JPH0318911A - Output controller for power generating system of solar battery - Google Patents

Abstract

PURPOSE:To optimize the control of a solar battery over a wide range of the solar radiation energy by using a proportional gain correction means which corrects the output of a proportional computing element in response to the change of the solar radiation energy to output the corrected output. CONSTITUTION:A proportional gain correction means 40 consists of a power computing element 41 which obtains the output power of a solar battery 2 and a function computing element 42 which corrects the output of the element 31 based on the output power of the battery 2, and outputs the corrected output to an adder 33. Therefore,the output of the element 31 is multiplied by the output power of the battery 2 which changes in proportion to the solar radiation energy via the element 42. Thus it is possible to obtain a function equivalent to that using a variable gain proportional computing element. In other words, a voltage controller 30 having the variable proportional gain optimized regardless of the solar radiation energy can be obtained. As a result, a control constant can be optimized over a wide range of change of the solar radiation energy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an output control device for a solar cell power generation system, and in particular, an output control device for a solar cell power generation system, which controls the output current of a solar cell from a power converter disposed on the output side of the solar cell. , a power generation system that generates power by maintaining the output voltage of a solar cell at a set voltage determined by its operating point includes a voltage calculator that calculates the deviation of the solar cell output voltage from the set voltage, and a voltage calculator that calculates the deviation of the solar cell output voltage from the set voltage, and a current setting that outputs the output signal. a current calculator that calculates the deviation from the solar cell output current as a value;
The present invention relates to an output control device including a pulse width modulator that converts the output signal into a pulse width modulated on/off command signal and outputs the signal to the power converter.

[Conventional technology]

FIG. 6 is a connection diagram showing the configuration of a conventional solar cell power generation system and its output control device. In the figure, the solar power generation system includes a solar cell 2, a step-down converter 3 as a power converter placed on the output side of the solar cell 2, and a storage battery 4 placed on the output side of the step-down converter 3. A proportional/integral regulator (hereinafter referred to as P
Px! I
Output signal of ltm unit (sum of proportional gain and integral gain)'
A current regulator 13 that compares the actual output current value of the solar cell detected by the current detector 6A as a t-current set value, calculates the deviation, and outputs the result, and the output signal and a carrier wave such as a sawtooth triangular wave. The output control device 10 includes a pulse width modulator 14 that outputs a pulse train whose pulse width is modulated by binary control based on the cut and match of the pulse width modulator 14. The pulse width modulated pulse train of the output control device 10 turns on and off switching elements such as transistors in the step-down circuit.
It is supplied as an off control command signal, and the conduction rate of the chirotsuba and the output current of the solar cell 2 are controlled, so that the output voltage of the solar cell is maintained at a constant voltage determined by its operating point, and efficient power generation operation is achieved. It will be done.

Note that the setting value can be given to the voltage setting device 11 in two ways: by fixing it to a fixed voltage value in advance based on the voltage-current characteristics of the solar cell 2, and by adjusting the setting voltage in small steps and comparing it with the actual value. However, a method is known in which the voltage is shifted to a voltage (operating point) at which a larger amount of generated power can be obtained.

In addition, since the power generated by the solar cell 2 changes in response to changes in the amount of solar radiation, there is a difference in the power consumed by the load 5, but this difference is caused by the power supplied to the load by discharging the storage battery 4.
Conversely, power generation is sustained by charging the storage battery with the power generated by the solar cell.

Figure 7 is a connection diagram showing different conventional columns, main circuit 20
This example shows a power generation system that includes an inverter 23 as a power converter and supplies the obtained AC power to a power grid 25. In this case, the multiplier 22
2 and the AC voltage detected by the voltage detector 27 are multiplied together, and this is supplied to the current regulator 13 as the AC output current setting value (different from the conventional example described above), pulse width modulation. The switching elements of the inverter are controlled on/off by the output pulse train of the inverter 14.

In the case of Fig. 3, in order to set the output power factor to 1, the system should be
It is also known to replace the combination of the current regulator 13 and the pulse width modulator 14 with a hysteresis comparator, resulting in so-called current instantaneous value control.

