A method and device for designing main circuit wiring of an offshore station

Abstract

The present invention proposes a method and device for designing the wiring of an offshore station main circuit. Based on the boundary conditions of the offshore wind power diode rectifier transmission system, the system's uncontrolled rectifier valve type is determined; based on the system's uncontrolled rectifier valve type, the offshore station main circuit components corresponding to each uncontrolled rectifier valve type are obtained; and according to the system's uncontrolled rectifier valve type and the offshore station main circuit components corresponding to each uncontrolled rectifier valve type, the wiring method of each part of the offshore station main circuit is determined. The present invention solves the problem that the existing offshore converter platform is limited in long-distance AC submarine cable power transmission due to the size and weight of the platform. The present invention only needs to be designed according to the minimum reactive capacity, which can not only maximize the reduction of design and construction costs, but also reduce the size and weight of the offshore converter station. At the same time, it can be adaptively adjusted to complex operating conditions and offshore environments, so that the applicability of the offshore wind power diode rectifier transmission system can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore power generation, and in particular to a method and device for designing main circuit wiring of an offshore station. Background Art

[0002] The pressure brought by energy transition has driven the development of the offshore wind power industry. Offshore wind power technology is becoming increasingly mature, and there are no longer technical constraints on the development of large-scale intertidal and offshore wind farms. However, this will be affected by the shortage of sea use and will have an impact on the ecological environment, fishing grounds and shipping routes. This will impose certain restrictions on the construction and development of offshore wind farms.

[0003] At present, all domestic offshore wind power uses AC transmission technology, and there are two main technical routes for offshore wind power transmission in existing technologies: one is AC transmission technology, which is mainly used in wind farms less than 70 kilometers offshore. Its advantages are good economy and simple system structure. The disadvantage is that when the transmission distance exceeds 70 kilometers, a compensation station needs to be set up to compensate for the reactive power of the submarine cable; the second is flexible direct current transmission technology, which is mainly used in large-scale deep-sea wind farms with an offshore distance greater than 70 kilometers. Although this technology can avoid the problem of reactive power compensation in long-distance AC submarine cable transmission, it requires the establishment of offshore converter stations and platforms. Its advantage is long transmission distance, and its disadvantage is large size and weight of the offshore converter platform, high investment cost and low rate of return; at this stage, the cost of offshore converter stations is mainly affected by the size and weight of the platform, which leads to limitations in the long-distance AC submarine cable transmission process. Summary of the Invention

[0004] In order to solve the above problems, the present invention proposes a method and device for designing the main circuit wiring of an offshore station, which can reduce the constraints of platform size and weight on the offshore converter station and improve the applicability of long-distance AC submarine cable transmission.

[0005] To achieve the above objectives, an embodiment of the present invention provides an offshore station main circuit wiring design method, which is applied to an offshore wind power diode rectifier transmission system. The offshore wind power diode rectifier transmission system includes: an offshore station, an HVDC transmission channel, and an onshore station; the offshore station includes: an offshore wind farm, a segmented bus, and an uncontrolled rectifier station; the offshore station is connected to the onshore station via the HVDC transmission channel; the offshore wind farm is connected to the uncontrolled rectifier station via the segmented bus;

[0006] The offshore station main circuit wiring design method includes:

[0007] Based on the boundary conditions of the offshore wind power diode rectifier transmission system, determining the type of uncontrolled rectifier valve of the system;

[0008] Based on the uncontrolled rectifier valve types of the system, obtaining the main circuit components of the offshore station corresponding to each uncontrolled rectifier valve type;

[0009] According to the types of the uncontrolled rectifier valves of the system and the components of the main circuit of the offshore station corresponding to each type of the uncontrolled rectifier valve, the wiring mode of each part of the main circuit of the offshore station is determined.

[0010] Furthermore, based on the boundary conditions of the offshore wind power diode rectifier transmission system, the type of the uncontrolled rectifier valve of the system is determined, including:

[0011] Based on the system capacity, DC system voltage level, DC system wiring method, offshore AC side voltage level, offshore AC side voltage level, onshore AC side voltage level, onshore AC side wiring method, onshore converter valve structure and transmission cable length of the offshore wind power diode rectifier transmission system, different numbers of uncontrolled rectifier valves are configured according to a preset ratio;

[0012] Based on different numbers of uncontrolled rectifier valves, the type of uncontrolled rectifier valves in the system is obtained.

[0013] Furthermore, based on the type of the uncontrolled rectifier valve of the system, the main circuit components of the offshore station corresponding to each type of the uncontrolled rectifier valve are obtained, including:

[0014] When the uncontrolled rectifier valve type of the system is a first uncontrolled rectifier valve, components of the main circuit of the offshore station are obtained, including: a first GIS chamber, an AC filter, a first converter transformer, a first uncontrolled rectifier valve, and a first smoothing reactor;

[0015] When the uncontrolled rectifier valve type of the system is the second uncontrolled rectifier valve, the main circuit components of the offshore station are obtained, including: a second GIS room, a second converter transformer, a phase-shifting transformer, a second uncontrolled rectifier valve, and a second smoothing reactor.

[0016] Furthermore, according to the type of the uncontrolled rectifier valve of the system and the components of the main circuit of the offshore station corresponding to each type of the uncontrolled rectifier valve, the wiring mode of each part of the main circuit of the offshore station is determined, including:

[0017] When the uncontrolled rectifier valve type of the system is a first uncontrolled rectifier valve, determining a wiring mode of an AC side of the first uncontrolled rectifier station, a wiring mode of a DC side of the first uncontrolled rectifier station, and a wiring mode within the first uncontrolled rectifier station;

[0018] When the uncontrolled rectifier valve type of the system is the second uncontrolled rectifier valve, the connection mode of the AC side of the second uncontrolled rectifier station, the connection mode of the DC side of the second uncontrolled rectifier station and the connection mode inside the second uncontrolled rectifier station are determined.

