Wind generating set power curve correction and generating capacity prediction method

Abstract

The invention discloses a wind generating set power curve correction and generating capacity prediction method, which comprises the following steps: 1, obtaining test stage data P1, rhoH1, alpha1 and H1 according to a power curve f (P1, V) corresponding to the average wind speed of a wind generating set; 2, according to the position condition of the wind generating set to be built, actual data H2, rhoH2 and alpha2 are obtained through measurement; 3, calculating the corrected field wind speed corresponding power P2 of the field state wind generating set through MATLAB software; 4, the step 3 is executed repeatedly, and a data set A including a series of fan output power pn corresponding to the average wind speed # imgabs0 # is formed; 5, screening the data set A, and processing unreasonable data groups to obtain a data set B; 6, obtaining a new field wind resource condition power curve f (P2, V) according to the data set B; and 7, predicting the generating capacity within the required time according to the new power curve # imgabs1 #. The influence of different test environment and actual wind power plant environment is eliminated.

Description

Technical Field

[0001] The invention relates to the field of computer-aided technology, and in particular to a method for correcting a power curve of a wind turbine generator set and predicting power generation. Background Art

[0002] The power curve refers to the corresponding curve of the wind turbine output power and wind speed. It is a graph that depicts the functional relationship between the wind turbine power output and wind speed. In the prior art, the curve of the average wind speed at the hub height of the wind turbine corresponding to the output power is generally used. Therefore, the current wind turbine power generation is calculated by following the curve of the average wind speed at the hub height corresponding to the theoretical power of the wind turbine under a certain air density, obtaining the power at the wind speed, and accumulating it over a period of time to obtain the power generation:

[0003]

[0004] Among them, E is the power generation, the unit is Wh; P is the wind turbine power output, the unit is W; V is the wind speed, the unit is m / s; f(P,V) is the functional relationship between the average wind speed and the theoretical power of the wind turbine.

[0005] The existing power curve reflects the power corresponding to the average wind speed at the hub height, ignoring the fact that factors such as hub height and wind shear during the test phase are different from those in the actual field, resulting in different actual wind energy captured by the unit under the same average wind speed, which leads to changes in wind turbine output and makes the power curve inapplicable in the actual field. Ultimately, the power generation results calculated by the power curve corresponding to the average wind speed at the hub height during the current test phase have certain limitations.

[0006] Therefore, how to correct the existing theoretical average wind speed corresponding power curve into a power curve corresponding to the project site wind speed has become a technical problem that technical personnel in this field need to solve urgently. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, the present invention provides a method for correcting the power curve of a wind turbine and predicting power generation, the purpose of which is to correct the existing power curve corresponding to the theoretical average wind speed to the power curve corresponding to the project site wind speed, and predict the power generation through the new power curve.

[0008] To achieve the above object, the present invention discloses a method for correcting a power curve of a wind turbine generator set and predicting power generation, comprising the following steps:

[0009] Step 1: According to the power curve f(P1,V) corresponding to the average wind speed of the wind turbine generator set, the output power P1 of the wind turbine generator set at the average wind speed at the hub height during the test phase and the corresponding wind speed, as well as the air density ρ corresponding to the power curve are obtained. H1, wind shear index α1 during the test phase, wind turbine height H1 during the test phase;

[0010] Step 2: According to the location conditions of the wind turbine to be built, measure the actual hub height H2 and the corresponding actual air density ρ H2 and the actual wind shear index α2 during the corresponding wind speed period;

[0011] Step 3, according to the wind energy formula, calculate the wind energy in the test phase obtained in the swept surface of the impeller under the average wind speed at the hub height during the test phase, then calculate the real wind energy obtained in the swept surface of the impeller under any period of the same average wind speed on site, establish a mathematical model of the corresponding wind energy utilization coefficient, and calculate the power P2 corresponding to the corrected on-site wind speed of the wind turbine generator set in the on-site state through MATLAB software;

[0012] Step 4: Repeat step 3 to obtain the corrected wind speed corresponding power of the wind turbine generator set at the same average wind speed period at the site, forming a series of wind speed corresponding power. The corresponding fan output power p n Dataset A;

[0013] Step 5: According to the operating characteristics of the wind turbine generator set at different average wind speeds, the data set A is screened, and unreasonable data sets are processed to obtain data set B;

[0014] Step 6: Arrange the data set B to obtain a new on-site wind resource situation power curve f(P2,V);

[0015] Step 7: Power curve according to the new on-site wind resource situation Predict the amount of power generated over the required time.

