含异步机负荷的虚拟同步机并联系统暂态电压稳定性分析及其提升措施研究  

Study on Transient Voltage Stability and Improvement Measures of Paralleled Virtual Synchronous Generators System With Induction Motors

作　　者：程慧婕 帅智康[1] 彭也伦 沈超 赵峰[1] CHENG Huijie;SHUAI Zhikang;PENG Yelun;SHEN Chao;ZHAO Feng(College of Electrical and Information Engineering,Hunan University,Changsha 410082,Hunan Province,China)

机构地区：[1]湖南大学电气与信息工程学院,湖南省长沙市410082

出　　处：《中国电机工程学报》2021年第14期4787-4798,共12页Proceedings of the CSEE

基　　金：国家自然科学基金面上项目(51977066)。

摘　　要：含异步机负荷的虚拟同步机并联系统在遭受严重故障后,存在暂态电压失稳问题,严重影响系统的安全稳定运行。该文揭示了并联系统暂态电压失稳机理,并对比分析了虚拟同步机无功环的3种控制模式对系统暂态电压稳定性的影响。分析表明,该并联系统发生对称短路故障时,虚拟机无功环的Q-V下垂和恒无功控制模式的动态特性恶化系统的暂态电压稳定性。且故障期间逆变器的内电势电压跌落程度越浅,系统暂态电压稳定性越高。在理论分析的基础上,提出一种考虑逆变器故障电流限制的系统暂态电压稳定性提升措施。该措施在保证逆变器输出电流不过流的前提下,提升了并联系统的暂态电压稳定性。此外,为定量分析系统的暂态电压稳定性,提出一种考虑无功控制环动态特性的临界故障清除时间计算方法。基于Matlab/Simulink的仿真结果验证了理论分析的准确性。A paralleled virtual synchronous generators(VSGs) system with induction motors can lose its transient voltage stability, when it is suffered from serious faults. That would seriously influence security and steady operation of the microgrid. This paper explored transient voltage instability mechanism of the system and analyzed the effects of three control modes of reactive power loop of VSGs on its transient voltage stability. The results showed that dynamic characteristics of Q-V droop and constant reactive power control modes of VSGs’ reactive power loop deteriorate transient voltage stability of the system, when symmetrical short circuit faults occur in the system. Moreover, a slighter internal voltage drop of inverters was beneficial to transient voltage stability of the system during the fault. Based on the theoretical analysis, an improvement method of transient voltage stability of the system was proposed when considering the limitation of inverter fault current. The method was to enhance the transient voltage stability of paralleled system without overcurrent produced by inverters. Moreover, in order to quantify transient voltage stability of the system, this paper proposed a calculation method for critical fault clearance time with considering the dynamic characteristics of reactive power control loop. The accuracy of theoretical analysis was validated by simulation results based on Matlab/Simulink.

关 键 词：虚拟同步机 暂态电压稳定性 异步电动机 无功控制环 临界故障清除时间 

分 类 号：TM712[电气工程—电力系统及自动化]