CN111969652A - Multi-direct-current cooperative control method and device for eliminating overload of alternating-current line of receiving-end power grid - Google Patents

Multi-direct-current cooperative control method and device for eliminating overload of alternating-current line of receiving-end power grid Download PDF

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CN111969652A
CN111969652A CN202010654462.0A CN202010654462A CN111969652A CN 111969652 A CN111969652 A CN 111969652A CN 202010654462 A CN202010654462 A CN 202010654462A CN 111969652 A CN111969652 A CN 111969652A
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power
line
direct current
converter station
modulation
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CN111969652B (en
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朱泽翔
付超
李诗旸
杨荣照
赵睿
毛田
吴为
谢宇翔
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China Southern Power Grid Co Ltd
Research Institute of Southern Power Grid Co Ltd
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China Southern Power Grid Co Ltd
Research Institute of Southern Power Grid Co Ltd
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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
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • 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
    • 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 relates to the technical field of power grid operation control, and discloses a multi-direct-current cooperative control method and a multi-direct-current cooperative control device for eliminating overload of an alternating-current line of a receiving-end power grid, wherein the method comprises the following steps: acquiring a receiving-end power grid alternating current line set and the maximum capacity of each alternating current line in the set; acquiring the direct current transmission power of each direct current converter station and the sensitivity factor of the direct current transmission power to the alternating current line power; judging whether the alternating current lines in the set have faults or zero power in the receiving-end power grid; when an AC line fails or has zero power, judging whether the AC line is overloaded or not; when an AC line is overloaded, acquiring the power return drop of the overloaded AC line; acquiring the direct current modulation amount of each direct current converter station according to the power drop back amount; and sending the direct current modulation amount to the corresponding direct current converter station, so that the corresponding direct current converter station carries out modulation control on direct current transmission power, and the overload problem of the alternating current circuit of the receiving-end power grid is eliminated.

Description

Multi-direct-current cooperative control method and device for eliminating overload of alternating-current line of receiving-end power grid
Technical Field
The invention relates to the technical field of power grid operation control, in particular to a multi-direct-current cooperative control method and device for eliminating overload of an alternating-current line of a receiving-end power grid.
Background
At present, with the promotion of west-east power transmission projects, a large amount of west clean energy supplies electric energy to east load-intensive regions through direct current power transmission projects. However, since the east load-intensive area is often a building concentration area, conditions for constructing the dc converter station are not provided. The direct current receiving end converter station can only be built in a suburb far away from the load, and supplies power to the urban area through an alternating current transmission line. This results in that, when an ac transmission line at a dc drop point fails, the power flow of the failed line is diverted to other power transmission channels, resulting in overloading of the relevant load receiving line. Because the line overload belongs to load overload, the power lifting and back-down modulation control measures of single direct current cannot change the power flow distribution of a power grid again to eliminate the line overload problem, a large amount of loads also need to be cut off, and the influence range of accidents is enlarged. If the influence of the load is removed after the line fault is avoided, the system load flow needs to be pre-controlled. But this severely limits the consumer's power usage and also cuts down on the economics of grid operation.
Aiming at the problems, the power flow of the power grid after the line fault can be redistributed through multi-direct current cooperative control, the problem of alternating current line overload is solved, and a related method is not available at present. The existing multi-direct-current cooperative control method only aims at the direct-current fault problem, reduces the loss amount of the total direct-current transmission power and the machine switching amount of stable control actions by improving other direct-current transmission power, and does not solve the problem of overload of a direct-current receiving end power grid line.
Disclosure of Invention
The technical problem to be solved by the embodiment of the invention is as follows: the multi-direct-current cooperative control method and the multi-direct-current cooperative control device for eliminating overload of the alternating-current line of the receiving-end power grid are provided, a plurality of direct-current transmission powers are uniformly adjusted, and the overload problem of the alternating-current line of the receiving-end power grid is eliminated.
In order to solve the above technical problem, in a first aspect, an embodiment of the present invention provides a multi-dc cooperative control method for eliminating overload of an ac line of a receiving-end power grid, where the method includes:
acquiring a receiving-end power grid alternating current line set and the maximum capacity of each alternating current line in the set;
acquiring the direct current transmission power of each direct current converter station and the sensitivity factor of the direct current transmission power to the alternating current line power;
judging whether the alternating current lines in the set have faults or zero power in the receiving-end power grid;
when the AC line in the set fails or has zero power, judging whether the AC line in the set is overloaded or not;
when the AC line in the set is overloaded, acquiring the power return amount of the overloaded AC line;
acquiring the direct current modulation quantity of each direct current converter station according to the power back-off quantity;
and sending the direct current modulation amount of each direct current converter station to the corresponding direct current converter station, so that the corresponding direct current converter station performs modulation control on direct current transmission power according to the direct current modulation amount.
