基于电气转矩法的VSC-HVDC系统直流电压振荡稳定性评估  

DC-link Voltage Oscillation Stability Assessment of VSC-HVDC Systems Using Electrical Torque Method

作　　者：张旭[1] 郝治国[1] 李宇骏 李佳朋 杨松浩 梁天宇 ZHANG Xu;HAO Zhiguo;LI Yujun;LI Jiapeng;YANG Songhao;LIANG Tianyu(School of Electrical Engineering,Xi’an Jiaotong University,Xi’an 710049,Shaanxi Province,China)

机构地区：[1]西安交通大学电气工程学院,陕西省西安市710049

出　　处：《电网技术》2024年第10期4306-4316,共11页Power System Technology

基　　金：国家重点研发计划项目(2022YFB2402705);国家电网公司科技项目(52272222001J)。

摘　　要：文章采用电气转矩法分析了VSC-HVDC系统的直流电压振荡稳定性。首先,基于电压源型换流器的平均值模型,分别研究了基于功率控制的换流器及基于电压控制的换流器的动态响应特征以得到适用于电气转矩法的并网换流器模型。基于提出的评估模型,建立了双端VSC-HVDC系统的Phillips-Heffron模型并推导出系统的阻尼系数和同步系数。经典电气转矩法指出:电力系统稳定性与系统阻尼系数高度相关。因此,基于电气转矩法推导出的稳定条件揭示了系统直流电压振荡失稳机理,量化了直流网络动态及换流器控制动态对直流电压振荡稳定性的影响。当由基于电压控制的换流器及直流网络提供的正阻尼无法抵消由基于功率控制的换流器产生的负阻尼时,系统直流电压振荡稳定性将无法得到保证。此外,合理设置电压控制器的比例增益能够使系统获得足够的稳定裕度。最后,通过仿真验证了电气转矩法在分析VSC-HVDC系统直流电压振荡稳定性问题时的可行性及所得稳定条件的正确性。This paper investigates the DC-link voltage oscillation stability of voltage sourced converter(VSC)based high voltage direct current(HVDC)system using electrical torque method.Firstly,the dynamics of power-controlled converter and voltage-controlled converter are fully explored based on the averaged value model to obtain the model suitable for electrical torque method.Then,the Phillips-Heffron model of a two-terminal VSC-HVDC system is constructed.Based on the proposed model,the damping and synchronizing coefficient are obtained.Since it is indicated by electrical torque method that the system stability is mainly related to the damping coefficient.Accordingly,the stabilizing conditions based on electrical torque method can be derived,revealing the DC-link voltage oscillation instability mechanism and quantifying the impacts of DC grid and DC controller dynamics on system stability.The DC-link voltage oscillation stability can no more be guaranteed once the positive damping provided by DC grids and voltage-controlled converter fails to offset the negative damping generated by power-controlled converter.In addition,reasonable setting of proportional gain of DC-link voltage control can ensure sufficient stability margins under various operating conditions.Finally,the feasibility of electrical torque method in analyzing the DC-link voltage oscillation stability of power-electronics-based power systems and the correctness of the proposed stabilizing conditions are verified by numerical simulation in professional software.

关 键 词：直流电压振荡稳定性 电气转矩法 阻尼系数 Philips-Heffron模型 稳定裕度 

分 类 号：TM721[电气工程—电力系统及自动化]