CN113315108B - Method and system for dividing and uniformly managing operation modes of direct-current power distribution network - Google Patents
Method and system for dividing and uniformly managing operation modes of direct-current power distribution network Download PDFInfo
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- CN113315108B CN113315108B CN202110625986.1A CN202110625986A CN113315108B CN 113315108 B CN113315108 B CN 113315108B CN 202110625986 A CN202110625986 A CN 202110625986A CN 113315108 B CN113315108 B CN 113315108B
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- 238000011217 control strategy Methods 0.000 claims abstract description 6
- 238000007142 ring opening reaction Methods 0.000 claims description 12
- 238000001514 detection method Methods 0.000 claims description 9
- 238000012545 processing Methods 0.000 claims description 8
- 238000004891 communication Methods 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 4
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/06—Two-wire systems
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements 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 method and a system for dividing and uniformly managing operation modes of a direct-current power distribution network, belongs to the technical field of direct-current power distribution network control, and particularly divides various typical operation modes of a double-end flexible direct-current distribution network into 3 planned operation modes and 4 unplanned operation modes in order to ensure that the system can maintain stable operation when the operation modes are changed, and provides a switching scheme among the different modes and corresponding control strategies of a converter station under the various operation modes. The strategy enables the direct-current power distribution network to be flexibly switched and maintain the stability of direct-current voltage when the operation of a converter station is switched on or off or the system has N-1 faults, DCSST is disconnected from the network and the like, thereby improving the operation reliability of the direct-current power distribution network and facilitating the realization of flexible interconnection and flexible power control among multiple feeders of the alternating-current power distribution network.
Description
Technical Field
The invention belongs to the technical field of control over direct-current power distribution networks, and particularly relates to a method and a system for dividing and uniformly managing operation modes of a direct-current power distribution network.
Background
In recent years, direct current distribution networks have shown outstanding advantages both technically and economically. The multi-terminal power supply structure can improve the operation reliability of a medium-voltage direct-current power distribution network, and more importantly, the structure can realize flexible interconnection and flexible power control among multiple feeders of an alternating-current power distribution network. The design of the multi-terminal direct-current power grid control system is closely related to the system operation mode, and as the multi-terminal direct-current power grid control system exchanges energy with an alternating-current system through a plurality of converters, any multi-terminal VSC can supply power for a distribution network. At present, master-slave control is widely adopted for operation control of a multi-terminal direct current power distribution network. However, with the development of a direct-current distribution network, the number of converter stations is increasing, devices connected to the distribution network are more and more diverse, the operation mode and the power flow control of the system are more and more complex, and changes of lines and devices in the direct-current distribution network may cause changes of the operation mode of the system, thereby affecting the control mode of each converter station. Therefore, the traditional master-slave control mode faces a complicated mode switching problem. Because the traditional master-slave control has the defects that the switching of the operation modes can not be realized when the communication fault exists and the direct-current voltage is difficult to control stably, the stability of the direct-current voltage can not be ensured under each operation mode.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a direct current power distribution network operation mode division and unified management strategy. Based on the characteristics that the switching on and off of the multi-terminal direct-current power distribution network distribution and utilization equipment has randomness and the operation modes are changeable, the criterion for dividing the multiple operation states of the distribution and utilization equipment and the unified management strategy suitable for the multi-scene operation modes are provided, so that the stability of direct-current voltage is ensured.
The invention solves the practical problem by adopting the following technical scheme:
the method for dividing the operation modes of the direct-current power distribution network and designing the unified management strategy comprises the following steps of:
And 2, aiming at the fact that the system has N-1 faults or DCSST in the system is off-grid and the like, the system operation mode is transited to other operation modes except for 3 plan operation modes, and based on the structure of a double-end ring network, 4 unplanned operation modes are divided into the following steps:
(1) Double-end ring-opening operation mode
When any line of the looped network line in the medium-voltage direct-current power distribution network breaks down, the system is operated in a ring-opening mode, and the double-end ring-opening mode is converted.
(2) Single-ended ring network operation mode
Any converter station connected with the alternating current power grid in the medium-voltage direct current power distribution network quits operation, the alternating current power grid supplies power to the direct current power distribution network only through a single VSC converter station, and the system is still in closed-loop operation.
(3) Single-ended ring-opening operation mode
And (3) switching out any converter station bus connected with the alternating current power grid in the medium-voltage direct current power distribution network, supplying power to the direct current power distribution network by the alternating current power grid through a single VSC converter station, and performing ring-opening operation on the system.
(4) Double-end back-to-back operation mode
In the direct current distribution network system, only power transmission between VSCs connected with the alternating current system exists, and other loads are all off-network, so that direct current interconnection among different alternating current systems is realized. Under this operational mode, double-ended VSC interconnect closes the ring operation.
