Patent Publication Number: US-2010109326-A1

Title: Fan unit for wind power generator and wind power generator

Description:
TECHNICAL FIELD  
     The present invention relates to a fan unit for a wind power generator and a wind power generator. 
     BACKGROUND ART  
     The range of air temperatures in which the wind power generator is operated is generally from minus 30 degrees centigrade to plus 40 degrees centigrade. Accordingly, it is necessary to control the temperature of the internal equipment of the wind power generator such as main bearings, a speed increasing gear, a generator, a transformer and an inverter, for example, to within a range of the standard temperature. 
     In order to perform such temperature control, an oil piping system for a vane pitch system, the speed increasing gear, the main bearing and the like and a cooling piping system for the inverter and the like are respectively provided with heaters and coolers as temperature control systems (refer to Patent Document 1). 
     The cooler is provided with a cooling fan for ventilating the cooler. Each of the heater and the cooling fan is controlled to be turned on and off based on the set temperatures. 
     Patent Document 1: Japanese Unexamined Patent Application, Publication No. Sho-58-065977 
     DISCLOSURE OF INVENTION  
     A fan for ventilating a windmill and a fan for cooling the cooler fan are provided in a nacelle. This causes a problem where a pressure loss at an air intake port of the fan or a discharge port of the fan increases according to the internal structure of the nacelle or the placement of the fan, and the ventilation performance and the cooling performance can not be sufficiently exerted. 
     Specifically, the flow of the air is asymmetrical to the rotation axis of the fan when the internal components of the nacelle are placed to obstruct the air flow into the fan. This causes a problem where a pressure loss at an air flow port of the fan is increased. 
     In the case where a heat exchanger is mounted to the fan such as with the cooling fan, the flow of the air flowing into the fan is asymmetrical, and is uneven. This causes a problem where a pressure loss at the heat exchanger increases. 
     Further, in the case of discharging the air to the rear side of the nacelle by means of the fan, there is a problem where an external wind flowing outside the nacelle influences the flow of the air flowing into the fan, and the ventilation performance and the cooling performance can not be sufficiently exerted. 
     In other words, the influence of the external wind around the nacelle causes back pressure on the rear side of the nacelle, and the back pressure varies according to the changes of the external wind speed. Such variation of the back pressure causes a change of an operation point of the fan and the amount of fan wind changes. Accordingly, air flowing into the fan is affected, which causes a problem where the ventilation performance and the cooling performance can not be sufficiently exerted. 
     The invention is to solve such problems. An object of the invention is to provide a fan unit for a wind power generator and a wind power generator, which are capable of preventing a loss of flow at a flowing port from increasing and capable of preventing a pressure loss of a heat exchanger from increasing. 
     In order to achieve the object, the invention provides the following means. 
     In accordance with the first aspect of the invention, provided is a fan unit for a wind power generator having an axial fan for discharging air in a nacelle of the wind power generator to the rear side of the nacelle, the axial fan being provided on a floor of the nacelle, and an equipment of the wind power generator provided in front of the axial fan in a direction of a rotation axis, the fan unit for a wind power generator comprising a rectification part for adjusting distribution of a flow rate of air flowing into the axial fan. 
     In accordance with the first aspect of the invention, a rectification part adjusts distribution of the flow rate of the air detouring around an equipment of the wind power generator to flow into the axial fan. This allows a pressure loss at an air intake port or a discharge port of the axial fan to be prevented from increasing. Especially, the pressure loss at an air intake port or a discharge port of the axial fan can be prevented from increasing by adjusting the distribution of the flow rate of the air so as to be symmetrical to the rotation axis of the axial fan. 
     On the other hand, in the case of guiding the air to be sent by means of the axial fan to the heat exchanger, a pressure loss of the heat exchanger is prevented from increasing since the distribution of the flow rate of the air has been adjusted. 
     In the first aspect of the invention, a structure in which plural flow speed sensors for measuring a flow speed of the air flowing into the axial fan are provided and the rectification part adjusts the distribution of the flow rate of the air on the basis of the flow speed of the air measured by means of the flow speed sensors, is preferable. 
