CN110970904A - Reactive power control method of internal feedback generator grid-connected power generation system - Google Patents
Reactive power control method of internal feedback generator grid-connected power generation system Download PDFInfo
- Publication number
- CN110970904A CN110970904A CN201811148096.0A CN201811148096A CN110970904A CN 110970904 A CN110970904 A CN 110970904A CN 201811148096 A CN201811148096 A CN 201811148096A CN 110970904 A CN110970904 A CN 110970904A
- Authority
- CN
- China
- Prior art keywords
- winding
- axis
- reference value
- rotor
- axis current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1885—Arrangements for adjusting, eliminating or compensating reactive power in networks using rotating means, e.g. synchronous generators
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Eletrric Generators (AREA)
Abstract
A reactive power control method of an internal feedback generator grid-connected power generation system comprises the following steps: step one, a q-axis current reference value iqs2 *Is configured as 0, and determines the current q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor windingqr *(ii) a Step two, judging the current q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor windingqr *Whether the value meets the preset condition or not, if so, executing a third step; step three, according to the d-axis current reference value i of the rotor windingdr *And the maximum value I of the amplitude of the steady-state current allowed to be output by the rotor-side convertermaxReference value i of d-axis current for rotor windingqr *Make a correctionAccording to the corrected d-axis current reference value i of the rotor windingqr *Re-determining the q-axis current reference i of the feedback windingqs2 *. The method can accurately determine the d-axis current reference value i of the rotor winding under each reactive power output valueqr *And a q-axis current reference i of the feedback windingqs2 *The value of (2) lays a foundation for the grid-connected power generation of the grid-connected power generation system of the internal feedback generator.
Description
Technical Field
The invention relates to the technical field of grid-connected power generation, in particular to a reactive power control method of an internal feedback generator grid-connected power generation system and a grid-connected power generation control method of the internal feedback generator grid-connected power generation system.
Background
Wind power is one of the fastest growing energy sources in the world in recent years. The double-fed generator is one of the mainstream modes of grid-connected variable-speed constant-frequency wind power generation at present.
As shown in fig. 1, in the conventional grid-connected variable speed constant frequency wind power generation system based on the double-feedback generator, the electrical part of the system is mainly composed of a low-voltage doubly-fed generator 101, a matched low-voltage doubly-fed converter 102 and a boost grid-connected transformer 103. The variable-speed constant-frequency control of the system is realized by a low-voltage doubly-fed converter 102 on the rotor side of a doubly-fed generator 101, and the active power flowing through the low-voltage doubly-fed converter 102 is only the slip power of the doubly-fed generator 101, so that the capacity and the control difficulty of the low-voltage doubly-fed converter 102 are greatly reduced. However, since the generator stator and the doubly-fed converter 102 are designed at low voltage, a step-up grid-connected transformer 103 for connecting to the high-voltage grid is indispensable. Since the grid-connected transformer 103 is usually installed on the ground near the tower of the wind turbine, the requirement for the ground of the wind farm is increased, and the cost of the whole wind power generation system is also increased.
Disclosure of Invention
In order to solve the above problems, the present invention provides a reactive power control method for an internal feedback generator grid-connected power generation system, the method comprising:
step one, a q-axis current reference value i of a feedback winding of an internal feedback generator is usedqs2 *Is configured to be 0 according to a preset reactive power reference value
Determining a current q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor windingqr *；
Step two, judging the current q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor windingqr *Whether the value of (a) meets a preset condition, wherein if the value of (a) meets the preset condition, the third step is executed;
step three, according to the d-axis current reference value i of the rotor windingdr *And the maximum value I of the amplitude of the steady-state current allowed to be output by the rotor-side convertermaxReference value i of d-axis current for rotor windingqr *Correcting according to the corrected d-axis current reference value i of the rotor windingqr *Re-determining the q-axis current reference i of the feedback windingqs2 *。
According to an embodiment of the present invention, in the second step, if the current q-axis current reference value i is presentqs2 *Is taken as the d-axis current reference value i of the corresponding rotor windingqr *If the value of (1) does not meet the preset condition, taking 0 as the preset reactive power reference value
Required q-axis current reference i of feedback windingqs2 *Is calculated by taking the q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor winding when the value is 0qr *Is taken as the preset reactive power reference value
The required value.
According to an embodiment of the present invention, the preset conditions include:
wherein, ImaxIndicating that the rotor-side converter is allowed to output a maximum value of the steady-state current amplitude.
According to one embodiment of the invention, the d-axis current reference value i of the rotor winding is determined according to the following expressiondr *：
Wherein M is*Indicating an electromagnetic torque command, nsynIndicating synchronous speed of rotation, us1mRepresenting the peak phase voltage, K, of the main winding of the statorN1/NrThe turns ratio of the stator main winding phase to the rotor winding phase is shown.
According to an embodiment of the present invention, in the step one, the current q-axis current reference value i is expressed as followsqs2 *D-axis current reference value i of corresponding rotor windingqr *：
Wherein, Us1Representing stator main winding voltage, Zs1Representing the main excitation impedance, K, of the machineN1/NrThe turns ratio of the stator main winding phase to the rotor winding phase is shown.
According to an embodiment of the present invention, in the third step, the d-axis current reference value i of the rotor winding is calculated according to the following expressionqr *And (5) correcting:
wherein, i on the left side of the equationqr *I represents the corrected value of the d-axis current reference value of the rotor winding, right side of equationqr *Representing the value of the rotor winding before the d-axis current reference is corrected.
According to one embodiment of the invention, the q-axis current reference value i of the feedback winding is re-determined according to the following expressionqs2 *：
Wherein Q iss1 *Representing the grid-connected reactive power reference value, U, of the stator main windings1Representing stator main winding voltage, Zs1Representing the main excitation impedance, KN1/NrRepresenting the turns ratio of the main winding to the rotor winding, KN1/N2Representing the turns ratio of the main winding to the feedback winding.
The invention also provides a grid-connected power generation control method of the grid-connected power generation system of the internal feedback generator, and the control method adopts any one of the methods to determine the d-axis current reference value of the rotor winding and the q-axis current reference value of the feedback winding required in the reactive power control process.
According to an embodiment of the present invention, the control method further includes:
determining a first d-axis reference voltage u 'of the rotor winding according to the actual current of the rotor winding in the two-phase synchronous coordinate system and the reference current of the rotor winding in the two-phase synchronous coordinate system'drAnd a first q-axis reference voltage u'qr；
According to the first d-axis reference electric u'drVoltage and first q-axis reference voltage u'qrIntroducing a first feedforward control variable to obtain a second d-axis reference voltage u of the rotor windingdrAnd a second q-axis reference voltage uqr；
According to the second d-axis reference voltage udrAnd a second q-axis reference voltage uqrGenerating corresponding inverter controlA signal to control the operating state of the inverter.
According to one embodiment of the present invention, the second d-axis reference voltage u is determined according to the following expressiondrAnd a second q-axis reference voltage uqr：
Wherein u isdrAnd uqrRespectively representing a second d-axis reference voltage and a second q-axis reference voltage, u'drAnd u'qrRespectively representing a first d-axis reference voltage and a first q-axis reference voltage, ω, of the rotor windingslipRepresenting slip angular velocity, Ls1rIndicating the mutual inductance, L, of the main and rotor windingss1mAnd Ls1σIndicating the main and leakage inductances of the main winding, respectively, phis1Denotes the main winding flux linkage, LrλRepresenting the leakage inductance of the rotor, idrAnd iqrRepresenting the d-axis and q-axis actual currents of the rotor windings, respectively.
