CN111697634A - Modeling method for DC voltage control small signal based on instantaneous power at AC/DC side - Google Patents

Modeling method for DC voltage control small signal based on instantaneous power at AC/DC side Download PDF

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CN111697634A
CN111697634A CN202010432161.3A CN202010432161A CN111697634A CN 111697634 A CN111697634 A CN 111697634A CN 202010432161 A CN202010432161 A CN 202010432161A CN 111697634 A CN111697634 A CN 111697634A
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current
representing
converter
power
voltage
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CN111697634B (en
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林莉
马明辉
金鑫
贾源琦
王静芝
罗皓
汪莎莎
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Chongqing University
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    • 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
    • H02J5/00—Circuit arrangements for transfer of electric power between ac networks and dc networks
    • 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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

The application provides a modeling method of a direct-current voltage control small signal based on instantaneous power at an alternating-current side and a direct-current side, which comprises the following steps: s1: constructing a small signal model of a power balance equation of an AC side of a converter in a DC distribution network; s2: constructing a small signal model of a converter direct current side power balance equation in a direct current distribution network; s3: constructing a direct-current voltage control small signal model according to the power balance relation between the alternating current side and the direct current side of a converter in a direct-current distribution network; the S1 further includes: s11: determining a power balance equation of an alternating current side of a converter in a direct current distribution network; the S2 further includes: s21: determining the voltage-current relationship after the DC side of the converter is added into the LC type filter according to the positive and negative of the power value; s22: and determining a power balance equation of the direct current side of the converter in the direct current distribution network. The modeling method provided by the invention takes the influence of the energy storage element at the AC/DC side of the converter on the DC voltage control effect in the system operation process into account on the basis of considering the power loss of the converter and the switching device, and improves the accuracy of the DC voltage control small-signal model.

Description

Modeling method for DC voltage control small signal based on instantaneous power at AC/DC side
Technical Field
The invention relates to the technical field of operation control of a direct-current distribution network system, in particular to a modeling method of a direct-current voltage control small signal based on instantaneous power at an alternating-current side and a direct-current side.
Background
In recent years, a direct current distribution network is widely concerned due to the fact that the direct current distribution network has high-efficiency distributed energy access capability and can be connected with a traditional alternating current power grid to form a multi-terminal power grid, a converter is a core device with the most complex function of a direct current power grid, an alternating current side energy storage unit of a voltage source type converter can bring instantaneous power flow change inside the converter, and the dynamic response of a small signal of direct current bus voltage can be changed from a minimum system in an inversion operation state to a non-minimum phase system in a rectification operation state, so that the stability of direct current voltage control is influencedlossHowever, the corresponding current i is not taken into account when defining the DC-side DC currentloss② when the instantaneous power of the DC side capacitor is taken into account, the voltage V on the DC side of the converter is not taken into account by the voltage drop caused by the newly added DC side inductordcAs the capacitor voltage
Figure BDA0002500978260000011
Therefore, a direct-current voltage control small-signal model fine modeling method considering the instantaneous power at the alternating-current and direct-current sides of the direct-current distribution network voltage source converter, which is used for overcoming the defects in the prior art, is needed.
Disclosure of Invention
In view of this, the present invention provides a modeling method for dc voltage control small signal based on instantaneous power at ac/dc side.
The invention provides a modeling method of a direct current voltage control small signal based on instantaneous power at an alternating current side and a direct current side, which is characterized by comprising the following steps of: the method comprises the following steps:
s1: constructing a small signal model of a power balance equation of an AC side of a converter in a DC distribution network;
s2: constructing a small signal model of a converter direct current side power balance equation in a direct current distribution network;
s3: constructing a direct-current voltage control small signal model according to the equal relation between an alternating-current side small signal model and a direct-current side small signal model of a current converter in a direct-current distribution network;
the step S1 further includes:
s11: determining a power balance equation of an alternating current side of a converter in a direct current distribution network;
the step S2 further includes:
s21: determining the voltage-current relationship after the DC side of the converter is added into the LC type filter according to the positive and negative of the power value;
s22: and determining a power balance equation of the direct current side of the converter in the direct current distribution network.
