JP5532429B2 - Operation control method of photovoltaic power generation system - Google Patents

Description

  The present invention relates to an operation control method for a photovoltaic power generation system in which a photovoltaic power generation system in which a solar cell is connected to a power system by a power conditioner is shifted from a standby state to an operating state, or is shifted from an operating state to a standby state. About.

  In recent years, a photovoltaic power generation system using sunlight is attracting attention as one of clean natural energy from the viewpoint of environmental protection. This solar power generation system includes a configuration in which a solar cell is connected to a power system such as a commercial power source by a power conditioner (power converter) including an inverter (see, for example, Patent Document 1).

  In the solar power generation system in which the solar battery and the power system are linked by a power conditioner, the above-described control is performed to control the supply of power generated by the solar battery to the load according to the amount of solar radiation. It is necessary to start and stop the entire system with the inverter. For example, in the morning when solar radiation becomes stronger, the system is started to start solar power generation, the system continues to operate in the daytime, and in the evening, solar radiation becomes weaker. When it comes, it is necessary to stop the system to stop the photovoltaic power generation.

  Conventionally, the start and stop of the photovoltaic power generation system has been such that the photovoltaic power generation system is shifted from the standby state to the operating state based on the following conditions, or the operating state is shifted to the standby state.

  By shifting the inverter from the standby state to the operating state at the time when the state where the solar radiation becomes stronger and the output voltage of the solar cell becomes larger than the start setting value of 400 V for a predetermined time in the morning, Start the system and start solar power generation.

  In the evening, when the solar radiation is weak and the generated power of the solar cell is less than 2% of the rated value for a predetermined time, the system is switched from the operating state to the standby state. It stops and stops photovoltaic power generation.

  As a protection function of the inverter, the system is stopped by shifting the inverter from the operating state to the standby state when the output voltage of the solar cell becomes lower than 300V even during system startup. To stop solar power generation.

JP-A-8-126208

  By the way, as described above, in the morning, when the solar radiation becomes stronger and the state where the output voltage of the solar cell becomes higher than 400V continues for a predetermined time, the power conditioner is shifted from the standby state to the operating state. Thus, the system is activated to start photovoltaic power generation.

  However, immediately after the start of the solar power generation, the output voltage of the solar cell may be reduced due to the interconnection with the power system by shifting the power conditioner from the standby state to the operating state. This decrease in the output voltage of the solar cell is significant when the amount of solar radiation is small in the morning. When the output voltage of the solar cell becomes lower than 300 V due to the decrease in the output voltage of the solar cell, the protective function of the power conditioner works as described above, and the system is moved from the operating state to the standby state by moving the power conditioner to the standby state. To stop the photovoltaic power generation.

  After that, when the solar radiation becomes stronger and the open voltage of the solar cell becomes larger than 400V for a predetermined time, the system is started by shifting the power conditioner from the standby state to the operating state. Solar power generation will be started again. However, when the amount of solar radiation is small in the morning, the output voltage of the solar cell becomes lower than 300 V due to a decrease in the output voltage of the solar cell, and the power conditioner is again turned on. This will cause the inverter to move from the operating state to the standby state.

  As a result, in the morning, it is easy for the inverter to repeat hunting from the standby state to the operating state and from the operating state to the standby state, and the number of huntings is very high. Stabilization was difficult.

  Therefore, the present invention has been proposed in view of the above-described problems, and the purpose of the present invention is to hunting in which the power conditioner repeats the transition from the standby state to the operation state and the transition from the operation state to the standby state. It is in providing the operation control method of the photovoltaic power generation system which can reduce the frequency | count of this.

