电网扰动下双馈式风力发电机组的分析与控制

发布时间：2018-01-11 23:16

  本文关键词：电网扰动下双馈式风力发电机组的分析与控制　出处：《华北电力大学》2014年博士论文　论文类型：学位论文

  更多相关文章： 风能转化系统(WECS) 双馈发电机(DFIG) dq原理 磁场定向控制(FOC)

【摘要】：本文基于矢量控制或磁场定向控制的方法对双馈风电机组(DFIG)的风能转化系统(WECS)在电网扰动情况下的运行特性进行了深入研究,并将磁链作为描述DFIG模型的基本变量。详细推导了三相静止到两相旋转的dq变换,第一步是三相静止到两相静止坐标变换,第二步是由两相静止到两相旋转坐标变换。建立了三相静止坐标系下的双馈感应电机的模型,通过dq变换,建立了两相旋转坐标系下的双馈感应电机模型。在双馈式风电机组中,网侧变流器以及转子侧变流器的控制起到至关重要的作用。对于网侧变流器,采用基于网侧电压定向的矢量控制来保持直流侧电压的恒定并控制转子和电网之间的无功流动,电网电压定向在d轴,q轴分量为0。并假定电网电压恒定,利用d轴电流分量和q轴电流分量分别控制有功功率和无功功率。锁相环检测电网电压的位置角,为dq坐标变换提供相角。利用电压外环维持直流母线电压恒定,网侧电流参考值是直流母线电压参考值与实际值的偏差经过PI控制获得,对网侧电流的参考值和实际值之间的偏差进行控制获得网侧变流器的控制信号。对于转子侧变流器,采用基于定子电压定向的矢量控制转子电流的dq分量,从而实现对无功功率和有功功率的控制,其中,定子电压定向在d轴。为了简化控制和计算转子dq轴电流参考值,假设定子励磁电流恒定,并且忽略漏磁。为了实现最大风能追踪,转速实际值与参考值之间的偏差经过PI控制得到转子侧d轴电流分量,无功功率参考值与实际值的偏差经过获得PI控制得到转子侧q轴电流分量,对转子侧电流的参考值和实际值之间的偏差进行控制获得转子侧变流器的控制信号,形成了基于定子电压定向的DFIG有功、无功功率解耦控制策略。基于上述建立的转子侧变流器和网侧变流器模型,对双馈式风电机组进行控制,并利用MATLAB/SIMULINK进行了仿真并验证了模型的正确性。 本文对双馈式风电机组的五种运行工况进行了仿真,分别是：正常运行、电网电压扰动、风速扰动、系统频率扰动和无功功率参考值扰动。仿真结果表明：在正常运行状态下,转子侧变流器的控制策略可以实现有功功率和无功功率的解耦控制,转子磁链和定子磁链保持常数。当电网侧电压突然增加时,定子电流和转子电流减小,此时无功功率也减小；当电网侧电压突然减小时,定子电流和转子电流增加,由于变流器吸收一部分能量,直流侧电压首先会升高,经过一段时间的调整后维持在初值。风速的改变直接影响到转子的转速,桨距角会达到最佳值来保证从风能中,吸收的功率最大。当风速超过额定风速时,桨距角将会动作,使风力机吸收的风功率不再增加,风力机此时输出额定功率。系统中频率的微小改变不会对系统的可靠性产生影响,但当频率变化比较大的时,系统会受到较大影响。当无功功率指令增加时,定子电流和转子电流增加,而转子转速减小。
[Abstract]:Based on the vector control method or field oriented control of double fed wind generator (DFIG) wind energy conversion system (WECS) in the power grid operation characteristics under perturbations is studied, and the flux as the basic variables describing the DFIG model deduced in detail. The three-phase static to the two-phase rotating dq transformation, the first step is to three-phase static two-phase static coordinate transform, the second step is to the two-phase rotating coordinate transformation by two-phase stationary. The doubly fed induction motor three-phase static coordinate system of the model, through the dq transform, established the DFIG model of two-phase rotating coordinate system. In the doubly fed wind turbine. The network side converter and the rotor side converter control plays a crucial role. For the grid side converter, based on the vector control of grid side voltage oriented to maintain constant DC voltage control and rotor and power grid The reactive power flow between the grid voltage oriented in the d axis, q axis component 0. and assuming constant voltage control, active power and reactive power of the d axis and the q axis current component currents. The phase-locked loop detection voltage position angle, provide phase angle of dq coordinate transformation. The use of voltage loop to maintain the DC link voltage constant, the net side current reference value of DC bus voltage is the reference value of the deviation between the actual values obtained by the PI control of the grid current reference value and the actual value of the deviation between the control signal to gain control of the grid side converter. For the rotor side converter, the DQ component of the stator voltage oriented vector based on the control of the rotor current, so as to realize the control of active power and reactive power of the stator voltage oriented in the d axis. In order to simplify the control and calculation of rotor DQ axis current value, assuming that the stator excitation current constant Set, and ignore the magnetic leakage. In order to achieve the maximum wind power tracking speed, the actual value and the reference value of the deviation between the PI control by rotor side d axis current component, reactive power reference value and the actual value of the deviation obtained by PI control of rotor side Q axial current component of rotor current reference value and the actual the value of the deviation between the control gain control signal of the rotor side converter is formed based on the stator voltage oriented DFIG active and reactive power decoupling control strategy. The model of rotor side converter and grid side converter is established based on the above, the control of the doubly fed wind turbine, and simulates and verifies the correctness of the model the use of MATLAB/SIMULINK.
In this paper, five kinds of operating conditions of the doubly fed wind turbine are simulated, respectively: normal operation, voltage disturbance, wind disturbance, system frequency disturbance and reference value of reactive power disturbance. The simulation results show that under normal operating conditions, the rotor side converter control strategy can realize active power and no reactive power decoupling control, rotor flux and stator flux is constant. When the sudden increase of grid side voltage, stator current and rotor current decreases, the reactive power is reduced; when the grid voltage suddenly decreases, stator current and rotor current is increased, because the absorption part of the energy converter, DC side voltage first increased, after a period of adjustment and maintenance in the initial value. The wind speed change directly affects the rotor speed, pitch angle will achieve the best value to ensure the power absorbed from the wind, when the maximum. The wind speed exceeds the rated wind speed, the pitch will move, wind power of the wind absorption is not increased, then the output of wind turbine rated power system frequency. Minor changes will not affect the reliability of the system, but when the frequency is relatively large changes, the system will be subject to greater impact. When the reactive power command increased when the stator current and rotor current and rotor speed increases, decreases.

【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】：TM315
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本文编号：1411665