Medium-voltage conversion power supply device suitable for seabed observation network

Abstract

The medium-voltage conversion power supply device is deployed between a main base station and a junction box, under the full-load state of a scientific instrument, if the working voltage of the junction box is kept at 20% or above of the minimum threshold value, a single-preceding-stage module working mode is adopted, and otherwise, a front-and-back-stage module working mode is adopted; when a single-preceding-stage module working mode is adopted, the device comprises a preceding-stage boosting module for performing first-stage boosting on medium-voltage direct current and directly supplying the medium-voltage direct current to a junction box for use through a submarine cable transmission line; when a front-back two-stage module working mode is adopted, the device comprises a front-stage boost module and a back-stage boost-buck module which are connected in series; the pre-stage boosting module performs primary boosting on the medium-voltage direct current and transmits the medium-voltage direct current to the post-stage boosting and reducing module, the post-stage boosting and reducing module injects a communication signal into the submarine cable transmission line and transmits the communication signal back to the pre-stage boosting module, and the pre-stage boosting module activates a secondary boosting function after identification; and the post-stage buck-boost module converts the boosted direct current into medium-voltage direct current and supplies the medium-voltage direct current to the junction box for use.

Description

Technical Field

[0001] The present invention belongs to the technical field of subsea observation networks, and particularly relates to a medium-voltage conversion power supply device suitable for subsea observation networks. Background Art

[0002] The backbone network of a subsea observation network consists of an onshore power supply, a submarine cable, and a subsea main base station. The onshore power supply converts commercial power into high-voltage direct current and transmits it through the submarine cable to the subsea main base station. The subsea main base station realizes the conversion of high voltage to 375V medium-voltage direct current and outputs it to the junction box.

[0003] During the actual deployment process, according to the observation needs, the distance from the junction box to the main base station ranges from dozens of meters to dozens of kilometers.

[0004] For a junction box dozens of kilometers away, if 375V medium-voltage transmission is still adopted, due to the relatively large resistivity of the submarine cable (about 1Ω / kM), a large current can cause a transmission line voltage drop of dozens to hundreds of volts. When the electric energy reaches the junction box, it is close to the lower limit of the supply voltage of the junction box, which is likely to trigger low-voltage protection and affect the observation. Summary of the Invention

[0005] Aiming at the demand of the subsea observation network for medium-voltage long-distance high-power electric energy transmission, the purpose of the present invention is to overcome the defects of the prior art and provide a medium-voltage conversion power supply system with flexible configuration and adjustable adaptability.

[0006] The present invention provides a medium-voltage conversion power supply device suitable for subsea observation networks, which is deployed between the main base station and the junction box. When the scientific instruments are fully loaded, if the operating voltage of the junction box remains above the lowest threshold of 20%, the single pre-stage module operating mode is adopted; otherwise, the front and rear double-stage module operating mode is adopted.

[0007] When the single pre-stage module operating mode is adopted, the device includes a pre-stage boost module, which boosts the medium-voltage direct current provided by the main base station by one stage and directly supplies it to the junction box through the submarine cable transmission line.

[0008] When the front and rear double-stage module operating mode is adopted, the device includes a series-connected pre-stage boost module and a post-stage buck-boost module; the pre-stage boost module boosts the medium-voltage direct current provided by the main base station by one stage and transmits it to the post-stage buck-boost module. The post-stage buck-boost module injects a communication signal into the submarine cable transmission line and transmits it back to the pre-stage boost module. After the pre-stage boost module recognizes it, it activates the secondary boost function, and the output voltage is further increased. The post-stage buck-boost module converts the boosted direct current into medium-voltage direct current and supplies it to the junction box for use.

[0009] Preferably, the submarine cable transmission line is a unipolar or bipolar submarine cable.

[0010] Preferably, in the working mode of the single pre-stage module, the boost range of the first-stage boost does not exceed the upper limit of the power supply voltage of the junction box.

