Port electromagnetic crane, regenerated energy recovery and cyclic utilization method and application

Abstract

The invention discloses a port electromagnetic crane and a regenerated energy recovery and cyclic utilization method and application, according to the scheme, whether a variable frequency motor is in an electric state or a power generation state is judged in real time by ingeniously monitoring the voltage change condition of a common direct current bus between the variable frequency motor and a frequency converter, and meanwhile, the variable frequency motor is in a regenerated energy recovery and cyclic utilization state. According to the scheme, the state of the energy storage unit is monitored, charging and discharging of the auxiliary motor are carried out through the energy storage unit so as to avoid negative effects on a system circuit, and the working state of the energy storage unit is switched to different states through the energy manager according to the state information of the motor and the energy storage state information of the energy storage unit; the scheme can be applied to a working control method of the port electromagnetic crane to realize energy recovery and reutilization when the lifting motor of the crane works, and meanwhile, as regenerated energy generated by the lifting motor is not fed back to a power grid, the regenerated energy cannot impact the power grid, and pollution problems such as harmonic waves and flicker on the power grid cannot be generated.

Description

Technical Field

[0001] The invention relates to the fields of energy storage technology and port crane operation control technology, and in particular to a port electromagnetic crane and a regenerative energy recovery and recycling method and application. Background Art

[0002] Cranes are common transfer equipment in ports and docks. They are widely used due to their strong transfer capacity and stable operation. Hoisting motors are common working parts of cranes and undertake important transfer work. Due to the special working characteristics of hoisting motors, the use of variable frequency motors as hoisting motors has become a widely used technology.

[0003] With the development and wide application of variable frequency speed regulation technology, the current electrical transmission speed regulation scheme for port machinery mainly adopts AC variable frequency speed regulation scheme. When the hoisting motor assembly of the port crane is in loading and unloading operation, it will generate regenerative energy. There are two main types of regenerative energy. One is the inertia energy generated by the frequent braking of each mechanism, and the other is the potential energy generated by the descent of the lifting mechanism cargo. Because the hoisting motor corresponding to the mechanism has the effect of inertia energy or potential energy, the speed of the hoisting motor is higher than the speed corresponding to the output frequency of the inverter. The hoisting motor is in a regenerative power generation state, and the generated regenerative electric energy is fed back to the filter capacitor on the DC side of the inverter to generate a pump-up voltage. Because the excessively high pump-up voltage may damage the switching device, electrolytic capacitor, and even destroy the insulation of the motor, thus threatening the safe operation of the system. Therefore, this part of the regenerative energy must be processed. The traditional general methods for processing regenerative energy are energy consumption and energy feedback. Among them, energy consumption is to add a discharge resistor unit component on the DC side of the inverter, and consume the regenerative electric energy on the power resistor through a special energy consumption braking circuit, and convert it into heat energy, so it is called resistance braking. In order to ensure the safe operation of the system, this part of the electric energy has to be consumed by the resistor as heat energy, which is also the solution for the traditional crane frequency conversion system control; in addition, energy feedback is to install a feedback device to make the inverter grid-side converter reversible, and recycle the regenerated electric energy to the grid on site, making up for the loss of electric energy. This energy inverter feedback method needs to solve the following technical problems: (1) The feedback energy of the hoisting motor during braking is a shock source to the power grid, affecting the operation of the power grid. At the same time, it will produce more pollution problems such as harmonics and flicker. It is necessary to use corresponding filtering devices to control harmonics; (2) For lines with distributed generation systems, since the current flows in both directions between the power grid and the distributed system, the electric energy flowing back to the power grid will cause voltage fluctuations in the power grid and increase the short-circuit current of the power grid, posing a safety hazard to the use of electrical components in surrounding equipment; (3) For the user unit, the electric energy fed back to the grid can be measured, but there is a possibility that only part of the fed-back electric energy can be reused, that is, the fed-back electric energy cannot be fully utilized by the user unit, and it is difficult to accurately count the amount of electric energy reused by a single device.

[0004] In summary, there are certain technical difficulties in recovering and utilizing the regenerative energy of the hoisting motor of the crane using a variable frequency motor. How to recover and recycle the regenerative energy is an important issue for improving the energy efficiency of the crane and protecting the reliability of the system. If the logic of regenerative energy recovery and recycling can be optimized and technical transformation can be carried out, it will have positive practical significance for the optimization of the crane's operation. Summary of the invention

[0005] In view of this, the purpose of the present invention is to propose a port electromagnetic crane and a method and application for recycling and regenerating energy. This solution is reliable in implementation, flexible in application and can ensure the stability and safety of the working circuit of the crane when the regenerating energy generated by the crane's lifting motor (variable frequency motor) is recovered and recycled.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: A regenerative energy recovery and recycling method is used for the recovery and utilization of regenerative energy when a variable frequency motor is working. The variable frequency motor is electrically connected to a frequency converter, and the frequency converter is connected to a power grid to input electric energy for driving the variable frequency motor to work. A common DC bus is provided on the circuit connecting the frequency converter and the variable frequency motor, and an energy manager is connected to the common DC bus, and the energy manager is connected to an energy storage unit. The method comprises: S01, collecting voltage data of a common DC bus to which the variable frequency motor is connected in real time to generate voltage monitoring data; S02, judging the working state of the variable frequency motor according to the voltage monitoring data and the preset conditions, and generating the motor state information; S03, the energy manager collects parameters of the energy storage unit according to a preset time frequency, and generates energy storage status information according to preset conditions; S04. According to the motor status information and the energy storage status information of the energy storage unit, the energy manager switches the working status of the energy storage unit to the first state, the second state or the third state. In the first state, the energy manager controls the energy storage unit to be connected to the public DC bus to introduce the regenerative energy generated by the variable frequency motor for charging; in the second state, the energy manager controls the electric energy stored in the energy storage unit to be supplied to the public DC bus to assist the operation of the variable frequency motor; in the third state, the energy manager controls the energy storage unit to keep the electrical connection with the public DC bus interrupted.

