CN115912358A - Grid-connected smooth switching method and device for power distribution system, terminal and storage medium - Google Patents

Grid-connected smooth switching method and device for power distribution system, terminal and storage medium Download PDF

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Publication number
CN115912358A
CN115912358A CN202211722796.2A CN202211722796A CN115912358A CN 115912358 A CN115912358 A CN 115912358A CN 202211722796 A CN202211722796 A CN 202211722796A CN 115912358 A CN115912358 A CN 115912358A
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China
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low
voltage
direct
current
power distribution
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王磊
胡雪凯
周昊
王向东
陈柏翰
孙凯
周文
孟良
杨少波
李子璠
侯小超
田培根
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Tsinghua University
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd
State Grid Hebei Energy Technology Service Co Ltd
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Tsinghua University
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd
State Grid Hebei Energy Technology Service Co Ltd
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Priority to CN202211722796.2A priority Critical patent/CN115912358A/en
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    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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Abstract

The invention provides a grid-connected smooth switching method, a grid-connected smooth switching device, a grid-connected smooth switching terminal and a grid-connected smooth switching storage medium for a power distribution system. The method comprises the following steps: configuring a high-voltage alternating-current power distribution network, a medium-voltage direct-current power distribution network, a low-voltage alternating-current power distribution network and a low-voltage direct-current power distribution network in a power distribution system, arranging a direct/direct-current converter station between the medium-voltage direct-current power distribution network and the low-voltage direct-current power distribution network, and arranging a low-voltage alternating-current transformer substation between the medium-voltage alternating-current power distribution network and the low-voltage alternating-current power distribution network; monitoring operation data of the direct/direct current converter station and the low-voltage alternating current transformer substation, and judging the states of the direct/direct current converter station and the low-voltage alternating current transformer substation according to the operation data; when the state of the direct current/direct current converter station is a fault state, smoothly switching the low-voltage alternating current transformer substation to supply power to the low-voltage direct current distribution network; and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct current/direct current converter station to supply power to the low-voltage alternating-current distribution network. The invention can smoothly switch in the grid-connected switching process so as to ensure the normal operation of the low-voltage distribution network.

Description

Grid-connected smooth switching method and device for power distribution system, terminal and storage medium
Technical Field
The invention relates to the technical field of grid-connected smooth switching, in particular to a grid-connected smooth switching method, a grid-connected smooth switching device, a grid-connected smooth switching terminal and a storage medium of a power distribution system.
Background
The roof distributed photovoltaic power generation develops rapidly in recent years, and the practical application of the roof distributed photovoltaic power generation is mainly photovoltaic power generation facilities which are characterized by self-generation and self-use at a user side, on-line with redundant electric quantity and balance adjustment in a power distribution system. The roof distributed photovoltaic power generation is a novel power generation and energy comprehensive utilization mode with wide development prospect, advocates the principles of near power generation, near grid connection, near conversion and near use, not only can effectively improve the generated energy of photovoltaic power stations with the same scale, but also effectively solves the loss problem of electric power in boosting and long-distance transportation.
However, the photovoltaic high-proportion access of the low-voltage distribution network at present easily causes the following problems: 1. reverse power flow and voltage rise; 2. in the daytime, overvoltage is generated when photovoltaic power generation power is excessive; 3. photovoltaic power generation is stopped at night and the load is heavy, the voltage is underdriven, and the influence of weather is great in daytime. In addition, the problems of voltage out-of-limit and power reverse transmission caused by photovoltaic high-proportion access of the low-voltage distribution network are also obvious. In addition, in the grid-connected switching process, the phenomenon of power failure and the like caused by unsmooth switching is easy to occur, and once the power failure occurs, irreparable loss is caused to the production and the life of residents and the society.
Disclosure of Invention
The embodiment of the invention provides a grid-connected smooth switching method, a grid-connected smooth switching device, a terminal and a storage medium of a power distribution system, and aims to solve the problem of power failure caused by unsmooth switching in the grid-connected switching process in the prior art.
In a first aspect, an embodiment of the present invention provides a grid-connected smooth switching method for a power distribution system, including:
configuring a high-voltage alternating-current power distribution network, a medium-voltage direct-current power distribution network, a low-voltage alternating-current power distribution network and a low-voltage direct-current power distribution network in a power distribution system, arranging a direct/direct-current converter station between the medium-voltage direct-current power distribution network and the low-voltage direct-current power distribution network, and arranging a low-voltage alternating-current transformer substation between the medium-voltage alternating-current power distribution network and the low-voltage alternating-current power distribution network;
monitoring operation data of the direct/direct current converter station and the low-voltage alternating current transformer substation, and judging the states of the direct/direct current converter station and the low-voltage alternating current transformer substation according to the operation data;
when the state of the direct current/direct current converter station is a fault state, smoothly switching the low-voltage alternating current transformer substation to supply power to the low-voltage direct current distribution network;
and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct/direct current converter station to supply power to the low-voltage alternating-current power distribution network.
