CN112615388A - Medium-high voltage power supply quality unified regulator containing distributed energy storage units - Google Patents
Medium-high voltage power supply quality unified regulator containing distributed energy storage units Download PDFInfo
- Publication number
- CN112615388A CN112615388A CN202011476258.0A CN202011476258A CN112615388A CN 112615388 A CN112615388 A CN 112615388A CN 202011476258 A CN202011476258 A CN 202011476258A CN 112615388 A CN112615388 A CN 112615388A
- Authority
- CN
- China
- Prior art keywords
- phase
- energy storage
- mmc
- voltage
- converter
- 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.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
-
- 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
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
- H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
- H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
- H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
-
- 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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
- H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
-
- 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
- Y02E40/10—Flexible AC transmission systems [FACTS]
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Rectifiers (AREA)
Abstract
The invention discloses a medium-high voltage power supply quality unified regulator containing a distributed energy storage unit, which comprises an alternating current power grid access end, an input switch, a phase-shifting transformer, n three-phase rectifiers, an MMC (modular multilevel converter), an output switch, a load access end and a bypass switch, wherein six bridge arms of the MMC comprise cascaded composite sub-modules SM, and the composite sub-modules SM comprise MMC sub-modules and energy storage modules. The invention can greatly reduce the number of the windings of the phase-shifting transformer and the three-phase rectifiers, and the energy storage module can independently supply power for the load through a cascade bridge formed by three upper bridge arms and three lower bridge arms of the MMC converter, thereby improving the transmission efficiency of the system.
Description
Technical Field
The invention belongs to the technical field of power transmission and distribution of a power system, and particularly relates to a medium-high voltage power supply quality unified regulator comprising distributed energy storage units, which is used for ensuring safe and reliable power supply of users.
Background
With the rapid development of global industrialization and informatization, a high-power supply quality comprehensive improvement system is increasingly and widely applied to large-capacity important loads with excellent power supply protection performance. In the conventional high-Power supply quality comprehensive improvement System, a cascaded H-bridge type medium-voltage Uninterruptible Power Supply (UPS) including a phase-shifting transformer is widely concerned with the advantages of small network side harmonic, high modularization degree, large System capacity, good redundancy characteristic and the like. The topological operation principle is that each secondary winding of the phase-shifting transformer forms direct-current voltage input of each submodule of the cascade H bridge after three-phase rectification, and three-phase load voltage is output through the three-phase cascade H bridge, so that the single-machine capacity of the system is effectively improved, and the problem of current and voltage equalization caused by the parallel connection of a plurality of machines in the prior art is solved. When the off-grid energy storage battery is powered, the system outputs three-phase load voltage through the cascaded H-bridge, so that the running loss of the system is low, and the power supply time of the energy storage battery is ensured.
It is worth noting that the direct current voltage input of each cascaded H bridge submodule in the three phases of the topology needs a secondary winding of a phase-shifting transformer, a three-phase rectifier and an energy storage device, so that the number of the secondary winding and the three-phase rectifier is large, the system size is large, the cost is high, and the system control is complex. And the output voltage quality of the cascaded H bridge and the number of the secondary windings of the phase-shifting transformer have strong correlation, so that the number of the cascaded H bridge sub-modules needs to be obviously improved for improving the output voltage quality of the cascaded H bridge, the above defects of the system are increasingly highlighted, and particularly, the requirement of the improvement of the number of the secondary windings of the phase-shifting transformer on the manufacturing process is greatly increased. It can be known from the above that the system has certain contradiction problems in the aspects of output power quality, module utilization efficiency, economy and the like, and the use is increasingly limited with the increasing load capacity of important users and the increasing requirements on power quality.
Disclosure of Invention
In order to solve the technical problems of the existing power supply quality comprehensive improvement system, the invention provides a medium-high voltage power supply quality unified regulator containing distributed energy storage units, which greatly reduces the number of secondary windings and three-phase rectifiers of a phase-shifting transformer, effectively improves the system modularization degree and reliability, effectively reduces the influence of direct current of an MMC converter on each bridge arm, and improves the system power transmission efficiency.
The technical scheme for realizing the functions is as follows:
a medium-high voltage power supply quality unified regulator containing a distributed energy storage unit comprises an alternating current power grid access end, an input switch, a phase-shifting transformer, n three-phase rectifiers, an MMC current converter, an output switch, a load access end and a bypass switch, wherein six bridge arms of the MMC current converter are all formed by cascaded composite sub-modules SM, and each composite sub-module SM comprises an MMC sub-module and an energy storage module;
the input switch is connected between the alternating current power grid access end and a primary three-phase winding of the phase-shifting transformer; the output ends of the n secondary three-phase windings of the phase-shifting transformer are connected to the alternating current input ends of the n three-phase rectifiers in a one-to-one correspondence manner; the direct current output end of the n three-phase rectifiers forms direct current voltage of another voltage class in a cascading mode, the direct current voltage anode of the another voltage class is connected to the direct current end anode of the MMC converter, the direct current voltage cathode of the another voltage class is connected to the direct current end cathode of the MMC converter, the alternating current end of the MMC converter is connected to the load access end through the output switch, and the bypass switch is connected between the alternating current power grid access end and the load access end.
