JP2001325031A - Solar power generation controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solar power generation controller, capable of adding changes in power generation environment, such as amount of solar radiation, and performing the quick maximum power point tracing control. SOLUTION: Output voltages W1, W2, and W3 in operating voltages V1, V2, V3 (V3<V1<V2) are obtained successively (steps T1-T13). When a first condition (W1>W2 and W1>W3) or a second condition (W1<W2 and W1<W3) is satisfied (steps T14, T16; YES), this voltage is returned to the voltage V1. When the first and second conditions are not satisfied and a third condition (W2>W1) is satisfied (a step T17: 'YES'), the voltage is increased to the voltage V2 (step T18). When the third condition is not satisfied (the step T17: 'NO'), the voltage is decided to the voltage V3 (the step T1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic power generation control device for tracking and controlling the maximum power operating point of a solar cell.
In particular, the speed of the tracking control is increased to enable accurate control even when the power generation environment of the solar cell changes drastically.

[0002]

2. Description of the Related Art A solar cell that generates DC power when exposed to light has a point (voltage, current value) at which a maximum output power is generated depending on a power generation environment such as weather (illuminance of light) and temperature of a solar cell element. Changes. FIG. 9 shows the current and power of the solar cell when the irradiance (W / m ² ) changes.
3 shows voltage characteristics. In a photovoltaic power generation system, maximum power point tracking (MPPT) control is indispensable in order to effectively use limited solar cell output. The MPPT control controls the operating voltage and current of the solar cell so that the output power of the solar cell that changes according to the power generation environment is always maximized. Currently, it is used in most solar power systems.
Various methods have been devised for tracking the maximum power point of the solar cell. However, when the power generation environment changes drastically, it is not always possible to quickly track the power generation environment.

FIG. 10 is a block diagram for performing conventional MPPT control. In the figure, 1 is a solar power generation system, 2 is a solar cell, 3 is a circuit for monitoring the output voltage of the solar cell 2, 4 is a circuit for monitoring the output current of the solar cell 2, and 5 is a MPPT control by a microprocessor. The microprocessor is provided with an AD converter for reading a solar cell operating voltage value and a current value. Reference numeral 6 denotes a DC / DC converter (or DC / AC inverter) which is a power converter of the photovoltaic power generation system, and reference numeral 7 denotes a load or, in the case of a system interconnection type, a commercial system power supply. Here, the microprocessor of the controller 5 can calculate the output power of the solar cell 2 by multiplying the voltage and the current of the solar cell 2 and store the voltage and the power value at that time in the memory. The controller 5 is a DC / DC converter (or DC / AC
Inverter) 6 controls the output of solar cell 2
Operating voltage can be changed.

Next, the operation of the MPPT control will be described. The controller 5 changes the output power of the solar cell by periodically changing the operating voltage of the solar cell 2,
By monitoring the value, it is determined which solar cell operating voltage has the highest output power. If a solar cell operating voltage with a large output power is found, the voltage is used as a reference value for the next operating voltage, and then the operating voltage of the solar cell 2 is changed again to monitor the output power of the solar cell 2 at that time. Find the voltage with the largest output power. By repeating this, the maximum power point of the solar cell 2 is tracked.

The details of this control will be described in more detail with reference to the flowcharts shown in FIGS. Initially, when the solar cell operating voltage is V1, the microprocessor of the controller 5 monitors the output voltage V1 of the solar cell 2 and the output current I1, and calculates the solar cell output power W1 by multiplying V1 by I1. Then, the values of V1 and W1 are stored in the memory (steps S1 to S3). Next, in accordance with an instruction from the controller 5, the DC / DC converter 6 increases or decreases its output power, thereby increasing the DC power as viewed from the solar cell 2.
By changing the impedance of the / DC converter 6, the operating voltage of the solar cell 2 is changed stepwise to an arbitrary voltage value V2, which is several volts higher than V1 (step S4). The microprocessor of the controller 5 waits for a certain period (for example, 0.5 seconds) at which the operating voltage of the solar cell 2 will settle to V2 (step S).
5) Measure the solar cell output current I2 at V2,
And I2 are multiplied to calculate the solar cell output power W2, and the values of V2 and W2 are stored in a memory (steps S6 to S6).
S8).

