JP3655831B2 - Booster unit, power conditioner, and solar power generation system using them - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a boosting unit, a power conditioner, and a photovoltaic power generation system using them, and more particularly, for boosting the output voltage of a second solar cell array to match the output voltage of the first solar cell array The present invention relates to a booster unit, a power conditioner that converts DC power generated by a first solar cell array and output power of the booster unit into AC power and supplies the AC power to a load circuit, and a solar power generation system using them.
[0002]
[Prior art]
As long as sunlight is irradiated, the solar cell operates as a DC power source and outputs DC power. A solar cell is known as a simple and clean energy source because it can output direct-current power without any other energy source such as a secondary battery and does not discharge harmful substances.
[0003]
In a conventional solar power generation system, DC power generated by a solar cell is converted into AC power by a power conditioner and supplied to a general AC load or an existing commercial power system. A plurality of solar cell strings are connected to the inverter through a connection box that is an external device having a connection function.
[0004]
The plurality of solar cell strings include a standard solar cell string including a standard number of solar cell modules connected in series and a non-standard solar cell string including less than the standard number of solar cell modules connected in series. included.
[0005]
For example, when installing a solar cell string on the roof of a house, depending on the shape and area of the roof, it may not be possible to configure the solar cell string by arranging solar cell modules only on the south surface of the roof with the highest amount of solar radiation. is there. Solar cell modules that were not placed on the south side of the roof were also placed on the west and east sides of the roof to form a solar cell string, or after the solar cell module was placed on the main part of the south side of the roof. A solar cell string may be configured including a small solar cell module arranged in the remaining region. That is, the number of solar cell modules included in some solar cell strings may be smaller than that of other solar cell strings, and in this case, the output voltage differs between the solar cell strings.
[0006]
When a solar cell string composed of a standard series number of solar cell modules and a solar cell string composed of less than the standard series number of solar cell modules are connected in parallel to the power conditioner, Therefore, even if the power conditioner performs maximum power point tracking control based on the synthesized voltage-power characteristics, it is not possible to output power that is the sum of the maximum powers. It is not possible to make the best use of the generated power. In such a case, it is possible to make the most effective use of the power generated by the solar cell by providing a booster unit in front of the inverter and combining the output voltages of the standard solar cell string and the non-standard solar cell string. Become.
[0007]
FIG. 3 is a circuit block diagram showing the configuration of such a photovoltaic power generation system. In FIG. 3, the photovoltaic power generation system includes a standard solar cell string 31 a, a nonstandard solar cell string 31 b, a boost unit 32, a connection box 40, and a power conditioner 45. In FIG. 3, only two solar cell strings 31a and 31b are shown for simplification of the drawing, but it goes without saying that more solar cell strings are usually included.
[0008]
The standard solar cell string 31 a is connected to the power conditioner 45 through the connection box 40, while the nonstandard solar cell string 31 b is connected to the power conditioner 45 through the booster unit 32 and the connection box 40. The step-up unit 32 includes a step-up circuit 33 and a step-up control unit 39, and the step-up circuit 33 includes a reactor 34, a switching transistor 35, diodes 36 and 37, and a capacitor 38.
[0009]
As shown in FIG. 4, the boost control unit 39 includes a boost ratio setting unit 51, a signal setting calculation unit 52, a triangular wave generation unit 53, a signal comparison unit 54, and a gate drive unit 55. The step-up ratio setting unit 51 sets the ratio between the number n1 of solar cell modules included in the standard solar cell string 31a and the number n2 of solar cell modules included in the non-standard solar cell string 31b, that is, the step-up ratio n1 / n2. The boost ratio setting unit 51 is provided with a selector switch for switching the boost ratio, and the boost ratio is set by manually switching the selector switch in advance according to the solar cell strings 31a and 31b.
[0010]
Based on the boost ratio set by the boost ratio setting unit 51, the signal setting value Vt generated by the signal setting calculation unit 52 and the triangular wave signal φT generated by the triangular wave generation unit 53 and having an amplitude value from 0 to Vd are signals. The comparison unit 54 compares them. The signal comparison unit 54 performs PWM (pulse width modulation) control by outputting a gate-off level when the signal set value Vt is higher than the level of the triangular wave signal φT. The output pulse signal PS of the signal comparison unit 54 is input to the gate of the switching transistor 35 via the gate drive 55.
