CN113626971B - DC transformer simulation modeling method and system based on AC-DC decoupling - Google Patents

DC transformer simulation modeling method and system based on AC-DC decoupling Download PDF

Info

Publication number
CN113626971B
CN113626971B CN202010387165.4A CN202010387165A CN113626971B CN 113626971 B CN113626971 B CN 113626971B CN 202010387165 A CN202010387165 A CN 202010387165A CN 113626971 B CN113626971 B CN 113626971B
Authority
CN
China
Prior art keywords
bridge
current
full
module
voltage
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.)
Active
Application number
CN202010387165.4A
Other languages
Chinese (zh)
Other versions
CN113626971A (en
Inventor
赵彪
安峰
宋强
余占清
曾嵘
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tsinghua University
Original Assignee
Tsinghua University
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Tsinghua University filed Critical Tsinghua University
Priority to CN202010387165.4A priority Critical patent/CN113626971B/en
Publication of CN113626971A publication Critical patent/CN113626971A/en
Application granted granted Critical
Publication of CN113626971B publication Critical patent/CN113626971B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/3353—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
  • Geometry (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses a DC transformer simulation modeling method and system based on AC-DC decoupling, wherein the method comprises the steps of firstly, performing equivalent decoupling on the input side and the output side of each sub-module of a modular combined DC transformer based on the connection mode of the input side and the output side of each sub-module in the modular combined DC transformer to obtain a first decoupling equivalent model; then, based on the first decoupling equivalent model, performing equivalent decoupling on the double-active full-bridge DC-DC converter in any sub-module in the modularized combined DC transformer to obtain a second decoupling equivalent model; and finally, based on the first decoupling equivalent model and the second decoupling equivalent model, combining one or more module sets consisting of the sub-modules to obtain the modular combined type direct current transformer rapid equivalent model. The modeling method is suitable for any high-voltage large-capacity large-scale modularized combined direct-current transformer, has strong universality and improves simulation precision and simulation efficiency.

