CN111525583A - Voltage regulating transformer and power flow control system - Google Patents

Voltage regulating transformer and power flow control system Download PDF

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Publication number
CN111525583A
CN111525583A CN202010550443.3A CN202010550443A CN111525583A CN 111525583 A CN111525583 A CN 111525583A CN 202010550443 A CN202010550443 A CN 202010550443A CN 111525583 A CN111525583 A CN 111525583A
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China
Prior art keywords
transformer
voltage regulating
voltage
phase
output
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Pending
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CN202010550443.3A
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Inventor
宋洁莹
戴朝波
陆振纲
乔光尧
邓占锋
赵国亮
尉志勇
鲍伟
陈凯龙
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State Grid Corp of China SGCC
Global Energy Interconnection Research Institute
State Grid Shanghai Electric Power Co Ltd
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State Grid Corp of China SGCC
Global Energy Interconnection Research Institute
State Grid Shanghai Electric Power Co Ltd
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Priority to CN202010550443.3A priority Critical patent/CN111525583A/en
Publication of CN111525583A publication Critical patent/CN111525583A/en
Pending legal-status Critical Current

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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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

Abstract

The invention discloses a regulating transformer and a power flow control system, wherein the regulating transformer comprises: the transformer comprises a transformer and at least one voltage regulating circuit, wherein a primary side winding of the transformer is connected with an alternating current system, one end of a secondary side winding of the transformer is connected with the at least one voltage regulating circuit in series, and the other end of the secondary side winding is connected with the alternating current system; the voltage regulating circuit comprises at least one switch module, and the output voltage of the voltage regulating circuit is controlled by controlling the on-off state of the switch module. The invention connects the secondary side winding of the transformer with at least one voltage regulating circuit, adjusts the voltage of the output end of the voltage regulating circuit by changing the on-off state of the switch module, and realizes multi-gear voltage regulation and control of the voltage amplitude of the transmission line of the alternating current system by changing the voltage amplitude of the output end when the voltage regulating winding is completely connected into the transformer.

Description

Voltage regulating transformer and power flow control system
Technical Field
The invention relates to the technology of electric equipment, in particular to a voltage regulating transformer and a power flow control system.
Background
With the rapid development of economy, the increasing of social electricity consumption and the increasingly complex and flexible power grid structure bring higher requirements for the safe and economic operation of a power system. In order to ensure safe and economic operation of a power grid, flexible regulation and control of power flow are essential. A Flexible Alternating Current Transmission System (FACTS) utilizes a power electronic device to adjust power grid operation parameters and effectively regulate and control line power flow. A Unified Power Flow Controller (UPFC) is a device with the strongest function in FACTS, and can adjust the line end voltage and the line parameters, so that the UPFC has the capability of fast and independent Power Flow regulation and control, and has good performance in the aspects of dynamic reactive Power compensation, Power grid stability maintenance and the like. However, the UPFC is mainly composed of high-voltage high-power electronic devices, which is expensive, has a switching loss much higher than that of conventional electrical devices such as transformers, and is inferior to the conventional devices in terms of reliability. In consideration of economic factors and the like, the UPFC is not widely used in a high-voltage power grid. The traditional transformer tap switch is slow in action speed, has arcing risks, and influences the service life of the transformer tap switch after multiple actions. Meanwhile, the system can not be used for system oscillation and the like, and the aim of dynamic flexible support of the power grid voltage can not be achieved.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to overcome the defect that the transformer in the prior art cannot realize dynamic flexible support on the voltage of the power grid, thereby providing a voltage regulating transformer and a power flow control system.
In order to achieve the purpose, the invention provides the following technical scheme:
in a first aspect, an embodiment of the present invention provides a voltage regulating transformer, including: the transformer comprises a transformer and at least one voltage regulating circuit, wherein a primary side winding of the transformer is connected with an alternating current system, one end of a secondary side winding of the transformer is connected with the at least one voltage regulating circuit in series, and the other end of the secondary side winding is connected with the alternating current system; the voltage regulating circuit comprises at least one switch module, and the output voltage of the voltage regulating circuit is controlled by controlling the on-off state of the switch module.
In one embodiment, the voltage regulation circuit includes: the voltage regulating winding, two output and four switch modules, wherein, the one end of first switch module and third switch module is connected with the one end of voltage regulating winding, the other end of first switch module and the one end of second switch module are connected in first tie point, and draw forth first output in first tie point department, the other end of third switch module and the one end of fourth switch module are connected in the second tie point, and draw forth the second output in second tie point department, the other end of second switch module and the other end of fourth switch module all are connected with the other end of voltage regulating winding.
In one embodiment, when the secondary winding of the transformer is connected to a plurality of voltage regulating circuits, the output terminals of all the voltage regulating circuits are interconnected in series.
In one embodiment, the transformer is a single-phase transformer or a three-phase transformer.
In one embodiment, when the voltage regulating transformer comprises a transformer and a voltage regulating circuit, the voltage regulating circuit is connected in series with the secondary side winding of the transformer, and the output voltages of the two output ends of the voltage regulating circuit are three-level voltages by controlling the on-off state of the switch module.
In an embodiment, when the voltage regulating transformer comprises a transformer and two voltage regulating circuits, the two voltage regulating circuits are connected in series and then connected in series with the secondary side winding of the transformer, and the output voltages of the two output ends of the two voltage regulating circuits after being connected in series are nine-level voltages by controlling the on-off state of the switch module and the on-off state of the switch module.
