CN112688353B - High-power direct current charging system - Google Patents
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Abstract
The invention discloses a high-power direct current charging system, which is suitable for an electric ship and comprises: the two direct current charging modules respectively comprise a self-adaptive detection control unit which is used for connecting the electric ship and obtaining a voltage detection value; the self-adaptive detection control unit is preset with at least one voltage threshold range and is adjusted through a voltage detection value; and the flexible grid-connected unit is also arranged and connected with the self-adaptive detection control unit, and the working state of the energy exchange between the direct current bus and the external alternating current power grid and the working state of the direct current charging module are adjusted according to the comparison result of the actual voltage of the direct current bus and the voltage threshold range at the current moment. Has the advantages that: the source-network-load interaction capacity is improved by mixing and connecting the phase-shifting rectification conversion device and the flexible grid-connected bidirectional device in parallel, and meanwhile, the system can still stably and reliably operate under the condition of local faults by adopting a multi-section direct current bus connection mode and matching the flexible grid-connected bidirectional device.
Description
Technical Field
The invention relates to the field of high-power charging, in particular to a high-power direct-current charging system.
Background
At present, electric ships are widely accepted by the market because of the characteristics that the discharge of ship pollutant gas can be greatly reduced and even zero discharge can be realized. With the continuous improvement of international ship emission regulations and the continuous maturity of ship power batteries and hybrid power technologies, the acceptance of the electric ship market is also continuously improved, and the electric ship becomes the key point for the development of the ship industry in the future. Besides reducing the emission, the running cost of the electric ship is obviously lower than that of a diesel oil and LNG fuel ship, the structure of the electric ship is simple, the number of rotating parts is small, and meanwhile, the maintenance cost is also reduced.
In the prior art, because new energy such as photovoltaic energy, wind power and the like has the characteristics of intermittence and instability in power generation, a new energy power generation system has serious impact on safe operation, and has obvious influence on power grid scheduling and system safe operation, the high-power direct-current charging technology can externally provide various power sources and load interfaces, a distributed power source, an energy storage system and a direct-current load can be connected into a power grid, the energy form conversion link is reduced, and the direct-current system is easier to be connected into an alternating-current power grid system, so that the high-power direct-current charging technology is a development trend of a future power distribution network.
Disclosure of Invention
According to the problems in the prior art, a high-power direct-current charging system is provided, so that the power quality of a grid side is optimized and improved while the stability of a direct-current bus is ensured, and the system can still run stably and reliably under the condition of local faults.
The technical scheme specifically comprises the following steps: a high-power direct-current charging system is suitable for an electric ship and comprises: the two direct current charging modules are respectively provided with a charging interface and are used for charging the electric ship through the charging interfaces; each direct current charging module is respectively provided with a self-adaptive detection control unit; the self-adaptive detection control unit is connected with the electric ship, acquires an electric characteristic value of the electric ship and obtains a voltage detection value; at least one voltage threshold range is preset in the self-adaptive detection control unit, and each voltage threshold range is adjusted through the voltage detection value; each direct current charging module is provided with a flexible grid-connected unit, and the flexible grid-connected unit is arranged between an external alternating current power grid and a direct current bus connected with the direct current charging module; the flexible grid-connected unit is connected with the self-adaptive detection control unit, and adjusts the working state of energy exchange between the direct current bus and the external alternating current power grid and adjusts the working state of the corresponding direct current charging module according to the comparison result of the real-time voltage of the direct current bus detected in real time and the voltage threshold range at the current moment.
Preferably, each of the dc charging modules further includes: the voltage transformation unit is used for carrying out voltage reduction processing on the voltage of a high-voltage alternating current bus in the external alternating current power grid and then inputting the voltage into a low-voltage alternating current bus; the phase-shifting rectifying unit is connected to the low-voltage alternating current bus and is used for converting the voltage of the low-voltage alternating current bus and inputting the converted voltage to the direct current bus; a reactive compensation unit connected to the low-voltage alternating current bus and used for compensating reactive current of the low-voltage alternating current bus; the charging units are respectively connected between the direct current bus and the charging interface and used for charging the electric ship through the charging interface; the energy storage unit is connected to the direct current bus, is preset with an upper energy storage limit and a lower energy storage limit and is used for storing the energy of the direct current bus; the power generation unit is connected to the direct current bus and used for generating photovoltaic energy and outputting the photovoltaic energy to the direct current bus; and the super capacitor unit is connected to the direct current bus and used for stabilizing the voltage of the direct current bus.
Preferably, the flexible grid connection unit includes: the acquisition component is used for acquiring the current voltage threshold range in the self-adaptive detection control unit in real time; the detection component is connected with the acquisition component and is used for detecting the real-time voltage on the direct current bus, comparing the detected real-time voltage with the currently acquired voltage threshold range and outputting the comparison result; and the control component is connected with the detection component and generates a corresponding control instruction according to the comparison result, and the control component adjusts the working state of energy exchange between the direct current bus and the external alternating current power grid and adjusts the working state of the corresponding direct current charging module according to the control instruction.
Preferably, the adaptive detection control unit includes: a first identification acquisition means for acquiring an electric ship voltage, an electric ship power, and an electric ship charging capacity of the electric ship and including them in the electric characteristic value; the first calculation part is connected with the first identification acquisition part and used for calculating the voltage detection value according to the electrical characteristic value; the adjusting component is connected with the first calculating component, is preset with a plurality of voltage threshold value ranges and respectively adjusts each voltage threshold value range in real time according to the voltage detection value; the plurality of voltage threshold ranges respectively include: when the real-time voltage of the direct current bus is within the first voltage threshold range, the direct current charging module is in an overvoltage fault state, and at the moment, the corresponding control instruction controls the direct current charging module to stop working and outputs overvoltage warning information; when the real-time voltage of the direct current bus is within the second voltage threshold range, the corresponding control instruction controls the power generation unit to stop working at the moment; when the real-time voltage of the direct current bus is within the third voltage threshold range, the corresponding control instruction is to preferentially control the energy storage unit to perform charging operation and then start the flexible grid-connected unit to transmit the energy of the direct current bus to the low-voltage alternating current bus; when the real-time voltage of the direct current bus is within the fourth voltage threshold range, the corresponding control instruction controls the power generation unit to generate power; when the real-time voltage of the direct-current bus is within the fifth voltage threshold range, the corresponding control instruction is to start the flexible grid-connected unit to transmit the energy of the low-voltage alternating-current bus to the direct-current bus; when the real-time voltage of the direct current bus is within the sixth voltage threshold range, the corresponding control instruction controls the energy storage unit to perform discharge work at the moment; and when the real-time voltage of the direct current bus is within the seventh voltage threshold range, the direct current charging module is in an undervoltage fault state, and at the moment, the corresponding control instruction controls the direct current charging module to stop working and output undervoltage alarm information.