[0011]
The connection box 40 includes backflow prevention diodes 41 and 42 for preventing a backflow of current from the power conditioner 45 side to the solar cell strings 31a and 31b side, and from the solar cell string 31a and 31b side to the power conditioner 45 side. It includes a lightning surge absorber 43 for preventing a lightning surge from entering during a lightning strike, and a breaker for connecting / blocking the solar cell strings 31a, 31b and the power conditioner 45. The power conditioner 45 converts the DC power supplied through the connection box 40 into AC power having the same phase and frequency 50 or 60 Hz as the commercial power and supplies the AC power to the commercial power system 46.
[0012]
Next, the operation of this solar power generation system will be described. FIG. 5 is a diagram showing output characteristics of the standard solar cell string 31a and the nonstandard solar cell string 31b. In FIG. 5, the horizontal axis indicates the output voltage V of the solar cell strings 31a and 31b, and the vertical axis indicates the output power P of the solar cell strings 31a and 31b. Since the number n1 of solar cell modules of the standard solar cell string 31a is larger than the number n2 of solar cell modules of the nonstandard solar cell string 31b, the maximum output power Pa and the output voltage Va at the time of maximum power output of the standard solar cell string 31a. Is larger than the maximum output power Pb of the non-standard solar cell string 31b and the output voltage Vb at the time of maximum power output (Pa> Pb, Va> Vb).
[0013]
FIG. 6 is a diagram showing characteristics obtained by synthesizing the output characteristics of the standard solar cell string 31a and the non-standard solar cell string 31b. In the synthesized output characteristics, when the output voltage is Vb, the output power becomes the maximum value Pa + α (<Pa + Pb). When the booster unit 32 is not used, the electric power of the solar cell strings 31a and 31b is input to the power conditioner 45 with this characteristic. In this case, the standard solar cell string 31a and the non-standard solar cell string 31b have different voltages Va and Vb for outputting the maximum powers Pa and Pb. Therefore, the power Pa + Pb obtained by adding the maximum powers Pa and Pb is output. Therefore, the output power of the solar cell strings 31a and 31b cannot be utilized to the maximum extent possible.
[0014]
When the booster unit 32 is used, as shown in FIG. 7, the voltage at the time of the maximum power Pb output of the non-standard solar cell string 31b can be matched with the voltage Va at the time of the maximum power Pb output of the standard solar cell string 31a. As a result, it is possible to output the electric power Pa + Pb obtained by adding the maximum electric power Pa and Pb of the two solar cell strings 31a and 31b, and it is possible to utilize the output electric power of the solar cell strings 31a and 31b as much as possible. It becomes.
[0015]
In addition, there are also a photovoltaic power generation system composed of a booster unit and a power conditioner having a junction box function, and a photovoltaic power generation system composed of a booster unit having a junction box function and a power conditioner. The basic function is the same as that of the photovoltaic power generation system shown in FIG.
[0016]
[Problems to be solved by the invention]
However, in the conventional photovoltaic power generation system, based on the number n1 of solar cell modules of the standard solar cell string 31a and the number n2 of solar cell modules of the nonstandard solar cell string 31b, the boost ratio n1 / It is necessary to set n2 at the time of system installation, and the work at the time of system installation becomes complicated.
[0017]
Moreover, the solar cell module differs in the number of solar cells depending on the type, and the output voltage also differs. Therefore, in order to deal with all types of solar cell modules and combinations of the number of solar cell modules in series, it is necessary to prepare a large number of step-up ratio setting values in advance. It is very troublesome to check the type and the number in series and select an optimum value from a large number of set values.
[0018]
Further, even when the optimum step-up ratio is set for the combination of the types of solar cell modules and the number of serially connected modules, the voltage ratio between the solar cell strings 31a and 31b is not always constant. For example, when the installation directions of the solar cell strings 31a and 31b are different and the element temperature of the non-standard solar cell string 31b changes from Ts to Ts ′ due to the influence of solar radiation or shadow, as shown in FIG. The output characteristics of the solar cell string 31b also change. FIG. 8 shows a state in which the maximum output power of the non-standard solar cell string 31b is reduced from Pb to Pb ′, and the voltage at the maximum output is reduced from Vb to Vb ′. In this case, as shown in FIG. 9, the output voltage Va ′ of the non-standard solar cell string 31b after boosting is lower than the output voltage Va of the standard solar cell string 31a, and the generated power of the solar cell strings 31a and 31b is reduced. It cannot be used as effectively as possible.
