JP2000341875A - Solar generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-layered battery type solar generator, in which batteries are arranged in parallel and charge/discharge control can be conducted easily in order to maintain the required value of the residual capacity of the batteries, even if power supplies other than a solar cell are discontinued due to an accident, failure, etc. SOLUTION: In a solar generator E1, 1st and 2nd batteries B1 and B2 which are connected in parallel to each other are charged by a solar cell power supply P, an auxiliary power supply A which are connected in parallel to each other, and a power is supplied to a load L by the power supplies and the batteries. The solar cell power supply P is connected to a 1st battery B via a 1st switch S1. A 2nd battery B2 is connected to the connection point between the solar cell power supply P and the 1st switch S1 via a 2nd switch S2. The auxiliary power supply A is connected to the 2nd battery B2 via a 3rd switch S3. The switching control of the 1st-3rd switches are conducted according to the charged state of the 1st battery B1 to select the power supplies and batteries which supply a power to the load L.

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 system in which a plurality of storage batteries connected in parallel are charged using a solar cell connected in parallel and an auxiliary power supply for stabilizing the power supply of the solar cell. Related to the device.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, the output of a solar cell P fluctuates almost in proportion to the insolation intensity, and no power is generated from the solar cell P at night (the output becomes zero).
It is common practice to connect storage batteries B in parallel and supply power to a load L for the purpose of stabilizing power supply.

Further, in order to avoid that the sunshine day continues more than expected due to abnormal weather and the like and the storage battery B becomes overdischarged, a backup auxiliary power supply (for example, a commercial power supply or a diesel generator) is connected to the solar battery P. And a method of charging the storage battery B using these power sources in some cases.

For example, as shown in FIG. 4, a solar cell P and a commercial power supply A are connected in parallel, the solar cell P is connected to a storage battery B via a diode D, and the commercial power supply A is connected to a switch SW and AC / DC. In some cases, the battery B is connected to the storage battery B via the converter AD, and the storage battery B is charged with these power sources to supply power to the load L. In such an apparatus, even when the storage battery B is in an overdischarged state when the amount of charge by the solar cell P is insufficient or the power consumption exceeds the design value of the load L, the switch SW is closed and the commercial power supply A Charging can be performed. This increases the stability of the power supply,
The storage battery B also requires a small capacity.

[0005]

In supplementary charging using a commercial power supply, the remaining capacity of the storage battery is detected, and when the remaining capacity falls below a certain level, supplementary charging is started. If it is, the auxiliary charging is terminated. Here, the detection of the remaining capacity of the storage battery is performed by measuring the terminal voltage of the storage battery, the specific gravity of the electrolyte, the balance of the charge / discharge amp hour, and the like.

However, the measurement of the remaining capacity by any of the sensing methods is insufficient for monitoring the state of the storage battery. The reason will be described with reference to FIGS. FIG. 5 shows the relationship between the discharge time (discharge amount) of the storage battery and the terminal voltage, and the change in the specific gravity of the electrolyte of the storage battery.
Is the relationship between the battery charging time (charging time) and the terminal voltage,
And changes in the specific gravity of the electrolyte. In FIG. 5, a period indicates a sharp drop immediately after the start of discharge of the terminal voltage, a period indicates a gentle voltage drop, and a period indicates a voltage sudden drop at the end of discharge. In FIG. 6, the period indicates a sharp rise immediately after the start of charging of the terminal voltage, the period indicates a gradual rise in voltage, the period indicates a sharp rise in voltage, and the period indicates the end of charging (constant voltage).

[0007] In each case, the terminal voltage largely changes at the end of charge and discharge, but the change in the intermediate portion (period) is small. In the case of a power supply consisting only of a solar cell and a storage battery, in many cases, charge / discharge control captures this terminal voltage and performs control of disconnecting the solar cell if overcharged and disconnecting the load if overdischarged.

However, when the remaining capacity is 30% or 50%,
It is difficult to discriminate the case by the terminal voltage. When applied to a device that is backed up by a commercial power supply, for example, even if auxiliary charging is started after reaching the terminal voltage, there is no guarantee that power can be supplied to the load with the remaining capacity of the storage battery if the commercial power supply fails at that time. . In order to secure a predetermined remaining capacity of the storage battery in advance and to guarantee the operation of the load for a certain period during a long-term commercial power outage, it is necessary to accurately detect an intermediate value of the storage battery remaining capacity. Although the specific gravity of the electrolyte of the storage battery has a linear relationship with the remaining capacity in a wide range, the specific gravity varies greatly depending on the location in the battery case, and the accuracy of the amp-hour balance is also poor because the charging / discharging efficiency changes during the lifetime.

Accordingly, the present invention provides a multi-tiered storage battery capable of easily performing charge / discharge control of the storage battery even if the power supply other than the solar battery is stopped due to an accident or a failure in order to stabilize the power supply of the solar battery. It is an object of the present invention to provide a photovoltaic power generator of a type.

