Large scale wind power machine control method based on maximum energy capture
Technical field
What the present invention relates to is a kind of controlling method of technical field of wind power generation, specifically, relates to a kind of large scale wind power machine control method based on maximum energy capture.
Background technique
Wind energy is a kind of renewable energy sources, and in recent years, wind energy development is extensively paid much attention to utilization.The wind-power electricity generation main purpose is the wind energy of utilizing as much as possible, but wind is a kind of vector, has randomness, no matter be that wind direction or wind speed are always constantly changing, so the energy that produces also is to change constantly, this just requires wind power generating set is controlled, and guarantees wind energy conversion system Maximum Power Output all the time, and the utilization ratio that improves wind energy guarantees the Security and the reliability of wind energy conversion system simultaneously.
In the prior art, the someone proposes to adopt stall power adjustments mode, and the blade of stall power adjustments mode unit can not change with wind speed in the generating angle of the time facining the wind, and power adjustments realizes by the stalling characteristics of blade self.This mode has advantage simple in structure, that probability of malfunction is low, and its shortcoming mainly is the restriction that the performance of wind power generating set is subjected to the blade stall performance, and generated output descends on the contrary to some extent when the wind speed overrate.Another shortcoming is that blade shape and complex structure, weight are big, makes the wind wheel rotary inertia big, is unwell to Large-scale Wind Turbines.The somebody proposes to adopt variable speed constant frequency power adjustments mode, though can overcome above-mentioned shortcoming effectively, but when wind speed surpassed rated wind speed, owing to be subjected to the strong mechanical constraints of rotary component and the Power Limitation of power electronic devices, the control effect neither be very desirable.
Find through literature search prior art, Perales etc. were " Proc.of The 25th AnnualConference of the IEEE " (the 25th nd Annual Meeting collection of IEEE) (1999, the 2nd volume, the 614--618 page or leaf) " Fuzzy logic control of a variablespeed; variable pitch wind turbine " (speed-changing oar-changing is apart from the wind energy conversion system fuzzy logic control) delivered on, a kind of speed-changing oar-changing has been proposed apart from wind energy conversion system fuzzy logic control method in this article, concrete grammar is: based on catching the maximal wind-energy principle, by detecting the rotating speed and the output power of generator, and control the tip-speed ratio of wind energy conversion system according to the variation of rotating speed and output power, seek maximum output value point, but this method is owing to control rotating speed and power simultaneously, controlled quentity controlled variable is more, is difficult to actual central the application.Also find in the retrieval, Prats etc. were " Proc.of The 33th Power Electronics Specialists Conference " (the 33rd the special nd Annual Meeting collection of International Power electronics) (2002, the 1st volume, the 101--105 page or leaf) " the A new fuzzy logic controller to improve the captured wind energy in areal 800kW variable speed-variable pitch wind turbine " that delivers on (a kind of novel being applicable to improved the fuzzy logic controller that 800kw speed change-change oar blower fan improves capturing wind energy), designed a kind of fuzzy controller in this article, proposed to adopt the thought of different control strategies at change of wind velocity, but control input quantity or generator speed during feather control, rather than generator power, the control effect neither be very desirable.
Summary of the invention
The objective of the invention is to overcome the deficiencies in the prior art, a kind of large scale wind power machine control method based on maximum energy capture is proposed, make it adopt shifting control method at low wind speed, high wind speed adopts variable pitch control method, even be engraved in variation like this during wind speed, wind energy conversion system also can keep peak output output.
The present invention is achieved by the following technical solutions, and the inventive method is: when wind speed changes, adopt shifting control method between incision wind speed and rated wind speed, follow the trail of the best power curve, obtain peak output; When wind speed changes between rated wind speed and cut-out wind speed, adopt variable pitch control method, regulate the variation of blade propeller pitch angle, keep rated power constant.
Described shifting control method, be meant: when wind speed changed between incision wind speed and rated wind speed, the tach signal according to speed probe records sent drive signal by dsp controller, the control generator speed changes, it is constant to make that tip-speed ratio λ=ω R/v keeps optimum value, and keeping the blade propeller pitch angle simultaneously is 0 °, makes wind energy conversion system follow the trail of the best power curve, has the highest wind energy conversion efficiency, in the formula: v is a wind speed, and ω is the wind wheel angular velocity of rotation, and R is the wind wheel radius.
Described variable pitch control method, be meant: when wind speed changes between rated wind speed and cut-out wind speed, the dynamo power signal that records according to power sensor, send drive signal by dsp controller, make the hydraulic variable-pitch mechanism action regulate the variation of blade propeller pitch angle, keep rated power constant.
