CN109149618B - Parallel recovery optimization decision method for alternating current-direct current hybrid power system - Google Patents

Parallel recovery optimization decision method for alternating current-direct current hybrid power system Download PDF

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CN109149618B
CN109149618B CN201811057524.9A CN201811057524A CN109149618B CN 109149618 B CN109149618 B CN 109149618B CN 201811057524 A CN201811057524 A CN 201811057524A CN 109149618 B CN109149618 B CN 109149618B
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power
node
recovered
power supply
direct current
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CN109149618A (en
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和敬涵
许寅
张沛
李长城
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Beijing Jiaotong University
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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
    • 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
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • 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]

Abstract

The invention provides a parallel recovery optimization decision method for an alternating current-direct current series-parallel power system, which considers a direct current system positioned at the boundary of a power failure power grid, determines the sub-area range divided by the power failure power grid and a black start power supply of each sub-area, and converts a receiving end node of the boundary direct current power transmission system into a power supply node; searching the shortest power transmission path of each power supply node, and calculating a recovery efficiency value f; and selecting the power supply node in the region with the maximum recovery efficiency value f, and realizing the sharing of the resources in the sub-regions by utilizing the sub-regions in parallel connection with the direct-current power transmission connection system in the process of simultaneously recovering the plurality of sub-regions. The invention forms a recovery scheme with the maximum recovery efficiency as a target by utilizing the characteristic of high-voltage direct current quick controllability, accelerates the overall recovery process of the system and shortens the power failure time of the system.

Description

Parallel recovery optimization decision method for alternating current-direct current hybrid power system
Technical Field
The invention relates to the field of recovery control of a series-parallel power system, in particular to a parallel recovery optimization decision method of an alternating current-direct current series-parallel power system.
Background
When a large-scale power failure accident occurs in a power system, huge economic loss and adverse social influence are often caused, and sometimes, life safety is even damaged. Therefore, there is a need to develop a scientific and effective system recovery method and make a system recovery scheme to cope with large-scale power outage events. At present, most of traditional power system recovery methods are established on the basis of application of an alternating current power grid, and after a major power failure occurs, a partition parallel recovery mode is usually adopted, and a conventional black start unit is used for providing starting power for a non-black start unit in a sub-area where the black start unit is located. And after the recovery of each sub-area is finished, synchronously and parallelly operating each sub-area. Therefore, the sub-regions cannot support each other in the sub-region recovery process.
With the development of modern power systems, power systems have gradually shifted from traditional alternating Current power grids to alternating Current and Direct Current (ac) hybrid power grids including Direct Current systems in the alternating Current power grids, and High Voltage Direct Current (HVDC) power transmission systems are widely applied, so that the recovery of the ac and Direct Current hybrid power systems presents new characteristics. The high-voltage direct current has the characteristics of high regulation speed, strong controllability, capability of asynchronously interconnecting different alternating current power grids and the like, and is more favorable for accelerating the recovery speed of the power grids. The application types of high-Voltage direct current are mainly divided into Line-commutated-converter-based high-Voltage direct current (LCC-HVDC) based on a grid commutation converter and high-Voltage direct current (VSC-HVDC) based on a Voltage source converter.
Because the effect of the current system recovery technical method still needs to be further improved, the characteristics of different types of high-voltage direct current need to be fully exerted, and an efficient power system recovery method is provided.
Disclosure of Invention
The embodiment of the invention provides a parallel recovery optimization decision method for an alternating current-direct current hybrid power system, and aims to provide a method for recovering the power system with better effect.
In order to achieve the purpose, the invention adopts the following technical scheme.