[0007] As a possible implementation mode, further, the frequency converter described in this scheme includes a rectifier, an inverter and a braking unit. The rectifier is connected to the power grid to input electric energy for driving the variable frequency motor. The inverter is electrically connected to the rectifier and the variable frequency motor, respectively, so as to supply the electric energy input by the rectifier to the variable frequency motor. The braking unit is connected to the circuit between the rectifier and the inverter. The braking unit is also connected to a braking resistor. The braking resistor is used to feed back the regenerative energy on the common DC bus for consumption when the variable frequency motor is in a power generation state.

[0008] As a possible implementation mode, further, the energy storage unit described in this solution includes a capacitor management module and at least one supercapacitor; the energy manager includes a bidirectional DC-DC driver and a PLC module, the PLC module is electrically connected to the bidirectional DC-DC driver, and the working state of the bidirectional DC-DC driver is controlled by the PLC module, the bidirectional DC-DC driver is also electrically connected to at least one supercapacitor, the capacitor management module is electrically connected to the PLC module and at least one supercapacitor, and is used to obtain parameters of at least one supercapacitor at a preset time frequency and pass it to the PLC module to generate energy storage status information.

[0009] As a preferred implementation option, preferably, in the present solution S01, the voltage monitoring data are all associated with corresponding time points at which they are collected.

[0010] Based on the above, as a better implementation option, preferably, this solution S02 includes: S021. Gather voltage monitoring data within a preset time period in time series, and calculate the voltage monitoring data and the preset reference voltage according to the voltage monitoring data. The difference and voltage change rate ; S022. Determine the difference at the same time point t and voltage change rate ,when or , and the voltage change rate or When t, the working state of the variable frequency motor at the time point t is defined as the electric state, and the definition time of the working state is recorded at the same time; when , and the voltage change rate or voltage change rate When t is reached, the working state of the variable frequency motor at the time point t is defined as the power generation state, and the definition time of the working state is recorded at the same time, where: Setting a threshold for the voltage change rate; S023. Obtain the working state definition of the variable frequency motor and generate motor state information.

[0011] As a preferred implementation option, preferably, this solution S023 also includes: Obtain the working state definition of the variable frequency motor. When it points to the time point t when the variable frequency motor is in the power generation state, obtain the working state definition of the variable frequency motor in the time period T before the time point t according to the preset time window T. When the working state definition of the variable frequency motor in the time period T is all the power generation state, generate the power generation state as the motor state information. When the working state definition includes the electric state, generate the electric state as the motor state information. The working state definition and the motor state information corresponding to the variable frequency motor at the time point t are recorded separately and are related to each other.

[0012] Based on the above, the present solution also provides a port electromagnetic crane operation control method, which includes the above-mentioned regenerative energy recovery and recycling method; wherein the variable frequency motor is a lifting motor of the port electromagnetic crane; the operation control method includes: responding to the start signal of the electromagnetic crane, executing S01 to S04; it also includes one of the following: (1) Establish a mathematical model for the energy fluctuation of variable frequency motors, smooth the energy fluctuations through energy storage units, and optimize energy scheduling according to preset strategies; (2) According to the energy storage status information of the energy storage unit, the charge and discharge distribution of the energy storage unit is adjusted to balance the load of each sub-unit in the energy storage unit.

[0013] As a preferred implementation option, preferably, this solution establishes a mathematical model for energy fluctuations of variable frequency motors, smoothes energy fluctuations through energy storage units, and optimizes energy scheduling according to preset strategies, including: A01. Establish a mathematical model of energy fluctuation. Based on the fact that the electromagnetic crane uses a variable frequency motor for the lifting motor, the regenerative energy generation is a time-varying process. Assuming that the regenerative power is a function of time t and is defined as follows: ; in, is the electric power regenerated by the hoisting motor, in watts; is the mechanical-electrical conversion efficiency of the motor, It is the power converted from the mechanical energy of the motor; Based on mechanical power Hoisting speed of the crane's hoisting motor and load force Related, it is expressed as follows: ; in, , is the load force, is the weight of the cargo, is the acceleration; is the lifting speed in meters per second; By monitoring the mass and descent speed of the load, the electric power regenerated by the lifting motor is calculated in real time ; A02: The energy storage unit is used to absorb the energy fluctuations of regeneration and release the energy to the system in a timely manner. Assume that the storage capacity of the energy storage unit is , and its relationship with time is expressed as follows: ; in, is the energy in the energy storage unit, in joules, is the power of regenerative electricity, that is, the power regenerated by the lifting motor. is the electrical power consumed by the system; According to the storage capacity of the energy storage unit The relationship between the energy storage upper limit of the energy storage unit is used to manage its charging and discharging, including the following: when = The upper limit of the energy storage unit When , the energy storage unit stops charging; when Less than the lower limit of energy storage unit When the energy storage unit stops discharging and enters the charging standby state; Through the above-mentioned charge-discharge switching, the energy storage unit smoothes the fluctuation of the regenerative energy generated by the lifting motor and recovers the energy to release it in time; A03. In addition to the energy storage unit, the excess regenerative energy is fed back to the grid or used for other energy-consuming devices through the energy feedback system. The power conditioner is used in the circuit to transmit the excess regenerative energy to the grid. It is expressed as follows: ; in, To feedback power, The power of the regenerative energy is the power that the energy storage unit can absorb after charging, is the current load demand of the electromagnetic crane, when When , it means that the regenerative energy generated by the lifting motor can be fed back to the power grid. When , it means that the system needs to obtain energy from the grid; A04. Energy management is used to dispatch the regenerative energy and loads to dynamically adjust the charging and discharging of the energy storage unit and the grid feedback, including: when Greater than When the energy manager controls the energy storage unit to be connected to the common DC bus to introduce the regenerative energy generated by the lifting motor for charging; When the energy storage unit is fully loaded, and When the energy manager controls the energy storage unit to maintain the electrical connection with the common DC bus interrupted; When the system load requires more energy, the energy manager controls the electric energy stored in the energy storage unit to be supplied to the common DC bus to assist the variable frequency motor in working.

