Power adjusting method suitable for water resistance load device

Abstract

The invention discloses a power regulation method suitable for a water resistance load device. The method comprises the following steps: calculating the power deviation of the water resistance load device; if the power deviation is large, proportional adjustment is used, and otherwise proportional-integral adjustment is used; calculating a temperature correction coefficient to reduce the influence of the water temperature on the adjusting performance; calculating an angle correction coefficient to reduce the influence of the rotation angle of the resistance adjusting plate on the adjusting performance; and the adjusting speed is selected according to the power deviation. According to the invention, the adjusting speed of the water resistance load device is higher, and the time from the minimum power to the maximum power does not exceed 20 seconds; the control precision is higher, and the error does not exceed 3%; the power adjusting range is wider and reaches 6-100%; in the power adjusting process, the acceleration is not too large, and overshoot is avoided.

Description

Technical Field

[0001] The present invention relates to the field of generator sets and power supply testing, and in particular to a power regulation method suitable for a water resistance load device. Background Art

[0002] Currently, there are two common types of load devices used for generator set load testing: dry resistors and water resistors. Dry resistors primarily consist of a contactor and metal resistance wire, and a specified resistance value is achieved by opening and closing the contactor to change the number of parallel resistor wires. Water resistors primarily consist of metal plates and water, and a specified resistance value is achieved by adjusting the distance or contact area between the metal plates and the water.

[0003] The advantages of dry resistors are small power fluctuations and high control accuracy (within 1%). The disadvantages are: (1) the resistance value can only be adjusted in the form of stepped gears. A load device designed for a certain power is difficult to apply to generator sets of other powers, and the compatibility is very poor. If load tests are required on multiple generator sets of different powers, multiple load devices can only be purchased, which is a serious waste of funds. (2) The noise pollution of the cooling fan is serious, with a noise level of 60 to 80 decibels when a single unit is running and up to 100 decibels when multiple units are running together.

[0004] The disadvantages of water resistors are large power fluctuations, low control accuracy, and a small power adjustment range (the minimum power is around 20-30%). However, their advantages are: (1) they can continuously adjust the resistance and are suitable for most generator sets. Only one load device is needed to be suitable for multiple generator sets with different powers; (2) they do not require a cooling fan and there is no noise pollution.

[0005] "A load device using water as a resistor and a resistance adjustment method" (application number 2023117283308) discloses a rotary adjustable water resistor load device, in which the conductive plates are immersed in water, kept parallel to each other and with equal spacing, and then a stepper motor is used to drive the non-conductive insulating plates to rotate between the plates. The larger the area of the plates blocked, the greater the resistance and the smaller the power; the smaller the area of the plates blocked, the smaller the resistance and the greater the power. This patent effectively overcomes the shortcomings of water resistors, such as low control accuracy and a relatively narrow power adjustment range, while retaining the advantages of low price and no noise, making it possible for water resistors to replace part of the dry resistor market. However, this patent only uses the simplest proportional adjustment algorithm to automatically adjust the power, so the adjustment performance is not good and cannot adapt to situations where the water temperature and rotation angle change greatly. Summary of the Invention

[0006] In response to the above-mentioned problems existing in the prior art, the present invention provides a power regulation method suitable for a water resistance load device. Proportional regulation is used when the power deviation is large, and proportional integral regulation is used when the power deviation is small. Corrections for water temperature and rotation angle are also added, thereby achieving good results such as a relatively fast regulation speed without overshoot, unchanged regulation performance when the water temperature and rotation angle change greatly, and a steady-state error of less than 3%.

[0007] The technical solutions of the present invention are as follows:

[0008] A power regulation method applicable to a water resistance load device, the method being implemented by the water resistance load device; the water resistance load device comprising a water tank 1, a plate 2, a resistance adjustment plate 3, and a rotating shaft 4; the plate 2 and the resistance adjustment plate 3 being arranged inside the water tank 1;

[0009] The electrode plate 2 is a conductive thin plate structure, and the two surfaces perpendicular to the thickness direction of the thin plate are called electrode plate surfaces;

[0010] The number of the electrode plates 2 is not less than 2 and they are fixed inside the water tank 1 according to the following conditions:

[0011] (1-1) All plates 2 are in contact with the water inside the water tank 1;