In a preferred embodiment, the sensitivity factor of the dc transmission power to the ac line power is calculated by the following formula:
Figure BDA0002574498210000021
wherein, TijDenotes the sensitivity factor, DiRepresents the DC transport power, D 'of the ith DC converter station before the change'iRepresenting the DC transmission power, P, of the i-th DC converter station after the changejRepresents the power, P ', of the j-th AC line before the change of the DC transmission power'jRepresenting the power of the jth AC line after a change in DC transmission power, i>0，j>0。
In a preferred embodiment, the determining whether there is a fault or zero power of an ac line in the set in the receiving-end power grid specifically includes:
comparing the line power of the AC lines in the set with a preset first power;
when the absolute values of the line power of all the alternating current lines are not less than the first power, judging that no alternating current line of the receiving-end power grid has a fault or zero power;
when the absolute value of the line power of any AC line is smaller than the first power, comparing the duration time with a preset first time;
when the duration is longer than the first time, judging that an alternating current line of the receiving-end power grid has a fault or zero power;
when the duration is not greater than the first time, determining that no fault or zero power occurs in the alternating current line; and when all the AC lines are not in fault or have zero power, judging that no AC line of the receiving-end power grid is in fault or has zero power.
In a preferred embodiment, the determining whether there is an overload on the ac line in the set specifically includes:
comparing the power of each AC line with the corresponding maximum capacity;
when the power of any AC line is larger than the corresponding maximum capacity, judging that the AC lines in the set are overloaded;
and when the power of all the AC lines is not larger than the corresponding maximum capacity, judging that no AC line in the set is overloaded.
In a preferred embodiment, the power drop amount of the overload ac line is calculated by the following formula:
ΔPk＝Pk-K×PUk；
wherein the subscript k denotes the number of the overload ac line in the set, Δ PkRepresenting the amount of power drop-back, P, of the kth AC linekRepresenting the overload power of the kth AC line, K representing the calculation coefficient of the power back-off quantity, PUkDenotes the maximum capacity, k, of the kth AC line>0，0<K<1。
In a preferred embodiment, the dc modulation amount of the dc converter station is calculated by the following formula:
Figure BDA0002574498210000041
wherein min represents the minimum calculation symbol, Δ DiIndicating the direct current modulation quantity of the ith direct current converter station, wherein the direct current modulation quantity is larger than zero to indicate direct current upward modulation, the direct current downward modulation is smaller than zero to indicate no modulation, nDRepresenting the total number of DC converter stations, | | represents the absolute value calculation sign, s.t represents the constraint, the equation and inequality in the bracket represent the constraint condition, the first is the constraint that the DC modulation quantity can not overload the AC line in the set, the second is the constraint of the total DC modulation quantity, the third is the constraint of single DC transmission power, T is the constraint of single DC transmission powerikIndicating the sensitivity factor of the i-th dc transmission power of the dc converter station to the k-th ac line k-power, the subscript k indicating the number of overloaded ac lines in said set, adminRepresents the minimum value of the sum of all DC modulation quantities, Δ DmaxMeans all rightThe maximum value of the sum of the modulation amounts of the streams,D irepresenting the minimum power of the i-th dc converter station,
Figure BDA0002574498210000042
representing the maximum power of the ith DC converter station, DiIndicating the dc transmission power of the i-th dc converter station before the change.
In order to solve the above technical problem, in a second aspect, an embodiment of the present invention provides a multi-dc cooperative control apparatus for eliminating overload of an ac line of a receiving-end grid, where the apparatus includes:
the system comprises a first acquisition module, a second acquisition module and a control module, wherein the first acquisition module is used for acquiring a receiving-end power grid alternating current line set and the maximum capacity of each alternating current line in the set;
the second acquisition module is used for acquiring the direct current transmission power of each direct current converter station and the sensitivity factor of the direct current transmission power to the alternating current line power;
the first judgment module is used for judging whether the alternating current lines in the set have faults or zero power or not;
the second judgment module is used for judging whether the AC lines in the set are overloaded or not when the AC lines in the set have faults or zero power;
a third obtaining module, configured to obtain a power back-off amount of an overloaded ac line when the ac line in the set is overloaded;
a fourth obtaining module, configured to obtain a dc modulation amount of each dc converter station according to the power back-off amount;
and the modulation control module is used for sending the direct current modulation amount of each direct current converter station to the corresponding direct current converter station, so that the corresponding direct current converter station performs modulation control on direct current transmission power according to the direct current modulation amount.