In this way, the operating voltage and the output power of the solar cell 2 are stored two by two, and the operating voltage of the solar cell outputting more power is set as a new reference point. If the power increases when the solar cell operating voltage is changed from the initial V1 to a higher voltage point V2 (YES in step S9), the next reference point is set to V2, and the point to be moved next is also set to a point higher than V2. It is changed (step S10). Conversely, if the power decreases (NO in step S9), the point to be moved next is V1
The voltage value is changed to a voltage value V3 lower by an arbitrary voltage value (step S11).

Here, a certain period for settling (0.5
(Seconds) (step S12), the solar cell output current I3 at the time of V3 is measured, the solar cell output power W3 is calculated by multiplying V3 by I3, and the values of V3 and W3 are stored in the memory. (Steps S13 to S15). And the voltage V
3, when the power increases (step S16).
Is YES), the next reference point is set to V3, and step S11 is performed.
And the direction shifts to the direction of further lowering the voltage. Conversely, when the power has decreased (NO in step S16), the process returns to step S4, and shifts to the direction of increasing the voltage again.

[0008] In this way, the output power at each solar cell operating voltage is compared, and the solar cell operating voltage that is outputting higher power is newly set as the reference operating point V1. By repeating such control, the maximum output power of the solar cell is tracked.

[0009]

However, in this method, when fluctuations of solar radiation occur continuously, it may not always be possible to accurately track the maximum power point. In other words, when the amount of solar radiation increases continuously and the power generated by the solar cell increases continuously, the power generation continues to increase despite the higher operating voltage of the solar cell being closer to the maximum power point. Therefore, it may not be possible to correctly track the maximum power point, and the operating voltage to be tracked may move in the opposite direction to the lower side. Further, this adverse effect is promoted by prolonging the interval between the measurement points of the output power at two operating points having different voltages. That is, in order to shift the voltage set value from the current value to the next set value that is changed stepwise, and to measure the accurate output power at the voltage after the shift, the solar cell must be stable at the voltage after the shift. It takes time to reach the set operating state and settling time.

Incidentally, the time required for this settling depends on the characteristics and installation conditions of the solar cells, the units between the solar cells, and the DC / DC voltage.
The length of the connection wiring to the DC converter, and also the DC / D
Since it greatly changes depending on the circuit conditions including the C converter and the like, from the viewpoint of obtaining accurate output power, it is usually necessary to set a longer time of about 0.5 seconds with a margin as described above. As a result, the measurement interval becomes longer, which is a factor that adversely affects the control of tracking the maximum power operating point when the amount of solar radiation varies. Of course, if this setting takes a long time, even if there is no fluctuation in the amount of solar radiation, it will be slower to reach the maximum power operating point, so that the average operating efficiency of the solar cell may be reduced. Become.

Various solutions have been studied in the past as solutions to the above disadvantages. That is, for example, Japanese Patent Application Laid-Open No. 7-646
No. 60 discloses a method for tracking the maximum power of a solar cell, in which a new superimposed voltage source or superimposed current source is newly provided, so that a new voltage set value or current set value can be quickly followed. However, this method has a problem that expensive hardware such as a superimposed voltage source or a superimposed current source is required and a main circuit configuration is complicated.

As a method for simultaneously detecting a change in the amount of solar radiation, for example, Japanese Patent Application Laid-Open No. 6-35555 discloses a method of changing the voltage set value from V1 to V2 and returning it to V1 again to reduce the output power at three times. A control method for measuring and comparing the maximum power point of the solar cell from these comparisons is disclosed. However, in this case, one comparison operation is performed based on the three data at the three time points to determine the voltage set value in the next step, so that the control operation must be delayed by that much, and among the three points, Since the data at the two points have the same operating voltage and are used only for determining a change in the amount of solar radiation and cannot be used as data for detecting the current position on the power-voltage characteristic, the control response of the maximum power point tracking results. I have to say that it is not enough.

Further, for example, Japanese Patent Application Laid-Open No. Hei 9-131081 measures output power at a plurality of operating points of voltage or current, and determines maximum power according to the curvature of a voltage (current) -power characteristic curve obtained from these data. Disclosed is a battery power control device for tracking the direction of a point. Here, at least, a complicated calculation process of calculating the curvature of an approximate curve determined by a polar function formula from a plurality of measurement data is required, and the software becomes more complicated and the calculation processing time becomes longer. It is difficult to realize quick tracking control.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to substantially reduce the time required for settling when changing the set value of voltage or current by maximizing the time. An object of the present invention is to provide a photovoltaic power generation control device capable of accelerating a control operation for power point tracking. Another object of the present invention is to provide a photovoltaic power generation control device that enables quick maximum power point tracking control while taking into account changes in the power generation environment such as the amount of solar radiation.