[0019] Furthermore, when the uncontrolled rectifier valve type of the system is a first uncontrolled rectifier valve, determining the wiring mode of the AC side of the first uncontrolled rectifier station, the wiring mode of the DC side of the first uncontrolled rectifier station, and the wiring mode within the first uncontrolled rectifier station includes:

[0020] The first GIS room is connected to the generator set through a first AC busbar, a first branch busbar is led out through the GIS room and connected to the AC filter, the AC filter is connected to the grid side of the first converter transformer, the valve side of the first converter transformer is connected to the first uncontrolled rectifier valve, the first uncontrolled rectifier valve is connected to the first smoothing reactor, and the first smoothing reactor is connected to the external DC line through a DC cable.

[0021] Furthermore, the first uncontrolled rectifier valve is composed of a plurality of groups of first uncontrolled rectifier bridges that differ from each other by a preset first angle, and the plurality of groups of first uncontrolled rectifier bridges that differ from each other by the preset first angle are connected in series on the DC side;

[0022] The first converter transformer is composed of a plurality of groups of first winding transformers, and the plurality of groups of first winding transformers are connected in parallel to the AC busbar on the AC side.

[0023] Furthermore, when the uncontrolled rectifier valve type of the system is a second uncontrolled rectifier valve, determining the wiring mode of the AC side of the second uncontrolled rectifier station, the wiring mode of the DC side of the second uncontrolled rectifier station, and the wiring mode within the second uncontrolled rectifier station includes:

[0024] The second GIS room is connected to the generator set through a second AC busbar, and the first branch busbar is led out through the GIS room and connected to the grid side of the second converter transformer. The valve side of the second converter transformer is connected to the phase-shifting transformer and the second uncontrolled rectifier valve in sequence, and the second uncontrolled rectifier valve is connected to the second smoothing reactor. The second smoothing reactor is connected to the external DC line through a DC cable.

[0025] Furthermore, the second uncontrolled rectifier valve is composed of a plurality of groups of second uncontrolled rectifier bridges that are mutually different by a preset second angle, and the plurality of groups of second uncontrolled rectifier bridges that are mutually different by the preset second angle are connected in series on the DC side;

[0026] The second converter transformer is composed of a plurality of groups of second winding transformers, and the plurality of groups of second winding transformers are connected in parallel to the AC busbar on the AC side.

[0027] Furthermore, it also includes:

[0028] The grid side and valve side of the first converter transformer are both equipped with lightning arresters, the positive and negative high-voltage side diodes of the first uncontrolled rectifier valve are equipped with lightning arresters, and one side of the first smoothing reactor is equipped with a lightning arrester;

[0029] The grid side and valve side of the second converter transformer are both equipped with lightning arresters, the positive and negative high-voltage side diodes of the second uncontrolled rectifier valve are equipped with lightning arresters, and one side of the second smoothing reactor is equipped with a lightning arrester.

[0030] An embodiment of the present invention further provides an offshore station main circuit wiring design device, comprising: an uncontrolled rectifier valve type determination module, an offshore station main circuit component composition determination module, and a wiring mode determination module;

[0031] The uncontrolled rectifier valve type determination module is used to determine the type of the uncontrolled rectifier valve of the system based on the boundary conditions of the offshore wind power diode rectifier transmission system;

[0032] The offshore station main circuit component composition determination module is used to obtain the offshore station main circuit component corresponding to each uncontrolled rectifier valve type based on the uncontrolled rectifier valve type of the system;

[0033] The offshore station main circuit wiring mode determination module is used to determine the wiring mode of each part of the offshore station main circuit according to the uncontrolled rectifier valve type of the system and the offshore station main circuit component components corresponding to each uncontrolled rectifier valve type.

[0034] Beneficial effects:

[0035] (1) Based on the boundary conditions of the offshore wind power diode rectifier transmission system, the system's uncontrolled rectifier valve types are configured into two categories. Taking into account the system parameters on the offshore and onshore sides, the optimal uncontrolled rectifier valve application scheme is constructed, which improves the adaptability of the offshore wind power diode rectifier transmission system to the complex offshore environment, thereby improving the applicability of the offshore wind power diode rectifier transmission system;

[0036] (2) Obtain the corresponding main circuit components of the offshore station through the types of uncontrolled rectifier valves. Pure diodes are used for rectification on the offshore side, and MMC flexible direct current valves are used for inversion on the land side. That is, a hybrid flexible direct current transmission technology based on high-power diodes is applied. Diode rectification is used at the sending end, and MMC flexible direct current valves are used at the receiving end. The diodes have no trigger circuit and are equivalent to passive components. They can be installed in a closed structure and are very suitable for complex offshore environments. The reliability is also higher than that of the MMC valves, and it can basically be maintenance-free all year round. In addition, the size and weight of the diode valves are more advantageous than those of the MMC valves, and are basically not on the same order of magnitude. This can greatly reduce the size and weight of the offshore converter station, thereby improving the applicability of the offshore wind power diode rectification transmission system.

[0037] (3) According to the different types of uncontrolled rectifier valves and the components of the offshore station main circuit corresponding to each type of uncontrolled rectifier valve, the wiring methods of each part of the offshore station main circuit are designed. By designing different wiring methods under various conditions, it is only necessary to design according to the minimum reactive capacity. This can not only minimize the design and construction costs, but also reduce the size and weight of the offshore converter station. At the same time, it can make adaptive adjustments to complex operating conditions and offshore environments, so that the applicability of the offshore wind power diode rectifier transmission system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic flow chart of the steps of a method for designing the main circuit wiring of an offshore station provided in one embodiment of the present invention;

[0039] Figure 2 A schematic diagram of the module structure of an offshore wind power diode rectification and transmission system provided by one embodiment of the present invention;

[0040] Figure 3 A topological diagram of the AC side feeder aggregation of an offshore converter station of an offshore wind power diode rectifier transmission system provided in one embodiment of the present invention;