In order to solve the above technical problem, in a third aspect, an embodiment of the present invention provides a computer-readable storage medium, where a computer program is stored, and the computer program, when executed, implements the method for coordinated multi-dc control to eliminate ac line overload of a receiving-end grid according to any one of the first aspect.
In order to solve the technical problem, in a fourth aspect, an embodiment of the present invention provides a terminal device, where the terminal device includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the computer program is executed by the processor, the method for coordinated multi-dc control to eliminate ac line overload of a receiving-end grid according to any one of the first aspect is implemented.
Compared with the prior art, the multi-direct-current cooperative control method, the multi-direct-current cooperative control device, the multi-direct-current cooperative control storage medium and the multi-direct-current cooperative control equipment for eliminating overload of the alternating current line of the receiving-end power grid have the advantages that: by pre-fetching a set of ac lines of a receiving end grid and the maximum capacity of each ac line in the set, and the DC transmission power of each DC converter station and the sensitivity factor of the DC transmission power to the AC line power are obtained in the on-line monitoring system of the receiving-end power grid, whether an AC line in the receiving-end power grid is overloaded or not is further judged, when an alternating current line is overloaded, the power back-off quantity of the overloaded alternating current line is obtained, the direct current modulation quantity of the direct current converter station is obtained according to the power back-off quantity, the direct current modulation quantity is sent to the corresponding direct current converter station, the corresponding direct current converter station can carry out modulation control of the direct current transmission power lifting or back-off according to the direct current modulation quantity, the direct current transmission power can be dynamically adjusted according to the fault type and the line overload condition, and therefore the overload problem of the alternating current line of the receiving-end power grid is eliminated through multi-direct current cooperative control.
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In order to more clearly illustrate the technical features of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is apparent that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on the drawings without inventive labor.
Fig. 1 is a schematic flow chart of a multi-dc cooperative control method for eliminating ac line overload of a receiving-end grid according to a preferred embodiment of the present invention;
fig. 2 is a schematic structural diagram of an application scenario of a multi-dc cooperative control method for eliminating overload of an ac line of a receiving-end power grid according to the present invention;
fig. 3 is a schematic structural diagram of a preferred embodiment of a multi-dc cooperative control device for eliminating overload of an ac line of a receiving-end grid according to the present invention;
fig. 4 is a schematic structural diagram of a preferred embodiment of a terminal device provided by the present invention.
Detailed Description
In order to clearly understand the technical features, objects and effects of the present invention, the following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings and examples. The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention. Other embodiments, which can be derived by those skilled in the art from the embodiments of the present invention without inventive step, shall fall within the scope of the present invention.
In the description of the present invention, it should be understood that the numbers themselves, such as "first", "second", etc., are used only for distinguishing the described objects, do not have a sequential or technical meaning, and cannot be understood as defining or implying the importance of the described objects.
Fig. 1 is a schematic flow chart of a multi-dc cooperative control method for eliminating ac line overload of a receiving-end grid according to a preferred embodiment of the present invention.
As shown in fig. 1, the method includes:
s11: acquiring a receiving-end power grid alternating current line set and the maximum capacity of each alternating current line in the set;
s12: acquiring the direct current transmission power of each direct current converter station and the sensitivity factor of the direct current transmission power to the alternating current line power;
s13: judging whether the alternating current lines in the set have faults or zero power in the receiving-end power grid;
s14: when the AC line in the set fails or has zero power, judging whether the AC line in the set is overloaded or not;
s15: when the AC line in the set is overloaded, acquiring the power return amount of the overloaded AC line;
s16: acquiring the direct current modulation quantity of each direct current converter station according to the power back-off quantity;
s17: and sending the direct current modulation amount of each direct current converter station to the corresponding direct current converter station, so that the corresponding direct current converter station performs modulation control on direct current transmission power according to the direct current modulation amount.
Specifically, the maximum capacity of the set and each ac line in the set may be obtained in advance before the implementation of the present invention, or may be obtained in real time when the implementation of the present invention is performed, the dc transmission power of the dc converter station and the line power of the ac line are obtained in an online monitoring system of a power grid, and the sensitivity factor is further calculated; the method comprises the steps of firstly judging whether an alternating current line in a set has a fault or zero power when the alternating current line has the fault or zero power, then further judging whether the alternating current line has the overload or not, acquiring the power back-off quantity of the overload alternating current line when the alternating current line has the overload, calculating the direct current modulation quantity of each direct current converter station according to the power back-off quantity, and further sending the direct current modulation quantity to the corresponding direct current converter station, so that the corresponding direct current converter station performs modulation control of lifting or back-off on direct current transmission power according to the direct current modulation quantity.
