A method for controlling the power of a variable speed wind turbine generator set based on slip

Abstract

The present invention discloses a method for controlling the power of a variable-speed wind generator set based on slip, wherein a main controller of the wind generator set creates a slip control curve, and a slip controller realizes power control of the wind generator set based on the slip control curve, wherein the two-dimensional coordinate correspondence between the rotation speed of the wind generator set and its power is determined by the slip control curve; the present invention can improve the control effect of the wind generator set on stable rotation speed regulation and stable power output, and at the same time, the slip control curve is automatically and dynamically adjusted through the slip power limit control, thereby meeting the power limit control requirement for the wind generator set.

Description

Technical Field

[0001] The invention belongs to the field of wind power generation, and in particular relates to a method for controlling the power of a variable-speed wind power generator set based on slip. Background Art

[0002] In the field of wind power generation, variable pitch constant speed asynchronous wind turbines usually include variable speed wind turbines with slip control systems. Figure 1 As shown, the variable speed wind turbine generator set with slip control system mainly includes (wound rotor) asynchronous generator a. When in operation, the stator end of asynchronous generator a is always connected to the power grid b, and the rotor end of asynchronous generator a is connected to the variable slip system c through a slip ring. The asynchronous generator a starts by rotating the blade d to achieve the optimal blade angle and accelerate the rotor; when the speed of the asynchronous generator has reached the synchronous speed, the surge current is controlled by the soft starter e to achieve grid connection, and the bypass contactor f is turned on and the soft starter e is bypassed, so that the asynchronous generator a is directly connected to the power grid b.

[0003] Specifically, the control of a variable-speed wind turbine with a slip control system includes pitch control and slip control. The two controls work together to achieve dynamic optimal stability. Pitch control is an open-loop control based on achieving a target speed at a certain wind speed as the control working point target, and is a slow-speed regulation control; while slip control is a closed-loop control based on the wind turbine being in a dynamically optimal stable state around the target speed as the control working point target, and is a fast-speed regulation system.

[0004] However, since the slip control used in the prior art is usually based on a pre-set slip control curve, it is impossible to achieve automatic dynamic adjustment. From a practical application perspective, this will result in the wind turbine generator set being unable to achieve limited power operation control, which also causes the slip control scheme to be subject to more application restrictions.

[0005] Based on the long-term and dedicated research of the applicant and the applicant's R&D team in the field of wind power generation control, we hope to find a technical solution to solve the above technical problems. Summary of the invention

[0006] In view of this, the purpose of the present invention is to propose a method for controlling the power of a variable-speed wind turbine generator set based on slip, which can improve the control effect of the wind turbine generator set on stable speed regulation and smooth power output. At the same time, the slip control curve is automatically and dynamically adjusted through the slip limited power control, thereby meeting the power limit control requirements of the wind turbine generator set.

[0007] To this end, the technical solution adopted in the present invention is as follows:

[0008] A method for controlling the power of a variable-speed wind generator set based on slip, wherein a main controller of the wind generator set creates a slip control curve, and a slip controller implements power control of the wind generator set based on the slip control curve, wherein the two-dimensional coordinate correspondence between the rotation speed of the wind generator set and its power is determined by the slip control curve.

[0009] Preferably, the main controller sends a slip control curve signal to the slip controller via communication.

[0010] Preferably, the main controller creates the slip control curve by taking the stable power output of the wind turbine generator set as a control target.

[0011] Preferably, the slip control curve introduces a slip power limit control, and the slip control curve is automatically and dynamically adjusted through the slip power limit control to meet the power limit control requirement for the wind turbine generator set.

[0012] Preferably, the slip-limited power control comprises: in the slip control curve, respectively determining at least one power constant coordinate point corresponding to the minimum speed range and at least one power constant coordinate point corresponding to the maximum speed range; and based on the target of the limited power control, determining a first straight line, a second straight line and a third straight line respectively passing through the coordinate zero point and whose slopes increase successively, and a fourth straight line intersecting with the first straight line and a fifth straight line intersecting with the second straight line, the slope of the fourth straight line being greater than the slope of the third straight line and less than the slope of the fifth straight line; performing linear fitting on each power constant coordinate point, the intersection point of the first straight line and the fourth straight line, the intersection point of the fourth straight line and the fifth straight line, and the intersection point of the second straight line and the fifth straight line to obtain the slip control curve after the slip-limited power control.

[0013] Preferably, the power constant coordinate point corresponding to the maximum rotation speed range is located on the fifth straight line.

[0014] Preferably, the minimum speed range corresponds to the first power constant coordinate point and the second power constant coordinate point, respectively, and the maximum speed range corresponds to the third power constant coordinate point.

