A bdfig-dc system harmonic copper loss minimization control device and method

Abstract

The application provides a BDFIG-DC system harmonic copper loss minimization control device and method, and belongs to the technical field of BDFIG control. The device comprises an MSC control system and a harmonic copper loss minimization control system. The MSC control system is connected to the CW side of the BDFIG and is used for stabilizing the DC bus voltage of the BDFIG-DC system. The harmonic current of the PW is controlled by using a CW harmonic current compensation mode. The harmonic copper loss minimization control system is connected to the PW side and is used for providing a CW harmonic current reference value. The PW of the BDFIG-DC system is connected to a three-phase uncontrolled rectifier bridge. The CW harmonic current reference value comprises a -5th harmonic current reference value and a 7th harmonic current reference value. The application minimizes the harmonic copper loss of the BDFIG and improves the system efficiency.

Description

Technical Field

[0001] This invention belongs to the field of BDFIG control technology, and more specifically, relates to a control device and method for minimizing harmonic copper loss in a BDFIG-DC system. Background Technology

[0002] BDFIG (Brushless Doubly Fed Induction Generator) is a new type of AC induction motor that consists of two sets of stator windings with different pole pairs and a specially designed rotor for coupling rotating magnetic fields with different pole pairs on the stator side. These two sets of stator windings are designated PW and CW according to the amount of energy transferred. Compared to traditional brushed doubly fed induction generators, BDFIG eliminates brushes and slip rings, and its high reliability and other characteristics give it significant advantages in applications such as ship shaft-driven power generation, wind power generation, and hydropower generation.

[0003] Compared to traditional AC power grids, DC power grids offer advantages such as zero reactive power flow, low losses, and simple parallel connection processes. Currently, there are many successful examples of integrating distributed renewable energy generation, such as wind and solar power, into DC microgrids both domestically and internationally, and it has become a research hotspot. However, in BDFIG-DC systems, the power supply (PW) is connected to the three-phase uncontrolled rectifier bridge, which generates significant -5th and 7th harmonics in the windings, leading to harmonic copper losses and a decrease in system efficiency. This is one of the main factors restricting the further development of this system and must be addressed through measures. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a control device and method for minimizing harmonic copper losses in a BDFIG-DC system. This invention addresses the problem that in existing BDFIG-DC systems, the PW is connected to a three-phase uncontrolled rectifier bridge, resulting in significant -5th and 7th harmonics in the windings, which in turn lead to harmonic copper losses and reduced system efficiency.

[0005] To achieve the above objectives, on the one hand, the present invention provides a BDFIG-DC system harmonic copper loss minimization control device, comprising: an MSC control system and a harmonic copper loss minimization control system;

[0006] The MSC control system is connected to the CW side of the BDFIG to stabilize the DC bus voltage of the BDFIG-DC system; and it uses the CW harmonic current compensation method to control the harmonic current of the PW.

[0007] The harmonic copper loss minimization control system is connected to the PW side of the BDFIG to provide a reference value for the CW harmonic current.

[0008] The PW of the BDFIG-DC system is connected to the three-phase uncontrolled rectifier bridge; the CW harmonic current reference value includes the -5th harmonic current reference value and the 7th harmonic current reference value of CW.

[0009] More preferably, the harmonic copper loss minimization control system includes: a PW voltage phase-locked loop module, a PW harmonic current reference value calculation module, a PW current separation module, and a PW harmonic current control module;

[0010] The PW voltage phase-locked loop module is used to control the three-phase voltage u in the PW stationary abc coordinate system. pa u pb u pc The voltage of PW in the positive-sequence fundamental frequency rotating coordinate system is obtained by sequentially performing improper integral, coordinate transformation, division, proportional-integral, addition, and integration operations. The angle θ of the PW fundamental voltage vector p and the angular velocity ω of the PW fundamental voltage vector p ;

[0011] The PW harmonic current reference value calculation module is connected to the PW voltage phase-locked loop module and is used to calculate the harmonic current reference value based on the PW harmonic current reference value calculation module. and ω p Calculate the PW harmonic current reference value required to achieve minimum copper loss control.

[0012] The PW current separation module is used to separate the three-phase current i in the PW stationary abc coordinate system. pa i pb i pc By sequentially performing coordinate transformations, addition operations, improper integration, and coordinate transformations, the actual current components of PW under the -5th and 7th rotation dq coordinates are obtained. and

[0013] The input terminal of the PW harmonic current control module is connected to the PW harmonic current reference value calculation module, which is used to calculate the harmonic current reference value. After sequentially performing PI calculations, coordinate transformations are performed to obtain the reference values ​​of the -5th and 7th harmonic currents of CW in the positive-sequence fundamental frequency rotating coordinate system.

[0014] More preferably, the MSC control system includes: a DC bus voltage control module, a CW total current calculation module, a CW current control module, a first coordinate transformation module, an SVPWM generator, a second coordinate transformation module, and a CW transformation angle calculation module;

[0015] The output of the DC bus voltage control module is connected to the CW total current calculation module to calculate the DC bus voltage reference value. and DC bus voltage feedback value U dc Obtain the reference value of the d-axis fundamental current of CW.

