A reactive compensation configuration method for offshore wind farms

Abstract

The present invention provides a reactive power compensation configuration method for an offshore wind farm. First, the capacitive reactive power shortfall Q during the operation of the offshore wind farm is calculated. C and the inductive reactive power shortage Q during the operation of offshore wind farms L Then, based on the reactive power control capability of the offshore wind turbine itself, the inductive reactive power adjustment range Q of the wind turbine under the grid power factor requirement is calculated. WL And the wind turbine capacitive reactive power adjustment range Q WC Finally, the reactive power compensation configuration capacity of offshore wind farm is obtained as Q=max{Q C ‑Q WC ,Q L ‑Q WL The present invention takes the reactive power regulation capability of the wind turbine itself into consideration and makes appropriate corrections to the reactive compensation configuration capacity of the offshore wind farm, giving full play to the reactive power regulation capability of the wind turbine. This, in turn, saves investment in reactive compensation configuration of the offshore wind farm while meeting the reactive power voltage requirements of the offshore wind farm connected to the power system.

Description

Technical Field

[0001] The present invention belongs to the field of new energy technology and relates to a reactive power compensation configuration method for an offshore wind farm. Background Art

[0002] Offshore wind power has the characteristics of high stability of sea wind resources, large power generation capacity, no occupation of scarce land resources and less environmental pollution. It is a new energy power generation technology with great conditions for large-scale development and commercial prospects.

[0003] Offshore wind farms use submarine cables to transmit power, and AC submarine cables generally have high capacitive charging power, which is more pronounced over long distances and with larger cross-sections. Therefore, considering the impact of submarine cable capacitive charging power, offshore wind farms differ from onshore wind farms in terms of reactive power characteristics, necessitating the use of reactive power compensation configurations for offshore wind farms. However, current reactive power compensation configurations for offshore wind farms fail to account for the impact of submarine cable capacitive charging power and the reactive power regulation capabilities of the wind turbines themselves. Consequently, reactive power compensation configurations are generally large in capacity and require high investment costs. Summary of the Invention

[0004] In order to solve the problems described in the background technology, the present invention provides a reactive power compensation configuration method for an offshore wind farm.

[0005] The technical solution of the present invention comprises the following steps:

[0006] Step 1: Calculate the capacitive reactive power shortfall Q during the operation of the offshore wind farm based on the inductive reactive power consumption of the offshore wind turbine box transformer, collector line, booster station main transformer and outgoing submarine cable. C ;

[0007] Step 2: Calculate the inductive reactive power shortage Q during the operation of the offshore wind farm based on the capacitive reactive power consumption of the offshore wind farm's collection lines and transmission cables. L ;

[0008] Step 3: Based on the reactive power control capability of the offshore wind turbine itself, calculate the wind turbine inductive reactive power adjustment range Q under the grid power factor requirement. WL And the wind turbine capacitive reactive power adjustment range Q WC ;

[0009] Step 4: Obtain the reactive power compensation configuration capacity of the offshore wind farm Q = max{Q C -Q WC ,Q L -Q WL}.

[0010] Furthermore, in step 1, the capacitive reactive power shortage Q during the operation of the offshore wind farm C Expressed as:

[0011] Q C =Q C1 +Q C2 +Q C3 +Q C4 ,

[0012] Among them, the wind box variable inductive reactive power consumption Q C1 Expressed as:

[0013]

[0014] In the above formula, U wd % is the short-circuit impedance of the fan box; I we is the working current of the high-voltage side of the fan box transformer, I wN I is the rated current of the high-voltage side of the fan box transformer; w0 % is the no-load current of the fan box; S wt The rated capacity of the fan box; n w Change the number of fan boxes;

[0015] Inductive reactive power consumption of collector line Q C2 Expressed as:

[0016]

[0017] In the above formula, I Nli is the rated current of the i-th collector circuit; Ω li is the average reactance of the submarine cable of the i-th collector line; L li is the length of the i-th collector line; m is the number of collector line loops;

[0018] Inductive reactive power consumption of main transformer in booster station Q C3 Expressed as:

[0019]

[0020] In the above formula, U d % is the short-circuit impedance of the main transformer; I e is the main transformer low-side operating current, I N The rated current of the main transformer low voltage side; I0% is the no-load current of the main transformer; S t The rated capacity of the main transformer; n is the number of main transformers;

[0021] Inductive reactive power consumption of the outgoing submarine cable Q C4 Expressed as:

[0022]

[0023] In the above formula, INu Rated current of the outgoing submarine cable; Ω u is the average reactance of the sending submarine cable; L u The length of the submarine cable sent out.