Compared with the existing power generation system, the power generation system provided by the invention has the advantages that the main stator winding is directly connected with the high-voltage power grid, so that a conventional boosting grid-connected transformer is omitted, and the feedback winding and the rotor winding of the generator adopt low-voltage working voltage, so that a low-voltage converter with mature technology and low cost can be conveniently adopted. The converter receives an electromagnetic torque instruction and a power instruction of the complete machine control device of the wind turbine generator, and controls the rotor current and the stator feedback winding current of the generator so as to realize the control of the electromagnetic torque of the generator and the power output of the power grid merged into the main winding of the stator.
Meanwhile, the grid-connected power generation control method of the internal feedback generator provided by the invention indirectly realizes the control of the active power and the reactive power output by the stator main winding by controlling the active current component and the reactive current component of the rotor winding of the generator in a two-phase rotating dq synchronous coordinate system. In a two-phase rotating dq synchronous coordinate system, the method realizes the stabilization of the DC side voltage of the converter by controlling an active current component entering a feedback winding, and a control reference instruction of the active current component is derived from the output of a DC side voltage control loop.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required in the description of the embodiments or the prior art:
FIG. 1 is a schematic structural diagram of a grid-connected variable-speed constant-frequency wind power generation system based on a double-feedback generator;
FIG. 2 is a schematic structural diagram of a grid-connected variable-speed constant-frequency wind power generation system in the prior art, wherein a stator winding of a doubly-fed generator is designed to be directly connected to a grid at a high voltage;
FIG. 3 is a schematic diagram of a main circuit of an exemplary internal feedback motor speed regulation application in accordance with one embodiment of the present invention;
FIG. 4 is a schematic block diagram of a power generation system according to an embodiment of the present invention;
FIG. 5 is a partial circuit schematic of a power generation system according to one embodiment of the invention;
FIG. 6 is a schematic illustration of the internal feedback generator winding position relationship in accordance with one embodiment of the present invention;
FIG. 7 is a schematic representation of a transformation of a three-phase stationary coordinate system to a two-phase synchronous coordinate system according to one embodiment of the present invention;
FIG. 8 is a schematic diagram of a current transformer on the feedback winding side according to one embodiment of the present invention;
FIG. 9 is a schematic flow chart of an implementation of a control method of an internal feedback generator grid-connected power generation system according to an embodiment of the invention;
FIG. 10 is a control logic diagram of a control method of an internal feedback generator grid-connected power generation system according to one embodiment of the invention;
FIG. 11 is a flow diagram illustrating an implementation of determining a first d-axis reference voltage according to one embodiment of the invention;
FIG. 12 is a schematic diagram of an implementation flow for controlling current in a feedback winding of an internal feedback generator, according to an embodiment of the invention;
FIG. 13 is a flow diagram illustrating an implementation of determining a third d-axis reference voltage according to one embodiment of the invention;
fig. 14 is a schematic flow diagram of an implementation of determining reactive current of rotor windings and reactive current of feedback windings according to an embodiment of the invention.
Detailed Description
The following detailed description of the embodiments of the present invention will be provided with reference to the drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. It should be noted that, as long as there is no conflict, the embodiments and the features of the embodiments of the present invention may be combined with each other, and the technical solutions formed are within the scope of the present invention.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details or with other methods described herein.
Additionally, the steps illustrated in the flow charts of the figures may be performed in a computer system such as a set of computer-executable instructions and, although a logical order is illustrated in the flow charts, in some cases, the steps illustrated or described may be performed in an order different than here.
In a high-power double-fed wind power generation system for grid-connected wind power generation at present, a double-fed generator and a converter are usually designed according to low voltage. The output rated voltage of a stator winding and a rotor winding of the doubly-fed generator is usually 690Vac at low voltage, the doubly-fed converter is connected between the rotor output side of the doubly-fed generator and a grid-connected transformer, and the rated working voltage of the doubly-fed converter is also 690Vac at low voltage. The low-voltage design scheme of the system reduces the insulation requirement of the system and facilitates the development and application of the wind power converter. However, a grid-connected transformer (with power capacity equivalent to that of a doubly-fed generator) for boosting grid connection is indispensable for the low-voltage design scheme of the system, and the ground occupation requirement of the power generation system on the ground of a wind field is increased because the grid-connected transformer is usually arranged on the ground near a tower of a wind turbine.
In order to reduce the cost and the line loss of the fan, the stator winding of the doubly-fed generator is designed into a high-voltage direct grid-connection mode by the fan complete machine manufacturer in China on the basis of the traditional low-voltage doubly-fed wind turbine generator scheme. As shown in fig. 2, in this solution, the stator winding of the doubly fed generator 201 is designed at high voltage, while the rotor is still designed at low voltage, so that although a step-up transformer with full power capacity between the stator and the grid can be omitted, a step-up transformer 203 with power capacity of about 30% of the generator capacity still needs to be arranged between the doubly fed converter 202 and the grid. In the doubly-fed generator 201 with the same capacity, the cost of the motor is slightly increased after the stator voltage is increased to a high voltage, so that the cost of the power generation system is slightly reduced, but the grid-connected transformer (namely the boosting transformer 203) is not completely omitted.
The internal feedback motor is a new type of wound asynchronous motor, which is a special wound motor designed for internal feedback cascade AC speed regulator. The stator of the internal feedback motor is provided with two sets of windings, wherein one set of windings is called a main winding and is connected with the voltage of a power grid; the other set of windings, called the feedback winding, is routed in-line with the main winding and electrically isolated from the main winding. The feedback winding is connected to the ac side of the active inverter and is capable of receiving slip power from the rotor windings.
Fig. 3 shows a main circuit of a speed regulation application of a typical internal feedback motor, which is developed on the basis of a traditional cascade speed regulation system. The converter loop 301 is mainly composed of a rotor-side diode rectifier 302, an IGBT chopper 303 and a feedback winding-side active inverter 304. The direct current electromotive force can be controlled by controlling the on-off of the IGBT in the IGBT chopper 303, so that the purpose of adjusting the rotating speed of the motor is achieved.
The existing internal feedback motor is mainly applied to a traditional cascade speed control system, and in the system, the internal feedback motor is used as a motor. However, for the wind power application scenario, the internal feedback motor is required to be used as a generator, and this makes the main circuit of the speed regulation application of the existing internal feedback motor as shown in fig. 3 no longer applicable.
In view of the above problems in the prior art, the present invention provides a new power generation system, which changes a practical doubly-fed generator in the existing power generation system into an internal feedback motor (since the motor in the power generation system mainly works in a power generation mode, the internal feedback motor may also be referred to as an internal feedback generator), and also improves the circuit structure and control manner of the original doubly-fed converter to completely remove a grid-connected transformer for boosting, thereby reducing the cost and loss of the power generation system, and also effectively saving the installation site cost of the transformer.
Fig. 4 shows a schematic structural diagram of the power generation system provided in the present embodiment.
As shown in fig. 4, the power generation system provided by the present embodiment preferably includes: an internal feedback motor 401 and a doubly fed converter 402. The rotor of the inner feedback motor 401 is mechanically connected with the gear box, and the gear box can transmit the kinetic energy of the fan to the inner feedback motor 401, so that the rotor of the inner feedback motor 401 is driven to rotate, and the inner feedback motor can be used as a generator to generate corresponding electric energy.
