CN110783954A - Method and system for controlling transmission power of island system - Google Patents
Method and system for controlling transmission power of island system Download PDFInfo
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- CN110783954A CN110783954A CN201911053086.3A CN201911053086A CN110783954A CN 110783954 A CN110783954 A CN 110783954A CN 201911053086 A CN201911053086 A CN 201911053086A CN 110783954 A CN110783954 A CN 110783954A
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- 230000005540 biological transmission Effects 0.000 title claims abstract description 13
- 230000001276 controlling effect Effects 0.000 claims description 10
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- 230000001105 regulatory effect Effects 0.000 claims description 2
- 230000033228 biological regulation Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 9
- 230000000903 blocking effect Effects 0.000 description 8
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Classifications
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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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- 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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- Dc-Dc Converters (AREA)
Abstract
The invention discloses a method and a system for controlling transmission power of an island system, and belongs to the technical field of power systems. The method comprises the following steps: obtaining an island system current signal and a power signal; determining whether the island system fault is a single-pole lockout fault or not and determining whether the island system fault is a direct-current voltage adjustable range of a converter station of the island system; boosting the direct current voltage of the converter station of the island system within the adjustable range, reducing the direct current of the converter station to a preset range, and obtaining the normal pole power value of the converter station; and determining that the normal pole power value of the converter station is reduced and the normal pole power value is reduced to the inflow power value of the converter station, stopping boosting the direct-current voltage of the converter station of the island system and reducing the direct-current of the converter station. The method is simple in process and easy to implement, and can economically and efficiently implement fault ride-through of the new energy unit of the island system.
Description
Technical Field
The present invention relates to the field of power system technology, and more particularly, to a method and system for controlling transmission power of an island system.
Background
When the new energy generating set works in an island operation mode and is directly sent out through a flexible direct current transmission system, a converter station needs to adopt a passive control mode, the converter station provides grid-connected voltage and frequency support for the passive system, and because the inflow size of power cannot be informed, when a single-pole locking fault occurs, the power flowing in the converter station and the direct current component and the alternating current component of bridge arm current form a positive correlation relationship,
wherein i
armpFor upper arm current, i
armnIs the lower bridge arm current, I
dcIs a direct current i
vaFor alternating current, P is the power inrush from the converter station.
Thus, the current of the upper and lower bridge arms of the converter station can be changed into an equation with the independent variable being the power P. Each power corresponds to a bridge arm current.
When single-pole blocking occurs, the inrush power of the normal pole is the surplus power of the blocking pole besides the normal power, the power is changed into P',
P'＝P+VP
wherein, P is the inrush power when not in fault, and VP is the surplus power needed to be transferred after fault.
When single-pole locking happens, power rises, so that bridge arm current rises, time is needed for fan load shedding, and the direct-current voltage U is increased based on an allowable range of action protection during the period from the occurrence of a fault to the completion of fan load shedding
dcTo a dc voltage protection limit value U
dcrproUnder the condition of (3), the bridge arm current rise caused by surplus power can be greatly reduced, so that the maximum value of the bridge arm current is lower than a protection value i of bridge arm overcurrent protection
armpro。
Due to the inverse time-limit action protection principle, the magnitude of the over-current protection value and the direct-current voltage protection value of the bridge arm is a function inversely proportional to time.
Wherein i
armAnd U
dcAnd x and y are inverse time-lag protection coefficients for bridge arm current and direct current voltage of the converter station when the converter station normally operates.
The bridge arm overcurrent protection value generally takes an effective value of current as a judgment reference, because the bridge arm current contains direct current bias, taking the bridge arm as an example, the boundary equation of the bridge arm current at the moment is as follows:
taking the obtained result as a boundary condition, the method can obtain the standard electrode converter stationMaximum power P
max：
In the input control mode, the required power consumption is reduced to
P
cooper＝P+VP-P
max＜VP (6)
From the analysis, after the single-stage locking, the normal pole of the converter station carries the power of the fault pole, the power can cause the bridge arm current of the converter station to rise, and when the bridge arm current of the converter station is larger than the overcurrent protection fixed value, the normal pole of the converter station can be locked due to the overcurrent of the bridge arm, so that the new energy is off-line in a large area.