In an embodiment, when the voltage regulating transformer comprises a transformer and three voltage regulating circuits, the three voltage regulating circuits are connected in series and then connected in series with the secondary side winding of the transformer, and the output voltages of two output ends of the three voltage regulating circuits after being connected in series are twenty-seven levels of voltage by controlling the on-off state of the switch module and the on-off state of the switch module.
In a second aspect, an embodiment of the present invention provides a power flow control system, including the voltage regulating transformer of the first aspect, further including: the controller and at least one converter, wherein, the input side of the converter is connected with the primary side winding of the regulating transformer, the output side is connected with the output end of the regulating circuit of the secondary side of the regulating transformer, the converter is used for regulating the amplitude and the phase of the voltage of the alternating current system; the controller is installed on an AC system power line and used for collecting the voltage and current of an installation point, a node in a preset adjacent range and a branch, or receiving a superior dispatching instruction and changing the voltage and the current of the AC system by coordinating the amplitude and the phase of the output voltage of the voltage regulating circuit and the current converter.
In one embodiment, the power flow control system further comprises: the bypass switch module is used for rapidly cutting off a fault point when any one of the voltage regulating circuit or the current converter has a fault; or the output end of the voltage regulating circuit is connected with the current converter through a bypass switch module, and the bypass switch module is used for cutting off a current loop of the voltage regulating circuit and the current converter when the voltage regulating circuit or the current converter fails.
In one embodiment, when the voltage regulating transformer is a single-phase transformer, one end of the primary winding of the single-phase transformer is connected to any one phase power transmission line of the ac system, the other end and the self-coupled output end of the primary winding of the single-phase transformer are connected to the input side of the converter, and one end of the output side of the converter is connected to the output end of the voltage regulating circuit on the secondary side of the single-phase transformer.
In one embodiment, when the regulating transformer is a three-phase transformer and the inverter is a single-phase inverter, the self-coupled output end of the primary winding of each phase of the three-phase transformer is connected with one end of the input side of one inverter, the other ends of the input sides of the three inverters are connected with each other, and one end of the output side of each inverter is connected with the output end of the regulating circuit of the secondary side of the corresponding phase of the three-phase transformer.
In one embodiment, the power flow control system further comprises: and when the regulating transformer is a three-phase transformer and the converter is a three-phase converter, the self-coupled output end of the primary side winding of each phase of the three-phase transformer is correspondingly connected with each input side of the converter, each phase of the output side of the converter is connected with one end of the primary side winding of one additional transformer, the other end of the primary side winding of each additional transformer is interconnected, one end of the secondary side winding of each additional transformer is respectively connected with the low potential output end or the high potential output end of the regulating circuit of the secondary side of the corresponding phase of the three-phase transformer, and the other ends of the secondary side.
In one embodiment, when one end of the secondary side winding of each additional transformer is respectively connected with the high-potential output end of the voltage regulating circuit of the corresponding secondary side of the three-phase transformer, one end of the secondary side winding of each phase of the three-phase transformer is connected with the ground, the other end of the secondary side winding of each phase of the three-phase transformer is connected with the corresponding secondary side winding of the additional transformer, and the low-potential output end of the voltage regulating circuit of the corresponding secondary side of the three-phase transformer.
In one embodiment, when one end of the secondary side winding of each additional transformer is connected with the low potential output end of the voltage regulating circuit of the corresponding phase secondary side of the three-phase transformer, one end of the secondary side winding of each phase of the three-phase transformer is connected with the corresponding alternating current system transmission line, the other end of the secondary side winding of each phase of the three-phase transformer is connected with the voltage regulating circuit, and the high potential output end of the voltage regulating circuit of the corresponding phase secondary side of the three-phase transformer is connected with the corresponding alternating current system transmission.
The technical scheme of the invention has the following advantages:
1. the voltage regulating transformer provided by the invention has the advantages that the secondary side winding of the transformer is connected with at least one voltage regulating circuit, the voltage of the output end of the voltage regulating circuit is adjusted by changing the on-off state of the switch module, and the amplitude of the voltage of the output end when the voltage regulating winding is completely connected into the transformer is changed, so that multi-gear voltage regulation is realized, and the voltage amplitude of a power transmission line of an alternating current system is controlled.
2. According to the power flow control system provided by the invention, on the basis of the voltage regulating transformer, the converter and the primary side of the transformer are introduced to be connected in parallel to obtain energy, the output end of the converter is connected in series with the secondary side of the transformer, and the parallel reactive compensation of an alternating current system and the control of the voltage amplitude and the phase of a transmission line of the alternating current system are realized by controlling the operation state of the converter, so that the power flow control capability of the alternating current system is enhanced; when the regulating transformer is a three-phase transformer, the current converter can be a single-phase transformer or a three-phase transformer, and when the regulating transformer is a single-phase transformer, the current converter can be a single-phase transformer, so that the flexible adaptability of the power flow control system is improved; the controller controls the running state of the current converter, so that the stability of the power flow control system and the power flow control capability of the power flow control system are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic diagram of a specific example of a voltage regulating transformer according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a specific example of a voltage regulating circuit provided in an embodiment of the present invention;
FIG. 3 is a schematic diagram of a specific example of a bypass switch module provided by an embodiment of the invention;
FIG. 4 is a schematic diagram of a specific example of a power flow control system according to an embodiment of the invention;
fig. 5 shows a voltage regulation range of the voltage regulating transformer and the inverter according to the embodiment of the present invention;
fig. 6 is a schematic diagram of another specific example of the voltage regulating circuit according to the embodiment of the present invention;
fig. 7 is a schematic diagram of another specific example of the power flow control system provided by the embodiment of the invention;
fig. 8 is a schematic diagram of another specific example of the power flow control system according to the embodiment of the invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. 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.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be communicated with each other inside the two elements, or may be wirelessly connected or wired connected. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example 1
An embodiment of the present invention provides a voltage regulating transformer 1, which is applied to an occasion where voltage regulation needs to be performed on a power transmission line, as shown in fig. 1, and includes: a transformer 11 and at least one voltage regulating circuit 12.