[0015]

According to a first aspect of the present invention, there is provided a photovoltaic power generation control device which converts power from a solar cell to a voltage or a load and supplies the converted power to a load or a grid.
By controlling the power detection means for detecting the output power of the solar cell, and the power conversion means, the set values of the voltage or current of the solar cell are sequentially changed stepwise, and a plurality of operations in which these set values are different from each other In a photovoltaic power generation control device provided with power control means for tracking and controlling the maximum power operation point of the solar cell from a comparison of the output power of the solar cell at a point, a change in the voltage or current of the solar cell as a set value is monitored. When the monitoring means is provided, and after the power detection at the first operating point is completed, the set target value is changed to the set target value in the next step and the operation shifts to the second operating point at which power is to be detected next. A deviation between the output of the monitoring means and the target value set in the next step is detected, and the output power detection value when the deviation falls within a predetermined range is determined by the second operation. It is an output power at.

Further, in the photovoltaic power generation control device according to the second aspect, when shifting from the first operating point to the second operating point, the set target value is changed to the set target value in the next step. When the elapsed time is detected and the deviation amount does not fall within a predetermined range at the time when the elapsed time reaches a predetermined time, the output power detection value at the predetermined time is output to the second operating point. It is power.

According to a third aspect of the present invention, there is provided a photovoltaic power generation control device, comprising: a power conversion means for converting power from a solar cell to supply the converted voltage to a load or a system; Means, and the set value of the voltage or current of the solar cell is sequentially changed stepwise by controlling the power conversion means, and these set values are compared with the output power of the solar cell at a plurality of operating points different from each other. In a photovoltaic power generation control device including a power control unit that determines an operation set value to be adopted and tracks and controls a maximum power operation point of the solar cell, a comparison of output power is performed when the first set value is used. An output power detection value W1; an output power detection value W2 when operating at a second set value increased or decreased by a predetermined amount from the first set value;
The output power detection value W3 when operating at a third set value that is decreased or increased by a predetermined amount from the set value is performed for the first condition (W1> W2 and W1> W3) and the second condition. When either of the conditions (W1 <W2 and W1 <W3) is satisfied, the first set value is determined as the operation set value. When both the first and second conditions are not satisfied,
The setting value of the one having the maximum output power detection value among the above three is determined as the operation setting value.

According to a fourth aspect of the present invention, there is provided a photovoltaic power generation control device, comprising: a power conversion means for converting the power from a solar cell to supply the converted voltage to a load or a system; Means, and the set value of the voltage or current of the solar cell is sequentially changed stepwise by controlling the power conversion means, and these set values are compared with the output power of the solar cell at a plurality of operating points different from each other. In a photovoltaic power generation control device including a power control unit that determines an operation set value to be adopted and tracks and controls a maximum power operation point of the solar cell, a comparison of output power is performed when the first set value is used. An output power detection value W1; an output power detection value W2 when operating at a second set value increased or decreased by a predetermined amount from the first set value;
The output power detection value W3 when operating at a third set value that is decreased or increased by a predetermined amount from the set value is performed for the first condition (W1> W2 and W1> W3) and the second condition. When either of the conditions (W1 <W2 and W1 <W3) is satisfied, the first set value is determined as the operation set value, and both the first and second conditions are not satisfied, and the third set value is not satisfied. When the condition (W2> W1) is satisfied, the second condition
Is determined as the operation set value, and when the third condition is not satisfied, the third set value is determined as the operation set value.

According to a fifth aspect of the present invention, in the photovoltaic power generation control device according to the third or fourth aspect, the detection of the output power at each operating point is performed according to the first or second aspect. This is performed by a control method.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a flowchart for explaining MPPT control of the solar power generation control device according to Embodiment 1 of the present invention. The hardware configuration of the control device is the same as that of the conventional device shown in FIG. In the MPPT control proposed this time, the set value of the voltage or current of the solar cell is sequentially changed stepwise, and the maximum power operating point of the solar cell is determined by comparing the output power of the solar cell at a plurality of operating points where these set values are different from each other. The conventional operation voltage value to be adopted next is determined from comparison of output powers at two operation points having different voltage values in the conventional FIG. From the comparison of the output powers at the three different operating points, the operating voltage value to be adopted next is determined.

