Offshore wind turbine generator converter motor side control method and system

Abstract

The invention discloses an offshore wind turbine generator converter motor side control method and system. The method comprises the following steps: acquiring motor current, and performing coordinate transformation to obtain d-axis current and q-axis current under a two-phase synchronous rotating coordinate system; respectively comparing the output active power effective value with an active power reference value and comparing the output reactive power effective value with a reactive power reference value, and then obtaining an active current reference value and a reactive current reference value through PI regulation; respectively comparing the active current reference value and the reactive current reference value with d-axis current and q-axis current of the two control loops, and respectively obtaining d-axis voltage and q-axis voltage of the two control loops through current loop PI regulation and decoupling feedforward; and the d-axis voltage and the q-axis voltage of the two control loops drive corresponding phase IGBTs after being subjected to coordinate inverse transformation and a PWM (pulse-width modulation) strategy respectively. By improving the control strategy, the performance of the converter is improved, the electric energy quality and the electromagnetic compatibility are improved, and the optimized control method reduces the calorific value, improves the response speed and improves the economic benefit.

Description

Technical Field

[0001] This invention relates to the field of wind turbine converter technology, specifically to a motor-side control method and system for an offshore wind turbine converter. Background Technology

[0002] With increasing global emphasis on clean energy and continuous technological advancements, wind power, as a clean and renewable energy source, is playing an increasingly important role. This is particularly true in the field of offshore wind power, where the unique characteristics of the marine environment, such as abundant wind resources and stable wind speeds, have led to the widespread application of offshore wind turbines. During the operation of offshore wind turbines, the converter, as a crucial piece of equipment, directly affects multiple aspects of the entire wind power system, including power quality, electromagnetic compatibility, heat generation, response speed, and communication functions. Therefore, the performance requirements for converters are extremely high.

[0003] As a core component in a converter, the performance of IGBTs directly impacts the overall performance of the converter. Specifically, IGBT response parameters include switching speed, on-resistance, and saturation voltage drop, which significantly affect the converter's efficiency, stability, and reliability. Currently, different IGBTs exhibit variations in their response parameters, which directly influences converter performance.

[0004] To address this issue, how to achieve domestic substitution and reduce production costs while ensuring converter performance is an urgent problem to be solved in the current wind power generation field. Summary of the Invention

[0005] To address the issue of differences in IGBT response parameters affecting converter performance, this invention proposes a motor-side control method and system for offshore wind turbine converters.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for controlling the motor side of an offshore wind turbine converter includes the following steps:

[0008] The motor current is collected and transformed to obtain the d-axis and q-axis currents in a two-phase synchronous rotating coordinate system.

[0009] The effective value of the output active power is compared with the reference value of active power and the effective value of reactive power are compared with the reference value of reactive power respectively, and then the active current reference value and reactive current reference value are obtained through PI regulation.

[0010] The active current reference value and reactive current reference value are compared with the d-axis currents of the two control loops, respectively. After current loop PI regulation and decoupling feedforward, the d-axis voltages of the two control loops are obtained respectively.

[0011] The d-axis and q-axis voltages of the two control loops are then driven by the corresponding IGBTs after undergoing inverse coordinate transformation and PWM strategy.

[0012] The collected motor current is transformed to obtain the d-axis and q-axis currents in a two-phase synchronous rotating coordinate system, specifically:

[0013] The collected current is transformed by Clark to obtain the current in a two-phase stationary coordinate system, and then transformed by Park to obtain the d-axis and q-axis currents in a two-phase synchronous rotating coordinate system.

[0014] The effective value of the output active power is compared with the active power reference value, and then the active current reference value is obtained by PI regulation through the power loop and then by 1 / 2 regulator. The effective value of the output reactive power is compared with the reactive power reference value by a comparator, and then the reactive current reference value is obtained by PI regulation through the power loop and then by 1 / 2 regulator.

[0015] The active current reference value and reactive current reference value are compared with the d-axis and q-axis currents of the two control loops, respectively. After current loop PI regulation and decoupling feedforward, the d-axis and q-axis voltages of the two control loops are obtained, specifically as follows:

[0016] The active current reference value and reactive current reference value are input into two control loops respectively. The active current reference value is compared with the current on the q-axis, and after being adjusted by the PI of the current loop, the decoupling feedforward and flux feedforward of the d-axis are added to obtain the voltage on the q-axis. The reactive current reference value is compared with the current on the d-axis, and after being adjusted by the PI of the current loop, the decoupling feedforward of the q-axis is added to obtain the voltage on the d-axis.

[0017] The effective values ​​of active power and reactive power are calculated based on the real-time current and voltage of the motor.

[0018] A converter motor-side control system for an offshore wind turbine includes a permanent magnet synchronous motor, which is controlled by two control loops, each of which includes an outer loop control and an inner loop control.

[0019] The outer loop control uses power control, which compares the effective values ​​of active power and reactive power with the reference values ​​through a comparator, and then adjusts the current value through the power loop PI regulator. The current value is then adjusted by the 1 / 2 regulator to obtain the current reference value.

