A method and device for determining the short-circuit ratio of a new energy power station

Abstract

The present invention relates to a method and device for determining the short-circuit ratio of a new energy power station, including: determining the short-circuit capacity on the bus side in the collection station according to the short-circuit capacity at the grid connection point of the collection station; determining the short-circuit capacity at the grid connection point of each new energy power station in the collection station according to the short-circuit capacity on the bus side in the collection station; determining the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity at the grid connection point of each new energy power station in the collection station; the short-circuit ratio of the new energy power station obtained by the present invention is more accurate, and can provide accurate support for the evaluation of new energy grid connection oscillation and the planning and management of new energy.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy, and particularly relates to a method and device for determining the short-circuit ratio of a new energy power station. Background Art

[0002] Due to the large-scale use of new energy power generation in remote areas far from the load center, the grid strength is weak, and the stability problem of the new energy power generation system is prominent. New energy grid-connected oscillation is the main influencing factor of the stability problem. Its essence is an instability problem caused by the interaction between a new energy power station and a weak grid. The weaker the grid into which the new energy power station is connected, the greater the possibility of oscillation. Therefore, the assessment of grid strength is one of the key contents of the oscillation risk assessment of the new energy grid-connected system.

[0003] In power system analysis, the strength of the grid is usually described by the short-circuit ratio. When a new energy power station is connected to the grid by means of multi-station aggregation and boosting, that is, when there is a series connection of multiple power stations, how to accurately calculate the short-circuit ratio of the new energy power station is an urgent problem to be solved in this field. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is a method and device for determining the short-circuit ratio of a new energy power station. First, based on the short-circuit capacity of the connection point of the aggregation station, the short-circuit capacity of the bus side in the aggregation station is determined, and then the short-circuit capacity of the connection point of each new energy power station in the aggregation station is determined. Finally, the short-circuit ratio of the new energy power station is calculated. The short-circuit ratio of the new energy power station obtained by the present invention is more accurate, and can provide accurate support for the new energy grid-connected oscillation assessment and new energy planning management.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] The present invention provides a method for determining the short-circuit ratio of a new energy power station, which is improved in that the method includes:

[0007] Determine the short-circuit capacity of the bus side in the aggregation station according to the short-circuit capacity of the connection point of the aggregation station;

[0008] Determine the short-circuit capacity of the connection point of each new energy power station in the aggregation station according to the short-circuit capacity of the bus side in the aggregation station;

[0009] Determine the short-circuit ratio of each new energy power station in the aggregation station according to the short-circuit capacity of the connection point of each new energy power station in the aggregation station;

[0010] Wherein, the short-circuit capacity of the bus side in the aggregation station includes: the short-circuit capacity of the high-voltage bus side, the short-circuit capacity of the medium-voltage bus side, and the short-circuit capacity of the low-voltage bus side.

[0011] Preferably, the step of determining the short-circuit capacity of the bus side in the aggregation station according to the short-circuit capacity of the connection point of the aggregation station includes:

[0012] Obtain the short-circuit capacity of the grid connection point of the collection station, and determine the short-circuit capacity on the bus side in the collection station according to the following formula:

[0013]

[0014] In the formula, SC H is the short-circuit capacity of the high-voltage bus side of the collection station, SC M is the short-circuit capacity of the medium-voltage bus side in the collection station, SC L is the short-circuit capacity of the low-voltage bus side of the collection station, S is the rated capacity of the collection station, S H is the rated capacity of the high-voltage bus side of the collection station, U H is the rated voltage of the high-voltage bus side of the collection station, Z H,M is the line impedance between the high-voltage bus and the medium-voltage bus of the collection station, Z H,L is the line impedance between the high-voltage bus and the low-voltage bus of the collection station, S M is the rated capacity of the medium-voltage bus side of the collection station, S L is the rated capacity of the low-voltage bus side of the collection station, and SC is the short-circuit capacity of the grid connection point of the collection station.

[0015] Furthermore, the obtaining of the short-circuit capacity of the grid connection point of the collection station includes:

[0016] If the grid connection point of the collection station is connected to the power grid, determine the short-circuit capacity SC of the grid connection point of the collection station according to the following formula:

[0017] SC = SC0

[0018] In the formula, SC0 is the short-circuit capacity of the grid connection point of the power grid;

[0019] If the grid connection point of the collection station is connected to the high-voltage bus of other collection stations, determine the short-circuit capacity SC of the grid connection point of the collection station according to the following formula:

[0020]

[0021] In the formula, Z is the line impedance between the grid connection point of the collection station and the high-voltage bus of other collection stations, and SC′ is the short-circuit capacity allocated by the high-voltage bus of other collection stations to the collection station;

[0022] Among them, determine the rated capacity S of the collection station according to the following formula:

[0023]

[0024] In the formula, S j is the rated capacity of the jth new energy power station on the medium-voltage bus side and the low-voltage bus side of the collection station, j ∈ [1, J], and J is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station.