In a possible implementation manner, the grid-connected smooth switching method of the power distribution system further includes: configuring an energy storage device and an optical storage device in the power distribution system, wherein the energy storage device is arranged in the low-voltage direct current power distribution network, and the optical storage device is arranged in the low-voltage alternating current power distribution network;
monitoring device data of the energy storage device and the optical storage device, and judging the states of the energy storage device and the optical storage device according to the device data;
when the state of the optical storage device is insufficient energy storage and the states of the direct current/direct current converter station and the low-voltage alternating current transformer substation are normal states, the low-voltage alternating current transformer substation is switched smoothly to supply power to the low-voltage alternating current power distribution network, and the direct current/direct current converter station and the energy storage device supply power to the low-voltage direct current power distribution network;
when the state of the energy storage device is insufficient energy storage and the states of the direct current/direct current converter station and the low-voltage alternating current transformer substation are normal states, the direct current/direct current converter station is switched smoothly to supply power to the low-voltage direct current power distribution network, and the low-voltage alternating current transformer substation and the light device supply power to the low-voltage alternating current power distribution network.
In a possible implementation manner, the grid-connected smooth switching method of the power distribution system further includes:
when the states of the optical storage device and the energy storage device are sufficient in energy storage and the states of the direct current/direct current converter station and the low-voltage alternating current transformer station are fault states, the energy storage device is switched smoothly to supply power to the low-voltage direct current power distribution network, and the optical storage device supplies power to the low-voltage alternating current power distribution network.
In a possible implementation manner, when the state of the dc/dc converter station is a fault state, the smoothly switching the low-voltage ac substation to supply power to the low-voltage dc distribution network includes:
and when the DC/DC converter station is in a no-load operation, maintenance or power failure state, smoothly switching the low-voltage AC transformer substation and the optical device to supply power to the low-voltage AC power distribution network, and supplying power to the low-voltage DC power distribution network by the low-voltage AC power distribution network and the energy storage device.
In a possible implementation manner, when the state of the low-voltage ac substation is a fault state, the smoothly switching the dc/dc converter station to supply power to the low-voltage ac distribution network includes:
when the low-voltage alternating-current transformer substation is in no-load operation, maintenance or power failure, the direct/direct-current converter station and the energy storage device are switched smoothly to supply power to the low-voltage direct-current power distribution network, and the low-voltage direct-current power distribution network and the light device supply power to the low-voltage alternating-current power distribution network.
In one possible implementation, a coaxial machine is provided within the power distribution system;
and one end of the coaxial machine is connected with the low-voltage alternating-current power distribution network through a low-voltage alternating-current bus, and the other end of the coaxial machine is connected with the direct-current power distribution network through a low-voltage direct-current bus, so that flexible sequential connection of a medium-voltage direct-current port, a direct/direct-current converter station, the coaxial machine, a low-voltage alternating-current transformer substation and a medium-voltage alternating-current port is realized.
In one possible implementation, when the medium-voltage dc port and the medium-voltage ac port are disconnected, the energy storage device stabilizes the low-voltage dc bus, and realizes flexible sequential connection of the dc/dc converter station, the coaxial machine, and the low-voltage ac substation
In a second aspect, an embodiment of the present invention provides a grid-connected smooth switching device for a power distribution system, where a high-voltage ac power distribution network, a medium-voltage dc power distribution network, a low-voltage ac power distribution network, and a low-voltage dc power distribution network are configured in the power distribution system, a dc/dc converter station is provided between the medium-voltage dc power distribution network and the low-voltage dc power distribution network, and a low-voltage ac substation is provided between the medium-voltage ac power distribution network and the low-voltage ac power distribution network, including:
the monitoring module is used for monitoring the operation data of the direct/direct current converter station and the low-voltage alternating current transformer station;
the judging module is used for judging the states of the direct/direct current converter station and the low-voltage alternating current transformer substation according to the operation data;
the processing module is used for smoothly switching the low-voltage alternating-current transformer substation to supply power to the low-voltage direct-current power distribution network when the state of the direct/direct-current converter station is a fault state; and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct/direct current converter station to supply power to the low-voltage alternating-current power distribution network.
In a third aspect, an embodiment of the present invention provides a terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the method according to the first aspect or any possible implementation manner of the first aspect when executing the computer program.
In a fourth aspect, the present invention provides a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the computer program implements the steps of the method according to the first aspect or any one of the possible implementation manners of the first aspect.
The embodiment of the invention provides a grid-connected smooth switching method, a grid-connected smooth switching device, a grid-connected smooth switching terminal and a storage medium of a power distribution system, wherein the states of a direct/direct converter station and a low-voltage alternating-current transformer substation are judged according to operation data by monitoring the operation data of the direct/direct converter station and the low-voltage alternating-current transformer substation; when the state of the direct current/direct current converter station is a fault state, smoothly switching the low-voltage alternating current transformer substation to supply power to the low-voltage direct current distribution network; and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct/direct current converter station to supply power to the low-voltage alternating-current power distribution network. The invention can switch different power supply modes according to the running states of the direct/direct current converter station and the low-voltage alternating current transformer station, and can ensure the stability of the low-voltage direct current distribution network and the low-voltage alternating current distribution network in real time in the switching process, thereby ensuring the normal running of the low-voltage distribution network and avoiding the power failure accident caused by the instability of the low-voltage distribution network.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart illustrating an implementation of a grid-connected smooth switching method for a power distribution system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a power distribution system provided by an embodiment of the present invention;
fig. 3 is a circuit diagram of an ac/dc converter provided in an embodiment of the present invention;
fig. 4 is a voltage waveform of an ac/dc converter circuit provided by an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a coaxial machine provided by an embodiment of the invention;
fig. 6 is a schematic structural diagram of a grid-connected smooth switching device of a power distribution system according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a terminal according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following description is made by way of specific embodiments with reference to the accompanying drawings.
