CN115833243A - Centralized inversion and boosting integrated offshore wind power generation system and method - Google Patents
Centralized inversion and boosting integrated offshore wind power generation system and method Download PDFInfo
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- CN115833243A CN115833243A CN202211610789.3A CN202211610789A CN115833243A CN 115833243 A CN115833243 A CN 115833243A CN 202211610789 A CN202211610789 A CN 202211610789A CN 115833243 A CN115833243 A CN 115833243A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a centralized inversion and boosting integrated offshore wind power generation system and a method, wherein the system comprises a plurality of offshore wind turbine groups, and a single offshore wind turbine group comprises a plurality of series-connected wind turbines; a plurality of fans on the single offshore fan group are connected in series to the input end of one box inversion all-in-one machine through a primary direct current bus line; the output ends of a plurality of box inversion integrated machines corresponding to a plurality of offshore wind turbine groups are connected in parallel to the input end of a single offshore booster station through a secondary alternating current collecting line; the output end of the offshore booster station is connected to the input end of the onshore transformer substation through a submarine alternating current cable; and the output end of the onshore transformer substation is connected with a power grid. On one hand, the invention can improve the voltage grade of the direct current side, reduce the loss of the direct current side and is beneficial to reducing the volume and the weight of the box inversion all-in-one machine; on the other hand will many fan inverters and transformer be replaced with case contravariant all-in-one, reduce offshore wind power construction cost, can reduce the later stage operation and maintenance and overhaul the degree of difficulty.
Description
Technical Field
The invention belongs to the technical field of offshore wind power transmission and transformation, and particularly relates to a centralized inversion and boosting integrated offshore wind power generation system and method.
Background
With the development and application of offshore wind power technology, the scale of offshore wind power plants tends to be large, and the site selection tends to be deep and open sea. The offshore wind power development cost is an important factor for restricting the sustainable high-speed development of offshore wind power. In offshore wind power engineering, equipment cost of a fan, a transformer and the like and building installation engineering cost occupy a large proportion, and how to save the equipment cost and the building installation engineering cost is a great problem to be overcome in offshore wind power development. Particularly, when the offshore wind power fair era comes, a new technology needs to be developed urgently to reduce the development cost of offshore wind power and guarantee the investment profitability of offshore wind power projects. In an existing offshore wind power system, each wind turbine is individually provided with a wind driven generator, a rectifier, an inverter and a box type transformer, wherein the wind driven generator, the rectifier, the inverter and the box type transformer share one pile foundation platform. The mass and the volume of the inverter and the box-type transformer are large, the cost of a pile foundation platform can be increased, meanwhile, the investment cost of offshore wind power can be increased due to the excessive number of inverters and box-type transformer stations, and the operation, maintenance and overhaul difficulty is increased.
The chinese patent No. CN103023067B discloses a direct-drive wind power generation system based on a common dc bus, which converges and transmits electric energy generated by a plurality of wind power generation sets to a transformer substation for uniform inversion, and converts the electric energy into ac power with the same frequency and voltage as a power grid to feed the ac power into the power grid; and the voltages of the electric energy transmitted to the common direct current bus by the plurality of wind generating sets through the machine side converter are all equal. This patent adopts the direct current to collect to the machine side converter of many fans is the parallel structure, and direct current side voltage is the same with single fan machine side converter output voltage, fails to give full play to many fans advantage of voltage increase after establishing ties, and used cable length is long, and the cost is higher.
Disclosure of Invention
Aiming at the problems that an inverter and a box-type substation on a single fan platform of the existing offshore wind power generation system are large in mass and size, the invention provides the integrated offshore wind power generation system and the integrated offshore wind power generation method for centralized inversion and boosting.