     In accordance with such a structure, measuring the speed of a flow of the air at plural places allows the distribution of the flow rate of the air flowing into the axial fan to be estimated. Accordingly, controlling the rectification part on the basis of the measured speed of the flow of the air can surely prevent a pressure loss at the air intake port or the discharge port of the axial fan from increasing. 
     In the above structure, it is preferable that the rectification part is a bell mouth and is provided movably in the direction of the rotation axis of the axial fan. 
     In accordance with such a structure, changing the location of the bell mouth in the direction of the rotation axis allows the distribution of the flow rate of the air flowing into the axial fan to be adjusted. 
     In the above structure, it is preferable that the rectification part is a guide for guiding air to the axial fan and is provided movably in the direction of the rotation axis of the axial fan. 
     In accordance with such a structure, changing the location of the guide in the direction of the rotation axis allows the distribution of the flow rate of the air flowing into the axial fan to be adjusted. 
     In the above structure, it is preferable that a first perforated plate provided with holes having approximately the same diameter, the holes evenly distributed, and a second perforated plate provided with holes gradually increasing in diameter in one direction are provided in the rectification part and the first perforated plate and the second perforated plate relatively move to adjust the distribution of the flow rate of the air flowing into the axial fan. 
     In accordance with such a structure, moving the first perforated plate and the second perforated plate relatively allows the area of overlap between holes of the first perforated plate and holes of the second perforated plate to be adjusted to adjust the distribution of the flow rate of the air flowing into the axial fan. 
     In the second aspect of the invention, provided is a wind power generator provided in a nacelle with the fan unit for a wind power generator according to the invention. 
     In accordance with the second aspect of the invention, a rectification part adjusts distribution of the flow rate of the air detouring around an equipment of the wind power generator to flow into the axial fan. This allows a pressure loss at an air intake port or a discharge port of the axial fan to be prevented from increasing. Especially, the pressure loss at the air intake port or the discharge port of the axial fan can be prevented from increasing by adjusting the distribution of the flow rate of the air so as to be symmetrical to the rotation axis of the axial fan. 
     On the other hand, in the case of guiding the air to be sent by means of the axial fan to the heat exchanger, a pressure loss of the heat exchanger is prevented from increasing since the distribution of the flow rate of the air has been adjusted. 
     According to the fan unit for a wind power generator in accordance with the first aspect of the invention and the wind power generator in accordance with the second aspect, a rectification part adjusts distribution of the flow rate. This allows both of the advantages where a loss of flow at a flowing port can be prevented from increasing and that a pressure loss of the heat exchanger can be prevented from increasing to be achieved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates an overall structure of a wind power generator in accordance with the first embodiment of the invention. 
         FIG. 2  is a simplified view of a structure showing the inside of a nacelle in  FIG. 1 . 
         FIG. 3  is a simplified view of a structure of a fan unit for a converter in  FIG. 2 . 
         FIG. 4  is a block diagram illustrating a structure of a fan unit for a converter in  FIG. 2 . 
         FIG. 5  is a simplified view of a fan unit for a converter in  FIG. 3  in accordance with another embodiment. 
         FIG. 6  is a simplified view of a fan unit for a converter in  FIG. 3  in accordance with further another embodiment. 
         FIG. 7  is a simplified view of a fan unit for a converter in  FIG. 3  in accordance with further another embodiment. 
         FIG. 8  is a simplified view of a structure of a fan unit for a converter in a wind power generator in accordance with a second embodiment of the invention. 
         FIG. 9  is a partially enlarged view of a structure of a first perforated plate in  FIG. 8 . 
         FIG. 10  is a partially enlarged view of a structure of a second perforated plate in  FIG. 8 . 
         FIG. 11  is a block diagram illustrating a structure of a fan unit for a converter in  FIG. 8 . 
         FIG. 12  is a simplified view of a structure of a fan unit for a converter in a wind power generator in accordance with a third embodiment of the invention. 