Fig. 1 is a flowchart of an implementation of a grid-connected smooth switching method for a power distribution system according to an embodiment of the present invention, which is detailed as follows:
a high-voltage alternating-current power distribution network, a medium-voltage direct-current power distribution network, a low-voltage alternating-current power distribution network and a low-voltage direct-current power distribution network are configured in a power distribution system, a direct/direct-current converter station is arranged between the medium-voltage direct-current power distribution network and the low-voltage direct-current power distribution network, and a low-voltage alternating-current transformer substation is arranged between the medium-voltage alternating-current power distribution network and the low-voltage alternating-current power distribution network.
Step 101, monitoring operation data of a direct/direct current converter station and a low-voltage alternating current transformer station.
Optionally, the operation data mainly includes data in the operation process of the direct/direct current converter station and the low-voltage alternating current transformer station, switch operation data, primary measurement equipment operation data, lightning arrester operation data, direct current key operation data, valve cooling system operation data, alternating current/direct current filter operation data, oil chromatography operation data, sleeve on-line monitoring operation data and infrared temperature measurement operation data.
The data in the operation process of the direct/direct current converter station and the low-voltage alternating current transformer substation can be operation data such as pipe pressure, tap action times, oil temperature linear temperature, oil level and iron core clamp current corresponding to the direct/direct current converter station and the low-voltage alternating current transformer substation.
Step 102, judging the states of the direct/direct current converter station and the low-voltage alternating current transformer station according to the operation data;
103, when the state of the direct current/direct current converter station is a fault state, smoothly switching the low-voltage alternating current transformer substation to supply power to a low-voltage direct current distribution network; and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct/direct current converter station to supply power to the low-voltage alternating-current distribution network.
Optionally, the fault state represents a state when the dc/dc converter station or the low-voltage ac substation has no input, and may be idle operation, maintenance or power failure.
When the DC/DC converter station is in no-load operation, maintenance or power failure, the low-voltage AC transformer substation and the optical device are switched smoothly to supply power to the low-voltage AC distribution network, and the low-voltage AC distribution network and the energy storage device supply power to the low-voltage DC distribution network.
Optionally, an energy storage converter is disposed between the low-voltage ac power distribution network and the low-voltage dc power distribution network, and is configured to convert energy of the optical storage device and energy of the energy storage device, so as to balance voltages of the low-voltage ac power distribution network and the low-voltage dc power distribution network.
Optionally, when the dc/dc converter station is in an idle running, maintenance or power failure state, the voltage of the low-voltage ac power distribution network is maintained by a low-voltage port of the low-voltage ac transformer substation, the energy storage device charges and discharges the low-voltage dc power distribution network according to the power instruction, and the low-voltage ac power distribution network supplies power to the low-voltage dc power distribution network through the energy storage converter, so that the voltage stability of the low-voltage dc power distribution network is maintained. At the moment, the low-voltage port of the low-voltage alternating-current transformer substation has smooth switching capacity, voltage balance of the low-voltage alternating-current power distribution network and the low-voltage direct-current power distribution network is achieved, and production and life of residents and society are guaranteed.
When the low-voltage alternating-current transformer substation is in no-load operation, maintenance or power failure, the direct/direct-current converter station and the energy storage device are switched smoothly to supply power to the low-voltage direct-current distribution network, and the low-voltage direct-current distribution network and the optical device supply power to the low-voltage alternating-current distribution network.
Optionally, when the low-voltage ac substation is in an idle running, maintenance or power failure state, the low-voltage port of the dc/dc converter station stabilizes the low-voltage dc bus, the energy storage device charges and discharges the low-voltage dc power distribution network according to the power instruction, the low-voltage ac port of the low-voltage ac bus at the connection between the low-voltage dc power distribution network and the low-voltage ac power distribution network maintains the voltage of the low-voltage ac power distribution network, the photovoltaic node outputs the low-voltage ac power distribution network according to the maximum power of the photovoltaic node, and at this time, the low-voltage port of the dc/dc converter needs to have a smooth switching capability.
In a possible embodiment, the grid-connected smooth switching method of the power distribution system further includes: an energy storage device and an optical storage device are configured in a power distribution system, the energy storage device is arranged in a low-voltage direct-current power distribution network, and the optical storage device is arranged in a low-voltage alternating-current power distribution network;
monitoring device data of the energy storage device and the optical storage device, and judging the states of the energy storage device and the optical storage device according to the device data;
optionally, the device data of the energy storage device and the optical storage device may be voltages or electric quantities of the energy storage device and the optical storage device, and when the voltages or the electric quantities of the energy storage device and the optical storage device are smaller than a preset value, the states of the energy storage device and the optical storage device are determined as insufficient energy storage.