[0019]
Further, when the set value of the boost ratio of the boost unit 32 is approximated by a representative set value rather than a fine set value for each combination of the types of solar cell modules and the number of series units, it is not necessary to prepare many set values. Although the operation at the time of setting is not comparatively complicated, the operating voltage that is the maximum power at the set step-up ratio differs between the solar cell strings 31a and 31b, and it is not possible to output the power obtained by adding the respective maximum powers. The power generated by the solar cell strings 31a and 31b cannot be utilized to the maximum extent possible.
[0020]
Therefore, a main object of the present invention is to provide a booster unit, a power conditioner, and a solar power generation system using them that are easy to install and can improve efficiency.
[0021]
[Means for Solving the Problems]
The step-up unit according to the present invention includes a first solar cell array including a first number of solar cells connected in series, and a second number of solar cells smaller than the first number connected in series. In a solar power generation system that is connected to at least two solar cell columns and converts DC power generated by the first and second solar cell columns to AC power and supplies the AC power to a load circuit, the second solar cell column A boosting unit for boosting the output voltage to match the output voltage of the first solar cell array, and a booster circuit capable of controlling the boost ratio for boosting the output voltage of the second solar cell array; A power detector for detecting the output power of the second solar cell array, and a signal indicating whether the output power of the second solar cell array has increased or decreased based on the detection result of the power detector. And a signal generation circuit.
[0022]
Thick The positive power generation system further includes control means for controlling the boost ratio of the booster circuit so that the output power of the photovoltaic power generation system is maximized based on the output signal of the signal generation circuit, and the booster unit further includes a booster Setting means for setting the step-up ratio of the circuit to a predetermined value, and selection means for selecting any one of the control means and the setting means are provided.
[0023]
Preferably, further, a protection unit is provided for stopping the boosting operation of the booster circuit when the output voltage of the booster circuit exceeds a predetermined value.
[0024]
Further preferably, a display means for displaying the output power of the second solar cell array based on the detection result of the power detector is further provided.
[0025]
The power conditioner according to the present invention includes a first solar cell array including a first number of solar cells connected in series, and a second number of solar cells smaller than the first number connected in series. And a step-up unit capable of controlling the step-up ratio for boosting the output voltage of the second solar cell row to coincide with the output voltage of the first solar cell row. A power conditioner that is connected at least and that converts DC power generated by the first solar cell array and output power of the boost unit to AC power and supplies the AC power to a load circuit, the output power of the first solar array An inverter circuit that combines the output power of the boosting unit, converts the combined DC power into AC power, and applies it to the load circuit, a first power detector that detects the output power of the inverter circuit, and a first power detection Detector detection Based on the output power of the power conditioner are those having a control unit for controlling the booster unit and the inverter circuit so as to maximize.
[0026]
Ascension The pressure unit further increases the output power of the second solar cell array based on the second power detector that detects the output power of the second solar battery array and the detection result of the second power detector. And a signal generating circuit for outputting a signal indicating whether the voltage has been reduced or not, and the control means controls the boosting ratio of the boosting unit based on the output signal of the signal generating circuit.
[0027]
Ma The The control means includes a first step of controlling the input voltage of the inverter circuit so that the output power of the inverter circuit increases while the input voltage of the boosting unit is held constant, and the input voltage of the inverter circuit is constant. And a second step of controlling the boosting ratio of the boosting unit so that the output power of the second solar cell array increases during the held period.
[0028]
Moreover, the solar power generation system according to the present invention includes a first solar cell array including a first number of solar cells connected in series, and a second number of solar cells smaller than the first number connected in series. A photovoltaic power generation system that is connected to at least a second solar cell array including a battery, converts DC power generated by the first and second solar cell columns into AC power, and supplies the AC power to a load circuit; A step-up unit capable of controlling the step-up ratio for boosting the output voltage of the second solar cell array to match the output voltage of the first solar cell array, and the output power of the first solar cell array and the boost unit An inverter circuit that combines output power and converts the combined DC power to AC power and supplies it to the load circuit, and control means for controlling the boosting unit and the inverter circuit so that the output power of the photovoltaic power generation system is maximized Including It is obtained by a chromatography conditioner.
