JP6909056B2 - Power converter, control method of power converter and power generation system - Google Patents

Description

The present invention relates to a power conversion device, a control method for the power conversion device, and a power generation system. In particular, the control method for the power conversion device and the power conversion device, which is effective when the power output from the DC power source is output to the power system. And about the power generation system.

In recent years, power generation systems that use natural energy, such as photovoltaic power generation systems, have become widespread. In addition, DC power generated by a power generation system using natural energy is converted into predetermined AC power and supplied to a household load, or reverse power flow to the power system.

If the number of power generation systems that use natural energy increases and the amount of power that reverses the power system increases, the system voltage rises, which becomes a problem. Therefore, it is required to control the output of the power conversion device so that the system voltage does not rise. For example, Patent Document 1 discloses a power conversion device that suppresses the power conversion capacity of AC power generated by itself so that the voltage value of system power does not exceed the upper limit value. Further, a power converter or a power conditioner capable of reverse power flow is usually provided with an overvoltage protection function so that the operation is stopped and the output is stopped when the output voltage exceeds a predetermined upper limit voltage.

In addition, the "System Interconnection Regulations" (Non-Patent Document 1) issued by the Japan Electric Association includes a function to advance the phase of the power conditioner at a constant power factor as a measure to suppress the voltage rise due to reverse power flow. It is described that the output control function is provided.

Japanese Unexamined Patent Publication No. 2015-116064

"System interconnection regulations JEAC 9701-2016", published by the Japan Electric Association (issued on August 9, 2016, 7th edition)

According to the grid interconnection provision of Non-Patent Document 1 (for example, page 122), either a phase-advancing ineffective power control function or an output control function may be adopted on the power converter side as a countermeasure when the grid voltage rises. Has been described. Further, at the time of output control, a predetermined output control operation is started after a predetermined time has elapsed after detecting an increase in the system voltage, and after the system voltage has decreased, the output suppression value of the power converter is determined to be 0. There is a statement that sometimes the timer that counts the elapsed time is initialized (for example, the voltage adjustment flow on page 130).

The above-mentioned Patent Document 1 discloses that the power conversion ability of the AC power generated by itself is suppressed so that the voltage value (system voltage) of the system power does not exceed the upper limit value, but the elapsed time is counted. It is not taken into consideration that the system voltage may rise and the overvoltage protection function may be activated during the operation.

Therefore, if the output voltage reaches a predetermined upper limit voltage before the output control is started, the output is stopped and the power conversion device is disconnected from the system power, so that the power generation system cannot be effectively used. It becomes a problem.

Therefore, in a grid interconnection system in which the power generated by a DC power source using natural energy is reverse-flowed to the power system, the system voltage can be controlled so as not to exceed the upper limit, and the power generation capacity of the DC power source can be wasted. Instead, it is preferable to be able to provide a power generation system that enables high-rate and good power generation operation.

Therefore, in view of the above problems, the present invention can easily control the system without increasing the system voltage in the system interconnection system that converts DC power into a predetermined power and outputs it to the power system, and prevents unnecessary disconnection. It is an object of the present invention to provide a power conversion device, a control method of the power conversion device, and a power generation system that can prevent sudden fluctuations in the power system and enable effective utilization without wasting the power generation capacity of the DC power source. ..

In order to achieve the above object, the present invention converts the input unit to which the DC power source is connected, the output unit connected to the power system, and the DC power input to the input unit into predetermined power and outputs the power. It includes a power conversion unit that outputs to the unit and a control device that controls the output of the power conversion unit. The control device controls the output of the power conversion unit according to the system voltage of the power system, and also has a predetermined first voltage value, a third voltage value that serves as a threshold for stopping the output of the power conversion unit, and a first voltage. From the time when the system voltage rises and becomes larger than the first voltage value to the time when the system voltage falls to the first voltage value based on the second voltage value set between the value and the third voltage value. During that time, the output of the power conversion unit is controlled so that the system voltage does not exceed the second voltage value, and after the system voltage drops to the first voltage value, the system voltage does not exceed the first voltage value. It is characterized by controlling the output of the power conversion unit.

