Modeling and testing method of fan model

Abstract

The invention discloses a modeling and testing method of a fan model, which belongs to the field of fan model establishment, and comprises a rotor side converter, a controller of the rotor side converter, a pitch angle controller, a wind turbine, a driving system and a generator / grid side converter, the test method comprises the following steps of: 1, connecting the doubly-fed fan into an infinite bus system; and 2, carrying out a typical test project. According to the method, active and reactive decoupling control of the fan is realized, active control logic is relatively simple, and an active current instruction value is obtained by dividing an active power given value by a current interface voltage after the active power given value passes through an inertia link; reactive power control has multiple control modes, such as fixed power factor, fixed reactive power, fixed voltage and the like, switching is carried out through control words, meanwhile, a reactive current compensation characteristic setting link is provided, and the requirement that in some regulations, after a power grid breaks down, wind power needs to provide moderate reactive current can be met.

Description

Technical Field

[0001] The invention relates to the technical field of fan model establishment, and in particular to a modeling and testing method for a fan model. Background Art

[0002] Wind power, with its mature technology and abundant resources, has a priority position in the development of clean energy. With the leapfrog development of wind power, the contradiction between the explosive growth of wind power installed capacity and the relatively backward construction of power grids has become increasingly prominent;

[0003] The existing wind turbine modeling cannot decouple the active and reactive power of the wind turbine, and cannot meet the requirements of certain regulations that wind power needs to provide moderate reactive current after a power grid failure. In addition, the existing wind turbine modeling method does not have a test simulation process and has not been verified by actual operating data. The accuracy and applicability of the model are low, and it cannot fully and accurately simulate the operating conditions after large-scale wind power access. Therefore, a modeling and test method for a wind turbine model is proposed to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to solve the problems in the prior art and to propose a modeling and testing method for a fan model.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A modeling of a wind turbine model, including a rotor-side converter and a controller thereof, a pitch angle controller, a wind turbine and a drive system, and a generator / grid-side converter, wherein the rotor-side converter and the controller thereof establish an information transmission connection with the generator / grid-side converter, and the rotor-side converter and the controller thereof control a current specified value I p and a voltage specified value Eq of the generator / grid-side converter;

[0007] The rotor-side converter and its controller establish an information transmission connection with the pitch angle controller, the rotor-side converter and its controller send an active power instruction to the pitch angle controller, and the pitch angle controller feeds back a speed instruction to the rotor-side converter and its controller;

[0008] The pitch angle controller establishes an information transmission connection with the wind turbine and the drive system, and the pitch angle controller transmits the pitch angle information to the wind turbine and the drive system;

[0009] The generator / grid-side converter establishes an information transmission connection with the wind turbine and the drive system.

[0010] Preferably, the wind turbine is used to convert wind energy into mechanical energy and drive the generator to rotate, and the doubly-fed generator DFIG is used to convert mechanical energy into electrical energy.

[0011] Preferably, the rotor side / grid side converter ensures that the grid frequency remains unchanged by adjusting the rotor side and grid side currents, and the grid-connected transformer is used for convergence and providing grid-connected point voltage and grid-connected interface.

[0012] Preferably, in the wind turbine and drive system, a double-fed equal-speed wind turbine is taken as an example, and the wind speed-power relationship is as follows:

[0013]

[0014] Where: ρ is air density, Vw is wind speed, A is the swept area of ​​the blade, Vm and Vout are cut-in wind speed and cut-out wind speed respectively, Cp is the wind energy utilization coefficient, which is entered into the dynamic simulation table

[0015] Shown as a function of tip speed ratio λ and pitch angle θ, it is a series of curves as Cp is under different θ conditions.

[0016] Preferably, before the maximum wind speed is reached, the blade pitch controller always outputs a blade pitch of 0. After the maximum wind speed is reached, the blade pitch controller automatically increases or decreases the blade pitch angle according to the power setting and the fan speed setting.

[0017] A test method for a fan model comprises the following steps:

[0018] S1. Connect the doubly-fed wind turbine to the infinite system: connect the doubly-fed wind turbine to the public grid with lines and equivalent power sources after passing through the transformer;

[0019] S2. Carry out typical test items: (1) Cp characteristics under different tip speed ratios. In the maximum power tracking area, the power coefficient Cp is guaranteed to be maximum. After reaching the rated power, as the wind speed increases, the pitch angle needs to be adjusted to reduce Cp and limit the output power to the rated value.