Further, the alternating-current side power balance equation is determined by the following method:
1.5VsdId-DWL-PR-Pt＝0 (1)
wherein Vsd represents the d-axis component of the AC side grid voltage of the converter in dq coordinate system, IdRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000021
D represents a differential factor with respect to time, Dx ═ D (x)/dt, WLRepresenting equivalent inductance on the ac sideEnergy, PRRepresents the equivalent resistance R (R) of the AC sidesAnd ronSum) of power, PtRepresenting the converter ac side power.
Further, the small signal model of the alternating-current side power balance equation is determined by adopting the following method:
ΔPt＝1.5Id0ΔVsd+(-1.5LsId0s+1.5Vsd0-3RId0)ΔId-(1.5LsIq0s+3RIq0)ΔIq(2)
wherein, Δ PtRepresenting a small semaphore on the AC side, Id0Indicates the steady-state operating point IdCorresponding value, VsdRepresenting d-axis component of AC side network side voltage of the converter in dq coordinate system, Ls representing sum of equivalent inductance and transformer leakage inductance of coupling transformer and reactor, s representing Laplace operator, and V representingsd0Representing the steady-state operation point of the d-axis component of the AC side network side voltage of the converter in a dq coordinate system, R representing the equivalent resistance of a coupling transformer and a reactor, IdRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000032
Active term of (1)q0Indicates the steady-state operating point IqCorresponding steady state value, IqAnd the q-axis component of the grid side current dq coordinate system of the AC side of the converter is shown.
Further, the relationship between the voltage and the current is determined by the following method:
Figure BDA0002500978260000033
wherein iLeqRepresenting the inductor current, IdcRepresenting the DC current at the outlet of a DC line connected to the DC side of the converter, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, VdcIndicating the DC voltage at the outlet of the DC link at the DC side of the converter, VCeqRepresenting the capacitor voltage, LeqRepresenting the equivalent inductance on the DC side, D-tableThe differentiation factor over time is shown, Dx ═ d (x)/dt.
Further, the power balance equation of the AC side of the converter in the DC distribution network is determined by adopting the following method:
Figure BDA0002500978260000034
wherein, PdcRepresents the transmission power of the DC side of the converter, D represents the differential factor of time, Dx ═ D (x)/dt, CeqRepresents the equivalent capacitance, V, of the DC sideCeqRepresenting the capacitor voltage, LeqRepresents the equivalent inductance of the DC side, iLeqRepresenting the inductor current, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, IdcRepresenting the direct current at the outlet of the DC link at the DC side of the converter, VdcWhich represents the dc voltage at the outlet of the dc link connected to the dc side of the converter.
Further, the small-signal model of the direct-current side power balance equation is determined by adopting the following method:
Figure BDA0002500978260000031
wherein, Δ PdcRepresenting a small semaphore on the DC side, CeqRepresents the equivalent capacitance on the DC side, LeqRepresents the equivalent inductance of the DC side, Ploss0Representing steady state value of power loss, Vdc0Representing the corresponding value of the DC voltage at the outlet of the converter at the steady-state operating point, Idc0Representing the corresponding value of the DC current at the outlet of the converter at the steady-state operation point, S represents the Laplace operator, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process.
Further, step S3 further includes: and obtaining a direct-current voltage control small signal model by combining the converter double-loop control structure.
The invention has the beneficial technical effects that: the modeling method provided by the invention takes the influence of the energy storage element at the AC/DC side of the converter on the DC voltage control effect in the system operation process into account on the basis of considering the power loss of the converter and the switching device, and improves the precision of the DC voltage control small-signal model.
