System for rapidly switching power supply of shore power platform

Abstract

The invention provides a system for rapidly switching power supply of shore power platforms, which comprises a stable device, a rapid switching device, a remote jumping device and an optical communication workstation SDH, and is characterized in that the stable device is arranged on a plurality of offshore power platforms and a plurality of onshore switching stations, one offshore power platform is provided with a stable master station, and the other offshore power platform is provided with a remote jumping device; the rest of the offshore power platforms and the land switching stations are respectively provided with stable substations, the fast switching device is arranged on a remote jump device on the offshore power platform where the stable master station is located, and the optical communication work stations SDH are respectively arranged on each offshore power platform and each land switching station, so that networking communication of the stable devices and the remote jump devices is realized. The limitation of using a single device is overcome, a set of power supply rapid switching system is configured on an offshore power platform and a land switching station, the switching action time is effectively shortened, the risk of off-network of an oil and gas platform motor is avoided, and the reliability of oil and gas platform shore power supply is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of offshore oil shore power supply technology, and in particular to a system for rapid switching of power supply to shore power platforms. Background Technology

[0002] Currently, the power supply to offshore oil and gas platforms in my country's Bohai Bay is gradually being replaced by shore power. The stable power supply to offshore oilfield clusters is crucial; large-scale power outages would result in incalculable losses. To increase power supply reliability, the incoming submarine cables for offshore power platforms are often connected from different onshore switching stations. Offshore power platforms are interconnected by connecting submarine cables, which are normally kept on standby. In the event of a failure in any incoming submarine cable, the connecting cable switch is closed, and the other incoming submarine cable takes over all power loads, minimizing the impact of power outages on oil and gas field production. Because numerous motors in oil and gas fields require power switching times within 150ms, exceeding this time limit will cause equipment disconnection from the grid. Even after the grid voltage is restored, the motors cannot automatically resume operation, leading to disruptions in continuous production and potentially causing production and equipment accidents. Conventional automatic transfer switch (ATS) devices typically have switching times in the second range, which does not meet the switching time requirement. While single fast-switching devices meet the switching time requirement, they are limited to use within a single substation and are unsuitable for signal transmission and switching coordination under complex conditions across multiple shore power supply sites. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system for rapid switching of power supply to shore power platforms. This system can solve the problems of slow switching speed and difficulty in multi-site coordination in the prior art, which makes it difficult to achieve reliable switching of power supply to shore power systems and may lead to the disconnection of motors on offshore oil and gas platforms from the grid and production interruption.

[0004] Therefore, the present invention adopts the following technical solution: A system for rapid power switching from shore power platforms includes a stabilization device, a fast switching device, a remote switching device, and an optical communication workstation (SDH). The stabilization device is installed on multiple offshore power platforms and multiple onshore switching stations. One offshore power platform houses a stabilization master station, while the remaining offshore power platforms and onshore switching stations each house a stabilization substation. The fast switching device is installed on the offshore power platform where the stabilization master station is located and is connected to the stabilization master station via optical fiber. The remote switching device and the SDH optical communication workstation are respectively installed on each offshore power platform and each onshore switching station. The remote jump device located on the same offshore power platform and the same onshore switch station is connected to the optical communication workstation SDH via a coaxial cable. The stabilization device on the same offshore power platform and the same onshore switch station is connected to the optical communication workstation SDH via an Ethernet cable. The optical communication workstation SDH on each onshore switch station is connected to the optical communication workstation SDH on the corresponding offshore power platform via a submarine multiplexed optical cable. The optical communication workstations SDH on two offshore power platforms are connected via a submarine multiplexed optical cable, thereby realizing the network communication between the stabilization device and the remote jump device.

[0005] Based on the above technical solutions, the present invention may also employ the following further technical solutions, or combine these further technical solutions: Both the offshore power platform and the onshore switch station are equipped with high-voltage busbars. The offshore power platform is connected to the corresponding onshore switch station via an incoming submarine cable to form a main power supply path. The offshore power platforms are connected to each other via interconnecting submarine cables to form a backup power supply path. The offshore power platform is equipped with a connecting circuit breaker for switching the interconnecting submarine cable and an incoming submarine cable circuit breaker for switching the incoming submarine cable. The onshore switch station is equipped with a system outgoing circuit breaker and an outgoing submarine cable circuit breaker for switching the incoming submarine cable. The high-voltage busbar side and the outgoing submarine cable side of the onshore switch station are respectively equipped with voltage transformers and high-voltage reactance. The outgoing submarine cable side, the high-voltage busbar side, and the interconnecting submarine cable side of the offshore power platform are respectively equipped with voltage transformers.