[0016] The output of the CW total current calculation module is connected to the input of the CW current control module; it is used to add the CW fundamental current reference value generated by the DC bus voltage control module to the -5th and 7th harmonic current reference values ​​of CW generated by the PW harmonic current control module to generate the CW total current reference value.

[0017] The output of the CW total current control module is connected to the first coordinate transformation module, which is used to compare the CW total current reference value obtained by the CW total current calculation module with the actual CW current value obtained by the second coordinate transformation module. and The difference is then used for proportional-integral resonance calculation to obtain the CW voltage reference value in the dq coordinate system. and

[0018] The output of the first coordinate transformation module is connected to the SVPWM generator to convert the CW voltage reference value in the dq coordinate system. and Transformed into reference values ​​of the α-axis component of CW in a two-phase stationary coordinate system and β-axis component reference value

[0019] The output of the second coordinate transformation module is connected to the CW current control module to control the a-phase current i of CW in the abc coordinate system. ca b-phase current i cb and c-phase current i cc Transformed into the d-axis component i of the CW current in the dq coordinate system cd and q-axis component i cq ;

[0020] The CW transformation angle calculation module is used to obtain the transformation reference angle based on the measured RW angular frequency and the given PW angular frequency.

[0021] The SVPWM generator is used to obtain a reference value for the α-axis component of CW in a two-phase stationary coordinate system. and β-axis component reference value It generates the PWM signal required by the MSC, thereby stabilizing the DC bus voltage of the BDFIG-DC system.

[0022] More preferably, the PW harmonic current control module includes a tenth adder, an eleventh adder, a twelfth adder, a thirteenth adder, a third PI controller, a fourth PI controller, a fifth PI controller, a sixth PI controller, a seventh coordinate transformer, and an eighth coordinate transformer.

[0023] The output of the tenth adder is connected to the input of the third PI controller; the output of the eleventh adder is connected to the input of the fourth PI controller; the outputs of the third and fourth PI controllers are connected to the input of the seventh coordinate transformer; the output of the twelfth adder is connected to the input of the fifth PI controller; the output of the thirteenth adder is connected to the input of the sixth PI controller; and the outputs of the fifth and sixth PI controllers are connected to the input of the eighth coordinate transformer.

[0024] The tenth, eleventh, twelfth, and thirteenth adders are used for performing... and Operations;

[0025] The third, fourth, fifth, and sixth PI controllers are respectively used for... and Perform proportional-integral calculations;

[0026] The seventh coordinate transformer is used to obtain the d-axis component of the -5th harmonic current reference value of CW in positive sequence fundamental frequency rotating coordinates. The q-axis component of the -5th harmonic current reference value of CW in positive sequence fundamental frequency rotating coordinates.

[0027] The eighth coordinate transformer is used to obtain the d-axis component of the 7th harmonic current reference value of CW in positive sequence fundamental frequency rotating coordinates. The q-axis component of the 7th harmonic current reference value of CW in positive sequence fundamental frequency rotating coordinates

[0028] On the other hand, the present invention provides a method for minimizing harmonic copper loss in a BDFIG-DC system, comprising the following steps:

[0029] A harmonic copper loss minimization control system is used to provide CW harmonic current reference values;

[0030] The harmonic current of the PW is controlled by using the CW harmonic current compensation method in the MSC control system, thereby reducing harmonic copper loss.

[0031] The PW of the BDFIG-DC system is connected to the three-phase uncontrolled rectifier bridge; the CW harmonic current reference value includes the -5th harmonic current reference value and the 7th harmonic current reference value of CW.

[0032] More preferably, the method for obtaining the CW harmonic current reference value is as follows:

[0033] For the three-phase voltage u in the PW stationary abc coordinate system pa u pb u pcThe voltage of PW in the positive-sequence fundamental frequency rotating coordinate system is obtained by sequentially performing improper integral, coordinate transformation, division, proportional-integral, addition, and integration operations. The angle θ of the PW fundamental voltage vector p and the angular velocity ω of the PW fundamental voltage vector p ;

[0034] according to and ω p Calculate the PW harmonic current reference value required to achieve minimum copper loss control.

[0035] in,

[0036] These are the d-axis and q-axis components of the -5th harmonic reference current in the -5th rotating coordinate system of PW, respectively. and These are the d-axis and q-axis components of the 7th harmonic reference current in the 7th rotating coordinate system of PW, respectively. The actual fundamental voltage d-axis component in the PW positive sequence fundamental frequency rotating coordinate system; ω p R is the fundamental voltage angular frequency of PW; p R c and R r The single-phase resistors for PW, CW, and RW are respectively; L p L c and L r The self-inductance of PW, CW, and RW respectively; L pr and L cr These refer to the mutual inductance between PW and RW, and between CW and RW, respectively.

[0037] For the three-phase current i in the PW stationary abc coordinate system pa i pb i pc By sequentially performing coordinate transformations, addition operations, improper integration, and coordinate transformations, the actual current components of PW under the -5th and 7th rotation dq coordinates are obtained. and

[0038] Will After sequentially performing PI calculations, coordinate transformations are performed to obtain the reference values ​​of the -5th and 7th harmonic currents of CW in the positive-sequence fundamental frequency rotating coordinate system.