According to the embodiment, the direct current transmission power can be dynamically adjusted according to the fault type and the line overload condition, so that the overload problem of the alternating current line of the receiving-end power grid is eliminated through multi-direct current cooperative control.
In a preferred embodiment, the sensitivity factor of the dc transmission power to the ac line power is calculated by the following formula:
Figure BDA0002574498210000081
wherein, TijDenotes the sensitivity factor, DiRepresents the DC transport power, D 'of the ith DC converter station before the change'iRepresenting the DC transmission power, P, of the i-th DC converter station after the changejRepresents the power, P ', of the j-th AC line before the change of the DC transmission power'jRepresenting the power of the jth AC line after a change in DC transmission power, i>0，j>0。
In an online monitoring system of a power grid, the direct current transmission power of the ith direct current converter station before and after the change and the power of the jth alternating current line before and after the change of the direct current transmission power are obtained, so that the sensitivity factor can be calculated.
In a preferred embodiment, the determining whether there is a fault or zero power of an ac line in the set in the receiving-end power grid specifically includes:
comparing the line power of the AC lines in the set with a preset first power;
when the absolute values of the line power of all the alternating current lines are not less than the first power, judging that no alternating current line of the receiving-end power grid has a fault or zero power;
when the absolute value of the line power of any AC line is smaller than the first power, comparing the duration time with a preset first time;
when the duration is longer than the first time, judging that an alternating current line of the receiving-end power grid has a fault or zero power;
when the duration is not greater than the first time, determining that no fault or zero power occurs in the alternating current line; and when all the AC lines are not in fault or have zero power, judging that no AC line of the receiving-end power grid is in fault or has zero power.
The first power is a parameter larger than zero, and the size setting is related to a parameter of the ac line corresponding to the first power.
The first time may also be set according to an actual condition of the power grid, which is not limited in this embodiment.
Specifically, when the absolute value of the line power of all the ac lines is not less than the first power, it may be determined that no ac line of the receiving-end grid has a fault or zero power; when the absolute value of the line power of any alternating current line is smaller than the first power and the duration time of the line power of any alternating current line is longer than the first time, namely the absolute value of the line power of N alternating current lines (N is larger than or equal to 1) is smaller than the first power and the duration time of any one of the N alternating current lines is longer than the first time, it can be judged that the alternating current line of the receiving-end power grid has a fault or zero power; when the absolute value of the line power of any one alternating current line is smaller than the first power and the duration time of the line power of any one alternating current line is not larger than the first time, namely the absolute value of the line power of N (N is larger than or equal to 1) alternating current lines is smaller than the first power and the duration time of all the alternating current lines in the N alternating current lines is not larger than the first time, judging that the N alternating current lines have no fault or zero power; and when all the alternating current lines are not in fault or zero power, namely all the alternating current lines of the receiving-end power grid alternating current line set are not in fault or zero power, judging that no alternating current line of the receiving-end power grid is in fault or zero power.
In a preferred embodiment, the determining whether there is an overload on the ac line in the set specifically includes:
comparing the power of each AC line with the corresponding maximum capacity;
when the power of any AC line is larger than the corresponding maximum capacity, judging that the AC lines in the set are overloaded;
and when the power of all the AC lines is not larger than the corresponding maximum capacity, judging that no AC line in the set is overloaded.
It can be understood that, when determining whether the ac line is overloaded, the present embodiment only needs to determine whether the power of the ac line is greater than the maximum capacity corresponding to the ac line, and does not need to determine the duration time again, and can obtain the determination at the first time when the ac line is overloaded, so as to facilitate subsequent control.
In a preferred embodiment, the power drop amount of the overload ac line is calculated by the following formula:
ΔPk＝Pk-K×PUk；
wherein the subscript k denotes the number of the overload ac line in the set, Δ PkRepresenting the amount of power drop-back, P, of the kth AC linekRepresenting the overload power of the kth AC line, K representing the calculation coefficient of the power back-off quantity, PUkDenotes the maximum capacity, k, of the kth AC line>0，0<K<1。
It should be noted that K is a coefficient set to prevent the actual power fluctuation. Typically, the ac line power should be less than the line capacity multiplied by K after the action is taken to ensure that the actual line power fluctuation is not overloaded after the control action.
It is to be understood that K is an engineering empirical value, and is set to 0.95 in this embodiment.