Description

DC transformer simulation modeling method and system based on AC-DC decoupling
Technical Field
The invention belongs to the technical field of direct-current transformers, and particularly relates to a direct-current transformer simulation modeling method and system based on alternating-current and direct-current decoupling.
Background
The high-voltage direct current transmission technology has the advantages of large transmission capacity, long transmission distance, small loss and the like, so that the high-voltage direct current transmission technology is applied to large scale in China. The complementary characteristics of various energy sources can be fully utilized by constructing the high-voltage direct-current power grid, and the optimization configuration of resources in a large range, the reliable access of large-scale new energy sources and the improvement of the running stability of the existing power system are realized. The high-voltage high-capacity direct-current transformer is a key link for realizing high-efficiency access of renewable energy sources and interconnection of direct-current systems with different voltage levels.
The topology types of the existing high-voltage high-capacity direct-current transformer mainly comprise: thyristor resonance type, modularized multi-level type, switch capacitance type, modularized combination type direct current transformer, etc. The modular combined direct current transformer can effectively avoid direct series connection of power devices, has a modular structure, is convenient for standardized production, debugging and redundant design, and is widely adopted. Meanwhile, the double active full-bridge DC-DC converter is adopted as a basic power unit of the DC transformer, so that the DC transformer has the advantages of electric isolation, bidirectional power flow, high power density and the like, and the application requirements of the DC transformer in the DC system interconnection and new energy access scenes are met.
The external operation working condition of the direct current transformer is complex, and electromagnetic transient simulation analysis under various working conditions is necessary before actual production, installation and debugging. However, in order to construct a dc port of a transmission voltage class, a modular combined dc transformer usually needs to be formed by combining hundreds of sub-modules in series-parallel, which greatly increases the number of network nodes and power devices of the system, so that the simulation process is very slow. The existing rapid electromagnetic transient modeling method mainly comprises an equivalent modeling method based on a controlled source and a Thevenin equivalent modeling method. Compared with the Thevenin equivalent modeling, the equivalent modeling method based on the controlled source has clearer physical concept, avoids complex formula deduction and is easy to realize. However, the existing fast electromagnetic transient simulation method is mainly focused on the modularized multi-level converter, compared with the modularized multi-level converter, the structure of the direct current transformer is more complex, all the sub-modules of the direct current transformer are not connected in series, and meanwhile, each sub-module comprises eight switching devices, inductance, capacitance, transformers and other elements, so that the modeling method of the direct current transformer is difficult to be equivalent to the modularized multi-level converter.
Therefore, how to realize equivalent modeling of the direct current transformer becomes an urgent technical problem to be solved.
Disclosure of Invention
Aiming at the problems, the invention provides a DC transformer simulation modeling method and system based on AC-DC decoupling, wherein the modeling method has strong universality and high simulation precision.
The invention aims to provide a DC transformer simulation modeling method based on AC-DC decoupling, which comprises the following steps of,
based on a connection mode of an input side and an output side of each submodule in the modularized combined direct-current transformer, performing equivalent decoupling on the input side and the output side of each submodule of the combined direct-current transformer to obtain a first decoupling equivalent model;
based on the first decoupling equivalent model, performing equivalent decoupling on the double-active full-bridge DC-DC converter in any sub-module in the modular combined DC transformer to obtain a second decoupling equivalent model;
and combining one or more module sets consisting of the sub-modules based on the first decoupling equivalent model and the second decoupling equivalent model to obtain a modular combined type direct current transformer rapid equivalent model.
Further, the step of equivalently decoupling the input side and the output side of each sub-module of the modular combined direct current transformer based on the connection mode of the input side and the output side of each sub-module of the modular combined direct current transformer, the step of obtaining a first decoupling equivalent model comprises,
When the input sides of all the submodules in the modularized combined direct-current transformer are serial connection ports:
the input side currents of all the sub-modules are equal, and the input side of each sub-module is equivalent to a controlled current source; wherein the current value of each controlled current source is the input current I of the power supply side of the modularized combined direct current transformer in ；
Each series-connected submodule in the modularized combined direct-current transformer is equivalent to a controlled voltage source, and the voltage value of the controlled voltage source is the sum U of the voltages at the input sides of each submodule in ；
When the output sides of all the submodules in the modularized combined direct-current transformer are parallel connection ports:
the output side voltages of all the sub-modules are equal, and the output side of each sub-module is equivalent to a controlled voltage source; wherein the voltage value of the controlled voltage source is the output voltage U of the modularized combined direct current transformer o ；
The modularizationEach parallel submodule in the combined direct-current transformer is equivalent to a controlled current source, and the current value of the controlled current source is the sum I of the currents at the output sides of each submodule o 。
Further, the method comprises the steps of,
the sum U of the voltages at the input sides of the sub-modules in Sum of output side current I o The following relationship is satisfied:
wherein M is the total number of sub-modules in any module set in the modularized combined direct current transformer, i is E M, U ini Representing the voltage value at the input side of the ith sub-module, I oi The current value at the output side of the ith sub-module is shown.
Further, the step of equivalently decoupling the double-active full-bridge DC-DC converter in any sub-module in the modular combined DC transformer based on the first decoupling equivalent model, the step of obtaining a second decoupling equivalent model comprises,
equivalent decoupling of the dual active full bridge DC-DC converter into three parts includes: an input side DC port, an intermediate AC link, and an output side DC port, wherein,
the method comprises the steps of enabling an input side direct current port of a double-active full-bridge DC-DC converter to be equivalent to an input controlled current source, wherein the current of the input controlled current source is the input current of the double-active full-bridge DC-DC converter;
the method comprises the steps of enabling an intermediate alternating current link of a double-active full-bridge DC-DC converter to be equivalent to a primary full-bridge controlled voltage source, an isolation transformer and a secondary full-bridge controlled voltage source, wherein the voltages of the primary full-bridge controlled voltage source and the secondary full-bridge controlled voltage source are respectively the alternating current output voltages of the primary full-bridge and the secondary full-bridge;
And the direct current port at the output side of the double-active full-bridge DC-DC converter is equivalent to an output controlled current source, and the current of the output controlled current source is the output current of the double-active full-bridge DC-DC converter.
Further, based on the first decoupling equivalent model, the step of equivalently decoupling the double-active full-bridge DC-DC converter in any sub-module in the modular combined DC transformer, the step of obtaining a second decoupling equivalent model further comprises,
determining the current of the input controlled current source, the voltage of the primary full-bridge controlled voltage source, the voltage of the secondary full-bridge controlled voltage source and the current of the output controlled current source in any second decoupling equivalent model based on three working states of the primary full-bridge and the secondary full-bridge of the double-active full-bridge DC-DC converter under single-phase shift control; wherein,
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 11 And S is equal to 14 On and switch tube S 12 And S is equal to 13 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (1):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 12 And S is equal to 13 On and switch tube S 11 And S is equal to 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (2):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg And U fd Respectively represent a switching tube and a diodeI is the conduction voltage drop of Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 11 ～S 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (3):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fd Representing the conduction voltage drop of the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 15 And S is equal to 18 On and switch tube S 16 And S is equal to 17 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (4):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 16 And S is equal to 17 On and switch tube S 15 And S is equal to 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (5):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 15 ～S 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (6):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fd Representing the conduction voltage drop of the diode, i Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer.