A parallel recovery optimization decision method for an alternating current-direct current hybrid power system comprises the following steps:
s1: determining the sub-area range divided by the power failure power grid and the black start power supply of each sub-area, and converting the receiving end node of the boundary direct current transmission system of the power failure power grid into a power supply node;
s2: searching the shortest power transmission path from the black-start power supply of each subarea to each unrecovered power supply node in the subarea, calculating the recovery efficiency value f corresponding to each power supply node according to the output characteristic of each power supply node in the subarea, and sorting the recovery efficiency values f of each power supply node;
s3: selecting a power node with the maximum current recovery efficiency value f, determining the shortest power transmission path corresponding to the power node with the maximum current recovery efficiency value f, evaluating whether a power node close to the start time limit constraint exists in a subarea where the power node with the maximum current recovery efficiency value f exists, and if so, selecting the power node close to the start time limit constraint to replace the power node with the maximum current recovery efficiency value f to serve as a power node to be recovered for subsequent processing; if no power node close to the start time limit constraint exists, directly taking the power node with the maximum current recovery efficiency value f as a power node to be recovered for subsequent processing;
s4; checking whether the starting power constraint of the power source node to be recovered is met, if so, executing S5; otherwise, executing S6;
s5: judging whether the selected power source node to be recovered is a receiving end node of the direct current power transmission system, if not, executing S7; if yes, checking whether active power impact constraint and reactive power impact constraint brought by starting the power source node to be recovered are met, and if yes, executing S7; if the constraint is not met, deleting the power supply node to be recovered from the power supply set which is not recovered currently, and returning to S2;
s6: calculating the interconnection time of the power source node to be recovered in the starting power support sub-area by the direct current power transmission system in parallel connection with the adjacent sub-area, and if the interconnection time after supporting is less than the recovery time in the sub-area, acquiring the starting power from the adjacent sub-area by the direct current power transmission system to recover the interconnection time of the power source node to be recovered, and executing step S7; if the interconnection time after supporting is not less than the recovery time in the subarea, deleting the power supply nodes to be recovered from the power supply set which is not recovered at present, and returning to S2;
s7: performing power flow verification on the power source node to be recovered, performing power recovery on the power source node to be recovered by using a black-start power source in the sub-area, and returning to S2 if an un-started power source exists in the sub-area; otherwise, the procedure is ended.
Preferably, before the step S7 of performing power restoration on the power node to be restored by using the black-start power supply in the sub-area, the method further includes: and checking the current of the power source node to be recovered by adopting an alternating current-direct current mutual iteration mode.
Preferably, the output characteristic of the power supply node is a start-up characteristic of a dc power transmission system corresponding to the power supply node.
Preferably, the recovery efficiency value f of the power supply node is calculated by the following formula:
f＝max(C/T)
wherein C is ∈ { C ∈ [)G,CDCDenotes the upper power limit that the selected power supply node can provide: cGTo generator capacity, CDCThe maximum power output for the direct current transmission system; t represents the selected power node starting from the current stage to the output and reaching the selected power nodeThe time required to power up the upper limit that the point can provide.
Preferably, the said T represents the time required for the selected power source to output and reach the selected power source from the current stage, including:
the shortest power transmission time from the recovered system to the power node to be recovered;
starting time of a power supply node to be recovered;
and (5) the climbing time of the power source node to be recovered.
Preferably, the active power impact constraint and the reactive power impact constraint in step S5 are calculated by the following formulas:
the active power impact constraint is:
Figure BDA0001796186770000041
in the formula,. DELTA.PDCThe injection power is the injection power when the direct current transmission system is started; df is anThe transient frequency response value of the unit n is obtained; f. ofNIs the rated frequency of the system; Δ flimFor the limitation of frequency variation, the frequency is generally-0.5 to 1 Hz;
the reactive power impact constraint is:
Figure BDA0001796186770000042
the delta Q is the reactive power variation of an alternating-current side bus of the direct-current transmission system; sscIs the short circuit capacity of the AC bus;
system short circuit ratio:
Figure BDA0001796186770000043
in the formula, PdcRated power transmitted for the direct current transmission system; z is the equivalent impedance of the alternating current system; u shapeacTo commutate the bus voltage. When using an alternating voltage UacAnd a DC transmission power PdcFor nominal values, SCR can then be reduced to Z-1。
Preferably, the check whether the starting power constraint of the power node to be recovered is satisfied is calculated by the following formula:
PDC,min＜PDC＜CDC
wherein, PDCThe starting power of the power supply in the selected area; cDCProviding the minimum value of the upper capacity limit for the upper transmission capacity limit of the direct current transmission system and the sending end system; pDC,minIs the minimum operating power of the direct current transmission system.
