CN113162494A - Efficiency optimization control method and system for brushless doubly-fed induction generator - Google Patents
Efficiency optimization control method and system for brushless doubly-fed induction generator Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
- H02P9/007—Control circuits for doubly fed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
- H02P21/18—Estimation of position or speed
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
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Abstract
The invention discloses an efficiency optimization control method and system for a brushless doubly-fed induction generator, belonging to the technical field of brushless doubly-fed induction generator control and comprising the following steps: (1) in the current control period, calculating output power according to a voltage amplitude feedback value and a resistive load value of a power winding, calculating direct current input power according to direct current bus voltage and direct current bus current, and calculating mechanical power converted into input electromagnetic power according to rotor angular velocity and electromagnetic torque so as to calculate the motor efficiency eta of the current control period; (2) if eta is larger than the current optimal motor efficiency, the optimal power generation efficiency is updated to eta, and the optimal power generation frequency is changed into etaUpdating the set value of the angular frequency of the control winding after the current generating frequency f is updated; (3) after the power generation frequency is increased by delta f, if the power generation frequency does not exceed the upper limit of the power generation frequency, the step (1) is carried out to start the efficiency optimization of the next control period; otherwise, make the generator followAnd (6) operating and finishing the optimization control. The invention can maximize the efficiency of the motor.
Description
Technical Field
The invention belongs to the technical field of brushless doubly-fed induction generator control, and particularly relates to a method and a system for optimizing and controlling efficiency of a doubly-fed induction generator.
Background
Brushless doubly-fed induction generator (BDFIG) has cancelled brush and sliding ring as a novel AC induction machine, compares in brush doubly-fed induction generator, not only operational reliability promotes by a wide margin, and is maintenance-free basically moreover, has good application prospect.
The brushless doubly-fed induction generator comprises two sets of stator Windings with different pole pairs, which are respectively called Power Windings (PW) and Control Windings (CW), and a rotor winding of the brushless doubly-fed induction generator is specially designed, so that rotating magnetic fields generated by the Power Windings and the Control Windings indirectly interact without direct coupling. The power winding is mainly used for controlling active power, and the control winding is mainly used for controlling reactive power and maintaining the voltage stability of the direct-current bus. The brushless doubly-fed induction generator can be applied to a ship shaft power generation system, a hydroelectric power generation system, a wind power generation system and the like.
The existing brushless doubly-fed induction generator adopts a constant-voltage constant-frequency power generation mode, namely, in the power generation process, the voltage and the power generation frequency of a direct-current bus are kept constant, so that electric energy which can be directly used can be obtained. However, the power generation mode is not beneficial to improving the energy utilization rate and energy conservation and emission reduction, and the special structure of the brushless double-fed induction generator also causes the motor efficiency to be low. The existing motor efficiency optimization control method mainly aims at a rotary induction motor and a linear induction motor, and in the field of brushless double-fed induction motors, research is concentrated on modeling and analyzing loss, and no corresponding efficiency optimization control method exists at present. Therefore, how to optimize the motor efficiency of the brushless doubly-fed induction generator is a problem to be solved urgently.
Disclosure of Invention
Aiming at the defects and improvement requirements of the prior art, the invention provides an efficiency optimization control method and system for a brushless double-fed induction generator, and aims to effectively solve the technical problem that the efficiency of the brushless double-fed induction generator is not high.
To achieve the above object, according to one aspect of the present invention, there is provided a method for controlling efficiency optimization of a brushless doubly-fed induction generator, comprising the steps of:
(1) in the current control period, according to the voltage amplitude feedback value U of the power windingpCalculating the output power P of the motor according to the resistive load value RoutAccording to the DC bus voltage UdcAnd DC bus current IdcCalculating DC input power P of motordcAnd obtaining the rotor angular speed omega of the brushless doubly-fed induction generatorrAnd electromagnetic torque TemTo calculate the mechanical power P converted into input electromagnetic poweremAnd calculating the motor efficiency of the current control period as eta-Pout/(Pem+Pdc);
(2) If the motor efficiency in the current control period is greater than the current optimal motor efficiency, the optimal power generation efficiency is updated to the motor efficiency in the current control period, and the optimal power generation frequency is obtainedUpdating the current generation frequency f in the current control period and obtaining the updated optimal generation frequencyUpdating control winding angular frequency given valueThen, turning to the step (3); otherwise, directly switching to the step (3);
(3) increasing the power generation frequency f by a preset frequency step length delta f to be used as a new power generation frequency f, and if the power generation frequency f is updated, generating the powerIf the rate f does not exceed the preset upper limit of the power generation frequency, taking the next control period as the current control period, and turning to the step (1); otherwise, the brushless doubly-fed induction generator is enabled to generate power according to the optimal power generation frequencyAnd (6) operating and finishing the optimization control.
