摘要
电网电压跌落引起双馈感应风电机组(double fed induction generator,DFIG)定子电压跌落,造成DFIG定子磁链振荡,从而引起定、转子产生较大的振荡电流,特别是对双脉冲宽度调制(pulse width modulation,PWM)变换器产生极大的危害。若不采取有效的低电压穿越(low voltage ride through,LVRT)控制措施,将会导致DFIG从电网解列,危及电力系统安全运行。提出一种直流侧的低电压穿越技术,通过在DFIG背靠背变流器直流母线电容上加装超级电容储能系统,利用其功率密度大、充电时间短、使用寿命长、温度特性好等特点,来进行短时大功率充放电,在电网电压跌落、直流侧电压波动期间,将能量储存在超级电容中,同时也可以释放多余的能量补偿直流侧电压,从而有效地提升DFIG低电压故障的耐受能力,实现DFIG的低电压穿越。建立了3 MW风力发电机仿真模型,根据相应的计算原则确定配置7.65 F的超级电容器,当电压跌落50%且故障时间一直持续,超级电容可以控制机组维持稳定运行15 s,验证了超级电容提高风电机组低电压穿越能力的有效性。
The drop of grid voltage can cause the stator voltage of double fed induction wind generator（ DFIG） to drop rapidly,which can make the DFIG＇s stator flux vibrate and cause a large oscillating current in DFIG＇s rotor and stator side,especially to the dual pulse width modulation（ PWM） converter. If we don＇t take an effective low voltage ride-through（ LVRT）control measure,the DFIG may be disconnected from grid which will endanger the safe operation of the power system. This paper presents the DC-side LVRT technology,which installs super capacitor energy storage system on the DC bus capacitor in DFIG back to back converters,and uses its characteristics of high power density,short charging time,long service life and good temperature characteristic to realize short-term high-power charging and discharging; in the period of grid voltage drop and the DC voltage fluctuation,store the energy in the super capacitor,meanwhile can release excess energy to compensate DC voltage,thus can effectively enhance the low voltage fault tolerance of DFIG,and achieve the LVRT of DFIG. Through establishing 3 MW wind turbine simulation model,we determine and configure 7. 65 F super capacitor according to the corresponding calculation principles. When the voltage drops 50% and the failure time continues,the super capacitor can maintain stable operation 15 s. The result verifies the effectiveness of super capacitor improving the LVRT capability of wind turbines.
出处
《电力建设》
北大核心
2016年第8期84-89,共6页
Electric Power Construction
基金
国家电网公司科技项目(KY-SG-2016-204-JLDKY)
