KR102249662B1 - Marine integrated power control management system - Google Patents

Abstract

An integrated power control management system for a ship is provided. The system is characterized by comprising: a power generation control unit for controlling and managing a power generation device including at least one of a power generator, a battery, and a renewable power generation device; and a load control unit for controlling and managing a load device including at least one of a propulsion motor, a cooling water pump system, an engine compartment intake and exhaust fan system, a living area air conditioning system, and a load control system. The power generation control unit and the load control unit receive the feedback of the power generation status and the power load operation status in the ship, thereby executing the switching-on and switching-off of each power generation device and the selective switching-off of each load.

Description

Marine integrated power control management system

The present invention relates to an integrated power control management system for ships, and more particularly, by receiving feedback on the power generation status and power load operation status from the power generation stage and the load stage in the ship, input and departure of each power generation device and selective blocking of each load are performed. Therefore, it relates to an integrated power control management system for integrated management of all electric facilities in a ship so that stable and efficient operation is possible.

Conventional ships are mostly equipped with diesel engines as main propulsion equipment to operate the ship as a main engine, and since this is an internal combustion engine, not an electric device, it has been classified as a mechanical facility and has been excluded from the ship's power system.

However, electric propulsion ships, which are in the spotlight as next-generation ships, are not equipped with a main engine based on an internal combustion engine because a propulsion motor is mounted as the main propulsion equipment. In addition, the power to drive the propulsion motor mounted on the electric propulsion ship is very large compared to the power generation and required power managed by the existing ship. Unlike mechanical propulsion, electric propulsion ships are propelled through electric power, so the stability of the power generation system is very important. In order to secure stability, the conventional power generation system used a large-capacity generator, but as a result, energy efficiency is lowered due to low-load operation, and economical efficiency is lowered. Therefore, the need to control and manage by integrating propulsion motors, generators and related power generation facilities, engine room and other power loads including heavy loads as a problem directly connected to safe navigation of next-generation ships has increased.

As a technology for the power management control system of such a ship, in the'electric propulsion ship equipped with a power management control system (registration number: 10-1117306)', the power management control panel controls the rotation speed of the propulsion motor and charges and discharges the storage battery. And by controlling the distribution, the propulsion and switching functions are provided in a single equipment so that the propulsion motor can be driven through an electric energy source such as a storage battery, a generator, and a solar cell module, so that propulsion can be carried out with optimal efficiency, as well as various conditions. Disclosed is a power management control system that controls each charging and discharging control to be performed.

However, as a control system for electric energy sources that enables the propulsion motor to be driven with optimum efficiency, the power of various loads mounted on the ship such as commercial loads, irregular loads, cargo equipment-related loads, and deck loads, excluding propulsion loads, are integrated. Since there is a limit to management, it is the time when the development of new technology is desperately required.

KR 10-1117306 B1

The present invention is to solve the above problems, and efficient operation is possible by receiving feedback on the power generation status and power load operation status from the power generation stage and the load stage in the ship, and performing input and departure of each power generation device and selective blocking of each load. The purpose of this is to provide an integrated power control management system for integrated management of all electric facilities in a ship.

According to the features of the present invention for achieving the above object, the present invention is an integrated power control management system for integrated management of all electrical equipment in a ship, comprising at least one of a generator, a battery, and a renewable power generation device. Power generation control unit that controls and manages power generation devices; and propulsion motors, cooling pump control systems (CPCS), engine room air supply and exhaust fan systems (ERFCS, Engine Room Fan Control System), and air conditioning systems in accommodation areas. (HVACS, Heating Ventilating and Air Conditioning System), a load control system (LCS, Load Control System) for controlling and managing a load device including at least one of the load control unit; comprises a, the power generation control unit and the load Provides an integrated power control management system for ships, characterized in that input and departure of each power generation device and selective cut-off of each load by receiving feedback from the control unit of the power generation status and the operation status of the power load in the ship.

The power generation control unit of the integrated power control management system for ships according to the present invention acquires in real time the load rate and spare power of the generator, which is the main power source, and starts and stops each generator according to the operating situation of the power load, power input, and It characterized in that it is configured to include a generator control device for controlling the departure.

The power generation control unit of the integrated power control management system for ships according to the present invention is a power system capable of bidirectional power control using a grid tie inverter or an active front end (AFE). It is characterized.