[0014] As a preferred implementation option, preferably, this solution adjusts the charge and discharge distribution of the energy storage unit according to the energy storage state information of the energy storage unit to balance the load of each subunit in the energy storage unit, including: B01. When the energy storage unit is composed of multiple supercapacitors, the storage capacity of each supercapacitor is defined as follows: The first i Energy storage of supercapacitors The voltage across the capacitor and capacitance value It is expressed as follows: ; in, It is i The energy stored by a supercapacitor at time t, in joules; It is i The capacitance value of a supercapacitor, in Farads; It is i The voltage of a supercapacitor at time t, in volts; Assuming that the energy storage unit has N supercapacitors that can be configured, the total system energy storage capacity It is expressed as follows: ; B02. Assign charging priority to N supercapacitors. Assume that the charging power of each supercapacitor is The current voltage and the regenerative energy provided by the system Impact, define charging power as: ; in, is the charging efficiency, which is between 0-1. is the current input power of the regenerative energy of the system, is the maximum charging voltage of the supercapacitor; For the charging power of each supercapacitor, is the current voltage of the supercapacitor; This formula shows that the supercapacitor with lower voltage will get more charging power first because the current voltage of the supercapacitor Distance Maximum Voltage The farther away it is, the more energy it is allocated; In order to prevent the supercapacitor from overcharging, the charging state of each supercapacitor is controlled by a threshold value, defining the maximum acceptable voltage of each supercapacitor. Once the current voltage of the supercapacitor The maximum acceptable voltage has been reached , the supercapacitor stops charging, and its strategy is described as follows: when When the charging power is allocated according to the priority level, when When the supercapacitor is charged, the remaining regenerative energy is distributed to other supercapacitors. B03. Assign discharge priority to N supercapacitors. Assume that the output power requirement of the system is , the discharge power of each supercapacitor is , which is defined as follows: ; in, is the discharge efficiency, is the discharge power of each supercapacitor, is the current voltage of the supercapacitor, is the output power requirement of the system; This formula strategy shows that the supercapacitor with higher voltage is discharged first to provide more stable output power; In order to prevent the supercapacitor from over-discharging, the discharge state of each supercapacitor is controlled by a threshold value and a minimum discharge voltage is set. ; when When , the supercapacitor continues to discharge; when When , the supercapacitor stops discharging; B04, dynamically adjusting the charging and discharging sequence of the N supercapacitors of the energy storage unit through the energy manager; In terms of charging priority adjustment, the voltage of all supercapacitors is calculated in real time to increase the charging priority of supercapacitors with lower voltages. At the same time, it ensures that the voltage of each supercapacitor does not exceed the maximum acceptable voltage. ; In terms of discharge priority adjustment, when the system load increases, the supercapacitors with higher voltage are given priority to supply energy. At the same time, it is ensured that the voltage of each supercapacitor is not lower than the minimum discharge voltage. ; The energy manager distributes energy to the N supercapacitors of the energy storage unit through a dynamic programming algorithm, allowing the system to optimize the charging and discharging sequence at each time step t to minimize energy loss and efficiency decay. Its objective function is defined as follows: ; in, For charging efficiency; For the charging power of each supercapacitor, is the discharge efficiency, is the discharge power of each supercapacitor.

[0015] As a preferred implementation option, preferably, the scheme adjusts the charge and discharge distribution of the energy storage unit to balance the load of each subunit in the energy storage unit and further includes: optimizing the distribution of the charging rate of the supercapacitor and optimizing the distribution of the discharge of the supercapacitor; Among them, the distribution optimization of the charging rate of the supercapacitor includes: Introducing the partition coefficient , which is used to adjust the charging rate of each supercapacitor, and its corresponding charging power is defined as follows: ; In the above formula, To allocate to i The charging power of a supercapacitor, is the total regenerative energy power of the system, For the i The dynamic allocation coefficient of the supercapacitor satisfies ; The corresponding distribution coefficient according to the voltage state of the supercapacitor Dynamic adjustment is performed, and the formula is defined as follows: ; in, It is i The charge distribution coefficient of a supercapacitor at time t is, is the maximum allowable charging voltage of the supercapacitor, is the current voltage of the supercapacitor at time t, It is the comprehensive charging demand of N supercapacitors, which represents the total charge margin of N supercapacitors in the system; Optimizing the distribution of supercapacitor discharge includes: Introducing the partition coefficient , which is used to adjust the discharge rate of each supercapacitor, and its corresponding discharge power is defined as follows: ; In the above formula, To allocate to i The discharge power of a supercapacitor, is the current load demand of the system, For the i The dynamic distribution coefficient of a supercapacitor, that is, the discharge distribution coefficient, Its satisfaction ; The corresponding distribution coefficient according to the voltage state of the supercapacitor Dynamic adjustment is performed, and the formula is defined as follows: ; in, It is i The discharge distribution coefficient of a supercapacitor at time t is, is the current voltage of the supercapacitor at time t, is the sum of the voltages of N supercapacitors, which represents the sum of the voltages of N supercapacitors in the system; The energy manager dynamically adjusts the control input based on future system predictions to optimize system performance. The control goal is to minimize energy loss and optimize energy utilization during charging and discharging. Its objective function is defined as follows: ; in, For charging efficiency; For the charging power of each supercapacitor, is the discharge efficiency, is the discharge power of each supercapacitor.

[0016] Based on the above, the present solution also provides a method for recycling the regenerative energy of a port crane variable frequency motor, which is applied by the above-mentioned regenerative energy recovery and recycling method or the above-mentioned port electromagnetic crane operation control method.