When the state of the optical storage device is insufficient energy storage and the states of the direct current/direct current converter station and the low-voltage alternating current transformer substation are normal states, the low-voltage alternating current transformer substation is switched smoothly to supply power to the low-voltage alternating current distribution network, and the direct current/direct current converter station and the energy storage device supply power to the low-voltage direct current distribution network;
optionally, when the state of the optical storage device is energy storage deficiency and the states of the dc/dc converter station and the low-voltage ac transformer station are normal states, the dc/dc converter station and the low-voltage ac transformer station have power output capability at the same time, the energy storage device charges and discharges the low-voltage dc distribution network according to the power instruction, and at this time, the low-voltage ac transformer station and the dc/dc converter station have smooth switching capability.
When the energy storage device is in an insufficient energy storage state and the direct current/direct current converter station and the low-voltage alternating current transformer substation are in normal states, the direct current/direct current converter station is switched smoothly to supply power to the low-voltage direct current power distribution network, and the low-voltage alternating current transformer substation and the light device supply power to the low-voltage alternating current power distribution network.
Optionally, when the state of the energy storage device is insufficient energy storage and the states of the direct/direct current converter station and the low-voltage alternating current transformer substation are normal, the direct/direct current converter station and the low-voltage alternating current transformer substation have power output capability at the same time, the optical storage device charges and discharges the low-voltage alternating current power distribution network according to the power instruction, and at this time, the low-voltage alternating current transformer substation and the direct/direct current converter station have smooth switching capability.
In a possible embodiment, the grid-connected smooth switching method of the power distribution system further includes:
when the states of the optical storage device and the energy storage device are the states that energy storage is sufficient and the states of the direct current/direct current converter station and the low-voltage alternating current transformer substation are fault states, the energy storage device is switched smoothly to supply power to the low-voltage direct current distribution network, and the optical storage device supplies power to the low-voltage alternating current distribution network.
Optionally, when the state of the optical storage device and the state of the energy storage device are that the energy storage is sufficient and the states of the direct current/direct current converter station and the low voltage alternating current transformer station are fault states, the optical storage device and the energy storage device maintain the stability of the low voltage power distribution network according to the power instruction, at this time, the low voltage alternating current transformer station and the direct current/direct current converter station are both disconnected from running, and the energy storage converter needs to have the capability of maintaining the low voltage alternating current bus voltage and the low voltage direct current bus voltage at the same time.
As shown in fig. 2, the schematic structural diagram of the power distribution system, the grid-connected smooth switching system of the power distribution system includes: a high voltage ac distribution network 10, a medium voltage ac distribution network 11, a medium voltage dc distribution network 12, a low voltage dc distribution network 13, a low voltage ac distribution network 14, a transformer substation 20, a low voltage ac transformer substation 21, an ac/dc converter station 22, a dc/dc converter station 23, an energy storage device 24, an optical storage device 25, and a dc/ac converter 26;
the output end of the high-voltage alternating-current distribution network 10 is connected with the input end of a transformer 20 through a high-voltage alternating-current branch, the output end of the transformer 20 is connected with the input end of a medium-voltage alternating-current distribution network 11 through a high-voltage alternating-current branch, the output end of the medium-voltage alternating-current distribution network 11 is connected with the input end of an alternating/direct-current converter 22 through a medium-voltage alternating-current branch, and the output end of the alternating/direct-current converter 22 is connected with the input end of a medium-voltage direct-current distribution network 12 through a medium-voltage direct-current branch;
the output end of the medium-voltage alternating-current distribution network 11 is connected with the input end of the low-voltage alternating-current transformer substation 21 through a low-voltage alternating-current bus, the output end of the low-voltage alternating-current transformer substation 21 is connected with the input end of the low-voltage alternating-current distribution network 14 through a low-voltage alternating-current bus, the output end of the medium-voltage direct-current distribution network 12 is connected with the input end of the direct/direct-current converter 23 through a medium-voltage direct-current bus, and the output end of the direct/direct-current converter 23 is connected with the input end of the low-voltage direct-current distribution network 13 through a low-voltage direct-current bus;
the output end of the low-voltage alternating-current distribution network 14 is connected with the input end of an alternating-current/direct-current converter 22 through a low-voltage alternating-current branch, the output end of the alternating-current/direct-current converter 22 is connected with the input end of a low-voltage direct-current distribution network 13 through a low-voltage direct-current branch, the output end of the low-voltage direct-current distribution network 13 is connected with the input end of a direct-current/exchange converter 26 through a low-voltage direct-current branch, and the output end of the direct-current/exchange converter 26 is connected with the input end of the low-voltage alternating-current distribution network 14 through a low-voltage alternating-current branch;
the output end of the energy storage device 24 is connected with the input end of the low-voltage direct-current power distribution network 13 through a low-voltage direct-current bus;
the output of the optical storage device 25 is connected to the input of the dc/ac converter 26 via a low-voltage ac branch, and the output of the dc/ac converter 26 is connected to the input of the low-voltage ac distribution network 14 via a low-voltage ac branch.