[Problem to be solved by the invention]

FIG. 8 is a graph showing the general voltage-current characteristics (① workability) of solar cells, and FIGS. 9 and 10 are enlarged views of positions A and B in FIG. 8. In FIG. 8, the output current of the solar cell 8 changes significantly depending on the amount of solar radiation, as shown by the curve 100 representing the V time efficiency when the amount of solar radiation is large, and the curve 110 representing the characteristics when the amount of solar radiation is small. Therefore, the power generation amount Vp −L゛, or Vp・
Point Ps + P* 'fr where 2 is the largest
In other words, the power generation operation is performed while keeping the output voltage Vp constant as the operating point. Since the slope of the V plane line at the operating point P1 and that at the operating point P are different as shown in Figures 9 and 10, the voltage at the P regulator in Figures 6 or 7 is The proportional gain of the regulator 12 is normally determined to a constant value based on the slope of the V-plane line 100 when the amount of sunlight is large, and on the assumption that the V-plane line is a straight line when viewed microscopically. .

Now, in the device shown in Fig. 6, the current flowing through the load 5 increases, and as a result, the voltage of the storage battery 4 decreases to 9.
Assume that the output current factor 1 of Part 3 is increased by Δ factor 9. At this time, the output voltage Vp of the solar cell 2 becomes Δv as shown in FIG. 9 when the amount of solar radiation is large based on its V workability.
When the amount of solar radiation is small, the slope of the curve 110 is small as shown in FIG. 10, so the amount of radiation decreases by ΔvlI, which is larger than Δvh. Therefore, in order to return the output voltage of the solar cell to vp, the output control device 10 outputs a pulse train with a narrowed pulse width so as to reduce the conduction rate of the cap 3. and ζ are optimized according to the curve 100 when the proportional gain of the P regulator is constant and the amount of solar radiation is large.Please note that when the amount of solar radiation is large, the current increase is as shown in Figure 9. Pulse width change 11
It is possible to perform control to increase the output voltage by Δvh and bring it closer to Vp by reducing the output voltage by Δvh, but the voltage correction amount ΔVl for the current increase ΔΔ due to small solar radiation
If ΔvL is large, it is assumed that there is a large voltage drop of ΔvL in FIG. occurs, and this causes overcompensation in control when the amount of solar radiation is low, resulting in unstable operation of the power generation system. The same applies to power generation systems using inverters in the main circuit.

An object of the present invention is to optimize the control of solar cells over a wide range of changes in solar radiation by making the control constant of an output control device for changes in solar cell output voltage variable with respect to solar radiation. .

[Means to solve the problem]

In order to solve the above problems, according to the present invention, the output current of a solar cell is controlled by a power converter disposed on the output side of all solar cells, and the output voltage of the solar cell is set to be determined by its operating point. A power generation system that generates power by maintaining a voltage has a voltage regulator that calculates the deviation of the solar cell output voltage from the set voltage, and a current regulator that uses the output signal as a current set value to calculate the deviation from the solar cell output current. and a pulse width modulator that converts the output signal into a pulse width modulated on/off command signal and outputs it to the power converter, wherein the voltage regulator is Proportional/integral calculator with separate proportional calculator and integral calculator
a proportional gain correction means comprising an integral regulator and outputting a corrected proportional gain according to changes in the output total solar radiation of the proportional calculator; and a proportional gain correction means that adds the output of this correction means and the output of the integral calculator and an adder for output.

[Effect]

The proportional gain of the PI controller, which is set to a constant value in consideration of the v-manufacturing efficiency of solar cells when the amount of solar radiation is large, is corrected by the amount of electricity such as generated power and current that changes depending on the amount of solar radiation. With this configuration, the proportional gain of the P controller changes depending on the amount of solar radiation! Pond VI
Since the output of the voltage regulator, which is a P-modulator, can be controlled to correspond to the voltage change of the solar cell, it is controlled to be large when the amount of solar radiation is large and small when the amount of solar radiation is small. Even when the amount of solar radiation is small, the operating point of the solar cell can be maintained without overcompensation, and stable power generation operation can be performed. The proportional gain correction means can be composed of a power or current detector and a function calculator, and can be configured to measure the output power or output current of the solar cell and the intermediate current of the power converter.

