CN113904365B - Offshore wind power grid-connected system and control method based on IGCT and LCC devices - Google Patents

Abstract

The present disclosure provides an offshore wind power grid-connected system based on IGCT and LCC devices and a control method, wherein the system comprises: the offshore wind power station comprises an offshore transmitting end converter station and an onshore receiving end converter station connected with the offshore transmitting end converter station, wherein the offshore transmitting end converter station adopts a first converter based on an IGCT current source and a second converter based on an LCC current source and is used for converting alternating current generated by an offshore wind power station into direct current and conveying the direct current to the onshore receiving end converter station; the land receiving end converter station adopts a third converter based on an IGCT current source type for converting direct current transmitted by the marine transmitting end converter station into alternating current and transmitting the alternating current to a land alternating current power grid. The sending end adopts a half control device and a full control device, the LCC thyristor has large capacity, the power electronic device requirement when the full control device is adopted can be reduced, the weight of an offshore platform is further reduced, the offshore wind power low-price sending out is facilitated, the characteristics of full control of the IGCT can be used as a starting source of the LCC side for assisting LCC passive starting, the offshore wind power stable sending out is realized, and the DC fault can be traversed.

Description

Offshore wind power grid-connected system and control method based on IGCT and LCC devices

technical field

The present disclosure relates to the technical field of offshore wind power generation, in particular to an offshore wind power grid-connected system and control method based on IGCT and LCC devices.

Background technique

The grid-connected transmission of offshore wind power usually adopts high-voltage alternating current transmission (HVAC) or high-voltage direct current transmission (HVDC). The HVAC technology is mature and the structure is simple, but limited by the capacitive effect of submarine cables, it is generally only suitable for the connection of offshore wind farms. With the large-scale development and layout of offshore wind farms gradually moving from near sea to far sea, the application of traditional HVAC technology has gradually encountered bottlenecks, and HVDC technology is generally adopted.

In related technologies, voltage source flexible DC transmission technology based on insulated gate bipolar transistors (InsulatedGate Bipolar Transistor, IGBT) is generally used on the rectifier side and inverter side. Technical problems such as heavy weight and difficulty in construction and installation. In addition, when the offshore wind power transmission capacity is large, the converter station adopts a single converter structure to face the requirements of high voltage level and large current amplitude, which puts more stringent requirements on offshore core equipment such as DC submarine cables and converter valves. Require.

Contents of the invention

This application proposes an offshore wind power grid-connected system and control method based on IGCT and LCC devices, aiming to solve one of the technical problems in related technologies at least to a certain extent.

The embodiment of the first aspect of the present application proposes an offshore wind power grid-connected system based on IGCT devices, including: an offshore sending-end converter station, and an onshore receiving-end converter station connected to the offshore sending-end converter station. The terminal converter station includes the first converter based on the IGCT current source type and the second converter based on the LCC current source type, which are used to convert the alternating current generated by the offshore wind farm into direct current and send it to the onshore receiving terminal converter station. Transmission: The onshore receiving end converter station includes a third converter based on the IGCT current source type, which is used to convert the direct current delivered by the offshore sending end converter station into alternating current and transmit it to the onshore AC power grid.

In some embodiments, the first converter based on the IGCT current source type adopts a constant AC bus voltage control strategy and a constant frequency control strategy, and the second converter based on the LCC current source type adopts a constant DC current control strategy.

In some embodiments, the third converter based on the IGCT current source adopts a constant DC current control strategy and an AC bus voltage control strategy.

In some embodiments, the sum of the transmission power of the first inverter and the second inverter is equal to the reception power of the third inverter.

In some embodiments, the system further includes: a first step-up transformer arranged between the first converter and the offshore wind farm; a second step-up transformer arranged between the second converter and the offshore wind farm; The first step-up transformer and the second step-up transformer are configured to step up the AC power generated by the offshore wind farm.

In some embodiments, the first converter based on the IGCT current source type and the third converter based on the IGCT current source type both adopt an IGCT series topology.

In some embodiments, the first converter and the third converter respectively include three valve arms, and the valve arms are formed by connecting several IGCT series diode structures in series, and the number of IGCTs in the first converter is the same as that in the first converter. The transmission power of the converter is related, and the number of IGCTs in the third converter is related to the receiving power of the third converter.

The embodiment of the second aspect of the present application proposes a control method for offshore wind power grid connection, which is applied to an offshore wind power grid connection system. The upper wind power grid connection system includes an offshore sending end converter station and an onshore receiving end converter station. The sending end converter station includes a first converter based on IGCT current source type and the second converter based on LCC current source type, and the onshore receiving end converter station includes a third converter based on IGCT current source type, The method includes: controlling the first converter of the offshore sending end converter station to adopt a constant AC bus voltage control strategy and a constant frequency control strategy, and controlling the second converter to adopt a constant DC current control strategy to convert the alternating current generated by the offshore wind farm to Converted to DC and transmitted to the onshore receiving end converter station; and the third converter controlling the onshore receiving end converter station adopts a constant DC current control strategy and an AC bus voltage control strategy to convert DC into AC and send it to the onshore AC grid transmission.

In some embodiments, the sum of the transmission power of the first inverter and the second inverter is equal to the reception power of the third inverter.

The embodiment of the third aspect of the application provides a non-transitory computer-readable storage medium storing computer instructions, the computer instructions are used to make the computer execute the offshore wind power grid-connected control method disclosed in the embodiment of the application.

In this embodiment, the offshore sending end converter station adopts the first converter based on the IGCT current source type and the second converter based on the LCC current source type, which can convert the AC power generated by the offshore wind farm into DC power and send it to the land. The upper receiving end converter station is used for transmission, and the onshore receiving end converter station adopts the third converter based on the IGCT current source type to convert the direct current delivered by the offshore sending end converter station into alternating current and transmit it to the onshore AC power grid. The offshore sending end adopts half-controlled devices and fully-controlled devices to cooperate with each other. The large capacity of LCC thyristors can reduce the demand for power electronic devices when using fully-controlled devices, further reduce the weight of offshore platforms, and help realize the parity of offshore wind power transmission, and The feature of IGCT full control can be used as the starting source of the LCC side, assisting the passive starting of the LCC, realizing the smooth transmission of offshore wind power, and being able to ride through DC faults. Furthermore, the technical problems existing in the related technologies such as the high overall cost of the offshore wind power grid-connected system, the large volume and weight of the offshore platform, and the difficulty in construction and installation are solved.

Additional aspects and advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure.

Description of drawings

The above and/or additional aspects and advantages of the present disclosure will become apparent and understandable from the following description of the embodiments in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic topology diagram of an offshore wind power grid-connected system provided according to an embodiment of the present disclosure;

Fig. 2 is a schematic circuit diagram of a control strategy of a first inverter provided according to an embodiment of the present disclosure;

Fig. 3 is a schematic circuit diagram of a control strategy of a second inverter provided according to an embodiment of the present disclosure;

Fig. 4 is a schematic circuit diagram of a control strategy of a third inverter provided according to an embodiment of the present disclosure;

Fig. 5 is a schematic flowchart of a method for controlling offshore wind power grid connection according to another embodiment of the present disclosure.

Detailed ways

Embodiments of the present disclosure are described in detail below, examples of which are illustrated in the drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present disclosure and should not be construed as limiting the present disclosure. On the contrary, the embodiments of the present disclosure include all changes, modifications and equivalents coming within the spirit and scope of the appended claims.

In view of the technical problems of the offshore wind power grid-connected system mentioned in the background technology that the overall cost is relatively high, the volume and weight of the offshore platform is too large, and the construction and installation are difficult, the technical solution of this embodiment provides an offshore wind power grid-connected system. The method will be described below in conjunction with specific embodiments.

Fig. 1 is a schematic diagram of the topology of an offshore wind power grid-connected system based on IGCT and LCC devices according to an embodiment of the present disclosure. As shown in Fig. 1 , the offshore wind power grid-connected system generally includes an offshore sending end converter station ( rectification side) and onshore receiving-end converter station (inverter side), the offshore sending-end converter station is connected to the offshore wind farm, the onshore receiving-end converter station is connected to the onshore AC grid, and the offshore sending-end converter station The DC cable can be used for power transmission between the terminal and the onshore receiving end converter station.

Among them, the offshore sending-end converter station includes the first converter based on the integrated gate-commutated thyristor (Integrated Gate-Commutated Thyristor, IGCT) current source type, and the second converter based on the LCC (line-commutated converter, LCC) current source type. Two converters, wherein the LCC is composed of multiple thyristors connected in series.

Among them, the AC side of the first converter is equipped with LC filter devices Lr1 and Cr1 and connected to the wind farm, the DC side is connected to the smoothing reactor L _dc1 , and the second converter is directly connected to the wind farm. Through the first converter based on the IGCT current source type and the second converter based on the LCC current source type, the AC power generated by the offshore wind farm can be converted into DC power (the DC voltage is U _dc ) and sent to the onshore receiving terminal Converter station delivery.

The receiving-end converter station on land includes a third converter based on the IGCT current source type. The AC side of the third converter is equipped with filtering devices Li and Ci to convert the DC power delivered by the offshore sending-end converter station. It is alternating current and sent to the onshore AC power grid. Wherein, the sum of the transmission powers of the first converter and the second converter is equal to the receiving power of the third converter.

In some embodiments, a first step-up transformer and a second step-up transformer may be arranged between the first converter, the second converter and the offshore wind farm, and the offshore wind farm is connected to the first step-up transformer and the second step-up transformer. The low-voltage side of the second step-up transformer, the AC side of the first converter and the second converter are respectively connected to the high-voltage side of the first step-up transformer and the second step-up transformer, through which the step-up transformer can convert the The alternating current is boosted to improve the transmission efficiency.

In some embodiments, the IGCT devices in the first converter based on the IGCT current source type and the third converter based on the IGCT current source type can be arranged in series, that is to say, the IGCT devices of the embodiments of the present disclosure The current source converter adopts a series topology.

For example, the first converter and the third converter based on the IGCT current source type may respectively include three valve arms, each of which is composed of several IGCT series diode structures connected in series, and the first converter The number of IGCTs in the converter is related to the transmission power of the first converter, and the number of IGCTs in the third converter is related to the receiving power of the third converter, that is to say, the first converter, the third converter The number of IGCT devices in the converter is related to the rated power, so that the power transmission efficiency can be improved.

It can be understood that the above examples are only exemplary topological structures of the current source converter of the IGCT, and other topological structures can also be used in practical applications, which is not limited.

Moreover, in the second converter based on the LCC current source type, a 6-pulse bridge or a 12-pulse bridge structure may be used, which is not limited.

In this embodiment, the offshore sending end converter station adopts the first converter based on the IGCT current source type and the second converter based on the LCC current source type, which can convert the AC power generated by the offshore wind farm into DC power and send it to the land. The upper receiving end converter station is used for transmission, and the onshore receiving end converter station adopts the third converter based on the IGCT current source type to convert the direct current delivered by the offshore sending end converter station into alternating current and transmit it to the onshore AC power grid. The offshore sending end adopts half-controlled devices and fully-controlled devices to cooperate with each other. The large capacity of LCC thyristors can reduce the demand for power electronic devices when using fully-controlled devices, further reduce the weight of offshore platforms, and help realize the parity of offshore wind power transmission, and The feature of IGCT full control can be used as the starting source of the LCC side, assisting the passive starting of the LCC, realizing the smooth transmission of offshore wind power, and being able to ride through DC faults. Furthermore, the technical problems existing in the related technologies such as the high overall cost of the offshore wind power grid-connected system, the large volume and weight of the offshore platform, and the difficulty in construction and installation are solved.

Among them, the offshore converter station adopts the parallel structure of IGCT and LCC. The IGCT can be passively started. When the offshore AC bus voltage at the sending end is established, it will drive the LCC to start. The capacity is large, and the total number of devices required is far less than that of IGBTs. It realizes the lightweight and affordable design of offshore wind power transmission. The onshore receiving end adopts IGCTs, and there is no commutation failure problem, which is conducive to the stability of onshore power grids.

In some embodiments, the first converter based on the IGCT current source type can adopt a constant AC bus voltage control strategy and a constant frequency control strategy, and the second converter based on the LCC current source type can adopt a constant DC current control strategy.

Specifically, Fig. 2 is a schematic circuit diagram of the control strategy of the first converter provided according to an embodiment of the present disclosure. In this way, an AC voltage with constant amplitude and frequency is established for the wind farm, which is equivalent to a V0 node relative to the AC system of the wind farm. Among them, f _{ACref_r} and U _{ACref_r} are the setting values of the constant frequency control strategy and the constant AC bus voltage respectively, f _{AC_r} and U _{Ac_r} are the actual measured values of the frequency and AC voltage of the offshore sending end converter station, I _{dref_r} and I _{qref_r} are the offshore The d and q-axis components of the AC current of the first converter of the sending-end converter station, I _{aref_r} , I _{bref_r} , and I _{cref_r} are the reference values of the AC current modulation wave of the first converter of the offshore sending-end converter station.

Fig _. 3 is a _schematic diagram of a control strategy circuit of the second converter according to an embodiment of the present disclosure. The actual measured value of the direct current of the rectifier.

The third converter of the onshore receiving-end converter station adopts the constant DC current control strategy and the AC bus voltage control strategy, as shown in Fig. 4, where _{Idcref_i} is the setting value of the constant DC current control strategy of the third converter , U _{Acref_i} is the AC bus voltage setting value of the third converter, I _{dc_i} and U _{AC_i} are the actual measured values of the DC current and AC voltage of the third converter, I _{dref_i} and I _{qref_i} are the third converter The d and q axis components of the AC current of the converter, I _{aref_i} , I _{bref_i} , and I _{cref_i} are the reference values of the AC current modulation wave of the third converter of the offshore sending end converter station. Among them, K, P, and s are PI controllers (for example: constant AC bus voltage controller, constant frequency controller, constant DC current controller, constant reactive power controller, constant DC current controller, AC bus voltage controller wait).

In the embodiment of the present disclosure, the half-controlled device and the full-controlled device are used to cooperate with each other at the offshore sending end. The large capacity of the LCC thyristor can reduce the demand for power electronic devices when the fully-controlled device is used, further reduce the weight of the offshore platform, and help realize offshore wind power. Affordable transmission and full control of IGCT can be used as the start-up source on the LCC side, assisting the passive start-up of LCC, realizing the smooth transmission of offshore wind power, and being able to pass through DC faults. Fig. 5 is a schematic flow chart of an offshore wind power grid-connected control method according to another embodiment of the present disclosure. The control method can be executed, for example, by an offshore wind power grid-connected control system. The upper receiving end converter station, wherein the offshore sending end converter station includes the first converter based on IGCT current source type and the second converter based on LCC current source type, and the onshore receiving end converter station includes the IGCT based The third converter of the current source type is shown in Fig. 5, and the offshore wind power grid-connected control method includes:

S501: Control the first converter of the offshore sending end converter station to adopt a constant AC bus voltage control strategy and constant frequency control strategy, and control the second converter to adopt a constant DC current control strategy to convert the alternating current generated by the offshore wind farm It is direct current and sent to the onshore receiving end converter station.

S502: The third converter controlling the onshore receiving-end converter station adopts a constant direct current control strategy and an alternating current bus voltage control strategy to convert direct current into alternating current and transmit it to the onshore alternating current grid.

Specifically, in the embodiments of the present disclosure, the offshore sending-end converter station is connected to the offshore wind farm, the onshore receiving-end converter station is connected to the onshore AC power grid, and the offshore sending-end converter station and the onshore receiving-end converter station Power can be transmitted through DC cables. Wherein, the offshore sending end converter station may include a first converter based on the IGCT current source type and a second converter based on the LCC current source type. The system controls the first converter of the offshore sending end converter station to adopt a constant AC bus voltage control strategy and constant frequency control strategy, and controls the second converter to adopt a constant DC current control strategy to convert the alternating current generated by the offshore wind farm into The direct current is transmitted to the onshore receiving end converter station.

The onshore receiving end converter station includes the third converter based on the IGCT current source type. During the process of offshore wind power grid connection, the offshore wind power grid connection control system can control the third converter to adopt constant DC current control. Strategies and AC bus voltage control strategies convert the DC power to AC power and transmit it to the onshore AC grid.

In some embodiments, the sum of the transmission power of the first inverter and the second inverter is equal to the reception power of the third inverter.

In this embodiment, the offshore sending end converter station adopts the first converter based on the IGCT current source type and the second converter based on the LCC current source type, which can convert the AC power generated by the offshore wind farm into DC power and send it to the land. The upper receiving end converter station is used for transmission, and the onshore receiving end converter station adopts the third converter based on the IGCT current source type to convert the direct current delivered by the offshore sending end converter station into alternating current and transmit it to the onshore AC power grid. The offshore sending end adopts half-controlled devices and fully-controlled devices to cooperate with each other. The large capacity of LCC thyristors can reduce the demand for power electronic devices when using fully-controlled devices, further reduce the weight of offshore platforms, and help realize the parity of offshore wind power transmission, and The feature of IGCT full control can be used as the starting source of the LCC side, assisting the passive starting of the LCC, realizing the smooth transmission of offshore wind power, and being able to ride through DC faults. Furthermore, the technical problems existing in the related technologies such as the high overall cost of the offshore wind power grid-connected system, the large volume and weight of the offshore platform, and the difficulty in construction and installation are solved.

According to the embodiments of the present disclosure, the present disclosure also provides an electronic device, a readable storage medium, and a computer program product.

Other embodiments of the present application will be readily apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the application, these modifications, uses or adaptations follow the general principles of the application and include common knowledge or conventional technical means in the technical field not disclosed in the application . The specification and examples are to be considered exemplary only, with a true scope and spirit of the application indicated by the following claims.

It should be understood that the present application is not limited to the precise constructions which have been described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

It should be noted that, in the description of the present application, terms such as "first" and "second" are used for description purposes only, and should not be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, "plurality" means two or more.

Any process or method descriptions in flowcharts or otherwise described herein may be understood to represent modules, segments or portions of code comprising one or more executable instructions for implementing specific logical functions or steps of the process , and the scope of preferred embodiments of the present application includes additional implementations in which functions may be performed out of the order shown or discussed, including in substantially simultaneous fashion or in reverse order depending on the functions involved, which shall It should be understood by those skilled in the art to which the embodiments of the present application belong.

It should be understood that each part of the present application may be realized by hardware, software, firmware or a combination thereof. In the embodiments described above, various steps or methods may be implemented by software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented by any one or combination of the following techniques known in the art: Discrete logic circuits, ASICs with suitable combinational logic gates, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

Those of ordinary skill in the art can understand that all or part of the steps carried by the methods of the above embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. During execution, one or a combination of the steps of the method embodiments is included.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing module, each unit may exist separately physically, or two or more units may be integrated into one module. The above-mentioned integrated modules can be implemented in the form of hardware or in the form of software function modules. If the integrated modules are implemented in the form of software function modules and sold or used as independent products, they can also be stored in a computer-readable storage medium.

The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, and the like.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations on the present application, and those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (8)

1. An offshore wind power grid-connected system based on IGCT and LCC devices, comprising: an offshore sending-end converter station, and an onshore receiving-end converter station connected to the offshore sending-end converter station, characterized in that, The offshore sending end converter station includes a first converter based on the IGCT current source type and a second converter based on the LCC current source type, which are used to convert the alternating current generated by the offshore wind farm into direct current and supply it to the onshore Transported by the converter station at the receiving end; The onshore receiving-end converter station includes a third converter based on IGCT current source type, which is used to convert the direct current delivered by the offshore sending-end converter station into alternating current and transmit it to the onshore AC power grid. The first converter of the IGCT current source type adopts a constant AC bus voltage control strategy and a constant frequency control strategy, the second converter based on the LCC current source type adopts a constant DC current control strategy, and the IGCT current source type based The third converter adopts a constant DC current control strategy and an AC bus voltage control strategy. 2. The system according to claim 1, wherein the sum of the transmission power of the first inverter and the second inverter is equal to the reception power of the third inverter. 3. The system of claim 1, further comprising: a first step-up transformer arranged between the first converter and the offshore wind farm; a second step-up transformer arranged between the second converter and the offshore wind farm; The first step-up transformer and the second step-up transformer are configured to step up the alternating current generated by the offshore wind farm. 4 . The system according to claim 1 , wherein the first converter based on the IGCT current source type and the third converter based on the IGCT current source type both adopt an IGCT series topology. 5. The system according to claim 4, wherein the first converter and the third converter comprise three valve arms respectively, and the valve arms are formed by connecting several IGCT series diode structures in series, And the number of IGCTs in the first inverter is related to the transmission power of the first inverter, and the number of IGCTs in the third inverter is related to the reception power of the third inverter. 6. An offshore wind power grid-connected control method, which is applied to an offshore wind power grid-connected system, characterized in that the offshore wind power grid-connected system includes an offshore sending-end converter station and an onshore receiving-end converter station, wherein the The offshore sending-end converter station includes a first converter based on the IGCT current source type and a second converter based on the LCC current source type, and the onshore receiving-end converter station includes a third converter based on the IGCT current source type. streamer, the method comprising: Controlling the first converter of the offshore sending end converter station to adopt a constant AC bus voltage control strategy and a constant frequency control strategy, and controlling the second converter to adopt a constant DC current control strategy, the offshore wind farm The generated alternating current is converted into direct current and delivered to the onshore receiving end converter station; and The third converter controlling the onshore receiving-end converter station converts the direct current into alternating current by using a constant direct current control strategy and an alternating current bus voltage control strategy and transmits it to the onshore alternating current grid. 7. The method according to claim 6, wherein the sum of the transmission power of the first inverter and the second inverter is equal to the reception power of the third inverter. 8. A non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to cause the computer to execute the method according to any one of claims 6-7.