Preferably, the first calculation means calculates the voltage detection value by the following formula:
wherein,
us is the voltage detection value;
w0 is the electric marine power;
e0 is the electric ship charging capacity;
a is a correction factor associated with the voltage on the DC bus;
mt is a power change coefficient of the electric ship changing with time in a charging state.
Preferably, the adjusting means adjusts each of the voltage threshold ranges by the following formula:
wherein,
w0 is the electric marine power;
d is a voltage threshold correction coefficient;
nw is a power variation correction coefficient;
us is the voltage detection value;
u1 is the first voltage threshold range;
u2 is the second voltage threshold range;
u3 is the third voltage threshold range;
u41 is the upper limit of the fourth voltage threshold range;
u42 is the lower limit of the fourth voltage threshold range;
u5 is the fifth voltage threshold range;
u6 is the sixth voltage threshold range;
u7 is the seventh voltage threshold range.
Preferably, each of the dc charging modules further includes: the voltage stabilization control unit is connected between the direct current bus and the electric ship, is respectively connected with the charging unit and the super capacitor unit, and is used for controlling the output voltage and the output power of the charging unit and the super capacitor unit; the voltage stabilization control unit further includes: a second identification acquisition unit that acquires an electric ship voltage and an electric ship power of the electric ship; the second calculating component is connected with the second identification and acquisition component and used for calculating and outputting a first output voltage according to the voltage of the electric ship; the third calculating component is connected with the second identification and acquisition component and used for calculating and outputting a second output voltage according to the voltage detection value; the fourth calculating component is connected with the second identification and acquisition component and used for calculating and outputting first output power according to the power of the electric ship; a first voltage stabilization control unit, respectively connected to the second calculation unit, the third calculation unit and the fourth calculation unit, for: generating a first control instruction according to the first output voltage and sending the first control instruction to the charging unit so as to use the first output voltage as the charging output voltage of the charging unit; generating a second control instruction according to the second output voltage and sending the second control instruction to the super capacitor unit so as to use the second output voltage as the output voltage of the super capacitor unit; and generating a third control instruction according to the first output power and sending the third control instruction to the super capacitor unit so as to use the first output power as the output power of the super capacitor unit.
Preferably, the second calculation means calculates the first output voltage by the following equation:
wherein,
u0 is the electric watercraft voltage;
Δ U is a supplemental voltage;
uz is the first output voltage.
Preferably, the third calculating means calculates the second output voltage by the following formula:
wherein,
us is the voltage detection value;
uc is the second output voltage.
Preferably, the fourth calculating means calculates the first output power by the following equation:
wherein,
w0 is the electric marine power;
b is a correction factor associated with the output voltage of the super capacitor;
wc is the first output power.
Preferably, the two dc charging modules are a first dc charging module and a second dc charging module respectively; the first direct current charging module and the second direct current charging module exchange energy through a direct current communication module; the direct current communication module is specifically provided with: the first detection unit is connected with the first direct current charging module and used for detecting the real-time running state of the first direct current charging module and the real-time voltage of the first direct current charging module and outputting first detection data; the second detection unit is connected with the second direct current charging module and used for detecting the real-time running state of the second direct current charging module and the real-time voltage of the second direct current charging module and outputting second detection data; and the control unit is respectively connected with the first detection unit and the second detection unit and is used for controlling the connection or disconnection of the direct current connection module according to the first detection data and the second detection data so as to stabilize the voltage of the direct current bus.
Preferably, the control unit specifically includes: a third identification acquisition means that acquires the first detection data; a fourth identification acquisition section that acquires the second detection data; the fifth calculation component is prestored with standard operation data of the first direct current charging module, connected with the third identification acquisition component and used for comparing and calculating the first operation state data according to the first detection data and the standard operation data of the first direct current charging module to obtain and output the first operation state data; the sixth calculation component is prestored with standard operation data of a second direct current charging module, connected with the fourth identification acquisition component and used for comparing and calculating the second operation state data according to the second detection data and the standard operation data of the second direct current charging module to obtain and output second operation state data; and the second voltage stabilization control part is respectively connected with the fifth calculation part and the sixth calculation part and is used for generating a corresponding fourth control instruction according to the first operation state data and the second operation state data so as to connect or disconnect the direct current communication module.
The technical scheme of the invention has the beneficial effects that: according to the technical scheme, a high-reliability multi-pulse-wave rectification technology is adopted, the stability of the direct current bus is guaranteed, the quality of grid-side electric energy is optimized and improved, the source-grid-load interaction capacity is improved by mixing and connecting the phase-shifting rectification conversion device and the flexible grid-connected bidirectional device in parallel, and the system can still run stably and reliably under the condition of local faults by adopting a multi-section direct current bus connection mode and matching the flexible grid-connected bidirectional device.
Drawings
Embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings. The drawings are, however, to be regarded as illustrative and explanatory only and not as restrictive of the scope of the invention.
