CN115800412B - Alternating current/direct current flexible interaction device, system and method for transformer area - Google Patents

Alternating current/direct current flexible interaction device, system and method for transformer area Download PDF

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CN115800412B
CN115800412B CN202211567009.1A CN202211567009A CN115800412B CN 115800412 B CN115800412 B CN 115800412B CN 202211567009 A CN202211567009 A CN 202211567009A CN 115800412 B CN115800412 B CN 115800412B
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alternating current
power
current
control unit
sensitive load
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CN115800412A (en
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任昭颖
刘科研
盛万兴
孟晓丽
贾东梨
叶学顺
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China Electric Power Research Institute Co Ltd CEPRI
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China Electric Power Research Institute Co Ltd CEPRI
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Abstract

The invention provides a device, a system and a method for alternating current/direct current flexible interaction of a transformer area, comprising the following steps: an alternating-current/direct-current conversion link, an electric energy quality control unit, an on-site cooperative control unit and a direct-current port; the on-site cooperative control unit is used for controlling the on-off of the electric energy quality control unit according to the voltage information and the current information of the alternating current sensitive load acquired by the electric energy quality control unit; the power transmission control command is sent to the AC/DC conversion link based on the optimal power scheduling scheme, and the AC/DC conversion link is controlled to supply power to the AC transformer area distribution transformer; and the power output control instruction is also used for sending the power output control instruction to the fusion terminal based on the optimal power scheduling scheme. According to the invention, through the flexible interaction device, the power quality control is carried out on the alternating-current sensitive load and the flexible power control is carried out on the distributed power supply; the flexible power mutual aid between the transformer areas is facilitated, and the power supply reliability and the operation economy of the key load are improved.

Description

Alternating current/direct current flexible interaction device, system and method for transformer area
Technical Field
The invention belongs to the technical field of low-voltage power distribution/alternating current-direct current hybrid power distribution networks, and particularly relates to a transformer area alternating current-direct current flexible interaction device, system and method.
Background
At present, with the large amount of access of wind energy, photovoltaic and other direct-current type distributed power sources and the increasing of direct-current loads of electric vehicle charging stations, large-scale data centers, 5G communication equipment and the like, the problems of unbalanced load phenomenon of a platform area, voltage sag, current harmonic waves and the like are highlighted year by year, and the existing low-voltage power distribution network structure faces three challenges of power supply reliability, distributed power source consumption and electric energy quality.
Aiming at the problems of the three aspects, the traditional technical means and the defects are as follows: firstly, the capacity of a transformer in a transformer area is expanded and upgraded, and the method has the defects that: the impact load brings low load rate and Gao Fenggu difference to the power supply, and the expanded transformer is subjected to larger capacity waste and low in utilization rate; in the process of upgrading and expanding the transformer, planned power failure and the like cannot be avoided, and the cost performance is low in the whole view. Controlling the on-off of a distributed power supply access switch through a fusion terminal; the disadvantage of this method is that: the control mode is coarser, only the on-off of the distributed power supply can be controlled, and the power output of the distributed power supply cannot be controlled. The third method has the defects that by adding the electric energy quality control device: most of the existing power quality control devices aim at individual functions in voltage sag, current harmonic wave, three-phase unbalance and reactive compensation, and the unified power quality regulator has the defects of higher cost, complex control, smaller capacity and limited practical application although the function coverage is more comprehensive.
Aiming at the defects of the traditional means, the power control technology based on the full-control type power electronic device provides a thought for solving the problem, related devices such as an energy router, a flexible interconnection device and the like are generated, the purpose of realizing power conversion and flexible control through a power electronic link is realized, and the energy flow between a distributed power supply and a power distribution network, between alternating current and direct current networks and between different stations is realized, but the novel devices have defects for solving the problems:
(1) The energy router is usually placed in the platform region, can realize the centralized plug and play of multiple distributed power supplies, is accessed into the power distribution network as an energy flow interface, solves the problem of distributed power supply digestion in a single platform region, can not effectively support the optimal scheduling of multiple intervals, and has less involvement in the aspect of electric energy management.
(2) The flexible interconnection device is a back-to-back power electronic device for connecting a plurality of stations, can realize inter-station power mutual compensation and allow distributed power supply centralized access, but does not support distributed power supply distributed plug and play and control adjustment thereof, and does not have power quality management capability.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a flexible alternating current-direct current interaction device for a transformer area, which comprises:
an alternating-current/direct-current conversion link, an electric energy quality control unit, an on-site cooperative control unit and a direct-current port;
the direct current end of the alternating current-direct current conversion link is electrically connected with the direct current port, and the alternating current end is electrically connected with an external alternating current platform area distribution transformer;
one end of the electric energy quality control unit is electrically connected with the direct current port, and the other end of the electric energy quality control unit is electrically connected with an external alternating current sensitive load and an alternating current end of an alternating current-direct current conversion link respectively;
the on-site cooperative control unit is respectively in communication connection with the electric energy quality control unit, the AC/DC conversion link, the AC sensitive load and an external fusion terminal;
the on-site cooperative control unit is used for controlling the on-off of the electric energy quality control unit according to the voltage information and the current information of the alternating current sensitive load acquired by the electric energy quality control unit; the power transmission control method is also used for receiving an optimal power scheduling scheme issued by the fusion terminal, transmitting a power transmission control instruction to the AC-DC conversion link based on the optimal power scheduling scheme, and controlling the AC-DC conversion link to supply power to the AC-DC distribution transformer; and the power output control instruction is sent to the fusion terminal based on the optimal power scheduling scheme.