Further, in the step (2), the optimal power generation frequency is updated according to the updated optimal power generation frequencyUpdating control winding angular frequency given valueThe method comprises the following steps:
will optimize the power generation frequencyEnlarging 2 pi times to obtain the angular frequency given value of the power winding
Angular velocity omega of rotorrEnlargement (p)p+pc) Given value of angular frequency of multiplied and power windingMaking difference to obtain the angular frequency given value of the control winding
Wherein p ispIs the number of pole pairs, p, of the power windingcTo control the number of winding pole pairs.
Further, in the step (1), the voltage amplitude feedback value U is fed back according to the power windingpCalculating the output power P of the motoroutBefore, still include:
obtaining three-phase voltage u of power windingp_abcAnd converting the voltage to an alpha beta coordinate system to obtain a power winding voltage alpha axis component upαAnd beta axisComponent upβAccording to the formulaCalculating the voltage amplitude feedback value U of the power winding in the current control periodp。
Further, in the step (1), the voltage is measured according to the DC bus voltage UdcAnd DC bus current IdcCalculating DC input power P of motordcBefore, still include:
setting value of preset power winding voltage amplitudeWith the feedback value U of the voltage amplitude of the power winding in the current control periodpPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding currentAnd setting a given value of q-axis component of the control winding current
Given value of angular frequency of current control windingIntegrating to obtain the given value of the coordinate transformation angle of the control winding
Transformation of angle set-point by control winding coordinatesWill control the three-phase current i of the windingc_abcConverting the abc coordinate system into the dq coordinate system to obtain a feedback value i of the d-axis component of the control winding currentcdAnd q-axis component feedback value icq;
Given value of d-axis component of control winding currentAnd a feedback value i of d-axis component of control winding currentcdPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding voltageFor setting the q-axis component of the control winding currentAnd a feedback value i of a q-axis component of the control winding currentcqPerforming PI control on the difference value to obtain a given value of a q-axis component of the control winding voltage
Transformation of angle set-point by control winding coordinatesSetting the d-axis component of the control winding voltageAnd q-axis component given valueConverting the abc coordinate system into the dq coordinate system to obtain the three-phase voltage given value of the control winding
According to the given value of three-phase voltage of the control windingGenerating PWM wave to control converter to output control winding three-phase voltage u actually required by motorc_abcAnd outputs the DC bus voltage U of the current control perioddcAnd DC bus current Idc。
Further, in the step (1), the rotor angular speed ω of the brushless doubly-fed induction generator is obtainedrAnd electromagnetic torque TemTo calculate the mechanical power P converted into input electromagnetic poweremThe method comprises the following steps:
obtaining mechanical torque T measured by a torque meter in a brushless doubly-fed induction generatormechAccording to Tem=Tmech-T0Calculating electromagnetic torque Tem;T0Representing the no-load torque of the torque meter;
obtaining a rotor position angle theta obtained by measuring a rotary encoder in a brushless doubly-fed induction generatorrAnd carrying out differentiation and LPF filtering in sequence to obtain the angular speed omega of the rotorr;
According to Pem=TemωrCalculating mechanical power P converted into input electromagnetic powerem。
According to another aspect of the present invention, there is provided a brushless doubly-fed induction generator efficiency optimization control system, comprising: a power winding frequency controller;
the power winding frequency controller includes: the device comprises an efficiency calculation module, a frequency iteration module and a control module;
an efficiency calculation module for calculating the feedback value U according to the voltage amplitude of the power winding in the current control periodpCalculating the output power P of the motor according to the resistive load value RoutAccording to the DC bus voltage UdcAnd DC bus current IdcCalculating DC input power P of motordcAnd obtaining the rotor angular speed omega of the brushless doubly-fed induction generatorrAnd electromagnetic torque TemTo calculate the mechanical power P converted into input electromagnetic poweremAnd calculating the motor efficiency of the current control period as eta-Pout/(Pem+Pdc) Then triggering a frequency iteration module;
a frequency iteration module for updating the optimal power generation efficiency to the optimal power generation efficiency when the motor efficiency in the current control period is higher than the current optimal motor efficiencyThe motor efficiency in the current control period will optimize the generation frequencyUpdating the current generation frequency f in the current control period and obtaining the updated optimal generation frequencyUpdating control winding angular frequency given valueThen triggering the control module; the frequency iteration module is also used for directly triggering the control module when the motor efficiency in the current control period is greater than the motor efficiency in the previous control period;
the control module is used for increasing the power generation frequency f by a preset frequency step length delta f to be used as a new power generation frequency f, and when the updated power generation frequency f does not exceed the preset upper limit of the power generation frequency, the next control cycle is used as the current control cycle and triggers the efficiency calculation module; when the updated generating frequency f exceeds the preset generating frequency upper limit, the brushless doubly-fed induction generator is enabled to generate power according to the optimal generating frequencyAnd (6) running and finishing the optimization control.
