JPH1146458A - Solar power generating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always secure a predetermined quantity of charging with a high conversion efficiency of an inverter, by controlling the discharge of a battery unit in such a manner that the input power from a solar battery module or battery unit to the inverter always exceeds a predetermined value during inverter operation. SOLUTION: A solar battery module 1 is connected to a discharge controller 4 through a connection box 6, an inverter 3 and a battery unit 2 are connected to the discharge controller 4, and the inverter 3 is connected to a power distribution panel 7. A commercial system line 8, a load 9 and a charging controller 5 are connected to the power distribution panel 7, and this charging controller 5 is connected to a battery device 2. The discharging controller 4 starts the discharge from the battery device 2 at the same time with the start of generation of the solar cell module 1. The battery device 2 is controlled in such a manner that the discharge is continued at a constant output until the time set depending on the place and season. Thus, the shortage of charging power of the battery device can be solved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photovoltaic power generation system linked to an external power source such as a commercial power system.

[0002]

2. Description of the Related Art A residential photovoltaic power generation system linked to a commercial power system is inexpensive without requiring a large-scale power storage device unlike an independent type photovoltaic power generation system, and is affected by output fluctuations inherent to a photovoltaic module. Since it is possible to obtain stable electric power without receiving it, and it is possible to sell surplus electric power and it has an economic advantage, it has recently become popular as a mainstream solar power generation system for houses. This photovoltaic power generation system includes a solar cell module, a junction box, an inverter, and a distribution board. The solar cell module and the inverter are connected via a junction box, and the commercial power system is connected to a distribution line in a house. This inverter is connected to the distribution board that has been connected, and when the amount of power generated by the solar cell module exceeds a predetermined output, the inverter starts up, and this inverter converts DC power to AC power and supplies it to the distribution board The operation is performed such that a power flow and a reverse power flow are performed between the power generation system and the commercial power system in accordance with the magnitude relationship between the power generation amount and the power consumption in the house.

[0003]

FIG. 3 is a characteristic diagram showing the relationship between the conversion efficiency and the addition rate of the inverter shown below. As shown in this figure, the conversion efficiency of an inverter generally used in a photovoltaic power generation system rapidly decreases as the addition rate decreases. For this reason, when the amount of power generated by the solar cell module is small, the amount of power actually supplied to the distribution board and used is very small compared to the amount of generated power, causing a reduction in the conversion efficiency of the entire photovoltaic power generation system. It has become one of.

[0004] One of the methods to solve this problem is to supplement the power from an auxiliary power supply such as a power storage device or a commercial power system to increase the input power when the power generation amount of the solar cell module is small. There are ways to increase efficiency. In addition, when a power storage device such as a secondary battery is incorporated in the photovoltaic power generation system, if the power generation output of the solar cell module is smaller than a predetermined value at which the efficiency of the inverter is improved, all of the power is charged to the power storage device and the inverter stops. Then, there is a method of operating the inverter when the power output of the solar cell module exceeds the predetermined value. With such a system configuration, even when the power output of the solar cell module is small, the power is temporarily stored in the power storage device, and the stored power is collectively output to the inverter later to efficiently use the generated power. It becomes possible. Furthermore, when the power generated by the solar cell module fluctuates greatly, the inverter repeatedly starts and stops, and the standby time for this may further reduce the overall efficiency. By incorporating this to compensate for the temporary decrease in the output of the solar cell module and maintain the above-mentioned predetermined value, frequent start and stop can be prevented, and the efficiency of the system can be increased. It becomes possible.