[0006] The Anwen master station and the Anwen substation are used to collect the action signals of high-voltage bus protection, system outgoing line protection, incoming submarine cable protection, inter-submarine cable protection, and high-resistance protection at their respective locations, as well as the closed and open position status information of the incoming submarine cable circuit breaker, the outgoing submarine cable circuit breaker, and the inter-submarine circuit breaker. The information collected by each Anwen substation is sent to the Anwen master station through network communication. The Anwen master station determines whether the conditions for fast switching are met and sends a fast switching start signal to the fast switching device.

[0007] The fast-switching device communicates with the stable master station via the optical fiber and receives the fast-switching start signal from the stable master station. After receiving the fast-switching start signal, the fast-switching device collects the voltage signals of the voltage transformer on the high-voltage bus side and the voltage transformer of the connecting submarine cable on the offshore power platform where it is located. By comparing the frequency difference and phase angle difference between its high-voltage bus voltage and the voltage of the connecting submarine cable, when the difference is less than a set value, the fast-switching is initiated and the connecting circuit breaker is closed.

[0008] After the remote tripping device of the onshore switch station collects the action signals of the high-voltage bus protection, system outgoing line protection or high-resistance protection of the onshore switch station, it transmits them to the remote tripping device of the corresponding offshore power platform through the optical communication workstation SDH and the submarine multiplexed optical cable. The remote tripping device of the offshore power platform directly trips its incoming submarine cable circuit breaker without local judgment.

[0009] The power supply switching logic of the system after a fault in the incoming submarine cable is as follows: If any incoming submarine cable fails, the line protection will trip, disconnecting the submarine cable outgoing circuit breaker on the onshore switch station side and the incoming submarine cable circuit breaker on the offshore power platform side. After the Anwen main station collects the line protection action signal of the faulty incoming submarine cable, the breaker position signal of the submarine cable outgoing circuit breaker and the breaker position signal of the incoming submarine cable, it initiates a fast-switching command. Upon receiving a start command, the fast-switching device detects that the frequency and phase angle differences between the high-voltage bus voltage of its offshore power platform and the voltage of the connecting submarine cable are less than the set values. It then closes the connecting submarine cable circuit breaker, allowing another incoming submarine cable to supply power to the offshore power platform via the connecting submarine cable. The system's fast power switching logic after a fault in the high-voltage bus, system outgoing line, or high-resistance fault at the onshore switchyard is as follows: If any high-voltage busbar, system outgoing line, or high-resistance fault occurs at any onshore switching station, the protection system outgoing line circuit breaker and its submarine cable outgoing line circuit breaker will trip after the protection action is activated. The remote tripping device of the onshore switch station collected the protection action signal, initiated the remote tripping, and tripped the incoming submarine cable circuit breaker of its corresponding offshore power platform. After the Anwen main station collects the protection action signal and the opening status signal of the submarine cable outgoing circuit breaker of the onshore switch station and the corresponding submarine cable incoming circuit breaker of the offshore power platform, it initiates the fast switching command. Upon receiving a start command, the fast-switching device detects that the frequency difference and phase angle difference between the high-voltage bus voltage of its offshore power platform and the voltage of the connecting submarine cable are less than the set values. It then closes the connecting submarine cable circuit breaker, allowing another onshore switching station to supply power to the offshore power platform via the connecting submarine cable. If a high-voltage bus fault occurs on any offshore power platform, the fast-switching device on that platform is locked.

[0010] The system completes the power supply switch within 150ms.