Further, based on the formulas (1) - (6), I in the ith sub-module pi 、U abi 、U cdi And I si The method meets the following conditions:
or alternatively, the first and second heat exchangers may be,
wherein S is 11 -S 18 A switching signal representing each switching tube in the ith sub-module; u (U) abi And U cdi The alternating current output voltages of the primary full bridge and the secondary full bridge of the isolation transformer are respectively; i.e Li Inductance of the i-th moduleA stream; u (U) ini And U oi Respectively representing the input voltage and the output voltage of the ith module; u (U) fg And U fd Respectively representing the conduction voltage drops of the switching tube and the diode; i pi And I si Respectively representing the input current and the output current of the ith sub-module; n represents the transformation ratio of the isolation transformer; sign represents a sign function and v represents a logical or gate.
Another object of the present invention is to provide a dc transformer simulation modeling system based on ac-dc decoupling, the system comprising a first decoupling equivalent model, a second decoupling equivalent model and a modular combined dc transformer fast equivalent model, wherein,
the first decoupling equivalent model comprises an input side model and an output side model of a modularized combined direct current transformer submodule;
the second decoupling equivalent model comprises an input side direct current port model, an intermediate alternating current link model and an output side direct current port model of the double-active full-bridge DC-DC converter in any submodule of the modularized combined direct current transformer;
The modularized combined type direct current transformer rapid equivalent model is an equivalent model formed by combining one or more module sets consisting of sub-modules based on a first decoupling equivalent model and a second decoupling equivalent model.
Further, the input side model and the output side model of the sub-module of the modularized combined direct current transformer are equivalently decoupled based on the connection mode of the input side and the output side of the modularized combined direct current transformer; wherein,
when the input side of the modular combined direct-current transformer is a serial connection port:
the input side current of each sub-module is equal, and the input side of the sub-module is equivalent to a controlled current source; wherein the current value of the controlled current source is the input current I of the power supply side of the modularized combined direct current transformer in Each series-connected submodule in the modularized combined direct-current transformer is equivalent to a controlled voltage source, and the voltage value of the controlled voltage source is the voltage of the input side of each submoduleAnd U in ；
When the output side of the modularized combined direct-current transformer is a parallel connection port:
the output side voltages of all the sub-modules are equal, and the output side of each sub-module is equivalent to a controlled voltage source; wherein the voltage value of the controlled voltage source is the output voltage U of the modularized combined direct current transformer o The method comprises the steps of carrying out a first treatment on the surface of the The parallel submodules in the modularized combined direct-current transformer are equivalent to a controlled current source, and the current value of the controlled current source is the sum I of the currents at the output sides of the submodules o ；
The sum U of the voltages at the input sides of the sub-modules in Sum of output side current I o The following relationship is satisfied:
wherein M is the total number of sub-modules in any module set in the modularized combined direct current transformer, i is E M, U ini Representing the voltage value at the input side of the ith sub-module, I oi The current value at the output side of the ith sub-module is shown.
Further, the method comprises the steps of,
the direct current port model of the input side of the double-active full-bridge DC-DC converter is to equivalent the direct current port of the input side of the double-active full-bridge DC-DC converter to an input controlled current source, and the current of the input controlled current source is the input current of the double-active full-bridge DC-DC converter;
the model of the intermediate alternating current link of the double-active full-bridge DC-DC converter is to equivalent the intermediate alternating current link of the double-active full-bridge DC-DC converter to a primary full-bridge controlled voltage source, an isolation transformer and a secondary full-bridge controlled voltage source, wherein the voltage values of the primary full-bridge controlled voltage source and the secondary full-bridge controlled voltage source are respectively the alternating current output voltages of the primary full-bridge and the secondary full-bridge;
The direct current port model of the output side of the double-active full-bridge DC-DC converter is to equivalent the direct current port of the output side of the double-active full-bridge DC-DC converter to an output controlled current source, and the current of the output controlled current source is the output current of the double-active full-bridge DC-DC converter.
Further, the system also comprises a parameter acquisition model for acquiring the current of the input controlled current source, the voltage of the primary full-bridge controlled voltage source, the voltage of the secondary full-bridge controlled voltage source and the current of the output controlled current source in the input side direct current port model, the middle alternating current link model and the output side direct current port model of the double-active full-bridge DC-DC converter based on three working states of the primary full-bridge and the secondary full-bridge under single phase shift control,
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 11 And S is equal to 14 On and switch tube S 12 And S is equal to 13 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (1):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 12 And S is equal to 13 On and switch tube S 11 And S is equal to 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (2):
wherein U is ini Representing the input side of the ith sub-moduleVoltage value, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 11 ～S 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (3):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fd Representing the conduction voltage drop of the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 15 And S is equal to 18 On and switch tube S 16 And S is equal to 17 When the power-off is turned off, the double-active full-bridge DC-DC converter outputs the voltage U in an alternating current mode cdi And input side current I si Satisfy formula (4):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 16 And S is equal to 17 On and switch tube S 15 And S is equal to 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (5):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 15 ～S 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (6):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fd Representing the conduction voltage drop of the diode, i Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer;
Based on the formulas (1) - (6), I in the ith sub-module pi 、U abi 、U cdi And I si The method meets the following conditions:
or alternatively, the first and second heat exchangers may be,
wherein S is 11 -S 18 A switching signal representing each switching tube in the ith sub-module; u (U) abi And U cdi The alternating current output voltages of the primary full bridge and the secondary full bridge of the isolation transformer are respectively; i.e Li Representing the ith modeInductor current of the block; u (U) ini And U oi Respectively representing the input voltage and the output voltage of the ith module; u (U) fg And U fd Respectively representing the conduction voltage drops of the switching tube and the diode; i pi And I si Respectively representing the input current and the output current of the ith sub-module; n represents the transformation ratio of the isolation transformer; sign represents a sign function and v represents a logical or gate.
The invention has the beneficial effects that:
1. the high-order admittance matrix in the detailed model of the original modularized combined direct-current transformer is completely decomposed into the low-order subsystems by the rapid equivalent model, so that the low-order matrix is only required to be solved simultaneously, the simulation speed is increased, and the modeling method is suitable for establishing rapid equivalent modeling for large-scale modularized combined direct-current transformers in any high-voltage large-capacity occasion and has strong universality.
2. Aiming at a modularized combined direct current transformer taking a double-active full-bridge DC-DC converter as a basic power unit, each submodule in the direct current transformer is decomposed into a corresponding number of alternating current-direct current ports by an alternating current-direct current decoupling and node equivalent method, so that simulation accuracy can be ensured, and simulation efficiency can be greatly improved.
