用于电力系统稳定分析的同步发电机数学模型研究
发布时间：2018-08-19 13:48
【摘要】：同步发电机在扰动后的动态运行能力对于系统安全稳定运行具有重要意义。本文建立了用于研究扰动条件下发电机运行能力的时步有限元模型,研究了汽轮发电机转子复杂阻尼结构及其材料特性对系统稳定性的影响,并与电力系统仿真分析所用的发电机三种实用模型的计算结果进行了对比研究。在此基础上,以时步有限元结果作为标准响应,辨识了发电机大扰动过程中的电机参数。主要成果如下： 1.建立了用于分析汽轮发电机转子三部分阻尼结构和阻尼材料特性对其动态运行能力影响的时步有限元模型,对该模型的时空离散策略进行了优化和改进,使其能够更加准确的计及多因素非线性条件下转子阻尼结构中的涡流集肤效应,并通过模型机试验验证了该模型的准确性。 2.以一台300MW汽轮发电机为例,通过详细的时步有限元计算分析,揭示了汽轮发电机转子大齿导条、转子铁心和转子导电槽楔等阻尼结构与发电机第一摆稳定性之间的关系,发现转子阻尼结构对第一摆稳定极限的影响主要取决于其等效电阻；进一步对转子槽楔采用不同材料时发电机的第一摆稳定性进行研究,揭示了第一摆稳定极限随转子槽楔电导率的变化规律。 3.揭示了实用模型两种假设条件的物理本质,假设A模型计及了励磁绕组和阻尼绕组的互漏磁链,忽略了阻尼绕组自漏磁链；假设B模型反之；在假设B模型的基础上进一步对阻尼相关项进行简化得到了假设B-1模型。在此基础上,对比分析了时步有限元模型与三种实用模型所计算的大扰动和小扰动结果,得出不同模型仿真结果之问的差异。 4.将解析法和数值仿真相结合研究了实用模型中定子绕组电磁暂态对发电机机电暂态过程的影响,发现忽略定子绕组暂态后,发电机三相突然短路过程中的交变电磁转矩分量和定子非周期电流产生的单向电磁转矩分量均被忽略,而后者属于制动性质的转矩,被忽略后会影响功角第一摆稳定性的仿真精度。 5.以时步有限元结果作为目标曲线,采用最小二乘法辨识了发电机大扰动过程中的电机参数,揭示了这些参数随发电机功角的变化规律,得出辨识参数计算结果的精度明显高于厂家参数。同时,对转子导电槽楔采用不同材料时的发电机参数进行辨识,得出转子槽楔电导率对发电机各参数的影响。研究结果为实用模型的进一步改进提供了理论支撑。
[Abstract]:The dynamic operation ability of synchronous generator after disturbance is of great significance to the safe and stable operation of the system. In this paper, a time-step finite element model is established for the study of generator operating capacity under disturbance conditions. The influence of complex damping structure and material characteristics of turbogenerator rotor on the stability of the system is studied. The results are compared with the results of three practical models used in power system simulation. On this basis, the parameters of the generator in the process of large disturbance are identified by using the time-step finite element results as the standard response. The main results are as follows: 1. A time-step finite element model is established to analyze the influence of three-part damping structure and damping material characteristics on the dynamic performance of turbogenerator rotor. The spatio-temporal discretization strategy of the model is optimized and improved. The skin effect of eddy current in rotor damping structure can be taken into account more accurately, and the veracity of the model is verified by the model machine test. 2. Taking a 300MW turbogenerator as an example, through detailed time-step finite element calculation and analysis, the relationship between the damping structure of the turbine generator rotor, such as the large tooth guide bar, the rotor core and the rotor conductive slot wedge, and the first pendulum stability of the generator is revealed. It is found that the influence of rotor damping structure on the stability limit of the first pendulum mainly depends on its equivalent resistance. It is revealed that the stability limit of the first pendulum varies with the conductivity of the rotor slot wedge. The physical nature of the two hypothetical conditions of the practical model is revealed. Model A assumes the mutual flux leakage between the excitation winding and the damping winding and neglects the self-leakage flux chain of the damping winding. On the basis of hypothesis B model, the damping correlation term is further simplified and the hypothesis B-1 model is obtained. On this basis, the results of large and small disturbances calculated by time step finite element model and three practical models are compared and analyzed, and the differences between the simulation results of different models are obtained. 4. The influence of electromagnetic transient of stator winding on electromechanical transient process of generator is studied by combining analytical method and numerical simulation. It is found that the transient state of stator winding is ignored. The alternating electromagnetic torque component and the one-way electromagnetic torque component produced by the aperiodic current of the stator are ignored in the process of three-phase short circuit of the generator, and the latter belongs to the braking torque. The simulation accuracy of the stability of the first pendulum at the power angle will be affected by neglecting it. 5. 5. Taking the time-step finite element results as the target curve, the parameters of the generator in the process of large disturbance are identified by the least square method, and the variation of these parameters with the power angle of the generator is revealed. The accuracy of the calculation results of identification parameters is obviously higher than that of factory parameters. At the same time, the generator parameters are identified when different materials are used in the rotor slot wedge, and the influence of rotor slot wedge conductivity on the generator parameters is obtained. The results provide theoretical support for further improvement of the practical model.