[0020] (2) Short-circuit fault at the wind turbine grid connection point. Depending on the type of wind turbine, the transient characteristics during the short-circuit fault are also different;

[0021] (3) The low voltage ride-through characteristic of the wind turbine ensures that the wind turbine is not cut off during low voltage periods and provides reactive power to improve the voltage stability of the power grid.

[0022] Preferably, the doubly-fed wind turbine has a rated capacity of 2MW, a rated voltage of 690V, an excitation reactance of 2.5e-3H, a stator and rotor resistance of 0.026 ohms, a stator and rotor leakage reactance of 0.87e-4H, and a step-up transformation ratio of 0.69kV / 35kV.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention realizes the decoupling control of active and reactive power of wind turbines. The active control logic is relatively simple. The active power given value, after passing through the inertia link, is divided by the current interface voltage to obtain the active current command value. There are multiple reactive control modes, such as constant power factor, constant reactive power, constant voltage, etc., which are switched through control words. At the same time, it also has a reactive current compensation characteristic setting link, which can meet the requirements of certain regulations for wind power to provide moderate reactive current after a power grid failure.

[0025] 2. The present invention can accurately simulate the operating conditions after large-scale wind power access by setting up simulation tests, and ensure the accuracy and applicability of the wind turbine model through verification by actual data. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A structural schematic diagram of a doubly-fed unit in a modeling and testing method of a wind turbine model proposed by the present invention;

[0027] Figure 2 A schematic diagram of a simulation model of a doubly-fed unit in a modeling and testing method of a wind turbine model proposed in the present invention;

[0028] Figure 3 A Cp curve diagram of a modeling and testing method of a fan model proposed by the present invention;

[0029] Figure 4 A schematic diagram of a pitch angle control module in a modeling and testing method of a wind turbine model proposed in the present invention;

[0030] Figure 5 A diagram of a rotor-side converter control module in a modeling and testing method for a wind turbine model proposed in the present invention;

[0031] Figure 6 A generator / grid-side converter module diagram in a modeling and testing method for a wind turbine model proposed in the present invention;

[0032] Figure 7 A typical engineering wiring diagram in a modeling and testing method of a fan model proposed by the present invention;

[0033] Figure 8 A system block diagram of a modeling and testing method of a fan model proposed by the present invention;

[0034] Fig. 9 A CP characteristic diagram of a modeling and testing method of a fan model proposed in the present invention;

[0035] Fig.10 A short-circuit fault diagram of a wind turbine grid connection point in a modeling and testing method of a wind turbine model proposed by the present invention;

[0036] Fig.11 This is a low voltage ride-through characteristic diagram of a wind turbine in a modeling and test method of a wind turbine model proposed in the present invention. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] Reference Figure 1-11 , a modeling of a wind turbine model, including a rotor-side converter and a controller thereof, a pitch angle controller, a wind turbine and a drive system and a generator / grid-side converter, the rotor-side converter and the controller thereof establish an information transmission connection with the generator / grid-side converter, and the rotor-side converter and the controller thereof control a current specified value Ip and a voltage specified value Eq of the generator / grid-side converter;

[0039] The rotor-side converter and its controller establish an information transmission connection with the pitch angle controller, the rotor-side converter and its controller send an active power instruction to the pitch angle controller, and the pitch angle controller feeds back a speed instruction to the rotor-side converter and its controller;

[0040] The pitch angle controller establishes an information transmission connection with the wind turbine and the drive system, and the pitch angle controller transmits the pitch angle information to the wind turbine and the drive system;

[0041] The generator / grid-side converter establishes an information transmission connection with the wind turbine and the drive system.

[0042] It should be noted that: Taking the double-fed unit as an example, the typical double-fed access infinite system can be used Figure 1 Please explain.

[0043] Furthermore, the wind turbine is used to convert wind energy into mechanical energy and drive the generator to rotate, and the double-fed generator DF IG is used to convert mechanical energy into electrical energy.