[0029]
System The control means includes a first step of controlling the input voltage of the inverter circuit so that the output power of the inverter circuit increases while the input voltage of the boosting unit is held constant, and the input voltage of the inverter circuit is constant. And a second step of controlling the boosting ratio of the boosting unit so that the output power of the second solar cell array increases during the held period.
[0030]
Further preferably, there is further provided a setting means for setting the boosting ratio of the boosting unit to a predetermined value, and a selecting means for selecting one of the control means and the setting means. The step-up ratio is controlled or set by the control means or setting means selected by the selection means.
[0031]
Preferably, further, a protection unit is provided for stopping the boosting operation of the boosting unit when the output voltage of the boosting unit exceeds a predetermined value.
[0032]
Preferably, a display means for displaying the output power of the second solar cell array is further provided.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a configuration of a photovoltaic power generation system according to an embodiment of the present invention. In FIG. 1, this photovoltaic power generation system includes a standard solar cell string 1 a, a nonstandard solar cell string 1 b, a power conditioner 2, and a booster unit 10. In FIG. 1, only one standard solar cell string 1a and one nonstandard solar cell string 1b are shown for simplification of the drawing, but it goes without saying that more solar cell strings can be included. Absent. The standard solar cell string 1a includes a standard series number (usually 8 or 9) of solar cell modules. The non-standard solar cell string 1b includes a number of solar cell modules less than the standard series number.
[0034]
The power conditioner 2 includes backflow prevention diodes 3 and 4, an inverter circuit 5, an inverter control unit 6, an output current detector 7, an input voltage detector 8, and a boost unit control unit 9. The output voltage of the standard solar cell string 1 a is input to the inverter circuit 5 through the backflow prevention diode 3. The output voltage of the non-standard solar cell string 1b is input to the inverter circuit 5 through the boost unit 10 and the backflow prevention diode 4. The inverter circuit 5 is controlled by the inverter control unit 6, converts DC power into AC power having the same phase and frequency 50 or 60 Hz as the commercial power, and supplies the AC power to the commercial power system 22.
[0035]
The output current IO of the power conditioner 2 is detected by the output current detector 7, and the input voltage VA of the power conditioner 2 is detected by the input voltage detector 8 and input to the inverter control unit 6. The inverter control unit 6 controls the inverter circuit 5 so that the output current IO becomes maximum based on the output current detection value IO and the input voltage detection value VA, so that the output power of the inverter circuit 5 becomes maximum. So that it is controlled. When the booster unit 10 is not operated, the output power of the standard solar cell string 1a is maximized as shown in FIGS. Here, if control is performed so that the output power of the non-standard solar cell string 1b is maximized, it is possible to output power obtained by adding the respective maximum powers, and the generated power of the solar cell strings 1a and 1b is maximally effective. It becomes possible to utilize it.
[0036]
The step-up unit controller 9 controls the step-up unit 10 so that the output power of the non-standard solar cell string 1b is maximized by controlling the step-up ratio and giving a duty to the step-up unit 10. That is, the boosting unit control unit 9 has the target boosting unit input voltage setting value VBref, and changes the target input voltage setting value VBref so that the output power of the non-standard solar cell string 1b increases. Further, the inverter input voltage VA is detected, the boost ratio VA / VBref is determined from the boost unit input voltage setting value VBref, and the duty 1-VBref / VA is calculated from the boost ratio and applied to the boost unit 10.
[0037]
The step-up unit 10 includes a step-up circuit 11, a step-up control unit 17, an input voltage detector 18, an output voltage detector 19, an input current detector 20, and a display unit 21. Booster circuit 11 includes a reactor 12, a switching transistor 13, diodes 14 and 15, and a capacitor 16. The DC power generated by the nonstandard solar cell string 1 b is input to the switching transistor 13 via the reactor 12. The energy stored in the reactor 12 during the ON period of the switching transistor 13 is stored and output to the capacitor 16 via the diode 14 during the OFF period of the switching transistor 13. That is, the output voltage of the booster circuit 11 is controlled by the on / off control of the switching transistor 13. The booster unit 10 and the power conditioner 2 are connected by a signal line, and communication between the control units 9 and 17 is possible.