As a technical means for achieving the above-described object, the present invention provides a photovoltaic power generation system in which a solar cell is connected to a power system by a power conditioner, and the output voltage of the solar cell becomes larger than a startup set value. when the state continues for the initial set time, the power of the conditioner is shifted from the standby state to the operating state, condition the output voltage of the solar cell is smaller than the protection level, the rated power generation of the solar cell of the solar cell An operation control method for causing the power conditioner to shift from an operating state to a standby state when a condition that is smaller than a predetermined ratio or a condition that causes a failure in the solar cell power generation system is satisfied. Only when the inverter is moved from the operating state to the standby state under the condition that the output voltage of the solar cell is smaller than the protection set value. , When the initial setting time was changed to long hunting avoidance time than the initialization time, when the output voltage of the solar cell is greater than the start set value continues for the hunting avoidance time, wait a power conditioner It is characterized by reducing the frequency | count of hunting which a power conditioner repeats a transition from a standby state to a driving | running state and a transition from a driving | running state to a standby state by making it transfer from a state to a driving | running state .

  In the present invention, the initial setting time is changed to the hunting avoidance time only when the inverter is shifted from the operating state to the standby state under the condition that the output voltage of the solar cell is smaller than the protection set value. When the output voltage is higher than the startup setting value for the hunting avoidance time, the inverter is moved from the standby state to the operating state. Even when the hunting avoidance time longer than the initial set value elapses, the solar radiation becomes sufficiently strong, and it becomes easy to maintain a state where the output voltage of the solar cell is equal to or higher than the startup set value.

  As a result, when the state in which the output voltage of the solar cell is higher than the startup setting value continues for the hunting avoidance time, the output voltage of the solar cell is protected after the inverter is shifted from the standby state to the operating state. The number of times that the protective function of the inverter is activated can be reduced by becoming smaller than the set value, and the hunting of the inverter that repeats the transition from the standby state to the operation state and the transition from the operation state to the standby state. The number of times can be reduced.

  Here, the “startup setting value” of the output voltage of the solar cell means a voltage that can be linked to the power system. In addition, the “protection set value” of the output voltage of the solar cell means an insufficient voltage for protecting the power conditioner. The above-mentioned “hunting avoidance time” is longer than the initial setting time and reduces the number of times of hunting. Therefore, even if the output voltage of the solar cell decreases due to interconnection with the power system during system startup, the power system This means the time during which it is easy to maintain a voltage that can be linked to.

  In the present invention, the condition for shifting the power conditioner from the operation state to the standby state is not limited to the condition that the output voltage of the solar cell is smaller than the protection set value, but the generated power of the solar cell is the rated value of the solar cell. For example, it may be smaller than a predetermined ratio or a failure may occur in the solar cell power generation system.

  According to the present invention, the initial setting time is changed to the hunting avoidance time only when the inverter is shifted from the operating state to the standby state under the condition that the output voltage of the solar cell is smaller than the protection setting value. When the battery output voltage is higher than the startup set value for the duration of the hunting avoidance time, the inverter is shifted from the standby state to the operating state, so the amount of solar radiation is low in the morning. Even in this case, the solar radiation becomes sufficiently strong while the hunting avoidance time longer than the initial setting value elapses, and it becomes easy to maintain the state where the output voltage of the solar cell is equal to or higher than the startup setting value.

  As a result, the number of times the protective function of the inverter is activated can be reduced, and the inverter can reduce the number of huntings that repeat the transition from the standby state to the operation state and the transition from the operation state to the standby state. be able to. By reducing the number of times of hunting, the photovoltaic power generation system can be stabilized, and a highly reliable photovoltaic power generation system can be provided.

In embodiment of this invention, it is a block diagram which shows schematic structure of a solar energy power generation system. It is a flowchart for demonstrating the control mode of the solar energy power generation system in the morning. It is a flowchart for demonstrating the control mode of the solar energy power generation system in daytime. It is a flowchart for demonstrating the control mode of the solar energy power generation system in the evening.

  The embodiment of the operation control method of the photovoltaic power generation system according to the present invention will be described in detail below. FIG. 1 is a block diagram showing a schematic configuration of a photovoltaic power generation system according to this embodiment.