3. The three decoupled parts of the double-active full-bridge DC-DC converter are not electrically connected, and only secondary information is transmitted through a controlled source (a controlled current source or a controlled voltage source), so that not only is all switching devices omitted, but also the admittance matrix of the node network is reduced again to improve the simulation speed, and all characteristics of an original detailed model, such as voltage and current characteristics of an alternating current link, loss characteristics of a transformer and the switching devices and the like, can be effectively reserved.
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 may 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 drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 shows a topology of a modular combined DC transformer in accordance with an embodiment of the present invention;
FIG. 2 shows an equivalent decoupling schematic of a series-parallel submodule according to an embodiment of the present invention;
FIG. 3 shows an equivalent model of a dual active full bridge DC-DC converter in an embodiment of the invention;
FIG. 4 shows a fast equivalent model of a modular combined DC transformer in an embodiment of the invention;
fig. 5 shows the voltage U of the MVDC port of the modular combined dc transformer fast equivalent model FEM at the start-up stage and the detailed model DM of the conventional modular combined dc transformer in the embodiment of the present invention MV A simulation waveform comparison schematic diagram;
FIG. 6 shows the primary full-bridge AC output voltage U of the detailed model DM of the modular combined DC transformer and the FEM of the quick equivalent model of the modular combined DC transformer in the starting stage of the embodiment of the invention ab1 Inductor current i L1 And secondary side full bridge AC output voltage U cd1 Simulation comparison schematic diagram;
FIG. 7 shows the primary full-bridge AC output voltage U of the fast equivalent model FEM of the steady-state stage modular combined DC transformer and the detailed model DM of the conventional modular combined DC transformer in the embodiment of the invention ab1 Inductor current i L1 And secondary side full bridge AC output voltage U cd1 Simulation comparison schematic diagram;
fig. 8 shows a trend chart of the running time of the modular combined type dc transformer fast equivalent model FEM and the conventional modular combined type dc transformer detailed model DM according to the number of sub-modules in the embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention discloses a DC transformer simulation modeling method based on AC-DC decoupling, which is characterized in that firstly, based on the connection mode of the input side and the output side of each submodule in a modularized combined DC transformer, equivalent decoupling is carried out on the input side and the output side of each submodule of the combined DC transformer, and a first decoupling equivalent model is obtained; then, based on the first decoupling equivalent model, performing equivalent decoupling on the double-active full-bridge DC-DC converter in any sub-module in the modularized combined DC transformer to obtain a second decoupling equivalent model; and finally, based on the first decoupling equivalent model and the second decoupling equivalent model, combining one or more module sets consisting of the sub-modules to obtain the modular combined type direct current transformer rapid equivalent model. The high-order admittance matrix in the detailed model DM (model built by a switching device) of the original modularized combined direct current transformer is completely decomposed into a low-order subsystem by the rapid equivalent model FEM (fast equivalent model: model built according to an electromagnetic transient modeling algorithm), so that the low-order matrix is only required to be solved simultaneously, the simulation speed is increased, and the modeling method is suitable for rapid equivalent modeling of the large-scale modularized combined direct current transformer in any high-voltage high-capacity occasion and has strong universality.
Exemplary, a DAB (Dual Active Bridge: bi-directional full bridge) type modular combined type DC transformer using the dual active full bridge DC-DC converter shown in fig. 1 as a basic power unit is illustrated.
DAB type modular combined DC transformer junction shown in FIG. 1The structure comprises 1-N DAB module sets, wherein N is more than or equal to 1, namely DAB module set 1, DAB module sets 2 and … … and DAB module set N in figure 1. Because the input and output of each DAB module set are connected in series, the equivalent decoupling methods at the two ends of each DAB module set are consistent. A DAB module set internally comprises a plurality of DAB modules, namely a DAB module 1, a DAB module 2 and a … … and a DAB module M (also called DAB#1 and DAB#2 … … DAB#M), wherein M is more than or equal to 1. The input side of the DAB type modular combined direct-current transformer is an HVDC (High Voltage Direct Current: high-voltage direct-current transmission) port, and the voltage of the port is U HV The output side is MVDC (medium voltage direct current: medium voltage direct current transmission) port, the voltage of the port is U MV . At present, only one DAB module with internal input, serial output and parallel connection is taken as an example for analysis, and the specific equivalent decoupling method is as follows:
equivalent decoupling of the DAB module input side: because the input sides of all DAB modules in the DAB module set are connected in series, the input currents of all DAB modules are equal, the input sides of all DAB modules can be equivalent to a controlled current source, and the current value of each controlled current source is the input current I of the power supply side in The method comprises the steps of carrying out a first treatment on the surface of the From the input side of the DAB module set, each DAB module connected in series can be equivalent to a controlled voltage source, and the voltage value of the controlled voltage source is the sum U of the voltages at the input side of each DAB module in As shown in fig. 2.
Equivalent decoupling of the output side of the DAB module: because the output sides of the DAB modules are connected in parallel, the output voltages of the DAB modules are equal, the output sides of the DAB modules can be equivalently used as a controlled voltage source, and the voltage value of each controlled voltage source is the output voltage U o The method comprises the steps of carrying out a first treatment on the surface of the From the output side of the DAB module set, each DAB module connected in parallel can be equivalent to a controlled current source, and the current value of the controlled current source is the sum I of the currents of the output sides of each DAB module o As shown in fig. 2.
Specifically, as shown in fig. 2, in the DAB module set 1, the currents at the input sides of dab#1 to dab#m are all I in The voltages at the input sides of DAB#1-DAB#M are U respectively in1 -U inM 。
The voltages at the output sides of DAB#1-DAB#M are all U o The currents at the output sides of DAB#1-DAB#M are respectively I o1 -I oM, . Furthermore, any DAB module concentrates the sum U of the input side terminal voltages in Sum of output side current I o The method can be used for solving the problems that,
wherein M is the total number of DAB modules in any DAB module set, i is E M, U ini Representing the voltage value of the input side of the ith DAB module, I oi The current value at the output side of the ith DAB module is shown.
Through decoupling the input side and the output side of the DAB module set, electric decoupling among DAB modules in the modular combined direct current transformer can be realized, and meanwhile, transmission of secondary information among ports is ensured, so that a model after decoupling has the same simulation precision as an original detailed model.
In this embodiment, the dual-active full-bridge DC-DC converter in any DAB module of the combined DC transformer is subjected to equivalent decoupling modeling, and since the dual-active full-bridge DC-DC converter has a completely symmetrical topology, the supporting capacitors on the input side and the output side thereof respectively form two DC ports, and the two H-bridges (primary full-bridge and secondary full-bridge) plus the auxiliary inductor and the isolation transformer form an intermediate ac link to transmit energy, the dual-active full-bridge DC-DC converter is equivalently decoupled into three parts including an input side DC port, an intermediate ac link and an output side DC port. As shown in fig. 3, the dual active full-bridge DC-DC converter in the DAB module 1 in the DAB module set is exemplified, but not limited to the DAB module 1, and any DAB module is applicable.
The direct current port at the input side of the double-active full-bridge DC-DC converter is equivalent to an input controlled current source, and the current is I p1 ；
The intermediate alternating link of the double-active full-bridge DC-DC converter is equivalent to a primary full-bridge controlled voltage source, an isolation transformer and a secondary full-bridge controlled voltage source, wherein the primary full-bridge controlled voltageThe voltage values of the source and the secondary full-bridge controlled voltage source are respectively the alternating current output voltage U of the primary full-bridge and the secondary full-bridge ab1 And U cd1 ；
The output side direct current port of the double-active full-bridge DC-DC converter is equivalent to an output controlled current source, and the current is I s1 。
The three parts after decoupling are not electrically connected any more, and secondary information is transmitted only through a controlled source (a controlled current source or a controlled voltage source), compared with the existing modularized combined type direct current transformer average value model, discrete time model and the like, the modeling method in the embodiment of the invention not only omits all switching devices, but also is equivalent to reducing the admittance matrix of the node network again to improve the simulation speed, and can effectively keep all characteristics of the original detailed model, such as the voltage and current characteristics of an alternating current link, the loss characteristics of the transformer and the switching devices and the like.
