CN113036770A - Power balancing device for alternating-current power distribution network - Google Patents

Power balancing device for alternating-current power distribution network Download PDF

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Publication number
CN113036770A
CN113036770A CN202110292571.7A CN202110292571A CN113036770A CN 113036770 A CN113036770 A CN 113036770A CN 202110292571 A CN202110292571 A CN 202110292571A CN 113036770 A CN113036770 A CN 113036770A
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China
Prior art keywords
power
distribution network
rectifier
inverter
current
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Pending
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CN202110292571.7A
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Chinese (zh)
Inventor
陈武
何国豪
舒良才
马大俊
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Southeast University
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Southeast University
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Priority to CN202110292571.7A priority Critical patent/CN113036770A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)

Abstract

The invention discloses a power balancing device for an alternating-current power distribution network, and belongs to the field of power distribution networks. An ac distribution network power balancing apparatus comprising: a transformer and a converter, the converter comprising a rectifier and an inverter electrically coupled; the transformer is at least provided with two homonymous terminals and a public terminal, and one homonymous terminal and the public terminal form a primary side port which is cascaded with the power distribution network; the other homonymous terminal and the common terminal form a secondary side port which is cascaded with the rectifier; the primary side port is coupled with the output end of the inverter to form an output port; the control method of the rectifier is double closed-loop control, and the control method of the inverter is closed-loop control. The topology combines the autotransformer and the power electronic transformer, so that two sides of the power electronic converter only need to bear partial voltage of an alternating current power supply node, and meanwhile, power control is realized by controlling current at two ends of the converter.