Fig. 1 is a schematic diagram of a specific circuit implementation structure of a high-power dc charging system according to an embodiment of the present invention;
fig. 2 is a structural composition diagram of a dc charging module of the high-power dc charging system according to the embodiment of the present invention;
fig. 3 is a structural composition diagram of a flexible grid-connected unit of the dc charging module according to the embodiment of the present invention;
fig. 4 is a structural composition diagram of an adaptive detection control unit of the dc charging module according to the embodiment of the present invention;
FIG. 5 is a diagram illustrating the relationship between seven voltage regions of the determining unit according to the embodiment of the present invention;
fig. 6 is a structural assembly diagram of a voltage stabilization control unit of the dc charging module according to the embodiment of the present invention;
fig. 7 is a structural composition diagram of a dc link module of the high power dc charging system according to the embodiment of the present invention;
FIG. 8 is a structural diagram of a control unit of the DC link module according to the embodiment of the present invention;
FIG. 9 is a flow chart of a high voltage charging method of the high power DC charging method according to the embodiment of the present invention;
FIG. 10 is a flow chart of a low voltage charging method of the high power DC charging method according to the embodiment of the present invention;
fig. 11 is a flowchart of a multi-bus charging method of the high-power dc charging method according to the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.
The invention provides a high-power direct current charging system, which is suitable for an electric ship, and as shown in figure 1, the high-power direct current charging system comprises: the two direct current charging modules 1 are respectively provided with a charging interface, and the electric ship 3 is charged through the charging interfaces; each direct current charging module 1 is provided with a self-adaptive detection control unit 18; the self-adaptive detection control unit 18 is connected with the electric ship 3, acquires an electric characteristic value of the electric ship 3, and obtains a voltage detection value Us; the self-adaptive detection control unit 18 is preset with at least one voltage threshold range, and adjusts each voltage threshold range respectively through a voltage detection value Us; each direct current charging module 1 is respectively provided with a flexible grid-connected unit 14, and the flexible grid-connected unit 14 is arranged between an external alternating current power grid L1 and a direct current bus L3 connected with the direct current charging module 1; the flexible grid-connected unit 14 is connected to the adaptive detection control unit 18, and adjusts the working state of the energy exchange between the dc bus L3 and the external ac power grid L1 and the working state of the corresponding dc charging module 1 according to the comparison result between the real-time voltage Ua of the dc bus detected in real time and the voltage threshold range at the current time.
Specifically, two direct current charging modules 1 are provided with a plurality of high-power charging piles to charge the electric ship 3 needing to be charged through the direct current charging line L4 connected with the high-power charging piles, the self-adaptive detection control unit 18 can detect in real time to obtain the electric characteristic value of the electric ship 3, the electric characteristic value comprises an electric ship voltage U0, an electric ship power W0 and an electric ship charging capacity E0, and meanwhile, the voltage detection value Us of the high-power direct current charging system is calculated according to different grades of the electric ship voltage U0, the electric ship power W0 and the electric ship charging capacity E0.
Specifically, the flexible grid-connected unit 144 is a 300KVA flexible grid-connected bidirectional device, and has a main function of adjusting a voltage threshold range of the high-power dc charging system by detecting a dc bus voltage detection value Us through the adaptive detection control unit 18, adjusting a working state of energy exchange between the dc bus L3 and the external ac power grid L1 and adjusting a working state of the corresponding dc charging module 1 according to a specific voltage threshold range of the dc bus real-time voltage Ua at the current time, and supporting the dc bus L3 to adjust energy flow of the high-power dc charging system, so that the dc bus L3 voltage is balanced with system energy.
In a preferred embodiment, as shown in fig. 2, the dc charging module 2 is specifically provided with: the voltage transformation unit 11 is used for performing voltage reduction processing on the voltage of a high-voltage alternating-current bus in an external alternating-current power grid L1 and inputting the voltage into a low-voltage alternating-current bus L2; the phase-shifting rectifying unit 12 is connected to the low-voltage alternating-current bus L2 and is used for converting the voltage of the low-voltage alternating-current bus L2 and inputting the converted voltage to the direct-current bus L3; a reactive compensation unit 13 connected to the low-voltage ac bus 12 for compensating the reactive current of the low-voltage ac bus L2; a plurality of charging units 15 respectively connected between the dc bus L3 and the charging interface, for charging the electric ship 3 through the charging interface; the energy storage unit 16 is connected to the direct current bus L3, preset with an upper energy storage limit and a lower energy storage limit and used for storing energy of the direct current bus L3; the power generation unit 17 is connected to the direct current bus L3 and used for generating photovoltaic energy and outputting the photovoltaic energy to the direct current bus L3; and the super capacitor unit 19 is connected to the direct current bus L3 and is used for stabilizing the voltage of the direct current bus L3.
Specifically, the voltage transformation unit 11 is a 1WM isolation transformer.
Specifically, the phase shift rectifying unit 12 is a 1MW phase shift rectifying device, and provides a stable dc bus voltage for a dc charging system of the electric ship and power supply energy for a dc load.
Specifically, the reactive compensation unit 13 is a reactive harmonic hybrid compensation device.
Specifically, the charging unit 15 is a 300KW group control dc charger.
In particular, the energy storage unit 16 is a 200KW energy storage system.
Specifically, the power generation unit 17 is a 50KW photovoltaic power generation system.
Specifically, the supercapacitor unit 19 is a supercapacitor of 20 kvar.
Further, the transforming unit 11 step-down-processes the 10kV ac bus L1 in the external grid to the 400V low-voltage ac bus L2.
Further, the phase shift rectifying unit 12 converts a low-voltage ac bus L2 of 400VAC by uncontrolled rectification and inputs the converted low-voltage ac bus L2 to a dc bus L3 of 750V.
Further, the reactive power compensation unit 13 is connected with a low-voltage alternating current bus L2, so that harmonic content management is realized.
Further, the three charging units 15 are connected to the dc bus L3 and the dc charging line L4, so as to charge the electric ship 3.
Further, the energy storage unit 16 is connected to the dc bus L3, so as to store energy in the dc bus L3.
Further, the power generation unit 17 is connected to the dc bus L3, and outputs the photovoltaic energy generated by the photovoltaic module to the dc bus L3.
Furthermore, the super capacitor unit 19 is connected to the dc bus L3, and especially plays a role in stabilizing voltage when the flexible grid connection unit 14 controls the dc charging module 1 to perform charging and discharging.