Preferably, the direct current port is also electrically connected with an external DC/DC breaker;
the DC/DC breaker is used for receiving the power output control instruction sent by the fusion terminal and controlling the power of an external distributed power supply.
Preferably, the flexible interaction device further comprises: an isolation transformer;
one end of the isolation transformer is electrically connected with the alternating current end of the alternating current-direct current conversion link, and the other end of the isolation transformer is electrically connected with one end of an external alternating current platform area distribution transformer and electric energy quality control unit respectively;
the isolation transformer is used for electrically isolating the AC transformer.
Based on the same inventive concept, the invention also provides a platform alternating current-direct current flexible interaction system, which comprises:
the system comprises a plurality of flexible interaction devices, a power distribution system cloud master station, a plurality of alternating current transformer areas, a plurality of fusion terminals, a DC/DC breaker, a distributed power supply and a plurality of alternating current sensitive loads;
each flexible interaction device is respectively connected with one fusion terminal, one AC platform area distribution transformer and one AC sensitive load; all the fusion terminals are in communication connection with a power distribution system cloud master station;
the DC/DC breaker is connected between the distributed power supply and the direct current port;
the flexible interaction device is used for collecting information of the distribution transformer of the alternating current transformer area and the distributed power supply as alternating current/direct current interaction information, uploading the alternating current/direct current interaction information to a cloud master station of a power distribution system through the fusion terminal, receiving an optimal power scheduling scheme issued by the fusion terminal, and sending a power output control instruction to the DC/DC breaker based on the optimal power scheduling scheme; the power supply system is also used for supplying power to the AC transformer area distribution transformer based on the optimal power scheduling scheme; the system is also used for monitoring voltage information and current information of the alternating current sensitive load and carrying out electric energy quality management on the alternating current sensitive load;
the DC/DC breaker is used for executing the power output control instruction and controlling the power of the distributed power supply;
the fusion terminal is used for receiving the AC/DC interaction information and uploading the AC/DC interaction information to the cloud master station of the power distribution system through a wireless private network;
the power distribution system cloud master station is used for carrying out information processing on alternating current and direct current interaction information uploaded by different fusion terminals, determining an optimal power scheduling scheme and transmitting the optimal power scheduling scheme to respective corresponding flexible interaction devices through the corresponding fusion terminals;
wherein the flexible interaction device is the flexible interaction device as described above.
Preferably, the plurality of flexible interaction devices are electrically connected through a direct current port.
Preferably, the plurality of flexible interaction devices are electrically connected through a direct current interconnection bus.
Based on the same inventive concept, the invention also provides a platform alternating current-direct current flexible interaction method, which comprises the following steps:
each flexible interaction device carries out electric energy quality control on the connected alternating current sensitive load according to the acquired voltage information and current information of the corresponding alternating current sensitive load;
each flexible interaction device monitors whether fault signals exist in real time, and when a local cooperative control unit in the flexible interaction device monitors the fault signals, load transfer is conducted on a fault platform region by switching the working modes of the flexible interaction devices in the fault platform region;
when the on-site cooperative control unit does not monitor fault signals, acquiring alternating current/direct current interaction information acquired by the on-site cooperative control unit in each flexible interaction device from a distributed power supply and an alternating current station distribution transformer, uploading the alternating current/direct current interaction information to a power distribution system cloud master station through a fusion terminal, and transmitting a power output control instruction to a DC/DC breaker based on an optimal power scheduling scheme issued by the power distribution system cloud master station; transmitting a power transmission control instruction to an alternating current-direct current conversion link based on the optimal power scheduling scheme;
the optimal power scheduling scheme is obtained by the power distribution system cloud master station after information processing according to the alternating current-direct current interaction information;
the flexible interactive system is the flexible interactive system as described above.
Preferably, the flexible interaction device performs power quality control on the connected ac sensitive load according to the acquired voltage information and current information of the corresponding ac sensitive load, and the flexible interaction device includes:
and the flexible interaction device judges whether the corresponding alternating current sensitive load works normally or not according to the voltage information and the current information, and carries out electric energy quality control on the alternating current sensitive load according to a judging result.
Preferably, the flexible interaction device judges whether the corresponding ac sensitive load works normally according to the voltage information and the current information, and performs power quality control on the ac sensitive load according to a judgment result, and the flexible interaction device comprises:
step S1: the flexible interaction device judges whether the corresponding alternating current sensitive load is in a preset working voltage threshold range according to the voltage information, if not, the alternating current sensitive load is judged to work abnormally, and step S2 is executed; if yes, executing step S3;
step S2: cutting off an alternating current path of the power quality control unit and controlling the power quality control unit to be in a voltage stabilizing mode;
step S3: the flexible interaction device judges whether the corresponding alternating current sensitive load is in a preset working current threshold range according to the current information, if not, the alternating current sensitive load is judged to work abnormally, and step S4 is executed; if yes, judging that the alternating current sensitive load works normally, and executing step S5;
step S4: cutting off an alternating current path of the power quality control unit and controlling the power quality control unit to be in a current harmonic/unbalance control mode;
step S5: and ending the system operation.
