Abstract:
The present invention relates to a hybrid generation system and a control method thereof. The hybrid generation system can maximize operation efficiency of a generator by selectively supplying normal utility power or power, which is generated by the generator, based on a power level supplied to a load. A hybrid generation system includes a generator and a generator controller. The generator generates power, and the generator controller performs a control activity to supply one of the normal utility power and the generated power to the load. The selective supply of the normal utility power or the generated power can maximize efficiency of the generator and as a result, a power consumption level of the hybrid generation system can be decreased, thereby reducing related costs.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a hybrid generation system and a control method thereof, and more particularly, to a hybrid generation system, which supplies selectively one of normal utility power and power, which is produced by a generator, to a load depending on a level of power supplied to the load, and to a control method thereof.  
         [0003]     2. Description of the Background Art  
         [0004]     Driving power is generally required to drive home or industrial electrical appliances and devices. Typically, these home or industrial electrical appliances and devices receive necessary power through a power supply, which supplies normal utility power provided from a power station (e.g., Korea Electric Power Corporation). However, it is a frequent case that externally provided normal utility power is insufficient to supply power to all loads in industrial plants. Thus, a self-generation system is often prepared separately.  
         [0005]      FIG. 1  is a configuration diagram illustrating a conventional self-generation system.  
         [0006]     As illustrated, the self-generation system includes a generator  2 , a switch  3  and a generator controller  4 . The generator  2  generates power as an internal engine is driven and supplies the power to a load  1 . The generator controller  4  sends data to the generator  2  or receives data from the generator  2  to control operation of the generator  2 . The switch  3  is turned on or off in response to a control signal transmitted from the generator controller  4  to supply to the load  1  or break the power generated by the generator  2 .  
         [0007]     In the above conventional self-generation system, when a signal that indicates a load generation is transmitted to the generator controller  4 , the generator controller  4  detects the signal, and generates a driving instruction and transmits the driving instruction to an engine of the generator  2 . The generator  2  generates a certain level of power as the engine drives, and then, the switch  3  is turned on. As a result, the generated power is supplied to the load  1 .  
         [0008]     However, in the above described conventional self-generation system, the generator  2  is mandated to operate whenever there is a load generation. Hence, the generator  2  generates a certain level of power regardless of a size of the load and supplies the power to the load  1 . Supplying the power to the load  1  may cause an abrupt decrease in efficiency of the self-generation system. For instance, assuming that a generator has the maximum operation efficiency when generating 100 kilowatts (KW) of power, the generator drives until reaching a state that the generator can generate 100 KW of power even if not only 100 KW of power but also 10 KW thereof are to be transferred to a load coupled with the generator. Accordingly, the self-generation system may have a decreased level of efficiency, and resources may be wasted unnecessarily and a cost to drive the generator may increase to a greater extent.  
       SUMMARY OF THE INVENTION  
       [0009]     Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the background art.  
         [0010]     It is an object of the present invention to provide a hybrid generation system, which can drive a generator effectively by determining operation efficiency of the generator based on a summated level of power supplied to a load and supplying normal utility power instead of power generated by the generator when the operation efficiency is low, and a control method thereof.  
         [0011]     According to a first embodiment of the present invention, a hybrid generation system includes a generator engine and a generator controller. The generator generates a certain output to generate power. The generator controller summates a power level supplied to a load and selectively supplies normal utility power or the generated power according to the summated power level.  
         [0012]     According to a second embodiment of the present invention, a method of controlling a hybrid generation system includes supplying power generated by a generator to a load and calculating a summated power level of the generated power supplied to the load and comparing the calculation result with an operation efficiency of the generator to supply one of the generated power and normal utility power to the load according to the comparison result. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The invention will be described in detail with reference to the following drawings in which like numerals refer to like elements.  
         [0014]      FIG. 1  is a configuration diagram illustrating a conventional self-generation system;  
         [0015]      FIG. 2  is a block diagram illustrating a hybrid generation system according to an embodiment of the present invention;  
         [0016]      FIG. 3  is a detailed configuration diagram illustrating the hybrid generation system according to the embodiment of the present invention; and  
         [0017]      FIG. 4  is a flowchart illustrating a control method of the hybrid generation system according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]     Embodiments of the present invention will be described in a more detailed manner with reference to the drawings.  