By detecting the output current or output power of the power converter with a voltage detector or a current detector and inputting it to a calculator, calculations can be performed by converting the amount of solar radiation into an amount of electricity proportional to this. Furthermore, in a power generation system having a pilot cell or a solar radiation meter, the proportional gain can be corrected by inputting the output power or output current to a computing unit.

〔Example〕

Below is this release! A will be explained based on an example.

FIG. 1 is a connection diagram showing the configuration of a solar cell power generation system and its output control device, which is an embodiment of Jin's invention, and shows an example in which a step-down chopper is used as a power converter. In the figure, the output side of the solar cell 2 is provided with a step-down silicon capacitor 3 consisting of a switching element such as a switching transistor 3A, a flywheel diode 3B, a reactor 3C, a capacitor 3D, etc., and a storage battery 4. Power generation operation is performed while maintaining the operating point of the solar cell while adjusting the difference between the power required by the solar cell 2 and the output power of the solar cell 2, which changes depending on the amount of solar radiation, by charging and discharging the storage battery a4. On the other hand, voltage regulator 30° current regulator 13. and voltage adjustment of the output control device consisting of the pulse width modulator 14! The fJ device 3D has a proportional calculator 61 and an integral calculator 32 that compare the setting value of the t8E setting device 11 and the output voltage of the solar cell 2 to find the deviation, and has an adder 33. It is configured as a mechanical controller. Further, 40 is a proportional gain correction means; in the case shown in the figure, a power calculator 41 calculates the output power of the solar cell 2 based on the output voltage of the solar cell and the detected current of the current detector 6A; The function calculator 42 corrects the output of the proportional calculator 31 based on the output, and outputs the corrected output to the adder 33.

The proportional gain of the proportional calculator 31 is set to a constant gain suitable for optimizing the operating point P1 of the V workability (curve 100 in FIG. 8) of the solar cell 2 when the amount of solar radiation is large. Therefore, a constant current correction command ΔF is output for the voltage deviation ΔVl regardless of the level of solar radiation. On the other hand, the function calculator 42 calculates the operating point Ps of the solar cell 2.
It's P.

If the slope of the VI characteristic curve in the vicinity is equal to the straight line/L, it is configured as a multiplier. Therefore, the output of the proportional calculator 31 is multiplied by the output power of the solar cell 2, which changes in proportion to the amount of solar radiation, by the functional calculator 42. It is possible to obtain a function equivalent to using a proportional calculator with variable gain. In other words, 71 songs 1s1 when the amount of solar radiation is large in Fig. 9
It is possible to obtain a voltage regulator 30 having a variable proportional gain that is optimized for the voltage V. 00 and also for the V-force curve when the amount of solar radiation is small in FIG. 10.

FIG. 2 is a connection diagram showing a modification of the embodiment shown in FIG.
1 and is the amount of electricity proportional to the amount of solar radiation.

FIG. 3 is a connection diagram showing a solar cell power generation system and its output control device according to a different embodiment of the present invention.
It is composed of a function calculator 52 that multiplies the detected current and the output of the proportional calculator 31, and corrects the proportional gain by using the current that changes depending on the amount of solar radiation as an electrical quantity, so that the dead center differs from the previous embodiment.

The current detectors include a detector 6A that detects the output current of the solar cell 2, and a detector 6A that detects the intermediate circuit current of the step-down converter 3.
Either B or A6C for detecting the output current of the step-down sodium carbonate tube 3 may be used, and since the power calculator can be omitted, there is an advantage that the device can be simplified.

FIG. 4 is a connection diagram showing another embodiment of the present invention, in which a change in solar radiation is detected by a pilot cell 62, a short-circuit current detector 63, and a current detected by the detector 63 is used as a proportional gain correction signal. The function calculator 52 constitutes a proportional gain correction means, and the dead center is different from each of the above-described embodiments, and by applying it to a power generation system equipped with a pilot cell, the output control device can be further simplified. At the same time, it is possible to perform control that more accurately captures the change in p1 solar radiation by adjusting the arrangement and number of pilot cells.