[0016] Preferably, in step 3, the calculation formula of the power P2 corresponding to the corrected on-site wind speed of the wind turbine generator set in the on-site state is as follows:

[0017]

[0018] Wherein, R is the impeller radius of the wind turbine generator set, in m;

[0019] e is a natural constant;

[0020] z is any height within the swept surface of the wind turbine rotor, in m;

[0021] π is the ratio of a circle to its circumference.

[0022] Preferably, step 5 is as follows:

[0023] When any of the wind turbine output power p in the data set A nWhen it is greater than 0 and less than or equal to the rated power, the corresponding fan output power p n and the corresponding average wind speed All of them are reasonable data and are retained in the data set B;

[0024] When any of the wind turbine output power p in the data set A n When the power is greater than the rated power, the corresponding fan output power p n The vertical is replaced with the rated power.

[0025] Beneficial effects of the present invention:

[0026] The present invention does not need to add complicated calculation and measurement steps, and directly corrects the theoretical power curve corresponding to the average wind speed at the hub height, corrects the wind speed corresponding power curve of the test environment to the wind speed corresponding power curve under the wind resource conditions of the project site, and finally calculates the power generation.

[0027] The present invention eliminates the influence of the difference between the test environment and the actual wind farm environment, and obtains a more accurate theoretical power generation result of the wind farm.

[0028] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart showing an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0030] Example

[0031] like Figure 1 As shown, the method for correcting the power curve of a wind turbine generator set and predicting power generation includes the following steps:

[0032] Step 1: According to the power curve f(P1,V) corresponding to the average wind speed of the wind turbine generator set, the output power P1 of the wind turbine generator set at the average wind speed at the hub height during the test phase and the corresponding wind speed, as well as the air density ρ corresponding to the power curve are obtained. H1 , wind shear index α1 during the test phase, wind turbine height H1 during the test phase;

[0033] Step 2: According to the location conditions of the wind turbine to be built, measure the actual hub height H2 and the corresponding actual air density ρ H2 and the actual wind shear index α2 during the corresponding wind speed period;

[0034] Step 3: According to the wind energy formula, calculate the wind energy in the test phase obtained within the swept surface of the impeller under the average wind speed at the hub height during the test phase, and then calculate the actual wind energy obtained within the swept surface of the impeller under any period of the same average wind speed on site, establish a mathematical model for the corresponding wind energy utilization coefficient, and calculate the power P2 corresponding to the corrected on-site wind speed of the wind turbine generator set in the on-site state through MATLAB software;

[0035] Step 4: Repeat step 3 to obtain the corrected wind speed corresponding power of the wind turbine generator set at the same average wind speed period at the site, forming a series of wind speed corresponding power. The corresponding fan output power p n Dataset A;

[0036] Step 5: According to the operating characteristics of the wind turbine generator set at different average wind speeds, the data set A is screened, and the unreasonable data sets are processed to obtain the data set B;

[0037] Step 6: Arrange the data set B to obtain a new on-site wind resource situation power curve f(P2,V);

[0038] Step 7: Power curve according to the new on-site wind resource situation Predict the amount of power generated over the required time.

[0039] In some embodiments, in step 3, the calculation formula of the power P2 corresponding to the corrected on-site wind speed of the wind turbine generator set in the on-site state is specifically as follows:

[0040]

[0041] Wherein, R is the impeller radius of the wind turbine generator set, in m;

[0042] e is a natural constant;

[0043] z is any height within the swept surface of the wind turbine rotor, in m;

[0044] π is the ratio of a circle to its circumference.

[0045] In some embodiments, step 5 is as follows:

[0046] When the output power p of any wind turbine in data set A n When it is greater than 0 and less than or equal to the rated power, the corresponding fan output power p n and the corresponding average wind speed All of them are reasonable data and are retained in data set B;

[0047] When the output power p of any wind turbine in data set A n When the power is greater than the rated power, the corresponding fan output power pn The vertical is replaced with the rated power.

[0048] The principle of the present invention is as follows:

[0049] 1. Wind energy utilization coefficient

[0050] The wind energy utilization coefficient of a wind turbine is the ratio of the wind turbine's output power to the wind energy obtained within the rotor's swept area. The wind energy utilization coefficient is represented by Cp, and it mainly depends on the aerodynamics, structural design and manufacturing process level of the rotor blades. Its specific expression is as follows:

[0051]

[0052] Where, W is wind energy, kg·m 2 ·s -3 .