     
    
    
     EXPLANATION OR REFERENCES  
     
         
           1 ,  401 : WIND POWER GENERATOR 
           3 : NACELLE 
           7 : GENERATION DEVICES (EQUIPMENT) 
           51 : CONVERTER MAIN BODY (EQUIPMENT) 
           52 ,  452 : FAN UNIT FOR CONVERTER (FAN UNIT FOR WIND POWER GENERATOR) 
           54 : FAN FOR CONVERTER (AXIAL FAN) 
           56 : BELL MOUTH (RECTIFICATION PART) 
           156 ,  256 : GUIDE (RECTIFICATION PART) 
           356 : DUCT (RECTIFICATION PART) 
           456 A: FIRST PERFORATED PLATE (RECTIFICATION PART) 
           456 B: SECOND PERFORATED PLATE (RECTIFICATION PART) 
           461 A: FIRST HOLE (OPENING) 
           461 B: SECOND HOLE (OPENING) 
           556 : EXFOLIATION PREVENTION GUIDE (RECTIFICATION PART) 
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
     First Embodiment 
     A wind power generator in accordance with the First Embodiment of the invention will be described hereinafter, with references to  FIGS. 1 to 7 . 
       FIG. 1  illustrates an overall structure of a wind power generator in accordance with First Embodiment. 
     A wind power generator  1  is for generating wind power, as shown in  FIG. 1 . The wind power generator  1  comprises a support  2  erected on a base B, a nacelle  3  provided at the top end of the support  2 , a rotor head  4  mounted to the nacelle  3  so as to be rotatable about a substantially horizontal axis, a head capsule  5  for covering the rotor head  4 , plural windmill rotation vanes  6  radially mounted around the rotation axis of the rotor head  4  and generation devices (equipment)  7  for generating electricity in accordance with a rotation of the rotor head  4 . 
     In First Embodiment, exemplified will be a case in which three windmill rotation vanes  6  are provided. The number of the windmill rotation vanes  6 , however, is not limited to three, but may be two or a number more than three. It is not specifically limited. 
     The support  2  is arranged to be in the shape of a pillar extending upward (to an upper side of  FIG. 1 ) from the base B, as shown in  FIG. 1 . The support  2  is arranged to comprise multiple units connected in the vertical direction, for example. At an uppermost part of the support  2 , provided is the nacelle  3 . The nacelle  3  is provided on a unit provided at the uppermost part in the case that the support  2  is formed from multiple units. 
     The nacelle  3  rotatably supports the rotor head  4  and contains therein the generation devices  7  for generating electricity in accordance with a rotation of the rotor head  4 , as shown in  FIG. 1 . Furthermore, an air intake port  8  for introducing the external air into the inside of the nacelle  3  is provided in a front part of the nacelle  3 , namely in a lower part of the nacelle  3  on a rotor head  4  side. 
     To the rotor head  4 , mounted are the plural windmill rotation vanes  6  extending radially about the rotation axis of the rotor head  4 , as shown in  FIG. 1 . The head capsule  5  covers the rotor head  4 . 
     The rotor head  4  is provided with a pitch control part (not shown) for rotating the windmill rotation vanes  6  about an axis of the windmill rotation vanes  6  to change a pitch angle of the windmill rotation vanes  6 . 
     This allows the windmill rotation vanes  6  to generate power for rotating the rotor head  4  about the rotation axis when the wind strikes the windmill rotation vanes  6  from a direction of the rotation axis of the rotor head  4 , so that the rotor head  4  is driven to rotate. 
       FIG. 2  is a simplified view of a structure showing the inside of a nacelle in  FIG. 1 . 
     The generation devices  7  contained in the nacelle  3  are provided with main bearings  11  for rotatably holding a main shaft (not shown) transmitting rotational driving force of the rotor head  4  to a generator  14 , a speed increasing gear  12  for increasing a speed of a rotation of the rotor head  4  to transmit the same to the generator  14 , an oil cooling part  13  for cooling oil used for lubricating the main bearings  11  and the speed increasing gear  12 , the generator  14  for generating electricity by means of the transmitted rotational driving force, a transformer part  15  for controlling a voltage of generated electricity and a converter part  16  for controlling a frequency, as shown in  FIG. 2 . 