Preferably, the recovering the interconnection time of the selected power source node in the sub-area supporting the power obtaining from the adjacent sub-area comprises:
the recovery time from the system which has recovered in the adjacent subarea to the direct current transmission system;
time when the direct current system is connected with the adjacent sub-area in parallel;
recovery time from the dc power transmission system to the selected power source node to be recovered.
According to the technical scheme provided by the embodiment of the invention, the parallel recovery optimization decision method of the alternating current-direct current hybrid power system increases the number of power supply points and sub-areas of the system by utilizing the characteristic of quick controllability of HVDC; continuously searching and starting a power supply with the maximum recovery efficiency index, and performing sub-area interconnection operation by using HVDC (high voltage direct current), so that the cooperative recovery capability of the sub-areas is improved; finally, the power failure power supply of each subarea is started step by step to form a recovery scheme with the maximum recovery efficiency as a target, so that the overall recovery process of the system is accelerated, and the system power failure time is shortened.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a processing flow chart of a parallel recovery optimization decision method for an ac-dc hybrid power system according to embodiment 1 of the present invention;
fig. 2 is a schematic view of a topology of a power system according to embodiment 2 of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood by those skilled in the art that, unless otherwise defined, all 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. It will be further 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 prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
For the convenience of understanding the embodiments of the present invention, the following description will be further explained by taking several specific embodiments as examples in conjunction with the drawings, and the embodiments are not to be construed as limiting the embodiments of the present invention.
The embodiment of the invention provides an optimization decision method for parallel recovery of an alternating current-direct current hybrid power system, aiming at forming a recovery scheme with the maximum recovery efficiency by utilizing the characteristic of high-voltage direct current rapid controllability, and realizing the purposes of accelerating the overall recovery process of the system and shortening the power failure time of the system.
Example 1
Fig. 1 is a processing flow chart of a parallel recovery optimization decision method for an ac/dc hybrid power system according to an embodiment of the present invention, and with reference to fig. 1, the method includes the following steps:
s1: determining the sub-area range divided by the power failure power grid and the black start power supply of each sub-area, and converting the receiving end node of the boundary direct current transmission system of the power failure power grid into a power supply node;
preferably, before determining the subarea range of the division of the blackout power grid, the blackout power grid can be abstracted into a weighted undirected graph. The black start power supply refers to a power supply with self-starting capability, such as hydroelectric power generation, wind power generation and the like, and can be started without acquiring electric energy from a system.
S2: searching the shortest power transmission path from the black-start power supply of each subarea to each unrecovered power supply node in the subarea, calculating the recovery efficiency value f corresponding to each power supply node according to the output characteristic of each power supply node in the subarea, and sorting the recovery efficiency values f of each power supply node;
s3: selecting a power node with the maximum current recovery efficiency value f, determining a shortest power transmission path corresponding to the power node with the maximum current recovery efficiency value f, evaluating whether a power node close to a starting time limit constraint exists in a sub-region where the power node with the maximum current recovery efficiency value f exists, if so, selecting the power node close to the starting time limit constraint to replace the power node with the maximum current recovery efficiency value f to serve as a power node to be recovered for subsequent processing, and deleting the power node with the maximum current recovery efficiency value f from a power source which is not recovered; otherwise, if the power node close to the start time limit constraint does not exist, directly taking the power node with the maximum current recovery efficiency value f as the power node to be recovered for subsequent processing.
