A floating photovoltaic storage integrated charging station system and method

Abstract

The present invention provides a floating photovoltaic storage integrated charging station system and method at sea, belonging to the field of offshore photovoltaic power generation technology. The system includes a triangular floating buoy structure, a control unit installed on the floating buoy structure, an energy storage tank is provided on the floating buoy structure, an energy storage unit is installed in the energy storage tank, and a photovoltaic power generation unit is laid on the energy storage tank; the battery pack in the energy storage tank on each triangular buoy is an energy storage unit, which can effectively ensure that the entire system can maintain normal operation when a single energy storage unit fails, and the energy storage unit can supply power or charge the ship alone when the photovoltaic power generation unit does not generate electricity and the energy storage unit is sufficiently charged; the energy storage unit control adopts a drooping charge and discharge control mode, a constant power charging control mode, and a standby mode, and switches between the four control modes according to system needs to ensure stable operation of the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of offshore photovoltaic power generation, and in particular relates to an offshore floating photovoltaic-storage integrated charging station system and method. Background Art

[0002] Electrification of transportation and clean electricity have become the trend of energy consumption today. New energy and clean energy are sweeping all areas of energy consumption. Modern ships, especially ocean-going ships, usually use traditional fossil fuels due to their high power and other reasons, which cause serious pollution. Port shore power technology provides a source of energy for ships when they are berthed at the port, which can reduce pollution in the port. However, large ports generally have a large number of ships berthed offshore waiting to enter the port, and shore power facilities cannot supply them with power, making it difficult to effectively alleviate pollution in the offshore area of ​​the port.

[0003] At the same time, as an important means of transportation in modern society, ships have also become one of the targets of new energy. Electric ships have become the "new favorite" of the market with their advantages of zero emissions and low noise. However, problems such as ship power batteries and endurance have also restricted the rapid development of electric ships. It is necessary to learn from the development laws of electric vehicles and give priority to solving related charging infrastructure issues.

[0004] Under such background conditions, the construction of offshore floating charging platforms can effectively meet the needs of clean power supply for conventional ships during berthing and endurance charging for electric ships. At present, there are few studies on offshore floating charging platform stations at home and abroad, and even fewer with energy storage units. Summary of the invention

[0005] Based on the above problems, the present invention provides an offshore floating photovoltaic integrated charging station system, the charging station system comprises a triangular floating floating structure, a control unit, an energy storage unit, and a photovoltaic power generation unit. The floating floating structure is provided with an energy storage tank, the energy storage unit is installed in the energy storage tank, and the photovoltaic power generation unit is laid on the energy storage tank;

[0006] The photovoltaic power generation unit is used to convert light energy into electrical energy;

[0007] The energy storage unit is used to store excess electric energy generated by the photovoltaic power generation unit and to provide differential power when the power of the photovoltaic array power generation unit is less than the power required by the load;

[0008] The control unit is used to control the energy storage unit according to the light intensity ill, the charge state SOC, the DC bus voltage U dc and the operating mode of the charging interface with or without a load control system;

[0009] The floating buoy structure is a triangular structure in which four triangular buoys are connected, and each triangular buoy is connected by a hinge; the three apex corners of the floating buoy structure are vertical cylindrical structures; the buoy includes a tubular shell and foam, and the foam is filled in the cavity covered by the shell;

[0010] The charging station system includes four parallel energy storage units and four parallel photovoltaic power generation units, each energy storage unit includes a number of batteries connected in series, and each photovoltaic power generation unit includes a number of photovoltaic cells connected in series and in parallel; the control unit is a controller;

[0011] The charging station system also includes a charging interface, a unidirectional DC / DC converter I, a unidirectional DC / DC converter II, and a bidirectional DC / DC converter; the input interface of the unidirectional DC / DC converter I is connected to the output interface of the photovoltaic power generation unit, the PWM interface of the unidirectional DC / DC converter I is connected to the control unit, the output interface of the unidirectional DC / DC converter I is connected to the DC bus, the input interface of the unidirectional DC / DC converter II is connected to the DC bus, the PWM interface of the unidirectional DC / DC converter II is connected to the control unit, the output interface of the unidirectional DC / DC converter II is connected to the charging interface, the input interface of the bidirectional DC / DC converter is connected to the energy storage unit, the PWM interface of the bidirectional DC / DC converter is connected to the control unit, and the output interface of the bidirectional DC / DC converter is connected to the DC bus;

[0012] The charging interface, unidirectional DC / DC converter I, unidirectional DC / DC converter II, and bidirectional DC / DC converter are integrated in three control boxes, and the control boxes are installed on the three top corners of the floating structure;

[0013] An operation control method of an offshore floating photovoltaic-storage integrated charging station system is implemented based on the offshore floating photovoltaic-storage integrated charging station system, and the operation control method includes:

[0014] Mode 1, 2: When δ1% <SOC≤δ2%、 When the external load needs to be charged, the light intensity cannot make the photovoltaic power generation unit generate electricity normally, and the photovoltaic power generation unit is controlled to be in standby state, and the droop discharge control method is used to control the output power of the energy storage unit; if there is no load that needs to be charged, the light intensity cannot make the photovoltaic power generation unit generate electricity normally, and the system ends operation; where SOC represents the state of charge of the energy storage unit, ill represents the light intensity, δ1 and δ2 represent the percentage thresholds of the state of charge of the energy storage unit, δ1<δ2, Indicates the threshold value of light intensity;

[0015] Mode 3, 4: When δ1% <SOC≤δ2%、 U dc <γ1UN When the external load needs to be charged, the output power of the photovoltaic power generation unit is less than the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop discharge control method is used to control the output power of the energy storage unit; if there is no load that needs to be charged, the photovoltaic charging unit charges the energy storage unit, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop charging control method is used to charge the energy storage unit; δ1<δ2, U dc represents the DC bus voltage, γ1 represents the threshold coefficient of the DC bus voltage, U N Indicates the nominal operating voltage of the DC bus;

[0016] Mode 5, 6: When δ1% <SOC≤δ2%、 γ1U N dc <γ2U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is equal to the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the energy storage unit is controlled to be in standby state; if there is no load that needs to be charged, the photovoltaic charging unit charges the energy storage unit, and the droop constant voltage control method is used to control the output power of the photovoltaic power generation unit, and the constant power charging rate control method is used to charge the energy storage unit; the linear bus voltage range is set to γ1U N ~γ2U N ;γ2 represents the threshold coefficient of DC bus voltage, γ1<γ2;

[0017] Mode 7, 8: When δ1% <SOC≤δ2%、 U dc >γ2U N If the external load needs to be charged, the output power of the photovoltaic power generation unit is greater than the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop charging control method is used to charge the energy storage unit; if there is no load that needs to be charged, the photovoltaic charging unit charges the energy storage unit, and the droop constant voltage control method is used to control the output power of the photovoltaic power generation unit, and the constant power charging rate control method is used to charge the energy storage unit;

[0018] Mode 9, 10: When SOC>δ2%, When the external load needs to be charged, the light intensity cannot make the photovoltaic power generation unit generate electricity normally, so the photovoltaic power generation unit is controlled to be in standby state, and the output power of the energy storage unit is controlled by droop discharge control mode; if there is no load that needs to be charged, the energy storage unit is fully charged and does not need to be charged, and the system ends operation;

[0019] Mode 11, 12: When SOC>δ2%, ​U dc <γ1U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is less than the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop discharge control method is used to control the output power of the energy storage unit; if there is no load that needs to be charged, the energy storage unit is fully charged and does not need to be charged, and the system ends operation;

[0020] Mode 13, 14: When SOC>δ2%, γ1U N dc <γ2U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is equal to the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the energy storage unit is controlled to be in standby state; if there is no load that needs to be charged, the energy storage unit is fully charged and does not need to be charged, and the system ends operation;

[0021] Mode 15, 16: When SOC>δ2%, U dc >γ2U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is greater than the charging power required by the load, and the output power of the photovoltaic power generation unit is controlled by the droop constant voltage control method. The energy storage unit is sufficiently charged and does not need to be charged, and the energy storage unit is controlled to be in standby state; if there is no load that needs to be charged, the energy storage unit is sufficiently charged and does not need to be charged, and the system ends operation;

[0022] Mode 17: When SOC<δ1%, If the light intensity cannot make the photovoltaic power generation unit generate electricity normally, the energy storage unit and the load cannot be charged, and the system ends operation;

[0023] Mode 18: When SOC<δ1%, U dc <γ1U N When the output power of the photovoltaic power generation unit is less than the charging power required by the load, the charge state of the energy storage unit does not meet the discharge state, and the photovoltaic power generation unit is required to charge the energy storage unit. The MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop charging control method is used to charge the energy storage unit.

[0024] Mode 19, 20: When SOC≤δ1%, γ1U N dc <γ2U N ​​When the external load needs to be charged, the output power of the photovoltaic power generation unit is equal to the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the energy storage unit is controlled to be in standby state; if there is no load that needs to be charged, the photovoltaic power generation unit is required to charge the energy storage unit, and the droop constant voltage control method is used to control the output power of the photovoltaic power generation unit, and the constant power charging rate control method is used to charge the energy storage unit;

[0025] Mode 21, 22: When SOC≤δ1%, U dc >γ2U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is greater than the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop charging control method is used to charge the energy storage unit; if there is no load that needs to be charged, the photovoltaic power generation unit is required to charge the energy storage unit, and the droop constant voltage control method is used to control the output power of the photovoltaic power generation unit, and the constant power charging rate control method is used to charge the energy storage unit;

