Abstract:
Aspects of the present invention relate to a device and method for controlling a floating structure of a solar power generating device, which can generate electricity from solar power of incident light while tracking the position of the sun in a state in which it floats on the water.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to International Application No. PCT/KR2012/002000 filed Mar. 21, 2012, which claims priority to Korean Patent Application Nos. 10-2011-0024722 filed Mar. 21, 2011, 10-2011-0053352 filed Jun. 2, 2011, and 10-2011-0071361 filed Jul. 19, 2011, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Aspects of the present invention relate to a device and method for controlling a floating structure of a solar power generating device, which can generate electricity from solar power of incident light while tracking the position of the sun in a state in which it floats on the water. 
     2. Description of the Related Art 
     Recently, a floating structure equipped with a solar power generating device is operated to be floatable in reservoir or lake. 
     In general, a solar power generation method directly converts solar power into electrical energy by a solar cell. Differently from a solar heat generation method for generating energy using heat energy of sunlight, the solar power generation method generates electrical energy directly from sunlight by the solar cell formed of semiconductors. 
     In detail, the conventional solar power generating device includes a floating structure that is floatable on the water, a solar cell module installed on the floating structure, having a plurality of solar cells connected to each other and converting sunlight energy incident from the sun into electrical energy, and a floating structure rotating unit rotating the floating structure along the solar orbit. 
     With this configuration, since electricity generation efficiency of the solar cell module depends upon an incidence angle of sunlight, it is necessary to appropriately rotate the floating structure using the floating structure rotating unit according to the seasonal time zone. 
     The floating structure rotating unit is operated to control its rotation by cross-linking a pair of power units installed on the ground to both edges of the floating structure using a pair of wires and unwinding and winding of the wires. Since unwinding and wound amounts of the pair of wires cannot be precisely measured, it is difficult to accurately control the rotation of the floating structure. 
     The water level of the reservoir or lake may be changed by environmental factors. Accordingly, tension may be applied to the wires of the floating structure rotating unit. If the tension applied the wires exceeds a tensile strength, the wires may be broken. Thus, a change in the water level of the reservoir or lake may impair stability of the floating structure. 
     A conventional solar power generating device is configured such that a post is inserted to stand at the center of a floating structure to guide up-down movement of the floating structure while minimizing vibration or shock of the floating structure due to water conditions and the post is firmly supported by a separate support unit. 
     Therefore, the floating structure can stably rotate about the post along a predetermined track of sunlight. In a case where the floating structure rotating unit is damaged due to a big wave or wind, a rotation restraining state is released, so that an incidence angle with respect to the solar cell module may not be controlled and solar power generation may not be stably operated. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention provide a device and method for controlling a floating structure of a solar power generating device, which can precisely control rotation of the floating structure. 
     Other aspects of the present invention provide a device for controlling a floating structure, which can maintain stability even when a water level change occurs in the reservoir or lake. 
     Aspects of the present invention further provide a device for controlling a floating structure, which can temporarily support the floating structure when a floating structure rotating unit is damaged. 
     In accordance with one aspect of the present invention, there is provided a device for controlling a floating structure of a solar power generating device, the device including a floating structure ( 110 ) installed to be floatable on the water (W), a post ( 120 ) passing through the center of the floating structure ( 110 ) to then fixedly rise and inducing ascending and descending of the floating structure ( 110 ) according to the water level, a floating structure rotating unit ( 130 ) including a pair of first and second power devices ( 131 ,  132 ) installed on the ground, and a pair of first and second wires ( 133 ,  134 ) having both ends connected to the first and second power devices ( 131 ,  132 ) and the floating structure ( 110 ) to cross each other, a wire winding measurement unit ( 140 ) fixedly installed on the ground to correspond to the first wire ( 133 ) and measuring a wound amount, and a control unit ( 150 ) connected to the wire winding measurement unit ( 140 ) and controlling forward and backward actuation of the pair of first and second power devices ( 131 ,  132 ) according to the reference angle depending on the seasonal solar orbit. 
