Maritime station major loop wiring design method and device

Abstract

The invention provides an offshore station main loop wiring design method and device, and the method comprises the steps: determining the type of an uncontrolled rectifying valve of a system based on the boundary condition of an offshore wind power diode rectification sending-out system; based on the types of the uncontrolled rectifying valves of the system, obtaining components of the main loop of the offshore station corresponding to the types of the uncontrolled rectifying valves; and determining the wiring mode of each part of the main loop of the offshore station according to the types of the uncontrolled rectifying valves of the system and the components of the main loop of the offshore station corresponding to the types of the uncontrolled rectifying valves. The problem that limitation exists in the long-distance alternating-current submarine cable power transmission process due to the fact that an offshore current conversion platform in the prior art is affected by the size and weight of the platform is solved. The offshore wind power diode rectification sending-out system only needs to be designed according to the minimum reactive capacity, the design and construction cost can be reduced to the maximum extent, the size and weight of the offshore converter station can be reduced, meanwhile, the complex operation working conditions and the offshore environment can be adaptively adjusted, and the applicability of the offshore wind power diode rectification sending-out system is 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 transformation has promoted the development of offshore wind power industry. Offshore wind power technology is becoming more and more mature. There are no technical constraints on the development of large-scale intertidal and offshore wind farms. However, it will be affected by the tight use of the sea and will have an impact on the ecological environment, fishing grounds and shipping routes. This will restrict the construction and development of offshore wind farms to a certain extent.

[0003] At present, all domestic offshore wind power adopts 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, and its disadvantages are 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 for long-distance AC submarine cable transmission, it requires the establishment of offshore converter stations and platforms. Its advantage is long transmission distance, and its disadvantages are large size and weight of offshore converter platforms, 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, so as to 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-mentioned purpose, 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, wherein the offshore wind power diode rectifier transmission system comprises: an offshore station, an HVDC transmission channel and an onshore station; the offshore station comprises: an offshore wind farm, a segmented bus and an uncontrolled rectifier station; the offshore station is connected to the onshore station through the HVDC transmission channel; the offshore wind farm is connected to the uncontrolled rectifier station through the segmented bus;

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

[0007] Based on the boundary conditions of the offshore wind power diode rectifier transmission system, determine 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 uncontrolled rectifier valve types of the system and the main circuit components of the offshore station corresponding to each uncontrolled rectifier valve type, the wiring mode of each part of the main circuit of the offshore station is determined.

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

[0011] 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;

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

[0013] Further, based on the uncontrolled rectifier valve type of the system, the main circuit component of the offshore station corresponding to each uncontrolled rectifier valve type is obtained, including:

[0014] When the uncontrolled rectifier valve type of the system is a first uncontrolled rectifier valve, the main circuit components of the offshore station are obtained, including: a first GIS room, 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] Further, according to the uncontrolled rectifier valve type of the system and the components of the main circuit of the offshore station corresponding to each uncontrolled rectifier valve type, the wiring mode of each part of the main circuit of the offshore station is determined, including:

[0017] When the type of the uncontrolled rectifier valve of the system is the 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 inside the first uncontrolled rectifier station;

[0018] When the uncontrolled rectifier valve type of the system is a second uncontrolled rectifier valve, 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 inside the second uncontrolled rectifier station are determined.

[0019] Further, 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 bus, a first branch bus is led out through the GIS room and connected to an 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 a first uncontrolled rectifier valve, the first uncontrolled rectifier valve is connected to a first smoothing reactor, and the first smoothing reactor is connected to an 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 which differ from each other by a preset first angle, and the plurality of groups of first uncontrolled rectifier bridges which differ from each other by a 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 an AC busbar on an AC side.

[0023] Further, 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 in the second uncontrolled rectifier station includes:

[0024] The second GIS room is connected to the generator set through a second AC bus, and the first branch bus 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, and 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 which differ from each other by a preset second angle, and the plurality of groups of second uncontrolled rectifier bridges which differ from each other by a 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] The 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 elements corresponding to each uncontrolled rectifier valve type.