[0044] Furthermore, the rotor side / grid side converter ensures that the grid frequency remains unchanged by adjusting the rotor side and grid side currents. The rotor side / grid side converter ensures that the grid frequency remains unchanged by adjusting the rotor side and grid side currents. The grid-connected transformer is used for convergence and provides grid-connected point voltage and grid-connected interface.

[0045] Furthermore, taking a double-fed variable speed wind turbine as an example in the wind turbine and drive system, the wind speed-power relationship is as follows:

[0046]

[0047] Where: ρ is air density, Vw is wind speed, A is the swept area of ​​the blade, Vm and Vout are cut-in wind speed and cut-out wind speed respectively, Cp is the wind energy utilization coefficient, which is expressed as a function of blade tip speed ratio λ and blade pitch angle θ in dynamic simulation. As Cp is under different θ conditions, it is a series of curves such as Figure 3 .

[0048] Furthermore, before the maximum wind speed is reached, the blade angle controller always outputs 0. After the maximum wind speed is reached, the blade angle controller automatically increases or decreases the blade angle according to the power setting and the fan speed setting. Please refer to Figure 4 .

[0049] For further information, please refer to Figure 5 The PQ control module realizes the decoupling control of the active and reactive power of the wind turbine. The active control logic is relatively simple. The active power given value, after passing through the inertia link, is divided by the current interface voltage to obtain the active current command value; there are multiple reactive control modes, such as constant power factor, constant reactive power, constant voltage, etc., which are switched through control words. At the same time, it also has a reactive current compensation characteristic setting link, which can meet the requirements of certain regulations for wind power to provide moderate reactive current after a power grid failure.

[0050] Furthermore, the generator / grid-side converter module, in addition to converting the DQ components into ABC three-phase symmetrical components, also has high and low voltage current limiting links to simulate the current limiting function of the grid-side converter under fault conditions. Since the time constant of the power electronic interface is small, the dynamic process can be ignored and can be equivalent to a first-order inertia link.

[0051] It should be noted that the fan modeling parameters are as follows:

[0052] name parameter Rated active power (MW) Voltage level (kV) Power factor range Blade length (m) Tower height (m) Cut-in wind speed, rated wind speed, cut-out wind speed (m / s) Wind wheel cut-in speed, rated speed (Rpm) Delivery System With / without gearbox Transmission system efficiency (％) Generator rated speed (Rpm) Generator efficiency (％) Generator inertia time constant Tj (s) Generator stator resistance (pu) Generator stator inductance (pu) Generator rotor resistance (pu) Generator rotor inductance (pu) Generator stator and rotor mutual inductance (pu) Shafting elastic coefficient (pu) Shaft damping coefficient (pu)

[0053] The operation control parameters are as follows:

[0054]

[0055] Other parameters are as follows:

[0056] name parameter Reactive power compensation capacity MVAR Grid-connected transformer ratio Grid-connected transformer reactance (pu) Collector line impedance (pu)

[0057] A test method for a fan model comprises the following steps:

[0058] S1. Connect the doubly-fed wind turbine to the infinite system: Connect the doubly-fed wind turbine to the public grid with lines and equivalent power supply after passing through the transformer. Please refer to Figure 7 ;

[0059] S2. Carry out typical test items: (1) Cp characteristics under different tip speed ratios. In the maximum power tracking area, the power coefficient Cp is guaranteed to be maximum. After reaching the rated power, as the wind speed increases, the pitch angle needs to be adjusted to reduce Cp and limit the output power to the rated value.

[0060] (2) Short-circuit fault at the wind turbine grid connection point. Depending on the type of wind turbine, the transient characteristics during the short-circuit fault are also different;

[0061] (3) The low voltage ride-through characteristic of the wind turbine ensures that the wind turbine is not cut off during low voltage periods and provides reactive power to improve the voltage stability of the power grid.

[0062] It should be noted that the typical test waveform is as follows:

[0063] (1) Cp characteristics at different tip speed ratios (refer to Fig. 9 ):

[0064] Note: The tip speed ratio is (impeller radius r speed / wind speed). Under given tip speed ratio and pitch angle, there will always be a maximum Cp value (generally between 0.46 and 0.5), at which the maximum wind energy conversion efficiency can be obtained.

