A method and system for selecting and designing brake resistors for wind turbine variable pitch systems based on load calculation

Abstract

The present application discloses a method for selecting and designing a brake resistor for a wind power generation variable pitch system based on load calculation, including: obtaining a blade root load sequence of a wind turbine generator set under various working conditions with a time interval of t by simulation; calculating the power of the variable pitch system under all working conditions according to the load sequence, counting the situations in which the variable pitch motor is in the power generation mode under all working conditions, and finding the maximum number of cycles k of continuous power generation of the variable pitch motor; calculating a 1‑k cycle continuous power generation value sequence under various working conditions; calculating a 1‑k cycle variable pitch system busbar capacitor energy absorption power value sequence; calculating a 1‑k cycle variable pitch system brake resistor power value sequence, and drawing a power curve of the brake resistor; selecting the brake resistor according to the brake resistor power value sequence and the brake resistor resistance value determined in the variable pitch controller design. The present invention avoids excessive selection while ensuring system performance, can effectively reduce system costs, and improve market competitiveness.

Description

Technical Field

[0001] The invention belongs to the technical field of wind power variable pitch systems, and relates to a method and system for selecting and designing a brake resistor of a wind power variable pitch system based on load calculation. Background Art

[0002] Wind power generation is an important part of the national new energy strategic planning. As a technology-intensive strategic emerging industry, the stability and safety of wind turbine power generation pose challenges to each of its components. As the control system and brake system of the wind turbine, the wind turbine pitch system undertakes the dual tasks of control and protection.

[0003] There are currently two mainstream solutions for pitch systems: hydraulic pitch and electric pitch. The electric pitch system uses a pitch motor to drive the wind turbine blades. The motor will feed back energy to the system when it is in the power generation or braking state. The feedback energy has the risk of damaging the system, so the brake resistor is needed to discharge the excess energy. Summary of the invention

[0004] In order to address the deficiencies in the prior art, the present application provides a method and system for selecting and designing brake resistors for a wind power variable pitch system based on load calculation, which can avoid thermal failure caused by selecting low power brake resistors and the problem of high cost due to selecting high power brake resistors.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation comprises the following steps:

[0007] Step 1: obtain the blade root load sequence of the wind turbine generator set under various working conditions with a time interval of t through simulation;

[0008] Step 2: Calculate the power of the variable pitch system under all working conditions according to the load sequence, count the situations in which the variable pitch motor is in the power generation mode under all working conditions, and find out the maximum number of cycles k of continuous power generation of the variable pitch motor;

[0009] Step 3: Calculate the 1-k period continuous power generation value sequence under each working condition;

[0010] Step 4: Calculate the energy power value sequence of the bus capacitor absorbed by the pitch system in 1-k cycles;

[0011] Step 5: Based on the sequence of steps 3 and 4, calculate the 1-k cycle variable pitch system brake resistor power value sequence and draw the power curve of the brake resistor;

[0012] Step 6: Select the brake resistor according to the brake resistor power value sequence and the brake resistor resistance value determined in the pitch controller design.

[0013] The present invention further includes the following preferred embodiments:

[0014] Preferably, in step 1, the IEC61400-1 standard and Germanischer Lloyd's GL wind turbine certification guide are used to set the working conditions of the wind turbine generator set and perform simulation calculations to obtain a time series file of blade root load data under various working conditions with a time interval of t, i.e., a load sequence.

[0015] Preferably, the simulation data included in each load data timing file includes time data, blade position data, blade speed data, and blade root torque data;

[0016] The simulation data is high-speed shaft data on the pitch motor side.

[0017] Preferably, step 2 specifically includes:

[0018] Step 2.1: Calculate the power of the pitch system under all working conditions based on the torque and speed in the load sequence;

[0019] Step 2.2: When the pitch system is in power generation mode, the power is negative. Count the situations where the pitch motor is in power generation mode in all working conditions and find the maximum number of cycles k of continuous power generation of the pitch motor.

[0020] Preferably, in step 2.1, the power calculation formula of the pitch system is:

[0021] P = T * N / 9549.297;

[0022] Among them, P is power, unit kW; T is torque, unit Nm; N is speed, unit r / min.

[0023] Preferably, in step 2.2, the minimum time period t in the load sequence is used to find the longest sequence in the continuous power generation situation in all working conditions, with a time of k*t, that is, continuous power generation for a maximum of k cycles, k>0, and the maximum number of continuous power generation cycles is k.

