Energy management system and method for improving electric energy output characteristics of underwater fuel cell

Abstract

The invention relates to an energy management system and method for improving the electric energy output characteristic of an underwater fuel cell, and the system comprises two groups of fuel cells which are arranged in parallel, the single group of fuel cells is connected with a DC / DC converter, the fuel cells generate electric energy through an electrochemical reaction, and the electric energy is converted by the DC / DC converter and then is output to an underwater platform power system for equipment in a platform to use; the system further comprises energy storage control devices arranged in parallel, each energy storage control device is connected with a storage battery pack, a super capacitor and a flywheel, and the system further comprises a monitoring device which monitors the working states of the fuel cell, the DC / DC converter, the energy storage control devices and the power system in real time. Through cooperation of the fuel cell, the DC / DC converter, the monitoring device, the energy storage device, the energy storage control device and other components, the impact energy of the power grid can be absorbed, and the electric energy output characteristic of the fuel cell and the operation safety of the storage battery are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater carrier platform power systems, and in particular to an energy management system and method for improving the electrical energy output characteristics of underwater fuel cells. Background Art

[0002] Underwater fuel cell propulsion systems have many advantages such as high energy conversion efficiency and specific energy, low vibration and noise, and no exhaust emissions. They can greatly improve the key performance of unmanned submersibles such as range, depth and concealment, and are a technical direction with great development potential in the field of underwater propulsion.

[0003] Fuel cells generate electricity through electrochemical reactions between hydrogen and oxygen. Due to their advantages in energy density and power generation efficiency, they have become one of the options for underwater carrier platform power systems. Considering the internal space and safety of the underwater platform, it is impossible to carry too many hydrogen and oxygen sources; and because the dynamic response characteristics of fuel cells are slow, they cannot adapt to working scenarios with frequent changes in load power. Based on the above problems, the current fuel cell power system solution uses a combination of fuel cells and batteries to output electricity, and the battery pack plays the role of peak shaving and valley filling. However, this method will cause the battery to over-charge and discharge, affecting the safety of the underwater platform. Summary of the invention

[0004] In view of the shortcomings in the above-mentioned existing production technologies, the applicant provides an energy management system and method with a rational structure for improving the power output characteristics of underwater fuel cells. Through real-time monitoring of the fuel cell power system and the electric power system, the working characteristics of the fuel cells, batteries, and energy storage devices are rationally adjusted to absorb the impact energy of the power grid, improve the power output characteristics of the fuel cell and the safety of the battery operation, and effectively ensure the safety of the underwater platform and improve the output characteristics of the fuel cell power system.

[0005] The technical solution adopted by the present invention is as follows:

[0006] An energy management system for improving the power output characteristics of underwater fuel cells, comprising two groups of fuel cells arranged in parallel, wherein a single group of fuel cells is connected to a DC / DC converter, the fuel cell generates electrical energy through an electrochemical reaction, and after conversion by the DC / DC converter, the electrical energy is output to an underwater platform power system for use by equipment on the platform; the energy management system also comprises energy storage control devices arranged in parallel, each of which is connected to a battery pack, a supercapacitor and a flywheel, and a monitoring device, which monitors the working status of the fuel cell, the DC / DC converter, the energy storage control device and the power system in real time.

[0007] As a further improvement of the above technical solution:

[0008] The supercapacitor is connected to the flywheel, and the flywheel uses the supercapacitor to charge and discharge.

[0009] The battery pack is connected to the flywheel, and the flywheel uses the battery pack to charge and discharge.

[0010] The energy storage control device is connected between the DC / DC converter and the power system.

[0011] Fuel cells are used to bear the main load demand of the power system, and the output power of the fuel cell is adjusted according to load changes. Battery packs, supercapacitors, and flywheels are used to smooth out peak loads.

[0012] A method for improving an energy management system for an underwater fuel cell power output characteristic includes the following steps:

[0013] Initial launch of the platform:

[0014] Step 1: The monitoring device first controls the energy storage control device, and the battery pack outputs electric energy to supply the power system. At the same time, the monitoring device controls the start-up of the fuel cell, and the electric energy generated by the fuel cell is converted by the DC / DC converter and supplied to the power system.