In one possible embodiment, a coaxial machine is provided within the power distribution system;
optionally, the coaxial machine is coaxially connected with a three-phase alternating current motor and a direct current motor, and the coaxial machine is configured in the power distribution system to generate an equal proportion control technology of voltages of an alternating current port and a direct current port, so that the problem that smooth switching cannot be performed is solved.
The invention makes the proportional control technique of the AC port and DC port voltage more clear by comparing and analyzing the AC/DC converter and the coaxial machine.
Alternatively, referring to the circuit diagram of the ac/dc converter shown in fig. 3 and the voltage waveform shown in fig. 4, it can be obtained that the ac/dc converter employs a three-phase bridge rectifier circuit, which is composed of six rectifier diodes, at t 1 ~t 2 During the period, e in the common cathode group a Highest point potential, S 1 Conducting, in common anode e b Lowest point potential, S 4 And conducting. At this time, the current flows through u a ->e a ->S 1 ->u D ->S 4 ->e b ->u b The voltage at the DC port is line voltage u a -u b
At t 2 ~t 3 During the period of time, e in the common cathode group a Highest point potential, S 1 Conducting, common anode group e c Lowest point potential, S 6 And conducting. At this time, the current flows through u a ->e a ->S 1 ->u D ->S 6 ->e c ->u c The voltage at the DC port is line voltage u a -u c
At t 3 ~t 4 During the period of time, e in the common cathode group b Highest point potential, S 3 Conducting, common anode group e c Lowest point potential, S 6 And conducting. At this time, the current flows through u b ->e b ->S 3 ->u D ->S 6 ->e c ->u c The voltage at the DC port is line voltage u b -u c
Optionally, the conducting diode is judged according to the level of the potential, so that a current path is obtained, and the equal proportion control of the alternating current port voltage and the direct current port voltage is realized.
As shown in the schematic structural diagram of the coaxial machine shown in fig. 5, from the perspective of the ac/dc interface converter, the voltage state equation can be expressed as:
Figure BDA0004030153300000091
u a 、u b and u c Respectively representing the phase voltage of the AC input port, in each case>
Figure BDA0004030153300000092
And &>
Figure BDA0004030153300000093
Respectively represent three-phase rotating magnetomotive force, i a 、i b And i c Respectively representing three-phase currents, e a 、e b And e c Respectively representing three-phase electromotive force, r a i a 、r b i b And r c i c Respectively representing three-phase line voltage reduction, and t represents the current time.
And obtaining dq axis components through park transformation, wherein a park transformation matrix is as follows:
Figure BDA0004030153300000101
wherein C T Representing park transformation matricesθ denotes the current vector position, t 0 Representing initial time, omega representing rotational vector speed, theta 0 Indicating the initial vector position.
According to
Figure BDA0004030153300000102
Obtaining a dq axis component;
wherein u is d Represents the direct axis voltage u q Representing the quadrature axis voltage, L representing the inductance, i q Representing quadrature axis current, i d Represents the direct axis current, r d i d Indicating a direct line voltage drop, r q i q Indicating quadrature line step-down, e d Representing direct-axis electromotive force, e q Representing the quadrature electromotive force.
From a coaxial machine perspective, the dq axis component can be written as:
Figure BDA0004030153300000103
wherein e is md Representing direct-axis modulated electromotive force, omega m Indicating the modulated rotary vector speed.
Therefore, the coaxial machine control of the AC/DC interface converter is realized, and the direct-axis component e of the electromotive force is induced d =e md Set to 0, a quadrature component e q =e mq Writing an equivalent control equation of the AC-DC interface converter to a coaxial motor:
Figure BDA0004030153300000111
wherein e is mq Representing quadrature modulated electromotive force.
One end of the coaxial machine is connected with a low-voltage alternating-current power distribution network through a low-voltage alternating-current bus, the other end of the coaxial machine is connected with a direct-current power distribution network through a low-voltage direct-current bus, and flexible sequential connection of a medium-voltage direct-current port, a direct/direct-current converter station, the coaxial machine, a low-voltage alternating-current transformer substation and a medium-voltage alternating-current port is achieved.
After the control of the coaxiality machine is realized, the voltage amplitude of the alternating current/direct current port is proportional, so that the effect of connecting a plurality of groups of coaxiality machines in parallel at the port of the energy storage converter is realized for the low-voltage power distribution network, and the method is equivalent to connecting the alternating current/direct current low-voltage bus with the alternating current/direct current coaxial machines, and realizing the flexible connection of a medium-voltage direct current port, a direct/direct current converter station, the coaxiality machine, a low-voltage alternating current transformer substation and a medium-voltage alternating current port.
In one possible embodiment, the energy storage device stabilizes the low-voltage dc bus when the medium-voltage dc port and the medium-voltage ac port are disconnected, enabling a flexible sequential connection of the dc/dc converter station, the coaxial machine and the low-voltage ac substation.