[0041] Figure 4 A schematic diagram of the non-segmented connection of double busbars on the offshore side of an offshore wind power diode rectifier transmission system provided by one embodiment of the present invention;

[0042] Figure 5 A schematic diagram of the topological structure of an offshore uncontrolled rectifier station of an offshore wind power diode rectifier transmission system provided by one embodiment of the present invention;

[0043] Figure 6 A schematic diagram of the topological structure of a passive filter of an offshore wind power diode rectification and transmission system provided by one embodiment of the present invention;

[0044] Figure 7 An enlarged view of the HVDC and onshore channel of an offshore wind power diode rectifier transmission system provided in one embodiment of the present invention;

[0045] Figure 8 A schematic diagram of the arrangement of diode area protection measurement points for an offshore converter station of an offshore wind power diode rectifier transmission system provided by one embodiment of the present invention;

[0046] Figure 9 A schematic diagram of the structure of an auto-coupling phase-shifting transformer for an offshore wind power diode rectification and transmission system provided by one embodiment of the present invention;

[0047] Figure 10 A schematic diagram of the phase shift mechanism of an auto-coupling phase-shifting transformer in an offshore wind power diode rectifier transmission system provided by one embodiment of the present invention;

[0048] Figure 11 A wiring diagram of a 24-pulse phase-shifting rectifier transformer with auto-coupling phase-shifting for an offshore wind power diode rectifier transmission system provided by one embodiment of the present invention;

[0049] Figure 12 A schematic diagram of the electrical wiring of a twelve-pulse uncontrolled rectifier station of an offshore wind power diode rectifier transmission system provided by one embodiment of the present invention;

[0050] Figure 13 A schematic diagram of the electrical wiring of a 24-pulse uncontrolled rectifier station of an offshore wind power diode rectifier transmission system provided by one embodiment of the present invention;

[0051] Figure 14 A schematic diagram of the module structure of a main circuit wiring design device for an offshore station provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] In the embodiments of the present invention, "system" refers to the offshore wind power diode rectification and transmission system, which will not be described in detail below.

[0054] Example 1

[0055] See also Figure 1 , Figure 1 A schematic flow chart of a method for designing the main circuit wiring of an offshore station according to an embodiment of the present invention. Figure 1 As shown, the embodiment of the present invention proposes a method for designing the main circuit wiring of an offshore station, including steps 101 to 103. It is worth mentioning that in this embodiment, the method for designing the main circuit wiring of an offshore station proposed by the present invention is applied to the following example: Figure 2 An offshore wind power diode rectifier transmission system is shown. Figure 2A schematic diagram of the module structure of an offshore wind power diode rectifier transmission system provided in one embodiment of the present invention; the offshore wind power diode rectifier transmission system includes: an offshore station 201, an HVDC transmission channel 205, and an onshore station 206; the offshore station 201 includes: an offshore wind farm 202, a segmented bus 203, and an uncontrolled rectifier station 204; the offshore station 201 is connected to the onshore station 206 via the HVDC transmission channel 205; the offshore wind farm 202 is connected to the uncontrolled rectifier station 204 via the segmented bus 203;

[0056] The steps of the offshore station main circuit wiring design method proposed by the present invention are as follows:

[0057] Step 101, based on the boundary conditions of the offshore wind power diode rectifier transmission system, determine the type of the system's uncontrolled rectifier valve;

[0058] As an example of this embodiment, based on the system capacity of the offshore wind power diode rectifier transmission system, the DC system voltage level, the DC system wiring method, the offshore AC side voltage level, the offshore AC side voltage level, the onshore AC side voltage level, the onshore AC side wiring method, the onshore converter valve structure and the length of the transmission submarine cable, different numbers of uncontrolled rectifier valves are configured according to a preset ratio; based on the different numbers of uncontrolled rectifier valves, the type of uncontrolled rectifier valves of the system is obtained.

[0059] In a specific embodiment, the offshore wind power diode rectifier transmission system adopts pure diodes for rectification on the offshore side, MMC flexible DC valves for inversion on the land side, and a symmetrical single-pole connection mode for the DC system. Taking a 2GW / ±500kV offshore wind power diode rectifier transmission system as an example, its boundary conditions are shown in Table 1 below:

[0060] Table 1 Boundary conditions of 2GW / ±500kV offshore wind power diode rectifier transmission system

[0061] System capacity 2GW DC system voltage level ±500kV DC system wiring method Symmetrical monopole Offshore AC side voltage level 66kV Offshore AC side wiring method 36 feedback lines Onshore AC side voltage level 500kV Onshore AC side wiring method 3 / 2 wiring mode, 1 outgoing line Onshore converter valve structure Soft straight valve Length of transmission submarine cable 100 kilometers

[0062] Pure diodes are used for rectification on the offshore side, and 6-pulse, 12-pulse, and 24-pulse systems are possible. However, since the six-pulse uncontrolled rectifier has high DC 6k and AC 6k±1 harmonic content, additional passive filters are required to meet the harmonic requirements of offshore wind farms, resulting in poor economic benefits. Therefore, the offshore wind power diode rectification and transmission system of the present invention uses a 12-pulse uncontrolled rectifier valve or a 24-pulse uncontrolled rectifier valve for diode rectification, with the 12-pulse uncontrolled rectifier valve being preferred.