[0024] Preferably, in step 3, the RMS power value of 1-k cycles of continuous power generation under each operating condition is calculated respectively, and the maximum value of the RMS power value of 1-k cycles of continuous power generation is statistically obtained, which is recorded as the sequence of 1-k cycles of continuous power generation power value under each operating condition.

[0025] Preferably, in step 4, assuming that the busbar capacitance is C, the voltage is V1 when there is no feedback energy, and the maximum tolerable voltage is V2, the tolerable energy E is calculated;

[0026] Then, the relationship between power, time and energy E=P*T is used to calculate the sequence of power values ​​of energy absorbed by the capacitor when the time T is t, 2t, 3t...kt.

[0027] Preferably, in step 4, the energy E calculation formula is:

[0028] Preferably, in step 5, the power value of the brake resistor is calculated by subtracting the energy power absorbed by the bus capacitor from the power generated by the pitch system, and a power curve of the brake resistor is drawn according to the brake resistor power value sequence.

[0029] The present application also provides a wind power generation pitch control system brake resistor selection and design system based on load calculation, and the system is used to implement the above-mentioned wind power generation pitch control system brake resistor selection and design method based on load calculation.

[0030] Beneficial effects achieved by this application:

[0031] The present invention obtains the blade root load sequence of the wind turbine generator set through simulation, finds out the situation that the variable pitch motor is in the power generation mode in all working conditions, and calculates the maximum value of the root mean square power at different power generation durations to obtain the continuous power generation value sequence; the total energy that can be absorbed and the power value sequence of the bus capacitor absorbed energy converted to different durations are calculated according to the bus capacitor parameters of the variable pitch system; the feedback energy under the power generation condition of the variable pitch motor is absorbed by the system bus and the brake resistor, so the brake resistor power value sequence at different power generation durations can be calculated, thereby obtaining the power curve of the brake resistor; and then according to the brake resistor resistance value designed by the system, the appropriate brake resistor parameters can be determined to complete the selection design.

[0032] The load of wind turbine generator sets is the basis for designing wind turbine control systems. This invention combines the advanced experience and theoretical calculations in the industry to accurately obtain the load-based variable pitch system brake resistor technical parameters. While ensuring system performance, it avoids excessive selection, can effectively reduce system costs, and improve market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of a method for selecting and designing a brake resistor for a wind power generation variable pitch system based on load calculation according to the present invention;

[0034] Figure 2 This is a flow chart of a method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation according to the present invention;

[0035] Figure 3 This is an example diagram of the brake resistor power curve of the present invention. DETAILED DESCRIPTION

[0036] The present application is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present application.

[0037] like Figure 1-2 As shown, a method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation of the present invention comprises the following steps:

[0038] Step 1: obtain the blade root load sequence of the wind turbine generator set under various working conditions with a time interval of t through simulation;

[0039] In specific implementation, the wind power generation pitch control system of the present invention is an electronic control system, not a hydraulic pitch control system, and uses the IEC61400-1 standard and the Germanischer Lloyd's Register GL wind turbine certification guide to set the working conditions of the wind turbine generator set and perform simulation calculations to obtain a time series file of blade root load data under each working condition with a time interval of t, i.e., a load sequence;

[0040] The simulation data included in each load data timing file include time data, blade position data, blade speed data, and blade root torque data;

[0041] The simulation data is the high-speed shaft data on the pitch motor side. The time interval in the load sequence is t, which is generally 50ms.

[0042] Step 2: Calculate the power of the pitch system under all working conditions according to the load sequence, count the situations in which the pitch motor is in the power generation mode under all working conditions, and find out the maximum number of cycles k of continuous power generation of the pitch motor, including:

[0043] Step 2.1: Calculate the power of the pitch system under all working conditions based on the torque and speed in the load sequence;

[0044] P = T * N / 9549.297;

[0045] Among them, P is power, unit kW; T is torque, unit Nm; N is speed, unit r / min.

[0046] Step 2.2: When the pitch system is in the power generation mode, the power is negative. The situations where the pitch motor is in the power generation mode in all working conditions are counted to find the maximum number of cycles k of continuous power generation of the pitch motor.

[0047] In step 2.2, the minimum time period t in the load sequence, among all working conditions, find the longest sequence in the continuous power generation situation, the time is k*t, that is, the maximum continuous power generation is k cycles, k>0, the maximum number of continuous power generation cycles is k.

