一种风电场经柔性直流输电并网控制方法改进探讨

摘要

基于PSCAD仿真工具对通过柔性直流输电进行大型风电并网的问题进行了研究。建立了采用永磁同步电机的风电场等效聚合模型，分析了柔性直流输电的结构及控制改进方法，研究了在交流大电网互联和大型风电并网两种情况下的柔性直流输电系统响应。当风电场接入柔性直流输电系统时，输电系统对风电场产生一定的影响，使得风电场的输出波动通过电流内环的电压补偿项经过二次反馈给风电场，从而导致输出有功功率和无功功率的波动。为了解决风电场并网输出波动的问题，对柔性直流输电控制方案进行了改进。仿真结果显示在保持了系统优异故障穿越能力的同时，该改进方案能够有效地减小风电场的输出波动，增强了系统的稳定性。%The paper studies the large-scale wind power grid integration through VSC-HVDC (i.e. HVDC -Flexible defined in China) using the software tool PSCAD/EMTDC. It models a wind farm with a fully-aggregated Permanent Magnet Synchronous Generator,analyzes the VSC-HVDC system struc-ture and modified control strategy,and then studies the VSC-HVDC system responses under the situation of large-sized AC grids interconnection or large wind power connected to the grid. When connected to VSC-HVDC,the wind farm is affected by the power delivery system which feeds back the disturbance to wind farm itself via the voltage compensation of inner current control,leading to increasing fluctuations of active power and reactive power output. To solve this issue,this study makes some modifications to the control strategy of VSC-HVDC. The results show the modified control improves the system stability by reducing the wind farm output fluctuations and maintains the superb Fault Ride Through capability of VSC-HVDC at the same time.