In a preferred embodiment, as shown in fig. 3, the flexible grid tie unit 14 includes: an acquiring unit 141, configured to acquire the current voltage threshold range in the adaptive detection control unit 18 in real time; the detection part 142 is connected with the acquisition part 141 and is used for detecting the real-time voltage Ua on the direct current bus, comparing the detected real-time voltage Ua with the currently acquired voltage threshold range and outputting a comparison result; and the control component 143 is connected to the detection component 142, generates a corresponding control instruction according to the comparison result, and adjusts the working state of the energy exchange between the dc bus L3 and the external ac power grid L1 and the working state of the corresponding dc charging module 1 according to the control instruction.
Specifically, the flexible grid-connected unit 14 detects the real-time voltage Ua on the dc bus through the detection component 142 according to the voltage threshold range of the current high-power dc charging system acquired by the acquisition component 141, and compares the real-time voltage Ua with the voltage threshold range, and the output comparison result is output to the control component 143, the control component 143 further generates a corresponding control instruction according to the comparison result, and according to the corresponding control instruction, the flexible grid-connected unit 14 can control the working states of the relevant energy transmission units, such as the charging unit 15, the energy storage unit 16, and the power generation unit 17, in the dc charging module 1.
In a preferred embodiment, as shown in fig. 4, the adaptive detection control unit 18 includes: a first identification acquisition means 188 for acquiring the electric ship voltage U0, the electric ship power W0, and the electric ship charging capacity E0 of the electric ship 3 and including them in the electric characteristic values; a first calculating section 189, connected to the first identification acquiring section 188, for calculating a voltage detection value Us based on the electrical characteristic value; an adjusting component 190 connected to the first calculating component 189, wherein the adjusting component 190 is preset with a plurality of voltage threshold ranges, and adjusts each voltage threshold range in real time according to the voltage detection value Us; the plurality of voltage threshold ranges respectively include: when the real-time voltage Ua of the direct current bus is within the first voltage threshold range U1, the first voltage threshold range U1 indicates that the direct current charging module 1 is in an overvoltage fault state, and at this time, the corresponding control instruction is to control the direct current charging module 1 to stop working and output an overvoltage warning message; a second voltage threshold range U2, when the real-time voltage Ua of the dc bus is within the second voltage threshold range U2, the corresponding control command is to control the power generation unit 17 to stop working at this time; when the real-time voltage Ua of the direct-current bus is within the third voltage threshold range U3, the corresponding control instruction is to preferentially control the energy storage unit 16 to perform charging operation and then start the flexible grid-connected unit 14 to transmit the energy of the direct-current bus L3 to the low-voltage alternating-current bus L2; a fourth voltage threshold range U4, when the real-time voltage Ua of the dc bus is within the fourth voltage threshold range U4, the corresponding control command is to control the power generation unit 17 to perform power generation operation; a fifth voltage threshold range U5, when the real-time voltage Ua of the dc bus is within the fifth voltage threshold range U5, the corresponding control command is to start the flexible grid connection unit 14 to transmit the energy of the low-voltage ac bus L2 to the dc bus L3; a sixth voltage threshold range U6, when the real-time voltage Ua of the dc bus is within the sixth voltage threshold range U6, the corresponding control command is to control the energy storage unit 16 to perform discharging operation; and a seventh voltage threshold range U7, wherein when the real-time voltage Ua of the dc bus is within the seventh voltage threshold range U7, it indicates that the dc charging module 1 is in an under-voltage fault state, and at this time, the corresponding control instruction is to control the dc charging module 1 to stop working and output an under-voltage alarm message.
Specifically, the first identification acquisition unit 188 acquires the level data of the electric ship voltage U0, the electric ship power W0, and the electric ship charging capacity E0 of the electric ship 3 to be connected, and transmits the acquired relevant data to the first calculation unit 189 together with the electric characteristic values, and the first calculation unit 189 calculates the voltage detection value Us and transmits the voltage detection value Us to the adjustment unit 190.
Specifically, the adjusting unit 190 presets 7 voltage threshold ranges, each voltage threshold range corresponds to a voltage threshold, and the adaptive detection control unit 18 adaptively adjusts and controls each voltage threshold range according to the voltage detection value Us.
Specifically, the voltage threshold range of the first voltage zone 181 is a first voltage threshold range U1, the voltage threshold range of the second voltage zone 182 is a second voltage threshold range U2, the voltage threshold range of the third voltage zone 183 is a third voltage threshold range U3, the voltage threshold range of the fourth voltage zone 184 is a fourth voltage threshold range U4, the voltage threshold range of the fifth voltage zone 185 is a fifth voltage threshold range U5, the voltage threshold range of the sixth voltage zone 186 is a sixth voltage threshold range U6, and the voltage threshold range of the seventh voltage zone 187 is a seventh voltage threshold range U7.
Specifically, as shown in fig. 5, the voltages of the first voltage zone 181 to the seventh voltage zone 187 are gradually decreased, and in the technical scheme, a multi-voltage interval sectional control strategy based on dc voltage rinse compensation is adopted, and the phase-shift rectification unit 12 is used to keep the dc bus L3 stable, so as to ensure that the actual voltage of the dc bus L3 is in the fourth voltage zone, which is a voltage stabilization zone. The first voltage region 181 is an overvoltage fault region, the second voltage region 182 is a second region with a higher voltage, the third voltage region 183 is a first region with a higher voltage, the fifth voltage region 185 is a first region with a lower voltage, the sixth voltage region 186 is a second region with a lower voltage, and the seventh voltage region 187 is an undervoltage fault region.
Specifically, when the flexible grid-connected unit 14 detects that the energy storage unit 16 reaches the energy storage upper limit and detects that the actual voltage Ua of the dc bus L3 continuously rises to be within the first voltage threshold range U1, the flexible grid-connected unit 14 controls the dc charging module 1 to stop working, and outputs an overvoltage warning message to prompt an administrator to check; similarly, when the flexible grid-connected unit 14 detects that the energy storage unit 16 reaches the energy storage lower limit and detects that the actual voltage Ua of the dc bus L3 continuously decreases to be within the seventh voltage threshold range U7, the flexible grid-connected unit 14 controls the dc charging module 1 to stop working, and outputs an under-voltage alarm message to prompt the administrator to perform an inspection.