[0015] Step 2: If the output power of the fuel cell power system is greater than the power required by the power system load, the energy storage control device controls the battery pack to reduce the output power, and drives the supercapacitor and flywheel to absorb and store the excess electrical energy;

[0016] Step 3: If the electric energy output power is less than the power required by the power system load, the energy storage control device controls the battery pack to increase the output power;

[0017] Step 4: If the power output and the power required by the power system load are within the set threshold range, the monitoring device controls the fuel cell and DC / DC converter to start normally and steadily increase the output power. At the same time, the energy storage control device drives the battery pack to reduce the output power to complete the platform power-on.

[0018] Normal working status of the platform:

[0019] When the platform is working normally, the platform is mainly powered by fuel cells. During the entire working period, the output power of the fuel cells is kept constant as much as possible. When the platform load fluctuates greatly, the energy storage control device first controls the battery pack, supercapacitor, and flywheel to smooth out the peaks and fill the valleys. If the energy storage device cannot meet the load demand for a long time, the monitoring device starts the first group of fuel cells.

[0020] Platform power off process:

[0021] Since supercapacitors and flywheels cannot store energy for a long time, the energy in supercapacitors and flywheels should be consumed first during platform power outages. Since supercapacitors can charge and discharge at high power in a short period of time, direct discharge to the grid during power outages can easily cause a large impact on the grid. Therefore, supercapacitors discharge directly to the flywheel until the supercapacitors have released all the stored energy. For the battery pack, when the SOC value of the battery pack is lower than 20%, the flywheel will first discharge to the battery pack. When the energy stored in the flywheel is not enough to charge the battery pack to a SOC of 20%, the fuel cell will be raised to The power is used to charge the battery pack; when the SOC value of the battery pack is greater than or equal to 80%, the battery pack discharges to the flywheel, and the flywheel speed increases to store energy; if the flywheel reaches the rated speed before the SOC value of the battery pack drops to 80%, the fuel cell should reduce its output power, and the flywheel outputs electrical energy to the grid until the SOC value of the battery pack drops to 80%; when the SOC value of the battery pack is between 20% and 80% and the supercapacitor does not store energy, the fuel cell stops working, and the power system energy is supported by the flywheel until the flywheel speed is 0, the flywheel stops working, and the platform is powered off.

[0022] The beneficial effects of the present invention are as follows:

[0023] The present invention has a compact and reasonable structure and is easy to operate. Through the cooperation between components such as a fuel cell, a DC / DC converter, a monitoring device, an energy storage device, and an energy storage control device, the impact energy of the power grid can be absorbed and the power output characteristics of the fuel cell and the safety of the battery operation can be improved.

[0024] The present invention is used to maintain the stability of the output characteristics of the fuel cell in the platform, effectively reducing the impact of power system load fluctuations on the fuel cell output; at the same time, it can absorb excess electric energy in the power grid to improve the platform's endurance; in addition, through the energy storage control device, the battery pack, supercapacitor, flywheel and other equipment are reasonably deployed to perform peak shaving and valley filling in the power grid, reduce power loss and avoid overcharging and over-discharging of the battery pack; and the fuel cell system is monitored as a whole through the monitoring device, and the working status of the fuel cell, DC / DC converter and energy storage control device are adjusted in real time to ensure that the fuel cell system is in the best working state.

[0025] In addition, the present invention also has the following advantages:

[0026] 1. The fuel cell and energy storage device are combined to avoid frequent power changes of the fuel cell and increase the service life and endurance of the fuel cell;

[0027] 2. Flywheel energy storage and battery packs work together to bear the low-frequency fluctuations of the power system, overcoming the shortcomings of battery packs such as short energy storage life, slow response speed, and inability to charge and discharge frequently;

[0028] 3. The supercapacitor is combined with the flywheel, and the flywheel can be used to consume the high-frequency electrical energy released by the supercapacitor;

[0029] 4. The charging and discharging between the battery pack and the flywheel can ensure that the SOC of the battery pack is maintained between 20% and 80%, avoiding over-charging and discharging of the battery pack;