[0012] (1-2) The plate surfaces of all plates 2 are perpendicular to the horizontal plane;

[0013] (1-3) The electrode surfaces of different electrodes 2 are parallel to each other;

[0014] (1-4) The distance between the plate surfaces of two adjacent plates 2 is the same; this distance is defined as the plate spacing;

[0015] The resistance adjustment plate 3 is a non-conductive thin plate structure, and the two surfaces perpendicular to the thickness direction are called adjustment plate surfaces;

[0016] The rotating shaft 4 is a long rod structure, the central axis of which is called the central axis;

[0017] The number of the resistance adjustment plates 3 is one less than the number of the electrode plates 2, and they are fixed on the rotating shaft 4 according to the following conditions to form a whole, namely, a resistance adjustment system:

[0018] (2-1) The surfaces of all resistance adjustment plates 3 are perpendicular to the central axis;

[0019] (2-2) The distance between the surfaces of two adjacent resistance adjustment plates 3 is the same, which is equal to the plate spacing;

[0020] Observed with the rotating shaft 4 as the center, the edge contour of the resistance-adjusting plate 3 is a circle. On this circle, a diameter can be found: one side of the diameter has a hollowed-out area, i.e., the hollowed-out area; the other side of the diameter has no hollowed-out area, i.e., the solid area. When the resistance-adjusting plate 3 rotates, the contact area between the solid area and the water changes, blocking the plate. If the area of the plate blocked by the solid area increases, the resistance increases and the power decreases; if the area of the plate blocked by the solid area decreases, the resistance decreases and the power increases.

[0021] The resistance adjustment system is arranged inside the water tank 1 according to the following conditions and moves in a circular motion around the central axis:

[0022] (3-1) The rotating shaft 4 does not come into contact with the water inside the water tank;

[0023] (3-2) The rotating shaft 4 is located above the electrode plate 2 and does not come into contact with the electrode plate 2;

[0024] (3-3) the central axis is parallel to the horizontal plane;

[0025] (3-4) Along the central axis, the electrode plate 2 and the resistance adjusting plate 3 are alternately arranged, and the starting and ending ends are both the electrode plate 2, that is: electrode plate 2, resistance adjusting plate 3, electrode plate 2, resistance adjusting plate 3, ..., electrode plate 2;

[0026] (3-5) When the resistance adjustment system performs circular motion around the central axis, the resistance adjustment plate 3 comes into contact with the water inside the water tank 1, and the contact area between the two changes as the rotating shaft 4 rotates;

[0027] The stepper motor 5 is connected to the rotating shaft 4 via a coupling 6; the PLC is connected to the stepper motor 5 via a stepper motor driver, thereby controlling the rotation of the stepper motor 5; the PLC measures the voltage and current between the plates using an electric energy meter and a current transformer, measures the water temperature T inside the water tank 1 using a temperature sensor, and measures the angle A of the rotating shaft 4 using an angle sensor;

[0028] The specific steps of the method are as follows:

[0029] S1. The PLC receives the power set value P_Set, then calculates the actual power value P_Real based on the voltage and current of the energy meter, and finally calculates the power deviation P = power set value P_Set - power actual value P_Real;

[0030] S2. Set a constant: PI enable threshold PI_En, which is used to control the start and stop of the PI algorithm; set two coefficients: proportional adjustment coefficient K and integral adjustment coefficient I;

[0031] S3. If the absolute value of the power deviation P is greater than PI_En, execute S4; otherwise, execute S5.

[0032] S4, calculate the moving distance D of the stepping motor 5, that is: D = K × P, and jump to S10;

[0033] S5. Set two constants: the integration interval time t and the accumulated power error W. Start a timer in the PLC with the time set to t. The action after triggering is: save the current power deviation P to the array M.