In the embodiment of the invention, the primary side winding of the transformer is connected with an alternating current system, one end of the secondary side winding of the transformer is connected with at least one voltage regulating circuit in series, and the other end of the secondary side winding is connected with the alternating current system. The voltage regulating circuit comprises at least one switch module, and the output voltage of the voltage regulating circuit is controlled by controlling the on-off state of the switch module, wherein the primary side of the transformer can be a primary side or a secondary side, and the secondary side of the transformer is an opposite side of the primary side.
The transformer in fig. 1 is a single-phase transformer, a primary side of which is connected to a single-phase transmission line of an ac system, one end of a secondary winding (one end of a conventional winding) of which is connected to at least one series-connected voltage regulating circuit (fig. 2 illustrates that one end of the secondary winding is connected to two series-connected voltage regulating circuits), and the other end of the conventional winding is connected to a corresponding phase transmission line of the ac system.
When the transformer is a three-phase transformer, the primary side of the three-phase transformer is connected with an alternating current system, one end of each phase of winding (one end of the conventional winding) on the secondary side of the three-phase transformer is connected with at least one voltage regulating circuit, and the other end of each phase of the conventional winding on the secondary side of the three-phase transformer is connected with a corresponding phase of power transmission line of the alternating current system.
As shown in fig. 2, the voltage regulating circuit includes: a voltage regulating winding 121, two output terminals and four switch modules 122. One ends of the first switch module S1 and the third switch module S3 are connected to one end of the voltage regulating winding, the other end of the first switch module S1 and one end of the second switch module S2 are connected to a first connection point, and a first output end is led out at the first connection point, the other end of the third switch module S3 and one end of the fourth switch module S4 are connected to a second connection point, and a second output end is led out at the second connection point, and the other end of the second switch module S2 and the other end of the fourth switch module S4 are both connected to the other end of the voltage regulating winding.
Fig. 2 shows a voltage regulating circuit comprising a voltage regulating winding and four controllable switch modules, the voltage regulating circuit comprising two output terminals, the voltage regulating circuits being connected in series via the output terminals. In fig. 2, four controllable switch modules S1, S2, S3, and S4 form an H-bridge structure, each controllable switch module may be composed of thyristors connected in anti-parallel, or a bidirectional IGBT and its anti-parallel diode connected in series to the top, and the switch module in fig. 2 is composed of a bidirectional IGBT and its anti-parallel diode, which is only by way of example and not limited thereto.
It should be noted that the number of the voltage regulating circuits and the number of turns of the voltage regulating windings connected in series with the conventional winding on the secondary side of the transformer can be set according to actual conditions, and when the conventional winding on the secondary side of the transformer is connected with a plurality of voltage regulating circuits, the number of turns of each voltage regulating winding can be different.
In fig. 2, one ends of S1 and S3 are connected to a first end of the regulating winding, and the other end of S1 is connected to one end of S2, and then are connected together and led out of a first output end; the other end of the S3 is connected with one end of the S4, and then the other ends of the S2 and the S4 are connected with the second end of the regulating winding together and lead out of a second output end.
It should be noted that, in the embodiment of the present invention, the number of the switch modules may be not only 4, but also may be other numbers, the plurality of switch modules may not only form one H-bridge structure, and meanwhile, according to the practical situation of the voltage regulating transformer in the application field, the plurality of switch modules may form a plurality of H-bridge structures, or the switch modules are connected to the first end, the second end, and the self-coupling output end of the voltage regulating winding, and the on-off state of the switch modules may be changed, so that the voltage regulating winding is completely connected in the forward direction, or connected in the reverse direction, or connected in the incomplete forward direction, or connected in the incomplete reverse direction, to the secondary winding of the transformer, thereby changing the total voltage output after.
In a specific embodiment, the voltage regulating transformer further comprises: the bypass switch module is used for rapidly cutting off all the voltage regulating circuits when any one voltage regulating circuit is connected in parallel, as shown in fig. 3, two ends of the bypass switch module are respectively connected with two output ends of the plurality of voltage regulating circuits after being connected in series, and one end of the bypass switch module is grounded. The bypass switch module in fig. 3 is a controllable thyristor switch for fast bypassing of a fault point, and may further include a mechanical switch for reliable bypassing of a fault point; and the lightning arrester is used for overvoltage protection between terminals. When the voltage regulating circuit is positioned at the low potential end of the transformer, one end of the bypass switch module can be directly grounded, so that the transformer has a stable and reliable grounding point when the bypass switch module is conducted.
In the embodiment of the invention, the output voltage amplitudes of the two output ends of the transformer after all the voltage regulating windings are connected to the secondary side of the transformer can be changed by changing the number of turns of the voltage regulating windings.
