A control method and device for an offshore wind turbine

Abstract

The application relates to the technical field of wind power generation, in particular to a control method and device for offshore wind turbines. When the current wind turbine rotating speed is greater than the rated wind turbine rotating speed, the application determines the low-speed shaft rated rotating speed of the wind wheel according to the current wind turbine rotating speed; determines the change amount of the blade pitch angle of the wind turbine based on the low-speed shaft rated rotating speed of the wind wheel; and controls the wind turbine based on the change amount of the blade pitch angle of the wind turbine. The scheme can reduce the load of the wind turbine under the premise of ensuring the stability of the power generation of the wind turbine through the linkage adjustment mechanism of the rotating speed and the pitch angle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind power generation technology, and in particular to a control method and device for offshore wind turbine. BACKGROUND

[0002] At present, most of the built offshore wind farms are located in the intertidal zone and offshore area, and the resource development is gradually saturated, and the cost of further development is rising. However, China has huge deep-sea wind energy reserves, and the wind is more powerful and stable. Under the driving of offshoring development, it is an inevitable trend for offshore wind power to move towards deep-sea and far-offshore. Considering the cost and benefit of deep-sea wind energy development, large floating wind turbines have cost advantages in water depths of more than 50 meters, and they have strong adaptability to complex deep-sea areas, low construction difficulty and low operation and maintenance cost, which have become an inevitable choice for future offshore wind power development.

[0003] Floating wind turbine system motion and load reduction control has always been a hot research topic. With the increase of megawatt level of wind turbine, the floating wind turbine system is more flexible, especially under the combined action of extreme wind and wave load, the system will produce large strong nonlinear motion, and significant vibration and larger structural load will be generated at the key parts such as the blade root and the connection between the tower and the platform, which will further lead to the generation of larger fatigue load, and even cause fatigue damage of the floating wind turbine system structure. Therefore, it is essential to propose necessary measures to suppress excessive motion and fatigue load of the system and ensure its reliability and stability of power output during the whole life cycle.

[0004] Based on this, the present application provides a control method and device for offshore wind turbine to solve the problem of how to reduce the load of the wind turbine under the premise of ensuring the stability of the power generation of the wind turbine. SUMMARY

[0005] In order to solve the problem of how to reduce the load of the wind turbine under the premise of ensuring the stability of the power generation of the wind turbine, the present application provides a control method and device for offshore wind turbine.

[0006] In the first aspect, the present application provides a control method for offshore wind turbine, which comprises:

[0007] When the current wind turbine speed is greater than the rated wind turbine speed, the low-speed shaft rated speed of the wind wheel is determined based on the current wind turbine speed;

[0008] The change amount of the blade pitch angle of the wind turbine is determined based on the low-speed shaft rated speed of the wind wheel;

[0009] The wind turbine is controlled based on the change amount of the blade pitch angle of the wind turbine.

[0010] In the second aspect, the present application provides a control device for offshore wind turbine, which comprises:

[0011] a first data processing module, configured to determine a wind wheel low-speed shaft rated speed based on the current fan speed when the current fan speed is greater than the rated fan speed;

[0012] a second data processing module, configured to determine a wind turbine blade pitch angle change amount based on the wind wheel low-speed shaft rated speed;

[0013] a third data processing module, configured to control the fan based on the wind turbine blade pitch angle change amount.

[0014] In a third aspect, an electronic device is provided, which includes a memory and a processor, the memory storing a computer program, and the processor executes the computer program to implement the method according to any of the embodiments.

[0015] In a fourth aspect, a computer readable storage medium is provided, which stores a computer program, and the computer program, when executed in a computer, causes the computer to perform the method according to any of the embodiments.