[0011] Preferably, the pre-stage boost module includes: a plurality of independent sub-boost modules connected in parallel, and each sub-boost module includes: an isolation boost circuit, an auxiliary power supply circuit, a sampling circuit, a main control circuit, and a detection circuit; wherein,

[0012] The isolation boost circuit is used to boost the medium-voltage direct current provided by the main base station to the target voltage and achieve single / double-pole submarine cable compatibility through an isolation transformer;

[0013] The auxiliary power supply circuit is used to provide electrical energy for other circuits;

[0014] The sampling circuit is used to collect the real-time status of the input / output current and voltage and the system temperature;

[0015] The main control circuit is used to control the sub-boost module;

[0016] The detection circuit is used to communicate with the post-stage step-up / step-down module to determine the working mode.

[0017] Preferably, the startup process of the pre-stage boost module includes:

[0018] Judge whether the voltage of the input medium-voltage direct current meets the normal state. If it is judged to be yes, the single pre-stage module working mode is adopted, and the pre-stage boost module performs first-stage boost and enters the detection waiting state; otherwise, it is a fault and continues to judge;

[0019] Wait for the communication signal. If received, there is a post-stage step-up / step-down module, which is the working mode of the front and rear double-stage modules, and the pre-stage boost module activates the second-stage boost function.

[0020] Preferably, in the single pre-stage module working mode, the voltage V o output by the first-stage boost is:

[0021] V o = V basic1 + I o * C1

[0022] Wherein, V o is the working voltage of the target operation, V basic1 is the basic voltage of the medium-voltage direct current, I o is the output current, and C1 is the boost coefficient, which is determined by the submarine cable structure and length; when the line is in the no-load state, the pre-stage boost module maintains the V basic output. When the output power in the line rises, the output voltage of the pre-stage boost module rises accordingly to offset the influence of the transmission line voltage drop on the junction box;

[0023] In multiple sub-booster modules, all power is borne by a single sub-booster module, and the other sub-booster modules maintain V basic operation, and the pre-stage booster module is in a semi-hot standby state.

[0024] Preferably, in the working mode of the front and rear double-stage modules, the voltage V output by the secondary booster is o as follows:

[0025] V o = V basic2 - I o * C2

[0026] wherein, V o is the working voltage for target operation, V basic2 is the secondary booster base voltage, I o is the output current, and C2 is the current sharing coefficient;

[0027] Multiple sub-booster modules perform current sharing output through the Droop method, and the pre-stage booster module is in a hot standby state.

[0028] Preferably, the post-stage buck-boost module includes a plurality of mutually independent sub-buck-boost modules connected in parallel. The sub-buck-boost module includes: an isolation buck-boost circuit, an auxiliary power supply circuit, a sampling circuit, a main control circuit, and a signal superposition circuit; wherein,

[0029] The isolation buck-boost circuit is used to convert the direct current of the transmission line into medium-voltage direct current and achieve single and double-pole submarine cable compatibility through an isolation transformer;

[0030] The sampling circuit is used to collect the real-time status of the input and output current and voltage and the system temperature;

[0031] The main control circuit is used to control the sub-buck-boost module;

[0032] The signal superposition circuit is used to inject communication signals into the submarine cable transmission line to complete communication with the pre-stage booster module;

[0033] The plurality of mutually independent sub-buck-boost modules connected in parallel use the Droop current sharing algorithm for hot standby.

[0034] Preferably, the startup process of the post-stage buck-boost module includes:

[0035] Inject communication signals into the submarine cable transmission line and wait:

[0036] After the waiting timeout, judge whether the input voltage reaches the set threshold. If it is judged to be yes, the post-stage buck-boost module operates at full load and outputs medium-voltage direct current; otherwise, while maintaining constant voltage output, power limitation is performed, and the output power is limited to half load.

[0037] Compared with the prior art, the advantages of the present invention are as follows:

[0038] 1. The power transmission system proposed by the present invention, which can be adaptively adjusted, can achieve cable length self-matching and output voltage self-adaptation under the conditions of medium-voltage, long-distance, and high-power transmission, always keep the power supply voltage on the connection box side within a reasonable range, reduce the risk of input undervoltage, and improve the observation stability.