The power supply constrained by the time limit for starting is that the power-off time of the power supply is close to the longest critical value of the restarting time of the power supply. Once the length of the power outage exceeds the threshold, the power source is unavailable for system recovery.
S4; checking whether the starting power constraint of the power source node to be recovered is met, if so, executing S5; otherwise, executing S6;
s5: judging whether the selected power source node to be recovered is a receiving end node of the direct current power transmission system, if not, executing S7; otherwise, checking whether active power impact constraint and reactive power impact constraint brought by starting the power source node to be recovered are met, and executing S7 if the active power impact constraint and the reactive power impact constraint are met; if the constraint is not met, deleting the power source node to be recovered from the power source set which is not recovered currently, and returning to S2;
s6: calculating the interconnection time of the power source node to be recovered in the starting power support sub-area by the direct current power transmission system in parallel connection with the adjacent sub-area, and if the interconnection time after supporting is less than the recovery time in the sub-area, acquiring the starting power from the adjacent sub-area by the direct current power transmission system to recover the interconnection time of the power source node to be recovered, and executing step S7; if the interconnection time after supporting is not less than the recovery time in the sub-area, deleting the power supply nodes to be recovered from the power supply set which is not recovered currently, and returning to the S2;
s7: performing power flow verification on the power source node to be recovered, then performing power recovery on the power source node to be recovered by using a black-start power source in the sub-area, and returning to S2 if a non-start power source exists in the sub-area; otherwise, the procedure is ended.
Preferably, in step S6, if the interconnection time after supporting is less than the recovery time in the sub-area, the dc power transmission system is used to obtain the starting power from the adjacent sub-area to recover the interconnection time of the power source node to be recovered, and when step S7 is executed, the ac/dc mutual iteration method is used to perform the power flow verification of the current stage recovery on the power source node to be recovered.
In step S2, the output characteristic of the power supply node is the start-up characteristic of the dc power transmission system corresponding to the power supply node.
Preferably, the recovery efficiency value f is calculated by the following formula:
f＝max(C/T)
wherein C is ∈ { C ∈ [)G,CDCDenotes the upper limit of power that the selected power source can provide: cGTo generator capacity, CDCThe maximum power output for the direct current transmission system; t represents the elapsed time required for the selected power source to start at the current stage, to exert a force and reach the upper limit of the power that the selected power source can provide.
Further, T represents the time required for the selected power source to exert a force from the current stage and reach the upper limit of the power that the selected power source can provide, including:
the shortest power transmission time from the recovered system to the power supply to be recovered;
starting time of a power supply to be recovered;
and (5) the climbing time of the power supply to be recovered.
Preferably, the ramp-up time of the power node where the receiving end of the boundary direct current transmission system is located is negligible. The start-up time of the dc power transmission system is determined according to the state of the dc power transmission system at that time. If the direct current transmission system is in a hot standby state, the starting time of the direct current transmission system can be ignored; if the direct current transmission system is in a cold standby state, the starting time of the direct current transmission system cannot be ignored.
In the above step S5, the active power surge constraint and the reactive power surge constraint are calculated by the following formulas:
the active power impact constraint is:
Figure BDA0001796186770000091
in the formula,. DELTA.PDCThe injection power is the injection power when the direct current transmission system is started; df is anThe transient frequency response value of the unit n is obtained; f. ofNIs the rated frequency of the system; Δ flimFor frequency variation limitation, schematically Δ flimIs-0.5 to 1 Hz;
the reactive power impact constraint is:
Figure BDA0001796186770000092
the delta Q is the reactive power variation of an alternating-current side bus of the direct-current transmission system; sscIs the short circuit capacity of the AC bus;
preferably, whether the starting power constraint of the power node to be recovered is satisfied is checked, and the starting power constraint is calculated by the following formula:
PDC,min＜PDC＜CDC
wherein, PDCThe starting power of the power supply in the selected area; cDCProviding the minimum value of the upper capacity limit for the upper transmission capacity limit of the direct current transmission system and the sending end system; pDC,minIs the minimum operating power of the direct current transmission system.