[0034] S6. Read the latest n data stored in the array M, perform cumulative calculation, and obtain the accumulated power error W;

[0035] S7, calculate the temperature correction coefficient T_xz, which is used to solve the problem of inconsistent adjustment effects of the PI algorithm at different temperatures;

[0036] S8, calculate the angle correction coefficient A_xz, which is used to solve the problem of inconsistent adjustment effect of the PI algorithm when the rotating shaft (4) is at different angles; S9, calculate the moving distance D of the stepper motor, that is: D = (K×P+I×W)×T_xz×A_xz;

[0037] S10, set a constant: speed coefficient ks, and calculate the moving speed S of the stepping motor 5, that is: S = ks × D;

[0038] S11. Set two constants: upper speed limit S_Max and lower speed limit S_Min. If S>S_Max, then S=S_Max; if S<S_Min, then S=S_Min.

[0039] S12, PLC drives stepper motor 5 to rotate according to D and S;

[0040] S13. Set a constant: dead zone Z. If the absolute value of the power deviation P is less than P_Set×Z, stop the rotation of the stepper motor; otherwise, continue to execute S1.

[0041] Furthermore, the calculation formula of the temperature correction coefficient T_xz is:

[0042]

[0043] Wherein T represents the water temperature inside the water tank 1.

[0044] Furthermore, the calculation formula of the angle correction coefficient A_xz is:

[0045]

[0046] Wherein R represents the radius of the hollow area of the resistance adjustment plate 3, and h represents the distance from the central axis of the rotating shaft 4 to the water surface.

[0047] Furthermore, the dead zone Z≤3%.

[0048] Compared with the existing water resistor, the present invention has the following advantages:

[0049] (1) Dynamically adjust the resistance and power with an error of less than 3%. When the power deviation is large, the acceleration will not be too large; when the power deviation is small, there will be no overshoot; when the water temperature and rotation angle change greatly, there will be no overshoot or oscillation.

[0050] (2) The power adjustment range reaches 6-100%;

[0051] (3) The power regulation responds very quickly, and the time from minimum power to maximum power does not exceed 20 seconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is an appearance diagram of an embodiment;

[0053] Figure 2 is an internal structure diagram of an embodiment;

[0054] Figure 3 It is an exploded view of the core components of the embodiment;

[0055] Figure 4 It is a schematic diagram for deriving the angle correction coefficient;

[0056] Figure 5 is the relationship between the rotation angle θ and the current I;

[0057] Figure 6 This is the effect diagram of automatic adjustment;

[0058] In the figure, the correspondence between the component names and the drawing numbers is: 1. Water tank; 2. Plate; 3. Resistance adjustment plate; 4. Rotating shaft; 5. Stepper motor; 6. Coupling. DETAILED DESCRIPTION

[0059] The present invention is described in detail below with reference to the accompanying drawings and embodiments. It is apparent that the embodiments described are only a portion of the embodiments of the present invention, rather than all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0060] The embodiment is Figure 1 The 100KW water resistance load device (hereinafter referred to as water resistance) shown in the figure is Figure 2 This is a diagram of its internal structure. Figure 2The left area is used to install electrical components such as circuit breakers, contactors, stepper motors, and control systems, and the right area is used to install mechanical equipment such as water tank 1, plate 2, and resistance adjustment board 3.

[0061] like Figure 3 As shown, the core components of the water resistor used to adjust the resistance mainly include a water tank 1, a plate 2, a resistance adjustment plate 3 and a rotating shaft 4; the plate 2, the resistance adjustment plate 3 and the rotating shaft 4 are all arranged inside the water tank 1.

[0062] The number of the electrode plates 2 is 13, and they are conductive thin plate structures. The two surfaces perpendicular to the thickness direction of the thin plate are called electrode plate surfaces.

[0063] The plate 2 is fixed inside the water tank 1 according to the following conditions:

[0064] (1-1) All plates 2 are in contact with the water inside the water tank 1;

[0065] (1-2) The plate surfaces of all plates 2 are perpendicular to the horizontal plane;

[0066] (1-3) The electrode surfaces of different electrodes 2 are parallel to each other;

[0067] (1-4) The distance between the plate surfaces of two adjacent plates 2 is the same; this distance is defined as the plate spacing.

[0068] The number of resistance adjustment plates 3 is 12, and they are non-conductive thin plate structures, and the two surfaces perpendicular to the thickness direction are called adjustment plate surfaces.

[0069] The rotating shaft 4 is a long rod structure, and its central axis is called the central axis.