Further, by incorporating the power storage device as described above, it becomes possible to efficiently reduce the power generation facilities of the commercial power system. FIG. 6 is a diagram showing an example of the power consumption of a day in summer and the amount of power generated by the conventional photovoltaic power generation system in a sunny day. As shown in this figure, since both power consumption and power generation increase during the day, peak power consumption during the daytime, especially in the summertime, can be reduced by increasing the number of systems, thereby reducing the amount of power generation equipment. However, since the peak of the power consumption and the peak of the power generation amount are slightly shifted with respect to time, the efficiency of power generation equipment reduction is lower than in the case where the peak positions are the same. Further, since the power generation amount of the solar cell module is unstable, the power consumption and the power generation amount may fluctuate completely differently, and in this case, the effect of reducing the power generation equipment cannot be expected. However, if the power storage device is incorporated as described above, the power generated by the solar cell module is temporarily stored in the power storage device, and the power is discharged in accordance with the peak power consumption, thereby increasing the efficiency of power generation equipment reduction. Can be done.

Furthermore, for the purpose of high efficiency operation of the inverter and shortening of the operation time of the inverter, the power generated by the solar cell module is always charged to the power storage device, and the amount of power stored in the power storage device is equal to or more than a predetermined value. A method of starting to supply power having a certain output or more to the inverter via the power storage device when the power storage device becomes a power supply device, and stopping the power supply when the amount of power stored in the power storage device becomes a predetermined value or less, or a solar cell module. The power generated by the power storage device is always charged, the power supply to the inverter is performed at a certain output or higher through the power storage device, and the start and stop of the power supply to the inverter are controlled by time. In order to effectively link with the system power supply, the power generated by the solar cell module is always charged to the power storage device, and the power to the inverter and the system is Power supply is carried out via the power storage device at a constant output over, there is also a method in which the starting and stopping of the power supply to the system performed by remote control.

However, when a power storage device is used to guarantee the input power to the inverter, a sufficient amount of power must always be stored in the power storage device. In some cases, the amount of stored power may be insufficient, and when discharging according to the power consumption, the capacity of the power storage device may be reduced to prevent the power to be temporarily stored from being unable to be temporarily stored due to insufficient capacity. It needs to be large enough, which is problematic in terms of economy. In addition, irrespective of the control method, the provision of the power storage device increases the cost of the entire photovoltaic power generation system and the amount of energy used for constructing the system, and causes economical and environmental problems. An object of the present invention is to solve the above-mentioned problems that occur when using a power storage device, and to provide an efficient and economical solar power generation system.

[0008]

A solar power generation system according to the present invention comprises a solar cell module, a power storage device, a discharge control device for controlling discharge of the power storage device, and a charge control device for controlling charging of the power storage device from an external power supply. And an inverter to which power from a solar cell module or a power storage device is input and supplies power to an external power supply or a load, wherein the solar cell module is configured such that the generated power is input to the inverter. The power storage device is connected to the inverter via the discharge control device so that its output power is input to the inverter, and connected to the external power supply via the charge control device, When the discharge control device operates the inverter, the discharge control device inputs power from the solar cell module or the power storage device to the inverter. And controlling the discharge of the storage device so that power is always greater than or equal to a predetermined value.
In the photovoltaic power generation system of the present invention, since the inverter always operates under the input power equal to or higher than the predetermined value, the high conversion efficiency of the inverter is maintained, and the charging of the power storage device is performed.
The charging is performed from the external power supply by the charging control device so as not to be affected by the output of the solar cell module. Therefore, the charging amount as planned in advance can be always secured, and shortage of charging power can be prevented. Note that the predetermined value of the input power to the inverter may be appropriately set so that the required efficiency is maintained in accordance with the performance of the inverter.

[0009] Further, when the charging control device is operated at night to charge the power storage device at night, it is possible to effectively use nighttime electric power, and to improve the economical efficiency accompanying the increase in the capacity of the power storage device. The decrease can be compensated for by effective use of nighttime power, which is preferable.

[0010] In addition, the solar power generation system of the present invention includes:
When a remote control device that performs the discharge operation control of the discharge control device or the charge operation control of the charge control device by a control signal by remote control is provided, the power supply from the photovoltaic power generation system to the external power supply is performed as needed. This is preferable because the power can be controlled systematically from the place where the power control of the commercial power system is performed, and is particularly effective when the capacity of the power storage device is large.

