ONLINE INDIRECT MEASUREMENT METHOD FOR PITCHING AND YAWING MOMENTS OF WIND OR TIDAL CURRENT TURBINE

Abstract

An online indirect measurement method for pitching and yawing moments of a wind or tidal current turbine is provided. The method uses an online indirect measurement system including an incoming flow velocity measurement module, a generator rotation speed measurement module, a pitch angle measurement module, and a computer; the incoming flow velocity measurement module measures the flow velocity of the rotor center; the generator rotation speed measurement module measures the generator rotation speed; the pitch angle measurement module measures the pitch angle of each blade; the computer receives signals of flow velocity, generator rotation speed, and pitch angle, obtains the pitching moment and yawing moments of the turbine via an online calculation, and displays and stores the measured and calculated data in real time.

Claims

1. An online indirect measurement method for pitching and yawing moments of wind or tidal current turbine, wherein the online indirect measurement method adopts an online indirect measurement system for the pitching and yawing moments of the wind or tidal current turbine, the system comprises an incoming flow velocity measurement module, a generator rotation speed measurement module, a pitch angle measurement module, and a computer; the incoming flow velocity measurement module is used to measure a flow velocity at a center of the turbine rotor, the generator rotation speed measurement module is used to measure a rotation speed of the turbine generator, and the pitch angle measurement module is used to measure a pitch angle of each blade of the rotor, and the incoming flow velocity measurement module, the generator rotation speed measurement module, and the pitch angle measurement module all implement a serial communication connection with the computer via communication cables to respectively transmit signals of the flow velocity, the rotation speed, and the pitch angle to the computer, wherein the method comprises the following steps: step 1) constructing a three-dimensional (3D) model of the turbine blade by using a 3D modeling software, and obtaining the position coordinate of an equivalent loading point of force applied to the blade via a 3D simulation analysis, and calculating a distance between the equivalent loading point and the rotor center; step 2) transmitting the measured flow velocity signal, rotation speed signal, and pitch angle signal to the computer respectively via the incoming flow velocity measurement module, the generator rotation speed measurement module, and the pitch angle measurement module; step 3) performing a filtering processing on the received flow velocity signal, rotation speed signal, and pitch angle signal via the computer to remove noise interferences; and calculating the pitching moment and the yawing moment of the wind or tidal current turbine in real time according to the distance between the equivalent loading point and the rotor center obtained by the simulation in step 1), and according to filtered data of the flow velocity, generator rotation speed, and the pitch angle of each blade; step 4) displaying the data of flow velocity, the generator rotation speed, and the pitch angle of each blade measured in step 2), and the calculated pitching moment and yawing moment in step 3) in real time via a monitoring interface and storing all of the above via the computer; step 3) is specifically: 3.1) performing integration the generator rotation speed and adding it to the initial azimuth angle .sub.i of each blade to obtain the current blade azimuth angle .sub.i of each blade, where i=1, 2N, and Nis the total number of the blades, and a specific formula is: ${}_i={}_i^{}+\underset{0}{\overset{t}{}}\frac{}{n}\mathrm{dt}$ where n is the gearbox ratio of the turbine, and t is the system operating time; 3.2) calculating the flow velocity v.sub.i of each blade at the equivalent point of force applied to the blade based on the flow shear formula, according to the flow velocity v.sub.s of the rotor center, the current azimuth angle .sub.i of each blade, and the distance r.sub.c between the equivalent point and the rotor center, specifically: $v_i=v_s.Math.{\left(\frac{z_h}{z_s}\right)}^{}$ where v.sub.i is the flow velocity at the equivalent loading point, z.sub.h is a vertical distance of the equivalent loading point from a ground or a seabed level, z.sub.s is a vertical distance of the rotor center from the ground or the seabed level, v.sub.s is the flow velocity of the rotor center, and is a shear coefficient; 3.3) calculating a blade tip speed ratio according to the generator rotation speed and the flow velocity v.sub.s of the rotor center, and a specific formula is: $=\frac{R}{n{v}_s}$ where R is a distance between a blade tip and the rotor center; calculating a rotor thrust coefficient C.sub.T via a blade element-momentum theory according to the blade tip speed ratio and a pitch angle .sub.i; of each blade measured by the pitch angle measurement module; and calculating a rotor thrust T according to the rotor thrust coefficient C.sub.T and the flow velocity v.sub.s of the rotor center, and a specific calculation formula is: $T=\frac{1}{2}{C}_{T}s{v}_s^2$ wherein in the formula, is an air density or a seawater density, and s is a rotor sweep area; 3.4) calculating a non-axial moment M.sub.yi of each blade, and a specific calculation formula is: $M_{yi}=\frac{v_i^2}{3v_s^2}T{r}_c$ 3.5) decomposing the non-axial moments M.sub.yi of all blades along a pitch direction and a yaw direction and summing them separately to obtain a pitching moment M.sub.tilt and a yawing moment M.sub.yaw of the rotor, and a specific calculation formula is: $\{\begin{array}{c}{M}_{\mathrm{tilt}}=\underset{i=1}{\overset{N}{.Math.}}{M}_{\mathrm{yi}}\sin {}_i\\ M_{\mathrm{yaw}}=\underset{i=1}{\overset{N}{.Math.}}{M}_{\mathrm{yi}}\cos {}_i\end{array}.$