[0034] Beneficial effects:

[0035] (1) Through 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 each type of uncontrolled rectifier valve. Pure diodes are used for rectification on the offshore side, and MMC flexible DC valves are used for inversion on the land. That is, a hybrid flexible DC transmission technology based on high-power diodes is applied. Diode rectification is used at the sending end, and MMC flexible DC valves are used at the receiving end. The diode has no trigger circuit and is equivalent to a passive component. It can be installed in a closed structure and is very suitable for complex offshore environments. The reliability is also higher than that of the MMC valve, and it can basically be maintenance-free all year round. The size and weight of the diode valve are more advantageous than those of the MMC valve, and are basically not in the same order of magnitude. It 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 adapt to complex operating conditions and offshore environments, so as to improve the applicability of the offshore wind power diode rectifier transmission system. 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 by a certain 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 an embodiment of the present invention;

[0040] Figure 3 A topological diagram of the AC side feeder collection 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 a non-segmented connection of double busbars on the offshore side of an offshore wind power diode rectification transmission system provided by a certain 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 a certain 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 transmission system provided by a certain embodiment of the present invention;

[0044] Figure 7 An enlarged view of the HVDC and onshore channel of an offshore wind power diode rectification 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 of an offshore converter station of an offshore wind power diode rectification and transmission system provided by a certain embodiment of the present invention;

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

[0047] Fig.10 A schematic diagram of the phase shifting mechanism of an auto-phase-shifting transformer of an offshore wind power diode rectification transmission system provided by a certain embodiment of the present invention;

[0048] Fig.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;

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

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

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

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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 the steps of a method for designing the main circuit wiring of an offshore station provided by 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 Figure 2 An offshore wind power diode rectification and transmission system is shown. Figure 2A schematic diagram of the module structure of an offshore wind power diode rectification and transmission system provided for a certain embodiment of the present invention; the offshore wind power diode rectification and transmission system comprises: an offshore station 201, an HVDC transmission channel 205 and an onshore station 206; the offshore station 201 comprises: an offshore wind farm 202, a segmented bus 203 and an uncontrolled rectification 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 rectification station 204 via the segmented bus 203;

[0056] The steps of a method for designing the main circuit wiring of an offshore station 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 uncontrolled rectifier valve of the system;

[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] A specific possible implementation method is that the offshore wind power diode rectifier transmission system adopts pure diodes for rectification on the offshore side, and MMC flexible DC valves for inversion on the land, and the DC system adopts symmetrical single-pole wiring. Taking the 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 voltage level 66kV Offshore AC side wiring method 36 Feedback Line Onshore AC 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 km

[0062] Pure diodes are used for rectification on the offshore side, and 6-pulse, 12-pulse and 24-pulse can be considered. However, due to the high harmonic content of the six-pulse uncontrolled rectifier DC 6k and AC 6k±1, in order to meet the harmonic requirements of the offshore wind farm, more passive filters need to be additionally equipped, and the economic benefit is poor. Therefore, the diode rectifier selected for the offshore wind power diode rectification and transmission system of the present invention is a twelve-pulse uncontrolled rectifier valve or a twenty-four-pulse uncontrolled rectifier valve, and the twelve-pulse uncontrolled rectifier valve is preferably used.

[0063] Step 102, based on the types of uncontrolled rectifying valves of the system, obtaining the main circuit components of the offshore station corresponding to each type of uncontrolled rectifying 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 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; when the uncontrolled rectifier valve type of the system is a second uncontrolled rectifier valve, the components of the main circuit of the offshore station 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. A specific possible implementation method is that 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 wiring 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 main circuit of the offshore station 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, determine 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 inside the first uncontrolled rectifier station;