[0011] Compared with existing technologies, this invention has the following advantages and beneficial effects: Addressing the signal transmission and switching coordination issues under complex conditions between multiple shore power supply sites, it overcomes the limitations of using a single device. A rapid power supply switching system is configured on both the offshore power platform and the onshore switchyard, effectively reducing switching time, avoiding the risk of oil and gas platform motors disconnecting from the grid, and greatly improving the reliability of shore power supply to oil and gas platforms. Remote tripping devices are separately configured on the offshore power platform and the onshore switchyard. In the event of a fault at the onshore switchyard, the onshore protection action signal can be transmitted to the offshore circuit breaker for rapid tripping. This ensures that the high-voltage connecting submarine cable is disconnected from the offshore power platform before the rapid tripping action, preventing the charging power of the high-voltage submarine cable from causing residual voltage waveform distortion on the offshore high-voltage busbar, affecting the frequency difference and phase angle difference of the rapid tripping, thereby improving the success rate of the rapid tripping device. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the main wiring of the shore power supply system according to an embodiment of the present invention.

[0013] Figure 2 This is a schematic diagram of the network configuration of the fast switching system stability device according to an embodiment of the present invention.

[0014] Figure 3 This is a network diagram of the fast switching system remote jump device according to an embodiment of the present invention.

[0015] Figure 4 This is a logic diagram of the fast switching system action (I) according to an embodiment of the present invention.

[0016] Figure 5 This is a logic diagram (II) of the fast switching system according to an embodiment of the present invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote elements with the same or similar functions throughout. However, it should be understood that the drawings are for illustrative purposes only and should not be construed as limiting the present invention. To better illustrate this embodiment, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product size. It is understandable for those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting the present invention.

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0019] This invention provides a system for rapid power switching on shore power platforms, comprising a stabilization device, a fast switching device, a remote switching device, and an optical communication workstation (SDH). The stabilization device is installed on multiple offshore power platforms and multiple onshore switching stations, with one offshore power platform housing a stabilization master station and the remaining offshore power platforms and onshore switching stations each housing a stabilization substation. The fast switching device is installed on the offshore power platform where the stabilization master station is located and is connected to the stabilization master station via optical fiber. The remote switching device and the SDH are respectively installed on each offshore power platform and each onshore power platform. On the switching station, the remote jump device located on the same offshore power platform and the same onshore switching station is connected to the optical communication workstation SDH via a coaxial cable. The stabilization device on the same offshore power platform and the same onshore switching station is connected to the optical communication workstation SDH via an Ethernet cable. The optical communication workstation SDH on each onshore switching station is connected to the optical communication workstation SDH on the corresponding offshore power platform via a submarine multiplexed optical cable. The optical communication workstations SDH on two offshore power platforms are connected via a submarine multiplexed optical cable, thereby realizing network communication between the stabilization device and the remote jump device.

[0020] Both the offshore power platform and the onshore switch station are equipped with high-voltage busbars. The offshore power platform is connected to the corresponding onshore switch station via an incoming submarine cable to form a main power supply path. The offshore power platforms are connected to each other via interconnecting submarine cables to form a backup power supply path. The offshore power platform is equipped with a connecting circuit breaker for switching the interconnecting submarine cable and an incoming submarine cable circuit breaker for switching the incoming submarine cable. The onshore switch station is equipped with a system outgoing circuit breaker and an outgoing submarine cable circuit breaker for switching the incoming submarine cable. The high-voltage busbar side and the outgoing submarine cable side of the onshore switch station are respectively equipped with voltage transformers and high-voltage reactance. The outgoing submarine cable side, the high-voltage busbar side, and the interconnecting submarine cable side of the offshore power platform are respectively equipped with voltage transformers.

[0021] The Anwen master station and the Anwen substation are used to collect the action signals of high-voltage bus protection, system outgoing line protection, incoming submarine cable protection, inter-submarine cable protection, and high-resistance protection at their respective locations, as well as the closed and open position status information of the incoming submarine cable circuit breaker, the outgoing submarine cable circuit breaker, and the inter-submarine circuit breaker. The information collected by each Anwen substation is sent to the Anwen master station through network communication. The Anwen master station determines whether the conditions for fast switching are met and sends a fast switching start signal to the fast switching device.

[0022] The fast-switching device communicates with the stable master station via the optical fiber and receives the fast-switching start signal from the stable master station. After receiving the fast-switching start signal, the fast-switching device collects the voltage signals of the voltage transformer on the high-voltage bus side and the voltage transformer of the connecting submarine cable on the offshore power platform where it is located. By comparing the frequency difference and phase angle difference between its high-voltage bus voltage and the voltage of the connecting submarine cable, when the difference is less than a set value, the fast-switching is initiated and the connecting circuit breaker is closed.