[0011]

Next, the present invention will be described in more detail with reference to embodiments. FIG. 1 is a block diagram of a solar power generation system according to a first embodiment of the present invention.
As shown in FIG. 1, the solar power generation system includes a solar cell module 1, a power storage device 2, a discharge control device 4 for controlling discharge of the power storage device 2, and a power storage device from a commercial system line 8 as an external power supply. Charge control device 5 for controlling charging to 2
And an inverter 3 that receives power from the solar cell module 1 or the power storage device 2 and supplies power to the commercial system line 8 or the load 9. The solar cell module 1 performs discharge control via a connection box 6. The inverter 3 and the power storage device 2 are connected to the discharge control device 4, the inverter 3 is connected to the switchboard 7, and the commercial system line 8, the load 9, and the charge control device 5 are connected to the switchboard 7. The charging control device 5 is connected to the power storage device 2. The solar cell module 1 has a maximum output operating voltage of 24
V, and has a maximum output of 3 kW. As the power storage device 2, a secondary battery, a flywheel, a superconducting power storage device, or the like can be used. The power storage device 2 used here is a nominal voltage of 12 V, a capacity of 200 Ah (10 HR), and a discharge depth of 60%.
It consists of two lead-acid batteries with a cycle life of 1200 cycles and connected in series.
And has a capacity of 4.8 kwh. The discharge control device 4 starts discharging the power storage device 2 at the same time as the start of power generation of the solar cell module 1 (assuming the time of 30 W output is started), and keeps a constant output until a time set in advance according to the place and season. The power storage device 2 is configured to control the power storage device 2 so as to continue discharging. The time from the discharge start time to the stop time is automatically calculated, and the power storage device 2 discharges 60% of its capacity by the stop time. The output current value is automatically determined so as to be completed. Also, even if the weather is bad and the power generation of the solar cell module is not performed, the constant current discharge at 20 Ah is automatically performed six hours before the stop time. By providing a timer function, the charging control device 5 starts constant-current charging of the power storage device 2 from the commercial grid line 8 at 23 o'clock, completes charging by 5:00 of the next day, and stops charging. Has become.
The inverter 3 has a rated input voltage of 24 V and a rated output voltage of 2
At 02 V and a rated output of 3 kW, the efficiency becomes maximum at an addition rate of 45% as shown in FIG. 3, and when the addition rate becomes small, the efficiency drops sharply. At a load rate of 8%, the conversion efficiency is 85%. Yes, it starts when there is an input of 24 V or more and 240 W or more, and stops when it falls below this.

FIG. 2 is an operation characteristic diagram showing an output operation of the photovoltaic power generation system, and shows a case where the solar cell module 1 is installed on the southern roof at an inclination of 25 degrees in Osaka.
This shows the operation status on a sunny day on July 1. In the figure, the hatched portion in the night portion indicates the charge output to the power storage device 2, the hatched portion in the day portion indicates the discharge output from the power storage device 2,
The solid line indicates the power output of the solar cell module 1, and the dotted line indicates the input output to the inverter 3. The setting of the discharge control device 4 on this day is such that the discharge is stopped at 18:00, and the power storage device 2 starts discharging at the same time as the solar cell module 1 starts power generation at 6:00.
Until the time, power of 240 W is always input from the power storage device 2, and the generated power from the solar cell module 1 is input so as to be superimposed thereon. During this time, the inverter 3 operates without stopping, and its conversion efficiency is always maintained at a value of at least 85% at the time of starting and at the time of stopping, at least. At 18:00, the power storage device 2 has a capacity of 60
%, The charging control device 5 is activated at 23:00 to start charging the power storage device 2, and the battery is fully charged again in 6 hours until 5 o'clock. In addition, in the case of this system, even if the solar cell module 1 stops power generation due to a change in weather once the power generation of the solar cell module 1 is started, the power supply is stopped.
Until the time, the output of 240 W is always input from the power storage device 2 to the inverter 3, so that the inverter 3 continues to operate without stopping during this period. Therefore, the start and stop operation of the inverter is only once a day at maximum. In addition, since the charge and discharge operation of the power storage device 2 is performed once a day at the maximum, repetition of charge and discharge can be reduced and the life of the battery can be fully used.