The power generation control unit of the integrated power control management system for ships according to the present invention, wherein the power generation device is in one of a generator single operation mode, a battery single operation mode, a generator operation-battery charging mode, and a generator-battery hybrid operation mode. It is characterized in that it is controlled to be operated.

The load control unit of the integrated power control management system for ships according to the present invention acquires the operating status of the propulsion motor in real time, and controls the output of the propulsion motor in consideration of the load factor and the spare power of the power generation source. It characterized in that it is configured to include a load control device.

The present invention according to the solution to the above problem is to secure the stability of the power system through integrated power control that enables bidirectional power grid operation centered on supply and demand power by interlocking each control unit of the power generation end and the load end in the ship, and There is an effect of improving the energy efficiency in the ship by controlling to satisfy the optimum operating conditions of the internal generator and the propulsion motor.

1 is a block diagram of an integrated power control management system according to an embodiment of the present invention.
Figure 2 is a wiring block diagram of a general electric propulsion ship.
3 is main measurement data for power management in the integrated power control management system according to an embodiment of the present invention.
4 is a diagram for explaining a non-stepless synchronous transfer control according to an embodiment of the present invention.
5 is a view for explaining a control mode of the power generation device according to an embodiment of the present invention.
6 is a view showing a reference load factor for controlling parallel input and departure of a generator according to an embodiment of the present invention.
7 is a view for explaining the acceleration limiting function of the propulsion electric motor according to an embodiment of the present invention.
8 is a view for explaining a starting torque compensation function of a propulsion motor according to an embodiment of the present invention.
9 is a diagram showing a stability standard of a general AC power system.
10 is a block diagram of the other load control device of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 10 in the accompanying drawings. On the other hand, in the drawings and detailed description, illustrations and references for configurations and actions that can be easily understood by those in the field from general power generation control, power control including load control, and the like are briefly or omitted. In particular, in the illustration and detailed description of the drawings, detailed descriptions and illustrations of specific technical configurations and actions of elements not directly related to the technical features of the present invention are omitted, and only the technical configurations related to the present invention are briefly illustrated or described. I did.

The integrated power control management system 10 according to the present invention is an integrated power control management system for ships to which a smart grid is applied, and as shown in FIG. 1, a power generation control unit consisting of a generator control device 110 and a battery control device 120 ( 100), and a load control unit 200 consisting of a propulsion load control device 210 and other load control device 220.

This integrated power control management system 10, as shown in Figure 2, a generator 111, a battery 121, a power generation stage having at least one power generation source of the renewable energy generation device 131 and a propulsion motor 211, The cooling pump 221, the engine room fan 222, the HVAC 223, and other auxiliary devices 224 can be applied to an electric propulsion ship composed of a load including at least one of the load end.

Electric propulsion ships are next-generation ships in which an engine drives a generator and rotates a propulsion motor with generated electric energy to drive a propeller.Diesel engine generator, dual fuel generator, LNG generator, lead acid battery, lithium ion battery, solar power It is characterized by establishing a hybrid power generation system by linking power generation and fuel cells. In particular, unlike conventional ships that used fossil fuel-based internal combustion engines such as diesel engines, electric propulsion ships account for more than 70% of the total energy consumption, thus ensuring stability in the operation of power generation and load stages. It is essential to secure it, and it is necessary to control the energy efficiently.

The power generation control unit 100 is configured to control all power sources in the ship, and includes a generator control device 110 and a battery control device 120. If the ship is equipped with a new and renewable energy generation device as an additional power source, a new and renewable energy generation control device for controlling it may be further provided. At this time, the power load operation status is fed back to the integrated power control management system 10 in real time so that it can be interlocked with the load control unit 200.

Power generation sources applied to ships can be mainly classified into generators, energy storage systems (ESS), and renewable energy. Among the generators, the prime mover is an internal combustion engine, and a diesel engine that operates based on the sabate cycle is mainly mounted, and recently, a dual fuel generator, an LNG generator, and a shaft generator are sometimes installed. The energy storage device refers to equipment used as a means to store energy through charging and discharging, such as a battery, and a lead acid battery or lithium-ion battery is mainly used, and in addition, it can be designed suitable for operating conditions such as power capacitors. have. Solar power generation is often used for new and renewable energy depending on the structure of the ship, and wind power generation is also used in ships.