[0023] After the remote tripping device of the onshore switch station collects the action signals of the high-voltage bus protection, system outgoing line protection or high-resistance protection of the onshore switch station, it transmits them to the remote tripping device of the corresponding offshore power platform through the optical communication workstation SDH and the submarine multiplexed optical cable. The remote tripping device of the offshore power platform directly trips its incoming submarine cable circuit breaker without local judgment.

[0024] Before the fast-switching action, disconnect the submarine cable connecting the sea and land at the offshore power platform side to avoid the charging power of the high-voltage submarine cable affecting the frequency difference and angle difference of the residual voltage at sea, thereby improving the success rate of fast switching.

[0025] The power supply switching logic of the system after a fault in the incoming submarine cable is as follows: If any incoming submarine cable fails, the line protection will trip, disconnecting the submarine cable outgoing circuit breaker on the onshore switch station side and the incoming submarine cable circuit breaker on the offshore power platform side. After the Anwen main station collects the line protection action signal of the faulty incoming submarine cable, the breaker position signal of the submarine cable outgoing circuit breaker and the breaker position signal of the incoming submarine cable, it initiates a fast-switching command. Upon receiving a start command, the fast-switching device detects that the frequency and phase angle differences between the high-voltage bus voltage of its offshore power platform and the voltage of the connecting submarine cable are less than the set values. It then closes the connecting submarine cable circuit breaker, allowing another incoming submarine cable to supply power to the offshore power platform via the connecting submarine cable. The system's fast power switching logic after a fault in the high-voltage bus, system outgoing line, or high-resistance fault at the onshore switchyard is as follows: If any high-voltage busbar, system outgoing line, or high-resistance fault occurs at any onshore switching station, the protection system outgoing line circuit breaker and its submarine cable outgoing line circuit breaker will trip after the protection action is activated. The remote tripping device of the onshore switch station collected the protection action signal, initiated the remote tripping, and tripped the incoming submarine cable circuit breaker of its corresponding offshore power platform. After the Anwen main station collects the protection action signal and the opening status signal of the submarine cable outgoing circuit breaker of the onshore switch station and the corresponding submarine cable incoming circuit breaker of the offshore power platform, it initiates the fast switching command. Upon receiving a start command, the fast-switching device detects that the frequency difference and phase angle difference between the high-voltage bus voltage of its offshore power platform and the voltage of the connecting submarine cable are less than the set values. It then closes the connecting submarine cable circuit breaker, allowing another onshore switching station to supply power to the offshore power platform via the connecting submarine cable. If a high-voltage bus fault occurs on any offshore power platform, the fast-switching device on that platform is locked to prevent operation on the faulty high-voltage bus.

[0026] The system completes the power supply switch within 150ms.

[0027] The following will be combined with the appendix Figures 1-5 The embodiments of the present invention will be described in detail below: As attached Figure 1 As shown, under normal operating conditions, the No. 1 offshore power platform is powered by the No. 1 onshore switch station via submarine cable L1. Circuit breaker QF3 is located on the No. 1 offshore power platform side of submarine cable L1, and QF2 is located on the No. 1 onshore switch station side. The No. 2 offshore power platform is powered by the No. 2 onshore switch station via submarine cable L3. Circuit breaker QF6 is located on the No. 2 offshore power platform side of submarine cable L3, and QF7 is located on the No. 2 onshore switch station side. The No. 1 and No. 2 offshore power platforms are connected by a connecting submarine cable L2. Circuit breaker QF4 is located on the No. 1 offshore power platform side of submarine cable L2, and QF5 is located on the No. 2 offshore power platform side. The circuit breaker QF1 is located on the L4 side of the No. 1 onshore switch station system outgoing line, and QF8 is located on the L5 side of the No. 2 onshore switch station system outgoing line. During normal operation, circuit breaker QF4 remains open, the other circuit breakers remain closed, and the connecting submarine cable L2 is in hot standby mode.