[0070] The resistance adjustment plate 3 is fixed to the rotating shaft 4 according to the following conditions to form a whole, namely the resistance adjustment system:

[0071] (2-1) The surfaces of all resistance adjustment plates 3 are perpendicular to the central axis;

[0072] (2-2) The distance between the surfaces of two adjacent resistance adjustment plates 3 is the same, which is equal to the plate spacing.

[0073] like Figure 4 As shown, when observed with the rotating shaft 4 as the center, the edge contour of the resistance adjustment plate 3 is a circle; with a certain diameter of the circle as the dividing line, there is a hollow area on one side of the dividing line, namely the hollow area; and there is no hollow area on the other side, namely the solid area; when the resistance adjustment plate 3 rotates, the contact area between the solid area and the water changes, forming a shielding on the plate; if the area of the solid area shielding the plate becomes larger, the resistance increases and the power decreases; if the area of the solid area shielding the plate becomes smaller, the resistance decreases and the power increases.

[0074] The resistance adjustment system is set inside the water tank according to the following conditions and moves in a circular motion around the central axis:

[0075] (3-1) The rotating shaft 4 does not come into contact with the water inside the water tank;

[0076] (3-2) The rotating shaft 4 is located above the electrode plate 2 and does not come into contact with the electrode plate 2;

[0077] (3-3) The central axis is parallel to the horizontal plane;

[0078] (3-4) Along the central axis, the electrode plate 2 and the resistance adjusting plate 3 are spaced apart, and the starting and ending ends are both the electrode plate 2, that is: electrode plate 2, resistance adjusting plate 3, electrode plate 2, resistance adjusting plate 3, ..., electrode plate 2;

[0079] (3-5) When the resistance adjustment system performs a circular motion around the central axis, the resistance adjustment plate 3 comes into contact with the water inside the water tank, and the contact area between the two changes as the rotating shaft 4 rotates.

[0080] The stepper motor 5 is connected to the rotating shaft 4 through a coupling 6; the PLC is connected to the stepper motor 5 through a stepper motor driver, thereby controlling the rotation of the stepper motor 5; the PLC measures the voltage and current between the plates through an electric energy meter and a current transformer, measures the water temperature T inside the water tank 1 through a temperature sensor, and measures the rotation angle θ of the rotating shaft 4 through an angle sensor.

[0081] The control logic of the PLC program is as follows:

[0082] S1. The PLC receives the power set value P_Set, then calculates the power actual value P_Real based on the voltage and current of the electric energy meter, and finally calculates the power deviation P = power set value P_Set - power actual value P_Real.

[0083] S2. Set a constant: the PI enable threshold, PI_En, which controls the activation and deactivation of the PI algorithm. This constant ensures that the acceleration of resistance adjustment plate 3 is not excessive. To maximize the power adjustment range, the gap between resistance adjustment plate 3 and electrode 2 is very small, resulting in high friction. Excessive acceleration can easily damage the resistance adjustment system.

[0084] Two coefficients are set: the proportional adjustment coefficient K and the integral adjustment coefficient I, to implement the PI algorithm. The PI algorithm is used instead of the PID algorithm because the acceleration of the resistance adjustment board 3 cannot be too large or overshoot, and adding a differential coefficient is not conducive to achieving this goal.

[0085] S3. If the absolute value of the power deviation P is greater than PI_En, execute S4; otherwise, execute S5.

[0086] S4. Calculate the moving distance D of the stepper motor, that is: D = K × P, and jump to S10.

[0087] S5. Set two constants: the integration interval time t and the accumulated power error W. Start a timer in the PLC, set the time to t, and the action after triggering is: save the current power deviation P to array M.

[0088] S6. Read the n most recently saved data in the array M, perform cumulative calculation, and obtain the accumulated power error W.