Specifically, based on the technical solution described in this embodiment, the method includes a high-power dc charging method, and when the actual voltage Ua of the dc bus L3 is larger, the method is a high-voltage charging method, as shown in fig. 9, and specifically includes: step S1A: the detection part 141 detects whether the actual voltage Ua of the direct current bus L3 is in the fourth voltage zone 184; if yes, go to step S5A; if not, go to step S2A; step S2A: the detection section 141 detects whether the actual voltage Ua of the direct current bus L3 is in the third voltage zone 183; if yes, go to step S3A; if not, go to step S4A; step S3A: the detection section 141 detects whether the energy storage unit 16 reaches the upper energy storage limit; if yes, the control component 142 controls the flexible grid-connected unit 14 to start, the flexible grid-connected unit 14 transmits the energy of the direct current bus L3 to the low-voltage alternating current bus L2 to reduce the actual voltage Ua of the direct current bus L3, and step S1A is performed; if not, the control component 142 controls the flexible grid-connected unit 14 to start, the flexible grid-connected unit 14 transmits the energy of the direct current bus L3 to the energy storage unit 16 to reduce the actual voltage Ua of the direct current bus L3, and the step S1A is performed; step S4A: the detection part 141 detects whether the actual voltage Ua of the direct current bus L3 is in the second voltage region 182; if so, the control unit 142 controls the power generation unit 17 to stop operating, and proceeds to step S1A; if not, the control component 142 controls the direct current charging module 1 to stop working, and outputs overvoltage warning information to prompt a manager to check; step S5A: the detection section 141 detects whether the power generation unit 17 is started; if yes, the direct current charging module 1 enters normal operation; if not, the control part 142 controls the power generation unit 17 to start.
Specifically, when the actual voltage Ua of the dc bus L3 is smaller, the method is a high-low voltage charging method, as shown in fig. 10, and specifically includes: step S1B: the detection part 141 detects whether the actual voltage Ua of the direct current bus L3 is in the fourth voltage zone 184; if yes, go to step S5B; if not, go to step S2B; step S2B: the detection part 141 detects whether the actual voltage Ua of the direct current bus L3 is in the fifth voltage zone 185; if yes, the control component 142 controls the flexible grid-connected unit 14 to start, the flexible grid-connected unit 14 transmits the energy of the low-voltage alternating-current bus L2 to the direct-current bus L3 to increase the actual voltage Ua of the direct-current bus L3, and step S1B is performed; if not, go to step S3B; step S3B: the detection part 141 detects whether the energy storage unit 16 reaches the energy storage lower limit; if yes, the control unit 142 controls the dc charging module 1 to stop working, and outputs an under-voltage alarm message to prompt the administrator to perform inspection; if not, go to step S4B; step S4B: the detection part 141 detects whether the actual voltage Ua of the direct current bus L3 is in the sixth voltage zone 186; if yes, the control component 142 controls the flexible grid-connected unit 14 to start, the flexible grid-connected unit 14 transmits the energy of the energy storage unit 16 to the direct-current bus L3 to increase the actual voltage Ua of the direct-current bus L3, and the step S1B is performed; if not, the control unit 142 controls the direct current charging module 1 to stop working, and outputs the under-voltage alarm information to prompt the administrator to check; step S5B: the detection section 141 detects whether the power generation unit 17 is started; if yes, the direct current charging module 1 enters normal operation; if not, the control part 142 controls the power generation unit 17 to start.
Specifically, the above steps are performed by default when the power generation unit 17 is started.
Specifically, the power generation unit 17 outputs the electric energy to the dc bus L3, and is preferentially used by the three charging units 15 to supply power to the electric ship 3, and the excess energy is stored in the energy storage unit 16, so as to prevent the electric energy of the power generation unit 17 from reaching the charging unit 15 through the energy storage unit 16, and reduce the repeated operation of the energy storage unit 16.
Specifically, the charging unit 15 inputs energy into the battery of the electric ship 3.
In a preferred embodiment, the first calculation section calculates the voltage detection value by the following equation:
wherein,
us is a voltage detection value;
w0 is electric ship power;
e0 is electric ship charging capacity;
a is a correction factor associated with the voltage on the DC bus;
mt is a power change coefficient of the electric ship changing with time in a charging state.
Specifically, the variation range of the power variation coefficient Mt of the electric ship, which varies with time in a charging state, is 0.1-1; the variation amplitude of a correction coefficient A related to the voltage on the direct current bus is between 1 and 3; the variation range of the charging capacity E0 of the electric ship is 0.1-1.
In a preferred embodiment, the adjusting means adjusts each voltage threshold range separately by the following formula:
wherein,
w0 is electric ship power;
d is a voltage threshold correction coefficient;
nw is a power variation correction coefficient;
us is a voltage detection value;
u1 is a first voltage threshold range;
u2 is a second voltage threshold range;
u3 is a third voltage threshold range;
u41 is the upper limit of the fourth voltage threshold range;
u42 is the lower limit of the fourth voltage threshold range;
u5 is a fifth voltage threshold range;
u6 is a sixth voltage threshold range;
u7 is a seventh voltage threshold range.
Specifically, a power change correction coefficient Nw is generated by the electric ship power W0 according to the voltage threshold correction coefficient D, and each specific voltage threshold range is obtained according to the voltage detection value Us and the corresponding fixed coefficient, and further, each voltage threshold range is adjusted to change according to the electric ship power W0 change and the corresponding voltage threshold correction coefficient D.
