KR101793571B1 - Water level detection system using solar power supply - Google Patents

Abstract

The disclosed technology relates to a system to sense a water level of a distribution reservoir using a solar power supply device. The system which senses a water level of underground water stored in a water tank of a distribution reservoir, comprises: a first control board to supply power to an underground water motor, sensing insulation resistance of the underground water motor, and vibration generated in the underground water motor, and sensing a state of the underground water motor to transmit information on the state of the underground water motor; and a second control board to drive a sensor using battery charged by solar power generation, sensing an underground water level stored in a water tank of a distribution reservoir, vibration generated in the water tank of the distribution reservoir, and water leakage using the sensor, and transmitting information on the state of the underground water motor and information on the water tank of the distribution reservoir to a monitoring server. As such, the system is able to smoothly be driven by processing data even with small amounts of power.

Description

TECHNICAL FIELD [0001] The present invention relates to a water level detection system using a solar power source,

The disclosed technology relates to a system for sensing the level of a reservoir water tank using a power supply that is charged with solar power.

Commonly used groundwater monitoring systems send information to the supervisor about problems when a problem arises with a motor that lifts groundwater or a problem with a water tank that stores raised groundwater. For example, if the system senses a change in the state of the water tank using a sensor disposed in a water tank every predetermined period, and if a value exceeding a reference value for sensing or a value significantly low is detected, .

In such a surveillance system, conventionally, the consumed electric power for operating the surveillance system is supplied from an external electric power source, or the electric power is generated by itself to produce consumed electric power. For example, when the external power source is connected to the power unit of the system by a cable, the power is always supplied or the removable battery is periodically replaced, or the power is supplied using a power generation method such as solar power generation Can be used.

However, in the method of connecting to the external power source, the cost for installation of the wired cable increases as the location of the external power source and the position where the system is embedded become farther away, and the method of replacing the battery every predetermined period is troublesome There is a problem that it is somewhat inconvenient to apply to the surveillance system because the amount of power obtained by the photovoltaic power generation is insignificant and irregular.

On the other hand, referring to Korean Patent No. 10-0956124 (entitled " integrated monitoring system and method for disaster management in rivers or reservoirs), a water level of a reservoir is measured using a sensor, And the system monitors the status of the reservoir based on the collected data. However, since such a surveillance system must periodically transmit image data having a large capacity, a separate wired / wireless transmission path must be provided, and there is a problem in that loads due to the processing of data collected in a plurality of reservoirs are generated.

The disclosed technology is to provide a system for monitoring a remote location by charging a battery using a solar power device and driving a water level sensing system with charged power.

According to a first aspect of the present invention, there is provided a system for sensing the level of groundwater stored in a water tank of a reservoir, comprising: a power supply for supplying a groundwater motor; an insulation resistance of the groundwater motor; A first control panel for sensing the condition of the groundwater motor and transmitting information about the condition of the groundwater motor, and a battery for charging the photovoltaic power generator to drive the sensor, and using the sensor, And a second control panel for detecting the level of stored ground water, vibration and leakage occurring in the reservoir water tank, information on the condition of the groundwater motor, and information on the reservoir water tank to the monitoring server .

Embodiments of the disclosed technique may have effects that include the following advantages. It should be understood, however, that the scope of the disclosed technology is not to be construed as limited thereby, since the embodiments of the disclosed technology are not meant to include all such embodiments.

According to an embodiment of the disclosed technology, a drainage level sensing system using a solar power source device has a small data processing amount and thus has an effect of smoothly driving the system even with a small amount of power supplied and received through solar power generation.

In addition, there is an effect of easily detecting an abnormal situation occurring in a reservoir water tank.

Further, there is an advantage of maximizing the photovoltaic power generation efficiency by controlling the solar panel forming the cover of the water tank.

In addition, there is an effect that the driving power of the system is smoothly supplied by using two batteries.