  The solar power generation system in the embodiment shown in FIG. 1 includes a configuration in which a solar cell 20 is connected to a power system 30 such as a commercial power source by a power conditioner 10 (power conversion device) formed of an inverter. This solar power generation system includes a control unit 40 that controls the operation of the power conditioner 10 based on the output voltage or generated power of the solar battery 20. The power conditioner 10 converts the DC power generated by the solar cell 20 into AC by a switching operation by an inverter, and supplies the AC power to a load (not shown). As described above, the operation by the control unit 40 is performed. Start and stop the system under control. In addition, the code | symbol 50 in a figure is a connection transformer for connecting the power conditioner 10 and the electric power grid | system 30. FIG.

  In the solar power generation system in which the solar battery 20 and the power system 30 are linked by the power conditioner 10, the supply of the power generated by the solar battery 20 to the load is controlled according to the amount of solar radiation. Thus, the entire system is started and stopped by the power conditioner 10 described above. For example, in the morning when solar radiation becomes stronger, the system is started to start solar power generation, the system continues to operate in the daytime, and in the evening, solar radiation becomes weaker. When it comes, the system is stopped to stop the photovoltaic power generation.

  The start and stop of the solar power generation system in this embodiment is performed by shifting the solar power generation system from the standby state to the operation state or from the operation state to the standby state based on the following conditions.

  At the start of operation of the power conditioner 10, as shown in FIG. 2, in the morning, the solar radiation becomes stronger and the output voltage of the solar cell 20 is larger than the start setting value that can be connected to the power system 30, for example, 400V. When this state continues for the initial setting time α (STEP 1), the power conditioner 10 is shifted from the standby state to the operating state (STEP 2), thereby starting the system and starting photovoltaic power generation. The above-mentioned 400 V is a value that can be appropriately changed according to the scale of the photovoltaic power generation system, and can be set to an arbitrary value.

  Here, as described above, at the time when the solar radiation 20 becomes stronger and the output voltage of the solar cell 20 becomes larger than 400 V in the morning, the power conditioner 10 is brought into the standby state from the standby state. By shifting to the operating state, the system is started and solar power generation is started. Immediately after the start of this solar power generation, the power conditioner 10 is shifted from the standby state to the operating state to connect to the power system 30. Depending on the system, the output voltage of the solar cell 20 may decrease. The decrease in the output voltage of the solar cell 20 is remarkable when the amount of solar radiation is small in the morning.

  When the output voltage of the solar battery 20 is reduced to a protection setting value that is an insufficient voltage for protecting the power conditioner 10, for example, 300 V (STEP 3), the protection function of the power conditioner 10 is reduced. By operating the inverter 10 from the operating state to the standby state (STEP 4), the system is stopped and the photovoltaic power generation is stopped. The above-mentioned 300V is a value that can be appropriately changed according to the scale of the photovoltaic power generation system, and can be set to an arbitrary value.

  After that, when the state where the solar radiation becomes strong and the open voltage of the solar cell 20 becomes larger than 400 V continues for the initial setting time α, the power conditioner 10 is not shifted from the standby state to the operating state. The system is started and the photovoltaic power generation is started again. However, when the amount of solar radiation is small in the morning, the output voltage of the solar cell 20 is smaller than 300V due to the decrease in the output voltage of the solar cell 20. Thus, the protection function of the power conditioner 10 is activated again, and the power conditioner 10 is shifted from the operating state to the standby state.

  Therefore, in this embodiment, the initial setting time α is changed to the hunting avoidance time β only when the power conditioner 10 is shifted from the operating state to the standby state under the condition that the output voltage of the solar cell 20 is smaller than 300V. Then, when the state in which the output voltage of the solar cell 20 is greater than 400 V continues for the hunting avoidance time β (STEP 5), the power conditioner 10 is shifted from the standby state to the operating state (STEP 6).

  Note that the time during which the output voltage of the solar battery 20 continues to be higher than 400V is set to β, but this hunting avoidance time is arbitrarily set to an optimum value according to the photovoltaic power generation system. Settings can be changed. Here, the time for which the output voltage of the solar battery 20 continues to be higher than 400V is longer than the initial setting time α by, for example, about 180 times. In order to reduce the number of times of hunting, What is necessary is just to set as time when it is easy to maintain the voltage (400V) which can be connected with an electric power grid | system, even if the output voltage of the solar cell 20 falls by the grid connection.