Drawings
The invention is further described below with reference to the following figures and examples:
fig. 1 is a three-terminal dc distribution network topology structure diagram of the present application.
Fig. 2 is a topology structure diagram of a dc distribution network voltage source converter according to the present application.
Fig. 3 is a double-loop control structure diagram of the voltage source converter of the direct-current distribution network.
Fig. 4 is a dc voltage control small signal model of the applied dc distribution network voltage source converter.
Detailed Description
The invention is further described with reference to the accompanying drawings in which:
the invention provides a modeling method of a direct current voltage control small signal based on instantaneous power at an alternating current side and a direct current side, which is characterized by comprising the following steps of: the method comprises the following steps:
s1: constructing a small signal model of a power balance equation of an AC side of a converter in a DC distribution network;
s2: constructing a small signal model of a converter direct current side power balance equation in a direct current distribution network;
s3: constructing a direct-current voltage control small-signal model according to the power balance relation between the alternating-current side and the direct-current side of a converter in a direct-current distribution network;
the step S1 further includes:
s11: determining a power balance equation of an alternating current side of a converter in a direct current distribution network;
the step S2 further includes:
s21: determining the voltage-current relationship after the DC side of the converter is added into the LC type filter according to the positive and negative of the power value;
s22: and determining a power balance equation of the direct current side of the converter in the direct current distribution network.
In this embodiment, the ac-side power balance equation is determined by the following method:
1.5VsdId-DWL-PR-Pt＝0 (1)
wherein, VsdIs represented bydRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000051
D represents a differential factor with respect to time, Dx ═ D (x)/dt, WLRepresenting the energy of the equivalent inductance on the AC side, PRRepresents the equivalent resistance R (R) of the AC sidesAnd ronSum) of power, PtRepresenting the converter ac side power.
Because the current converter adopts current vector control, each term should use a current space vector in dq coordinate system
Figure BDA0002500978260000052
Represents, including a merit term IdAnd a reactive term Iq. While the instantaneous power of the ac side transmission can be expressed as:
Figure BDA0002500978260000053
wherein, Pac3-3Represents the instantaneous power of the ac side transmission,
Figure BDA0002500978260000054
a space vector representing the voltage on the ac side,
Figure BDA0002500978260000055
the space vector representing the alternating side current, followed by:
Figure BDA0002500978260000056
wherein, PRRepresents the equivalent resistance R (R) of the AC sidesAnd ronSum), R represents the ac-side equivalent resistance,
Figure BDA0002500978260000057
a space vector representing the voltage on the ac side,
Figure BDA0002500978260000058
space vector representing alternating side current, active term IdRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000059
Active term of (1)qRepresenting current space vectors in dq coordinate system
Figure BDA00025009782600000510
The reactive term of (2).
For an alternating-current side three-phase inductor, the stored energy is as follows:
Figure BDA00025009782600000511
wherein, WLRepresenting the energy of the equivalent inductance on the AC side, LSIs represented by iaRepresenting phase A current i in three-phase power on the AC sidebRepresenting the phase B current i in the three-phase power on the AC sidecShowing the phase C current in the three-phase power at the AC side,
wherein, the three-phase current on the alternating current side can be expressed as:
Figure BDA0002500978260000061
wherein iaRepresenting phase A current i in three-phase power on the AC sidebRepresenting the phase B current i in the three-phase power on the AC sidecRepresenting the C phase current in the three-phase power at the AC side, I is a space vector
Figure BDA0002500978260000062
The amplitude of (a) of (b) is,
Figure BDA0002500978260000063
to correspond to the phase angle, one can thus obtain:
Figure BDA0002500978260000064
wherein iaRepresenting phase A current i in three-phase power on the AC sidebRepresenting the phase B current i in the three-phase power on the AC sidecRepresenting the C phase current in the three-phase power at the AC side, I is a space vector
Figure BDA0002500978260000065
The amplitude of (c).