[0039] 2. The front-stage module and the rear-stage module proposed by the present invention can select different configuration schemes according to the actual distance and power demand to achieve a balance between long-distance high-power power transmission and system complexity.

[0040] 3. The operation mode adaptive algorithm proposed by the present invention can automatically select the operation mode according to different module configurations to reduce line losses.

[0041] 4. The inter-module carrier communication scheme proposed by the present invention can reduce additional communication lines and simplify system design. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a system composition diagram of the medium-voltage conversion power supply device;

[0043] Figure 2 is an internal block diagram of the front-stage boost module;

[0044] Figure 3 is a start-up flowchart of the front-stage boost module;

[0045] Figure 4 is a schematic diagram of the submarine cable transmission line;

[0046] Figure 5 is an internal block diagram of the rear-stage step-up / step-down module;

[0047] Figure 6 is a start-up flowchart of the rear-stage step-up / step-down module. DETAILED DESCRIPTION OF THE INVENTION

[0048] A medium-voltage conversion power supply device applicable to the submarine observation network of the present invention is used to solve the problem of underwater medium-voltage, long-distance, and high-power electric energy transmission. Its composition is as Figure 1 shown, and it is composed of a front-stage boost module (referred to as the front-stage module), a submarine cable transmission line, and a rear-stage step-up / step-down module (referred to as the rear-stage module).

[0049] The front-stage module is located in the main power supply network of the observation network. Its input is the medium-voltage direct current provided by the main base station, and its output is connected to the submarine cable transmission line.

[0050] The post-stage module is located on the input side of the connection box. Its input is connected to the submarine cable transmission line, and its output is medium-voltage direct current, which is connected to the input of the connection box. The post-stage module can be omitted according to requirements to further simplify the system. In this case, the submarine cable transmission line is directly connected to the connection box.

[0051] The present invention has two working modes: a single pre-stage module and a dual pre-stage and post-stage module. During actual deployment, according to the estimated power of the load, the node distance, the cable type laid, combined with the power margin, the allowable cable loss, and the voltage threshold range of the connection box and scientific instruments, a selection is made. Usually, when the scientific instrument is at full load, if the operating voltage of the connection box remains above 20% of the lowest threshold, the single pre-stage module scheme can be applied; otherwise, the dual pre-stage and post-stage module scheme is used.

[0052] The working mode of the single pre-stage is as follows: The medium-voltage direct current provided by the main base station is stepped up by the pre-stage module in one stage. The step-up range does not exceed the upper limit of the power supply voltage of the connection box and is directly supplied to the connection box through the submarine cable transmission line for use.

[0053] The working mode of the dual pre-stage and post-stage module is as follows: The medium-voltage direct current provided by the main base station is stepped up by the pre-stage module in two stages. The voltage level increased is higher than that of the single pre-stage. After being transmitted through the submarine cable transmission line, the post-stage module converts the stepped-up direct current into 375V medium-voltage direct current for the connection box to use.

[0054] The present invention can perform adaptive adjustment for the working mode of the single pre-stage module or the dual pre-stage and post-stage module.

[0055] When the single pre-stage is working, the pre-stage step-up module slowly outputs medium-voltage direct current. The electric energy is transmitted to the connection box through the submarine cable transmission line. Since there is no post-stage module in the transmission system, the secondary step-up function of the pre-stage module cannot be activated, and the module operates stably in the one-stage step-up mode. Its output voltage automatically increases according to the output current to prevent the connection box from entering the under-voltage lockout range.

[0056] When the dual pre-stage and post-stage module is working, the pre-stage step-up module slowly outputs medium-voltage direct current. The electric energy is transmitted to the post-stage module through the submarine cable transmission line. At this time, the power in the transmission line is almost zero, and the cable voltage drop can be ignored. After the post-stage module is started, a communication signal is injected into the submarine cable transmission line, and the signal is transmitted back to the pre-stage module through the submarine cable transmission line. After being recognized by the pre-stage module, the secondary step-up function is activated, and the output voltage is further increased. The post-stage module reads the voltage of the submarine cable transmission line within a certain time limit. When the voltage reaches the set threshold, it outputs a constant medium-voltage direct current in the full-power mode. When the voltage does not reach the set threshold, it outputs a constant medium-voltage direct current in the half-power mode for the connection box to use.