And step 3, among 3 planned operation modes of the double-end ring network power distribution system, a double-end isolated power supply operation mode is adopted, and each converter station works at V dc A Q mode; the operation of the double-end hand-in-hand and the double-end looped network adopts the same control mode, namely, self-adaptive Droop control (DBD) with Dead zone, so as to ensure the steady-state power distribution characteristic of the system and the dynamic voltage regulation characteristic of transition to an unplanned operation mode when faults/disturbances occur.
And 4, when the operation of the double-end looped network is transited to the unplanned operation, wherein the double-end looped operation and the back-to-back operation are performedThe control mode of the line is the same as that of the double-end ring network, and mode switching is not needed. For single ended ring operation, mode switching is not required if it is due to a slave converter station failure to exit operation, and the slave converter control mode needs to be switched from DBDQ to V if it is due to a master converter station failure to exit operation dc And Q. For single-ended ring-off operation, if the operation is caused by switching out the bus on the converter station side, mode switching is not needed, and if the operation is caused by switching out the bus on the main converter station side, the mode of the slave conversion control mode needs to be switched from DBDQ to V dc Q。
A direct current distribution network operation mode division and unified management system comprises a detection module, a communication module, a calculation processing module and an execution module;
a detection module; the real-time data are used for detecting the change condition of the electric equipment of the power grid and the voltage and current in the power grid system;
the calculation processing module: executing a direct current distribution network operation mode division and unified management method according to the data detected by the detection module;
an execution module: executing switching of the operation modes of the direct-current power distribution network according to the calculation result of the calculation processing module;
a communication module: the device is used for data transmission and control among the detection module, the calculation processing module and the execution module.
The invention has the beneficial effects that:
1. in a multi-terminal direct current power distribution network, aiming at a double-terminal ring network, the state division basis of 4 system unplanned operation modes is provided, and corresponding control strategies of different operation modes are provided.
2. The method provides a unified operation management strategy which takes 3 planned operation modes and 4 unplanned operation modes into consideration and can realize self-adaptive multi-operation scene mode switching in a double-end direct-current power distribution network, provides operation mode division bases, mode switching methods and changes of corresponding control strategies during switching, and improves the steady-state power distribution characteristics and the direct-current voltage stability of the direct-current power distribution network in the multi-operation mode.
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In order to more clearly illustrate the embodiments or technical solutions of the present disclosure, the drawings used in the embodiments or technical solutions of the present disclosure will be briefly described below, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a diagram of operating mode switching;
FIG. 2 is a diagram of a double-ended annular direct distribution network system;
FIG. 3 is a schematic view of a planned operation mode;
fig. 4 is a schematic illustration of an unplanned operation.
Detailed Description
The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are only a part of the embodiments of the present disclosure, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without inventive step, are intended to be within the scope of the present disclosure.
As shown in fig. 1-3, the invention researches division criteria of multiple operation states of a flexible direct-current distribution and utilization system aiming at the characteristic that the switching of power distribution and utilization equipment has randomness, provides a unified management strategy adapting to a multi-scene operation mode, and realizes the plug and play and flexible switching of the power distribution and utilization equipment;
the medium-voltage direct-current power distribution network comprises two VSC converter stations, a double-end annular direct-current power distribution system structure is formed, a VSC1 is set as a master station and works in a constant-voltage control mode, a VSC2 is set as a slave converter station, and the division of the operation modes and the design of a control strategy of the slave converter stations apply the operation mode division and unified management strategy of the direct-current power distribution network provided by the invention:
the first step, dividing the planned operation modes of the direct-current distribution network comprises 1) a double-end isolated power supply operation mode; 3) A double-end hand-in-hand power supply operation mode; 3) And a double-end ring network power supply operation mode.
And secondly, aiming at the fact that the system operation mode is transited to other operation modes except 3 planned operation modes caused by N-1 faults of the system or DCSST off-network in the system and the like, based on the structure of a double-end ring network, 4 unplanned operation modes can be divided into:
as shown in FIG. 4a (1) double end split ring mode of operation
When any one of the looped network lines L1, L2, L3 and L4 (taking the line L4 as an example of the fault) in the medium-voltage direct-current distribution network has a fault, the system is operated in a ring-opening mode, and the two-end ring-opening mode is converted into the double-end ring-opening mode.
As shown in FIG. 4b, (2) single-ended ring network operation mode
Any converter station connected with the alternating current power grid in the medium-voltage direct current power distribution network quits operation (taking VSC2 off-network as an example), the alternating current power grid supplies power to the direct current power distribution network only through a single VSC converter station, and the system is still in closed-loop operation.
As shown in FIG. 4c, (3) single end ring-opening operation mode
And (for example, the VSC2 bus is switched out), the alternating current power grid supplies power to the direct current distribution network only through a single VSC converter station, and the system is operated in an open loop mode.