Hereinafter, the control operation will be described in detail with reference to the flowchart of FIG. 1 while referring to FIG. 2 showing operating points on the power-voltage characteristics of the solar cell. First, the solar cell output current I1 is measured using the current solar cell operating voltage V1 as a first set value (step T1), and the microprocessor of the controller 5 multiplies V1 and I1 to obtain the solar cell output power W1. Is calculated (step T2), and the values of V1 and W1 are stored in the memory (step T3).
Next, the set target value is moved to V2, which is the second set value that is higher than V1 by a predetermined amount (step T4).
The / DC converter 6 increases / decreases its output power and changes the impedance of the DC / DC converter 6 viewed from the solar cell 2 to increase the operating voltage, and waits for 0.5 seconds for this settling (step) T5). In addition,
In the first embodiment, a certain time (0.
(5 seconds) Waiting is the same as before.

The operating voltage V2 and the output current I2 after settling are measured (step T6), and the microprocessor of the controller 5 calculates the solar cell output power W2 by multiplying V2 by I2 (step T7). V in memory
The values of 2 and W2 are stored (step T8).

Next, the set target value is moved to V3 which is a third set value lower than the initial V1 by a predetermined amount (step T).
9) In response, the DC / DC converter 6 increases / decreases its output power and changes the impedance seen from the solar cell 2 to lower the operating voltage, and waits for 0.5 seconds for this settling. (Step T10). The set operating voltage V3 and output current I3 are measured (step T1).
1) The microprocessor of the controller 5 calculates the solar cell output power W3 by multiplying V3 by I3 (step T12), and stores the values of V3 and W3 in a memory (step T13).

The different operating voltages V1, V2, V stored in the memory by the above steps T1 to T13.
3 (V3 <V1 <V2), the output powers W1, W2,
Steps T14 and T1 to be described later for comparing the magnitudes of W3.
6. At T17, the operation setting value to be adopted next is determined based on the result.

By the way, three output power measured values W1, W
2. The magnitude relationship between W3 and K3 in pure mathematical terms shown in Table 1
There are six cases of K6.

[0026]

[Table 1]

Here, the measurement time elapses in the order of W 1 → W 2 → W 3, and the amount of solar radiation as the power generation environment decreases, increases, or hardly changes over time. That three cases are assumed,
Further, as shown in FIG. 3, even when the value of the output power fluctuates due to the fluctuation of the amount of solar radiation, the phenomenon that the voltage at the maximum power point of the solar cell at each amount of solar radiation does not change much is recognized. As a result of the comparison of the output powers at the points, when it is determined that the amount of solar radiation has changed during that time, it is considered that the output power is larger as a whole of the tracking control operation if the operating voltage is not changed.

Based on the above prerequisites, a description will be given for each case shown in Table 1 with respect to the contents of judgment that are highly likely and the output of the set voltage value to be adopted as a result of the judgment. First, in case K1 (W1>W2> W3), the output power monotonically decreases as the measurement time elapses, and one of the reasons is that the amount of solar radiation continuously decreases during this period.
In this case, as described above, it is advisable not to move the set voltage value, and the original voltage V1 is adopted. In addition, since the output power W1 at the voltage V1 at the center of the voltages at the three points is the maximum, another possibility is that there is no change in the amount of solar radiation during this time, and that the voltage V1 is at or near the maximum power operating point. It is possible that there is. Therefore, in this case, the voltage to be adopted is V1.

Next, case K2 (W1>W3> W2)
A continuous change in the amount of solar radiation is unlikely, there is no change in the amount of solar radiation, and there is a high possibility that the voltage V1 is near the maximum power operating point as in the case K1, and in this case, the voltage V1 should be used naturally. . As described above, in the cases K1 and K2, V1 should be adopted as the next set value. Therefore, in the flowchart of FIG. 1, this is set to the first condition (W1> W2 and W1> W3) in step T14. It is determined that the condition is satisfied (YES), and in this case, the operating voltage is returned to V1 (step T1).
5).

Cases K3 to NO in Step T14
Of K6, the case K4 (W2>W3> W1) does not occur unless a specific change in the power generation environment is assumed, so it is considered that it is practically unlikely to occur, and may be excluded here. In case K6 (W3>W2> W1), the output power monotonically increases as the measurement time elapses, and it is conceivable that the solar radiation continuously increases during this time. In this case, as described above, it is advisable not to move the set voltage value, and the original voltage V1 is adopted. Therefore, the cases K4 and K6 are changed to the second condition (W1 <W2) in step T16.
In addition, it is determined that W1 <W3) holds (YES), and the operating voltage is returned to V1 (step T15).