1 is a block diagram of a water level detection system using a solar power system according to an embodiment of the present invention.
FIG. 2 is a flow chart illustrating operation in consideration of remaining battery life and remaining battery life according to one embodiment of the disclosed technique.
3 is a block diagram illustrating a power generation unit according to an embodiment of the disclosed technology.
4 is a block diagram illustrating a sensor module in accordance with one embodiment of the disclosed technique.
5 is a block diagram illustrating a controller according to one embodiment of the disclosed technique.
6 is a diagram illustrating an administrator terminal using API-based map data according to an embodiment of the disclosed technology.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, A, B, etc., may be used to describe various components, but the components are not limited by the terms, but may be used to distinguish one component from another . For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that the singular < RTI ID = 0.0 > terms < / RTI > used herein should be interpreted to include a plurality of representations unless the context clearly dictates otherwise. And "comprises ", when used in this specification, specify the presence of stated features, numbers, steps, operations, elements, parts, or combinations thereof, Or combinations thereof, as a matter of course.

Before describing the drawings in detail, it is to be clarified that the division of constituent parts in this specification is merely a division by main functions of each constituent part. That is, two or more constituent parts to be described below may be combined into one constituent part, or one constituent part may be divided into two or more functions according to functions that are more subdivided.

In addition, each of the constituent units described below may additionally perform some or all of the functions of other constituent units in addition to the main functions of the constituent units themselves, and that some of the main functions, And may be carried out in a dedicated manner. Accordingly, the presence or absence of each component described in this specification should be interpreted as a function.

1 is a block diagram of a water level detection system using a solar power system according to an embodiment of the present invention. Referring to FIG. 1, a water level detection system 100 using a solar power supply includes a first control panel 110 and a second control panel 120. The first control panel 110 includes an inverter 111, a reactor 112, a communication unit 113, a sensing unit 114, and a control unit 115.

The first control panel 110 is connected to an external power source to supply power to the groundwater motor. Then, this power source is converted into a predetermined form and supplied to the groundwater motor. In one embodiment, the first control panel may control the inverter 111 to convert the external power source to a form that can be used by the groundwater motor.

On the other hand, the first control panel 110 can control the supply amount of the power supply by controlling the inverter 111 in supplying power to the groundwater motor. In one embodiment, when the groundwater motor is driven, the supply amount of the converted power can be sequentially or gradually increased. Conversely, when the groundwater motor is driven, the power supply can be sequentially reduced or gradually reduced. Therefore, the impact on groundwater motors and pumps is considerably reduced, and as a result, life expectancy of groundwater motors and pumps can be maximized.

According to one embodiment of the disclosed technology, the first control panel 110 includes a reactor 112 capable of replacing the inverter 111 in case the inverter 111, which functions to reduce the load on the groundwater motor, fails, As shown in FIG. It is also possible to supply power to the groundwater motor by replacing the inverter 111 with the reactor 112 in case of emergency. In one embodiment, the first control panel 110 may store a reference value for the performance of the inverter 111 in advance. If the performance of the inverter 111 is determined to be less than the reference value by periodically measuring the performance of the inverter 111, the inverter 111 can be replaced with the reactor 112 provided in advance. Here, the first control panel 110 may measure the insulation resistance value of the inverter 111 in order to measure the performance of the inverter 111. Based on the insulation resistance value, it can be judged whether the performance of the inverter 111 is good or lower than a good state.

Meanwhile, the first control panel 110 can measure the insulation resistance of the groundwater motor when power is supplied to the groundwater motor through the inverter 111. That is, if there is a problem in the power source, it is possible to distinguish between the problem of the inverter 111 and the problem of the groundwater motor. Based on the measured insulation resistance, it is possible to determine whether the groundwater motor has failed. For example, when the operation of the groundwater motor is stopped, the first control panel 110 may measure the insulation resistance of the groundwater motor and compare the insulation resistance of the groundwater motor with the reference value of the insulation resistance of the groundwater motor stored in advance.

In addition, the first control panel 110 can detect vibrations generated in the groundwater motor when the groundwater motor is being driven. For example, the first control panel may include a sensing unit 114 and a control unit 115. The sensing unit 114 is provided with a plurality of vibration sensing sensors. The control unit 115 receives vibration values sensed through the vibration sensing sensors and compares the reference values with respect to previously stored vibrations, Can be judged.

The first control panel 110 transmits information on the state of the groundwater motor to the communication unit 123 of the second control panel 120 using the communication unit 113. For example, the communication units 113 and 123 may exchange data with each other using a wireless communication network, and may transmit status information on the groundwater motor transmitted from the communication unit 113 of the first control panel 110 to the second control panel 120 Is communicated to the monitoring server together with information on the water level of the water tank. On the monitoring server, it is possible to perform remote monitoring based on this information.

