高渗透率新能源发电并网变流器跟网/构网型稳定控制技术综述与展望

Review and Prospect of Stability Control Techniques for Grid-following/Grid-forming Con-verters in High-penetration Renewable Energy Generation

随着以光伏和风电为代表的新能源渗透率不断提升,电网的特性愈发复杂,传统单一模式跟网型和构网型变流器无法完全满足电网的需求。因此,一方面,高渗透率条件下,局部电网的阻抗波动更加显著,电网表现出强弱交替变化的特点,现有并网变流器稳定控制应用存在局限性,如何将两种控制模式结合,使得变流器能够兼顾经济性和稳定性是研究热点;另一方面,现有并网变流器控制难以适应复杂电网特性的非线性变化。高渗透率条件下,受到新能源间歇性、电网故障导致设备/支路切除等因素的影响,电网结构/参数呈现非线性变化。为此,探索非线性控制在跟、构网变流器中的应用,使得变流器在复杂电网状况下能够具有更强的稳定性。综上,该文在构网型和跟网型单一控制的基础上,综述了几类结合跟、构网两种模式优点的控制方式,涉及单机双模式切换控制、单机双模式融合控制以及多机场站混合模式控制。然后,进一步阐述如何改进现有并网变流器控制,使其能够适应复杂电网特性的非线性变化。最后,对未来变流器控制技术进行了展望。

As the penetration rate of renewable energy sources(represented by photovoltaic and wind power)continues to increase,the characteristics of the power grid become increasingly complex.Traditional single-mode grid-following and grid-forming converters cannot fully meet the needs of power grids.Consequently,on one hand,under high penetration conditions,the problem of significant fluctuations in the impedance of local grids becomes more pronounced,exhibiting characteristics of strong to weak variations.The existing stability control of grid-connected converters still has application limitations.How to combine both control modes to ensure that the converters could compromise both economy and sta-bility is a research hotspot.On the other hand,the control of existing grid-connected inverters is hard to adapt to the nonlinear changes in the complex grid characteristics.Under high penetration conditions,influenced by the intermittency of renewable energy sources and grid faults leading to equipment or grid branch disconnections,the structure or parame-ters of the grid exhibit nonlinear changes.Therefore,exploring the application of nonlinear control in grid-following and grid-forming inverters to enhance their stability under complex grid conditions is of significant importance.In summary,we reviews several control methods that combine the advantages of both grid-following and grid-forming modes,based on the single-mode control of grid-forming and grid-following converters.These methods include single-converter du-al-mode switching control,single-converter dual-mode integrated control,and multi-converters station hybrid mode control.Furthermore,this paper elaborates how to improve the existing control of grid-connected inverters to adapt to the nonlinear changes in complex grid characteristics.Finally,we provide an outlook on future control technologies of converters.