CN104018987A - Method for controlling yaw system of wind turbine - Google Patents

Abstract

The invention discloses a control method for a yaw system of a wind power generator. Based on the whole life cycle cost theory, by comparing the comprehensive cost of yaw and the predicted production capacity of the unit after yaw, the start-up constraint conditions are established to control the yaw under different working conditions. Judging the yaw action, which solves the contradiction between the wind turbine production capacity and the yaw action loss, prolongs the working life of the yaw system, and maximizes the comprehensive benefits of the wind turbine's entire life cycle. This method comprehensively considers factors such as wind speed, wind direction change rate, and wind direction change angle. By predicting the increased production capacity after yaw, combined with the cost analysis of yaw action, from the perspective of the optimal life-cycle economy, the yaw rate is adjusted when the threshold control requirements are met. Whether the action is necessary should be judged scientifically.

Description

A control method for a wind turbine yaw system

technical field

The invention belongs to the technical field of wind power generation, and in particular relates to a control method for a yaw system of a wind power generator.

Background technique

As the problem of energy shortage intensifies, wind energy, as a new type of energy, is becoming the fastest growing green energy due to its advantages of being renewable, widely distributed, green and non-polluting. As a unique servo system of large-scale wind turbines, yaw system is an important part of wind turbines. Its operating performance directly determines the overall performance of wind turbines, wind farm power generation efficiency, and wind energy utilization efficiency.

As a product of nature, wind energy has the characteristics of randomness and intermittentness, and its direction changes all the time. During the operation of wind power generation, the yaw system needs to be started frequently to keep the wind rotor in the windward state as much as possible, and improve the efficiency of wind energy utilization. . However, problems such as gyro torque will occur during the yaw process of the wind turbine, which will cause vibration of towers, blades and other components, which will pose a threat to the safety of the entire wind power generation system, and the frequent actions of the yaw system will also bring Problems such as yaw power loss and yaw component wear.

The long-term frequent start and stop of the yaw system will cause damage to the yaw system and other wind turbine components associated with it. , resulting in huge operation and maintenance costs and power generation losses. Therefore, the research on optimal control of yaw system can avoid irreparable losses from the perspective of preventive maintenance, which is directly related to the power generation efficiency and wind energy utilization rate of wind turbines.

Contents of the invention

Aiming at the defects of the prior art, the object of the present invention is to provide a control method of the yaw system of the wind power generator which can reduce the number of starts of the yaw system of the wind power generator.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

The present invention provides a control method of a yaw system of a wind power generator, comprising the following steps:

Step 1: When the wind direction changes, judge whether the wind direction change angle θ is smaller than the maximum allowable error angle θ _dmax of the wind turbine. If θ<θ _dmax , go to the next step; The fan starts normally;

Step 2: Determine whether θ exceeds the set threshold angle θ _d corresponding to the wind speed range. When θ>θ _d , go to the next step; otherwise, no yaw is required for this θ change;

Step 3: Predict the time interval T from the next wind direction change and the wind speed V within the time interval T, and calculate the power generation W _optimization under the forecast conditions, the power generation W _threshold after yaw, and C _{yaw cost} , and then judge whether the wind direction change is yaw or not according to the calculation result, if it is yaw, go to step 6; otherwise, go to the next step;

Step 4: When there is no yaw, judge whether the time interval T from when the wind direction changes next time changes for the second time. If the T changes for the second time, there is no need to yaw for this θ change; otherwise, go to the next step ;

Step 5: Determine whether the wind direction changes within the time T+Δt, where Δt is the action setting time beyond the predicted wind direction change interval, if the wind direction changes within the time T+Δt, there is no need to yaw for this θ change; otherwise, turn to to the next step;

Step 6: Wind speed yaw delay T _d The yaw system starts to run. If the yaw is completed, the entire yaw process ends; otherwise, the yaw system restarts until the yaw completes the entire yaw process.

In the step 3, if W _optimization + C _{yaw cost} - W _threshold <0, the yaw motor performs a yaw process.

Before the step 1, the yaw system control starts the wind constraint condition as follows:

Where: ρ is the air density; R is the blade radius; V _t is the predicted wind speed; is the fan conversion efficiency; is the fluctuation threshold; C _Vt is the wind energy utilization coefficient corresponding to the wind speed V _t ; θ is the wind direction change angle; T _s is the yaw delay; T is the time interval between two wind direction changes; Yaw cost; f(θ) is the part related to the wind direction change angle θ.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The invention comprehensively considers factors such as wind speed, wind direction change rate, wind direction change angle, etc., by predicting the increased production capacity after yaw, combined with the analysis of the cost of yaw action, from the perspective of the economical optimization of the whole life cycle, when the threshold control requirements are met, the yaw It is necessary to make a scientific judgment on whether the action is necessary, especially in the case of low wind speed and frequent changes in wind direction, reciprocating changes in wind direction within a small range, and the yaw system and its associated systems are prone to failures, etc. The optimal control method of the yaw system can effectively enhance the response of the crew. Capable of extreme wind direction changes, avoiding unnecessary yaw movements, reducing mechanical failures and wear of consumable parts caused by frequent yaw movements, prolonging the life of related mechanical components, reducing the operation and maintenance costs of the yaw system, and improving the efficiency of wind turbines Operational reliability, which solves the contradiction between wind turbine production capacity and yaw action loss, so as to maximize the comprehensive benefits of wind turbines in their entire life cycle, and its large-scale application can significantly improve the overall economic benefits of wind farms; and preventive maintenance perspective In order to avoid irreparable losses, improve the power generation efficiency and wind energy utilization rate of wind turbines; reduce the number of starts of the yaw system of wind turbines without reducing the overall economic benefits of wind turbines.