In a preferred embodiment, the dc modulation amount of the dc converter station is calculated by the following formula:
Figure BDA0002574498210000101
wherein min represents the minimum calculation symbol, Δ DiIndicating the direct current modulation quantity of the ith direct current converter station, wherein the direct current modulation quantity is larger than zero to indicate direct current upward modulation, the direct current downward modulation is smaller than zero to indicate no modulation, nDRepresenting the total number of dc converter stations, | | represents the absolute value calculation sign, s.t represents constraints, the equations and inequalities in brackets represent constraints, the first is the constraint that the dc modulation amount makes the ac lines in the set not overloaded, the second is the constraint of the total dc modulation amount, and the third is the constraint of the single dc transmission powerBundle, TikIndicating the sensitivity factor of the i-th dc transmission power of the dc converter station to the k-th ac line power, subscript k indicating the number of overloaded ac lines in said set, adminRepresents the minimum value of the sum of all DC modulation quantities, Δ DmaxRepresents the maximum value of the sum of all the dc modulation amounts,D irepresenting the minimum power of the i-th dc converter station,
Figure BDA0002574498210000102
representing the maximum power of the ith DC converter station, DiIndicating the dc transmission power of the i-th dc converter station before the change.
It should be noted that the calculation of the dc modulation amount is an optimization problem, wherein,
Figure BDA0002574498210000111
min. indicates the objective function that should be minimized in the optimization problem, Δ D below miniThe variables to be optimized in the optimization problem are represented, s.t. represents constraint, and the equality and inequality in the brace represent constraint conditions.
Further, for an optimization problem, the solution can be performed by different methods, such as trial and error, heuristic algorithm, linear programming method, and the like. While the uniqueness of the solution is determined by the problem itself, it is not necessary that the solution of each problem be unique. For this embodiment, the solution can be performed by the following process: and preferentially arranging the direct current converter station with a large sensitivity factor for modulation, when inequality constraint of direct current transmission power of the corresponding direct current converter station just reaches a boundary, arranging the direct current converter station with the second sensitivity factor for modulation, and when inequality constraint of total direct current modulation quantity just reaches the boundary, arranging the direct current converter station with the sensitivity factor with the opposite direction and the largest absolute value for modulation. And by analogy, ending when the equality constraint condition is met, so that the modulation amounts of different direct current converter stations can be obtained.
For better illustration of the embodiment of the invention, fig. 2 shows an application scenario of the invention, where D1-D3 are dc converter stations, D1 is dc transmission power 5000MW, D2 is dc transmission power 5000MW, and D3 is dc transmission power 2000 MW; B1-B5 are loads, B1 is loaded with 1680MW, B2 is loaded with 2650MW, B3 is loaded with 2440MW, B4 is loaded with 3100MW, and B5 is loaded with 3260 MW; l1 to L9 are power transmission lines to the load from the dc converter station, and all the power transmission lines are ac lines in the receiving-end grid ac line set.
Wherein, the AC line L6 maximum capacity PU6The maximum power of the dc converter stations D1, D2, D3 is 3800MW, 5000MW, 3000MW, the minimum power of the dc converter stations D1, D2, D3 is 4000MW, 2000MW, and the maximum and minimum values of the sum of all dc modulation amounts are 1000MW and-1000 MW, respectively.
The dc transmission powers of D1, D2, and D3, 100MW, are changed to obtain different power values flowing through the ac line L6, and further, the sensitivity factors T of the dc transmission powers of D1, D2, and D3 to the line power of the ac line L6 can be obtainedi6：
Figure BDA0002574498210000121
When the alternating current line L5 has a fault (namely the absolute value of the line power of the L5 is less than the first power and the duration is greater than the first time), the line power of the alternating current line L6 is increased from 3003MW to P64046MW, exceeding the maximum capacity PU of L6 line63800 MW. When K is 0.95, the power return amount Δ P of the overload ac line L6 is increased6Comprises the following steps:
Figure BDA0002574498210000122
since the maximum power of D1, D2 and D3 is 5000MW, 5000MW and 3000MW, the minimum power is 4000MW, 4000MW and 2000MW, and the maximum value delta D of the sum of all the DC modulation amountsmaxAnd a minimum value Δ Dmin1000MW and-1000 MW respectively, so the direct current modulation amounts of D1, D2 and D3 are obtained by solving: 0MW, -1000MW, 930MW, i.e. D1 straightThe DC transmission power is unchanged, the DC transmission power of D2 is reduced by 1000MW, and the DC transmission power of D3 is increased by 930 MW. After the DC converter station implements the DC modulation amount, the power of the AC line L6 is reduced from 4046MW to 3530MW, which is less than 3800MW of the maximum capacity of the L6 line.
