Hybrid power control system and control method suitable for quayside container crane

Abstract

The invention relates to a hybrid power control system and method suitable for a quayside container crane. The hybrid power control system comprises a controller, a bidirectional rectifier, a bidirectional direct-current converter, a direct-current bus and an energy storage device, the direct-current bus is used for transmitting driving electric energy to the motors through the frequency converters, and the direct-current bus is used for realizing electric energy bidirectional flow between the direct-current bus and the energy storage device through the bidirectional direct-current converter; the controller performs analysis and calculation based on the acquired operation state information, and enables the energy storage device to be switched between a charging state and a discharging state according to a calculation result; in a charging state, electric energy on the direct current bus is sent to the energy storage device through the bidirectional direct current converter; and in a discharging state, the electric energy of the energy storage device is sent to the direct-current bus through the bidirectional direct-current converter. According to the technical scheme provided by the invention, hybrid power control of power utilization compensation of the quay crane can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of power control of a shore container crane, and in particular to a hybrid power control system and a control method suitable for a shore container crane. Background Art

[0002] As the core loading and unloading equipment of container terminals, the operating efficiency of quay cranes (shore container cranes) directly impacts the terminal's economic profitability. However, a single quay crane has a huge power demand, with stable power consumption exceeding 1MW, starting surge power reaching 1.6 times the stable value, and energy feedback. This presents a difficult challenge for underdeveloped countries and regions with underdeveloped power grids and insufficient power supply capacity. To ensure the normal operation of quay cranes, terminals in these areas face two options: if they have grid coverage, they must bear high capacity expansion fees and electricity costs; if the mains power is insufficient, they must equip multiple high-power diesel generator sets. Not only is the initial investment cost high, but the diesel generator sets cannot recover the feedback energy from the quay cranes, and must instead consume it through heating resistors, resulting in energy waste. Therefore, hybrid quay cranes using lithium batteries or supercapacitors have become a viable solution to these pain points.

[0003] However, hybrid quay cranes have yet to be implemented in terminal operations, primarily due to technical challenges. Conventional hybrid technology relies on DC bus voltage fluctuations to control the charging and discharging of energy storage devices: when the bus voltage drops, the energy storage device discharges; when the voltage rises, the energy storage device charges, and this charging and discharging cannot be manually controlled. However, the bidirectional rectifiers used in quay cranes maintain a constant DC bus voltage, making hybrid technology based on voltage fluctuations unsuitable for quay cranes. The development of new technologies to achieve hybrid functionality is urgently needed. Summary of the Invention

[0004] In view of the above problems in the prior art, the present invention proposes a hybrid power control system and control method suitable for a quayside container crane, which can realize hybrid power control for electricity compensation of the quayside container crane.

[0005] Specifically, the present invention proposes a hybrid power control system suitable for a shore container crane, wherein the shore container crane includes multiple frequency converters and multiple motors correspondingly connected to the multiple frequency converters. The hybrid power control system includes a controller, a bidirectional rectifier, a bidirectional DC converter, a DC bus, and an energy storage device.

[0006] The bidirectional rectifier transfers electric energy between the external power grid and the DC bus. The DC bus is used to transmit driving electric energy to the multiple motors through the multiple frequency converters. The DC bus is used to achieve bidirectional flow of electric energy with the energy storage device through a bidirectional DC converter. The bidirectional DC converter determines the direction and magnitude of the electric energy flow according to the control instructions issued by the controller.

[0007] The controller obtains operating status information of the bidirectional rectifier, the bidirectional DC converter, the energy storage device, and the multiple frequency converters connected, and performs analysis and calculation based on the operating status information to switch the energy storage device between a charging state and a discharging state;

[0008] In the charging state, the controller drives the bidirectional DC converter to enter the charging mode, and the electric energy on the DC bus is sent to the energy storage device through the bidirectional DC converter; in the discharging state, the controller drives the bidirectional DC converter to enter the discharging mode, and the electric energy of the energy storage device is sent to the DC bus through the bidirectional DC converter.

[0009] According to one embodiment of the present invention, the controller collects and aggregates the real-time power consumption of the multiple inverters. If the aggregate real-time power consumption is greater than zero, the controller calculates the difference between the power supply power setting value of the external power grid and the aggregate real-time power consumption. If the difference is greater than zero, the controller drives the bidirectional DC converter to enter a discharge mode, and the electric energy of the energy storage device is sent to the DC bus through the bidirectional DC converter.