[0053] 2. Wind energy

[0054] The utilization of wind energy is mainly to convert the kinetic energy of wind into other forms of energy. Therefore, the calculation of wind energy is to calculate the kinetic energy of the airflow flowing through the cross-sectional area perpendicular to the wind speed in unit time. The formula is as follows:

[0055]

[0056] 3. Air density

[0057] At a certain temperature and pressure, the mass of each cubic meter of air is the air density. In the field of wind power, air density is generally calculated using the annual average temperature and annual average air pressure of the wind tower in the wind farm, and then derived to the height of the wind turbine hub through a formula based on the altitude difference between the wind farm and the wind tower. The formula is as follows:

[0058] ρ z =ρ h e -0.0001(z-h)

[0059] In the formula, ρ z ——Air density at any height z, kg·m -3 ρ h ——The air density at the actual observation height h, kg·m -3 , h——actual observation height, m.

[0060] 4. Wind shear

[0061] Wind shear is an atmospheric phenomenon, which refers to the change of wind vector (wind direction, wind speed) in horizontal and / or vertical distance in the air. In the field of wind power, wind shear mainly refers to the change of horizontal wind speed in vertical height in the atmospheric boundary layer.

[0062] The wind shear index characterizes how quickly the wind speed changes with height. The larger the wind shear index, the more the wind speed increases with height. If the wind speed profile is described by a power law equation, then the power law index is the wind shear index. The role of the wind shear index, in simple terms, is to infer the wind speed at other unknown heights through the wind speed at different heights measured by the wind measuring equipment, thereby providing a basis for wind turbine selection, power generation and rate of return calculation. When there are only wind speed data at two heights, the wind shear power law formula is as follows:

[0063]

[0064] Wherein, V2 is the wind speed at height Z2, m / s; V1 is the wind speed at height Z1, m / s.

[0065] 5. Impeller swept area

[0066] The impeller swept area refers to the projected area of ​​the circle generated by the movement of the blade tip when the fan impeller rotates, which is perpendicular to the wind vector plane. It is one of the important indicators to measure the performance of wind turbines. The impeller swept area affects the power generation capacity and efficiency of the generator. The larger the impeller swept area, the greater the wind force on the rotating impeller, thus generating more electricity.

[0067] For a wind turbine with a rotor radius of R, it is easy to obtain the swept area of ​​the rotor:

[0068] S=πR 2

[0069] In the formula, π is the ratio of a circle to a circle.

[0070] 6. Formula derivation

[0071] The hub height of the wind turbine is H, and the rotor radius is R. The chord length corresponding to any height z is:

[0072]

[0073] Where c(z) is the chord length corresponding to any height z within the impeller swept surface, m.

[0074] Since the area of ​​a circle can be regarded as the accumulation of chord lengths, the entire impeller swept area is the integral of the chord lengths at each height, as shown in the following formula:

[0075]

[0076] When the swept surface of the wind wheel is infinitely divided, the impeller area corresponding to each layer height z can be considered as the chord length of the height multiplied by the height of the segment, and the result is:

[0077]

[0078] Where, S(z) is the area corresponding to any height z within the impeller swept surface, m 2 .

[0079] It can be seen from the above formulas that for any height z, when the segment is infinitely divided, the wind speed, air density, and impeller swept area are all functions of the corresponding height z within the impeller swept surface. Therefore, using the wind energy formula (4), substituting into the formulas (5), (6), and (10) for the variation of air density, wind shear, and impeller area with height, the wind energy obtained at any height z within the impeller swept surface can be considered as follows:

[0080]

[0081] Where W z ——Wind energy obtained at any height z within the impeller swept surface, kg·m 2 ·s -3 .

[0082] The wind energy obtained in the entire wind rotor swept surface is the accumulation of all heights in the wind rotor swept surface:

[0083]

[0084] Substituting into formula (3) we get:

[0085]

[0086] That is, the current theoretical power generation of a wind turbine is obtained by accumulating the power at the wind speed corresponding to the theoretical power curve of the wind turbine according to the average wind speed at the hub height over a period of time.