[0067] As an example of this embodiment, the first GIS room is connected to the generator set through the first AC bus, the first branch bus 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 through 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 bus on the AC side. A specific explanation, such as Fig.12 As shown, Fig.12A schematic diagram of electrical wiring of a twelve-pulse uncontrolled rectifier station of an offshore wind power diode rectifier transmission system provided for a certain embodiment of the present invention; when the uncontrolled rectifier valve is a twelve-pulse uncontrolled rectifier valve, the AC bus connected to the generator set is connected to the GIS room, the branch bus drawn from the GIS room is connected to the AC filter and then connected to the grid side of the converter transformer, the valve side of the converter transformer is connected to the twelve-pulse uncontrolled rectifier valve, the twelve-pulse uncontrolled rectifier valve is connected to the smoothing reactor, and the smoothing reactor is connected to the DC line through a DC cable. The first converter transformer is designed as a three-winding transformer with four groups of 8 windings on the wind farm side and 4 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 mutual difference of 30 degrees to achieve the compensation of harmonics. Therefore, the number of uncontrolled rectifier bridges must be an integer multiple of 2. The number of converter transformer windings needs to match the diode valve and also needs to match the incoming line current of GIS. Therefore, the twelve-pulse uncontrolled rectifier can use four groups of diode rectifier bridges in series on the DC side and four groups of three-winding transformers in parallel on the AC bus on the AC side. In this embodiment, the three-winding transformer (rectifier transformer winding) adopts two types of yn / yn / Y and yn / yn / Δ. The grounding method is that the AC side winding is grounded with a small resistance, and the phase shift angle is 30 degrees. At the same time, in order to ensure the GIS requirements for the incoming line current, the number of phase-shifting transformer wind farm side windings is 8 groups, and the connection form of 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 of an offshore wind power diode rectifier transmission system provided for a certain embodiment of the present invention. At the same time, since the uncontrolled rectifier valve will generate voltage and current harmonics, in order to improve the voltage / current power quality of the offshore wind farm, it is necessary to connect an active or passive filter in parallel to the uncontrolled rectifier valve. Since the reactive power required by the uncontrolled rectifier valve can be automatically compensated by the reactive self-synchronous control of the wind turbine, 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 with small disturbances. Therefore, the embodiment of the present invention uses a passive double-tuned filter, which is configured on the commutation transformer side to reduce the 11th, 13th, 23rd, and 25th voltage and current harmonics generated by the twelve-pulse uncontrolled rectification to avoid excessive harmonic current in the system. The AC filter adopts the form of double tuning, and is designed with 11 / 13th tuning filter and 23 / 25th tuning filter respectively. According to the principle of minimum capacity, it is first designed as a single passive tuning filter, and then the parameters of the two sets of single tuning filters are fitted into a set of double tuning 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 inductor 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 the effectiveness of the tuned filter within 1% of the wind farm frequency deviation. 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 It is the relative frequency deviation 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 of an offshore wind power diode rectifier transmission system provided for a certain embodiment of the present invention; at the same time, to ensure reliability and prevent any group of AC filters from exiting operation due to a fault, 11 / 13 tuned filters and 23 / 25 tuned filters are set as two groups for mutual backup, with a total of 4 groups 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 wiring method on the AC side of the first uncontrolled rectifier station includes the feeder collection method and the AC bus wiring method on the converter transformer network side. For the feeder collection method on the AC side of the converter station (the main circuit of the offshore station 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 rectification transmission system described in Table 1 as an example, since the offshore wind farm transmission power is 2GW, there are 36 feeders, including two types of unit capacity of 8MW and 11MW, therefore, the feeders are classified into two transmission power types of 8MW*7 and 11MW*5, of which there are 16 55MW feeders and 20 56MW feeders. Considering the constraint of the maximum current of the wind farm busbar incoming line, the offshore wind farm is equipped with 8 66kV collection transformer windings. Considering the reactive power consumption in the process of diode uncontrolled rectification, 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 side feeder collection of an offshore converter station of an offshore wind power diode rectifier transmission system provided by a certain embodiment of the present invention; for the AC busbar wiring mode, a double busbar non-segmented structure is selected to ensure that the voltage phases of different buses are the same, and to ensure that the uncontrolled rectifier valve can provide an accurate phase shift angle through the rectifier transformer winding to achieve staggered phase cancellation of harmonics, thereby avoiding affecting the harmonic power quality of the wind farm network, and at the same time effectively preventing power outages caused by busbar failures or maintenance. When one busbar fails, it can operate normally through the other busbar, see 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 main circuit of the offshore station 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. 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 of an offshore converter station of an offshore wind power diode rectification and transmission system provided by a certain embodiment of the present invention; Figure 8 The diode area protection measurement points of the China Offshore Converter Station are shown in Table 2:

[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 of which is drawn from the diesel generator, and the other two can be drawn from the fourth winding of the rectifier transformer or the 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 from the 66kV bus.