In the embodiment of the invention, when the voltage regulating transformer comprises a transformer and a voltage regulating circuit, the voltage regulating circuit is connected with the secondary side winding of the transformer in series, and the output voltages of two output ends of the voltage regulating circuit are three-level voltages by controlling the on-off state of the switch module.
According to the embodiment of the invention, the on-off state of the switch module in the H-bridge structure is controlled, so that the module can output three states of forward winding voltage, reverse winding voltage and zero voltage. As shown in fig. 2, when the primary side and the secondary side of the transformer both flow into the winding from the same name end, assuming that the voltage regulating winding is connected to the transformer in the forward direction, the voltage between the first output end and the second output end is U1, when the voltage regulating winding is connected to the transformer in the reverse direction, the voltage between the first output end and the second output end is-U1, the voltage between the two ends of the conventional winding on the secondary side of the transformer is U, and the control mode of the voltage regulating circuit is as follows:
firstly, switching on of S1 and S4 and switching off of S2 and S3 are controlled, so that the forward voltage of the voltage regulating winding is output between the first output end and the second output end of the voltage regulating circuit, and the voltage output after the conventional winding of the transformer is connected with the voltage regulating circuit in series is U + U1;
secondly, by controlling the conduction of S2 and S3 and the disconnection of S1 and S4, the negative voltage of the voltage regulating winding is output between the first output end and the second output end of the voltage regulating circuit, and the voltage output after the conventional winding of the transformer is connected with the voltage regulating circuit in series is U-U1;
and thirdly, controlling the conduction of S1 and S3, or when S2 and S4 are conducted, the voltage of the voltage regulating winding output between the first output end and the second output end of the voltage regulating circuit is 0, and the voltage output after the conventional winding of the transformer is connected with the voltage regulating circuit in series is U.
In the embodiment of the invention, when the voltage regulating transformer comprises a transformer and two voltage regulating circuits, the two voltage regulating circuits are connected in series and then are connected in series with the secondary side winding of the transformer, and the output voltage of two output ends of the two voltage regulating circuits after being connected in series is nine-level voltage by controlling the on-off state of the switch module and the on-off state of the switch module.
As shown in fig. 1, when the conventional winding on the secondary side of the transformer is connected to two voltage regulating circuits, the two voltage regulating circuits form a double H-bridge structure, assuming that the voltage at the two ends of the conventional winding on the secondary side of the transformer is U, when the voltage regulating circuit a in the two voltage regulating circuits is connected to the transformer in the forward direction, the voltage between the first output end and the second output end of the voltage regulating circuit a is U1, and when the voltage regulating winding is connected to the transformer in the reverse direction, the voltage between the first output end and the second output end of the voltage regulating circuit a is-U1, and then the voltage between the first output end and the second output end of the voltage regulating circuit a is U1, -U1, 0 by changing the on-off state of the switch; when the B voltage regulating circuit is connected with the transformer in the forward direction, the voltage between the first output end and the second output end of the B voltage regulating circuit is U2, when the voltage regulating winding is connected with the transformer in the reverse direction, the voltage between the first output end and the second output end of the B voltage regulating circuit is-U2, and the voltage between the first output end and the second output end of the B voltage regulating circuit is U2, -U2 and 0 by changing the on-off state of the switch modules in the two voltage regulating circuits; the two output ends of the two voltage regulating circuits after being connected in series can obtain the voltage output by the two voltage regulating circuits after being connected in series, and the voltage output by the two voltage regulating circuits can be U1+ U2, U1, U1-U2, U2, U, -U2, - (U1-U2), - (U1 and- (U1+ U2).
Further, when the voltages between the first output end and the second output end of the voltage regulating circuit a of the two voltage regulating circuits shown in fig. 1 are U1, -U1, 0, and the voltages between the first output end and the second output end of the voltage regulating circuit B of the two voltage regulating circuits are 3U1, -3U1, 0, the output voltage of the transformer secondary side conventional winding connected in series with the two voltage regulating circuits can be continuously regulated between nine levels of voltages, and the output state of the double H-bridge multi-level voltage output combination is shown in the following table.
Figure BDA0002542308150000111
In the embodiment of the invention, when the voltage regulating transformer comprises the transformer and three voltage regulating circuits, the three voltage regulating circuits are connected in series and then are connected in series with the secondary side winding of the transformer, and the output voltages of two output ends of the three voltage regulating circuits after being connected in series are twenty-seven-level voltages by controlling the on-off state of the switch module and the on-off state of the switch module.