[0038]
The step-up control unit 17 turns on / off the switching transistor 13 of the step-up circuit 11 with the duty given from the step-up unit control unit 9 of the power conditioner 2. Further, the boost control unit 17 detects the input voltage VB and the input current IB via the detectors 18 and 20, respectively, calculates the input power of the boost unit 10 (output power of the non-standard solar cell string 1b), and inputs it. A signal indicating whether the power has increased or decreased is supplied to the boosting unit controller 9 of the power conditioner 2. The display unit 21 displays the instantaneous power calculated by the boost control unit 17 and the operation state of the boost circuit 11. Further, the boost control unit 17 monitors the output voltage VC of the boost unit 10 detected via the detector 19 so that it does not exceed a predetermined value. If the output voltage VC exceeds the predetermined value, the boost circuit 17 is used for overvoltage protection. 11 is stopped.
[0039]
FIG. 2 is a time chart showing the operation of this solar power generation system. When the power conditioner 2 starts the interconnection operation from time T0, the inverter controller 6 first starts an initial operation. In this initial operation period, the output is increased until the power conditioner input voltage VA reaches a preset initial value VAref (T0). During this period T0 to T1, the boosting unit controller 9 is not operating, and the boosting unit 10 is stopped. When the input voltage VA reaches a preset initial value VAref (T0), the inverter control unit 6 controls the inverter circuit 5 so as to maintain this voltage. On the other hand, the boosting unit controller 9 starts an initial operation from time T1. In the initial operation period of the boosting unit control unit 9, the boosting ratio VA (T) / VBref (T0) is based on the power conditioner input voltage VA and a preset initial value VBref (T0) of the boosting unit input voltage. Furthermore, the duty 1-VBref (T0) / VA (T) is obtained, and the duty and the operation permission signal are given to the boosting unit 10. When the boosting unit controller 9 receives the operation permission signal and the duty, the boosting unit 10 starts to operate, gradually changes the duty to increase the on-time of the switching transistor 13, and increases the duty to 1-VBref (T0). ) / VA (T). Here, VA (T) indicates a power conditioner input voltage that changes every moment. This is because the inverter control unit 6 controls the power conditioner input voltage to be kept constant between times T1 and T2, but the voltage changes due to a change in the output power of the boosting unit 10. At time T2 when the duty of the boosting unit 10 reaches 1-VBref (T0) / VA (T), the boosting unit 10 provides a signal indicating whether the detected power has increased or decreased to the power conditioner 2. In the initial operation period, since the power is started from 0, the power always increases.
[0040]
Next, the inverter control unit 6 starts a maximum power point tracking operation (MPPT). During time T2 to T3, the boosting unit control unit 9 continues to give the duty 1-VBref (T0) / VA (T) to the boosting unit 10, so that the inverter controller 6 performs the maximum power point tracking operation to input the power conditioner. Even if the voltage VA fluctuates, the boost unit input voltage VB is kept constant. Therefore, since the output power of the boosting unit 10 is kept constant, the maximum power point tracking operation of the inverter control unit 6 is performed with high accuracy. In the maximum power point tracking operation of the inverter control unit 6 at times T2 to T3, the direction in which the power conditioner output current IO increases is checked, and the input voltage set value VAref (T0) is increased in the direction in which the power conditioner output current IO increases. Is updated to VAref (T3).
[0041]
From the time (T3) when the inverter input voltage VA reaches the input voltage set value VAref (T3), the maximum power point tracking operation moves to the boosting unit control unit 9, and the inverter control unit 6 uses the input voltage VA as the input voltage. The inverter circuit 6 is controlled to maintain the set value VAref (T3). On the other hand, the boosting unit control unit 9 receives a signal indicating whether the power has increased or decreased from the boosting unit 10, and based on the signal, sets the input voltage setting value in the direction in which the power of the boosting unit 10 increases, VBref (T0 ) To VBref (T4), and the duty 1−VBref (T4) / VA (T) is given to the boosting unit 10. The step-up unit 10 operates with the duty given from the step-up unit controller 9. From time T4, the maximum power point following operation moves to the inverter control unit 6. As described above, the maximum power point follow-up control is alternately and repeatedly executed by the inverter control unit 6 and the boosting unit control unit 9, whereby the maximum power of each of the solar cell strings 1a and 1b can be output.