Preferably, the switching the working mode of the flexible interaction device in the fault area performs load transfer on the fault area, including:
acquiring a working mode of a flexible interaction device in a fault area;
when the working mode is a constant voltage mode, controlling other flexible interaction devices in the flexible interaction system to change a new host, and switching the working mode of the flexible interaction device to be a V-f control mode;
when the working mode of the flexible interaction device is a constant power mode, the working mode of the flexible interaction device is switched to be a V-f control mode.
Compared with the closest prior art, the invention has the following beneficial effects:
1. the invention provides a transformer area alternating current/direct current flexible interaction device, which comprises: an alternating-current/direct-current conversion link, an electric energy quality control unit, an on-site cooperative control unit and a direct-current port; the direct current end of the alternating current-direct current conversion link is electrically connected with the direct current port, and the alternating current end is electrically connected with an external alternating current platform area distribution transformer; one end of the electric energy quality control unit is electrically connected with the direct current port, and the other end of the electric energy quality control unit is electrically connected with an external alternating current sensitive load and an alternating current end of an alternating current-direct current conversion link respectively; the on-site cooperative control unit is respectively in communication connection with the electric energy quality control unit, the AC/DC conversion link, the AC sensitive load and an external fusion terminal; the on-site cooperative control unit is used for controlling the on-off of the electric energy quality control unit according to the voltage information and the current information of the alternating current sensitive load acquired by the electric energy quality control unit; the power transmission control method is also used for receiving an optimal power scheduling scheme issued by the fusion terminal, transmitting a power transmission control instruction to the AC-DC conversion link based on the optimal power scheduling scheme, and controlling the AC-DC conversion link to supply power to the AC-DC distribution transformer; the power output control instruction is sent to the fusion terminal based on the optimal power scheduling scheme; according to the invention, the power quality control unit is arranged in the flexible interaction device, so that voltage and current monitoring is carried out on the alternating current sensitive load with larger influence on the power quality of the power grid, and the power quality control is carried out on the alternating current sensitive load; the acquired information is processed through the fusion terminal, so that a power scheduling scheme with optimal economy is obtained, and flexible power control of distribution transformer of the distributed power supply and the alternating current station is realized;
2. the system and the method provided by the invention comprise the following steps: the system comprises a plurality of flexible interaction devices, a power distribution system cloud master station, a plurality of alternating current transformer areas, a plurality of fusion terminals, a DC/DC breaker, a distributed power supply and a plurality of alternating current sensitive loads; each flexible interaction device is respectively connected with one fusion terminal, one AC platform area distribution transformer and one AC sensitive load; all the fusion terminals are in communication connection with a power distribution system cloud master station; the DC/DC breaker is connected between the distributed power supply and the direct current port; the flexible interaction device is used for collecting information of the distribution transformer of the alternating current transformer area and the distributed power supply as alternating current/direct current interaction information, uploading the alternating current/direct current interaction information to a cloud master station of a power distribution system through the fusion terminal, receiving an optimal power scheduling scheme issued by the fusion terminal, and sending a power output control instruction to the DC/DC breaker based on the optimal power scheduling scheme; the power supply system is also used for supplying power to the AC transformer area distribution transformer based on the optimal power scheduling scheme; the system is also used for monitoring voltage information and current information of the alternating current sensitive load and carrying out electric energy quality management on the alternating current sensitive load; the DC/DC breaker is used for executing the power output control instruction and controlling the power of the distributed power supply; the fusion terminal is used for receiving the AC/DC interaction information and uploading the AC/DC interaction information to the cloud master station of the power distribution system through a wireless private network; the power distribution system cloud master station is used for carrying out information processing on alternating current and direct current interaction information uploaded by different fusion terminals, determining an optimal power scheduling scheme and transmitting the optimal power scheduling scheme to respective corresponding flexible interaction devices through the corresponding fusion terminals; according to the invention, a plurality of flexible interaction devices are distributed in different areas, information of distributed power sources and alternating-current area distribution transformers in each area is processed through a power distribution system cloud master station, so that an optimal power scheduling scheme is obtained, the information is issued to the corresponding flexible interaction devices through different fusion terminals, interconnection of a plurality of areas is realized, flexible power mutual compensation among the areas is further realized, capacity expansion pressure is relieved, and key load power supply reliability and operation economy are improved.
Drawings
FIG. 1 is a schematic diagram of the structure of a flexible AC/DC interaction device in a transformer area;
fig. 2 is a schematic structural diagram of a flexible ac/dc interaction system for a transformer area according to the present invention;
FIG. 3 is a schematic diagram of the structure of the AC/DC flexible interaction system of the DC bus type transformer area provided by the invention;
fig. 4 is a schematic flow chart of a flexible interaction method of ac and dc in a transformer area according to the present invention.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the drawings.