In this embodiment, it is also necessary to determine I p1 、U ab1 、U cd1 And I s1 Wherein I is p1 、U ab1 、U cd1 And I s1 The parameter values of (a) are related to the operation state of each H-bridge of the double active full-bridge DC-DC converter under single phase shift control, and in particular, each H-bridge comprises three operation states. Taking the primary full-bridge of the double active full-bridge DC-DC converter in the DAB module 1 in FIG. 1 as an example, the working states thereof are respectively switch tubes S 11 And S is equal to 14 On and switch tube S 12 And S is equal to 13 Switch-off and switch tube S 12 And S is equal to 13 On and switch tube S 11 And S is equal to 14 Switch-off and switch tube S 11 ～S 14 All off, i.e. the locked state. In each working state, the relation between the alternating-current side voltage and the current of the converter and the relation between the direct-current side voltage and the current of the converter are different, and the specific is that:
in the primary full-bridge of the double-active full-bridge DC-DC converter, a switching tube S 11 And S is equal to 14 On and switch tube S 12 And S is equal to 13 When the switch is turned off, the voltage U of the primary full-bridge controlled voltage source ab1 And current I input to a controlled current source p1 The method meets the following conditions:
wherein U is in1 Indicating the voltage value of the input side of the DAB module 1, U fg For voltage drop over S11-S18 switching tubes, U fd Is the voltage drop across the diode in anti-parallel with S11-S18, i L1 The output current of the primary full-bridge in the double active full-bridge DC-DC converter in the DAB module 1 is shown.
In the primary full-bridge of the double-active full-bridge DC-DC converter, a switching tube S 12 And S is equal to 13 On and switch tube S 11 And S is equal to 14 When the switch is turned off, the voltage U of the primary full-bridge controlled voltage source ab1 And current I input to a controlled current source p1 The method meets the following conditions:
U in1 indicating the voltage value of the input side of the DAB module 1, U fg For voltage drop over S11-S18 switching tubes, U fd Is the voltage drop across the diode in anti-parallel with S11-S18, i L1 The output current of the primary full-bridge in the double active full-bridge DC-DC converter in the DAB module 1 is shown.
In the primary full-bridge of the double-active full-bridge DC-DC converter, a switching tube S 11 ～S 14 When the switch is turned off, the voltage U of the primary full-bridge controlled voltage source ab1 And current I input to a controlled current source p1 The method meets the following conditions:
wherein U is in1 Indicating the voltage value of the input side of the DAB module 1, U fd Is the voltage drop across the diode in anti-parallel with S11-S18, i L1 Representing the output current of the primary full bridge in the double active full bridge DC-DC converter in the DAB module 1;
similarly, the relationship of ac side voltage to current and DC side voltage to current for the secondary full bridge (H-bridge) of a dual active full bridge DC-DC converter is as follows:
in the secondary full-bridge of the double-active full-bridge DC-DC converter, a switching tube S 15 And S is equal to 18 On and switch tube S 16 And S is equal to 17 When the secondary side full-bridge controlled voltage source is turned off, the voltage U of the secondary side full-bridge controlled voltage source cd1 And outputting the current I of the controlled current source s1 The method meets the following conditions:
wherein U is o1 Indicating the voltage value at the output side of the DAB module 1, U fg For voltage drop over S11-S18 switching tubes, U fd Is the voltage drop across the diode in anti-parallel with S11-S18, i L1 The inductance current of the primary full bridge in the double active full bridge DC-DC converter in the DAB module 1 is represented, and n represents the transformation ratio of the isolation transformer;
in the secondary full-bridge of the double-active full-bridge DC-DC converter, a switching tube S 16 And S is equal to 17 On and switch tube S 15 And S is equal to 18 When the secondary side full-bridge controlled voltage source is turned off, the voltage U of the secondary side full-bridge controlled voltage source cd1 And outputting the current I of the controlled current source s1 The method meets the following conditions:
wherein U is o1 Indicating the voltage value at the output side of the DAB module 1, U fg For voltage drop over S11-S18 switching tubes, U fd Is the voltage drop across the diode in anti-parallel with S11-S18, i L1 The inductance current of the primary full bridge in the double active full bridge DC-DC converter in the DAB module 1 is represented, and n represents the transformation ratio of the isolation transformer;
in the secondary full-bridge of the double-active full-bridge DC-DC converter, a switching tube S 15 ～S 18 When the secondary side full-bridge controlled voltage source is turned off, the voltage U of the secondary side full-bridge controlled voltage source cd1 And outputting the current I of the controlled current source s1 The method meets the following conditions:
wherein U is o1 Indicating the voltage value at the output side of the DAB module 1, U fd Is the voltage drop across the diode in anti-parallel with S11-S18, i L1 The inductive current of the primary full bridge in the double active full bridge DC-DC converter in the DAB module 1 is shown, and n is the transformation ratio of the isolation transformer.
Based on the relation between the alternating-current side voltage and the current and the direct-current side voltage and the current of the primary side full bridge and the secondary side full bridge of the double-active full-bridge DC-DC converter, I in the second decoupling equivalent model p1 、U ab1 、U cd1 And I s1 The parameter values of (a) satisfy:
or alternatively, the first and second heat exchangers may be,
wherein S is 11 -S 18 A switching signal representing a switching tube in the DAB module 1; u (U) ab1 And U cd1 The alternating current output voltages of the H bridges at the two sides of the isolation transformer are respectively; i.e L1 Representing the inductor current in DAB module 1; u (U) in1 And U o1 Respectively representing an input voltage and an output voltage in the DAB module 1; u (U) fg And U fd Respectively representing the conduction voltage drops of the switching tube and the diode; i p1 And I s1 Respectively representing the input current and the output current in the DAB module 1; n represents the transformation ratio of the transformer; sign represents a sign function and v represents a logical or gate.
Preferably, the input sides of the respective DAB module sets in the DAB type modular combined type direct current transformer are also connected in series, and the output sides are also connected in parallel.
In addition, under the single phase shift working module, the double active full-bridge DC-DC converter in any sub-module has three states in one period, wherein the on and off time sequences of S11 and S14 are consistent, the on and off time sequences of S12 and S13 are consistent, namely the on and off time sequences of S15 and S18 are consistent, and the on and off time sequences of S16 and S17 are consistent, so that only one switch of two switches is needed to be selected for representing in the primary full-bridge and the secondary full-bridge.
By combining the equivalent decoupling methods of fig. 2 and fig. 3, all DAB modules in the DAB module set and DAB modules in the DAB module set are subjected to equivalent decoupling, so that the modular combined type direct current transformer shown in fig. 1 can be completely decomposed into low-order subsystems, and therefore, only the low-order matrixes are required to be solved simultaneously, and the simulation speed is increased. The final fast equivalent model of the high-voltage high-capacity modular combined dc transformer is shown in fig. 4.
As can be seen from fig. 5, the voltage of the DAB-type modular combined dc transformer reaches a given value 40kv at about 0.05s after the DAB-type modular combined dc transformer is started, and the fast equivalent model FEM of the DAB-type modular combined dc transformer can accurately and equivalently measure the average value of the detailed model DM, and meanwhile, the voltage ripples of the DAB-type modular combined dc transformer and the DAB-type modular combined dc transformer almost coincide (two curves in the figure coincide), so that the harmonic characteristics are completely consistent. Therefore, the fast equivalent model is only the segmentation and the equivalent of the electrical network nodes, and the method does not reduce the order of the electrical network nodes compared with the original detailed model, so that the electrical network nodes have very high accuracy.
As shown in FIG. 6, the DAB type modular combined DC transformer starts to output control pulse after starting for 0.03s, taking DAB module 1 as an example, and outputs voltage U at the primary side full bridge AC ab1 Under the action of (1) inductor current i L1 The capacitor in the secondary full bridge starts to be charged, and the secondary full bridge AC output voltage U cd1 The increase starts, and all three have very high coincidence with corresponding parameters in the DM detailed model.
As shown in fig. 7, in the steady state stage, the DAB module 1 is taken as an example, and the primary side full-bridge ac output voltage U of the DAB type modular combined dc transformer ab1 Inductor current i L1 And secondary side full bridge AC output voltage U cd1 Has very high coincidence with corresponding parameters in the DM detailed model, thus the DAB type modular combined straightThe fast equivalent model of the flow transformer has higher precision.