[0026] The droop constant voltage control method is specifically described as follows: adding voltage feedforward compensation control to the droop control, and adjusting the DC bus voltage U dc The expected value of bus voltage setting U * Compare and output compensation value ΔU through PI controller * , for U * The values ​​obtained by dynamic compensation are compared with r and i s The product of is subtracted and sent to the voltage and current dual loop control, and finally the corresponding PWM signal d is generated. pv , through d pv Control unidirectional DC / DC converter I;

[0027]

[0028] In the formula, k p and k i are the proportional adjustment coefficient and integral adjustment coefficient of the PI controller in the feedforward compensation controller respectively; i s represents the inductor current output by the converter, and r is the droop coefficient;

[0029] The droop charging control method and the droop discharging control method are specifically described as follows: dc with U * Compare and output compensation value ΔU through PI controller * , for U * The value obtained by dynamic compensation is compared with R(SOC) and i s The product of is subtracted and sent to the voltage and current dual loop control, and finally the corresponding PWM signal d is generated. b, through d b Control bidirectional DC / DC converter;

[0030]

[0031] In the formula, k′ p , k′ i are the proportional adjustment coefficient and integral adjustment coefficient of the PI controller in the feedforward compensation controller, s is the complex variable of the PI transfer function; R(SOC) is the droop coefficient based on the energy storage SOC.

[0032] The beneficial effects of the present invention are:

[0033] The present invention proposes a floating photovoltaic storage integrated charging station system and method at sea, the system includes a triangular floating buoy structure, a control unit installed on the floating buoy structure, an energy storage tank is provided on the floating buoy structure, an energy storage unit is installed in the energy storage tank, and a photovoltaic power generation unit is laid on the energy storage tank; the battery pack in the energy storage tank on each triangular buoy is an energy storage unit, which can effectively ensure that the entire system can maintain normal operation when a single energy storage unit fails, and the energy storage unit can supply power or charge the ship alone when the photovoltaic power generation unit does not generate electricity and the state of charge (SOC) of the energy storage unit is sufficient. The energy storage unit control adopts four control modes: drooping charge and discharge control mode, constant power charging control mode, and standby mode. Switching between the four control modes according to system needs ensures stable operation of the system; the power provided by the photovoltaic cell and the storage battery is supplied to conventional ships or charged to electric ships through the charging interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the offshore floating photovoltaic storage integrated charging station system of the present invention;

[0035] Figure 2 It is a schematic diagram of the floating structure of the present invention;

[0036] Figure 3 It is a schematic diagram of the aluminum alloy frame structure in the present invention;

[0037] Figure 4 This is the electrical wiring diagram of the offshore floating photovoltaic storage integrated charging station system of the present invention;

[0038] Figure 5 is a coordination control diagram of the photovoltaic power generation unit in the present invention;

[0039] Figure 6 It is a droop constant voltage control diagram of a photovoltaic power generation unit with voltage feedforward compensation in the present invention;

[0040] Figure 7 is a coordination control diagram of the energy storage unit in the present invention;

[0041] Figure 8 It is a droop charge and discharge control diagram of the energy storage unit in the present invention;

[0042] Fig. 9 This is the working logic diagram of the offshore floating photovoltaic storage integrated charging platform of the present invention;

[0043] Figures 1 to 3 Among them, 1. Floating body; 2. Aluminum alloy frame; 3. Energy storage tank; 4. Control box; 5. Hinge; 6. Mooring cable; 7. Anchor body. DETAILED DESCRIPTION

[0044] The invention will be further described below with reference to the accompanying drawings and specific implementation examples.

[0045] An offshore floating photovoltaic storage integrated charging station system comprises a triangular floating floating structure, a control unit, an energy storage unit, and a photovoltaic power generation unit. The floating floating structure is provided with an energy storage tank, the energy storage unit is installed in the energy storage tank, and the photovoltaic power generation unit is laid on the energy storage tank.

[0046] The photovoltaic power generation unit is used to convert light energy into electrical energy;

[0047] The energy storage unit is used to store excess electric energy generated by the photovoltaic power generation unit and to provide differential power when the power of the photovoltaic array power generation unit is less than the power required by the load;

[0048] The control unit is used to control the energy storage unit according to the light intensity ill, the charge state SOC, the DC bus voltage U dc and the operating mode of the charging interface with or without a load control system;

[0049] like Figures 1 to 3 As shown, the charging station system can be divided into a three-layer structure, and the bottom layer is a floating floating structure, which provides buoyancy for floating on the sea water. The middle layer includes an energy storage tank 3, a control box 4, and a control unit. The energy storage tank 3 is placed with an energy storage unit, mainly a battery with corrosion-resistant and moisture-proof treatment. The top layer is a photovoltaic charging unit placement layer, and an aluminum alloy frame 2 is installed on the floating floating structure for laying photovoltaic power generation units. Multiple photovoltaic panels form an array shape according to design requirements. The aluminum alloy frame 2 and the energy storage tank 3 are fixed on the triangular floating body 1 according to a triangular structure, and the three top corners and bottoms of the floating body 1 are connected to the anchor body 7. The anchor body 7 helps the entire offshore floating photovoltaic power generation unit resist the forces of wind, waves, and currents, and avoids excessive displacement of the offshore floating photovoltaic storage integrated system under the influence of the marine environment. The anchor body 7 can be in the form of an anchor pile or an anchor. The mooring cable 6 can be made of materials such as anchor chain, wire rope, and composite materials.