Disclosure of Invention
In view of the above problem, the present invention provides a method for controlling transmission power of an island system, including:
determining that a new energy true bipolar flexible-direct island system has a fault, and acquiring a current signal and a power signal of the island system;
determining whether the island system fault is a single-pole blocking fault or not according to the current signal and the power signal, and acquiring the adjustable range of the direct-current voltage of the converter station of the island system according to a preset inverse time-limit protection coefficient and overcurrent time of the island system after the island system is determined to be the single-pole blocking fault;
boosting the direct current voltage of the converter station of the island system within the adjustable range, reducing the direct current of the converter station to a preset range, and determining the normal pole power value of the converter station;
and determining that the normal pole power value of the converter station is reduced and the normal pole power value is reduced to the inflow power value of the converter station, stopping boosting the direct-current voltage of the converter station of the island system and reducing the direct-current of the converter station.
Optionally, the adjustable range is 1-1.299 p.u.
Optionally, the preset range is 1-1.768 p.u.
Optionally, the method further comprises: and after the direct current of the converter station is reduced to a preset range, the inverse time limit protection of the direct current of the converter station is not operated.
Optionally, the method further comprises: and after the normal pole power value of the converter station is determined to be reduced and is reduced to the inflow power value of the converter station, restoring the direct current voltage of the converter station of the island system to the reference voltage of the direct current voltage of the converter station.
The invention also provides a system for controlling the transmission power of the island system, which comprises:
the parameter acquisition module is used for determining that a new energy true bipolar flexible-straight island system has a fault and acquiring a current signal and a power signal of the island system;
the fault judgment module is used for determining whether the island system fault is a single-pole latching fault or not according to the current signal and the power signal, and determining the adjustable range of the direct-current voltage of the converter station of the island system according to a preset inverse time-limit protection coefficient and overcurrent time of the island system after the island system is determined to be the single-pole latching fault;
the regulating module is used for boosting the direct current voltage of the converter station of the island system within the adjustable range and reducing the direct current of the converter station to a preset range to obtain a normal pole power value of the converter station;
and the judgment module is used for determining that the normal pole power value of the converter station is reduced and is reduced to the current inflow power value of the converter station, stopping boosting the direct-current voltage of the converter station of the island system and stopping reducing the direct-current of the converter station.
Optionally, the adjustable range is 1-1.299 p.u.
Optionally, the preset range is 1-1.768 p.u.
Optionally, the adjusting module is configured to reduce the dc current of the converter station to a preset range, and then disable the inverter protection of the dc current of the converter station.
Optionally, the determining module is configured to recover the dc voltage of the converter station of the island system to a reference voltage of the dc voltage of the converter station after determining that the normal pole power value of the converter station decreases and decreases to the inflow power value of the converter station.
The method is simple in process and easy to implement, and can economically and efficiently implement fault ride-through of the new energy unit of the island system.
Drawings
Fig. 1 is a flowchart of a method for controlling transmission power of an island system according to the present invention;
fig. 2 is a system structure diagram for controlling transmission power of an island system according to the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
The present invention provides a method for controlling transmission power of an island system, as shown in fig. 1, including:
determining that a new energy true bipolar flexible-direct island system has a fault, and acquiring a current signal and a power signal of the island system;
determining whether the island system fault is a single-pole blocking fault or not according to the current signal and the power signal, and determining the adjustable range of the direct-current voltage of the converter station of the island system to be 1-1.299 p.u. according to the preset inverse time-limit protection coefficient and overcurrent time of the island system after the island system is determined to be the single-pole blocking fault;
boosting the direct current voltage of the converter station of the island system within the adjustable range, reducing the direct current of the converter station to a preset range of 1-1.768 p.u., and after reducing the direct current of the converter station to the preset range, enabling the direct current inverse time-limit protection of the converter station not to act to obtain the normal pole power value of the converter station;
determining that the normal pole power value of the converter station is reduced and is reduced to the inflow power value of the converter station, stopping boosting the direct current voltage of the converter station of the island system and reducing the direct current of the converter station, and recovering the direct current voltage of the converter station of the island system to the reference voltage of the direct current voltage of the converter station
The present invention also provides a system 200 for controlling transmission power of an islanding system, as shown in fig. 2, including:
the parameter acquisition module 201 is used for determining that a new energy true bipolar flexible-direct island system has a fault and acquiring a current signal and a power signal of the island system;
the fault judgment module 202 determines whether the island system fault is a single-pole blocking fault according to the current signal and the power signal, and obtains an adjustable range of direct-current voltage of a converter station of the island system, which is 1-1.299 p.u., according to a preset inverse time-limit protection coefficient and overcurrent time of the island system after the island system is determined to be the single-pole blocking fault;
the adjusting module 203 is used for boosting the direct current voltage of the converter station of the island system within the adjustable range and reducing the direct current of the converter station to a preset range of 1-1.768 p.u., so that the inverse time limit protection of the direct current of the converter station does not act, and the normal pole power value of the converter station is obtained;
the determining module 204 determines that the normal pole power value of the converter station decreases and decreases to the converter station inflow power value, stops boosting the dc voltage of the converter station of the island system and reducing the dc current of the converter station, and restores the dc voltage of the converter station of the island system to the reference voltage of the dc voltage of the converter station.