In this way, the groundwater motor drives the groundwater to the reservoir water tank disposed at a high place through the pipeline according to the first control panel 110. The first control panel 110 is disposed near the groundwater motor where the groundwater is drawn up and the second control panel 120 is disposed near the reservoir water tank for storing the groundwater drawn up. The first control panel 110 may be disposed near the ground or the ground where the ground water flows and the second control panel 120 may be disposed at a position where the groundwater to be stored in the water tank is cleanly maintained, And may be placed in high mountains or on high ground several kilometers away from the ground to provide groundwater. As a matter of course, it is easy for the first control panel 110, which is close to the ground, to receive the commercial power supplied from outside or the power source of the KEPCO. However, the second control panel 120, The supply of available power is not smooth. Accordingly, the second control panel 120 secures power for driving the sensor through the photovoltaic power generation, and detects the state of the water tank based on the power.

As described above, the second control panel 120 includes a power generation unit 121 that performs solar power generation, a first battery 122 that is charged through the power generation unit, a communication unit 123 that communicates with the first control panel 110, A sensor module 124 that receives power from a battery and senses the level, vibration, and leakage of the water in the reservoir water tank, and a controller 125 for controlling them.

The power generation section 121 produces electric power required to drive the sensor module 124 disposed in the reservoir water tank. 3, the power generation section 121 includes a solar panel 121a for collecting sunlight, an inverter 121b for converting DC power collected according to solar power generation into AC power, A distribution board 121c and a watt hour meter 121d for recording the supplied power value. In one embodiment, the solar panel 121a may be used to collect sunlight and convert it from AC to AC power using the inverter 121b and supply it to the sensor module 124. The watt hour meter 121d can record information on the produced power and the supplied power.

Meanwhile, as shown in FIG. 1, the solar panel 121a is provided in the form of a lid to cover the upper part of the water tank. In one embodiment, the solar panel 121a may be provided in the form of a lid or lid suitable for the shape of a water tank for lifting and storing groundwater by a pump. The solar panel 121a can be detached and attached by a manager as needed to clean the interior of the water tank or replace it with another solar panel.

On the other hand, the solar panel 121a can change the angle depending on the direction in which sunlight is irradiated. In one embodiment, a plurality of solar cells are disposed on the solar panel 110a. The panel portion of the solar panel 110a to which each solar cell is attached is protruded at a predetermined angle, or the solar panel 110a itself is at a predetermined angle Lt; / RTI > For example, the power generation unit 121 may further include an angle control unit (not shown), and the angle control unit may be used to adjust the length of the column supporting the solar panel 110a, The angles of the cells can be adjusted. Since the photovoltaic power generation has the highest light absorptivity when the solar cell receives the solar light vertically, the administrator of the system inputs the value of the angle of the solar panel 110a in advance to the control unit 125 according to time, season, It is possible to appropriately set seasonally.

The first battery 122 is a battery that is charged through the power generation unit 121 and supplies power to the sensor module 124. The first battery 122 is not suitable for supplying the power required by the entire system in consideration of the power supply efficiency of the photovoltaic power generation, and thus supplies the power required for driving the sensor module 124. If a sufficient amount of power is not charged to the first battery 120, power can be supplied using the second battery connected to the first battery 122.

Unlike the first battery 120, the second battery is periodically replaced by a manager, and the amount of the battery is changed from the first battery 120 to the second battery 120. The second battery 120 is a battery that supplies power required by other units of the second control panel 12 except for the sensor module 124. [ Ensure enough. However, when the first battery 122 fails to perform its function, the controller 125 can control the second battery 122 through the control signal so that all the driving power of the second control panel 120 can be distributed. Of course, in this case, the alarm can be immediately transmitted to the monitoring server or the terminal 130 of the administrator through the communication unit 123.

The sensor module 124 receives power from the first battery 122 and senses the water level of the water tank, the vibration occurring in the water tank, and the water leakage. In one embodiment, the water level sensor 124b may be used to sense the water level of the water tank. In another embodiment, the vibration sensor 124c may be disposed at a lower portion of the water tank or a channel through which water is discharged, so that the vibration value can be sensed. In another embodiment, the moisture value of the ground in which the water tank is embedded can be sensed by using the water leakage sensor 124d. The sensor module 124 may include various types of sensors capable of detecting the water level, vibration, and leakage of the water tank.