[0039] More preferably, the method for controlling MSC includes the following steps:

[0040] Based on DC bus voltage reference value and DC bus voltage feedback value U dc Obtain the reference value of the d-axis fundamental current of CW.

[0041] The CW fundamental current reference value is added to the CW -5th and 7th harmonic current reference values ​​to generate the CW total current reference value.

[0042] Compare the reference value of CW total current with the actual value of CW current. and The difference is then used for proportional-integral resonance calculation to obtain the CW voltage reference value in the dq coordinate system. and

[0043] The CW voltage reference value in the dq coordinate system and Transformed into reference values ​​of the α-axis component of CW in a two-phase stationary coordinate system and β-axis component reference value

[0044] Let the a-phase current i in the CW coordinate system be... ca b-phase current i cb and c-phase current i cc Transformed into the d-axis component i of the CW current in the dq coordinate system cd and q-axis component i cq ;

[0045] The transformation reference angle is obtained based on the measured RW angular frequency and the given PW angular frequency.

[0046] Reference value of the α-axis component of CW in a two-phase stationary coordinate system and β-axis component reference value It generates the PWM signal required by the MSC, thereby enabling control of the MSC.

[0047] In summary, compared with the prior art, the above-described technical solutions conceived by this invention have the following advantages:

[0048] Beneficial effects:

[0049] This invention provides a harmonic copper loss minimization control device and method for a BDFIG-DC system. The aim is to reduce the possibility of harmonic copper loss and improve the efficiency of the BDFIG-DC system without adding an additional filter device. More specifically, this invention utilizes an MSC control system and uses CW harmonic current reference values ​​(the -5th and 7th harmonic components of CW) to compensate for the CW fundamental current reference value, thereby controlling the harmonic current of the PW to minimize the harmonic copper loss of the BDFIG and improve system efficiency. The harmonic copper loss minimization control system is connected to the PW side of the BDFIG to provide the CW harmonic current reference value; the CW harmonic current reference value includes the -5th and 7th harmonic current reference values ​​of the CW. More specifically, the three-phase voltage u in the stationary abc coordinate system of the PW is... pa u pb u pc The voltage of PW in the positive-sequence fundamental frequency rotating coordinate system is obtained by sequentially performing improper integral, coordinate transformation, division, proportional-integral, addition, and integration operations. The angle θ of the PW fundamental voltage vector p and the angular velocity ω of the PW fundamental voltage vector p ;according to and ω p Calculate the PW harmonic current reference value required to achieve minimum copper loss control. For the three-phase current i in the PW stationary abc coordinate system pa i pb i pc By sequentially performing coordinate transformations, addition operations, improper integration, and coordinate transformations, the actual current components of PW under the -5th and 7th rotation dq coordinates are obtained. and Will After sequentially performing PI calculations, coordinate transformations are performed to obtain the reference values ​​of the -5th and 7th harmonic currents of CW in the positive-sequence fundamental frequency rotating coordinate system. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the harmonic copper loss minimization control method for the BDFIG-DC system provided in an embodiment of the present invention;

[0051] Figure 2 This is a schematic diagram of the DC bus voltage control module provided in an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the CW total current calculation module provided in an embodiment of the present invention;

[0053] Figure 4This is a schematic diagram of the CW current control module provided in an embodiment of the present invention;

[0054] Figure 5 This is a schematic diagram of the structure of the PW voltage phase-locked loop module provided in an embodiment of the present invention;

[0055] Figure 6 This is a schematic diagram of the PW harmonic current reference value calculation module provided in an embodiment of the present invention;

[0056] Figure 7 This is a schematic diagram of the PW current separation module provided in an embodiment of the present invention;

[0057] Figure 8 This is a schematic diagram of the structure of the PW harmonic current control module provided in an embodiment of the present invention. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0059] The following explains the relevant concepts in this invention:

[0060] The abc coordinate system corresponds to the three-phase symmetrical stationary windings of an AC motor. It has three coordinate axes, a, b, and c, which intersect at the origin. The three coordinate axes are stationary in space and symmetrically distributed with a difference of 120 degrees between them. In a clockwise direction, they are a, b, and c, respectively.

[0061] Two-phase stationary coordinate system: Corresponds to the virtual two-phase orthogonal stationary windings of the AC motor, with two coordinate axes, α and β, intersecting at the origin. The two coordinate axes are stationary in space and differ from each other by 90 degrees. In the counterclockwise direction, they are the α axis and the β axis, respectively.

[0062] A rotating coordinate system with a positive-sequence fundamental frequency dq: It has two coordinate axes, d-axis and q-axis, intersecting at the origin. These two axes are 90 degrees apart (in a counter-clockwise direction, they are the d-axis and q-axis, respectively), and rotate at an angular velocity ω. p Rotate counterclockwise; where ω p The rotational angular velocity of the fundamental component of the PW voltage;

[0063] A negative 5th order rotation dq coordinate system: It has two coordinate axes, the d-axis and the q-axis, intersecting at the origin. These two axes are 90 degrees apart (in a counter-clockwise direction, they are the d-axis and the q-axis, respectively), and rotate at an angular velocity of -5ω. p Rotate clockwise;