Example 1:
the invention provides a transformer area alternating current-direct current flexible interaction device, the structure composition schematic diagram is shown in figure 1, comprising:
an alternating-current/direct-current conversion link, an electric energy quality control unit, an on-site cooperative control unit and a direct-current port;
the direct current end of the alternating current-direct current conversion link is electrically connected with the direct current port, and the alternating current end is electrically connected with an external alternating current platform area distribution transformer;
one end of the electric energy quality control unit is electrically connected with the direct current port, and the other end of the electric energy quality control unit is electrically connected with an external alternating current sensitive load and an alternating current end of an alternating current-direct current conversion link respectively;
the on-site cooperative control unit is respectively in communication connection with the electric energy quality control unit, the AC/DC conversion link, the AC sensitive load and an external fusion terminal;
the on-site cooperative control unit is used for controlling the on-off of the electric energy quality control unit according to the voltage information and the current information of the alternating current sensitive load acquired by the electric energy quality control unit; the power transmission control method is also used for receiving an optimal power scheduling scheme issued by the fusion terminal, transmitting a power transmission control instruction to the AC-DC conversion link based on the optimal power scheduling scheme, and controlling the AC-DC conversion link to supply power to the AC-DC distribution transformer; the power output control instruction is sent to the fusion terminal based on the optimal power scheduling scheme; the internal program of the local cooperative control unit comprises an AC/DC conversion link power control loop, an electric energy quality control unit voltage/current control loop and the like, and has the main functions of three aspects: firstly, two-way communication is carried out with the fusion terminal through a communication link, an optimal power scheduling scheme issued by the fusion terminal is received, and after the optimal power scheduling scheme is calculated according to an internal program, on one hand, a control signal is sent to an alternating-current/direct-current conversion link through the internal communication to enable the optimal power scheduling scheme to work according to a given power transmission value, on the other hand, a control signal is sent to a DC/DC breaker through the fusion terminal, and the DC/DC breaker is connected with a distributed power supply in a distributed power supply platform area through a direct-current bus, so that the power output of the distributed power supply is controlled; secondly, the communication between the local cooperative control units is adopted to realize the bottom execution of power transmission and ensure the voltage stability under different working conditions; thirdly, the voltage and current conditions of an alternating current sensitive load interface are monitored in real time through internal communication, and accordingly, an on-off instruction of a fast switch in an electric energy quality control unit and start-stop and control of a DC/AC link are issued;
an AC/DC topological structure is adopted in the AC/DC conversion link, so that the bidirectional conversion between three-phase AC and DC is realized, and the AC/DC conversion link is a core hardware foundation for realizing power mutual aid in a station area;
the power quality control unit adopts a DC/AC topological structure and comprises a fast switch and an outlet voltage and current monitoring link, and is used for leading out an alternating current sensitive load interface to supply power to an alternating current sensitive load with high power supply voltage requirement or large influence on the power quality of a power grid.
The direct current port is also electrically connected with an external DC/DC breaker;
the DC/DC breaker is used for receiving the power output control instruction sent by the fusion terminal and controlling the power of an external distributed power supply;
the flexible interaction device further comprises: an isolation transformer;
one end of the isolation transformer is electrically connected with the alternating current end of the alternating current-direct current conversion link, and the other end of the isolation transformer is electrically connected with one end of an external alternating current platform area distribution transformer and electric energy quality control unit respectively;
the isolation transformer is used for electrically isolating the AC transformer area distribution transformer;
the isolation transformer adopts a Y-delta connection method, so that the fault can be prevented from being conducted to the alternating current side, and the normal work of the original alternating current transformer area is affected;
according to the flexible interaction device, the voltage and the current of the alternating current sensitive load with larger influence on the electric energy quality of the power grid are monitored through the internal electric energy quality control unit, so that the electric energy quality control of the alternating current sensitive load in the transformer area can be realized; the acquired information of the distributed power supply and the information of the AC transformer area distribution transformer are processed through the fusion terminal to obtain an optimal power scheduling scheme, so that flexible power control of the distributed power supply and the AC transformer area distribution transformer is realized; the alternating current sensitive load is an important load with high requirements on power supply voltage and a load with serious current harmonic and three-phase imbalance phenomena, and the alternating current sensitive load is connected to an outlet of an electric energy quality control unit, so that comprehensive electric energy quality control including voltage stabilization, current harmonic compensation control and three-phase imbalance control can be realized, high-quality power supply of the important load is ensured, and adverse effects of harmonic and three-phase imbalance on a power grid are reduced.
The specific implementation process of the electric energy quality control comprises the following steps: monitoring port voltage and current of an alternating current sensitive load by each flexible interaction device, and if the port voltage meets the normal working requirement of the alternating current sensitive load and the current harmonic wave, the three-phase imbalance and the reactive power level of the port voltage are in the allowable range, keeping an alternating current channel switch in the electric energy quality control unit closed, wherein a DC/AC part in the electric energy quality control unit does not need to work; otherwise, the AC access switch is disconnected, and the DC/AC part is started and controlled to work by a built-in control algorithm in the local cooperative control unit, so that the output of the AC sensitive load port is converted into an AC power supply after the DC/AC part is treated, and the electric energy quality treatment can be realized.
