JPS60261360A - Starting method of solar light power generator system - Google Patents

Abstract

PURPOSE:To start a power converter with good response by shortcircuiting the output of a solar light generator by a switch element of a stepup chopper circuit when a solar light power generator system is stopped, thereby collecting an electromotive force by the shortcircuiting current. CONSTITUTION:The DC output of a solar battery 11 is converted through a power converter 13 to an AC, and connected through a switch 15 with an AC power system 14. The converter 13 has a stepup chopper 31 and an inverter 32, which are controlled by a controller 43 together with a current detector 42. Thus, when a solar light power generator system is stopped, a switch element 312 connected between DC terminals 301 and 302 of a solar battery 11 is operated, and shortcircuited through a DC reactor 311. The current in the shortcircuiting circuit is detected by a current detector 41, a level is detected from the signal 411 by the current detector 42 to monitor the electromotive force of the battery 11, thereby starting the converter 13.

Description

[Detailed Description of the Invention] [Technical Field of the Invention 1] The present invention relates to a solar cell system that converts the output current of a battery into a predetermined force. Appropriately monitor the electromotive force, and perform the following: Kada! 9!] 4p
``Regarding a method for starting a solar power generation system that can start [.

[Technical background of the invention]

As shown in Figure 1, a solar cell plate that generates electricity when irradiated with sunlight increases the output current Is beyond a certain value -E when the solar cell plate is kept at a constant value equal to the amount of solar radiation. Then, the output voltage Vs rapidly decreases to zero. Further, the maximum output power Pmax of a solar cell having such characteristics occurs when the output current is Iop, and the power value is given by the product of Iop and the output voltage Vop at this time.

A solar panel consists of 40 solar radio wave plates in one panel.
It is constructed by connecting a plurality of ~50 units in series or in parallel. For example, the configuration of the solar panel is
Constructed as shown in the figure. In the figure, 1 is a solar cell plate, and when it is irradiated with sunlight, the positive terminal 3 and the terminal 4
A negative polarity electromotive force is generated and an output of 5 is obtained. The solar cell panel 2 having the configuration shown in FIG. 2 is equivalently represented by the circuit shown in FIG. 3 in an electromotive state. Here, the numbers shown in FIG. 3 are the same as those in FIG. This thick 1ii% battery panel 2 ); j is the output 'small current Is and the output 'voltage VS [y, I
As shown in Fig. 4, the engagement curve changes with changes in the amount of solar radiation, and the maximum output point changes as shown by the three curves indicated by dotted lines in the figure.

Therefore, if you are operating a resistor connected to the solar panel 2 as a load that can produce maximum output when the solar radiation is 59 mW/cm, for example, due to a change in the weather, the solar radiation will change from 50 to 100 mW/cm. When it increases,
The operating point is the output when the solar radiation is 50 if the load is also a uniform curve.
-B Moves from the intersection A with the current vs. output voltage relationship curve to the intersection B with the output vs. current vs. voltage relationship curve when the solar radiation is 100 mW/d, and it is no longer possible to extract the maximum output. . Further, when the amount of solar radiation decreases from 5 Q m W/cr/I to, for example, l Q mW/+*, the operating point shifts to point C, which is significantly deviated from its maximum output point. In this way, the solar panel 2 whose output fluctuates as the amount of solar radiation changes! The output of a group of solar panels constructed by connecting several panels in series and parallel is also easily affected by the amount of solar radiation.

Therefore, as it is, it is not possible to efficiently extract output from the solar panel group, resulting in a solar power generation system with low efficiency. Usually, in order to effectively utilize the electromotive force of a solar power generation system, it is necessary to convert it into a stable old system, or to connect it to an AC power system, so it is necessary to convert direct current into alternating current. The former is composed of a DC-DC converter typified by a chopper, and the latter is composed of a DC-AC converter typified by an inverter.