[0025] Preferably, determining the short-circuit capacity of each new energy power station connection point in the collection station according to the short-circuit capacity on the bus side of the collection station includes:

[0026] Determine the short-circuit capacity SC of the connection point of the j-th new energy power station according to the following formula j :

[0027]

[0028] In the formula, U M is the rated voltage of the medium-voltage bus in the collection station, U L is the rated voltage of the low-voltage bus in the collection station, Z j is the line impedance between the connection point of the j-th new energy power station and the affiliated bus, j ∈ (1,..., J',..., J), J' is the total number of new energy power stations on the medium-voltage bus side, J is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station, J - J' is the total number of new energy power stations on the low-voltage bus side of the collection station, S j is the rated capacity of the j-th new energy power station in the collection station, S M is the rated capacity of the medium-voltage bus side of the collection station, SC M is the short-circuit capacity of the medium-voltage bus side of the collection station, S L is the rated capacity of the low-voltage bus side of the collection station, SC L is the short-circuit capacity of the low-voltage bus side of the collection station.

[0029] Preferably, determining the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity of each new energy power station connection point in the collection station includes:

[0030] Determine the short-circuit ratio R of the j-th new energy power station in the collection station according to the following formula j :

[0031]

[0032] In the formula, SC j is the short-circuit capacity of the connection point of the j-th new energy power station in the collection station, S j is the rated capacity of the j-th new energy power station in the collection station.

[0033] Based on the same inventive concept, the present invention also provides a device for determining the short-circuit ratio of a new energy power station, which is improved in that the device includes:

[0034] The first determination unit is used to determine the short-circuit capacity on the bus side of the collection station according to the short-circuit capacity of the collection station connection point;

[0035] The second determination unit is used to determine the short-circuit capacity of each new energy power station connection point in the collection station according to the short-circuit capacity on the bus side of the collection station;

[0036] A third determination unit, configured to determine the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity of the connection points of each new energy power station in the collection station;

[0037] Wherein, the short-circuit capacity on the bus side in the collection station includes: the short-circuit capacity on the high-voltage bus side, the short-circuit capacity on the medium-voltage bus side, and the short-circuit capacity on the low-voltage bus side.

[0038] Preferably, the first determination unit includes:

[0039] An acquisition unit, configured to acquire the short-circuit capacity of the connection point of the collection station;

[0040] A determination subunit, configured to determine the short-circuit capacity on the bus side in the collection station according to the following formula:

[0041]

[0042] In the formula, SC H is the short-circuit capacity on the high-voltage bus side of the collection station, SC M is the short-circuit capacity on the medium-voltage bus side of the collection station, SC L is the short-circuit capacity on the low-voltage bus side of the collection station, S is the rated capacity of the collection station, S H is the rated capacity on the high-voltage bus side of the collection station, U H is the rated voltage on the high-voltage bus side of the collection station, Z H,M is the line impedance between the high-voltage bus and the medium-voltage bus of the collection station, Z H,L is the line impedance between the high-voltage bus and the low-voltage bus of the collection station, S M is the rated capacity on the medium-voltage bus side of the collection station, S L is the rated capacity on the low-voltage bus side of the collection station, and SC is the short-circuit capacity of the connection point of the collection station.

[0043] Further, the acquisition unit is specifically configured to:

[0044] If the connection point of the collection station is connected to the power grid, the short-circuit capacity SC of the connection point of the collection station is determined according to the following formula:

[0045] SC = SC0

[0046] In the formula, SC0 is the short-circuit capacity of the power grid connection point;

[0047] If the connection point of the collection station is connected to the high-voltage bus of other collection stations, the short-circuit capacity SC of the connection point of the collection station is determined according to the following formula:

[0048]

[0049] In the formula, Z is the line impedance between the grid connection point of the collection station and the high-voltage bus of other collection stations, and SC′ is the short-circuit capacity allocated to the collection station by the high-voltage bus of other collection stations;

[0050] Among them, the rated capacity S of the collection station is determined according to the following formula:

[0051]

[0052] In the formula, S j is the rated capacity of the j-th new energy power station on the medium-voltage bus side and the low-voltage bus side of the collection station, j ∈ [1, J], and J is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station.