[0057] Main innovation points:

[0058] 1. By using the step-up module to raise the transmission line voltage, the purpose of medium-voltage long-distance high-power power transmission is achieved.

[0059] 2. The front - end and rear - end modules can be used in combination. When there is a rear - end module, the output voltage is further boosted to reduce the transmission line loss.

[0060] 3. The front - end and rear - end modules can communicate and handshake, adaptively adjust the working mode, and can be reasonably configured according to the actual project requirements.

[0061] 4. The front - end and rear - end modules perform carrier communication through the transmission line, reducing additional communication lines and lowering the system complexity.

[0062] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0063] Embodiment

[0064] An embodiment of the present invention provides a medium - voltage conversion power supply device applicable to a submarine observation network, which consists of a front - end module, a submarine cable transmission line, and a rear - end module.

[0065] The front - end module is located at the main base station. Its input is the medium - voltage direct current provided by the main base station, and its output is connected to the submarine cable transmission line.

[0066] The submarine cable transmission line can use a single - polarity or bipolar submarine cable according to the actual construction requirements.

[0067] The rear - end module is located on the input side of the junction box. Its input is connected to the submarine cable transmission line, and its output is medium - voltage direct current, which is connected to the input of the junction box. The rear - end module can be omitted according to the requirements to further simplify the system. At this time, the submarine cable transmission line is directly connected to the junction box.

[0068] The present invention is divided into two working modes: a single front - end module mode and a front - end and rear - end dual - module mode. During actual deployment, according to the estimated power of the load, the node distance, the cable type laid, combined with the power margin, the allowable cable loss, and the voltage threshold range of the junction box and scientific instruments for selection. Usually, when the scientific instrument is in a full - load state, if the working voltage of the junction box remains above 20% of the lowest threshold, the single front - end module scheme can be applied; otherwise, the front - end and rear - end dual - module scheme is used.

[0069] The working mode of the single front - end is: the medium - voltage direct current provided by the main base station is step - up by the front - end module for the first - level boost, and the boost range does not exceed the upper limit of the junction box voltage, and is directly supplied to the junction box through the submarine cable transmission line.

[0070] The working mode of the front - end and rear - end dual - module is: the medium - voltage direct current provided by the main base station is step - up by the front - end module for the second - level boost, and the boosted voltage level is higher than that of the first - level boost. After transmission through the submarine cable, the rear - end module converts the boosted direct current into medium - voltage direct current for supply to the junction box.

[0071] The internal structure of the front - end module is as Figure 2As shown in the figure, multiple independent sub-boosting modules are connected in parallel for redundancy. It internally consists of an isolated boosting circuit, an auxiliary power supply circuit, a sampling circuit, a main control circuit, and a detection circuit. Among them, the isolated boosting circuit is responsible for boosting the medium-voltage direct current to the target voltage and achieving single- and double-pole submarine cable compatibility through an isolation transformer. The auxiliary power supply circuit provides electrical energy for other circuits inside the module. The sampling circuit collects real-time states such as input and output current and voltage, and system temperature. The main control circuit controls the system. The detection circuit is used to communicate with the subsequent module to determine the working mode of the boosting module.

[0072] Its startup process is as Figure 3 shown.

[0073] 1. After the system is powered on and starts up, it judges whether the input voltage is satisfied. If it is in a normal state, the previous module works in the first-stage boosting mode and enters the detection waiting state.

[0074] 2. If there is a subsequent module, a communication signal will be received. After the signal reception is completed, the module enters the second-stage boosting mode to work.

[0075] 3. If the communication signal cannot be received, the module continues to work in the first-stage boosting mode.

[0076] The adaptive operating voltage algorithm can ensure that the scientific load is in a stable working state when operating at different platform voltages.