Of the remaining two cases K3 and K5 for which a negative determination was made in step T16, case K3 (W2>W1> W3)
In the case of, the possibility of a change (decrease or increase) in the amount of insolation is excluded by the discrimination in the steps T14 and T16 so that the change in the amount of insolation may be considered to be almost non-existent. Operating voltage V2 at the output power W2. This is determined when the third condition (W2> W1) is satisfied (YES) in step T17,
The voltage is increased to the operating voltage V2 (step T18). In addition,
This case K3 corresponds to the case where the three voltages are located before the voltage at the maximum power point in FIG.

In the remaining case K5 (W3>W1> W2), as in case K3, no change in the amount of solar radiation may occur, so that the operating voltage V at the maximum output power W3 among the three points is obtained.
3 should be adopted. This case K5 corresponds to the case where the three voltages are in the portion exceeding the voltage at the maximum power point in FIG. In the flowchart of FIG. 1, this case K5 is not satisfied in step T17 (NO).
Then, the current operating voltage, that is, the operating voltage V3 at the last time point among the three points is set to the new V1, and therefore to the central voltage value of the three points of the next comparison operation (step T1).

In the above description, the equal sign is established between any of the three output powers (W1 = W2, W2 = W
3, W3 = W1 or W1 = W2 = W3) is not mentioned, but when these signs are satisfied, that is, when the output power of the solar cell does not change even when the operating voltage is changed, the time of sunset is It is determined that the amount of solar radiation is extremely weak, such as cloudiness or cloudiness. Therefore, when this equality holds, the judgment and output result based on the contents described in Table 1 are not necessarily obtained. However, if such an extremely low output state continues for a certain period of time, the monitoring means (not shown) detects this. However, there is no particular problem since the solar cell is disconnected from the load or the system.

As described above, in the solar power generation control device according to Embodiment 1 of the present invention, it is possible to determine whether or not there is a change in the amount of solar radiation.
Without shifting the operating voltage, it is possible to perform a rational operation in which the output power becomes large as a whole, and if it is determined that there is no change in the amount of solar radiation, any one of the three different voltages has the maximum output power. Can be immediately determined, and the control operation for maximum power point tracking can be accelerated.

Note that step T in the flowchart of FIG.
17, it is determined whether W2> W1 is satisfied or not as a third condition. However, the output powers W1 and W3 of the three parties are determined.
2. Among the W3s, the largest one (here, either W2 or W3) may be selected and the voltage of the maximum output power operating point may be adopted.

In the above description, the set voltage is
After the voltage V1, the voltage V2 is obtained by increasing the voltage V1 by a predetermined amount, and then by the voltage V2 obtained by reducing the voltage V1 by a predetermined amount.
1, the voltage V2 is obtained by decreasing the voltage V1 by a predetermined amount, and then by increasing the voltage V1 by a predetermined amount. The quick maximum power point tracking control can be realized in a similar manner.

Embodiment 2 FIG. 4 is a block diagram showing a solar power generation control device according to Embodiment 2 of the present invention. In the second embodiment, the control speed of the tracking control is improved by shortening the time required for the settling described in the related art. Here, a constant monitoring means 51 is provided inside the controller 5 of FIG. The constant monitoring means 51 is configured to constantly monitor the operating voltage of the solar cell (or at a very fast repetition cycle of about 100 times per second).

Next, the operation will be described in detail with reference to FIG. 5 showing the operating point on the power-voltage characteristics of the solar cell and FIG. 6 showing the flow chart of the processing flow. The flowchart shown in FIG. 6 illustrates a configuration in which the constant monitoring unit 51 substantially reduces the settling time, as described in the first embodiment.
This is applied to tracking control of a method of determining an operating voltage value to be adopted from a comparison of output powers W1, W2, W3 at point voltages. Therefore, the duplicate description will be appropriately omitted.

In FIG. 6, steps U1 to U3 correspond to FIG.
And the values of V1 and W1 are stored in the memory. Next, in step U4, the set target value is moved to a second set value V2 higher than V1 by a predetermined amount,
In response, the DC / DC converter 6 increases or decreases its output power and increases the operating voltage of the solar cell.

