CN102966486A - Variable characteristic curve controlling method for float-type wave power generation device - Google Patents

Abstract

The invention belongs to the field of ocean utilization and renewable energy power generation, and relates to a variable characteristic curve control method of a float type wave power generation device. The method first obtains the torque-speed curve of the float type wave power generation device through experiments or simulations, and sets the curve The slope of the first part of the linear rising area is K. When controlling, first collect the wave period and wave height of the current wave, calculate the K value according to the relationship between the wave input power proportional to the square of the wave height and the wave period, and correct the float formula The torque-speed curve of the wave power generation device, and then according to the measured motor speed, the motor torque corresponding to the measured motor speed is obtained by the look-up table method, which is regarded as the reference electromagnetic torque, and according to the reference electromagnetic torque Calculate the corresponding reference output power according to the torque, and then control the actual output power of the float type ocean wave power generation device according to the reference output power value. The control method of the invention has the advantages of simple principle, easy realization and high reliability.

Description

Control Method of Variable Characteristic Curve for Float Type Ocean Wave Generator

Technical field

The invention belongs to the field of ocean utilization and renewable energy power generation, and in particular relates to a control method for a float type ocean wave power generation device.

Background technique

Environmental pollution and energy crisis are two common problems in the development of the world today. Vigorously developing wind power generation, wave power generation, tidal power generation, geothermal power generation and other new energy power generation methods, and realizing the change of energy conversion mode and the improvement of utilization rate are an important means to solve these two problems. Sustainable development plays an important role and has significant economic and social benefits. Because of its large power storage capacity, good economic potential, and strong safety, wave power generation devices have become a research hotspot in marine renewable energy power generation. In order to realize the maximum wave energy capture of the floating wave power generation device, the control methods currently studied include: reactive control, latch control, intelligent control, etc. The reactive control strategy is relatively simple and reliable in theory, but for the non-resonant wave power generation device, not only the generator needs to be able to run in the electric state, but also the wave information in the future is required to be predicted. The latching control strategy is most suitable for specific occasions where the external wave force can be captured in any direction, while in the vertical unidirectional energy absorption type floating wave power generation device, the latching control is only suitable for a period of one cycle. The advantages of intelligent control methods (fuzzy control, neural network control, etc.) are that they can overcome factors such as time-varying and nonlinear parameters of the wave power generation system; the disadvantage is that the research on simulating human intelligence activities and the process of control and information transmission will be more complicated. And the hardware and software requirements of the control system are relatively high.

Contents of the invention

Aiming at the above problems, the present invention provides a new maximum wave energy capture control method suitable for a buoy type ocean wave power generation device. The control principle of the method is simple and easy to implement. The present invention draws lessons from the advanced control technology in wind power generation—the maximum power tracking method, and proposes an improved variable characteristic curve control method. By selecting appropriate parameters and designing a simple controller, the method can significantly reduce the maximum power of the wave power generation device. While reducing the rate of change of the electromagnetic torque (that is, reducing the torque ripple), it ensures a good and stable torque output performance of the system. Technical scheme of the present invention is as follows:

A variable characteristic curve control method of a float type ocean wave power generation device, the method first obtains the torque-rotational speed curve of the float type wave power generation device through experiments or simulations, the slope of the first part of the linear rising area of the curve is set to K, and the When controlling, first collect the wave period and wave height of the current wave, calculate the K value according to the relationship between the wave input power proportional to the square of the wave height and the wave period, and correct the torque-speed curve of the floater type wave power generation device, and then according to The measured motor speed, the motor torque corresponding to the measured motor speed is obtained by the look-up table method, and it is regarded as the reference electromagnetic torque, and the corresponding reference output power is obtained according to the reference electromagnetic torque, and then according to the reference The output power value controls the actual output power of the buoyant wave generator.

As a preferred embodiment, in the above technical solution, according to the reference output power value, combined with a PID controller, a PWM wave is generated to change the duty ratio of the IGBT in the voltage source converter, thereby controlling the actual output power.

The beneficial effects of the present invention are as follows:

1) The principle of this control method is simple, easy to realize and high in reliability.

2) The control method has good real-time performance and can meet the requirements of fast control.

3) On the basis of this method, after selecting appropriate system parameters and applying PI controller, it can not only ensure higher output power, but also effectively reduce the electromagnetic torque change rate of the wave power generation device.

4) This control method does not need to predict future wave information, and has low requirements for generators and other software and hardware.

5) This control method has no requirements on the direction in which the wave energy device captures the external wave force. It is not only suitable for buoyant wave power generation devices, but also suitable for other types of wave power generation devices. It has strong practicability and a wide range of applications.

Description of drawings

Fig. 1 is a schematic diagram of a float type ocean wave power generation device.

In the figure, 1 is the floating body, 2 is the balance floating body, 3 is the pulley, 4 is the cable, 5 is the input shaft, 6 is the clutch, 7 is the output shaft, 8 is the flywheel, 9 is the permanent magnet synchronous motor, and 10 is AC-DC -AC converter.

Fig. 2 is a characteristic diagram of the variable characteristic curve control method. In the figure, the variable characteristic curve is divided into three parts: (1) linear rising area; (2) constant torque area; (3) constant power area.

Fig. 3 is an electrical system configuration diagram of the variable characteristic curve control method and a simplified representation diagram of the motor and its controller.