According to this configuration, the output control is started when the system voltage becomes higher than the first voltage value, and the output is controlled so that the system voltage does not exceed the second voltage value. Therefore, the output is stopped at the third set voltage value. Is no longer reached, and the output of the power converter does not have to be stopped. Therefore, in a grid interconnection system that converts DC power into predetermined power and outputs it to the power system, control that does not raise the system voltage can be easily performed, and sudden fluctuations in the power system can be prevented by preventing unnecessary disconnection. In addition, it is possible to obtain a power conversion device that can be effectively used without wasting the power generation capacity of the DC power source.

Further, the power conversion device according to the present invention converts the input unit to which the DC power source is connected, the output unit connected to the power system, and the DC power input to the input unit into predetermined power and outputs the output. A power conversion unit that outputs to the unit and a control device that controls the output of the power conversion unit are provided, and the control device controls the output of the power conversion unit according to the system voltage of the power system and controls the output. Based on the fourth voltage value, which is the target value, the third voltage value, which is the threshold for stopping the output of the power converter, and the second voltage value set between the fourth voltage value and the third voltage value. The output of the power conversion unit so that the system voltage does not exceed the second voltage value from the time when the system voltage rises and becomes larger than the fourth voltage value until the system voltage falls to the fourth voltage value. The output of the power conversion unit may be controlled so that the system voltage does not exceed the fourth voltage value after the system voltage drops to the fourth voltage value.

Further, the power conversion device according to the present invention converts the input unit to which the DC power source is connected, the output unit connected to the system power, and the DC power input to the input unit into predetermined power and outputs the power. It includes a power conversion unit that outputs to the unit and a control device that controls the output of the power conversion unit. The control device controls the output of the power conversion unit according to the system voltage of the power system, and the system voltage rises. In this case, the first output control is performed to control the output of the power conversion unit so that the system voltage does not exceed the second voltage value, and after the first output control, the system voltage is smaller than the second voltage value. The second output control that controls the output of the power conversion unit may be performed so as not to exceed the value.

Further, the power conversion device according to the present invention is a power conversion device including a power conversion unit that converts DC power generated by a DC power source into a predetermined power and outputs it to a power system, and is predetermined as a system voltage. The output of the power conversion unit is controlled by comparing with the voltage value of the above, and as the predetermined voltage value, the first voltage value which is the threshold for starting the output control operation and the threshold for stopping the output of the power conversion unit. It has a third voltage value that becomes Execute the operation Start the counting operation, and when the system voltage reaches the second voltage value during the counting operation, power is supplied so that the system voltage does not become higher than the second voltage value even if the elapsed time does not reach the standby time. The configuration may include a control device that starts a first output control operation for controlling the output state of the conversion unit.

Further, the above-mentioned control device includes a voltage acquisition unit, a storage unit, a count unit, a comparison unit, an output control unit, and an output stop unit, and the voltage acquisition unit is a voltage value of a power system to which a power conversion device is connected. The storage unit acquires a predetermined standby time until a predetermined control operation for controlling the output of the power conversion unit is started, and the first voltage value, the second voltage value, and the third voltage value. , The counting unit performs a counting operation and counts the elapsed time from the time when the system voltage reaches each voltage value, and the comparison unit performs the elapsed time, the predetermined standby time, and the system. The voltage is compared with each voltage value, the output control unit executes the output control operation of the power conversion unit, and the output stop unit stops the output of the power conversion unit when the system voltage reaches the third voltage value. It is preferable to do so.

Further, in the power conversion device having the above configuration, the power purchase state in which power is received from the power system, the power sale state in which the predetermined power generated by the power conversion unit is transmitted to the power system, and the power reception and transmission are performed. The first output control operation is performed at least when it has a state recognition unit that recognizes a non-trading 0 state and recognizes a power buying state, a power selling state, and a buying / selling 0 state through the state recognition unit. It is preferable to control the output state of the power conversion unit so that the system voltage does not exceed the second voltage value until the predetermined standby time elapses, and the system voltage reaches the second voltage value during the counting operation. When this is detected, it is preferable to immediately start the first output control operation, and when it is detected that the system voltage is higher than the first voltage value when the elapsed time reaches a predetermined standby time, the system voltage becomes high. It is preferable to start the second output control operation that controls the output state of the power conversion unit so as not to exceed the first voltage value.