[0050] The floating buoy structure is a triangular structure in which four triangular buoys 1 are connected, and each triangular buoy 1 is connected by a hinge 5; the three apex angles of the floating buoy structure adopt a vertical cylindrical structure; the buoy 1 includes a tubular shell and foam, and the foam is filled in the cavity covered by the shell; the triangular buoy 1 is composed of three tubular shells connected, and in order to avoid the rigidity reduction and deformation caused by the excessive structure, the overall floating buoy structure adopts a structure in which four triangular buoys are connected, and the triangular buoys are connected by hinges 5, and the hinges 5 are closed and waterproof. The energy storage tank adopts a waterproof structure and is fixed on the floating structure with an aluminum alloy frame 2.

[0051] Aluminum alloy is used as the raw material of the shell. On the one hand, aluminum alloy itself has sufficient rigidity to resist cracking. On the other hand, aluminum alloy and aluminum-magnesium alloy are more resistant to seawater corrosion than other general metal plates. They are not easily rusted or corroded in various water environments. On the other hand, the density of aluminum alloy is relatively small, and the shell made of aluminum alloy itself is lighter, which can provide a larger part of the total buoyancy for the photovoltaic power generation system carried by the platform. Of course, it is also possible to consider using other lightweight, environmentally resistant, and preferably rigid materials as the raw materials of the shell to replace the polyethylene or reinforced resin commonly used in the prior art. The shell is in the shape of a hollow tube as a whole, thereby defining a cavity inside it, and the foam is filled into the cavity. As we all know, the density of foam is much smaller than that of water. In this way, even if the aluminum shell encounters extreme conditions and breaks, water penetrates into the interior of the floating tube through the cracks. Based on the characteristics of the foam, the floating tube can still provide sufficient buoyancy for the platform and the photovoltaic power generation unit it carries.

[0052] In order to prevent the entire system from maintaining normal operation when a single photovoltaic power generation unit fails, the charging station system includes four parallel energy storage units and four parallel photovoltaic power generation units. Each energy storage unit includes a number of batteries connected in series, and each photovoltaic power generation unit is composed of a number of photovoltaic cells connected in series and parallel according to the required voltage level; the control unit is a controller; the photovoltaic cell array on each triangular floating body is a photovoltaic power generation unit, and the battery array on each triangular floating body is an energy storage unit. The battery is treated with corrosion resistance and moisture resistance, and the battery is connected to the DC bus through a bidirectional DC / DC converter. The bidirectional DC / DC converter realizes the charging / discharging function of the energy storage unit. In this embodiment, the triangular floating body 1 has a side length of 8m and can accommodate a photovoltaic power generation unit with a maximum power of 17kW and a 40kWh energy storage unit.

[0053] The charging station system also includes a charging interface, a unidirectional DC / DC converter I, a unidirectional DC / DC converter II, and a bidirectional DC / DC converter. The converter is used to connect the photovoltaic power generation unit to the DC bus to achieve voltage boost and maximum power operation of the photovoltaic power generation unit. The charging interface is used to supply the electric energy provided by the system to loads such as conventional ships or electric ships. The input interface of the unidirectional DC / DC converter I is connected to the output interface of the photovoltaic power generation unit, the PWM interface of the unidirectional DC / DC converter I is connected to the control unit, the output interface of the unidirectional DC / DC converter I is connected to the DC bus, the input interface of the unidirectional DC / DC converter II is connected to the DC bus, the PWM interface of the unidirectional DC / DC converter II is connected to the control unit, the output interface of the unidirectional DC / DC converter II is connected to the charging interface, the input interface of the bidirectional DC / DC converter is connected to the energy storage unit, the PWM interface of the bidirectional DC / DC converter is connected to the control unit, and the output interface of the bidirectional DC / DC converter is connected to the DC bus; the specific wiring diagram is as follows Figure 4 shown.

[0054] The charging interface, unidirectional DC / DC converter I, unidirectional DC / DC converter II, and bidirectional DC / DC converter are integrated in three control boxes, which are installed on the three vertices of the floating structure; the control unit is installed in a control box, which is installed on the triangular floating body in the middle of the floating structure. In order to prevent the unbalanced gravity on the floating structure from causing unbalanced buoyancy of the floating structure and causing structural instability, the vertices of the floating body located below the charging interface adopt a vertical cylindrical structure and are combined with a triangular structure.

[0055] like Figure 5 As shown, the control mode of the photovoltaic power generation unit is set to: maximum power point tracking control (MPPT), droop constant voltage control and standby mode. Switch between the three operating modes according to system needs to ensure stable operation of the system.