[0030] 5. Supercapacitors are used to bear high-frequency fluctuations in the power system, while batteries and flywheels are used to bear low-frequency fluctuations in the power system, ensuring stable output power of the fuel cell and improving the power output characteristics of the fuel cell;

[0031] 6. Use monitoring devices to monitor the status of fuel cells, DCDC, and energy storage control devices in real time to ensure that the output power of the fuel cell is balanced with the load of the power system;

[0032] 7. Based on the information from the monitoring device, the energy storage control device independently selects battery packs, supercapacitors, flywheels and other energy storage devices to smooth out grid fluctuations and fill valleys, effectively improving the energy utilization rate of fuel cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a system structure diagram of the present invention.

[0034] Figure 2 This is a power-on flow chart of the platform of the present invention.

[0035] Figure 3 This is a normal working flow chart of the platform of the present invention.

[0036] Figure 4 This is a power-off flow chart of the platform of the present invention.

[0037] Among them: 1. Fuel cell; 2. DC / DC converter; 3. Energy storage control device; 4. Battery pack; 5. Supercapacitor; 6. Flywheel; 7. Monitoring device; 8. Power system. DETAILED DESCRIPTION

[0038] The specific implementation of the present invention will be described below in conjunction with the accompanying drawings.

[0039] like Figure 1-Figure 4 As shown, the energy management system for improving the power output characteristics of underwater fuel cells in this embodiment includes two groups of fuel cells 1 arranged in parallel, a single group of fuel cells 1 is connected to a DC / DC converter 2, the fuel cell 1 generates electrical energy through an electrochemical reaction, and after conversion by the DC / DC converter 2, it is output to the underwater platform power system 8 for use by the equipment in the platform; it also includes energy storage control devices 3 arranged in parallel, each energy storage control device 3 is connected to a battery pack 4, a supercapacitor 5 and a flywheel 6, and also includes a monitoring device 7, the monitoring device 7 monitors the working status of the fuel cell 1, the DC / DC converter 2, the energy storage control device 3 and the power system 8 in real time.

[0040] The super capacitor 5 is connected to the flywheel 6 , and the flywheel 6 is charged and discharged by the super capacitor 5 .

[0041] The battery pack 4 is connected to the flywheel 6 , and the flywheel 6 is charged and discharged by the battery pack 4 .

[0042] The energy storage control device 3 is connected between the DC / DC converter 2 and the power system 8 .

[0043] The fuel cell 1 bears the main load demand of the power system 8, and the output power of the fuel cell 1 is adjusted according to the load change. The battery group 4, the super capacitor 5, and the flywheel 6 play the role of peak shaving and valley filling.

[0044] like Figure 1 As shown, the specific composition and connection relationship of the energy management system for improving the power output characteristics of the underwater platform fuel cell according to the present invention are as follows:

[0045] It mainly includes a fuel cell 1, a DC / DC converter 2, a monitoring device 7, an energy storage control device 3, etc.

[0046] The energy storage device includes a battery pack 4 , a supercapacitor energy storage 5 and a flywheel energy storage 6 .

[0047] The fuel cell 1 generates electric energy through electrochemical reaction, which is converted by the DC / DC converter 2 and output to the underwater platform power system 8 for use by the equipment in the platform. The monitoring device 7 monitors the working status of the fuel cell 1, DC / DC converter 2, energy storage control device 3, and power system 8 in real time, and the fuel cell 1 bears the main load demand of the power system 8, and adjusts the output power of the fuel cell 1 according to the load change. The battery pack 4, super capacitor 5, flywheel 6, etc. play the role of peak shaving and valley filling. In this system, the fuel cell 1 bears the load stabilization part, and keeps the output power of the fuel cell unchanged as much as possible. The battery pack 4 and flywheel 6 bear the low-frequency power fluctuations, and the super capacitor 5 bears the high-frequency fluctuations, so as to ensure the real-time balance of energy / power of the underwater platform power grid.