In a preferred embodiment, as shown in fig. 6, each dc charging module 1 further includes: the voltage stabilizing control unit 20 is connected between the direct current bus L3 and the electric ship 3, is respectively connected with the charging unit 15 and the super capacitor unit 19, and is used for controlling the output voltage and the output power of the charging unit 15 and the super capacitor unit 19; the voltage stabilization control unit 20 further includes: a second identification acquisition unit 201, wherein the second identification acquisition unit 201 acquires the electric ship voltage U0 of the electric ship 3 and the electric ship power W0; the second calculating component 202 is connected with the second identification acquiring component 201 and used for calculating and outputting a first output voltage Uz according to the voltage U0 of the electric ship; a third calculating component 203, connected to the second identification acquiring component 201, for calculating and outputting a second output voltage Uc according to the voltage detection value Us; the fourth calculating component 204 is connected with the second identification acquiring component 201 and used for calculating and outputting a first output power Wc according to the electric ship power W0; a first voltage stabilization control unit 205, connected to the second calculating unit 202, the third calculating unit 203 and the fourth calculating unit 204, respectively, for: generating a first control command according to the first output voltage Uz and sending the first control command to the charging unit 15, so as to use the first output voltage Uz as the charging output voltage of the charging unit 15; generating a second control instruction according to the second output voltage Uc and sending the second control instruction to the super capacitor unit 15, so as to use the second output voltage Uc as the output voltage of the super capacitor unit 19; and generating a third control command according to the first output power Wc and sending the third control command to the super capacitor unit 19, so as to use the first output power Wc as the output power of the super capacitor unit 19.
Specifically, the voltage regulation control unit 20 acquires the electric ship voltage U0 of the electric ship 3 and the electric ship power W0 through the second identification acquisition unit 201, the electric ship voltage U0 generates the first output voltage Uz through the second calculation unit 202, the voltage detection value Us generates the second output voltage Uc through the third calculation unit 203, the electric ship power W0 generates the first output power Wc through the fourth calculation unit 204, and the first voltage regulation control unit 205 transmits the first output voltage Uz to the charging unit 15 as the charging output voltage of the charging unit 15 and the second output voltage Uc and the first output power Wc to the supercapacitor unit 19 as the output voltage and the output power of the supercapacitor unit 19, respectively.
In a preferred embodiment, the second calculation means calculates the first output voltage by the following formula:
wherein,
u0 is electric ship voltage;
Δ U is a supplemental voltage;
uz is the first output voltage.
Specifically, the change range of the supplementary voltage delta U is between 5V and 10V.
In a preferred embodiment, the third calculating means calculates the second output voltage by the following equation:
wherein,
us is a voltage detection value;
uc is the second output voltage.
Specifically, the second output voltage Uc serving as the output voltage of the super capacitor can ensure that the voltage on the dc bus L3 in the high-power dc charging system is stable, and ensure the consistency of the voltage detection value Us and the output voltage Uc of the super capacitor.
In a preferred embodiment, the fourth calculating means calculates the first output power by the following equation:
wherein,
w0 is electric ship power;
b is a correction coefficient associated with the output voltage of the super capacitor;
wc is the first output power.
Specifically, the variation range of the correction coefficient B related to the output voltage of the super capacitor is between 1 and 2.
In a preferred embodiment, as shown in fig. 1, two dc charging modules 1 are a first dc charging module a1 and a second dc charging module a 2; the first direct current charging module A1 and the second direct current charging module A2 exchange energy through a direct current communication module 2; as shown in fig. 7, the dc link module 2 specifically includes: a first detecting unit 21 connected to the first dc charging module a1 for detecting a real-time operating state a1_ state of the first dc charging module a1 and a real-time voltage of the first dc charging module a1
And outputting a first detection data; a second detecting unit 22 connected to the second dc charging module a2 for detecting the second dc charging module a2 real-time operating state a2_ state and real-time voltage of the second dc charging module a2
And outputting a second detection data; and the control unit 23 is connected with the first detection unit 21 and the second detection unit 22 respectively, and is used for controlling the connection or disconnection of the direct current communication module according to the first detection data and the second detection data so as to stabilize the voltage of the direct current bus.
Specifically, the first dc charging module a1 and the second dc charging module a2 both include a voltage transformation unit 11, a phase-shift rectification unit 12, a reactive compensation unit 13, a flexible grid connection unit 14, a charging unit 15, an energy storage unit 16, a power generation unit 17, an adaptive detection control unit 18, a super capacitor unit 19, and a voltage stabilization control unit 20.
In a preferred embodiment, as shown in fig. 8, the control unit 23 specifically includes: a third recognition acquisition section 231, the third recognition acquisition section 231 acquiring the first detection data; a fourth recognition acquisition section 232, the fourth recognition acquisition section 232 acquiring the second detection data; a fifth calculating component 233, pre-storing standard operation data of a first dc charging module a1, connected to the third identification obtaining component 231, for comparing and calculating to obtain and output a first operation status data according to the first detection data and the standard operation data of the first dc charging module a 1; a sixth calculating component 234, pre-storing standard operation data of a second dc charging module a2, connected to the fourth identification acquiring component 232, for comparing and calculating to obtain and output a second operation status data according to the second detection data and the standard operation data of the second dc charging module a 2; and the second voltage stabilization control part 235 is respectively connected with the fifth calculating part 233 and the sixth calculating part 234 and is used for correspondingly generating a fourth control instruction according to the first operating state data and the second operating state data so as to connect or disconnect the direct current communication module.
Specifically, the fourth control instruction is a connection instruction or a disconnection instruction.
Specifically, the first detection data includes a first DC charging modeThe real-time operating state value a1_ state of the block a1 and the real-time voltage of the dc bus L3 of the first dc charging module a1
The value is obtained.
Specifically, the standard operation data preset by the first dc charging module a1 includes a high voltage threshold of the first dc charging module a1, a low voltage threshold of the first dc charging module a1, and a standard operation value of the first dc charging module a 1.
Specifically, the second detection data includes the real-time operating status value a2_ state of the second dc charging module a2 and the real-time voltage of the dc bus L3 of the first dc charging module a2
The value is obtained.
Specifically, the standard operation data preset by the second dc charging module a2 includes a high voltage threshold of the second dc charging module a2, a low voltage threshold of the second dc charging module a2, and a standard operation value of the second dc charging module a 2.
Specifically, the high voltage threshold of the first dc charging module a1 is generally preset to be 600V, and the low voltage threshold is generally preset to be 100V; the second dc charging module a2 has a high voltage threshold of 600V and a low voltage threshold of 100V.