FIG. 7 shows the process of this voltage rise. The voltage continues to rise from the value of V1 at time t1 to a target set value V2 by a time constant determined by various constants of the wiring including the solar cell 2 and the circuit including the DC / DC converter 6 and the load 7. . In the second embodiment, the voltage change is constantly monitored by the constant monitoring means 51, and it is constantly determined whether or not the difference between the monitored voltage and V2 is within 3% of ΔV = | V2-V1 |. (Step U51). If the voltage difference is not within 3% (NO in step U51), the operation set value is set to V
2, whether or not the elapsed time from the point of time when it is moved to 2 (corresponding to time t1 in FIG. 7) is 0.5 seconds or more, which is the time conventionally set as a sufficient time necessary for settling regardless of circuit conditions. Is determined (step U52). The determination operation of step U51 is repeated during less than 0.5 seconds.

If the voltage difference falls within 3% in step U51 (YES in step U51), the operating voltage V2 'and the output current I2' at that time are measured (step U6), and the microprocessor of the controller 5 outputs V2 '. 'And I2'
Is calculated by multiplying by (step U7), and the values of V2 'and W2' are stored in the memory (step U8). If the voltage difference does not fall within 3% even when the elapsed time from the time when the operation set value is moved to V2 becomes 0.5 seconds (YE in step U52).
S) At this point, the voltage monitoring is terminated, and steps U6 to U6 are performed.
At U8, the values of V2 'and W2' are stored. This case is intended to prevent the occurrence of some abnormality in the monitoring operation or the like and the setting time is unnecessarily lengthened, and is considered to be impossible in a normal control operation.

Since the operations in steps U9 to U13 are the same, detailed description is omitted, but in step U101, the difference between the monitored voltage and the operation set value V3 which is lower than V1 by a predetermined amount is ΔV = | V3 It is always determined whether or not −3% of −V1 |. If the voltage difference is within 3% (YES in step U101), the operating voltage V at that time
3 ', the output current I3' is measured, and the microprocessor of the controller 5 calculates the solar cell output power W3 'by multiplying V3' and I3 ', and stores V3' in the memory.
The values of 3 'and W3' are stored (steps U11 to U1).
3).

The operations in steps U14 to U18 are performed in the order of W2 →
Except for W2 ', W3.fwdarw.W3', V2.fwdarw.V2 ', and V3.fwdarw.V3', the contents are exactly the same as those described in FIG.

As described above, in the second embodiment, when the operating voltage is shifted from V1 to V2 and from V2 to V3, various circuit conditions are assumed as in the prior art, and sufficient for stabilization. The operating voltage is constantly monitored by the constant monitoring means 51, and the level can be regarded as almost settled (here, for example, the monitoring voltage). And V2
At the time when the difference from ΔV = | V2−V1 | is within 3%), the voltages V2 ′, W3 ′, etc. are obtained, and the processing shifts to the subsequent output power comparison calculation processing. Therefore, as a whole, the speed of the maximum power point tracking control is increased,
Further, since the time lag of the measurement of the output power at the three points is shortened by that amount, the influence of the change in the amount of solar radiation during that time is reduced, and the accuracy of tracking control can be expected to be improved.

FIG. 8 shows measured waveforms when the output voltage is changed in a real model of a photovoltaic power generation control device using an inverter. In this example, the current output voltage V0 = 200 V is shifted to the set target value voltage V1 = 198 V. FIG. 11A shows the solar cell output voltage, FIG. 10B shows the system voltage, and FIG. This shows the inverter output current. In this case, the output voltage is settled at about 0.05 seconds, and by applying the second embodiment, the speed of the tracking control is reduced as compared with the conventional case where the processing is uniformly performed for 0.5 seconds. Will rise significantly.

Incidentally, the specific numerical values (3%, 0.5 seconds) of the discrimination criterion used in steps U51 and U101 and steps U52 and U102 in FIG. 6 can be appropriately changed according to the capabilities and characteristics of the apparatus. Needless to say.

In FIG. 6, the invention of introducing the constant monitoring means 51 to realize a substantial reduction in the time for settling is described in the first embodiment in terms of the output power at three different voltages. Was applied to the invention that performs the maximum power point tracking control based on the comparison of the above, but the former invention can be widely applied to the case where the maximum power point tracking control is performed from the comparison of the output powers at arbitrary plural voltages different from each other. Has the same effect of increasing the

Further, in each of the above embodiments, the voltage value is employed as the set value when measuring the output power at a plurality of points. However, the current value is used as the set value, and the output power is calculated from the measured output voltage. Alternatively, the current value may be constantly monitored.