The invention realizes the comprehensive treatment of the electric energy quality including the voltage stabilizing output facing important load and the current harmonic treatment facing high harmonic or unbalanced load, three-phase unbalanced treatment and the like in the electric energy quality treatment process, and realizes the integration of power flexible control and electric energy quality treatment; in addition, by means of the existing communication links among the fusion terminal, the distributed power supply and the DC/DC breaker, not only can the on-off of the distributed power supply be controlled functionally, but also the power output of the distributed power supply can be controlled, and the defect of the function of the fusion terminal is overcome.
Example 2:
based on the same inventive concept, the invention also provides a platform alternating current-direct current flexible interaction system, the structural composition schematic diagram is shown in fig. 2, and the system comprises:
the system comprises a plurality of flexible interaction devices, a power distribution system cloud master station, a plurality of alternating current transformer areas, a plurality of fusion terminals, a DC/DC breaker, a distributed power supply and a plurality of alternating current sensitive loads;
each flexible interaction device is respectively connected with one fusion terminal, one AC platform area distribution transformer and one AC sensitive load; all the fusion terminals are in communication connection with a power distribution system cloud master station;
the DC/DC breaker is connected between the distributed power supply and the direct current port;
the flexible interaction device is used for collecting information of the distribution transformer of the alternating current transformer area and the distributed power supply as alternating current/direct current interaction information, uploading the alternating current/direct current interaction information to a cloud master station of a power distribution system through the fusion terminal, receiving an optimal power scheduling scheme issued by the fusion terminal, and sending a power output control instruction to the DC/DC breaker based on the optimal power scheduling scheme; the power supply system is also used for supplying power to the AC transformer area distribution transformer based on the optimal power scheduling scheme; the system is also used for monitoring voltage information and current information of the alternating current sensitive load and carrying out electric energy quality management on the alternating current sensitive load;
the DC/DC breaker is used for executing the power output control instruction and controlling the power of the distributed power supply;
the fusion terminal is used for receiving the AC/DC interaction information and uploading the AC/DC interaction information to the cloud master station of the power distribution system through a wireless private network;
the power distribution system cloud master station is used for carrying out information processing on alternating current and direct current interaction information uploaded by different fusion terminals, determining an optimal power scheduling scheme and transmitting the optimal power scheduling scheme to respective corresponding flexible interaction devices through the corresponding fusion terminals;
the alternating current-direct current interaction information comprises alternating current transformer area distribution transformation output information and distributed power supply power generation information, and is uploaded to a fusion terminal through an existing communication link and uploaded to a power distribution system cloud master station through a wireless private network by the fusion terminal; and processing the collected information by a functional module in a cloud master station of the power distribution system to obtain an optimal power scheduling scheme, and transmitting the optimal power scheduling scheme to an on-site cooperative control unit of the flexible interaction device through a fusion terminal.
The local cooperative control unit receives an optimal power scheduling scheme, generates a power output control instruction and a power transmission control instruction according to the optimal power scheduling scheme, works the power transmission control instruction according to a specified power value through an internal communication control AC/DC conversion link of the device, so that power supply for the AC station area is realized, the local cooperative control unit communicates with local cooperative control units and DC/DC circuit breakers of other flexible interaction devices through communication links, and executes the power output control instruction through the DC/DC circuit breakers, thereby realizing flexible regulation and control of power of distributed power supplies in a station area, and realizing bottom execution of the power instruction by determining that one party of the distributed power supplies is controlled to be constant voltage output and the other parties are constant in power output; when the method is applied to a plurality of areas, the collected alternating current-direct current interaction information is uploaded to a power distribution system cloud master station through a fusion terminal, and the alternating current-direct current interaction information is processed through the power distribution system cloud master station to obtain an optimal power scheduling scheme; when the method is applied to a single area, the optimal power scheduling scheme is directly integrated through the fusion terminal and is issued to the corresponding local cooperative control unit;
the flexible interaction device is the flexible interaction device as described above.
The plurality of flexible interaction devices are electrically connected through the direct current ports.
The plurality of flexible interaction devices are electrically connected through a direct current interconnection bus, and a structural schematic diagram is shown in fig. 3.
When the plurality of flexible interaction devices are electrically connected through the direct current ports, the method is suitable for a scene with a centralized distributed power supply;
when the plurality of flexible interaction devices are electrically connected through the direct current interconnection bus, the flexible interaction device is suitable for a distributed power supply dispersion scene, and the direct current interconnection bus provides an energy path for power interaction between the distributed power supply and the direct current ports of the plurality of areas;
the AC/DC flexible interaction system for the transformer area can solve the problems that the form and the expandability of integrated equipment formed by integrating a plurality of back-to-back AC/DC devices inside the conventional flexible interconnection device are poor; the distributed power supplies can be arranged in a centralized manner and can be respectively arranged in the power distribution rooms of the respective transformer areas and are interconnected in a direct current bus mode, so that the distributed power supplies in distributed arrangement can be conveniently used in a plug-and-play manner; the direct current ports are closely connected, so that the centralized access of the distributed power supply is facilitated, the flexible power mutual compensation among the transformer areas is realized, the capacity expansion pressure is relieved, and the power supply reliability and the operation economy of the key load are improved.