Specifically, the standard operating value of the first dc charging module a1 is generally preset to be 1 or 0, where 1 indicates the standard operating state Normal, and 0 indicates the non-standard operating state Error.
Specifically, based on the technical solution described in this embodiment, the method includes a multi-bus high-power dc charging method, as shown in fig. 11, specifically including: step S1C: the first detecting unit 21 detects the real-time operating state a1_ state of the first dc charging module a1 and the real-time voltage Ua of the second dc charging module a1 respectively1And the second detecting unit 22 detects the real-time operating state a2_ state of the second dc charging module a2 and the real-time voltage Ua of the second dc charging module a2, respectively2(ii) a Step S2C: the real-time operation state of the first dc charging module a1 is the Normal operation state, and the first dc charging module isReal-time voltage Ua of block a11Greater than or equal to the high voltage threshold, and the real-time operating state of the second dc charging module a2 is the Normal operating state, and the real-time voltage Ua of the second dc charging module a22Greater than or equal to a high voltage threshold;
if yes, the control unit 23 controls the dc link module 2 to disconnect, so that the first dc charging module a1 and the second dc charging module a2 are not connected; if not, go to step S3C; step S3C: the real-time operation state of the second dc charging module a2 is the non-standard operation state Error, and the real-time voltage Ua of the second dc charging module a22Less than or equal to the low voltage threshold, and the real-time operating state of the first dc charging module a1 is the Normal operating state; if yes, the control unit 23 controls the dc link module 2 to close, so that the first dc charging module a1 transmits energy to the second dc charging module a 2; if not, go to step S4C; step S4C: the real-time operation state of the first dc charging module a1 is the non-standard operation state Error, and the real-time voltage Ua of the first dc charging module a11The real-time operation state of the second direct current charging module A2 is a standard operation state Normal; if yes, the control unit 23 controls the dc link module 2 to close, so that the second dc charging module a2 transmits energy to the first dc charging module a 1; if not, step S1C is performed.
In summary, the technical scheme adopts two direct current charging modules to charge the electric ship; each direct current charging module is respectively provided with a flexible grid-connected unit which is used for exchanging energy between an external alternating current power grid and a direct current bus of the direct current charging module; each direct current charging module comprises a self-adaptive detection control unit which is used for being connected with the electric ship and obtaining a voltage detection value; the self-adaptive detection control unit is preset with at least one voltage threshold range, and adjusts each voltage threshold range respectively through the voltage detection value; the flexible grid-connected unit is connected with the self-adaptive detection control unit, and adjusts the working state of energy exchange between the direct current bus and an external alternating current power grid and adjusts the working state of a corresponding direct current charging module according to the comparison result of the actual voltage of the direct current bus detected in real time and the voltage threshold range at the current moment. The technical scheme has the advantages that the high-reliability multi-pulse rectification technology is adopted, the stability of the direct current bus is guaranteed, the quality of the electric energy on the grid side is optimized and improved, the source-grid-load interaction capacity is improved by mixing and connecting the phase-shifting rectification conversion device and the flexible grid-connected bidirectional device in parallel, and meanwhile, the system can still run stably and reliably under the condition of local faults by adopting a multi-section direct current bus connection mode and matching the flexible grid-connected bidirectional device.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (12)
1. The utility model provides a high-power direct current charging system, is applicable to electric ship, its characterized in that includes:
the two direct current charging modules are respectively provided with a charging interface and are used for charging the electric ship through the charging interfaces; each direct current charging module is respectively provided with a self-adaptive detection control unit; the self-adaptive detection control unit is connected with the electric ship, acquires an electric characteristic value of the electric ship and obtains a voltage detection value; at least one voltage threshold range is preset in the self-adaptive detection control unit, and each voltage threshold range is adjusted through the voltage detection value; each direct current charging module is provided with a flexible grid-connected unit, and the flexible grid-connected unit is arranged between an external alternating current power grid and a direct current bus connected with the direct current charging module; the flexible grid-connected unit is connected with the self-adaptive detection control unit, and adjusts the working state of energy exchange between the direct current bus and the external alternating current power grid and adjusts the working state of the corresponding direct current charging module according to the comparison result of the real-time voltage of the direct current bus detected in real time and the voltage threshold range at the current moment.
2. The high power dc charging system according to claim 1, wherein each of said dc charging modules further comprises: the voltage transformation unit is used for carrying out voltage reduction processing on the voltage of a high-voltage alternating current bus in the external alternating current power grid and then inputting the voltage into a low-voltage alternating current bus; the phase-shifting rectifying unit is connected to the low-voltage alternating current bus and is used for converting the voltage of the low-voltage alternating current bus and inputting the converted voltage to the direct current bus; a reactive compensation unit connected to the low-voltage alternating current bus and used for compensating reactive current of the low-voltage alternating current bus; the charging units are respectively connected between the direct current bus and the charging interface and used for charging the electric ship through the charging interface; the energy storage unit is connected to the direct current bus, is preset with an upper energy storage limit and a lower energy storage limit and is used for storing the energy of the direct current bus; the power generation unit is connected to the direct current bus and used for generating photovoltaic energy and outputting the photovoltaic energy to the direct current bus; and the super capacitor unit is connected to the direct current bus and used for stabilizing the voltage of the direct current bus.
3. The high power dc charging system of claim 2, wherein the flexible grid connection unit comprises: the acquisition component is used for acquiring the current voltage threshold range in the self-adaptive detection control unit in real time; the detection component is connected with the acquisition component and is used for detecting the real-time voltage on the direct current bus, comparing the detected real-time voltage with the currently acquired voltage threshold range and outputting the comparison result; and the control component is connected with the detection component and generates a corresponding control instruction according to the comparison result, and the control component adjusts the working state of energy exchange between the direct current bus and the external alternating current power grid and adjusts the working state of the corresponding direct current charging module according to the control instruction.