In this embodiment, the internal feedback motor 401 includes a rotor winding configured on the rotor and a main winding and a feedback winding configured on the stator, wherein the main winding is electrically connected to the grid. Because the feedback resistor is embedded in the stator of the internal feedback motor 401 and is not fixed relative to the main winding embedded in the stator, the internal feedback motor 401 has the characteristics of an asynchronous motor and a three-phase static transformer, so that the internal feedback motor (i.e., the internal feedback motor 401) can be simplified to be a combination of the asynchronous motor and the three-phase transformer, namely, the main winding of the stator and the feedback winding can be regarded as the three-phase static transformer, and the main winding of the stator and the rotor can be regarded as a common asynchronous motor.
Compared with the traditional cascade speed regulation system, the internal feedback motor 401 can be understood as transferring the external transformer winding to the stator side of the motor from the physical structure, and the inverter transformer in the common cascade speed regulation is omitted, so that the occupied area of the speed regulation device is reduced, and the speed regulation system is more compact and simpler.
As shown in fig. 4, in this embodiment, the main winding of internal feedback motor 401 is connected to grid 403, and the rotor winding is connected to Crowbar device 404. In order to reduce the current harmonics transmitted from the main winding to the grid, the converter used in the power generation system preferably uses a doubly-fed converter 402, which is connected between the rotor winding and the feedback winding 402 for controlling the active and reactive power output by the main winding.
Specifically, in the present embodiment, the doubly-fed converter 402 includes a first rectifying and inverting circuit 402a and a second rectifying and inverting circuit 402 b. The first rectifying and inverting circuit 402a and the second rectifying and inverting circuit 402b share a dc bus, that is, the dc ports of the first rectifying and inverting circuit 402a are respectively connected to the dc ports of the second rectifying and inverting circuit 402 b. The first rectifying inverter circuit 402a and the second rectifying inverter circuit 402b can operate in four quadrants, thereby realizing bidirectional energy flow.
The first rectification inverter circuit 402a is electrically connected to the rotor winding of the internal feedback motor 401, thereby forming a rotor-side rectification inverter circuit. The second rectification inverter circuit 402b is electrically connected to the feedback winding of the internal feedback motor 401, thereby forming a feedback winding side rectification inverter circuit.
In this embodiment, the first rectifying and inverting circuit 402a and the second rectifying and inverting circuit 402b are preferably implemented by using a three-phase PWM rectifying and inverting inverter capable of bidirectional power energy flow. The three-phase PWM rectifier inverter is a fully-controlled three-phase bridge rectifier inverter, and can be used as a rectifier to realize the rectification function of alternating current and can also be used as an inverter to realize the inversion function of direct current according to actual requirements.
It should be noted that, in different embodiments of the present invention, the switching devices used in the three-phase PWM rectifier inverter may be IGBTs, or other power electronic switching devices capable of realizing high-speed switching control, and the present invention is not limited thereto.
In the present embodiment, during the power generation of the power generation system, the first rectifying and inverting circuit 402a (i.e., the rotor-side rectifying and inverting circuit) preferably serves as an inverter to control the active power and the reactive power output from the stator main winding of the internal feedback motor 401, and the second rectifying and inverting circuit 402b (i.e., the feedback winding-side rectifying and inverting circuit) preferably serves as a rectifier to control the dc-side voltage of the inverter and stabilize the dc-side voltage.
It should be noted that, according to actual needs, the second rectifying and inverting circuit 402b may also separately control the extra reactive power output by the main winding of the stator, and the extra reactive power is superimposed with the reactive power controlled by the first rectifying and inverting circuit 402a to be the total electronic reactive power, and provide reactive support for the power grid 403.
The existing internal feedback type cascade control system aims at controlling the rotating speed of the motor, however, the power generation system provided by the embodiment aims at controlling the active power and the reactive power output by the stator winding, and for this reason, the embodiment also provides a new control method of the internal feedback type generator grid-connected power generation system, and the method is preferably implemented by a complete machine controller 405 of the power generation system.
Specifically, in this embodiment, the doubly-fed converter 402 is preferably connected to the overall controller 405, and is capable of receiving a torque command and/or a power command from the overall controller 405, so as to adjust the active power and the reactive power output by the stator winding of the internal feedback motor 401 according to the torque command and/or the power command. Furthermore, the doubly-fed converter 402 is preferably also capable of detecting the rotation speed of the internal feedback motor 401 and transmitting the rotation speed information to the overall controller 405, so that the overall controller 405 controls the rotation speed of the internal feedback motor 401 according to the rotation speed information.
Assuming that the stator and the rotor of the internal feedback generator are used as the reference positive directions of the physical quantities of the motor according to the motor convention, the voltage equation of the internal feedback generator in the a-b-c three-phase coordinate system (wherein the main winding of the stator is represented by s1, the feedback winding is represented by s2, and the rotor winding is represented by r) is as follows:
[u]＝[uas1ubs1ucs1uas2ubs2ucs2uarubrucr]T(2)
[ψ]＝[ψas1ψbs1ψcs1ψas2ψbs2ψcs2ψarψbrψcr]T(3)
[i]＝[ias1ibs1ics1ias2ibs2ics2iaribricr]T(4)
[r]＝diag[ras1rbs1rcs1ras2rbs2rcs2rarrbrrcr](5)
wherein u, psi and i respectively represent three-phase voltage, flux linkage and current column vectors of a stator winding, a feedback winding and a rotor winding of the internal feedback generator, and r represents a diagonal matrix of resistances of the stator winding, the feedback winding and the rotor winding of the internal feedback generator. u. ofas1、ubs1、ucs1Representing the voltages, u, of the three-phase axes of the stator main windings a, b, c, respectivelyas2、ubs2、ucs2Representing the voltages, u, of the three-phase axes of the feedback windings a, b, c, respectivelyar、ubrAnd ucrRepresenting the voltages of the three-phase axes of the rotor windings a, b, c, respectively.
The flux linkage equation is:
wherein L isi,iIndicating the self-inductance, L, of the respective windingi,j(i ≠ j) represents the amount of mutual inductance between the windings.
Based on the characteristics of the wound-rotor asynchronous motor, the self-inductance of the three-phase main winding of the stator, the feedback winding and the rotor winding exists:
wherein L iss1mAnd Ls2mMain inductances, L, representing stator main and feedback windings, respectivelyrmIndicating the main inductance of the rotor winding, Ls1σAnd Ls2σIndicating the leakage inductances, L, of the stator main and feedback windings, respectivelyrσRepresenting the leakage inductance of the rotor windings.