[0064] A seventh-order rotating dq coordinate system: It has two coordinate axes, the d-axis and the q-axis, intersecting at the origin. These two axes are 90 degrees apart (in a counter-clockwise direction, they are the d-axis and the q-axis, respectively), and rotate at an angular velocity of 7ω. p Rotate counterclockwise;

[0065] In this invention, the α-axis and the a-axis coincide;

[0066] In this invention, if the dq coordinate system in which the electrical quantity is located is not marked in the upper right corner, it is assumed to be the positive sequence fundamental frequency rotating coordinate system: dq coordinate system;

[0067] The p in the lower right corner of the electrical quantity represents the PW side, dq and αβ represent the two-phase rotating coordinate system and the two-phase stationary coordinate system, respectively, and the number represents the harmonic order; the number in the upper right corner represents the order of the rotating coordinate system, "*" represents the reference value, and "~" above the variable represents the conjugate of the variable;

[0068] Fundamental component: refers to the component whose frequency is the same as the rated frequency;

[0069] Harmonic components: components whose frequency is an integer multiple of the rated frequency;

[0070] PI controller: A commonly used concept in motor control; in this invention, the PI controllers are all of the following forms. Where, k p For proportional gain, k i Here, is the integral gain, and s is the Laplace operator. It sequentially performs proportional and integral operations on the deviation between the reference value and the feedback value of the control target, as provided by the PI controller. The results of the proportional and integral operations are then added together to form the control quantity, which controls the controlled object. p and k i The debugging method is as follows: First, set k i Set it to 0, then gradually increase k. p k until the control target experiences overshoot. p It stops changing; then gradually increase k. i This continues until the adjustment time of the control target meets the user's needs.

[0071] PIR controller: In this invention, both the first PIR controller and the second PIR controller are of the form of... Where, k p For proportional gain, k i For integral gain, k r For the resonant gain, ω c ω is the cutoff frequency (typically taken as 5-20 rad / s). nHere, is the resonant frequency (generally set according to the frequency of the harmonic signal), s is the Laplace operator, which sequentially performs proportional, integral, and resonant calculations on the deviation between the reference value and the feedback value of the control target, as given by the PIR controller; then, the results of the proportional, integral, and resonant calculations are added together to form the control quantity, which controls the controlled object; k p k i and k r The debugging method is as follows:

[0072] 1. First, set k r Set it to 0, and debug k according to the PI controller debugging method. p and k i Parameter: First set k i Set it to 0, then gradually increase k. p k until the control target experiences overshoot. p It stops changing; then gradually increase k. i This continues until the adjustment time of the control target meets the user's needs.

[0073] 2. Guarantee k p and k i With parameters unchanged, a resonant tuning signal is added, changing k. r Parameter: First set k i Set it to 0, then gradually increase k. r Continue until the resonant signal tracking effect meets the user's requirements;

[0074] SVPWM Generator: The SVPWM generator in this invention belongs to this category; taking the ideal flux linkage circle of the stator of a three-phase symmetrical motor when powered by a three-phase symmetrical sinusoidal voltage as a reference standard, and making appropriate switching of different switching modes of the three-phase inverter to form a PWM wave, the actual flux linkage vector formed is used to track its accurate flux linkage circle.

[0075] The physical meanings involved in this invention are shown in the table below:

[0076]

[0077]

[0078]

[0079] Example 1

[0080] like Figure 1 As shown, this invention provides a method for minimizing harmonic copper loss in a BDFIG-DC system, comprising the following steps:

[0081] The DC bus voltage is stabilized using an MSC (control winding side converter). Simultaneously, the harmonic current of the PW is controlled using a CW harmonic current reference value compensation method. The PW of the BDFIG is connected to a three-phase uncontrolled rectifier bridge, resulting in significant -5th and 7th harmonics in the PW voltage and current. The CW harmonic current reference value includes both the -5th and 7th harmonic current reference values ​​of the CW.

[0082] More specifically, the MSC control system includes a DC bus voltage control module, a CW total current calculation module, a CW current control module, a first coordinate transformation module, an SVPWM generator, a second coordinate transformation module, and a CW transformation angle calculation module;

[0083] The output of the DC bus voltage control module is connected to the CW total current calculation module to calculate the DC bus voltage reference value. and DC bus voltage feedback value U dc Obtain the reference value of the d-axis fundamental current of CW.

[0084] The CW total current calculation module is used to add the CW fundamental current reference value generated by the DC bus voltage control module to the -5th and 7th harmonic current reference values ​​of CW generated by the PW harmonic current control module to generate the CW total current reference value.