In summary, the multi-dc cooperative control method for eliminating ac line overload of the receiving-end power grid according to the embodiments of the present invention further determines whether there is an ac line in the receiving-end power grid overloaded by obtaining a set of ac lines of the receiving-end power grid and a maximum capacity of each ac line in the set in advance, and obtaining a dc transmission power of each dc converter station and a sensitivity factor of the dc transmission power to the ac line power in an online monitoring system of the receiving-end power grid, when an ac line is overloaded, obtaining a power back-off quantity of the overloaded ac line, obtaining a dc modulation quantity of the dc converter station according to the power back-off quantity, and sending the dc modulation quantity to the corresponding dc converter station, where the corresponding dc converter station can perform modulation control of dc transmission power boost or back-off according to the dc modulation quantity, and can dynamically adjust the dc transmission power according to a fault type and a line overload condition, therefore, the overload problem of the alternating current line of the receiving-end power grid is eliminated through multi-direct current cooperative control.
It should be understood that all or part of the processes in the multi-dc cooperative control method for eliminating ac line overload of the receiving-end power grid according to the present invention may also be implemented by a computer program instructing related hardware, where the computer program may be stored in a computer readable storage medium, and when being executed by a processor, the computer program may implement the steps of the multi-dc cooperative control method for eliminating ac line overload of the receiving-end power grid. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable storage medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable storage medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable storage media that does not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.
Fig. 3 is a schematic structural diagram of a preferred embodiment of the multi-dc cooperative control apparatus for eliminating ac line overload of a receiving-end power grid according to the present invention, which is capable of implementing all processes of the multi-dc cooperative control method for eliminating ac line overload of a receiving-end power grid according to any of the above embodiments.
As shown in fig. 3, the apparatus includes:
the system comprises a first acquisition module, a second acquisition module and a control module, wherein the first acquisition module is used for acquiring a receiving-end power grid alternating current line set and the maximum capacity of each alternating current line in the set;
the second acquisition module is used for acquiring the direct current transmission power of each direct current converter station and the sensitivity factor of the direct current transmission power to the alternating current line power;
the first judgment module is used for judging whether the alternating current lines in the set have faults or zero power or not;
the second judgment module is used for judging whether the AC lines in the set are overloaded or not when the AC lines in the set have faults or zero power;
a third obtaining module, configured to obtain a power back-off amount of an overloaded ac line when the ac line in the set is overloaded;
a fourth obtaining module, configured to obtain a dc modulation amount of each dc converter station according to the power back-off amount;
and the modulation control module is used for sending the direct current modulation amount of each direct current converter station to the corresponding direct current converter station, so that the corresponding direct current converter station performs modulation control on direct current transmission power according to the direct current modulation amount.
Preferably, the second obtaining module calculates a sensitivity factor of the obtained dc transmission power to the ac line power by the following formula:
Figure BDA0002574498210000141
wherein, TijDenotes the sensitivity factor, DiRepresents the DC transport power, D 'of the ith DC converter station before the change'iRepresenting the DC transmission power, P, of the i-th DC converter station after the changejRepresents the power, P ', of the j-th AC line before the change of the DC transmission power'jRepresenting the power of the jth AC line after a change in DC transmission power, i>0，j>0。
Preferably, the first determining module is specifically configured to:
comparing the line power of the AC lines in the set with a preset first power;
when the absolute values of the line power of all the alternating current lines are not less than the first power, judging that no alternating current line of the receiving-end power grid has a fault or zero power;
when the absolute value of the line power of any AC line is smaller than the first power, comparing the duration time with a preset first time;
when the duration is longer than the first time, judging that an alternating current line of the receiving-end power grid has a fault or zero power;
when the duration is not greater than the first time, determining that no fault or zero power occurs in the alternating current line; and when all the AC lines are not in fault or have zero power, judging that no AC line of the receiving-end power grid is in fault or has zero power.
Preferably, the second determination module is specifically configured to:
comparing the power of each AC line with the corresponding maximum capacity;
when the power of any AC line is larger than the corresponding maximum capacity, judging that the AC lines in the set are overloaded;
and when the power of all the AC lines is not larger than the corresponding maximum capacity, judging that no AC line in the set is overloaded.
