摘要
当电网发生不对称故障时,并网逆变器自身限流控制及支撑故障电网的能力决定了系统运行的可靠性。为解决该问题,首先,对三相四线制并网系统中瞬时功率关系进行分析,获得以功率波动抑制为目标的三相四桥臂逆变器进网电流各序分量的参考表达式。然后,通过与不同的电压跌落深度和功率因数进行对比,得出中线电流为最大相电流幅值的重要结论,并给出三相四桥臂逆变器能提供的最大有功和无功功率。在此基础上,提出了基于最大相电流约束和改进无功注入曲线的三相四桥臂逆变器不对称故障穿越策略,在满足并网逆变器自身安全情况下优先注入定量无功功率,从而实现了对故障电网电压的有效支撑。最后对传统方法及文中所提方法进行了对比仿真研究,结果验证了提出方法的可行性和有效性。
When asymmetrical fault occurs in distribution grid,peak current limitation of grid-connected inverters and their ability to inject sufficient reactive power to support fault grid determine reliability of the system.In order to solve this problem,firstly,the relationship between instantaneous active and reactive powers in three-phase four-wire grid-connected system is analyzed,and the reference expressions of sequence components of three-phase four-leg inverter for power oscillation suppression are obtained.Then,by comparing with different voltage drop depths and power factors,an important conclusion is obtained that neutral current is the maximum among phase currents,and the maximum active and reactive power injections are given.On this basis,an asymmetrical fault-ride-through strategy of three-phase four-leg inverter based on maximum phase current constraints and improvement of reactive power injection curve is proposed,which can ensure security of grid-connected inverter and give priority to injection of definitive reactive power,so as to achieve effective support to fault grid voltage.Finally,comparison between traditional methods and the method proposed in this paper is performed with PSCAD/EMTDC simulation,and results verify feasibility and validity of the proposed method.
作者
雷金勇
葛俊
谈赢杰
帅智康
胡洋
肖敏
LEI Jinyong;GE Jun;TAN Yingjie;SHUAI Zhikang;HU Yang;XIAO Min(Electric Power Research Institute,CSG,Guangzhou 510663,Guangdong Province,China;National Engineering Research Center for Power Conversion and Control(Hunan University),Changsha 410082,Hunan Province,China)
出处
《电网技术》
EI
CSCD
北大核心
2020年第3期944-952,共9页
Power System Technology
基金
南方电网公司科技项目(ZBKJXM20180211).
关键词
不对称故障
三相四桥臂逆变器
限流控制
改进无功注入曲线
电网电压支撑
功率波动抑制
asymmetrical grid fault
three-phase four-leg inverter
current limiting control
improved reactive power injection curve
grid voltage support
power oscillation suppression