[0020] The inner loop control uses current control. The active current reference value and reactive current reference value are compared with the d-axis current of the two control loops by comparators. The current difference obtained after comparison is passed through the current loop PI regulator and simultaneously decoupled feedforward regulation. The d-axis voltage is then obtained through the regulator. The q-axis voltage value is also fed forward by flux linkage and output through the comparator. The d-axis voltage of the two control loops is then transformed by Park transformation and Clark transformation to obtain the three-phase voltage. After passing through the PWM strategy, the corresponding phase IGBT is driven.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The control method of this invention can be applied to the motor side of the converter in offshore wind turbines, improving converter performance and enhancing its performance in terms of power quality, electromagnetic compatibility, heat generation, response speed, and communication functions in grid connection and generator control. Simultaneously, the control method and system of this invention have advantages such as simple structure, ease of implementation, and low cost, which is conducive to promoting the localization of wind power generation technology. This invention effectively improves the power quality and electromagnetic compatibility of the converter through optimized control strategies. This helps reduce grid harmonic pollution, improves power utilization efficiency, and reduces the impact of electromagnetic interference on equipment and other systems, enhancing system stability and reliability. By precisely controlling the switching process of the IGBT, this invention reduces the heat generated by the converter during operation, improves heat dissipation efficiency, and thus extends the service life of the equipment. At the same time, the optimized control strategy also improves the converter's response speed, enabling it to respond more quickly to grid changes and load fluctuations, improving the dynamic performance of the system. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below:

[0024] Figure 1 This is a flowchart illustrating the control method for the motor side of the converter in an offshore wind turbine according to the present invention.

[0025] Figure 2 This is a schematic diagram of the control strategy for the motor side of the converter in the offshore wind turbine of the present invention. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings:

[0027] like Figure 1 As shown, the present invention provides a control method for the motor side of an offshore wind turbine converter, the specific steps of which are as follows: a power control outer loop is adopted, and a current decoupling control inner loop is adopted;

[0028] The motor current is collected and transformed to obtain the d-axis and q-axis currents in a two-phase synchronous rotating coordinate system.

[0029] The effective value of the output active power is compared with the reference value of active power and the effective value of reactive power are compared with the reference value of reactive power respectively, and then the active current reference value and reactive current reference value are obtained through PI regulation.

[0030] The active current reference value and reactive current reference value are compared with the d-axis currents of the two control loops, respectively. After current loop PI regulation and decoupling feedforward, the d-axis voltages of the two control loops are obtained respectively.

[0031] The d-axis and q-axis voltages of the two control loops are then driven by the corresponding IGBTs after undergoing inverse coordinate transformation and PWM strategy.

[0032] like Figure 2 As shown, the control method for the motor side of the converter of this offshore wind turbine specifically includes the following steps:

[0033] Collect motor current I sabc The current I in the two-phase stationary coordinate system is obtained after Clark transformation. sαβ Current I sαβ After Park transformation, the current I in the two-phase synchronous rotating coordinate system is obtained. sdq ;

[0034] Compare the output RMS value of active power with the active power reference value P. sref After comparison by the comparator, the active current reference value I is obtained through power loop PI regulation and then through a 1 / 2 regulator. sqref The effective value of the output reactive power is compared with the reactive power reference value Q. sref After comparison by a comparator, the reactive current reference value I is obtained through power loop PI regulation and then through a 1 / 2 regulator. sdref .

[0035] The active current reference value I sqref and reactive current reference value I sdref Two control loops are input separately, with active current reference value I. sqref Current I along the q-axis sq The voltage U on the q-axis is obtained by comparing the voltage after current loop PI regulation, plus decoupling feedforward on the d-axis and flux feedforward. sq reactive current reference value I sdref Current I along the d-axis sd By comparing the voltage U on the d-axis after current loop PI regulation and the addition of decoupling feedforward on the q-axis, we obtain the voltage U on the d-axis. sd ;

[0036] The q-axis voltage U of the two control loops sqand the voltage U along the d-axis sd After the inverse transformations of the Park and Clark transformations and the PWM strategy, the corresponding phase IGBT is driven.

[0037] The effective values ​​of active power and reactive power are based on the real-time current I of the motor. sabc and voltage U sabc Calculated.

[0038] The mathematical model of the permanent magnet synchronous motor used in the control method of the converter motor side of the offshore wind turbine in this invention is as follows:

[0039] The voltage equation and flux linkage equation of the permanent magnet synchronous motor in synchronous rotating coordinates can be obtained through coordinate transformation theory, as follows:

[0040]

[0041] Substituting the flux linkage equation into the voltage equation, we obtain the total voltage equation, which is:

[0042]

[0043] Since the rotor flux linkage is constant and its derivative is 0, after reorganizing the formula and removing the invariant inductance term, the voltage equation is as follows:

[0044]

[0045] Among them U sd U sq For the d-axis and q-axis components of the motor, I sd I sq R represents the d-axis and q-axis voltage components of the stator current. s Winding resistance, ω is the electrical angular velocity, and p is the number of pole pairs of the motor. The magnetic flux generated by the permanent magnet remains constant. For stator direct-axis inductance; For stator quadrature-axis inductance; L sσ This is due to stator leakage.