Thus, it is possible to obtain:
Figure BDA0002500978260000066
wherein, WLRepresenting the energy of the equivalent inductance on the AC side, LSIs expressed by I being a space vector
Figure BDA0002500978260000067
Amplitude of (1)dRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000068
Active term of (1)qRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000069
The reactive term of (2).
In this embodiment, the small-signal model of the ac-side power balance equation is determined by the following method:
ΔPt＝1.5Id0ΔVsd+(-1.5LsId0s+1.5Vsd0-3RId0)ΔId-(1.5LsIq0s+3RIq0)ΔIq(2)
wherein, Δ PtRepresenting a small semaphore on the AC side, Id0Indicates the steady-state operating point IdCorresponding value, VsdRepresenting d-axis component of the AC side network side voltage of the converter in dq coordinate system, Ls representing sum s of equivalent inductance and leakage inductance of the coupling transformer and reactor and Laplace operator, and V representing sum of equivalent inductance and leakage inductance of the transformersd0Represents VsdR represents the equivalent resistance of the coupling transformer and reactor, Iq0Indicates the steady-state operating point IqCorresponding value, IqAnd the q-axis component of the grid side current dq coordinate system on the AC side of the converter is shown, s represents a Laplace operator, and R represents equivalent resistance on the AC side.
Aiming at the fact that the power balance equation of the alternating current side of the converter obtained in the S1 is a nonlinear equation, the nonlinear equation is expanded by using Taylor series, and the specific calculation process is as follows:
and (3) dividing a function F:
Figure BDA0002500978260000072
wherein, VsdRepresenting the d-axis component, I, of the AC side grid side voltage of the converter in the dq coordinate systemdRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000073
Ls represents the sum of the equivalent inductance of the coupling transformer and reactor and the leakage inductance of the transformer, IqRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000074
D represents a differential factor with respect to time, Dx ═ D (x)/dt, PtRepresenting the converter ac side power.
Deployment is performed at steady state operating points:
Figure BDA0002500978260000071
wherein, Δ PtFor small semaphores, (H.O.T) is the high order term generated upon unfolding, neglected here, VsdIs represented bydRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000075
Active term of (1), Ls represents, IqRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000076
D represents a differential factor with respect to time, Dx ═ D (x)/dt, PtRepresenting the converter ac side power.
The system steady state operating point may be expressed as:
(E.P.)＝(Vsd-0,Id-0,DId-0,Iq-0,DIq-0,Pt-0)＝(Vsd0,Id0,0,Iq0,0,Pt0) (2-3)
wherein, Vsd0Is represented byd0Is represented byq0Is represented by Pt0To represent
Then, the following results are obtained:
ΔPt＝1.5Id0ΔVsd+1.5Vsd0ΔId-1.5LsId0Δ(DId)-1.5LsIq0Δ(DIq)-3RId0ΔId-3RIq0ΔIq(2-4)
wherein, Δ PtRepresenting a small semaphore on the AC side, Id0Is represented bydIs represented by VsdIs represented by Vsd0Is represented byq0Is represented byqLs represents, and R represents an ac equivalent resistance.
Laplace transform of the above equation can be obtained (Laplace operator is omitted)s)：
ΔPt＝1.5Id0ΔVsd+(-1.5LsId0s+1.5Vsd0-3RId0)ΔId-(1.5LsIq0s+3RIq0)ΔIq(2)
Wherein, Δ PtRepresenting a small semaphore on the AC side, Id0Is represented bydIs represented by VsdIs represented by Vsd0Is represented byq0Is represented byqIt is shown that Ls represents, R represents an ac equivalent resistance, and S represents a laplace operator.
In this embodiment, the relationship between the voltage and the current is determined by the following method:
Figure BDA0002500978260000081
wherein iLeqRepresenting the inductor current, IdcRepresenting the DC current at the outlet of a DC line connected to the DC side of the converter, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, VdcIndicating the DC voltage at the outlet of the DC link at the DC side of the converter, VCeqRepresenting the capacitor voltage, LeqD represents a differential factor with respect to time, and Dx ═ D (x)/dt.