[0017] By adopting the above technical scheme, the present invention has the following beneficial effects compared with the prior art: the present scheme cleverly monitors the voltage change of the common DC bus between the variable frequency motor and the inverter to judge in real time whether the variable frequency motor is in the electric state or the power generation state. At the same time, the present scheme also monitors the state of the energy storage unit and uses the energy storage unit to charge and discharge the auxiliary motor to avoid its negative impact on the system circuit. The present scheme switches the working state of the energy storage unit to the first state, the second state or the third state through the energy manager according to the motor state information and the energy storage state information of the energy storage unit. In the first state, the energy manager controls the energy storage unit to be connected to the common DC bus to introduce the regenerative energy generated by the variable frequency motor for charging; in the second state, the energy manager controls the energy storage unit to be connected to the common DC bus to introduce the regenerative energy generated by the variable frequency motor for charging; in the second state, the energy manager controls the energy storage unit to be connected to the common DC bus to introduce the regenerative energy generated by the variable frequency motor for charging. The manager controls the electric energy stored in the energy storage unit to be supplied to the common DC bus to assist the operation of the variable frequency motor; in the third state, the energy manager controls the energy storage unit to maintain the interruption of the electrical connection with the common DC bus; this scheme can be applied to the working control method of the port electromagnetic crane to realize the energy recovery and reuse when the lifting motor of the crane is working. At the same time, because the regenerative energy generated by the lifting motor is not fed back to the power grid, the regenerative electric energy will not cause impact on the power grid when it is recovered, and will not cause pollution problems such as harmonics and flicker to the power grid. On the contrary, the stored energy is released during the accelerated start-up process of the lifting motor of the port electromagnetic crane, which can reduce the impact of the motor on the power grid, reduce the effect of the instantaneous drop in the power grid voltage (especially the working conditions of high-power motors), and improve the quality of power grid use. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a brief implementation flow diagram of the renewable energy recovery and recycling method of this scheme; Figure 2 It is a brief system schematic diagram of the connection between the frequency converter and the frequency conversion motor and other components in the regenerative energy recovery and recycling method of this scheme; Figure 3 It is a simplified system circuit schematic diagram of the connection between the inverter and the variable frequency motor and other components in the regenerative energy recovery and recycling method of this scheme. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0021] Combination Figure 1 As shown, the present scheme is a method for recycling and utilizing regenerative energy, which is used for recycling and utilizing regenerative energy when a variable frequency motor is working. The variable frequency motor is electrically connected to a frequency converter, which is connected to a power grid to input electric energy for driving the variable frequency motor to work. A common DC bus is provided on the circuit connecting the frequency converter and the variable frequency motor, and an energy manager is connected to the common DC bus, which is connected to an energy storage unit. The method comprises: S01, collecting voltage data of a common DC bus to which the variable frequency motor is connected in real time to generate voltage monitoring data; S02, judging the working state of the variable frequency motor according to the voltage monitoring data and the preset conditions, and generating the motor state information; S03, the energy manager collects parameters of the energy storage unit according to a preset time frequency, and generates energy storage status information according to preset conditions; S04, according to the motor state information, combined with the energy storage state information of the energy storage unit, switching the working state of the energy storage unit to the first state, the second state or the third state through the energy manager; In the first state, the energy manager controls the energy storage unit to be connected to the common DC bus to introduce the regenerative energy generated by the variable frequency motor for charging; In the second state, the energy manager controls the electric energy stored in the energy storage unit to be supplied to the common DC bus to assist the operation of the variable frequency motor; In the third state, the energy manager controls the energy storage unit to maintain an electrical disconnection with the common DC bus.

[0022] Combination Figure 2 , Figure 3As shown in the figure, as a possible implementation mode of the frequency converter, further, the frequency converter described in this scheme includes a rectifier, an inverter and a brake unit, the rectifier is connected to the power grid to input electric energy for driving the variable frequency motor to work, the inverter is electrically connected to the rectifier and the variable frequency motor respectively, so as to supply the electric energy connected by the rectifier to the variable frequency motor, the brake unit is connected to the circuit between the rectifier and the inverter, and the brake unit is also connected to a brake resistor, which is used to feed back the regenerative energy on the common DC bus for consumption when the variable frequency motor is in a power generation state; In the first step, the energy storage unit of the present invention includes a capacitor management module and at least one super capacitor; the energy manager includes a bidirectional DC-DC driver and a PLC module, the PLC module is electrically connected to the bidirectional DC-DC driver, and the working state of the bidirectional DC-DC driver is controlled by the PLC module. The bidirectional DC-DC driver is also electrically connected to at least one super capacitor, and the capacitor management module is electrically connected to the PLC module and at least one super capacitor, and is used to obtain the parameters of at least one super capacitor according to a preset time frequency, and pass it to the PLC module to generate energy storage status information.

[0023] In order to improve the time consistency of data monitoring and processing, as a better implementation option, preferably, in the present solution S01, the voltage monitoring data are all associated with the time point at which they are collected.

[0024] In this solution, the working state of the variable frequency motor is judged according to the change of the voltage monitoring data. In order to improve the reliability and accuracy of the detection, based on the above, as a better implementation option, preferably, this solution S02 includes: S021. Gather voltage monitoring data within a preset time period in time series, and calculate the voltage monitoring data and the preset reference voltage according to the voltage monitoring data. The difference and voltage change rate ; S022. Determine the difference at the same time point t and voltage change rate ; when or , and the voltage change rate or When t, the working state of the variable frequency motor at the time point t is defined as the electric state, and the definition time of the working state is recorded at the same time; when , and the voltage change rate or voltage change rate When t is reached, the working state of the variable frequency motor at the time point t is defined as the power generation state, and the definition time of the working state is recorded at the same time, where: Setting a threshold for the voltage change rate; S023. Obtain the working state definition of the variable frequency motor and generate motor state information, that is, correspond the working state definition of the variable frequency motor to the motor state information.