Furthermore, in the n three-phase rectifiers, the positive pole of the direct current output end of the three-phase rectifier 1 is connected with the positive pole of the direct current end of the MMC converter, the negative pole of the direct current output end of the three-phase rectifier 1 is connected with the positive pole of the direct current output end of the three-phase rectifier 2, the other three-phase rectifiers are sequentially connected according to the connection method, the negative pole of the direct current output end of the direct current-to-three-phase rectifier n-1 is connected with the positive pole of the direct current output end of the three-phase rectifier n, and the negative pole of the direct current output end of the three-phase rectifier n is connected with.
Furthermore, the port of the composite submodule SM comprises a first port and a second port, the first port of the composite submodule SM is the first port of the MMC submodule, the second port of the composite submodule SM is the second port of the MMC submodule, the third port of the MMC submodule is connected with the positive electrode of the output end of the energy storage module, and the fourth port of the MMC submodule is connected with the negative electrode of the output end of the energy storage module.
Further, the MMC submodule piece in the MMC transverter bridge arm is all half-bridge submodule pieces, or all full-bridge submodule pieces, or all self-resistance submodule pieces, or all clamping double submodule pieces, or the mixed use form of above-mentioned type MMC submodule pieces, the MMC submodule piece can be parallelly connected by a plurality of above-mentioned type MMC submodule pieces according to the requirement of system capacity and constitutes to improve the biggest resistant current that the MMC transverter bridge arm flowed through, wherein, two input ports of above-mentioned type MMC submodule piece the first port, the second port of MMC submodule piece, the anodal and the energy storage electric capacity negative pole of energy storage electric capacity of above-mentioned type MMC submodule piece do not promptly be the third port, the fourth port of submodule piece MMC.
Furthermore, the port of the energy storage module comprises an output end anode of the energy storage module and an output end cathode of the energy storage module, the energy storage module is composed of an energy storage battery, the output end anode of the energy storage module is an energy storage battery anode, and the output end cathode of the energy storage module is an energy storage battery cathode; or the energy storage module consists of a DC-DC converter and an energy storage battery, the positive electrode of the output end of the energy storage module is the positive electrode of the high-voltage end of the DC-DC converter, the negative electrode of the output end of the energy storage module is the negative electrode of the high-voltage end of the DC-DC converter, the positive electrode of the low-voltage end of the DC-DC converter is connected with the positive electrode of the energy storage battery, and the negative electrode of the low-voltage end of the DC-DC converter is connected with the negative electrode of the energy storage battery.
Furthermore, the energy storage module is composed of a DC-DC converter and an energy storage battery, the DC-DC converter adopts a non-isolated DC-DC converter or an isolated DC-DC converter, and the topological type of the DC-DC converter is selected according to the capacitance voltage grade of the MMC submodule and the isolation requirement of the energy storage battery.
Furthermore, the primary three-phase winding connection of the phase-shifting transformer is star-shaped or triangular; the secondary three-phase winding connection method of the phase-shifting transformer adopts an extended connection mode of extended triangle phase shifting to achieve that the voltage of a secondary winding line leads the voltage of a primary winding line by a phase angle of-30 degrees to 30 degrees, the number n of the secondary three-phase windings is selected according to the phase-shifting pulse wave number requirement of the phase-shifting transformer, the direct-current terminal voltage of an MMC converter and the manufacturing process feasibility of the number of the secondary three-phase windings, the phase-shifting angle of the secondary three-phase windings is selected according to the phase-shifting pulse wave number requirement of the phase-shifting transformer and the number n of the secondary three-phase windings, and the pollution of system rectification to current harmonics at a grid-connected side.
Further, according to the control type of the switching device, all the n three-phase rectifiers are uncontrolled rectifiers, or all the three-phase rectifiers are half-controlled rectifiers, or all the three-phase rectifiers are full-controlled rectifiers, or the control type three-phase rectifiers are mixed for use; the direct current output ends of the n three-phase rectifiers boost direct current voltage in a cascading mode to form direct current voltage of another voltage level, and the direct current voltage of the another voltage level is the direct current end voltage of the MMC converter.
Further, the ac grid connection end is a first ac grid connection end or a second ac grid connection end, where the first ac grid connection end is the ac grid connection end to which the input switch is connected, and the second ac grid connection end is another three-phase power supply.
Further, the operation conditions of the medium-high voltage power supply quality unified regulator comprise a system grid-connected mode, an energy storage battery power supply mode and a system bypass mode, the operation conditions are switched according to the power grid condition, the system condition and the load operation requirement, wherein,
the system grid-connected mode is an operation condition when a power grid normally operates, at the moment, the input switch and the output switch are both in a closed state, and the bypass switch is in an on-off state; the method comprises the following steps that the voltage of a power grid is converted through a phase-shifting transformer, three-phase alternating-current voltage with a specific phase-shifting angle is generated on each secondary winding of the phase-shifting transformer, the three-phase alternating-current voltage is rectified through a three-phase rectifier and then is used for improving the voltage of a direct-current end in a cascading mode, the voltage of the direct-current end outputs stable three-phase alternating-current voltage of a load end through an MMC current converter, and the voltage of the load end can be kept stable;
the power supply mode of the energy storage battery is an operation working condition when the power grid fails or is continuously disturbed, at the moment, the output switch is in a closed state, and the input switch and the bypass switch are both in an open state; the direct current end of the MMC converter is equivalent to open circuit, the energy storage module in each bridge arm composite submodule SM can output load power in real time according to the state of a power grid and the voltage condition of the direct current end after cascade connection, and the uninterrupted power supply of the load is ensured through the control of six bridge arms; according to the different topologies of the MMC sub-modules adopted in the composite sub-module SM of the bridge arms of the MMC converter, the power supply mode of the energy storage battery of the system is a single power supply mode of a cascade bridge formed by three upper bridge arms of the MMC converter, or a single power supply mode of the cascade bridge formed by three lower bridge arms, or a common power supply mode of two cascade bridges formed by three upper bridge arms and three lower bridge arms.