[0053] Preferably, the second determination unit is specifically used for:

[0054] Determine the short-circuit capacity SC of the grid connection point of the j-th new energy power station according to the following formula j :

[0055]

[0056] In the formula, U M is the rated voltage of the medium-voltage bus of the collection station, U L is the rated voltage of the low-voltage bus of the collection station, Z j is the line impedance between the grid connection point of the j-th new energy power station and the affiliated bus, j ∈ (1, …, J′, …, J), J′ is the total number of new energy power stations on the medium-voltage bus side, J is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station, J - J′ is the total number of new energy power stations on the low-voltage bus side of the collection station, S j is the rated capacity of the j-th new energy power station in the collection station, S M is the rated capacity of the medium-voltage bus side of the collection station, SC M is the short-circuit capacity of the medium-voltage bus side of the collection station, S L is the rated capacity of the low-voltage bus side of the collection station, SC L is the short-circuit capacity of the low-voltage bus side of the collection station.

[0057] Preferably, the third determination unit is specifically used for:

[0058] Determine the short-circuit ratio R of the j-th new energy power station in the collection station according to the following formula j :

[0059]

[0060] In the formula, SC j is the short-circuit capacity of the grid connection point of the j-th new energy power station in the collection station, S j is the rated capacity of the j-th new energy power station in the collection station.

[0061] Compared with the closest prior art, the beneficial effects of the present invention are as follows:

[0062] A method and device for determining the short-circuit ratio of a new energy power station provided by the present invention include: determining the short-circuit capacity on the bus side in the collection station according to the short-circuit capacity at the grid connection point of the collection station; determining the short-circuit capacity at the grid connection point of each new energy power station in the collection station according to the short-circuit capacity on the bus side in the collection station; determining the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity at the grid connection point of each new energy power station in the collection station. When obtaining the short-circuit capacity at the grid connection point of the collection station, the present invention considers the distribution of the short-circuit capacity among multiple series-connected collection stations and the impedance of the transmission line between the grid connection point of the collection station and the high-voltage bus of other collection stations. When obtaining the short-circuit capacity at the grid connection point of the new energy power station, the present invention considers the distribution of the short-circuit capacity among multiple power stations and the impedance of the transmission line between the grid connection point of the new energy power station and the bus to which it belongs, making the obtained short-circuit ratio of the new energy power station more accurate, and providing accurate support for the evaluation of new energy grid connection oscillation and the planning and management of new energy. Description of the Drawings

[0063] Figure 1 is a schematic diagram of the calculation principle of the short-circuit ratio of a new energy power station;

[0064] Figure 2 is a schematic diagram of the structure of a new energy power station in the first embodiment;

[0065] Figure 3 is a flow chart of the method for determining the short-circuit ratio of a new energy power station of the present invention;

[0066] Figure 4 is a diagram of the short-circuit capacity distribution of the collection station in the first embodiment;

[0067] Figure 5 is a schematic diagram of the device for determining the short-circuit ratio of a new energy power station of the present invention

[0068] Figure 6a is a schematic diagram of the structure of the collection station in the second embodiment;

[0069] Figure 6b is a diagram of the short-circuit capacity distribution of the collection station in the second embodiment. Detailed Description of the Invention

[0070] The following further elaborates on the specific embodiments of the present invention with reference to the drawings.

[0071] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0072] In power system analysis, the strength of the power grid is usually described by the short-circuit ratio (SCR), as Figure 1 shown, the definition of the short-circuit ratio of a new energy power station is:

[0073]

[0074] In the formula, SCR RE is the short-circuit ratio of this new energy power station, S N,RE is the rated capacity of this new energy power station, SC PCC is the short-circuit capacity of the grid connection point of this new energy power station, and the calculation formula is as follows.

[0075] SC PCC = U N,PCC I SC,PCC

[0076] In the formula, U N,PCC is the rated voltage of the grid connection point, and I SC,PCC is the short-circuit current calculated for a three-phase metal short-circuit fault at the grid connection point.

[0077] Figure 1 In, U S is the infinite bus voltage, Z G is the line impedance between the grid connection point of the new energy power station and the infinite bus, which is generally composed of the impedances of components such as transmission lines and transformers. Assuming U N,PCC ≈ U S , then

[0078]

[0079] Therefore,

[0080] In the formula, Z N,RE is the impedance under the rated capacity of this new energy power station, and Z G,PU is the per-unit value of the grid impedance based on the impedance of the new energy power station.

[0081] It can be seen that the grid-connected short-circuit ratio of a new energy power station is related not only to the rated capacity of the new energy power station itself and the rated voltage of the grid connection point, but also to the connection impedance of its connection to the grid. Given the rated capacity of the new energy power station and the rated voltage of the grid connection point, if the connection impedance of its connection to the grid is larger, the short-circuit capacity of the grid connection point is smaller, the short-circuit ratio is smaller, and the grid is relatively weaker; conversely, the short-circuit ratio is larger and the grid is relatively stronger. Given the rated voltage of the grid connection point of the new energy power station and the connection impedance of its connection to the grid, the larger the rated capacity of the power station, the smaller the short-circuit ratio and the relatively weaker the grid; conversely, the larger the short-circuit ratio and the relatively stronger the grid.