[0042]
Note that if the boost control unit 17 of the boost unit 10 is provided with a selector switch for switching the boost ratio to either manual setting or automatic control by the boost unit control unit 9, the existing power conditioner 2 is boosted. When the power conditioner 2 does not have a communication function with the boosting unit 10 as in the case of adding the unit 10, the boosting unit 10 can be operated at a boosting ratio set in advance by the standard series number and the non-standard series number. It becomes possible and it can respond to more systems. The changeover switch may be automatically changed according to the presence / absence of a communication function between the power conditioner 2 and the booster unit 10.
[0043]
In this embodiment, when the output voltage VC of the booster circuit 11 exceeds a predetermined value, the boosting operation of the booster circuit 11 is stopped for overvoltage protection. However, the input voltage VA of the inverter circuit 5 has a predetermined value. When exceeding, the boosting operation of the booster circuit 11 may be stopped.
[0044]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0045]
【The invention's effect】
As described above, in the boosting unit according to the present invention, the booster circuit capable of controlling the boosting ratio for boosting the output voltage of the second solar cell array and the output power of the second solar cell array are detected. A power detector and a signal generation circuit that outputs a signal indicating whether the output power of the second solar cell array has increased or decreased based on the detection result of the power detector are provided. Therefore, the boost ratio of the booster circuit can be controlled so that the output power of the system is maximized based on the output signal of the signal generation circuit, so there is no need to manually set the boost ratio of the booster circuit as in the prior art. Work at the time of setting becomes easy. Even when the output voltage of one of the first and second solar cell arrays changes due to the influence of solar radiation, the boost ratio of the booster circuit can be controlled to the optimum value accordingly, so that the boost ratio is a constant value. The efficiency is higher than in the conventional case.
[0046]
Also The photovoltaic power generation system further includes control means for controlling the boosting ratio of the boosting circuit so that the output power of the photovoltaic power generation system is maximized based on the output signal of the signal generating circuit, and the boosting unit further includes And a setting means for setting the boosting ratio of the boosting circuit to a predetermined value, and a selection means for selecting one of the control means and the setting means. Therefore This is convenient when adding a second solar cell array.
[0047]
Preferably, further, a protection unit is provided for stopping the boosting operation of the booster circuit when the output voltage of the booster circuit exceeds a predetermined value. In this case, it is possible to prevent the output voltage of the booster circuit from becoming too high and destroying the system.
[0048]
Further preferably, a display means for displaying the output power of the second solar cell array based on the detection result of the power detector is further provided. In this case, the output power of the second solar cell array can be confirmed, which is convenient.
[0049]
Further, in the power conditioner according to the present invention, an inverter circuit that combines the output power of the first solar cell array and the output power of the boosting unit, converts the combined DC power into AC power, and supplies the AC power to the load circuit; A first power detector that detects the output power of the inverter circuit, and a control that controls the boost unit and the inverter circuit so that the output power of the power conditioner is maximized based on the detection result of the first power detector. Means. Therefore, since the booster unit and the inverter circuit are controlled based on the detection result of the first power detector so as to maximize the output power of the power conditioner, the booster ratio of the booster unit is manually set as in the prior art. Eliminates the need for system setup. Further, even when the output voltage of one of the first and second solar cell arrays changes due to the influence of solar radiation, the boost ratio of the boost unit can be controlled to the optimum value accordingly, so that the boost ratio is a constant value. The efficiency is higher than in the conventional case.
[0050]
Also The boosting unit further includes a second power detector that detects the output power of the second solar cell array, and the output power of the second solar cell array based on the detection result of the second power detector. And a signal generating circuit for outputting a signal indicating whether the voltage has increased or decreased, and the control means controls the boosting ratio of the boosting unit based on the output signal of the signal generating circuit. This By The boost ratio of the boost unit can be easily controlled.