Therefore, the power generation control unit 100 divides AC power and DC power according to the characteristics of each power source provided in the electric propulsion ship, and allows the DC power to be input according to the frequency of the AC power. inverter) or an active front end (AFE, Active Frond End) to enable integrated control of all power generation sources in the ship so that bidirectional power control is possible. In addition, since AC power and DC power have different electrical properties, the power generation control unit 100 uses data as shown in FIG. 3 to check the power production and power consumption of the integrated power control management system on board in real time and maintain the stability of the power system. It must be acquired.

The generator control device 110 performs overall operation and protection functions such as starting and stopping of the generator 111, which is the main power source of the ship, and power input and departure. This acquires the load ratio and spare power of the generator 111 in real time and feeds it back to the integrated power control management system 10, and controls the start-up and parallel connection of the generator 111 according to the operation status of the load stage. Control and management of the generator 111, which is the main power generation source, is performed through a function of selectively forcibly shutting off load devices of low importance.

The battery control device 120 controls to be operated at an optimal load ratio based on the operation and interlocking state of all power generation sources in the ship except for the generator 111, which is the main power generation source of the ship. This performs overall operation and protection functions such as starting and stopping of all power sources, such as the battery 121 including the energy storage device and the renewable energy power generation device 131, and power input and departure.

The power generation control unit 100 receives real-time data feedback from the generator control device 110 and the battery control device 120 based on the operation and interlocking state of each power generation source, and controls the operation at an optimal load rate to improve energy efficiency. will be.

The generator control device 110 performs a protection function for a peak load that may occur instantaneously in each generator 111, and when an overload occurs in a specific generator 111, the generator 111 stops and other generators By replacing it with (111), it performs a protective function against overload.

Since each generator 111 and the power load are designed based on AC or DC, when different types of power are required, or when a specific generator 111 is asynchronous with the driving frequency of the propulsion motor 211 or the frequency deviates In the case of occurrence, as shown in Fig. 4, by connecting to the main bus through a transfer switch capable of non-instantaneous synchronous transfer control, the power supply can be smoothly converted, and energy efficiency and operational stability are secured through power quality improvement. can do.

In addition, if the operation of the generator 111 is changed according to the operation of each load, and power optimization is performed through power and synchronous transfer control in real time, the load ratio of the generator 111 is lowered after the power optimization and fuel efficiency is reduced due to incomplete combustion. It is reduced, and if the low-load operation is performed for a long time, a mechanical defect may occur in the generator observation. Accordingly, the power generation control unit 100 receives operation data of each generator 111 from the generator control device 110 and selects and controls an operation mode suitable for the operation situation of power, thereby preventing low-load operation.

In the embodiment of the present invention, as the most basic structure, a case where power is supplied from a power generation stage composed of a generator 111 used as a main power generation source and a battery 121 that supplies power by assisting the same will be described as an example. do.

The operation mode for power supply of the power generation stage is divided into a generator single operation mode, a battery single operation mode, a generator operation-battery charging mode, and a generator-battery hybrid operation mode, as shown in FIG. 5.

As shown in (a) of FIG. 5, the single generator operation mode is an operation mode in which power is supplied using only the generator 111. In this operation mode, since the load ratio of the generator 111 may vary greatly depending on the power load, the load ratio of the generator 111 must be measured and calculated in focus to perform control.

As shown in FIG. 5B, the single battery operation mode is an operation mode in which power is supplied using only the battery. In this operation mode, since the battery 121 must handle the onboard power load, the state of charge of the battery 121 must be mainly measured and calculated to perform control.

As shown in (c) of FIG. 5, the generator operation-battery charging mode is a mode in which power is supplied by operating the generator 111 and at the same time the battery 121 is charged. In this operation mode, when it is determined that the load factor of the generator 111 is stable even when the battery 121 is charged, the battery 121 is treated the same as the power load from the side of the generator 111.

As shown in (d) of FIG. 5, the generator-battery hybrid operation mode is a mode in which power is supplied by operating the generator 111 and the battery 121 together. It is an operation mode that is performed when the power demand can be sufficiently handled by inserting the battery 121 rather than operating by connecting one more generator 111 in parallel to the generator 111 that is already being operated. For example, in a situation in which the power load is greatly fluctuated under the control of the propulsion motor 211, when it is necessary to temporarily handle the peak load of the generator 111, the battery 121 can be quickly input.