[Problems with background technology]

In any of the above power conversions, the voltage of the solar cell is set relatively low due to the withstand voltage of the solar cell itself, so the switch elements used in the power conversion device must be designed with a greater withstand voltage margin than necessary. Being forced to
Further, since the solar cell voltage indicating the maximum output point varies depending on the amount of solar radiation, in the method of controlling the output voltage by pulse width control of the inverter circuit, the madder harmonic component included in the output voltage varies according to the voltage adjustment. As a result, when providing a filter circuit for removing harmonics from the output voltage, the filter circuit must be designed at the maximum value of the harmonics, taking into consideration the pulse width control range.

On the other hand, in the case of a power conversion device with a chopper circuit, by controlling the AC voltage of the inverter output to a predetermined value with the chopper circuit, the inverter can be controlled so that the pulse width is always constant. The harmonic components of the output voltage of the power converter can be made constant. In other words, in a power conversion device having a chopper circuit, the filter circuit only needs to be designed for harmonics at a specific pulse width.
Economical design of the filter circuit can be achieved.

For the above reasons, it is well known that the above-mentioned problems can be solved by providing a step-up chopper circuit in the power converter for photovoltaic power generation systems, whether it is a DC load, an AC load, or connected to an AC power system. It is.

FIG. 5 shows a conventional configuration example of a solar power generation system provided with a power conversion device having a boost chopper circuit.

In FIG. 5, 11 is a solar panel group consisting of a plurality of solar panels 2, 12 is a backflow prevention diode, 13 is a power conversion device consisting of a boost chopper circuit and an inverter circuit, and 14 is a power conversion device consisting of a boost chopper circuit and an inverter circuit. AC power system, 1
5 is a switch.

When starting up such a solar power generation system, in order to monitor whether the electromotive force of the solar power generator 11 is sufficient to start the power conversion device 13, conventionally, the electromotive force of the solar power generator 11 is monitored. A monitor circuit for monitoring the electromotive force is provided close to the solar power generator 11, and when the output of this monitor circuit exceeds a predetermined value, the boost chopper and the inverter are operated in a predetermined manner. A method of activating the power conversion device 13 has been considered. Here, since the operations of the boost chopper and the inverter are well known, their explanation will be omitted.

This monitor circuit connects the solar power generator 11 as shown in FIG.
In addition to this, it was configured with a solar panel 2 or a monitor circuit 21 that can measure sunlight irradiation. However, the sixth
With the configuration shown in the figure, the true electromotive force of the solar power generator 11 cannot be monitored. For example, in the figure, if the solar power generator 11 is blocked by clouds or the like and the monitor circuit 21 is receiving solar radiation, the electromotive force of the solar power generator 11 activates the power converter 13 due to the output of the monitor circuit 21. It is erroneously determined that the electromotive force is sufficient to cause the power conversion device 13 to start, and the start condition is satisfied and a start command is given to the power conversion device 13. However, since the solar power generator 11 does not have enough electromotive force to start the power conversion device 13, the control is performed to significantly deviate from the operating point shown in the explanation of the $4 diagram. This results in the disadvantage that the power converter 13 cannot be operated.

This drawback is more likely to occur as the scale of the solar power generator 11 becomes larger, and it becomes more difficult to start and operate the solar power generator 11.

[Purpose of the invention]

Therefore, the present invention operates the switch element of the step-up chopper circuit, which is one component of the power converter 13, when the solar power generation system is stopped, and forms a circuit that short-circuits the output of the solar power generator 11. After monitoring the weight and force of the generator 11 itself and confirming that it has sufficient electromotive force to start the power converter R13, sunlight that can reliably start the power converter 13 is used. Its purpose is to provide a method for starting a power generation system.

[Summary of the Invention] To achieve this object, the present invention provides a solar power generation system comprising a solar cell and a power conversion device having a step-up chopper circuit that converts the DC output of the solar cell into predetermined power. When the solar power generation system is stopped, the switching element of the boost chopper circuit that constitutes the power conversion device is turned on to short-circuit the DC terminals, and when the short-circuit current reaches a predetermined value, the boost chopper circuit is activated. The power converter is started by turning off the switch of the circuit.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

Components in FIG. 7 with the same symbols as in FIG. 5 have the same functions. Boost chopper circuit 31, inverter circuit 32
1 shows the basic configuration, and the principle of operation for converting direct current into alternating current is well known, so a description thereof will be omitted. In addition, ii: the i-current capacitor 33 is charged with electric current generated from the operation of the boost chopper circuit 31, [F! It has the effect of suppressing J-pull.