As shown in fig. 8, when the number of DAB modules of the DAB type modular combined dc transformer is 200, the calculation efficiency of the fast equivalent model FEM is two orders of magnitude higher than that of the DM detailed model, and the actual acceleration multiple is 270 times. With the increase of the number of direct current transformer submodules (DAB models), the simulation time of the detailed model increases exponentially, while the simulation time of the fast equivalent model increases linearly, so that the acceleration factor also increases exponentially.
The invention takes the interconnection of the direct current system as an application background, and aims at a modularized combined direct current transformer taking a double-active full-bridge DC-DC converter as a basic power unit, and each submodule in the direct current transformer is decomposed into a corresponding number of alternating current-direct current ports by an alternating current-direct current decoupling and node equivalent method, so that the simulation efficiency can be greatly improved while the simulation precision is ensured. The rapid equivalent modeling method for the large-scale modularized combined direct current transformer, which is suitable for the high-voltage high-capacity occasion, has extremely high simulation precision under various operation conditions. Meanwhile, compared with the original detailed model, the simulation efficiency of the quick equivalent model can be 1-2 orders of magnitude higher. In addition, the method is simultaneously suitable for control and real-time digital simulation of the serial-parallel combined converters of other topology types, and has strong practicability.
The embodiment of the invention also discloses a DC transformer simulation modeling system based on AC/DC decoupling, which can execute the modeling method, wherein the system comprises a first decoupling equivalent model, a second decoupling equivalent model and a modularized combined DC transformer rapid equivalent model, wherein the first decoupling equivalent model comprises an input side model and an output side model of a modularized combined DC transformer neutron module; the second decoupling equivalent model comprises an input side direct current port model, an intermediate alternating current link model and an output side direct current port model of the double-active full-bridge DC-DC converter in any submodule of the modularized combined direct current transformer; the modularized combined type direct current transformer rapid equivalent model is an equivalent model formed by combining one or more module sets consisting of sub-modules based on a first decoupling equivalent model and a second decoupling equivalent model.
The input side model and the output side model of the submodule of the modularized combined direct-current transformer are equivalently decoupled based on the connection mode of the input side and the output side of the modularized combined direct-current transformer; wherein,
when the input side of the modular combined direct-current transformer is a serial connection port:
The input side current of each sub-module is equal, and the input side of the sub-module is equivalent to a controlled current source; wherein the current value of the controlled current source is the input current I of the power supply side of the modularized combined direct current transformer in The serial submodules in the modularized combined direct-current transformer are equivalent to a controlled voltage source, and the voltage value of the controlled voltage source is the sum U of the voltages at the input sides of the submodules in ；
When the output side of the modularized combined direct-current transformer is a parallel connection port:
the output side voltages of all the sub-modules are equal, and the output side of each sub-module is equivalent to a controlled voltage source; wherein the voltage value of the controlled voltage source is the output voltage U of the modularized combined direct current transformer o The method comprises the steps of carrying out a first treatment on the surface of the The parallel submodules in the modularized combined direct-current transformer are equivalent to a controlled current source, and the current value of the controlled current source is the sum I of the currents at the output sides of the submodules o ；
The sum U of the voltages at the input sides of the sub-modules in Sum of output side current I o The following relationship is satisfied:
wherein M is the total number of sub-modules in any module set in the modularized combined direct current transformer, i is E M, U ini Representing the voltage value at the input side of the ith sub-module, I oi Representing the current at the output side of the ith sub-moduleValues.
The direct current port model of the input side of the double-active full-bridge DC-DC converter is to equivalent the direct current port of the input side of the double-active full-bridge DC-DC converter to an input controlled current source, and the current of the input controlled current source is the input current of the double-active full-bridge DC-DC converter;
the model of the intermediate alternating current link of the double-active full-bridge DC-DC converter is to equivalent the intermediate alternating current link of the double-active full-bridge DC-DC converter to a primary full-bridge controlled voltage source, an isolation transformer and a secondary full-bridge controlled voltage source, wherein the voltage values of the primary full-bridge controlled voltage source and the secondary full-bridge controlled voltage source are respectively the alternating current output voltages of the primary full-bridge and the secondary full-bridge;
the direct current port model of the output side of the double-active full-bridge DC-DC converter is to equivalent the direct current port of the output side of the double-active full-bridge DC-DC converter to an output controlled current source, and the current of the output controlled current source is the output current of the double-active full-bridge DC-DC converter.
The system also comprises a parameter acquisition model for acquiring the current of the input controlled current source, the voltage of the primary full-bridge controlled voltage source, the voltage of the secondary full-bridge controlled voltage source and the current of the output controlled current source in the input side direct current port model, the middle alternating current link model and the output side direct current port model of the double-active full-bridge DC-DC converter based on the relation between the alternating current side voltage and the current and the relation between the direct current side voltage and the current in three working states of the primary full-bridge and the secondary full-bridge under single-phase shift control of the double-active full-bridge DC-DC converter,
In the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, a switching tube S 11 And S is equal to 14 On and switch tube S 12 And S is equal to 13 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (1):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg For conducting voltage drop on S11-S18 switch tube, U fd Is the conduction voltage drop, i, over the diode in anti-parallel with S11-S18 Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, a switching tube S 12 And S is equal to 13 On and switch tube S 11 And S is equal to 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (2):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg For conducting voltage drop on S11-S18 switch tube, U fd Is the conduction voltage drop, i, over the diode in anti-parallel with S11-S18 Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, a switching tube S 11 ～S 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (3):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fd Is the conduction voltage drop, i, over the diode in anti-parallel with S11-S18 Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, a switching tube S 15 And S is equal to 18 On and switch tube S 16 And S is equal to 17 Shut offWhen in use, the double-active full-bridge DC-DC converter outputs an alternating current output voltage U cdi And input side current I si Satisfy formula (4):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg For conducting voltage drop on S11-S18 switch tube, U fd Is the conduction voltage drop, i, over the diode in anti-parallel with S11-S18 Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, a switching tube S 16 And S is equal to 17 On and switch tube S 15 And S is equal to 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (5):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fg For conducting voltage drop on S11-S18 switch tube, U fd Is the conduction voltage drop, i, over the diode in anti-parallel with S11-S18 Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, a switching tube S 15 ～S 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (6):
wherein U is oi Representing the ith sub-module inputVoltage value at the output side, U fd Is the conduction voltage drop, i, over the diode in anti-parallel with S11-S18 Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer;
based on the formulas (1) - (6), I in the ith sub-module pi 、U abi 、U cdi And I si The method meets the following conditions:
or alternatively, the first and second heat exchangers may be,
wherein S is 11 -S 18 A switching signal representing each switching tube in the ith sub-module; u (U) abi And U cdi The alternating current output voltages of the H bridges at the two sides of the isolation transformer are respectively; i.e Li Representing the inductor current of the ith module; u (U) ini And U oi Respectively representing the input voltage and the output voltage of the ith module; u (U) fg For voltage drop over S11-S18 switching tubes, U fd Is the conduction voltage drop on the diode connected in anti-parallel with S11-S18; i pi And I si Respectively representing the input current and the output current of the ith sub-module; n represents the transformation ratio of the isolation transformer; sign represents a sign function and v represents a logical or gate.
Although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (5)