[0025] Since the time that the variable frequency motor is in the charging state fluctuates, in order to avoid the energy manager sending high-frequency switching when the variable frequency motor is in the charging state for too short a time, the variable frequency motor can be ignored in time when it is in the power generation state for a short time to avoid the energy storage unit frequently switching to the charging state in a short time. As a better implementation option, preferably, this solution S023 also includes: Obtain the working state definition of the variable frequency motor. When it points to the time point t when the variable frequency motor is in the power generation state, obtain the working state definition of the variable frequency motor in the time period T before the time point t according to the preset time window T; When the working state definition of the variable frequency motor in the time period T is all the power generation state, the power generation state is generated as the motor state information; When the working state definition includes the electric state, the electric state is generated as the motor state information; wherein the working state definition and the motor state information corresponding to the variable frequency motor at the time point t are recorded separately and are related to each other.

[0026] Based on the above, the regenerative energy recovery and recycling method of this scheme can be applied to the working control method of the port electromagnetic crane; wherein the variable frequency motor is the lifting motor of the port electromagnetic crane; the working control method comprises: responding to the start signal of the electromagnetic crane, executing S01 to S04; it also comprises one of the following: (1) Establish a mathematical model for the energy fluctuation of variable frequency motors, smooth the energy fluctuations through energy storage units, and optimize energy scheduling according to preset strategies; (2) According to the energy storage status information of the energy storage unit, the charge and discharge distribution of the energy storage unit is adjusted to balance the load of each sub-unit in the energy storage unit.

[0027] In this solution, when the lifting motor is in the power generation state, the regenerative electric energy it generates is fed back to the common DC bus of the inverter to generate a pump-up voltage. Under the scheduling of the energy manager, the energy storage unit of this solution intervenes in a timely manner to convert the generated regenerative electric energy into the charging energy of the supercapacitor of the energy storage unit. In terms of the stable consumption of regenerative energy, this solution establishes a mathematical model for the energy fluctuation of the variable frequency motor, smoothes the energy fluctuation through the energy storage unit, and optimizes the energy scheduling according to the preset strategy, including: A01. Establish a mathematical model of energy fluctuation. Based on the fact that the electromagnetic crane uses a variable frequency motor for the lifting motor, the regenerative energy generation is a time-varying process. Assuming that the regenerative power is a function of time t and is defined as follows: ; in, is the electric power regenerated by the hoisting motor, in watts; is the mechanical-electrical conversion efficiency of the motor, It is the power converted from the mechanical energy of the motor; Based on mechanical power Hoisting speed of the crane's hoisting motor and load force Related, it is expressed as follows: ; in, , is the load force, is the weight of the cargo, is the acceleration; is the lifting speed in meters per second; By monitoring the mass and descent speed of the load, the electric power regenerated by the lifting motor is calculated in real time ; A02: The energy storage unit is used to absorb the energy fluctuations of regeneration and release the energy to the system in a timely manner. Assume that the storage capacity of the energy storage unit is , and its relationship with time is expressed as follows: ; in, is the energy in the energy storage unit, in joules, is the power of regenerative electricity, that is, the power regenerated by the lifting motor. is the electrical power consumed by the system; According to the storage capacity of the energy storage unit The relationship between the energy storage upper limit of the energy storage unit is used to manage its charging and discharging, including the following: when = The upper limit of the energy storage unit When , the energy storage unit stops charging; when Less than the lower limit of energy storage unit When the energy storage unit stops discharging and enters the charging standby state; Through the above-mentioned charge-discharge switching, the energy storage unit smoothes the fluctuation of the regenerative energy generated by the lifting motor and recovers the energy to release it in time; A03. In addition to the energy storage unit, the excess regenerative energy is fed back to the grid or used for other energy-consuming devices through the energy feedback system. The power conditioner is used in the circuit to transmit the excess regenerative energy to the grid. It is expressed as follows: ; in, To feedback power, The power of the regenerative energy is the power that the energy storage unit can absorb after charging, is the current load demand of the electromagnetic crane, when When , it means that the regenerative energy generated by the lifting motor can be fed back to the power grid. When , it means that the system needs to obtain energy from the grid; A04. Energy management is used to dispatch the regenerative energy and loads to dynamically adjust the charging and discharging of the energy storage unit and the grid feedback, including: when Greater than When the energy manager controls the energy storage unit to be connected to the common DC bus to introduce the regenerative energy generated by the lifting motor for charging; When the energy storage unit is fully loaded, and When the energy manager controls the energy storage unit to maintain the electrical connection with the common DC bus interrupted; When the system load requires more energy, the energy manager controls the electric energy stored in the energy storage unit to be supplied to the common DC bus to assist the variable frequency motor in working.