     The wire winding measurement unit ( 140 ) may include a fixing member ( 141 ) fixedly installed on the ground, an extending member ( 143 ) supported at one side of the fixing member ( 141 ) and extending in a lengthwise direction of the first wire ( 133 ), a plurality of rollers ( 145 ) installed at one side of the extending member ( 143 ) so as to allow the first wire ( 133 ) to be wound at a constant interval and rotatably installed according to winding of the first wire ( 133 ), and a sensor member ( 147 ) fixed at the other side of the extending member ( 143 ) and sensing the number of turns of one of the plurality of rollers ( 145 ). 
     The sensor member ( 147 ) may include a bar ( 147   a ) extending to the outside of the one of the plurality of rollers ( 145 ) and rotating in an interlocked manner, and a sensor ( 147   b ) installed at the other side of the extending member ( 143 ) so as to correspond to the bar ( 147   a ). 
     The sensor ( 147   b ) may be electrically connected to the control unit ( 150 ). 
     The device may further include a water level measurement unit ( 160 ) positioned in an internal space ( 122 ) of the post ( 120 ) and measuring the water level. 
     An air inlet hole ( 124 ) and a water inlet hole ( 126 ) may be formed in the post ( 120 ), the air inlet hole ( 124 ) formed at an upper portion of the post ( 120 ) and allowing the inflow of air into the internal space ( 122 ), and the water inlet hole ( 126 ) formed at a lower portion of the post ( 120 ) and allowing the inflow of water into the internal space ( 122 ). 
     The water level measurement unit ( 160 ) may include a buoyancy member ( 162 ) positioned on the surface of water induced into the internal space ( 122 ) of the post ( 120 ), and a distance measurement sensor ( 164 ) mounted in an internal space of the floating structure ( 110 ) and measuring the distance of the buoyancy member ( 162 ). 
     The device may further include a rotation preventing wire ( 170 ) having a center wound around either of top and bottom ends of the post ( 120 ) and both ends engaged with both sides of the floating structure ( 110 ). 
     Both ends of the rotation preventing wire ( 170 ) may be loosely installed such that rotation of the floating structure ( 110 ) is not interfered. 
     A wire fixing member ( 176 ) may be installed in the post ( 120 ), the wire fixing member ( 176 ) fixing a winding position of the rotation preventing wire ( 170 ). 
     In accordance with another aspect of the present invention, there is provided a method for controlling a floating structure of a solar power generating device, the method including a first step (S 10 ) of actuating first and second power devices ( 131 ,  132 ) forward and backward, a third step (S 30 ) of measuring an rotation angle of the floating structure ( 110 ) based on an wound amount of the first wire ( 133 ), a fourth step (S 40 ) of comparing the measured rotation angle of the floating structure ( 110 ) with a reference angle input according to the seasonal solar orbit, and a fifth step (S 50 ) of fixing the floating structure ( 110 ) by stopping the actuating of the first and second power devices ( 131 ,  132 ). 
     The method may further include a second step (S 20 ) of measuring a rotation time of a roller ( 145 ) having a bar ( 147   a ) installed therein when the first and second power devices ( 131 ,  132 ) are actuated forward and backward. 
     As described above, in the device and method for controlling a floating structure of a solar power generating device, rotation of the floating structure can be accurately controlled according to the solar orbit. 
     In addition, the device for controlling a floating structure of a solar power generating device according to the present invention can maintain stability even when a water level change occurs in the reservoir or lake. 
     Further, the device for controlling a floating structure of a solar power generating device according to the present invention can temporarily support the floating structure in a safe manner even when the floating structure is uncontrollable by broken wires due to bad weather, thereby preventing a solar power generating device from being damaged and operating solar power generation in a stable manner. 
     Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects, features and advantages of the present invention will be more apparent from the following detailed description in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a floating structure controlling device according to an embodiment of the present invention; 
         FIG. 2  is an enlarged view illustrating one side of a wire winding measurement unit of  FIG. 1 ; 
         FIG. 3  is a side view illustrating the other side of the wire winding measurement unit  FIG. 2 ; 
         FIG. 4  is a flowchart illustrating a controlling method performed by a floating structure controlling device according to an embodiment of the present invention; 
         FIG. 5  is a laterally cross-sectional view of a floating structure controlling device according to another embodiment of the present invention; 
         FIG. 6  illustrates essential parts of  FIG. 5 ; 
         FIG. 7  illustrates operating states of the floating structure shown in  FIG. 5 ; 
         FIG. 8  is a laterally cross-sectional view of a floating structure controlling device according to still another embodiment of the present invention; 
         FIG. 9  illustrates a portion ‘A’ of  FIG. 8 ; 
         FIG. 10  is an enlarged view of a wire fixing member of  FIG. 9 ; and 
         FIG. 11  is a laterally cross-sectional view of a modified embodiment of the floating structure controlling device shown in  FIG. 8 . 
     
    
    
     Hereinafter, a device for controlling a floating structure according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Before the present invention is described terms or words used in the specification and claims of the present invention should not be restrictively construed as having the same meanings as those commonly used or those defined in dictionaries but should be interpreted as having meanings and concepts that are consistent with their meanings and concepts in the context of the spirit or scope of the present invention. 
     Therefore, the constitution shown in the embodiments and drawings of the present invention are provided only for illustration of the best exemplary embodiment of the present invention but are not provided to completely encompass the spirit or scope of the present invention. Accordingly, it is to be understood that various equivalents and modifications that can be substituted at the time of the filing date of the present application may be made to the invention. 
     As shown in  FIG. 1 , the floating structure controlling device according to an embodiment of the present invention includes a floating structure  110 , a post  120 , a floating structure rotating unit  130 , a wire winding measurement unit  140  and a control unit  150 . 
     The floating structure  110  is formed using a material having buoyancy so as to be floatable on the water (W) and a through-hole  110   b  may be formed at a predetermined position, preferably at the center of the floating structure  110 . 
     The floating structure  110  may take any shape so long as it has buoyancy without being limited to a particular shape. In the following description, the floating structure  110  will be described by way of example with regard to a case where the floating structure  110  is shaped of a rectangular plate. 
     A solar energy generating device  115  may be mounted on a top surface of the floating structure  110 . The solar energy generating device  115  may include a solar cell module, a power conversion device (not shown), and a storage battery (not shown). 
     The solar cell module is constituted of a plurality of solar cells connected to each other as a module and may be controlled by a support stand ( 117  of  FIG. 5 ) capable of varying angles of the solar cell module to allow sunlight to be incident in a vertical direction. 
     The power conversion device is connected to the solar cell module and converts DC power into AC power, the DC power having the voltage and current generated by the solar cell module not constant. 
     The storage battery is connected to the power conversion device and is capable of accumulating electricity. 
     In addition, the floating structure  110  includes a slot hole  110   a  having a predetermined section pierced such that a water surface and a bottom portion of the solar cell module make contact with each other. Low-temperature gas on the water surface is brought into contact with the heated bottom portion of the solar cell module by convection, thereby cooling the solar cell module. 
     The post  120  is disposed to stand and guides ascending and descending of the floating structure  110  according to the water level. 
     In particular, the post  120  penetrates the through-hole  110   b  of the floating structure  110  and has one end fixed to the bottom of the reservoir or lake and the other end upwardly protruding from the floating structure  110 . Thus, a portion of the post  120  is positioned in water, that is, below the water surface, and the other portion of the post  120  is positioned outside the water. 
     Meanwhile, the floating structure rotating unit  130  includes a pair of first and second power devices  131  and  132  installed on the ground, and a pair of first and second wires  133  and  134  having opposite ends installed at the first and second power devices  131  and  132  and a fixing bar  116  of the floating structure  110  to be cross-linked with each other. 
     The pair of first and second power devices  131  and  132  may include a motor (not shown) generating power, a decelerator (not shown), a clutch (not shown) for transmitting or interrupting power of the motor, and a brake (not shown) stopping the motor. 
