用于電力系統(tǒng)穩(wěn)定分析的同步發(fā)電機數(shù)學模型研究
發(fā)布時間：2018-08-19 13:48
【摘要】：同步發(fā)電機在擾動后的動態(tài)運行能力對于系統(tǒng)安全穩(wěn)定運行具有重要意義。本文建立了用于研究擾動條件下發(fā)電機運行能力的時步有限元模型,研究了汽輪發(fā)電機轉子復雜阻尼結構及其材料特性對系統(tǒng)穩(wěn)定性的影響,并與電力系統(tǒng)仿真分析所用的發(fā)電機三種實用模型的計算結果進行了對比研究。在此基礎上,以時步有限元結果作為標準響應,辨識了發(fā)電機大擾動過程中的電機參數(shù)。主要成果如下： 1.建立了用于分析汽輪發(fā)電機轉子三部分阻尼結構和阻尼材料特性對其動態(tài)運行能力影響的時步有限元模型,對該模型的時空離散策略進行了優(yōu)化和改進,使其能夠更加準確的計及多因素非線性條件下轉子阻尼結構中的渦流集膚效應,并通過模型機試驗驗證了該模型的準確性。 2.以一臺300MW汽輪發(fā)電機為例,通過詳細的時步有限元計算分析,揭示了汽輪發(fā)電機轉子大齒導條、轉子鐵心和轉子導電槽楔等阻尼結構與發(fā)電機第一擺穩(wěn)定性之間的關系,發(fā)現(xiàn)轉子阻尼結構對第一擺穩(wěn)定極限的影響主要取決于其等效電阻；進一步對轉子槽楔采用不同材料時發(fā)電機的第一擺穩(wěn)定性進行研究,揭示了第一擺穩(wěn)定極限隨轉子槽楔電導率的變化規(guī)律。 3.揭示了實用模型兩種假設條件的物理本質(zhì),假設A模型計及了勵磁繞組和阻尼繞組的互漏磁鏈,忽略了阻尼繞組自漏磁鏈；假設B模型反之；在假設B模型的基礎上進一步對阻尼相關項進行簡化得到了假設B-1模型。在此基礎上,對比分析了時步有限元模型與三種實用模型所計算的大擾動和小擾動結果,得出不同模型仿真結果之問的差異。 4.將解析法和數(shù)值仿真相結合研究了實用模型中定子繞組電磁暫態(tài)對發(fā)電機機電暫態(tài)過程的影響,發(fā)現(xiàn)忽略定子繞組暫態(tài)后,發(fā)電機三相突然短路過程中的交變電磁轉矩分量和定子非周期電流產(chǎn)生的單向電磁轉矩分量均被忽略,而后者屬于制動性質(zhì)的轉矩,被忽略后會影響功角第一擺穩(wěn)定性的仿真精度。 5.以時步有限元結果作為目標曲線,采用最小二乘法辨識了發(fā)電機大擾動過程中的電機參數(shù),揭示了這些參數(shù)隨發(fā)電機功角的變化規(guī)律,得出辨識參數(shù)計算結果的精度明顯高于廠家參數(shù)。同時,對轉子導電槽楔采用不同材料時的發(fā)電機參數(shù)進行辨識,得出轉子槽楔電導率對發(fā)電機各參數(shù)的影響。研究結果為實用模型的進一步改進提供了理論支撐。
[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.
【學位授予單位】：華北電力大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：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.
【學位授予單位】：華北電力大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TM31
【參考文獻】
相關期刊論文 前10條
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本文編號：2191839
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