Since the battery 121 is designed differently in specifications such as capacity, C-Rate, etc. according to the purpose of operation, the battery 121 must be operated according to the purpose. For example, if the main purpose of the battery 121 is to reduce the peak load of the generator 111 and the overload operation, the discharge C-Rate is designed to be high and operated to handle the instantaneous peak load. , Overload is also operated in the same manner, but in consideration of the discharge of the battery 121, the control such as parallel operation of the generator 111 is accompanied. Conversely, it is also possible to handle constant power for a long time without increasing the discharge C-Rate.

Even when a fuel cell is mounted among the power generation sources, DC power is produced like the battery 121, and thus a single operation mode and a hybrid operation mode are provided. However, the operation mode that is treated as a power load from the side of the generator 111, such as charging the battery 121, is not operated. When a battery is mounted, the charging rate of the battery 121 must be considered in order to include a protection function of the power generation source against a peak load.

In addition, the new renewable energy generation device 131 such as solar or wind power generation does not directly input power, but indirectly generates power by charging the battery 121, so the battery 121 is not operated as a power generation source. In the situation, control is performed to charge the battery 121 in most situations except when the battery 121 is overcharged.

The power generation control unit 100 controls the generator 111 in synchronization with the main bus in order to additionally input or leave the generator 111. That is, if the generator 111 needs to be additionally operated due to insufficient power remaining in the power generation source being operated due to the fluctuation of the power load in the ship during operation, the generator 111 started in the stopped state is put into the main bus to generate the generator. The parallel operation of 111 is controlled, and when the generator 111 performs a low load operation due to a fall of the power load, the generator 111 is safely asynchronously and separated from the main bus sequentially over a predetermined period of time.

Here, an example of a reference load factor for controlling parallel input and departure of the generator 111 is shown in FIG. 6. For example, if the load ratio exceeds 80% in the state in which one generator 111 is input, one more generator 111 that is stopped 30 seconds later increases the power reserve and facilitates power supply and demand. In addition, when the load ratio of the generator 111 rapidly rises to 88% instantaneously, one more generator 111 that is stopped after 10 seconds is input. On the contrary, if the load ratio is lowered below 65% while the two generators 111 are turned on, one generator 111 is separated from the main bus after 600 seconds and then stopped.

The load control unit 200 is configured to control all power loads in the ship, and includes a propulsion load control device 210 and other load control devices 220. At this time, the power load operation status is fed back to the integrated power control management system 10 in real time so that it can be interlocked with the power generation control unit 100.

The propulsion load control device 210 controls the output of the propulsion motor 211, which is the main propulsion equipment, and protects the propulsion motor 211 in case of emergency. Since the load rate of the power generation source, the reserve power in the ship, and the operation situation of the power load vary according to the operation of the ship and the maritime situation, instantaneous control and management of the propulsion motor 211 must also be involved.

Control functions of the propulsion load control device 210 include a propulsion speed control function according to a telegraph signal, an acceleration limit function of the propulsion motor 211 according to the power demand and current consumption, and the propulsion motor 211 There is a function of compensating the starting torque of the generator 211, the output reduction function of the propulsion motor 211 in case of emergency such as parallel connection or drop-out of the generator 211.

The propulsion speed control function according to the telegraph signal controls the load of the propulsion motor 211 when a user's command is transmitted according to the control signal of the telegraph, which is a command device that controls the speed of the marine engine. This is the most basic function of the propulsion load control device 210, and when the operating speed of the ship is determined through a telegraph, the propulsion load control device 210 controls the propulsion motor 211 by outputting a control signal corresponding thereto.

The acceleration limiting function of the propulsion motor 211 according to the power demand and the current power consumption is instantaneously unstable in power supply and demand when a situation in which the power consumption of the propulsion motor 211 changes rapidly occurs as the propulsion load fluctuates. As shown in FIG. 7, the acceleration of the propulsion motor 211 is limited from the time when the telegraph signal is generated, so that the output of the propulsion motor 211 gradually rises. Through the gentle acceleration of the propulsion motor 211 using such a control method, it is possible to prevent the peak load or overload operation of the power generation source.