[0016] The embodiments of the present application provide a control method and device for offshore wind turbines. The present application collects fan main shaft speed signals in real time through high-precision sensors, and when the measured speed exceeds the rated speed threshold, the rated target speed of the wind wheel low-speed shaft is calculated based on the aerodynamic characteristic curve and the transmission system speed ratio relationship and the mechanical transmission principle. The aerodynamic characteristic curve is an important basis for describing the aerodynamic performance of the wind turbine at different wind speeds and speeds, and the transmission system speed ratio determines the speed conversion relationship between the wind wheel and the generator. The change amount of the wind turbine blade pitch angle is determined according to the rated speed of the wind wheel low-speed shaft. Finally, the pitch angle dynamic adjustment is executed through the electro-hydraulic servo system. The electro-hydraulic servo system is a high-precision control system that uses hydraulic oil as the medium and controls the action of the hydraulic actuator through the electrical signal, which can realize the rapid and accurate adjustment of the blade pitch angle. While maintaining the generator power tracking rated value, the aerodynamic load fluctuation is reduced through the advance adjustment of the pitch angle. Thus, the present application can reduce the load of the fan while ensuring the stability of the fan power generation. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0018] Figure 1A control method flow chart of an offshore wind turbine according to one embodiment is shown;

[0019] Figure 2 is a hardware architecture diagram of an electronic device provided by an embodiment of the present application;

[0020] Figure 3 A control device structure diagram of an offshore wind turbine according to one embodiment is shown. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0022] Reference is made to Figure 1 The present application provides a control method of an offshore wind turbine, which comprises:

[0023] Step 100: when the current wind turbine speed is greater than the rated wind turbine speed, determining the rated low-speed shaft speed of the wind wheel based on the current wind turbine speed;

[0024] Step 102: determining the change amount of the blade pitch angle of the wind turbine based on the rated low-speed shaft speed of the wind wheel;

[0025] Step 104: controlling the wind turbine based on the change amount of the blade pitch angle of the wind turbine.

[0026] In the present embodiment, the high-precision sensor is used to collect the wind turbine main shaft speed signal in real time, and when the measured speed exceeds the rated speed threshold, the rated target speed of the wind wheel low-speed shaft is calculated based on the aerodynamic characteristic curve and the transmission system speed ratio relationship and the mechanical transmission principle. The aerodynamic characteristic curve here is an important basis for describing the aerodynamic performance of the wind turbine at different wind speeds and speeds, and the transmission system speed ratio determines the speed conversion relationship between the wind wheel and the generator. The change amount of the blade pitch angle of the wind turbine is determined according to the rated low-speed shaft speed of the wind wheel. Finally, the electro-hydraulic servo system is used to execute the dynamic adjustment of the pitch angle. The electro-hydraulic servo system is a high-precision control system using hydraulic oil as the medium and controlling the action of the hydraulic actuator through the electrical signal, which can realize the rapid and accurate adjustment of the blade pitch angle. While maintaining the generator power tracking rated value, the aerodynamic load fluctuation is reduced through the advance adjustment of the pitch angle. Thus, the present application can reduce the load of the wind turbine while ensuring the stability of the wind turbine power generation.

[0027] In one embodiment of the present application, the change of the pitch angle of the wind turbine blade is determined based on the rated speed of the low-speed shaft of the wind wheel, comprising:

[0028] The proportional gain of the pitch angle and the integral gain of the pitch angle are determined based on the rated speed of the low-speed shaft of the wind wheel.

[0029] The change of the pitch angle of the wind turbine blade is determined based on the proportional gain of the pitch angle and the integral gain of the pitch angle.

[0030] In the embodiment, when the change of the pitch angle of the wind turbine blade is determined based on the rated speed of the low-speed shaft of the wind wheel, the proportional gain and the integral gain of the pitch angle are determined according to the rated speed, and then the change of the pitch angle of the wind turbine blade is calculated based on the obtained proportional gain and integral gain.

[0031] In one embodiment of the present application, the change of the pitch angle of the wind turbine blade is determined by the following formula:

[0032]

[0033] In the formula, Δθ is the change of the pitch angle of the wind turbine blade, T r is the torque of the wind wheel, I r is the inertia moment of the low-speed shaft of the wind wheel, T g is the torque of the generator, I g is the inertia moment of the high-speed shaft of the generator, I drv is the inertia moment of the low-speed shaft of the transmission system, N g is the transmission ratio of the gear box, Ω0 is the rated speed of the low-speed shaft of the wind wheel, is the acceleration of the low-speed shaft of the wind wheel, K P is the proportional gain of the pitch angle, K I is the integral gain of the pitch angle, K D is the preset differential gain of the pitch angle, and t is time.