4. The high power dc charging system according to claim 3, wherein said adaptive detection control unit comprises: a first identification acquisition means for acquiring an electric ship voltage, an electric ship power, and an electric ship charging capacity of the electric ship and including them in the electric characteristic value; the first calculation part is connected with the first identification acquisition part and used for calculating the voltage detection value according to the electrical characteristic value; the adjusting component is connected with the first calculating component, is preset with a plurality of voltage threshold value ranges and respectively adjusts each voltage threshold value range in real time according to the voltage detection value; the plurality of voltage threshold ranges respectively include: when the real-time voltage of the direct current bus is within the first voltage threshold range, the direct current charging module is in an overvoltage fault state, and at the moment, the corresponding control instruction controls the direct current charging module to stop working and outputs overvoltage warning information; when the real-time voltage of the direct current bus is within the second voltage threshold range, the corresponding control instruction controls the power generation unit to stop working at the moment; when the real-time voltage of the direct current bus is within the third voltage threshold range, the corresponding control instruction is to preferentially control the energy storage unit to perform charging operation and then start the flexible grid-connected unit to transmit the energy of the direct current bus to the low-voltage alternating current bus; when the real-time voltage of the direct current bus is within the fourth voltage threshold range, the corresponding control instruction controls the power generation unit to generate power; when the real-time voltage of the direct-current bus is within the fifth voltage threshold range, the corresponding control instruction is to start the flexible grid-connected unit to transmit the energy of the low-voltage alternating-current bus to the direct-current bus; when the real-time voltage of the direct current bus is within the sixth voltage threshold range, the corresponding control instruction controls the energy storage unit to perform discharge work at the moment; and when the real-time voltage of the direct current bus is within the seventh voltage threshold range, the direct current charging module is in an undervoltage fault state, and at the moment, the corresponding control instruction controls the direct current charging module to stop working and output undervoltage alarm information.
5. The high power dc charging system according to claim 4, wherein the first calculation means calculates the voltage detection value by the following formula:
wherein,
us is the voltage detection value;
w0 is the electric marine power;
e0 is the electric ship charging capacity;
a is a correction factor associated with the voltage on the DC bus;
mt is a power change coefficient of the electric ship changing with time in a charging state.
6. The high power dc charging system according to claim 4, wherein said adjusting means adjusts each of said voltage threshold ranges by the following formula:
wherein,
w0 is the electric marine power;
d is a voltage threshold correction coefficient;
nw is a power variation correction coefficient;
us is the voltage detection value;
u1 is the first voltage threshold range;
u2 is the second voltage threshold range;
u3 is the third voltage threshold range;
u41 is the upper limit of the fourth voltage threshold range;
u42 is the lower limit of the fourth voltage threshold range;
u5 is the fifth voltage threshold range;
u6 is the sixth voltage threshold range;
u7 is the seventh voltage threshold range.
7. The high power dc charging system according to claim 2, wherein each dc charging module further comprises: the voltage stabilization control unit is connected between the direct current bus and the electric ship, is respectively connected with the charging unit and the super capacitor unit, and is used for controlling the output voltage and the output power of the charging unit and the super capacitor unit; the voltage stabilization control unit further includes: a second identification acquisition unit that acquires an electric ship voltage and an electric ship power of the electric ship; the second calculating component is connected with the second identification and acquisition component and used for calculating and outputting a first output voltage according to the voltage of the electric ship; the third calculating component is connected with the second identification and acquisition component and used for calculating and outputting a second output voltage according to the voltage detection value; the fourth calculating component is connected with the second identification and acquisition component and used for calculating and outputting first output power according to the power of the electric ship; a first voltage stabilization control unit, respectively connected to the second calculation unit, the third calculation unit and the fourth calculation unit, for: generating a first control instruction according to the first output voltage and sending the first control instruction to the charging unit so as to use the first output voltage as the charging output voltage of the charging unit; generating a second control instruction according to the second output voltage and sending the second control instruction to the super capacitor unit so as to use the second output voltage as the output voltage of the super capacitor unit; and generating a third control instruction according to the first output power and sending the third control instruction to the super capacitor unit so as to use the first output power as the output power of the super capacitor unit.
8. The high power dc charging system according to claim 7, wherein the second calculating means calculates the first output voltage by the following equation:
wherein,
u0 is the electric watercraft voltage;
Δ U is a supplemental voltage;
uz is the first output voltage.
9. The high power dc charging system according to claim 7, wherein said third calculating means calculates said second output voltage by the following equation:
wherein,
us is the voltage detection value;
uc is the second output voltage.
10. The high power dc charging system according to claim 7, wherein the fourth calculating means calculates the first output power by the following equation:
wherein,
w0 is the electric marine power;
b is a correction factor associated with the output voltage of the super capacitor;
wc is the first output power.
11. The high-power direct-current charging system according to claim 1, wherein the two direct-current charging modules are a first direct-current charging module and a second direct-current charging module respectively; the first direct current charging module and the second direct current charging module exchange energy through a direct current communication module; the direct current communication module is specifically provided with: the first detection unit is connected with the first direct current charging module and used for detecting the real-time running state of the first direct current charging module and the real-time voltage of the first direct current charging module and outputting first detection data; the second detection unit is connected with the second direct current charging module and used for detecting the real-time running state of the second direct current charging module and the real-time voltage of the second direct current charging module and outputting second detection data; and the control unit is respectively connected with the first detection unit and the second detection unit and is used for controlling the connection or disconnection of the direct current connection module according to the first detection data and the second detection data so as to stabilize the voltage of the direct current bus.
12. The high-power dc charging system according to claim 11, wherein the control unit specifically comprises: a third identification acquisition means that acquires the first detection data; a fourth identification acquisition section that acquires the second detection data; the fifth calculation component is prestored with standard operation data of the first direct current charging module, connected with the third identification acquisition component and used for comparing and calculating the first operation state data according to the first detection data and the standard operation data of the first direct current charging module to obtain and output the first operation state data; the sixth calculation component is prestored with standard operation data of a second direct current charging module, connected with the fourth identification acquisition component and used for comparing and calculating the second operation state data according to the second detection data and the standard operation data of the second direct current charging module to obtain and output second operation state data; and the second voltage stabilization control part is respectively connected with the fifth calculation part and the sixth calculation part and is used for correspondingly generating a fourth control instruction according to the first operation state data and the second operation state data so as to connect or disconnect the direct current communication module.
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