弱连接下并网VSC外环控制稳定性分析  

Stability Analysis of Power Control Outer Loop of Grid-connected VSC Under Weak Connection Conditions

作　　者：任必兴 孙蓉 李强 甘德强[3] 周前 汪成根 REN Bixing;SUN Rong;LI Qiang;GAN Deqiang;ZHOU Qian;WANG Chenggen(State Grid Jiangsu Electric Power Company Ltd.Research Institute,Nanjing 211103,China;State Grid Jiangsu Electric Power Company Ltd.,Nanjing 210024,China;College of Electrical Engineering,Zhejiang University,Hangzhou 310027,China)

机构地区：[1]国网江苏省电力有限公司电力科学研究院,南京211103 [2]国网江苏省电力有限公司,南京210024 [3]浙江大学电气工程学院,杭州310027

出　　处：《高电压技术》2022年第2期762-771,共10页High Voltage Engineering

基　　金：国网江苏省电力有限公司科技项目(多电力电子变流器接入江苏电网引发宽频振荡风险评估及优化控制策略研究)(J2020129)。

摘　　要：近年来,关于弱连接下并网电压源型换流器(voltage source converter,VSC)造成的电力系统振荡稳定性问题的研究大多集中于锁相环(phase locked loop,PLL)环节,对于不考虑PLL动态作用的VSC外环控制系统稳定性的研究相对较少。为了研究这一环节的稳定特性及影响因素,建立了考虑直流电压控制环节及无功功率控制环节的VSC外环线性化模型。基于劳斯-赫尔维茨判据,得到了弱连接条件下并网VSC外环控制系统的稳定性指标,通过算例仿真验证了所推导的稳定指标的正确性,并分析得出了影响VSC外环控制系统振荡稳定性的关键因素及对应变化规律。研究结果表明:当不考虑PLL的动态作用时,主要影响弱连接条件下并网VSC稳定性的环节为VSC功率控制外环,且直流电压外环控制参数对并网VSC稳定性影响显著,而无功功率外环控制参数对并网VSC稳定性的影响相对较小;同时,VSC连接电网强度越弱,系统发生不稳定振荡的风险越大。In recent years,most existing researches on power system oscillation stability problems caused by grid-connected voltage source converters(VSC)under weak connections have focused on the link of phase locked loop(PLL),and the researches on the stability of the VSC outer loop control system that does not consider the dynamic effect of the PLL are rarely available.In order to study the stability characteristics and affecting factors of this link,this paper establishes a VSC outer loop linearization model in which the DC voltage control link and the reactive power control link are taken into consideration.Based on the Rouss-Herwitz criterion,the stability criterion of the outer loop control model of the grid-connected VSC under the weak connection condition is obtained,and the correctness of the stability criterion derived is verified by the simulation in case study.And then,the key factors affecting the stability and changing rules are analyzed.The research results show that when the dynamic effect of PLL is not considered,the main link that affects the stability of the grid-connected VSC under weak connection conditions is the VSC power control outer loop.The DC voltage outer loop control parameters have a significant impact on the stability of the grid-connected VSC,and the reactive power outer loop control parameters have a relatively small impact on the stability of the grid-connected VSC;at the same time,the more weakly the VSC is connected to the grid,the greater the risk of unstable oscillations in the system will be.

关 键 词：并网VSC系统 外环控制 弱连接 稳定性分析 直流电压控制 

分 类 号：TM721.1[电气工程—电力系统及自动化]