独立运行的风力发电系统.ppt

The Research of Stand-alone DFIG Systems and Its Control Stratagy,Outline,Applicable occasions and system components,The research of fixed-pitch wind turbine,Vector control strategies based on stator-flux orientation,Simulation,Applicable occasions and system components,Applicable occasions: Stand-alone wind power systems are generally used in remote areas where are not covered by the conventional power grid. In addition to regular grid, we should promote stand-alone wind power systems vigorously and supply the power of daily lives and production for remote area residents (such as remote rural, pastoral area, island and so on).,remote rural,Applicable occasions and system components,Advantages compared with general wind power generation : High mobility ; b. Diversification of energy use ; c. Easy installation.,Island,pastoral area,Applicable occasions and system components,system components Due to the characteristics of the wind energy instability, for the stable power supply to the regional load,wind power generation system is often combined with other forms of energy such as solar energy, fuel, or adding energy storage devices ( batteries, fly wheels and so on), which can store up the wind energy . When wind energy is insufficient, energy storage devices supply to the loads together with wind power generation system.,storage battery,Comined energy supply systems,Applicable occasions and system components,Structure of stand-alone DFIG systems,off grid,The research of fixed-pitch wind turbine,Wind turbines are the primary energy conversion parts in wind power generation system i. Its used to intercept the air flowing with the kinetic energy, and the part of the kinetic energy of wind turbine blades wind swept area is converted into mechanical energy. It not only determines the effective output power of the wind power generation system, but also directly affecting the safety of the crew and stable operation,which is one of the key components in the wind power generation system. According to the aerodynamics, the input power of the wind turbine:,:air density,:airflow through the cross-sectional area of the wind wheel in unit time,:wind Speed,Tip speed ratio:,：blade rotation angular speed,The research of fixed-pitch wind turbine,Mechanical power output of the wind turbine:,R：blade radius,Cp：Wind energy utilization factor,Fixed-pitch wind turbine Cp() curve:,The research of fixed-pitch wind turbine,A particular fixed pitch wind turbine has a unique optimaltip speed ratio that can get the maximum value of wind energy utilization factor.,Fixed pitch variable speed wind power - speed curve,: optimal tip speed ratio,Cpmax : maximum value of wind energy utilization factor,The research of fixed-pitch wind turbine,Simulation model of fixed-pitch wind turbine,Vector control strategies based on stator-flux orientation,Excitation stator flux oriented control strategy is derived under the conditions of the grid voltage symmetry , the motor parameters symmetry, symmetrical line and transformer parameters and symmetry load conditions ,Therefore, each three-phase system of physical quantities (voltage, current, flux, etc.) contains only positive sequence component system in steady-state operation, active power, reactive power, electromagnetic torque, mechanical torque and speed are constants.,DFIG coordinate transformation diagram,Vector control strategies based on stator-flux orientation,DFIG voltage equation in a two-phase synchronous rotating coordinate system:,(1-1),DFIG system flux equation under the two-phase synchronous rotating coordinate :,(1-2),Vector control strategies based on stator-flux orientation,To reduce the system order and simplify the mathematical model, directiing d-axis synchronous rotating coordinate system. with the following assumptions: a. Ignoring the transient process of the stator flux, that space vector s is in synchronous speed rotation, keeping the amplitude constant. And the s was defined in the d-axis synchronous coordinates; b. Ignoring the stator resistance Rs.,By the previous equations(1-1)(1-2)and this equation(1-3):,(1-3),(1-4),(1-6),Vector control strategies based on stator-flux orientation,The definition of the magnetizing current ims as follows:,(1-5),By the previous equations(1-4):,the stator flux orientation,(1-6),(1-7),Control the amplitude of the stator voltage vector,(1-8),Vector control strategies based on stator-flux orientation,By the previous equations(1-5)(1-7)(1-8), mathematical model of the DFIG in independent operation as shown below:,By the mathematical model of DFIG independent operation, which can get control block diagram as shown below:,Vector control strategies based on stator-flux orientation,DFIG in independent operationthe excitation vector control strategy diagram:,decoupled control,Current inner loop PI controller: based on IMC,Voltage outer loop PI contorller,Simulation,Simulation Figure:,Simulation,Initial conditions and requirements: Each phase resistance value of the load:R=5.45 ohm Input constant power : Pm=30 KW In stable operation, the stator voltage Us maintained a