Further, the efficiency optimization control system of the brushless doubly-fed induction generator further comprises a power winding voltage calculator;
the power winding voltage calculator is to:
obtaining three-phase voltage u of power windingp_abcAnd converting the voltage to an alpha beta coordinate system to obtain a power winding voltage alpha axis component upαAnd a beta axis component upβAccording to the formulaCalculating the voltage amplitude feedback value U of the power winding in the current control periodp。
Furthermore, the efficiency optimization control system of the brushless doubly-fed induction generator further comprises a power winding voltage regulator and a control winding voltage controller;
the power winding voltage regulator is to:
setting value of preset power winding voltage amplitudeWith the feedback value U of the voltage amplitude of the power winding in the current control periodpPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding currentAnd setting a given value of q-axis component of the control winding current
Given value of angular frequency of current control windingIntegrating to obtain the given value of the coordinate transformation angle of the control winding
Transformation of angle set-point by control winding coordinatesWill control the three-phase current i of the windingc_abcConverting the abc coordinate system into the dq coordinate system to obtain a feedback value i of the d-axis component of the control winding currentcdAnd q-axis component feedback value icq;
Given value of d-axis component of control winding currentAnd a feedback value i of d-axis component of control winding currentcdPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding voltageFor setting the q-axis component of the control winding currentAnd a feedback value i of a q-axis component of the control winding currentcqPerforming PI control on the difference value to obtain a given value of a q-axis component of the control winding voltage
Transformation of angle set-point by control winding coordinatesSetting the d-axis component of the control winding voltageAnd q-axis component given valueConverting the abc coordinate system into the dq coordinate system to obtain the three-phase voltage given value of the control winding
The control winding voltage controller is for:
according to the given value of three-phase voltage of the control windingGenerating PWM wave to control converter to output control winding three-phase voltage u actually required by motorc_abcAnd outputs the DC bus voltage U of the current control perioddcAnd DC bus current Idc。
Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained:
(1) the invention gradually increases the power generation frequency within a preset range, realizes frequency iteration, calculates the efficiency of the motor under each power generation frequency in real time, correspondingly updates the optimal power generation frequency when the efficiency of the motor is optimized, and maintains the constant voltage of the direct current bus in the control process, thereby adjusting the power generation mode from a constant voltage and constant frequency mode to a constant voltage and variable frequency mode. The optimal power generation frequency which enables the efficiency of the motor to be maximum can be finally obtained, and the generator can run at the optimal power generation frequency, so that the aim of maximizing the efficiency of the motor can be achieved, the loss of the motor is minimized, the requirements of energy conservation and emission reduction are met, and the technical problem that the brushless double-fed induction generator is low in motor efficiency in a constant-voltage constant-frequency power generation mode is effectively solved.
(2) According to the invention, the power generation mode is adjusted from a constant-voltage constant-frequency type to a constant-voltage variable-frequency type, so that the input power and the loss power of the motor are changed when the frequency of the motor is adjusted under the condition of keeping the output power of the motor unchanged, at the moment, the power is redistributed, the maximum efficiency point can still be solved through frequency iteration, and the reasonable distribution of the power of the motor and the improvement of the efficiency are realized. The method is simple and reliable, has strong robustness, and is suitable for any system based on the brushless doubly-fed induction generator, such as a ship shaft-driven power generation system, a hydroelectric power generation system, a wind power generation system and the like based on the brushless doubly-fed induction generator.
