CN112531765A - Method and device for determining short circuit ratio of new energy station - Google Patents
Method and device for determining short circuit ratio of new energy station Download PDFInfo
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- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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Abstract
The invention relates to a method and a device for determining a short-circuit ratio of a new energy station, which comprise the following steps: determining the short-circuit capacity of a bus side in a collection station according to the short-circuit capacity of a grid-connected point of the collection station; determining the short circuit capacity of a grid-connected point of each new energy field station in the collection station according to the short circuit capacity of a bus side in the collection station; determining the short circuit ratio of each new energy station in the collection station according to the short circuit capacity of the grid-connected point of each new energy station in the collection station; the short circuit ratio of the new energy station obtained by the method is more accurate, and accurate support can be provided for new energy grid-connected oscillation evaluation and new energy planning management.
Description
Technical Field
The invention relates to the technical field of new energy, in particular to a method and a device for determining a short-circuit ratio of a new energy station.
Background
The new energy power generation is used in a large scale in remote areas far away from a load center, so that the power grid strength is weak, and the stability problem of a new energy power generation system is obvious. The new energy grid-connected oscillation is a main influence factor of the stability problem, the essence of the new energy grid-connected oscillation is an unstable problem caused by interaction between a new energy station and a weak power grid, and the weaker the power grid incorporated in the new energy station, the higher the possibility of oscillation, so that the evaluation of the power grid strength is one of key contents of the evaluation of the oscillation risk of the new energy grid-connected system.
In electric power system analysis, the strength of a power grid is generally described by adopting a short circuit ratio, and when a new energy station is connected into the power grid in a multi-station convergence boosting mode, namely when the new energy station is connected in series, how to accurately calculate the short circuit ratio of the new energy station is a problem to be solved urgently in the field.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a method and a device for determining a short-circuit ratio of a new energy field station.
The purpose of the invention is realized by adopting the following technical scheme:
the invention provides a method for determining a short-circuit ratio of a new energy station, which is improved in that the method comprises the following steps:
determining the short-circuit capacity of a bus side in a collection station according to the short-circuit capacity of a grid-connected point of the collection station;
determining the short circuit capacity of a grid-connected point of each new energy field station in the collection station according to the short circuit capacity of a bus side in the collection station;
determining the short circuit ratio of each new energy station in the collection station according to the short circuit capacity of the grid-connected point of each new energy station in the collection station;
wherein the short circuit capacity of the bus side in the collection station comprises: short-circuit capacity on the high-voltage bus side, short-circuit capacity on the medium-voltage bus side, and short-circuit capacity on the low-voltage bus side.
Preferably, the determining the short circuit capacity of the bus side in the aggregation station according to the short circuit capacity of the aggregation station grid-connected point includes:
acquiring the short circuit capacity of a grid-connected point of the collecting station, and determining the short circuit capacity of a bus side in the collecting station according to the following formula:
in the formula, SCHFor short-circuit capacity on the high-voltage bus side of the collecting station, SCMFor short-circuit capacity on the medium-voltage bus side of the collecting station, SCLShort-circuit capacity on the low-voltage bus side of the collector station, S is the rated capacity of the collector station, SHFor rated capacity on the high-voltage bus side of the collection station, UHFor collecting rated voltage, Z, on the high-voltage bus side of the stationH,MFor line impedance, Z, between high-voltage and medium-voltage busbars of a collection stationH,LIs the line impedance between the high-voltage bus and the low-voltage bus of the collection station, SMRated capacity, S, for the medium-voltage bus side of the collection stationLThe rated capacity of the low-voltage bus side of the collecting station is shown, and SC is the short-circuit capacity of the grid-connected point of the collecting station.
Further, the acquiring the short circuit capacity of the merging station grid-connected point includes:
if the grid-connected point of the collection station is connected with the power grid, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
SC＝SC0
in the formula, SC0Short circuit capacity of grid connection points;
if the grid-connected point of the collection station is connected with the high-voltage buses of other collection stations, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
in the formula, Z is the line impedance between the grid-connected point of the collection station and the high-voltage buses of other collection stations, and SC' is the short-circuit capacity distributed to the collection station by the high-voltage buses of other collection stations;
wherein the rating S of the pooling station is determined as follows:
in the formula, SjThe rated capacity of the jth new energy field station at the medium-voltage bus side and the low-voltage bus side of the collection station is J ∈ [1, J ∈ [ ]]J is the medium-voltage bus side and the low-voltage bus side of the collecting stationTotal number of new energy stations.