     The oil cooling part  13  is for lubricating the main bearings  11  and the speed increasing gear  12  and for cooling lubricating oil having a high temperature. 
     The oil cooling part  13  comprises an oil heat exchanger  21  for radiating heat of the lubrication oil, an oil fan  22  for ventilating the oil heat exchanger  21 , an oil pipe  23  for circulating the lubricating oil between the main bearings  11  and the oil heat exchanger  21  or between the speed increasing gear  12  and the oil heat exchanger  21 . 
     The generator  14  comprises a generator main body  31  for generating electricity, a generator fan  32  for introducing the air into the generator main body  31  and a generator duct  33  for guiding the air, which has been introduced into the generator  14 , to the outside of the nacelle  3 . 
     As the generator main body  31 , the generator fan  32  and the generator duct  33 , used can be well-known components, which are not specifically limited. 
     The transformer part  15  comprises a transformer main body  41  for converting a voltage, an opening  42  for ventilating the transformer main body  41  and a transformer fan  43 . 
     As the transformer main body  41 , the opening and the transformer fan  43 , used can be well-known components, which are not specifically limited. 
     The converter part  16  is provided in the nacelle  3  at the rear part thereof (on the right side in  FIG. 2 ) on a floor F of the nacelle  3 . 
     The converter part  16  comprises a converter main body (equipment)  51  for converting a frequency and a fan unit for a converter (a fan unit for a wind power generator)  52  for cooling the converter main body  51 . 
     The converter  51  is provided in front of the fan unit for a converter  52  (on the left side in  FIG. 2 ) on the floor F of the nacelle  3 . In other words, it is provided in front of the fan unit for a converter  52  in a direction of a rotation axis L of the fan for a converter  54 . 
     As the converter main body  51 , used can be a well-known component, which is not specifically limited. 
       FIG. 3  is a simplified view of a structure of a fan unit for a converter in  FIG. 2 .  FIG. 4  is a block diagram illustrating a structure of a fan unit for a converter in  FIG. 2 . 
     The fan unit for a converter  52  comprises a heat exchanger for a converter  53  in which a refrigerant for cooling the converter main body  51  circulates, the fan for a converter (the axial fan)  54  for ventilating the heat exchanger for a converter  53 , plural flow speed sensors  55  for measuring a speed of a flow of the air flowing into the fan for the converter  54 , a bell mouth (a rectification part)  56  for adjusting distribution of the flow rate of the air flowing into the fan for a converter  54  and a control part  57  for controlling a location where the bell mouth  56  is provided, as shown in  FIGS. 3 and 4 . 
     The refrigerant having increased in temperature by absorbing the heat generated in the converter main body  51  flows into the heat exchanger for a converter  53 . The heat exchanger for a converter  53  radiates the heat of the refrigerant to the air. The heat exchanger for a converter  53  is provided on a downstream side of the fan for a converter  54  (on the left side in  FIG. 3 ). 
     The heat exchanger for a converter  53  can be a known one, which is not specifically limited. 
     The fan for a converter  54  is an axial fan and for ventilating the heat exchanger for a converter  53  with the air for a heat exchange. In other words, it is for ventilating the heat exchanger for a converter  53  to discharge the air in the nacelle  3  to the rear side of the nacelle  3 . 
     The fan for a converter  54  is provided with a fan for a converter  54  extending to the rear side of the nacelle  3 . The fan for a converter  54  is for sending the air into a converter duct  58 . Moreover, the heat exchanger for a converter  53  is provided in the converter duct  58 . 
     The flow speed sensor  55  is a sensor, which is provided in an air flow part of the fan for a converter  54 , for measuring a speed of a flow. The flow speed sensors  55  are provided so as to disperse on a surface to which the air flows. 
     The flow speed sensors  55  are connected to the control part  57  so that data of the measured flow speed can be transmitted, as shown in  FIG. 4 . 