Preferably, the third obtaining module obtains the power drop amount of the overload ac line by calculating according to the following formula:
ΔPk＝Pk-K×PUk；
wherein the subscript k denotes the number of the overload ac line in the set, Δ PkRepresenting the amount of power drop-back, P, of the kth AC linekRepresenting the overload power of the kth AC line, K representing the calculation coefficient of the power back-off quantity, PUkDenotes the maximum capacity, k, of the kth AC line>0，0<K<1。
Preferably, the fourth obtaining module obtains the dc modulation amount of the dc converter station by calculating according to the following formula:
Figure BDA0002574498210000151
wherein min represents the minimum calculation symbol, Δ DiIndicating the direct current modulation quantity of the ith direct current converter station, wherein the direct current modulation quantity is larger than zero to indicate direct current upward modulation, the direct current downward modulation is smaller than zero to indicate no modulation, nDRepresenting the total number of DC converter stations, | | represents the absolute value calculation sign, s.t represents the constraint, the equation and inequality in the bracket represent the constraint condition, the first is the constraint that the DC modulation quantity can not overload the AC line in the set, the second is the constraint of the total DC modulation quantity, the third is the constraint of single DC transmission power, T is the constraint of single DC transmission powerikIndicating the sensitivity factor of the i-th dc transmission power of the dc converter station to the k-th ac line power, subscript k indicating the number of overloaded ac lines in said set, adminRepresents the minimum value of the sum of all DC modulation quantities, Δ DmaxRepresents the maximum value of the sum of all DC modulation quantities, DiRepresenting the minimum power of the i-th dc converter station,
Figure BDA0002574498210000161
representing the maximum power of the ith DC converter station, DiIndicating the dc transmission power of the i-th dc converter station before the change.
The multi-direct-current cooperative control device for eliminating the overload of the alternating-current line of the receiving-end power grid provided by the embodiment of the invention can dynamically adjust the direct-current transmission power according to the fault type and the line overload condition, so that the problem of the alternating-current line overload of the receiving-end power grid is eliminated through the multi-direct-current cooperative control.
Fig. 4 is a schematic structural diagram of a preferred embodiment of a terminal device according to the present invention, where the terminal device is capable of implementing all processes of the multi-dc cooperative control method for eliminating ac line overload of a receiving-end grid according to any of the above embodiments.
As shown in fig. 4, the terminal device includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and when the computer program is executed by the processor, the computer program implements all the processes of the multi-dc cooperative control method for eliminating ac line overload of a receiving-end grid according to any one of the embodiments.
Illustratively, the computer program may be partitioned into one or more modules/units that are stored in the memory and executed by the processor to implement the invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used for describing the execution process of the computer program in the terminal device.
The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory may be used for storing the computer programs and/or modules, and the processor may implement various functions of the terminal device by executing or executing the computer programs and/or modules stored in the memory and calling data stored in the memory. The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required by at least one function (such as a sound playing function, an image playing function, etc.), and the like; the storage data area may store data (such as audio data, a phonebook, etc.) created according to the use of the cellular phone, and the like. In addition, the memory may include high speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), at least one magnetic disk storage device, a Flash memory device, or other volatile solid state storage device.
It should be noted that the terminal device includes, but is not limited to, a processor and a memory, and those skilled in the art will understand that the structural diagram of fig. 4 is only an example of the terminal device, and does not constitute a limitation to the terminal device, and may include more components than those shown in the drawings, or may combine some components, or may be different components.
The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be noted that, for those skilled in the art, several equivalent obvious modifications and/or equivalent substitutions can be made without departing from the technical principle of the present invention, and these obvious modifications and/or equivalent substitutions should also be regarded as the scope of the present invention.

Claims (9)

1. A multi-direct current cooperative control method for eliminating overload of an alternating current line of a receiving-end power grid is characterized by comprising the following steps:
acquiring a receiving-end power grid alternating current line set and the maximum capacity of each alternating current line in the set;
acquiring the direct current transmission power of each direct current converter station and the sensitivity factor of the direct current transmission power to the alternating current line power;
judging whether the alternating current lines in the set have faults or zero power in the receiving-end power grid;
when the AC line in the set fails or has zero power, judging whether the AC line in the set is overloaded or not;
when the AC line in the set is overloaded, acquiring the power return amount of the overloaded AC line;
acquiring the direct current modulation quantity of each direct current converter station according to the power back-off quantity;
and sending the direct current modulation amount of each direct current converter station to the corresponding direct current converter station, so that the corresponding direct current converter station performs modulation control on direct current transmission power according to the direct current modulation amount.
