start strategy based on the grid-forming WT.