When the voltage regulating transformer comprises three voltage regulating circuits, the voltage at two ends of a conventional winding of the secondary side of the transformer is assumed to be U, when an A voltage regulating circuit in the three voltage regulating circuits is connected to the transformer in a forward direction, the voltage between a first output end and a second output end of the A voltage regulating circuit is U1, when the voltage regulating winding is connected to the transformer in a reverse direction, the voltage between the first output end and the second output end of the A voltage regulating circuit is-U1, and the voltage between the first output end and the second output end of the A voltage regulating circuit is U1, -U1 and 0 by changing the on-off state of a switch module in the two voltage regulating circuits; when the B voltage regulating circuit is connected with the transformer in the forward direction, the voltage between the first output end and the second output end of the B voltage regulating circuit is U2, when the voltage regulating winding is connected with the transformer in the reverse direction, the voltage between the first output end and the second output end of the B voltage regulating circuit is-U2, and the voltage between the first output end and the second output end of the B voltage regulating circuit is U2, -U2 and 0 by changing the on-off state of the switch modules in the two voltage regulating circuits; when the C voltage regulating circuit is connected with the transformer in the forward direction, the voltage between the first output end and the second output end of the C voltage regulating circuit is U3, when the voltage regulating winding is connected with the transformer in the reverse direction, the voltage between the first output end and the second output end of the C voltage regulating circuit is-U3, and the voltage between the first output end and the second output end of the C voltage regulating circuit is U3, -U3 and 0 by changing the on-off state of the switch modules in the two voltage regulating circuits; the two output ends of the three voltage regulating circuits after being connected in series can obtain the voltage output by the three voltage regulating circuits after being connected in series, which can be U + U + U, U + U-U, U + U, U-U, U + U, U-U, 0, - (U + U + U), - (U + U-U), - (U + U), - (U-U), - (U + U-U), - (U-U-U), - (U + U), - (U-U), -U, or-U, therefore, by changing the on-off state of the switch modules in the three voltage regulating circuits, the voltage output after the conventional winding on the secondary side of the transformer is connected with the three voltage regulating circuits in series can be rapidly switched among twenty-seven levels of voltage.
When the number of voltage regulating circuit was three and above, can change the voltage amplitude of two output terminals behind the transformer of whole access of voltage regulating winding through the number of turns that changes every voltage regulating winding to realize more multistage voltage regulation, for example: when the number of the voltage regulating circuits is three, the voltage amplitude proportion of two output ends of each voltage regulating winding after all the voltage regulating windings are connected into the transformer can be 1: 1: 1, or 1:2:4, so that more voltages can be regulated. Taking the number of the voltage regulating circuits as 3 as an example, when the voltage regulating windings are all connected into the transformer, the voltage amplitude ratio of the two output ends is 1:2:4, when the minimum voltage amplitude of the two output ends of the voltage regulating windings after all the voltage regulating windings are connected to the transformer is U, after the three voltage regulating circuits are connected in series, the total output voltage can be 15 grades including 7U, 6U, 5U, 4U, 3U, 2U, U, 0, -U, 2U, 3U, 4U, 5U, 6U and 7U; when the voltage amplitude ratios of the two output ends of the voltage regulating winding after all the voltage regulating windings are connected into the transformer are 1: 3: 9, when the minimum voltage amplitude of the two output ends of the transformer to which all the voltage regulating windings are connected is U, then when the three voltage regulating circuits are connected in series, the total output voltage can be 27 levels including 13U, 12U, 11U, 10U, 9U, 8U, 7U, 6U, 5U, 4U, 3U, 2U, 1U, 0, -1U, -2U, -3U, -4U, -5U, -6U, -7U, -8U, -9U, -10U, -11U, -12U and 13U. Therefore, it can be known from the above that, when the transformer is connected in series with more voltage regulating circuits, and the voltage amplitudes of the two output ends of the voltage regulating circuit after all the voltage regulating windings of the voltage regulating circuit are connected to the transformer are more graded, the transformer connected in series with the voltage regulating circuit can output more graded voltages.
According to the voltage regulating transformer provided by the embodiment of the invention, the secondary side winding of the transformer is connected with at least one voltage regulating circuit, the voltage of the output end of the voltage regulating circuit is adjusted by changing the on-off state of the switch module, and the amplitude of the voltage of the output end when the voltage regulating winding is completely connected into the transformer is changed, so that multi-gear voltage regulation is realized, and the voltage amplitude of a transmission line of an alternating current system is controlled.
Example 2
The embodiment of the invention provides a power flow control system, which is applied to occasions needing power flow control on an alternating current system, and comprises the following components: the power supply comprises a controller 2, at least one current converter 3 and a regulating transformer 1 of the embodiment 1, wherein the regulating transformer can be a single-phase regulating transformer or a three-phase regulating transformer, and when the regulating transformer is a single-phase transformer and the current converter is a single-phase current converter, one regulating transformer and one current converter are combined and then connected into a one-phase power transmission line of an alternating current system; when the regulating transformer is a three-phase transformer and the current converter is a single-phase current converter, a power flow control system formed by connecting one regulating transformer with three current converters is connected to an alternating current system power transmission line; when the regulating transformer is a three-phase transformer and the current converter is a three-phase current converter, a power flow control system formed by connecting one regulating transformer and one current converter is connected in the power transmission line of the alternating current system. Fig. 4 shows a case where the regulating transformer is a single-phase transformer, the inverter is a single-phase inverter, and the regulating transformer includes two regulating circuits, and the inverter includes two single-phase inverting units, which is only an example and not a limitation.
The input side of the converter is connected with the primary side winding of the regulating transformer, the output side of the converter is connected with the output end of the regulating circuit on the secondary side of the regulating transformer, and the converter is used for regulating the voltage amplitude and the phase of the alternating current system.
If the regulating transformer is connected in series in the alternating current system independently, the amplitude of the alternating current voltage can be changed, but the phase of the alternating current voltage cannot be changed.
The controller is installed on an AC system power line and used for collecting the voltage and current of an installation point, a node in a preset adjacent range and a branch, or receiving a superior dispatching instruction and changing the voltage and the current of the AC system by coordinating the amplitude and the phase of the output voltage of the voltage regulating circuit and the current converter.
