多VSC汇集变电站母线电压低频振荡机理分析与抑制  

Mechanism analysis and suppression of bus voltage low frequency oscillation of multi-VSC connected substation

作　　者：程亮 段彭洋 苏宏帮 马归圣 田生娟 代铮 CHENG Liang;DUAN Pengyang;SU Hongbang;MA Guisheng;TIAN Shengjuan;DAI Zheng(State Grid Qinghai Electric Power Company Service Center,Xining 810001,China)

机构地区：[1]国网青海省电力公司营销服务中心,青海西宁810001

出　　处：《电信科学》2024年第11期170-182,共13页Telecommunications Science

摘　　要：大型新能源场站选址偏远,多将其并入升压变电站并经长距离交流线路将电能送至负荷中心,造成升压站母线与负荷中心电气连接强度薄弱,易发生母线电压低频振荡。为揭示低频振荡的产生机理,建立了多电压源换流器(voltage source converter,VSC)并网系统的低频动态通用分析模型。该模型着眼于系统低频动态,对各VSC及交流电网独立建模,适用于在不同控制策略下的任意数量VSC并网建模。基于此模型,通过状态空间分析揭示了电网强度、VSC运行点,以及各VSC动态环节耦合等各因素对系统低频动态稳定性的影响机理。基于分析结果,提出虚拟公共并网点控制策略,该策略以汇集母线电压作为各VSC的统一控制目标,可有效抑制弱连接系统内各VSC的动态交互产生的低频振荡,并设计参数自整定功能以消除线路参数变化导致的误差。通过PSCAD/EMTDC仿真验证基于低频动态通用分析模型得出的各要素对低频动态影响结果的正确性,以及虚拟公共并网点控制策略对于低频振荡抑制的有效性。Large new energy stations are located in remote areas and integrate into boost substation,which is transmitted to load center through long-distance AC lines.This results in weak electrical connections between boost substation busbar and load center,and causes low-frequency oscillation instability.To reveal the mechanism of low-frequency oscillation,a universal model for low-frequency dynamic analysis of multi-VSC system was established.Focusing on low-frequency dynamics,each VSC and AC power grid were independently established,which is applicable to different quantities of grid-tied VSC with various control strategies.Based on the proposed model,the impact mechanism of various factors such as power grid strength,VSC operating point,and coupling interaction of various VSC’s dynamic loops on low-frequency stability of multi-VSC system were revealed by state space analysis.Based on the analysis results,a virtual point of common coupling control strategy was proposed,which takes the voltage of substation busbar as the unified control objective of each VSC.This strategy can effectively suppress the low-frequency oscillations caused by dynamic interaction of different VSC,and a parameter self-tuning function was designed to eliminate errors caused by variation of line parameters. Finally, the correctness of the impact of various elements on lowfrequencydynamics is verified through PSCAD/EMTDC simulation based on proposed model, as well as the effectivenessof proposed control strategy for low-frequency oscillation suppression.

关 键 词：多VSC系统 通用分析模型 动态环节交互 改进控制策略 低频振荡抑制 

分 类 号：TM73[电气工程—电力系统及自动化]