Next, another embodiment will be described. FIG.
FIG. 2 is a block diagram of a photovoltaic power generation system according to a second embodiment of the present invention. As shown in the figure, the solar power generation system includes a solar cell module 1 and a power storage device 2.
And a charge / discharge control device 4 for controlling the charge / discharge of the power storage device 2
A charging control device 5 that controls charging of the power storage device 2 from the commercial power line 8 that is an external power supply;
Alternatively, electric power from power storage device 2 is input and
Or, it comprises an inverter 3 for supplying power to the load 9, and a remote control device 10 for performing a discharge operation control of the charge / discharge control device 4 and a charge operation control of the charge control device 5 by a control signal by remote control. Battery module 1 is connected box 6
, The inverter 3 and the power storage device 2 are connected to the charge / discharge control device 4, the inverter 3 is connected to the switchboard 7, and the commercial power line 8 and the load 9 are connected to the switchboard 7. Then, the charging control device 5 is connected, the charging control device 5 is connected to the power storage device 2, the remote control device is connected to the power transmission control room, and the control signal line (dotted line) connected to the commercial system line 8 and led is connected. The control device 10 is a charge / discharge control device 4
And the charging control device 5. The solar cell module 1 has characteristics of a maximum output operation voltage of 48 V and a maximum output of 2.88 kW. The power storage device 2 has a nominal voltage of 12 V, a capacity of 200 Ah (10 HR), and a discharge depth of 60%.
Are connected in series with four lead-acid batteries having the characteristic of a cycle life of 1200 cycles, and three sets of these batteries are further connected in parallel.
It has a capacity of 8 kwh. The charge / discharge control device 4 operates to charge the power storage device 2 simultaneously with the start of power generation of the solar cell module 1, and stops charging when the power storage device 2 is fully charged. When the solar cell module 1 is generating power of 20 W or more when charging is stopped, the sum of the output of the solar cell module 1 and the discharge output of the power storage device 2 is 2.88 kWh.
The discharge current from power storage device 2 is controlled so that the integrated value of the discharge current is 60% (360%) of the rated capacity of power storage device 2.
Discharge is continued until Ah), and when the output of the solar cell module 1 exceeds 20 W after the end of the discharge, the operation is performed so that all of the output power is charged to the power storage device 2. If the output of the solar cell module 1 is lower than 20 W when the charging is stopped, the discharge from the power storage device 2 is prevented from being performed, and the discharge from the power storage device 2 is stopped when the output exceeds 20 W. , And the discharge is controlled in the same manner as described above. Also,
In addition to the above-described discharge start operation, when a discharge start signal is received from the remote control device 10, the control by this signal is prioritized, and the discharge control is started. As described above, the output of the solar cell module 1 and the power storage device 2 Is 2.8.
The discharge current from power storage device 2 is controlled to be 8 kwh, and the integrated value of the discharge current is 50% of the rated capacity of power storage device 2.
% (300 Ah). The charge control device 5 starts constant-current charging of the power storage device 2 from the commercial grid line 8 at 0:00 by providing a timer function,
By 5:00, 90% charging is performed and charging is stopped. When a charge start signal is received from the remote control device 10, control by this signal is given priority and constant-current charging of the power storage device 2 from the commercial power line 8 is started, and 90% charging is performed by 5:00. To stop charging. The inverter 3 has a rated input voltage of 48 V, a rated output voltage of 202 V, a rated output of 2.88 kW, and an addition rate of 10
At 0%, the efficiency becomes the maximum of 95%, 48V or more, 2.8
It starts when there is an input of kW or more, and stops when it falls below this.