[0015] Preferably, (rotation speed reference value nref, power reference value Pref) is used as a coordinate point, and the coordinate point is used as the intersection point of the fourth straight line and the fifth straight line.

[0016] Preferably, the speed reference value nref is 1540-1580 rpm, and the power reference value Pref is 1400-1600 kW.

[0017] Preferably, the minimum speed range is 1500-1530rpm, the maximum speed range is 1700-1750rpm, wherein the power of the first power constant coordinate point is greater than 10kw and less than 50kw, the power of the second power constant coordinate point is greater than 150kw and less than 200kw, and the power of the third power constant coordinate point is not less than 1700kw.

[0018] It should be noted that the rotation speed of the (variable speed) wind turbine generator set referred to in the entire application refers to the target rotation speed of the generator; the power of the wind turbine generator set referred to refers to the output power of the generator.

[0019] The present application first proposes that a slip controller performs coordinated control of the power of a wind turbine based on a preset slip control curve, which can improve the control effect of the wind turbine on stable speed regulation and smooth power output; at the same time, the present application further creatively proposes that the slip control curve introduces a specific slip power limit control, through which the slip control curve is automatically and dynamically adjusted, thereby meeting the power limit control requirements for the wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the electrical connection structure of a known variable speed wind turbine generator set;

[0021] Figure 2 It is a schematic diagram of the connection structure of the controller of the variable speed wind turbine generator set in the specific implementation mode of the present application;

[0022] Figure 3 It is a diagram of the dynamic adjustment design process of the slip difference control curve in the specific implementation mode of the present application;

[0023] Figure 4 It is a comparison diagram of slip control curves before and after the slip limiting power control is introduced in the specific implementation mode of the present application. DETAILED DESCRIPTION

[0024] An embodiment of the present invention discloses a method for controlling the power of a variable-speed wind generator set based on slip, wherein a main controller of the wind generator set creates a slip control curve, and a slip controller implements power control of the wind generator set based on the slip control curve, wherein a two-dimensional coordinate correspondence between the rotation speed of the wind generator set and its power is determined by the slip control curve.

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] See also Figure 2 As shown, this embodiment proposes a variable speed wind turbine generator set (hereinafter referred to as: wind turbine generator set), including a main controller, a pitch controller, and a slip controller; the main controller outputs a target grid-connected speed set value to the pitch controller, and the slip controller outputs a slip control curve to the slip controller for coordinated control;

[0027] In this embodiment, the wind turbine generator set adopts the following control method:

[0028] A method for controlling the power of a variable-speed wind generator set based on slip, wherein a main controller of the wind generator set creates a slip control curve, and a slip controller implements power control of the wind generator set based on the slip control curve, wherein a two-dimensional coordinate correspondence between the rotation speed of the wind generator set and its power is determined by the slip control curve.

[0029] Preferably, in this embodiment, the main controller sends a slip control curve signal to the slip controller through a communication method (specifically, a two-way communication method can be used); further preferably, in this embodiment, the main controller creates a slip control curve with the stable power output of the wind turbine as the control target.

[0030] Preferably, in the present embodiment, the slip control curve introduces slip power limit control, and the slip control curve is automatically and dynamically adjusted by the slip power limit control to meet the power limit control requirements of the wind turbine generator set; further preferably, in the present embodiment, the slip power limit control includes: in the slip control curve, respectively determining at least one power constant coordinate point corresponding to the minimum speed range and at least one power constant coordinate point corresponding to the maximum speed range; at the same time, based on the target of power limit control, determining a first straight line, a second straight line and a third straight line respectively passing through the coordinate zero point and whose slopes increase successively, and a fourth straight line intersecting the first straight line, and a fifth straight line intersecting the second straight line, the slope of the fourth straight line is greater than the slope of the third straight line and less than the slope of the fifth straight line, and the power constant coordinate point corresponding to the maximum speed range (that is, the third power constant coordinate point described below) is located on the fifth straight line; performing linear fitting on each power constant coordinate point, the intersection point of the first straight line and the fourth straight line, the intersection point of the fourth straight line and the fifth straight line, and the intersection point of the second straight line and the fifth straight line to obtain the slip control curve after slip power limit control.

[0031] Further preferably, in the present embodiment, the minimum speed range corresponds to the first power constant coordinate point and the second power constant coordinate point, respectively, and the maximum speed range corresponds to the third power constant coordinate point; at the same time, (speed reference value nref, power reference value Pref) is used as the coordinate point, and the coordinate point is used as the intersection point of the fourth straight line and the fifth straight line; in actual implementation, technical personnel in this field can select the speed reference value nref and the power reference value Pref according to the actual required power limit requirements.