Drawings
Fig. 1 is a flowchart of an efficiency optimization control method for a brushless doubly-fed induction generator according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an efficiency optimization control system of a brushless doubly-fed induction generator according to an embodiment of the present invention;
FIG. 3 shows the motor efficiency and motor loss at 600 rpm for BDFIG provided by an embodiment of the present invention;
FIG. 4 shows the motor efficiency and motor losses for a BDFIG at 750 rpm for an embodiment of the present invention;
fig. 5 shows the motor efficiency and motor loss of the BDFIG at 900 rpm according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In the present application, the terms "first," "second," and the like (if any) in the description and the drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
The invention provides a brushless double-fed induction generator efficiency optimization control method and system aiming at the technical problem that the existing brushless double-fed induction generator is low in power generation efficiency in a constant-voltage constant-frequency power generation mode, and the overall thought is as follows: the power generation mode of the brushless doubly-fed induction generator is adjusted from constant voltage and constant frequency to constant voltage and variable frequency through frequency iteration, the maximum motor efficiency is gradually solved in the frequency iteration process, and finally the brushless doubly-fed induction generator operates at the power generation frequency corresponding to the maximum motor efficiency, so that the purposes of efficiency maximization and motor loss minimization are achieved.
The following are examples.
Example 1:
an efficiency optimization control method for a brushless doubly-fed induction generator is shown in fig. 1, and comprises the following steps:
(1) in the current control period, according to the voltage amplitude feedback value U of the power windingpCalculating the output power P of the motor according to the resistive load value RoutAccording to the DC bus voltage UdcAnd DC bus current IdcCalculating DC input power P of motordcAnd obtaining the rotor angular speed omega of the brushless doubly-fed induction generatorrAnd electromagnetic torque TemTo calculate the mechanical power P converted into input electromagnetic poweremAnd calculating the motor efficiency of the current control period as eta-Pout/(Pem+Pdc);
In this embodiment, the output power PoutThe calculation formula of (2) is as follows:direct current transmissionInput power PdcThe calculation formula of (2) is as follows: pdc=UdcIdc;
In an alternative embodiment, in step (1), the rotor angular speed ω of the brushless doubly-fed induction generator is obtainedrAnd electromagnetic torque TemTo calculate the mechanical power P converted into input electromagnetic poweremThe method comprises the following steps:
obtaining mechanical torque T measured by a torque meter in a brushless doubly-fed induction generatormechAccording to Tem=Tmech-T0Calculating electromagnetic torque Tem;T0Representing the no-load torque of the torque meter;
obtaining a rotor position angle theta obtained by measuring a rotary encoder in a brushless doubly-fed induction generatorrAnd carrying out differentiation and LPF filtering in sequence to obtain the angular speed omega of the rotorr;
According to Pem=TemωrCalculating mechanical power P converted into input electromagnetic powerem;
(2) If the motor efficiency in the current control period is greater than the current optimal motor efficiency, the optimal power generation efficiency is updated to the motor efficiency in the current control period, and the optimal power generation frequency is obtainedUpdating the current generation frequency f in the current control period and obtaining the updated optimal generation frequencyUpdating control winding angular frequency given valueThen, turning to the step (3); otherwise, directly switching to the step (3);
in an alternative embodiment, in step (2), the optimal power generation frequency is updated according to the updated optimal power generation frequencyUpdating control winding angular frequency given valueThe method comprises the following steps:
will optimize the power generation frequencyEnlarging 2 pi times to obtain the angular frequency given value of the power winding
Angular velocity omega of rotorrEnlargement (p)p+pc) Given value of angular frequency of multiplied and power windingMaking difference to obtain the angular frequency given value of the control winding
Wherein p ispIs the number of pole pairs, p, of the power windingcFor controlling the number of winding pole pairs;
(3) increasing the power generation frequency f by a preset frequency step length delta f to be used as a new power generation frequency f, and if the updated power generation frequency f does not exceed a preset power generation frequency upper limit, taking the next control period as the current control period, and turning to the step (1); otherwise, the brushless doubly-fed induction generator is enabled to generate power according to the optimal power generation frequencyRunning and finishing the optimization control;
the upper limit of the generating frequency needs to be set correspondingly according to the actual working frequency range of the brushless doubly-fed motor; for example, in the embodiment, the actual operating frequency range of the brushless doubly-fed motor is 50Hz to 70Hz, and accordingly, the upper limit of the generating frequency is set to 70 Hz.