The method is simple in process and easy to implement, and can economically and efficiently implement fault ride-through of the new energy unit of the island system.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application 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 application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams 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.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A method for controlling island system transmission power, the method comprising:
determining that a new energy true bipolar flexible-direct island system has a fault, and acquiring a current signal and a power signal of the island system;
determining whether the island system fault is a single-pole locking fault or not according to the current signal and the power signal, and determining the adjustable range of the direct-current voltage of the converter station of the island system according to a preset inverse time-limit protection coefficient and overcurrent time of the island system after determining that the island system is the single-pole locking fault;
boosting the direct current voltage of the converter station of the island system within the adjustable range, reducing the direct current of the converter station to a preset range, and obtaining the normal pole power value of the converter station;
and determining that the normal pole power value of the converter station is reduced and the normal pole power value is reduced to the inflow power value of the converter station, stopping boosting the direct-current voltage of the converter station of the island system and reducing the direct-current of the converter station.
2. The method according to claim 1, wherein the adjustable range is 1-1.299 p.u..
3. The method according to claim 1, wherein the predetermined range is 1-1.768 p.u..
4. The method of claim 1, further comprising: and after the direct current of the converter station is reduced to a preset range, the inverse time limit protection of the direct current of the converter station is not operated.
5. The method of claim 1, further comprising: and after the normal pole power value of the converter station is determined to be reduced and is reduced to the inflow power value of the converter station, restoring the direct current voltage of the converter station of the island system to the reference voltage of the direct current voltage of the converter station.
6. A system for controlling island system transmission power, the system comprising:
the parameter acquisition module is used for determining that a new energy true bipolar flexible-straight island system has a fault and acquiring a current signal and a power signal of the island system;
the fault judgment module is used for determining whether the island system fault is a single-pole latching fault or not according to the current signal and the power signal, and determining the adjustable range of the direct-current voltage of the converter station of the island system according to a preset inverse time-limit protection coefficient and overcurrent time of the island system after the island system is determined to be the single-pole latching fault;
the regulating module is used for boosting the direct current voltage of the converter station of the island system within the adjustable range and reducing the direct current of the converter station to a preset range to obtain a normal pole power value of the converter station;
and the judgment module is used for determining that the normal pole power value of the converter station is reduced and is reduced to the current inflow power value of the converter station, stopping boosting the direct-current voltage of the converter station of the island system and stopping reducing the direct-current of the converter station.
7. The system of claim 6, wherein the adjustable range is 1-1.299 p.u..
8. The system according to claim 6, wherein the predetermined range is 1-1.768 p.u.
9. The system of claim 6, wherein the regulation module is configured to reduce the converter station DC current to a predetermined range, and disable the converter station DC inverse time protection.
10. The system according to claim 1, wherein the determining module is configured to recover the dc voltage of the converter station of the island system to the reference voltage of the dc voltage of the converter station after determining that the normal pole power value of the converter station decreases and decreases to the inflow power value of the converter station.
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