     The bell mouth  56  is provided on an air flow side of the fan for a converter  54 , as shown in  FIG. 3 , and adjusts the distribution of the flow rate of the air flowing into the fan for a converter  54 . 
     The bell mouth  56  comprises a bell mouth main body  61 , which is provided movably in a direction along the rotation axis L of the fan for a converter  54 , for adjusting a flow of the air and a bell mouth drive part  62  for controlling a location where the bell mouth main body  61  is provided. 
     The bell mouth drive part  62  is connected to the control part  57  as shown in  FIG. 4  so that a control signal for controlling the location of the bell mouth main body  61  can be inputted. 
     As the bell mouth and the bell mouth drive part  62 , used can be well-known components, which are not specifically limited. 
     The control part  57  controls the bell mouth  56  on the basis of outputs from the flow speed sensors  55  to even distribution of the flow rate of the air flowing into the fan for a converter  54 . 
     The control part  57  is connected to the flow speed sensors  55  so that the data of the flow speed detected by means of the flow speed sensors  55  would be inputted and is connected to the bell mouth drive part  62  so that the control signal would be inputted. 
     Now, schematically described will be a way of generating electricity in the wind power generator  1  having the above structure. 
     In the wind power generator  1 , the force of the wind having struck the windmill rotation vanes  6  in a direction of the rotation axis of the rotor head  4  is converted into power for rotating the rotor head  4  about the rotation axis. 
     The rotation of the rotor head  4  is transmitted to the generation devices  7 . In the generation devices  7 , generated is the power corresponding to a subject of power supply, the alternated current power having the frequency of 50 Hz or 60 Hz, for example. 
     In this case, the nacelle  3  is properly rotated in a horizontal plane to make the rotor head  4  be directed to the wind at least during generation so that the wind power would effectively operate on the windmill rotation vanes. 
     Now, described will be a flow of the air in the fan unit for a converter  52 , which is a character of First Embodiment. 
     A way of cooling the converter main body  51  will be first described. Following to the above, described will be a way of adjusting the distribution of the flow rate of the air flowing into the fan for a converter  54 . 
     The refrigerant is circulated between the converter main body  51  and the heat exchanger for a converter  53  to let the refrigerant having absorbed heat in the converter main body  51 , flow into the heat exchanger for a converter  53 , as shown in  FIG. 3 , in order to cool the converter main body  51 . The heat of the refrigerant is radiated to the air flowing around in the heat exchanger for a converter  53 . The refrigerant having decreased in temperature due to radiation of the heat flows into the converter main body  51  again to absorb the heat generated in the converter main body  51 . 
     The air sent from the nacelle  3  by means of the fan for a converter  54  flows around the heat exchanger for a converter  53  to take the heat from the refrigerant. The air having taken the heat passes through the converter duct  58  to be discharged to the rear side of the nacelle  3 . 
     When the air in the nacelle  3  flows into the fan  54  for a converter  54 , the air detours around the converter main body  51  provided in front of the fan for a converter  54 , as shown in  FIG. 3 . In other words, the fan for a converter  54  is provided on the floor F while the converter main body  51  is provided in front of the fan for a converter  54 . Accordingly, the air in the nacelle  3  flows from the upper side to the fan for a converter  54  along the converter main body  51 , and the direction of the flow is changed so as to flow along the rotation axis L of the fan for a converter  54 . 
     The flow speed of the air flowing into the fan for a converter  54  is detected by means of the plural flow speed sensors  55 . The data of the flow speed is inputted to the control part  57  as shown in  FIG. 4 . The control part  57  estimates the distribution of the flow rate of the air on the basis of the data of the flow speed to control the bell mouth  56  based on the estimated distribution of the flow rate. 
     In the case that the distribution of the flow rate of the air inclines to a floor F side to be uneven, for example, outputted to the bell mouth drive part  62  is a control signal for separating the bell mouth main body  61  from the fan for a converter  54 . 
     The bell mouth drive part  62  moves the bell mouth main body  61  to a position away from the fan for a converter  54  on the basis of the inputted control signal. 