On the other hand, the sensor module 124 changes the pressure generated due to the water stored in the water tank to the voltage and current signals for detecting the water level of the water tank. Referring to FIG. 4, the sensor module 124 includes a transducer 124a and may convert a signal for pressure through a transducer 124a into a voltage and current signal. And, by using the changed voltage and current signals, it is possible to detect the level of the ground water stored in the water tank. The water level of the groundwater stored in the water tank can be calculated by inputting the voltage and current signals to the water level sensor 124b.

Meanwhile, the sensor module 124 stores a period value for sensing the level of groundwater stored in the water tank. And the change of the water level can be detected according to the period value. For example, the sensor module 124 may further include a timer 124e for storing the period value, and may detect a change in the water level using the period value provided in the timer 124e.

In addition, if the water level of the water tank does not reach the water level threshold, the sensor module 124 detects the vibration sensor 124c in order to prepare for the possibility of occurrence of a sinkhole in an area where the water tank is installed due to natural disasters such as an earthquake or a landslide And detects the vibration occurring in the ground where the water tank is buried. 4, when the result of the water level detection calculated through the water level sensor 124b is less than the pre-stored water level threshold value, the sensor module 124 detects that the water tank is embedded through the vibration sensor 124c It is possible to monitor the occurrence of cracks in a water tank such as a sinkhole by detecting the vibration generated in the stratum.

Referring again to FIG. 4, the sensor module 124 further includes a leak detection sensor 124d. Like the vibration detection sensor 124c, the water leakage sensor 124d may also be a cause of lowering the water level of the water tank due to vibration. Therefore, the water leakage sensor 124c may be contacted with the water layer. In one embodiment, the sensor module 124 controls the water leakage sensor 124d to determine whether leakage of water to the water tank is possible if the result of the water level detection calculated through the water level sensor 124b is less than the pre-stored water level threshold value Can be detected. The water leakage sensor 124d detects the moisture value contained in the stratum by contacting the stratum buried with the water tank. If the sensed moisture value exceeds the reference value, it can be judged that the ground water is leaked from the water tank.

On the other hand, the sensor module 124 can check whether leakage occurs in the reservoir water tank or leakage occurs in the pipeline connected to the water tank by using the leakage detection sensor 124d. In an embodiment, a plurality of leakage detection sensors 124d may be disposed at predetermined intervals in a water tank and a channel, or may be installed in a predetermined range on a connection portion or a vulnerable portion where leakage occurs frequently, and a detection value may be received from each leakage detection sensor It is possible to detect at which part a leak occurs.

The controller 125 senses the lifetime information of the first battery 122 and calculates the remaining life of the first battery 122. The controller 125 receives the result of sensing the water level from the sensor module 124, And generates an alarm if the result value is less than the threshold value. In one embodiment, the controller 125 may sense the life information on the basis of the number of times of charging and discharging of the first battery 122 in sensing the life information of the first battery 122. If the number of times of charging or discharging exceeds the reference value, it can be determined that the battery has reached the end of its life. Of course, it is also possible to refer to the impedance value in determining the life of the battery. If the first battery 122, which is charged through the sunlight, repeats charging and discharging several hundred times as well as a normal battery, the performance of the first battery 122 is degraded to a level far below the original expected performance. The remaining life of the first battery 122 is sensed to prevent performance degradation.

Referring to FIG. 2, it can be seen that the controller 125 operates in consideration of the remaining capacity and remaining life of the first battery 122. In step S210, the controller 125 confirms that the first battery 122 is connected to the system 100. For example, it may be a process of initializing before the system is started. In step S220, the controller 125 determines whether the charged amount of the connected first battery 122 is sufficient. For example, if a sufficient amount of driving power is stored through the power generation unit 121, the amount of charge of the first battery 122 will exceed the reference value, and if not, the first battery 122 will be below the reference value. The controller 125 may check the electrostatic capacitance value of the first battery 122 to determine whether or not the battery is charged. If it is determined that the charged amount exceeds the reference value, the remaining service life of the first battery 122 may be checked in step S230. On the contrary, if the charged amount is less than the reference value, it is determined that the first battery 122 can not be used, and the second battery connected to the first battery 122 can be used in step S250.