Described speed probe, wherein magnetoelectric measuring cell (phonic wheel) rotates in magnetic field with alternator shaft, from coil, export the consecutive pulses signal owing to electromagnetic induction when rotating continuously, thereby change the rotating speed of generator into pulse signal with certain frequency, can calculate rotating speed from pulse frequency easily by formula n=60f/z, n is a generator speed in the formula, and z is the number of teeth of phonic wheel, and f is the frequency values of pulse.
Described power sensor adopts Hall current sensor and Hall voltage sensor, detects the voltage and current of generator amature side respectively, thereby realizes the detection to generator power.That Hall current sensor is used for measuring is straight, alternating-current pulse and hybrid type electric current, and the Hall voltage sensor is mainly used in measures direct current, interchange and pulsed voltage.
The present invention adopts the wind energy conversion system maximum energy capture controlling method of speed change-feather, when wind speed changes between incision wind speed and rated wind speed, adopts shifting control method; When wind speed changes between rated wind speed and cut-out wind speed, adopt variable pitch control method, behind the wind power generation set grid-connection, the initialization control system is also judged the wind speed size, when wind speed greater than the incision wind speed and during less than rated wind speed, carry out speed Control, the tach signal that records according to speed probe, send drive signal by dsp controller, make generator speed follow the trail of the best power curvilinear motion, catch peak output thereby obtain the optimal wind energy coefficient; When wind speed greater than rated wind speed less than cut-out wind speed, this moment, variable-speed controller quit work, the feather controller is started working, the power signal that records according to power sensor, send drive signal by dsp controller, make the hydraulic variable-pitch mechanism action regulate the variation of blade propeller pitch angle, keep rated power constant; If wind speed becomes less than rated wind speed, this moment, the feather controller quit work, and variable-speed controller is started working again; If wind speed is greater than cut-out wind speed or be lower than the incision wind speed, quit work after the wind energy conversion system brake this moment, and wind power generating set cuts out electrical network; If wind speed is greater than the incision wind speed, wind power generation set grid-connection is started working.The present invention according to the size of wind speed actual change, adopts speed change-variable pitch control method from the angle of large scale wind acc power control.
The wind velocity signal that the wind energy conversion system control system of Large-scale Wind Turbines records according to anemoscope, send control command through wind energy conversion system speed change or feather controller (dsp controller), control generator speed and hydraulic variable-pitch mechanism action, thereby the variation of control generated output power.
Large-scale, grid type wind energy conversion system power control requirement that the present invention can satisfy.Its motion speed can be conditioned in the scope of a broad during wind energy conversion system variable-speed operation, can accomplish to make wind energy conversion system to keep or near under best tip speed ratio, moving, thereby the wind energy coefficient value that makes wind energy conversion system reaches or near optimum value, there is test data to show, when mean wind velocity 6.7m/s, speed change wind-powered electricity generation unit is caught 15% wind energy more than constant speed wind-powered electricity generation unit.Regulate the variation of blade propeller pitch angle during the feather operation by the hydraulic pressure pitch-changing mechanism, can reduce the violent torque of wind power generating set rises and falls, reduce the mechanical stress of all parts, this provides strong assurance for alleviating part quality or developing Large-scale Wind Turbines.Can realize the low level and smooth electric power output that rises and falls of generator in addition, reduce generator-temperature detection in the time of power grid quality in the optimization system and change.The present invention is under low wind speed, rated wind speed, high wind speed, and the wind-powered electricity generation unit all has good performance characteristic, and stability and reliability for as much as possible utilizing wind energy and assurance wind-powered electricity generation unit have positive effect.
Description of drawings
Fig. 1 is a control flow chart of the present invention
Fig. 2 is a control system block diagram of the present invention
Fig. 3 is optimal wind energy coefficient figure during for speed Control of the present invention
Peak output control schematic representation when Fig. 4 changes for wind speed of the present invention
Embodiment
Below in conjunction with accompanying drawing embodiments of the invention are elaborated: present embodiment has provided detailed mode of execution and process being to implement under the prerequisite with the technical solution of the present invention, but protection scope of the present invention is not limited to following embodiment.