Preferably, the determining the short circuit capacity of the grid-connected point of each new energy field station in the collection station according to the short circuit capacity of the bus side in the collection station includes:
determining short circuit capacity SC of jth new energy field station grid-connected point according to the following formulaj：
In the formula of UMFor the rated voltage of the medium-voltage bus of the collecting station, ULRated voltage for low-voltage bus of collection station, ZjIs line impedance between a jth new energy field station grid-connected point and a bus to which the jth new energy field station grid-connected point belongs, J belongs to (1, …, J ', …, J), J ' is the total number of new energy field stations on a medium-voltage bus side, J is the total number of new energy field stations on the medium-voltage bus side and a low-voltage bus side of a collection station, J-J ' is the total number of new energy field stations on the low-voltage bus side of the collection station, and SjRated capacity of jth new energy station in the collection station, SMFor rated capacity on the medium-voltage bus side of the collecting station, SCMFor short-circuit capacity, S, on the medium-voltage bus side of the collection stationLFor rated capacity on the low-voltage bus side of the collector station, SCLThe short circuit capacity on the low voltage bus side of the collection station.
Preferably, the determining the short circuit ratio of each new energy station in the collection station according to the short circuit capacity of the grid-connected point of each new energy station in the collection station includes:
determining the short circuit ratio R of the jth new energy station in the collection station according to the following formulaj：
In the formula, SCjShort circuit capacity of grid-connected point of jth new energy field station of collecting station, SjThe rated capacity of the jth new energy station in the collection station.
Based on the same inventive concept, the invention also provides a new energy station short-circuit ratio determination device, and the improvement is that the device comprises:
the first determining unit is used for determining the short-circuit capacity of the bus side in the collecting station according to the short-circuit capacity of the grid-connected point of the collecting station;
the second determining unit is used for determining the short-circuit capacity of the grid-connected point of each new energy field station in the collecting station according to the short-circuit capacity of the bus side in the collecting station;
the third determining unit is used for determining the short circuit ratio of each new energy station in the collecting station according to the short circuit capacity of the grid-connected point of each new energy station in the collecting station;
wherein the short circuit capacity of the bus side in the collection station comprises: short-circuit capacity on the high-voltage bus side, short-circuit capacity on the medium-voltage bus side, and short-circuit capacity on the low-voltage bus side.
Preferably, the first determination unit includes:
the acquisition unit is used for acquiring the short circuit capacity of the merging point of the collecting station;
a determining subunit for determining the short circuit capacity of the bus side in the collection station according to the following formula:
in the formula, SCHFor short-circuit capacity on the high-voltage bus side of the collecting station, SCMFor short-circuit capacity on the medium-voltage bus side of the collecting station, SCLShort-circuit capacity on the low-voltage bus side of the collector station, S is the rated capacity of the collector station, SHFor rated capacity on the high-voltage bus side of the collection station, UHFor collecting rated voltage, Z, on the high-voltage bus side of the stationH,MFor line impedance, Z, between high-voltage and medium-voltage busbars of a collection stationH,LIs the line impedance between the high-voltage bus and the low-voltage bus of the collection station, SMRated capacity, S, for the medium-voltage bus side of the collection stationLThe rated capacity of the low-voltage bus side of the collecting station is shown, and SC is the short-circuit capacity of the grid-connected point of the collecting station.
Further, the obtaining unit is specifically configured to:
if the grid-connected point of the collection station is connected with the power grid, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
SC＝SC0
in the formula, SC0Short circuit capacity of grid connection points;
if the grid-connected point of the collection station is connected with the high-voltage buses of other collection stations, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
in the formula, Z is the line impedance between the grid-connected point of the collection station and the high-voltage buses of other collection stations, and SC' is the short-circuit capacity distributed to the collection station by the high-voltage buses of other collection stations;
wherein the rating S of the pooling station is determined as follows:
in the formula, SjThe rated capacity of the jth new energy field station at the medium-voltage bus side and the low-voltage bus side of the collection station is J ∈ [1, J ∈ [ ]]And J is the total number of the new energy stations on the medium-voltage bus side and the low-voltage bus side of the collecting station.
Preferably, the second determining unit is specifically configured to:
determining short circuit capacity SC of jth new energy field station grid-connected point according to the following formulaj：
In the formula of UMFor the rated voltage of the medium-voltage bus of the collecting station, ULRated voltage for low-voltage bus of collection station, ZjThe line impedance between the grid-connected point of the jth new energy station and the bus belongs to the jth new energy station, J belongs to (1, …, J ', …, J), J' is the total number of the new energy stations on the medium-voltage bus side, and J is the medium-voltage bus side and the low-voltage bus side of the collection stationThe total number of the new energy stations, J-J' is the total number of the new energy stations at the low-voltage bus side of the collecting station, SjRated capacity of jth new energy station in the collection station, SMFor rated capacity on the medium-voltage bus side of the collecting station, SCMFor short-circuit capacity, S, on the medium-voltage bus side of the collection stationLFor rated capacity on the low-voltage bus side of the collector station, SCLThe short circuit capacity on the low voltage bus side of the collection station.