In step S230, the control unit 125 checks the number of times of charging and discharging by checking the number of times of variation in the capacitance of the first battery 122 in checking the remaining service life of the first battery 122. [ For example, the remaining life of the first battery 122 can be calculated by checking the number of times of charging and discharging based on the value recorded in the counter 125a, and comparing the number of times of charging and discharging with the reference value based on the deterioration of battery performance. Here, the control unit 125 may refer to the impedance value of the first battery 122 as mentioned above. If it is determined that the remaining life of the first battery 122 is good, it is confirmed that the charged amount of the first battery 122 is equal to or higher than the reference value. Accordingly, the power charged in the first battery 122 is driven As shown in FIG. On the contrary, if the remaining life of the first battery 122 is to be replaced, the control signal can be transmitted to use the second battery in step S250 even if the charged amount of the first battery 122 is secured.

5, a controller 125 according to an embodiment of the disclosed technology includes a counter 125a for recording the number of times of charging and discharging of the first battery 122 to calculate the remaining life of the first battery 122, A processor 125b that generates a control signal for the sensor module 124 and calculates the remaining life of the first battery 122 according to the number of times of charging and discharging, and an alarm generating unit 125c that generates an alarm do. The controller 125 may control the second battery connected to the first battery 122 when the first battery 122 is determined to be discharged based on the number of times of charging and discharging recorded in the counter 125a, Thereby supplying power to the sensor module 124. In this case, the second battery is set so as to supply power to the entire second control panel 120, so that the sensor module 124 is also supplied with electric power instead of the first battery 122 in accordance with the control signal transmitted from the processor 140b. Can be supplied.

The counter 125a included in the controller 125 measures the capacitance of the first battery 122 in order to record the number of times of charging and discharging of the first battery 122. In one embodiment, the counter 125a measures the electrostatic capacity of the first battery 122, determines that the charge is stored if the stored amount of charge is greater than the reference value, and determines the discharged state if the stored amount is less than the reference value , And each of the counter values is checked according to the detection of each state, and it can be recorded as the number of charging and the number of discharging.

On the other hand, if the water level of the water tank does not reach the water level threshold value, the controller 125 generates an alarm. The controller 125 may generate an alarm through the alarm generator 125c and wirelessly transmit the alarm about the drop in the water level generated through the communication unit 123 to the monitoring server and the administrator terminal 130 . The manager can monitor information about the water level of the water tank remotely through the screen of the monitoring server or the screen of his / her terminal 130.

Meanwhile, the system 100 according to the disclosed technique monitors not only the water level of the water tank but also the information sensed through the vibration sensor 124c and the water leakage sensor 124d included in the sensor module 124 It is possible. That is, if it is determined that cracks have occurred in the water tank based on the sensed vibration, or if it is determined that leakage occurs based on the sensed moisture value, it is also possible to generate an alarm for the leakage. 6, the administrator of the system 100 can monitor information on the state of the water tank together with simple information on the position of the water tank using the API-based map data.

For example, an application for exchanging data with the system 100 is installed in the monitoring server or the administrator terminal 130, and the number, location, water level, vibration state, and water level of the water tank are calculated using the API- You can monitor information about battery life. Obviously, since there are a plurality of water tanks installed in each region, distinguishing information such as a unique number for a water tank or a buried address is displayed in the monitoring information, and the state of each water tank Information about the battery life and information may be provided. Accordingly, the system 100 can drive the sensor module 124 using a small amount of power obtained through solar power generation, and an administrator can manage a plurality of water tanks at a remote site through the monitoring information transmitted from the system 100 It is possible.

In monitoring the system 100, an administrator may receive information on the first control panel 110 and information on the second control panel 120 through the monitoring server or the terminal 130. [ Therefore, it is possible to know which control panel has a problem and to know which unit of the control panel has a problem through the monitored information. Therefore, there is an advantage that the time required for maintenance of the system is shortened and the problem is solved accurately.