Example 3:
based on the same inventive concept, the invention also provides a platform alternating current-direct current flexible interaction method, a flow diagram is shown in fig. 4, and the method comprises the following steps:
each flexible interaction device carries out electric energy quality control on the connected alternating current sensitive load according to the acquired voltage information and current information of the corresponding alternating current sensitive load;
each flexible interaction device monitors whether fault signals exist in real time, and when a local cooperative control unit in the flexible interaction device monitors the fault signals, load transfer is conducted on a fault platform region by switching the working modes of the flexible interaction devices in the fault platform region;
when the on-site cooperative control unit does not monitor fault signals, acquiring alternating current/direct current interaction information acquired by the on-site cooperative control unit in each flexible interaction device from a distributed power supply and an alternating current station distribution transformer, uploading the alternating current/direct current interaction information to a power distribution system cloud master station through a fusion terminal, and transmitting a power output control instruction to a DC/DC breaker based on an optimal power scheduling scheme issued by the power distribution system cloud master station; transmitting a power transmission control instruction to an alternating current-direct current conversion link based on the optimal power scheduling scheme;
the optimal power scheduling scheme is obtained by the power distribution system cloud master station after information processing according to the alternating current-direct current interaction information;
the flexible interactive system is the flexible interactive system as described above.
The flexible interaction device carries out electric energy quality control on the connected alternating current sensitive load according to the acquired voltage information and current information of the corresponding alternating current sensitive load, and the flexible interaction device comprises:
and the flexible interaction device judges whether the corresponding alternating current sensitive load works normally or not according to the voltage information and the current information, and carries out electric energy quality control on the alternating current sensitive load according to a judging result.
The flexible interaction device judges whether the corresponding alternating current sensitive load works normally according to the voltage information and the current information, and carries out electric energy quality control on the alternating current sensitive load according to a judging result, and the flexible interaction device comprises:
step S1: the flexible interaction device judges whether the corresponding alternating current sensitive load is in a preset working voltage threshold range according to the voltage information, if not, the alternating current sensitive load is judged to work abnormally, and step S2 is executed; if yes, executing step S3;
step S2: cutting off an alternating current path of the power quality control unit and controlling the power quality control unit to be in a voltage stabilizing mode;
step S3: the flexible interaction device judges whether the corresponding alternating current sensitive load is in a preset working current threshold range according to the current information, if not, the alternating current sensitive load is judged to work abnormally, and step S4 is executed; if yes, judging that the alternating current sensitive load works normally, and executing step S5;
step S4: cutting off an alternating current path of the power quality control unit and controlling the power quality control unit to be in a current harmonic/unbalance control mode;
step S5: ending the system operation;
the load transfer is carried out on the fault area by switching the working mode of the flexible interaction device in the fault area, and the load transfer comprises the following steps:
acquiring a working mode of a flexible interaction device in a fault area;
when the working mode is a constant voltage mode, controlling other flexible interaction devices in the flexible interaction system to change a new host, and switching the working mode of the flexible interaction device to be a V-f control mode;
when the working mode of the flexible interaction device is a constant power mode, switching the working mode of the flexible interaction device to a V-f control mode;
a specific embodiment is used for describing the alternating current/direct current flexible interaction method of the transformer area, and three transformer areas are interconnected for example, when one transformer area fails, if the transformer area flexible interaction device is controlled by constant power, the rest interconnected system can be ensured to be stable by direct cutting; if the area is controlled by a constant voltage, voltage instability can occur under the condition of not changing the control mode of the system, and the normal operation of the system is endangered;
therefore, the local cooperative control unit needs to determine whether the control mode of the flexible interactive system needs to be switched according to the monitoring condition of the platform area and the control mode of the local cooperative control unit in combination with the communication links among the local cooperative control units in the plurality of areas, and the specific switching mode is as follows: when the local cooperative control unit monitors the fault of the platform region, if the local cooperative control unit is in constant power control, the control mode is not required to be changed temporarily, and the local cooperative control unit is directly converted into V-f control after the subsequent fault is isolated; if the system is in constant voltage control, one of the other devices is selected again as a host computer to take over the voltage control right through a communication link, and the stable operation of the system is ensured;
when the fault part of the fault area is isolated, the flexible interaction device of the fault area is switched to V-f control to supply power to the alternating current side, so that the load transfer of the non-fault part can be realized;
the important load with high requirements on the power supply voltage and the load with serious current harmonic wave and three-phase imbalance phenomenon are called sensitive load, and are connected to the outlet of the power quality control unit, so that the comprehensive control of the power quality including voltage stabilization, current harmonic wave compensation control and three-phase imbalance control can be realized, the high-quality power supply of the important load is ensured, and the adverse effect of harmonic wave and three-phase imbalance on a power grid is reduced; the specific mode of the electric energy quality control is as follows: monitoring the voltage and the current of a sensitive load port by each flexible interaction device, and if the port voltage meets the normal working requirement of an alternating current sensitive load and the current harmonic wave, the three-phase imbalance and the reactive power level of the port voltage are in the allowable range, keeping an alternating current channel switch in the electric energy quality control unit closed, wherein the DC/AC part in the electric energy quality control unit does not need to work; otherwise, the AC access switch is disconnected, and the DC/AC part is started and controlled to work by a built-in control algorithm in the local cooperative control unit, so that the output of the AC sensitive load port is converted into an AC power supply after the DC/AC part is treated, and the electric energy quality treatment can be realized.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of protection thereof, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that various changes, modifications or equivalents may be made to the specific embodiments of the application after reading the present invention, and these changes, modifications or equivalents are within the scope of protection of the claims appended hereto.