[0082] However, new energy power stations are connected to the grid through the method of multi-station aggregation and boosting, and there is an access method of multi-station series connection. When short-circuit faults occur in the grid, wind, light and other new energy power generations will enter the low-voltage ride-through process and cannot provide stable short-circuit current to the grid. Therefore, the short-circuit current or short-circuit capacity involved in the present invention is considered to be provided by the grid side, and new energy power generations do not provide short-circuit current or short-circuit capacity.

[0083] For example: Figure 2 The figure shows a schematic diagram of the structure of a certain wind power aggregation system. It can be seen that wind farms with different capacities are connected to two aggregation stations through 35 kV or 110 kV lines of different distances, boosted to 220 kV and then connected to the grid. At the same time, the west aggregation station is connected in series to the east aggregation station and then connected to the grid.

[0084] Currently, the main body of new energy power generation development and grid connection management is the power station. Therefore, it is more important and easier to implement the calculation of the short-circuit ratio and the assessment of oscillation risk for the power station. However, for Figure 2 a certain power station in the shown aggregation system, if the above short-circuit ratio calculation method is directly adopted, the influence of other wind farms needs to be ignored, and the calculated short-circuit ratio is relatively large, which will affect the assessment result of the oscillation risk.

[0085] Therefore, the present invention proposes a method for determining the short-circuit ratio, which considers the differences in the capacities of multiple power stations and the lengths of grid-connected transmission lines in the aggregation system, realizes the rapid calculation of the short-circuit ratio of each power station, can be used for the assessment of oscillation risk, provides support for new energy planning and grid connection management, and the technical solution of the present invention is described in detail through the following embodiments:

[0086] Embodiment 1

[0087] As Figure 3 shown, the method for determining the short-circuit ratio proposed by the present invention includes:

[0088] Determine the short-circuit capacity on the bus side in the aggregation station according to the short-circuit capacity of the grid connection point of the aggregation station;

[0089] Determine the short-circuit capacity of the grid connection points of each new energy power station in the collection station according to the short-circuit capacity on the bus side of the collection station;

[0090] Determine the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity of the grid connection points of each new energy power station in the collection station;

[0091] Among them, the short-circuit capacity on the bus side of the collection station includes: the short-circuit capacity on the high-voltage bus side, the short-circuit capacity on the medium-voltage bus side, and the short-circuit capacity on the low-voltage bus side.

[0092] As Figure 4 shown, the new energy power stations are connected to the grid through the method of multi-station collection and boosting. Multiple power stations are connected in series. There are N collection stations in the new energy collection system connected in series to the grid. The grid connection point of collection station 1 is connected to the grid. The grid connection point of collection station 2 is connected to the high-voltage bus of collection station 1, the grid connection point of collection station 3 is connected to the high-voltage bus of collection station 2, ······, the grid connection point of collection station N is connected to the high-voltage bus of collection station N-1;

[0093] Among them, the three-winding transformer is used to connect the high, medium, and low-voltage buses of the collection station. A total of J new energy power stations are connected under each collection station, and J′ are connected to the medium-voltage bus side, and J-J′ are connected to the low-voltage bus side. Figure 4 Regard the high, medium, and low bus voltages of all collection stations as the same voltage level respectively, and regard the line impedances of each collection station as the same. In actual applications, calculations are carried out according to actual data; in the power transmission system, the impedances of lines and transformers are mainly inductive, that is, R << X. Therefore, the resistive values of the line and transformer impedances involved in the present invention are all ignored, that is, Z≈jX = X, and the impedance Z only includes the inductive reactance X.

[0094] Specifically, the determination of the short-circuit capacity on the bus side of the collection station according to the short-circuit capacity of the grid connection point of the collection station includes:

[0095] Obtain the short-circuit capacity of the grid connection point of the collection station, and determine the short-circuit capacity on the bus side of the collection station according to the following formula:

[0096]

[0097] In the formula, SC H is the short-circuit capacity on the high-voltage bus side of the collection station, SC M is the short-circuit capacity on the medium-voltage bus side of the collection station, SC L is the short-circuit capacity on the low-voltage bus side of the collection station, S is the rated capacity of the collection station, S H is the rated capacity on the high-voltage bus side of the collection station, U H is the rated voltage on the high-voltage bus side of the collection station, Z H,M is the line impedance between the high-voltage bus and the medium-voltage bus of the collection station, Z H,Lis the line impedance between the high-voltage bus and the low-voltage bus of the collection station, S M is the rated capacity on the medium-voltage bus side of the collection station, S L is the rated capacity on the low-voltage bus side of the collection station, SC is the short-circuit capacity of the grid connection point of the collection station;

[0098] Further, the obtaining of the short-circuit capacity of the grid connection point of the collection station includes:

[0099] If the grid connection point of the collection station is connected to the power grid (such as Figure 4 collection station 1 in), then the short-circuit capacity SC of the grid connection point of the collection station is determined by the following formula:

[0100] SC = SC0

[0101] In the formula, SC0 is the short-circuit capacity of the grid connection point of the power grid;

[0102] If the grid connection point of the collection station is connected to the high-voltage bus of other collection stations (such as Figure 4 collection station 2 in), then the short-circuit capacity SC of the grid connection point of the collection station is determined by the following formula:

[0103]

[0104] In the formula, Z is the line impedance between the grid connection point of the collection station and the high-voltage bus of other collection stations, SC′ is the short-circuit capacity allocated by the high-voltage bus of other collection stations to the collection station, SC′ = SC″ - SC″ H , SC″ is the short-circuit capacity of the grid connection point of other collection stations, SC″ H is the short-circuit capacity on the high-voltage bus side of other collection stations;

[0105] Among them, the rated capacity S of the collection station is determined by the following formula:

[0106]

[0107] In the formula, S i,j is the rated capacity of the jth new energy power station on the medium-voltage bus side and the low-voltage bus side of the collection station, j ∈ [1, J], and J is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station.

[0108] In order to more easily understand the above short-circuit capacity distribution process, the following takes collection station 1 and collection station 2 in embodiment 1 as examples for detailed description:

[0109] Short-circuit capacity on the high-voltage bus side of collection station 1: SC1 = SC0, S1 is the rated capacity of collection station 1 (the sum of the rated capacities of the new energy power stations on the medium-voltage bus and the low-voltage bus sides of collection station 1), S 1,H is the rated capacity on the high-voltage bus side of collection station 1, Si,j is the rated capacity of the j-th new energy power station in the i-th collection station in Embodiment 1.

[0110] Short-circuit capacity allocated from the high-voltage bus of Collection Station 1 to Collection Station 2: SC 1,2 = SC1 - SC 1,H ;

[0111] Short-circuit capacity on the high-voltage bus side of Collection Station 2: S2 is the rated capacity of Collection Station 2, S 2,H is the rated capacity on the high-voltage bus side of Collection Station 2, J is the total number of new energy power stations on the medium-voltage and low-voltage bus sides of the collection station. In Embodiment 1, the total number of new energy power stations on the medium-voltage and low-voltage bus sides of each collection station in the collection system is regarded as the same. N is the total number of collection stations in the collection system;

[0112] Short-circuit capacity allocated from the high-voltage bus of Collection Station 2 to Collection Station 3: SC 2,3 = SC2 - SC 2,H ;

[0113] Those skilled in the art can obtain the short-circuit capacities of Collection Stations 3 to N in Embodiment 1 by referring to the above distribution process of Collection Station 2.

[0114] In the embodiments provided by the present invention, determining the short-circuit capacity of the connection point of each new energy power station in the collection station according to the short-circuit capacity on the bus side of the collection station includes:

[0115] Determine the short-circuit capacity SC of the connection point of the j-th new energy power station according to the following formula j :

[0116]

[0117] In the formula, U M is the rated voltage of the medium-voltage bus of the collection station, U L is the rated voltage of the low-voltage bus of the collection station, Z j is the line impedance between the connection point of the j-th new energy power station and the affiliated bus, j ∈ (1, …, J′, …, J), J′ is the total number of new energy power stations on the medium-voltage bus side, J is the total number of new energy power stations on the medium-voltage and low-voltage bus sides of the collection station, S j is the rated capacity of the j-th new energy power station in the collection station, S M is the rated capacity on the medium-voltage bus side of the collection station, SC M is the short-circuit capacity on the medium-voltage bus side of the collection station, S L is the rated capacity on the low-voltage bus side of the collection station, SC L is the short-circuit capacity on the low-voltage bus side of the collection station.

[0118] Determining the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity of the connection points of each new energy power station in the collection station includes:

[0119] Determine the short-circuit ratio R of the j-th new energy power station in the collection station according to the following formula j :

[0120]

[0121] In the formula, SC j is the short-circuit capacity of the connection point of the j-th new energy power station in the collection station, and S j is the rated capacity of the j-th new energy power station in the collection station.

[0122] Based on the same inventive concept, the present invention also provides a device for determining the short-circuit ratio of a new energy power station, as Figure 5 shown, the device includes:

[0123] A first determination unit for determining the short-circuit capacity on the bus side in the collection station according to the short-circuit capacity of the connection point of the collection station;

[0124] A second determination unit for determining the short-circuit capacity of the connection point of each new energy power station in the collection station according to the short-circuit capacity on the bus side in the collection station;

[0125] A third determination unit for determining the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity of the connection point of each new energy power station in the collection station;

[0126] Among them, the short-circuit capacity on the bus side in the collection station includes: the short-circuit capacity on the high-voltage bus side, the short-circuit capacity on the medium-voltage bus side, and the short-circuit capacity on the low-voltage bus side.