In step (1) of this embodiment, the feedback value U is obtained according to the voltage amplitude of the power windingpCalculating the output power P of the motoroutBefore, still include:
to obtainThree-phase voltage u of power windingp_abcAnd converting the voltage to an alpha beta coordinate system to obtain a power winding voltage alpha axis component upαAnd a beta axis component upβAccording to the formulaCalculating the voltage amplitude feedback value U of the power winding in the current control periodp。
In step (1) of this embodiment, the voltage is measured according to the DC bus voltage UdcAnd DC bus current IdcCalculating DC input power P of motordcBefore, still include:
setting a preset power winding voltage amplitude valueWith the feedback value U of the voltage amplitude of the power winding in the current control periodpDifference of (2)Feeding into PI regulator to correct differencePI control is carried out to obtain a d-axis component given value of the control winding currentAnd setting a given value of q-axis component of the control winding currentBy the signal processing mode, closed-loop control of the voltage amplitude of the power winding is realized; in order to simplify the control, as an alternative embodiment, in the present embodiment, the given value of the q-axis component of the control winding current is set to
Given value of angular frequency of current control windingIntegrating to obtain the given value of the coordinate transformation angle of the control winding
Transformation of angle set-point by control winding coordinatesWill control the three-phase current i of the windingc_abcConverting the abc coordinate system into the dq coordinate system to obtain a feedback value i of the d-axis component of the control winding currentcdAnd q-axis component feedback value icq;
Setting the d-axis component of the control winding currentAnd a feedback value i of d-axis component of control winding currentcdDifference of (2)Feeding into PI regulator to correct differencePI control is carried out to obtain a d-axis component given value of the control winding voltageSetting the q-axis component of the control winding currentAnd a feedback value i of a q-axis component of the control winding currentcqDifference of (2)Feeding into PI regulator to correct differencePerforming PI control to obtain the given value of the q-axis component of the control winding voltageBy the signal processing mode, closed-loop control of d-axis component and q-axis component of control winding current is realized;
transformation of angle set-point by control winding coordinatesSetting the d-axis component of the control winding voltageAnd q-axis component given valueConverting the abc coordinate system into the dq coordinate system to obtain the three-phase voltage given value of the control winding
According to the given value of three-phase voltage of the control windingGenerating PWM wave to control converter to output control winding three-phase voltage u actually required by motorc_abcAnd outputs the DC bus voltage U of the current control perioddcAnd DC bus current Idc(ii) a In the embodiment, the three-phase voltage given value of the control winding is usedThe input is input to an SVPWM controller to generate a required PWM wave.
In the embodiment, the power generation frequency is gradually increased within a preset range, frequency iteration is realized, the efficiency of the motor under each power generation frequency is calculated in real time, the optimal power generation frequency is updated correspondingly when the efficiency of the motor is optimized, and the voltage of the direct-current bus is kept constant in the control process, so that the power generation mode is adjusted from a constant-voltage constant-frequency mode to a constant-voltage variable-frequency mode. To complete the frequency iteration, at the initial moment, the optimal motor efficiency needs to be set to a small value, usually smaller thanThe motor efficiency in the constant voltage and constant frequency operating mode is only needed, as shown in fig. 1, in this embodiment, at the initial time of the motor operation, the optimal motor efficiency is initialized to η *0, the optimum power generation frequency isThe iteration number is n-1; f. of1The initial power generation frequency is represented and can be set according to the power generation frequency range of the brushless doubly-fed induction generator, optionally, in this embodiment, the initial power generation frequency is set to be power frequency, that is, 50Hz, and each time iteration is performed, the frequency step Δ f of the power generation frequency increase is 1 Hz;
in the embodiment, the power generation mode is adjusted from a constant-voltage constant-frequency mode to a constant-voltage variable-frequency mode, so that the optimal power generation frequency which enables the efficiency of the motor to be maximum can be finally obtained, and the generator can run at the optimal power generation frequency, therefore, the aim of maximizing the efficiency of the motor can be achieved, the loss of the motor is minimized, the requirements of energy conservation and emission reduction are met, and the technical problem that the brushless double-fed induction generator is low in motor efficiency in the constant-voltage constant-frequency power generation mode is effectively solved;
in the embodiment, the power generation mode is adjusted from the constant-voltage constant-frequency mode to the constant-voltage variable-frequency mode, so that under the condition of keeping the output power of the motor unchanged, the input power and the loss power of the motor are changed when the frequency of the motor is adjusted, at the moment, the power is redistributed, the maximum efficiency point can still be solved through frequency iteration, and the reasonable distribution of the power of the motor and the improvement of the efficiency are realized. The method is simple and reliable, has strong robustness, and is suitable for any system based on the brushless doubly-fed induction generator, such as a ship shaft-driven power generation system, a hydroelectric power generation system, a wind power generation system and the like based on the brushless doubly-fed induction generator.