According to the above content of the design of the invention, compared with the existing technical scheme for comprehensively improving the power supply quality, the invention can obtain the following beneficial effects:
1) the medium-high voltage power supply quality unified regulator containing the distributed energy storage units adopts a cascading mode to boost the direct current voltage output by a three-phase rectifier connected with each secondary winding in the phase-shifting transformer into direct current voltage of another voltage class, and outputs stable and reliable load voltage through an MMC converter formed by composite sub-modules SM through bridge arms. Compared with the prior art, under the condition that the system realizes the same pulse number rectification through the phase-shifting transformer, the number of the secondary winding and the three-phase rectifier of the phase-shifting transformer is reduced by two times, and the modularization degree and the system reliability are effectively improved;
2) the system of the invention removes the strong association phenomenon that the number of the cascaded H bridge submodules is equal to the number of the secondary windings of the phase-shifting transformer in the prior art through the improvement of the topological structure 1), and solves the problem that the number of the steps of the generated load voltage waveform is limited in the prior art. According to the invention, the output voltage of each three-phase rectifier can be independently designed according to the number of secondary windings so as to realize the required direct-current voltage of the MMC converter, and the type and the number of the composite sub-modules SM of each bridge arm in the MMC converter can be independently designed so as to meet the requirements of important users on the quality of electric energy;
3) when the system is in the energy storage battery mode, the system works in a cascade bridge mode formed by three upper bridge arms and three lower bridge arms in the MMC converter, so that the influence of direct current transmitted by a direct current end of the MMC converter on each bridge arm can be effectively avoided, the power transmission efficiency of the system is improved, and the power-saving time of the energy storage battery for important users is prolonged;
4) according to the schemes 1), 2) and 3), the topology has more outstanding advantages of improving the single machine capacity and the load voltage electric energy quality of the system, the single machine capacity and the voltage grade of the system can be independently designed according to an MMC converter and a three-phase rectifier, wherein bridge arms of the MMC converter and the three-phase rectifier are composed of composite sub-modules SM, and the system is high in expandability.
Drawings
Fig. 1 is a schematic structural diagram of a medium-high voltage power supply quality unified regulator including distributed energy storage units according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a delta connection of a primary winding of a phase-shifting transformer in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit according to an embodiment of the present invention;
fig. 3 is a schematic diagram of an uncontrolled rectification manner of a three-phase rectifier in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit according to an embodiment of the present invention;
fig. 4 is a schematic diagram of an energy storage module in a medium-high voltage power supply quality unified regulator with distributed energy storage units, which is composed of a DC-DC converter and an energy storage battery according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a composite submodule SM in which an MMC submodule in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit is a half-bridge submodule according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a composite submodule SM in which an MMC submodule in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit is a full-bridge submodule according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a composite submodule SM in which an MMC submodule in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit is a self-resistance submodule according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a composite submodule SM in which an MMC submodule in a medium-high voltage power supply quality unified regulator including distributed energy storage units is a clamping submodule according to an embodiment of the present invention;
fig. 9 is a schematic diagram of a power supply mode of an energy storage battery when an MMC sub-module in a medium-high voltage power supply quality unified regulator including distributed energy storage units is a half-bridge sub-module according to an embodiment of the present invention;
fig. 10 is a schematic diagram of a power supply mode of an energy storage battery when an MMC sub-module in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit is a full-bridge sub-module according to an embodiment of the present invention;
fig. 11 is a schematic diagram of a first port of a bypass switch in a medium-high voltage power supply quality unified regulator including distributed energy storage units according to another embodiment of the present invention being connected to a second ac power grid;
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the following specific examples are illustrative only and are not intended to limit the invention. In addition, the technical features related to the embodiments of the present invention may be combined with each other as long as they do not conflict with each other.
Fig. 1 is a schematic structural diagram of a medium-high voltage power supply quality unified regulator including a distributed energy storage unit according to an embodiment of the present invention, where the medium-high voltage power supply quality unified regulator includes an ac power grid access end 11, a load access end 12, an input switch 13, an output switch 14, a bypass switch 15, a phase-shifting transformer 16, n three-phase rectifiers 17, and an MMC converter 18.
