双馈感应发电机接入配电网的三相短路电流特性及峰值评估
发布时间：2018-07-21 14:08
【摘要】：双馈感应发电机(Doubly Fed Induction Generator，DFIG)以其灵活的控制性能，在风力发电中应用广泛。电网发生短路时DFIG机端电压下降，在定子绕组产生冲击电流，对于大部分商用DFIG机组，须在转子侧接入合适的撬棒电阻，以保护DFIG和实现低电压穿越运行。短路电流计算是电网规划和保护的基础，短路故障将会对电网及设备产生冲击，特别是电气设备动稳定性校验和确保含DFIG电网中断路器遮断容量的合理配置时，都须对电网故障后DFIG短路电流峰值进行估算，因此准确地计算出短路电流的峰值尤为重要。本文主要内容如下： ①根据DFIG矢量模型，推导撬棒保护动作前后的DFIG定转子电流解析式。当配网故障后撬棒保护未动作时，考虑转子侧变流器控制对转子电流的调节作用，利用转子电压和转子变流器输出电压指令方程，求解转子电流二阶微分方程，，推导撬棒保护未动作时DFIG的三相短路电流解析式；而撬棒保护动作后，考虑撬棒电阻计算定子磁链直流分量，提出将DFIG定子磁链直流分量归算至转子侧形成静态等值电路，以此推导撬棒保护动作时DFIG的三相短路电流解析式。 ②基于DFIG定子三相短路电流时域表达式，提出DFIG接入配电网的三相短路电流峰值评估方法。根据撬棒保护动作前的转子电流表达式，研究不同功率控制下的转子电流峰值对撬棒保护的影响，提出撬棒判别依据；针对撬棒动作后分析近端和远端故障时不同撬棒电阻对短路电流暂态直流分量、暂态周期分量和强制分量的影响，利用DFIG转子运动方程，提出计及转速变化的DFIG三相短路电流峰值评估方法，由此来确定DFIG三相短路电流峰值的出现时刻。 ③在MATLAB/Simulink仿真软件平台中建立DFIG接入配电网的电磁暂态仿真模型，验证本文提出的评估方法。分析DFIG三相短路故障暂态特性，研究不同机组容量以及不同故障节点时的DFIG三相短路电流，并对本文所提方法的计算值与仿真结果进行对比分析，验证所提出的DFIG接入配电网的三相短路电流峰值评估方法的正确性。
[Abstract]:Doubly-fed induction generator (DFIG) is widely used in wind power generation due to its flexible control performance. For most commercial DFIG units, appropriate crowbar resistance should be connected to the rotor side to protect DFIG and realize low voltage traversing operation. Short circuit current calculation is the basis of power network planning and protection. Short circuit fault will impact the power network and equipment, especially when checking the dynamic stability of electrical equipment and ensuring the reasonable configuration of circuit breaker interrupting capacity in DFIG power network. It is necessary to estimate the peak value of DFIG short-circuit current after fault, so it is very important to calculate the peak value of short-circuit current accurately. The main contents of this paper are as follows: 1 according to the DFIG vector model, the analytical formula of DFIG stator and rotor current before and after crowbar protection is derived. When the bar protection does not work after the fault of the distribution network, considering the regulating effect of the rotor side converter control on the rotor current, the second order differential equation of rotor current is solved by using the rotor voltage and the output voltage instruction equation of the rotor converter. The three-phase short circuit current analytical formula of DFIG is deduced when the rod protection is not in operation, and the DC component of stator flux is calculated by considering the crowbar resistance, and the static equivalent circuit is formed when the DC component of DFIG stator flux is reduced to the rotor side. Based on the time-domain expression of three-phase short-circuit current of DFIG stator, a method for evaluating the peak value of three-phase short-circuit current of DFIG connected to distribution network is proposed. According to the expression of rotor current before crowbar protection, the influence of rotor current peak value under different power control on crowbar protection is studied, and the discriminant basis of crowbar is put forward. Based on the analysis of the influence of different crowbar resistance on the transient DC component, transient periodic component and forced component of short circuit current, the DFIG rotor motion equation is used to analyze the influence of different bar resistance on the transient DC component, transient periodic component and forced component of short circuit current. A method of evaluating the peak value of DFIG three-phase short-circuit current considering the variation of rotational speed is proposed to determine the peak time of DFIG three-phase short-circuit current. 3 the electromagnetic transient simulation model of DFIG connecting to distribution network is established in MATLAB / Simulink simulation software platform. Verify the evaluation method proposed in this paper. The transient characteristics of DFIG three-phase short-circuit fault are analyzed, and the DFIG three-phase short-circuit current with different unit capacity and different fault nodes is studied, and the calculated value of the proposed method is compared with the simulation results. The correctness of the proposed method for evaluating the peak value of three phase short circuit current in DFIG distribution network is verified.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM31
本文编号：2135777
[Abstract]:Doubly-fed induction generator (DFIG) is widely used in wind power generation due to its flexible control performance. For most commercial DFIG units, appropriate crowbar resistance should be connected to the rotor side to protect DFIG and realize low voltage traversing operation. Short circuit current calculation is the basis of power network planning and protection. Short circuit fault will impact the power network and equipment, especially when checking the dynamic stability of electrical equipment and ensuring the reasonable configuration of circuit breaker interrupting capacity in DFIG power network. It is necessary to estimate the peak value of DFIG short-circuit current after fault, so it is very important to calculate the peak value of short-circuit current accurately. The main contents of this paper are as follows: 1 according to the DFIG vector model, the analytical formula of DFIG stator and rotor current before and after crowbar protection is derived. When the bar protection does not work after the fault of the distribution network, considering the regulating effect of the rotor side converter control on the rotor current, the second order differential equation of rotor current is solved by using the rotor voltage and the output voltage instruction equation of the rotor converter. The three-phase short circuit current analytical formula of DFIG is deduced when the rod protection is not in operation, and the DC component of stator flux is calculated by considering the crowbar resistance, and the static equivalent circuit is formed when the DC component of DFIG stator flux is reduced to the rotor side. Based on the time-domain expression of three-phase short-circuit current of DFIG stator, a method for evaluating the peak value of three-phase short-circuit current of DFIG connected to distribution network is proposed. According to the expression of rotor current before crowbar protection, the influence of rotor current peak value under different power control on crowbar protection is studied, and the discriminant basis of crowbar is put forward. Based on the analysis of the influence of different crowbar resistance on the transient DC component, transient periodic component and forced component of short circuit current, the DFIG rotor motion equation is used to analyze the influence of different bar resistance on the transient DC component, transient periodic component and forced component of short circuit current. A method of evaluating the peak value of DFIG three-phase short-circuit current considering the variation of rotational speed is proposed to determine the peak time of DFIG three-phase short-circuit current. 3 the electromagnetic transient simulation model of DFIG connecting to distribution network is established in MATLAB / Simulink simulation software platform. Verify the evaluation method proposed in this paper. The transient characteristics of DFIG three-phase short-circuit fault are analyzed, and the DFIG three-phase short-circuit current with different unit capacity and different fault nodes is studied, and the calculated value of the proposed method is compared with the simulation results. The correctness of the proposed method for evaluating the peak value of three phase short circuit current in DFIG distribution network is verified.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM31
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