[0010] If the total real-time power consumption is not greater than zero, the controller drives the bidirectional DC converter to enter a charging mode, and the electric energy on the DC bus is sent to the energy storage device through the bidirectional DC converter.

[0011] According to one embodiment of the present invention, the bidirectional DC converter has current control technology, and the control instruction includes the current control parameters of the bidirectional DC converter to achieve the discharge power of the bidirectional DC converter in the discharge mode or the charging power in the charging mode.

[0012] According to one embodiment of the present invention, when the energy storage device is in a discharging state, the controller controls the bidirectional rectifier to prevent the electric energy on the DC bus from flowing into the external power grid through the bidirectional rectifier;

[0013] When the energy storage device is in a charging state, the controller controls the bidirectional rectifier to prevent electric energy from an external power grid from flowing into the DC bus through the bidirectional rectifier.

[0014] According to one embodiment of the present invention, the controller is used to control the power transmission size of the bidirectional rectifier.

[0015] According to one embodiment of the present invention, if the energy storage device reaches a lower discharge limit protection value or an upper charge limit protection value, the controller limits the bidirectional DC converter to stop the discharging action or the charging action of the energy storage device.

[0016] According to one embodiment of the present invention, the controller is a high-speed PLC.

[0017] According to one embodiment of the present invention, the scanning period of the controller is less than 20 milliseconds.

[0018] According to one embodiment of the present invention, the energy storage device is a supercapacitor.

[0019] According to one embodiment of the present invention, the lower limit of discharge of the energy storage device is not less than 10%, and the upper limit of charge of the energy storage device is not more than 90%.

[0020] The present invention also provides a hybrid power control method, which is applied to the aforementioned hybrid power control system and includes the following steps:

[0021] S1, starting the shore container crane;

[0022] S2, the controller obtains operating status information of the bidirectional rectifier, the bidirectional DC converter, the energy storage device and the multiple inverter connections;

[0023] S3, determining whether the real-time power consumption of the plurality of inverters is greater than zero, if so, proceeding to step S4, if not, proceeding to step S6;

[0024] S4, determining whether the difference between the real-time power consumption and the power supply setting value of the external power grid is greater than zero, if so, proceeding to step S5, if not, proceeding to step S2;

[0025] S5, the energy storage device supplies power to the DC busbar through the bidirectional DC converter according to the difference, and the process proceeds to step S7;

[0026] S6, the energy storage device is charged by the bidirectional DC converter;

[0027] S7, judging whether the charging and discharging conditions of the energy storage device meet the requirements, if so, returning to step S2, if not, stopping the charging and discharging operation of the energy storage device.

[0028] According to one embodiment of the present invention, in step S5, the controller controls the bidirectional rectifier to prevent the electric energy on the DC bus from flowing into the external power grid through the bidirectional rectifier;

[0029] In step 6, the controller controls the bidirectional rectifier to prevent the electric energy of the external grid from flowing into the DC bus through the bidirectional rectifier.

[0030] The present invention provides a hybrid power control system and control method suitable for a quayside container crane. The control system uses a controller to calculate the required power of the quayside crane in real time, and controls a bidirectional DC converter and a bidirectional rectifier so that an energy storage device can be charged and discharged according to the power demand of the quayside crane, thereby achieving electricity compensation for the quayside crane.

[0031] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application. The accompanying drawings illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.

[0033] In the attached figure:

[0034] Figure 1 A structural schematic diagram of a hybrid power control system applicable to a shore container crane according to an embodiment of the present invention is shown.

[0035] Figure 2 A flow chart of a hybrid power control method applicable to a shore container crane according to an embodiment of the present invention is shown.

[0036] The above drawings include the following reference numerals:

[0037] Hybrid power control system 100

[0038] Controller 101

[0039] Bidirectional rectifier 102

[0040] Bidirectional DC converter 103

[0041] DC bus 104

[0042] Energy storage device 105

[0043] Communication bus 106

[0044] Shore container crane 200

[0045] External grid 300 DETAILED DESCRIPTION

[0046] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0047] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0048] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0049] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0050] In the description of this application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of this application; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0051] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0052] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is solely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. Furthermore, while the terms used in this application are selected from commonly known and commonly used terms, some terms mentioned in this specification may have been selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of this description. Furthermore, this application should be understood not only by the actual terms used, but also by the meaning implied by each term.