In the step S6, the obtaining interconnection time of the power support sub-area from the adjacent sub-area for restoring interconnection time of the selected power node includes:
the recovery time from the system which has recovered in the adjacent subarea to the direct current transmission system;
time when the direct current system is connected with the adjacent sub-area in parallel;
recovery time from the dc power transmission system to the selected power node.
Example 2
Fig. 2 is a topological schematic diagram of an electric power system provided in embodiment 2 of the present invention, and referring to fig. 2, the system has 8 generator sets, where G30 and G33 are black start sets, and the rest are non-black start sets; there are 46 branches including lines and transformers, where the branches 16-17 are flexible High Voltage Direct Current (HVDC) lines, and the rest are ac. The nodes 32 and 37 are each connected to a different external grid via a conventional HVDC line. The direct current lines 16-17 and the alternating current lines 2-3, 8-9 and 17-18 divide the system into two subareas: the subzone 1 uses G30 as black start set, and the subzone 2 uses G33 as black start set. The system parameters are shown in tables 1 and 2:
TABLE 1 Power supply characteristic parameters
Node point C/MW Ps/MW k/MW·h-1 Starting time/min TH/min
30 1040 0 625 0 0
31 646 50 172 7 70
32 725 0 / 0 0
33 652 0 475 0 0
34 508 30 210 10 17
35 687 300 196 50 50
36 580 60 190 20 90
37 564 0 / 0 0
38 865 78 420 15 70
39 1100 100 480 25 80
TABLE 2 line recovery time parameter
Figure BDA0001796186770000101
Figure BDA0001796186770000111
If the system has a blackout, in the first recovery stage, the specific steps are as follows:
step 1: the power failure system is determined to be in the range of two subareas, wherein G30 is used as a black start unit in subarea 1, and G33 is used as a black start unit in subarea 2. High-voltage direct-current (Line-commutated-converter-based HVDC, LCC-HVDC) receiving end nodes 32 and 37 based on the power grid commutation converter are converted into power source nodes.
Step 2: in the subarea 1, searching a path from the black-start power supply node G30 to the power supply nodes G37, G38 and G39 in the subarea with the Dijkstra algorithm to calculate the recovery efficiency value f of each power supply node, as shown in the following Table 3;
table 3 first recovery phase power recovery efficiency in sub-area 1
Node point Route of travel f/(MW/min) Priority level
37 30-2-25-37 82.24 1
38 30-2-25-26-29-38 5.6332 3
39 30-2-1-39 6.414 2
And step 3: selecting a power supply node 37 with the maximum current recovery efficiency value f and a corresponding power transmission path 30-2-25-37 thereof, and evaluating that no power supply close to the starting time limit constraint exists currently;
and 4, step 4: verifying that the start-up power constraint of the selected power supply 37 is not out-of-limit;
and 5: judging that the selected power node is a direct-current power transmission system, checking that active power and reactive power impact brought by starting of the direct-current power transmission system cannot meet constraint conditions, and deleting the power node 37 in the recovery stage;
step 6: selecting a power supply node 39 with the current f maximum and a power transmission path 30-2-1-39 corresponding to the power supply node, and evaluating that no power supply close to the starting time limit constraint exists at present;
and 7: verifying that the startup power constraint of the selected power supply 39 is not met, the power supply node 39 is removed during this recovery phase;
and 8: selecting a power supply node 38 with the current f maximum and a power transmission path 30-2-25-26-38 corresponding to the power supply node, and evaluating that no power supply close to the starting time limit constraint exists at present;
and step 9: verifying that the startup power constraint of the selected power source 38 is satisfied;
step 10: and the selected power source node is not a receiving end node of the direct current transmission system, and the trend verification is adopted to show that the recovery scheme at the recovery stage is feasible.