The alternating current network access end 11 is connected to a primary three-phase winding of a phase-shifting transformer 16 through an input switch 13; the output ends of the n secondary three-phase windings of the phase-shifting transformer 16 are respectively connected with the alternating current input ends of the n three-phase rectifiers 17 in a one-to-one correspondence manner; the direct current output ends of the n three-phase rectifiers 17 are connected in a cascading mode to improve the direct current end voltage level and are connected to the positive electrode and the negative electrode of the direct current end of the MMC converter 18, namely the positive electrode of the direct current output end of the three-phase rectifier 1 is connected with the positive electrode of the direct current end of the MMC converter 18, the negative electrode of the direct current output end of the three-phase rectifier 1 is connected with the positive electrode of the direct current output end of the three-phase rectifier 2, the other three-phase rectifiers are sequentially connected according to the connection method, the negative electrode of the direct current output end of the direct current-to-three-phase rectifier n-1 is connected with the positive electrode of the direct current output end of the three-phase rectifier n, and the negative electrode of the; the alternating current end of the MMC converter 18 is connected to the load access end 12 through the output switch 14; the bypass switch 15 is connected between the ac grid input 11 and the load input 12.
The MMC converter 18 is composed of six bridge arms, specifically, the ports of the MMC converter 18 comprise an MMC converter direct-current end positive electrode, an MMC converter direct-current end negative electrode, an MMC converter A cross current port, an MMC converter B cross current port and an MMC converter C cross current port, every two bridge arms are respectively connected through a first port of one bridge arm and a second port of the other bridge arm to form a phase unit, through the connection, the phase units respectively comprise a first port, a second port and bridge arm port connection points, and the six bridge arms form three phase units; the first ports of the three phase units are connected together to form the positive pole of the direct current end of the MMC converter, the second ports of the three phase units are connected together to form the negative pole of the direct current end of the MMC converter, and the bridge arm port connecting points of the three phase units form the three-phase alternating current output port of the MMC converter.
Through the above connection manner, the ports of the phase units include a first port, a second port, and a bridge arm port connection point, as in the C-phase unit 182 in fig. 1, the ports of the C-phase unit 182 include a first port 1821, a second port 1823, and a bridge arm port connection point 1822, and the six bridge arms constitute three phase units; the first ports of the three phase units are connected together to form an anode 1821 of a direct-current end of the MMC converter, the second ports of the three phase units are connected together to form a cathode 1823 of the direct-current end of the MMC converter, and bridge arm port connecting points of the three phase units form an alternating-current output port of three phases of the MMC converter.
Six bridge arms of the MMC transverter 18 are composed of cascaded composite sub-modules SM181, each composite sub-module SM181 is composed of an MMC sub-module and an energy storage module, a port of each composite sub-module SM181 comprises a first port 1811 and a second port 1812, the first port 1811 of each composite sub-module SM is a first port of the MMC sub-module, the second port 1812 of each composite sub-module SM is a second port of the MMC sub-module, a third port 1813 of the MMC sub-module is connected with the positive pole of the output end of the energy storage module, and a fourth port 1814 of the MMC sub-module is connected with the negative pole of the output end of the energy storage module.
The middle-high voltage power supply quality unified regulator containing the distributed energy storage units provided by the embodiment of the invention adopts a mode of cascading the direct current ends of the three-phase rectifier 17 connected with each secondary winding of the phase-shifting transformer 16 to boost the voltage of the direct current ends, and then the voltage of the direct current ends is output as a stable load end voltage through an MMC converter 18 formed by cascading composite submodule SM on a bridge arm. Through the design of the topological structure, the number of secondary windings and three-phase rectifiers 17 of the phase-shifting transformer 16 is greatly reduced while the high-reliability power supply performance of a large-capacity user is ensured, and the system reliability and the modularization degree are effectively improved. In addition, the invention can independently design the SM type and the number of the composite sub-modules of the MMC current converter 18 according to the power quality requirement of important users, and has strong expandability. The system is characterized in that the energy storage module is installed in a composite submodule SM of the MMC converter 18, and when the energy storage battery is in a power supply mode, the system works in a cascade bridge mode formed by three upper bridge arms and three lower bridge arms in the MMC converter 18, so that the influence of direct current of the MMC converter 18 on each bridge arm is effectively reduced, and the power transmission efficiency of the system is improved.
Fig. 2 is a schematic diagram illustrating a primary winding of a phase-shifting transformer in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit according to an embodiment of the present invention is delta-connected, where the phase-shifting transformer 2 is a primary three-phase winding 20, and the primary three-phase winding 20 is selectively connected in delta-connected; the phase-shifting transformer 2 comprises n secondary three-phase windings (21, 22, 21.... or 2n), the n secondary three-phase windings are in extended connection mode of extended triangle phase shifting, the extended connection mode comprises a forward connection mode and a backward connection mode, the voltage of the secondary winding wire can lead or lag the voltage of the primary winding wire by any angle within a range of 0-30 degrees, and the phase-shifting angles of the n secondary three-phase windings can be different or partially the same.
Fig. 3 is a schematic diagram of a three-phase rectifier in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit according to an embodiment of the present invention, where the three-phase uncontrolled rectifier 3 is composed of a three-phase uncontrolled rectifier bridge 31, a voltage stabilizing capacitor 32, and a discharge resistor 33, and the three-phase rectifier adopts a three-phase uncontrolled rectification mode, which can greatly simplify system control and reduce system production cost in terms of components and control.