[0028] As attached Figure 2 As shown, the safety and stability equipment in the four station areas is networked. The safety and stability substation of the No. 1 onshore switch station is connected to the SDH equipment via Ethernet cable; the safety and stability master station of the No. 1 offshore power platform is connected to the SDH equipment via Ethernet cable, and the fast-switching device is connected to the safety and stability master station via optical fiber; the safety and stability substation of the No. 2 offshore power platform is connected to the SDH equipment via Ethernet cable; and the safety and stability substation of the No. 2 onshore switch station is connected to the SDH equipment via Ethernet cable. The SDH equipment in the four station areas is networked via submarine multiplexed optical cables. The safety and stability substations or safety and stability master stations in each station area collect the protection action signals and circuit breaker status of their respective stations, transmit them through the SDH equipment network, and the information is aggregated to the safety and stability master station of the No. 1 offshore power platform. The safety and stability master station sends a fast-switching command to the fast-switching device. The fast-switching device collects the voltage of its own bus (voltage transformer 4) and the voltage of the power platform tie line (voltage transformer 5), judges the signal, and then closes the circuit breaker QF4.

[0029] As attached Figure 3As shown, the remote tripping devices of offshore power platform #1 and onshore switch station #1, and offshore power platform #2 and onshore switch station #2 are networked respectively. The remote tripping devices of onshore switch stations #1 (#2) are connected to SDH equipment via coaxial cables, and the remote tripping devices of offshore power platforms #1 (#2) are connected to SDH equipment via coaxial cables. The SDH equipment between the offshore and onshore stations is networked via submarine multiplexed optical cables. The onshore remote tripping device collects the onshore protection action signals and transmits them to the offshore remote tripping device via SDH, and disconnects the offshore circuit breaker QF3 (QF6).

[0030] Taking the power outage of the No. 1 offshore power platform as an example: (1) When a fault occurs in submarine cable L1, the circuit breakers on both sides of the line protection trip, and submarine cable L1 cannot supply power to offshore power platform No. 1. At this time, offshore power platform No. 1 loses power. See attached. Figure 1 , 4 As shown, the time is calculated from the start of the fault. After 10ms, the protection device operates. At 35ms, the circuit breakers QF2 and QF3 on both sides of the submarine cable L1 are opened. At 70ms, the No. 1 offshore power platform's main station receives information from its own station and the No. 1 onshore switch station's substation regarding the protection operation information on both sides of the submarine cable line L1 and the opening status information of circuit breakers QF2 and QF3, and sends a command to the fast-switching device. At 95ms, the fast-switching device determines the frequency difference and phase angle difference between the No. 1 offshore power platform bus voltage (voltage transformer 4) and the outgoing voltage of the connecting submarine cable L2 (voltage transformer 5). If both are less than the set value, the fast-switching condition is met, and the fast-switching device sends a closing command to circuit breaker QF4 (if the fast-switching device receives a signal from the offshore high-voltage bus protection operation, the fast-switching is locked and the program ends). At 120ms, circuit breaker QF4 is closed, and power supply to the No. 1 offshore power platform is restored.

[0031] (2) When a fault occurs on the high-voltage busbar, system outgoing line L4, or submarine cable high-resistance 1 at the No. 1 onshore switch station, the corresponding protection will trip circuit breaker QF1 or QF2, causing the No. 1 offshore power platform to lose power. (See attached...) Figure 1 , 5As shown, calculating the time from the start of the fault, after 10ms, the protection device operates; at 35ms, circuit breaker QF1 or QF2 at the No. 1 onshore switch station completes tripping; simultaneously, at 20ms, the remote tripping device FOX-41 acquires the protection action signal and initiates, transmitting a signal to the No. 1 offshore power platform to trip the submarine cable circuit breaker QF3; at 45ms, the submarine cable circuit breaker QF3 completes tripping; at 80ms, the Anwen master station acquires the high-voltage busbar, system outgoing line L4, or submarine cable high-resistance 1 protection action signal through the Anwen substation at the No. 1 onshore switch station, as well as the signal from the submarine cable circuit breaker QF3. The opening signals of circuit breakers QF2 and QF3 on both the land and sea sides are sent to the fast-switching device. At 105ms, the fast-switching device determines the frequency difference and phase angle difference between the voltage of the No. 1 offshore power platform bus (voltage transformer 4) and the voltage of the L2 connecting submarine cable (voltage transformer 5). If both are less than the set value, the fast-switching condition is met, and the fast-switching device sends a closing command to circuit breaker QF4 (if the fast-switching device receives a signal from the offshore high-voltage bus protection, the fast-switching device is locked and the program ends). At 130ms, circuit breaker QF4 closes and power supply to the No. 1 offshore power platform is restored.