In this embodiment, the power balance equation of the ac side of the converter in the dc distribution network is determined by the following method:
Figure BDA0002500978260000082
wherein, PdcRepresents the transmission power of the DC side of the converter, D represents the differential factor of time, Dx ═ D (x)/dt, CeqRepresents the equivalent capacitance, V, of the DC sideCeqRepresenting the capacitor voltage, LeqRepresents the equivalent inductance of the DC side, iLeqRepresenting the inductor current, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, IdcRepresenting the direct current at the outlet of the DC link at the DC side of the converter, VdcWhich represents the dc voltage at the outlet of the dc link connected to the dc side of the converter.
In this embodiment, the small-signal model of the dc-side power balance equation is determined by the following method:
Figure BDA0002500978260000091
wherein, Δ PtRepresents a small semaphore (in equation 2, Δ PtExpressing the small semaphore, it can be seen from the context that the small signal on the AC side is in equation 2, the small signal on the DC side is in equation 5, and one letter does not exist according to the relevant provisions of the patent LawCan simultaneously proxy two meanings, please ask the inventor to change the letter of formula 2 or formula 5 for small semaphore), CeqRepresents the equivalent capacitance on the DC side, LeqRepresents the equivalent inductance of the DC side, Ploss0Is represented by Vdc0Is represented bydc0Denotes, S denotes, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process.
Considering the constant P of AC/DC powert＝PdcThen, the following can be obtained:
Figure BDA0002500978260000092
wherein D represents a differential factor with respect to time, and Dx ═ D (x)/dt, CeqRepresents the equivalent capacitance, V, of the DC sidedcIndicating the DC voltage V at the outlet of the DC-side connected DC line of the converterCeqRepresenting the capacitor voltage, LeqRepresents the equivalent inductance of the DC side, iLeqRepresenting the inductor current, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, IdcRepresenting the DC current at the outlet of a DC line connected to the DC side of the converter, PtRepresenting the converter ac side power.
The above formula is expanded as:
Figure BDA0002500978260000101
wherein D represents a differential factor with respect to time, and Dx ═ D (x)/dt, CeqRepresents the equivalent capacitance, V, of the DC sidedcIndicating the DC voltage V at the outlet of the DC-side connected DC line of the converterCeqRepresenting the capacitor voltage, LeqRepresents the equivalent inductance of the DC side, iLeqRepresenting the inductor current, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, IdcRepresenting the DC current at the outlet of a DC line connected to the DC side of the converter, PtRepresenting the converter ac side power.
Then, the following results are obtained:
Figure BDA0002500978260000102
wherein D represents a differential factor with respect to time, and Dx ═ D (x)/dt, CeqRepresents the equivalent capacitance, V, of the DC sidedcIndicating the DC voltage V at the outlet of the DC-side connected DC line of the converterCeqRepresenting the capacitor voltage, LeqRepresents the equivalent inductance of the DC side, iLeqRepresenting the inductor current, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, IdcRepresenting the DC current at the outlet of a DC line connected to the DC side of the converter, PtRepresenting the converter ac side power.
The above formula is expressed by variable Vdc,DVdc,D2Vdc,Idc,DIdc,D2Idc,Ploss,DPloss,D2Ploss,PtExpressed as equation of dynamics G:
Figure BDA0002500978260000103
wherein the content of the first and second substances,
Figure BDA0002500978260000111
Figure BDA0002500978260000112
Figure BDA0002500978260000113
Figure BDA0002500978260000114
wherein D represents a differential factor with respect to time, and Dx ═ D (x)/dt, CeqRepresents the equivalent capacitance, V, of the DC sidedcIndicating the DC side of the converter is connected to DCDC voltage V at outlet of flow lineCeqRepresenting the capacitor voltage, LeqRepresents the equivalent inductance of the DC side, iLeqRepresenting the inductor current, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, IdcRepresenting the DC current at the outlet of a DC line connected to the DC side of the converter, PtRepresenting the converter ac side power.