The controller is used for collecting voltage and current of an installation point or a nearby node (the node can comprise a balance node, a PQ node, a PV node and the like) and a branch circuit, load flow calculation is carried out by using the voltage and the current, and when the load flow calculation is abnormal, the voltage and the load flow of the alternating current system can be changed by controlling the output voltage amplitude and the phase of a current converter at an abnormal place and combining the output voltage amplitude of the voltage regulating transformer.
In an embodiment, as shown in fig. 4, when the voltage regulating transformer is a single-phase transformer, one end of the primary winding of the single-phase transformer is connected to any one phase transmission line of the ac system, the other end and the self-coupled output end of the primary winding of the single-phase transformer are connected to the input side of the inverter, and one end of the output side of the inverter is connected to the output end of the voltage regulating circuit on the secondary side of the single-phase transformer.
When the regulating transformer is a single-phase transformer, the converter is a single-phase converter, the input side of the converter is connected with the primary side of the regulating transformer in parallel to obtain energy, so that the converter is an active converter, the output side of the converter is connected with the output end of a regulating circuit at the low potential end of the secondary side of the regulating transformer, and one regulating transformer and one converter are combined and then connected into a one-phase power transmission circuit of an alternating current system.
The conventional secondary winding of the transformer in the embodiment of the invention is not only connected in series with at least one voltage regulating module, but also connected in series with a current converter at the low-voltage output end of the voltage regulating module, the current converter is at least composed of two current converter units sharing a bus, at least one current converter unit is connected in parallel with the transformer winding for energy acquisition to provide dynamic reactive compensation for a system, the voltage level of a node is stabilized, alternating current output voltage output by the alternating current side of the current converter unit at the output side of the current converter is connected in series with the output end of the voltage regulating circuit, the current converter has the capability of quickly regulating the amplitude and phase of low-capacity voltageThe voltage regulation range of the two-stage type on-load voltage regulation and active converter matched with the rapid power flow regulation capacity is shown in figure 5, wherein A is the output voltage amplitude of the power flow control system, and U is the output voltage amplitude of the power flow control systemtapAnd outputting a voltage vector for the power flow control system.
In one embodiment, the power flow control system further includes: each voltage regulating circuit and each current converter are connected with a bypass switch in parallel, and the bypass switch module is used for rapidly cutting off a fault point when any one voltage regulating circuit or current converter has a fault; or the output end of the voltage regulating circuit is connected with the current converter through a bypass switch module, and the bypass switch module is used for cutting off a current loop of the voltage regulating circuit and the current converter when the voltage regulating circuit or the current converter fails.
As shown in fig. 6, the output end of the voltage regulating circuit is connected with the current converter through a bypass switch module 4, and the bypass switch module is used for cutting off a current loop of the voltage regulating circuit and the current converter when the voltage regulating circuit or the current converter fails. The specific structure of the bypass switch module is shown in fig. 3, the bypass switch module in fig. 3 is a controllable thyristor switch and is used for quickly bypassing a fault point, and in addition, the bypass switch module can also comprise a mechanical switch and is used for reliably bypassing the fault point; and the lightning arrester is used for overvoltage protection between terminals. When the voltage regulating circuit is positioned at the low potential end of the transformer, one end of the bypass switch module can be directly grounded, so that the transformer has a stable and reliable grounding point when the bypass switch module is conducted. In addition, the voltage regulating circuit in the voltage regulating transformer in the power flow control system is connected in parallel with the bypass switch module in a specific connection manner as shown in fig. 3.
In one embodiment, when the regulating transformer is a three-phase transformer and the inverter is a single-phase inverter, the self-coupled output terminal of the primary winding of each phase of the three-phase transformer is connected to one input terminal of one inverter, the other input terminals of the three inverters are connected to each other, and one output terminal of each inverter is connected to the output terminal of the regulating circuit of the secondary side of the corresponding phase of the three-phase transformer.
When the regulating transformer is a three-phase transformer and the converter is a single-phase converter, each phase on the primary side of the three-phase transformer is connected with the input side of the converter, one converter is composed of at least two single-phase converter units connected back to back, the single-phase converter units can be converter circuits such as a full-bridge converter circuit and a half-bridge converter circuit, one end of the AC side of the single-phase converter unit on the input side of each converter is connected with the phase on the primary side of the transformer in parallel for energy acquisition, the other end of the AC side of the single-phase converter unit on the input side of each converter is connected with each other to form a neutral point, the AC side output voltage of the AC side of one converter unit on the output side of each converter is connected with the output end of the regulating circuit of the corresponding phase on the secondary side of the three-phase transformer and, the output of the voltage regulating circuit is connected to the ac system line.
In an embodiment, as shown in fig. 7, the power flow control system further includes:
and when the regulating transformer is a three-phase transformer and the converter is a three-phase converter, the self-coupled output end of the primary side winding of each phase of the three-phase transformer is correspondingly connected with each input side of the converter, each phase of the output side of the converter is connected with one end of the primary side winding of one additional transformer, the other end of the primary side winding of each additional transformer is interconnected, one end of the secondary side winding of each additional transformer is respectively connected with the low potential output end or the high potential output end of the regulating circuit of the secondary side of the corresponding phase of the three-phase transformer, and the other ends of the secondary side.
When the regulating transformer is a three-phase transformer and the converter is a three-phase converter, the converter is composed of at least two three-phase converter units connected back to back, and the three-phase converter units can be a three-phase rectifying circuit or a three-phase inverting circuit. As shown in fig. 7, the primary side of the three-phase transformer is connected in parallel to the ac system transmission line, and the three-phase secondary side incoming line ends of the three-phase transformer are respectively connected in series with the conventional winding, the voltage regulating circuit of each phase and the adjustable ac voltage output by the output side of the inverter.