[0085] The output of the CW current control module is connected to the first coordinate transformation module; it is used to compare the CW current reference value obtained by the CW total current calculation module with the actual CW current value obtained by the second coordinate transformation module. and The difference is then used for proportional-integral-resonance calculation to obtain the voltage reference value in the CWdq coordinate system. and

[0086] The output of the first coordinate transformation module is connected to the SVPWM generator; it is used to convert the voltage reference value of the CWdq coordinate system. and Transformed into reference values ​​of the α-axis component of CW in a two-phase stationary coordinate system and β-axis component reference value The specific transformation formula is as follows:

[0087]

[0088] The output of the second coordinate transformation module is connected to the CW current control module to control the a-phase current i of CW in the abc coordinate system. ca b-phase current i cb and c-phase current i ccTransformed into the d-axis component i of the CW current in the dq coordinate system cd and q-axis component i cq The specific transformation formula is as follows:

[0089]

[0090] Wherein, the reference angle θ is transformed c Obtained from the PW voltage phase-locked loop module, the calculation formula is ω c =(p p +p c )ω r -ω p ; for ω c Perform integration to obtain θ c ;

[0091] Where, ω r ω is the angular frequency of RW; p p is the angular frequency of PW; p and p c These are the PW pole pairs and the CW pole pairs, respectively; ω c The angular frequency of CW;

[0092] The CW transformation angle calculation module is used to obtain the transformation reference angle based on the measured RW angular frequency and the given PW angular frequency.

[0093] The SVPWM generator is used to obtain a reference value for the α-axis component of CW in a two-phase stationary coordinate system. and β-axis component reference value It generates the PWM signal required by the MSC, thereby stabilizing the DC bus voltage of the BDFIG-DC system.

[0094] The harmonic copper loss minimization control system includes: a PW voltage phase-locked loop module, a PW harmonic current reference value calculation module, a PW current separation module, and a PW harmonic current control module;

[0095] The PW voltage phase-locked loop module is used to control the three-phase voltage u in the PW stationary abc coordinate system. pa u pb u pc The voltage of PW in the positive-sequence fundamental frequency rotating coordinate system is obtained by sequentially performing improper integral, coordinate transformation, division, proportional-integral, addition, and integration operations. The angle θ of the PW fundamental voltage vector p and the angular velocity ω of the PW fundamental voltage vector p ;

[0096] The PW harmonic current reference value calculation module is connected to the PW voltage phase-locked loop module and is used to calculate the harmonic current reference value based on the PW harmonic current reference value calculation module. and ω pCalculate the reference value of PW harmonic current required to achieve minimum copper loss control.

[0097] The PW current separation module is used to separate the three-phase current i in the PW stationary abc coordinate system. pa i pb i pc By sequentially performing coordinate transformation, addition, improper integration, and coordinate transformation, the actual current components under the -5th and 7th rotation dq coordinates on the PW side are obtained. and

[0098] The input terminal of the PW harmonic current control module is connected to the PW harmonic current reference value calculation module, which is used to calculate the harmonic current reference value. After sequentially performing PI calculations, coordinate transformations are performed to obtain the reference values ​​of the -5th and 7th harmonic currents of CW in the positive-sequence fundamental frequency rotating coordinate system.

[0099] Specifically, such as Figure 2 As shown, the DC bus voltage control module includes a first adder and a first PI controller; the first adder is used to input the DC bus voltage reference value. With DC bus voltage feedback value u dc Difference; the first PI controller is used to... Perform proportional-integral calculations to output the d-axis fundamental current reference value of CW.

[0100] Specifically, such as Figure 3 As shown, the CW total current calculation module includes a second adder and a third adder. The second adder is used to... and conduct The calculation yields the reference value of the total d-axis current of CW. The third adder is used to... and conduct The calculation yields the reference value for the total q-axis current of CW.

[0101] Specifically, such as Figure 4 As shown, the CW current control module includes a fourth adder, a fifth adder, a first PIR controller, and a second PIR controller; the fourth adder is used to input the d-axis current reference value of the CW. Compared with the actual current value i cd Subtraction The fifth adder is used to input the q-axis current reference value of CW. Compared with the actual current value i cq Subtraction The first PIR controller and the second PIR controller are respectively used for... and By performing proportional-integral resonance calculations, the voltage reference value in the dq coordinate system of CW is obtained. and Send to the first coordinate transformation module;

[0102] Specifically, such as Figure 5 As shown, the PW voltage phase-locked loop module includes a first generalized integrator, a third coordinate transformer, a first amplitude arithmetic unit, a first divider, a second PI controller, a sixth adder, and a first integrator.

[0103] The first generalized integrator is used to convert the three-phase voltage u in the PW stationary abc coordinate system. pabc The transfer function for filtering is:

[0104]

[0105]

[0106] Among them, u f u(s) is the value of the input signal after filtering; u(s) is the input signal; k is the damping coefficient; ω is the resonant frequency; s is the Laplace transform symbol, and its value is jω; qu f (s) is u f (s) Values ​​lagging by 90 degrees;

[0107] The third coordinate transformer is used to perform coordinate transformation on the obtained PW fundamental voltage to obtain the PW voltage in the positive sequence fundamental rotating coordinate system;

[0108] To prevent the voltage amplitude from affecting the phase-locked loop, a first amplitude calculator and a first divider were specially set up so that the quantity entering the second PI controller is independent of the amplitude.

[0109] The sixth adder adds the angular frequency reference value to the output of the second PI controller to obtain the angular frequency of the PW voltage, which is then passed through the first integrator to obtain the PW voltage θ. p ;

[0110] Specifically, such as Figure 6 As shown, the PW harmonic current reference value calculation module obtains the PW harmonic current reference value required to minimize harmonic copper loss.