[0034] In the embodiment, when the wind speed is higher than the rated wind speed, the blade pitch control of the wind turbine is started, and the control equations of the wind wheel, the nacelle and the transmission system are as follows:

[0035]

[0036] In the formula, T r is the torque of the wind wheel, I r is the inertia moment of the low-speed shaft of the wind wheel, T g is the torque of the generator, I g is the inertia moment of the high-speed shaft of the generator, I drv is the inertia moment of the low-speed shaft of the transmission system, N g is the transmission ratio of the gear box, Ω0 is the rated speed of the low-speed shaft of the wind wheel, is the acceleration of the low-speed shaft of the wind wheel.

[0037] Further, it is assumed that the rotor torque varies negligibly with its rotational speed, and that the generator torque is inversely proportional to the rotor low speed shaft speed in the pitch controlled wind speed range, the first order Taylor expansion of the generator torque and the rotor torque are as follows:

[0038]

[0039] where P and P0are the mechanical power of the generator and the rated mechanical power, respectively, Ω is the rotor low speed shaft speed, θ is the pitch angle of the wind turbine blade, and Ω0is the rated rotor low speed shaft speed and the relationship between the pitch angle variation and the rotor low speed shaft speed difference is as follows:

[0040]

[0041] where Kp is the proportional gain of the pitch angle, Ki is the integral gain of the pitch angle, and Kd is the differential gain of the pitch angle. P I D

[0042] Further, let then the second order equation of the azimuth angle variation can be expressed as:

[0043]

[0044] where the natural frequency and the damping ratio are expressed as:

[0045]

[0046] For the active global pitch wind turbine, the sensitivity of the aerodynamic power to the rotor pitch angle is negative in the pitch controlled wind speed range. Therefore, in the case of positive control gain, the differential term increases the effective inertia of the drive train, the proportional term increases the damping, and the integral term increases the restoring force. In addition, since the generator torque decreases with the increase of the rotational speed difference, the generator torque controller introduces a negative damping term in the rotational speed difference response and the negative damping term must be compensated by the proportional term in the blade pitch torque control.

[0047] Further, in the design process of the pitch torque controller of the floating wind turbine, the differential gain term is usually ignored to ignore the negative damping from the generator torque control.

[0048] In one embodiment of the present application, the proportional gain of the pitch angle is determined by the following formula:

[0049]

[0050] where K​​​​p is a proportional gain of the pitch angle, I drv is an inertia moment of a low speed shaft of a transmission system, and ω0 is a rated speed of a low speed shaft of a wind wheel, is a damping ratio, is a natural frequency, N g is a transmission ratio of a gear box, is a preset parameter.

[0051] In one embodiment of the present application, the integral gain of the pitch angle is determined by the following formula:

[0052]

[0053] wherein, K I is an integral gain of the pitch angle, I drv is an inertia moment of a low speed shaft of a transmission system, and ω0 is a rated speed of a low speed shaft of a wind wheel, is a damping ratio, is a natural frequency, N g is a transmission ratio of a gear box, is a preset parameter.

[0054] In one embodiment of the present application, based on the proportional gain of the pitch angle and the integral gain of the pitch angle, a variation of the pitch angle of the wind turbine blade is determined, comprising:

[0055] The proportional gain of the pitch angle and the integral gain of the pitch angle are optimized according to a preset objective function, to obtain an optimized proportional gain of the pitch angle and an optimized integral gain of the pitch angle;

[0056] Based on the optimized proportional gain of the pitch angle and the optimized integral gain of the pitch angle, the variation of the pitch angle of the wind turbine blade is determined.