When one end of the secondary side winding of each additional transformer is respectively connected with the low potential output end of the voltage regulating circuit of the corresponding phase secondary side of the three-phase transformer, one end of the secondary side winding of each phase of the three-phase transformer is connected with the corresponding alternating current system power transmission line, the other end of the secondary side winding of each phase of the three-phase transformer is connected with the voltage regulating circuit, and the high potential output end of the voltage regulating circuit of the corresponding phase secondary side of the three-phase transformer is connected with the corresponding alternating current.
The three-phase ac terminal of the input side of the three-phase current converter is connected in parallel with the transformer to perform dynamic reactive compensation on the system node, the three-phase ac voltage output by the output side of the three-phase current converter is connected to the primary side of the additional transformer, the additional transformer is an additional three-phase transformer, as shown in fig. 7, the secondary winding of the additional transformer has a three-phase structure and has 6 ports, the three-phase ac voltage output by the current converter is converted into three single-phase voltages to be connected with the high potential output terminal or the low potential output terminal of the corresponding phase of the three-phase secondary side of the three-phase transformer, fig. 7 shows that the additional transformer is connected with the low potential output terminal, when one end of the secondary side of the additional transformer is.
As shown in fig. 8, when one end of the secondary side winding of each additional transformer is connected to the high-potential output end of the voltage regulating circuit on the secondary side of the corresponding phase of the three-phase transformer, one end of the secondary side winding of each phase of the three-phase transformer is connected to ground, the other end of the secondary side winding of the corresponding phase of the three-phase transformer is connected to the secondary side winding of the corresponding additional transformer, the low-potential output end of the voltage regulating circuit on the secondary side of the corresponding phase of the three-phase transformer is connected to the corresponding transmission line of the ac system, and when one end of the secondary side of the. The secondary sides of the additional transformers in fig. 8 are interconnected in a delta connection, but may also be interconnected in a star connection.
According to the power flow control system provided by the embodiment of the invention, on the basis of the voltage regulating transformer, the converter and the primary side of the transformer are introduced to be connected in parallel to obtain energy, the output end of the converter is connected in series with the secondary side of the transformer, and the running state of the converter is controlled, so that the parallel reactive compensation of an alternating current system is realized, the voltage amplitude and the phase of a transmission line of the alternating current system are controlled, and the power flow control capability of the alternating current system is enhanced; when the regulating transformer is a three-phase transformer, the current converter can be a single-phase transformer or a three-phase transformer, and when the regulating transformer is a single-phase transformer, the current converter can be a single-phase transformer, so that the flexible adaptability of the power flow control system is improved; the controller controls the running state of the current converter, so that the stability of the power flow control system and the power flow control capability of the power flow control system are improved.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.

Claims (14)

1. A step transformer, comprising: a transformer and at least one voltage regulation circuit, wherein,
the transformer comprises a primary side winding, a secondary side winding and a transformer, wherein the primary side winding of the transformer is connected with an alternating current system, one end of the secondary side winding of the transformer is connected with at least one voltage regulating circuit in series, and the other end of the secondary side winding of the transformer is connected with the alternating current system;
the voltage regulating circuit comprises at least one switch module, and the output voltage of the voltage regulating circuit is controlled by controlling the on-off state of the switch module.
2. The voltage regulating transformer of claim 1, wherein the voltage regulating circuit comprises: a voltage regulating winding, two output ends and four switch modules, wherein,
one end of the first switch module and one end of the third switch module are connected with one end of the voltage regulating winding, the other end of the first switch module and one end of the second switch module are connected with the first connecting point, a first output end is led out from the first connecting point, the other end of the third switch module and one end of the fourth switch module are connected with the second connecting point, a second output end is led out from the second connecting point, and the other end of the second switch module and the other end of the fourth switch module are both connected with the other end of the voltage regulating winding.
3. The voltage regulating transformer according to claim 2, wherein when the secondary winding of the transformer is connected to a plurality of voltage regulating circuits, each voltage regulating circuit is connected in series with the other voltage regulating circuit through two output terminals.
4. The voltage regulating transformer according to any one of claims 1 to 3, wherein the transformer is a single-phase transformer or a three-phase transformer.
5. The voltage regulating transformer according to claim 3, wherein when the voltage regulating transformer comprises a transformer and a voltage regulating circuit, the voltage regulating circuit is connected in series with the secondary winding of the transformer, and the output voltage of the two output ends of the voltage regulating circuit is a three-level voltage by controlling the on-off state of the switch module.
6. The voltage regulating transformer according to claim 3, wherein when the voltage regulating transformer comprises a transformer and two voltage regulating circuits, the two voltage regulating circuits are connected in series and then connected in series with the secondary winding of the transformer, and the output voltage of the two output ends of the two voltage regulating circuits after being connected in series is nine-level voltage by controlling the on-off state of the switch module and the on-off state of the switch module.
7. The voltage regulating transformer according to claim 3, wherein when the voltage regulating transformer comprises a transformer and three voltage regulating circuits, the three voltage regulating circuits are connected in series with the secondary winding of the transformer, and the output voltage of two output ends of the three voltage regulating circuits after being connected in series is twenty-seven levels by controlling the on-off state of the switch module and the on-off state of the switch module.