[0024] Furthermore, in step 2, the inductive reactive power shortage Q during the operation of the offshore wind farm is L Expressed as:

[0025] Q L =Q L1 +Q L2 ,

[0026] Among them, the capacitive reactive power consumption of the collector line Q L1 Expressed as:

[0027]

[0028] In the above formula, I Nli is the rated current of the i-th collector circuit; G li is the average susceptance of the submarine cable of the i-th collector line; L li is the length of the i-th collector line; m is the number of collector line loops;

[0029] Transmitting submarine cable capacitive reactive power consumption Q L2 Expressed as:

[0030]

[0031] In the above formula, I Nu G is the rated current of the outgoing submarine cable; u is the average susceptance of the sending submarine cable; L u The length of the submarine cable sent out.

[0032] Furthermore, in step 3, the wind turbine inductive reactive power adjustment range Q WL Expressed as:

[0033]

[0034] Wind turbine capacitive reactive power adjustment range Q WC Expressed as:

[0035]

[0036] In the above formula, P N is the rated active power of the wind turbine; s L The required value of inductive power factor for wind farm access to power system; s C n is the required value of capacitive power factor for wind farm access to power system; wt is the number of fans with adjustable reactive power.

[0037] Compared with the existing technology, the present invention configures reactive power compensation for offshore wind farms based on the inductive and capacitive reactive power requirements of offshore wind farms, taking into account the impact of capacitive charging power of submarine cables and the fact that wind turbines with independent active-reactive power control based on dq decoupling typically have a certain degree of reactive power regulation capability. This invention takes into account the reactive power regulation capability of the wind turbines themselves and appropriately modifies the reactive power compensation configuration capacity of the offshore wind farm, fully utilizing the reactive power regulation capability of the wind turbines. This, in turn, reduces investment in reactive power compensation configuration for offshore wind farms while meeting the reactive voltage requirements for offshore wind farm access to the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the curve diagram of the inductive and capacitive reactive power adjustment range of the wind turbine. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0040] The reactive power compensation configuration method for offshore wind farms is described in detail as follows.

[0041] Step 1: Calculate the capacitive reactive power shortfall Q during the operation of the offshore wind farm based on the inductive reactive power consumption of the offshore wind turbine box transformer, collector line, booster station main transformer and outgoing submarine cable. C .

[0042] Capacitive reactive power shortfall Q during offshore wind farm operation C Expressed as:

[0043] Q C =Q C1 +Q C2 +Q C3 +Q C4 ,

[0044] Among them, the wind box variable inductive reactive power consumption Q C1 Expressed as:

[0045]

[0046] In the above formula, U wd % is the short-circuit impedance of the fan box; I we is the working current of the high-voltage side of the fan box transformer, I wN I is the rated current of the high-voltage side of the fan box transformer; w0 % is the no-load current of the fan box; S wt The rated capacity of the fan box; nw Change the number of fan boxes;

[0047] Inductive reactive power consumption of collector line Q C2 Expressed as:

[0048]

[0049] In the above formula, I Nli is the rated current of the i-th collector circuit; Ω li is the average reactance of the submarine cable of the i-th collector line; L li is the length of the i-th collector line; m is the number of collector line loops;

[0050] Inductive reactive power consumption of main transformer in booster station Q C3 Expressed as:

[0051]

[0052] In the above formula, U d % is the short-circuit impedance of the main transformer; I e is the main transformer low-side operating current, I N The rated current of the main transformer low voltage side; I0% is the no-load current of the main transformer; S t The rated capacity of the main transformer; n is the number of main transformers;

[0053] Inductive reactive power consumption of the outgoing submarine cable Q C4 Expressed as:

[0054]

[0055] In the above formula, I Nu Rated current of the outgoing submarine cable; Ω u is the average reactance of the sending submarine cable; L u The length of the submarine cable sent out.