Mutual inductance of the stator three-phase main winding, the feedback three-phase winding and the rotor three-phase winding:
in consideration of the positional relationship between the windings, there are:
FIG. 6 shows winding for an internal feedback generatorSchematic diagram of group position relationship. A, B, C is the output end of the stator main winding, A ', B ' and C ' are the output ends of the feedback winding, and a, B and C are the output ends of the rotor winding. ThetakThe included angle of the spatial positions of the corresponding phase axes of the stator main winding and the feedback winding is considered as theta, because the corresponding phases of the stator main winding and the feedback winding are in the same stator slotk＝0。
Mutual inductance between corresponding phases of the stator main winding, the feedback winding and the rotor winding is as follows:
in order to realize the power control of the generator, a mathematical model of the internal feedback generator under a two-phase rotating coordinate system is derived as follows:
and positioning the d axis of the d-q-0 coordinate system on the voltage comprehensive vector of the main winding of the stator, wherein the q axis leads the d axis by 90 degrees. As shown in fig. 7, assuming that the included angle between the d-axis and the a-phase axis of the stator main winding is θ, and adopting coordinate transformation with equal amplitude, the physical quantity transformation matrix from the three-phase stationary coordinate system to the two-phase synchronous coordinate system is:
and the coordinate transformation matrix of the physical quantity from the two-phase synchronous coordinate system to the three-phase static coordinate system is TABC→dq -1(θ)。
After coordinate transformation, the flux linkage equation and the voltage equation of the internal feedback generator under a d-q-0 coordinate system are obtained as follows:
wherein u isds1And uqs1Representing d-axis and q-axis voltages, u, of the stator main winding, respectivelyds2And uqs2Representing the d-and q-axis voltages, u, of the feedback winding, respectivelydrAnd uqrRepresenting d-axis and q-axis voltages, r, of the rotor winding, respectivelys1、rs2And rrRepresenting the resistances of the stator main, feedback and rotor windings, respectively, ids1And iqs1Representing d-axis and q-axis currents, i, of the stator main winding, respectivelyds2And iqs2Representing d-and q-axis currents, i, of the feedback winding, respectivelydrAnd iqrRespectively representing d-axis and q-axis currents of the rotor winding, #ds1And psiqs1Respectively representing the d-axis flux linkage and the q-axis flux linkage of the stator main winding, psids1And psiqs1Respectively representing the d-axis flux linkage and the q-axis flux linkage of the stator main winding, psids2And psiqs2D-axis flux linkage and q-axis flux linkage, psi, respectively, representing the feedback windingdrAnd psiqrRespectively representing the d-axis flux linkage and the q-axis flux linkage, omega, of the rotor winding1Representing stator flux angular frequency, ωrRepresenting the rotor angular velocity.
And eliminating the flux linkage item to obtain a mathematical model of the internal feedback generator as follows:
when the three phases are symmetrical, the active power P input by the main winding of the stator can be considereds1And reactive power Qs1Comprises the following steps:
active power P input by feedback windings2And reactive power Qs2Comprises the following steps:
rotor winding input active power PrComprises the following steps:
since the leakage inductance of the stator winding is relatively small and can be ignored when calculating the steady-state power, substituting expression (18) into expressions (19) and (20) and omitting the differential term, the steady-state power of the stator winding can be obtained as follows:
from (22) can be obtained:
similarly, substituting the expression (18) into the expression (21), omitting the differential term, and defining the stable power P of the rotor winding by using the slip ratiorComprises the following steps:
according to the expressions (23) and (24), the following quantity relation exists between the power of the rotor winding and the active power of the stator main winding and the feedback winding:
Pr＝-s(Ps1+Ps2) (26)
as shown in fig. 4, if the heat loss of the dual PWM converter is neglected, it can be considered that:
Pr＝-Ps2(27)
the combined formulae (26) and (27) are obtained,
orienting the d-axis according to the stator main winding voltage synthetic vector, then there are:
because the resistance of the main winding is relatively small and the influence of the resistance is negligible, the stator main winding voltage synthetic vector can be considered as a constant, and the magnitude of the stator main winding flux linkage Ψ s1 is kept unchanged, which can be obtained according to the expression (16):
wherein u iss1mExpressing the peak value of the phase voltage of the main winding of the stator.
Substituting expression (30) into expression (20) may result in:
substituting expression (29) into expression (18) may result in:
substituting expression (33) into expression (32) may result in:
and for the active power of the stator main winding, the active power can be decomposed into two parts:
wherein, Ps1_drAnd Ps1_ds2Representing the stator main winding power as affected by the rotor and feedback winding electrical quantities, respectively.
For the reactive power of the stator main winding, the reactive power can be decomposed into three parts:
wherein Q iss1_ψs1、Qs1_qrAnd Qs1_qs2Representing the reactive power of the main stator winding, u, influenced by the electric quantities of the main stator winding, the rotor winding and the feedback winding, respectivelys1mRepresenting the peak phase voltage of the stator main winding.
From expressions (34) to (36), it can be seen that the active power sent from the stator main winding to the grid is composed of two parts, one part (i.e., P)s1_dr) With active component i of the rotor windingdrProportional, another part (i.e. P)s1_ds2) With the current active component i of the feedback windingds2Is in direct proportion. The reactive power exchanged between the main stator winding and the grid is composed of three parts, one part (Q)s1_ψs1) Is the excitation reactive power of the motor, the size of which depends on the amplitude of the network voltage, and a part (namely Q)s1_qr) Reactive current i to rotor windingqrProportional, one part (i.e. Q)s1_qs2) Current reactive component i with feedback windingds2Is in direct proportion.
When the expression (35) is analyzed, the leakage inductance of the stator winding is far smaller than the self-inductance, and the influence is neglected, the following results are obtained:
wherein, Ps1_drRepresenting the power of the main winding of the stator, P, as influenced by the rotor electrical quantitys1_ds2Representing the power of the main winding of the stator, u, as influenced by the electric quantity of the feedback windings1mAnd us2mRespectively representing the phase voltage peak values of the main winding and the feedback winding of the stator.
Because the feedback winding and the main winding are designed in the same slot, similar to expression (32), the active power P of the feedback winding can be obtaineds2And reactive power Qs2Respectively as follows:
in addition, when system loss is neglected, the active power relationship between the feedback winding and the rotor winding can be considered as follows:
Ps2＝-Pr(39)
according to the formulae (28), (34), (37), (38) and (39):
assume, according to the positive reference in FIG. 5, that when P iss1When the power is more than 0, the generator absorbs active power from the power grid, and the generator works in a motor mode; when P is presents1When the power is less than 0, the generator outputs active power to the power grid, and the generator works in a power generation mode.
The motor losses are neglected. The active power of the stator can be considered equal to the electromagnetic torque power, i.e. there is:
wherein n issynIndicating synchronous speed (rpm) and M indicating electromagnetic torque.
The positive and negative of the torque are determined by taking the rotation direction as a reference, the rotation direction of a rotor during normal operation power generation is taken as a speed reference positive direction, the electromagnetic torque M is greater than 0 when the direction of the electromagnetic torque is the same as the speed reference positive direction, the electromagnetic torque is driving torque, and the generator works in an electric mode. According to the positive current-voltage reference direction, P of FIG. 5s1Above zero, the generator absorbs active power from the grid.
When the direction of the electromagnetic torque is opposite to the positive speed reference direction, the electromagnetic torque M is less than 0, which is a braking torque, the generator works in a power generation mode, Ps1And when the current is smaller than zero, the generator sends active power to the power grid. During normal grid-connected power generation, M takes a negative value, and omegarTaking the straight.
The rotor side active current component i in the steady state can be obtained by using the expression (40) and the expression (41)dr *And electromagnetic torque command M*The relation of (A) is as follows:
defining the turn ratio of a main winding phase of the stator to a rotor winding phase as KN1/NrDefining the turn ratio of a main winding phase and a feedback winding phase of the stator as KN1/N2Then, there are:
the voltage of the power grid applied to the stator main winding is Us1, and formula (43) is brought into formula (41) and utilized
Can be converted into:
it should be noted that if the main stator winding is delta-connected and the rotor and feedback windings are star-connected, the network is rated with UnApplied to the external terminal of the stator main winding, and when the rotor is still, the voltage measured by the rotor winding output terminal is set as UkrThe voltage measured at the output terminal of the feedback winding is Uks2Then, we can get:
the turn ratio of the main winding phase and the feedback winding phase of the stator is KN1/N2The method comprises the following steps:
since the leakage inductance is small relative to the self-inductance, in case of neglecting the winding leakage inductance,the reactive instruction (namely grid-connected reactive power reference value) Q of the main winding of the stator can be obtained by the formula (34)s1 *And a rotor winding reactive current command (i.e. a q-axis current reference value of the rotor winding) iqr *And a feedback winding reactive current command (i.e. a q-axis current reference value of the feedback winding) iqs2 *The magnitude relation of (A) is as follows:
wherein, Us1Representing the stator main winding voltage. Zs1Represents the main excitation impedance of the motor, which can be determined according to the following expression:
Zs1＝ω1Ls1m(49)
assume, according to the positive reference direction of FIG. 5, that when Q iss1When the voltage is more than 0, the generator absorbs reactive power from the power grid, the main winding of the stator is inductive to the outside, and when Q is greater than 0s1When the output voltage is less than 0, the generator outputs reactive power to the power grid, and the main winding of the stator is outward capacitive.