Optionally, when the medium-voltage dc port and the medium-voltage ac port are disconnected, the energy storage converter stabilizes the low-voltage dc bus to form a flexible connection between the dc/dc converter station, the coaxial machine, and the low-voltage ac transformer station, and only if the energy storage converter has sufficient capacity, the voltage of the low-voltage distribution network is stabilized, thereby implementing a smooth switching function.
The embodiment of the invention provides a grid-connected smooth switching method of a power distribution system, which comprises the steps of monitoring operation data of a direct/direct current converter station and a low-voltage alternating current transformer substation, and judging the states of the direct/direct current converter station and the low-voltage alternating current transformer substation according to the operation data; when the state of the direct current/direct current converter station is a fault state, smoothly switching the low-voltage alternating current transformer substation to supply power to the low-voltage direct current distribution network; and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct/direct current converter station to supply power to the low-voltage alternating-current distribution network. The invention can switch different power supply modes according to the running states of the direct/direct current converter station and the low-voltage alternating current transformer station, and can ensure the stability of the low-voltage direct current distribution network and the low-voltage alternating current distribution network in real time in the switching process, thereby ensuring the normal running of the low-voltage distribution network and avoiding the power failure accident caused by the instability of the low-voltage distribution network. And a coaxial machine is arranged between the two ports of the energy storage converter, and the control between the two ports has the characteristic of a synchronous machine, so that the flexible connection of the medium-voltage direct current port, the direct/direct current converter station, the coaxial machine, the low-voltage alternating current transformer substation and the medium-voltage alternating current port is realized.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
The following are embodiments of the apparatus of the invention, reference being made to the corresponding method embodiments described above for details which are not described in detail therein.
Fig. 6 is a schematic structural diagram of a grid-connected smooth switching device of a power distribution system according to an embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and detailed descriptions are as follows:
as shown in fig. 6, a high-voltage ac distribution network, a medium-voltage dc distribution network, a low-voltage ac distribution network, and a low-voltage dc distribution network are configured in a distribution system, a dc/dc converter station is provided between the medium-voltage dc distribution network and the low-voltage dc distribution network, a low-voltage ac substation is provided between the medium-voltage dc distribution network and the low-voltage dc distribution network, and the distribution system grid-connection smooth switching apparatus 60 includes: .
The monitoring module 61 is used for monitoring the operation data of the direct/direct current converter station and the low-voltage alternating current transformer station;
the judging module 62 is used for judging the states of the direct/direct current converter station and the low-voltage alternating current transformer station according to the operation data;
the processing module 63 is used for smoothly switching the low-voltage alternating-current transformer substation to supply power to the low-voltage direct-current power distribution network when the state of the direct/direct-current converter station is a fault state; and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct/direct current converter station to supply power to the low-voltage alternating-current distribution network.
In a possible implementation manner, an energy storage device and an optical storage device are configured in the power distribution system, the energy storage device is disposed in a low-voltage direct-current power distribution network, the optical storage device is disposed in a low-voltage alternating-current power distribution network, and the monitoring module 61 is further configured to monitor device data of the energy storage device and the optical storage device;
the judging module 62 is further configured to judge states of the energy storage device and the optical storage device according to the device data;
the processing module 63 is further configured to, when the state of the optical storage device is an energy storage shortage and the states of the dc/dc converter station and the low-voltage ac transformer substation are normal states, smoothly switch the low-voltage ac transformer substation to supply power to the low-voltage ac distribution network, and supply power to the low-voltage dc distribution network through the dc/dc converter station and the energy storage device; and when the energy storage device is in a state of insufficient energy storage and the direct/direct current converter station and the low-voltage alternating current transformer substation are in normal states, smoothly switching the direct/direct current converter station to supply power to the low-voltage direct current power distribution network, and supplying power to the low-voltage alternating current power distribution network by the low-voltage alternating current transformer substation and the optical device.
In a possible implementation manner, the processing module 63 is further configured to, when the states of the optical storage device and the energy storage device are that the energy storage is sufficient and the states of the dc/dc converter station and the low-voltage ac substation are fault states, smoothly switch the energy storage device to supply power to the low-voltage dc distribution network, and the optical storage device supplies power to the low-voltage ac distribution network.
In one possible implementation manner, when the state of the dc/dc converter station is a fault state, the processing module 63 switches the low-voltage ac substation smoothly to supply power to the low-voltage dc distribution network, and is configured to:
when the DC/DC converter station is in no-load operation, maintenance or power failure, the low-voltage AC transformer substation and the optical device are switched smoothly to supply power to the low-voltage AC distribution network, and the low-voltage AC distribution network and the energy storage device supply power to the low-voltage DC distribution network.
In one possible implementation, when the state of the low-voltage ac substation is a fault state, the processing module 63 smoothly switches the dc/dc converter station to supply power to the low-voltage ac distribution network, and is configured to:
when the low-voltage alternating-current transformer substation is in no-load operation, maintenance or power failure, the direct/direct-current converter station and the energy storage device are switched smoothly to supply power to the low-voltage direct-current distribution network, and the low-voltage direct-current distribution network and the optical device supply power to the low-voltage alternating-current distribution network.