Preferably, the third determining unit is specifically configured to:
determining the short circuit ratio R of the jth new energy station in the collection station according to the following formulaj：
In the formula, SCjShort circuit capacity of grid-connected point of jth new energy field station of collecting station, SjThe rated capacity of the jth new energy station in the collection station.
Compared with the closest prior art, the invention has the following beneficial effects:
the invention provides a method and a device for determining a short-circuit ratio of a new energy station, which comprise the following steps: determining the short-circuit capacity of a bus side in a collection station according to the short-circuit capacity of a grid-connected point of the collection station; determining the short circuit capacity of the grid-connected point of each new energy field station in the collection station according to the short circuit capacity of the bus side in the collection station; determining the short circuit ratio of each new energy station in the collection station according to the short circuit capacity of the grid-connected point of each new energy station in the collection station; according to the method, when the short-circuit capacity of the merging station grid-connected point is obtained, the distribution of the short-circuit capacity among a plurality of serially connected merging stations and the impedance of the power transmission line between the grid-connected point of the merging station and the high-voltage buses of other merging stations are considered, and when the short-circuit capacity of the new energy field-connected point is obtained, the distribution of the short-circuit capacity among the plurality of field stations and the impedance of the power transmission line between the grid-connected point of the new energy field station and the bus are considered, so that the obtained short-circuit ratio of the new energy field station is more accurate, and accurate support can be provided for new energy grid-connected oscillation evaluation and new energy planning.
Drawings
FIG. 1 is a schematic diagram of a short-circuit ratio calculation principle of a new energy station;
FIG. 2 is a schematic structural diagram of a new energy station according to a first embodiment;
FIG. 3 is a flowchart of a new energy station short-circuit ratio determination method of the present invention;
FIG. 4 is a diagram of the distribution of the short circuit capacity of the collector stations in the first embodiment;
FIG. 5 is a schematic diagram of the short-circuit ratio determination device of the new energy station of the present invention
FIG. 6a is a schematic view of a collecting station according to a second embodiment;
fig. 6b is a diagram of sink station short circuit capacity allocation in a second embodiment.
Detailed Description
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In power system analysis, the strength of a power grid is generally described by using a short-circuit ratio (SCR), as shown in fig. 1, the short-circuit ratio of a new energy station is defined as:
in the formula, SCRREIs the short-circuit ratio of the new energy station, SN,REFor the rated capacity of the new energy station, SCPCCThe short circuit capacity of the new energy station grid-connected point is calculated by the following formula,
SCPCC＝UN,PCCISC,PCC
in the formula of UN,PCCRated voltage for the grid-connection point, ISC,PCCAnd calculating the short-circuit current for the three-phase metal short-circuit fault at the grid-connected point.
In FIG. 1, USIs infinite bus voltage, ZGThe line impedance from a new energy station grid-connected point to an infinite bus is generally formed by impedances of elements such as a power transmission line, a transformer and the like. Suppose UN,PCC≈USThen, then
Therefore, the temperature of the molten metal is controlled,
in the formula, ZN,REIs impedance at rated capacity, Z, of the new energy stationG,PUAnd taking the impedance of the new energy station as a per unit value of a reference value for the impedance of the power grid.
It can be seen that the grid-connected short circuit ratio of the new energy station is related to the rated capacity of the new energy station and the rated voltage of a grid-connected point, and is also related to the connection impedance of the new energy station incorporated into a power grid. Under the condition that the rated capacity of the new energy station and the rated voltage of the grid-connected point are given, if the connection impedance of the new energy station and the grid-connected point is larger, the short-circuit capacity of the grid-connected point is smaller, the short-circuit ratio is smaller, and the power grid is relatively weaker; conversely, the larger the short-circuit ratio, the stronger the grid is. Under the condition that the rated voltage of a grid-connected point of the new energy station and the connection impedance of the new energy station and the power grid are given, the larger the rated capacity of the station is, the smaller the short-circuit ratio is, and the weaker the power grid is; conversely, the larger the short circuit ratio, the stronger the grid is.
However, the new energy station is connected to the power grid in a multi-station collecting and boosting mode, and a multi-station series connection mode exists, so that when the power grid has a short-circuit fault, the power generation of new energy such as wind and light enters a low-voltage ride-through process, and stable short-circuit current cannot be provided for the power grid. Therefore, the short-circuit current or the short-circuit capacity referred to in the present invention is considered to be supplied from the grid side, and the new energy power generation does not supply the short-circuit current or the short-circuit capacity.
For example: fig. 2 is a schematic structural diagram of a certain wind power collection system. It can be seen that wind power plants with different capacities are merged into two collecting stations through 35kV or 110kV lines with different distances, the wind power plants are merged into a power grid after being boosted to 220kV, and meanwhile, the west collecting station is serially connected to the east collecting station and then merged into the power grid.