[0056] Step 2: Calculate the inductive reactive power shortage Q during the operation of the offshore wind farm based on the capacitive reactive power consumption of the offshore wind farm's collection lines and transmission cables. L .

[0057] Inductive reactive power shortage Q during offshore wind farm operation L Expressed as:

[0058] Q L =Q L1 +Q L2 ,

[0059] Among them, the capacitive reactive power consumption of the collector line Q L1 Expressed as:

[0060]

[0061] In the above formula, I Nli is the rated current of the i-th collector circuit; G li is the average susceptance of the submarine cable of the i-th collector line; L li is the length of the i-th collector line; m is the number of collector line loops;

[0062] Transmitting submarine cable capacitive reactive power consumption Q L2 Expressed as:

[0063]

[0064] In the above formula, I Nu G is the rated current of the outgoing submarine cable; u is the average susceptance of the sending submarine cable; L u The length of the submarine cable sent out.

[0065] Step 3: Based on the reactive power control capability of the offshore wind turbine itself, calculate the wind turbine inductive reactive power adjustment range Q under the grid power factor requirement. WL And the wind turbine capacitive reactive power adjustment range Q WC .

[0066] Wind turbine inductive reactive power adjustment range Q WL Expressed as:

[0067]

[0068] Wind turbine capacitive reactive power adjustment range Q WC Expressed as:

[0069]

[0070] In the above formula, P N is the rated active power of the wind turbine; s L The required value of inductive power factor for wind farm access to power system; s C n is the required value of capacitive power factor for wind farm access to power system; wt is the number of fans with adjustable reactive power.

[0071] Step 4: Obtain the reactive compensation configuration capacity Q of the offshore wind farm.

[0072] The reactive power compensation configuration capacity Q of offshore wind farm is expressed as:

[0073] Q=max{ΔQ C ,ΔQ L}.

[0074] In the above formula, ΔQ C =Q C -Q WC =Q C1+Q C2 +Q C3 +Q C4 -Q WC ,

[0075] ΔQ L =Q L -Q WL =Q L1 +Q L2 -Q WL .

[0076] Example

[0077] Taking a 1000MW offshore wind farm as an example, the wind farm contains three main transformers with capacities of 400MVA, 400MVA, and 200MVA respectively. Every five 8MW wind turbines in the wind farm form a collector line, with a total of 25 collector lines. The transmission capacity of a single collector line is 40MW. The medium-voltage submarine cable model of the collector line is: HYJQF41-F48 / 66kV 3×300mm 2 The outgoing submarine cable uses 5 loops of HYJQF41-F 127 / 220kV 3×(1×500)mm 2 High-voltage submarine cable.

[0078] According to calculations, without considering the reactive power regulation capability of the wind turbine itself, the reactive power compensation capacity required by the offshore wind farm is Q = max {Q C ,Q L}=240Mvar.

[0079] Considering that half of the wind turbines in the wind farm have reactive power regulation capabilities, according to the wind turbine power characteristics, the wind turbine inductive and capacitive reactive power regulation range curves are drawn, as shown in Figure 2. Figure 1 As shown. Figure 1 It can be seen that when the wind turbine operates at rated active power and has the ability to adjust reactive power within the power factor range of ±0.98, its reactive power adjustment range is approximately 20% of the wind turbine's rated capacity. Therefore, considering the equal adjustment capabilities of the wind turbine's inductive and capacitive reactive power, the reactive power adjustment range is Q WL =Q WC =100MW.

[0080] In summary, considering the adjustable range of wind turbine reactive power, the inductive and capacitive reactive power shortage of offshore wind farm is corrected, and the reactive compensation configuration capacity of offshore wind farm is obtained as Q=max{ΔQ C ,ΔQ L}=140MW.