[0063] Step 102: Based on the types of the uncontrolled rectifier valves in the system, obtain the main circuit components of the offshore station corresponding to each type of the uncontrolled rectifier valve;

[0064] As an example of this embodiment, when the uncontrolled rectifier valve type of the system is a first uncontrolled rectifier valve, the components of the offshore station main circuit are obtained, including: a first GIS chamber, an AC filter, a first converter transformer, a first uncontrolled rectifier valve, and a first smoothing reactor; when the uncontrolled rectifier valve type of the system is a second uncontrolled rectifier valve, the components of the offshore station main circuit are obtained, including: a second GIS chamber, a second converter transformer, a phase-shifting transformer, a second uncontrolled rectifier valve, and a second smoothing reactor. In a specific embodiment, when the uncontrolled rectifier valve is a twelve-pulse uncontrolled rectifier valve, the main circuit of the offshore station includes a GIS room, an AC filter, a converter transformer, a twelve-pulse uncontrolled rectifier valve, and a smoothing reactor (equivalent to the first GIS room, the AC filter, the first converter transformer, the first uncontrolled rectifier valve, and the first smoothing reactor); when the uncontrolled rectifier valve is a twenty-four-pulse uncontrolled rectifier valve, the main circuit of the offshore station includes a GIS room, a converter transformer, a phase-shifting transformer, an uncontrolled rectifier valve, and a smoothing reactor (equivalent to the second GIS room, the second converter transformer, the phase-shifting transformer, the second uncontrolled rectifier valve, and the second smoothing reactor).

[0065] Step 103 : determining the connection mode of each part of the main circuit of the offshore station according to the type of the uncontrolled rectifier valve of the system and the components of the offshore station main circuit corresponding to each type of the uncontrolled rectifier valve.

[0066] As an example of this embodiment, when the uncontrolled rectifier valve type of the system is a first uncontrolled rectifier valve, the wiring mode of the AC side of the first uncontrolled rectifier station, the wiring mode of the DC side of the first uncontrolled rectifier station, and the wiring mode within the first uncontrolled rectifier station are determined;

[0067] As an example of this embodiment, the first GIS room is connected to the generator set via the first AC busbar, the first branch busbar is led out from the GIS room and connected to the AC filter, the AC filter is connected to the grid side of the first converter transformer, the valve side of the first converter transformer is connected to the first uncontrolled rectifier valve, the first uncontrolled rectifier valve is connected to the first smoothing reactor, and the first smoothing reactor is connected to the external DC line via a DC cable. The first converter transformer is composed of several groups of first winding transformers, and the several groups of first winding transformers are connected in parallel to the AC busbar on the AC side. A specific explanation, such as Figure 12 As shown, Figure 12This is a schematic diagram of the electrical wiring for a twelve-pulse uncontrolled rectifier station in an offshore wind power diode rectifier and power transmission system, provided in accordance with one embodiment of the present invention. When the uncontrolled rectifier valve is a twelve-pulse uncontrolled rectifier, the AC bus connecting the generator set is connected to the GIS room. The branch bus extending from the GIS room is connected to the AC filter and then to the grid side of the converter transformer. The valve side of the converter transformer is connected to the twelve-pulse uncontrolled rectifier valve, which is connected to a smoothing reactor. The smoothing reactor is connected to the DC line via a DC cable. The first converter transformer is designed as a three-winding transformer with four groups of eight windings on the wind farm side and four windings on the rectifier side. The twelve-pulse uncontrolled rectifier valve (equivalent to the first uncontrolled rectifier valve) is composed of four groups of six-pulse uncontrolled rectifiers with a 30-degree offset to achieve harmonic cancellation. Therefore, the number of uncontrolled rectifier bridges must be an integer multiple of 2. The number of converter transformer windings must match the diode valve and the incoming current of the GIS. Therefore, the twelve-pulse uncontrolled rectifier can use four groups of diode rectifier bridges connected in series on the DC side and four groups of three-winding transformers connected in parallel to the AC bus on the AC side. In this embodiment, the three-winding transformer (rectifier transformer winding) adopts two grouping methods: yn / yn / Y and yn / yn / Δ. The grounding method is low-resistance grounding of the AC side winding, with a phase shift angle of 30 degrees. At the same time, to meet the GIS's incoming current requirements, the number of phase-shift transformer windings on the wind farm side is 8. The connection method between the converter transformer and the twelve-pulse uncontrolled rectifier valve is as follows: Figure 5 As shown, Figure 5 A schematic diagram of the topological structure of an offshore uncontrolled rectifier station for an offshore wind power diode rectifier transmission system provided in a certain embodiment of the present invention. At the same time, since uncontrolled rectifier valves generate voltage and current harmonics, in order to improve the voltage / current power quality of offshore wind farms, it is necessary to connect active or passive filters in parallel with the uncontrolled rectifier valves. Since the reactive power required by the uncontrolled rectifier valves can be automatically compensated by the reactive self-synchronous control of the wind turbine generator, the AC filter only needs to meet the harmonic capacity requirements. The disadvantage of using active filtering is that it will generate negative resistance in the frequency domain, which is not conducive to the stable operation of the system under small disturbances. Therefore, this embodiment of the present invention uses a passive double-tuned filter. The passive double-tuned filter is configured on the converter transformer side to reduce the 11th, 13th, 23rd, and 25th voltage and current harmonics generated by the twelve-pulse uncontrolled rectification, thereby preventing the system harmonic current from exceeding the standard. The AC filter adopts a dual-tuned form, with 11 / 13th order tuning filters and 23 / 25th order tuning filters designed respectively. According to the principle of minimum capacity, it is first designed as a single passive tuned filter. Then, the parameters of the two sets of single tuned filters are fitted into a set of dual tuned filter parameters by parameter fitting, so that the two have the same frequency response characteristics. The minimum fundamental reactive power of the filter capacitor is:

[0068]

[0069] Among them, L fnis the tuning filter inductance parameter, ω s is the fundamental frequency and n is the harmonic number.