[0111]

[0112]

[0113] in:

[0114]

[0115] in, and These are the d-axis and q-axis components of the -5th harmonic reference current in the -5th rotating coordinate system of PW, respectively. and These are the d-axis and q-axis components of the 7th harmonic reference current in the 7th rotating coordinate system of PW, respectively. The actual fundamental voltage d-axis component in the PW positive sequence fundamental frequency rotating coordinate system; ω p R is the fundamental voltage angular frequency of PW; p R c and R r The single-phase resistors for PW, CW, and RW are respectively; L p L c and L r The self-inductance of PW, CW, and RW respectively; L pr L cr These refer to the mutual inductance between PW and RW, and between CW and RW, respectively.

[0116] Specifically, such as Figure 7 As shown, the PW current separation module includes a fourth coordinate transformer, a seventh adder, an eighth adder, a ninth adder, a second second-order generalized integrator, a third second-order generalized integrator, a fourth second-order generalized integrator, a fifth coordinate transformer, and a sixth coordinate transformer.

[0117] The fourth coordinate transformer is used to transform the three-phase current i in the PW stationary abc coordinate system. pa i pb i pc Transformed into a two-phase stationary αβ coordinate system current i pα and i pβ This current undergoes subtraction operations through the seventh, eighth, and ninth adders. pαβ -i pαβ-5 -i pαβ7 i pαβ -i pαβ-5 -i pαβ1 and i pαβ -i pαβ7 -i pαβ1 The obtained difference is fed into the second, third, and fourth generalized integrators, whose transfer functions are:

[0118]

[0119]

[0120] Among them, i f(s) is the value of the input signal after filtering; i(s) is the input signal; D(s) is the transfer function; Q(s) is the transfer function; qi f (s) is related to i f (s) values ​​that differ by 90 degrees;

[0121] The obtained i pαβ1 i pαβ-5 i pαβ7 All of these are quantities in the two-phase stationary αβ coordinate system, therefore they are transformed to the corresponding dq rotation coordinate systems through coordinate transformation; i pαβ-5 The coordinates are transformed to a -5th order rotation coordinate system using the fifth coordinate transformer, resulting in the following transformation: ;change i pαβ7 The coordinates are transformed to a 7th rotation coordinate system using the sixth coordinate transformer, resulting in the following transformation: ;

[0122] Specifically, such as Figure 8 As shown, the PW harmonic current control module includes a tenth adder, an eleventh adder, a twentieth adder, a thirteenth adder, a third PI controller, a fourth PI controller, a fifth PI controller, a sixth PI controller, a seventh coordinate transformer, and an eighth coordinate transformer.

[0123] The tenth, eleventh, twelfth, and thirteenth adders are used for performing... and The third, fourth, fifth, and sixth PI controllers are used for calculations; and Perform proportional-integral calculations; the seventh coordinate transformer is used to obtain the d-axis component of the -5th harmonic current reference value of CW in positive-sequence fundamental frequency rotating coordinates. The q-axis component of the -5th harmonic current reference value of CW in positive sequence fundamental frequency rotating coordinates. The eighth coordinate transformation module is used to obtain the d-axis component of the 7th harmonic current reference value of CW in positive sequence fundamental frequency rotating coordinates. The q-axis component of the 7th harmonic current reference value of CW in positive sequence fundamental frequency rotating coordinates The basis for coordinate transformation is:

[0124]

[0125]

[0126]

[0127]

[0128] in, This represents the value of the -5th harmonic component of the electrical quantity in the positive sequence fundamental frequency rotating coordinate system. This represents the value of the -5th harmonic of an electrical quantity in a -5th rotating coordinate system. This represents the value of the 7th harmonic of an electrical quantity in a rotating coordinate system based on the positive sequence fundamental frequency. The value of the 7th harmonic component of the electrical quantity in the 7th rotating coordinate system.

[0129] Example 2

[0130] This invention provides a method for minimizing harmonic copper loss in a BDFIG-DC system, comprising the following steps:

[0131] A harmonic copper loss minimization control system is used to provide CW harmonic current reference values;

[0132] The harmonic current of the PW is controlled by using the CW harmonic current compensation method in the MSC control system, thereby stabilizing the DC bus voltage of the BDFIG-DC system.

[0133] The PW of the BDFIG-DC system is connected to the three-phase uncontrolled rectifier bridge; the CW harmonic current reference value includes the -5th harmonic current reference value and the 7th harmonic current reference value of CW.

[0134] More preferably, the method for obtaining the CW harmonic current reference value is as follows:

[0135] For the three-phase voltage u in the PW stationary abc coordinate system pa u pb u pc The voltage of PW in the positive-sequence fundamental frequency rotating coordinate system is obtained by sequentially performing improper integral, coordinate transformation, division, proportional-integral, addition, and integration operations. The angle θ of the PW fundamental voltage vector p and the angular velocity ω of the PW fundamental voltage vector p ;

[0136] according to and ω p Calculate the PW harmonic current reference value required to achieve minimum copper loss control.

[0137] For the three-phase current i in the PW stationary abc coordinate system pa i pb i pc By sequentially performing coordinate transformations, addition operations, improper integration, and coordinate transformations, the actual current components of PW under the -5th and 7th rotation dq coordinates are obtained. and

[0138] Will After sequentially performing PI calculations, coordinate transformations are performed to obtain the reference values ​​of the -5th and 7th harmonic currents of CW in the positive-sequence fundamental frequency rotating coordinate system.