2. The online indirect measurement method for pitching and yawing moments of the wind or tidal current turbine according to claim 1, wherein in step 3.1), a two-dimensional coordinate system with a turbine hub as an origin is constructed, wherein an x-axis and a y-axis are both located on a rotor rotation plane, the x-axis represents a horizontal axis on the rotor rotation plane, and the y-axis is a vertical axis on the rotor rotation plane; a blade azimuth angle refers to the rotation angle of the blade relative to the x-axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 is a schematic structural diagram of the system of the invention.

[0037] FIG. 2 is a schematic flowchart of the method of the invention.

[0038] FIG. 3 is a layout diagram of an embodiment of the system of the invention on the wind turbine.

[0039] FIG. 4 is a schematic structural diagram of the three-dimensional model of the turbine blade of the invention.

[0040] FIG. 5 is a layout diagram of an embodiment of the system of the invention on the tidal current turbine.

DESCRIPTION OF THE EMBODIMENTS

[0041] The invention is further described in detail below with reference to the accompanying drawings and specific embodiments. However, it should be noted that the invention is not limited to the following specific embodiments.

Embodiment 1

[0042] Referring to FIG. 1 and FIG. 3, the present embodiment provides an online indirect measurement system for pitching and yawing moments of a wind turbine, including an incoming flow velocity measurement module 1, a generator rotation speed measurement module 2, a pitch angle measurement module 3, and a computer 4. In particular, the incoming flow velocity measurement module 1 is used to measure the wind speed at the rotor center of the wind turbine; the generator rotation speed measurement module 2 is used to measure the generator rotation speed; the pitch angle measurement module 3 is used to measure the pitch angle of each blade; the computer 4 is used to receive the flow velocity signal, rotation speed signal, and pitch angle signal, and obtain the pitching moment and the yawing moment of the wind turbine via online real-time calculating and processing, and display and store the measurement and calculation data in real time.

[0043] The incoming flow velocity measurement module 1 adopts an anemometer arranged outside the wind turbine and fixed at the top of the nacelle.

[0044] The generator rotation speed measurement module 2 is arranged at the high-speed shaft of the gearbox inside the turbine nacelle 6; the pitch angle measurement module 3 is arranged at the pitch change device inside the turbine hub 7. The generator rotation speed measurement module 2 and pitch angle measurement module 3 are both located inside the turbine and remain relatively stationary. Therefore, the mounting is easy and the measurement reliability is high.

[0045] The incoming flow velocity measurement module 1, generator rotation speed measurement module 2, and pitch angle measurement module 3 are all connected to the computer 4 via communication cable 5, enabling serial communication. They respectively transmit the flow velocity signal, rotation speed signal, and pitch angle signal to the computer 4.

[0046] Referring to FIG. 2, this embodiment provides an online indirect measurement method for pitching and yawing moments of a wind turbine adopting the above online indirect measurement system for pitching and yawing moments of the wind turbine. The steps are as follows: [0047] step 1) according to the blade design parameters of the wind turbine, a three-dimensional model of the wind turbine blades is established in the ANSYS Workbench software on the computer 4, as shown in FIG. 4. The three-dimensional simulation analysis is conducted, taking into account the blade's airfoil, mass distribution, and other characteristics. This analysis yields the coordinates of the equivalent loading points on the blades and calculates the distance between the equivalent loading points and the center of the rotor; [0048] step 2) the incoming flow velocity measurement module 1, generator rotation speed measurement module 2, and pitch angle measurement module 3 are connected to the computer 4 via serial communication. During the actual operation of the turbine, the wind speed of the rotor center, the generator rotation speed, and the pitch angle of each blade are measured in real time. Subsequently, the signals for the wind speed, rotation speed, and pitch angle are transmitted to the computer 4; [0049] step 3) the computer 4 receives the wind speed signal, rotation speed signal, and pitch angle signal transmitted by the modules in step 2), and applies filtering to remove noise interference. Utilizing the distance between the equivalent loading points on the blades and the rotor center obtained from the simulation in step 1), as well as the filtered wind speed, generator rotation speed, and pitch angle data, the computer 4 performs real-time calculations to determine the pitching moment and the yawing moment of the wind turbine; [0050] the calculation process of the pitching moment and the yawing moment is as follows:

[0051] 3.1) The generator rotation speed measured by the generator rotation speed measurement module 1 is integrated and then added to the initial azimuth angle .sub.i0 of each blade, resulting in the current azimuth angle .sub.i of each blade. The wind turbine of this present embodiment is designed with three blades, and the value of i ranges from {1, 2, 3};

[00007]${}_i={}_i^{}+\underset{0}{\overset{t}{}}\frac{}{n}\mathrm{dt}$ [0052] where n is the gearbox ratio of the turbine, and t is the system operating time; [0053] a two-dimensional coordinate system with the turbine hub as the origin is constructed, wherein the x-axis and y-axis are both located on the rotor rotation plane, the x-axis represents the horizontal axis on the rotor rotation plane, and the y-axis is the vertical axis on the rotor rotation plane. The blade azimuth angle refers to the rotation angle of the blade relative to the x-axis.