The invention discloses a centralized inversion and boosting integrated offshore wind power generation system, which comprises a plurality of offshore wind turbine groups, wherein a single offshore wind turbine group comprises a plurality of series-connected wind turbines; a plurality of fans on the single offshore fan group are connected in series to the input end of one box inversion all-in-one machine through a primary direct current collection line; the output ends of a plurality of box inversion integrated machines corresponding to a plurality of offshore wind turbine groups are connected to the input end of a single offshore booster station through a secondary alternating current collection line; the output end of the single offshore booster station is connected to the input end of the onshore transformer substation through a submarine alternating current cable; and the output end of the onshore transformer substation is connected with a power grid.
Further, a single fan comprises a wind driven generator and a machine side rectifier matched with the wind driven generator.
Furthermore, a plurality of machine side rectifiers of the single offshore wind turbine group are connected in series through primary direct current collecting cables among the wind turbines.
Further, the control strategy of each fan-side rectifier is to keep outputting the same amount of current.
Furthermore, the single box inversion all-in-one machine comprises a centralized inverter positioned at the input end of the box inversion all-in-one machine and a box type transformer positioned at the output end of the box inversion all-in-one machine.
Further, the voltage level of the alternating current output by the box-type transformer in each offshore wind turbine group is the same.
Furthermore, the single box inversion all-in-one machine is arranged inside a tower barrel of the single fan.
The invention also discloses a centralized inversion and boosting integrated offshore wind power generation method, which comprises the following steps:
wind energy is converted into alternating current through wind power generators of a plurality of fans on an offshore fan group, the alternating current is converted into direct current with the same current grade through machine side rectifiers corresponding to the fans, and the direct current is transmitted to the input end of a box inversion integrated machine through a first-level direct current bus circuit;
the direct current with the same current level is converted into alternating current through a centralized inverter of the box inversion all-in-one machine, the alternating current with the same voltage level is obtained through first boosting output of a box type transformer, and the alternating current is connected to the input end of a single offshore boosting station in parallel through a secondary alternating current collecting line;
the alternating current with the same voltage grade after primary boosting is subjected to secondary boosting through the offshore boosting station, and the high-voltage alternating current output after secondary boosting is transmitted to the input end of the onshore transformer substation through the submarine alternating current cable;
and the high-voltage alternating current subjected to secondary boosting is transmitted to a power grid through an output end of the onshore transformer substation.
Compared with the prior art, the invention can obtain the following beneficial effects:
1. according to the invention, direct currents output by a plurality of fans are connected in series through the primary direct current collecting line, so that the voltage level of a direct current side can be improved, the loss of the direct current side is reduced, the cable consumption is optimized, the size and the weight of the box inversion all-in-one machine are favorably reduced, and the cost of the box inversion all-in-one machine foundation is reduced.
2. According to the invention, a plurality of fan inverters and transformers are replaced by a small number of box inversion integrated machines, so that the number of the fan inverters and the transformers can be greatly reduced, power cables between the fan inverters and the box-type transformers are saved, and the construction cost of offshore wind power is further reduced; meanwhile, the number of equipment is greatly reduced, and the later operation and maintenance difficulty and cost of the offshore wind farm can be reduced.
Drawings
FIG. 1 is a schematic diagram of a centralized inversion and boosting integrated offshore wind power generation system of the invention;
FIG. 2 is a basic control diagram of the machine side rectifier of the present invention;
fig. 3 is a basic control diagram of the centralized inverter of the present invention.
Reference numerals: 1. an offshore wind turbine group; 10. a fan; 101. a wind power generator; 102. a machine side rectifier; 103. a primary DC collection cable; 2. a primary direct current bus line; 3. a box inversion integrated machine; 31. a centralized inverter; 32. a box-type transformer; 4. a secondary alternating current collection bus; 5. an offshore booster station; 6. a subsea ac cable; 7. an onshore substation; 8. and (4) a power grid.