At present, the main body of new energy power generation development and grid-connected management is a station, so that short circuit of the station is more important than calculation and oscillation risk assessment, and the implementation is easier. However, if the short circuit ratio calculation method is directly adopted for a certain station in the aggregation system shown in fig. 2, the influence of other wind power plants needs to be ignored, and the calculated short circuit ratio is relatively large, which will affect the evaluation result of the oscillation risk.
Therefore, the invention provides a short-circuit ratio determination method, which considers the difference between the capacity of a plurality of stations in a collection system and the length of a grid-connected power transmission line, realizes the rapid calculation of the short-circuit ratio of each station, can be used for oscillation risk assessment, provides support for new energy planning and grid-connected management, and describes the technical scheme of the invention in detail through the following embodiments:
example 1
As shown in fig. 3, the short-circuit ratio determining method provided by the present invention includes:
determining the short-circuit capacity of a bus side in a collection station according to the short-circuit capacity of a grid-connected point of the collection station;
determining the short circuit capacity of a grid-connected point of each new energy field station in the collection station according to the short circuit capacity of a bus side in the collection station;
determining the short circuit ratio of each new energy station in the collection station according to the short circuit capacity of the grid-connected point of each new energy station in the collection station;
wherein the short circuit capacity of the bus side in the collection station comprises: short-circuit capacity on the high-voltage bus side, short-circuit capacity on the medium-voltage bus side, and short-circuit capacity on the low-voltage bus side.
As shown in fig. 4, the new energy station is connected to the power grid in a multi-station collection and voltage boosting manner, the multiple stations are connected in series, the new energy collection system has N collection stations connected in series to the power grid, the grid-connected point of the collection station 1 is connected to the power grid, the grid-connected point of the collection station 2 is connected to the high-voltage bus of the collection station 1, the grid-connected point of the collection station 3 is connected to the high-voltage bus of the collection station 2, and the grid-connected point of the collection station N is connected to the high-voltage bus of the collection station N-1;
wherein, the high, medium and low voltage buses of the collecting station are connected by a three-winding transformer. In fig. 4, the high, medium and low bus voltages of all the collection stations are respectively regarded as the same voltage class, and the line impedances of all the collection stations are regarded as the same, and calculation is performed according to actual data in practical application; in a power transmission system, the impedance of a line and a transformer is mainly inductive, namely R & lt & ltX, so that the impedance of the line and the transformer related to the invention neglects the resistance value, namely Z ≈ jX | ═ X, and the impedance Z only comprises inductive reactance X.
Specifically, the determining the short-circuit capacity of the bus side in the aggregation station according to the short-circuit capacity of the grid-connected point of the aggregation station includes:
acquiring the short circuit capacity of a grid-connected point of the collecting station, and determining the short circuit capacity of a bus side in the collecting station according to the following formula:
in the formula, SCHFor short-circuit capacity on the high-voltage bus side of the collecting station, SCMFor short-circuit capacity on the medium-voltage bus side of the collecting station, SCLShort-circuit capacity on the low-voltage bus side of the collector station, S is the rated capacity of the collector station, SHFor rated capacity on the high-voltage bus side of the collection station, UHFor collecting rated voltage, Z, on the high-voltage bus side of the stationH,MFor line impedance, Z, between high-voltage and medium-voltage busbars of a collection stationH,LIs the line impedance between the high-voltage bus and the low-voltage bus of the collection station, SMRated capacity, S, for the medium-voltage bus side of the collection stationLRated capacity of low-voltage bus side of collecting station, short circuit of grid-connected point of collecting stationCapacity;
further, the acquiring the short circuit capacity of the merging station grid-connected point includes:
if the grid-connected point of the collection station is connected with the power grid (such as the collection station 1 in fig. 4), the short-circuit capacity SC of the grid-connected point of the collection station is determined according to the following formula:
SC＝SC0
in the formula, SC0Short circuit capacity of grid connection points;
if the grid-connected point of the collecting station is connected with the high-voltage bus of other collecting stations (such as the collecting station 2 in fig. 4), the short-circuit capacity SC of the grid-connected point of the collecting station is determined according to the following formula:
wherein Z is a line impedance between a grid-connected point of the collection station and a high-voltage bus of another collection station, SC 'is a short-circuit capacity allocated to the collection station by the high-voltage bus of the other collection station, SC' ═ SC ″ -SC ″HSC' is the short circuit capacity of the point-to-point network of other gathering stations, SCHShort circuit capacity on the high-voltage bus side of other collection stations;
wherein the rating S of the pooling station is determined as follows:
in the formula, Si,jThe rated capacity of the jth new energy field station at the medium-voltage bus side and the low-voltage bus side of the collection station is J ∈ [1, J ∈ [ ]]And J is the total number of the new energy stations on the medium-voltage bus side and the low-voltage bus side of the collecting station.