[0048] Step 3: Calculate the 1-k period continuous power generation value sequence under each working condition;

[0049] Specifically, the root mean square power value of 1-k cycles under each working condition is calculated respectively, and the maximum value of the root mean square power value of 1-k cycles is counted, which is recorded as the 1-k cycle continuous power generation value sequence;

[0050] The root mean square calculation method is:

[0051]

[0052] Among them, P k is the RMS value of power when k cycles of continuous power generation, in kW; T i is the torque of the ith cycle, in Nm; N i is the speed of the ith cycle, in r / min. i=1...k.

[0053] Step 4: Calculate the energy power value sequence of the bus capacitor absorbed by the pitch system in 1-k cycles;

[0054] Calculate the ability of the pitch system bus capacitor to withstand feedback energy.

[0055] Assuming the busbar capacitance is C, the voltage is V1 when there is no feedback energy, and the maximum voltage that can be tolerated is V2, the energy that can be tolerated is calculated to be

[0056] Then, the relationship between power, time and energy E=P*T is used to calculate the sequence of power values ​​of energy absorbed by the capacitor when the time T is t, 2t, 3t...kt.

[0057] Step 5: Based on the sequence of steps 3 and 4, calculate the 1-k cycle variable pitch system brake resistor power value sequence and draw the power curve of the brake resistor:

[0058] The braking resistor power value is calculated by subtracting the energy absorbed by the bus capacitor from the power generated by the pitch system. That is, the energy fed back by the system is absorbed by the bus capacitor and the braking resistor. Assuming that the braking resistor power is PC, the power generated by the pitch system is PMax. i -Bus capacitor absorbs energy power PD i = Braking resistor power PC i , so as to obtain the braking resistor power value required as the power generation time of the variable pitch system changes, and draw the power curve of the braking resistor according to the braking resistor power value sequence, such as Figure 3 shown.

[0059] Step 6: Select the brake resistor according to the brake resistor power value sequence and the brake resistor resistance value determined in the pitch controller design.

[0060] The resistance of the brake resistor is determined by the hardware design of the pitch system controller, and it is assumed here that the resistance is R. The brake resistor selection of the system can be determined based on the brake resistor power curve and resistance calculated by the above method.

[0061] The present application also provides a wind power generation pitch control system brake resistor selection and design system based on load calculation, and the system is used to implement the above-mentioned wind power generation pitch control system brake resistor selection and design method based on load calculation.

[0062] Example 1

[0063] A method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation of the present invention comprises:

[0064] Step 1: Simulate and obtain the load sequence of a 3.XMW wind turbine, and the minimum time period t of the load sequence is 50 milliseconds (ms);

[0065] Step 2: Calculate the longest cycle number k of the variable pitch system in the power generation mode under all working conditions to be 60.

[0066] Step 3: Select the power value at 1 cycle as the maximum instantaneous power of the braking resistor, the power value of 20 consecutive cycles as the 1-second (s) power of the braking resistor, the power value of 40 consecutive cycles as the 2-second power of the braking resistor, and the power value of 60 consecutive cycles as the 3-second power of the braking resistor;

[0067] According to the actual load sequence, calculate the instantaneous power of each cycle of the variable pitch system, and find the maximum value, that is, the instantaneous maximum power value P max = 22.18kW, calculate the RMS power of the variable pitch system per second (i.e. 20 consecutive cycles), and find the maximum value, i.e. the maximum power PMax of the system for 1 second of continuous power generation 1s =4.2kW, and similarly calculate the maximum power PMax of the system for continuous power generation for 2 seconds 2s =3.78kW, the maximum power PMax of the system for continuous power generation for 3 seconds 3s =1.48kW.

[0068] Step 4: The busbar capacitance C of the pitch system is 1.64 millifarads (mF). When the system has no energy feedback, the voltage V1 = 560 volts, and the maximum voltage that can be tolerated is V2 = 780 volts.

[0069] according to The calculated energy is 241.74 joules. According to E=P*T, the maximum power PD absorbed by the bus capacitor is calculated. max =4.8kW, 1 second power is PD 1s =241.74W, 2 seconds power is PD 1s =120.87W, 3 seconds power is PD 3s =80.58W.

[0070] Step 5: According to PMaxi -PD i =PC i It can be calculated that the instantaneous power of the braking resistor is PC max =17.35kW, 1 second power is PC 1s =3.99kW, 2 seconds power is PC 1s =3.66kW, 3 seconds power is PC 3s =1.4kW.

[0071] At the same time, a braking resistor power curve can be drawn according to the braking resistor power value of 1-60 cycles.