Detailed Description
The invention provides a centralized inversion and boosting integrated offshore wind power generation system, which can serially connect direct currents output by a plurality of fans through a primary direct current collecting line, can improve the voltage level of a direct current side, reduce the loss of the direct current side, reduce the number of fan inverters and transformers, and further reduce the construction and operation and maintenance costs of offshore wind power.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
As shown in fig. 1, the centralized inversion and boosting integrated offshore wind turbine system of the present invention includes a plurality of offshore wind turbine clusters 1, and a single offshore wind turbine cluster 1 includes a plurality of wind turbines 10. The wind turbine 10 includes a wind power generator 101 that converts wind energy into alternating current and a machine-side rectifier 102 that is adapted to convert the alternating current into direct current. In this embodiment, the number of offshore wind turbine clusters is related to the capacity of a single wind turbine in the booster station, and the total capacity of each offshore wind turbine cluster may be different.
In this embodiment, a plurality of machine-side rectifiers 102 on a single offshore wind turbine group 1 are connected in series through a primary dc collecting cable 103 between the wind turbines 10, and output ends of two machine-side rectifiers 102 at the head and the tail of the single offshore wind turbine group are connected to one box inversion integrated machine 3 through a primary dc collecting line 2.
The box inversion all-in-one machine 3 is composed of a centralized inverter 31 connected with the common direct current bus 2 and a box type transformer 32 connected with the centralized inverter 31. A plurality of fan inverters and transformers are replaced by a small number of box inversion integrated machines, the number of the fan inverters and the transformers can be greatly reduced, power cables between the fan inverters and the box-type transformers are saved, operation and maintenance difficulty is reduced, and meanwhile construction cost of offshore wind power can be further reduced. While a smaller number of devices means less operation and maintenance effort.
The box-type transformers 32 of the offshore wind turbines 1 are connected to the low-voltage side of a main transformer on an offshore booster station 5 through a secondary collection bus 4, are further boosted by the main transformer, are output to one end of a submarine alternating current cable 6 from the high-voltage side of the main transformer, and the other end of the submarine alternating current cable 6 is connected to a shore-based transformer station 7 and is finally connected to a power grid 8 after being transformed by the shore-based transformer station 7.
In this embodiment, the number N of fans connected in series in a single fan group is related to the dc voltage output by the machine-side rectifier 102 and the MPPT voltage operating range of the centralized inverter 31. Now, assume that the range of the DC voltage output by the fan is V dc1 ,V dc2 ]In which V is dc1 For connecting the output voltage, V, of the fans in series at start-up dc2 The output voltage of the fan is connected in series when the fan works normally. The MPPT working voltage range of the centralized inverter 31 is [ V ] mppt1 ,V mppt2 ]Therefore, the number N of the fans is mainly determined by the following formula
The number N of the fans is determined finally after economic comparison and selection by comprehensively considering the manufacturing cost of each device. Generally speaking, when the secondary collecting line is 35kV, the total capacity of the series connection of the plurality of fans should not exceed 25MW, and when the secondary collecting line is 66kV, the total capacity of the series connection of the plurality of fans should not exceed 45MW.
The meanings of the respective reference numerals in fig. 2 and 3 are as follows. Wherein ω is r 、ω rref As fan rotor speed and speed command, ω p 、θ p For phase-locked loop outputting angular velocity and position, theta r 、θ pitch For fan rotor position and pitch angle command values, C dc Is a DC capacitor, V dc 、V dcref The dc capacitor voltage and its command value are,
and
internal potentials, V, of d-and q-axes, respectively, of the rotor side t 、V tref The terminal voltage amplitude and its command value,
and
the internal potentials of the d axis and the q axis of the net side are respectively,
and i
The d-axis current at the rotor side and the command value thereof,
and
respectively the rotor side q-axis currentAnd its instruction value, V t 、V g Are the terminal voltage and the grid voltage vectors,
and
respectively, the grid side d-axis current and the command value thereof,
and
respectively, the q-axis current of the network side and the command value, T emref For torque command value, ψ f Is a fan air gap flux linkage, e αβ And e γαβ Respectively, the projections of the net-side internal potential and the rotor-side internal potential rotation vector in the stationary coordinate system α β.