     The distribution of the flow rate of the air flowing into the fan for a converter  54  is evened when the bell mouth main body  61  is moved. The loss coefficient at a flow port of the fan for a converter  54  then decreases from 1 to 0.1, for example. 
     In accordance with such a structure, the distribution of the flow rate of the air detouring around the converter main body  51  of the wind power generator  1  to flow into the fan for a converter  54  is adjusted by means of the bell mouth  56 . This allows a pressure loss at the air intake port or the discharging port of the fan for a converter  54  to be prevented from increasing. Especially adjusting the distribution of the flow rate of the air so as to be symmetrical to the rotation axis L of the fan for a converter  54  allows a pressure loss at the air intake port or the discharging port of the fan for a converter  54  to be prevented from increasing. 
     On the other hand, a pressure loss of the heat exchanger for a converter  53  can be prevented from increasing since the distribution of the flow rate of the air is adjusted in the case of guiding the air sent by means of the fan for a converter  54  to the heat exchanger for a converter  53 . 
     Measuring the flow speed of the air by means of the plural flow speed sensors  55  allows the distribution of the flow rate of the air flowing into the fan for a converter  54  to be estimated. Accordingly, changing the location of the bell mouth  56  in a direction along the rotation axis L on the basis of the measured flow speed of the air allows a pressure loss at the air intake port or the discharging port of the fan for a converter  54  to be surely prevented from increasing. 
       FIG. 5  is a simplified view of the fan unit for a converter in  FIG. 3  in accordance with another embodiment. 
     It may be possible to provide the bell mouth  56  in the fan for a converter  54  to adjust the distribution of the flow rate of the air flowing into the fan for a converter  54  like the above embodiment. It may be also possible to provide a guide (a rectification part)  156  to adjust the distribution of the flow rate of the air flowing into the fan for a converter  54 , as shown in  FIG. 5 . This is not limited specifically. 
     The guide  156  is a member having a cross section in the approximate shape of an L bent toward the fan for a converter  54 , as shown in  FIG. 5 . The guide  156  is a member extending in a right-and-left direction of the nacelle  3  (a direction vertical to a surface of a sheet of  FIG. 5 ). Furthermore, the guide  156  is movably provided in the direction along the rotation axis L similarly to the bell mouth main body  61 . 
     Changing a location of the guide  156  in the direction along the rotation axis L as described above allows the distribution of the flow rate of the air flowing into the fan for a converter  54  to be adjusted. 
       FIG. 6  is a simplified view of a fan unit for a converter in  FIG. 3  in accordance with further another embodiment. 
     It may be possible to provide the guide  156  bent into the shape of an L in the fan for a converter  54  to adjust the distribution of the flow rate of the air flowing into the fan for a converter  54  similarly to the above-mentioned embodiment. Moreover, a guide (a rectification part)  256  may be also provided to adjust the distribution of the flow rate of the air flowing into the fan for a converter  54 , as shown in  FIG. 6 . This is not specifically limited. 
     The guide  256  is a member having a cross section gradually bent toward the fan for a converter  54 , as shown in  FIG. 6 . The guide is a member extending in the right-and-left direction of the nacelle  3  (a direction vertical to a surface of a sheet of  FIG. 6 ). Further, the guide  256  is movably provided in the direction along the rotation axis L similarly to the bell mouth main body  61 . 
     Changing a location of the guide  256  in the direction along the rotation axis L as described above allows a loss coefficient at the flow port of the fan for a converter  54  to be reduced from 1 to 0.3. 
       FIG. 7  is a simplified view of the fan unit for a converter in  FIG. 3  in accordance with further another embodiment. 
     It may be possible to provide the bell mouth  56  in the fan for a converter  54  to adjust the distribution of the flow rate of the air flowing into the fan for a converter  54  similarly to the above embodiment. Moreover, a duct (a rectification part)  356  may be also provided as shown in  FIG. 7  to adjust the distribution of the flow rate of the air flowing into the fan for a converter  54 . This is not specifically limited. 