【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM31
[Abstract]:The dynamic operation ability of synchronous generator after disturbance is of great significance to the safe and stable operation of the system. In this paper, a time-step finite element model is established for the study of generator operating capacity under disturbance conditions. The influence of complex damping structure and material characteristics of turbogenerator rotor on the stability of the system is studied. The results are compared with the results of three practical models used in power system simulation. On this basis, the parameters of the generator in the process of large disturbance are identified by using the time-step finite element results as the standard response. The main results are as follows: 1. A time-step finite element model is established to analyze the influence of three-part damping structure and damping material characteristics on the dynamic performance of turbogenerator rotor. The spatio-temporal discretization strategy of the model is optimized and improved. The skin effect of eddy current in rotor damping structure can be taken into account more accurately, and the veracity of the model is verified by the model machine test. 2. Taking a 300MW turbogenerator as an example, through detailed time-step finite element calculation and analysis, the relationship between the damping structure of the turbine generator rotor, such as the large tooth guide bar, the rotor core and the rotor conductive slot wedge, and the first pendulum stability of the generator is revealed. It is found that the influence of rotor damping structure on the stability limit of the first pendulum mainly depends on its equivalent resistance. It is revealed that the stability limit of the first pendulum varies with the conductivity of the rotor slot wedge. The physical nature of the two hypothetical conditions of the practical model is revealed. Model A assumes the mutual flux leakage between the excitation winding and the damping winding and neglects the self-leakage flux chain of the damping winding. On the basis of hypothesis B model, the damping correlation term is further simplified and the hypothesis B-1 model is obtained. On this basis, the results of large and small disturbances calculated by time step finite element model and three practical models are compared and analyzed, and the differences between the simulation results of different models are obtained. 4. The influence of electromagnetic transient of stator winding on electromechanical transient process of generator is studied by combining analytical method and numerical simulation. It is found that the transient state of stator winding is ignored. The alternating electromagnetic torque component and the one-way electromagnetic torque component produced by the aperiodic current of the stator are ignored in the process of three-phase short circuit of the generator, and the latter belongs to the braking torque. The simulation accuracy of the stability of the first pendulum at the power angle will be affected by neglecting it. 5. 5. Taking the time-step finite element results as the target curve, the parameters of the generator in the process of large disturbance are identified by the least square method, and the variation of these parameters with the power angle of the generator is revealed. The accuracy of the calculation results of identification parameters is obviously higher than that of factory parameters. At the same time, the generator parameters are identified when different materials are used in the rotor slot wedge, and the influence of rotor slot wedge conductivity on the generator parameters is obtained. The results provide theoretical support for further improvement of the practical model.
【学位授予单位】：华北电力大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM31
【参考文献】
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