JP4355687B2 - Operation method of solar system - Google Patents

Description

  The present invention relates to a method for operating a solar system, for example, a solar independent power supply base station, and a driving apparatus therefor.

  As is well known, a solar cell, a converter electrically connected to the solar cell, a load electrically connected to the converter, a storage battery electrically connected to the converter, and the storage battery A solar system is known that includes an external power generation device that is electrically connected to the power source.

  In such a solar system, when determining the storage battery specifications of the solar independent power supply base, conventionally, comparing the safety factor to the extent that the system failure does not occur due to the occurrence of non-sunshine from the average load current from the past days The storage battery capacity that was largely estimated was determined.

  However, in this case, since the design is made so as to cover all the non-sunshine periods of the past sunshine data, the maximum specification is reached, and a battery having an excessive capacity is installed. Also, if the sun continues beyond the design expectations, the system will go down.

  Therefore, regardless of the state of the storage battery, the administrator periodically went to the site to manually operate the power generator installed regularly to perform supplementary charging / charging of the storage battery.

When determining the storage battery specifications of the solar independent power supply base, the storage battery capacity with a relatively large estimated safety factor that does not cause system down due to the occurrence of non-sunshine from the past data and the average load current is calculated. decide. In this case, there is a risk that the maximum specification will be reached because the design covers all the unlit periods of past data.

  In addition, a battery having an excessive capacity has been installed in order to cause the system to be down when the non-sunshine daylight exceeding the expectation at the time of design continues. For this reason, regardless of the state of the storage battery, the administrator regularly went to the site, manually operating the power generator installed regularly, and performing supplementary charging / charging of the storage battery.

  Patent Document 1 describes a point similar to the solar system of the present invention, that is, a point that always monitors the state of charge of the storage battery, but this changes the driving method of the load according to the state of the storage battery. There is clearly a difference from the case where the storage battery is automatically charged by the external power generator as in the present invention.

Patent Document 2 describes the point of accurately grasping the state of performance deterioration of a storage battery by effectively using the fact that the open voltage of the storage battery at full charge has a close correlation with the capacity. There is no description about the point that the storage battery is automatically charged by the external power generator as in the invention.
JP-A-9-35757 JP-A-8-228441

  Excessive design of storage battery capacity to cover all the periods of non-sunshine in past data.

Charging work when the administrator goes to the site. Prevents system downtime during non-sunshine periods beyond specifications.
The present invention has been made in consideration of such circumstances, and avoids excessive design of the storage battery capacity to cover all the non-sunshine periods of the past sunshine data, and the administrator visits the site to perform charging work. It is an object of the present invention to provide a solar system operating method and an operating device thereof capable of avoiding the above-mentioned problem and further avoiding the system down in the non-sunshine period exceeding the specification.

In order to achieve the object, an invention corresponding to claim 1 includes a solar cell, a power converter electrically connected to the solar cell, a load electrically connected to the power converter, In a method for operating a solar system including a storage battery electrically connected to a power converter and an external power generation device electrically connected to the storage battery,
The remaining capacity of the storage battery when the storage battery voltage reaches the charge setting voltage and the charging current of the storage battery enters a state of continuously decreasing is used as a storage battery remaining capacity reference obtained based on the rated capacity, and the storage battery The external power generation device is calculated when the storage battery estimated operational days are obtained from the remaining capacity reference, the current integrated value obtained from the input / output current flowing through the storage battery and the time, and when the obtained storage battery estimated operational days reach a predetermined reference number of days. The operation method of the solar system, wherein the storage battery is charged by the above.

To achieve the aforementioned object, the present invention corresponding to claim 2, the battery estimated workable days D of claim 1, wherein a (3) Characteristics and to Luso over error system operation method of the determination of the expression.
D = (C80 _% −ΣkVT− _CX% ) / 24I (3) where C80 _% is based on the remaining battery capacity, 80% of the rated capacity of the battery, k is a conversion coefficient, V Is the storage battery measurement sampling voltage (voltage measured by converting the input / output current of the storage battery), T is the voltage measurement sampling time of the storage battery, C _X% is the minimum storage battery capacity to be kept, and I flows to the load Average load current.