[0028] In addition, in order to efficiently and reliably balance the load of each supercapacitor in the energy storage unit, as a preferred implementation option, preferably, this solution adjusts the charge and discharge distribution of the energy storage unit according to the energy storage state information of the energy storage unit to balance the load of each sub-unit in the energy storage unit, including: B01. When the energy storage unit is composed of multiple supercapacitors, the storage capacity of each supercapacitor is defined as follows: The first i Energy storage of supercapacitors The voltage across the capacitor and capacitance value It is expressed as follows: ; in, It is i The energy stored by a supercapacitor at time t, in joules; It is i The capacitance value of a supercapacitor, in Farads; It is i The voltage of a supercapacitor at time t, in volts; Assuming that the energy storage unit has N supercapacitors that can be configured, the total system energy storage capacity It is expressed as follows: ; B02. Assign charging priority to N supercapacitors. Assume that the charging power of each supercapacitor is The current voltage and the regenerative energy provided by the system Impact, define charging power as: ; in, is the charging efficiency, which is between 0-1. is the current input power of the regenerative energy of the system, is the maximum charging voltage of the supercapacitor; For the charging power of each supercapacitor, is the current voltage of the supercapacitor; This formula shows that the supercapacitor with lower voltage will get more charging power first because the current voltage of the supercapacitor Distance Maximum Voltage The farther away it is, the more energy it is allocated; In order to prevent the supercapacitor from overcharging, the charging state of each supercapacitor is controlled by a threshold value, defining the maximum acceptable voltage of each supercapacitor. Once the current voltage of the supercapacitor The maximum acceptable voltage has been reached , the supercapacitor stops charging, and its strategy is described as follows: when When the charging power is allocated according to the priority level, when When the supercapacitor is charged, the remaining regenerative energy is distributed to other supercapacitors. B03. Assign discharge priority to N supercapacitors. Assume that the output power requirement of the system is , the discharge power of each supercapacitor is , which is defined as follows: ; in, is the discharge efficiency, is the discharge power of each supercapacitor, is the current voltage of the supercapacitor, is the output power requirement of the system; This formula strategy shows that the supercapacitor with higher voltage is discharged first to provide more stable output power; In order to prevent the supercapacitor from over-discharging, the discharge state of each supercapacitor is controlled by a threshold value and a minimum discharge voltage is set. ; when When , the supercapacitor continues to discharge; when When , the supercapacitor stops discharging; B04, dynamically adjusting the charging and discharging sequence of the N supercapacitors of the energy storage unit through the energy manager; In terms of charging priority adjustment, the voltage of all supercapacitors is calculated in real time to increase the charging priority of supercapacitors with lower voltages. At the same time, it ensures that the voltage of each supercapacitor does not exceed the maximum acceptable voltage. ; In terms of discharge priority adjustment, when the system load increases, the supercapacitors with higher voltage are given priority to supply energy. At the same time, it is ensured that the voltage of each supercapacitor is not lower than the minimum discharge voltage. ; The energy manager distributes energy to the N supercapacitors of the energy storage unit through a dynamic programming algorithm, allowing the system to optimize the charging and discharging sequence at each time step t to minimize energy loss and efficiency decay. Its objective function is defined as follows: ; in, For charging efficiency; For the charging power of each supercapacitor, is the discharge efficiency, is the discharge power of each supercapacitor.

[0029] In terms of charging and discharging, in order to conveniently and timely correct the charging and discharging parameters of the supercapacitor so that the supercapacitor can better perform its performance during operation, as a preferred implementation option, preferably, the scheme adjusts the charging and discharging distribution of the energy storage unit to balance the load of each subunit in the energy storage unit and also includes: optimizing the distribution of the charging rate of the supercapacitor and optimizing the distribution of the supercapacitor discharge; Among them, the distribution optimization of the charging rate of the supercapacitor includes: Introducing the partition coefficient , which is used to adjust the charging rate of each supercapacitor, and its corresponding charging power is defined as follows: ; In the above formula, To allocate to i The charging power of a supercapacitor, is the total regenerative energy power of the system, For the i The dynamic allocation coefficient of the supercapacitor satisfies ; The corresponding distribution coefficient according to the voltage state of the supercapacitor Dynamic adjustment is performed, and the formula is defined as follows: ; in, It is i The charge distribution coefficient of a supercapacitor at time t is, is the maximum allowable charging voltage of the supercapacitor, is the current voltage of the supercapacitor at time t, It is the comprehensive charging demand of N supercapacitors, which represents the total charge margin of N supercapacitors in the system; Optimizing the distribution of supercapacitor discharge includes: Introducing the partition coefficient , which is used to adjust the discharge rate of each supercapacitor, and its corresponding discharge power is defined as follows: ; In the above formula, To allocate to i The discharge power of a supercapacitor, is the current load demand of the system, For the i The dynamic distribution coefficient of the supercapacitor, that is, the discharge distribution coefficient, satisfies ; The corresponding distribution coefficient according to the voltage state of the supercapacitor Dynamic adjustment is performed, and the formula is defined as follows: ; in, It is i The discharge distribution coefficient of a supercapacitor at time t is, is the current voltage of the supercapacitor at time t, is the sum of the voltages of N supercapacitors, which represents the sum of the voltages of N supercapacitors in the system; The energy manager dynamically adjusts the control input based on future system predictions to optimize system performance. The control goal is to minimize energy loss and optimize energy utilization during charging and discharging. Its objective function is defined as follows: ; in, For charging efficiency; For each supercapacitor charging power, is the discharge efficiency, is the discharge power of each supercapacitor.

[0030] Based on the above, the present solution also provides a method for recycling the regenerative energy of a port crane variable frequency motor, which is applied by the above-mentioned regenerative energy recovery and recycling method or the above-mentioned port electromagnetic crane operation control method.

[0031] The above descriptions are only some embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for recycling and utilizing regenerative energy, used for recycling and utilizing regenerative energy when a variable frequency motor is working, wherein the variable frequency motor is electrically connected to a frequency converter, the frequency converter is connected to a power grid to input electric energy for driving the variable frequency motor to work, a common DC bus is provided on the circuit connecting the frequency converter and the variable frequency motor, an energy manager is connected to the common DC bus, and the energy manager is connected to an energy storage unit; characterized in that: It includes: S01, collecting voltage data of a common DC bus to which the variable frequency motor is connected in real time to generate voltage monitoring data; S02, judging the working state of the variable frequency motor according to the voltage monitoring data and the preset conditions, and generating the motor state information; S03, the energy manager collects parameters of the energy storage unit according to a preset time frequency, and generates energy storage status information according to preset conditions; S04, according to the motor state information, combined with the energy storage state information of the energy storage unit, switching the working state of the energy storage unit to the first state, the second state or the third state through the energy manager; In the first state, the energy manager controls the energy storage unit to be connected to the common DC bus to introduce the regenerative energy generated by the variable frequency motor for charging; In the second state, the energy manager controls the electric energy stored in the energy storage unit to be supplied to the common DC bus to assist the operation of the variable frequency motor; In the third state, the energy manager controls the energy storage unit to maintain an electrical disconnection with the common DC bus.