[0056] The control mode of the energy storage unit is set as: droop charge / discharge control, constant power charge control, and standby mode; switch between the four operating modes according to system needs to ensure stable operation of the system. Moreover, when the photovoltaic power generation unit is not generating electricity and the state of charge (SOC) of the energy storage unit is sufficient, it can supply power or charge the ship alone.

[0057] The MPPT control method adopts the traditional disturbance observation method.

[0058] The droop control adopts droop control with voltage feedforward compensation. The specific improvement methods are as follows:

[0059] U dc =U * -i s r

[0060] Where: U * It represents the expected value of bus voltage setting; r is the droop coefficient.

[0061] like Figure 6 As shown in FIG. 1 , voltage feedforward compensation control is added to the traditional droop control. Specifically, the DC bus voltage U dc with U * Compare and then output the compensation value ΔU through the PI controller * , for U * Dynamic compensation is performed, and then, with the participation of droop control, the voltage and current dual-loop control is input to finally generate the corresponding PWM signal d pv , through d pv Control unidirectional DC / DC converter I.

[0062] Depend on Figure 6 Available

[0063]

[0064] In the formula, k p and k i are the parameters of the PI controller in the feedforward compensation controller. s Represents the inductor current output by the converter;

[0065] Control methods of energy storage units, such as Figure 7 As shown, the energy storage unit adopts four operating modes: droop charge and discharge control mode, constant power charge control mode and standby mode. Switch between the four operating modes according to system needs to ensure stable system operation.

[0066] The droop control adopts improved SOC droop control, and its control diagram is as follows Figure 8 As shown, through the improved SOC droop control, the resolution of the nuclear power state SOC of the energy storage unit is improved, the DC bus voltage is stabilized, and the system quickly converges to the SOC equilibrium state. The specific improved droop control method is as follows:

[0067] The improved SOC droop characteristic equation is:

[0068] U dc =U * -R(SOC)i dc

[0069] in:

[0070]

[0071] Where: R(SOC) is the droop coefficient based on the SOC of the energy storage unit; k D is the reference value of the droop coefficient; p is the convergence factor; is the average state of charge.

[0072] The above formula shows that SOC n Eventually tends to the average R(SOC) equals k D When the energy storage unit is charged dc <0 and SOC is higher than the average value, R(SOC)>k D , the energy storage unit absorbs less electricity; when SOC is lower than the average value, R(SOC) <k D , the energy storage unit absorbs more electricity. The energy storage unit discharges dc >0, when SOC is higher than the average value, R(SOC) <k D , the energy storage unit releases more electricity; when SOC is lower than the average value, R(SOC)>k D , the energy storage unit releases more electricity.

[0073] In the improved SOC droop control, voltage feedforward compensation control is added. Specifically, U dc with U * Compare and then output the compensation value ΔU through the PI controller * , for U * Dynamic compensation is performed, and then, with the participation of droop control, the voltage and current dual-loop control is input to finally generate the corresponding PWM signal d b , through d b Controls bidirectional DC / DC converters.

[0074] Depend on Figure 8 Available

[0075]

[0076] In the formula, k′ p , k′ t are the proportional adjustment coefficient and integral adjustment coefficient of the PI controller in the feedforward compensation controller, s is the complex variable of the PI transfer function; R(SOC) is the droop coefficient based on the energy storage SOC.

[0077] like Fig. 9 As shown, an operation control method of an offshore floating photovoltaic storage integrated charging station system is implemented based on the offshore floating photovoltaic storage integrated charging station system, and the operation control method includes:

[0078] Let U N is the nominal operating voltage of the DC bus of the system, combined with the state of charge (SOC) of the energy storage unit, the light intensity (ill), and the DC bus voltage U dc The overall operation conditions are divided into 22 operation modes according to the actual operation conditions of the present invention such as whether the ship needs to be charged or not:

[0079] Mode 1, 2: 20% <SOC≤90%、ill<300W / m 2 When there is a ship charging, the system operation mode is mode 1. At this time, the light intensity cannot make the photovoltaic power generation unit generate electricity normally. The photovoltaic power generation unit is in standby mode, and the energy storage unit operates in droop discharge mode. When there is no ship to be charged, the system operation mode is mode 2. At this time, the light intensity cannot make the photovoltaic power generation unit generate electricity normally, and the system ends operation.

[0080] Mode 3, 4: 20%<SOC≤90%、ill> 300W / m 2 , U dc <0.98U N When there is a ship charging, the system operation mode is mode 3. At this time, the output power of the photovoltaic power generation unit is still less than the charging power of the ship. The energy storage unit provides the difference power. The photovoltaic power generation unit operates in MPPT mode and the energy storage unit operates in droop discharge mode. When there is no ship to be charged, the system operation mode is mode 4. At this time, the photovoltaic power generation unit charges the energy storage unit. In order to improve the utilization efficiency of the photovoltaic power generation unit, the photovoltaic power generation unit operates in MPPT mode and the energy storage unit operates in droop charging mode.