D = (C _80% −ΣkVT−C _X% ) / 24I (4)

  According to this invention, even if the battery capacity decreases, the capacity can be recovered automatically by charging with the power generation device, so there is no need for excessive design of the storage battery capacity to cover all the non-sunshine periods of past data, System down due to battery voltage drop can be avoided. In addition, there is no charge work for the manager to go to the site. Furthermore, long-term unmanned operation is possible.

  Embodiments of the present invention will be described below with reference to the drawings.

First, the solar system SS and the driving device DR according to the present invention will be described with reference to FIG.
Reference numeral 1 in the figure indicates, for example, a solar cell (PV: Photovoltaic) installed on the roof of a building. The solar cell 1 is electrically connected to a load 3 such as a transmission / reception device or an electric lamp via a power converter such as a DC / DC converter 2 for boosting the output voltage to a constant voltage, for example. The converter 2 is connected to a storage battery 4 that charges power from the solar battery 1 and supplies power to the load 3. Furthermore, an external power generation device 8 is electrically connected to the storage battery 4 and is configured to be rechargeable when the capacity of the storage battery 4 is reduced by the external power generation device 8. The configuration described above is the solar system SS.

  The driving device DR includes a measurement unit 5 that constitutes a measurement unit, a processing unit 6 that constitutes a calculation unit, and a determination unit 7 that constitutes a determination unit.

The measuring unit 5 measures the voltage of the storage battery 4 and the input / output current of the storage battery . The processing unit 6 has an 80% storage battery capacity C _80% of the rated capacity value of the storage battery 4, a conversion coefficient k, a storage battery measurement sampling voltage (voltage measured by converting the input / output current of the storage battery), and the storage battery When the voltage measurement sampling time of 4 is T, the minimum storage battery capacity to be left is C _X% , and the average load current flowing through the load 3 is I, the storage battery estimated operational days D are obtained by the equation ( 5).
When the measured voltage reaches the charge setting voltage and the state in which the charging current of the storage battery is in a continuous downward trend is measured, the part “C _80% −ΣkVT” for calculating the remaining capacity of the storage battery in equation (5) ΣkVT (integrated current value) is reset to zero.

D = (C _80% −ΣkVT−C _X% ) / 24I (5) Formula The determination unit 7 charges the storage battery 4 by the external power generation device 8 based on the estimated number D of operational days for the storage battery obtained by the processing unit 6. Judge whether to do.

  In such a system, the electric power from the solar cell 1 is supplied to the load 3 via the power converter 2 or the storage battery 4 is charged during sunshine. On the other hand, electric power is supplied from the storage battery 4 to the load 3 during non-sunshine hours or at night, and thus the output voltage of the storage battery decreases. Therefore, the measurement unit 5 always measures the voltage of the storage battery 4, and the processing unit 6 obtains the estimated number D of operational days for the storage battery. Then, the determination unit 7 determines whether or not to operate the external power generator 8 by comparing with a preset set value. When it is determined that the vehicle is in operation, the external power generator 8 is operated to supply power to the storage battery 4 to make up for the shortage of the storage battery 4.

  In addition, the solar system SS mentioned above shows an example, The structure is not limited to the thing of FIG. The electric power at the time of starting the external power generation device 8 described above is supplied by, for example, the storage battery 4.

  Usually, the room temperature (indoor temperature) in the solar independent power supply base station is relatively stable compared to the outside air temperature (outdoor temperature). This is because the thermal insulation of the building of the solar independent power base station is high and it is adjusted by an indoor temperature adjustment device (air conditioner), so it is less susceptible to changes in the outside air temperature.

  For example, FIG. 2 shows the temperature change between the room temperature and the outside air temperature from November 2003 to June 2004, for example. The upper waveform in FIG. 2 shows the room temperature, and the lower waveform in FIG. 2 shows the outside air temperature. From these two waveforms, since the room temperature is relatively stable, it is considered that the influence of temperature is negligible when performing the following data analysis.