[0053] Figure 1 The following diagram illustrates a hybrid power control system for a shore-to-shore container crane according to one embodiment of the present invention. As shown, a hybrid power control system 100 is applicable to a shore-to-shore container crane 200. The shore-to-shore container crane 200 includes multiple inverters and multiple motors (motor 1 through motor n) connected to the inverters (inverter 1 through inverter n). The hybrid power control system 100 includes a controller 101, a bidirectional rectifier 102, a bidirectional DC converter 103, a DC bus 104, and an energy storage device 105.

[0054] The bidirectional rectifier 102 transfers electrical energy between the external power grid 300 and the DC bus 104. The bidirectional rectifier 102 converts AC power into DC power, which is then transmitted via the DC bus 104 to multiple frequency converters. The frequency converters then convert the power into AC power of a specific frequency to drive the motors. Furthermore, the DC bus 104 is used to facilitate bidirectional energy flow with the energy storage device 105 via the bidirectional DC converter 103. The bidirectional DC converter 103 determines the direction and magnitude of energy flow based on control commands from the controller 101. As will be readily understood, when the quay crane is generating electricity, excess energy on the DC bus 104 can be stored in the energy storage device 105 via the bidirectional DC converter 103. When the quay crane's power demand exceeds the external power grid 300 supply, energy from the energy storage device 105 is fed back to the DC bus 104 via the bidirectional DC converter 103 to maintain power supply for the quay crane.

[0055] Controller 101 obtains operating status information of bidirectional rectifier 102, bidirectional DC converter 103, energy storage device 105, and multiple inverter connections via communication bus 106. Controller 101 analyzes and calculates the operating status information and dynamically controls energy storage device 105 to switch between charging and discharging states.

[0056] When the energy storage device 105 is in the charging state and the quay crane is in the generating state, the controller 101 drives the bidirectional DC converter 103 to enter the charging mode, and the excess electric energy on the DC bus 104 is sent to the energy storage device 105 through the bidirectional DC converter 103; when the energy storage device 105 is in the discharging state, for example, the power demand of the quay crane exceeds the power supply capacity of the external power grid 300, the controller 101 drives the bidirectional DC converter 103 to enter the discharging mode, and the energy storage device 105 releases electric energy to be supplemented to the DC bus 104 through the bidirectional DC converter 103 to ensure the stable operation of the quay crane.

[0057] In some examples, the controller 101 collects and aggregates the real-time power consumption of multiple inverters in real time. The controller 101 determines the real-time power consumption. If the aggregate real-time power consumption is greater than zero, it indicates that the quay crane is in a power-consuming state. The controller 101 compares this aggregate value with the power supply setting value of the external power grid 300 and calculates the difference between the power supply setting value of the external power grid 300 and the aggregate value. If the difference is greater than zero, it indicates that the quay crane's power demand exceeds the power supply capacity of the external power grid 300. The controller 101 drives the bidirectional DC converter 103 into a discharge mode, and the energy storage device 105 releases energy, which is then transferred to the DC bus 104 via the bidirectional DC converter 103 to fill the power gap. If the aggregate real-time power consumption is not greater than zero, it indicates that the quay crane is in a power generation state (energy feedback). The controller 101 drives the bidirectional DC converter 103 into a charging mode, and the excess energy on the DC bus 104 is stored in the energy storage device 105 via the bidirectional DC converter 103.

[0058] In some examples, the bidirectional DC converter 103 has current control technology. The control instructions issued by the controller 101 include current control parameters of the bidirectional DC converter 103 to accurately control the discharge power of the bidirectional DC converter 103 in the discharge mode or the charging power in the charging mode.

[0059] In some examples, when energy storage device 105 is discharging, controller 101 limits the feedback function of bidirectional rectifier 102 to prevent electrical energy from flowing back to external grid 300 via bidirectional rectifier 102, ensuring that the discharged energy of energy storage device 105 is used only to meet the power needs of the quay crane. When energy storage device 105 is charging, controller 101 limits the rectification and power supply function of bidirectional rectifier 102 to prevent electrical energy from external grid 300 from participating in the charging process, ensuring that energy storage device 105 only absorbs excess energy fed back from the quay crane.