[0070] At the same time, in order to prevent the frequency of the output voltage of the offshore wind farm from shifting, the series resistance of the single-tuned filter needs to be designed to improve the tuning sharpness of the monotonic passive filter. In order to ensure that the wind farm frequency deviation is within 1%, the effectiveness of the tuned filter is guaranteed. The single-tuned filter resistance is:

[0071]

[0072] Among them, R f is the single tuned filter series resistance, Q opt is the optimal tuning sharpness of a single-tuned filter, is the impedance angle of the system, δ m Is the relative frequency offset of the system. The impedance angle of the general system ranges from 80 to 85 degrees, and the optimal tuning sharpness of the system is 30 to 60. The larger the tuning filter resistance, the greater the filter loss, so the tuning sharpness Q opt The value is 60. According to the above formula, the 11th order single-tuned AC filter parameters, the 13th order single-tuned AC filter parameters, the 23rd order single-tuned AC filter parameters and the 25th order single-tuned AC filter parameters can be calculated respectively, and then a group of single-tuned small-capacity filters need to be configured at each group of coils on the grid side of the converter transformer, which are responsible for filtering out the 11th, 13th, 23rd and 25th order harmonics, and the single-tuned filters are aggregated to form 11 / 13th order tuned filters and 23 / 25th order tuned filters (using parameter fitting to fit the 11th and 23rd order single-tuned filter parameters into a group of double-tuned filter parameters, and the 13th and 25th order single-tuned filter parameters into another group of double-tuned filter parameters, and have the same frequency response characteristics). In an embodiment of the present invention, the AC filter is preferably a passive double-tuned filter, and the topology diagram of the passive double-tuned filter is as shown in FIG. Figure 6 As shown, Figure 6 A schematic diagram of the topological structure of a passive filter for an offshore wind power diode rectifier transmission system provided in one embodiment of the present invention. To ensure reliability and prevent any set of AC filters from exiting operation due to a fault, two sets of 11 / 13 tuning filters and 23 / 25 tuning filters are provided as backup for each other, for a total of four sets of AC filters.

[0073] A specific possible implementation method is that when the uncontrolled rectifier valve is a twelve-pulse uncontrolled rectifier valve, first, the connection method on the AC side of the first uncontrolled rectifier station includes the feeder collection method on the converter transformer network side and the AC busbar connection method. For the feeder collection method on the AC side of the converter station (the offshore station main loop under the first uncontrolled rectifier valve), it is necessary to design the feeder output power type and the number of feeders of each type. The feeder output power type is determined according to the unit capacity type and number of the generator set, and the number of feeders of each type is determined according to the total number of feeders in the offshore wind farm. Still taking the 2GW / ±500kV offshore wind power diode rectifier transmission system described in Table 1 as an example, since the offshore wind farm has a transmission power of 2GW and 36 feeders, including two types of unit capacity, 8MW and 11MW, the feeders are classified into two transmission power types, 8MW*7 and 11MW*5. Among them, there are 16 55MW feeders and 20 56MW feeders. Considering the maximum current constraint of the wind farm busbar incoming line, the offshore wind farm is equipped with 8 66kV busbar transformer windings. Considering the reactive power consumption during the uncontrolled diode rectification process, the active power of the wind farm busbar at full load is 2000MW, and the power factor is 0.9. For details, see Figure 3 , Figure 3 A topological diagram of the AC feeder aggregation line of an offshore converter station for an offshore wind power diode rectifier transmission system provided in one embodiment of the present invention. For the AC busbar wiring method, a dual-busbar non-segmented structure is selected to ensure that the voltage phases of different buses are the same, and that the uncontrolled rectifier valves can provide precise phase shift angles through the rectifier transformer windings to achieve staggered phase cancellation of harmonics, thereby avoiding impacts on the harmonic power quality of the wind farm network. This also effectively prevents power outages caused by busbar failures or maintenance. When one busbar fails, normal operation can be achieved through the other busbar. See [Note: The following appears to be unrelated text and should be omitted.] Figure 4 , Figure 4 A schematic diagram of the non-segmented connection of the double busbars on the offshore side of an offshore wind power diode rectifier transmission system provided for a certain embodiment of the present invention; furthermore, the DC side of the converter station (the offshore station main circuit under the first uncontrolled rectifier valve) adopts a symmetrical single-stage connection method, which can maximize land conservation and reduce the weight and size of the offshore platform. In addition, the AC side of the converter valve does not need to bear the DC bias voltage, the equipment requirements are relatively simple, and there is no need to set up a special grounding electrode.

[0074] In order to realize the control and protection of the system, the control and protection strategy should be integrated in the main wiring mode, and the measuring devices should be configured at the corresponding measuring points, such as Figure 8 As shown, Figure 8 A schematic diagram of the arrangement of diode area protection measurement points for an offshore converter station of an offshore wind power diode rectifier transmission system provided by one embodiment of the present invention; Figure 8 The diode area protection measurement points of the China Offshore Converter Station are shown in Table 2 below:

[0075] Table 2 List of diode area protection measurement points in offshore converter stations

[0076]

[0077] Among them, UVYx (x=1, 2, 3, ...), UVDx, UdP, and UdN are voltage measurement elements, and IVCx, IVDx, IdP, IdN, IdL, and IdNL are current detection elements.

[0078] Finally, the offshore converter station (the main circuit of the offshore station under the first uncontrolled rectifier valve) generally has three high-voltage station power supplies. One is drawn from the diesel generator, and the other two can be drawn from the fourth winding of the rectifier transformer or a 66kV dedicated step-down transformer. In order to ensure the balance of the rectifier transformer and facilitate maintenance and inspection, it is recommended to configure a dedicated step-down transformer at the 66kV busbar to draw the power.

[0079] When the uncontrolled rectifier valve type of the system is the second uncontrolled rectifier valve, the connection mode of the AC side of the second uncontrolled rectifier station, the connection mode of the DC side of the second uncontrolled rectifier station and the connection mode inside the second uncontrolled rectifier station are determined.