As shown in fig. 4d (4) double-end back-to-back operation mode
In the direct current distribution network system, only power transmission between VSCs connected with the alternating current system exists, all other loads are off-network, direct current interconnection between different alternating current systems is achieved, and in the operation mode, double-end VSCs are connected with each other and loop closing operation is achieved.
Thirdly, in 3 planned operation modes of the double-end ring network power distribution system, a double-end isolated power supply operation mode is adopted, and each converter station works at V dc A Q mode; the operation of the double-end hand-in-hand and the double-end looped network adopts the same control mode, namely, self-adaptive Droop control (DBD) with Dead zone, so as to ensure the steady-state power distribution characteristic of the system and the dynamic voltage regulation characteristic of transition to an unplanned operation mode when faults/disturbances occur.
And fourthly, when the operation of the double-end looped network is transited to the unplanned operation, wherein the control modes of the double-end ring-opening operation and the back-to-back operation are the same as those of the double-end looped network, and mode switching is not needed. For single ended ring operation, if due to slaveMode switching is not needed due to the fact that the converter station fails to exit from operation, and if the converter station fails to exit from operation, the slave conversion control mode needs to be switched from DBDQ to V dc And Q. For single-ended open loop operation, mode switching is not needed if switching is caused by switching out from the bus on the converter station side, and the mode of the slave conversion control mode needs to be switched from DBDQ to V if switching is caused by switching out from the bus on the main converter station side dc Q。
And fifthly, the control modes including the planned operation mode and the unplanned operation mode and the switching scheme are arranged as shown in the following table.
Principle of operation
In the double-end direct-current power distribution network, 3 planned operation modes and 4 unplanned operation modes are jointly considered, the operation mode division basis, the mode switching method and the change of the corresponding control strategy during switching are given, and the steady-state power distribution characteristic and the direct-current voltage stability of the direct-current power distribution network in multiple operation modes are improved.
In the description of the present specification, reference to the description of "one embodiment," "an example," "a specific example," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing shows and describes the general principles, principal features, and advantages of the disclosure. It will be understood by those skilled in the art that the present disclosure is not limited to the embodiments described above, which are presented solely for illustrating the principles of the disclosure, and that various changes and modifications may be made within the scope of the disclosure as claimed without departing from the spirit and scope of the disclosure.
Claims (4)
1. A method for dividing and uniformly managing the operation modes of a direct current distribution network is characterized by comprising the following steps: setting a plurality of planned operation modes and a plurality of unplanned operation modes for a direct current distribution network, and determining a switching scheme among different operation modes and an operation control strategy corresponding to each operation mode;
the division of the unplanned operation mode is based on a system structure of a double-end ring network;
the planned operation mode comprises, 1) a double-end isolated power supply operation mode; 2) A double-end hand-in-hand power supply operation mode; 3) A double-end ring network power supply operation mode;
the unplanned operating mode includes, 1) a double end split ring operating mode; 2) A single-ended ring network operation mode; 3) Single-ended ring-opening operation mode; 4) A double-end back-to-back operation mode;
among the multiple planned operation modes, a double-end isolated power supply operation mode is adopted, and each converter station works at V dc A Q mode; the operation of the double-end hand-in-hand and the double-end looped network adopts the same control mode, and the main converter station works at V dc A Q mode, wherein the slave converter station adopts droop control with dead zone;
and the double-end ring network is transited to the unplanned operation, wherein the control modes of double-end ring opening operation and back-to-back operation are the same as those of the double-end ring network, mode switching is not needed, for single-end ring operation, if the operation is quitted due to the fault of the slave converter station, mode switching is not needed, and if the operation is quitted due to the fault of the master converter station, the control mode of the slave converter station needs to be switched from DBDQ to V dc Q; for single-ended ring-off operation, if the operation is caused by switching out the bus on the converter station side, mode switching is not needed, and if the operation is caused by switching out the bus on the main converter station side, the mode of the slave conversion control mode needs to be switched from DBDQ to V dc Q。
2. A direct current distribution network operation mode division and unified management system is characterized by comprising a detection module, a communication module, a calculation processing module and an execution module;
a detection module; the real-time data are used for detecting the change condition of the power grid electric equipment and the voltage and current in the power grid system;
the calculation processing module: executing the method for dividing and uniformly managing the operation modes of the direct-current power distribution network according to the data detected by the detection module;
an execution module: executing the method for dividing and uniformly managing the operation modes of the direct-current power distribution network according to the calculation result of the calculation processing module;
a communication module: the device is used for data transmission and control among the detection module, the calculation processing module and the execution module.
3. A storage device, characterized in that the storage device comprises the method for dividing and uniformly managing the operation modes of the dc distribution network according to claim 1.
4. A controller for object detection, wherein the controller is configured to execute the method for dividing and uniformly managing dc distribution network operation modes according to claim 1.
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