[0072] Step 6: According to the pitch controller design, the brake resistor value range is between 12 ohms and 20 ohms.

[0073] According to the above calculations, the maximum continuous working time of the variable pitch system brake resistor is 3 seconds. The final selected brake resistor has a resistance of 12 ohms, a continuous power (continuous operation without interruption) of 320W, a 30-fold overload when running for 1 second, that is, 9.6kW, a power of 7kW when running for 2 seconds, and a power of 6kW when running for 3 seconds, which meets the brake resistor selection parameter requirements. Considering the complex operating environment and difficult maintenance of the variable pitch system, the final resistor selection has a large margin.

[0074] The applicant of the present invention has made a detailed explanation and description of the implementation examples of the present invention in conjunction with the drawings in the specification. However, those skilled in the art should understand that the above implementation examples are only preferred implementation schemes of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, but not to limit the scope of protection of the present invention. On the contrary, any improvements or modifications based on the inventive spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation, characterized in that: The method comprises the following steps: Step 1: obtain the blade root load sequence of the wind turbine generator set under various working conditions with a time interval of t through simulation; Step 2: Calculate the power of the pitch system under all working conditions according to the load sequence, count the situations in which the pitch motor is in the power generation mode under all working conditions, and find out the maximum number of cycles k of continuous power generation of the pitch motor, including: Step 2.1: Calculate the power of the pitch system under all working conditions based on the torque and speed in the load sequence; The power calculation formula of the pitch system is: P = T*N / 9549.297; Among them, P is power, unit kW; T is torque, unit Nm; N is speed, unit r / min; Step 2.2: When the pitch system is in the power generation mode, the power is negative. The situations where the pitch motor is in the power generation mode in all working conditions are counted to find the maximum number of cycles k of continuous power generation of the pitch motor. In step 2.2, the minimum time period t in the load sequence, among all working conditions, find the longest sequence in the continuous power generation situation, the time is k*t, that is, the maximum continuous power generation is k cycles, k>0, the maximum number of continuous power generation cycles is k; Step 3: Calculate the 1-k period continuous power generation value sequence under each working condition; Step 4: Calculate the energy power value sequence of the bus capacitor absorbed by the pitch system in 1-k cycles; Step 5: Based on the sequence of steps 3 and 4, calculate the 1-k cycle variable pitch system brake resistor power value sequence and draw the power curve of the brake resistor; Step 6: Select the brake resistor according to the brake resistor power value sequence and the brake resistor resistance value determined in the pitch controller design.

2. The method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation according to claim 1 is characterized in that: In step 1, the IEC61400-1 standard and the Germanischer Lloyd's GL wind turbine certification guide are used to set the working conditions of the wind turbine generator set and perform simulation calculations to obtain the blade root load data time series file under each working condition with a time interval of t, that is, the load sequence.

3. The method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation according to claim 2 is characterized in that: The simulation data included in each load data timing file include time data, blade position data, blade speed data, and blade root torque data; The simulation data is high-speed shaft data on the pitch motor side.

4. The method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation according to claim 1 is characterized in that: In step 3, the root mean square value of the power of continuous power generation for 1-k cycles under each operating condition is calculated respectively, and the maximum value of the root mean square value of the power of continuous power generation for 1-k cycles is statistically obtained, which is recorded as the sequence of continuous power generation power values ​​for 1-k cycles under each operating condition.

5. The method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation according to claim 1 is characterized in that: In step 4, assuming that the busbar capacitance is C, the voltage is V1 when there is no feedback energy, and the maximum voltage that can be tolerated is V2, calculate the tolerable energy E; Then, the relationship between power, time and energy E=P*T is used to calculate the sequence of power values ​​of energy absorbed by the capacitor when the time T is t, 2t, 3t...kt.

6. The method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation according to claim 5 is characterized in that: In step 4, the energy E calculation formula is:

7. The method for selecting and designing a brake resistor for a wind power generation pitch control system based on load calculation according to claim 1, characterized in that: In step 5, the power value of the brake resistor is calculated by subtracting the energy power absorbed by the bus capacitor from the power generated by the pitch system, and a power curve of the brake resistor is drawn according to the power value sequence of the brake resistor.

8. A wind power generation variable pitch system brake resistor selection and design system based on load calculation, characterized by: The system is used to implement the method for selecting and designing the brake resistor of a wind power generation pitch control system based on load calculation as described in any one of claims 1 to 7.

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