In view of imperfect performance of the existing low voltage ride through (LVRT) schemes especially the crowbar for the rotor during LVRT, we put forward an integrated LVRT strategy combining hardware and software for doubly-fed induction generator (DFIG). For the hardware part, stator series reactance (SSL) is used to reduce the rotor impact current, and a proper value-setting method of SSL is proposed by theoretically analyzing the mechanism of rotor current surge during the fault. For the software part, since the rotor side converter (RSC) is no longer deactivated, the original control scheme of RSC is modified to counteract the negative influence of the extended duration of DFIG electromagnetic torque oscillation caused by SSL, as well as adding an additional reactive power compensation to achieve the full potential of reactive power supply. The simulation results show that this integrated strategy can effectively suppress the peak value of rotor impact current, the electromagnetic torque oscillation amplitude and duration while providing reactive power to the grid by DFIG’s own capability. Therefore, the method proposed can not only guarantee the LVRT performance of DFIG, but also be conductive to the system transient stability.
KEY WORDS :doubly-fed induction generator;low voltage ride through;stator series reactance;reactive power compensation;transient stability;electromagnetic torque oscillation;
可见故障后的转子电流可表示为\({{L}_{\text{SSL}}}\)、t、urr的函数\(f\left( {{L}_{\text{SSL}}},t,u_{\text{r}}^{\text{r}} \right)\)。变流器采用空间矢量脉宽调制(SVPWM)方式,变流器输出电压的幅值上限为\({{{U}_{\text{dc}}}}/{\sqrt{3}}\;\)(\({{U}_{\text{dc}}}\)为直流母线电压),因此将式(9)中的$u_{\text{r}}^{\text{r}}\left( t \right)$替换为\({{{U}_{\text{dc}}}}/{\sqrt{3}}\;\);转子电流最大值出现在故障后1/2周期[21]左右,因此时间t取0.5T(T为同步周期)。将上述值带入式(9)后,可得转子电流峰值的表达式为
[1]
任永峰,孙伟,韩俊飞,等. 采用全钒液流电池储能的UDVR提升DFIG-LVRT能力研究[J]. ,2015,41(10):3185-3192.RENYongfeng, SUNWei, HANJunfei, et al.Improvements in DFIG-LVRT capability via UDVR based vanadium redox battery energy storage system[J]. , 2015, 41(10): 3185-3192.
[2]
袁铁江,董小顺,张增强,等. 基于氢储能技术的双馈风力发电系统基本架构及其建模[J]. ,2016,42(7):2100-2110.YUANTiejiang, DONGXiaoshun, ZHANGZengqiang, et al.Architecture and modeling of doubly-fed wind power generation system based on hydrogen energy storage technology[J]. , 2016, 42(7): 2100-2110.
[3]
风电场接入电网技术规定: Q/GDW392—2009[S],2009.Regulations on accessing power system technology to wind electric field: Q/GDW392—2009[S], 2009.
[4]
ZHUR, CHENZ, WUX, et al.Virtual damping flux-based LVRT control for DFIG-based wind turbine[J]. , 2015, 30(2): 1-12.
[5]
杨淑英,陈银,周天保,等. 低电压穿越过程中双馈风电机组虚拟电感暂态自灭磁控制[J]. ,2015,39(4):12-18.YANGShuying, CHENYin, ZHOUTianbao, et al.Virtual inductance based self-demagnetization control for doubly-fed induction generator wind turbines during low voltage ride-through process[J]. , 2015, 39(4): 12-18.
[6]
程鹏,年珩,诸自强. 电网对称故障时双馈电机虚拟电阻控制技术[J]. ,2014,18(6):1-8.CHENGPeng, NIANHeng, ZHUZiqiang.Control technique of DFIG based on virtual resistance under symmetrical grid fault[J]. , 2014, 18(6): 1-8.
[7]
赵宏博,汤海雁,张文亮,等. 双馈风电机组零电压穿越暂态特性分析及综合控制策略[J]. ,2016,40(5):1422-1430.ZHAOHongbo, TANGHaiyan, ZHANGWenliang, et al.Transient characteristics research and integrated control strategy of DFIG for zero voltage ride through[J]. , 2016, 40(5): 1422-1430.
[8]
张禄,金新民,唐芬,等. 电网电压对称跌落下的双馈感应发电机PI-R控制及改进[J]. ,2013,33(3):106-116.ZHANGLu, JINXinmin, TANGFen, et al.Improved PI-R control for doubly fed induction generators under grid voltages symmetrical dip[J]. , 2013, 33(3): 106-116.