Although the drainage level sensing system using the solar power supply apparatus according to an embodiment of the disclosed technology has been described with reference to the embodiments shown in the drawings for the sake of understanding, it is merely an example, and those skilled in the art It will be understood that various modifications and equivalent embodiments may be possible. Accordingly, the true scope of protection of the disclosed technology should be determined by the appended claims.

100: Reservoir level detection system 110: First control panel
111: inverter 112: reactor
113: communication unit 114:
115: control unit 120: second control panel
121: power generation section 121a: solar panel
121b: inverter 121c: distribution board
121d: watt hour meter 122: first battery
123: communication unit 124: sensor module
124a: Transducer 124b: Water level sensor
124c: vibration detection sensor 124d: leak detection sensor
124e: Timer 125:
125a: counter 125b: processor
125c: alarm generating unit 130: administrator terminal

Claims (14)

A system for sensing a level of groundwater stored in a reservoir water tank,
A first control panel for supplying power to the groundwater motor, detecting the insulation resistance of the groundwater motor and the vibration generated in the groundwater motor to detect the condition of the groundwater motor and transmitting information about the condition of the groundwater motor; And
The sensor is driven by using a battery charged with solar power and detects the level of groundwater stored in the reservoir water tank, vibration and leakage occurring in the reservoir water tank using the sensor, information on the state of the groundwater motor, And a second control panel for transmitting information on the reservoir water tank to a monitoring server. The method according to claim 1,
Wherein the first control panel includes an inverter and converts power supplied from the outside using the inverter and sequentially supplies the converted power to the groundwater motor while increasing or decreasing the supply of the converted power. The apparatus of claim 1, wherein the first control panel comprises:
And when the groundwater motor is supplied with power, the insulation resistance of the groundwater motor is measured to determine whether the state of the groundwater motor is faulty. The apparatus of claim 1, wherein the first control panel comprises:
Wherein the controller detects the vibration occurring in the groundwater motor when the groundwater motor is in operation and determines whether the state of the groundwater motor is faulty. 3. The apparatus of claim 2, wherein the first control panel comprises:
Wherein the reference value for the performance of the inverter is stored in advance and the inverter is replaced with a reactor provided in advance if it is determined that the performance of the inverter is lower than the reference value. The apparatus of claim 1, wherein the second control panel comprises:
A power generator disposed at an upper portion of the water tank to perform solar power generation;
A first battery charged through the power generation unit to supply power to the system;
A controller for detecting the pressure generated according to the groundwater stored in the water tank and converting the detected pressure into a voltage and a current signal, detecting a level of the water tank based on the voltage and current signals, detecting vibration generated in the water tank, A sensor module for sensing the moisture content of the buried ground; And
The method includes calculating lifetime of the first battery based on the lifetime information of the first battery, receiving data on the level, vibration, and moisture sensed by the sensor module, comparing the lifetime with the threshold, And a controller for generating an alarm. The method according to claim 6,
Wherein the controller controls the second battery connected to the first battery to supply power to the system when it is determined that the first battery is discharged. 7. The power unit according to claim 6,
Solar panels to collect sunlight;
An inverter for converting the DC power collected according to solar power generation into AC power;
A distribution board for supplying the AC power to the sensor module; And
And a watt hour meter for recording data on the supplied electric power. 9. The power generation apparatus according to claim 8,
And an angle control unit for adjusting the angle of the plurality of solar cells provided in the solar panel according to a direction in which sunlight is irradiated. 7. The apparatus of claim 6,
A counter for recording the number of times of charging and discharging of the first battery;
A processor for generating a control signal for the sensor module and calculating a remaining lifetime of the first battery according to the number of times of charging and discharging; And
And a communication unit for transmitting the alarm. 11. The method of claim 10,
Wherein the counter measures the electrostatic capacity of the first battery and counts the number of times of charging and discharging for the first battery. The method according to claim 6,
And the control unit wirelessly transmits the alert to the monitoring server and the administrator terminal. 13. The method of claim 12,
Wherein the monitoring server and the manager terminal receive information on a position where the water tank is buried in advance using API-based map data, and sequentially store the alarms transmitted from the controller. The method according to claim 6,
Wherein the control unit controls the water leakage sensor included in the sensor module to detect whether the water tank is leaking if the result of the water level detection is less than the pre-stored water level threshold value.

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