【作者】 张剑；

【导师】 肖湘宁；

【作者基本信息】 华北电力大学 ， 电力系统及其自动化， 2014， 博士

【摘要】 次同步振荡是电力系统稳定问题之一。随着世界各国电力系统的发展,特别是我国高电压、大容量、长距离交直流输电的不断建设和规模化可再生能源的并网发电,由传统次同步振荡带来的新问题以及新的次同步振荡现象相继出现,这给电力系统稳定性研究又带来了新的挑战,本文围绕电力系统中出现的两种新的次同步振荡问题—间歇式次同步振荡(Intermittent Subsynchronous Oscillation, ISSO)和次同步控制互作用(Subsynchronous Control Interaction, SSCI)开展了如下研究：大型火电机组集群经高压直流输电线路与交流混合串联补偿线路送出时可能引起频繁超越发电机轴系累积阈值的收敛型次同步振荡问题,本文称为间歇式次同步振荡SSCI。通过对比其与传统HVDC引起的次同步扭振相互作用的不同特性,本文详细分析了间歇式次同步振荡产生的根本原因和作用路径；基于经直流送出的单机无穷大系统,提出了一种确定电气阻尼对间歇式次同步振荡作用路径中各电参量敏感度的方法,由此可确定最敏感的扰动因素；紧密结合我国蒙东呼盟系统多年来存在和困扰的间歇式次同步振荡问题,搭建了该系统的5厂10机等效电磁暂态仿真模型,采用测试信号法分析了系统的电气阻尼特性,并基于上述分析确定的最敏感因素,提出了一种与实际振荡特性一致的间歇式次同步振荡的仿真模拟方法,这为所研发的抑制装置的阻尼特性仿真和实验验证提供了可行的仿真手段。近年来的研究表明,含有双馈感应发电机的风力发电厂经固定串补线路远距离送出时会出现次同步控制互作用SSCI,可能引起风电机组的严重损坏。本文基于双馈感应风力发电机经固定串联补偿送出的单机无穷大系统,通过数学建模详细分析了次同步控制互作用产生的根本原因和作用路径,给出了发生次同步控制互作用的近似条件,提出了一种区分风机中可能出现的感应发电机效应和次同步控制互作用的方法；采用时域仿真法分析了风机风速、线路串补度以及双馈风机转子侧变流器控制器参数对次同步控制互作用的影响；基于其作用路径和相关控制器参数对振荡的影响分析,提出了抑制次同步控制互作用的阻断方法和附加阻尼方法,并对其有效性进行了时域仿真验证。基于并联电压源型换流器的拓扑结构,本文提出一种采用次同步振荡动态稳定器(Subsynchronous Oscillation-Dynamic Stabilizer, SSO-DS)抑制次同步振荡的方法,并基于此提出一种无功电流次同步调制策略。详细介绍了这种控制策略的具体控制流程,并采用复转矩系数法详细推导了其能够提供的近似电气阻尼,分析了影响该阻尼正负和大小的相关因素。针对SSO-DS这种新的抑制装置,基于IEEE第一标准模型中由固定串补引发的次同步谐振问题,通过测试信号法和时域仿真法验证了所提出控制策略的有效性。针对实际呼盟系统交直流并列输电方式和呼贝电厂存在的间歇式次同步振荡问题,分别提出了宽带通和窄带通SSDC的阻尼控制方法,详细分析了二者抑制间歇式次同步振荡的可行性。通过数学推导和仿真,对比分析了附加励磁阻尼控制器-SEDC与SSO-DS装置的响应时间以及阻尼转矩提供能力上的不同,对比分析了基于SVC拓扑结构的次同步谐振动态稳定器(Subsynchronous Resonance-Dynamic Stabilizer, SSR-DS)与SSO-DS抑制次同步振荡的阻尼能力,最后通过时域仿真法对比了SEDC、SSR-DS与SSO-DS阻尼间歇式次同步振荡的效果。在以上理论与方法研究的基础上,综合考虑了响应速度、抑制效果以及占地面积等多方面因素后,本文建议呼贝电厂采用SSO-DS的方法,并为装置的测试搭建了实时数字—物理闭环仿真实验平台。介绍了仿真平台的结构和各部分的功能,提出了一种模拟转速传感器的方法用于转速测量卡与转速处理卡的闭环接入。利用该实时仿真环境,通过SSO-DS的输入输出特性测试验证了控制器设计的准确性；针对呼贝电厂间歇式次同步振荡问题,提出了一种测量SSO-DS有效阻尼区域的方法,并通过多个工况下的测试对控制器参数进行优化,最后通过时域仿真法验证了SSO-DS解决呼贝电厂次同步振荡问题的有效性。目前,合作研制的SSO-DS装置已用于呼贝电厂解决多年来困扰的次同步振荡问题,并已具有较好的抑制效果。更多还原