Fig. 4 is a schematic diagram of an energy storage module in the medium-high voltage power supply quality unified regulator including a distributed energy storage unit, where the energy storage module 4 is composed of an energy storage battery 41 and a DC-DC converter 42, a port of the energy storage module 4 includes an output terminal anode of the energy storage module and an output terminal cathode of the energy storage module, a low-voltage terminal anode of the DC-DC converter 42 is connected to an anode of the energy storage battery 41, a low-voltage terminal cathode of the DC-DC converter is connected to a cathode of the energy storage battery 41, a high-voltage terminal anode of the DC-DC converter 42 is an output terminal anode of the energy storage module 4, and a high-voltage terminal cathode of the DC-DC converter 42 is an output terminal cathode of the energy storage module 4. By adding the DC-DC converter 42 into the energy storage module 4, the voltage of the energy storage battery 41 can be better matched with the capacitance voltage of the MMC sub-module, the energy storage battery 41 has good control performance, and the DC-DC converter 42 can be selected according to the ratio of the voltage of the energy storage battery 41 to the capacitance voltage of the MMC sub-module and the system requirement.
Fig. 5, fig. 6, fig. 7, and fig. 8 are schematic diagrams of a composite submodule SM in which an MMC submodule in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit according to an embodiment of the present invention is a half-bridge submodule, a full-bridge submodule, a self-resistance submodule, and a clamping submodule, topologies of a half-bridge submodule 51, a full-bridge submodule 61, a self-resistance submodule 71, and a clamping submodule 81 may all be used as MMC submodules in six bridge arms of the MMC current converter, further, the MMC submodule of each of the six bridge arms of the MMC current converter may be a mixed form of the above-mentioned multiple types of submodules, and the MMC submodule may be formed by connecting multiple MMC submodules of the above-mentioned types in parallel according to a system capacity requirement of the present invention, so as to increase a maximum withstand current flowing through the MMC current, and the energy storage module 52 in the composite submodule SM of fig., 62. 72, 82 are each comprised of a DC-DC converter and an energy storage battery.
Fig. 9 is a schematic diagram of a power supply mode of an energy storage battery when an MMC sub-module in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit is a half-bridge sub-module according to an embodiment of the present invention, where the MMC sub-modules of three upper bridge arms 91 and three lower bridge arms 92 in an MMC current converter are half-bridge sub-modules, and the half-bridge sub-modules can output two levels, i.e., a positive level and a 0 level. Fig. 9 shows that each composite submodule in the cascaded bridge composed of three upper bridge arms 91 has the same SM type and topology connection method, that is, the MMC submodule and the energy storage battery have the same positive and negative polarities, and the bridge arm port connection point of each phase unit in the cascaded bridge composed of three upper bridge arms 91 can output a negative level and 0; similarly, each composite sub-module SM in the cascaded bridge composed of the three lower bridge arms 92 has the same type and topological connection method, and has the same connection mode as the composite sub-modules SM in the three upper bridge arms 91, so that the cascaded bridge composed of the three lower bridge arms 92 can output a positive level and 0 at the bridge arm port connection point of each phase unit. When a power grid fails or is disturbed continuously, the system is in an energy storage battery power supply mode, at the moment, an output switch 93 of the system is in a closed state, an input switch and a bypass switch of the system are in an open-close state, a direct-current end of the MMC converter is equivalent to an open circuit, in order to ensure that bridge arm port connection points of three phase units can output standard three-phase alternating-current voltage, a cascade bridge formed by three upper bridge arms 91 and a cascade bridge formed by three lower bridge arms 92 are put into operation together in a working mode shown in fig. 9, and levels output by the cascade bridge formed by the three upper bridge arms 91 and the cascade bridge formed by the three lower bridge arms 92 are matched with each other through control to output stable three-phase alternating-current voltage at a load end.
FIG. 9
The schematic diagram of the power supply mode of the energy storage battery when the MMC submodule in the medium-high voltage power supply quality unified regulator containing the distributed energy storage unit is the full-bridge submodule is shown, wherein the MMC submodules of three upper bridge arms 101 and three lower bridge arms 102 in the MMC current converter are the full-bridge submodule, and the full-bridge submodule can output three levels, namely a positive level, a 0 level and a negative level, so that a cascade bridge formed by the three upper bridge arms 101 and the three lower bridge arms 102 can output the positive level, the 0 level and the negative level at a bridge arm port connection point of each phase unit. When the system is in the energy storage battery power supply mode, the output switch 103 of the system is in a closed state, the input switch and the bypass switch of the system are both in an open state, the MMC converter can be converted into a single power supply mode of a cascade bridge formed by three upper bridge arms 101, or a single power supply mode of a cascade bridge formed by three lower bridge arms 102, or a common power supply mode of the two cascade bridges, and stable three-phase alternating-current voltage at the load end is output at the bridge arm port connection point of the three-phase unit, and fig. 10 is a schematic diagram of the single power supply mode of the cascade bridge formed by the three lower bridge arms 102.