     The first power device  131  and the second power device  132  are actuated forward and backward, respectively, thereby rotating the floating structure  110 . 
     Meanwhile, as shown in  FIGS. 2 and 3 , the wire winding measurement unit  140  is installed on the ground so as to correspond to the first wire  133 , and measures a wound amount on a real time basis. 
     The wire winding measurement unit  140  includes a fixing member  141  fixedly installed on a block structure B on the ground, an extending member  143  supported to one side of the fixing member  141  and extending in a lengthwise direction of the first wire  133 , a plurality of rollers  145  installed at one side of the extending member  143  to allow the first wire  133  to be wound in a constant interval and rotatably installed according to winding of the first wire  133 , and a sensor member  147  fixed at the other side of the extending member  143  and sensing the number of revolutions of one of the plurality of rollers  145 . 
     The fixing member  141  includes an ‘L’ shaped support unit  141   a  and a standing unit  141   b  upwardly installed on the support unit  141   a.    
     The extending member  143  is shaped of a rectangle having a predetermined length and fixedly installed at the standing unit  141   b.    
     The shape of the extending member  143  is not limited to the rectangle and various changes may be made to the shape of the extending member  143  so long as it can support the plurality of rollers  145 . 
     The plurality of rollers  145  are rotatably supported to a fixed shaft  143   a  installed on a top surface of the extending member  143  to be spaced apart from each other in a lengthwise direction, and are arranged at different heights in a zigzag configuration, thereby establishing a winding state of the first wire  133  more firmly. 
     Here, the wound amount of the first wire  133  can be estimated per one revolution of the roller  145 . 
     The sensor member  147  includes a bar  147   a  integrally extending to the outside of the one of the plurality of rollers  145  and rotating in an interlocked manner, and a sensor  147   b  supported to a bracket  143   b  installed at the other side of the extending member  143  and corresponding to the bar  147   a.    
     Here, the sensor  147   b  may include one of known sensors, such as a proximity sensor or an optical sensor, and is electrically connected to the control unit  150  by a cable (C). For example, when a proximity sensor is used as the sensor  147   b , the bar  147   a  is preferably made of a metal. 
     The control unit  150  is connected to the wire winding measurement unit  140  and the first and second power devices  131  and  132  and estimates a rotation angle of the floating structure  110  based on the number of revolutions of one of the plurality of rollers  145  having the bar  147   a  installed therein. In addition, the control unit  150  controls forward and backward actuation of the pair of first and second power devices  131  and  132  in units of several seconds or several minutes according to reference angles pre-programmed by seasonal and temporal solar orbits. 
     Further, when the first and second power devices  131  and  132  are actuated forward and backward, the control unit  150  checks whether one of the plurality of rollers  145  having the bar  147   a  installed therein rotates normally or not, thereby safely controlling the floating structure rotating unit  130 . 
     That is to say, a reference time, which can be compared with the rotation time of the one of the plurality of rollers  145  having the bar  147   a  installed therein, is input to the control unit  150 . If the rotation time exceeds the reference time, it is determined that the one of the plurality of rollers  145  having the bar  147   a  installed therein does not rotate normally, and the actuation of the first and second power devices  131  and  132  is forcibly stopped, thereby preventing over-rotation of the floating structure  110 . 
     Here, the control unit  150  may control a greater torque to be applied to the first power device  131  than to the second power device  132  to allow the second wire  134  to be unwound by the wound first wire  133  with a tension. 
     In addition, the floating structure  110  according to the present invention may further include a bearing  125  for rotatably supporting the floating structure  110  between the through-hole  110   b  of the floating structure  110  and the circumferential surface of the post  120 . 
     In the embodiment of the present invention, an element for rotatably supporting the floating structure  110  is limited to the bearing  125 , but any element can be adopted so long as it can smoothly rotate the floating structure  110  with respect to the post  120 . 
     That is to say, the floating structure  110  includes gear teeth (not shown) formed on its outer peripheral surface, an interlocking gear (not shown) engaged with the gear teeth and a driving gear (not shown) engaged with the interlocking gear to increase a rotation torque by adjusting a gear ratio, thereby easily rotating the floating structure  110 . 