[0079] When the uncontrolled rectifier valve type of the system is a second uncontrolled rectifier valve, 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 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 through the second AC bus, the first branch bus 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, the second uncontrolled rectifier valve is connected to the second smoothing reactor, and the second smoothing reactor is connected to the external DC line through a DC cable. 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 bus on the AC side. When the uncontrolled rectifier valve is a 24-pulse uncontrolled rectifier valve, the AC bus connected to the generator set is connected to the GIS room, the branch bus led out from the GIS room is connected to the grid side of the converter transformer, the valve side of the converter transformer is connected to the phase-shifting transformer and the 24-pulse uncontrolled rectifier valve in sequence, the 24-pulse uncontrolled rectifier valve is connected to the smoothing reactor, and the smoothing reactor is connected to the DC line through 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) are the same as when the uncontrolled rectifier valve is a twelve-pulse uncontrolled rectifier valve, and will not be elaborated 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 Fig.13, Fig.13 A schematic diagram of the electrical connection of a 24-pulse uncontrolled rectifier station of an offshore wind power diode rectifier transmission system provided for a certain embodiment of the present invention; the converter transformer is designed as a three-winding transformer with four groups of 8 windings on the wind farm side and 4 windings on the rectifier side, and each group of three-winding transformers 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 mutual difference of 15 degrees, so the number of uncontrolled rectifier units should be an integer multiple of 4, and the number of converter transformer windings needs to match the diode valve, and also needs to match 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 on the AC side, it is connected in parallel with the four groups of three-winding transformers connected to the phase-shifting transformer on the valve side on the AC bus. 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 commutator transformer valve side, such as Fig.11 As shown, Fig.11 A wiring diagram of a twenty-four-pulse phase-shifting rectifier transformer with auto-coupling phase-shifting transformer for an offshore wind power diode rectifier transmission system provided in 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 realized by specially designing 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 volume 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 topological structure of the auto-coupling phase-shifting transformer is as follows: Fig. 9 As shown, Fig. 9 A schematic diagram of the structure of an auto-phase-shifting transformer for an offshore wind power diode rectification and transmission system provided by a certain embodiment of the present invention; Fig. 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: Fig.10 As shown in the vector diagram, Fig.10 A schematic diagram of the phase shifting mechanism of an auto-phase-shifting transformer of an offshore wind power diode rectification transmission system provided by a certain embodiment of the present invention; Fig.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 the embodiment of the present invention, the offshore risk first passes through 4 groups of rectifier transformers (4 groups of three-winding transformers), the rectifier transformer transformer groups are all Y / Y / Δ, and then passes through the autotransformer winding on the rectifier transformer valve side to achieve phase shifting to ensure that the four groups of uncontrolled rectifier bridges are 15 degrees apart. Preferably, in order to reduce the volume of the seawater converter platform, the rectifier transformer uses a three-phase transformer.

[0085] As another example of this embodiment, the grid side and valve test of the first converter transformer are both equipped with arresters, the positive and negative high-voltage side diodes of the first uncontrolled rectifier valve are equipped with arresters, and one side of the first smoothing reactor is equipped with arresters; the grid side and valve test of the second converter transformer are both equipped with arresters, the positive and negative high-voltage side diodes of the second uncontrolled rectifier valve are equipped with arresters, and one side of the second smoothing reactor is equipped with arresters. Specifically, the main protection device for the equipment in the converter station is a metal zinc oxide arrester. The principle of its configuration is: the overvoltage generated on the AC side is limited by the arrester on the AC side, the overvoltage generated on the DC side is limited by the arrester on the DC side, and the key protection equipment is directly protected by the arrester close to it. Generally, the protection of the valve side winding of the converter transformer is realized by connecting several types of arresters in series to protect other equipment. The valve side winding of the converter transformer with the highest potential can be directly protected by the arrester close 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 rectification 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 converter transformers and AC busbars;

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

[0089] "D" type arresters are used to protect smoothing reactors and DC line equipment;

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

[0091] “DR” type arrester, used to protect smoothing reactor;

[0092] "VD" type arrester is used to protect the diode of the uncontrolled rectifier valve. The positive and negative high voltage side diode valve is equipped with 2 column VD1 arrester.

[0093] A method for designing the main circuit wiring of an offshore station proposed in an embodiment of the present invention configures the uncontrolled rectifier valve types of the system into two types through the boundary conditions of the offshore wind power diode rectifier transmission system, comprehensively considers the system parameters on the offshore side and the onshore side, constructs an optimal uncontrolled rectifier valve application scheme, improves the adaptability of the offshore wind power diode rectifier transmission system to the complex offshore environment, and thus improves the applicability of the offshore wind power diode rectifier transmission system; obtains the corresponding main circuit components of the offshore station through each uncontrolled rectifier valve type, adopts pure diodes for rectification on the offshore side, and adopts MMC flexible direct current valves for inversion on the onshore means, that is, a hybrid flexible direct current transmission technology based on high-power diodes is applied, and diode rectification is adopted at the sending end, and MMC flexible direct current valves are adopted at the receiving end. The diode has no trigger circuit, which is equivalent to a passive component, and can be installed in a closed structure, which is very suitable for complex offshore environments, and has higher reliability than the MMC valve, and can basically achieve maintenance-free all year round, and the size and weight of the diode valve are more advantageous than the MMC valve, which are basically not in the same order of magnitude, and can greatly reduce the size and weight of the offshore converter station, thereby improving the applicability of the offshore wind power diode rectifier transmission system.