[0065] (2) Short circuit fault at the wind turbine grid connection point (top: wind turbine voltage waveform; bottom: wind turbine current waveform, refer to Fig.10 ):

[0066] Note: During the short-circuit pause process, there are forced power frequency components and free components that are not power frequency and are attenuated.

[0067] (3) Wind turbine low voltage ride-through characteristics (top: voltage amplitude; bottom: active power (black) and reactive power (red), see Fig.11 ):

[0068] Note: During a fault, the wind turbine can provide additional reactive power and provide appropriate support for system voltage stability.

[0069] Furthermore, the rated capacity of the doubly-fed wind turbine is 2MW; rated voltage is 690V; excitation reactance is 2.5e-3H; stator and rotor resistance is 0.026 ohm; stator and rotor leakage reactance is 0.87e-4H; step-up transformation ratio is 0.69kV / 35kV.

Claims

1. A modeling of a wind turbine model, including a rotor-side converter and its controller, a pitch angle controller, a wind turbine and a drive system, and a generator / grid-side converter, characterized in that: The rotor-side converter and its controller establish an information transmission connection with the generator / grid-side converter, and the rotor-side converter and its controller control the current specified value Ip and the voltage specified value Eq of the generator / grid-side converter; The rotor-side converter and its controller establish an information transmission connection with the pitch angle controller, the rotor-side converter and its controller send an active power instruction to the pitch angle controller, and the pitch angle controller feeds back a speed instruction to the rotor-side converter and its controller; The pitch angle controller establishes an information transmission connection with the wind turbine and the drive system, and the pitch angle controller transmits the pitch angle information to the wind turbine and the drive system; The generator / grid-side converter establishes an information transmission connection with the wind turbine and the drive system.

2. The modeling of a fan model according to claim 1, characterized in that: The wind turbine is used to convert wind energy into mechanical energy and drive the generator to rotate, and the double-fed generator DFIG is used to convert mechanical energy into electrical energy.

3. The modeling of a wind turbine model according to claim 1, characterized in that: The rotor-side / grid-side converter ensures that the grid frequency remains unchanged by adjusting the rotor-side and grid-side currents. The rotor-side / grid-side converter ensures that the grid frequency remains unchanged by adjusting the rotor-side and grid-side currents. The grid-connected transformer is used for converging and providing grid-connected point voltage and grid-connected interface.

4. The modeling of a wind turbine model according to claim 1, characterized in that: Taking a double-fed variable speed wind turbine as an example in the wind turbine and drive system, the wind speed-power relationship is as follows: Where: ρ is the air density, Vw is the wind speed, A is the swept area of ​​the blade, Vm and Vout are the cut-in wind speed and cut-out wind speed respectively, Cp is the wind energy utilization coefficient, which is expressed as a function of the tip speed ratio λ and the pitch angle θ in the dynamic simulation, and is a series of curves with Cp under different θ conditions.

5. The modeling of a wind turbine model according to claim 1, characterized in that: Before the maximum wind speed is reached, the blade pitch controller always outputs a blade pitch of 0. After the maximum wind speed is reached, the blade pitch controller automatically increases or decreases the blade pitch angle according to the power setting and the fan speed setting.

6. A method for testing a fan model according to any one of claims 1 to 5, characterized in that: The following steps are included: S1. Connect the doubly-fed wind turbine to the infinite system: connect the doubly-fed wind turbine to the public grid with lines and equivalent power sources after passing through the transformer; S2. Carry out typical test items: (1) Cp characteristics under different tip speed ratios. In the maximum power tracking area, the power coefficient Cp is guaranteed to be maximum. After reaching the rated power, as the wind speed increases, the pitch angle needs to be adjusted to reduce Cp and limit the output power to the rated value. (2) Short-circuit fault at the wind turbine grid connection point. Depending on the type of wind turbine, the transient characteristics during the short-circuit fault are also different; (3) The low voltage ride-through characteristic of the wind turbine ensures that the wind turbine is not cut off during low voltage periods and provides reactive power to improve the voltage stability of the power grid.

7. A method for testing a fan model according to claim 6, characterized in that: The rated capacity of the double-fed wind turbine: 2MW; Rated voltage: 690V; excitation reactance: 2.5e-3H; stator and rotor resistance: 0.026 ohm; stator and rotor leakage reactance: 0.87e-4H; step-up transformation ratio: 0.69kV / 35kV.

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