In order to make the above-described short-circuit capacity allocation process easier to understand, the following description will be made in detail by taking the sink station 1 and the sink station 2 in embodiment 1 as an example:
short circuit capacity on the high voltage bus side of the collection station 1:
SC1＝SC0，S1is the rated capacity of the collection station 1 (sum of the rated capacities of the new energy stations on the medium-voltage bus and low-voltage bus sides of the collection station 1), S1,HFor the rated capacity of the high-voltage bus side of the collector station 1,
Si,jfor the rated capacity of the jth new energy site in the ith collection station in example 1,
the short circuit capacity of the collection station 1, which the high-voltage bus is allocated to the collection station 2: SC (Single chip computer)1,2＝SC1-SC1,H；
Short circuit capacity on the high voltage bus side of the collection station 2:
S2for the rated capacity of the collector station 2, S2,HFor the rated capacity of the high-voltage bus side of the collector station 2,
j is the total number of new energy stations on the medium-voltage bus and low-voltage bus sides of the collection station, in embodiment 1, the total number of new energy stations on the medium-voltage bus and low-voltage bus sides of each collection station of the collection system is regarded as the same, and N is the total number of collection stations in the collection system;
the short circuit capacity of the collection station 3 allocated to the high-voltage bus of the collection station 2: SC (Single chip computer)2,3＝SC2-SC2,H；
The short circuit capacity of the collecting stations 3 to N in example 1 can be obtained by a person skilled in the art with reference to the distribution procedure of the collecting station 2 described above.
In an embodiment of the present invention, the determining the short circuit capacity of the grid-connected point of each new energy field station in the collection station according to the short circuit capacity of the bus side in the collection station includes:
determining short circuit capacity SC of jth new energy field station grid-connected point according to the following formulaj：
In the formula of UMFor the rated voltage of the medium-voltage bus of the collecting station, ULRated voltage for low-voltage bus of collection station, ZjThe new energy field station is the line impedance between the jth new energy field station grid-connected point and the bus to which the jth new energy field station belongs, J belongs to (1, …, J ', …, J), J' is the total number of the new energy field stations at the medium-voltage bus side, J is the total number of the new energy field stations at the medium-voltage bus side and the low-voltage bus side of the collecting station, and S isjRated capacity of jth new energy station in the collection station, SMFor rated capacity on the medium-voltage bus side of the collecting station, SCMFor short-circuit capacity, S, on the medium-voltage bus side of the collection stationLFor rated capacity on the low-voltage bus side of the collector station, SCLThe short circuit capacity on the low voltage bus side of the collection station.
The above-mentioned short circuit ratio of confirming each new energy field station in the station that collects according to the short circuit capacity of each new energy field station grid-connected point in the station that collects includes:
determining the short circuit ratio R of the jth new energy station in the collection station according to the following formulaj：
In the formula, SCjShort circuit capacity of grid-connected point of jth new energy field station of collecting station, SjThe rated capacity of the jth new energy station in the collection station.
Based on the same inventive concept, the invention further provides a new energy station short-circuit ratio determination device, as shown in fig. 5, the device includes:
the first determining unit is used for determining the short-circuit capacity of the bus side in the collecting station according to the short-circuit capacity of the grid-connected point of the collecting station;
the second determining unit is used for determining the short-circuit capacity of the grid-connected point of each new energy field station in the collecting station according to the short-circuit capacity of the bus side in the collecting station;
the third determining unit is used for determining the short circuit ratio of each new energy station in the collecting station according to the short circuit capacity of the grid-connected point of each new energy station in the collecting station;
wherein the short circuit capacity of the bus side in the collection station comprises: short-circuit capacity on the high-voltage bus side, short-circuit capacity on the medium-voltage bus side, and short-circuit capacity on the low-voltage bus side.
In a specific implementation method of the present invention, the first determining unit includes:
the acquisition unit is used for acquiring the short circuit capacity of the merging point of the collecting station;
a determining subunit for determining the short circuit capacity of the bus side in the collection station according to the following formula:
in the formula, SCHFor short-circuit capacity on the high-voltage bus side of the collecting station, SCMFor short-circuit capacity on the medium-voltage bus side of the collecting station, SCLShort-circuit capacity on the low-voltage bus side of the collector station, S is the rated capacity of the collector station, SHFor rated capacity on the high-voltage bus side of the collection station, UHFor collecting rated voltage, Z, on the high-voltage bus side of the stationH,MFor line impedance, Z, between high-voltage and medium-voltage busbars of a collection stationH,LIs the line impedance between the high-voltage bus and the low-voltage bus of the collection station, SMRated capacity, S, for the medium-voltage bus side of the collection stationLThe rated capacity of the low-voltage bus side of the collecting station is shown, and SC is the short-circuit capacity of the grid-connected point of the collecting station.