Comparing No. 7 V and No. 5 Hi-1 and describing the means involved, in the conventional Fig. 5, as shown in FIG. Is it due to detection point 1 of monitor number 21? ) In contrast, in Fig. 7, when the solar power generation system is stopped, the W1 flow terminals 301 and 302 of the solar converter 13 are activated.
The switch 312 connected between the DC terminals 30J and 302 is operated to short-circuit the DC terminals 30J and 302 through the reactor reactor 3]1, and the a! By detecting the current, the electromotive force of solar power generation i1.1 is monitored and the power conversion device 13 is activated.

That is, in the embodiment shown in FIG. 7, when the solar power generation system is stopped, the switch element 31 of the boost chopper circuit 31 is
2, the control circuit 43 applies an ON command to the DC terminal 30.
1 and 302 are shorted. That is, the solar power generator 11 has a backflow prevention diode 12-DC terminal 301-
The circuit formed from the DC reactor 311, the switch element 312, the current detector 41, and the DC terminal 302 causes an output current corresponding to the amount of solar radiation shown in FIG. 4 to flow.

Here, in the case of a solar power generation system, daily startup and shutdown are performed based on the electromotive force of the solar power generator 11, that is, the level of solar radiation. That is, to start up the solar power generation system, it is sufficient that the solar power generator 11 can supply power that is greater than the no-load loss of the power converter 13, so the current in the short circuit described above when starting up the system is 10 to 10% of the rated DC current. This is about 15%, and the current burden on the switching element 312 is well within the rated value.

Returning to the explanation of FIG. 7 again, the current flowing through the aforementioned short circuit is detected by the current detector 41, and the current detection signal 4 is detected by the current detector 41.
11 is level detected by a current detection circuit 42. Here, the current detection circuit 42 may be a well-known comparator, so a detailed explanation will be omitted.

When the amount of solar radiation increases and the electromotive force of the solar power generator 11 increases, the current flowing through the current detector 41 increases as shown in FIG. 4. The current detection signal 411 of the current detector 41 is detected by the current detection circuit 42 and its set value is determined to be sufficient to start the power converter 13. When the value is reached, an output signal 421 is generated.

When this output No. 45 421 is given as a starting command to the control circuit 43, the switch element 312 is turned off. At this time, the current flowing through the DC reactor 311 is charged to the capacitor via the free-wheeling diode 313. Thereafter, the boost chopper circuit 31 and the inverter circuit 32 are operated to control the inverter circuit 32 to maintain a constant pulse width, and at the same time, the boost chopper circuit controls the AC voltage of the group output to a predetermined value by inversely changing Jgf.

The above operation is shown in the time chart of FIG.

To explain the operation of the present invention using a time chart, when the resilience of the solar power generator 11 is not sufficient, a gate signal is given so that the switch element 312 of the boost chopper circuit 31 is continuously turned on, and the current is When the detection signal 41 reaches a predetermined value, the switching element 312 of the promotion chopper circuit 31 is activated.
Stop the gate from continuous arcing.

At this time, since the switching element 312 performs a chopper operation, it is made up of an element that has a self-extinguishing function, such as a turn-off thyristor, a power transistor, or a thyristor that has a commutation function, so it is continuously turned on. Since the off command can be given at the same time as stopping the gate, continuous arcing can be stopped instantly. After that, the boost chopper circuit 31 and the inverter circuit 32
can be started immediately, so the power converter 13
immediately transfers the electromotive force of the solar power generator 11 to the AC power system 1.
4 can be supplied.