[0081] Mode 5, 6: 20%<SOC≤90%、ill> 300W / m 2 、0.98U N dc <1.02U N When there is a ship charging, the system operation mode is mode 5. At this time, the output power of the photovoltaic power generation unit just meets the charging power of the ship. The photovoltaic power generation unit operates in MPPT mode and the energy storage unit operates in standby mode. When there is no ship to be charged, the system operation mode is mode 6. At this time, the photovoltaic power generation unit charges the energy storage unit. The photovoltaic power generation unit operates in the drooping constant voltage control mode, and the energy storage unit operates in the constant power charging rate mode. In order to avoid frequent switching of the energy storage unit charging and discharging mode, the linear bus voltage range under modes 5 and 6 is set to 0.98U N To 1.02U N .

[0082] Mode 7, 8: 20%<SOC≤90%、ill> 300W / m 2 , U dc >1.02U N ​When there is a ship charging, the system operation mode is mode 7. At this time, the output power of the photovoltaic power generation unit is greater than the charging power of the ship. The photovoltaic power generation unit operates in MPPT mode, and the energy storage unit operates in droop charging mode. When there is no ship to be charged, the system operation mode is mode 8. At this time, the photovoltaic power generation unit charges the energy storage unit, the photovoltaic power generation unit operates in droop constant voltage control mode, and the energy storage unit operates in constant power mode.

[0083] Mode 9, 10: SOC>90%, ill<300W / m 2 When there are ships charging, the system operation mode is mode 9. At this time, the light intensity cannot make the photovoltaic power generation unit generate electricity normally. The photovoltaic power generation unit is in standby mode, and the energy storage unit operates in droop discharge mode. When there are no ships to be charged, the system operation mode is mode 10. At this time, the light intensity cannot make the photovoltaic power generation unit generate electricity normally, the energy storage unit is fully charged and does not need to be charged, and the system ends operation.

[0084] Mode 11, 12: SOC>90%, ill>300W / m 2 , U dc <0.98U N When there is a ship charging, the system operation mode is mode 11. At this time, the output power of the photovoltaic power generation unit is still less than the charging power of the ship. The energy storage unit provides the difference power, the photovoltaic power generation unit operates in MPPT mode, and the energy storage unit operates in droop discharge mode. When there is no ship charging, the system operation mode is mode 12. At this time, the energy storage single charge state is sufficient and does not need to be charged, and the system ends operation.

[0085] Mode 13, 14: SOC>90%, ill>300W / m 2 、0.98U N dc <1.02U N When there is a ship charging, the system operation mode is mode 13. At this time, the output power of the photovoltaic power generation unit just meets the charging power of the ship. The photovoltaic power generation unit operates in MPPT mode and the energy storage unit operates in standby mode. When there is no ship, the system operation mode is mode 14. At this time, the energy storage unit is fully charged and does not need to be charged, and the system ends operation.

[0086] Mode 15, 16: SOC>90%, ill>300W / m 2 , U dc >1.02U N ​When there is a ship charging, the system operation mode is mode 15. At this time, the output power of the photovoltaic power generation unit is greater than the charging power of the ship, and the photovoltaic power generation unit operates in the drooping constant voltage control mode. At this time, the energy storage unit is fully charged and does not need to be charged and is in standby mode. When there is no ship to be charged, the system operation mode is mode 16. At this time, the energy storage unit is fully charged and does not need to be charged, and the system ends operation.

[0087] Mode 17: SOC≤20%, ill<300W / m 2 At this time, the light intensity cannot make the photovoltaic power generation unit generate electricity normally, and the energy storage unit charge state does not meet the discharge state, and cannot provide charging services to the ship. The system ends operation.

[0088] Mode 18: SOC≤20%, ill>300W / m 2 , U dc <0.98U N At this time, the output power of the photovoltaic power generation unit is still less than the charging power of the ship. The charge state of the energy storage unit does not meet the discharge state and cannot provide charging services to the ship. The photovoltaic power generation system charges the energy storage unit. The photovoltaic power generation unit operates in the MPPT mode, and the energy storage unit operates in the droop charging control mode.

[0089] Mode 19, 20: SOC ≤ 20%, ill> 300W / m 2 、0.98U N dc <1.02U N , when there is a ship charging, the system operation mode is mode 19. At this time, the output power of the photovoltaic power generation unit just meets the charging power of the ship, the photovoltaic power generation unit operates in MPPT mode, and the energy storage unit operates in standby mode. When there is no ship to be charged, the system operation mode is mode 20. At this time, the photovoltaic power generation unit charges the energy storage unit, the photovoltaic power generation unit operates in the droop constant voltage control mode, and the energy storage unit operates in the constant power charging control mode.