[0032] After implementation and verification, the following parameters are recommended for this application:

[0033] The speed reference value nref is 1540-1580rpm, and the power reference value Pref is 1400-1600kw; the minimum speed range is 1500-1530rpm, and the maximum speed range is 1700-1750rpm, wherein the power at the first power constant coordinate point is greater than 10kw and less than 50kw, the power at the second power constant coordinate point is greater than 150kw and less than 200kw, and the power at the third power constant coordinate point is not less than 1700kw.

[0034] Specifically preferably, this embodiment carries out the following specific implementation process:

[0035] See also Figure 3 and Figure 4 As shown, the horizontal axis is the speed of the wind turbine generator set ngen, in units of rpm; the vertical axis is the power of the wind turbine generator set P, in units of kw;

[0036] The first power constant coordinate point P1 = const, specifically (1500rpm, 23.1kw), the second power constant coordinate point P2 = const, specifically (1505rpm, 189.5kw), the third power constant coordinate point P6 = const, specifically (1725rpm, 1790.8kW); the speed reference value nref = 1545rpm, which is the synchronous speed of the wind turbine generator set; the power reference value Pref = 1500kw, which is the rated power of the wind turbine generator set; according to the power limit control requirements of the wind turbine generator set, the main controller of the wind turbine generator set is designed for matching and provides the corresponding The corresponding working area is determined according to the range of the working area, and the first straight line L1, the second straight line L2 and the third straight line L3 that pass through the coordinate zero point and whose slopes increase successively are determined. Combined with the intersection point P4=(nref, Pref) of the fourth straight line and the fifth straight line, specifically (1545rpm, 1500kw), the fourth straight line L4=(P4, slope4) and the fifth straight line L5=(P4, slope5) are determined, and then the intersection point P3=intersect(L1, L4) of the first straight line and the fourth straight line and the intersection point P5=intersect(L2, L5) of the second straight line and the fifth straight line are determined.

[0037] Linear fitting is performed on P1, P2, P3, P4, and P5 determined as above to obtain the slip control curve K after slip-limited power control and the slip control curve K without slip-limited power control. 0 Compared with the previous example, the slip control curve K is realized. 0 Automatic dynamic adjustment meets the power limit control requirements of wind turbines.

[0038] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0039] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for controlling the power of a variable speed wind turbine generator set based on slip, characterized in that: The main controller of the wind generator set creates a slip control curve, and the slip controller implements power control of the wind generator set based on the slip control curve, wherein the two-dimensional coordinate correspondence between the rotation speed of the wind generator set and its power is determined by the slip control curve; The slip control curve introduces a slip power limit control, through which the slip control curve is automatically and dynamically adjusted to meet the power limit control requirements of the wind turbine generator set; The slip-limited power control includes: in the slip control curve, respectively determining at least one power constant coordinate point corresponding to the minimum speed range and at least one power constant coordinate point corresponding to the maximum speed range; at the same time, based on the target of the limited power control, determining a first straight line, a second straight line and a third straight line respectively passing through the coordinate zero point and whose slopes increase successively, and a fourth straight line intersecting with the first straight line and a fifth straight line intersecting with the second straight line, the slope of the fourth straight line is greater than the slope of the third straight line and less than the slope of the fifth straight line; performing linear fitting on each power constant coordinate point, the intersection point of the first straight line and the fourth straight line, the intersection point of the fourth straight line and the fifth straight line, and the intersection point of the second straight line and the fifth straight line to obtain a slip control curve after slip-limited power control.

2. The control method according to claim 1, characterized in that: The main controller sends a slip control curve signal to the slip controller via communication.

3. The control method according to claim 1, characterized in that: The main controller creates the slip control curve by taking the stable power output of the wind turbine generator set as a control target.

4. The control method according to claim 1, characterized in that: The power constant coordinate point corresponding to the maximum rotation speed range is located on the fifth straight line.

5. The control method according to claim 1, characterized in that: The minimum speed range corresponds to the first power constant coordinate point and the second power constant coordinate point, respectively, and the maximum speed range corresponds to the third power constant coordinate point.

6. The control method according to claim 1, characterized in that: The (rotation speed reference value nref, the power reference value Pref) is taken as a coordinate point, and the coordinate point is taken as the intersection point of the fourth straight line and the fifth straight line.

7. The control method according to claim 6, characterized in that: The speed reference value nref is 1540-1580 rpm, and the power reference value Pref is 1400-1600 kW.

8. The control method according to claim 5, characterized in that: The minimum speed range is 1500-1530rpm, the maximum speed range is 1700-1750rpm, wherein the power of the first power constant coordinate point is greater than 10kw and less than 50kw, the power of the second power constant coordinate point is greater than 150kw and less than 200kw, and the power of the third power constant coordinate point is not less than 1700kw.

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