Fig. 11 is a schematic diagram of a second ac power grid connected to a first port of a bypass switch in a medium-high voltage power supply quality unified regulator including a distributed energy storage unit according to another embodiment of the present invention, where when the system of the present invention is in a system failure or is in periodic maintenance, in order to ensure uninterrupted power supply for an important load, the system switches to connect the first port of the bypass switch 13 to a second ac power grid connection end 111 for power supply, that is, electric energy of the second ac power grid directly supplies power to the load through the bypass switch 15, and the second ac power grid connection end 111 serves as another power supply source of the important load, which may be a power supply source with higher power supply quality, and provides more stable and reliable power supply for the important load.
In the above embodiment, the input switch, the output switch and the bypass switch are three-phase switches, the three-phase switches may be ac breakers or ac contactors, and the switching action types of the three-phase switches may be three-phase linkage or split-phase operation.
The embodiment of the invention adopts a mode of cascading the direct current ends of the three-phase rectifier connected with each secondary winding of the phase-shifting transformer to boost the voltage of the direct current ends, and then the voltage of the direct current ends is output to a stable load end voltage through a Modular Multilevel Converter (MMC). By greatly improving the design of a topological structure, the number of secondary windings and three-phase rectifiers of a phase-shifting transformer is greatly reduced while the high-reliability power supply performance of a high-capacity user is ensured, the system modularization degree and the reliability are effectively improved, the type and the number of Sub-modules (SM) of the MMC converter can be independently designed according to the power quality requirement of an important user, the expandability is high, the system works in a cascade bridge mode formed by three upper bridge arms and three lower bridge arms in the MMC converter in the power supply mode of an energy storage battery, the influence of direct current of the MMC converter on each bridge arm is effectively reduced, and the power transmission efficiency of the system is improved.
The embodiments of the present invention are not limited to the above-mentioned embodiments, but the above-mentioned embodiments are only preferred embodiments of the present invention and should not be used to limit the scope of the present invention, and those skilled in the art will readily understand that any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (10)
1. A medium-high voltage power supply quality unified regulator containing a distributed energy storage unit is characterized in that a system topology comprises an alternating current power grid access end, an input switch, a phase-shifting transformer, n three-phase rectifiers, an MMC (modular multilevel converter) converter, an output switch, a load access end and a bypass switch, wherein six bridge arms of the MMC converter are all composed of cascaded composite sub-modules SM, and each composite sub-module SM comprises an MMC sub-module and an energy storage module;
the input switch is connected between the alternating current power grid access end and a primary three-phase winding of the phase-shifting transformer; the output ends of the n secondary three-phase windings of the phase-shifting transformer are connected to the alternating current input ends of the n three-phase rectifiers in a one-to-one correspondence manner; the direct current output end of the n three-phase rectifiers forms direct current voltage of another voltage class in a cascading mode, the direct current voltage anode of the another voltage class is connected to the direct current end anode of the MMC converter, the direct current voltage cathode of the another voltage class is connected to the direct current end cathode of the MMC converter, the alternating current end of the MMC converter is connected to the load access end through the output switch, and the bypass switch is connected between the alternating current power grid access end and the load access end.
2. The medium-high voltage power supply quality unified regulator containing distributed energy storage units according to claim 1, wherein in the n three-phase rectifiers, the positive pole of the direct current output end of the three-phase rectifier 1 is connected with the positive pole of the direct current end of the MMC converter, the negative pole of the direct current output end of the three-phase rectifier 1 is connected with the positive pole of the direct current output end of the three-phase rectifier 2, the other three-phase rectifiers are connected in sequence according to the connection method, the negative pole of the direct current output end of the direct current-to-three-phase rectifier n-1 is connected with the positive pole of the direct current output end of the three-phase rectifier n, and the negative pole of the direct current output end of the three-phase rectifier n is connected.
3. The medium-high voltage power supply quality unified regulator containing the distributed energy storage unit according to claim 1, wherein the ports of the composite sub-module SM comprise a first port and a second port, the first port of the composite sub-module SM is the first port of the MMC sub-module, the second port of the composite sub-module SM is the second port of the MMC sub-module, the third port of the MMC sub-module is connected with the positive electrode of the output end of the energy storage module, and the fourth port of the MMC sub-module is connected with the negative electrode of the output end of the energy storage module.
4. The unified regulator of medium and high voltage power supply quality with the distributed energy storage unit according to claim 1 or 3, wherein all of the MMC sub-modules in the bridge arm of the MMC converter are half-bridge sub-modules, or all of the MMC sub-modules are full-bridge sub-modules, or all of the MMC sub-modules are self-resistance sub-modules, or all of the MMC sub-modules are clamping bi-sub-modules, or a mixed use form of the MMC sub-modules, the MMC sub-modules can be formed by connecting a plurality of the MMC sub-modules in parallel according to the requirement of system capacity, so as to improve the maximum tolerant current flowing through the bridge arm of the MMC converter, wherein two input ports of the MMC sub-modules are respectively a first port and a second port of the MMC sub-modules, and the positive pole and the negative pole of the storage capacitor of the MMC sub-modules are.