[0090] Mode 21, 22: SOC ≤ 20%, ill> 300W / m 2 , U dc >1.02U N When there is a ship charging, the system operation mode is mode 21. At this time, the output power of the photovoltaic power generation unit is greater than the charging power of the ship. The photovoltaic power generation unit operates in MPPT mode, and the energy storage unit operates in droop charging control mode. When there is no ship to be charged, the system operation mode is mode 22. At this time, the photovoltaic power generation unit charges the energy storage unit, the photovoltaic power generation unit operates in droop constant voltage control mode, and the energy storage unit operates in constant power charging control mode.

[0091] ​In order to realize the normal startup, operation and shutdown of the control system, a human-machine interaction interface is designed and installed at each charging port. It specifically implements the following functions:

[0092] Start the system: Design a start button. When a ship needs to be charged and the system is in the off state, the system can be started by pressing the start button. After starting, the control system determines whether the charging conditions are met. When the conditions are met, the screen displays "Please plug in the device to start charging". When charging starts, the screen displays "Power is being supplied". When charging is completed, the screen displays "Charging is completed". When the charging conditions are not met, the screen displays "Currently unable to supply power".

[0093] Regularly check SOC and light intensity: automatically start the system when SOC is less than 90% and light intensity meets system operating conditions.

[0094] Shut down the system: When the control system determines that the operation has ended or the system fails and cannot operate normally, the system will be automatically shut down.

Claims

1. An operation control method for an offshore floating photovoltaic storage integrated charging station system, characterized in that: The operation control method comprises: When δ1% <SOC≤δ2%、 When the external load needs to be charged, the light intensity cannot make the photovoltaic power generation unit generate electricity normally, so the photovoltaic power generation unit is controlled to be in standby state, and the droop discharge control method is used to control the output power of the energy storage unit; if there is no load that needs to be charged, the system ends operation; where SOC represents the state of charge of the energy storage unit, ill represents the light intensity, δ1 and δ2 represent the percentage thresholds of the state of charge of the energy storage unit, δ1<δ2, Indicates the threshold value of light intensity; When δ1% <SOC≤δ2%、 U dc <γ1U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is less than the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop discharge control method is used to control the output power of the energy storage unit; if there is no load that needs to be charged, the photovoltaic charging unit charges the energy storage unit, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop charging control method is used to charge the energy storage unit; U dc represents the DC bus voltage, γ1 represents the threshold coefficient of the DC bus voltage, U N Indicates the nominal operating voltage of the DC bus; When δ1% <SOC≤δ2%、 γ1U N dc <γ2U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is equal to the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the energy storage unit is controlled to be in standby state; if there is no load that needs to be charged, the photovoltaic charging unit charges the energy storage unit, and the droop constant voltage control method is used to control the output power of the photovoltaic power generation unit, and the constant power charging rate control method is used to charge the energy storage unit; the linear bus voltage range is set to γ1U N ~γ2U N ;γ2 represents the threshold coefficient of DC bus voltage, γ1<γ2;​ When δ1% <SOC≤δ2%、 U dc >γ2U N If the external load needs to be charged, the output power of the photovoltaic power generation unit is greater than the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop charging control method is used to charge the energy storage unit; if there is no load that needs to be charged, the photovoltaic charging unit charges the energy storage unit, and the droop constant voltage control method is used to control the output power of the photovoltaic power generation unit, and the constant power charging rate control method is used to charge the energy storage unit; When SOC>δ2%, When the external load needs to be charged, the light intensity cannot make the photovoltaic power generation unit generate electricity normally, the photovoltaic power generation unit is controlled to be in standby state, and the output power of the energy storage unit is controlled by droop discharge control method; if there is no load that needs to be charged, the energy storage unit is fully charged and does not need to be charged, and the system ends operation; When SOC>δ2%, U dc <γ1U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is less than the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop discharge control method is used to control the output power of the energy storage unit; if there is no load that needs to be charged, the energy storage unit is fully charged and does not need to be charged, and the system ends operation; When SOC>δ2%, γ1U N dc <γ2U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is equal to the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the energy storage unit is controlled to be in standby state; if there is no load that needs to be charged, the energy storage unit is fully charged and does not need to be charged, and the system ends operation;​ When SOC>δ2%, U dc >γ2U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is greater than the charging power required by the load, and the output power of the photovoltaic power generation unit is controlled by the droop constant voltage control method. The energy storage unit is sufficiently charged and does not need to be charged, and the energy storage unit is controlled to be in standby state; if there is no load that needs to be charged, the energy storage unit is sufficiently charged and does not need to be charged, and the system ends operation; When SOC<δ1%, If the light intensity cannot make the photovoltaic power generation unit generate electricity normally, the energy storage unit and the load cannot be charged, and the system ends operation; When SOC<δ1%, U dc <γ1U N When the output power of the photovoltaic power generation unit is less than the charging power required by the load, the charge state of the energy storage system does not meet the discharge state, and the photovoltaic power generation unit is required to charge the energy storage unit. The MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop charging control method is used to charge the energy storage unit. When SOC≤δ1%, γ1U N dc <γ2U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is equal to the charging power required by the load, and the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the energy storage unit is controlled to be in standby state; if there is no load that needs to be charged, the photovoltaic power generation unit is required to charge the energy storage unit, and the droop constant voltage control method is used to control the output power of the photovoltaic power generation unit, and the constant power charging rate control method is used to charge the energy storage unit;​ When SOC≤δ1%, U dc >γ2U N When the external load needs to be charged, the output power of the photovoltaic power generation unit is greater than the charging power required by the load, the MPPT control method is used to control the output power of the photovoltaic power generation unit, and the droop charging control method is used to charge the energy storage unit; if there is no load that needs to be charged, the photovoltaic power generation unit is needed to charge the energy storage unit, the droop constant voltage control method is used to control the output power of the photovoltaic power generation unit, and the constant power charging rate control method is used to charge the energy storage unit.