[0060] In some examples, the controller 101 is used to control the amount of power transferred by the bidirectional rectifier 102. Specifically, the controller 101 dynamically adjusts the power transmission of the bidirectional rectifier 102 based on the monitoring and analysis of the real-time operating status of the system. When the shore crane's power consumption exceeds the power supply power set by the external power grid 300 and the energy storage device 105 needs to discharge to supplement, the controller 101 will limit the bidirectional rectifier 102 from feeding power back to the power grid. By reducing its reverse transmission capacity, the power released by the energy storage device 105 is prevented from flowing back to the external power grid 300, ensuring that this energy is first used to meet the shore crane's own power needs and avoid energy waste. When the shore crane is in the power generation state, there is excess power on the DC bus 104, and the energy storage device 105 is charging, the controller 101 will limit the bidirectional rectifier 102 from obtaining power from the external power grid 300. By reducing its forward rectifier power, grid power is prevented from participating in the charging process of energy storage device 105. This allows energy storage device 105 to absorb only excess energy fed back by the quay crane, ensuring efficient energy recycling within the system. When the quay crane is operating normally and its power consumption matches the power supplied by the external grid 300, controller 101 controls bidirectional rectifier 102 to transmit power at a stable power level, maintaining a constant voltage on DC bus 104 and ensuring stable operation of equipment such as the inverter and motor.

[0061] In some examples, if the energy storage device 105 reaches the lower discharge limit protection value or the upper charge limit protection value, the controller 101 limits the bidirectional DC converter 103 to stop the discharge or charge action of the energy storage device 105. To ensure the service life and safety of the energy storage device 105, the system sets a charge and discharge protection threshold. When the power level of the energy storage device 105 drops to the lower discharge limit value, that is, not less than 10%, the bidirectional DC converter 103 stops the discharge operation and restores the normal operation of the bidirectional rectifier 102; when the energy storage device 105 is charged to the upper limit value, that is, not higher than 90%, the bidirectional DC converter 103 stops charging to avoid overcharging and damage to the equipment.

[0062] In some examples, the controller 101 is a high-speed PLC. As the core controller 101 of the system, the high-speed PLC establishes a connection with the bidirectional rectifier 102, the bidirectional DC converter 103, multiple frequency converters, and the energy storage device 105 through the communication bus 106. After completing data acquisition and calculation, the high-speed PLC sends control instructions to the bidirectional rectifier 102, the bidirectional DC converter 103 and other devices through the communication bus 106 to accurately control the operating mode of each device and achieve coordinated operation of the entire system. Preferably, the scanning cycle of the high-speed PLC is set to less than 20ms, preferably 10ms. The high-speed PLC can ensure that the operating parameters and status information of each device can be collected quickly and in real time, such as the real-time power consumption of the frequency converter, the working status of the bidirectional rectifier 102, the power of the energy storage device 105, etc.

[0063] In some examples, energy storage device 105 is a battery or a supercapacitor.

[0064] Figure 2 A flowchart of a hybrid power control method for a shore container crane according to an embodiment of the present invention is shown. As shown in the figure, the present invention also provides a hybrid power control method, which is applied to the aforementioned hybrid power control system 100. The hybrid power control method includes the following steps:

[0065] S1: Start the quayside container crane 200. Specifically, the quayside crane equipment is turned on, activating all components, including the bidirectional rectifier 102, multiple inverters and motors, the bidirectional DC converter 103, and the energy storage device 105, to prepare for operation. This provides the foundation for subsequent energy transmission and control. At this point, the external grid 300 supplies power to the DC bus 104 through the bidirectional rectifier 102, providing initial power to the various components of the quayside crane.

[0066] S2, information collection, the controller 101 obtains the operating status information of the bidirectional rectifier 102, the bidirectional DC converter 103, the energy storage device 105 and the multiple inverter connections. The collected content includes:

[0067] Bidirectional rectifier 102: operating mode, output voltage and current, and energy flow status;

[0068] Bidirectional DC converter 103: current operating mode (charging or discharging), input and output voltages and currents;

[0069] Energy storage device 105: remaining capacity, terminal voltage, charge and discharge current;

[0070] Multiple frequency converters: real-time power consumption and operating parameters of drive motors.