Expanding the dynamic equation G at the steady-state operating point by using a Taylor series:
Figure BDA0002500978260000115
and the system steady state operating point may be expressed as:
(E.P.)＝(Vdc-0,DVdc-0,D2Vdc-0,Idc-0,DIdc-0,D2Idc-0,Ploss-0,DPloss-0,D2Ploss-0,Pt-0)
＝(Vdc0,0,0,Idc0,0,0,Ploss0,0,0,Pt0)
(5-6)
wherein, Pt0Is represented by Ploss0Is represented bydc0Is represented by Vdc0It is shown that,
then, a linear small signal dynamic equation of the direct current side of the converter can be obtained:
Figure BDA0002500978260000121
wherein, Pt0Is represented by Ploss0Is represented bydc0Is represented by Vdc0In the formula, D represents a time-dependent differential factor, Dx ═ D (x)/dt, CeqRepresents the equivalent capacitance, V, of the DC sidedcIndicating the DC voltage V at the outlet of the DC-side connected DC line of the converterCeqRepresenting the capacitor voltage, LeqRepresents the equivalent inductance of the DC side, iLeqRepresenting the inductor current, PlossIndicating reverse recovery and tracking current flow due to switchingPower loss due to stroke, IdcRepresenting the DC current at the outlet of a DC line connected to the DC side of the converter, PtRepresenting the converter ac side power.
Laplace transform of the above equation can be obtained (the laplace operator s is omitted):
Figure BDA0002500978260000122
the ac-dc side power balance of the inverter obtained in S11 and S22 respectively can obtain:
Figure BDA0002500978260000123
wherein, Δ PtRepresenting a small semaphore on the AC side, Id0Indicates the steady-state operating point IdCorresponding value, IdRepresenting current space vectors in dq coordinate system
Figure BDA0002500978260000131
R represents the equivalent resistance on the ac side, S represents the laplace operator, D represents the differential factor with respect to time, Dx ═ D (x)/dt, CeqRepresents the equivalent capacitance, V, of the DC sidedcIndicating the DC voltage V at the outlet of the DC-side connected DC line of the converterCeqRepresenting the capacitor voltage, LeqRepresents the equivalent inductance of the DC side, iLeqRepresenting the inductor current, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, IdcRepresenting the DC current at the outlet of a DC line connected to the DC side of the converter, PtRepresenting the converter ac side power.
In this embodiment, step S3 further includes: and obtaining a direct current voltage control small signal model by combining the converter double-loop control structure.
Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims (7)

1. A modeling method for controlling small signals by direct current voltage based on instantaneous power at an alternating current side and a direct current side is characterized by comprising the following steps: the method comprises the following steps:
s1: constructing a small signal model of a power balance equation of an AC side of a converter in a DC distribution network;
s2: constructing a small signal model of a converter direct current side power balance equation in a direct current distribution network;
s3: constructing a direct-current voltage control small signal model according to the equal relation between an alternating-current side small signal model and a direct-current side small signal model of a current converter in a direct-current distribution network;
the step S1 further includes:
s11: determining a power balance equation of an alternating current side of a converter in a direct current distribution network;
the step S2 further includes:
s21: determining the voltage-current relationship after the DC side of the converter is added into the LC type filter according to the positive and negative of the power value;
s22: and determining a power balance equation of the direct current side of the converter in the direct current distribution network.