[0057] In the present embodiment, based on the proportional gain of the pitch angle and the integral gain of the pitch angle, the variation of the pitch angle of the wind turbine blade is determined, and the specific steps are as follows: first, the proportional gain and the integral gain of the pitch angle are calculated and optimized according to a preset objective function, to obtain an optimized proportional gain of the pitch angle and an optimized integral gain of the pitch angle; then, the dynamic adjustment amount of the pitch angle of the wind turbine blade is calculated according to the optimized proportional gain and the optimized integral gain, to ensure that the control system can achieve optimal control effect under different working conditions.

[0058] In one embodiment of the present application, the preset objective function is constructed by the following formula:

[0059]

[0060] wherein, F NSGA is the preset objective function, f rotor (t) is a speed difference of the wind wheel, d p(t) is the floating foundation translational motion response, θ p (t) is the floating foundation rotational motion response, ψ rotor-over is the wind wheel rotational speed overshoot, ψ d-over is the floating foundation translational displacement response overshoot, ψ θ-over is the floating foundation rotational motion response overshoot, α is an ITAE weight coefficient, β is an overshoot weight coefficient, and t is time.

[0061] In the embodiment, the pitch controller parameters are optimized in real time by using an intelligent optimization algorithm to ensure the stability of the wind turbine output power and suppress the motion of the floating foundation to reduce the wind turbine load and fatigue load at key positions of the wind turbine structure and increase the service life thereof. The wind turbine load and output power are selected as the control objects, the main influencing factors thereof include the wind wheel rotational speed and the rocking motion of the floating foundation, and accordingly, the sum of the time domain integral value (ITAE) of the error absolute value and the super penalty function term is constructed as the target function of optimization, and the minimum value of the target function is used to determine the setting of the pitch controller K p and K I .

[0062] In an embodiment of the present application, below the rated wind speed, the maximum power tracking control objective is achieved by torque control to achieve maximum capture of wind energy:

[0063]

[0064] wherein ρ a is the air density, R is the wind wheel radius, λ is the DTU 10MW wind turbine tip speed ratio, Ω l is the low speed shaft rotational speed, C p (λ) is the wind energy utilization coefficient.

[0065] As shown in Figure 2 , Figure 3 , the embodiment of the present application provides a control device of an offshore wind turbine. The device embodiment can be realized by software, or realized by hardware or a combination of software and hardware. From the hardware layer, as shown in Figure 2 , it is a hardware architecture diagram of an electronic device where the control device of the offshore wind turbine provided by the embodiment of the present application is located. In addition to the processor, the memory, the network interface, and the non-volatile memory shown in Figure 2 , the electronic device where the device in the embodiment is located can usually also include other hardware, such as a forwarding chip responsible for processing messages and the like. Taking the software implementation as an example, as shown in Figure 3 , as a logically meaningful device, it is formed by the CPU of the electronic device where it is located reading the corresponding computer program in the non-volatile memory into the memory for running.

[0066] As Figure 3 shown, the device comprises:

[0067] a first data processing module 300, configured to determine a wind wheel low-speed shaft rated speed based on a current wind turbine speed when the current wind turbine speed is greater than a rated pre-wind turbine speed;

[0068] a second data processing module 302, configured to determine a wind turbine blade pitch angle change amount based on the wind wheel low-speed shaft rated speed;

[0069] a third data processing module 304, configured to control the wind turbine based on the wind turbine blade pitch angle change amount.

[0070] In an embodiment of the present application, the second data processing module 302 is configured to perform the following steps:

[0071] determine a pitch angle proportional gain and a pitch angle integral gain based on the wind wheel low-speed shaft rated speed;

[0072] determine the wind turbine blade pitch angle change amount based on the pitch angle proportional gain and the pitch angle integral gain.