Description of drawings

Fig. 1 is a flow chart of the control method of the wind generator yaw system provided by the present invention.

Figure 2 is the input wind speed curve.

Fig. 3 is a diagram of angle change under yaw threshold control.

Figure 4 is a power output diagram under yaw threshold control.

Fig. 5 is a graph of angle change under yaw optimization control.

Figure 6 is a power output diagram under yaw optimization control.

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiments shown in the accompanying drawings.

Example 1

The control method of the wind turbine yaw system proposed in the present invention is based on the whole life cycle cost theory, by comparing the comprehensive cost of yaw and the predicted production capacity of the unit after yaw, and establishing the start-up constraint conditions, to control the yaw under different working conditions The action is judged, which solves the contradiction between the wind turbine production capacity and the yaw action loss, prolongs the working life of the yaw system, and realizes the maximization of the comprehensive benefits of the whole life cycle of the wind turbine.

The wind constraint condition for yaw system control startup is:

In the above formula: ρ is the air density; R is the blade radius; V _t is the predicted wind speed; is the fan conversion efficiency; is the fluctuation threshold; C _Vt is the wind energy utilization coefficient corresponding to the wind speed V _t ; θ is the wind direction change angle; T _s is the yaw delay; T is the time interval between two wind direction changes; Yaw cost; f(θ) is the part related to the wind direction change angle θ.

In order to simplify the calculation process and refer to relevant parameters, set V _t =7m/s, C _Vt =0.35, T _s =210s, ρ=1.29kg/m ³ , S=π·R ² =6793m ² , θ=20, It can be seen from the calculation that under the conditions of the wind speed of 7m/s and the set wind direction change angle of 20°, when the predicted wind direction change time interval T is between 3.5min and 16min, the yaw cost is higher than the production capacity after yaw. Thus no yaw action needs to be performed immediately.

The optimal control flow of the yaw system is shown in Fig. 1, which is a flow chart of the control method of the yaw system of the wind power generator provided by the present invention. In the figure, θ _dmax is the maximum allowable error angle of the fan; θ _d is the set threshold angle corresponding to the wind speed range; T _d is the wind speed yaw delay corresponding to the wind speed range; If the wind direction does not change within +Δt, a yaw operation is required).

Step 1: When the wind direction changes, the yaw system first judges whether the wind direction change angle θ is less than the maximum allowable error angle θ _dmax of the fan, and if θ<θ _dmax , go to the next step; otherwise, stop the fan normally and then proceed to yaw Action, and then make the fan start normally;

Step 2: Determine whether θ exceeds the set threshold angle θ _d corresponding to the wind speed range. When θ>θ _d , go to the next step; otherwise, no yaw is required for this θ change;

Step 3: Predict the time interval T from the next wind direction change and the wind speed V within the time interval T, and calculate the power generation W _optimization under the forecast conditions, the power generation W _threshold after yaw, and C _{yaw cost} , and then judge whether the wind direction change is yaw or not according to the calculation results. If it is yaw, go to step 6; otherwise, go to the next step; if W _optimization + C _{yaw cost} - W _threshold < 0, the yaw motor performs yaw navigation process.

Step 4: When there is no yaw, judge whether the time interval T from the time when the wind direction changes next time changes for the second time. If the T changes for the second time, it means that the time interval T when the wind direction changes this time is accurately predicted. This θ change does not require yaw; otherwise go to the next step;

Step 5: Determine whether the wind direction changes within the time T+Δt, where Δt is the action setting time beyond the predicted wind direction change interval, if the wind direction changes within the time T+Δt, there is no need to yaw for this θ change; otherwise, turn to to the next step;

Step 6: Wind speed yaw delay T _d The yaw system starts to run. If the yaw is completed, the entire yaw process ends; otherwise, the yaw system restarts until the yaw completes the entire yaw process.

Matlab simulates 8 changes in wind direction within one hour, as shown in Table 1, + means the wind direction changes to the right, - means the wind direction changes to the left; set the input wind speed value to 7m/s, and the wind direction angle changes within ±30°, including One-way change and reciprocating change; the error angle after yaw is 0, the rated speed of yaw is 0.8°/s, and the yaw delay in low wind speed area is 210s; the maximum power output at wind speed V depends on the wind energy captured by the wind turbine formula Obtained; when the wind speed is constant but the wind direction changes, the output power at this time is P _θ =P _Vmax ·cos(θ).