     Hereinafter, a method for controlling the floating structure according to an embodiment of the present invention will be described with reference to the accompanying drawings. 
     As shown in  FIG. 4 , the floating structure controlling method according to an embodiment of the present invention includes a first step (S  10 ) of actuating first and second power devices  131  and  132  forward and backward in a predetermined time unit, a second step (S 20 ) of measuring a rotation time of a roller  145  having a bar  147   a  installed therein when the first and second power devices  131  and  132  are actuated forward and backward, a third step (S 30 ) of measuring an rotation angle of the floating structure  110  based on an wound amount of the first wire  133 , a fourth step (S 40 ) of comparing the measured rotation angle of the floating structure  110  with a reference angle input according to the seasonal solar orbit, and a fifth step (S 50 ) of fixing the floating structure  110  by stopping the actuating of the first and second power devices  131  and  132 . 
     In the first step (S  10 ), motors of the first and second power devices  131  and  132  are actuated forward and backward for a predetermined time, that is, in units of several seconds or several minutes, to allow the solar energy generating device  115  to move along the solar orbit, thereby rotating the floating structure  110 . 
     That is to say, in order to rotate the floating structure  110  in a clockwise direction (the solar orbit) of  FIG. 1 , the first wire  133  is wound by driving the motor of the first power device  131  while the second wire  134  is unwound by driving the motor of the second power device  132 . 
     In the second step (S 20 ), when the first and second power devices  131  and  132  are actuated forward and backward, a rotation time of one of the plurality of rollers  145  having a bar  147   a  installed therein is measured using a sensor  147   b  and is compared with a reference time input to the control unit  150 , thereby determining whether the one of the plurality of rollers  145  having the bar  147   a  installed therein rotates normally or not. 
     If the rotation time of the one of the plurality of rollers  145  having the bar  147   a  installed therein exceeds the reference time of the control unit  150 , it is determined that the one of the plurality of rollers  145  having the bar  147   a  installed therein does not rotate normally. Therefore, the actuating of the first and second power devices  131  and  132  is forcibly stopped, the wire winding measurement unit  140  is checked and repaired, and the process goes back to the first step (S  10 ). 
     Next, in the third step (S 30 ), the wire winding measurement unit  140  estimates the wound amount of the first wire  133  based on the number of revolutions of the one of the plurality of rollers  145  having the bar  147   a  installed therein, thereby measuring the rotation angle of the floating structure  110  on a real time basis. 
     In addition, in the fourth step (S 40 ), the control unit  150  receives the number of revolutions of the one of the plurality of rollers  145  and compares reference angles set according to seasonal and temporal solar orbits to control the motors of the first and second power devices  131  and  132  to be continuously actuated until the rotation angle of the floating structure  110  reaches a predetermined level. 
     That is to say, if the reference angle is 4°, the rotation angle of the floating structure  110  can be controlled based on the number of revolutions of the one of the plurality of rollers  145  having the bar  147   a  installed therein. 
     If the rotation angle of the floating structure  110  is 2° per one revolution of the one of the plurality of rollers  145 , the motors of the first and second power devices  131  and  132  are continuously actuated until the one of the plurality of rollers  145  having the bar  147   a  installed therein rotates twice. 
     Thereafter, if the number of revolutions of the one of the plurality of rollers  145  is 2, the actuating of the motors of the first and second power devices  131  and  132  is immediately stopped by a brake, thereby fixing the floating structure  110   
     The above-described process (the fourth and fifth steps) are repeatedly performed in units of several seconds or several minutes before the sunset, thereby accurately controlling the rotation of the floating structure  110  according to the solar orbit. 
     After the sunset, the motors of the first and second power devices  131  and  132  are actuated forward or backward which is opposite to that in the above actuation, thereby restoring the floating structure  110  to a morning start position. 
     Meanwhile, as shown in  FIG. 5 , a floating structure controlling device according to another embodiment of the present invention further includes a water level measurement unit  160 . 