[0073] In an embodiment of the present application, the wind turbine blade pitch angle change amount is determined by the following formula:

[0074]

[0075] wherein, Δθ is the wind turbine blade pitch angle change amount, T r is a wind wheel torque, I r is a wind wheel low-speed shaft inertia moment, T g is a generator torque, I g is a generator high-speed shaft inertia moment, I drv is a transmission system low-speed shaft inertia moment, N g is a gear box transmission ratio, Ω0 is a wind wheel low-speed shaft rated speed, is an acceleration of the wind wheel low-speed shaft rotation, K P is the pitch angle proportional gain, K I is the pitch angle integral gain, K D is a preset pitch angle differential gain, and t is time.

[0076] In an embodiment of the present application, the pitch angle proportional gain is determined by the following formula:

[0077]

[0078] wherein, K pis a proportional gain of the pitch angle, I drv is an inertia moment of a low speed shaft of a transmission system, and ω0 is a rated speed of a low speed shaft of the wind wheel, is a damping ratio, is a natural frequency, N g is a gear box transmission ratio, is a preset parameter.

[0079] In an embodiment of the present application, the integral gain of the pitch angle is determined by the following formula:

[0080]

[0081] wherein, K I is an integral gain of the pitch angle, I drv is an inertia moment of a low speed shaft of a transmission system, and ω0 is a rated speed of a low speed shaft of the wind wheel, is a damping ratio, is a natural frequency, N g is a gear box transmission ratio, is a preset parameter.

[0082] In an embodiment of the present application, the second data processing module 302 is configured to perform the following steps:

[0083] optimizing the proportional gain of the pitch angle and the integral gain of the pitch angle according to a preset target function, to obtain an optimized proportional gain of the pitch angle and an optimized integral gain of the pitch angle;

[0084] determining the variation of the pitch angle of the wind turbine blade based on the optimized proportional gain of the pitch angle and the optimized integral gain of the pitch angle.

[0085] In an embodiment of the present application, the preset target function is constructed by the following formula:

[0086]

[0087] wherein, F NSGA is the preset target function, f rotor (t) is a wind wheel speed difference, d p (t) is a heave motion response of the floating foundation, θ p (t) is a rotational motion response of the floating foundation, ψ rotor-over is a wind wheel speed overshoot, ψ d-over is a heave displacement response overshoot, ψ θ-over is a rotational motion response overshoot of the floating foundation, α is an ITAE weight coefficient, β is an overshoot weight coefficient, and t is time.

[0088] It can be understood that the structural schematic of the embodiments of the present application does not constitute a specific limitation on the control measurement device of the offshore wind turbine. In other embodiments of the present application, the control measurement device of the offshore wind turbine can include more or fewer components than the schematic, or combine certain components, or split certain components, or different component arrangement. The components shown can be implemented in hardware, software, or a combination of software and hardware.

[0089] The information interaction, execution process and the like between the modules in the device are based on the same concept as the method embodiments of the present application, and the specific content can be referred to the description in the method embodiments of the present application, which will not be described here.

[0090] The embodiments of the present application also provide an electronic device, including a memory and a processor, the memory stores a computer program, and the processor implements the control method of the offshore wind turbine in any of the embodiments of the present application when executing the computer program.

[0091] The embodiments of the present application also provide a computer readable storage medium, the computer readable storage medium stores a computer program, and the computer program makes the processor execute the control method of the offshore wind turbine in any of the embodiments of the present application when the processor executes the computer program.

[0092] Specifically, a system or device equipped with a storage medium can be provided, the storage medium stores software program codes for realizing the functions of any of the above embodiments, and the computer (or CPU or MPU) of the system or device reads and executes the program codes stored in the storage medium.

[0093] In this case, the program codes read from the storage medium can realize the functions of any of the above embodiments, and therefore the program codes and the storage medium storing the program codes constitute a part of the present application.

[0094] The storage medium embodiments for providing the program codes include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), magnetic tapes, nonvolatile memory cards and ROM. Alternatively, the program codes can be downloaded from a server computer through a communication network.

[0095] In addition, it should be clear that not only the program codes read by the computer can be executed, but also part or all of the actual operations can be completed by the operating system and the like operating on the computer based on the instructions of the program codes, so as to realize the functions of any of the above embodiments.