Description

Power balancing device for alternating-current power distribution network
Technical Field
The invention relates to the field of power distribution networks, in particular to a power balancing device of an alternating current power distribution network.
Background
With the massive access of various distributed power supplies in China, the increase of bidirectional interaction between users and a power distribution network and the wide application of power electronic devices, the conventional alternating-current power distribution network structure cannot meet the requirements of various power supply modes, bidirectional energy flow, active power flow regulation and reliability of the power distribution network. The power balance technology can enable a plurality of feeders to form a closed loop, thereby realizing multi-end loop closing operation among the feeders, realizing flexible power flow control among the feeders, achieving the effects of balancing load, optimizing power supply capacity of a power grid, providing dynamic reactive power support, improving reliability of a power distribution network and equipment utilization rate, and remarkably improving reliability and transfer capacity when a system N-1 fails.
The existing power balancing apparatus generally achieves power balance through a full-capacity back-to-back converter, such as the power balance between different power nodes in a single-phase power grid shown in fig. 1, and the structure includes AC/DC and DC/AC two-stage conversion, and two ends of the converter are coupled with the power nodes. However, in the scheme of the full-capacity back-to-back converter, the back-to-back converter needs to bear all high voltages of the ac power source node, and has high requirements on the voltage endurance capability of the power electronic devices, and the capacity of the converter is the same as the power to be transmitted, which is difficult to meet the increasing power transmission requirement.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a power balancing device for an alternating current power distribution network.
The purpose of the invention can be realized by the following technical scheme:
an ac distribution network power balancing apparatus comprising: a transformer and a converter, the converter comprising a rectifier and an inverter electrically coupled;
the transformer is at least provided with two homonymous terminals and a public terminal, and one homonymous terminal and the public terminal form a primary side port which is cascaded with the power distribution network; the other homonymous terminal and the common terminal form a secondary side port which is cascaded with the rectifier; the primary side port is coupled with the output end of the inverter to form an output port;
the rectifier control method is that the outer ring is direct-current voltage, the inner ring is input current double closed-loop control, and the inverter control method is output current closed-loop control.
Further, the rectifier includes a rectifying full bridge and a filter inductor coupled with an input of the rectifying full bridge.
Further, the rectifier is connected with a direct current port of the inverter, and the direct current port is connected with a filter capacitor in parallel.
The power balancing device of the alternating current power distribution network is applied between two nodes with the same voltage class in the alternating current power distribution network.
The power balancing device of the alternating-current power distribution network is applied to a single-phase alternating-current power grid and a three-phase alternating-current power grid.
Drawings
The invention will be further described with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a power distribution network of the prior art;
FIG. 2 is a schematic diagram of a power distribution network power balancing apparatus in one example of the present application;
fig. 3 is a circuit schematic of a power electronic converter in one example of the present application;
FIG. 4 is a schematic diagram of an overall signal sampling and control circuit in one example of the present application;
fig. 5 is a flow chart of a current closed loop control of an inverter side DC/AC inverter in a power electronic transformer according to an example of the present application;
fig. 6 is a phasor diagram of an exemplary power balancing apparatus input and output current and a power electronic converter input current of the present application;
fig. 7 is a flow chart of a double closed loop control of a rectification side AC/DC rectifier in a power electronic converter according to an example of the present application.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 2 is a schematic circuit diagram of a power balancing apparatus for a power distribution network according to the present invention. The power balance device of the invention comprises an autotransformer TauAnd a power electronic converter Tpe. Autotransformer TauThe power distribution network node has three terminals x, y and z, wherein the terminals x and y are homonymous terminals, the terminal z is a public terminal, the terminal x and the terminal z are primary side ports, the primary side ports are in cascade connection with a power distribution network node A, the terminal y and the terminal z are secondary side ports, and the primary side ports and a converter T are connected with the power distribution network node ApeThe input ends are cascaded. Power electronic converter TpeThe rectifier is formed by cascading a rectifier-side AC/DC rectifier and an inverter-side DC/AC inverter, wherein an output direct-current port of the rectifier-side AC/DC rectifier is connected with an input direct-current port of the inverter-side DC/AC inverter, alternating-current input terminals of the rectifier are a and b, and alternating-current output terminals of the inverter are c and d. Converter TpeInput terminals a, b of and transformer TauSecondary side terminals y, z of the converter TpeOutput terminal d and transformer TauIs connected to the secondary side terminal z. Converter TpeTerminal c and autotransformer TauConstitutes an output port and is connected to the distribution network node B. The topology combines the autotransformer and the power electronic transformer, so that two sides of the power electronic converter only need to bear partial voltage of an alternating current power supply node, and meanwhile, power control is realized by controlling current at two ends of the converter.
As shown in FIG. 3, the rectification side AC/DC rectifier of the power electronic converter consists of a full bridge rectified by switching tubes and two filter inductors L1And L1′The inductor is connected in series with the input end of the rectifying full bridge. The DC/AC inverter on the inversion side is formed by inverting a full bridge and two filter inductors L by a switching tube2And L2′The inductor is connected in series with the output end of the inverter full bridge. The rectifier is connected with the DC side port of the inverter, and the DC port is connected with a DC filter capacitor in parallel.
In the power electronic converter, a rectification side AC/DC rectifier realizes input side power factor correction and control of stabilization of direct current side voltage by using a double closed loop control strategy that output direct current voltage is an outer loop and input current of the rectifier is an inner loop. The DC/AC inverter on the inversion side adopts closed-loop control of output current, thereby realizing control of transmission power.
As shown in the detailed topology of the invention in FIG. 4, the rectification side AC/DC rectifier in the power electronic converter uses the control strategy of voltage outer loop and current inner loop double closed loop to realize the input side power factor correction and control the stabilization of the DC side voltage, wherein, the rectifier input current i1By input current i of power-balancing meansinAnd an output current ioutAnd calculating to obtain the following calculation formula:
i1＝N(iin-iout)
wherein, the primary-secondary side transformation ratio of the autotransformer is N: 1.
The DC/AC inverter on the inverting side adopts an output current i2Thereby realizing the control of the transmission power.
As shown in FIG. 5, the inverter-side DC/AC inverter employs an output current i2Control its output current i2Phase of and voltage u of AC power supply node BsBSame, output current i2Is calculated according to the following formula:
I2_ref＝Ptran/UsB
wherein, I2_refGiven value i of output current of inverter2_refEffective value of (P)tranFor a given value of the power transmitted from node A of the distribution network to node B of the distribution network, UsBFor node B voltage u of the distribution networksBIs determined.
Obtaining the phase angle theta of the node B of the power distribution network through a phase-locked loopBDue to the output current i2Phase of and voltage u of AC power supply node BsBInstead, a reference value i of the output current is obtained2_ref＝I2_ref·cos(ωt+θB) Will output a current i2With its reference value i2_refAnd comparing, obtaining PWM modulation through a proportional-integral link, and then carrying out PWM modulation to generate a driving signal.
As shown in FIG. 6, since the input and output sides of the power balance device of the present invention are both power factor corrected, the power balance device of the present invention can be used for correcting the power factor
Figure BDA0002982889880000051
Phase of
Figure BDA0002982889880000052
In the same way, the first and second,
Figure BDA0002982889880000053
phase of
Figure BDA0002982889880000054
The same is true. As can be seen from the circuit of fig. 4, the input current of the power electronic converter can be obtained by the following formula:
Figure BDA0002982889880000055
and then can obtain
Figure BDA0002982889880000056
Phase of (a)1。
As shown in FIG. 7, the rectifier side AC/DC rectifier uses a dual closed loop control strategy, in which the voltage outer loop controls the voltage stabilization on the DC side of the rectifier, and the DC side voltage UDCWith its reference value UDC_refAfter comparison, a reference value I of the input current amplitude is obtained through a proportional integral link1_refThe voltage on the DC side is simultaneously greater than the voltage u at the a and b endsabAnd c, d terminal voltage ucdPeak value of (a).
The current inner loop controls the power factor correction, the amplitude I of the input current reference value1_refGiven by the output value of the voltage outer loop, the phase angle of the input current reference value is theta1Obtaining a reference value i of the output current1_ref＝I1_ref·cos(ωt+θ1) Will output a current i1With its reference value i1_refAnd comparing, generating PWM modulation through a proportional-integral link, and then performing PWM modulation to generate a driving signal.
In the case, the embodiment can realize power balance between two nodes in an alternating-current power distribution network and also realize power factor correction under the condition that two sides of the power electronic converter only need to bear partial voltage of an alternating-current power supply node.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed.