In the implementation process, the sub-area 1 starts from the black-start power supply node 30, sequentially performs charging restoration on the nodes 2, 25, 26, 29 and 38, finally ignites the non-black-start unit of the node 38, and enters the next restoration phase. And continuously repeating the method, determining the next unit to be started, and determining all power supply starting sequences needing to be recovered after a plurality of stages.
Further, in the process of implementing step 4 in the recovery sub-area 2, the power supply at the node 35 is selected for recovery according to the power supply node recovery efficiency index of the current state. However, since the power supply is not sufficiently supplied through the shortest path in the sub-area 2, it is not possible to immediately start the power supply, and it takes a longer waiting time. At this time, a communication channel between the sub-area 1 and the sub-area 2 is established through the recovery lines 16 to 17 based on a high Voltage-source-converter-based HVDC (VSC-HVDC) of the Voltage source converter. Since the sub-area 1 has sufficient starting power, partial power can be supplied to the sub-area 2 through the paths 26-27-17-16, the power supply 35 is supported to be started successfully, the power supply starting time delay with high recovery efficiency is avoided, and the recovery efficiency of the system is improved.
Further, the recovery time of the system of fig. 2 obtained by the embodiment is 39 minutes, and the recovery time of the system described in fig. 2 obtained by the partitioned parallel recovery method without considering the assistance of the dc power transmission system is 59 minutes, so that the recovery time can be shortened by 33.89% in the embodiment of the present invention.
According to the embodiment, the number of the power supply points and the sub-areas of the system is increased by utilizing the high-voltage direct current of the boundary, and the power supply with the maximum recovery efficiency index is searched and gradually started in each sub-area. In the process, the high-voltage direct-current power transmission connecting line is used for restoring the connection among the sub-areas, and the sub-area with sufficient starting power can provide power support for the sub-area with insufficient starting power. Therefore, by adopting the technical scheme of the invention, all generator sets needing to be started in the power failure power grid can be gradually started in the shortest time, and the power generated by the power supply is the largest at the recovery end stage, so that the recovery efficiency of the power system is improved, and the economic loss caused by heavy power failure is reduced.
Those of ordinary skill in the art will understand that: the drawings are merely schematic representations of one embodiment, and the flow charts in the drawings are not necessarily required to practice the present invention.
From the above description of the embodiments, it is clear to those skilled in the art that the present invention can be implemented by software plus necessary general hardware platform. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which may be stored in a storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method according to the embodiments or some parts of the embodiments.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (8)

1. A parallel recovery optimization decision method for an alternating current-direct current hybrid power system is characterized by comprising the following steps:
s1: determining the sub-area range divided by the power failure power grid and the black start power supply of each sub-area, and converting the receiving end node of the boundary direct current transmission system of the power failure power grid into a power supply node;
s2: searching the shortest power transmission path from the black-start power supply of each subarea to each unrecovered power supply node in the subarea, calculating the recovery efficiency value f corresponding to each power supply node according to the output characteristic of each power supply node in the subarea, and sorting the recovery efficiency values f of each power supply node;
s3: selecting a power node with the maximum current recovery efficiency value f, determining the shortest power transmission path corresponding to the power node with the maximum current recovery efficiency value f, evaluating whether a power node close to the start time limit constraint exists in a subarea where the power node with the maximum current recovery efficiency value f exists, and if so, selecting the power node close to the start time limit constraint to replace the power node with the maximum current recovery efficiency value f to serve as a power node to be recovered for subsequent processing; if no power node close to the start time limit constraint exists, directly taking the power node with the maximum current recovery efficiency value f as a power node to be recovered for subsequent processing;
s4; checking whether the starting power constraint of the power source node to be recovered is met, if so, executing S5; otherwise, executing S6;
s5: judging whether the selected power source node to be recovered is a receiving end node of the direct current power transmission system, if not, executing S7; if yes, checking whether active power impact constraint and reactive power impact constraint brought by starting the power source node to be recovered are met, and if yes, executing S7; if the constraint is not met, deleting the power supply node to be recovered from the power supply set which is not recovered currently, and returning to S2;
s6: calculating the interconnection time of the power source node to be recovered in the starting power support sub-area by the direct current power transmission system in parallel connection with the adjacent sub-area, and if the interconnection time after supporting is less than the recovery time in the sub-area, acquiring the starting power from the adjacent sub-area by the direct current power transmission system to recover the interconnection time of the power source node to be recovered, and executing step S7; if the interconnection time after supporting is not less than the recovery time in the subarea, deleting the power supply nodes to be recovered from the power supply set which is not recovered at present, and returning to S2;
s7: performing power flow verification on the power source node to be recovered, performing power recovery on the power source node to be recovered by using a black-start power source in the sub-area, and returning to S2 if an un-started power source exists in the sub-area; otherwise, the procedure is ended.