1. A DC transformer simulation modeling method based on AC-DC decoupling is characterized in that the method comprises the following steps,
based on a connection mode of an input side and an output side of each submodule in the modularized combined direct-current transformer, performing equivalent decoupling on the input side and the output side of each submodule of the combined direct-current transformer to obtain a first decoupling equivalent model; comprising the steps of (a) a step of,
when the input sides of all the submodules in the modularized combined direct-current transformer are serial connection ports:
the input side currents of all the sub-modules are equal, and the input side of each sub-module is equivalent to a controlled current source; wherein the current value of each controlled current source is the input current I of the power supply side of the modularized combined direct current transformer in ；
Each series-connected submodule in the modularized combined direct-current transformer is equivalent to a controlled voltage source, and the voltage value of the controlled voltage source is the sum U of the voltages at the input sides of each submodule in ；
When the output sides of all the submodules in the modularized combined direct-current transformer are parallel connection ports:
the output side voltages of all the sub-modules are equal, and the output side of each sub-module is equivalent to a controlled voltage source; wherein the voltage value of the controlled voltage source is the output voltage U of the modularized combined direct current transformer o ；
Each parallel submodule in the modularized combined direct-current transformer is equivalent to a controlled current source, and the current value of the controlled current source is the sum I of the currents of the output sides of each submodule o ；
The sum U of the voltages at the input sides of the sub-modules in Sum of output side current I o The following relationship is satisfied:
wherein M is the total number of sub-modules in any module set in the modularized combined direct current transformer, i is E M, U ini Representing the voltage value at the input side of the ith sub-module, I oi Representing the ith sub-module inputCurrent value of the output side;
based on the first decoupling equivalent model, performing equivalent decoupling on the double-active full-bridge DC-DC converter in any sub-module in the modular combined DC transformer to obtain a second decoupling equivalent model; comprising the steps of (a) a step of,
equivalent decoupling of the dual active full bridge DC-DC converter into three parts includes: an input side DC port, an intermediate AC link, and an output side DC port, wherein,
The method comprises the steps of enabling an input side direct current port of a double-active full-bridge DC-DC converter to be equivalent to an input controlled current source, wherein the current of the input controlled current source is the input current of the double-active full-bridge DC-DC converter;
the method comprises the steps of enabling an intermediate alternating current link of a double-active full-bridge DC-DC converter to be equivalent to a primary full-bridge controlled voltage source, an isolation transformer and a secondary full-bridge controlled voltage source, wherein the voltages of the primary full-bridge controlled voltage source and the secondary full-bridge controlled voltage source are respectively the alternating current output voltages of the primary full-bridge and the secondary full-bridge;
the method comprises the steps of enabling a direct current port on the output side of a double-active full-bridge DC-DC converter to be equivalent to an output controlled current source, wherein the current of the output controlled current source is the output current of the double-active full-bridge DC-DC converter;
and combining one or more module sets consisting of the sub-modules based on the first decoupling equivalent model and the second decoupling equivalent model to obtain a modular combined type direct current transformer rapid equivalent model.
2. The method for modeling a DC-DC decoupling-based DC transformer according to claim 1, wherein the step of equivalently decoupling the double-active full-bridge DC-DC converter in any sub-module of the modular combined DC transformer based on the first decoupling equivalent model to obtain a second decoupling equivalent model further comprises,
Determining the current of the input controlled current source, the voltage of the primary full-bridge controlled voltage source, the voltage of the secondary full-bridge controlled voltage source and the current of the output controlled current source in any second decoupling equivalent model based on three working states of the primary full-bridge and the secondary full-bridge of the double-active full-bridge DC-DC converter under single-phase shift control; wherein,
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 11 And S is equal to 14 On and switch tube S 12 And S is equal to 13 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (1):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 12 And S is equal to 13 On and switch tube S 11 And S is equal to 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (2):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 11 ～S 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (3):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fd Representing the conduction voltage drop of the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 15 And S is equal to 18 On and switch tube S 16 And S is equal to 17 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (4):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 16 And S is equal to 17 On and switch tube S 15 And S is equal to 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (5):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li Represents the inductive current of the full bridge of the primary side of the ith sub-module, and n represents isolationA transformation ratio of the transformer;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 15 ～S 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (6):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fd Representing the conduction voltage drop of the diode, i Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer.
3. The simulation modeling method of a direct current transformer based on the alternating current-direct current decoupling according to claim 2, wherein based on the formulas (1) - (6), I in the ith sub-module pi 、U abi 、U cdi And I si The method meets the following conditions:
or alternatively, the first and second heat exchangers may be,
wherein S is 11 -S 18 A switching signal representing each switching tube in the ith sub-module; u (U) abi And U cdi The alternating current output voltages of the primary full bridge and the secondary full bridge of the isolation transformer are respectively; i.e Li Representing the inductor current of the ith module; u (U) ini And U oi Respectively representing the input voltage and the output voltage of the ith module; u (U) fg And U fd Respectively representing the conduction voltage drops of the switching tube and the diode; i pi And I si Respectively representing the input current and the output current of the ith sub-module; n represents the transformation ratio of the isolation transformer; sign represents a sign function and v represents a logical or gate.
4. A DC transformer simulation modeling system based on AC-DC decoupling is characterized by comprising a first decoupling equivalent model, a second decoupling equivalent model and a modularized combined DC transformer rapid equivalent model, wherein,
the first decoupling equivalent model comprises an input side model and an output side model of a modularized combined direct current transformer submodule;
the second decoupling equivalent model comprises an input side direct current port model, an intermediate alternating current link model and an output side direct current port model of the double-active full-bridge DC-DC converter in any submodule of the modularized combined direct current transformer;
the modularized combined type direct current transformer rapid equivalent model is an equivalent model formed by combining one or more module sets consisting of sub-modules based on a first decoupling equivalent model and a second decoupling equivalent model;
The input side model and the output side model of the submodule of the modularized combined direct-current transformer are equivalently decoupled based on the connection mode of the input side and the output side of the modularized combined direct-current transformer; wherein,
when the input side of the modular combined direct-current transformer is a serial connection port:
the input side current of each sub-module is equal, and the input side of the sub-module is equivalent to a controlled current source; wherein the current value of the controlled current source is the input current I of the power supply side of the modularized combined direct current transformer in The serial submodules in the modularized combined direct-current transformer are equivalent to a controlled voltage source, and the voltage value of the controlled voltage source is the sum U of the voltages at the input sides of the submodules in ；
When the output side of the modularized combined direct-current transformer is a parallel connection port:
output side voltage of each sub-module is uniformAnd the like, the output side of each sub-module is equivalent to a controlled voltage source; wherein the voltage value of the controlled voltage source is the output voltage U of the modularized combined direct current transformer o The method comprises the steps of carrying out a first treatment on the surface of the The parallel submodules in the modularized combined direct-current transformer are equivalent to a controlled current source, and the current value of the controlled current source is the sum I of the currents at the output sides of the submodules o ；
The sum U of the voltages at the input sides of the sub-modules in Sum of output side current I o The following relationship is satisfied:
wherein M is the total number of sub-modules in any module set in the modularized combined direct current transformer, i is E M, U ini Representing the voltage value at the input side of the ith sub-module, I oi Representing the current value of the output side of the ith sub-module;
the direct current port model of the input side of the double-active full-bridge DC-DC converter is to equivalent the direct current port of the input side of the double-active full-bridge DC-DC converter to an input controlled current source, and the current of the input controlled current source is the input current of the double-active full-bridge DC-DC converter;
the model of the intermediate alternating current link of the double-active full-bridge DC-DC converter is to equivalent the intermediate alternating current link of the double-active full-bridge DC-DC converter to a primary full-bridge controlled voltage source, an isolation transformer and a secondary full-bridge controlled voltage source, wherein the voltage values of the primary full-bridge controlled voltage source and the secondary full-bridge controlled voltage source are respectively the alternating current output voltages of the primary full-bridge and the secondary full-bridge;
the direct current port model of the output side of the double-active full-bridge DC-DC converter is to equivalent the direct current port of the output side of the double-active full-bridge DC-DC converter to an output controlled current source, and the current of the output controlled current source is the output current of the double-active full-bridge DC-DC converter.
5. The ac/DC decoupling-based DC transformer simulation modeling system of claim 4, further comprising a parameter acquisition model for acquiring a current of the input controlled current source, a voltage of the primary full-bridge controlled voltage source, a voltage of the secondary full-bridge controlled voltage source, and a current of the output controlled current source in the input side DC port model, the intermediate ac link model, and the output side DC port model of the dual-active full-bridge DC-DC converter based on three operating states of the primary full-bridge and the secondary full-bridge of the dual-active full-bridge DC-DC converter under single-phase shift control, wherein,
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 11 And S is equal to 14 On and switch tube S 12 And S is equal to 13 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (1):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 12 And S is equal to 13 On and switch tube S 11 And S is equal to 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (2):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg And U fd Indicating the conductance of the switching tube and diode respectivelyPressure drop through, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the primary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 11 ～S 14 When the power supply is turned off, the voltage U of the primary full-bridge controlled voltage source in the ith sub-module abi And current I input to a controlled current source pi Satisfy formula (3):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fd Representing the conduction voltage drop of the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 15 And S is equal to 18 On and switch tube S 16 And S is equal to 17 When the power-off is turned off, the double-active full-bridge DC-DC converter outputs the voltage U in an alternating current mode cdi And input side current I si Satisfy formula (4):
wherein U is ini Representing the voltage value of the input side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li Representing the inductive current of the full bridge at the primary side of the ith sub-module;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 16 And S is equal to 17 On and switch tube S 15 And S is equal to 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (5):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fg And U fd Respectively representing the conduction voltage drop of the switching tube and the diode, i Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer;
in the secondary full-bridge of the double-active full-bridge DC-DC converter in the ith submodule, the working state is a switching tube S 15 ～S 18 When the power supply is turned off, the voltage U of the secondary full-bridge controlled voltage source in the ith sub-module cdi And outputting the current I of the controlled current source si Satisfy formula (6):
wherein U is oi Representing the voltage value of the output side of the ith sub-module, U fd Representing the conduction voltage drop of the diode, i Li The inductive current of the full bridge at the primary side of the ith sub-module is represented, and n represents the transformation ratio of the isolation transformer;
based on the formulas (1) - (6), I in the ith sub-module pi 、U abi 、U cdi And I si The method meets the following conditions:
or alternatively, the first and second heat exchangers may be,
wherein S is 11 -S 18 A switching signal representing each switching tube in the ith sub-module; u (U) abi And U cdi The alternating current output voltages of the primary full bridge and the secondary full bridge of the isolation transformer are respectively; i.e Li Representing the ith moduleIs provided; u (U) ini And U oi Respectively representing the input voltage and the output voltage of the ith module; u (U) fg And U fd Respectively representing the conduction voltage drops of the switching tube and the diode; i pi And I si Respectively representing the input current and the output current of the ith sub-module; n represents the transformation ratio of the isolation transformer; sign represents a sign function and v represents a logical or gate.
CN202010387165.4A 2020-05-09 2020-05-09 DC transformer simulation modeling method and system based on AC-DC decoupling Active CN113626971B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010387165.4A CN113626971B (en) 2020-05-09 2020-05-09 DC transformer simulation modeling method and system based on AC-DC decoupling