[0089] S7. The resistance of water varies significantly with temperature. The resistance at room temperature is twice that at boiling conditions. Therefore, temperature correction must be made. Otherwise, the performance of the same set of PI adjustment parameters under the two conditions mentioned above will differ significantly. Parameters that work well at room temperature may cause overshoot or oscillation under boiling conditions. The temperature correction coefficient T_xz is calculated as follows:

[0090]

[0091] S8, Figure 4 The shaded area of the grid represents the water not blocked by the resistance adjustment plate 3, which is called the conductive area; the length of the edge of the resistance adjustment plate 3 that is submerged in water is L. Figure 4 It can be seen that when the rotation angle θ of the rotating shaft 4 is relatively small, L is relatively small, and the conductive area changes very little when the rotating shaft 4 rotates through a small angle Δθ. When the rotation angle θ of the rotating shaft 4 is relatively large, L is relatively large, and the conductive area changes significantly when the rotating shaft 4 rotates through the same small angle Δθ. Therefore, the rotation angle θ must be adjusted. Otherwise, the adjustment performance of the same set of PI adjustment parameters under these two conditions will differ significantly. When θ is relatively small, the adjustment effect is very good, but when θ is relatively large, overshoot or oscillation occurs, and vice versa.

[0092] The calculation formula for L is:

[0093]

[0094] Where R represents the radius of the hollow area of the resistance adjustment plate 3, and h represents the distance from the central axis of the rotating shaft 4 to the water surface. The angle correction coefficient A_xz is calculated as follows:

[0095]

[0096] S9. Calculate the moving distance D of the stepper motor, that is: D = (K×P+I×W)×T_xz×A_xz.

[0097] S10. Set a constant: speed coefficient ks, and calculate the moving speed S of the stepper motor, that is: S = ks × D.

[0098] S11. Set two constants: the upper speed limit S_Max and the lower speed limit S_Min. If S>S_Max, then S=S_Max; if S<S_Min, then S=S_Min.

[0099] S12, PLC drives the stepper motor to rotate according to D and S.

[0100] S13. Set a constant: dead zone Z = 3%. If the absolute value of the power deviation P is less than P_Set×Z, stop the rotation of the stepper motor; otherwise, continue to execute S1.

[0101] The water resistance is tested by electricity. The relationship between the rotation angle θ and the current I is as follows: Figure 5 As shown, the effect of automatic adjustment is as follows Figure 6 When the conductive area is minimum, the current is 7.4A. This is because there is a gap between the resistance adjustment plate 3 and the electrode plate 2, which cannot be completely eliminated. When the conductive area is maximum, the current is 129.4A. Therefore, it can be calculated that the power adjustment range of the water resistor is 6-100%.

[0102] The rotation speed of the rotating shaft 4 is set by the PLC, and the time taken from minimum power to maximum power is about 18 seconds, and it can be further increased.

[0103] from Figure 6 It can be seen that when the power is set to 20kW, the power measurement value is stable at 20.4kW, with a relative error of 2%, and does not exceed the dead zone Z; the power increase process is relatively smooth, without excessive speed or overshoot; Figure 6 In the power-on test, the water is in a boiling state, and the power value is very stable with almost no fluctuation. Therefore, the present invention has achieved a very good regulation effect.