In one possible implementation, a coax is provided within the power distribution system;
one end of the coaxial machine is connected with a low-voltage alternating-current power distribution network through a low-voltage alternating-current bus, and the other end of the coaxial machine is connected with a direct-current power distribution network through a low-voltage direct-current bus, so that flexible sequential connection of a medium-voltage direct-current port, a direct/direct-current converter station, the coaxial machine, a low-voltage alternating-current transformer substation and a medium-voltage alternating-current port is realized.
In one possible implementation, when the medium voltage dc port and the medium voltage ac port are disconnected, the energy storage device stabilizes the low voltage dc bus, and realizes flexible sequential connection of the dc/dc converter station, the coaxial machine, and the low voltage ac substation.
The embodiment of the invention provides a grid-connected smooth switching device of a power distribution system, which is characterized in that the states of a direct/direct converter station and a low-voltage alternating-current transformer substation are judged according to operation data by monitoring the operation data of the direct/direct converter station and the low-voltage alternating-current transformer substation; when the state of the direct current/direct current converter station is a fault state, smoothly switching the low-voltage alternating current transformer substation to supply power to the low-voltage direct current distribution network; and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct/direct current converter station to supply power to the low-voltage alternating-current distribution network. The invention can switch different power supply modes according to the running states of the direct/direct current converter station and the low-voltage alternating current transformer station, and can ensure the stability of the low-voltage direct current distribution network and the low-voltage alternating current distribution network in real time in the switching process, thereby ensuring the normal running of the low-voltage distribution network and avoiding the power failure accident caused by the instability of the low-voltage distribution network. And a coaxial machine is arranged between the two ports of the energy storage converter, and the control between the two ports has the characteristic of a synchronous machine, so that flexible connection of the medium-voltage direct-current port, the direct/direct-current converter station, the coaxial machine, the low-voltage alternating-current transformer substation and the medium-voltage alternating-current port is realized.
Fig. 7 is a schematic diagram of a terminal according to an embodiment of the present invention. As shown in fig. 7, the terminal 7 of this embodiment includes: a processor 70, a memory 71, and a computer program 72 stored in the memory 71 and operable on the processor 70. The processor 70, when executing the computer program 72, implements the steps in the above-described embodiments of the grid-connection smooth switching method for each power distribution system, such as the steps 101 to 103 shown in fig. 1. Alternatively, the processor 70, when executing the computer program 72, implements the functions of the various modules/units in the various device embodiments described above, such as the functions of the modules/units 61-63 shown in fig. 6.
Illustratively, the computer program 72 may be divided into one or more modules/units, which are stored in the memory 71 and executed by the processor 70 to carry out the invention. One or more of the modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of the computer program 72 in the terminal 7. For example, the computer program 72 may be divided into the modules/units 61 to 63 shown in fig. 6.
The terminal 7 may include, but is not limited to, a processor 70, a memory 71. It will be appreciated by those skilled in the art that fig. 7 is only an example of a terminal 7 and does not constitute a limitation of the terminal 7, and that it may comprise more or less components than those shown, or some components may be combined, or different components, e.g. the terminal may further comprise input output devices, network access devices, buses, etc.
The Processor 70 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The storage 71 may be an internal storage unit of the terminal 7, such as a hard disk or a memory of the terminal 7. The memory 71 may also be an external storage device of the terminal 7, such as a plug-in hard disk provided on the terminal 7, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like. Further, the memory 71 may also include both an internal storage unit of the terminal 7 and an external storage device. The memory 71 is used for storing computer programs and other programs and data required by the terminal. The memory 71 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules, so as to perform all or part of the functions described above. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only used for distinguishing one functional unit from another, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the description of each embodiment has its own emphasis, and reference may be made to the related description of other embodiments for parts that are not described or recited in any embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal and method may be implemented in other ways. For example, the above-described apparatus/terminal embodiments are merely illustrative, and for example, a module or a unit may be divided into only one type of logical function, and may be implemented in another manner, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not implemented. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow in the method according to the embodiments of the present invention may also be implemented by instructing related hardware through a computer program, where the computer program may be stored in a computer readable storage medium, and when the computer program is executed by a processor, the steps of the embodiments of the method for smoothly switching between grid connection and grid connection of each power distribution system may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying computer program code, recording medium, U.S. disk, removable hard disk, magnetic disk, optical disk, computer Memory, read-Only Memory (ROM), random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution media, and the like.
The above examples are only intended to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.

Claims (10)

1. A grid-connected smooth switching method for a power distribution system is characterized by comprising the following steps: configuring a high-voltage alternating-current power distribution network, a medium-voltage direct-current power distribution network, a low-voltage alternating-current power distribution network and a low-voltage direct-current power distribution network in a power distribution system, arranging a direct/direct-current converter station between the medium-voltage direct-current power distribution network and the low-voltage direct-current power distribution network, and arranging a low-voltage alternating-current transformer substation between the medium-voltage alternating-current power distribution network and the low-voltage alternating-current power distribution network;
monitoring operation data of the direct/direct current converter station and the low-voltage alternating current transformer substation, and judging the states of the direct/direct current converter station and the low-voltage alternating current transformer substation according to the operation data;
when the state of the direct current/direct current converter station is a fault state, smoothly switching the low-voltage alternating current transformer substation to supply power to the low-voltage direct current distribution network;
and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct/direct current converter station to supply power to the low-voltage alternating-current power distribution network.