  As described above, the initial setting time α is changed to the hunting avoidance time β only when the power conditioner 10 is shifted from the operating state to the standby state under the condition that the output voltage of the solar cell 20 is smaller than 300V. When the state in which the output voltage of the battery 20 is greater than 400V continues for the hunting avoidance time β, the inverter 10 is shifted from the standby state to the operating state. Even if the amount is small, the solar radiation becomes sufficiently strong while the hunting avoidance time β longer than the initial setting value α elapses, and it becomes easy to maintain the state where the output voltage of the solar cell 20 is 400 V or higher. .

  As a result, when the state in which the output voltage of the solar cell 20 is greater than 400V continues for the hunting avoidance time β, the output voltage of the solar cell 20 is changed after the power conditioner 10 is shifted from the standby state to the operating state. Is less than 300V, and the number of times the protective function of the power conditioner 10 is activated can be reduced, and the power conditioner 10 repeats the transition from the standby state to the operation state and the transition from the operation state to the standby state. The number of times of hunting can be reduced.

  In the daytime, as shown in FIG. 3, when a failure occurs due to a condition unrelated to the output voltage of the solar battery 20 (STEP 7) in the operating state of the power conditioner 10 (STEP 7), the power conditioner 10 The controller 10 is shifted from the operating state to the standby state (STEP 9). Thereafter, when the failure is recovered (STEP 10), when the state in which the output voltage of the solar cell 20 is higher than 400V continues for the initial setting time α (STEP 11), the power conditioner 10 is operated from the standby state. (STEP 12).

  Thus, when a failure occurs during the daytime due to a reason unrelated to the output voltage of the solar cell 20, the time during which the state in which the output voltage of the solar cell 20 is greater than 400V continues is defined as the hunting avoidance time. By maintaining the initial setting time α, which is a short time, without changing to β, loss of the power generation amount of the solar cell 20 in the daytime is prevented in advance.

  Then, as shown in FIG. 4, in the evening, when the power conditioner 10 is in operation (STEP 13), the solar radiation is weakened and the generated power of the solar cell 20 is smaller than a predetermined ratio of the rated value, for example, 2%. When the state continues for a predetermined time γ (STEP 14), the power conditioner 10 is shifted from the operating state to the standby state (STEP 15) to stop the system and stop the photovoltaic power generation.

  In addition, the above-mentioned 2% is a value that can be appropriately changed according to the scale of the photovoltaic power generation system, and can be set to an arbitrary value. Further, the predetermined time γ during which the generated power of the solar cell 20 continues to be smaller than 2% of the rating is not changed from the initial setting time α to the hunting avoidance time β as described above, and is unchanged. is there.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

10 Power conditioner 20 Solar cell 30 Power system α Initial setting time β Hunting avoidance time

Claims (1)

In a solar power generation system in which a solar cell is connected to a power system by a power conditioner, when the state in which the output voltage of the solar cell is larger than a startup setting value continues for an initial setting time, the power conditioner From the standby state to the operating state, the condition that the output voltage of the solar cell becomes smaller than the protection setting value, the condition that the generated power of the solar cell becomes smaller than the predetermined ratio of the rated value of the solar cell, or the failure of the solar cell power generation system Is an operation control method for causing the power conditioner to shift from an operation state to a standby state at the time when any one of the conditions occurs .
The hunting avoidance time longer than the initial setting time only when the inverter is shifted from the operating state to the standby state under the condition that the output voltage of the solar cell is smaller than the protection setting value. change to, when the state in which the output voltage of the solar cell is greater than the start set value continues for the hunting avoidance time, by shifting the power conditioner from the standby state to the operation state, power conditioners An operation control method for a photovoltaic power generation system, characterized in that the number of huntings in which the na repeats the transition from the standby state to the operation state and the transition from the operation state to the standby state is reduced .

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