The storage battery 4 is charged by the power generated by the solar battery 1. In addition, the capacity of the solar cell 1 is selected in consideration of the amount of charge to the storage battery 4 after non-sunshine, and the capacity of the solar battery 1 having a sufficient margin for power generation relative to the amount of nighttime discharge from the storage battery 4 is selected. . For this reason, in the time when there is a lot of sunny days, charging of the storage battery 4 starts with sunrise, and then several hours pass, reaches the set charging voltage value, and starts drooping of the charging current. It can be seen from the charging characteristics of the storage battery 4 that the capacity of the storage battery 4 is, for example, about 80% or more at this time. In addition, the capacity | capacitance of the storage battery 4 shall be about 80% or more here, for the industrial storage battery used normally, since drooping will occur when the capacity | capacitance of the storage battery 4 becomes about 80% or more, depending on the case It is also conceivable that the capacity of the storage battery 4 has a certain width with respect to 80%.

As described above, the voltage / current value of the storage battery 4 is measured. When the voltage of the storage battery 4 reaches the set charging voltage and the charging current of the storage battery 4 drops, the capacity of the storage battery 4 at that time is 80% of the rated capacity ratio. Assuming%, the capacity of the storage battery 4 is estimated thereafter, and a decrease in the storage battery capacity due to non-sunshine is expected.

  The above will be described with reference to the flowchart of FIG.

1) First, a method for measuring the current of the storage battery 4 and a method for calculating the integrated current value will be described.

In the measurement unit 5 output current of the battery 4, for example current transformers CT or shunt using (shunt resistor) and the like, the measurement so as to identify at the same time the current direction is performed to measure the battery current I _B as a voltage data (S1). Moreover also performs measurement of the battery voltage _{V B} (S1).

For example, the current direction is identified by a sign, and the input current to the storage battery 4 is − and the output current is +. If the measurement voltage value (sampling voltage) at this time is V1, V2, V3... And the measurement sampling time is T [h], the conversion coefficient from the measurement voltage value to the current value is k.
The integrated current value is
(V1 + V2 + V3 +...) × k × T [Ah] (6)

By executing the calculation for each sign of the measured voltage value V, the discharge amount from the storage battery 4 and the charge amount to the storage battery can be calculated. In the equation (6), the voltage value is converted into the current value because it is difficult to directly measure the current value, and therefore a current transformer CT or a current shunt is used.

  An example of daily current integrated value (capacity) transition of the solar independent power supply base station is shown in FIG.

FIG. 4 shows a case where FIG. 3 is converted to the capacity rating ratio of the storage battery 4.

2) The estimation of the capacity of the storage battery 4 will be described. In FIG. 4, the storage battery rated capacity ratio after charging is 80%.
At the above time, the storage battery 4 reaches the charging voltage and the drooping characteristic of the charging current can be confirmed (S2). In the solar independent power base station, the load 3 is mainly a communication device, the power consumption is almost constant, and it is small compared to the capacity of the installed storage battery 4, so that the storage battery 4 is considered to be a constant current discharge. To do. When the load current is I ₁ and the amount of load current per day is calculated,
ΣI ₁ × 24 = 24I ₁ [Ah] (7)

Here, the reset timing of the remaining battery capacity is determined, for example, from 12:00 to 16:00. Voltage of the battery 4 when measuring the voltage and current of the storage battery during this time (battery voltage) V _B has reached the charging setting voltage (reference voltage) V _0, there charging current of the battery 4 is in a continuous downward trend It was . A continuous downward trend is a case where, for example, data is acquired every 5 minutes, and the charging current decreases continuously (I _n-1 > I _n > I _{n + 1} ) for three or more points. (In this embodiment, since the current obtained by the converter or the shunt is measured as voltage data, V _n−1 > V _n > V _{n + 1} is satisfied.)
When this condition is satisfied, the remaining capacity of the storage battery is assumed to have a capacity of 80% of the rated capacity of the storage battery, and is set to “storage battery capacity 80%”. At this time, “storage battery capacity 80%” is used as a reference for the remaining battery capacity, and C _80% is set, and the accumulated current value is reset as the remaining capacity of the storage battery . The voltage does not increase if the weather is poor charging current has decreased to a charging set voltage (reference voltage) V _0.

