调速系统引发低频振荡的机理及抑制措施研究

发布时间：2018-06-23 13:24

本文选题：汽轮机调速系统 + 低频振荡　；参考：《华北电力大学》2014年硕士论文

【摘要】：低频振荡严重影响电网运行的安全与稳定性,根据负阻尼机理设计的电力系统稳定器(PSS)能够对低频振荡起到有效的抑制作用。然而一些电网即使加装了PSS仍会出现功率振荡现象,理论及实际表明原动机及其调节系统波动也会引发电力系统低频振荡。近年来,数字电液控制系统(DEH)的投入使汽轮机及其控制系统对低频振荡的影响更加显著。 2011年,南方电网某发电厂汽轮机组进行一次调频试验时引起机组低频功率振荡,并导致500kV电网多条联络线发生低频功率振荡告警,严重影响了电网稳定运行。根据电厂振荡时的实际运行情况,建立了锅炉、汽轮机、发电机、励磁系统和调速系统的数学模型,引入了调速系统的上位控制系统——单元机组负荷控制系统(CCS).,在热工控制模型的基础上建立了适于电力系统动态分析的简化CCS模型。根据所建立模型在PSCAD/EMTDC仿真软件中搭建了仿真平台并实现了低频振荡事件的重现。对汽轮机调速系统的运行原理、控制方式以及各部分组成做出了详尽的分析介绍。根据研究需要对系统模型进行了合理简化,建立了电力系统结构框图,利用阻尼转矩法对不同控制方式下的调速系统阻尼特性进行了分析,指出调速系统参数设置不当会引发电网功率振荡。根据电网运行要求,通过分析计算给出了保证系统稳定运行的调速系统参数取值范围。调速系统作为一次调频机构不仅会影响系统的动态稳定性,还会影响系统的频率特性,研究表明过于追求一次调频性能会破坏系统动态稳定。探讨了电力系统一次调频性能与电网动态稳定性的协调优化问题,采用新型的智能优化算法对汽轮机及其调速系统参数进行了优化,在保证一次调频性能的同时保证了电网的动态稳定性,时域仿真证明了结果的准确性。
[Abstract]:The low frequency oscillation seriously affects the safety and stability of the power network operation. The power system stabilizer (PSS) designed according to the negative damping mechanism can effectively suppress the low frequency oscillation. However, even if PSS is installed in some power networks, power oscillation will still occur. The theory and practice show that the fluctuation of prime mover and its regulating system will also cause low frequency oscillation of power system. In recent years, the input of Digital Electro-hydraulic Control system (DEH) has made the influence of steam turbine and its control system on low frequency oscillation more remarkable. During the primary frequency modulation test of steam turbine unit in a power plant of Southern Power Grid, the low frequency power oscillation of the unit is caused, and the alarm of low frequency power oscillation occurs in many tie lines of 500 kV power network, which seriously affects the stable operation of the power network. The mathematical models of boiler, steam turbine, generator, excitation system and speed regulating system are established according to the actual operation of power plant oscillation. The load control system of unit (CCS) is introduced in this paper. Based on the thermal control model, a simplified CCS model suitable for dynamic analysis of power system is established. According to the established model, a simulation platform is built in the PSCAD / EMTDC simulation software and the low frequency oscillation events are reproduced. The operation principle, control mode and composition of turbine speed regulating system are analyzed and introduced in detail. According to the need of the research, the system model is reasonably simplified, the power system structure block diagram is established, and the damping characteristics of the speed regulating system under different control modes are analyzed by using the damping torque method. It is pointed out that improper setting of parameters of speed regulating system will cause power oscillation in power grid. According to the operation requirements of the power system, the range of the parameters of the speed regulating system to ensure the stable operation of the system is given through analysis and calculation. As a primary frequency modulation mechanism, the speed regulation system will not only affect the dynamic stability of the system, but also affect the frequency characteristics of the system. The research shows that the pursuit of primary frequency modulation performance will destroy the dynamic stability of the system. This paper discusses the coordination optimization between the primary frequency modulation performance of power system and the dynamic stability of power network. The parameters of steam turbine and its governing system are optimized by a new intelligent optimization algorithm. The performance of primary frequency modulation is guaranteed and the dynamic stability of power network is guaranteed. The accuracy of the result is proved by time domain simulation.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM712

【参考文献】