[0139] More preferably, the MSC control method includes the following steps:

[0140] Based on DC bus voltage reference value and DC bus voltage feedback value U dc Obtain the reference value of the d-axis fundamental current of CW.

[0141] The fundamental current reference value of CW is added to the -5th and 7th harmonic current reference values ​​of CW to generate the total current reference value of CW.

[0142] Compare the reference value of CW total current with the actual value of CW current. and The difference is then used for proportional-integral resonance calculation to obtain the CW voltage reference value in the dq coordinate system. and

[0143] The CW voltage reference value in the dq coordinate system and Transformed into reference values ​​of the α-axis component of CW in a two-phase stationary coordinate system and β-axis component reference value

[0144] Let the a-phase current i in the CW coordinate system be... ca b-phase current i cb and c-phase current i cc Transformed into the d-axis component i of the CW current in the dq coordinate system cd and q-axis component i cq ;

[0145] The transformation reference angle is obtained based on the measured RW angular frequency and the given PW angular frequency.

[0146] Reference value of the α-axis component of CW in a two-phase stationary coordinate system and β-axis component reference value It generates the PWM signal required by the MSC, thereby stabilizing the DC bus voltage of the BDFIG-DC system.

[0147] More preferably, the PW harmonic current reference value required to achieve minimum copper loss control for:

[0148]

[0149]

[0150] in, and These are the d-axis and q-axis components of the -5th harmonic reference current in the -5th rotating coordinate system of PW, respectively. and These are the d-axis and q-axis components of the 7th harmonic reference current in the 7th rotating coordinate system of PW, respectively. The actual fundamental voltage d-axis component in the PW positive sequence fundamental frequency rotating coordinate system; ω p R is the fundamental voltage angular frequency of PW; p R c and R r The single-phase resistors for PW, CW, and RW are respectively; L p L c and L r The self-inductance of PW, CW, and RW respectively; L pr and L cr These refer to the mutual inductance between PW and RW, and between CW and RW, respectively.

[0151] Compared with the prior art, the present invention has the following advantages:

[0152] This invention provides a harmonic copper loss minimization control device and method for a BDFIG-DC system. The aim is to reduce the possibility of harmonic copper loss and improve the efficiency of the BDFIG-DC system without adding an additional filter device. More specifically, this invention utilizes an MSC control system and uses CW harmonic current reference values ​​(the -5th and 7th harmonic components of CW) to compensate for the CW fundamental current reference value, thereby controlling the harmonic current of the PW to minimize the harmonic copper loss of the BDFIG and improve system efficiency. The harmonic copper loss minimization control system is connected to the PW side of the BDFIG and provides the CW harmonic current reference value; the CW harmonic current reference value includes the -5th and 7th harmonic current reference values ​​of the CW. More specifically, the three-phase voltage u in the stationary abc coordinate system of the PW is... pa u pb u pc The voltage of PW in the positive-sequence fundamental frequency rotating coordinate system is obtained by sequentially performing improper integral, coordinate transformation, division, proportional-integral, addition, and integration operations. The angle θ of the PW fundamental voltage vector p and the angular velocity ω of the PW fundamental voltage vector p ;according to and ω p Calculate the PW harmonic current reference value required to achieve minimum copper loss control. For the three-phase current i in the PW stationary abc coordinate system pa i pb i pc By sequentially performing coordinate transformations, addition operations, improper integration, and coordinate transformations, the actual current components of PW under the -5th and 7th rotation dq coordinates are obtained. and Will After sequentially performing PI calculations, coordinate transformations are performed to obtain the reference values ​​of the -5th and 7th harmonic currents of CW in the positive-sequence fundamental frequency rotating coordinate system.

[0153] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A harmonic copper loss minimization control device for a BDFIG-DC system, characterized in that, include: MSC control system and harmonic copper loss minimization control system; The MSC control system is connected to the CW side of the BDFIG to stabilize the DC bus voltage of the BDFIG-DC system; and the harmonic current of the PW is controlled by the CW harmonic current compensation method. The harmonic copper loss minimization control system is connected to the PW side of BDFIG to provide a reference value for the CW harmonic current. The PW of the BDFIG-DC system is connected to the three-phase uncontrolled rectifier bridge; the CW harmonic current reference value includes the -5th harmonic current reference value and the 7th harmonic current reference value of CW. The harmonic copper loss minimization control system includes: a PW voltage phase-locked loop module, a PW harmonic current reference value calculation module, a PW current separation module, and a PW harmonic current control module. The PW voltage phase-locked loop module is used to control the PW static state. Three-phase voltage in coordinate system , , The voltage of PW in the positive-sequence fundamental frequency rotating coordinate system is obtained by sequentially performing improper integral, coordinate transformation, division, proportional-integral, addition, and integration operations. Angle of PW fundamental voltage vector and the angular velocity of the PW fundamental voltage vector ; The PW harmonic current reference value calculation module is connected to the PW voltage phase-locked loop module and is used to calculate based on... and Calculate the PW harmonic current reference value required to achieve minimum copper loss control. , , , ; The PW current separation module is used to control the PW static state. Three-phase current in coordinate system , , By sequentially performing coordinate transformations, addition operations, improper integrals, and coordinate transformations, the -5th rotation of PW is obtained. Coordinates and 7 rotations Actual current components in coordinate system and ; The input terminal of the PW harmonic current control module is connected to the PW harmonic current reference value calculation module, which is used to calculate the harmonic current reference value. , , , After sequentially performing PI calculations, coordinate transformations are performed to obtain the reference values ​​of the -5th and 7th harmonic currents of CW in the positive-sequence fundamental frequency rotating coordinate system. , , , ; Among them, the PW harmonic current reference value required to achieve minimum copper loss control , , , for: in, ; and These are the d-axis and q-axis components of the -5th harmonic reference current in the -5th rotating coordinate system of PW, respectively. and These are the d-axis and q-axis components of the 7th harmonic reference current in the 7th rotating coordinate system of PW, respectively. The actual fundamental voltage d-axis component in the PW positive sequence fundamental frequency rotating coordinate system; The fundamental voltage angular frequency of PW; , and These are the single-phase resistors for PW, CW, and RW, respectively. , and The self-inductances are PW, CW, and RW, respectively; and These refer to the mutual inductance between PW and RW, and between CW and RW, respectively.