Fig. 4 is a flow chart of the variable characteristic curve control method.

Detailed ways

The present invention will be described below in conjunction with the accompanying drawings and embodiments.

式中P_rate为额定功率。可以看出，这三部分都与K有关，它控制着上升区T_ref的变化率，因此也决定了恒转矩区和恒功率区的值。K小于1时，T_ref就不会达到T_rate，而当K很大时，会使线性上升区和恒转矩区的交点左移。因此，K值影响了变特性曲线控制方法的控制性能，针对不同海域、不同波浪周期和高度的波浪发电系统，可以根据不同K值的实验结果自动选择适当的K值，使控制方法的效果最佳。图2中，K值的自动变化是根据波浪输入功率正比于波浪高度H的平方和波浪周期T(即

)这一关系,从而由系统采集到的H和T，计算出对应的额定功率P_rate，进而得到参考额定转矩T_ref。Figure 1 is a structural diagram of a typical floater-type wave power generation device. Referring to Fig. 2 and Fig. 3, Fig. 2 is a characteristic diagram of the variable characteristic curve control method proposed by the present invention. The reference torque T _ref of the linear rising region of the first part of the curve can be expressed as: In the formula, ω _r is the motor speed, ω _rate is the rated speed of the motor, T _rate is the rated torque, and K is the slope of the curve. The second part is the constant torque control area, and its reference torque T _ref =T _rate . The third part is the constant power area, and its reference torque can be expressed as:

Where P _rate is the rated power. It can be seen that these three parts are all related to K, which controls the rate of change of T _ref in the rising zone, and therefore also determines the values of the constant torque zone and constant power zone. When K is less than 1, T _ref will not reach T _rate , and when K is large, the intersection of the linear rising zone and the constant torque zone will move to the left. Therefore, the K value affects the control performance of the variable characteristic curve control method. For wave power generation systems with different sea areas, different wave periods and heights, the appropriate K value can be automatically selected according to the experimental results of different K values, so that the effect of the control method is the best. good. In Fig. 2, the automatic change of the K value is based on the wave input power proportional to the square of the wave height H and the wave period T (ie

) relationship, so that the corresponding rated power P _rate is calculated from the H and T collected by the system, and then the reference rated torque T _ref is obtained.

Figure 3 shows the electrical configuration of the variable characteristic curve control method. In Fig. 3, T _e is the estimated value of the electromagnetic torque, T _m is the input torque, J is the moment of inertia of the motor, and P is the output power of the motor.

The present invention adopts the method for measuring the rotational speed of the motor based on a single-chip microcomputer, fixes a 60-hole optical code disc on the shaft of the motor, modulates the constant light from an infrared emitting diode into a light pulse that changes with time, and then uses a photoelectric conversion circuit to convert the light pulse converted into electrical impulses. Set the internal timer T ₁ of the M430F149 single-chip microcomputer to the timing state (set to 1s), the internal timer T ₀ adopts the external counting state, and then use the T ₀ of the M430F149 to record the measured signal electric pulse m within the unit measurement time, and Ensure that the starting moment of the measurement time is synchronized with the rising edge of a certain pulse of the signal under test, and then use _T1 of the M430F149 to record the time Δt from the end of the unit time to the rising edge of the next pulse of the signal under test. In this way, m complete periods of the measured signal can be accurately recorded within t=(10 ⁶ +Δt)μs, and the measured rotational speed is n=m/t. Among them, the function of two external interrupts INT1 and INT0 is to control T ₁ and T ₀ timing and counting at the same time (INT1 controls T ₁ , INT0 controls T ₀ ).

Figure 4 is a flow chart of the variable characteristic curve controller. First, the motor speed ω _r is fed back to the variable characteristic curve control module, and the corresponding reference electromagnetic torque T _ref is found by combining the variable characteristic curve relationship shown in Figure 2 automatically established by the detected H and T values. If T _ref =T _e , then directly control the IGBT duty cycle of the motor side through the PID controller according to the reference power P _ref corresponding to T _ref ; if T _ref ≠T _e , let T _ref be the electromagnetic torque T _e , Calculate the reference output power P _ref from ω _r and T _e , according to the P _ref value, combined with the PID control algorithm, generate PWM waves to make the duty cycle of the IGBT in the voltage source converter reach the reference value, thereby controlling the actual output power value .

Claims (2)

1. A variable characteristic curve control method of a float type wave power generating device, the method at first obtains the torque-rotating speed curve of the float type wave power generating device through experiments or simulations, the slope of the first part of the linear rising zone assuming the curve is K, When controlling, first collect the wave cycle and wave height of the current wave, calculate the K value according to the relationship between the wave input power proportional to the square of the wave height and the wave cycle, and correct the torque-speed curve of the floater type wave power generation device, and then Then according to the measured motor speed, the motor torque corresponding to the measured motor speed is obtained by the look-up table method, which is regarded as the reference electromagnetic torque, and the corresponding reference output power is obtained according to the reference electromagnetic torque, and then The actual output power of the float type ocean wave generator is controlled according to the reference output power value. 2. The control method according to claim 1, characterized in that, according to the reference output power value, combined with a PID controller, a PWM wave is generated to change the duty cycle of the IGBT in the voltage source converter, thereby controlling the actual output power.

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