     Here, the post  120  has an internal space  122  and is shaped of a pillar having a laterally cross section corresponding to the through-hole  110   b  to penetrate the through-hole  110   b  of the floating structure  110 . 
     The post  120  may further include an air inlet hole  124  and a water inlet hole  126 . 
     The air inlet hole  124  is formed at an upper portion of the post  120 . That is to say, the air inlet hole  124  is positioned outside the reservoir or lake, to allow the air present outside the water to be induced into the internal space  122 . 
     The water inlet hole  126  is formed at a lower portion of the post  120 . That is to say, the water inlet hole  126  is positioned in water to allow water to be induced into the internal space  122 . 
     Therefore, the water level of the internal space  122  of the post  120  may be equal to the height of the reservoir or lake. 
     Referring to  FIG. 6 , the water level measurement unit  160  is positioned in the internal space  122  of the post  120  and measures the water level of the reservoir or lake. 
     In more detail, the water level measurement unit  160  may include a buoyancy member  162  and a distance measurement sensor  164 . 
     The buoyancy member  162  is formed using a material having buoyancy and is positioned on a surface of the water induced into the internal space  122  of the post  120 . The buoyancy member  162  may take any shape so long as it is sized to be positioned within the internal space  122 . 
     The distance measurement sensor  164  is mounted in the internal space  122  of the post  120 , detects the buoyancy member  162  and measures a distance from the buoyancy member  162  to the distance measurement sensor. 
     In more detail, the distance measurement sensor  164  is mounted in the internal space  122  of the post  120 , specifically, above the buoyancy member  162 . That is to say, the distance measurement sensor  164  is mounted at a point spaced from the bottom surface of the reservoir or lake at a predetermined height, measures a distance between the distance measurement sensor and the buoyancy member  162 , and calculates a difference of the above distance, thereby measuring the water level of the reservoir or lake. 
     In addition, the distance measurement sensor  164  has a waterproofing function and is mounted under the buoyancy member  162  (that is, in water) if it can be operated in water, thereby measuring the water level by measuring the distance between the distance measurement sensor and the buoyancy member. 
     As described above, since the buoyancy member  162  and the distance measurement sensor  164  are positioned in the internal space  122  of the post  120 , the surface of the water induced into the internal space  122  is not affected by waves occurring on the water surface of the reservoir or lake. 
     That is to say, since the buoyancy member  162  is not subjected to up-down movement by the wave, the distance measurement sensor  164  can more accurately measure the distance from the buoyancy member  162 , thereby accurately measuring the water level of the reservoir or lake. 
     Hereinafter, a method for controlling a floating structure further including a water level measurement unit  160  according to the present invention will be described with reference to the accompanying drawings. 
     As shown in  FIG. 7 , a control unit  150  determines a value measured by the water level measurement unit  160  and actuates first and second power devices  131  and  132  to adjust lengths of the first and second wires  133  and  134 . 
     That is to say, the control unit  150  is mounted at the reservoir or lake side to then be connected to a distance measurement sensor  164  to determine the measured value received from the distance measurement sensor  164  and controls the actuations of the first and second power devices  131  and  132  based on the determination result. The control unit  150  and the distance measurement sensor  164  may be connected to each other on line. 
     In detail, the floating structure  110  moves up and down according to a change in the water level of the reservoir or lake. Here, the first and second wires  133  and  134  connected to the floating structure  110  extend to generate tension (T), and if the generated tension exceeds a tensile strength of the first and second wires  133  and  134 , the first and second wires  133  and  134  may be broken. 
     Therefore, the control unit  150  receives data measured by the water level measurement unit  160  on line and compares the data with a value input to the control unit  150  for determination. In addition, the control unit  150  actuates the first and second power devices  131  and  132  to unwind the first and second wires  133  and  134  wound around a motor device  174  to maintain the tension to be lower than the tensile strength of the first and second wires  133  and  134 , thereby preventing the first and second wires  133  and  134  from being broken. In addition, the control unit  150  may be connected to the first and second power devices  131  and  132  by wires (not shown) for transmitting electrical signals. 