2. The method for recycling and utilizing renewable energy according to claim 1, characterized in that: The frequency converter includes a rectifier, an inverter and a brake unit. The rectifier is connected to the power grid to input electric energy for driving the variable frequency motor. The inverter is electrically connected to the rectifier and the variable frequency motor respectively to supply the electric energy input by the rectifier to the variable frequency motor. The brake unit is connected to the circuit between the rectifier and the inverter. The brake unit is also connected to a brake resistor. The brake resistor is used to feed back the regenerative energy on the common DC bus for consumption when the variable frequency motor is in a power generation state.

3. The renewable energy recovery and recycling method according to claim 1, characterized in that: The energy storage unit includes a capacitor management module and at least one supercapacitor; the energy manager includes a bidirectional DC-DC driver and a PLC module, the PLC module is electrically connected to the bidirectional DC-DC driver, and the working state of the bidirectional DC-DC driver is controlled by the PLC module. The bidirectional DC-DC driver is also electrically connected to at least one supercapacitor, and the capacitor management module is electrically connected to the PLC module and at least one supercapacitor, and is used to obtain parameters of at least one supercapacitor at a preset time frequency and pass it to the PLC module to generate energy storage status information.

4. The method for recycling and utilizing renewable energy according to any one of claims 1 to 3, characterized in that: In S01, the voltage monitoring data are all associated with the time point at which they were collected; S02 includes: S021. Gather voltage monitoring data within a preset time period in time series, and calculate the voltage monitoring data and the preset reference voltage according to the voltage monitoring data. The difference and voltage change rate ; S022. Determine the difference at the same time point t and voltage change rate ; when or , and the voltage change rate or When t, the working state of the variable frequency motor at the time point t is defined as the electric state, and the definition time of the working state is recorded at the same time; when , and the voltage change rate or voltage change rate When t is reached, the working state of the variable frequency motor at the time point t is defined as the power generation state, and the definition time of the working state is recorded at the same time, where: Setting a threshold for the voltage change rate; S023. Obtain the working state definition of the variable frequency motor and generate motor state information.

5. The method for recycling and utilizing renewable energy according to claim 4, characterized in that: S023 also includes: Obtain the working state definition of the variable frequency motor. When it points to the time point t when the variable frequency motor is in the power generation state, obtain the working state definition of the variable frequency motor in the time period T before the time point t according to the preset time window T; When the working state definition of the variable frequency motor in the time period T is all the power generation state, the power generation state is generated as the motor state information; When the working state definition includes the electric state, the electric state is generated as the motor state information; wherein the working state definition and the motor state information corresponding to the variable frequency motor at the time point t are recorded separately and are related to each other.

6. A port electromagnetic crane operation control method, characterized in that: It includes the regenerative energy recovery and recycling method according to any one of claims 1 to 5; wherein the variable frequency motor is a lifting motor of a port electromagnetic crane; the work control method includes: responding to a start signal of the electromagnetic crane, executing S01 to S04; it also includes one of the following: (1) Establish a mathematical model for the energy fluctuation of variable frequency motors, smooth the energy fluctuations through energy storage units, and optimize energy scheduling according to preset strategies; (2) According to the energy storage status information of the energy storage unit, the charge and discharge distribution of the energy storage unit is adjusted to balance the load of each sub-unit in the energy storage unit.

7. The port electromagnetic crane operation control method according to claim 6, characterized in that: Establishing a mathematical model for energy fluctuations of variable frequency motors, smoothing energy fluctuations through energy storage units, and optimizing energy scheduling according to preset strategies include: A01. Establish a mathematical model of energy fluctuation. Based on the fact that the electromagnetic crane uses a variable frequency motor for the lifting motor, the regenerative energy generation is a time-varying process. Assuming that the regenerative power is a function of time t and is defined as follows: ； in, is the electric power regenerated by the hoisting motor, in watts; is the mechanical-electrical conversion efficiency of the motor, It is the power converted from the mechanical energy of the motor; Based on mechanical power Hoisting speed of the crane's hoisting motor and load force Related, it is expressed as follows: ； in, , is the load force, is the weight of the cargo, is the acceleration; is the lifting speed in meters per second; By monitoring the mass and descent speed of the load, the electric power regenerated by the lifting motor is calculated in real time ; A02: The energy storage unit is used to absorb the energy fluctuations of regeneration and release the energy to the system in a timely manner. Assume that the storage capacity of the energy storage unit is , and its relationship with time is expressed as follows: ； in, is the energy in the energy storage unit, in joules, is the power of regenerative electricity, that is, the power regenerated by the lifting motor. is the electrical power consumed by the system; According to the storage capacity of the energy storage unit The relationship between the energy storage upper limit of the energy storage unit is used to manage its charging and discharging, including the following: when = The upper limit of the energy storage unit When , the energy storage unit stops charging; when Less than the lower limit of energy storage unit When the energy storage unit stops discharging and enters the charging standby state; Through the above-mentioned charge-discharge switching, the energy storage unit smoothes the fluctuation of the regenerative energy generated by the lifting motor and recovers the energy to release it in time; A03. In addition to the energy storage unit, the excess regenerative energy is fed back to the grid or used for other energy-consuming devices through the energy feedback system. The power conditioner is used in the circuit to transmit the excess regenerative energy to the grid. It is expressed as follows: ； in, To feedback power, The power of the regenerative energy is the power that the energy storage unit can absorb after charging, is the current load demand of the electromagnetic crane, when When , it means that the regenerative energy generated by the lifting motor can be fed back to the power grid. When , it means that the system needs to obtain energy from the grid; A04. Energy management is used to dispatch the regenerative energy and loads to dynamically adjust the charging and discharging of the energy storage unit and the grid feedback, including: when Greater than When the energy manager controls the energy storage unit to be connected to the common DC bus to introduce the regenerative energy generated by the lifting motor for charging; When the energy storage unit is fully loaded, and When the energy manager controls the energy storage unit to maintain the electrical connection with the common DC bus interrupted; When the system load requires more energy, the energy manager controls the electric energy stored in the energy storage unit to be supplied to the common DC bus to assist the variable frequency motor in working.