[0071] S3, power consumption status judgment, judging whether the total real-time power consumption of multiple inverters is greater than zero;

[0072] If so, it indicates that the quay crane is in a power-consuming state, consuming the power of the external power grid 300 or the energy storage device 105, and the process proceeds to step S4;

[0073] If not, it indicates that the quay crane is in the power generation state (energy feedback), and there is excess power on the DC bus 104, and the process goes to step S6;

[0074] S4, when the quay crane is in power consumption, determining whether the difference between the total real-time power consumption and the power supply setting value of the external power grid 300 is greater than zero;

[0075] If yes, it indicates that the electricity demand of the quay crane exceeds the power supply capacity of the external power grid 300 and there is a power gap, then the process goes to step S5;

[0076] If not, it indicates that the power supply of the external power grid 300 is sufficient to meet the power demand of the quay crane, and there is no need for the energy storage device 105 to discharge. The process returns to step S2 and continues to monitor the operating status information of each device in real time.

[0077] S5, the controller 101 drives the bidirectional DC converter 103 to enter the discharge mode, and the energy storage device 105 supplies power to the DC bus 104 through the bidirectional DC converter 103 according to the difference, and then proceeds to step S7;

[0078] S6: When the quay crane is in a power generation state, that is, when there is excess power on the DC bus 104, the controller 101 drives the bidirectional DC converter 103 to enter a charging mode, and stores the power on the DC bus 104 into the energy storage device 105 through the bidirectional DC converter 103;

[0079] S7, the controller 101 monitors the charge and discharge status of the energy storage device 105 in real time, and determines whether the charge and discharge conditions of the energy storage device 105 meet the preset conditions:

[0080] If the requirements are met, that is, the power level of the energy storage device 105 has not reached the lower discharge limit (e.g., not less than 10%) or the upper charge limit (e.g., not more than 90%), and the bidirectional DC converter 103, the bidirectional rectifier 102 and other devices are operating normally, the process returns to step S2 to continue collecting the operating status information of each device in real time to maintain dynamic monitoring and regulation of the system.

[0081] If the requirements are not met, for example, the power of the energy storage device 105 reaches the lower discharge limit or the upper charge limit, or an abnormal situation occurs such as a device failure, the controller 101 immediately stops the charging and discharging of the energy storage device 105 and restores the normal working state of the bidirectional rectifier 102 to ensure safe and stable operation of the system.

[0082] In some examples, in step S5, during the discharge process of the energy storage device 105, in order to prevent the discharged energy from flowing back to the external power grid 300 through the bidirectional rectifier 102, the controller 101 synchronously limits the grid feedback function of the bidirectional rectifier 102, ensuring that the energy released by the energy storage device 105 is only used to meet the power demand of the shore crane; in step 6, in order to prevent the electric energy of the external power grid 300 from participating in the charging process, the controller 101 limits the rectified power supply power of the bidirectional rectifier 102, ensuring that the energy storage device 105 only absorbs excess energy fed back by the shore crane.

[0083] Specific embodiment 1 is to solve the problem of power limitation of a container terminal quay crane. Figure 1 The quay crane hybrid system architecture shown above is used to derive the selection scheme based on the demand:

[0084] The power supply of each quay crane is required to be no more than 1MW. During the power consumption phase: a stable power consumption of 1.2MW for 10 seconds; a starting surge power of 1.8MW for 3 seconds; and a stable feedback power of 1MW for 10 seconds. The DC bus 104 voltage is a constant 720VDC. The quay crane operation volume is calculated based on 40 cycles per hour, 20 hours per day, and 300 days per year. A supporting energy storage device 105 (supercapacitor) is required to achieve "peak shaving" and smooth power fluctuations in the quay crane's power consumption.

[0085] 1. Calculation of power demand (calculation of the energy task to be undertaken by the energy storage device 105 based on the power characteristics of the quay crane):

[0086] Compensation difference power (start-up impact compensation): 1800KW-1000KW=800KW (lasting 3 seconds); energy consumption 800kW×3s=2400KWs;

[0087] Compensation difference power (stable power compensation): 1200KW-1000KW=200KW (lasting 10 seconds); energy consumption 200kW×10s=2000KWs;

[0088] Absorbed steady-state power (energy recovery): feedback power 1000KW (lasting 10 seconds); recoverable energy 1000kW×10s=10000KWs.