【Abstract】 Subsynchronous oscillation is one of the power system stability problems. With the development of power system in the world, especially the continuous construction of high voltage, large capacity and long distant ac/dc transmission and the scale of renewable energies connected to the grid for generating in China have caused new subsynchronous oscillation problems. New subsynchronous oscillation phenomena emerged in succession, which challenge the research on power system stability. The thesis focuses on two types of new emerging subsynchronous oscillation problems, intermittent subsynchronous oscillation (ISSO) and subsynchronous control interaction (SSCI) and carries out the research as follows:When large scales of thermal power plants deliver their power by HVDC and ac hybrid series compensated transmission lines, the converging subsynchronous oscillation may happen, which frequently exceeds fatigue accumulation threshold value of the generator shafts. It is called intermittent subsynchronous oscillation in the thesis. Compared with the characteristics of conventional subsynchronous torsional interaction caused by HVDC, the thesis analyzes the root cause leading to ISSO and the ISSO path in detail. Based on single-machine infinite bus system connected with HVDC, a method analyzing electrical damping sensitivity with respect of electrical parameters in ISSO path is proposed, by which the most sensitive position can be determined. According to the actual ISSO problem existing in Hulunbuir League power system in the east of Inner Mongolia, the equivalent electromagnetic transient simulation model is built, which has5power plants in total including10generators. The test signal method is used to analyze the electrical damping characteristics of the system. According to the most sensitive position by analysis above, a disturbance simulation method is proposed which can stimulate similar ISSO with the actual case and provide feasible simulation method for damping characteristics simulation of mitigation device and experimental verification.The research in recent years indicates that subsynchronous control interaction may happen when a wind power plant including DFIG-based wind-power generators deliver its power by fixed series compensated long distant transmission lines. It may lead to the damage of wind-power generators. In the thesis, the mechanism and interaction path of SSCI is analyzed by math modeling based on a single machine infinite bus system where a DFIG-based wind-power generator is connected to the fixed series compensated transmission lines. And an approximate condition used to determine the existence of SSCI is given. A method used to distinguish induction generator effect (IGE) and SSCI of DFIG is proposed. The effects of wind speeds, series compensation levels and the parameters of rotor side converter controller on the characteristics of SSCI are analyzed by time domain simulation method. According to the analysis of SSCI path and the influence of the controller parameters on SSCI, the interdicting method and the supplementary damping method are proposed to mitigate SSCI and their effectiveness is verified by time domain simulation.Based on the topology of voltage sourced converter in parallel, the method using subsynchronous oscillation-dynamic stabilizer (SSO-DS) to mitigate SSO is proposed in the thesis. And based on SSO-DS, the control strategy of reactive current modulated by subsynchronous signals is proposed. The concrete control process of this control strategy is introduced in detail. And the damping provided by the control strategy is deduced by complex torque coefficient approach and the related influence factors on the direction and size of the damping are analyzed. Based on IEEE first benchmark model where there may be a subsynchronous resonance caused by fixed series compensation, the availability of this new mitigation device called SSO-DS with proposed control strategy is verified by test signal and time domain simulation methods.According to ISSO which exists in Hulunbuir League power system with ac and dc transmission, especially in Hulunbuir power plant, a wide band-pass SSDC damping method and a narrow band-pass SSDC damping method are proposed and their feasibilities for ISSO mitigation are analyzed. By math deduction and simulation, SEDC and SSO-DS are compared in the differences of response time and the ability of providing damping torque. SSO-DS is also compared with subsynchronous resonance-dynamic stabilizer (SSR-DS) based on the topology of SVC in damping ability by analysis and simulation. And time domain simulation method is used to compare the ISSO damping effect among SEDC, SSR-DS and SSO-DS.Based on the theories and methods above and considering response speed, mitigation effect, the floor space limit of the power plant and so on, SSO-DS is recommended to be used in Hulunbuir power plant for ISSO mitigation. In order to test its controller, the real-time digital and physical closed-loop simulation platform is built in this thesis. The structure of the platform and the function of every part are introduced. A method is proposed to interface the real-time digital simulator with the rotating speed acquisition panel by simulating the real rotating speed sensor. By means of the real-time simulating environment, input and output characteristics of SSO-DS test is done to verify the correction of its controller design. A testing method is proposed to measure effective damping area in multi operating conditions for ISSO mitigation and as a result, the parameters of SSO-DS controller can be optimized. Finally, time domain simulation is used to verify the effectiveness for SSO-DS to solve the problems of Hulunbuir power plant. Now SSO-DS device developed by cooperation has been used to solve the problem which has been bothering Hulunbuir power plant for many years, and have had good mitigation effect.更多还原