基于全过程仿真的城市电网中长期电压稳定轨迹特征及防控策略研究
发布时间：2018-09-11 20:29
【摘要】：随着我国大规模超/特高压交直流互联电网的快速发展,各种电力系统新设备和新技术不断投产和应用,系统的动态行为变得更加复杂,这使得发生在暂态过程之后的中长期动态稳定问题日趋突出并逐步受到电力系统研究人员的高度重视。发电机过励磁限制器和有载调压变压器等慢速动态元件的动态特性是影响大容量高比例受电城市电网中长期动态稳定水平的关键因素。构建适用于中长期动态过程的稳定判据及安全稳定控制措施以防止城市电网电压崩溃就显得尤为重要。本文基于北京市电力公司科技项目“北京电网全过程动态稳定及对策研究”,以环状分区运行的特大型城市电网为研究对象,分析了中长期过程中慢动态元件动作对系统运行点在系统动态PV曲线上的迁移特征及主要电气量的影响。研究过程中把负荷功率随负荷端电压和系统频率变化而改变的负荷特性现象进行了分析,分别研究了静态负荷模型和动态负荷模型负荷特性对中长期电压稳定的影响,揭示了过励磁限制和有载调压动作引起系统中长期电压失稳机理,并在此基础上定义了中长期动态稳定控制判据及裕度计算方法,提出了相应的多手段改善中长期稳定水平的控制策略。最后通过对北京电网的全过程动态仿真分析验证了稳定判据及控制策略的有效性。本文所做工作及得出的主要结论如下:1)研究了采用的不同负荷模型对仿真的影响,受端系统在慢动作元件动作时受不同负荷模型影响有不同形态的迁移轨迹。包含有阻抗和马达负荷的综合动态负荷模型系统在慢动作元件动作时的运行点迁移特性满足同阻抗-马达负荷所占比例相关的线型叠加原理,经过仿真分析验证马达负荷所占比例越大运行点迁移轨迹曲线斜率越大。2)全过程动态仿真中慢动作元件动作后系统稳定与否同状态迁移后系统运行点所在迁移后PV曲线上的位置直接相关。以发生状态迁移后的PV曲线极限功率点B所对应的迁移前系统运行点A作为中长期动态稳定的临界点,能够确保慢动元件动作导致的运行点迁移过程后系统运行点能够继续稳定运行于迁移后PV曲线。3)快速响应切负荷措施对慢动元件如过励限制和有载调压引起的系统中长期稳定性问题都有良好的优化效果。切负荷措施的及时响应是确保策略有效的关键。及时响应的切负荷动作能够保证系统运行点在慢元件动作之前回复到稳定临界点以内,进而防止因运行点迁移至动作后PV曲线失稳区而引发的电压崩溃。在仿真过程中证实了恒阻抗模型和马达模型均在有载调压动态中表现出了明显的负调压特性。因而在系统重载、动态无功支撑不足以及运行点接近稳定临界点时闭锁有载调压可以有效防止受端电压崩溃。
[Abstract]:With the rapid development of large-scale ultra-high voltage / ultra-high voltage AC / DC interconnected power grid in China, the dynamic behavior of the system becomes more and more complex, with the continuous production and application of new equipment and new technologies in various power systems. This makes the long-term dynamic stability problem after the transient process become more and more prominent and gradually received great attention by the power system researchers. The dynamic characteristics of low-speed dynamic components such as generator over-excitation limiter and on-load voltage regulating transformer are the key factors that affect the long-term dynamic stability of large capacity and high proportion of urban power grid. It is very important to construct the stability criterion and safety and stability control measures to prevent the voltage collapse of urban power network. Based on the scientific and technological project of Beijing Electric Power Company, "dynamic Stability and Countermeasures of Beijing Power Grid", this paper takes the super-large urban power grid running in the ring zone as the research object. The effects of slow dynamic component movement on the migration characteristics and main electrical quantities of the system running point on the dynamic PV curve of the system are analyzed in the medium and long term process. In the course of the study, the load characteristics of load power varying with load terminal voltage and system frequency are analyzed, and the effects of static load model and dynamic load model on medium and long-term voltage stability are studied respectively. The mechanism of medium and long term voltage instability caused by over-excitation limitation and on-load voltage regulation operation is revealed. On this basis, the medium and long-term dynamic stability control criterion and margin calculation method are defined. The control strategy of multi-means to improve the level of medium-long-term stability is put forward. Finally, the effectiveness of stability criterion and control strategy is verified by dynamic simulation of Beijing power grid. The main conclusions of this paper are as follows: 1) the effects of different load models on simulation are studied. The moving characteristic of the running point of the integrated dynamic load model system with impedance and motor load satisfies the linear superposition principle related to the ratio of impedance to motor load. The simulation results show that the larger the proportion of motor load, the bigger the slope of the moving trajectory curve. 2) in the whole process dynamic simulation, whether the system is stable or not after the slow motion element moves is the same as the system running point after the moving state. The position on the PV curve is directly related. The system operating point A corresponding to the limit power point B of the PV curve after the state transition is taken as the critical point for long-term dynamic stability. It can ensure that the system running point can continue to run stably in the PV curve 3 after the slow moving element moves.) the system can respond quickly to the system caused by the slow moving element such as over-excitation restriction and load voltage regulation. The medium-and long-term stability of the system has a good optimization effect. The timely response of load cutting measures is the key to ensure the effectiveness of the strategy. The timely response load shedding action can ensure that the operating point of the system returns to the stable critical point before the slow component action, and then prevents the voltage collapse caused by the point moving to the unstable zone of the PV curve after the operation. In the process of simulation, it is proved that both the constant impedance model and the motor model have obvious negative voltage regulation characteristics in the on-load voltage regulation dynamic. Therefore, when the system is overloaded, the dynamic reactive support is insufficient and the operation point is close to the stable critical point, the latch load voltage regulation can effectively prevent the terminal voltage from collapsing.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727.2;TM712