Substituting expression (33) into expression (18), the rotor voltage equation can be simplified as:
slip angular velocity ωslipIt can be calculated according to the following expression:
ωslip＝ω1-ωr(51)
and leakage inductance L for rotor windingrλThere is:
wherein L iss1mAnd Ls1σRepresenting the main and leakage inductances of the main winding, respectively.
Thus expression (50) can be rewritten as:
wherein r isrRepresenting rotor resistance, ωslipRepresenting slip angular velocity, LrλRepresenting the rotor leakage inductance.
According to the expression (52), a feedforward control quantity is introduced
And ωslipLrλidrThe decoupling control of the rotor voltage to the rotor current can be realized.
Order to
Then there is:
expression (54) is a first-order inertia element, and when current control is carried out, the reference current i is instructed through a d axisdr *And a feedback value idrThe d-axis reference voltage u 'of the rotor winding can be obtained through PI regulation'dr(i.e., first d-axis reference voltage), the reference current i is commanded via the q-axisqr *And a feedback value iqrPerforming PI regulation to obtain q-axis reference voltage u 'of the rotor winding'qr(i.e., the first q-axis reference voltage).
And for the feedback winding of the motor, the schematic of the current transformer on the feedback winding side can be as shown in fig. 8. As can be seen from fig. 8, the current transformer on the feedback winding side is a four-quadrant current transformer, and with reference to the positive direction according to the illustrated electrical physical quantity, the voltage equation can be listed as follows:
wherein v isA、vBAnd vCRespectively representing a phase equivalent voltage and b phase of inverter inversion outputThe equivalent voltage and the c are equivalent voltage, R represents the equivalent resistance of an output line of the inverter, and L represents the inductance of an output reactor of the inverter. u. ofas2、ubs2And ucs2I represents the a-phase voltage, b-phase voltage and c-phase voltage of the feedback winding, respectivelyas2、ibs2And ics2Phase a, phase b and phase c of the feedback winding are shown, respectively.
In a two-phase dq synchronous coordinate system with the feedback winding voltage synthetic vector as the d-axis and the q-axis leading the d-axis by 90 degrees, the above equation can be converted into:
wherein, ω iseRepresenting the grid voltage frequency.
From expression (57), one can obtain:
to implement the current decoupling control, one may order:
wherein, v'ds2And v'qs2Representing the d-axis voltage and the q-axis voltage of the feedback winding, respectively.
Then there is:
therefore, a compensation term is introduced, and the current control algorithm obtained after the feedforward control is adopted is as follows:
wherein v isd *And vq *Respectively representing converter control reference voltages (i.e. converter control d-axis reference voltages)And converter control q-axis reference voltage), KpPAnd KiPRespectively representing the proportionality coefficient and the integral coefficient, K, of a d-axis current-controlled PI regulatorpQAnd KiQRespectively representing the proportionality coefficient and the integral coefficient of the q-axis current control PI regulator.
The internal feedback generator grid-connected power generation system provided in this embodiment adjusts the internal feedback power generation system based on the analysis, where fig. 9 shows an implementation flow diagram of a control method of the internal feedback generator grid-connected power generation system provided in this embodiment.
As shown in fig. 9, in this embodiment, when the active current and the reactive current of the rotor winding of the internal feedback generator grid-connected power generation system are controlled, in step S901, the actual current i of the rotor winding of the internal feedback motor in the three-phase stationary coordinate system is first obtained in step S901ar、ibrAnd icr. Obtaining the actual current i of the rotor winding in a three-phase static coordinate systemar、ibrAnd icrThen, the method will determine the actual current i of the rotor winding in the three-phase stationary coordinate system in step S902ar、ibrAnd icrCorrespondingly obtaining the actual current of the rotor winding under the two-phase synchronous coordinate system, namely the d-axis actual current i of the rotor windingdrAnd q-axis actual current iqr。
As shown in fig. 9, in the present embodiment, the method preferably bases the principle shown in expression (15) on the actual current i of the rotor winding in the three-phase stationary coordinate system in step S902ar、ibrAnd icrConstant amplitude coordinate transformation is carried out to determine d-axis actual current i of rotor windingdrAnd q-axis actual current iqr。
In the embodiment, the method is used for measuring the actual current i of the rotor winding in a three-phase static coordinate systemar、ibrAnd icrDuring the process of carrying out the coordinate transformation with equal amplitude, the magnetic flux angle theta is preferably acquiredsAnd rotor phase θrThen based on the flux angle thetasAnd rotor phase θrDifference of (a) thetas-θrAccording to the rotorActual current i of winding in three-phase static coordinate systemar、ibrAnd icrCorrespondingly obtaining d-axis actual current i of the rotor windingdrAnd q-axis actual current iqr。
In particular, in the present embodiment, the method is preferably based on the actual current (including i) of the stator main winding of the internal feedback generatoras1、ibs1And ics1) And the actual voltage (including u)as1、ubs1And ucs1) To determine the magnetic flux angle thetas. At the same time, the method preferably utilizes a position sensor to determine the rotor phase θr。
Of course, in other embodiments of the invention, the method may also use other reasonable ways to determine the magnetic flux angle θ according to practical needssAnd/or rotor phase θrThe present invention is not limited thereto.
In this case, as shown in fig. 9, the d-axis actual current i of the rotor winding is obtaineddrAnd q-axis actual current iqrThen, the method will determine the d-axis actual current i of the rotor winding in step S903drAnd q-axis actual current iqrAnd the reference current of the rotor winding under the two-phase synchronous coordinate system (including the d-axis reference current i of the rotor winding)dr *And q-axis reference current iqr *) To obtain a first d-axis reference voltage u'drAnd a first q-axis reference voltage u'qr。
Specifically, referring to FIG. 10 and FIG. 11, in the present embodiment, the method is determining a first d-axis reference voltage u'drFirst, in step S1101, a d-axis reference current i of the rotor winding is calculateddr *And d-axis actual current idrTo obtain a first current difference idr *-idrThen, in step S1102, the PI control is used to control the current according to the first current difference idr *-idrObtaining a first d-axis reference voltage u 'of the rotor winding'dr。
Similarly, the method provides a first q-axis reference voltage u'qrFirst, the q-axis reference current of the rotor winding is calculatediqr *And q-axis actual current iqrTo obtain a second current difference iqr *-iqrThen, the PI regulation mode is used again to regulate the current according to the second current difference iqr *-iqrObtaining a first q-axis reference voltage u 'of the rotor winding'qr。
In the present embodiment, the method preferably determines the first d-axis reference voltage u 'based on the principle shown in expression (54)'drAnd a first q-axis reference voltage u'qr. Of course, in other embodiments of the present invention, the method may also determine the first d-axis reference voltage u 'in other reasonable manners'drAnd a first q-axis reference voltage u'qrThe present invention is not limited thereto.