[0054] 3.2) According to the wind speed v.sub.s measured at the rotor center by the incoming flow velocity measurement module 2, as well as the current azimuth angle .sub.i of each blade and a distance r.sub.c between the equivalent loading point and the rotor center, the wind speed v.sub.i at the equivalent loading point of each blade is calculated. The calculation method is based on the shear flow formula:

[00008]$v_i=v_s.Math.{\left(\frac{z_h}{z_s}\right)}^{}$

[0055] In the equation, z.sub.h is the height above the ground of the desired location, v.sub.i is the wind speed at the desired location, z.sub.s is the height above the ground of the rotor center, v.sub.s is the wind speed at the rotor center, and is the shear coefficient. The desired location refers to the equivalent force application point of the desired blade.

[0056] When the distance between the equivalent loading points of the blades and the rotor center, the height of the rotor center above the ground, and the current azimuth angle .sub.i of each blade are known, the height z.sub.h of the equivalent loading point above the ground can be obtained via trigonometric transformations.

[0057] 3.3) According to the generator rotation speed and the wind speed v.sub.s of the rotor center, a blade tip speed ratio is calculated. The specific formula is:

[00009]$=\frac{R}{n{v}_s}$ [0058] where R is the distance between the blade tip and the rotor center.

[0059] According to the blade tip speed ratio and the pitch angle .sub.i of each blade measured by the pitch angle measurement module, a rotor thrust coefficient C.sub.T is calculated via the blade element-momentum theory. According to the thrust coefficient C.sub.T and the wind speed v.sub.s of the rotor center, the rotor thrust T is calculated. The calculation formula is:

[00010]$T=\frac{1}{2}{C}_{T}s{v}_s^2$ [0060] where is the air density, and s is the rotor sweep area.

[0061] 3.4) The non-axial moment M.sub.yi of the blade i is calculated. The calculation formula is:

[00011]$M_{yi}=\frac{v_i^2}{3v_s^2}T{r}_c$

[0062] 3.5) The non-axial moments M.sub.yi of three blades are decomposed along the pitch direction and the yaw direction and summing them respectively to obtain the pitching moment M.sub.tilt and the yawing moment M.sub.yaw of the rotor. The calculation formula is:

[00012]$\{\begin{array}{c}{M}_{\mathrm{tilt}}=\underset{i=1}{\overset{3}{.Math.}}{M}_{\mathrm{yi}}\sin {}_i\\ M_{\mathrm{yaw}}=\underset{i=1}{\overset{3}{.Math.}}{M}_{\mathrm{yi}}\cos {}_i\end{array}$

[0063] Step 4) the computer 4 takes the measured data of wind speed, generator rotation speed, and pitch angle obtained in step 2), as well as the calculated pitching moment and yawing moment in step 3), and displays them in real-time on the monitoring interface. Additionally, all the data is stored.

Embodiment 2

[0064] Referring to FIG. 1, FIG. 2, and FIG. 5, this embodiment provides an online indirect measurement system and method for pitching and yawing moments of a tidal current turbine.

[0065] In this embodiment, the provided online indirect measurement system for pitching and yawing moments of the tidal current turbine is essentially similar to the one in Embodiment 1. The difference lies in the following aspects: the incoming flow velocity measurement module 1 is used to measure the tidal current velocity at the center of the tidal current turbine rotor; the incoming flow velocity measurement module 1 employs a current velocity and direction meter, which is positioned at an appropriate distance ahead of the center point of the tidal energy turbine rotor in the direction of the flow.

[0066] In this embodiment, the provided online indirect measurement method for pitching and yawing moments of the tidal current turbine is essentially similar to the one in Embodiment 1. The difference lies in the following aspects: a three-dimensional model of the tidal current turbine blades for simulation analysis is established; the wind speed readings, calculations, displays, and storage is replaced with tidal current velocity; during the calculation process, z.sub.h is the vertical distance of the desired point from the seabed level, z.sub.s is the vertical distance of the rotor center from the seabed level, and p is the seawater density.

[0067] The above description only outlines the basic principles and preferred embodiments of the invention. Any modifications, equivalent substitutions, and improvements, etc. made within the spirit and principles of the invention are all included in the scope of the invention.