[0089] Second, hardware selection and parameter matching:

[0090] 1. Selection of supercapacitor (energy storage device 105)

[0091] Determine the supercapacitor parameters based on power requirements and 720VDC bus voltage:

[0092] Single cell specifications: 3000F / 3V, single energy 3.75Wh, charge and discharge rate 150C, cycle life over 1 million times;

[0093] Series design: 720V÷3V=240 groups in series to meet bus voltage requirements;

[0094] Parallel configuration:

[0095] Single group parameters: capacity 240×3.75=900Wh, rated current 3.75Wh÷3V=1.25A, maximum current 1.25A×150=187.5A, rated power 900W, maximum power 187.5A×720V=135kW;

[0096] After 8 groups are connected in parallel: the maximum power is 135kW×8=1080kW (>800kW impact demand), the total rated capacity is 900Wh×8÷1000=7.2kWh, and the available capacity (10%~90% range) is 5.76kWh, which meets the maximum discharge capacity of a single cycle (2400kWs+2000kWs=4400kWs=1.22kWh).

[0097] 2. Selection of bidirectional DC converter 103

[0098] Select 1000V / 1200A specifications, support current control technology, and meet:

[0099] Voltage matching: withstand voltage 1000V>bus voltage 720VDC;

[0100] Current capacity: Rated current 1200A, maximum current of 8 capacitors in parallel 187.5A × 8 = 1500A (short-term overload capacity needs to be verified or the specifications upgraded).

[0101] 3. Controller 101 selection

[0102] A certain brand of high-speed PLC is used, which has a 10-millisecond periodic cycle scanning function:

[0103] Real-time performance guarantee: Rapid acquisition of inverter power (e.g., 300 data points can be captured within 3 seconds during the startup shock phase) to ensure timely power calculation and control response;

[0104] Control accuracy: It can meet the demand for precise control of the charging and discharging of the energy storage device 105 under complex working conditions of the quay crane.

[0105] 3. System logic and operation adaptation:

[0106] Power connection: The supercapacitor is connected to the DC bus 104 via the bidirectional DC converter 103, and the high-speed PLC is connected to each device via the communication bus 106 to achieve data exchange and control command issuance;

[0107] Control process: Tell the PLC to monitor power in real time. When the power consumption of the quay crane exceeds 1MW, the supercapacitor is triggered to discharge and charging is started during power generation. At the same time, the energy flow of the bidirectional rectifier 102 is restricted to ensure that the energy storage device 105 can independently support power fluctuations and achieve the goal of "peak shaving and valley filling".

[0108] The hybrid power control system and control method for a shore container crane provided by the present invention have the following advantages:

[0109] Real-time power compensation for quay cranes is achieved by collecting real-time power data through high-speed PLC and calculating it through aggregation, thus achieving controllable power compensation technology. This allows the terminal to more flexibly match the power of energy storage devices based on financial and technical needs.

[0110] The bidirectional rectifier maintains the DC bus voltage at a constant value. The bidirectional DC converter based on current control technology can achieve energy transmission in either direction at any operating voltage, allowing the energy storage device to be flexibly charged and discharged according to the real-time energy demand of the quay crane.

[0111] The energy transfer function of the bidirectional rectifier is limited to ensure that the charging and discharging functions of the energy storage device fully correspond to the energy changes of the quay crane load, avoiding non-production energy exchange between the energy storage device and the external power grid. In actual control, the high-speed PLC dynamically limits the bidirectional energy transfer function of the bidirectional rectifier: that is, when the energy storage device discharges to compensate for the load power consumption, the grid feedback function of the bidirectional rectifier is limited; when the energy storage device charges to absorb the feedback energy, the grid rectification function of the bidirectional rectifier is also limited.

[0112] The timing scanning function of high-speed PLC is used to ensure the real-time and accuracy of control technology.