2. The BDFIG-DC system harmonic copper loss minimization control device according to claim 1, characterized in that, The MSC control system includes: a DC bus voltage control module, a CW total current calculation module, a CW current control module, a first coordinate transformation module, an SVPWM generator, a second coordinate transformation module, and a CW transformation angle calculation module; The output of the DC bus voltage control module is connected to the CW total current calculation module, used to calculate the DC bus voltage reference value. DC bus voltage feedback value Get CW d Shaft base current reference value ; The output terminal of the CW total current calculation module is connected to the input terminal of the CW current control module; it is used to add the fundamental current reference value of CW generated by the DC bus voltage control module and the -5th and 7th harmonic current reference values ​​of CW generated by the PW harmonic current control module to generate the total current reference value of CW. The output of the CW total current control module is connected to the first coordinate transformation module, which is used to compare the CW total current reference value obtained by the CW total current calculation module with the actual CW current value obtained by the second coordinate transformation module. and The operation involves performing a proportional-integral-harmonic resonance calculation on the obtained difference to obtain... CW voltage reference value in coordinate system and ; The output of the first coordinate transformation module is connected to the SVPWM generator, used to convert... CW voltage reference value in coordinate system and Transformed into CW in a two-phase stationary coordinate system α Axis component reference value and β Axis component reference value ; The output of the second coordinate transformation module is connected to the CW current control module for use in... CW in coordinate system a Phase current , b Phase current and c Phase current Transform into CW current in coordinate system d Axial components and q Axial components ; The CW transformation angle calculation module is used to obtain the transformation reference angle based on the measured RW angular frequency and the given PW angular frequency. The SVPWM generator is used for CW based on a two-phase stationary coordinate system. α Axis component reference value and β Axis component reference value This generates the PWM signal required by the MSC, thereby stabilizing the DC bus voltage of the BDFIG-DC system.

3. The BDFIG-DC system harmonic copper loss minimization control device according to claim 1, characterized in that, The PW harmonic current control module includes a tenth adder, an eleventh adder, a twelfth adder, a thirteenth adder, a third PI controller, a fourth PI controller, a fifth PI controller, a sixth PI controller, a seventh coordinate transformer, and an eighth coordinate transformer. The output of the tenth adder is connected to the input of the third PI controller; the output of the eleventh adder is connected to the input of the fourth PI controller; the outputs of the third and fourth PI controllers are connected to the input of the seventh coordinate transformer; the output of the twelfth adder is connected to the input of the fifth PI controller; the output of the thirteenth adder is connected to the input of the sixth PI controller; and the outputs of the fifth and sixth PI controllers are connected to the input of the eighth coordinate transformer. The tenth, eleventh, twelfth, and thirteenth adders are respectively used for performing... , , and Operations; The third, fourth, fifth, and sixth PI controllers are respectively used for... , , and Perform proportional-integral calculations; The seventh coordinate transformer is used to obtain the reference value of the -5th harmonic current of CW in the positive sequence fundamental frequency rotating coordinate. Axial components Reference value of the -5th harmonic current of CW in positive sequence fundamental frequency rotating coordinates Axial components ; The eighth coordinate transformer is used to obtain the reference value of the 7th harmonic current of CW in positive-sequence fundamental frequency rotating coordinates. Axial components Reference value of the 7th harmonic current of CW in positive sequence fundamental frequency rotating coordinates Axial components .

4. A method for minimizing harmonic copper loss in a BDFIG-DC system based on the BDFIG-DC system harmonic copper loss minimization control device according to claim 1 or 3, characterized in that, Includes the following steps: A harmonic copper loss minimization control system is used to provide CW harmonic current reference values; The harmonic current of the PW is controlled by using the CW harmonic current compensation method in the MSC control system, thereby reducing harmonic copper loss. The PW of the BDFIG-DC system is connected to the three-phase uncontrolled rectifier bridge. The CW harmonic current reference values ​​include the -5th harmonic current reference value and the 7th harmonic current reference value for CW.

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