As shown in Figure 1, the concrete implementing procedure of present embodiment is as follows:
A. behind the wind power generation set grid-connection, the initialization control system, propeller pitch angle β=0, and judge the wind speed size;
B. work as wind speed less than the incision wind speed, wind energy conversion system is failure to actuate.
C. when wind speed changes between incision wind speed and rated wind speed, carry out speed Control, the tach signal that records according to speed probe, send drive signal by dsp controller, by gear-box regulator generator rotational speed omega, and and setting value ω * compare and constitute a closed-loop feedback automatic control system, know that by Fig. 3 this moment, wind energy conversion system was followed the trail of the best power curvilinear motion, obtain optimal wind energy coefficient C
P-max=C
P(λ
Opt, 0), thus peak output caught
D. when wind speed greater than rated wind speed less than cut-out wind speed, this moment, variable-speed controller quit work, the feather controller is started working, the power signal P and the power given value P* that record according to power sensor compare, send drive signal by dsp controller, make the hydraulic variable-pitch mechanism action regulate the variation of blade propeller pitch angle, obtain the C that changes
P(λ β), constitutes a closed-loop feedback automatic control system, keeps rated power constant.
E. work as wind speed greater than cut-out wind speed, wind energy conversion system water brake mechanism begins action, and wind energy conversion system quits work, and the wind-powered electricity generation unit cuts out electrical network.
V is a wind speed among this figure, and P is a power, and P* is that power given value λ is a tip-speed ratio, λ
OPTBe optimum tip-speed ratio, ω is a wind wheel angular velocity, and ω * is a wind wheel angular velocity setting value, and n is a gear box ratio, and R is the wind wheel radius, and β is a propeller pitch angle, C
PBe the wind energy coefficient.
As shown in Figure 2, wind energy conversion system peak output acquisition control block diagram, wherein: controller is made up of variable-speed controller and feather controller, when wind speed changes between incision wind speed and rated wind speed, tach signal is imported variable-speed controller through speed probe, finally finish Tracing Control to the optimal power of large scale wind power machine, here the speed probe model is the OD9011 high sensitivity that Shanghai Ou Dan instrument Electronics Co., Ltd. produces, the magnetoelectric tachometric transducer of high noise immunity, measuring range is 0.3HZ~10KHZ, operating voltage 5~24V, serviceability temperature-30 ℃~+ 150 ℃, the wave mode of output is similar to square wave, and output signal amplitude size is directly proportional with rotating speed.Less than cut-out wind speed, this moment, variable-speed controller quit work wind speed greater than rated wind speed, and the feather controller is started working, and power signal is finally finished the control to the rated power of large scale wind power machine through power sensor input feather controller.Here power sensor adopts Hall current sensor and voltage sensor senses electric current and magnitude of voltage respectively, has just obtained the output power of generator.The current sensor model is the LA28-NP that Switzerland lime company (LEM) produces, and the specified effective value electric current in former limit is 25mA, and employings ± 15V power supply is powered, and precision is ± 0.5%, the primary current measuring range is 0~± 36A.The model of voltage transducer is the LV28-P that Switzerland lime company (LEM) produces, the specified effective value electric current in former limit is 10mA, and the specified effective value electric current of secondary is 25mA, the power supply of employing ± 15V power supply, precision is ± 0.6%, the primary current measuring range is 0~± 14mA.
As shown in Figure 3, wind energy conversion system wind energy coefficient C
P(λ, β) variation is relevant with propeller pitch angle β with blower fan tip-speed ratio λ.Propeller pitch angle β is big more, and wind energy conversion system wind energy coefficient is more little; In propeller pitch angle β=0, blower fan tip-speed ratio λ=λ
OptThe place, wind energy conversion system wind energy coefficient C
P(λ β) has maximum value C
P-maxSo in the speed Control process, as long as make that 0 ° of propeller pitch angle maintenance is constant, blower fan tip-speed ratio λ=ω R/v value keeps λ
OptConstant, wind energy conversion system wind energy coefficient in whole speed-change process can both be got maximum value C
P-max, promptly realized wind energy conversion system tracking best power curve.
As shown in Figure 4, wind speed is lower than incision wind speed v
i, wind energy conversion system stops operating and does not work; Wind speed is greater than incision wind speed v
i, wind energy conversion system is started working, at wind speed greater than incision wind speed v
iLess than rated wind speed v
rThe time, adopt speed Control, realize tracking to the optimal power curve, obtain peak output; When wind speed greater than rated wind speed v
rLess than cut-out wind speed v
oThe time, adopt feather control, it is constant to make the unit output power keep rated power Pr by the adjusting propeller pitch angle; When wind speed greater than cut-out wind speed v
o, wind energy conversion system starts braking mechanism, and wind energy conversion system quits work.