[0046] The present invention also provides a control system for the motor side of an offshore wind turbine converter, comprising: a permanent magnet synchronous motor, wherein the permanent magnet synchronous motor is controlled by two control loops, and each control loop includes an outer loop control and an inner loop control;

[0047] The outer loop control uses power control, which compares the effective values ​​of active power and reactive power with the reference values ​​through a comparator, and then adjusts the current value through the power loop PI regulator. The current value is then adjusted by the 1 / 2 regulator to obtain the current reference value.

[0048] The inner loop control uses current control. The active current reference value and reactive current reference value are compared with the d-axis current of the two control loops by comparators. The current difference obtained after comparison is passed through the current loop PI regulator and simultaneously decoupled feedforward regulation. The d-axis voltage is then obtained through the regulator. The q-axis voltage value is also fed forward by flux linkage and output through the comparator. The d-axis voltage of the two control loops is then transformed by Park transformation and Clark transformation to obtain the three-phase voltage. After passing through the PWM strategy, the corresponding phase IGBT is driven.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A control method for the motor side of an offshore wind turbine converter, characterized in that, include: The motor current is collected and the d-axis and q-axis currents in a two-phase synchronous rotating coordinate system are obtained through coordinate transformation. The effective value of the output active power is compared with the reference value of active power and the effective value of reactive power are compared with the reference value of reactive power respectively, and then the active current reference value and reactive current reference value are obtained through PI regulation. The active current reference value and reactive current reference value are compared with the d-axis currents of the two control loops, respectively. After current loop PI regulation and decoupling feedforward, the d-axis voltages of the two control loops are obtained respectively. The d-axis and q-axis voltages of the two control loops are then driven by the corresponding IGBTs after undergoing inverse coordinate transformation and PWM strategy.

2. The method for controlling the motor side of an offshore wind turbine converter according to claim 1, characterized in that, The collected motor current is transformed to obtain the d-axis and q-axis currents in a two-phase synchronous rotating coordinate system, specifically: The collected current is transformed by Clark to obtain the current in a two-phase stationary coordinate system, and then transformed by Park to obtain the d-axis and q-axis currents in a two-phase synchronous rotating coordinate system.

3. The method for controlling the motor side of an offshore wind turbine converter according to claim 1, characterized in that, The active power RMS value is compared with the active power reference value and the reactive power RMS value with the reactive power reference value respectively, and then the active current reference value and reactive current reference value are obtained through PI regulation. The effective value of the output active power is compared with the reference value of active power, and then the active current reference value is obtained by PI regulation through the power loop and then through the 1 / 2 regulator. The effective value of the output reactive power is compared with the reference value of reactive power by a comparator, then adjusted by the power loop PI, and finally obtained by the 1 / 2 regulator to obtain the reference value of reactive current.

4. The method for controlling the motor side of an offshore wind turbine converter according to claim 1, characterized in that, The active current reference value and reactive current reference value are compared with the d-axis and q-axis currents of the two control loops, respectively. After current loop PI regulation and decoupling feedforward, the d-axis and q-axis voltages of the two control loops are obtained, specifically as follows: The active current reference value and reactive current reference value are input into two control loops respectively. The active current reference value is compared with the current on the q-axis, and after being adjusted by the PI of the current loop, the decoupling feedforward and flux feedforward of the d-axis are added to obtain the voltage on the q-axis. The reactive current reference value is compared with the current on the d-axis, and after being adjusted by the PI of the current loop, the decoupling feedforward of the q-axis is added to obtain the voltage on the d-axis.

5. The method for controlling the motor side of an offshore wind turbine converter according to claim 1, characterized in that, The effective values ​​of active power and reactive power are calculated based on the real-time current and voltage of the motor.

6. The control system of the offshore wind turbine converter motor side control method according to claim 1, characterized in that, This includes permanent magnet synchronous motors, which are controlled by two control loops, each of which includes an outer loop control and an inner loop control. The outer loop control uses power control, which compares the effective values ​​of active power and reactive power with the reference values ​​through a comparator, and then adjusts the current value through the power loop PI regulator. The current value is then adjusted by the 1 / 2 regulator to obtain the current reference value. The inner loop control uses current control. The active current reference value and reactive current reference value are compared with the d-axis current of the two control loops by comparators. The current difference obtained after comparison is passed through the current loop PI regulator and simultaneously decoupled feedforward regulation. The d-axis voltage is then obtained through the regulator. The q-axis voltage value is also fed forward by flux linkage and output through the comparator. The d-axis voltage of the two control loops is then transformed by Park transformation and Clark transformation to obtain the three-phase voltage. After passing through the PWM strategy, the corresponding phase IGBT is driven.

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