Further, the obtaining unit is specifically configured to:
if the grid-connected point of the collection station is connected with the power grid, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
SC＝SC0
in the formula, SC0Short circuit capacity of grid connection points;
if the grid-connected point of the collection station is connected with the high-voltage buses of other collection stations, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
in the formula, Z is the line impedance between the grid-connected point of the collection station and the high-voltage buses of other collection stations, and SC' is the short-circuit capacity distributed to the collection station by the high-voltage buses of other collection stations;
wherein the rating S of the pooling station is determined as follows:
in the formula, SjThe rated capacity of the jth new energy field station at the medium-voltage bus side and the low-voltage bus side of the collection station is J ∈ [1, J ∈ [ ]]And J is the total number of the new energy stations on the medium-voltage bus side and the low-voltage bus side of the collecting station.
In a specific implementation method of the present invention, the second determining unit is specifically configured to:
determining short circuit capacity SC of jth new energy field station grid-connected point according to the following formulaj：
In the formula of UMFor the rated voltage of the medium-voltage bus of the collecting station, ULRated voltage for low-voltage bus of collection station, ZjThe new energy field station is the line impedance between the jth new energy field station grid-connected point and the bus to which the jth new energy field station belongs, J belongs to (1, …, J ', …, J), J' is the total number of the new energy field stations at the medium-voltage bus side, J is the total number of the new energy field stations at the medium-voltage bus side and the low-voltage bus side of the collecting station, and S isjRated capacity of jth new energy station in the collection station, SMFor rated capacity on the medium-voltage bus side of the collecting station, SCMFor short-circuit capacity, S, on the medium-voltage bus side of the collection stationLFor rated capacity on the low-voltage bus side of the collector station, SCLThe short circuit capacity on the low voltage bus side of the collection station.
In a specific implementation method of the present invention, the third determining unit is specifically configured to:
determining the sink byShort circuit ratio R of jth new energy station in station collectionj：
In the formula, SCjShort circuit capacity of grid-connected point of jth new energy field station of collecting station, SjThe rated capacity of the jth new energy station in the collection station.
Example 2
As shown in fig. 6a, the aggregation stations are connected in parallel, taking aggregation station 2 as an example:
the 220/500kV step-up in the aggregation station 2 is rated for 1500MW, then from the line length and line parameters marked in fig. 6a, the line impedance of the aggregation station 2 can be obtained as:
Z＝56.1Ω，ZH,L＝16.67Ω，Z1＝6.32Ω，Z2＝0.22Ω，Z3＝6.93Ω，Z4＝5.63Ω，Z5＝1.99Ω；
line parameters: the model of the 500kV power transmission line is LGJK-4 x 630mm2Typical impedance value is 0.275 omega/km, and the model of a 220kV power transmission line is LGJ-400mm2Typical values of impedance are 0.433 Ω/km;
determination of the short circuit capacity in the collection station 2:
as shown in fig. 6b, S C are given01650, then
Determining the short circuit capacity of the wind power plant 1, the wind power plant 2, the wind power plant 3, the wind power plant 4 and the wind power plant 5 grid-connected point of the collection station 2:
in the formula, Z1、Z2、Z3、Z4And Z5Line impedances of the wind farms 1, 2, 3, 4 and 5 with the low-voltage bus side;
determining the short circuit ratio of the wind power plant 1, the wind power plant 2, the wind power plant 3, the wind power plant 4 and the wind power plant 5:
in summary, the method and apparatus for determining the short-circuit ratio of the new energy station provided by the present invention include: determining the short-circuit capacity of a bus side in the collection station according to the short-circuit capacity of the merging points of the collection station; determining the short circuit capacity of a grid-connected point of each new energy field station in the collection station according to the short circuit capacity of a bus side in the collection station; determining the short circuit ratio of each new energy station in the collection station according to the short circuit capacity of the grid-connected point of each new energy station in the collection station; according to the method, when the short-circuit capacity of the collection station grid-connected point is obtained, the distribution of the short-circuit capacity among a plurality of collection stations connected in series and the impedance of the power transmission line between the grid-connected point of the collection station and the high-voltage bus of other collection stations are considered, and when the short-circuit capacity of the new energy station grid-connected point is obtained, the distribution of the short-circuit capacity among the plurality of stations and the impedance of the power transmission line between the grid-connected point of the new energy station and the bus are considered, so that the obtained short-circuit ratio of the new energy station is more accurate, and accurate support can be provided for new energy grid-connected oscillation evaluation and new energy planning.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A method for determining a short-circuit ratio of a new energy station is characterized by comprising the following steps:
determining the short-circuit capacity of a bus side in a collection station according to the short-circuit capacity of a grid-connected point of the collection station;
determining the short circuit capacity of a grid-connected point of each new energy field station in the collection station according to the short circuit capacity of a bus side in the collection station;
determining the short circuit ratio of each new energy station in the collection station according to the short circuit capacity of the grid-connected point of each new energy station in the collection station;
wherein the short circuit capacity of the bus side in the collection station comprises: short-circuit capacity on the high-voltage bus side, short-circuit capacity on the medium-voltage bus side, and short-circuit capacity on the low-voltage bus side.