[0032] Similarly, the same procedure will be followed when the No. 2 offshore power platform loses power.

[0033] In oil and gas fields, numerous electric motors require power switching times to be within 150ms. Figure 5 As shown, the Anwen master station needs to perform condition judgment and proceed to the next step after the offshore circuit breaker QF3 remotely trips. The remote trip TJR function of the traditional line differential protection device requires 40ms for activation and transmission, while this invention patent uses a separate remote trip device to reduce this to 10ms. If the remote trip TJR function of the traditional line differential protection device is used, the offshore QF3 tripping completion time is 75ms, and the Anwen master station's fast switching time is at least 110ms, and finally the circuit breaker QF4 completes closing time at 160ms, exceeding the 150ms required for many motors in oil and gas fields, thus failing to meet the requirements. However, the system for rapid switching of power supply to shore power platforms provided by this invention patent requires only 130ms for the fast switching device to complete the QF4 closing action, meeting the actual engineering requirements.

[0034] With the above-mentioned quick-switching system configuration, when a certain offshore power platform loses power, it can quickly switch to power supply from the normally operating offshore power platform connection line on the other side, which can ensure the stability of power supply to shore power platforms, minimize the risk of motor disconnection, and greatly improve the reliability of shore power supply.

[0035] Based on the description and accompanying drawings of this invention, those skilled in the art can readily manufacture or use the system for rapid switching of power supply to shore power platforms according to this invention, and can achieve the positive effects described in this invention.

[0036] It should be noted that the terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion. The terms "installed," "set," "equipped with," "connected," "linked," and "sleeve" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral construction; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two mechanisms, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] In the description of this invention, it should be understood that the terms "one end," "the other end," "outer side," "inner side," "horizontal," "end," "length," "outer end," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the mechanism or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. The terms "first" and "second" are also used only for the sake of brevity in description and do not indicate or imply relative importance.

[0038] Furthermore, in practicing the claims of this invention, those skilled in the art can understand and influence variations to the disclosed embodiments through a study of the drawings, the disclosure, and the appended claims. Additionally, in the claims and description, words such as "comprising" and "containing" do not exclude other elements or steps, and non-plural nouns do not exclude their plural forms.

[0039] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. All equivalent changes and modifications made in accordance with the present invention are covered by the scope of the claims of the present invention, and will not be listed here.

Claims

1. A system for shore power platform power supply fast switching, characterized in that, The application relates to a power supply system, which comprises stability devices, fast switching devices, remote jump devices and optical communication workstations SDH, wherein the stability devices are arranged on multiple offshore power platforms and multiple land switch stations, a stability master station is arranged on one offshore power platform, and stability sub-stations are arranged on the rest of the offshore power platforms and the land switch stations; the fast switching device is arranged on the offshore power platform where the stability master station is located, and is connected with the stability master station through an optical fiber; the remote jump device and the optical communication workstation SDH are arranged on each offshore power platform and each land switch station respectively; the remote jump device and the optical communication workstation SDH on the same offshore power platform or the same land switch station are connected through a coaxial cable; the stability device and the optical communication workstation SDH on the same offshore power platform or the same land switch station are connected through an Ethernet cable; the optical communication workstation SDH on each land switch station and the optical communication workstation SDH on the corresponding offshore power platform are connected through a submarine multiplexing optical cable; and the optical communication workstations SDH on two offshore power platforms are connected through a submarine multiplexing optical cable, so that the stability devices and the remote jump devices realize network communication.

2. A system for fast switching of shore power platform power supply as claimed in claim 1 wherein, The offshore power platform and the land switch station are both provided with high-voltage buses, the offshore power platform is connected with the corresponding land switch station through an incoming submarine cable to form a main power supply path, the offshore power platforms are connected through a tie-in submarine cable to form a standby power supply path, the offshore power platform is provided with a tie-in circuit breaker for switching the tie-in submarine cable and an incoming submarine cable circuit breaker for switching the incoming submarine cable, the land switch station is provided with a system outgoing circuit breaker and an outgoing submarine cable circuit breaker for switching the incoming submarine cable, the high-voltage bus side and the outgoing submarine cable side of the land switch station are respectively provided with a voltage transformer and a high-voltage reactor, and the incoming submarine cable side, the high-voltage bus side and the tie-in submarine cable side of the offshore power platform are respectively provided with voltage transformers.