Further, in the power conversion device having the above configuration, when it is recognized that the power is being sold through the state recognition unit, it is preferable to perform the second output control operation, and the power conversion device is not in the power selling state via the state recognition unit. The second output control operation may be performed even when it is recognized.

Further, the present invention is a control method of a power conversion device including a power conversion unit that converts DC power generated by a DC power source into predetermined power and outputs it to a power system, when the system voltage of the power system rises. In addition, after the first output control step that controls the output of the power conversion unit so that the system voltage does not become larger than the second voltage value and the first output control step, the system voltage is smaller than the second voltage value. It is characterized by including a second output control step for controlling the output of the power conversion unit so as not to be larger than the four voltage values.

With this configuration, in a grid interconnection system that converts DC power into predetermined power and outputs it to the power system, control that does not raise the system voltage can be easily performed, and the power system is steep by preventing unnecessary disconnection. It is possible to obtain a control method for a power conversion device that can prevent various fluctuations and effectively utilize the power generation capacity of a DC power source without wasting it.

Further, in the control method of the power conversion device having the above configuration, the second voltage value is preferably smaller than the third voltage value which is the threshold value for stopping the output of the power conversion unit.

Further, the present invention is a control method of a power conversion device including a power conversion unit that converts DC power generated by a DC power source into a predetermined power and outputs the DC power to a power system, and obtains a system voltage and a predetermined voltage value. By comparison, the output of the power conversion unit 10 is controlled, and the predetermined voltage value is a first voltage value that is a threshold for starting the output control operation and a third voltage value that is a threshold for stopping the output of the power conversion unit. The voltage value and the second voltage value provided between the first voltage value and the third voltage value are set in advance, and when the system voltage reaches the first voltage value, the output control operation is executed after a predetermined standby time elapses. When the system voltage reaches the second voltage value during the counting operation, the power conversion unit prevents the system voltage from becoming higher than the second voltage value even if the elapsed time does not reach the standby time. It is characterized in that the first output control operation for controlling the output state is started.

With this configuration, even if the system voltage reaches the first voltage value, from the third voltage value, which is the threshold value at which the system voltage stops the output of the power conversion unit during the counting operation until the output control operation is started. Since it can be controlled so that it does not become higher than the lower second voltage value, it is easy to control the system voltage without increasing it in a grid interconnection system that converts DC power into a predetermined power and outputs it to the power system, which is unnecessary. By preventing the disconnection, it is possible to prevent abrupt fluctuations in the power system and obtain a control method for a power conversion device that enables effective utilization without wasting the power generation capacity of the DC power source.

Further, in the control method having the above configuration, the counting operation is started when the system voltage reaches the first voltage value, and when the system voltage is higher than the first voltage value even after the elapsed time elapses, the system voltage becomes higher. The second output control operation that controls the output state of the power converter so as not to exceed the first voltage value is performed, and even if the predetermined standby time is not reached during the count operation, the system voltage becomes the second set voltage value. When it reaches, the first output control operation is started immediately, the second output control operation is started after the count operation elapses a predetermined standby time, and during this second output control operation, the system voltage becomes higher than the first voltage value. When it becomes low, it is preferable to stop the second output control operation.

Further, the present invention may be a power generation system including a power conversion device having the above configuration and a DC power source for supplying power to the power conversion device.

According to the present invention, in a grid interconnection system that converts DC power into a predetermined power and outputs it to the power system, control that does not raise the system voltage can be easily performed, and the power system is steep by preventing unnecessary disconnection. It is possible to obtain a power conversion device, a control method of the power conversion device, and a power generation system that can prevent various fluctuations and effectively utilize the power generation capacity of the DC power source without wasting it.