[0094] Example 2

[0095] See also Fig.14 , Fig.14 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. Fig.14 As shown, an embodiment of the present invention provides a main circuit wiring design device for an offshore station, comprising:

[0096] An uncontrolled rectifier valve type determination module 1401, an offshore station main circuit component composition determination module 1402, and a 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 elements corresponding to each uncontrolled rectifier valve type.

[0100] An offshore station main circuit wiring design device proposed in an embodiment of the present invention designs wiring methods of various parts of the offshore station main circuit according to different uncontrolled rectifier valve types and 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, which 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 adaptively adjust to complex operating conditions and offshore environments, so as to improve 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 description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means 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 one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0103] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and 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 rectification and transmission system, the offshore wind power diode rectification and transmission system comprises: an offshore station, an HVDC transmission channel and an onshore station; the offshore station comprises: an offshore wind farm, a segmented bus and an uncontrolled rectification station; the offshore station is connected to the onshore station through the HVDC transmission channel; the offshore wind farm is connected to the uncontrolled rectification station through the segmented bus; The offshore station main circuit wiring design method comprises: Based on the boundary conditions of the offshore wind power diode rectifier transmission system, determine the type of uncontrolled rectifier valve of the system; 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; According to the uncontrolled rectifier valve types of the system and the main circuit components of the offshore station corresponding to each uncontrolled rectifier valve type, the wiring mode of each part of the main circuit of the offshore station is determined.

2. A method for designing the main circuit connection of an offshore station as claimed in claim 1, characterized in that: Based on the boundary conditions of the offshore wind power diode rectifier transmission system, the type of uncontrolled rectifier valve of the system is determined, including: 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 different numbers of uncontrolled rectifier valves, the type of uncontrolled rectifier valves of the system is obtained.

3. A method for designing main circuit wiring of an offshore station as claimed in claim 1, characterized in that: Based on the uncontrolled rectifier valve types of the system, the main circuit components of the offshore station corresponding to each uncontrolled rectifier valve type are obtained, including: When the uncontrolled rectifier valve type of the system is a first uncontrolled rectifier valve, the main circuit components of the offshore station are obtained, including: a first GIS room, 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 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.

4. A method for designing main circuit wiring of an offshore station as claimed in claim 3, characterized in that: According to the uncontrolled rectifier valve type of the system and the components of the main circuit of the offshore station corresponding to each uncontrolled rectifier valve type, the wiring mode of each part of the main circuit of the offshore station is determined, including: When the type of the uncontrolled rectifier valve of the system is the 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 inside the first uncontrolled rectifier station; When the uncontrolled rectifier valve type of the system is a second uncontrolled rectifier valve, 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 inside the second uncontrolled rectifier station are determined.

5. A method for designing the main circuit connection of an offshore station as claimed in claim 4, 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 bus, a first branch bus is led out through the GIS room and connected to an 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 a first uncontrolled rectifier valve, the first uncontrolled rectifier valve is connected to a first smoothing reactor, and the first smoothing reactor is connected to an external DC line through a DC cable.

6. A method for designing main circuit wiring of an offshore station as claimed in claim 5, characterized in that: The first uncontrolled rectifier valve is composed of a plurality of groups of first uncontrolled rectifier bridges which are mutually different by a preset first angle, and the plurality of groups of first uncontrolled rectifier bridges which are mutually different by a 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 an AC busbar on an AC side.

7. A method for designing main circuit wiring of an offshore station as claimed in claim 4, 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 a second uncontrolled rectifier station, a wiring mode of a DC side of a 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 bus, and the first branch bus 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, and the second smoothing reactor is connected to the external DC line through a DC cable.

8. A method for designing main circuit wiring of an offshore station as claimed in claim 7, characterized in that: The second uncontrolled rectifier valve is composed of a plurality of groups of second uncontrolled rectifier bridges which are mutually different by a preset second angle, and the plurality of groups of second uncontrolled rectifier bridges which are mutually different by a 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.

9. A method for designing main circuit wiring of an offshore station according to any one of claims 1 to 8, 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.

10. A main circuit wiring design device for an offshore station, characterized in that: The method for designing the main circuit connection of an offshore station according to any one of claims 1 to 9 comprises: 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 the uncontrolled rectifier valve of the system based on the boundary conditions of the offshore wind power diode rectifier transmission system; 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; 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 elements corresponding to each uncontrolled rectifier valve type.

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