Referring again to FIG. 9, in this example, a first d-axis reference voltage u 'is obtained'drAnd a first q-axis reference voltage u'qrNext, the method proceeds to step S904 to derive a first d-axis reference voltage u'drAnd a first q-axis reference voltage u'qrCorrespondingly obtaining a second d-axis reference voltage u of the rotor winding by introducing a first feedforward control variabledrAnd a second q-axis reference voltage uqr。
In particular, in the present embodiment, the method preferably bases on expression (55) to derive first d-axis reference voltage u'drAnd a first q-axis reference voltage u'qrDetermining a second d-axis reference voltage u of the rotor windingdrAnd a second q-axis reference voltage uqr. Wherein a second d-axis reference voltage u of the rotor winding is determineddrAnd a second q-axis reference voltage uqrThe first feedforward control variable introduced in time comprises
And ωslipLrλidr。
In the present embodiment, as shown in fig. 9, the method preferably determines the slip angular velocity ω according to the following expressionslip：
Wherein, ω is1Representing angular velocity, ω, of stator flux linkagerRepresenting the rotor rotational angular velocity.
Because the resistance of the main winding of the internal feedback generator is relatively small, neglecting the influence, the comprehensive vector of the voltage of the main winding can be regarded as a constant, and the magnetic linkage psi of the main winding existss1Is a constant whose magnitude remains constant. Specifically, in the present embodiment, the method preferably determines the main winding flux linkage ψ based on expression (31)s1。
Of course, in other embodiments of the invention, the method may also use other reasonable ways to determine the main winding flux linkage ψs1The present invention is not limited thereto.
As shown in FIG. 9, a second d-axis reference voltage u of the rotor winding is obtaineddrAnd a second q-axis reference voltage uqrThen, the method proceeds to step S905 to determine the second d-axis reference voltage u of the rotor windingdrAnd a second q-axis reference voltage uqrAnd generating a corresponding inverter control signal, and sending the inverter control signal to a rotor-side inverter of the internal feedback generator to control an active current component and a reactive current component of a rotor winding of the internal feedback generator, thereby indirectly realizing the control of the output active power and the output reactive power of a stator main winding of the internal feedback generator.
Specifically, in this embodiment, in step S905, the method will use the second d-axis reference voltage u of the rotor winding under the two-phase synchronous coordinate systemdrAnd a second q-axis reference voltage uqrAnd converting the voltage into a corresponding voltage under a three-phase static coordinate system, and generating a corresponding PWM control signal according to the corresponding voltage under the three-phase static coordinate system, so as to control a rotor side inverter of the internal feedback generator through the PWM control signal.
According to the expression (44), the electromagnetic torque of the internal feedback generator is only commanded by the active current of the rotor-side converter (i.e. the d-axis reference current i of the rotor winding)dr *) This means that the power generated by the main stator winding at a certain speed is determined byThe active current command idr *The method can thus be implemented by adjusting the active current command idr *The grid-connected power of the generator is accurately controlled.
The method provided by the present embodiment can also realize the control of the current of the feedback winding of the internal feedback generator, wherein fig. 12 shows a schematic implementation flow diagram of the control of the current of the feedback winding of the internal feedback generator in the present embodiment.
As shown in fig. 12, when controlling the current of the feedback winding of the internal feedback generator, the method first obtains the actual current (including i) of the feedback winding of the internal feedback generator in the three-phase stationary coordinate system in step S1201as2、ibs2And ics2) And the actual voltage (including u)as2、ubs2And ucs2)。
Then, the method will obtain the actual current of the feedback winding in the two-phase synchronous coordinate system (including the d-axis actual current i of the feedback winding) according to the actual current and the actual voltage of the feedback winding in the three-phase stationary coordinate system in step S1202ds2And q-axis actual current iqs2) And the actual voltage (d-axis actual voltage u including the feedback winding)ds2And q-axis actual voltage uqs2)。
Specifically, in the present embodiment, the method obtains the actual current and the actual voltage of the feedback winding in the two-phase synchronous coordinate system preferably by the constant-amplitude coordinate transformation based on the principle shown in expression (15) in step S1202.
The method is used for carrying out equal-amplitude coordinate transformation on actual current and actual voltage of a feedback winding in a three-phase static coordinate systeme(i.e. the voltage phase of the feedback winding) is preferably determined by phase locking the grid voltage.
In step S1203, the method determines a third d-axis reference voltage v according to the actual current and the reference current of the feedback winding in the two-phase synchronous coordinate systemds2And a third q-axis reference voltage vqs2. Wherein FIG. 13 illustrates the determination of the third d-axis reference voltage v in this embodimentds2The implementation flow of (1) is schematic.
With reference to fig. 13 and 10, in the present embodiment, the method determines the third d-axis reference voltage vds2In step S1301, the actual voltage u on the dc side of the converter is obtaineddcAnd calculating the actual voltage udcAnd a predetermined reference DC voltage
To obtain a first voltage difference value
Obtaining a first voltage difference value
Then, the method proceeds to step S1302 according to the first voltage difference
To determine the d-axis current reference value of the feedback winding by means of PI control
Subsequently, the method calculates a d-axis current reference value of the feedback winding in step S1303
D-axis actual current (i.e. d-axis current actual value) i with feedback windingds2To obtain a third current difference value
To obtain a third current difference
Thereafter, the method proceeds to step 1304 according to the third current difference
To determine the third d-axis reference voltage v by means of PI controlds2。
Of course, in other embodiments of the present invention, the method may also use other reasonable ways to determine the second d-axis reference voltage vd1The present invention is not limited thereto.
In this embodiment, the method obtains the q-axis current reference value of the feedback winding
And calculating the q-axis current reference value of the feedback winding
Q-axis actual current (i.e. q-axis current actual value) i with feedback windingqs2To obtain a fourth current difference value
The method then proceeds with the fourth current difference being based on
To determine the third q-axis reference voltage v by means of PI controlqs2。
According to the expression (48), the grid-connected reactive power Q of the stator main windings1Mainly commanded by the reactive current of the rotor winding (i.e. the d-axis current reference of the rotor winding) iqr *And reactive current command (i.e. q-axis current reference of feedback winding) i of feedback windingqs2 *The method can thus be implemented by controlling the reactive current command i of the rotor windingqr *And reactive current command i of feedback windingqs2 *The output of grid-connected and grid-connected reactive power is accurately controlled.
D-axis current reference i of rotor winding for a certain required reactive output valueqr *And a q-axis current reference i of the feedback windingqs2 *Respectively, the method provided by the present embodiment refers to the rotor-side converter andand comprehensively determining the capacity of the feedback side converter, the heat loss optimization of the switching devices and other conditions.
Fig. 14 is a flowchart illustrating an implementation of the reactive power control method of the grid-connected internal feedback generator system according to the present embodiment, which is capable of determining a preset reactive power reference value
Q-axis current reference i of lower feedback windingqs2 *Reference value i of d-axis current of rotor windingqr *The specific value of (1).
As shown in fig. 14, in this embodiment, the method first sends a feedback winding reactive current command (i.e. a q-axis current reference value of the feedback winding) i in step S1401qs2 *Is configured to be 0, and then according to a preset reactive power reference value Qs * 1Determining the current reactive current command (i.e. the q-axis current reference value of the feedback winding) i of the feedback windingqs2 *Reactive current command i of the corresponding rotor windingqr *The value of (a).
In particular, in the present embodiment, the method preferably determines the reactive current command i of the rotor winding according to the following expressionqr *The value of (A) is as follows:
obtaining a q-axis current reference value i of a feedback windingqs2 *The reactive current instruction i of the rotor winding corresponding to the current valueqr *Then, the method judges the current q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor windingqr *Whether the value of (a) satisfies a preset condition.