Example 2:
there is provided a brushless doubly-fed induction generator efficiency optimization control system, as shown in fig. 2, comprising: the power winding frequency controller, the power winding voltage calculator, the power winding voltage regulator and the control winding voltage controller;
the power winding frequency controller includes: the device comprises an efficiency calculation module, a frequency iteration module and a control module;
an efficiency calculation module for calculating the feedback value U according to the voltage amplitude of the power winding in the current control periodpCalculating the output power P of the motor according to the resistive load value RoutAccording to the DC bus voltage UdcAnd DC bus current IdcCalculating DC input power P of motordcAnd obtaining the rotor angular speed omega of the brushless doubly-fed induction generatorrAnd electromagnetic torque TemTo calculate the mechanical power P converted into input electromagnetic poweremAnd calculating the motor efficiency of the current control period as eta-Pout/(Pem+Pdc) Then triggering a frequency iteration module;
a frequency iteration module for updating the optimal power generation efficiency to the motor efficiency in the current control cycle and updating the optimal power generation frequency when the motor efficiency in the current control cycle is greater than the current optimal motor efficiencyUpdating the current generation frequency f in the current control period and obtaining the updated optimal generation frequencyUpdating control winding angular frequency given valueThen triggering the control module; the frequency iteration module is also used for directly triggering the control module when the motor efficiency in the current control period is greater than the motor efficiency in the previous control period;
the control module is used for increasing the power generation frequency f by a preset frequency step length delta f to be used as a new power generation frequency f, and when the updated power generation frequency f does not exceed the preset upper limit of the power generation frequency, the next control cycle is used as the current control cycle and triggers the efficiency calculation module; when the updated generating frequency f exceeds the preset generating frequency upper limit, the brushless doubly-fed induction generator is enabled to generate power according to the optimal generating frequencyRunning and finishing the optimization control;
the power winding voltage calculator is to:
obtaining three-phase voltage u of power windingp_abcAnd converting the voltage to an alpha beta coordinate system to obtain a power winding voltage alpha axis component upαAnd a beta axis component upβAccording to the formulaCalculating the voltage amplitude feedback value U of the power winding in the current control periodp;
The power winding voltage regulator is to:
setting value of preset power winding voltage amplitudeWith the feedback value U of the voltage amplitude of the power winding in the current control periodpPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding currentAnd setting a given value of q-axis component of the control winding current
Given value of angular frequency of current control windingIntegrating to obtain the given value of the coordinate transformation angle of the control winding
Transformation of angle set-point by control winding coordinatesWill control the three-phase current i of the windingc_abcConverting the abc coordinate system into the dq coordinate system to obtain a feedback value i of the d-axis component of the control winding currentcdAnd q-axis component feedback value icq;
Given value of d-axis component of control winding currentAnd a feedback value i of d-axis component of control winding currentcdPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding voltageFor setting the q-axis component of the control winding currentAnd a feedback value i of a q-axis component of the control winding currentcqPerforming PI control on the difference value to obtain a given value of a q-axis component of the control winding voltage
Transformation of angle set-point by control winding coordinatesSetting the d-axis component of the control winding voltageAnd q-axis component given valueConverting the abc coordinate system into the dq coordinate system to obtain the three-phase voltage given value of the control winding
The control winding voltage controller is for:
according to the given value of three-phase voltage of the control windingGenerating PWM wave to control converter to output control winding three-phase voltage u actually required by motorc_abcAnd outputs the DC bus voltage U of the current control perioddcAnd DC bus current Idc;
In this embodiment, the detailed implementation of each module may refer to the description in the above method embodiment, and will not be repeated here.