[0048] The main functions of each component are:

[0049] Fuel cell 1 - produces electricity through the electrochemical reaction of hydrogen and oxygen.

[0050] DC / DC converter 2 - performs voltage conversion on the output electric energy of fuel cell 1 and supplies it to power system 8 equipment.

[0051] The energy storage control device 3 receives the control signal from the monitoring device 7 and selects different energy storage device combinations to absorb and release excess energy.

[0052] Battery Group 4 - Battery Group 4 plays the role of peak shaving and valley filling, so that Battery Group 4 can bear low-frequency power fluctuations.

[0053] Supercapacitor 5 - Supercapacitor 5 plays the role of peak shaving and valley filling, and supercapacitor 5 bears high-frequency power fluctuations.

[0054] The flywheel 6 plays the role of peak shaving and valley filling, can be charged and discharged with the battery pack 4, and can be charged by the supercapacitor 5.

[0055] Monitoring device 7 - by monitoring the power consumption of power system 8 and the output power of fuel cell 1, output control signals to DC / DC converter 2 and energy storage control device 3 to ensure the source-load balance of power grid.

[0056] Power system 8--After receiving the electric energy output by the fuel cell power system, it transforms and distributes the electric energy and supplies it to the load for use.

[0057] The main functions of the present invention are:

[0058] It is mainly used to maintain the stability of the output characteristics of the fuel cell in the platform, and effectively reduce the impact of load fluctuations in the power system 8 on the output of the fuel cell; at the same time, it can absorb excess electric energy in the power grid to improve the platform's endurance; in addition, through the energy storage control device 3, the battery pack 4, supercapacitor 5, flywheel 6 and other equipment are reasonably deployed to smooth the peak of the power grid, reduce power loss and avoid overcharging and over-discharging of the battery pack 4; and the monitoring device 7 is used to monitor the entire fuel cell system, and the working status of the fuel cell, DC / DC converter 2 and the energy storage control device 3 is adjusted in real time to ensure that the fuel cell system is in the best working state.

[0059] The workflow of the present invention is as follows:

[0060] 1. Initial launch of the platform:

[0061] When the platform is initially started, the monitoring device 7 first controls the energy storage control device 3, and the battery pack 4 outputs electric energy to supply the power system 8; at the same time, the monitoring device 7 controls the fuel cell 1 to start, and the fuel cell 1 generates electric energy and supplies it to the power system 8 after conversion by the DC / DC converter 2. If the output power of the fuel cell power system is greater than the power required by the load of the power system 8, the energy storage control device 3 controls the battery pack 4 to reduce the output power, and drives the supercapacitor 5 and the flywheel 6 to absorb and store the excess electric energy; if the electric energy output power is less than the power required by the load of the power system 8, the energy storage control device 3 controls the battery pack 4 to increase the output power; if the electric energy output power and the power required by the load of the power system 8 are within the set threshold range, the monitoring device 7 controls the fuel cell 1 and the DC / DC converter 2 to start normally, and stably increase the output power, and at the same time controls the energy storage control device 3 to drive the battery pack 4 to reduce the output power, completing the power-on of the platform.

[0062] (II) Normal working status process of the platform:

[0063] When the platform is working normally, the fuel cell 1 is mainly used to power the platform. During the entire working period, the output power of the fuel cell 1 is kept constant as much as possible. When the platform load fluctuates greatly, the energy storage control device 3 first controls the battery pack 4, super capacitor 5, and flywheel 6 to smooth the peak and fill the valley; if the energy storage device cannot meet the load demand for a long time, the monitoring device 7 starts the first group of fuel cells 1.

[0064] When the power grid fluctuates, the energy storage device operates as follows: First, the monitoring device 7 communicates with the power system 8 to obtain the load power conversion information of the power system 8. After processing the information, the monitoring device 7 determines whether the power fluctuation is a high-frequency fluctuation or a low-frequency fluctuation, and sends the information to the energy storage control device 3. If the power grid fluctuation is a high-frequency fluctuation, the energy storage control device 3 controls the supercapacitor 5 to charge and discharge to smooth out the high-frequency interference of the power grid.