It is a schematic explanatory drawing which shows the whole structure of the power generation system provided with the power conversion apparatus which concerns on this invention. It is a graph which shows the outline of the change of the system voltage and the 1st output control operation. It is a graph which shows the change of the system voltage and the outline of the 1st and 2nd output control operations. It is a graph which shows the change of the system voltage and the modification of the 1st and 2nd output control operations. It is a flowchart which shows an example of the control method of the power conversion apparatus which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. Further, the same reference numerals are used for the same constituent members, and duplicate description will be omitted as appropriate.

FIG. 1 is a schematic explanatory view showing an overall configuration of a power generation system 1 provided with a power conversion device 3 according to the present invention. FIG. 2 is a graph showing a change in the system voltage and an outline of the first output control operation, and FIG. 3 is a graph showing an outline of the change in the system voltage and the first and second output control operations.

As shown in FIG. 1, the power generation system 1 according to the present invention is configured by connecting a DC power source 2 (for example, photovoltaic power generation) to a power system 5 via a power conversion unit 10. The power conversion unit 10 is connected to the control device 13, and the operation of the power conversion unit 10 is controlled by the control device 13. Then, the DC power generated by the DC power source 2 is converted into a predetermined power by the power conversion unit 10 and the control device 13, is supplied to the load 6 via the power distribution board 4, and is also supplied to the load 6 via the power distribution board 4. Can be transmitted to.

As the DC power source 2, for example, a DC power source such as a solar power generation device, a wind power generation device, or a fuel cell can be used. In this embodiment, a photovoltaic power generation device using a solar cell is applied as a DC power source. However, other DC power sources may be used, or a plurality of different DC power sources may be used in combination.

The power conversion unit 10 is, for example, a first power conversion unit 11 that converts a DC voltage supplied from the DC power source 2 into a predetermined DC voltage, and a first power conversion unit 11 that converts the DC power supplied from the first power conversion unit 11 into a predetermined power. It has a second power conversion unit 12 that converts and outputs to.

The control device 13 according to the present embodiment controls the power conversion unit 10. The predetermined power output from the power conversion unit 10 is output to the power system 5 and the load 6 via the switchboard 4. The control device 13 has at least a voltage acquisition unit, a storage unit, a comparison unit, a count unit, an output control unit, and an output stop unit. Further, it is preferable to have a state recognition unit described later. The voltage acquisition unit acquires the voltage value of the power system 5 to which the power conversion device 3 is connected, and the storage unit stores the standby time T11 and a plurality of settling voltage values and target voltage values.

For example, the first voltage value (first set voltage value V01), the second voltage value (second set voltage value V02), and the third voltage value (third set voltage value V03) are stored as the set voltage values. Further, other target voltage values may be stored. The standby time T11 is a standby time until a predetermined second output control operation for controlling the output of the power conversion unit 10 is started. The first settling voltage value V01 is a settling voltage value that serves as a threshold value for performing an output control operation, and the third settling voltage value V03 is a settling voltage value that serves as a threshold value for stopping the output. The second set voltage value V02 is a set value provided between the first set voltage value V01 and the third set voltage value V03, and is a voltage slightly lower than the third set voltage value V03.

For example, in a power system that transmits 100 volt AC power, the normal system voltage V00 is, for example, 101 volt, the first set voltage value V01 is, for example, 109 volt, and the second set voltage value V02 is, for example, 114 volt. The third set voltage value V03 is, for example, 115 volts.

The counting unit counts the elapsed time from when the system voltage V0 reaches a predetermined voltage value (for example, the first set voltage value V01), and the comparison unit counts the elapsed time, the predetermined standby time T11, and the system. The voltage V0 is compared with the stored predetermined voltage value. Here, as the system voltage V0 used for comparing the system voltage V0 with a predetermined voltage value, it is preferable to use the voltage detected by the output unit 15 of the power conversion device 3 as the power receiving unit. Further, the voltage detected by the switchboard 4 may be used. When the grid power is alternating current, the effective value of the detected voltage is set to the grid voltage V0.