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010387165.4A CN113626971B (en) 2020-05-09 2020-05-09 DC transformer simulation modeling method and system based on AC-DC decoupling

Publications (2)

Publication Number Publication Date
CN113626971A CN113626971A (en) 2021-11-09
CN113626971B true CN113626971B (en) 2024-03-12

Family

ID=78377520

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010387165.4A Active CN113626971B (en) 2020-05-09 2020-05-09 DC transformer simulation modeling method and system based on AC-DC decoupling

Country Status (1)

Country Link
CN (1) CN113626971B (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106026159A (en) * 2016-07-28 2016-10-12 南方电网科学研究院有限责任公司 Simulation device of modular multiple-level converter, simulation system and simulation method
CN206004320U (en) * 2016-07-28 2017-03-08 南方电网科学研究院有限责任公司 The simulator of modularization multi-level converter
WO2017041428A1 (en) * 2015-09-10 2017-03-16 南方电网科学研究院有限责任公司 Modelling method and system for diode clamped cascaded multi-level converter
CN109948185A (en) * 2019-02-01 2019-06-28 全球能源互联网研究院有限公司 A kind of decoupling emulation mode of electric system
CN110705035A (en) * 2019-09-09 2020-01-17 清华大学 Discrete state event driven decoupling simulation method of large-capacity power electronic system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017041428A1 (en) * 2015-09-10 2017-03-16 南方电网科学研究院有限责任公司 Modelling method and system for diode clamped cascaded multi-level converter
CN106026159A (en) * 2016-07-28 2016-10-12 南方电网科学研究院有限责任公司 Simulation device of modular multiple-level converter, simulation system and simulation method
CN206004320U (en) * 2016-07-28 2017-03-08 南方电网科学研究院有限责任公司 The simulator of modularization multi-level converter
CN109948185A (en) * 2019-02-01 2019-06-28 全球能源互联网研究院有限公司 A kind of decoupling emulation mode of electric system
CN110705035A (en) * 2019-09-09 2020-01-17 清华大学 Discrete state event driven decoupling simulation method of large-capacity power electronic system

Also Published As

Publication number Publication date
CN113626971A (en) 2021-11-09

Similar Documents

Publication Publication Date Title
CN103208929B (en) Based on the electronic power transformer of MMC
CN109067218B (en) Solid-state transformer topology construction method based on multi-level sub-modules
Li et al. DC/DC converter for bipolar LVdc system with integrated voltage balance capability
CN107332443A (en) A kind of DC solid transformer and its control method
CN110492514A (en) Solid-state transformer topology race and design method applied to alternating current-direct current mixing power distribution network
CN103427652A (en) High-voltage high-power DC-DC conversion device
US11888410B1 (en) Symmetric hybrid converters
Hu et al. Fault-tolerant converter with a modular structure for HVDC power transmitting applications
CN108306324B (en) Modularized centralized energy storage system
Wang et al. Analysis and optimisation of modulation strategy based on dual‐phase‐shift for modular multilevel high‐frequency‐link DC transformer in medium‐voltage DC distribution network
Pineda et al. Optimal ZCS modulation for bidirectional high-step-ratio modular multilevel DC–DC converter
CN106570226B (en) Mean value model and emulation mode in modularization multi-level converter
Wang et al. An X-type boost multilevel inverter based on switched capacitor cells with low-voltage stress and high-frequency applications
CN116826694B (en) Multi-port data center power supply system and power supply method
CN113890122A (en) Alternating current-direct current multiport power distribution system for office residential area
CN106505902A (en) LCC/VSC direct currents interconnect transformator
Khan et al. Stability Analysis and Control Design for Multiterminal HVDC Network With Power Flow Controller
CN113626971B (en) DC transformer simulation modeling method and system based on AC-DC decoupling
Cui et al. Bidirectional modular multilevel resonant DC-DC converter for medium voltage power conversion
CN108306318B (en) Symmetrical energy storage system based on modular multilevel converter
CN216215929U (en) Alternating current-direct current multiport power distribution system for office residential area
US20220366115A1 (en) General decoupling method and system for electromagnetic transient simulation of voltage source converter
Wang et al. Topology and Control Optimization of Bidirectional DC/DC Converter for Electric Vehicles
Qin et al. Simulation and Analysis of Multilevel DC Transformer Using Different Dual-Active-Bridge DC-DC Converter Models
CN113726162A (en) Series network type transformer based on voltage reduction type public direct current bus

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