[0049]

As described above, the photovoltaic power generation control device according to claim 1 of the present invention is a power conversion means for converting power from a solar cell to a voltage and supplying the power to a load or a system.
By controlling the power detection means for detecting the output power of the solar cell, and the power conversion means, the set values of the voltage or current of the solar cell are sequentially changed stepwise, and a plurality of operations in which these set values are different from each other In a photovoltaic power generation control device provided with power control means for tracking and controlling the maximum power operation point of the solar cell from a comparison of the output power of the solar cell at a point, a change in the voltage or current of the solar cell as a set value is monitored. When the monitoring means is provided, and after the power detection at the first operating point is completed, the set target value is changed to the set target value in the next step and the operation shifts to the second operating point at which power is to be detected next. A deviation between the output of the monitoring means and the target value set in the next step is detected, and the output power detection value when the deviation falls within a predetermined range is determined by the second operation. Since the output power at the time required for settling is substantially reduced, it is possible to speed up the operation of the maximum power operating point tracking control.

Further, when shifting from the first operating point to the second operating point, the photovoltaic power generation control device according to claim 2 changes the set target value to the set target value in the next step. When the elapsed time is detected and the deviation amount does not fall within a predetermined range at the time when the elapsed time reaches a predetermined time, the output power detection value at the predetermined time is output to the second operating point. Since the power is used, it is possible to prevent the settling time from being unnecessarily increased due to an abnormality in the monitoring operation or the like.

According to a third aspect of the present invention, there is provided a photovoltaic power generation control device, comprising: a power conversion means for converting power from a solar cell to supply the power to a load or a system; Means, and the set value of the voltage or current of the solar cell is sequentially changed stepwise by controlling the power conversion means, and these set values are compared with the output power of the solar cell at a plurality of operating points different from each other. In a photovoltaic power generation control device including a power control unit that determines an operation set value to be adopted and tracks and controls a maximum power operation point of the solar cell, a comparison of output power is performed when the first set value is used. An output power detection value W1; an output power detection value W2 when operating at a second set value increased or decreased by a predetermined amount from the first set value;
The output power detection value W3 when operating at a third set value that is decreased or increased by a predetermined amount from the set value is performed for the first condition (W1> W2 and W1> W3) and the second condition. When either of the conditions (W1 <W2 and W1 <W3) is satisfied, the first set value is determined as the operation set value. When both the first and second conditions are not satisfied,
Of the above three, the set value of the output power detection value which becomes the maximum is determined as the operation set value, so that the maximum power operating point tracking control can be quickly performed in consideration of the change in the power generation environment, and a large power generation as a whole is achieved. Electricity can be secured.

A photovoltaic power generation control device according to claim 4 is a power conversion means for converting the voltage from the solar cell to supply the power to a load or a system, and a power detection means for detecting the output power of the solar cell. Means, and the set value of the voltage or current of the solar cell is sequentially changed stepwise by controlling the power conversion means, and these set values are compared with the output power of the solar cell at a plurality of operating points different from each other. In a photovoltaic power generation control device including a power control unit that determines an operation set value to be adopted and tracks and controls a maximum power operation point of the solar cell, a comparison of output power is performed when the first set value is used. An output power detection value W1; an output power detection value W2 when operating at a second set value increased or decreased by a predetermined amount from the first set value;
The output power detection value W3 when operating at a third set value that is decreased or increased by a predetermined amount from the set value is performed for the first condition (W1> W2 and W1> W3) and the second condition. When either of the conditions (W1 <W2 and W1 <W3) is satisfied, the first set value is determined as the operation set value, and both the first and second conditions are not satisfied, and the third set value is not satisfied. When the condition (W2> W1) is satisfied, the second condition
Is determined as the operation set value, and when the third condition is not satisfied, the third set value is determined as the operation set value. Tracking control becomes possible, and a large amount of generated power can be secured as a whole.

According to a fifth aspect of the present invention, in the photovoltaic power generation controller according to the third or fourth aspect, the detection of the output power at each operating point is performed according to the first or second aspect. Since the control method is used, it is possible to perform the maximum power operating point tracking control at higher speed and more accurately.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining an operation of MPPT control of a solar power generation control device according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing operating points on power-voltage characteristics of a solar cell.

FIG. 3 is a diagram for explaining movement of an operating point when the amount of sunlight changes.

FIG. 4 is a block diagram showing a configuration of a solar power generation control device according to Embodiment 2 of the present invention.

FIG. 5 is a diagram showing operating points on power-voltage characteristics of a solar cell.

FIG. 6 is a flowchart illustrating an operation of MPPT control according to the second embodiment.