The starting torque compensation function of the propulsion motor 211 is a propulsion motor ( This is a function to compensate the starting torque so that a current that is much larger than the rated current of 211) does not flow. Compensating the starting torque is also related to the stability of the power generation source supplying power to the propulsion motor 211, and is also related to the stability in terms of mechanical such as coupling of the propulsion motor 211. Therefore, it is desirable to compensate the starting torque of the propulsion motor 211 through a device such as an inverter.

The power reduction function of the propulsion motor 211 in case of emergency such as parallel connection or drop-off of the generator 211 is to reduce the output of the propulsion motor 211 within the allowable power range. Since this is a part that is directly connected to the operating speed of the electric propulsion ship, it can be directly connected to the safety of the ship itself depending on the ship's operation and maritime conditions. Therefore, in order to prevent emergency situations such as instability of the power source, sudden dropout, and power failure, the power generation control unit 100 monitors the stable operation of the power source in real time and controls the propulsion load.

Here, the acceleration limiting function of the propulsion motor 211 according to the power demand and current consumption, and the output reduction function of the propulsion motor 211 in case of emergency such as parallel connection or drop-out of the generator 211 are sufficient stability in the AC-based power system. In order to maintain this, the classification regulations as shown in Fig. 9 are to be observed. That is, in the starting and accelerating of the propulsion motor 211, the frequency and voltage fluctuation rate corresponding to the transient state must be observed until the normal state is reached, and the frequency and voltage fluctuation rate corresponding to the steady state in the situation that has already reached the steady state. Since it must be observed, the propulsion load control device 210 controls the frequency and voltage fluctuation rate according to each state of the propulsion motor 211.

The other load control device 220 controls and manages to improve energy efficiency according to the operating characteristics of all power loads in the ship except for the propulsion motor 211 as shown in FIG. 10. Since the largest and most important load of the electric propulsion ship is the propulsion motor 211, the other load control device 220 is a cooling pump 221, which is a relatively low importance heavy load or intermittent load, engine room. The fan 222, HVAC 223, and other auxiliary devices 224 can be organically operated according to the propulsion load. In particular, by efficiently controlling various power loads so that the power generation control unit 100 maintains sufficient spare power, flexibility in power supply can be secured and energy use efficiency can be improved.

First, the cooling pump 221 is operated for the purpose of cooling the propulsion motor 211, the generator 111 and the generator pipe, and other auxiliary devices, and the motor for driving the pump is included as a main power load. In most cases, a sea water pump and a fresh water pump are used to cool the propulsion motor 211, the generator 111, the generator pipe, and other auxiliary equipment. Redundant power can be secured by improving efficiency and reducing unnecessary power.

The engine room fan 222 serves to supply external air to each equipment that requires air in the engine room, such as a generator pipe, and serves to exhaust air mixed with dust and oil vapor to workers. It is also operated for the purpose of supplying fresh outside air to machinery and workers. The temperature and pressure monitored in the engine room are the main parameters of the engine room supply and exhaust fan system, and accordingly, energy is saved by controlling the number and rotational speed of each supply and exhaust fan in the engine room.

The HVAC 223 supplies fresh air to the residential area where workers reside, and maintains the living area in a comfortable state through temperature and humidity control. It includes a power load such as a motor for driving a fan, an air conditioner, and a heater, and when steam from a boiler is used for heating, the heater may be excluded from the power load. In order to further optimize the conditions such as temperature and humidity of each room in the living area, energy is saved by applying a variable air volume control method.

The other load control device 220 feeds back the power load operation status and energy efficiency, such as heavy load, intermittent load, and other auxiliary devices, to the integrated power control management system 10 through the load control unit 200, so that it can be used with other control devices. It is interlocked. When the non-essential load is selectively cut off in the integrated power control management system 10, these power loads are cut off according to the priority and importance of each power load, and each power load can be switched to the lowest operating mode for energy saving.

One of the main causes of deterioration in power quality in the AC power-based power system of the existing ship is related not only to the voltage, current, and frequency of the generator 111 but also to the operation situation of the power load side. Therefore, the integrated power control management system 10 checks whether the ship's power supply and supply are stably, and when an unintended voltage drop occurs, the output of the power supply source is increased, and when the voltage drops to a state lower than the designed voltage. It performs the protection function of the power generation source. In addition, the integrated power control management system 10 detects whether a leakage current is occurring in the integrated power grid so that the power factor is maintained at 90% or more, and in case of emergency, safety measures are possible.