[0080] As an example of this embodiment, the second GIS room is connected to the generator set via a second AC busbar. A first branch busbar is derived from the GIS room and connected to the grid side of the second converter transformer. The valve side of the second converter transformer is sequentially connected to a phase-shifting transformer and a second uncontrolled rectifier valve. The second uncontrolled rectifier valve is connected to a second smoothing reactor. The second smoothing reactor is connected to an external DC line via a DC cable. The second converter transformer comprises several groups of second-winding transformers, which are connected in parallel to the AC busbar on the AC side. When the uncontrolled rectifier valve is a 24-pulse uncontrolled rectifier valve, the AC busbar connecting the generator set is connected to the GIS room. The branch busbar derived from the GIS room is connected to the grid side of the converter transformer. The valve side of the converter transformer is sequentially connected to a phase-shifting transformer and a 24-pulse uncontrolled rectifier valve. The 24-pulse uncontrolled rectifier valve is connected to a smoothing reactor. The smoothing reactor is connected to the DC line via a DC cable.

[0081] A specific possible implementation method is that when the uncontrolled rectifier valve type of the system is the second uncontrolled rectifier valve (equivalent to when the uncontrolled rectifier valve is a twenty-four-pulse uncontrolled rectifier valve), the AC side wiring method of the converter station (the main circuit of the offshore station under the second uncontrolled rectifier valve), the DC side wiring method of the converter station (the main circuit of the offshore station under the second uncontrolled rectifier valve), the lightning arrester wiring method, the measuring device wiring and the converter station (the main circuit of the offshore station under the second uncontrolled rectifier valve) station power wiring are the same as when the uncontrolled rectifier valve is a twelve-pulse uncontrolled rectifier valve, and will not be described in detail here. The specific difference lies in the wiring between the converter transformer and the twenty-four-pulse uncontrolled rectifier valve in the converter station. The wiring between the converter transformer and the twenty-four-pulse uncontrolled rectifier valve in the converter station is introduced in detail below, see Figure 13, Figure 13 This is a schematic diagram of the electrical wiring for a 24-pulse uncontrolled rectifier station in an offshore wind power diode rectifier transmission system, according to one embodiment of the present invention. The converter transformer is designed as a three-winding transformer with four groups of eight windings on the wind farm side and four windings on the rectifier side. Each three-winding transformer group is connected to a phase-shifting transformer on the valve side. The 24-pulse uncontrolled rectifier valve is composed of four groups of uncontrolled rectifier bridges with a 15-degree offset. Therefore, the number of uncontrolled rectifier units should be an integer multiple of four. The number of converter transformer windings must match the number of diode valves and the incoming current of the GIS. Therefore, the 24-pulse uncontrolled rectifier valve uses four groups of diode uncontrolled rectifier bridges connected in series on the DC side and four groups of three-winding transformers connected to phase-shifting transformers on the valve side, connected in parallel to the AC busbar. Under the 24-pulse uncontrolled rectifier valve, since the rectifier transformer cannot naturally form a 15-degree commutation angle, in order to achieve 24-pulse uncontrolled rectification, the uncontrolled rectifier transformer is required to provide a 15-degree phase shift to offset the 11th and 13th characteristic harmonics on the wind farm side. An additional phase shift transformer (autotransformer winding) needs to be configured on the commutation transformer valve side, such as Figure 11 As shown, Figure 11 A wiring diagram of a twenty-four-pulse phase-shifting rectifier transformer with auto-coupling phase-shifting for an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention; existing small-capacity phase-shifting transformers can be classified into two types: single-core and multi-core. A single-core phase-shifting transformer refers to a transformer that is specially designed for the winding connection of a three-phase transformer, and a multi-core phase-shifting transformer refers to a transformer composed of a series transformer and a parallel transformer (excitation transformer). Considering the size of the phase-shifting transformer, the embodiment of the present invention adopts a single-core auto-coupling transformer to achieve phase shifting through wiring. The topology of the auto-coupling phase-shifting transformer is as follows: Figure 9 As shown, Figure 9 A schematic diagram of the structure of an auto-coupling phase-shifting transformer for an offshore wind power diode rectification and transmission system provided by one embodiment of the present invention; Figure 9 (a) is a positive angle phase shifting transformer, (b) is a negative angle phase shifting transformer, and the phase shifting principle is as follows: Figure 10 As shown in the vector diagram, Figure 10 A schematic diagram of the phase shift mechanism of an auto-coupling phase-shifting transformer in an offshore wind power diode rectifier transmission system provided by one embodiment of the present invention; Figure 10 (a) is the phase shifting mechanism of the positive phase-shifting transformer, and (b) is the phase shifting mechanism of the negative phase-shifting transformer.

[0082] The relationship between the phase-shifting transformer ratio and the phase-shifting angle is given as:

[0083]

[0084] In this embodiment of the present invention, the offshore current first passes through four sets of rectifier transformers (four three-winding transformers), all with a Y / Y / Δ voltage configuration. Phase shifting is then achieved through the autotransformer windings on the rectifier-transformer valve side, ensuring a 15-degree phase shift between the four uncontrolled rectifier bridges. Preferably, to reduce the size of the seawater converter platform, a three-phase rectifier transformer is used.

[0085] As another example of this embodiment, lightning arresters are installed on both the grid-side and valve-side of the first converter transformer, lightning arresters are installed on the positive and negative high-voltage side diodes of the first uncontrolled rectifier valve, and a lightning arrester is installed on one side of the first smoothing reactor. Lightning arresters are installed on both the grid-side and valve-side of the second converter transformer, lightning arresters are installed on the positive and negative high-voltage side diodes of the second uncontrolled rectifier valve, and a lightning arrester is installed on one side of the second smoothing reactor. Specifically, the primary protection device for equipment within the converter station is a metal zinc oxide lightning arrester. The principle of its configuration is as follows: overvoltages generated on the AC side are limited by lightning arresters on the AC side, overvoltages generated on the DC side are limited by lightning arresters on the DC side, and key protected equipment is directly protected by lightning arresters in close proximity. The valve-side winding of the converter transformer is generally protected by several types of lightning arresters connected in series to protect other equipment. The valve-side winding of the converter transformer with the highest potential can be directly protected by lightning arresters installed in close proximity to it.