     Providing the duct  356  as described above allows a loss coefficient at the flow port of the fan for a converter  54  to be reduced from 1 to 0.5. 
     Second Embodiment 
     Next, Second Embodiment of the invention will be described, with reference to  FIGS. 8 to 11 . 
     A basic structure of the wind power generator in accordance with Second Embodiment is similar to that of First Embodiment. Second Embodiment is different from First Embodiment in the structure of the fan unit for a converter. Accordingly, the structure of the fan unit for a converter will only be described in Second Embodiment with reference to  FIGS. 8 to 11 . Descriptions of other components and such are omitted. 
       FIG. 8  is a simplified view of a structure of a fan unit for a converter in a wind power generator in accordance with Second Embodiment. 
     Components same as those of First Embodiment are marked with the same reference signs and numerals and omitted from description. 
     A fan unit for a converter  452  in a wind power generator  401  comprises the heat exchanger for a converter  53  for circulating the refrigerant for cooling the converter main body  51 , the fan for a converter  54  for ventilating the heat exchanger for a converter  53 , the plural flow speed sensors  55  for measuring the flow speed of the air flowing into the fan for a converter  54 , a first perforated plate (a rectification part)  456 A and a second perforated plate (a rectification part)  456 B for adjusting the distribution of the flow rate of the air flowing into the fan for a converter  54 , and a control part  457  for controlling a location of the second perforated plate  456 B, as shown in  FIG. 8 . 
       FIG. 9  is a partially enlarged view of a structure of the first perforated plate in  FIG. 8 . 
     The first perforated plate  456 A is a plate in which plural holes having the same diameter for adjusting the distribution of the flow rate of the air flowing into the fan for a converter  54  together with the second perforated plate  456 B are formed. The first perforated plate  456 A is arranged to cover the fan for a converter  54  and the heat exchanger for a converter  53  as shown in  FIG. 8 . 
     In the first perforated plate  456 A, provided in the shape of a lattice are multiple first holes (openings)  461 A through which the air flows, as shown in  FIG. 9 . The plural first holes  461 A are formed so as to have a diameter between the maximum diameter and the minimum diameter of later-mentioned second holes  461 B. 
       FIG. 10  is a partially enlarged view of a structure of the second perforated plate in  FIG. 8 . 
     The second perforated plate  456 B is a belt-shaped plate in which plural holes having different diameters for adjusting the distribution of the flow rate of the air flowing into the fan for a converter  54  together with the first perforated plate  456 A are formed. The second perforated plate  456 B is movably provided along a surface of the first perforated plate  456 A on a fan for a converter  54  side, as shown in  FIG. 8 . 
     In the second perforated plate  456 B, provided in the shape of a lattice are plural second holes (openings)  461 B through which the air flows, as shown in  FIG. 10 . The second holes  461 B are arranged to have a larger diameter to a floor F side. 
       FIG. 11  is a block diagram illustrating a structure of the fan unit for a converter in  FIG. 8 . 
     The control part  457  is for controlling the second perforated plate  456 B on the basis of output from the flow speed sensors  55  to even the distribution of the flow rate of the air flowing into the fan for a converter  54 . 
     The control part  457  is connected to the flow speed sensors  55  so that flow speed data detected by means of the flow speed sensors  55  would be inputted and is connected to a second perforated plate drive part  462  so that a control signal would be inputted, as shown in  FIG. 11 . 
     The second perforated plate drive part  462  is for moving the second perforated plate  456 B along the first perforated plate  456 A. 
     Now, described will be a way of adjusting the distribution of the flow rate of the air flowing into the fan for a converter  54 , which is a character of Second Embodiment. 
     The air in the nacelle  3  detours around the converter main body  51  provided in front of the fan for a converter  54 , as shown in  FIG. 8 , when it flows into the fan for a converter  54 . In other words, the fan for a converter  54  is provided on the floor F while the converter main body  51  is provided in front of the fan for a converter  54 . Accordingly, the air in the nacelle  3  flows from the upper part to an area A along the converter main body  51 , and the direction of its flow is changed into a direction along the rotation axis L of the fan for a converter  54  in an area B. 
