大型光伏电站接入多机系统暂态电压稳定性研究

STABILITY RESEARCH OFTRANSIENT VOLTAGE FOR MULTI-MACHINE POWER SYSTEMS INTEGRATED LARGE-SCALE PV POWER PLANT

以一个集中式光伏电站接入IEEE 14节点系统为例,运用时域仿真法对含大规模光伏多机电力系统的暂态电压稳定性进行详细分析。除感应电动机外,光伏逆变器的动态特性以及光伏电站的运行模式也是影响系统暂态电压稳定性的重要因素。在系统负荷较轻时发生短路故障或系统发生断线故障时,较小的光伏逆变器响应时间常数有利于系统恢复暂态电压稳定;系统重载时光伏采用PV模式比PQ模式更有利于维持暂态电压稳定性。当光伏采用PQ模式运行,若系统重载,则会使短路故障极限切除时间大大减小,而在较大的光伏有功出力下断线故障易造成电压崩溃现象。安装动态无功补偿装置STATCOM可有效提高含光伏多机系统在重载时的暂态电压稳定性。

Taking the IEEE 14-bus system integrated with a centralized PV(photovolatic)power plant as an example,the transient voltage stability of multi-machine power systems with large-scale PV plant is analyzed in detail using thetime-domain simulation method. The simulation results show that besides the induction motor, the dynamiccharacteristics of PV inverter and operational mode of PV power plant are also important factors that can influence thetransient voltage stability of the system. When short circuit fault at light load or line disconnection fault happen,thesmaller response time constant of PV inverter is beneficial to restore the transient voltage stability of the system. PVsystem with heavy load adopting PV mode will be more beneficial to maintain the transient voltage stability than PQmode. When PV power plant with heavy load operates in PQ mode,the short-circuit fault limit cut-off time is greatlyreduced,and the disconnection fault is likely to cause a voltage collapse phenomenon under a large PV active output.The installation of dynamic reactive power compensation device STATCOM can effectively improve the transient voltagestability of multi-machine systems with PV under heavy load.