[Abstract]:With the rapid development of large-scale ultra-high voltage / ultra-high voltage AC / DC interconnected power grid in China, the dynamic behavior of the system becomes more and more complex, with the continuous production and application of new equipment and new technologies in various power systems. This makes the long-term dynamic stability problem after the transient process become more and more prominent and gradually received great attention by the power system researchers. The dynamic characteristics of low-speed dynamic components such as generator over-excitation limiter and on-load voltage regulating transformer are the key factors that affect the long-term dynamic stability of large capacity and high proportion of urban power grid. It is very important to construct the stability criterion and safety and stability control measures to prevent the voltage collapse of urban power network. Based on the scientific and technological project of Beijing Electric Power Company, "dynamic Stability and Countermeasures of Beijing Power Grid", this paper takes the super-large urban power grid running in the ring zone as the research object. The effects of slow dynamic component movement on the migration characteristics and main electrical quantities of the system running point on the dynamic PV curve of the system are analyzed in the medium and long term process. In the course of the study, the load characteristics of load power varying with load terminal voltage and system frequency are analyzed, and the effects of static load model and dynamic load model on medium and long-term voltage stability are studied respectively. The mechanism of medium and long term voltage instability caused by over-excitation limitation and on-load voltage regulation operation is revealed. On this basis, the medium and long-term dynamic stability control criterion and margin calculation method are defined. The control strategy of multi-means to improve the level of medium-long-term stability is put forward. Finally, the effectiveness of stability criterion and control strategy is verified by dynamic simulation of Beijing power grid. The main conclusions of this paper are as follows: 1) the effects of different load models on simulation are studied. The moving characteristic of the running point of the integrated dynamic load model system with impedance and motor load satisfies the linear superposition principle related to the ratio of impedance to motor load. The simulation results show that the larger the proportion of motor load, the bigger the slope of the moving trajectory curve. 2) in the whole process dynamic simulation, whether the system is stable or not after the slow motion element moves is the same as the system running point after the moving state. The position on the PV curve is directly related. The system operating point A corresponding to the limit power point B of the PV curve after the state transition is taken as the critical point for long-term dynamic stability. It can ensure that the system running point can continue to run stably in the PV curve 3 after the slow moving element moves.) the system can respond quickly to the system caused by the slow moving element such as over-excitation restriction and load voltage regulation. The medium-and long-term stability of the system has a good optimization effect. The timely response of load cutting measures is the key to ensure the effectiveness of the strategy. The timely response load shedding action can ensure that the operating point of the system returns to the stable critical point before the slow component action, and then prevents the voltage collapse caused by the point moving to the unstable zone of the PV curve after the operation. In the process of simulation, it is proved that both the constant impedance model and the motor model have obvious negative voltage regulation characteristics in the on-load voltage regulation dynamic. Therefore, when the system is overloaded, the dynamic reactive support is insufficient and the operation point is close to the stable critical point, the latch load voltage regulation can effectively prevent the terminal voltage from collapsing.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM727.2;TM712
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相关期刊论文 前10条
1 王晶;李卫星;李志民;孙勇;;计及发电机动态的多端口网络等值及中长期电压稳定监视[J];中国电机工程学报;2015年18期
2 宋玮;刘桂林;吴国e，
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