     The flow speed of the air flowing into the fan for a converter  54  is detected by means of the plural flow speed sensors  55  and data of the flow speed is inputted to the control part  457 , as shown in  FIG. 11 . The control part  457  estimates the distribution of the flow rate of the air on the basis of the data of the flow speed to control the second perforated plate  456 B on the basis of the estimated distribution of the flow rate. 
     A control signal for moving the second perforated plate  456 B to an area A side is outputted to the second perforated plate drive part  462  in order to increase resistance in flow in the area A and reduce resistance in flow in the area B, for example. 
     The second perforated plate drive part  462  moves the second perforated plate  456 B to a position away from the floor F on the basis of the inputted control signal. 
     This causes the air to pass through only a part where the first holes  461 A of the first perforated plate  456 A are overlapped with the second holes  461 B having smaller diameters in the area A. That is to say, the area the air passes through becomes smaller. Accordingly, the resistance in flow in the area A increases. On the other hand, the resistance in flow in the area B is reduced since there is only the first perforated plate  456 A in the area B, that is, because the area where the air passes through becomes larger. 
     In accordance with the above structure, moving the second perforated plate  456 B relatively to the first perforated plate  456 A allows the area of the overlap between the first holes  461 A of the first perforated plate  456 A and the second holes  461 B of the second perforated plate  456 B to be adjusted to adjust the distribution of the flow rate of the air flowing into the fan for a converter  54 . Accordingly, a pressure loss at the air intake port or the discharge port of the fan for a converter  54  can be prevented from increasing. 
     Third Embodiment 
     Next, the Third Embodiment of the invention will be described, with reference to  FIG. 12 . 
     A basic structure of the wind power generator in accordance with Third Embodiment is similar to that of First Embodiment. Third Embodiment is different from First Embodiment in the structure of the fan unit for a converter. Accordingly, the structure of the fan unit for a converter will be only described in Third Embodiment with reference to  FIG. 12 . Descriptions of other components and such are omitted. 
       FIG. 12  is a simplified view of a structure of a fan unit for a converter in a wind power generator in accordance with Third Embodiment. 
     Components same as those of First Embodiment are marked with the same reference signs and numerals and omitted from description. 
     A fan unit for a converter  552  in a wind power generator  501  comprises the heat exchanger for a converter  53  for circulating the refrigerant for cooling the converter main body  51 , the fan for a converter  54  for ventilating the heat exchanger for a converter  53 , and an exfoliation prevention guide (a rectification part)  556  for adjusting the distribution of the flow rate of the air flowing into the fan for a converter  54 , as shown in  FIG. 12 . 
     The exfoliation prevention guide  556  is provided at an air flow port of the fan for a converter  54  to prevent exfoliation of a flow of the air flowing into the fan for a converter  54  and to adjust the distribution of the flow speed of the air. 
     The exfoliation prevention guide  556  comprises a first inclining surface  561 , which is an inclining surface approaching the rotation axis L toward the fan for a converter  54 , and a second inclining surface  562 , which is an inclining surface going away from the rotation axis L toward the fan for a converter  54 . 
     The first inclining surface  561  is provided away from the fan for a converter  54  with respect to the second inclining surface  562 . The first inclining surface  561  and the second inclining surface  562  are smoothly connected to each other. 
     Now, described will be a way of adjusting the distribution of the flow rate of the air flowing into the fan for a converter  54 , which is a characteristic of Third Embodiment. 
     The air flowing into the fan for a converter  54  flows to the fan for a converter  54  along the rotation axis L or the first inclining surface  561 , as shown in  FIG. 12 . The air having flowed along the first inclining surface  561  then flows along the second inclining surface  562  to flow into the fan for a converter  54 . 
     Such a structure contributes to prevent exfoliation of a flow of the air flowing into the fan for a converter  54 . This allows a pressure loss at the air intake port or the discharging port of the fan for a converter  54  to be prevented from increasing.