         [0019]      FIG. 2  is a block diagram illustrating overall configuration of a hybrid generation system according to an embodiment of the present invention.  FIG. 3  is a detailed configuration diagram illustrating the hybrid generation system according to the embodiment of the present invention.  
         [0020]     Referring to  FIG. 2 , the hybrid generation system includes a generator  30 , a power transfer switch  40  and a generator controller  50 . The generator  30  drives to generate power without an aid, and outputs the self-generated power. The generator controller  40  controls the generator  30  or a power supply  20  supplying normal utility power to make one of the generator  30  and the power supply  20  selectively supply power to a load  10  depending on a level of generated load. The power transfer switch  40  transfers one of power generated by the generator  30  and normal utility power provided from the power supply  20  to the load  10  in response to a control signal transmitted from the generator controller  50 .  
         [0021]     The power transfer switch  40  is coupled individually with the generator  30  and the power supply  20  and includes first and second switches  41  and  42 , which can break driving power in response to a signal transmitted from the generator controller  50 , and a circuit breaker  43 , which can break the driving power transmitted through the first and second switches  41  and  42 .  
         [0022]     The first and second switches  41  and  42  may be configured as a magnetic relay switch, which is turned on or off according to the control signal transmitted from the generator controller  50 . The circuit breaker  43  is a manual switch, and can prevent leakage current by shutting down the power supply when a level of power supplied to the load  10  through the first and second switches  41  and  42  exceeds a predetermined level.  
         [0023]     In the present embodiment, an air conditioner is exemplified as the load  10  because the air conditioner generally consumes power with the maximum amount of load during summer and thus, frequently determines a peak level of power. However, it should be noted that the load  10  is not limited only to the exemplified air conditioner; rather, the load  10  can be configured with multiple devices that can drive by supplied power.  
         [0024]     A self-generation system including the generator  30  can be configured to a cogeneration system. A cogeneration system uses waste heat while generating power using a co-generator and, includes an engine, a co-generator, which generates power using a rotational force produced by the engine, a heat supplier, which supplies waste heat collected from cooling water which cools the engine or an exhausted gas from the engine to a heat consumer such as an air conditioner.  
         [0025]     The power generated in the cogeneration system can be used to operate various electrical appliances and devices such as light bulbs and air conditioners. Also, the cogeneration system may be specifically set to generate a consistent level of power under an optimum operation condition regardless of a size of the load generally necessary for such electrical appliances and devices such as air conditioners.  
         [0026]     Referring to  FIG. 3 , in the case of the cogeneration system, the generator  30  includes a generator engine  31  and an engine controller  32 . The generator engine  31  drives a generator  30 , and the engine controller  32  controls whether to drive the engine  31  or controls a round per minute (RPM) value. Therefore, the generator controller  50  transmits a control signal to the engine controller  32  in response to a load generation for the purpose of increasing or decreasing a RPM value of the generator engine  31 . As a result, a generation level of power by the generator  30  can be increased or decreased.  
         [0027]     Particularly, the generator controller  50  includes a power calculator  55 , an efficiency determination unit  53  and a main controller  51  to supply selectively one of power generated in the generator  30  and normal utility power provided from the power supply  20  to the load  10 . The power calculator  55  summates a level of power transferred to the load  10 . The efficiency determination unit  53  compares the summated level of power calculated by the power calculator  55  with operation efficiency of the generator engine  31  and determines the comparison result thereafter. According to the determination result by the efficiency determination unit  53 , the main controller  51  generates a control signal and transmits the control signal to the power transfer switch  40 .  
         [0028]     Although not illustrated, the generator controller  50  further includes a memory into which a control program for operation of the main controller  51  and a data about the summated power level calculated by the power calculator  55 .  
         [0029]     The power calculator  55  detects and summates a level of power supplied from the circuit breaker  43  to the load  10 .  