5. The medium-high voltage power supply quality unified regulator containing the distributed energy storage units according to claim 1 or 3, wherein a port of the energy storage module comprises an output end positive electrode of the energy storage module and an output end negative electrode of the energy storage module, the energy storage module is composed of energy storage batteries, the output end positive electrode of the energy storage module is the energy storage battery positive electrode, and the output end negative electrode of the energy storage module is the energy storage battery negative electrode; or the energy storage module consists of a DC-DC converter and an energy storage battery, the positive electrode of the output end of the energy storage module is the positive electrode of the high-voltage end of the DC-DC converter, the negative electrode of the output end of the energy storage module is the negative electrode of the high-voltage end of the DC-DC converter, the positive electrode of the low-voltage end of the DC-DC converter is connected with the positive electrode of the energy storage battery, and the negative electrode of the low-voltage end of the DC-DC converter is connected with the negative electrode of the energy storage battery.
6. The medium-high voltage power supply quality unified regulator containing the distributed energy storage unit according to claim 1 or 3, wherein the energy storage module is composed of a DC-DC converter and an energy storage battery, the DC-DC converter is a non-isolated DC-DC converter or an isolated DC-DC converter, and the topology type of the DC-DC converter is selected according to the capacitance voltage grade of the MMC sub-module and the isolation requirement of the energy storage battery.
7. The medium-high voltage power supply quality unified regulator containing the distributed energy storage units as claimed in claim 1, wherein the primary three-phase winding connection of the phase-shifting transformer is star-shaped or triangular; the secondary three-phase winding connection method of the phase-shifting transformer adopts an extension connection mode of extending triangle phase shifting to realize that the voltage of the secondary winding wire is ahead of the voltage of the primary winding wire by-30°To 30°The phase angle degree of the secondary three-phase winding is selected according to the phase-shifting pulse wave number requirement of the phase-shifting transformer, the direct-current terminal voltage of the MMC converter and the manufacturing process feasibility of the number of the secondary three-phase windings, and the phase-shifting angle of the secondary three-phase winding is selected according to the phase-shifting pulse wave number requirement of the phase-shifting transformer and the number n of the secondary three-phase windings.
8. The medium-high voltage power supply quality unified regulator containing the distributed energy storage units according to claim 1, characterized in that according to the control type of the switching devices, all the n three-phase rectifiers are uncontrolled rectifiers, or all the three-phase rectifiers are half-controlled rectifiers, or all the three-phase rectifiers are full-controlled rectifiers, or the control type three-phase rectifiers are mixed; the direct current output ends of the n three-phase rectifiers boost direct current voltage in a cascading mode to form direct current voltage of another voltage level, and the direct current voltage of the another voltage level is the direct current end voltage of the MMC converter.
9. The medium-high voltage power supply quality unified regulator containing the distributed energy storage unit according to claim 1, wherein the ac grid access end is a first ac grid access end or a second ac grid access end, wherein the first ac grid access end is an ac grid access end to which the input switch is connected, and the second ac grid access end is another three-phase power supply.
10. The medium-high voltage power supply quality unified regulator containing the distributed energy storage unit according to claim 1, wherein the operation conditions of the medium-high voltage power supply quality unified regulator include a system grid-connected mode, an energy storage battery power supply mode, and a system bypass mode, and the operation conditions are switched according to the power grid condition, the system condition, and the load operation requirement, wherein,
the system grid-connected mode is an operation condition when a power grid normally operates, at the moment, the input switch and the output switch are both in a closed state, and the bypass switch is in an on-off state; the method comprises the following steps that the voltage of a power grid is converted through a phase-shifting transformer, three-phase alternating-current voltage with a specific phase-shifting angle is generated on each secondary winding of the phase-shifting transformer, the three-phase alternating-current voltage is rectified through a three-phase rectifier and then is used for improving the voltage of a direct-current end in a cascading mode, the voltage of the direct-current end outputs stable three-phase alternating-current voltage of a load end through an MMC current converter, and the voltage of the load end can be kept stable;
the power supply mode of the energy storage battery is an operation working condition when the power grid fails or is continuously disturbed, at the moment, the output switch is in a closed state, and the input switch and the bypass switch are both in an open state; the direct current end of the MMC converter is equivalent to open circuit, the energy storage module in each bridge arm composite submodule SM can output load power in real time according to the state of a power grid and the voltage condition of the direct current end after cascade connection, and the uninterrupted power supply of the load is ensured through the control of six bridge arms; according to the different topologies of the MMC sub-modules adopted in the composite sub-module SM of the bridge arms of the MMC converter, the power supply mode of the energy storage battery of the system is a single power supply mode of a cascade bridge formed by three upper bridge arms of the MMC converter, or a single power supply mode of the cascade bridge formed by three lower bridge arms, or a common power supply mode of two cascade bridges formed by three upper bridge arms and three lower bridge arms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011476258.0A CN112615388A (en) | 2020-12-15 | 2020-12-15 | Medium-high voltage power supply quality unified regulator containing distributed energy storage units |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011476258.0A CN112615388A (en) | 2020-12-15 | 2020-12-15 | Medium-high voltage power supply quality unified regulator containing distributed energy storage units |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112615388A true CN112615388A (en) | 2021-04-06 |