3. A system for fast switching of shore power platform power supply as claimed in claim 2, characterized in that, The stability master station and the stability sub-stations are used for collecting high-voltage bus protection, system outgoing protection, incoming submarine cable protection, tie-in submarine cable protection and high-voltage reactor protection action signals of the positions where the stability master station and the stability sub-stations are located, and collecting the combined and separated position state information of the incoming submarine cable circuit breaker, the outgoing submarine cable circuit breaker and the tie-in circuit breaker; the information collected by each stability sub-station is sent to the stability master station through network communication; and the stability master station judges whether the fast switching condition is met and sends a fast switching starting signal to the fast switching device.

4. A system for fast switching of shore power platform power supply as claimed in claim 3 wherein, The fast switching device communicates with the stability master station through the optical fiber and receives the fast switching starting signal of the stability master station; after receiving the fast switching starting signal, the fast switching device collects the voltage signals of the high-voltage bus side voltage transformer and the tie-in submarine cable outgoing voltage transformer of the offshore power platform where the fast switching device is located; the fast switching device starts the fast switching and closes the tie-in circuit breaker when the frequency difference and the phase angle difference between the high-voltage bus voltage and the tie-in submarine cable outgoing voltage are less than the set value.

5. A system for fast switching of shore power platform power supply as claimed in claim 4 wherein, The remote trip device of the onshore switch station transmits the high-voltage bus protection, system outgoing line protection or high-voltage reactor protection action signal of the onshore switch station to the remote trip device of the corresponding offshore power platform through the SDH of the optical communication workstation and the submarine multiplex optical cable, and the remote trip device of the offshore power platform directly trips the incoming submarine cable breaker without local discrimination.

6. A system for fast switching of shore power platform power supply as claimed in claim 4 wherein, The power supply switching logic of the system after the incoming submarine cable fault is as follows: Any incoming submarine cable fault, line protection action, trip of the submarine cable outgoing line breaker at the onshore switch station side and the incoming submarine cable breaker at the offshore power platform side; After the stable master station collects the line protection action signal, the submarine cable outgoing line breaker open signal and the incoming submarine cable breaker open signal of the fault incoming submarine cable, the fast switching instruction is started; After the fast switching device receives the starting instruction, the frequency difference and the phase angle difference between the high-voltage bus voltage and the contact submarine cable outgoing line voltage of the offshore power platform are detected, and the contact submarine cable breaker is closed, and the other incoming submarine cable supplies power to the offshore power platform through the contact submarine cable.

7. A system for fast switching of shore power platform power supply as claimed in claim 5 wherein, The power supply fast switching action logic of the system after the high-voltage bus, system outgoing line or high-voltage reactor fault of the onshore switch station is as follows: Any high-voltage bus, system outgoing line or high-voltage reactor fault of the onshore switch station, protection action, trip of the system outgoing line breaker and the submarine cable outgoing line breaker thereof; The remote trip device of the onshore switch station collects the protection action signal, starts the remote trip, and trips the incoming submarine cable breaker of the corresponding offshore power platform; After the stable master station collects the protection action signal and the open signal of the submarine cable outgoing line breaker of the onshore switch station and the incoming submarine cable breaker of the corresponding offshore power platform, the fast switching instruction is started; After the fast switching device receives the starting instruction, the frequency difference and the phase angle difference between the high-voltage bus voltage and the contact submarine cable outgoing line voltage of the offshore power platform are detected, and the contact submarine cable breaker is closed, and the other incoming submarine cable supplies power to the offshore power platform through the contact submarine cable.

8. A system for fast switching of shore power platform power supply as claimed in claim 2 wherein, When any high-voltage bus of the offshore power platform fails, the fast switching device on the offshore power platform is locked.

9. A system for fast switching of shore power platform power supply as claimed in claim 1, wherein, The system completes the power supply switching within 150 ms.

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