FIG. 7 is a diagram showing a process of voltage rise during settling.

FIG. 8 is a diagram showing an actually measured waveform in an actual device model.

FIG. 9 shows the current of the solar cell when the irradiance changes,
FIG. 4 is a diagram illustrating power-voltage characteristics.

FIG. 10 is a block diagram illustrating a configuration of a conventional solar power generation control device.

FIG. 11 is a diagram showing operating points on power-voltage characteristics of a solar cell.

FIG. 12 is a flowchart illustrating an operation of a conventional MPPT control.

[Explanation of symbols]

1 solar power generation system, 2 solar cells, 3 voltage monitor circuit, 4 current monitor circuit, 5 controller,
51 Constant monitoring means, 6 DC / DC converter, 7
load.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G066 HA30 HB06 5H420 BB03 BB12 BB14 CC03 DD02 DD03 EB26 EB37 EB39 FF03 FF04 FF22

Claims (5)

[Claims] 1. A power conversion means for converting power from a solar cell to a voltage and supplying the converted power to a load or a system, a power detection means for detecting an output power of the solar cell, and controlling the power conversion means. The set value of the voltage or current of the solar cell is sequentially changed in a step-like manner, and the set value is used to track and control the maximum power operating point of the solar cell from a comparison of the output power of the solar cell at a plurality of operating points different from each other. In a photovoltaic power generation control device provided with a control means, a monitoring means for monitoring a change in a voltage or a current of a solar cell as a set value is provided. In the case of changing to the set target value of the step and shifting to the second operating point where power should be detected next, the deviation amount between the output of the monitoring means and the set target value of the next step is calculated Out,
A photovoltaic power generation control device characterized in that a detected output power value at the time when the deviation falls within a predetermined range is set as the output power at the second operating point. 2. When shifting from the first operating point to the second operating point, an elapsed time after the set target value is changed to a set target value in the next step is detected, and the elapsed time is determined in advance. 2. The method according to claim 1, wherein when the deviation amount does not fall within a predetermined range at a predetermined time, an output power detection value at the predetermined time is set as the output power at the second operating point. Solar power generation control device. 3. A power conversion means for converting power from a solar cell to a voltage and supplying the power to a load or a system, a power detection means for detecting an output power of the solar cell, and controlling the power conversion means. The set values of the voltage or current of the solar cell are sequentially changed in a step-like manner, and these set values are determined from the comparison of the output power of the solar cell at a plurality of operating points different from each other to determine an operation set value to be adopted. In a photovoltaic power generation control device provided with power control means for tracking and controlling a maximum power operating point, the output power comparison is performed by using an output power detection value W1 when operating at a first set value and the first set value. The output power detection value W2 when operating at the second set value increased or decreased by a predetermined amount from the value, and the third set value decreased or increased by the predetermined amount from the first set value And the output power detection value W3 at this time, and either the first condition (W1> W2 and W1> W3) or the second condition (W1 <W2 and W1 <W3) is satisfied. In this case, the first set value is determined as an operation set value. If both the first and second conditions are not satisfied, the set value of the three whose output power detection value is the maximum is operated. A photovoltaic power generation control device characterized by determining a set value. 4. A power conversion means for converting power from a solar cell to a voltage and supplying the power to a load or a system, a power detection means for detecting an output power of the solar cell, and controlling the power conversion means. The set values of the voltage or current of the solar cell are sequentially changed in a step-like manner, and these set values are determined from the comparison of the output power of the solar cell at a plurality of operating points different from each other to determine an operation set value to be adopted. In a photovoltaic power generation control device provided with power control means for tracking and controlling a maximum power operating point, the output power comparison is performed by using an output power detection value W1 when operating at a first set value and the first set value. The output power detection value W2 when operating at the second set value increased or decreased by a predetermined amount from the value, and the third set value decreased or increased by the predetermined amount from the first set value And the output power detection value W3 at this time, and either the first condition (W1> W2 and W1> W3) or the second condition (W1 <W2 and W1 <W3) is satisfied. When the first set value is determined as the operation set value, the first set value is determined as the operation set value. When both the first and second conditions are not satisfied and the third condition (W2> W1) is satisfied, the second set value is determined. Is determined as an operation set value, and when the third condition is not satisfied, the third set value is determined as an operation set value. 5. The photovoltaic power generation control device according to claim 3, wherein the detection of the output power at each operating point is performed by:
A photovoltaic power generation control device, wherein the control is performed by the control method according to claim 1.