Offshore Large Direct Drive Switched Reluctance Wind Turbine Power Converter System

Abstract

The invention provides an offshore large direct-drive switch reluctance wind driven generator power converter and a system of the converter. The converter is composed of a switch reluctance wind turbine, a power converter body, a DC / DC converter body and a system controller. The switch reluctance wind turbine is connected with the power converter body. The power converter body is connected with the DC / DC converter body. Output of the DC / DC converter body is connected with output of a DC / DC converter body of the other switch reluctance wind driven generator power converter system in series or parallel and then outputs electric energy to the shore through a direct-current submarine cable. The system controller is connected with the power converter body and connected with the DC / DC converter body. The switch reluctance wind turbine is connected with the system controller. According to the system, two-phase windings of a four-phase switch reluctance generator can work at the same time, exciting voltage is adjustable, the function of outputting direct-current voltage and adjusting boost can be achieved, the power density and the controllable flexibility are improved, and the power converter is suitable for the field of offshore large wind power plants.

Description

technical field [0001] The invention relates to the field of offshore wind power generation, in particular to a large-scale direct-drive switched reluctance wind power generator power converter system for an offshore wind farm. Background technique [0002] Compared with land wind energy, the advantage of offshore wind energy is that the wind speed is higher and the wind force is more sustainable. In my country, the wind speed in open sea areas is 30%-40% higher than that on land on average, and 15%-20% higher in offshore areas. It is used for power generation It can generate 50%-70% more electric energy. [0003] Although people have been developing wind power for fifty years, they are mainly concentrated on land, and experience in building large-scale offshore wind farms is relatively lacking; the main disadvantage of offshore wind power is the construction of towers and platforms (offshore substations) in seawater and The installation cost of generator sets is quite high,...

AI Technical Summary

Problems solved by technology

[0007] Researches at home and abroad have shown that using high-voltage direct current (High-Voltage Direct Current, referred to as: HVDC) to transmit power is the most convenient and economical for offshore wind power. However, if traditional doubly-fed asynchronous or permanent magnet synchronous The AC transformer connected to each AC generator set is first boosted to medium voltage, and then concentrated in the offshore substation to convert it into DC transmission, and then connected to the AC grid after inverting by the inverter in the onshore substation; its structure is complex, and the electric energy needs to be exchanged many times and DC conversion; while the switched reluctance generator directly generates DC power, which saves at least one rectification link

[0008] As mentioned earlier, since the existence of offshore substations in traditional offshore wind farms increases its cost, can offshore substations be omitted? There have been many studies on this aspect at home and abroad in recent years: 1. Amir Parastar, Jul-Ki Seok. High-Power-Density Power Conversion Systems for HVDC-Connected Offshore Wind Farms[J]. Journal of Power Electronics, 2013, 13(5) : 737-745.2, N.Holtsmark, H.J.Bahirat, M.Molinas, et al.An all-DC offshore wind farm with series-connected turbines: An alternative to the classical parallel AC model.IEEETrans.Ind.Electron, 2013, 60 (6): 2420-2428.3, Thanh Hai Nguyen, Dong-ChoonLee. Chan-Ki Kim. A Series-Connected Topology of a Diode Rectifier and a Voltage-Source Converter for an HVDC Transmission System[J]. IEEE TRANSACTIONSON POWER ELECTRONICS, 2014 , 29(4): 1579-1584. 4. Etienne Veilleux, PeterW.Lehn. Interconnection of Direct-Drive Wind Turbines Using a Series-ConnectedDC Grid[J]. IEEE TRANSACTIONS SUSTAINABLE ENERGY, 2014, 5(1): 139- 147.5, Li Xiang, Han Minxiao. Coordinated control strategy of offshore wind power series multi-terminal VSC-HVDC [J]. Journal of Electrotechnical Society, 2013, 28(5): 42-48, 57. etc., they focus on the DC wind farm topology and its In the research and practice of control, all units in the wind farm are connected in series and parallel to obtain DC high voltage and transmit it to the shore substation. However, most of them are aimed at permanent magnet synchronous generators

[0009] Due to its direct output of pulsating direct current, switched reluctance generators are completely different from other mainstream wind turbines, so their power converters are also different. In terms of research and practice of switched reluctance generator power converters, Most of them are aimed at power converters of small and medium power levels, but they also have certain reference significance. At present, the main circuit of power converters of switched reluctance generators mostly adopts an asymmetrical half-bridge structure, but its structure is relatively complicated, and too many electrical components are used. , Literature: Peng Hanmei, Yi Lingzhi, etc. Simple power converter control under separate excitation mode of switched reluctance generator [J]. Acta Solar Sinica, 2012, 33(8). A simple structure of power converter main The circuit structure has important practical value, however, it can only guarantee the operation of one-phase winding at any instant

[0010] The working process of the switched reluctance generator is divided into two stages: excitation and power generation, and it is carried out in time-sharing. The excitation mode is divided into separate excitation and self-excitation. In view of the fact that increasing the excitation voltage is beneficial to increase the winding current during subsequent freewheeling power generation In order to increase the output power and change the problem that the traditional excitation voltage cannot be adjusted online, some new circuit structures of the excitation part of the power converter that can adjust the excitation input voltage online according to the requirements of the control system have emerged in recent years, such as: 1. Peng Hanmei, Yi Lingzhi et al. New Excitation Mode of Switched Reluctance Generator Based on Buck Converter[J]. Acta Solar Sinica, 2012, 33(3). Research on the hardware structure of the system [J]. Ship Electric Technology, 2012, 32(2). It has greatly promoted the development of the switched reluctance generator power converter system; however, they are generally aimed at small and medium power applications

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