[0113] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention cover modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A hybrid power control system for a shore container crane, wherein the shore container crane comprises a plurality of frequency converters and a plurality of motors connected to the plurality of frequency converters, wherein: The hybrid power control system includes a controller, a bidirectional rectifier, a bidirectional DC converter, a DC bus and an energy storage device; The bidirectional rectifier transmits electric energy from an external power grid to the DC bus, the DC bus is used to transmit driving electric energy to multiple motors through the multiple frequency converters, and the DC bus is used to achieve bidirectional flow of electric energy with the energy storage device through a bidirectional DC converter; the bidirectional DC converter determines the direction and magnitude of electric energy flow according to the control instructions issued by the controller; The controller obtains operating status information of the bidirectional rectifier, the bidirectional DC converter, the energy storage device, and the multiple frequency converters connected, and performs analysis and calculation based on the operating status information to switch the energy storage device between a charging state and a discharging state; In the charging state, the controller drives the bidirectional DC converter to enter the charging mode, and the electric energy on the DC bus is sent to the energy storage device through the bidirectional DC converter; In the discharge state, the controller drives the bidirectional DC converter to enter the discharge mode, and the electric energy of the energy storage device is sent to the DC bus through the bidirectional DC converter.

2. The hybrid power control system for a shore container crane according to claim 1, characterized in that: The controller collects and aggregates the real-time power consumption of the multiple frequency converters. If the aggregate real-time power consumption is greater than zero, the controller calculates a difference between a power supply setting value of an external power grid and the aggregate real-time power consumption. If the difference is greater than zero, the controller drives the bidirectional DC converter to enter a discharge mode, and the electric energy of the energy storage device is fed into the DC bus through the bidirectional DC converter. If the total real-time power consumption is not greater than zero, the controller drives the bidirectional DC converter to enter a charging mode, and the electric energy on the DC bus is sent to the energy storage device through the bidirectional DC converter.

3. The hybrid power control system for a shore container crane according to claim 2, characterized in that: The bidirectional DC converter has a current control technology, and the control instruction includes a current control parameter of the bidirectional DC converter to achieve the discharge power of the bidirectional DC converter in the discharge mode or the charging power in the charging mode.

4. The hybrid power control system for a shore container crane according to claim 2, wherein: When the energy storage device is in a discharging state, the controller controls the bidirectional rectifier to prevent the electric energy on the DC bus from flowing into the external power grid through the bidirectional rectifier; When the energy storage device is in a charging state, the controller controls the bidirectional rectifier to prevent electric energy from an external power grid from flowing into the DC bus through the bidirectional rectifier.

5. The hybrid power control system for a shore container crane according to claim 4, characterized in that: The controller is used to control the power transmission size of the bidirectional rectifier.

6. The hybrid power control system for a shore container crane according to claim 1, characterized in that: If the energy storage device reaches a lower discharge protection value or an upper charge protection value, the controller limits the bidirectional DC converter to stop the discharging action or the charging action of the energy storage device.

7. The hybrid power control system for a shore container crane according to claim 1, characterized in that: The controller is a high-speed PLC.

8. The hybrid power control system for a shore container crane according to claim 1, characterized in that: The scanning period of the controller is less than 20 milliseconds.

9. The hybrid power control system for a shore container crane according to claim 1, characterized in that: The energy storage device is a battery or a supercapacitor.

10. The hybrid power control system for a shore container crane according to claim 6, characterized in that: The lower limit of discharge of the energy storage device is not less than 10%, and the upper limit of charge of the energy storage device is not more than 90%.

11. A hybrid power control method, applied to the hybrid power control system according to claim 1, comprising the steps of: S1, starting the shore container crane; S2, the controller obtains operating status information of the bidirectional rectifier, the bidirectional DC converter, the energy storage device and the multiple inverter connections; S3, determining whether the real-time power consumption of the plurality of inverters is greater than zero, if so, proceeding to step S4, if not, proceeding to step S6; S4, determining whether the difference between the real-time power consumption and the power supply setting value of the external power grid is greater than zero, if so, proceeding to step S5, if not, proceeding to step S2; S5, the energy storage device supplies power to the DC busbar through the bidirectional DC converter according to the difference, and the process proceeds to step S7; S6, the energy storage device is charged by the bidirectional DC converter; S7, judging whether the charging and discharging conditions of the energy storage device meet the requirements, if so, returning to step S2, if not, stopping the charging and discharging operation of the energy storage device.

12. The hybrid power control method according to claim 11, wherein: In step S5, the controller controls the bidirectional rectifier to prevent the electric energy on the DC bus from flowing into the external power grid through the bidirectional rectifier; In step 6, the controller controls the bidirectional rectifier to prevent the electric energy of the external grid from flowing into the DC bus through the bidirectional rectifier.

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