[0127] In the specific implementation method of the present invention, the above first determination unit includes:

[0128] An acquisition unit for acquiring the short-circuit capacity of the connection point of the collection station;

[0129] A determination subunit for determining the short-circuit capacity on the bus side in the collection station according to the following formula:

[0130]

[0131] In the formula, SC H is the short-circuit capacity of the high-voltage bus side of the collection station, SC M is the short-circuit capacity of the medium-voltage bus side of the collection station, SC L is the short-circuit capacity of the low-voltage bus side of the collection station, S is the rated capacity of the collection station, and S H is the rated capacity of the high-voltage bus side of the collection station, U H is the rated voltage of the high-voltage bus side of the collection station, and Z H,MThe line impedance between the high-voltage bus and the medium-voltage bus of the collection station is Z H,L The line impedance between the high-voltage bus and the low-voltage bus of the collection station is S M The rated capacity on the medium-voltage bus side of the collection station is S L The rated capacity on the low-voltage bus side of the collection station. SC is the short-circuit capacity of the grid connection point of the collection station.

[0132] Furthermore, the obtaining unit is specifically configured to:

[0133] If the grid connection point of the collection station is connected to the power grid, the short-circuit capacity SC of the grid connection point of the collection station is determined according to the following formula:

[0134] SC = SC0

[0135] In the formula, SC0 is the short-circuit capacity of the grid connection point of the power grid;

[0136] If the grid connection point of the collection station is connected to the high-voltage bus of other collection stations, the short-circuit capacity SC of the grid connection point of the collection station is determined according to the following formula:

[0137]

[0138] In the formula, Z is the line impedance between the grid connection point of the collection station and the high-voltage bus of other collection stations, and SC′ is the short-circuit capacity allocated by the high-voltage bus of other collection stations to the collection station;

[0139] Among them, the rated capacity S of the collection station is determined according to the following formula:

[0140]

[0141] In the formula, S j is the rated capacity of the jth new energy power station on the medium-voltage bus side and the low-voltage bus side of the collection station, j ∈ [1, J], and J is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station.

[0142] In the specific implementation method of the present invention, the above-mentioned second determination unit is specifically configured to:

[0143] Determine the short-circuit capacity SC of the grid connection point of the jth new energy power station according to the following formula j :

[0144]

[0145] In the formula, U M is the rated voltage of the medium-voltage bus of the collection station, U L is the rated voltage of the low-voltage bus of the collection station, Z jis the line impedance between the grid connection point of the j-th new energy power station and the bus to which it belongs, j ∈ (1, …, J′, …, J), J′ is the total number of new energy power stations on the medium-voltage bus side, and J is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station, S j is the rated capacity of the j-th new energy power station in the collection station, S M is the rated capacity of the medium-voltage bus side of the collection station, SC M is the short-circuit capacity of the medium-voltage bus side of the collection station, S L is the rated capacity of the low-voltage bus side of the collection station, SC L is the short-circuit capacity of the low-voltage bus side of the collection station.

[0146] In the specific implementation method of the present invention, the above third determination unit is specifically used for:

[0147] Determine the short-circuit ratio R of the j-th new energy power station in the collection station according to the following formula j :

[0148]

[0149] In the formula, SC j is the short-circuit capacity of the grid connection point of the j-th new energy power station in the collection station, S j is the rated capacity of the j-th new energy power station in the collection station.

[0150] Embodiment 2

[0151] As Figure 6a shown, the collection stations are connected in parallel. Taking collection station 2 as an example:

[0152] The rated capacity of the 220 / 500 kV step-up transformer in collection station 2 is 1500 MW. Then, according to Figure 6a the line lengths and line parameters marked in, the line impedance of collection station 2 can be obtained as:

[0153] Z = 56.1 Ω, Z H,L = 16.67 Ω, Z1 = 6.32 Ω, Z2 = 0.22 Ω, Z3 = 6.93 Ω, Z4 = 5.63 Ω, Z5 = 1.99 Ω;

[0154] Line parameters: The model of the 500 kV transmission line is LGJK-4*630mm 2 , and the typical impedance value is 0.275 Ω / km. The model of the 220 kV transmission line is LGJ-400mm 2 , and the typical impedance value is 0.433 Ω / km;

[0155] Determine the short-circuit capacity in collection station 2:

[0156] As Figure 6bAs shown, given SC0 = 1650, then

[0157] Determine the short - circuit capacity of the connection points of Wind Farm 1, Wind Farm 2, Wind Farm 3, Wind Farm 4, and Wind Farm 5 in Sub - station 2:

