SVG对海上风电交流并网系统稳定性影响分析

海上风电交流并网系统具有不同于陆上风电并网系统的结构和运行特点，其动态无功补偿装置(SVG)通常配置在陆上集控站而不是风电场出口，主要工作于补偿交流电缆充电无功的感性区，需要研究SVG对系统振荡特性的影响。针对某直驱型海上风电交流并网系统，基于系统特征模式分析，构建对比算例，研究了SVG容量配置、运行状态及其控制对系统主导振荡模式稳定性的影响。经研究发现，当SVG工作于感性区时，海上风电交流并网系统主导振荡模式稳定性明显弱于SVG工作于容性区。另一方面，SVG电流内环和功率外环控制参数可能导致海上风电并网系统主导振荡模式失稳，需要确定能适应系统运行方式变化的参数取值范围并与风电场控制参数协调以保持系统稳定。基于PSCAD/EMTDC的系统详细电磁暂态仿真验证了所得结论。研究工作对于认识海上风电交流并网系统特性和指导系统规划和优化运行具有较好的参考价值。

Analysis on the influence of an SVG on the stability of AC grid-connected offshore wind farms

An offshore wind power AC grid-connected system has a different structure and operational characteristics from an onshore system. The dynamic var compensation device (SVG) is usually located at onshore centralized control station instead of the wind farm outlet, and generally operates in an inductive state compensating the charging reactive power of the AC cable. In this case, it is necessary to study the impact of the SVG on the oscillation characteristics of the system. In this paper, a practical direct-drive offshore wind power AC grid-connected system is selected as a case study. Based on eigenvalue analysis, some comparative cases are constructed to study the impact of SVG capacity, operational region as well as its control on the stability of the dominant oscillation mode. It is found that the stability of the dominant subsynchronous oscillation mode is significantly weaker when SVG is working in an inductive state compared with SVG working in a capacitive state. In addition, current inner control and power outer control parameters of the SVG could lead to instability in the dominant oscillation mode. The control parameter design of a SVG should be adapted to system operation and coordinated with the control of the wind turbine generator for stable operation. A detailed electromagnetic transient simulation based on PSCAD/EMTDC validates the results. The study would be beneficial to understanding the characteristics of an offshore wind farm AC grid-connected system as well as guiding system planning and optimal operation. This work is supported by the Research and Development Plan in Key Areas of Guangdong Province (No. 2021B0101230004).