By using the embodiment to carry out efficiency optimization control on the brushless doubly-fed induction generator, the generating frequency is increased from 50Hz to 70Hz, and the output power P is maintainedoutUnder the same condition, the rotating speeds of the brushless doubly-fed induction generator are respectively 600 rpm, 750 rpm and 900 rpm, and the generating efficiency and the motor loss of the brushless doubly-fed induction generator are respectively shown in fig. 3, fig. 4 and fig. 5. According to the experimental results shown in fig. 3 to fig. 5, based on the above embodiments, the motor efficiency of the brushless doubly-fed induction generator can be well optimized at different rotation speeds, and the motor loss is also effectively reduced, so that the efficiency optimization control method and the system for the brushless doubly-fed induction generator provided by the invention can effectively solve the technical problem that the existing brushless doubly-fed induction generator is not high in efficiency.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. A brushless doubly-fed induction generator efficiency optimization control method is characterized by comprising the following steps:
(1) in the current control period, according to the voltage amplitude feedback value U of the power windingpCalculating the output power P of the motor according to the resistive load value RoutAccording to the DC bus voltage UdcAnd DC bus current IdcCalculating DC input power P of motordcAnd obtaining the rotor angular speed omega of the brushless doubly-fed induction generatorrAnd electromagnetic torque TemTo calculate the mechanical power P converted into input electromagnetic poweremTo calculate the motor efficiency of the current control cycleIs eta ═ Pout/(Pem+Pdc);
(2) If the motor efficiency in the current control period is greater than the current optimal motor efficiency, the optimal power generation efficiency is updated to the motor efficiency in the current control period, and the optimal power generation frequency is obtainedUpdating the current generation frequency f in the current control period and obtaining the updated optimal generation frequencyUpdating control winding angular frequency given valueThen, turning to the step (3); otherwise, directly switching to the step (3);
(3) increasing the power generation frequency f by a preset frequency step length delta f to be used as a new power generation frequency f, and if the updated power generation frequency f does not exceed a preset power generation frequency upper limit, taking the next control period as the current control period, and turning to the step (1); otherwise, enabling the brushless doubly-fed induction generator to generate power according to the optimal power generation frequencyAnd (6) operating and finishing the optimization control.
2. The method for controlling efficiency optimization of brushless doubly fed induction generator as claimed in claim 1, wherein in said step (2), according to the updated optimal power generation frequencyUpdating control winding angular frequency given valueThe method comprises the following steps:
will optimize the power generation frequencyEnlarging 2 pi times to obtain the angular frequency given value of the power winding
Angular velocity omega of rotorrEnlargement (p)p+pc) Given value of angular frequency of multiplied and power windingMaking difference to obtain the angular frequency given value of the control winding
Wherein p ispIs the number of pole pairs, p, of the power windingcTo control the number of winding pole pairs.
3. A brushless doubly fed induction generator efficiency optimization control method as claimed in claim 1 or 2, characterized in that in said step (1), the feedback value U is fed back according to the power winding voltage amplitudepCalculating the output power P of the motoroutBefore, still include:
obtaining three-phase voltage u of power windingp_abcAnd converting the voltage to an alpha beta coordinate system to obtain a power winding voltage alpha axis component upαAnd a beta axis component upβAccording to the formulaCalculating the voltage amplitude feedback value U of the power winding in the current control periodp。
4. A brushless doubly fed induction generator efficiency optimization control method as claimed in claim 3, wherein in said step (1), based on said dc bus voltage UdcAnd DC bus current IdcCalculating DC input power P of motordcBefore, still include:
for preset powerGiven value of winding voltage amplitudeWith the feedback value U of the voltage amplitude of the power winding in the current control periodpPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding currentAnd setting a given value of q-axis component of the control winding current
Given value of angular frequency of current control windingIntegrating to obtain the given value of the coordinate transformation angle of the control winding
Transformation of angle set-point by control winding coordinatesWill control the three-phase current i of the windingc_abcConverting the abc coordinate system into the dq coordinate system to obtain a feedback value i of the d-axis component of the control winding currentcdAnd q-axis component feedback value icq;
Given value of d-axis component of control winding currentAnd a feedback value i of d-axis component of control winding currentcdPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding voltageFor setting the q-axis component of the control winding currentAnd a feedback value i of a q-axis component of the control winding currentcqPerforming PI control on the difference value to obtain a given value of a q-axis component of the control winding voltage
Transformation of angle set-point by control winding coordinatesSetting the d-axis component of the control winding voltageAnd q-axis component given valueConverting the abc coordinate system into the dq coordinate system to obtain the three-phase voltage given value of the control winding