[0065] If the grid fluctuation is low-frequency fluctuation and the output power of the fuel cell 1 is greater than the load power of the power system 8, the energy storage control device 3 first drives the flywheel 6 to be in charging mode to absorb the excess energy in the grid; if there is more energy in the grid and the speed of the flywheel 6 reaches 80% of the rated speed, the flywheel 6 will not continue to charge, and the energy storage control device 3 will drive the battery pack 4 to charge and absorb the remaining energy. If the SOC of the battery pack 4 exceeds 80%, the battery pack 4 stops charging, and the flywheel 6 absorbs the remaining energy of the grid and the excess energy in the battery pack 4. When the speed of the flywheel 6 reaches 90% of the rated speed, the monitoring device 7 drives the fuel cell 1 to reduce the output power to match the load power of the power system 8.

[0066] If the power grid fluctuation is low-frequency fluctuation and the output power of the fuel cell 1 is less than the load power of the power system 8, the energy storage control device 3 first drives the flywheel 6 to be in the discharge mode, releasing the stored electric energy for the load of the power system 8; when the speed of the flywheel 6 reaches 20% of the rated speed, the flywheel 6 does not continue to discharge, and the energy storage control device 3 drives the battery pack 4 to discharge. If the SOC of the battery pack 4 is lower than 20%, the battery pack 4 stops discharging, and the flywheel 6 continues to discharge for the load of the power system 8. When the speed of the flywheel 6 reaches 10% of the rated speed, the monitoring device 7 drives the fuel cell 1 to increase the output power for the load of the power system 8. If a single fuel cell 1 reaches the rated power but still cannot meet the load power of the power system 8, the monitoring device 7 drives the first group of fuel cells 1 to start, and outputs electric energy for the load of the power system 8.

[0067] (III) Platform power-off process:

[0068] Since the supercapacitor 5 and the flywheel 6 cannot store energy for a long time, the electric energy in the supercapacitor 5 and the flywheel 6 should be consumed first during the platform power outage process. Since the supercapacitor 5 can charge and discharge at a high power in a short period of time, direct discharge to the power grid during the power outage process is likely to cause a large impact on the power grid. Therefore, the supercapacitor 5 directly discharges to the flywheel 6 until the supercapacitor 5 releases all the stored energy. For the battery pack 4, the SOC should be kept between 20% and 80% as much as possible after the power outage. When the SOC value of the battery pack 4 is lower than 20%, the flywheel 6 first discharges to the battery pack 4. When the energy stored in the flywheel 6 is not enough to charge the battery pack 4 to the SOC of 20%, the fuel cell 1 increases the power to charge the battery pack 4. When the SOC value of the battery pack 4 is greater than or equal to 80%, the battery pack 4 discharges to the flywheel 6, and the speed of the flywheel 6 increases the stored energy; if the flywheel 6 reaches the rated speed before the SOC value of the battery pack 4 drops to 80%, the fuel cell 1 should reduce the output power, and the flywheel 6 outputs electric energy to the power grid until the SOC value of the battery pack 4 drops to 80%. When the SOC value of the battery pack 4 is between 20% and 80% and the supercapacitor 5 does not store energy, the fuel cell 1 stops working, and the electric energy of the power system 8 is supported by the flywheel 6 until the speed of the flywheel 6 reaches 0, the flywheel 6 stops working, and the platform is powered off.

[0069] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any form of modification may be made within the scope of protection of the present invention.

Claims

1. An energy management system for improving the power output characteristics of underwater fuel cells, characterized in that: The invention comprises two groups of fuel cells (1) arranged in parallel, wherein a single group of fuel cells (1) is connected to a DC / DC converter (2), and the fuel cell (1) generates electric energy through an electrochemical reaction, which is converted by the DC / DC converter (2) and then output to an underwater platform power system (8) for use by equipment on the platform; the invention also comprises energy storage control devices (3) arranged in parallel, each energy storage control device (3) being connected to a battery group (4), a super capacitor (5) and a flywheel (6); and a monitoring device (7), which monitors the working status of the fuel cell (1), the DC / DC converter (2), the energy storage control device (3) and the power system (8) in real time.