Family
ID=75234117
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011476258.0A Pending CN112615388A (en) | 2020-12-15 | 2020-12-15 | Medium-high voltage power supply quality unified regulator containing distributed energy storage units |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112615388A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113489350A (en) * | 2021-06-22 | 2021-10-08 | 北京帕斯特电力集成技术有限公司 | Novel power supply system suitable for data center |
| CN113872459A (en) * | 2021-09-22 | 2021-12-31 | 国网江苏省电力有限公司扬州供电分公司 | Serial MMC topological structure and control method |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103138675A (en) * | 2012-12-29 | 2013-06-05 | 辽宁荣信众腾科技有限公司 | High-voltage inverter sharing direct current (DC) bus |
| CN107017798A (en) * | 2017-03-30 | 2017-08-04 | 上海交通大学 | A kind of modular multi-level converter topology with energy-storage function |
| CN206402112U (en) * | 2016-12-27 | 2017-08-11 | 厦门理工学院 | Bank electricity system high power frequency conversion power supply based on 36 pulse wave rectifiers |
| CN209016722U (en) * | 2018-12-04 | 2019-06-21 | 国网湖北省电力有限公司电力科学研究院 | A kind of power cell and power cell control system |
| CN110022071A (en) * | 2019-04-18 | 2019-07-16 | 清华大学 | Hybrid energy-storing type commutator transformer and its control method |
-
2020
- 2020-12-15 CN CN202011476258.0A patent/CN112615388A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103138675A (en) * | 2012-12-29 | 2013-06-05 | 辽宁荣信众腾科技有限公司 | High-voltage inverter sharing direct current (DC) bus |
| CN206402112U (en) * | 2016-12-27 | 2017-08-11 | 厦门理工学院 | Bank electricity system high power frequency conversion power supply based on 36 pulse wave rectifiers |
| CN107017798A (en) * | 2017-03-30 | 2017-08-04 | 上海交通大学 | A kind of modular multi-level converter topology with energy-storage function |
| CN209016722U (en) * | 2018-12-04 | 2019-06-21 | 国网湖北省电力有限公司电力科学研究院 | A kind of power cell and power cell control system |
| CN110022071A (en) * | 2019-04-18 | 2019-07-16 | 清华大学 | Hybrid energy-storing type commutator transformer and its control method |
Non-Patent Citations (2)
| Title |
|---|
| NICK ELLIOTT 等: "AnewUPStopologyformultimegawattmediumvoltagepowerprotection", 《IEEE》 * |
| 杨晓峰 等: "应用于矿井提升机系统的超级电容储能型MMC", 《电源学报》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113489350A (en) * | 2021-06-22 | 2021-10-08 | 北京帕斯特电力集成技术有限公司 | Novel power supply system suitable for data center |
| CN113872459A (en) * | 2021-09-22 | 2021-12-31 | 国网江苏省电力有限公司扬州供电分公司 | Serial MMC topological structure and control method |
| CN113872459B (en) * | 2021-09-22 | 2022-12-02 | 国网江苏省电力有限公司扬州供电分公司 | Control method of serial MMC topological structure |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR102311485B1 (en) | Chain-type multi-port grid connection interface device and control method | |
| US9502991B2 (en) | Hybrid converter and wind power generating system | |
| CN109245557B (en) | Modular converter device, combined converter and control method | |
| CN111525826B (en) | Modular capacitor phase-change current converter and method | |
| WO2017084120A1 (en) | Unidirectional direct current-direct current autotransformer, and high-low voltage side fault isolation method therefor | |
| CN113991662A (en) | LCC-MMC-based energy routing system and DC fault protection method | |
| CN107612408B (en) | Energy storage converter and energy storage system | |
| CN213585162U (en) | AC/DC power supply structure of data center | |
| WO2023134225A1 (en) | Low-frequency power transmission system and control mode therefor | |
| CN112886594A (en) | AC/DC power supply structure of data center | |
| CN112615388A (en) | Medium-high voltage power supply quality unified regulator containing distributed energy storage units | |
| Wang et al. | A novel converter station structure for improving multiterminal HVDC system resiliency against AC and DC faults | |
| Kadandani et al. | Solid state transformer: An overview of circuit configurations and applications | |
| CN106972541A (en) | A kind of power distribution network multiterminal flexible interconnection switch based on mixed type submodule MMC | |
| CN211958778U (en) | Flexible direct current back-to-back system | |
| Cao et al. | Comparison of cascaded multilevel and modular multilevel converters with energy storage system | |
| Chong et al. | A Power Conversion System For Large-Scale Reversible SOFC Energy Storage System | |
| CN113452276B (en) | CCC-PHC type hybrid cascade direct current converter, rectifying station, inverter station and power transmission system | |
| CN111884246B (en) | Direct-current fault clearing method of layered series-parallel direct-current transmission system | |
| CN112615551A (en) | MMC type medium voltage power supply quality comprehensive improving system | |
| CN113726162A (en) | Series network type transformer based on voltage reduction type public direct current bus | |
| JP2015095926A (en) | Power conversion system and first charging method therefor | |
| Hu et al. | Application of power electronic technology to energy Internet | |
| CN112290526A (en) | Direct current collector used as offshore wind power energy management hub | |
| CN213243833U (en) | Many level of modularization current regulator |
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 | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210406 |
|
| RJ01 | Rejection of invention patent application after publication |