In this embodiment, fig. 2 is a basic control diagram of the machine-side rectifier 102, which includes rotation speed control, inertia control and current control, and is used to convert ac power generated by the multiple wind power generators 101 into dc power of the same magnitude, and in order to avoid circulating current between the serially connected fans, a basic control strategy of the machine-side rectifier is to ensure that output currents of the machine-side rectifiers connected in series are consistent. After the output power of the fan is predicted, the output circuit of each fan rectifier can be determined according to the output voltage range, and then the output current of each rectifier is guaranteed to be consistent according to the current controller.
In this embodiment, the case inversion all-in-one machine 3 is disposed inside a tower of a certain wind turbine 10, and the wind turbine 10 closer to the offshore booster station is selected as much as possible to install the case inversion all-in-one machine 3, so that the cable cost can be saved. Compared with the prior art, the power cable between the inverter and the box-type transformer can be saved, and the space of the fan can be fully utilized.
In this embodiment, fig. 3 shows basic control of the centralized inverter 31, which includes dc voltage control, terminal voltage control, and current control, and can convert dc power transmitted from the common dc bus 2 into ac power, and the ac power is first boosted by the box transformer 32 and then collected to the low-voltage side of the main transformer of the offshore booster station 5 by the secondary collection bus 4.
Each offshore wind turbine group 1 is subjected to first boosting through the box-type transformer 32 to obtain alternating currents with the same voltage level, and the voltages of the alternating currents are the same, so that the cable type selection and planning of the secondary collection bus 4 are facilitated.
In this embodiment, the main transformer of the offshore booster station 5 boosts the ac power of the same voltage class collected from the secondary collection bus 4 for the second time, and the voltage of the high-voltage ac power after the second boosting is 110KV, but a voltage class of 220KV, 330KV, 500KV or higher may be adopted.
The embodiment also provides a centralized inversion and boosting integrated offshore wind power generation method, which comprises the following steps:
wind energy is converted into alternating current through wind power generators 101 of a plurality of fans 10 on an offshore wind turbine group 1, the alternating current is converted into direct current with the same current grade through machine side rectifiers 102 corresponding to the fans 10, and the direct current is transmitted to an input end of a box inversion all-in-one machine 3 through a primary direct current bus line 2;
the direct current with the same current level is converted into alternating current through a centralized inverter 31 of the box inversion all-in-one machine 3, the alternating current with the same voltage level is obtained through first boosting output of a box type transformer 32, and the alternating current is connected to the input end of a single offshore boosting station 5 in parallel through a secondary alternating current collection line 4;
the alternating current with the same voltage grade after primary boosting is subjected to secondary boosting through the offshore boosting station 5, and the high-voltage alternating current output after secondary boosting is transmitted to the input end of the onshore transformer substation 7 through the submarine alternating current cable 6;
the high-voltage alternating current subjected to secondary boosting is transmitted to a power grid 8 through an output end of the onshore substation 7.
In this embodiment, as shown in fig. 1, the offshore wind turbine system includes 10 offshore wind turbine groups 1, a single offshore wind turbine group 1 includes 4 wind turbines 10 connected in series, and each wind turbine 10 has a capacity of 5MW. 4 fans 10 on the single offshore fan group 1 are connected in series through a primary direct current collecting cable 103 and then connected into a primary direct current collecting line 2, and the primary direct current collecting line 2 is connected to the input end of a box inversion integrated machine 3. By adopting 35kV current collection lines for collection, and connecting one box inversion all-in-one machine after every 4 fans are connected in series, 30 sets of inverters and box transformers can be reduced, corresponding cables and foundation cost can be saved, about 1200 ten thousand can be saved, and meanwhile, the loss of a collection cable can be reduced by about 0.2%. Meanwhile, the number of the fan inverters and the number of the transformers can be greatly reduced, power cables between the fan inverters and the box-type transformers are saved, and the construction cost of offshore wind power is further reduced; meanwhile, the number of equipment is greatly reduced, and the later operation and maintenance difficulty and cost of the offshore wind farm can be reduced.