[0051]
Ma The The control means includes a first step of controlling the input voltage of the inverter circuit so that the output power of the inverter circuit increases while the input voltage of the boosting unit is held constant, and the input voltage of the inverter circuit is constant. And a second step of controlling the boosting ratio of the boosting unit so that the output power of the second solar cell array increases during the held period. Therefore Since the boosting ratio of the boosting unit and the inverter circuit are controlled alternately, these controls can be performed easily and reliably.
[0052]
Further, in the photovoltaic power generation system according to the present invention, the boosting unit for boosting the output voltage of the second solar cell array, the output power of the first solar cell array and the output power of the boosting unit are combined, An inverter circuit for converting the combined DC power into AC power and a power conditioner including control means for controlling the boosting unit and the inverter circuit so as to maximize the output power of the photovoltaic power generation system are provided. Therefore, since the boosting ratio of the boosting unit is controlled by the control means so that the output power of the system is maximized, there is no need to manually set the boosting ratio of the boosting unit as in the prior art. It becomes easy. Even when the output voltage of one of the first and second solar cell rows changes due to the influence of solar radiation, the boost ratio of the boost unit is controlled to the optimum value accordingly, so that the boost ratio is constant. The efficiency is higher than the conventional case where the value is fixed.
[0053]
Also The control means includes a first step of controlling the input voltage of the inverter circuit so that the output power of the inverter circuit increases during a period in which the input voltage of the boosting unit is held constant, and the input voltage of the inverter circuit is made constant And a second step of controlling the boosting ratio of the boosting unit so that the output power of the second solar cell array increases during the held period. Therefore Since the boosting ratio of the boosting unit and the inverter circuit are controlled alternately, these controls can be performed easily and reliably.
[0054]
Preferably, there is further provided a setting means for setting the boosting ratio of the boosting unit to a predetermined value, and a selecting means for selecting one of the control means and the setting means, and the boosting ratio of the boosting unit is provided. Are controlled or set by the control means or setting means selected by the selection means. This case is suitable for adding a second solar cell array.
[0055]
Preferably, further, a protection unit is provided for stopping the boosting operation of the boosting unit when the output voltage of the boosting unit exceeds a predetermined value. In this case, it is possible to prevent the output voltage of the boosting unit from becoming too high and destroying the inverter circuit or the like.
[0056]
Preferably, a display means for displaying the output power of the second solar cell array is further provided. In this case, the output power of the second solar cell array can be confirmed, which is convenient.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram showing a configuration of a photovoltaic power generation system according to an embodiment of the present invention.
FIG. 2 is a time chart for explaining the operation of the photovoltaic power generation system shown in FIG. 1;
FIG. 3 is a circuit block diagram showing a configuration of a conventional photovoltaic power generation system.
4 is a block diagram showing a configuration of a boost control unit shown in FIG. 3. FIG.
5 is a diagram for explaining the operation of the photovoltaic power generation system shown in FIG. 3. FIG.
6 is another diagram for explaining the operation of the photovoltaic power generation system shown in FIG. 3. FIG.
7 is still another diagram for explaining the operation of the photovoltaic power generation system shown in FIG. 3. FIG.
8 is a diagram for explaining problems of the photovoltaic power generation system shown in FIG. 3. FIG.
FIG. 9 is another diagram for explaining problems of the photovoltaic power generation system shown in FIG. 3;
[Explanation of symbols]
1a, 31a standard solar cell string, 1b, 31b non-standard solar cell string, 2,45 power conditioner, 3, 4, 14, 15, 36, 37, 41, 42 diode, 5 inverter circuit, 6 inverter control unit, 7,20 Current detector, 8, 18, 19 Voltage detector, 9 Boost unit controller, 10, 32 Boost unit, 11, 33 Boost circuit, 12, 34 reactor, 13, 35 Switching transistor, 16, 38 Capacitor, 17, 39 Step-up control unit, 21 Display unit, 22, 46 Commercial power system, 40 Junction box, 43 Lightning surge absorber, 44 Breaker, 51 Step-up ratio setting unit, 52 Signal setting calculation unit, 53 Triangular wave generation unit, 54 Signal comparison Part, 55 Gate drive part.