In other words, the solar power generator 1 serves as a power source for the power conversion device 13.
Since the electromotive force of the photovoltaic power generator 11 is directly monitored and the power conversion device 13 is started based on the detected level, there is no difference between the detected value of the monitor circuit and the electromotive force of the solar power generator 11 as in the conventional method, and the result is accurate. It is possible to perform a start-up. Further, unlike the conventional method, an expensive monitor circuit such as a solar cell panel 2 or a device capable of measuring sunlight irradiation is not required, and it can be realized with an inexpensive and simple circuit.

Next, other embodiments of the present invention will be described.

In FIG. 8, which shows the time pulse of the embodiment of FIG. 7, when the current detection <= sign 411 reaches a predetermined value, the continuous conduction gate of switch element 3]2 of the boost chopper circuit 31 is stopped, and at 11 o'clock the boost chopper circuit 31, inverter circuit 3
However, there are no particular restrictions on how to start these two circuits due to the characteristics of the present invention. For example, if there is a transformer at the output of the inverter circuit 32, the inverter circuit 32 is started in advance and the transformer is activated. After suppressing the rushing 7U flow,
^°, The chopper circuit 31 may be activated, and the inverter circuit 32 is the same regardless of whether it is a self-excited inverter or a separately excited inverter.Furthermore, the present invention as shown in FIG. In the embodiment described above, an inverter circuit 32 is added, but the effects of the present invention are the same even if the DC-DC conversion system includes only a boost chopper circuit 31.

In addition, the current detector 41 generally
It can also be used as a DC current detector for protection or control. In addition, in the embodiment of the present invention shown in FIG. 7, the switch element 312 of the boost chopper circuit 31 is used as a gate for continuous conduction when the system is stopped, but the output of the solar power generator 11 is not constantly short-circuited, but is short-circuited intermittently. The electromotive force of the solar power generator 11 may be monitored by operating the solar power generator 11.

〔Effect of the invention〕

Thus, according to the present invention, in a solar power generation system comprising a solar cell having photovoltaic power and a power conversion device having a step-up chopper circuit that converts its DC output into predetermined power, when the solar power generation system is stopped, The switch element of the step-up chopper circuit that makes up the power conversion device is turned on to form a short circuit that shorts the solar power generator, and the current flowing through the short circuit is detected to accurately determine the electromotive force of the solar power generator. Since the power converter is activated by detecting the electromotive force generated by the solar power generator, there is no need for an expensive electromotive force monitor circuit, and there is no system malfunction due to the difference in electromotive force between the monitor circuit and the solar power generator. It is capable of responsive startup that can immediately supply electromotive force to the AC power system.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram of the output voltage vs. output current of the solar battery plate when the output current vs. output voltage of the solar battery plate is related, Figure 5 is a block diagram of the solar power generation system, and Figure 6 is the conventional solar power generation system. FIG. 7 is a block diagram of the system, and FIG. 8 is a time chart of FIG. 7. 1... Solar cell plate, 2. Solar panel, 34. Terminal, 5. Output, 11. Solar valve' [torque device, 12. Backflow prevention diode, 13. 2 power conversion islands, 14.
- AC power system, 31 - chopper circuit, 32 - inverter circuit, 41 - current detector, 411 - Ichihara detection circuit, 42 - Ichihara detection circuit, 421 - output signal, 43 -
- Control circuit, 431. , 432 Gate No. 43, 31
2 Switch element, 301, 302 DC'', 1. Child, :33 ・■] Current capacitor, 311...U-1 flow reactor, 313.・Fast flow diode, 15-switch. Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 6' Fig. 7/9 Fig. 8 Threshold r; +i A-2 method 1 lower 771

Claims (1)

[Claims] In a solar power generation system consisting of a solar cell having a photovoltaic force and a power conversion device having a step-up chopper circuit that converts the DC output of the solar cell into predetermined power, the power conversion is performed when the solar power generation system is stopped. The switch element of the step-up chopper circuit constituting the device is turned on and the DC terminals are short-circuited, and when it is detected that the short-term current has reached a predetermined value, the switch element of the step-up chopper circuit is turned off. 1. A method for starting a solar power generation system, characterized in that the power conversion device is started after the power converter is activated.