2. The energy management system for improving the power output characteristics of underwater fuel cells according to claim 1, characterized in that: The supercapacitor (5) is connected to the flywheel (6), and the flywheel (6) is charged and discharged by the supercapacitor (5).

3. The energy management system for improving the power output characteristics of underwater fuel cells according to claim 1, characterized in that: The storage battery pack (4) is connected to the flywheel (6), and the flywheel (6) is charged and discharged by the storage battery pack (4).

4. The energy management system for improving the power output characteristics of underwater fuel cells according to claim 1, characterized in that: The energy storage control device (3) is connected between the DC / DC converter (2) and the power system (8).

5. The energy management system for improving the power output characteristics of underwater fuel cells according to claim 1, characterized in that: The fuel cell (1) bears the main load demand of the power system (8), and the output power of the fuel cell (1) is adjusted according to the load change. The battery group (4), the super capacitor (5) and the flywheel (6) play the role of peak shaving and valley filling.

6. A method for improving the energy management system of an underwater fuel cell power output characteristic as claimed in claim 1, characterized in that: The process includes: Initial launch of the platform: The first step: the monitoring device (7) first controls the energy storage control device (3), so that the storage battery group (4) outputs electric energy and supplies it to the power system; at the same time, the monitoring device (7) controls the fuel cell (1) to start, and the electric energy generated by the fuel cell is converted by the DC / DC converter (2) and supplied to the power system; Step 2: If the output power of the fuel cell power system is greater than the power required by the power system load, the energy storage control device (3) controls the battery pack (4) to reduce the output power, and drives the supercapacitor (5) and the flywheel (6) to absorb and store the excess electric energy; Step 3: If the electric energy output power is less than the power required by the power system load, the energy storage control device (3) controls the battery pack (4) to increase the output power; Step 4: If the electric energy output power and the power required by the power system load are within the set threshold range, the monitoring device (7) controls the fuel cell (1) and the DC / DC converter (2) to start normally and steadily increase the output power, and at the same time controls the energy storage control device (3) to drive the battery pack (4) to reduce the output power, thereby completing the platform power-on; Normal working status of the platform: When the platform is operating normally, the fuel cell (1) is mainly used to power the platform, and during the entire operation period, the output power of the fuel cell (1) is kept constant as much as possible; when the platform load fluctuates greatly, the energy storage control device first controls the battery group, super capacitor, and flywheel to smooth out the peak load; if the energy storage device cannot meet the load demand for a long time, the monitoring device (7) starts the first group of fuel cells (1); Platform power off process: Since the supercapacitor (5) and the flywheel (6) cannot store energy for a long time, the electric energy in the supercapacitor (5) and the flywheel (6) should be consumed first during the platform power outage process. Since the supercapacitor (5) can charge and discharge at a high power in a short period of time, direct discharge to the power grid during the power outage process is likely to cause a large impact on the power grid. Therefore, the supercapacitor (5) directly discharges to the flywheel (6) until the supercapacitor (5) releases all the stored energy. For the battery pack (4), when the SOC value of the battery pack (4) is lower than 20%, the flywheel (6) first discharges to the battery pack (4). When the energy stored in the flywheel (6) is not enough to charge the battery pack (4) to a SOC of 20%, the fuel cell (1) is increased in power. The storage battery pack (4) is charged; when the SOC value of the storage battery pack (4) is greater than or equal to 80%, the storage battery pack (4) discharges to the flywheel (6), and the speed of the flywheel (6) increases to store energy; if the flywheel (6) reaches the rated speed before the SOC value of the storage battery pack (4) drops to 80%, the fuel cell (1) should reduce the output power, and the flywheel (6) outputs electric energy to the power grid until the SOC value of the storage battery pack (4) drops to 80%; when the SOC value of the storage battery pack (4) is between 20% and 80% and the supercapacitor does not store energy, the fuel cell (1) stops working, and the electric energy of the power system (8) is supported by the flywheel (6) until the speed of the flywheel (6) is 0, the flywheel (6) stops working, and the platform is powered off.

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