摘要
针对海上风电场经多端柔性直流电网提供频率支撑的功率安全分配问题以及二次频率跌落问题,提出了风电场与换流站协同频率支撑控制策略及风机预设恢复策略。协同控制包括换流站和风电场两个层面。换流站层面,采用功率电压下垂控制,引入功率裕度因子修正自适应下垂系数,实现对风电场提供频率支撑功率在换流站间的合理分配以避免过载;海上风电场层面,风机首先在频率支撑阶段通过释放转子动能以提供惯量和一次调频支撑,提升频率最低点,其次对风机提供频率支撑后的转速恢复阶段,提出了衔接频率支撑阶段输出功率的预设恢复策略,并探究了不同加速曲线与二次频率跌落间的关系,缓解功率缺额导致的二次频率跌落问题。所提控制策略相对现有方法能提升频率最低点并缓解二次频率跌落问题,同时保证换流站的安全运行。以三区四端的海上风电场经柔直并网系统验证了提出控制策略的有效性。
In order to solve the problem in safe allocation of frequency support power from voltage source converter-based multi-terminal high-voltage direct current(VSC-MTDC)connected offshore wind farms(OWFs)and secondary frequency drop problem,this paper proposes a coordinated frequency support and wind turbine preset restoration scheme.The control scheme contains the onshore VSC stations’level and the offshore wind turbines’level.For onshore VSC stations,power-voltage droop control is adopted,and the power margin index is used to modify the adaptive droop coefficient to ensure reasonable power allocation and avoid the over-load accidents.For offshore wind turbine level,firstly,each wind turbine provides the inertial and primary frequency support by releasing the kinetic energy on frequency support stage to improve the frequency nadir.Secondly,to alleviate the secondary frequency drop problem of the restoration stage,this paper proposes a preset curve method and investigates the relationship between the different accelerating curves and secondary frequency drop.Compared with existing control schemes,the proposed control scheme can improve frequency nadir and reduce secondary frequency drop based on the safe operation of VSC stations.The proposed control scheme has been tested on a 3-area 4-terminal VSC-MTDC based offshore wind farms.The simulation results can verify the effectiveness of the proposed control scheme.
作者
姚雅涵
姚伟
熊永新
张靖
文劲宇
YAO Yahan;YAO Wei;XIONG Yongxin;ZHANG Jing;WEN Jinyu(State Key Laboratory of Advanced Electromagnetic Engineering and Technology,School of Electrical and Electronics Engineering,Huazhong University of Science and Technology,Wuhan 430074,China;Electrical Engineering College,Guizhou University,Guiyang 550025,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2021年第10期3537-3547,共11页
High Voltage Engineering
基金
国家自然科学基金(52022035)。