In addition, the integrated power control management system 10 receives operation data of the power generation stage through the power generation control unit 100, and feedback operation data of the load stage through the load control unit 200, and a large-capacity propulsion motor ( 211) and other power loads compared to heavy loads, intermittent loads with intermittent operation patterns, and other auxiliary devices, while improving power quality, and supplying stable power to the ship's operation and marine environment. It is to control so that it can be achieved.

Data related to the operation status of onboard generation sources and power loads are measured using a smart meter (AMI, Advanced Metering Infrastructure), and the measured power data is used to analyze power consumption and integrate so that users can take appropriate actions. By showing in the monitoring system, it becomes possible to monitor efficiently. At this time, the integrated monitoring system can be configured based on a GUI (Graphic User Interface) with user convenience to monitor the operation status of the ship in real time, and facilitate appropriate judgment, action, and equipment operation.

As described above, the integrated power control management system for a ship according to an embodiment of the present invention has been shown according to the above description and drawings, but this is only described as an example, and various changes within the scope not departing from the technical idea of the present invention And it will be appreciated by those of ordinary skill in the art that changes are possible.

10: Integrated power control management system
100: power generation control unit
110: generator control device
111: generator
120: battery control device
121: battery
131: renewable power generation device
200: load control unit
210: propulsion load control device
211: propulsion motor
220: other load control device
221: cooling pump
222: engine room fan
223: HVAC

Claims (5)

In the integrated power control management system for integrated management of all electric facilities in the ship,
A power generation control unit for controlling and managing a power generation device including at least one of a generator, a battery, and a renewable power generation device;
Propulsion motor, Cooling Pump Control System (CPCS), Engine Room Fan Control System (ERFCS), Heating Ventilating and Air Conditioning System (HVACS), Consists of including; a load control unit for controlling and managing a load device including at least one of the load control system (LCS, Load Control System),
By receiving feedback from the power generation status and operation status of the power load in the ship from the power generation control unit and the load control unit, input and release of each power generation device and selective cut-off of each load are performed,
The power generation control unit,
It is configured to include a generator control device that acquires the load rate and spare power of the generator, which is the main power generation source, in real time, and controls the start and stop of each generator, and energy input and departure according to the operation status of the power load,
It is a power system capable of bidirectional power control using a grid tie inverter or an active front end (AFE).
A function of controlling the power generation device to be operated in one of a generator single operation mode, a battery single operation mode, a generator operation-battery charging mode, and a generator-battery hybrid operation mode, and
An integrated power control management system for ships, characterized in that it performs a function of synchronizing and controlling the generator to a main bus in order to additionally input or leave the generator. The method of claim 1,
The function to control by synchronizing to the main bus,
In the event that a generator needs to be additionally operated due to insufficient power available from the power generation source in operation due to the fluctuation of the power load within the ship, the generator is inserted into the main bus to control the parallel operation of the generator,
The integrated power control management system for ships, characterized in that when the generator is operated with a low load due to a fall of the power load, the generator is sequentially asynchronousized and separated from the main bus. The method of claim 1,
The load control unit,
It is configured to include a propulsion load control device that acquires the operating status of the propulsion motor in real time, and controls the output of the propulsion motor in consideration of the load rate and spare power of the power generation source,
Performs the propulsion load control device control function including the propulsion speed control function according to the telegraph signal, the acceleration limit function of the propulsion motor, the starting torque compensation function, and the output reduction function of the propulsion motor in case of a parallel connection or drop-out of the generator. Integrated power control management system for ships, characterized in that. The method of claim 3,
The acceleration limiting function of the propulsion motor,
When the power consumption of the propulsion motor changes rapidly while the propulsion load changes, the acceleration of the propulsion motor is limited from the point when the telegraph signal is generated to gradually increase the output. Integrated power control management system for ships, characterized in that to prevent. The method of claim 3,
The starting torque compensation function,
Compensating the starting torque so that a current higher than the rated current of the propulsion motor does not flow in case a high torque is required for the initial start of the propulsion motor and the load of the power generating source supplying power increases rapidly. Integrated power control management system for ships characterized by.

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