[0104] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, for those of ordinary skill in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A power regulation method for a water resistance load device, characterized in that: The method is implemented by a water resistance load device; the water resistance load device comprises a water tank (1), an electrode plate (2), a resistance adjustment plate (3) and a rotating shaft (4); the electrode plate (2) and the resistance adjustment plate (3) are arranged inside the water tank (1); The electrode (2) is a conductive thin plate structure, and the two surfaces perpendicular to the thickness direction of the thin plate are called electrode plate surfaces; The number of the electrode plates (2) is not less than 2, and they are fixed inside the water tank (1) according to the following conditions: (1-1) All plates (2) are in contact with the water inside the water tank (1); (1-2) The plate surfaces of all plates (2) are perpendicular to the horizontal plane; (1-3) The electrode surfaces of different electrodes (2) are parallel to each other; (1-4) The distance between the plate surfaces of two adjacent plates (2) is equal; this distance is defined as the plate spacing; The resistance adjustment plate (3) is a non-conductive thin plate structure, and the two surfaces perpendicular to the thickness direction are called adjustment plate surfaces; The rotating shaft (4) is a long rod structure, the central axis of which is called the central axis; The number of the resistance adjustment plates (3) is one less than the number of the pole plates (2), and they are fixed on the rotating shaft (4) according to the following conditions to form a whole, namely, a resistance adjustment system: (2-1) The surfaces of all resistance adjustment plates (3) are perpendicular to the central axis; (2-2) The distances between the surfaces of the two adjacent resistance adjustment plates (3) are equal and are equal to the plate spacing; Observing with the rotating shaft (4) as the center, the edge profile of the resistance adjustment plate (3) is a circle; on the circle, a diameter can be found: a hollow area exists on one side of the diameter, i.e., the hollow area; and an area without a hollow area exists on the other side of the diameter, i.e., the solid area; when the resistance adjustment plate (3) rotates, the contact area between the solid area and the water changes, thereby blocking the electrode plate; if the area of the solid area blocking the electrode plate increases, the resistance increases and the power decreases; if the area of the solid area blocking the electrode plate decreases, the resistance decreases and the power increases; The resistance adjustment system is arranged inside the water tank according to the following conditions and moves in a circular motion around the central axis: (3-1) The rotating shaft (4) does not come into contact with the water inside the water tank (1); (3-2) The rotating shaft (4) is located above the electrode plate (2) and does not come into contact with the electrode plate (2); (3-3) the central axis is parallel to the horizontal plane; (3-4) along the central axis, the electrode (2) and the resistance adjustment plate (3) are alternately arranged, and the starting and ending ends are both the electrode (2), that is: electrode (2), resistance adjustment plate (3), electrode (2), resistance adjustment plate (3), ..., electrode (2); (3-5) When the resistance adjustment system performs circular motion around the central axis, the resistance adjustment plate (3) comes into contact with the water inside the water tank (1), and the contact area between the two changes as the rotating shaft (4) rotates; The stepper motor (5) is connected to the rotating shaft (4) through a coupling (6); the PLC is connected to the stepper motor (5) through a stepper motor driver, thereby controlling the rotation of the stepper motor (5); the PLC measures the voltage and current between the plates through an electric energy meter and a current transformer, measures the water temperature T inside the water tank (1) through a temperature sensor, and measures the angle A of the rotating shaft (4) through an angle sensor; The specific steps of the method are as follows: S1. The PLC receives the power set value P_Set, calculates the actual power value P_Real based on the voltage and current of the energy meter, and finally calculates the power deviation P = power set value P_Set - power actual value P_Real; S2. Set a constant: PI enable threshold PI_En, which is used to control the start and stop of the PI algorithm; Set two coefficients: proportional adjustment coefficient K and integral adjustment coefficient I; S3. If the absolute value of the power deviation P is greater than PI_En, execute S4; otherwise, execute S5. S4, calculate the moving distance D of the stepping motor (5), that is: D = K × P, and jump to S10; S5. Set two constants: the integration interval time t and the accumulated power error W. Start a timer in the PLC with the time set to t. The action after triggering is: save the current power deviation P to the array M. S6. Read the latest n data stored in the array M, perform cumulative calculation, and obtain the accumulated power error W; S7, calculate the temperature correction coefficient T_xz, which is used to solve the problem of inconsistent adjustment effects of the PI algorithm at different temperatures; S8, calculating the angle correction coefficient A_xz, which is used to solve the problem of inconsistent adjustment effects of the PI algorithm when the rotating shaft (4) is at different angles; S9. Calculate the moving distance D of the stepper motor, i.e., D = (K × P + I × W) × T_xz × A_xz; S10, set a constant: speed coefficient ks, and calculate the moving speed S of the stepper motor (5), that is: S = ks × D; S11. Set two constants: upper speed limit S_Max and lower speed limit S_Min. If S>S_Max, then S=S_Max; if S<S_Min, then S=S_Min. S12, PLC drives the stepping motor (5) to rotate according to D and S; S13. Set a constant: dead zone Z. If the absolute value of the power deviation P is less than P_Set×Z, stop the rotation of the stepper motor; otherwise, continue to execute S1.

2. A power regulation method for a water resistance load device according to claim 1, characterized in that: The calculation formula of temperature correction coefficient T_xz is: Wherein T represents the water temperature inside the water tank (1).

3. The power regulation method for a water resistance load device according to claim 1, characterized in that: The calculation formula of the angle correction coefficient A_xz is: Wherein R represents the radius of the hollow area of the resistance adjustment plate (3), and h represents the distance from the central axis of the rotating shaft (4) to the water surface.

4. The power regulation method for a water resistance load device according to claim 1, characterized in that: Dead zone Z≤3%.

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