2. The operation control method of an offshore floating photovoltaic storage integrated charging station system according to claim 1 is characterized in that: The droop constant voltage control method is specifically described as follows: adding voltage feedforward compensation control to the droop control, and adjusting the DC bus voltage U dc The expected value of bus voltage setting U * Compare and output compensation value ΔU through PI controller * , for U * The values ​​obtained by dynamic compensation are compared with r and i s The product of is subtracted and sent to the voltage and current dual loop control, and finally the corresponding PWM signal d is generated. pv , through d pv Control unidirectional DC / DC converter I; In the formula, k p and k i are the proportional adjustment coefficient and integral adjustment coefficient of the PI controller in the feedforward compensation controller respectively; i s It represents the inductor current output by the converter, and r is the droop coefficient.

3. The operation control method of an offshore floating photovoltaic storage integrated charging station system according to claim 1 is characterized in that: The droop charging control method and the droop discharging control method are specifically described as follows: dc with U * Compare and output compensation value ΔU through PI controller * , for U * The value obtained by dynamic compensation is compared with R(SOC) and i s The product of is subtracted and sent to the voltage and current dual loop control, and finally the corresponding PWM signal d is generated. b , through d pv Control bidirectional DC / DC converter; In the formula, k′ p , k′ i are the proportional adjustment coefficient and integral adjustment coefficient of the PI controller in the feedforward compensation controller, s is the complex variable of the PI transfer function; R(SOC) is the droop coefficient based on the energy storage SOC.

4. An offshore floating photovoltaic and storage integrated charging station system, implemented based on the operation control method of an offshore floating photovoltaic and storage integrated charging station system according to claim 1, characterized in that: It includes a triangular floating structure, a control unit, an energy storage unit, and a photovoltaic power generation unit. The floating structure is provided with an energy storage tank, the energy storage unit is installed in the energy storage tank, and the photovoltaic power generation unit is laid on the energy storage tank; The photovoltaic power generation unit is used to convert light energy into electrical energy; The energy storage unit is used to store excess electric energy generated by the photovoltaic power generation unit and to provide differential power when the power of the photovoltaic array power generation unit is less than the power required by the load; The control unit is used to control the energy storage unit according to the light intensity ill, the charge state SOC, the DC bus voltage U dc And the operating mode of the charging interface with or without a load control system.

5. The offshore floating photovoltaic and storage integrated charging station system according to claim 4 is characterized in that: The floating buoy structure is a triangular structure composed of four triangular buoys connected together, each triangular buoy is connected by a hinge; the three apex corners of the floating buoy structure are vertical cylindrical structures; the buoy includes a tubular shell and foam, and the foam is filled in a cavity covered by the shell.

6. The offshore floating photovoltaic and storage integrated charging station system according to claim 4 is characterized in that: The charging station system includes four parallel energy storage units and four parallel photovoltaic power generation units, each energy storage unit includes a number of batteries connected in series, and each photovoltaic power generation unit includes a number of photovoltaic cells connected in series and in parallel; the control unit is a controller.

7. The offshore floating photovoltaic and storage integrated charging station system according to claim 6 is characterized in that: The charging station system also includes a charging interface, a unidirectional DC / DC converter I, a unidirectional DC / DC converter II, and a bidirectional DC / DC converter; the input interface of the unidirectional DC / DC converter I is connected to the output interface of the photovoltaic power generation unit, the PWM interface of the unidirectional DC / DC converter I is connected to the control unit, the output interface of the unidirectional DC / DC converter I is connected to the DC bus, the input interface of the unidirectional DC / DC converter II is connected to the DC bus, the PWM interface of the unidirectional DC / DC converter II is connected to the control unit, the output interface of the unidirectional DC / DC converter II is connected to the charging interface, the input interface of the bidirectional DC / DC converter is connected to the energy storage unit, the PWM interface of the bidirectional DC / DC converter is connected to the control unit, and the output interface of the bidirectional DC / DC converter is connected to the DC bus.

8. The offshore floating photovoltaic and storage integrated charging station system according to claim 7 is characterized in that: The charging interface, the unidirectional DC / DC converter I, and the bidirectional DC / DC converter are integrated in three control boxes, and the control boxes are installed on the three top corners of the floating buoy structure.

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