[0158]

[0159]

[0160]

[0161]

[0162]

[0163] Wherein, Z1, Z2, Z3, Z4, and Z5 are the line impedances of Wind Farm 1, 2, 3, 4, and 5 to the low - voltage bus side;

[0164] Determine the short - circuit ratios of Wind Farm 1, Wind Farm 2, Wind Farm 3, Wind Farm 4, and Wind Farm 5:

[0165]

[0166]

[0167]

[0168]

[0169]

[0170] In summary, a method and device for determining the short - circuit ratio of a new - energy power station provided by the present invention include: determining the short - circuit capacity of the bus side in the sub - station according to the short - circuit capacity of the connection point of the sub - station; determining the short - circuit capacity of the connection point of each new - energy power station in the sub - station according to the short - circuit capacity of the bus side in the sub - station; determining the short - circuit ratio of each new - energy power station in the sub - station according to the short - circuit capacity of the connection point of each new - energy power station in the sub - station. When obtaining the short - circuit capacity of the connection point of the sub - station, the present invention considers the distribution of the short - circuit capacity among multiple series - connected sub - stations and the impedance of the transmission line between the connection point of the sub - station and the high - voltage bus of other sub - stations. When obtaining the short - circuit capacity of the connection point of the new - energy power station, the present invention considers the distribution of the short - circuit capacity among multiple power stations and the impedance of the transmission line between the connection point of the new - energy power station and the bus to which it belongs, making the obtained short - circuit ratio of the new - energy power station more accurate, and providing accurate support for new - energy grid - connection oscillation assessment and new - energy planning management.

[0171] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0172] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one or more of the flows Figure 1 or blocks or combinations of blocks.

[0173] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device that implements the functions specified in Figure 1 one or more of the flows Figure 1 or blocks or combinations of blocks.

[0174] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are performed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one or more of the flows Figure 1 or blocks or combinations of blocks.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific embodiments of the present invention. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for determining the short-circuit ratio of a new energy power station, characterized in that, The method includes: Determining the short-circuit capacity on the bus side in the collection station according to the short-circuit capacity at the grid connection point of the collection station; Determining the short-circuit capacity at the grid connection point of each new energy power station in the collection station according to the short-circuit capacity on the bus side in the collection station; Determining the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity at the grid connection point of each new energy power station in the collection station; Wherein, the short-circuit capacity on the bus side in the collection station includes: the short-circuit capacity on the high-voltage bus side, the short-circuit capacity on the medium-voltage bus side, and the short-circuit capacity on the low-voltage bus side; The determining the short-circuit capacity on the bus side in the collection station according to the short-circuit capacity at the grid connection point of the collection station includes: obtaining the short-circuit capacity at the grid connection point of the collection station; The obtaining the short-circuit capacity at the grid connection point of the collection station includes: If the grid connection point of the collection station is connected to the power grid, the short-circuit capacity of the grid connection point of the collection station shall be determined according to the following formula : Wherein, is the short-circuit capacity of the grid connection point of the power grid; If the grid connection point of the collection station is connected to the high-voltage busbar of other collection stations, the short-circuit capacity of the grid connection point of the collection station shall be determined according to the following formula : In the formula, is the line impedance between the grid connection point of the collection station and the high-voltage bus of other collection stations, is the short-circuit capacity allocated by the high-voltage bus of other collection stations to the collection station; Among them, the rated capacity of the gathering station is determined by the following formula :[[]]END]] Wherein, is the rated capacity of the j-th new energy power station on the medium-voltage bus side and the low-voltage bus side of the collection station, , and J is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station.

2. The method according to claim 1, characterized in that, Determining the short-circuit capacity on the bus side in the collection station according to the following formula: Wherein, is the short-circuit capacity on the high-voltage bus side of the collection station, is the short-circuit capacity on the medium-voltage bus side of the collection station, is the short-circuit capacity on the low-voltage bus side of the collection station, is the rated capacity of the collection station, is the rated capacity on the high-voltage bus side of the collection station, is the rated voltage on the high-voltage bus side of the collection station, is the line impedance between the high-voltage bus and the medium-voltage bus of the collection station, is the line impedance between the high-voltage bus and the low-voltage bus of the collection station, is the rated capacity on the medium-voltage bus side of the collection station, is the rated capacity on the low-voltage bus side of the collection station, is the short-circuit capacity at the grid connection point of the collection station.