Claims (8)

A first solar cell array including a first number of solar cells connected in series; and a second solar cell array including a second number of solar cells smaller than the first number connected in series. In a photovoltaic power generation system that is connected at least and that converts DC power generated by the first and second solar cell arrays into AC power and applies it to a load circuit, the output voltage of the second solar cell array is boosted Boosting unit for matching the output voltage of the first solar cell array,
A step-up circuit capable of controlling a step-up ratio for stepping up the output voltage of the second solar cell array;
A power detector for detecting output power of the second solar cell array, and a signal indicating whether the output power of the second solar cell array has increased or decreased based on a detection result of the power detector; It has a signal generation circuit to output ,
The solar power generation system further includes control means for controlling the boost ratio of the booster circuit so that the output power of the solar power generation system is maximized based on the output signal of the signal generation circuit,
The boost unit is
And setting means for setting the boost ratio of the booster circuit to a predetermined value;
Ru comprising a selection means for selecting either one of said control means and said setting means, boost unit. 2. The boosting unit according to claim 1, further comprising protection means for stopping the boosting operation of the booster circuit when the output voltage of the booster circuit exceeds a predetermined value. Furthermore, the pressure | voltage rise unit of Claim 1 or Claim 2 provided with the display means for displaying the output electric power of a said 2nd solar cell row | line | column based on the detection result of the said power detector. A first solar cell array including a first number of solar cells connected in series and a second solar cell array including a second number of solar cells smaller than the first number connected in series. And at least connected to a boost unit capable of controlling a boost ratio for boosting the output voltage of the second solar cell array to match the output voltage of the first solar battery array, A power conditioner that converts direct current power generated by a solar cell array and output power of the boosting unit into alternating current power and applies it to a load circuit,
An inverter circuit that combines the output power of the first solar cell array and the output power of the boosting unit, converts the combined DC power into AC power, and applies the AC power to the load circuit;
A first power detector for detecting output power of the inverter circuit; and the boost unit and the inverter so that the output power of the power conditioner is maximized based on a detection result of the first power detector. Comprising control means for controlling the circuit ;
The boost unit is
A second power detector for detecting an output power of the second solar cell array; and
A signal generation circuit that outputs a signal indicating whether the output power of the second solar cell array has increased or decreased based on the detection result of the second power detector;
The control means controls the boost ratio of the boost unit based on the output signal of the signal generation circuit,
The control means includes
A first step of controlling the input voltage of the inverter circuit so that the output power of the inverter circuit increases during a period in which the input voltage of the boosting unit is held constant; and
A power conditioner including a second step of controlling a boost ratio of the boost unit so that output power of the second solar cell array increases during a period in which the input voltage of the inverter circuit is held constant . A first solar cell array including a first number of solar cells connected in series; and a second solar cell array including a second number of solar cells smaller than the first number connected in series. A photovoltaic power generation system that is connected at least and that converts DC power generated by the first and second solar cell arrays into AC power and applies the AC power to a load circuit;
A step-up unit capable of controlling a step-up ratio for boosting the output voltage of the second solar cell array to match the output voltage of the first solar cell array;
An inverter circuit that combines the output power of the first solar cell array and the output power of the boosting unit, converts the combined DC power into AC power, and applies the AC power to the load circuit; and the output power of the photovoltaic power generation system A power conditioner including control means for controlling the boosting unit and the inverter circuit so that the
The control means includes
A first step of controlling the input voltage of the inverter circuit so that the output power of the inverter circuit increases during a period in which the input voltage of the boosting unit is held constant; and
A solar power generation system including a second step of controlling a boost ratio of the boost unit so that output power of the second solar cell array increases during a period in which the input voltage of the inverter circuit is held constant . Furthermore, a setting means for setting the boost ratio of the boosting unit to a predetermined value, and a selection means for selecting any one of the control means and the setting means,
The photovoltaic power generation system according to claim 5 , wherein the boosting ratio of the boosting unit is controlled or set by the control means or the setting means selected by the selection means. Furthermore, the solar power generation system of Claim 5 or Claim 6 provided with the protection means to stop the pressure | voltage rise operation of the said pressure | voltage rise unit according to the output voltage of the said pressure | voltage rise unit exceeding the predetermined value. Further comprising a display means for displaying the output power of the second solar cell strings, photovoltaic power generation system according to claim 5 of claim 7.

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