2. The method of claim 1, wherein determining the short circuit capacity of the bus side in the aggregation station from the short circuit capacity of the aggregation station grid-connected point comprises:
acquiring the short circuit capacity of a grid-connected point of the collecting station, and determining the short circuit capacity of a bus side in the collecting station according to the following formula:
in the formula, SCHFor short-circuit capacity on the high-voltage bus side of the collecting station, SCMFor short-circuit capacity on the medium-voltage bus side of the collecting station, SCLShort-circuit capacity on the low-voltage bus side of the collector station, S is the rated capacity of the collector station, SHRated capacity, U, for the high-voltage bus side of the collection stationHFor collecting rated voltage, Z, on the high-voltage bus side of the stationH,MFor line impedance, Z, between high-voltage and medium-voltage busbars of a collector stationH,LIs the line impedance between the high-voltage bus and the low-voltage bus of the collection station, SMRated capacity, S, for the medium-voltage bus side of the collection stationLThe rated capacity of the low-voltage bus side of the collecting station is shown, and SC is the short-circuit capacity of the grid-connected point of the collecting station.
3. The method of claim 2, wherein said obtaining the short circuit capacity of a aggregation site grid-connected point comprises:
if the grid-connected point of the collection station is connected with the power grid, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
SC＝SC0
in the formula, SC0Short circuit capacity of grid connection points;
if the grid-connected point of the collection station is connected with the high-voltage buses of other collection stations, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
in the formula, Z is the line impedance between the grid-connected point of the collection station and the high-voltage buses of other collection stations, and SC' is the short-circuit capacity distributed to the collection station by the high-voltage buses of other collection stations;
wherein the rating S of the pooling station is determined as follows:
in the formula, SjThe rated capacity of the jth new energy field station at the medium-voltage bus side and the low-voltage bus side of the collection station is J ∈ [1, J ∈ [ ]]And J is the total number of the new energy stations on the medium-voltage bus side and the low-voltage bus side of the collecting station.
4. The method as claimed in claim 1, wherein the determining the short circuit capacity of the grid-connected point of each new energy field station in the aggregation station according to the short circuit capacity of the bus side in the aggregation station comprises:
determining short circuit capacity SC of jth new energy field station grid-connected point according to the following formulaj：
In the formula of UMFor the rated voltage of the medium-voltage bus of the collecting station, ULRated voltage for low-voltage bus of collection station, ZjIs line impedance between a jth new energy field station grid-connected point and a bus to which the jth new energy field station grid-connected point belongs, J belongs to (1, …, J ', …, J), J ' is the total number of new energy field stations on a medium-voltage bus side, J is the total number of new energy field stations on a medium-voltage bus side and a low-voltage bus side of a collection station, J-J ' is the total number of new energy field stations on a low-voltage bus side of the collection station, and SjRated capacity of jth new energy station in the collection station, SMFor rated capacity on the medium-voltage bus side of the collecting station, SCMFor short-circuit capacity, S, on the medium-voltage bus side of the collection stationLTo collectRated capacity, SC, of low-voltage bus side of stationLThe short circuit capacity on the low voltage bus side of the collection station.
5. The method of claim 1, wherein determining the short circuit ratio of each new energy station in the aggregation station according to the short circuit capacity of the grid-connected point of each new energy station in the aggregation station comprises:
determining the short circuit ratio R of the jth new energy station in the collection station according to the following formulaj：
In the formula, SCjShort circuit capacity of grid-connected point of jth new energy field station of collecting station, SjThe rated capacity of the jth new energy station in the collection station.
6. A new energy station short circuit ratio determination device, characterized in that the device comprises:
the first determining unit is used for determining the short-circuit capacity of the bus side in the collecting station according to the short-circuit capacity of the grid-connected point of the collecting station;
the second determining unit is used for determining the short-circuit capacity of the grid-connected point of each new energy field station in the collecting station according to the short-circuit capacity of the bus side in the collecting station;
the third determining unit is used for determining the short circuit ratio of each new energy station in the collecting station according to the short circuit capacity of the grid-connected point of each new energy station in the collecting station;
wherein the short circuit capacity of the bus side in the collection station comprises: short-circuit capacity on the high-voltage bus side, short-circuit capacity on the medium-voltage bus side, and short-circuit capacity on the low-voltage bus side.