3. The method according to claim 1, characterized in that, The determining the short-circuit capacity at the grid connection point of each new energy power station in the collection station according to the short-circuit capacity on the bus side in the collection station includes: Determine the short-circuit capacity of the connection point of the j-th new energy power station according to the following formula : Wherein, is the rated voltage of the medium-voltage busbar of the collection station, is the rated voltage of the low-voltage busbar of the collection station, is the line impedance between the grid connection point of the j-th new energy power station and the affiliated busbar, , is the total number of new energy power stations on the medium-voltage busbar side of the collection station, is the total number of new energy power stations on the medium-voltage busbar side and the low-voltage busbar side of the collection station, is the total number of new energy power stations on the low-voltage busbar side of the collection station, is the rated capacity of the j-th new energy power station in the collection station, is the rated capacity of the medium-voltage busbar side of the collection station, is the short-circuit capacity of the medium-voltage busbar side of the collection station, is the rated capacity of the low-voltage busbar side of the collection station, is the short-circuit capacity of the low-voltage busbar side of the collection station.

4. The method according to claim 1, wherein The determining the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity at the grid connection point of each new energy power station in the collection station includes: Determine the short-circuit ratio of the j-th new energy power station in the collection station according to the following formula : Wherein, is the short-circuit capacity of the grid connection point of the j-th new energy power station at the collection station, is the rated capacity of the j-th new energy power station in the collection station.

5. A short-circuit ratio determination device for a new energy power station, characterized in that, The device includes: A first determination unit, configured to determine the short-circuit capacity on the bus side in the collection station according to the short-circuit capacity at the grid connection point of the collection station; A second determination unit, configured to determine the short-circuit capacity at the grid connection point of each new energy power station in the collection station according to the short-circuit capacity on the bus side in the collection station; A third determination unit, configured to determine the short-circuit ratio of each new energy power station in the collection station according to the short-circuit capacity at the grid connection point of each new energy power station in the collection station; Wherein, the short-circuit capacity on the bus side in the collection station includes: the short-circuit capacity on the high-voltage bus side, the short-circuit capacity on the medium-voltage bus side, and the short-circuit capacity on the low-voltage bus side; The first determination unit includes: an obtaining unit, configured to obtain the short-circuit capacity at the grid connection point of the collection station; The obtaining unit is specifically configured to: If the grid connection point of the collection station is connected to the power grid, the short-circuit capacity of the grid connection point of the collection station shall be determined according to the following formula : Wherein, is the short-circuit capacity of the grid connection point of the power grid; If the grid connection point of the collection station is connected to the high-voltage busbar of other collection stations, the short-circuit capacity of the grid connection point of the collection station shall be determined according to the following formula : In the formula, is the line impedance between the grid connection point of the collection station and the high-voltage bus of other collection stations, is the short-circuit capacity allocated by the high-voltage bus of other collection stations to the collection station; Among them, the rated capacity of the gathering station is determined by the following formula : Wherein, is the rated capacity of the j-th new energy power station on the medium-voltage bus side and the low-voltage bus side of the collection station, , and J is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station.

6. The device according to claim 5, wherein The first determination unit further includes: a determination subunit; The determination subunit is configured to determine the short-circuit capacity on the bus side in the collection station according to the following formula: Wherein, is the short-circuit capacity on the high-voltage bus side of the collection station; is the short-circuit capacity on the medium-voltage bus side of the collection station; is the short-circuit capacity on the low-voltage bus side of the collection station; is the rated capacity of the collection station; is the rated capacity on the high-voltage bus side of the collection station; is the rated voltage on the high-voltage bus side of the collection station; is the line impedance between the high-voltage bus and the medium-voltage bus of the collection station; is the line impedance between the high-voltage bus and the low-voltage bus of the collection station; is the rated capacity on the medium-voltage bus side of the collection station; is the rated capacity on the low-voltage bus side of the collection station; is the short-circuit capacity at the grid connection point of the collection station.

7. The device according to claim 5, characterized in that, The second determination unit is specifically configured to: Determine the short-circuit capacity of the connection point of the j-th new energy power station according to the following formula : Wherein, is the rated voltage of the medium-voltage bus of the collection station, is the rated voltage of the low-voltage bus of the collection station, is the line impedance between the grid connection point of the j-th new energy power station and the affiliated bus, , is the total number of new energy power stations on the medium-voltage bus side of the collection station, is the total number of new energy power stations on the medium-voltage bus side and the low-voltage bus side of the collection station, is the total number of new energy power stations on the low-voltage bus side of the collection station, is the rated capacity of the j-th new energy power station in the collection station, is the rated capacity of the medium-voltage bus side of the collection station, is the short-circuit capacity of the medium-voltage bus side of the collection station, is the rated capacity of the low-voltage bus side of the collection station, is the short-circuit capacity of the low-voltage bus side of the collection station.

8. The device according to claim 5, characterized in that, The third determination unit is specifically configured to: Determine the short-circuit ratio of the j-th new energy power station in the collection station according to the following formula : Wherein, is the short-circuit capacity of the grid connection point of the j-th new energy power station at the collection station, is the rated capacity of the j-th new energy power station in the collection station.

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