[0077] 1. The output voltage algorithm for the first-stage boosting mode is: V o =V basic1 +I o *C1, where V o is the target operating voltage, V basic1 is the medium-voltage direct current base voltage, I o is the output current, and C1 is the boosting coefficient, which is determined by the submarine cable structure and length. When the line is in the no-load state, the previous module maintains the output of V basic . When the output power in the line rises, the output voltage of the previous module rises accordingly to offset the influence of the transmission line voltage drop on the junction box. In this mode, all the power is borne by a single module among multiple sub-boosting modules, and the other modules maintain the operation of V basic , and the system is in a semi-hot standby state.

[0078] 2. The output voltage of the second-stage boosting mode is: V o =V basic2 -I o *C2, where V o is the target operating voltage, V basic2 is the second-stage boosting base voltage, I oLet \(I_{out}\) be the output current and \(C_2\) be the current sharing coefficient. After the boost module raises the output voltage to the secondary boost platform, it is then reduced to the medium voltage by the subsequent buck module, and the transmission line loss is completely isolated from the scientific load. In this mode, multiple sub-boost modules perform current sharing output in a Droop manner, and the system is in a hot standby state.

[0079] The submarine cable transmission methods are as Figure 4 There are two types: unipolar and bipolar. During unipolar transmission, a conduction loop is formed with seawater through the grounding electrode. Its line impedance is lower, the voltage drop is smaller, and the unipolar submarine cable technology has a higher maturity level, but an additional grounding electrode needs to be configured. The bipolar submarine cable does not require an additional grounding device, but its line impedance is higher, the voltage drop is larger, and its process maturity level is lower than that of the unipolar submarine cable. The specific construction method can be selected according to the actual project requirements.

[0080] The internal structure of the subsequent module is as Figure 5 shown. It consists of multiple independent sub-buck-boost modules connected in parallel for redundancy. It includes an isolated buck-boost circuit, an auxiliary power supply circuit, a sampling circuit, a main control circuit, and a signal superposition circuit. Among them, the isolated buck-boost circuit is responsible for converting the direct current of the transmission line to medium voltage direct current and achieving compatibility with single and double-pole submarine cables through an isolation transformer. The sampling circuit collects real-time states such as the input and output current and voltage, and the system temperature. The main control circuit controls the system, and the signal superposition circuit is used to inject communication signals into the submarine cable transmission line to complete communication with the boost module. The Droop current sharing algorithm is used among multiple sub-buck-boost modules for hot standby.

[0081] Its working process is as Figure 6 shown:

[0082] 1. When the system is powered on and starts up, the subsequent module injects a communication signal into the submarine cable transmission line and waits.

[0083] 2. After the waiting time-out, the input voltage is judged. If the voltage reaches the set threshold, the module enters the full-load working state and outputs medium voltage direct current. If the voltage does not reach the set threshold, while maintaining a constant voltage output, power limitation is performed, and the output power is limited to half load.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A medium voltage conversion power supply device suitable for a submarine observation network, deployed between a main base station and a junction box, characterized in that: When the scientific instrument is fully loaded, if the working voltage of the junction box remains above the minimum threshold of 20%, the single front-stage module working mode is adopted, otherwise the front-end and rear-end dual-stage module working mode is adopted; When the single front-stage module working mode is adopted, the device includes a front-stage boost module, which performs a first-stage boost on the medium-voltage direct current provided by the main base station and directly supplies it to the junction box through the submarine cable transmission line; When the front-and-back double-stage module working mode is adopted, the device includes a front-stage boost module and a rear-stage buck-boost module connected in series; the front-stage boost module performs a first-stage boost on the medium-voltage direct current provided by the main base station and transmits it to the rear-stage buck-boost module, the rear-stage buck-boost module injects a communication signal into the submarine cable transmission line and transmits it back to the front-stage boost module, the front-stage boost module activates the second-stage boost function after identification, and the output voltage is further increased, and the rear-stage buck-boost module converts the boosted direct current into medium-voltage direct current for supply to the junction box.

2. The medium voltage conversion power supply device suitable for the submarine observation network according to claim 1 is characterized in that: The submarine cable transmission line is a unipolar or bipolar submarine cable.