Specifically, in the present embodiment, as shown in fig. 14, the method determines in step S1402 whether the following conditions are satisfied:
wherein, ImaxIndicating that the rotor converter allows the maximum value of the steady-state current amplitude to be output.
In this embodiment, the d-axis current reference value i of the rotor windingdr *The value of (b) can be determined according to the expression (44), and is not described herein again.
If the front q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor windingqr *Satisfies the preset condition (i.e. the expression (64) is satisfied), in this embodiment, the method will output the maximum value I of the steady-state current amplitude according to the permission of the rotor converter in step S1403maxAnd reactive current command i of rotor windingqr *Corrects the rotor reactive current command according to the current value of the rotor reactive current command, and re-determines the feedback winding reactive current command (i.e. the q-axis current reference value of the feedback winding) i according to the corrected value of the rotor reactive current command in step S1404qs2 *。
Specifically, in the present embodiment, the method preferably performs the following expression on the rotor reactive current command i in step S1403qr *And (5) correcting:
wherein the rotor reactive current command i to the left of the equationqr *Represents the modified rotor reactive current command (i.e., the modified value of the d-axis current reference value of the rotor winding), and the rotor reactive current command i to the right of the equationqr *Indicating the rotor reactive current command before correction (i.e., the value of the d-axis current reference value of the rotor winding before correction).
After obtaining the corrected reactive current command iqr *Thereafter, the method preferably determines the feedback winding reactive current command (i.e., the q-axis current reference value of the feedback winding) i at that time according to the following expressionqs2 *The value of (A) is as follows:
it is noted that in other embodiments of the present invention, the method may also determine the reactive current command i of the rotor winding according to other reasonable manners according to actual needsqr *And reactive current command i of feedback windingqs2 *The present invention is not limited thereto.
In this embodiment, if the q-axis current reference value iqs2 *Is the d-axis current reference value i of the corresponding rotor windingqr *The value of (a) does not satisfy the preset condition, and the method takes 0 as a preset reactive power reference value
Required q-axis current reference i of feedback windingqs2 *And the q-axis current reference value i is obtainedqs2 *D-axis current reference value i of corresponding rotor winding when the value is 0qr *Is taken as a preset reactive power reference value
The required value.
As shown again in FIG. 12, in the present embodiment, the third d-axis reference voltage v is determinedds2And a third q-axis reference voltage vqs2Thereafter, in this embodiment, the method will follow the third d-axis reference voltage v in step S1204ds2And a third q-axis reference voltage vqs2Determining the converter control d-axis reference voltage v in combination with the actual voltage of the feedback windingd *And converter control q-axis reference voltage vq *。
Specifically, in the present embodiment, the method preferably bases the expression (60) on the basis of the third d-axis reference voltage v in step S1204ds2And a third q-axis reference voltage vqs2Determining converter control d-axis reference voltage vd *And converter control q-axis referenceVoltage vq *. Wherein the third d-axis reference voltage vds2And a third q-axis reference voltage vqs2Can be expressed by the following expression:
obtaining a reference voltage v of a d-axis controlled by the converterd *And converter control q-axis reference voltage vq *Then, the method can control the d-axis reference voltage according to the converter in step S1205
And the converter controls the q-axis reference voltage
And generating corresponding rectifier control signals to realize the stabilization of the DC side voltage of the converter by controlling a feedback side rectifier of the internal feedback generator.
Compared with the existing power generation system, the power generation system provided by the invention has the advantages that the main stator winding is directly connected with the high-voltage power grid, so that a conventional boosting grid-connected transformer is omitted, and the feedback winding and the rotor winding of the generator adopt low-voltage working voltage, so that a low-voltage converter with mature technology and low cost can be conveniently adopted. The converter receives an electromagnetic torque instruction and a power instruction of the complete machine control device of the wind turbine generator, and controls the rotor current and the stator feedback winding current of the generator so as to realize the control of the electromagnetic torque of the generator and the power output of the power grid merged into the main winding of the stator.
Meanwhile, the grid-connected power generation control method of the internal feedback generator provided by the invention indirectly realizes the control of the active power and the reactive power output by the stator main winding by controlling the active current component and the reactive current component of the rotor winding of the generator in a two-phase rotating dq synchronous coordinate system. In a two-phase rotating dq synchronous coordinate system, the method realizes the stabilization of the DC side voltage of the converter by controlling an active current component entering a feedback winding, and a control reference instruction of the active current component is derived from the output of a DC side voltage control loop.
It is to be understood that the disclosed embodiments of the invention are not limited to the particular structures or process steps disclosed herein, but extend to equivalents thereof as would be understood by those skilled in the relevant art. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.
Reference in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase "one embodiment" or "an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.
While the above examples are illustrative of the principles of the present invention in one or more applications, it will be apparent to those of ordinary skill in the art that various changes in form, usage and details of implementation can be made without departing from the principles and concepts of the invention. Accordingly, the invention is defined by the appended claims.
Claims (10)
1. A reactive power control method of an internal feedback generator grid-connected power generation system is characterized by comprising the following steps:
step one, a q-axis current reference value i of a feedback winding of an internal feedback generator is usedqs2 *Is configured to be 0 according to a preset reactive power reference value
Determining a current q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor windingqr *；
Step two, judging the current q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor windingqr *Whether the value of (a) satisfies a preset condition, wherein if so, the step is executedStep three;
step three, according to the d-axis current reference value i of the rotor windingdr *And the maximum value I of the amplitude of the steady-state current allowed to be output by the rotor-side convertermaxReference value i of d-axis current for rotor windingqr *Correcting according to the corrected d-axis current reference value i of the rotor windingqr *Re-determining the q-axis current reference i of the feedback windingqs2 *。
2. The method of claim 1, wherein in the second step, if the current q-axis current reference value i is presentqs2 *Is taken as the d-axis current reference value i of the corresponding rotor windingqr *If the value does not satisfy the preset condition and does not satisfy the preset condition, taking 0 as the preset reactive power reference value Qs * 1Required q-axis current reference i of feedback windingqs2 *Is calculated by taking the q-axis current reference value iqs2 *D-axis current reference value i of corresponding rotor winding when the value is 0qr *Is taken as the preset reactive power reference value
The required value.
3. The method of claim 1 or 2, wherein the preset conditions include:
wherein, ImaxIndicating that the rotor-side converter is allowed to output a maximum value of the steady-state current amplitude.
4. A method according to claim 3, wherein the d-axis current reference value i for the rotor winding is determined according to the expressiondr *：
Wherein M is*Indicating an electromagnetic torque command, nsynIndicating synchronous speed of rotation, us1mRepresenting the peak phase voltage, K, of the main winding of the statorN1/NrThe turns ratio of the stator main winding phase to the rotor winding phase is shown.
5. The method according to any one of claims 1 to 4, wherein in step one, the current q-axis current reference value i is expressed according to the following expressionqs2 *D-axis current reference value i of corresponding rotor windingqr *：
Wherein, Us1Representing stator main winding voltage, Zs1Representing the main excitation impedance, K, of the machineN1/NrThe turns ratio of the stator main winding phase to the rotor winding phase is shown.
6. The method according to any one of claims 1 to 5, wherein in step three, the d-axis current reference value i of the rotor winding is calculated according to the following expressionqr *And (5) correcting:
wherein, i on the left side of the equationqr *I represents the corrected value of the d-axis current reference value of the rotor winding, right side of equationqr *Representing the value of the rotor winding before the d-axis current reference is corrected.