[0081] In this embodiment, the reactive power compensation configuration capacity of the offshore wind farm is optimized based on the influence of the capacitive charging power of the submarine cable. While meeting the reactive power voltage requirements of the offshore wind farm connected to the power system, the reactive power compensation configuration of the offshore wind farm can be reduced by about 100MW, saving about 8 million yuan in investment in the reactive power compensation configuration of the offshore wind farm.

[0082] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the application can adopt 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. The scheme in the embodiment of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal translation scripting language JavaScript, etc.

[0083] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0084] These computer program instructions may 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, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0085] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0086] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0087] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A reactive power compensation configuration method for an offshore wind farm, characterized in that: The following steps are involved: Step 1: Calculate the capacitive reactive power shortfall Q during the operation of the offshore wind farm based on the inductive reactive power consumption of the offshore wind turbine box transformer, collector line, booster station main transformer and outgoing submarine cable. C The capacitive reactive power shortage Q during the operation of the offshore wind farm C Expressed as: Q C =Q C1 +Q C2 +Q C3 +Q C4 , Among them, the wind box variable inductive reactive power consumption Q C1 Expressed as: In the above formula, U wd % is the short-circuit impedance of the fan box; I we is the working current of the high-voltage side of the fan box transformer, I wN I is the rated current of the high-voltage side of the fan box transformer; w0 % is the no-load current of the fan box; S wt The rated capacity of the fan box; n w Change the number of fan boxes; Inductive reactive power consumption of collector line Q C2 Expressed as: In the above formula, I Nli is the rated current of the i-th collector circuit; Ω li is the average reactance of the submarine cable of the i-th collector line; L li is the length of the i-th collector line; m is the number of collector line loops; Inductive reactive power consumption of main transformer in booster station Q C3 Expressed as: In the above formula, U d % is the short-circuit impedance of the main transformer; I e is the main transformer low-side operating current, I N The rated current of the main transformer low voltage side; I0% is the no-load current of the main transformer; S t The rated capacity of the main transformer; n is the number of main transformers; Inductive reactive power consumption of the outgoing submarine cable Q C4 Expressed as: In the above formula, I Nu Rated current of the outgoing submarine cable; Ω u is the average reactance of the sending submarine cable; L u The length of the submarine cable sent out; Step 2: Calculate the inductive reactive power shortage Q during the operation of the offshore wind farm based on the capacitive reactive power consumption of the offshore wind farm's collection lines and transmission cables. L The inductive reactive power shortage Q during the operation of the offshore wind farm L Expressed as: Q L =Q L1 +Q L2 , Among them, the capacitive reactive power consumption of the collector line Q L1 Expressed as: In the above formula, I Nli is the rated current of the i-th collector circuit; G li is the average susceptance of the submarine cable of the i-th collector line; L li is the length of the i-th collector line; m is the number of collector line loops; Transmitting submarine cable capacitive reactive power consumption Q L2 Expressed as: In the above formula, I Nu G is the rated current of the outgoing submarine cable; u is the average susceptance of the sending submarine cable; L u The length of the submarine cable sent out; Step 3: Based on the reactive power control capability of the offshore wind turbine itself, calculate the wind turbine inductive reactive power adjustment range Q under the grid power factor requirement. WL And the wind turbine capacitive reactive power adjustment range Q WC ; Step 4: Obtain the reactive power compensation configuration capacity of the offshore wind farm Q = max{Q C -Q WC ,Q L -Q WL }.

2. The method for configuring reactive power compensation for an offshore wind farm according to claim 1, wherein: In step 3, the wind turbine inductive reactive power adjustment range Q WL Expressed as: Wind turbine capacitive reactive power adjustment range Q WC Expressed as: In the above formula, P N is the rated active power of the wind turbine; s L The required value of inductive power factor for wind farm access to power system; s C n is the required value of capacitive power factor for wind farm access to power system; wt is the number of fans with adjustable reactive power.

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