[0086] Arrangement of lightning arrester Figure 7 As shown, Figure 7 An enlarged view of the HVDC and onshore channel of an offshore wind power diode rectifier transmission system provided in one embodiment of the present invention; Figure 7 The types of lightning arresters and their protective functions are as follows:

[0087] "A" type AC busbar arrester, used to protect the converter transformer and AC busbar;

[0088] "A1" type lightning arrester, used to protect the valve side of the converter transformer;

[0089] "D" type lightning arrester, used to protect smoothing reactors and DC line equipment;

[0090] "BR" type lightning arrester, used to protect bridge arm reactors;

[0091] "DR" type lightning arrester, used to protect smoothing reactor;

[0092] "VD" type arresters are used to protect the diodes of uncontrolled rectifier valves. Two VD1 arresters are configured on the positive and negative high voltage side diode valves.

[0093] An embodiment of the present invention proposes a method for designing the main circuit wiring of an offshore station. By considering the boundary conditions of the offshore wind power diode rectifier transmission system, the system's uncontrolled rectifier valve types are configured into two categories. By comprehensively considering the system parameters on both the offshore and onshore sides, an optimal uncontrolled rectifier valve application scheme is constructed, thereby improving the adaptability of the offshore wind power diode rectifier transmission system to complex offshore environments and thereby enhancing the applicability of the offshore wind power diode rectifier transmission system. Corresponding offshore station main circuit components are obtained based on each uncontrolled rectifier valve type. Pure diodes are used for rectification on the offshore side, while MMC flexible DC valves are used for inversion onshore. This method utilizes a hybrid flexible DC transmission technology based on high-power diodes, with diode rectification used at the sending end and MMC flexible DC valves used at the receiving end. Diodes have no trigger circuits and are equivalent to passive components. They can be installed in a closed structure, making them highly suitable for complex offshore environments. They are also more reliable than MMC valves, essentially achieving year-round maintenance-free operation. Furthermore, diode valves offer advantages over MMC valves in both size and weight, being substantially on a different order of magnitude. This can significantly reduce the size and weight of offshore converter stations, thereby improving the applicability of offshore wind power diode rectifier transmission systems.

[0094] Example 2

[0095] See also Figure 14 , Figure 14 This is a schematic diagram of the module structure of a main circuit wiring design device for an offshore station provided by an embodiment of the present invention. Figure 14 As shown, an embodiment of the present invention provides a device for designing a main circuit connection of an offshore station, comprising:

[0096] Uncontrolled rectifier valve type determination module 1401, offshore station main circuit component composition determination module 1402 and wiring mode determination module 1403;

[0097] The uncontrolled rectifier valve type determination module 1401 is used to determine the type of the uncontrolled rectifier valve of the system based on the boundary conditions of the offshore wind power diode rectifier transmission system;

[0098] The offshore station main circuit component composition determination module 1402 is used to obtain the offshore station main circuit component corresponding to each uncontrolled rectifier valve type based on the uncontrolled rectifier valve type of the system;

[0099] The offshore station main circuit wiring mode determination module 1403 is used to determine the wiring mode of each part of the offshore station main circuit according to the uncontrolled rectifier valve type of the system and the offshore station main circuit component components corresponding to each uncontrolled rectifier valve type.

[0100] An embodiment of the present invention proposes an offshore station main circuit wiring design device, which designs the wiring methods of various parts of the offshore station main circuit according to different uncontrolled rectifier valve types and the offshore station main circuit components corresponding to each uncontrolled rectifier valve type. By designing different wiring methods under various conditions, it is only necessary to design according to the minimum reactive capacity. This can not only maximize the reduction of design and construction costs, but also reduce the size and weight of the offshore converter station. At the same time, it can adapt to complex operating conditions and offshore environments, thereby improving the applicability of the offshore wind power diode rectifier transmission system.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0102] In the description of this specification, the reference terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials, or characteristics described may be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and integrate different embodiments or examples described in this specification, as well as features of different embodiments or examples, unless they are mutually inconsistent.

[0103] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

Claims

1. A method for designing the main circuit connection of an offshore station, characterized in that: Applied to an offshore wind power diode rectifier transmission system, the offshore wind power diode rectifier transmission system includes: an offshore station, an HVDC transmission channel and an onshore station; the offshore station includes: an offshore wind farm, a segmented bus and an uncontrolled rectifier station; the offshore station is connected to the onshore station via the HVDC transmission channel; the offshore wind farm is connected to the uncontrolled rectifier station via the segmented bus; The offshore station main circuit wiring design method includes: Determining the type of uncontrolled rectifier valves of the system based on boundary conditions of the offshore wind power diode rectifier transmission system, including: configuring different numbers of uncontrolled rectifier valves according to a preset ratio based on the system capacity, DC system voltage level, DC system wiring method, offshore AC side voltage level, offshore AC side voltage level, onshore AC side voltage level, onshore AC side wiring method, onshore converter valve structure, and transmission submarine cable length of the offshore wind power diode rectifier transmission system; and obtaining the type of the uncontrolled rectifier valves of the system based on the different numbers of uncontrolled rectifier valves; Based on the type of the uncontrolled rectifier valve of the system, obtaining the main circuit components of the offshore station corresponding to each type of the uncontrolled rectifier valve, including: when the type of the uncontrolled rectifier valve of the system is a first uncontrolled rectifier valve, obtaining the main circuit components of the offshore station including: a first GIS chamber, an AC filter, a first converter transformer, a first uncontrolled rectifier valve, and a first smoothing reactor; when the type of the uncontrolled rectifier valve of the system is a second uncontrolled rectifier valve, obtaining the main circuit components of the offshore station including: a second GIS chamber, a second converter transformer, a phase-shifting transformer, a second uncontrolled rectifier valve, and a second smoothing reactor; According to the types of the uncontrolled rectifier valves of the system and the components of the main circuit of the offshore station corresponding to each type of the uncontrolled rectifier valve, the wiring mode of each part of the main circuit of the offshore station is determined.