[0087] In the test and simulation stage, the power corresponding to the wind speed at a certain hub height of the wind turbine generator set is obtained, and the power at multiple wind speeds is combined to obtain the power curve:

[0088] f(P1,V)=P

[0089] Since it was not considered that the wind energy obtained by the wind turbine generator set under the same wind speed at the hub height is not consistent, resulting in calculation errors, it is necessary to transform the theoretical power curve corresponding to the average wind speed at the hub height. Since the wind energy utilization coefficient is controlled according to the two parameters of the tip speed ratio and the pitch angle during the operation of the unit, and is related to the average wind speed at the hub height, the wind energy utilization coefficient is actually controlled consistently under the same average wind speed at the hub height. Substituting formulas (4), (13), and (14) into formula (15) is as follows:

[0090]

[0091] The power curve of each average wind speed section is corrected to obtain a new power curve f(P2,V)=P; according to the corrected new power curve, the power generation within a period of time is calculated as follows:

[0092]

[0093] The present invention corrects the existing theoretical average wind speed corresponding power curve to the project site wind speed corresponding power curve through the theoretical reasoning process of wind turbine output power, and calculates the power generation through the new power curve. The rationality of formula derivation and calculation accuracy are more accurate than the original formula, which improves the calculation accuracy of power generation of projects with different wind resource conditions.

[0094] Take a fan with a rated power of 5MW and an impeller diameter of 200m from a certain manufacturer as an example. The fan has an air density of 1.225kg·m -3 , when the average wind speed at the hub height is 6m / s, the theoretical output power is 1869kW. Assuming the hub height is 140m, the standard wind shear during the test phase is 0.2. If the existing method of calculating the power generation by the theoretical power curve corresponding to the average wind speed at the hub height is used, as long as the average wind speed is the same during the calculation period, the wind turbine output is exactly the same under different wind shears and hub heights, which is inconsistent with the theoretical results. Assuming that the average wind speed at the hub height at the project site is 6m / s within one hour (the wind speed distribution is consistent with the test phase), and the air density at the hub height remains unchanged, the deviation analysis of the power generation results obtained by the original method and the new method is performed, and the results are shown in the following table:

[0095]

[0096]

[0097] It is obvious that after considering the change of wind speed and air density with height in the swept area of ​​the impeller and the change of hub height at the project site and the test stage, there is a large deviation between the original power curve and the power generation calculated by the new method. When the wind shear is 2 / 3 and the hub height is 115m, the power generation calculated by the existing method underestimates the power generation by about 17%.

[0098] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. Wind turbine power curve correction and power generation prediction method; It is characterized in that The steps include: Step 1: According to the power curve f(P 1 , V), and obtain the average wind speed at the hub height during the test phase and the output power P of the wind turbine generator set at the corresponding wind speed 1 , and the air density ρ corresponding to the power curve H1 , wind shear index α during the test phase 1 , fan height H during the test phase 1 ; Step 2: Measure the actual hub height H according to the location conditions of the wind turbine to be built. 2 , and the corresponding actual air density ρ H2 and the actual wind shear index α in the corresponding wind speed period 2 ; Step 3: According to the wind energy formula, calculate the wind energy obtained in the swept surface of the impeller under the average wind speed at the hub height during the test phase, and then calculate the actual wind energy obtained in the swept surface of the impeller under any period of the same average wind speed on site, establish a mathematical model for the corresponding wind energy utilization coefficient, and calculate the power P corresponding to the corrected on-site wind speed of the wind turbine generator set in the on-site state through MATLAB software. 2 ; Step 4: Repeat step 3 to obtain the corrected wind speed corresponding power of the wind turbine generator set at the same average wind speed period at the site, forming a series of wind speed corresponding power corresponding to the average wind speed v. n The corresponding fan output power p n Dataset A; Step 5: According to the operating characteristics of the wind turbine generator set at different average wind speeds, the data set A is screened, and unreasonable data sets are processed to obtain data set B; Step 6: Arrange the data set B to obtain a new on-site wind resource situation power curve f(P 2 ,V); Step 7: Power curve according to the new on-site wind resource situation Predict the amount of power generated over the required time.

2. The method for correcting the power curve and predicting the power generation of a wind turbine generator set according to claim 1, It is characterized in that In step 3, the corrected on-site wind speed corresponding to the power P of the wind turbine generator set at the on-site state 2 The calculation formula is as follows: Wherein, R is the impeller radius of the wind turbine generator set, in m; e is a natural constant; z is any height within the swept surface of the wind turbine rotor, in m; π is the ratio of a circle to its circumference.

3. The method for correcting the power curve and predicting the power generation of a wind turbine generator set according to claim 1, It is characterized in that Step 5 is as follows: When any of the wind turbine output power p in the data set A n When it is greater than 0 and less than or equal to the rated power, the corresponding fan output power p n and the corresponding average wind speed v n All of them are reasonable data and are retained in the data set B; When any of the wind turbine output power p in the data set A n When the power is greater than the rated power, the corresponding fan output power p n The vertical is replaced by the rated power.

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