         [0030]     In the case that the generated power by the generator  30  is supplied to the load  10 , if the efficiency determination unit  53  determines that a summated level of power for a certain period falls within a range of low efficiency of the generator engine  31 , the main controller  51  transmits an off-signal and an on-signal to the second switch  42  coupled with the generator  30  and to the first switch  41  coupled with the power supply  20 , respectively. Also, the main controller  51  breaks a supply of the generated power and, supplies the normal utility power to the load  10 .  
         [0031]     In the case that the normal utility power is supplied to the load  10 , if the efficiency determination unit  53  determines that a summated level of power for a certain period falls within a range of high efficiency of the generator engine  31 , an off-signal and an on-signal are transmitted respectively to the first switch  41 , which is coupled with the power supply  20 , and the second switch  42 , which is coupled with the generator  30 . As a result, the power generated in the generator  30  is supplied to the load  10 .  
         [0032]     The efficiency determination unit  53  compares the summated level of the power with a generator efficiency based on the summated level. Various efficiency comparison methods may be employed depending on cases. For instance, a cost for the generator  30  to generate the summated power level supplied to the load  10  can be compared with a power rate charged based on the calculation for which the power is supplied from the power supply  20 . That is, if the generation cost is higher than the power rate, the efficiency determination unit  53  may determine that the generator  30  is in a range of low efficiency. On the other hand, if the generation cost is lower than the power rate, the efficiency determination unit  53  may determine that the generator  30  is in a range of high efficiency.  
         [0033]     More simply, on the basis of the maximum efficiency of the generator  30 , if the summated power level exceeds approximately 50% of the power level generated by the generator  30 , it may be determined that the generator  30  has high efficiency. On the other hand, if the summated power level does not exceed approximately 50% thereof, it may be determined that the generator  30  has low efficiency.  
         [0034]      FIG. 4  is a flowchart illustrating a control method of the hybrid generation system according to another embodiment of the present invention. With reference to FIGS.  2  to  4 , the other embodiment on the control method of the hybrid generation system will be described in detail.  
         [0035]     When a load is generated in operation S 101 , the load generation is detected to drive the generator  30 . In operation S 103 , when the generator  30  generates a certain output (e.g., electric power), a control signal is transmitted to the second switch  42  coupled with the generator  30 , so that the power generated in the generator  30  is supplied to the load  10 . Continuously, a level of the power transmitted to the load  10  is detected to calculate a summated power level.  
         [0036]     After a certain elapse of time, in operation S 105 , operation efficiency of the generator  30  is determined based on a summated power level for the certain time elapse. At this point, the determination is based on a comparison result between a cost to generate the summated power level and a power rate charged according to a consumption level of the summated power level, or a reference value of approximately 50% of the generated power level in the generator  30 .  
         [0037]     If the determination result provided in operation S 105  is that the operation efficiency of the generator  30  to generate the summated power level is low, in operation S 107 , the second switch  42  coupled with the generator  30  is broken, whereas the first switch  41  coupled with the power supply  20  is connected, so that normal utility power is supplied to the load  10 .  
         [0038]     If the normal utility power is supplied to the load  10  for a certain period of time, in operation S 109 , a summated power level calculated for the certain period of time and operation efficiency of the generator  30  are determined. If the determination result is that the generator  30  has high operation efficiency, in operation S 111 , the first switch  41  coupled with the power supply  20  is broken; on the contrary, the second switch  42  coupled with the generator  30  is connected. Hence, the generated power in the generator  30  is supplied to the load  10 .  
         [0039]     The generator  30  may be set to be detected by a user through outputting supply power (e.g., generated power or normal utility power) supplied to the load  10  and a data about a supply level of power to outside.  
         [0040]     According to the exemplary embodiments of the present invention, using a summated level of power supplied to the load allows a determination of high or low operation efficiency of the generator. Thus, normal utility power and the generated power in the generator are set to be supplied selectively to the load. As a result, operation efficiency of the generator can be maximized, and the maximized operation efficiency results in a decreased level of power consumption in the hybrid generation system.  
         [0041]     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.