6. As claimed in claim 1The efficiency optimization control method of the brushless doubly-fed induction generator according to the above item (2), wherein in the step (1), the rotor angular velocity ω of the brushless doubly-fed induction generator is obtainedrAnd electromagnetic torque TemTo calculate the mechanical power P converted into input electromagnetic poweremThe method comprises the following steps:
obtaining the mechanical torque T measured by a torque meter in the brushless doubly-fed induction generatormechAccording to Tem=Tmech-T0Calculating electromagnetic torque Tem;T0Representing the no-load torque of the torque meter;
obtaining a rotor position angle theta obtained by measuring a rotary encoder in the brushless doubly-fed induction generatorrAnd carrying out differentiation and LPF filtering in sequence to obtain the angular speed omega of the rotorr;
According to Pem=TemωrCalculating mechanical power P converted into input electromagnetic powerem。
7. A brushless doubly fed induction generator efficiency optimization control system, comprising: a power winding frequency controller;
the power winding frequency controller includes: the device comprises an efficiency calculation module, a frequency iteration module and a control module;
the efficiency calculation module is used for feeding back the value U according to the voltage amplitude of the power winding in the current control periodpCalculating the output power P of the motor according to the resistive load value RoutAccording to the DC bus voltage UdcAnd DC bus current IdcCalculating DC input power P of motordcAnd obtaining the rotor angular speed omega of the brushless doubly-fed induction generatorrAnd electromagnetic torque TemTo calculate the mechanical power P converted into input electromagnetic poweremAnd calculating the motor efficiency of the current control period as eta-Pout/(Pem+Pdc) Then triggering the frequency iteration module;
the frequency iteration module is used for judging whether the motor efficiency in the current control period is higher than the current optimal motor efficiencyUpdating the optimal power generation efficiency to the motor efficiency in the current control period, and updating the optimal power generation frequencyUpdating the current generation frequency f in the current control period and obtaining the updated optimal generation frequencyUpdating control winding angular frequency given valueThen triggering the control module; the frequency iteration module is also used for directly triggering the control module when the motor efficiency in the current control period is greater than the motor efficiency in the previous control period;
the control module increases the power generation frequency f by a preset frequency step length delta f to be used as a new power generation frequency f, and when the updated power generation frequency f does not exceed a preset power generation frequency upper limit, the control module takes the next control cycle as the current control cycle and triggers the efficiency calculation module; when the updated generating frequency f exceeds the preset generating frequency upper limit, the brushless doubly-fed induction generator is enabled to generate power according to the optimal generating frequencyAnd (6) running and finishing the optimization control.
8. A brushless doubly fed induction generator efficiency optimization control system as claimed in claim 7 further comprising a power winding voltage calculator;
the power winding voltage calculator is to:
obtaining three-phase voltage u of power windingp_abcAnd converting the voltage to an alpha beta coordinate system to obtain a power winding voltage alpha axis component upαAnd a beta axis component upβAccording to the formulaCalculating the voltage amplitude feedback value U of the power winding in the current control periodp。
9. A brushless doubly fed induction generator efficiency optimization control system as claimed in claim 8 further comprising a power winding voltage regulator and a control winding voltage controller;
the power winding voltage regulator is to:
setting value of preset power winding voltage amplitudeWith the feedback value U of the voltage amplitude of the power winding in the current control periodpPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding currentAnd setting a given value of q-axis component of the control winding current
Given value of angular frequency of current control windingIntegrating to obtain the given value of the coordinate transformation angle of the control winding
Transformation of angle set-point by control winding coordinatesWill control the three-phase current i of the windingc_abcConverting the abc coordinate system into the dq coordinate system to obtain a feedback value i of the d-axis component of the control winding currentcdAnd q-axis component feedback value icq;
Given value of d-axis component of control winding currentAnd a feedback value i of d-axis component of control winding currentcdPI control is carried out on the difference value to obtain a given value of a d-axis component of the control winding voltageFor setting the q-axis component of the control winding currentAnd a feedback value i of a q-axis component of the control winding currentcqPerforming PI control on the difference value to obtain a given value of a q-axis component of the control winding voltage
Transformation of angle set-point by control winding coordinatesSetting the d-axis component of the control winding voltageAnd q-axis component given valueConverting the abc coordinate system into the dq coordinate system to obtain the three-phase voltage given value of the control winding
The control winding voltage controller is configured to:
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