     Therefore, since the floating structure  110  is not affected by the wave formed in the reservoir or lake, the water level can be accurately measured, and based on the measured water level, lengths of the first and second wires  133  and  134  can be controlled according to the change in the water level of the reservoir or lake, thereby maintaining stability of the floating structure. 
     Meanwhile, as shown in  FIG. 8 , the floating structure controlling device may further include a rotation preventing wire  170 . 
     The rotation preventing wire  170  is wound around one of top and bottom end of the post  120  (the bottom end in this embodiment) and the both ends are engaged with a connecting member  175  of the floating structure  110 . 
     Preferably, the both ends of the rotation preventing wire  170  are loosely installed such that rotation of the floating structure  110  is not interfered. 
     Here, as shown in  FIG. 9 , in order to fix a winding position of the center of the rotation preventing wire  170 , at least one wire fixing member  176  may further be fixedly installed at the post  120 . 
     As shown in  FIG. 10 , the wire fixing member  176  has a ‘U’ shaped cross section. In a case where both ends of the wire fixing member  176  are fixed, a space is formed in the wire fixing member  176 . 
     Therefore, the rotation preventing wire  170  passes the space of the wire fixing member  176  and placed to enable a central winding portion of the rotation preventing wire fixed on a point of the floating structure  110  to be to be safely maintained. 
     Here, the same rotation preventing effect can be achieved such that a pair of wire fixing members  176  are fixedly installed on the post  120  in a connecting loop (not shown), one end of the rotation preventing wires  170  is connected to the connecting loop and the other end of the rotation preventing wire  170  is cross-linked to the connecting member  175  of the floating structure  110 . 
     In addition, as shown in  FIG. 11 , the same rotation preventing effect can also be achieved such that a pair of ground fixing members  177 , instead of the wire fixing member  176  or the connecting loop, are separately installed provided on the bottom of a water depth, one ends of the pair of rotation preventing wires  170  are connected to each other and the other ends of the rotation preventing wires  170  are cross-linked to the connecting member  175  of the floating structure  110 . 
     In this case, both ends of the rotation preventing wire  170  may be loosely installed such that rotation of the floating structure  110  is not interfered. In particular, the post  120  and the pair of ground fixing members  177  are preferably arranged on a line. 
     Here, the same effect can be expected even when both ends of the ground fixing member  177  are loosely installed on the ground to be positioned in the same line with the post  120 , rather than on the bottom of the water depth, such that the rotation of the floating structure  110  is not interfered. 
     Hereinafter, a method for controlling a floating structure further including a rotation preventing wire  170  according to the present invention will be described with reference to the accompanying drawings. 
     In a case where there is a big wave or wind due to an aggravating water environment, first and second wires  133  and  134  of a floating structure rotating unit  130  may be broken. 
     In such a case, a rotation restraining state in which a floating structure  110  is restrained by the first and second wires  133  and  134  may be released. As the result, an incidence angle with respect to a solar cell module may not be controlled, solar power generation may not be stably operated, and concerns of major facilities being damaged may be raised. 
     In this case, the floating structure  110  rotates in an uncontrollable manner in one direction by the wind and wave. Here, the rotation preventing wire  170  having both ends thereof loosely installed at both sides of the floating structure  110  is tightened to restrain rotation of the floating structure  110 , thereby temporarily supporting the floating structure  110  in an emergent situation in which the first and second wires  133  and  134  of the floating structure rotating unit  130  are broken. 
     Therefore, even when the floating structure  110  is uncontrollable by the broken first and second wires  133  and  134  due to bad weather, the floating structure  110  can be temporarily supported in a safe manner, thereby preventing a solar power generating device and operating solar power generation in a stable manner after repairing an actuating member. 
     Although exemplary embodiments of the present invention have been described in detail hereinabove, it should be understood that many variations and modifications of the basic inventive concept herein described, which may appear to those skilled in the art, will still fall within the spirit and scope of the exemplary embodiments of the present invention as defined by the appended claims.