2. The modeling method of the DC voltage control small signal based on the instantaneous power of the AC-DC side as claimed in claim 1, wherein: the alternating-current side power balance equation is determined by the following method:
1.5VsdId-DWL-PR-Pt＝0 (1)
wherein Vsd represents the d-axis component of the AC side grid voltage of the converter in dq coordinate system, IdRepresenting current space vectors in dq coordinate system
Figure FDA0002500978250000011
D represents a differential factor with respect to time, Dx ═ D (x)/dt, WLRepresenting equivalent inductance on the AC sideEnergy of PRRepresents the equivalent resistance R (R) of the AC sidesAnd ronSum) of power, PtRepresenting the converter ac side power.
3. The modeling method of the DC voltage control small signal based on the instantaneous power of the AC-DC side as claimed in claim 2, wherein: the small signal model of the alternating-current side power balance equation is determined by adopting the following method:
ΔPt＝1.5Id0ΔVsd+(-1.5LsId0s+1.5Vsd0-3RId0)ΔId-(1.5LsIq0s+3RIq0)ΔIq(2)
wherein, Δ PtRepresenting a small semaphore on the AC side, Id0Indicates the steady-state operating point IdCorresponding value, VsdRepresenting d-axis component of AC side network side voltage of the converter in dq coordinate system, Ls representing sum of equivalent inductance and transformer leakage inductance of coupling transformer and reactor, s representing Laplace operator, and V representingsd0Representing the steady-state operation point of the d-axis component of the AC side network side voltage of the converter in a dq coordinate system, R representing the equivalent resistance of a coupling transformer and a reactor, IdRepresenting current space vectors in dq coordinate system
Figure FDA0002500978250000023
Active term of (1)q0Indicates the steady-state operating point IqCorresponding steady state value, IqAnd the q-axis component of the grid side current dq coordinate system of the AC side of the converter is shown.
4. The modeling method of the DC voltage control small signal based on the instantaneous power of the AC-DC side as claimed in claim 1, wherein: the relationship between the voltage and the current is determined by the following method:
Figure FDA0002500978250000021
wherein iLeqRepresenting the inductor current, IdcRepresenting the DC current at the outlet of a DC line connected to the DC side of the converter, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, VdcIndicating the DC voltage at the outlet of the DC link at the DC side of the converter, VCeqRepresenting the capacitor voltage, LeqD represents a differential factor with respect to time, and Dx ═ D (x)/dt.
5. The modeling method of the DC voltage control small signal based on the instantaneous power of the AC-DC side as claimed in claim 4, wherein: the power balance equation of the AC side of the converter in the DC distribution network is determined by adopting the following method:
Figure FDA0002500978250000022
wherein, PdcRepresents the transmission power of the DC side of the converter, D represents the differential factor of time, Dx ═ D (x)/dt, CeqRepresents the equivalent capacitance, V, of the DC sideCeqRepresenting the capacitor voltage, LeqRepresents the equivalent inductance of the DC side, iLeqRepresenting the inductor current, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process, IdcRepresenting the direct current at the outlet of the DC link at the DC side of the converter, VdcWhich represents the dc voltage at the outlet of the dc link connected to the dc side of the converter.
6. The modeling method of the DC voltage control small signal based on the instantaneous power of the AC-DC side as claimed in claim 5, wherein: the small signal model of the direct current side power balance equation is determined by adopting the following method:
Figure FDA0002500978250000031
wherein, Δ PdcRepresenting a small semaphore on the DC side, CeqRepresents the equivalent capacitance on the DC side, LeqRepresenting direct currentSide equivalent inductance, Ploss0Representing steady state value of power loss, Vdc0Representing the corresponding value of the DC voltage at the outlet of the converter at the steady-state operating point, Idc0Representing the corresponding value of the DC current at the outlet of the converter at the steady-state operation point, S represents the Laplace operator, PlossRepresenting the power loss due to the reverse recovery of the switch and the tracking current process.
7. The modeling method of the DC voltage control small signal based on the instantaneous power of the AC-DC side as claimed in claim 5, wherein: step S3 further includes: and obtaining a direct-current voltage control small signal model by combining the converter double-loop control structure.
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