FIG. 5 is a connection diagram showing another embodiment of the present invention, in which a change in solar radiation is detected as a voltage value by a solar radiation meter 70, and this detected voltage is used as a proportional gain correction signal for a function calculator 72. This differs from the previous embodiments in that it is applied to a power generation system equipped with a solar radiation meter, which simplifies the configuration of the device and provides control that accurately captures changes in solar radiation. It can be performed.

Each of the above-mentioned implementation rows is explained using the example of power generation system 1 using a step-down chip as a power converter, but it can be similarly applied to a power generation system using an I/P converter as a power converter. .

〔Effect of the invention〕

As described above, the present invention provides a voltage v14 of an output control device consisting of a voltage regulator, a current regulator, and a pulse width modulator.
The proportional calculator and the integral calculator are separated into a proportional-integral regulator, and a proportional gain correction means is added to change the output of the proportional calculator in response to changes in solar radiation, and the output and integral are added. It was configured to add the outputs of the arithmetic units using an adder and output the result. As a result, the V of the solar cell when the amount of solar radiation is large is
Conventionally, the proportional gain is fixed at a constant value based on I engineering, and the output of the proportional gain calculator can be corrected to a variable proportional gain that changes in proportion to changes in solar radiation using a proportional gain correction means. When the load current changes due to unoptimized low solar radiation, and the output voltage of the solar cell changes accordingly, the control of the output current of the power converter becomes overcompensated and becomes unstable. Equipped with an output control circuit that eliminates problems and can optimize control constants over a wide range of changes in solar radiation, the solar cell power generation system can provide electricity that changes relative to zero solar radiation. The amount is the output power and output current of the solar cell.

The intermediate circuit current of the power converter, the output power and output current of the power converter can be used, and the output current of the pilot cell and the output voltage of the solar radiation meter can also be used. The advantage of using a detector is that the device can be simplified.

[Brief explanation of drawings]

Fig. 1 is a connection diagram showing the configuration of a solar cell power generation system and its output control device according to the present invention, and Fig.
3 is a connection diagram showing a modification of the embodiment shown in the figure; FIG. 3 is a connection diagram showing the configuration of a device according to a different embodiment of the present invention;
The figure is a connection diagram showing the configuration of a device according to another embodiment of the invention, FIG. 5 is a connection diagram showing the configuration of a device according to another embodiment of the invention, and FIGS. 6 and 7 are conventional Fig. 8 is a graph showing the general voltage-current characteristics of solar cells, and Figs. 9 and 10 are connection diagrams showing the configurations of different solar cell power generation systems and their output control devices. It is a graph which enlarges and shows part A and part B, respectively. 1.20...Main circuit, 2...Solar cell, 3...Power converter (step-down carbon dioxide), 4...Storage battery, 5...
Load, 6AI6B, 6C...Current detector, 7,27.
... Voltage detector, 11... Voltage setter, 12... Voltage regulator, 13... Current regulator, 14... Pulse width modulator, 22... Multiplier, 23... Power converter (inverter), 25... Power system, 30... Voltage regulator (PI regulator), 41... Proportional calculator, 42...
Integral calculator, 33... Adder, 40... Proportional gain correction means, 41... Power calculator, 42, 52, 72
...Function calculator, 62...Pilot cell, 63.
...Current detector, 70... Don't expose yourself to sunlight? IA3 Ward Figure 4

Claims (1)

[Claims] 1) A power generation system that controls the output current of a solar cell with a power converter placed on the output side of the solar cell, and generates power by maintaining the output voltage of the solar cell at a set voltage determined by its operating point. A voltage regulator that determines the deviation of the solar cell output voltage with respect to the voltage, a current regulator that uses the output signal as a current setting value to determine the deviation from the solar cell output current, and a pulse width modulated on/off command for the output signal. An output control device comprising a pulse width modulator that converts the signal into a signal and outputs the signal to the power converter,
The voltage regulator is composed of a proportional/integral regulator in which a proportional calculator and an integral calculator are separated, and a proportional gain correction means for correcting the output of the proportional calculator in accordance with changes in solar radiation and outputting the corrected output. , and an adder that adds and outputs the output of the correction means for ζ and the output of the integral calculator.