Claims (9)

1. The utility model provides a flexible interactive installation of district alternating current-direct current which characterized in that includes: an alternating-current/direct-current conversion link, an electric energy quality control unit, an on-site cooperative control unit and a direct-current port;
the direct current end of the alternating current-direct current conversion link is electrically connected with the direct current port, and the alternating current end is electrically connected with an external alternating current platform area distribution transformer;
one end of the electric energy quality control unit is electrically connected with the direct current port, and the other end of the electric energy quality control unit is electrically connected with an external alternating current sensitive load and an alternating current end of an alternating current-direct current conversion link respectively;
the on-site cooperative control unit is respectively in communication connection with the electric energy quality control unit, the AC/DC conversion link, the AC sensitive load and an external fusion terminal;
the on-site cooperative control unit is used for controlling the on-off of the electric energy quality control unit according to the voltage information and the current information of the alternating current sensitive load acquired by the electric energy quality control unit; the power transmission control method is also used for receiving an optimal power scheduling scheme issued by the fusion terminal, transmitting a power transmission control instruction to the AC-DC conversion link based on the optimal power scheduling scheme, and controlling the AC-DC conversion link to supply power to the AC-DC distribution transformer; the power output control instruction is sent to the fusion terminal based on the optimal power scheduling scheme; the internal program of the local cooperative control unit comprises an alternating-current/direct-current conversion link power control loop and an electric energy quality control unit voltage/current control loop; the specific implementation process comprises the following steps: firstly, two-way communication is carried out with the fusion terminal through a communication link, an optimal power scheduling scheme issued by the fusion terminal is received, and after the optimal power scheduling scheme is calculated according to an internal program, on one hand, a control signal is sent to an alternating-current/direct-current conversion link through the internal communication to enable the optimal power scheduling scheme to work according to a given power transmission value, on the other hand, a control signal is sent to a DC/DC breaker through the fusion terminal, and the DC/DC breaker is connected with a distributed power supply in a distributed power supply platform area through a direct-current bus, so that the power output of the distributed power supply is controlled; secondly, the communication between the local cooperative control units is adopted to realize the bottom execution of power transmission and ensure the voltage stability under different working conditions; thirdly, the voltage and current conditions of an alternating current sensitive load interface are monitored in real time through internal communication, and accordingly, an on-off instruction of a fast switch in an electric energy quality control unit and start-stop and control of a DC/AC link are issued;
the on-site cooperative control unit controls the on-off of the power quality control unit according to the voltage information and the current information of the alternating current sensitive load collected by the power quality control unit, and comprises the following components:
step S1: judging whether the corresponding alternating current sensitive load is in a preset working voltage threshold range according to the voltage information of the alternating current sensitive load, if not, judging that the alternating current sensitive load works abnormally, and executing step S2; if yes, executing step S3;
step S2: cutting off an alternating current path of the power quality control unit and controlling the power quality control unit to be in a voltage stabilizing mode;
step S3: judging whether the corresponding alternating current sensitive load is in a preset working current threshold range according to the current information of the alternating current sensitive load, if not, judging that the alternating current sensitive load works abnormally, and executing step S4; if yes, judging that the alternating current sensitive load works normally, and executing step S5;
step S4: cutting off an alternating current path of the power quality control unit and controlling the power quality control unit to be in a current harmonic/unbalance control mode;
step S5: and ending the system operation.
2. The apparatus of claim 1, wherein the direct current port is further electrically connected to an external DC/DC breaker;
the DC/DC breaker is used for receiving the power output control instruction sent by the fusion terminal and controlling the power of an external distributed power supply.
3. The apparatus as recited in claim 1, further comprising: an isolation transformer;
one end of the isolation transformer is electrically connected with the alternating current end of the alternating current-direct current conversion link, and the other end of the isolation transformer is electrically connected with one end of an external alternating current platform area distribution transformer and electric energy quality control unit respectively;
the isolation transformer is used for electrically isolating the AC transformer.