[0010]

In order to achieve the above object, a photovoltaic power generator according to the present invention comprises first and second parallel-connected solar cell power supplies and an auxiliary power supply.
A solar power generation apparatus configured to charge a storage battery of the present invention and to supply power to the load from the power supply and the storage battery, the first storage battery being connected to the solar battery power supply via a first switch, A second storage battery is connected between the power supply and the first switch via a second switch, and a second storage battery is connected to an auxiliary power supply via a third switch, so that the first storage battery is charged. Open / close control of the first to third switches is performed in accordance with the state, and a power supply for supplying power to a load and a storage battery are selected.

In the above photovoltaic power generator, in particular, when only the second switch is opened during normal times, power is supplied to the load by the solar cell power supply and the first storage battery, and the first storage battery is over-discharged. Closes the first to third switches, supplies power to the load with the solar cell power supply, the auxiliary power supply, and the second storage battery. If the first storage battery is overcharged,
Only the second switch is closed, and power is supplied to the load by the first storage battery.

In addition, a DC power supply comprising a solar cell power supply and an auxiliary power supply connected in parallel charges two storage batteries connected in parallel, and supplies power from the DC power supply and the storage battery to a load. A power generator, wherein the storage battery comprises a normal storage battery and an emergency storage battery, and usually supplies power to the load from the DC power supply and the normal storage battery, and when the DC power supply is stopped, the emergency storage battery. To supply power to the load.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the photovoltaic power generator according to the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, a photovoltaic power generator E1 has a solar cell P serving as a solar cell power supply and a commercial power supply A serving as an auxiliary power supply connected in parallel, and a solar cell and a storage battery serving as a first storage battery. B1 is the backflow prevention diode D and the first
Is connected via a switch S1 which is a second switch, and between the diode D and the switch S1 and a storage battery B2 which is a second storage battery is a switch S2 which is a second switch.
2 and the commercial power supply A and the storage battery B2 are connected to the third
Is connected to the switch S3 via the AC / DC converter AD.

Next, the operation of the photovoltaic power generator E1 will be described.

Normally, the switch S1 is closed, the switch SW2 is open, and the switch S3 is closed, and the solar cell P
Operates as a general stand-alone photovoltaic power generator. That is, power is supplied from the storage battery B1 and the solar cell P to operate the load L. When the switch S3 is closed, the floating charge of the storage battery B2 is performed, and the self-discharge of the storage battery B2 is supplemented.

When the storage battery B1 has reached the end of overdischarge as shown in FIG. 5, the switch S2 is closed from the above-mentioned switch state, all switches are closed, and the charging of the storage battery B1 and the load L are performed. Is supplied by the storage battery B2, the solar battery P, and the commercial power supply A.

At this time, if the commercial power supply A loses power, the storage batteries B1 and B2 are discharged, and power is supplied to the load L by the solar battery P while the switches are kept as they are.

When the storage battery B1 has reached the end of overcharging as shown in FIG. 6, the switch S1 is opened, the switch S2 is closed, the switch S3 is opened, and the solar cell P is switched to the commercial power supply A.
Instead of charging the storage battery B2, the solar cell P is effectively used, and the load L is operated only by the storage battery B1. Table 1 summarizes the above operations. In Table 1, 1 indicates that the switch is closed, and 0 indicates that the switch is open.

[0020]

[Table 1]

When a diesel generator is used as the auxiliary power source instead of the commercial power source A, the switch S3 is normally opened, and the auxiliary charging of the storage battery B2 is performed periodically. Battery B
In No. 1, the number of charge / discharge cycles is larger than that of the storage battery B2, so that the life is shortened. For this reason, it is also possible to perform control to periodically replace the storage battery B2.

The sizing of the storage battery B1 and the solar cell P is as follows.
This is the same as the design of a stand-alone solar photovoltaic power generation system that uses only a solar cell as a power source to charge a normal storage battery. Theoretically, the daily generated power of the solar cell P and the daily power consumption of the load Although the amounts are balanced, when the capacity of the solar cell is reduced, the probability of overcharging of the storage battery B1 is reduced, and the utilization rate of the solar cell P is improved. Conversely, the amount of auxiliary charging by the commercial power supply A increases. An apparatus characterized by increasing the utilization rate of the solar cell P in this way is also possible. In addition, when the capacity of the solar cell P is increased, the probability of supplementary charging of the storage battery B2 increases, and the amount of use of the commercial power supply A may be reduced. In any case, a device that does not affect the driving of the load L can be provided.

Further, in the ordinary solar cell independent power supply, an overdischarge prevention circuit is provided to protect the storage battery and the load is cut off. However, according to the photovoltaic power generator, the overdischarge prevention circuit is not required, so that it is simple. Control with the configuration becomes possible.