2. The grid-connected smooth switching method of the power distribution system according to claim 1, further comprising: configuring an energy storage device and an optical storage device in the power distribution system, wherein the energy storage device is arranged in the low-voltage direct current power distribution network, and the optical storage device is arranged in the low-voltage alternating current power distribution network;
monitoring device data of the energy storage device and the optical storage device, and judging the states of the energy storage device and the optical storage device according to the device data;
when the state of the optical storage device is insufficient energy storage and the states of the direct current/direct current converter station and the low-voltage alternating current transformer substation are normal states, the low-voltage alternating current transformer substation is switched smoothly to supply power to the low-voltage alternating current power distribution network, and the direct current/direct current converter station and the energy storage device supply power to the low-voltage direct current power distribution network;
when the state of the energy storage device is insufficient energy storage and the states of the direct current/direct current converter station and the low-voltage alternating current transformer substation are normal states, the direct current/direct current converter station is switched smoothly to supply power to the low-voltage direct current power distribution network, and the low-voltage alternating current transformer substation and the light device supply power to the low-voltage alternating current power distribution network.
3. The grid-connected smooth switching method of the power distribution system according to any one of claims 1 to 2, further comprising:
when the states of the optical storage device and the energy storage device are sufficient in energy storage and the states of the direct current/direct current converter station and the low-voltage alternating current transformer station are fault states, the energy storage device is switched smoothly to supply power to the low-voltage direct current power distribution network, and the optical storage device supplies power to the low-voltage alternating current power distribution network.
4. The grid-connected smooth switching method of the power distribution system according to claim 3, wherein when the state of the DC/DC converter station is a fault state, smoothly switching the low-voltage AC substation to supply power to the low-voltage DC distribution network comprises:
and when the DC/DC converter station is in a no-load operation, maintenance or power failure state, smoothly switching the low-voltage AC transformer substation and the optical device to supply power to the low-voltage AC power distribution network, and supplying power to the low-voltage DC power distribution network by the low-voltage AC power distribution network and the energy storage device.
5. The grid-connected smooth switching method of the power distribution system according to claim 4, wherein when the state of the low-voltage ac substation is a fault state, smoothly switching the dc/dc converter station to supply power to the low-voltage ac power distribution network comprises:
when the low-voltage alternating-current transformer substation is in no-load operation, maintenance or power failure, the direct/direct-current converter station and the energy storage device are switched smoothly to supply power to the low-voltage direct-current power distribution network, and the low-voltage direct-current power distribution network and the light device supply power to the low-voltage alternating-current power distribution network.
6. The grid-connected smooth switching method of the power distribution system according to claim 2, characterized in that a coaxial machine is arranged in the power distribution system;
and one end of the coaxial machine is connected with the low-voltage alternating-current power distribution network through a low-voltage alternating-current bus, and the other end of the coaxial machine is connected with the direct-current power distribution network through a low-voltage direct-current bus, so that flexible sequential connection of a medium-voltage direct-current port, a direct/direct-current converter station, the coaxial machine, a low-voltage alternating-current transformer substation and a medium-voltage alternating-current port is realized.
7. The power distribution system grid-connection smooth switching method according to claim 6, wherein when the medium-voltage direct-current port and the medium-voltage alternating-current port are disconnected, the energy storage device stabilizes a low-voltage direct-current bus, and flexible sequential connection of the direct/direct-current converter station, the coaxial machine and the low-voltage alternating-current substation is achieved.
8. A power distribution system grid-connected smooth switching device is characterized in that a high-voltage alternating-current power distribution network, a medium-voltage direct-current power distribution network, a low-voltage alternating-current power distribution network and a low-voltage direct-current power distribution network are configured in a power distribution system, a direct/direct-current converter station is arranged between the medium-voltage direct-current power distribution network and the low-voltage direct-current power distribution network, and a low-voltage alternating-current transformer substation is arranged between the medium-voltage alternating-current power distribution network and the low-voltage alternating-current power distribution network; the grid-connected smooth switching device of the power distribution system comprises:
the monitoring module is used for monitoring the operation data of the direct/direct current converter station and the low-voltage alternating current transformer station;
the judging module is used for judging the states of the direct/direct current converter station and the low-voltage alternating current transformer substation according to the operation data;
the processing module is used for smoothly switching the low-voltage alternating-current transformer substation to supply power to the low-voltage direct-current power distribution network when the state of the direct/direct-current converter station is a fault state; and when the state of the low-voltage alternating-current transformer substation is a fault state, smoothly switching the direct/direct current converter station to supply power to the low-voltage alternating-current power distribution network.
9. A terminal comprising a memory for storing a computer program and a processor for invoking and executing the computer program stored in the memory, characterized in that the processor when executing the computer program implements the steps of the method according to any of the preceding claims 1 to 7.
10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 7.
CN202211722796.2A 2022-12-30 2022-12-30 Grid-connected smooth switching method and device for power distribution system, terminal and storage medium Pending CN115912358A (en)

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