4. A flexible ac/dc interaction system for a bay, comprising: the system comprises a plurality of flexible interaction devices, a power distribution system cloud master station, a plurality of alternating current transformer areas, a plurality of fusion terminals, a DC/DC breaker, a distributed power supply and a plurality of alternating current sensitive loads;
each flexible interaction device is respectively connected with one fusion terminal, one AC platform area distribution transformer and one AC sensitive load;
all the fusion terminals are in communication connection with a power distribution system cloud master station;
the DC/DC breaker is connected between the distributed power supply and the direct current port;
the flexible interaction device is used for collecting information of the distribution transformer of the alternating current transformer area and the distributed power supply as alternating current/direct current interaction information, uploading the alternating current/direct current interaction information to a cloud master station of a power distribution system through the fusion terminal, receiving an optimal power scheduling scheme issued by the fusion terminal, and sending a power output control instruction to the DC/DC breaker based on the optimal power scheduling scheme; the power supply system is also used for supplying power to the AC transformer area distribution transformer based on the optimal power scheduling scheme; the system is also used for monitoring voltage information and current information of the alternating current sensitive load and carrying out electric energy quality management on the alternating current sensitive load;
the DC/DC breaker is used for executing the power output control instruction and controlling the power of the distributed power supply;
the fusion terminal is used for receiving the AC/DC interaction information and uploading the AC/DC interaction information to the cloud master station of the power distribution system through a wireless private network;
the power distribution system cloud master station is used for carrying out information processing on alternating current and direct current interaction information uploaded by different fusion terminals, determining an optimal power scheduling scheme and transmitting the optimal power scheduling scheme to respective corresponding flexible interaction devices through the corresponding fusion terminals;
monitoring voltage information and current information of the alternating current sensitive load in each flexible interaction device, and carrying out electric energy quality control on the alternating current sensitive load, wherein the method specifically comprises the following steps:
each flexible interaction device monitors the port voltage and current of the corresponding alternating current sensitive load, and if the port voltage meets the normal working requirement of the alternating current sensitive load and the current harmonic wave, the three-phase imbalance and the reactive power level of the port voltage are in the allowable range, an alternating current channel switch in the electric energy quality control unit is kept closed, and a DC/AC part in the electric energy quality control unit does not need to work; otherwise, the AC access switch is disconnected, and the DC/AC part is started and controlled to work by a built-in control algorithm in the local cooperative control unit, so that the output of the AC sensitive load port is converted into an AC power supply after the DC/AC part is treated, and the electric energy quality treatment can be realized;
wherein the flexible interaction means is a flexible interaction means according to any of claims 1 to 3.
5. The system of claim 4, wherein the plurality of flexible interaction means are electrically connected via a dc port.
6. The system of claim 4, wherein the plurality of flexible interaction means are electrically connected by a dc interconnect bus.
7. A platform area alternating current/direct current flexible interaction method is characterized by comprising the following steps:
each flexible interaction device carries out electric energy quality control on the connected alternating current sensitive load according to the acquired voltage information and current information of the corresponding alternating current sensitive load;
each flexible interaction device monitors whether fault signals exist in real time, and when a local cooperative control unit in the flexible interaction device monitors the fault signals, load transfer is conducted on a fault platform region by switching the working modes of the flexible interaction devices in the fault platform region;
when the on-site cooperative control unit does not monitor fault signals, acquiring alternating current/direct current interaction information acquired by the on-site cooperative control unit in each flexible interaction device from a distributed power supply and an alternating current station distribution transformer, uploading the alternating current/direct current interaction information to a power distribution system cloud master station through a fusion terminal, and transmitting a power output control instruction to a DC/DC breaker based on an optimal power scheduling scheme issued by the power distribution system cloud master station; transmitting a power transmission control instruction to an alternating current-direct current conversion link based on the optimal power scheduling scheme;
the optimal power scheduling scheme is obtained by the power distribution system cloud master station after information processing according to the alternating current-direct current interaction information;
the flexible interactive system is the flexible interactive system of any one of claims 4-6;
the method for transferring the load to the fault area by switching the working mode of the flexible interaction device in the fault area comprises the following steps:
acquiring a working mode of a flexible interaction device in a fault area;
when the working mode is a constant voltage mode, controlling other flexible interaction devices in the flexible interaction system to change a new host, and switching the working mode of the flexible interaction device to be a V-f control mode;
when the working mode of the flexible interaction device is a constant power mode, the working mode of the flexible interaction device is switched to be a V-f control mode.
8. The method of claim 7, wherein the flexible interaction device performs power quality management on the connected ac sensitive load according to the acquired voltage information and current information of the corresponding ac sensitive load, comprising:
and the flexible interaction device judges whether the corresponding alternating current sensitive load works normally or not according to the voltage information and the current information, and carries out electric energy quality control on the alternating current sensitive load according to a judging result.
9. The method of claim 8, wherein the flexible interaction device determines whether the corresponding ac sensitive load is operating normally according to the voltage information and the current information, and performs power quality management on the ac sensitive load according to the determination result, including:
step S1: the flexible interaction device judges whether the corresponding alternating current sensitive load is in a preset working voltage threshold range according to the voltage information, if not, the alternating current sensitive load is judged to work abnormally, and step S2 is executed; if yes, executing step S3;
step S2: cutting off an alternating current path of the power quality control unit and controlling the power quality control unit to be in a voltage stabilizing mode;
step S3: the flexible interaction device judges whether the corresponding alternating current sensitive load is in a preset working current threshold range according to the current information, if not, the alternating current sensitive load is judged to work abnormally, and step S4 is executed; if yes, judging that the alternating current sensitive load works normally, and executing step S5;
step S4: cutting off an alternating current path of the power quality control unit and controlling the power quality control unit to be in a current harmonic/unbalance control mode;
step S5: and ending the system operation.
CN202211567009.1A 2022-12-07 2022-12-07 Alternating current/direct current flexible interaction device, system and method for transformer area Active CN115800412B (en)

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