3. The medium voltage conversion power supply device suitable for a submarine observation network according to claim 1, characterized in that: In the single front-stage module working mode, the voltage boosting range of the first-stage voltage boosting does not exceed the upper limit of the power supply voltage of the connection box.

4. The medium voltage conversion power supply device suitable for a submarine observation network according to claim 1, characterized in that: The front-stage boost module includes: a plurality of mutually independent sub-boost modules connected in parallel, and the sub-boost module includes: an isolation boost circuit, an auxiliary power supply circuit, a sampling circuit, a main control circuit and a detection circuit; wherein, The isolation boost circuit is used to boost the medium voltage DC power provided by the main base station to the target voltage, and achieve single-pole and bipolar submarine cable compatibility through an isolation transformer; The auxiliary power supply circuit is used to provide power to other circuits; The sampling circuit is used to collect the real-time status of input and output current and voltage and system temperature; The main control circuit is used to control the sub-boost module; The detection circuit is used to communicate with the subsequent step-up and step-down module to determine the working mode.

5. The medium voltage conversion power supply device suitable for the seabed observation network according to claim 4 is characterized in that: The startup process of the front-stage boost module includes: Determine whether the voltage of the input medium voltage DC meets the normal state. If it is, the single front-stage module working mode is adopted, the front-stage boost module performs a first-stage boost, and enters the detection waiting state; otherwise, it is a fault and continues to be judged; Waiting for the communication signal, if received, there is a rear-stage buck-boost module, which is a front-and-rear dual-stage module working mode, and the front-stage boost module activates the secondary boost function.

6. The medium voltage conversion power supply device suitable for the seabed observation network according to claim 5, characterized in that: In the single front-stage module working mode, the voltage Vx of the first-stage boost output is: V o =V bisic1 +I o *C1 Among them, V o is the target operating voltage, V bisic1 is the medium voltage DC base voltage, I o is the output current, C1 is the boost coefficient, which is determined by the structure and length of the submarine cable; when the line is in an unloaded state, the front-stage boost module maintains V basic Output: When the output power in the line increases, the output voltage of the previous boost module increases accordingly to offset the effect of the voltage drop in the transmission line on the docking box; Among multiple sub-boost modules, a single sub-boost module bears all the power, and the other sub-boost modules maintain V basic The front-stage boost module is in semi-hot standby state.

7. The medium voltage conversion power supply device suitable for a submarine observation network according to claim 5, characterized in that: In the front-to-back double-stage module working mode, the voltage V o for: V o =V bisic2 -I o *C2 Among them, V o is the target operating voltage, V basic2 is the secondary boost base voltage, I o is the output current, C2 is the current sharing coefficient; Multiple sub-boost modules output current in a droop manner, and the front-stage boost module is in hot standby mode.

8. The medium voltage conversion power supply device suitable for a submarine observation network according to claim 1, characterized in that: The post-stage buck-boost module includes a plurality of mutually independent sub-buck-boost modules connected in parallel, and the sub-buck-boost module includes: an isolation buck-boost circuit, an auxiliary power supply circuit, a sampling circuit, a main control circuit and a signal superposition circuit; wherein, The isolation buck-boost circuit is used to convert the DC power of the transmission line into medium voltage DC power, and achieve single-pole and bipolar submarine cable compatibility through an isolation transformer; The sampling circuit is used to collect the real-time status of input and output current and voltage and system temperature; The main control circuit is used to control the sub-boost and buck-boost module; The signal superposition circuit is used to inject the communication signal into the submarine cable transmission line to complete the communication with the previous stage boost module; The multiple independent sub-buck-boost modules connected in parallel use the Droop current sharing algorithm for hot backup.

9. The medium voltage conversion power supply device suitable for a submarine observation network according to claim 1, characterized in that: The startup process of the post-stage buck-boost module includes: Inject communication signals into the submarine cable transmission line and wait for: After the waiting timeout, it is determined whether the input voltage reaches the set threshold. If it is, the subsequent buck-boost module works at full load and outputs medium voltage DC power; otherwise, power is limited while outputting at a constant voltage, and the output power is limited to half load.

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