7. The apparatus of claim 6, wherein the first determining unit comprises:
the acquisition unit is used for acquiring the short circuit capacity of the merging point of the collecting station;
a determining subunit for determining the short circuit capacity of the bus side in the collection station according to the following formula:
in the formula, SCHFor short-circuit capacity on the high-voltage bus side of the collecting station, SCMFor short-circuit capacity on the medium-voltage bus side of the collecting station, SCLShort-circuit capacity on the low-voltage bus side of the collector station, S is the rated capacity of the collector station, SHRated capacity, U, for the high-voltage bus side of the collection stationHFor collecting rated voltage, Z, on the high-voltage bus side of the stationH,MFor line impedance, Z, between high-voltage and medium-voltage busbars of a collector stationH,LIs the line impedance between the high-voltage bus and the low-voltage bus of the collection station, SMRated capacity, S, for the medium-voltage bus side of the collection stationLThe rated capacity of the low-voltage bus side of the collecting station is shown, and SC is the short-circuit capacity of the grid-connected point of the collecting station.
8. The apparatus of claim 7, wherein the obtaining unit is specifically configured to:
if the grid-connected point of the collection station is connected with the power grid, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
SC＝SC0
in the formula, SC0Short circuit capacity of grid connection points;
if the grid-connected point of the collection station is connected with the high-voltage buses of other collection stations, determining the short-circuit capacity SC of the grid-connected point of the collection station according to the following formula:
in the formula, Z is the line impedance between the grid-connected point of the collection station and the high-voltage buses of other collection stations, and SC' is the short-circuit capacity distributed to the collection station by the high-voltage buses of other collection stations;
wherein the rating S of the pooling station is determined as follows:
in the formula, SjThe rated capacity of the jth new energy field station at the medium-voltage bus side and the low-voltage bus side of the collection station is J ∈ [1, J ∈ [ ]]And J is the total number of the new energy stations on the medium-voltage bus side and the low-voltage bus side of the collecting station.
9. The apparatus of claim 6, wherein the second determining unit is specifically configured to:
determining short circuit capacity SC of jth new energy field station grid-connected point according to the following formulaj：
In the formula of UMFor the rated voltage of the medium-voltage bus of the collecting station, ULRated voltage for low-voltage bus of collection station, ZjIs line impedance between a jth new energy field station grid-connected point and a bus to which the jth new energy field station grid-connected point belongs, J belongs to (1, …, J ', …, J), J ' is the total number of new energy field stations on a medium-voltage bus side, J is the total number of new energy field stations on a medium-voltage bus side and a low-voltage bus side of a collection station, J-J ' is the total number of new energy field stations on a low-voltage bus side of the collection station, and SjRated capacity of jth new energy station in the collection station, SMFor rated capacity on the medium-voltage bus side of the collecting station, SCMFor short-circuit capacity, S, on the medium-voltage bus side of the collection stationLFor rated capacity on the low-voltage bus side of the collector station, SCLThe short circuit capacity on the low voltage bus side of the collection station.
10. The apparatus of claim 6, wherein the third determining unit is specifically configured to:
determining the short circuit ratio R of the jth new energy station in the collection station according to the following formulaj：
In the formula, SCjShort circuit capacity of grid-connected point of jth new energy field station of collecting station, SjThe rated capacity of the jth new energy station in the collection station.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115441513A (en) * | 2022-08-05 | 2022-12-06 | 国网冀北电力有限公司电力科学研究院 | Phase modulator determining method and device suitable for new energy station |
| CN116402412A (en) * | 2023-06-09 | 2023-07-07 | 国网江西省电力有限公司电力科学研究院 | Power grid strength evaluation method and system containing high-proportion new energy |
| EP4304040A1 (en) * | 2022-06-28 | 2024-01-10 | Vestas Wind Systems A/S | Method and system for improving grid stability based on infeed of renewable energy |
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2019
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP4304040A1 (en) * | 2022-06-28 | 2024-01-10 | Vestas Wind Systems A/S | Method and system for improving grid stability based on infeed of renewable energy |
| CN115441513A (en) * | 2022-08-05 | 2022-12-06 | 国网冀北电力有限公司电力科学研究院 | Phase modulator determining method and device suitable for new energy station |
| CN116402412A (en) * | 2023-06-09 | 2023-07-07 | 国网江西省电力有限公司电力科学研究院 | Power grid strength evaluation method and system containing high-proportion new energy |
| CN116402412B (en) * | 2023-06-09 | 2023-09-12 | 国网江西省电力有限公司电力科学研究院 | New energy-containing power grid strength evaluation method and system |
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