FIG. 5 is an operation characteristic diagram showing an output operation of the photovoltaic power generation system. The photovoltaic power generation system is shown in Osaka when the solar cell module 1 is installed on the southern roof at an inclination of 25 degrees.
This shows the operation status on July 1. In the figure, the left shaded portion in the morning is the charge output to the power storage device 2, the right shaded portion after 9:00 is the discharge output from the power storage device 2, the solid line is the power output of the solar cell module 1, and the dotted line is 3 shows an input output to the inverter 3. The charging of the power storage device 2 starts at 0 o'clock, and 90% of the charging is performed at 5 o'clock.
Stops its charging operation. At 6:00, the sun starts to shine, and the solar cell module 1 starts power generation, and accordingly, the charge / discharge control device 4 operates to start charging the power storage device 2 from the solar cell module 1. The clear condition continues until 9 o'clock. At this point, the battery is fully charged, so the charging operation is stopped and the operation shifts to the discharging operation. Thereafter, the discharging operation is continued until 19:00. During this time, the discharge amount is adjusted in accordance with the output fluctuation of the solar cell module 1, and the inverter always supplies 2.8 at 48V.
8kw constant power is input, the highest efficiency is maintained,
Also, there is no stop on the way. In this case, although the control by the remote control device is not performed, for example, when the weather is bad and the power storage device 2 is not sufficiently charged and the discharge is not automatically started, a proper time (for example, power A signal is sent to the remote control 10 so that the discharge is started at 13:00 when the consumption starts to rise to the maximum value, so that the power supply from the photovoltaic power generation system is performed. Also,
In charging at night, the charging start time is controlled by the central control room if necessary according to the power consumption situation. In this example,
Since the capacity of the power storage device is relatively large, load leveling by storing nighttime power can be effectively performed.In addition, since the capacity of the power storage device is larger than that of the solar cell module, commercial It is easy to adjust the start time of the power supply to the power system, and it is possible to effectively reduce the power generation equipment in addition to the load leveling effect. Furthermore, by leaving a margin in the amount of charge of the power storage device at the time of night charging so that the power generated by the solar cell module can be charged, the power supply from the solar power generation system can be concentrated in time. It is possible, and it is effective in reducing noise by shortening the operation time of the inverter.

[0015]

According to the present invention, the inverter can be operated efficiently, and the shortage of charging power of the power storage device can be solved. In addition, load leveling of the commercial power system can be effectively leveled, and stable power with a constant output can be sent when reverse power flows to the grid, preventing disturbance in distribution power. This makes it possible to construct a solar power generation system that is efficient, inexpensive, and low in environmental load.

[Brief description of the drawings]

FIG. 1 is a block diagram of a photovoltaic power generation system according to a first embodiment.

FIG. 2 is an operation characteristic diagram illustrating an output operation according to the first embodiment.

FIG. 3 is a characteristic diagram showing a relationship between the conversion efficiency of an inverter and an addition rate.

FIG. 4 is a block diagram of a photovoltaic power generation system according to a second embodiment.

FIG. 5 is an operation characteristic diagram showing an output operation of the second embodiment.

FIG. 6 is a diagram showing an example of the power consumption of a day in summer and the amount of power generated by a conventional solar power generation system in a sunny day.

[Explanation of symbols]

 1: solar cell module 2: power storage device 3: inverter 4: (charge / discharge) control device 5: charge control device 10: remote control device

Claims (3)

[Claims] An electric power is input from a solar cell module, a power storage device, a discharge control device that controls discharge of the power storage device, a charge control device that controls charging of the power storage device from an external power supply, and power from the solar cell module or the power storage device. A solar power generation system comprising: an inverter that supplies power to an external power supply or a load, wherein the solar cell module is connected to the inverter so that the generated power is input to the inverter; The device is connected to the inverter via the discharge control device so that its output power is input to the inverter, and is connected to the external power supply via the charge control device. During the above inverter operation,
A photovoltaic power generation system characterized in that discharge of the power storage device is controlled such that input power from the solar cell module or the power storage device to the inverter is always equal to or greater than a predetermined value. 2. The photovoltaic power generation system according to claim 1, wherein the charging control device operates at night, and charging of the power storage device is performed at night. 3. The photovoltaic power generation system according to claim 1, further comprising a remote control device for performing a discharge operation control of said discharge control device or a charge operation control of said charge control device by a control signal by remote control. system.