2. A method for designing main circuit wiring of an offshore station according to claim 1, characterized in that: According to the type of the uncontrolled rectifier valve of the system and the components of the main circuit of the offshore station corresponding to each type of uncontrolled rectifier valve, the wiring method of each part of the main circuit of the offshore station is determined, including: When the uncontrolled rectifier valve type of the system is a first uncontrolled rectifier valve, determining a wiring mode of an AC side of the first uncontrolled rectifier station, a wiring mode of a DC side of the first uncontrolled rectifier station, and a wiring mode within the first uncontrolled rectifier station; When the uncontrolled rectifier valve type of the system is the second uncontrolled rectifier valve, the connection mode of the AC side of the second uncontrolled rectifier station, the connection mode of the DC side of the second uncontrolled rectifier station and the connection mode inside the second uncontrolled rectifier station are determined.

3. A method for designing main circuit wiring of an offshore station according to claim 2, characterized in that: When the type of the uncontrolled rectifier valve of the system is a first uncontrolled rectifier valve, determining a wiring mode of an AC side of the first uncontrolled rectifier station, a wiring mode of a DC side of the first uncontrolled rectifier station, and a wiring mode within the first uncontrolled rectifier station includes: The first GIS room is connected to the generator set through a first AC busbar, a first branch busbar is led out through the GIS room and connected to the AC filter, the AC filter is connected to the grid side of the first converter transformer, the valve side of the first converter transformer is connected to the first uncontrolled rectifier valve, the first uncontrolled rectifier valve is connected to the first smoothing reactor, and the first smoothing reactor is connected to the external DC line through a DC cable.

4. A method for designing main circuit wiring of an offshore station according to claim 3, characterized in that: The first uncontrolled rectifier valve is composed of a plurality of groups of first uncontrolled rectifier bridges that differ from each other by a preset first angle, and the plurality of groups of first uncontrolled rectifier bridges that differ from each other by the preset first angle are connected in series on the DC side; The first converter transformer is composed of a plurality of groups of first winding transformers, and the plurality of groups of first winding transformers are connected in parallel to the AC busbar on the AC side.

5. The method for designing the main circuit connection of an offshore station according to claim 2, characterized in that: When the uncontrolled rectifier valve type of the system is a second uncontrolled rectifier valve, determining a wiring mode of an AC side of the second uncontrolled rectifier station, a wiring mode of a DC side of the second uncontrolled rectifier station, and a wiring mode within the second uncontrolled rectifier station includes: The second GIS room is connected to the generator set through a second AC busbar, and the first branch busbar is led out through the GIS room and connected to the grid side of the second converter transformer. The valve side of the second converter transformer is connected to the phase-shifting transformer and the second uncontrolled rectifier valve in sequence, and the second uncontrolled rectifier valve is connected to the second smoothing reactor. The second smoothing reactor is connected to the external DC line through a DC cable.

6. A method for designing main circuit wiring of an offshore station according to claim 5, characterized in that: The second uncontrolled rectifier valve is composed of a plurality of groups of second uncontrolled rectifier bridges that differ from each other by a preset second angle, and the plurality of groups of second uncontrolled rectifier bridges that differ from each other by the preset second angle are connected in series on the DC side; The second converter transformer is composed of a plurality of groups of second winding transformers, and the plurality of groups of second winding transformers are connected in parallel to the AC busbar on the AC side.

7. A method for designing main circuit wiring of an offshore station according to any one of claims 1 to 6, characterized in that: Also includes: The grid side and valve side of the first converter transformer are both equipped with lightning arresters, the positive and negative high-voltage side diodes of the first uncontrolled rectifier valve are equipped with lightning arresters, and one side of the first smoothing reactor is equipped with a lightning arrester; The grid side and valve side of the second converter transformer are both equipped with lightning arresters, the positive and negative high-voltage side diodes of the second uncontrolled rectifier valve are equipped with lightning arresters, and one side of the second smoothing reactor is equipped with a lightning arrester.

8. A main circuit wiring design device for an offshore station, characterized in that: Executing a method for designing main circuit wiring of an offshore station according to any one of claims 1 to 7, comprising: Uncontrolled rectifier valve type determination module, offshore station main circuit component composition determination module and wiring method determination module; The uncontrolled rectifier valve type determination module is used to determine the type of uncontrolled rectifier valve of the system based on the boundary conditions of the offshore wind power diode rectifier transmission system, including: configuring different numbers of uncontrolled rectifier valves according to a preset ratio based on the system capacity, DC system voltage level, DC system wiring mode, offshore AC side voltage level, offshore AC side voltage level, onshore AC side voltage level, onshore AC side wiring mode, onshore converter valve structure and transmission submarine cable length of the offshore wind power diode rectifier transmission system; obtaining the type of the uncontrolled rectifier valve of the system based on the different numbers of uncontrolled rectifier valves; The offshore station main circuit component composition determination module is used to obtain offshore station main circuit components corresponding to each uncontrolled rectifier valve type based on the uncontrolled rectifier valve type of the system, including: when the uncontrolled rectifier valve type of the system is a first uncontrolled rectifier valve, the offshore station main circuit components obtained include: a first GIS chamber, an AC filter, a first converter transformer, a first uncontrolled rectifier valve, and a first smoothing reactor; when the uncontrolled rectifier valve type of the system is a second uncontrolled rectifier valve, the offshore station main circuit components obtained include: a second GIS chamber, a second converter transformer, a phase-shifting transformer, a second uncontrolled rectifier valve, and a second smoothing reactor; The offshore station main circuit wiring mode determination module is used to determine the wiring mode of each part of the offshore station main circuit according to the uncontrolled rectifier valve type of the system and the offshore station main circuit component components corresponding to each uncontrolled rectifier valve type.

Images