It will be understood by those skilled in the art that the foregoing is only an exemplary embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, since various modifications, substitutions and improvements within the spirit and scope of the invention are possible and within the scope of the appended claims.
Claims (8)
1. The utility model provides a concentrate contravariant integration offshore wind power generation system that steps up which characterized in that: the system comprises a plurality of offshore wind turbine groups (1), wherein a single offshore wind turbine group (1) comprises a plurality of wind turbines (10) which are connected in series;
a plurality of fans (10) on the single offshore fan group (1) are connected in series to the input end of a box inversion all-in-one machine (3) through a primary direct current bus line (2);
the output ends of a plurality of box inversion integrated machines (3) corresponding to a plurality of offshore wind turbine groups (1) are connected in parallel to the input end of a single offshore booster station (5) through a secondary alternating current collecting line (4);
the output end of the single offshore booster station (5) is connected to the input end of an onshore transformer substation (7) through a submarine alternating current cable (6);
and the output end of the onshore transformer substation (7) is connected with a power grid (8).
2. The integrated offshore wind power generation system with centralized inversion and boosting functions as claimed in claim 1, wherein: the single wind turbine (10) comprises a wind driven generator (101) and a machine side rectifier (102) matched with the wind driven generator.
3. The integrated offshore wind power generation system with centralized inversion and boosting functions as claimed in claim 2, wherein: and a plurality of machine side rectifiers (102) of the single offshore wind turbine group (1) are connected in series through cables among the wind turbines (10).
4. The integrated offshore wind power generation system with centralized inversion and boosting functions as claimed in claim 3, wherein: the control strategy of each fan side rectifier (102) is to keep outputting the same current.
5. The integrated offshore wind power generation system with centralized inversion and boosting functions as claimed in claim 1, wherein: the box inversion all-in-one machine (3) comprises a centralized inverter (31) positioned at the input end of the box inversion all-in-one machine and a box type transformer (32) positioned at the output end of the box inversion all-in-one machine.
6. The integrated offshore wind power generation system with centralized inversion and boosting functions as claimed in claim 5, wherein: the voltage levels of the alternating currents output by the box-type transformers (32) in the offshore wind turbines (1) are the same.
7. The integrated offshore wind power generation system with centralized inversion and boosting functions as claimed in claim 1, wherein: and the single box inversion integrated machine (3) is arranged inside a tower of a single fan (10).
8. A centralized inversion and boosting integrated offshore wind power generation method is characterized by comprising the following steps:
wind energy is converted into alternating current through wind power generators (101) of a plurality of fans (10) on an offshore wind turbine group (1), the alternating current is converted into direct current with the same current grade through machine side rectifiers (102) corresponding to the fans (10), and the direct current is transmitted to the input end of a box inversion all-in-one machine (3) through a primary direct current bus line (2);
the direct current with the same current level is converted into alternating current through a centralized inverter (31) of the box inversion all-in-one machine (3), the alternating current with the same voltage level is obtained through first boosting output of a box type transformer (32), and the alternating current is connected to the input end of a single offshore boosting station (5) in parallel through a secondary alternating current collecting line (4);
the alternating current with the same voltage class after the first boosting is subjected to second boosting through the offshore boosting station (5), and the high-voltage alternating current output after the second boosting is transmitted to the input end of the onshore transformer substation (7) through the submarine alternating current cable (6);
and the high-voltage alternating current subjected to secondary boosting is transmitted to a power grid (8) through an output end of the onshore transformer substation (7).
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211610789.3A CN115833243A (en) | 2022-12-12 | 2022-12-12 | Centralized inversion and boosting integrated offshore wind power generation system and method |
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| CN202211610789.3A CN115833243A (en) | 2022-12-12 | 2022-12-12 | Centralized inversion and boosting integrated offshore wind power generation system and method |
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