[0096] Moreover, it is understood that the programs read out from the storage medium can be written to the storage device of an expansion board inserted in the computer or to the storage device of an expansion module connected to the computer, and that the CPU or the like installed on the expansion board or the expansion module is caused to perform part or all of the actual operations based on the instructions of the programs, thereby realizing the functions of the above-described embodiments.

[0097] It is to be understood that the terminology used herein such as first and second, merely for the purpose of distinguishing one entity or action from another, and (s) neither implies nor requires any actual such relationship or order between entities or actions. Also, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0098] Those skilled in the art can understand that all or part of the steps of the above-mentioned method embodiments can be completed by program instruction related hardware, and the foregoing program can be stored in a computer readable storage medium, and the program performs the steps of the above-mentioned method embodiments when executed; and the foregoing storage medium includes ROM, RAM, magnetic disk or optical disk and various storage media that can store program codes.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; even though the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of controlling an offshore wind turbine, characterized by, The offshore wind turbine is a megawatt floating wind turbine, and the method comprises: When the current wind turbine speed is greater than the rated wind turbine speed, the wind wheel low-speed shaft rated speed is determined based on the current wind turbine speed; The change amount of the wind turbine blade pitch angle is determined based on the wind wheel low-speed shaft rated speed by using a PID control mode; The wind turbine is controlled based on the change amount of the wind turbine blade pitch angle; determining the change amount of the wind turbine blade pitch angle based on the wind wheel low-speed shaft rated speed comprises: The proportional gain of the pitch angle and the integral gain of the pitch angle are determined based on the wind wheel low-speed shaft rated speed; The change amount of the wind turbine blade pitch angle is determined based on the proportional gain of the pitch angle and the integral gain of the pitch angle; The change amount of the wind turbine blade pitch angle is determined based on the proportional gain of the pitch angle and the integral gain of the pitch angle, comprising: The proportional gain of the pitch angle and the integral gain of the pitch angle are optimized according to a preset target function to obtain an optimized proportional gain of the pitch angle and an optimized integral gain of the pitch angle; The change amount of the wind turbine blade pitch angle is determined based on the optimized proportional gain of the pitch angle and the optimized integral gain of the pitch angle; The preset target function is constructed by the following formula: In the formula, is the preset target function, is the wind wheel rotating speed difference, is the floating foundation translational motion response, is the floating foundation rotational motion response, is the wind wheel rotating speed overshoot, is the floating foundation translational displacement response overshoot, is the floating foundation rotational motion response overshoot, is the ITAE weight coefficient, is the overshoot weight coefficient, t is time; The real-time optimization of the variable pitch controller parameters is performed, the wind turbine load and output power are selected as the control objects, the influencing factors include the wind wheel speed and the rocking motion of the floating foundation, and accordingly the sum of the time domain integral value of the error absolute value and the super penalty function item is constructed as the optimization target function.

2. The method of claim 1, wherein, The change amount of the wind turbine blade pitch angle is determined by the following formula: wherein is the change in the pitch angle of the wind turbine blade, is the gearbox ratio, is the acceleration of the low speed shaft of the wind rotor, is the proportional gain of the pitch angle, is the integral gain of the pitch angle, is the derivative gain of the preset pitch angle, and t is time.

3. Control arrangement for an offshore wind turbine, characterized in that For executing the method as claimed in any one of claims 1-2, comprising: The first data processing module is used for determining the wind wheel low-speed shaft rated speed based on the current wind turbine speed when the current wind turbine speed is greater than the rated wind turbine speed; The second data processing module is used for determining the change amount of the wind turbine blade pitch angle based on the wind wheel low-speed shaft rated speed; The third data processing module is used for controlling the wind turbine based on the change amount of the wind turbine blade pitch angle.

4. An electronic device, comprising: The memory and the processor are included, the computer program is stored in the memory, and the processor implements the method as claimed in any one of claims 1-2 when executing the computer program.

5. A computer readable storage medium, characterized in that, The computer program is stored thereon, and when the computer program is executed in the computer, the computer executes the method as claimed in any one of claims 1-2.

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