永磁偏置型故障限流器对系统暂态稳定性的影响

Influence of Permanent-magnet-biased Saturation Based Fault Current Limiter on Transient Stability of Power System

永磁偏置型故障限流器(permanent-magnet-biased saturation based fault current limiter,PMFCL)的使用会对电力系统的暂态稳定性产生一定影响。为此,首先介绍了PMFCL的基本工作原理,并以单机无穷大系统为例,利用正序增广网络建立了含PMFCL的暂态稳定分析模型;其次基于发电机功角曲线和等面积法则,详细分析了在输电线路不同位置发生不同类型的短路故障时PMFCL限流电抗值以及故障切除时间对系统暂态稳定性的影响;最后通过时域仿真计算出发电机在不同短路故障类型下的输出功率最大值和功角变化曲线。结果表明:输电线路发生三相对称短路时,PMFCL限流电抗值越大则越有利于系统的暂态稳定性;线路中间部分发生单相接地故障时,限流电抗值越大则越不利于系统的暂态稳定性,此时可适当延长故障切除时间来改善系统的暂态稳定性;两相接地短路和两相短路故障下,PMFCL对系统暂态稳定性的影响规律基本一致。以上针对PMFCL对系统的暂态稳定性影响所开展的研究,为PMFCL的元件参数优化提供了参考,也为其实际应用提供了理论依据。

Application of permanent-magnet-biased saturation based fault current limiter （PMFCL） will influence the transient stability of power system to some extent. Therefore, we introduced the basic operation principle of PMFCL firstly. Then, taking single-machine infinite bus system as example, we built a transient analysis model containing one PMFCL in view of positive sequence augmented network. Secondly, based on power-angle curves of the generator and the equal area criterion, the influence of PMFCLs on the transient stability of the system was analyzed in detail when various types of short circuit faults occurred at different locations of the transmission line considering variation of the current-limiting reactance and the fault-clearing time. At last, the power-angle curves of the generator and the amplitude of its output power were calculated by time-domain simulation. The simulation shows that the bigger the current-limiting reactance of the PMFCL is, the more beneficial to the transient stability the system will be when the short circuit fault occurs symmetrically in three-phase transmission line. The bigger current-limiting reactance is less beneficial to the transient stability of the system when the short circuit fault occurs in the middle of the single-phase transmission line and the transient stability of the system can be improved by extending the fault-clearing time. The influence of the PMFCL on the transient stability of the system in two-phase grounding fault is the same as that in two-phase short-circuit. The study about the influence of PMFCL on power system＇s transient stability provides a reference for the parameter optimization design of PMFCL. The study also provides a theoretical basis for the practical application of PMFCL.