Table 1

As shown in Figure 2, Figure 2 is a graph of the input wind speed. It can be seen from the figure that the input wind speed is maintained at 7m/s.

As shown in Fig. 3, Fig. 3 is a diagram of angle change under yaw threshold control. It can be seen from the figure that under the yaw threshold control, whenever the wind direction changes and exceeds the set threshold angle, after a 210s yaw delay, the yaw action is started, and the yaw rated speed is 0.8°/s .

As shown in Figure 4, Figure 4 is a power output diagram under yaw threshold control. W _threshold = 537.8744Kw h; It can be seen from the figure that under the threshold control of the yaw system, the mechanical power output formula of the wind turbine is The corresponding power output under the threshold control of the yaw system can be calculated; and when the wind speed is constant but the wind direction is deflected, the mechanical output power at this time is P _θ =P _Vmax cos(θ), and the W _{threshold is} the power P at Points value within one hour.

As shown in Figure 5, Figure 5 is a diagram of angle change under yaw optimization control. It can be seen from the figure that under the yaw optimization control, when the wind direction changes each time, by comparing the yaw cost and the predicted production capacity after yaw, it is judged whether it is necessary to yaw. When it is judged that yaw is not necessary, The angle remains unchanged, otherwise the yaw action is started to complete the yaw against the wind, and the rated speed of yaw is 0.8°/s.

As shown in Figure 6, Figure 6 is a power output diagram under yaw optimization control. W _optimization = 538.7169Kw h; It can be seen from the figure that under the optimal control of the yaw system, the mechanical power output formula of the wind turbine is The corresponding power output under the optimal control of the yaw system can be calculated; and when the wind speed is constant but the wind direction is deflected, the mechanical output power at this time is P _θ =P _Vmax cos(θ), and W _{is optimized} as the power P at Points within an hour.

Yaw cost model calculation:

The calculation of yaw cost model includes yaw fixed cost, yaw operation and maintenance cost, yaw energy consumption and shutdown cost, etc.:

The average daily yaw is taken as 150 times, considering factors such as wind abandonment, the annual average utilization hours of the wind farm is taken as 2000h, and the values of various variables can be calculated by referring to the values of relevant parameters:

Therefore, the total cost of a single yaw is:

Combining yaw cost and predicted production capacity, it can be calculated that optimal control is more economical than threshold control:

C=W _optimization +C _{yaw cost} -W _threshold =69.7438Kw h

in:

W _{threshold is} the wind turbine output capacity under threshold control;

W _optimization is the wind turbine output capacity under optimal control;

C _{yaw cost} is the yaw cost of this time.

The above description of the embodiments is for those of ordinary skill in the art to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative effort. Therefore, the present invention is not limited to the embodiments herein. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (3)

1. a controlling method for wind driven generator yaw system, is characterized in that: comprise the following steps:

Step 1: when wind direction changes, judge whether wind vector angle θ is less than blower fan limits of error angle θ _dmaxif, θ < θ _dmax, go to next step; Otherwise after making blower fan orderly closedown, carry out again yaw maneuver, then make blower fan normally start;

Step 2: judge whether θ exceeds the interval corresponding setting threshold angle θ of wind speed _d, as θ > θ _dtime, go to next step; Otherwise this θ changes without going off course;

Step 3: time lag T when the next wind direction of Prediction distance changes and the size of the wind speed in time lag T V, calculate the generated energy W under this predicted condition _optimize, the generated energy W after going off course _{threshold value}and C _{driftage cost}, then according to result of calculation, judge whether this wind vector goes off course, if driftage goes to step 6; Otherwise go to next step;

Step 4: while not going off course, whether time lag T when the next wind direction of judging distance changes occurs to change for the second time, if described T occurs to change for the second time, this θ changes without going off course; Otherwise go to next step;

Step 5: judge whether wind direction changes in the time at T+ Δ t, wherein Δ t is for exceeding prediction wind vector spacing movement set time, if wind direction changes in the time at T+ Δ t, this θ changes without going off course; Otherwise go to next step;

Step 6: wind speed driftage time delay T _dyaw system starts operation, if gone off course, whole driftage process finishes; Otherwise yaw system restarts operation, until the whole driftage process of having gone off course.

2. the controlling method of wind driven generator yaw system according to claim 1, is characterized in that: in described step 3, if W _optimize+ C _{driftage cost}-W _{threshold value}< 0, and yaw motor carries out driftage process.

3. the controlling method of wind driven generator yaw system according to claim 1, is characterized in that: before described step 1, yaw system is controlled to start and to wind constraint conditio is:

Wherein: ρ is air density; R is blade radius; V _tfor prediction of wind speed; for blower fan transformation efficiency; for fluctuation threshold value; C _vtfor wind speed V _tcorresponding power coefficient; θ is wind vector angle; T _sfor driftage time delay; T is the time lag between twice wind vector; (A+f (θ)) is driftage cost; F (θ) is and wind vector angle θ relative section.