The residual capacity C _{remaining capacity} of the storage battery is at the reset timing
C _{remaining capacity} = C _80% [Ah]. At this time, the accumulated current value of the storage battery is reset (S3).
Thereafter, when the storage battery 4 is being discharged or charged, the voltage V _{B of the} storage battery 4 does not reach the charge setting voltage V ₀ , and even if it reaches V ₀ , the charging current tends to continuously decrease (V _n-1 > V _n > V _{n + 1} ), the remaining capacity of the storage battery is calculated by subtracting the accumulated current value expressed by the equation (6) from the storage battery remaining capacity reference C _80% ,
C _{remaining capacity} = C _80% − (V1 + V2 + V3 +...) × k × T [Ah] (8)
At this time, as described above, the voltages (V1, V2,...) Are assumed to be − for charge of the storage battery, that is, input current, and + for discharge, that is, output current.
Then, the estimated operational days D up to the storage battery capacity C _x% is calculated from the equations (7) and (8) as D = [C _{remaining capacity−} C _x% ] ÷ 24I ₁
= [C _80% -(V1 + V2 + V3 +...) × k × T−C _x% ] ÷ 24I ₁ (9) (S4).

In the equation (8), the meaning of C _80% means that, for example, when a 50 Ah storage battery is used, 50 Ah × 80% = 40 Ah. Further, in the equation (9), C _x% indicates how much the lower limit value of the storage battery capacity is, and if the storage battery 4 is completely discharged (C _x% is 0%), the life of the storage battery 4 is reached. Therefore, C _x% is normally set to about 30%.

The calculation result is, for example, if the estimated workable number of days is less than 2 days (S5) gives a start command to the external power generator 8 (S6), the external charging of the battery 4 is This ensures This is done automatically, and as a result, system down can be prevented automatically. The external power generator is automatically stopped when the storage battery is fully charged. The fuel supply to the external power generation device 8 is performed, for example, every two months or by notifying the number of activations of the external power generation device 8 by wireless communication.

The block diagram for demonstrating the operating method of the solar system by this invention, and its operating device. The figure which shows an example of the data of the room temperature in the solar independent power supply base station of FIG. 1, and external temperature. The figure which shows an example of daily electric current integrated value (capacity | capacitance) transition of the solar independent power supply base station of FIG. The figure which shows the example which comparatively converted the rating of the capacity | capacitance of the storage battery of FIG. The flowchart for demonstrating the function of the operating device of FIG.

Explanation of symbols

  SS ... Solar system, DR ... Driving device, 1 ... Solar cell, 2 ... Power converter, for example, DC / DC converter, 3 ... Load, 4 ... Storage battery, 5 ... Measuring part, 6 ... Processing part, 7 ... Judgment part, 8 ... external power generator.

Claims (2)

A solar battery, a power converter electrically connected to the solar battery, a load electrically connected to the power converter, a storage battery electrically connected to the power converter, and the storage battery In a method for operating a solar system including an external power generator connected electrically,
The remaining capacity of the storage battery when the storage battery voltage reaches the charge setting voltage and the charging current of the storage battery enters a state of continuously decreasing is used as a storage battery remaining capacity reference obtained based on the rated capacity, and the storage battery When the estimated remaining number of days for the storage battery is determined based on the remaining capacity reference , the input / output current flowing through the storage battery, and the current integrated value obtained from the time, The method of operating a solar system, wherein the storage battery is charged by The method for operating a solar system according to claim 1, wherein the estimated number of days D of estimated storage battery operation is obtained by equation (1).
D = (C80 _% −ΣkVT− _CX% ) / 24I (1) Formula where C80 _% is a storage battery remaining capacity standard, 80% storage battery capacity of the rated capacity value of the storage battery, k is a conversion coefficient, V Is the storage battery measurement sampling voltage (voltage measured by converting the input / output current of the storage battery), T is the voltage measurement sampling time of the storage battery, C _X% is the minimum storage battery capacity to be kept, and I flows to the load Average load current.

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