水电机组经高压直流外送系统建模及多频段振荡模态分析  

Modeling and Multi-frequency Oscillation Mode Analysis of Hydropower Unit Integration Through HVDC System

作　　者：杜夏冰 郭春义 赵成勇 徐李清 张加卿 DU Xiabing;GUO Chunyi;ZHAO Chengyong;XU Liqing;ZHANG Jiaqing(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Beijing 102206,China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京市102206

出　　处：《电力系统自动化》2022年第4期75-83,共9页Automation of Electric Power Systems

基　　金：国家自然科学基金面上项目(51877077)。

摘　　要：随着电网不断扩大与发展,电力系统出现了水电经高压直流输电系统外送的结构,为保障电网的安全稳定运行,有必要探索该系统是否存在多频段振荡风险。首先,文中建立了水电机组和高压直流输电2个系统的独立模型,并推导了其接口动态方程,进而建立了全系统状态空间模型,并验证了模型的正确性。在此模型基础上,采用特征根分析法对系统进行多频段振荡模态特征识别和影响分析。分析结果表明,外送系统存在超低频、低频、次同步振荡模态。其中,超低频振荡模态除了与水电机组调速器强相关以外,还与整流站定电流控制器弱相关,在高比例水电出力的场景易发生超低频振荡;低频振荡模态与锁相环强相关,锁相环控制参数在合理范围内变化,不会激发系统低频振荡模态;水电机组和高压直流输电系统间电气和多控制环节共同影响次同步振荡模态,当受端电网强度弱时,系统次同步振荡模态被激发,调整励磁增益和整流站/逆变站控制参数可以改善模态阻尼。With the continuous expansion and development of the power grid, the structure of hydropower unit integration through the high voltage direct current(HVDC) transmission system appears in the power grid. In order to ensure the safe and stable operation of the power grid, it is necessary to explore whether the system has the risk of multi-frequency oscillation. First, the independent models of the hydropower unit and the HVDC system are established and the interface dynamic equation is deduced.Then, the state space model of the whole system is established and the correctness of the model is verified. Based on this model,the eigenvalue analysis method is adopted to identify the multi-frequency oscillation mode characteristics of the system and analyze the influence. The analysis results show that the integration system has ultra-low frequency, low frequency and sub-synchronous oscillation modes. The ultra-low frequency oscillation modes are not only strongly related to the hydropower unit governor, but also weakly related to the constant current controller of the rectifier station. The ultra-low frequency oscillation is prone to occur in the scenario of high proportion of hydropower unit. The low frequency oscillation modes are related to the phase-locked loop(PLL), which will not be excited if the PLL control parameters change within a reasonable range. The sub-synchronous oscillation modes are affected by multiple electrical and control links between the hydropower unit and the HVDC system. When the grid strength is weak at the receiving end, one of the sub-synchronous oscillation modes is excited. The modal damping can be improved by adjusting the excitation gain and the control parameters of the rectifier/inverter station.

关 键 词：水电机组 高压直流输电 接口模型 多频段振荡 模态识别与分析 

分 类 号：TV734[水利工程—水利水电工程]