Claims (5)

1. An ac distribution network power balancing apparatus, comprising: a transformer and a converter, the converter comprising a rectifier and an inverter electrically coupled;
the transformer is at least provided with two homonymous terminals and a public terminal, wherein one homonymous terminal and the public terminal form a primary side port which is in cascade connection with the power distribution network; the other homonymous terminal and the common terminal form a secondary side port which is cascaded with the rectifier; the primary side port is coupled with the output end of the inverter to form an output port;
the rectifier control method is that the outer ring is direct-current voltage, the inner ring is input current double closed-loop control, and the inverter control method is output current closed-loop control.
2. The ac power distribution network power balancing apparatus of claim 1, wherein the rectifier comprises a rectifying full bridge and a filter inductor coupled to an input of the rectifying full bridge.
3. The power balancing apparatus for ac distribution networks according to claim 1, wherein the rectifier is connected to the dc port of the inverter, and the dc port is connected in parallel with the filter capacitor.
4. Use of a power balancing device according to claim 1 for an ac distribution network between two nodes of the same voltage class in the ac distribution network.
5. Use of the power balancing device of an ac distribution network according to claim 1 in single phase ac networks and three phase ac networks.
CN202110292571.7A 2021-03-18 2021-03-18 Power balancing device for alternating-current power distribution network Pending CN113036770A (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106849095A (en) * 2017-02-27 2017-06-13 中国科学院电工研究所 For the non-full capacity power exchanging device of same AC network difference node

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106849095A (en) * 2017-02-27 2017-06-13 中国科学院电工研究所 For the non-full capacity power exchanging device of same AC network difference node

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