2. The method of claim 1, wherein the sensitivity factor of the dc transmission power to ac line power is calculated by the following equation:
Figure FDA0002574498200000011
wherein, TijDenotes the sensitivity factor, DiRepresents the DC transport power, D 'of the ith DC converter station before the change'iRepresenting the DC transmission power, P, of the i-th DC converter station after the changejRepresents the power, P ', of the j-th AC line before the change of the DC transmission power'jRepresenting the power of the jth AC line after a change in DC transmission power, i>0，j>0。
3. The method according to claim 1, wherein the determining whether the ac line in the set has a fault or zero power in the receiving-end grid specifically includes:
comparing the line power of the AC lines in the set with a preset first power;
when the absolute values of the line power of all the alternating current lines are not less than the first power, judging that no alternating current line of the receiving-end power grid has a fault or zero power;
when the absolute value of the line power of any AC line is smaller than the first power, comparing the duration time with a preset first time;
when the duration is longer than the first time, judging that an alternating current line of the receiving-end power grid has a fault or zero power;
when the duration is not greater than the first time, determining that no fault or zero power occurs in the alternating current line; and when all the AC lines are not in fault or have zero power, judging that no AC line of the receiving-end power grid is in fault or has zero power.
4. The method according to claim 1, wherein the determining whether there is an ac line in the set that is overloaded further comprises:
comparing the power of each AC line with the corresponding maximum capacity;
when the power of any AC line is larger than the corresponding maximum capacity, judging that the AC lines in the set are overloaded;
and when the power of all the AC lines is not larger than the corresponding maximum capacity, judging that no AC line in the set is overloaded.
5. The method of claim 1, wherein the power drop back amount of the overloaded ac line is calculated by the following formula:
ΔPk＝Pk-K×PUk；
wherein the subscript k denotes the number of the overload ac line in the set, Δ PkRepresenting the amount of power drop-back, P, of the kth AC linekRepresenting the overload power of the kth AC line, K representing the calculation coefficient of the power back-off quantity, PUkDenotes the maximum capacity, k, of the kth AC line>0，0<K<1。
6. The method according to claim 5, wherein the DC modulation amount of the DC converter station is calculated by the following formula:
Figure FDA0002574498200000031
wherein min represents the minimum calculation symbol, Δ DiIndicating the direct current modulation quantity of the ith direct current converter station, wherein the direct current modulation quantity is larger than zero to indicate direct current upward modulation, the direct current downward modulation is smaller than zero to indicate no modulation, nDRepresenting the total number of DC converter stations, | | represents the absolute value calculation sign, s.t represents the constraint, the equation and inequality in the bracket represent the constraint condition, the first is the constraint that the DC modulation quantity can not overload the AC line in the set, the second is the constraint of the total DC modulation quantity, the third is the constraint of single DC transmission power, T is the constraint of single DC transmission powerikIndicating the sensitivity factor of the i-th dc transmission power of the dc converter station to the k-th ac line power, subscript k indicating the number of overloaded ac lines in said set, adminRepresents the minimum value of the sum of all DC modulation quantities, Δ DmaxRepresents the maximum value of the sum of all DC modulation quantities, DiRepresenting the minimum power of the i-th dc converter station,
Figure FDA0002574498200000032
representing the maximum power of the ith DC converter station, DiIndicating the dc transmission power of the i-th dc converter station before the change.
7. A multi-dc cooperative control apparatus for eliminating ac line overload of a receiving-end grid, the apparatus comprising:
the system comprises a first acquisition module, a second acquisition module and a control module, wherein the first acquisition module is used for acquiring a receiving-end power grid alternating current line set and the maximum capacity of each alternating current line in the set;
the second acquisition module is used for acquiring the direct current transmission power of each direct current converter station and the sensitivity factor of the direct current transmission power to the alternating current line power;
the first judgment module is used for judging whether the alternating current lines in the set have faults or zero power or not;
the second judgment module is used for judging whether the AC lines in the set are overloaded or not when the AC lines in the set have faults or zero power;
a third obtaining module, configured to obtain a power back-off amount of an overloaded ac line when the ac line in the set is overloaded;
a fourth obtaining module, configured to obtain a dc modulation amount of each dc converter station according to the power back-off amount;
and the modulation control module is used for sending the direct current modulation amount of each direct current converter station to the corresponding direct current converter station, so that the corresponding direct current converter station performs modulation control on direct current transmission power according to the direct current modulation amount.
8. A computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed, the method for coordinated multi-dc control for eliminating ac line overload of a receiving-end grid according to any one of claims 1 to 6 is implemented.
9. A terminal device, characterized in that the terminal device comprises a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, wherein the computer program, when executed by the processor, implements the method for coordinated multi-dc control for eliminating ac line overload in a receiving-end grid according to any one of claims 1 to 6.
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