[9]
周临原,刘进军,周恩展. 对称电网故障下双馈式风力发电系统去磁控制[J]. ,2014,38(12):3424-3430.ZHOULinyuan, LIUJinjun, ZHOUEnzhan.Demagnetization control for doubly-fed induction generator under balanced grid fault[J]. , 2014, 38(12): 3424-3430.
[10]
陈鉴庆,邹旭东,梁宗泽,等. 基于反向电流跟踪的双馈风机低电压穿越控制策略[J]. ,2016,31(2):221-229.CHENJianqing, ZOUXudong, LIANGZongze, et al.An improved control strategy of doubly-fed wind turbine under voltage dips based on reverse current tracking[J]. , 2016, 31(2): 221-229.
[11]
HUANGQ, ZOUX, ZHUD, et al.Scaled current tracking control for doubly fed induction generator to ride-through serious grid faults[J]. ,2016,31(3):2150-2165.
[12]
李啸骢,黄维,黄承喜,等. 基于crowbar保护的双馈风力发电机低电压控制策略研究[J]. ,2014,42(14):67-71.LIXiaocong, HUANGWei, HUANGChengxi, et al.Analysis of doubly-fed wind power generator low voltage control strategy based on crowbar protection[J]. , 2014, 42(14): 67-71.
[13]
谭伦农,王肖,陈武晖. 双馈风电机组不对称故障穿越性能优化[J]. ,2014,38(12):3502-3508.TANLunnong, WANGXiao, CHENWuhui.Optimation for capability of asymmetrical fault ride through of DFIG[J]. , 2014, 38(12): 3502-3508.
[14]
赵霞,王倩,邵彬,等. 双馈感应风力发电系统低电压穿越控制策略研究及其分析[J]. ,2015,43(16):57-64.ZHAOXia, WANGQian, SHAOBin, et al.Low voltage ride through control strategy and its analysis of doubly fed induction generator[J]. , 2015, 43(16): 57-64.
[15]
张曼,姜惠兰. 基于撬棒并联动态电阻的自适应双馈风力发电机低电压穿越[J]. ,2014,29(2):271-278.ZHANGMan, JIANGHuilan.Adaptive low voltage ride-through of doubly-fed induction generators based on crowbar with a parallel dynamic resistor[J]. , 2014, 29(2): 271-278.
[16]
任永峰,胡宏彬,薛宇,等. 基于卸荷电路和无功优先控制的永磁同步风力发电机组低电压穿越研究[J]. ,2016,42(1):11-18.RENYongfeng, HUHongbin, XUEYu, et al.Low voltage ride-through capability improvement of PMSG based on chopper circuit and reactive priority control[J]. , 2016, 42(1): 11-18.
[17]
李凤婷,陈伟伟,樊艳芳,等. 基于电压跌落程度及变阻值的DFIG低电压穿越综合策略[J]. ,2015,39(12):3408-3413.LIFengting, CHENWeiwei, FANYanfang, et al.A integrated control strategy for LVRT of DFIG based on voltage dip levels and dynamic resistance[J]. , 2015, 39(12): 3408-3413.
[18]
张琛,李征,蔡旭,等. 采用定子串联阻抗的双馈风电机组低电压主动穿越技术研究[J]. ,2015,35(12):2943-2951.ZHANGChen, LIZheng, CAIXu, et al.An active low voltage ride through strategy of DFIG-based wind turbine using stator series impedance[J]. , 2015, 35(12): 2943-2951.
[19]
张文娟,马浩淼,张国慨,等. 基于转子串联电阻的双馈风力发电机低电压穿越[J]. ,2015,35(12):28-33.ZHANGWenjuan, MAHaomiao, ZHANGGuokai, et al.Low voltage ride-through of doubly-fed induction generator based on rotor series resistor[J]. , 2015, 35(12): 28-33.
[20]
RAHIMIM, PARNIANIM.Coordinated control approaches for low-voltage ride-through enhancement in wind turbines with doubly fed induction generators[J]. , 2010, 25(3): 873-883.
[21]
徐殿国,王伟,陈宁. 基于撬棒保护的双馈电机风电场低电压穿越动态特性分析[J]. ,2010,30(22):29-36.XUDianguo, WANGWei, CHENNing.Dynamic characteristic analysis of doubly-fed induction generator low voltage ride-through based on crowbar protection[J]. , 2010, 30(22): 29-36.