8. The port electromagnetic crane operation control method according to claim 6, characterized in that: According to the energy storage status information of the energy storage unit, the energy storage unit is charged and discharged to balance the load of each sub-unit in the energy storage unit, including: B01. When the energy storage unit is composed of multiple supercapacitors, the storage capacity of each supercapacitor is defined as follows: The first i Energy storage of supercapacitors The voltage across the capacitor and capacitance value It is expressed as follows: ； in, It is i The energy stored by a supercapacitor at time t, in joules; It is i The capacitance value of a supercapacitor, in Farads; It is i The voltage of a supercapacitor at time t, in volts; Assuming that the energy storage unit has N supercapacitors that can be configured, the total system energy storage capacity It is expressed as follows: ； B02. Assign charging priority to N supercapacitors. Assume that the charging power of each supercapacitor is The current voltage and the regenerative energy provided by the system Impact, define charging power as: ； in, is the charging efficiency, which is between 0-1. is the current input power of the regenerative energy of the system, is the maximum charging voltage of the supercapacitor; For each supercapacitor charging power, is the current voltage of the supercapacitor; This formula shows that the supercapacitor with lower voltage will get more charging power first because the current voltage of the supercapacitor Distance Maximum Voltage The farther away it is, the more energy it is allocated; In order to prevent the supercapacitor from overcharging, the charging state of each supercapacitor is controlled by a threshold value, defining the maximum acceptable voltage of each supercapacitor. Once the current voltage of the supercapacitor The maximum acceptable voltage has been reached , the supercapacitor stops charging, and its strategy is described as follows: when When the charging power is continuously allocated according to the priority; when When the supercapacitor is charged, the remaining regenerative energy is distributed to other supercapacitors. B03. Assign discharge priority to N supercapacitors. Assume that the output power requirement of the system is , the discharge power of each supercapacitor is , which is defined as follows: ； in, is the discharge efficiency, For the discharge power of each supercapacitor, is the current voltage of the supercapacitor, is the output power requirement of the system; This formula strategy shows that the supercapacitor with higher voltage is discharged first to provide more stable output power; In order to prevent the supercapacitor from over-discharging, the discharge state of each supercapacitor is controlled by a threshold value and a minimum discharge voltage is set. ; when When , the supercapacitor continues to discharge; when When , the supercapacitor stops discharging; B04, dynamically adjusting the charging and discharging sequence of the N supercapacitors of the energy storage unit through the energy manager, In terms of charging priority adjustment, the voltage of all supercapacitors is calculated in real time to increase the charging priority of supercapacitors with lower voltages. At the same time, it ensures that the voltage of each supercapacitor does not exceed the maximum acceptable voltage. , In terms of discharge priority adjustment, when the system load increases, the supercapacitors with higher voltage are given priority to supply energy. At the same time, it is ensured that the voltage of each supercapacitor is not lower than the minimum discharge voltage. ; The energy manager distributes energy to the N supercapacitors of the energy storage unit through a dynamic programming algorithm, allowing the system to optimize the charging and discharging sequence at each time step t to minimize energy loss and efficiency decay. Its objective function is defined as follows: ； in, For charging efficiency; For each supercapacitor charging power, is the discharge efficiency, is the discharge power of each supercapacitor.

9. The port electromagnetic crane operation control method according to claim 8, characterized in that: The charging and discharging distribution adjustment of the energy storage unit to balance the load of each sub-unit in the energy storage unit also includes: optimizing the distribution of the charging rate of the supercapacitor and optimizing the distribution of the discharge of the supercapacitor; Optimizing the charging rate of supercapacitors includes: Introducing the partition coefficient , which is used to adjust the charging rate of each supercapacitor, and its corresponding charging power is defined as follows: ； In the above formula, To allocate to i The charging power of a supercapacitor, is the total regenerative energy power of the system, For the i The dynamic allocation coefficient of the supercapacitor satisfies ; The corresponding distribution coefficient according to the voltage state of the supercapacitor Dynamic adjustment is performed, and the formula is defined as follows: ； in, It is i The charge distribution coefficient of a supercapacitor at time t is, is the maximum allowable charging voltage of the supercapacitor, is the current voltage of the supercapacitor at time t, It is the comprehensive charging demand of N supercapacitors, which represents the total charge margin of N supercapacitors in the system; Optimizing the distribution of supercapacitor discharge includes: Introducing the partition coefficient , which is used to adjust the discharge rate of each supercapacitor, and its corresponding discharge power is defined as follows: ； In the above formula, To allocate to i The discharge power of a supercapacitor, is the current load demand of the system, For the i The dynamic distribution coefficient of the supercapacitor, that is, the discharge distribution coefficient, satisfies ; The corresponding distribution coefficient according to the voltage state of the supercapacitor Dynamic adjustment is performed, and the formula is defined as follows: ； in, It is i The discharge distribution coefficient of a supercapacitor at time t is, is the current voltage of the supercapacitor at time t, is the sum of the voltages of N supercapacitors, which represents the sum of the voltages of N supercapacitors in the system; The energy manager dynamically adjusts the control input based on future system predictions to optimize system performance. The control goal is to minimize energy loss and optimize energy utilization during charging and discharging. Its objective function is defined as follows: ； in, For charging efficiency; For the charging power of each supercapacitor, is the discharge efficiency, is the discharge power of each supercapacitor.

10. A method for recycling regenerative energy of a frequency conversion motor of a port crane, characterized in that: The invention is applied with the regenerative energy recovery and recycling method described in any one of claims 1 to 5 or the port electromagnetic crane operation control method described in any one of claims 6 to 9.

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