8. A power flow control system comprising the step-up transformer of any one of claims 1 to 7, further comprising: a controller and at least one inverter, wherein,
the input side of the converter is connected with the primary side winding of the regulating transformer, the output side of the converter is connected with the output end of the regulating circuit on the secondary side of the regulating transformer, and the converter is used for regulating the amplitude and the phase of the voltage of the alternating current system;
the controller is installed on an AC system power line and used for collecting the voltage and current of an installation point, a node in a preset adjacent range and a branch, or receiving a superior dispatching instruction and changing the voltage and the current of the AC system by coordinating the amplitude and the phase of the output voltage of the voltage regulating circuit and the current converter.
9. The power flow control system of claim 8, further comprising:
the bypass switch module is used for rapidly cutting off a fault point when any one of the voltage regulating circuit or the current converter has a fault; or the output end of the voltage regulating circuit is connected with the current converter through a bypass switch module, and the bypass switch module is used for cutting off a current loop of the voltage regulating circuit and the current converter when the voltage regulating circuit or the current converter fails.
10. The power flow control system according to claim 8, wherein when the voltage regulating transformer is a single-phase transformer, one end of the primary winding of the single-phase transformer is connected to any one phase transmission line of an ac system, the other end and the self-coupled output end of the primary winding of the single-phase transformer are connected to the input side of the converter, and one end of the output side of the converter is connected to the output end of the voltage regulating circuit on the secondary side of the single-phase transformer.
11. The power flow control system of claim 8, wherein when the regulating transformer is a three-phase transformer and the inverters are single-phase inverters, the self-coupled output terminal of the primary winding of each phase of the three-phase transformer is connected to one input terminal of one inverter, the other input terminals of the three inverters are connected to each other, and one output terminal of each inverter is connected to the output terminal of the regulating circuit of the secondary side of the corresponding phase of the three-phase transformer.
12. The power flow control system of claim 8, further comprising:
at least one additional transformer, work as the regulating transformer is three-phase transformer, when the transverter is three-phase transverter, the auto coupling output of every looks primary winding of three-phase transformer all is connected with every correspondence of transverter input side, every looks of transverter output side all is connected with an additional transformer primary winding one end, every additional transformer primary winding's other end interconnection, every additional transformer secondary side winding one end respectively with the voltage regulating circuit low potential output or the high potential output of the corresponding looks secondary side of three-phase transformer be connected, the other end interconnection of three additional transformer secondary side winding.
13. The power flow control system of claim 12,
when one end of the secondary side winding of each additional transformer is respectively connected with the high-potential output end of the voltage regulating circuit of the corresponding secondary side of the three-phase transformer, one end of the secondary side winding of each phase of the three-phase transformer is connected with the ground, the other end of the secondary side winding of each phase of the three-phase transformer is connected with the secondary side winding of the corresponding additional transformer, and the low-potential output end of the voltage regulating circuit of the corresponding secondary side of the three-phase transformer.
14. The power flow control system of claim 12,
when one end of the secondary side winding of each additional transformer is respectively connected with the low potential output end of the voltage regulating circuit of the corresponding phase secondary side of the three-phase transformer, one end of the secondary side winding of each phase of the three-phase transformer is connected with the corresponding alternating current system power transmission line, the other end of the secondary side winding of each phase of the three-phase transformer is connected with the voltage regulating circuit, and the high potential output end of the voltage regulating circuit of the corresponding phase secondary side of the three-phase transformer is connected with the corresponding alternating current.
CN202010550443.3A 2020-06-16 2020-06-16 Voltage regulating transformer and power flow control system Pending CN111525583A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112821408A (en) * 2021-01-09 2021-05-18 华北电力大学（保定） Bidirectional voltage self-adaptive adjustment method for electromagnetic series transmission line
CN112821407A (en) * 2021-01-09 2021-05-18 华北电力大学（保定） Single-phase or three-phase electromagnetic series-type bidirectional voltage regulation topological circuit
CN113497447A (en) * 2021-01-09 2021-10-12 华北电力大学（保定） Three-phase electromagnetic type series-connection type transmission line bidirectional voltage self-adaptive adjusting device
WO2023241074A1 (en) * 2022-06-17 2023-12-21 国网智能电网研究院有限公司 Flexible power transformer

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112821408A (en) * 2021-01-09 2021-05-18 华北电力大学（保定） Bidirectional voltage self-adaptive adjustment method for electromagnetic series transmission line
CN112821407A (en) * 2021-01-09 2021-05-18 华北电力大学（保定） Single-phase or three-phase electromagnetic series-type bidirectional voltage regulation topological circuit
CN113497447A (en) * 2021-01-09 2021-10-12 华北电力大学（保定） Three-phase electromagnetic type series-connection type transmission line bidirectional voltage self-adaptive adjusting device
CN113497447B (en) * 2021-01-09 2024-01-09 华北电力大学（保定） Three-phase electromagnetic type series-connection type power transmission line bidirectional voltage self-adaptive adjusting device
CN112821407B (en) * 2021-01-09 2024-01-09 华北电力大学（保定） Single-phase or three-phase electromagnetic series-type bidirectional voltage regulation topological circuit
CN112821408B (en) * 2021-01-09 2024-01-09 华北电力大学（保定） Electromagnetic type series type transmission line bidirectional voltage self-adaptive adjusting method
WO2023241074A1 (en) * 2022-06-17 2023-12-21 国网智能电网研究院有限公司 Flexible power transformer

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