Offshore Wind Farm Grid-formation Control Method for Connection of DR-HVDC System
郭文花 1沈顺群 2刘凯3
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作者信息
1. 山西铁道职业技术学院机电工程系,太原 030013
2. 国网湖北省电力有限公司神农架供电公司,神农架 442400
3. 武汉大学电气与自动化学院,武汉 430072
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摘要
基于二极管整流器的高压直流DR-HVDC(diode-rectifer-based high voltage direct current)输电系统是一种很有前景的海上风电低成本接入方案,它可将风能从偏远的海上风电场输送到陆上电力系统.然而随着海上DR-HVDC系统的不断增多,可能会导致风机WT(wind turbine)的变流器控制难度增大,系统稳定性变差.基于此,提出了一种适用于DR-HVDC连接海上WT变流器的新型电网形成控制方法.该方法采用2个正序控制回路来调节WTs的输出有功功率,并维持海上交流电网的频率和电压,其中第一个控制器可将每台WT的有功功率误差调节为电压角偏差,从而造成系统频率偏差;第二个控制器通过调整WT的交流电压幅值以抵消频率偏差.变流器内部电流控制回路用于限制故障电流,并消除系统中的高频谐振.最后,通过故障穿越、WT功率变化、无功扰动和WTs停机4个方面的电磁暂态仿真,验证了所提控制方法的有效性和优越性.
Abstract
The diode-rectifer-based high voltage direct current(DR-HVDC)system is a promising low-cost scheme for the connection of offshore wind power,which can deliver wind energy from remote offshore wind farms to onshore power systems.However,the increasing number of offshore DR-HVDC systems may lead to a growing difficulty in controlling wind turbine(WT)converters and a poor system stability.On this basis,a novel grid-formation control method for the connection of DR-HVDC to offshore WT converters is proposed.Two positive-sequence control loops are used to adjust the active power output from WTs and maintain the frequency and voltage of offshore AC grid,in which the first controller can adjust the active power error of each WT to the voltage angle deviation and thus cause frequency changes,and the second controller counteracts frequency changes by adjusting the AC voltage amplitude of WT.The converter's internal current control loop is used to limit the fault current and eliminate high-frequency resonance in the system.Finally,the effectiveness and superiority of the proposed control method are verified by electromagnetic transient simulations in terms of fault crossing,WT power change,reactive power disturbance and WTs shutdown.
关键词
海上风电场/二极管整流器/HVDC/变流器控制
Key words
Offshore wind farm/diode rectifier/HVDC/converter control
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