7. The method of claim 6, wherein in step three, the q-axis current reference value i of the feedback winding is re-determined according to the following expressionqs2 *：
Wherein Q iss1 *Representing the grid-connected reactive power reference value, U, of the stator main windings1Representing stator main winding voltage, Zs1Representing the main excitation impedance, KN1/NrRepresenting the turns ratio of the main winding to the rotor winding, KN1/N2Representing the turns ratio of the main winding to the feedback winding.
8. A grid-connected power generation control method of an internal feedback generator grid-connected power generation system is characterized in that the control method adopts the method of any one of claims 1-7 to determine a d-axis current reference value of a rotor winding and a q-axis current reference value of a feedback winding required in a reactive power control process.
9. The control method according to claim 8, characterized by further comprising:
determining a first d-axis reference voltage u 'of the rotor winding according to the actual current of the rotor winding in the two-phase synchronous coordinate system and the reference current of the rotor winding in the two-phase synchronous coordinate system'drAnd a first q-axis reference voltage u'qr；
According to the first d-axis reference electric u'drVoltage and first q-axis reference voltage u'qrIntroducing a first feedforward control variable to obtain a second d-axis reference voltage u of the rotor windingdrAnd a second q-axis reference voltage uqr；
According to the second d-axis reference voltage udrAnd a second q-axis reference voltage uqrAnd generating corresponding inverter control signals to control the operation state of the inverter.
10. The control method of claim 9, wherein the second d-axis reference voltage u is determined according to the following expressiondrAnd a second q-axis reference voltage uqr：
Wherein u isdrAnd uqrRespectively representing a second d-axis reference voltage and a second q-axis reference voltage, u'drAnd u'qrRespectively representing a first d-axis reference voltage and a first q-axis reference voltage, ω, of the rotor windingslipRepresenting slip angular velocity, Ls1rIndicating the mutual inductance, L, of the main and rotor windingss1mAnd Ls1σIndicating the main and leakage inductances of the main winding, respectively, phis1Denotes the main winding flux linkage, LrλRepresenting the leakage inductance of the rotor, idrAnd iqrRepresenting the d-axis and q-axis actual currents of the rotor windings, respectively.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811148096.0A CN110970904B (en) | 2018-09-29 | 2018-09-29 | Reactive power control method of internal feedback generator grid-connected power generation system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811148096.0A CN110970904B (en) | 2018-09-29 | 2018-09-29 | Reactive power control method of internal feedback generator grid-connected power generation system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110970904A true CN110970904A (en) | 2020-04-07 |
| CN110970904B CN110970904B (en) | 2021-09-24 |
Family
ID=70027258
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811148096.0A Active CN110970904B (en) | 2018-09-29 | 2018-09-29 | Reactive power control method of internal feedback generator grid-connected power generation system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110970904B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111865165A (en) * | 2020-08-03 | 2020-10-30 | 上海电气风电集团股份有限公司 | Control method, system, medium and electronic device of squirrel-cage asynchronous generator |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014106810A1 (en) * | 2013-01-07 | 2014-07-10 | Aeg Power Solutions Bv | Methods for controlling electrical inverters and electrical inverters and systems using the same |
| CN105048510A (en) * | 2015-09-15 | 2015-11-11 | 湖南大学 | Direct-driven permanent-magnetic wind power generation system active power dynamic control method under voltage drop condition |
| CN106329571A (en) * | 2016-09-14 | 2017-01-11 | 国网河南省电力公司平顶山供电公司 | Operation control method of DFIG grid side and rotor side PWM converter |
| CN107863780A (en) * | 2017-11-10 | 2018-03-30 | 国网浙江省电力公司经济技术研究院 | Offshore wind farm direct current transmitting system fault control method and device |
-
2018
- 2018-09-29 CN CN201811148096.0A patent/CN110970904B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014106810A1 (en) * | 2013-01-07 | 2014-07-10 | Aeg Power Solutions Bv | Methods for controlling electrical inverters and electrical inverters and systems using the same |
| CN105048510A (en) * | 2015-09-15 | 2015-11-11 | 湖南大学 | Direct-driven permanent-magnetic wind power generation system active power dynamic control method under voltage drop condition |
| CN106329571A (en) * | 2016-09-14 | 2017-01-11 | 国网河南省电力公司平顶山供电公司 | Operation control method of DFIG grid side and rotor side PWM converter |
| CN107863780A (en) * | 2017-11-10 | 2018-03-30 | 国网浙江省电力公司经济技术研究院 | Offshore wind farm direct current transmitting system fault control method and device |
Non-Patent Citations (1)
| Title |
|---|
| 辛征等: ""新型高压内双馈风力发电机及其电磁特性研究"", 《中国电机工程学报》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111865165A (en) * | 2020-08-03 | 2020-10-30 | 上海电气风电集团股份有限公司 | Control method, system, medium and electronic device of squirrel-cage asynchronous generator |
| CN111865165B (en) * | 2020-08-03 | 2021-07-30 | 上海电气风电集团股份有限公司 | Control method, system, medium and electronic device of squirrel-cage asynchronous generator |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110970904B (en) | 2021-09-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Hopfensperger et al. | Stator-flux-oriented control of a doubly-fed induction machine: with and without position encoder | |
| US8253393B2 (en) | Method and a controlling arrangement for controlling an AC generator | |
| CN108429284B (en) | Harmonic voltage proportion feedforward compensation method based on voltage source output double-fed wind turbine generator | |
| CN106505921B (en) | A kind of control method and system of electric machine speed regulation | |
| CN103227603B (en) | Vector compensation control method of winding open permanent magnet generator system | |
| CN104022702B (en) | AC permanent magnet synchronous motor control system | |
| Meng et al. | A sub-synchronous oscillation suppression strategy for doubly fed wind power generation system | |
| CN109412478B (en) | Power droop control method of brushless doubly-fed motor | |
| CN108879893A (en) | A kind of electric car virtual synchronous motor fast charge method based on quasi- PR control | |
| CN105099320B (en) | Method and device for controlling output active power of permanent magnet direct-drive wind driven generator | |
| CN110970904B (en) | Reactive power control method of internal feedback generator grid-connected power generation system | |
| CN110970916B (en) | Control method of grid-connected power generation system of internal feedback generator | |
| CN106452235B (en) | Brushless dual-feed motor stand alone generating system excitation control method under asymmetric load | |
| CN110970917B (en) | Power generation system | |
| CN114744655B (en) | Control method and topology device of flywheel energy storage system | |
| CN113141139B (en) | Five-closed-loop control method and system for double three-phase permanent magnet motor | |
| CN103904970A (en) | Method for controlling PWM converter on electric generator side of nine-phase permanent magnetic wind power generating system | |
| Hao et al. | A novel sensorless control strategy of doubly fed induction generator based on stator voltage | |
| CN105515040A (en) | Slip form and repeation-based DFIG control method | |
| CN115441801B (en) | Synchronous camera starting method based on rotor flux linkage orientation | |
| CN112542973B (en) | Control method of brushless double-fed induction motor under unbalanced power grid | |
| CN111668859B (en) | Virtual synchronous generator control method and system with unbalanced load | |
| CN109768750A (en) | Winding permanent magnet motor zero-sequence current suppressing method is opened based on the virtual three-phase of extension | |
| Qing-long et al. | Field weakening control technology for asynchronous motor of electric vehicle | |
| CN110545055B (en) | Control method of generator motor of variable-speed pumped storage power station |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |