Offshore converter station and control method thereof

Abstract

The invention discloses an offshore converter station and a control method of the offshore converter station, and belongs to the technical field of offshore wind power. The positive wire direct current field comprises a positive submarine cable terminal, a first positive submarine cable, a second positive submarine cable and a first bridge arm reactor; the first bridge arm reactor is connected between the two positive submarine cables; the cathode line direct current field comprises a cathode submarine cable terminal, a first cathode submarine cable, a second cathode submarine cable and a second bridge arm reactor; the second bridge arm reactor is connected between the two cathode submarine cables; the positive and negative wire direct-current fields are connected through wires; isolation switches are arranged on the two positive submarine cables, the two negative submarine cables and the wires; the on-off state of the isolation switch is configured based on the working conditions of the two positive and negative submarine cables. The problem of power transmission failure caused by failure of any one or two submarine cables can be avoided only by changing the original single submarine cable with the positive pole and the negative pole into the two submarine cables and adding the isolating switch without increasing the plane size of an offshore platform and equipment required by a symmetric bipolar converter station, so that the power supply reliability is improved, and the submarine cable manufacturing cost is reduced.

Description

Technical Field

[0001] This application belongs to the field of offshore wind power technology, specifically relating to an offshore converter station and a control method for an offshore converter station. Background Technology

[0002] In large-capacity offshore wind power transmission projects, when the offshore converter station adopts a symmetrical monopolar wiring method, a failure in either the positive or negative submarine cable will result in the loss of all power from the offshore wind farm. If a bipolar flexible DC offshore converter station is used to solve this problem, the symmetrical bipolar technology requires converter valves and bridge arm reactors for both poles. Therefore, an additional valve hall and DC field area need to be arranged within the offshore converter station. Furthermore, in addition to the positive and negative submarine cables, a neutral cable is also required to connect to the onshore converter station, increasing the size and weight of the offshore converter station platform and resulting in higher construction costs.

[0003] In addition, existing symmetrical monopolar offshore converter stations are connected to onshore converter stations via positive and negative lines. In the context of high-voltage and large-capacity offshore wind power, the submarine cable cross-section is large, resulting in high cost. Summary of the Invention

[0004] The purpose of this application is to provide an offshore converter station and a control method for an offshore converter station, which can solve the problems that if any submarine cable of a symmetrical single-pole connection offshore converter station fails, the entire power of the offshore wind farm will be lost, while the cost of using a bipolar flexible DC offshore converter station is high.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, embodiments of this application provide an offshore converter station, including: a positive line DC field and a negative line DC field; The positive line DC field includes: a positive submarine cable terminal, a first positive submarine cable, a second positive submarine cable, and a first bridge arm reactor; the first bridge arm reactor is connected between the first positive submarine cable and the second positive submarine cable; The negative pole DC field includes: a negative pole submarine cable terminal, a first negative pole submarine cable, a second negative pole submarine cable, and a second bridge arm reactor; the second bridge arm reactor is connected between the first negative pole submarine cable and the second negative pole submarine cable; The positive electrode DC field and the negative electrode DC field are connected by a wire; The first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor are all equipped with disconnect switches; The on / off states of the disconnecting switches of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor are configured based on the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable.

[0006] Optionally, the isolating switch includes: a first positive switch, a second positive switch, a third positive switch, a first negative switch, a second negative switch, and a third negative switch; The first positive switch, the third positive switch, the first negative switch, and the third negative switch are all vertical disconnect switches. The second positive switch and the second negative switch are horizontal disconnect switches; The first positive switch is located on the first positive submarine cable near the first bridge arm reactor; the second positive switch and the third positive switch are located on the second positive submarine cable near the first bridge arm reactor; wherein, the second positive switch is located between the first bridge arm reactor and the third positive switch; The first negative switch is located on the first negative submarine cable near the second bridge arm reactor; the second negative switch and the third positive switch are located on the second negative submarine cable near the second bridge arm reactor; wherein, the second negative switch is located between the second bridge arm reactor and the third negative switch.

[0007] Optionally, the disconnecting switch further includes: a fourth positive switch and a fourth negative switch; The fourth positive switch and the fourth negative switch are vertical disconnect switches; One end of the conductor is located on the second positive submarine cable between the second positive switch and the third positive switch; the other end is located on the second negative submarine cable between the second negative switch and the third negative switch. The fourth positive switch is located on the conductor near the second positive submarine cable; the fourth negative switch is located on the conductor near the second negative submarine cable.

[0008] Optionally, If the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable are all in normal working condition, then the first positive switch, the third positive switch, the second positive switch, the first negative switch, the third negative switch, and the second positive switch are configured to be on, and the fourth positive switch and the fourth negative switch are configured to be off.

[0009] Optionally, If the first positive submarine cable and the second positive submarine cable fail simultaneously, the first negative switch, the third negative switch, the fourth negative switch, the second positive switch and the fourth positive switch are configured to be on, and the second negative switch, the first positive switch and the third positive switch are configured to be off. If the first negative submarine cable and the second negative submarine cable fail simultaneously, the first positive switch, the third positive switch, the fourth positive switch, the second negative switch, and the fourth negative switch are configured to be on, and the second positive switch, the first negative switch, and the third negative switch are configured to be off.

[0010] Optionally, If a fault occurs in one of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, or the second negative submarine cable, then all vertical disconnect switches on the faulty submarine cable are configured to be open, and all switches except the aforementioned vertical disconnect switches are configured to be closed.

[0011] Optionally, If any one of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, or the second negative submarine cable fails, all vertical disconnect switches on the faulty submarine cable are configured to be disconnected, and all switches except the aforementioned vertical disconnect switches are configured to be connected.

[0012] Secondly, embodiments of this application provide a control method for an offshore converter station, applied to the offshore converter station described in the first aspect, the method comprising: Based on the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable, configure the on / off state of the disconnecting switch of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor.

[0013] Optionally, the isolating switch comprises: a first positive switch, a second positive switch, a third positive switch, a first negative switch, a second negative switch, and a third negative switch; The first positive switch, the third positive switch, the first negative switch, and the third negative switch are all vertical disconnect switches. The second positive switch and the second negative switch are horizontal disconnect switches; The first positive switch is located on the first positive submarine cable near the first bridge arm reactor; the second positive switch and the third positive switch are located on the second positive submarine cable near the first bridge arm reactor; wherein, the second positive switch is located between the first bridge arm reactor and the third positive switch; The first negative switch is located on the first negative submarine cable near the second bridge arm reactor; the second negative switch and the third positive switch are located on the second negative submarine cable near the second bridge arm reactor; wherein, the second negative switch is located between the second bridge arm reactor and the third negative switch.

[0014] Optionally, the disconnecting switch further includes: a fourth positive switch and a fourth negative switch; The fourth positive switch and the fourth negative switch are vertical disconnect switches; One end of the conductor is located on the second positive submarine cable between the second positive switch and the third positive switch; the other end is located on the second negative submarine cable between the second negative switch and the third negative switch. The fourth positive switch is located on the conductor near the second positive submarine cable; the fourth negative switch is located on the conductor near the second negative submarine cable.

[0015] Optionally, configuring the on / off state of the disconnecting switch of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor according to the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor includes: If the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable are all in normal working condition, the first positive switch, the third positive switch, the second positive switch, the first negative switch, the third negative switch, and the second positive switch are configured to be in the on state, and the fourth positive switch and the fourth negative switch are configured to be in the off state.

[0016] Optionally, configuring the on / off state of the disconnecting switch of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor according to the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor further includes: If the first positive submarine cable and the second positive submarine cable fail simultaneously, the first negative switch, the third negative switch, the fourth negative switch, the second positive switch and the fourth positive switch are configured to be in the on state, and the second negative switch, the first positive switch and the third positive switch are configured to be in the off state. If the first negative submarine cable and the second negative submarine cable fail simultaneously, the first positive switch, the third positive switch, the fourth positive switch, the second negative switch, and the fourth negative switch are configured to be in the on state, and the second positive switch, the first negative switch, and the third negative switch are configured to be in the off state.

[0017] Optionally, configuring the on / off state of the disconnecting switch of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor according to the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor further includes: If a fault occurs in one of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, or the second negative submarine cable, all vertical disconnect switches on the faulty submarine cable are configured to be in the off state, and all switches except the vertical disconnect switches are configured to be in the on state.

[0018] Optionally, configuring the on / off state of the disconnecting switch of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor according to the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor further includes: If any one of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, or the second negative submarine cable fails, all vertical disconnect switches on the faulty submarine cable shall be set to the open state, and all switches except the aforementioned vertical disconnect switches shall be set to the closed state.

[0019] The embodiments of this application have the following advantages: This application embodiment introduces an offshore converter station, including a positive DC field and a negative DC field. The positive DC field includes a positive submarine cable terminal, a first positive submarine cable, a second positive submarine cable, and a first bridge arm reactor. The first bridge arm reactor is connected between the first positive submarine cable and the second positive submarine cable. The negative DC field includes a negative submarine cable terminal, a first negative submarine cable, a second negative submarine cable, and a second bridge arm reactor. The second bridge arm reactor is connected between the first negative submarine cable and the second negative submarine cable. The positive and negative DC fields are connected by a conductor. Isolating switches are provided on the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor. The on / off states of the isolating switches on the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor are configured based on the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable. Without increasing the size of the offshore platform or the equipment required for the bipolar converter station, simply replacing the original single large-section submarine cable for both positive and negative poles with two small-section submarine cables and adding a disconnecting switch can prevent the converter station from failing due to the failure of any one or two submarine cables, thereby improving power supply reliability and reducing the cost of submarine cables. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the positive and negative pole line system of an offshore converter station provided in an embodiment of this application; Figure 2 This is a DC field plan view of an offshore converter station provided in an embodiment of this application; Figure 3 This is a cross-sectional view of a DC field of an offshore converter station under normal operating conditions, provided in an embodiment of this application. Figure 4 This is a cross-sectional view of a simultaneous fault in two submarine cables at the positive pole of a DC field of an offshore converter station, provided in an embodiment of this application. Figure 5 This is a cross-sectional view of a fault in one submarine cable of different polarity in the DC field of an offshore converter station, provided in an embodiment of this application. Figure 6 This is a flowchart illustrating the steps of a control method for an offshore converter station provided in an embodiment of this application; The isolating switch DS includes: a first positive switch DS1-1, a second positive switch DS2-1, a third positive switch DS3-1, a fourth positive switch DS4-1, a first negative switch DS1-2, a second negative switch DS2-2, a third negative switch DS3-2, and a fourth negative switch DS4-2. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0023] The following description, in conjunction with the accompanying drawings, details a marine converter station and a control method for a marine converter station provided in this application through specific embodiments and application scenarios.

[0024] Reference Figure 1 This illustration shows a schematic diagram of the positive and negative pole line system of an offshore converter station according to an embodiment of this application. Figure 2 The diagram shows a DC field plan view of an offshore converter station according to an embodiment of this application. The offshore converter station may specifically include the following structures: a positive line DC field 1 and a negative line DC field 2. The symmetrical monopolar flexible DC offshore converter station is an advanced power conversion hub used for grid connection of long-distance, large-capacity offshore wind farms. It connects the offshore wind farm to the onshore power grid, efficiently and stably converting the AC power generated by the wind turbines into DC power for long-distance transmission. The offshore converter station is a large platform installed at sea, integrating key equipment such as transformers, converter valves, and control and protection systems to achieve AC / DC power conversion. Flexible DC refers to high-voltage DC transmission technology based on voltage source converters. Compared with traditional DC, it can independently control active and reactive power, requires no external commutation, and can supply power to passive networks, making it particularly suitable for wind power grid connection. Symmetrical monopolar is a special wiring method where the positive and negative voltages of the converter station are symmetrically distributed around the grounding reference point, eliminating the need for redundant converter equipment and neutral submarine cables, combining economic advantages with a compact structure.

[0025] This application is an improvement upon the symmetrical monopolar flexible DC offshore converter station. Unlike bipolar flexible DC offshore converter stations, it does not require an additional valve hall and DC field area within the offshore converter station. The main optimization lies in the DC field of the positive and negative poles. The positive and negative DC fields are generally adjacent and usually have independent compartments. The equipment in the compartments includes: DC through-wall bushings, allowing high-voltage DC power to be safely drawn out from the positive and negative DC fields; busbars for collecting current; DC voltage / current measuring devices for real-time monitoring of DC parameters; DC disconnect switches for maintenance isolation; surge arresters for protecting equipment from overvoltage surges; and DC submarine cable terminals for connecting high-voltage DC submarine cables to transmit power ashore.

[0026] The positive line DC field 1 includes: a positive submarine cable terminal 10 ( Figure 2 The structure consists of DCC1), a first positive submarine cable 11, a second positive submarine cable 12, and a first bridge arm reactor 13; the first bridge arm reactor 13 is connected between the first positive submarine cable 11 and the second positive submarine cable 12. The negative electrode DC field 2 includes: a negative electrode submarine cable terminal 20 ( Figure 2 The middle part consists of DCC2), a first negative submarine cable 21, a second negative submarine cable 22, and a second bridge arm reactor 23; the second bridge arm reactor 23 is connected between the first negative submarine cable 21 and the second negative submarine cable 22. The positive electrode DC field 1 and the negative electrode DC field 2 are connected by a wire 3; Symmetrical single-pole offshore converter stations are connected to onshore converter stations via positive and negative lines. In the context of high-voltage and large-capacity offshore wind power, the cross-section of the submarine cable is large and the cost is relatively high. If the positive and negative lines are first sent to the onshore converter station in the form of a double submarine cable, the cost can be significantly reduced.

[0027] The first positive submarine cable 11, the second positive submarine cable 12, the first negative submarine cable 21, the second negative submarine cable 22, and the conductor 3 are all equipped with an isolating switch DS; The on / off states of the disconnecting switch DS of the first positive submarine cable 11, the second positive submarine cable 12, the first negative submarine cable 21, the second negative submarine cable 22, and the conductor 3 are configured based on the operating conditions of the first positive submarine cable 11, the second positive submarine cable 12, the first negative submarine cable 21, and the second negative submarine cable 22.

[0028] Meanwhile, in a symmetrical single-pole connection offshore converter station, the failure of any one submarine cable will result in the loss of all power from the offshore wind farm. The design of using double-section submarine cables (optimizing the original form of sending out a single large-section submarine cable for the positive and negative poles to two small-section submarine cables for each pole) and adding a disconnecting switch between the positive and negative poles can significantly reduce the failure loss. A vertical telescopic disconnecting switch is added between the cable terminals of the positive and negative poles and connected to the conductors with through-wall bushings in the two DC field rooms. This allows the two unfaulted cables to take over the function of the positive and negative poles by operating the disconnecting switch in the event of a failure of any two submarine cables, continuing to transmit no less than half of the offshore wind farm capacity. This is suitable for large-capacity offshore wind power transmission scenarios that are far from land and difficult to maintain.

[0029] In one embodiment of this application, the isolating switch DS includes: a first positive switch DS1-1, a second positive switch DS2-1, a third positive switch DS3-1, a first negative switch DS1-2, a second negative switch DS2-2, and a third negative switch DS3-2; The first positive switch DS1-1, the third positive switch DS3-1, the first negative switch DS1-2, and the third negative switch DS3-2 are vertical disconnect switches; The second positive switch DS2-1 and the second negative switch DS2-2 are horizontal disconnect switches; The first positive switch DS1-1 is located on the first positive submarine cable 11 near the first bridge arm reactor 13; the second positive switch DS2-1 and the third positive switch DS3-1 are located on the second positive submarine cable 12 near the first bridge arm reactor; wherein, the second positive switch DS2-1 is located between the first bridge arm reactor 13 and the third positive switch DS3-1; The first negative switch DS1-2 is located on the first negative submarine cable 21 near the second bridge arm reactor 23; the second negative switch DS2-2 and the third positive switch DS3-2 are located on the second negative submarine cable 22 near the second bridge arm reactor 23; wherein, the second negative switch DS2-2 is located between the second bridge arm reactor 23 and the third negative switch DS3-2.

[0030] In one embodiment of this application, the disconnecting switch DS further includes: a fourth positive switch DS4-1 and a fourth negative switch DS4-2; The fourth positive switch DS4-1 and the fourth negative switch DS4-2 are vertical disconnect switches. One end of the conductor 3 is located on the second positive submarine cable 12 between the second positive switch DS2-1 and the third positive switch DS3-1; the other end is located on the second negative submarine cable 22 between the second negative switch DS2-2 and the third negative switch DS3-2. The fourth positive switch DS4-1 is located on the conductor 3 near the second positive submarine cable 12; the fourth negative switch DS4-2 is located on the conductor 3 near the second negative submarine cable 22.

[0031] In one embodiment of this application, if the first positive submarine cable 11, the second positive submarine cable 12, the first negative submarine cable 21, and the second negative submarine cable 22 are all operating normally, then the first positive switch DS1-1, the third positive switch DS3-1, the second positive switch DS2-1, the first negative switch DS1-2, the third negative switch DS3-2, and the second positive switch DS2-2 are configured to be on, and the fourth positive switch DS4-1 and the fourth negative switch DS4-2 are configured to be off.

[0032] In this embodiment, Figure 2 BSH2 is a DC through-wall bushing; BSH3 is a DC pole through-wall bushing; BK1 is a bridge arm reactor; MOA3 is a DC pole surge arrester; MOA4 is a bridge reactor inter-terminal surge arrester; DCC1 is the positive pole submarine cable terminal 10, DCC2 is the negative pole submarine cable terminal 20; CT3 is a DC current measuring device. These are all standard configurations for DC fields, and will not be described in detail in the embodiments of this application.

[0033] The first operating condition is the normal operating condition, where each submarine cable normally outputs power to the land, as per reference. Figure 3 The diagram shows a cross-sectional view of a DC field in normal operating condition of an offshore converter station according to an embodiment of this application. In this case, it is only necessary to configure DS1-1, DS2-1, DS3-1, DS1-2, DS2-2, and DS3-2 to be in the conducting state, and DS4-1 and DS4-2 to be in the disconnected state, so that all four submarine cables of the two pole lines can be in normal working condition.

[0034] In one embodiment of this application, if the first positive submarine cable 11 and the second positive submarine cable 12 fail simultaneously, the first positive switch DS1-1, the third positive switch DS3-1, the fourth positive switch DS4-1, the second negative switch DS2-2, and the fourth negative switch DS4-2 are configured to be turned on, and the second positive switch DS2-1, the first negative switch DS1-2, and the third negative switch DS3-2 are configured to be turned off. If the first negative submarine cable 21 and the second negative submarine cable 22 fail simultaneously, the first negative switch DS1-2, the third negative switch DS3-2, the fourth negative switch DS4-2, the second positive switch DS2-1 and the fourth positive switch DS4-1 are configured to be on, and the second negative switch DS2-2, the first positive switch DS1-1 and the third positive switch DS3-1 are configured to be off.

[0035] The second operating condition is the failure of both submarine cables of the same polarity, which is switched to the two unfailed submarine cables. Taking the failure of both positive polarity submarine cables of the same polarity as an example, refer to... Figure 4 This illustration shows a cross-sectional view of a simultaneous fault in the positive two submarine cables of a DC field at an offshore converter station, according to an embodiment of this application. In this case, only DS1-2, DS3-2, DS4-2, DS2-1, and DS4-2 need to be configured to be in the conducting state, while DS2-2, DS3-1, and DS1-1 are in the disconnected state. The two submarine cables of the negative pole then function as the positive and negative poles, respectively, and can continue to output some power to the shore. The operating condition of the two submarine cables of the same name in the negative pole is similar to that of the two submarine cables of the same name in the positive pole; only the configuration states of the positive and negative pole is swapped, i.e., DS1-1, DS3-1, DS4-1, DS2-2, and DS4-1 are configured to be in the conducting state, while DS2-1, DS3-2, and DS1-2 are in the disconnected state.

[0036] In one embodiment of this application, if a faulty submarine cable appears in each of the first positive submarine cable 11, the second positive submarine cable 12, the first negative submarine cable 21, and the second negative submarine cable 22, then all vertical disconnect switches on the faulty submarine cable are configured to be disconnected, and all switches except the vertical disconnect switches are configured to be connected.

[0037] The third operating condition is when one of the opposite polarity submarine cables is faulty. In this case, simply disconnecting the vertical telescopic DC disconnect switch corresponding to the faulty cable will allow some power to continue being output to the shore. Taking the faulty operation of both the first positive and first negative submarine cables as an example, refer to... Figure 5 The illustration shows a cross-sectional view of a faulty submarine cable on each of the different polarity lines of a marine converter station according to an embodiment of this application. In this case, only the isolating switch DS1-1 on the first positive submarine cable and the isolating switch DS1-2 on the first negative submarine cable need to be disconnected; the other isolating switches remain closed, and the remaining normally functioning submarine cables on each polarity line can still operate normally. The same principle applies to the case where one submarine cable on each of the other different polarity lines is faulty; simply disconnecting the vertical telescopic DC isolating switch corresponding to the faulty cable is sufficient. This embodiment of the application will not elaborate further.

[0038] In one embodiment of this application, if any one of the first positive submarine cable 11, the second positive submarine cable 12, the first negative submarine cable 21, and the second negative submarine cable 22 fails, all vertical disconnect switches on the faulty submarine cable are configured to be disconnected, and all switches except the aforementioned vertical disconnect switches are configured to be connected.

[0039] The fourth operating condition is when any one of the four submarine cables fails. In this case, it is similar to the third operating condition. It is only necessary to disconnect the vertical telescopic DC disconnect switch corresponding to the faulty submarine cable. Except for the vertical telescopic DC disconnect switch corresponding to the faulty submarine cable, all other disconnect switches remain closed, and some power can continue to be output to the shore. This application will not elaborate further in the embodiments.

[0040] This application provides an offshore converter station, including a positive DC field and a negative DC field. The positive DC field includes a positive submarine cable terminal, a first positive submarine cable, a second positive submarine cable, and a first bridge arm reactor. The first bridge arm reactor is connected between the first positive submarine cable and the second positive submarine cable. The negative DC field includes a negative submarine cable terminal, a first negative submarine cable, a second negative submarine cable, and a second bridge arm reactor. The second bridge arm reactor is connected between the first negative submarine cable and the second negative submarine cable. The positive and negative DC fields are connected by a conductor. Isolating switches are provided on the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor. The on / off states of the isolating switches on the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor are configured based on the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable. Without increasing the size of the offshore platform or the equipment required for the bipolar converter station, simply replacing the original single large-section submarine cable for both positive and negative poles with two small-section submarine cables and adding a disconnecting switch can prevent the converter station from failing due to the failure of any one or two submarine cables, thereby improving power supply reliability and reducing the cost of submarine cables.

[0041] Reference Figure 6 This document illustrates a flowchart of a control method for an offshore converter station according to an embodiment of this application. The method is applied to the offshore converter station described above, and specifically includes the following steps: Step 601: Based on the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable, configure the on / off state of the disconnecting switch of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor.

[0042] In one embodiment, the isolating switch includes: a first positive switch, a second positive switch, a third positive switch, a first negative switch, a second negative switch, and a third negative switch; The first positive switch, the third positive switch, the first negative switch, and the third negative switch are all vertical disconnect switches. The second positive switch and the second negative switch are horizontal disconnect switches; The first positive switch is located on the first positive submarine cable near the first bridge arm reactor; the second positive switch and the third positive switch are located on the second positive submarine cable near the first bridge arm reactor; wherein, the second positive switch is located between the first bridge arm reactor and the third positive switch; The first negative switch is located on the first negative submarine cable near the second bridge arm reactor; the second negative switch and the third positive switch are located on the second negative submarine cable near the second bridge arm reactor; wherein, the second negative switch is located between the second bridge arm reactor and the third negative switch.

[0043] In one embodiment, the disconnecting switch further includes: a fourth positive switch and a fourth negative switch; The fourth positive switch and the fourth negative switch are vertical disconnect switches; One end of the conductor is located on the second positive submarine cable between the second positive switch and the third positive switch; the other end is located on the second negative submarine cable between the second negative switch and the third negative switch. The fourth positive switch is located on the conductor near the second positive submarine cable; the fourth negative switch is located on the conductor near the second negative submarine cable.

[0044] In one embodiment, step 601 may include the following sub-steps: Sub-step S11: If the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable are all in normal working condition, configure the first positive switch, the third positive switch, the second positive switch, the first negative switch, the third negative switch, and the second positive switch to be in the on state, and configure the fourth positive switch and the fourth negative switch to be in the off state.

[0045] In one embodiment, step 601 may further include the following sub-steps: Sub-step S21: If the first positive submarine cable and the second positive submarine cable fail simultaneously, configure the first negative switch, the third negative switch, the fourth negative switch, the second positive switch and the fourth positive switch to be in the on state, and the second negative switch, the first positive switch and the third positive switch to be in the off state. In sub-step S22, if the first negative submarine cable and the second negative submarine cable both fail simultaneously, configure the first positive switch, the third positive switch, the fourth positive switch, the second negative switch, and the fourth negative switch to be in the on state, and configure the second positive switch, the first negative switch, and the third negative switch to be in the off state.

[0046] In one embodiment, step 601 may further include the following sub-steps: Sub-step S31: If a faulty submarine cable appears in the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable, configure all vertical disconnect switches on the faulty submarine cable to be in the open state, and configure all switches except the vertical disconnect switches to be in the closed state.

[0047] In one embodiment, step 601 may further include the following sub-steps: Sub-step S41: If any one of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, or the second negative submarine cable fails, configure all vertical disconnect switches on the faulty submarine cable to be in the open state, and configure all switches except the vertical disconnect switches to be in the on state.

[0048] This application provides an embodiment of an offshore converter station, including a positive DC field and a negative DC field. The positive DC field includes a positive submarine cable terminal, a first positive submarine cable, a second positive submarine cable, and a first bridge arm reactor. The first bridge arm reactor is connected between the first positive submarine cable and the second positive submarine cable. The negative DC field includes a negative submarine cable terminal, a first negative submarine cable, a second negative submarine cable, and a second bridge arm reactor. The second bridge arm reactor is connected between the first negative submarine cable and the second negative submarine cable. The positive and negative DC fields are connected by a conductor. Isolating switches are provided on the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor. The on / off states of the isolating switches on the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, the second negative submarine cable, and the conductor are configured based on the operating conditions of the first positive submarine cable, the second positive submarine cable, the first negative submarine cable, and the second negative submarine cable. Without increasing the size of the offshore platform or the equipment required for the bipolar converter station, simply replacing the original single large-section submarine cable for both positive and negative poles with two small-section submarine cables and adding a disconnecting switch can prevent the converter station from failing due to the failure of any one or two submarine cables, thereby improving power supply reliability and reducing the cost of submarine cables.

[0049] As the method embodiments are basically similar to the structural embodiments, the description is relatively simple, and relevant parts can be found in the description of the method embodiments.

[0050] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0051] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A marine converter station, characterized in that The offshore converter station comprises: a positive pole line direct current field and a negative pole line direct current field; the positive pole line direct current field comprises a positive pole submarine cable terminal, a first positive pole submarine cable, a second positive pole submarine cable and a first bridge arm reactor, the first bridge arm reactor being connected between the first positive pole submarine cable and the second positive pole submarine cable; the negative pole line direct current field comprises a negative pole submarine cable terminal, a first negative pole submarine cable, a second negative pole submarine cable and a second bridge arm reactor, the second bridge arm reactor being connected between the first negative pole submarine cable and the second negative pole submarine cable; the positive pole line direct current field and the negative pole line direct current field are connected through a conductor and a direct current bushing; each of the first positive pole submarine cable, the second positive pole submarine cable, the first negative pole submarine cable, the second negative pole submarine cable and the conductor is provided with a disconnecting switch; the on-off state of the disconnecting switch of the first positive pole submarine cable, the second positive pole submarine cable, the first negative pole submarine cable, the second negative pole submarine cable and the conductor is configured based on the working condition of the first positive pole submarine cable, the second positive pole submarine cable, the first negative pole submarine cable and the second negative pole submarine cable.

2. The offshore converter station according to claim 1, characterized in that, The disconnecting switch comprises a first positive pole switch, a second positive pole switch, a third positive pole switch, a first negative pole switch, a second negative pole switch and a third negative pole switch. The first positive pole switch, the third positive pole switch, the first negative pole switch and the third negative pole switch are vertical disconnecting switches. The second positive pole switch and the second negative pole switch are horizontal disconnecting switches. The first positive pole switch is arranged on the first positive pole submarine cable close to the first bridge arm reactor, the second positive pole switch and the third positive pole switch are arranged on the second positive pole submarine cable close to the first bridge arm reactor, and the second positive pole switch is located between the first bridge arm reactor and the third positive pole switch. The first negative pole switch is arranged on the first negative pole submarine cable close to the second bridge arm reactor, the second negative pole switch and the third negative pole switch are arranged on the second negative pole submarine cable close to the second bridge arm reactor, and the second negative pole switch is located between the second bridge arm reactor and the third negative pole switch.

3. The offshore converter station according to claim 2, characterized in that, The disconnecting switch further comprises a fourth positive pole switch and a fourth negative pole switch. The fourth positive pole switch and the fourth negative pole switch are vertical disconnecting switches. One end of the conductor is located on the second positive pole submarine cable between the second positive pole switch and the third positive pole switch, and the other end of the conductor is located on the second negative pole submarine cable between the second negative pole switch and the third negative pole switch. The fourth positive pole switch is arranged on the conductor close to the second positive pole submarine cable, and the fourth negative pole switch is arranged on the conductor close to the second negative pole submarine cable.

4. The offshore converter station according to claim 3, wherein If the working conditions of the first positive sea cable, the second positive sea cable, the first negative sea cable and the second negative sea cable are all normal, the first positive switch, the third positive switch, the second positive switch, the first negative switch, the third negative switch, the second positive switch are configured to be turned on, and the fourth positive switch and the fourth negative switch are configured to be turned off.

5. The offshore converter station according to claim 3, wherein, If the first positive sea cable and the second positive sea cable fail at the same time, the first negative switch, the third negative switch, the fourth negative switch, the second positive switch and the fourth positive switch are configured to be turned on, and the second negative switch and the first positive switch, the third positive switch are configured to be turned off; If the first negative sea cable and the second negative sea cable fail at the same time, the first positive switch, the third positive switch, the fourth positive switch, the second negative switch and the fourth negative switch are configured to be turned on, and the second positive switch and the first negative switch, the third negative switch are configured to be turned off.

6. The offshore converter station according to claim 3, wherein, If one of the first positive sea cable, the second positive sea cable and the first negative sea cable, the second negative sea cable fails, all vertical disconnectors on the failed sea cable are configured to be turned off, and all switches except the all vertical disconnectors are configured to be turned on.

7. The offshore converter station according to claim 3, wherein, If any one of the first positive sea cable, the second positive sea cable and the first negative sea cable, the second negative sea cable fails, all vertical disconnectors on the failed sea cable are configured to be turned off, and all switches except the all vertical disconnectors are configured to be turned on.

8. A control method of a marine converter station, characterized by, The method is applied to the offshore converter station as claimed in claims 1-7, and the method comprises: According to the working conditions of the first positive sea cable, the second positive sea cable, the first negative sea cable and the second negative sea cable, the on-off states of the disconnectors of the first positive sea cable, the second positive sea cable, the first negative sea cable, the second negative sea cable and the conductor are configured.

9. A control method of a marine converter station according to claim 8, characterized in that, The disconnectors comprise: a first positive switch, a second positive switch, a third positive switch, a first negative switch, a second negative switch, a third negative switch; The first positive switch, the third positive switch, the first negative switch and the third negative switch are vertical disconnectors; The second positive switch and the second negative switch are horizontal disconnectors; The first positive switch is arranged on the first positive sea cable close to the first bridge arm reactor; the second positive switch and the third positive switch are arranged on the second positive sea cable close to the first bridge arm reactor; and the second positive switch is located between the first bridge arm reactor and the third positive switch. The first negative electrode switch is arranged on the first negative electrode submarine cable close to the second bridge arm reactor; the second negative electrode switch and the third positive electrode switch are arranged on the second negative electrode submarine cable close to the second bridge arm reactor; and the second negative electrode switch is located between the second bridge arm reactor and the third negative electrode switch.

10. A control method of a marine converter station according to claim 9, characterized in that, The isolating switch further comprises a fourth positive electrode switch and a fourth negative electrode switch. The fourth positive electrode switch and the fourth negative electrode switch are vertical isolating switches. One end of the wire is located on the second positive electrode submarine cable between the second positive electrode switch and the third positive electrode switch; and the other end of the wire is located on the second negative electrode submarine cable between the second negative electrode switch and the third negative electrode switch. The fourth positive electrode switch is arranged on the wire close to the second positive electrode submarine cable; and the fourth negative electrode switch is arranged on the wire close to the second negative electrode submarine cable.

11. A control method of a marine converter station according to claim 10, characterized in that, The on-off state of the isolating switch of the first positive electrode submarine cable, the second positive electrode submarine cable, the first negative electrode submarine cable, the second negative electrode submarine cable and the wire is configured according to the working conditions of the first positive electrode submarine cable, the second positive electrode submarine cable, the first negative electrode submarine cable and the second negative electrode submarine cable, and comprises the following steps. If the working conditions of the first positive electrode submarine cable, the second positive electrode submarine cable, the first negative electrode submarine cable and the second negative electrode submarine cable are all normal, the first positive electrode switch, the third positive electrode switch, the second positive electrode switch, the first negative electrode switch, the third negative electrode switch, the second positive electrode switch are configured to be in a conductive state, and the fourth positive electrode switch and the fourth negative electrode switch are configured to be in a disconnected state.

12. A control method of a marine converter station according to claim 10, characterized in that, The on-off state of the isolating switch of the first positive electrode submarine cable, the second positive electrode submarine cable, the first negative electrode submarine cable, the second negative electrode submarine cable and the wire is configured according to the working conditions of the first positive electrode submarine cable, the second positive electrode submarine cable, the first negative electrode submarine cable and the second negative electrode submarine cable, and further comprises the following steps. If the first positive electrode submarine cable and the second positive electrode submarine cable fail at the same time, the first negative electrode switch, the third negative electrode switch, the fourth negative electrode switch, the second positive electrode switch and the fourth positive electrode switch are configured to be in a conductive state, and the second negative electrode switch and the first positive electrode switch, the third positive electrode switch are configured to be in a disconnected state. If the first negative electrode submarine cable and the second negative electrode submarine cable fail at the same time, the first positive electrode switch, the third positive electrode switch, the fourth positive electrode switch, the second negative electrode switch and the fourth negative electrode switch are configured to be in a conductive state, and the second positive electrode switch and the first negative electrode switch, the third negative electrode switch are configured to be in a disconnected state.

13. A control method of a marine converter station according to claim 10, characterized in that, The on-off state of the isolating switch of the first positive electrode submarine cable, the second positive electrode submarine cable, the first negative electrode submarine cable, the second negative electrode submarine cable and the wire is configured according to the working conditions of the first positive electrode submarine cable, the second positive electrode submarine cable, the first negative electrode submarine cable and the second negative electrode submarine cable, and further comprises the following steps. If one of the first positive sea cable, the second positive sea cable and the first negative sea cable, the second negative sea cable appears a fault sea cable, configure all vertical disconnectors on the fault sea cable to be in an open state, and all switches except the all vertical disconnectors to be in a closed state.

14. A control method of a marine converter station according to claim 10, characterized in that, The configuration of the on-off state of the disconnectors of the first positive sea cable, the second positive sea cable, the first negative sea cable, the second negative sea cable and the conductor according to the working conditions of the first positive sea cable, the second positive sea cable, the first negative sea cable and the second negative sea cable further comprises: If one of the first positive sea cable, the second positive sea cable and the first negative sea cable, the second negative sea cable appears a fault sea cable, configure all vertical disconnectors on the fault sea cable to be in an open state, and all switches except the all vertical disconnectors to be in a closed state.

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