2. The method according to claim 1, wherein before the step of performing power restoration on the power node to be restored by using the black-start power supply in the sub-area in S7, the method further comprises: and checking the current of the power source node to be recovered by adopting an alternating current-direct current mutual iteration mode.
3. The method according to claim 1, wherein the output characteristic of the power supply node is a start-up characteristic of a dc power transmission system to which the power supply node corresponds.
4. The method of claim 3 wherein the recovery efficiency value f for the power supply node is calculated by the formula:
f＝max(C/T)
wherein C is ∈ { C ∈ [)G,CDCDenotes the upper power limit that the selected power supply node can provide: cGTo generator capacity, CDCThe maximum power output for the direct current transmission system; t represents the elapsed time required for the selected power node to start from the current stage to exert a force and reach the upper limit of the power that the selected power node can provide.
5. The method of claim 4, wherein said T represents the time required for the selected power source to deliver power and reach the selected power source from the current stage, comprising:
the shortest power transmission time from the recovered system to the power node to be recovered;
starting time of a power supply node to be recovered;
and (5) the climbing time of the power source node to be recovered.
6. The method according to claim 1, wherein the active power surge constraint and the reactive power surge constraint in step S5 are calculated by the following formulas:
the active power impact constraint is:
Figure FDA0002323614940000031
in the formula,. DELTA.PDCThe injection power is the injection power when the direct current transmission system is started; df is anThe transient frequency response value of the unit n is obtained; f. ofNIs the rated frequency of the system; Δ flimFor the limitation of frequency variation, the frequency is generally-0.5 to 1 Hz;
the reactive power impact constraint is:
Figure FDA0002323614940000032
the delta Q is the reactive power variation of an alternating-current side bus of the direct-current transmission system; sscIs the short circuit capacity of the AC bus;
system short circuit ratio:
Figure FDA0002323614940000033
in the formula, PdcRated power transmitted for the direct current transmission system; z is the equivalent impedance of the alternating current system; u shapeacTo commutate the bus voltage.
7. The method of claim 1, wherein the checking whether the startup power constraint of the power node to be recovered is satisfied is calculated by the following formula:
PDC,min＜PDC＜CDC
wherein, PDCThe starting power of the power supply in the selected area; cDCProviding the minimum value of the upper capacity limit for the upper transmission capacity limit of the direct current transmission system and the sending end system; pDC,minIs the minimum operating power of the direct current transmission system.
8. The method of claim 1, wherein the retrieving interconnection time of the selected power source node from the adjacent sub-area within the boot power support sub-area comprises:
the recovery time from the system which has recovered in the adjacent subarea to the direct current transmission system;
time when the direct current system is connected with the adjacent sub-area in parallel;
recovery time from the dc power transmission system to the selected power source node to be recovered.
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