In order to accurately detect the remaining capacity of the storage batteries, the storage batteries may be configured in parallel. A device that supplies power to a load by an unstable power supply such as a solar cell connected in parallel with a storage battery, and when it is desired to operate the load for a predetermined period even when the power supply fails, the parallel connection If the banks used for normal charging and discharging are separated from the banks used for emergency discharging, the terminal voltage of the battery in the charging and discharging state can be easily sensed, so that the emergency power supply period is guaranteed. It will be easier. FIG. 2 shows a solar power generation device E2 having such a storage battery parallel bank power supply.

In FIG. 2, G is a DC power supply in which a plurality of types of power supplies (solar cell + auxiliary power supply) including a solar cell power supply are connected in parallel.
To connect the storage battery B1 for normal use and the storage battery B2 for emergency connected in parallel between the backflow prevention diode D and the load L, and the storage battery B2 is connected to the power supply G via the switch S4. This is connected to the load L.

In FIG. 2, a switch S4 is connected to a storage battery B2.
Is closed when the self-discharge amount is compensated and when the power supply G stops due to a failure. Power supply G and storage battery B1 during normal times
A stable power source is obtained by parallel operation. For example, when the consumption of the load L is 100 Ah per day, and the load is to be operated for two days even when the power supply is stopped, the storage battery capacity for normal charging and discharging is 100 Ah, and the emergency storage battery is 200 Ah.
h, in the case of a system that guarantees the operation of the load for two days, the remaining capacity is 200 Ah using a storage battery of 300 Ah.
This can be performed more easily than detecting the points.

In the above embodiment, the type of power supply connected in parallel and the number of storage batteries connected in parallel are two, respectively. However, the number, type, and the like are not limited to this embodiment. The present invention can be appropriately changed and implemented without departing from the spirit of the invention.

[0028]

As described above, according to the photovoltaic power generator of the present invention, a predetermined amount of the remaining capacity of the storage battery can be ensured even when the power supply other than the solar cell is stopped due to an accident or failure. It is possible to supply stable power to the load without always separating the load from the power supply.

Further, since it is not necessary to determine the capacity of the storage battery based on continuous non-sunlight compensation, the storage battery can be made as small as possible. Furthermore, since the storage battery is not over-discharged, an over-discharge prevention circuit is not required, and charge / discharge control of the storage battery is facilitated.

Thus, an excellent solar power generation device having a simple configuration and high reliability can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic circuit configuration diagram for schematically explaining a solar power generation device according to the present invention.

FIG. 2 is a schematic circuit configuration diagram schematically illustrating another solar power generation device according to the present invention.

FIG. 3 is a schematic circuit configuration diagram for schematically explaining a conventional solar power generation device.

FIG. 4 is a schematic circuit configuration diagram for schematically explaining a conventional solar power generation device.

FIG. 5 is a diagram showing a relationship between a discharge time (discharge amount) of a storage battery and a terminal voltage.

FIG. 6 is a diagram showing a relationship between a charging time (charging time) of a storage battery and a terminal voltage.

[Explanation of symbols]

 A: Commercial power supply (auxiliary power supply) B1: (First) storage battery B2: (Second) storage battery D: Backflow prevention diode E1, E2: Photovoltaic power generator G: Power supply L: Load P: Solar cells S1, S2 , S3, S4: Switch

Claims (3)

[Claims] 1. A photovoltaic power generator configured to charge first and second storage batteries connected in parallel by a solar cell power supply and an auxiliary power supply connected in parallel, and to supply power to a load from the power supply and the storage batteries. An apparatus, wherein the first storage battery is connected to the solar battery power supply via a first switch,
The second storage battery is connected between the solar battery power supply and the first switch via a second switch, and the second storage battery is connected to the auxiliary power supply via a third switch. A power source for supplying power to the load and a storage battery, wherein opening and closing control of the first to third switches is performed according to a state of charge of the first storage battery. Power generator. 2. In a normal state, only the second switch is opened, power is supplied to the load by the solar cell power supply and the first storage battery, and when the first storage battery is in an over-discharged state, Closing the first to third switches, supplying power to the load by the solar cell power supply, the auxiliary power supply, and the second storage battery, and when the first storage battery is in an overcharged state, The photovoltaic power generator according to claim 1, wherein only the second switch is closed, and the first storage battery supplies power to the load. 3. A DC power supply comprising a solar cell power supply and an auxiliary power supply connected in parallel to charge two storage batteries connected in parallel, and to supply power from the DC power supply and the storage battery to a load. A photovoltaic power generator, wherein the storage battery comprises a normal storage battery and an emergency storage battery, and usually supplies power to the load from the DC power supply and the normal storage battery, and when the DC power supply is stopped. Is a photovoltaic power generator, wherein the emergency storage battery supplies power to the load.