The output control unit executes the output control operation of the power conversion unit 10, and the output stop unit outputs the output of the power conversion unit 10 when the system voltage V0 reaches the third voltage value (third set voltage value V03). Stop. That is, the third set voltage value V03 corresponds to the upper limit voltage of the overvoltage protection, and the output stop unit corresponds to the overvoltage protection unit.

Then, when the comparison unit detects that the system voltage V0 to be received is higher than the first voltage value (first set voltage value V01), it starts a counting operation for counting the elapsed time via the counting unit and counts. When the system voltage V0 reaches the second voltage value (second set voltage value V02) during operation, even if the elapsed time does not reach the predetermined standby time T11, the output control unit tells the output control unit that the system voltage V0 is the second voltage. It is characterized in that the first output control operation OP1 for controlling the output state of the power conversion unit 10 is started so as not to be higher than the value (second set voltage value V02). The second settling voltage value V02 may be a voltage slightly lower than the third settling voltage value V03, for example, a voltage about 1 volt lower than the third settling voltage value V03.

The first output control operation OP1 may be shared by both output control that suppresses the output so that the system voltage V0 does not become higher than the second set voltage value V02, and phase advance invalid power control. In any case, the system voltage V0 is controlled so as not to be higher than the second set voltage value V02.

<First Embodiment>
Next, a first embodiment of the output control operation will be described with reference to FIG.

As shown in FIG. 2, the output control operation of the first embodiment starts the counting operation from T01 when the system voltage V0 reaches the first set voltage value V01 from the normal voltage V00. That is, the time point T01 becomes the count operation start point CS. Although the counting operation is started, the output control operation for controlling the output state of the power conversion unit 10 is not yet performed. Here, the first set voltage value V01 corresponds to the first voltage value of the present invention.

Then, when the system voltage V0 reaches the second settling voltage value V02 during the counting operation (time point T02), the system voltage V0 is higher than the second settling voltage value V02 even if the predetermined standby time has not elapsed. The first output control operation OP1 that controls the output state of the power conversion unit 10 is started. If this first output control operation OP1 is not performed, the system voltage V0 further rises and reaches the third set voltage value V03 at the upper limit voltage reaching point SS, and the operation of the power conversion unit 10 is stopped. Sometimes. Here, the second set voltage value V02 corresponds to the second voltage value of the present invention, and the third set voltage value V03 corresponds to the third voltage value of the present invention.

That is, as shown in FIG. 2, during the first output control operation OP1, the system voltage V0 maintains a voltage value that does not become higher than the second set voltage value V02. As a result, when the system voltage V0 reaches the second set voltage value V02 during the counting operation, the first output control operation OP1 for controlling the output state of the power conversion unit 10 is started even if the elapsed time does not reach the standby time. Since the system voltage V0 can be prevented from becoming higher than the second set voltage value V02, the third set voltage value V03, which stops the output, is not reached, and the output of the power conversion unit 10 does not have to be stopped. get well. Therefore, in a grid interconnection system that converts DC power into predetermined power and outputs it to the power system 5, control that does not raise the system voltage V0 can be easily performed, and by preventing unnecessary disconnection, the power system 5 is steep. It is possible to obtain a power conversion device 3 that prevents fluctuations and enables effective utilization without wasting the power generation capacity of the DC power source 2.

<Second Embodiment>
Next, a second embodiment of the output control operation will be described with reference to FIG.

As shown in FIG. 3, in the output control operation of the second embodiment, the counting operation is started from T01 when the system voltage V0 reaches the first set voltage value V01 from the normal voltage V00, and the system voltage V0 is the time point T02. When the second set voltage value V02 is reached, the first output control operation OP1 for controlling the output state of the power conversion unit 10 so that the system voltage V0 does not become higher than the second set voltage value V02 is started in the first execution. It is the same as the form.

After that, when the system voltage is detected to be higher than the first settling voltage value V01 at the time point T03 when the count operation is continued and the predetermined standby time T11 is reached, the output control unit sets the system voltage V0. The configuration is such that the second output control operation OP2, which controls the output state of the power conversion unit 10 so as not to exceed the set voltage value V01, is started. That is, the time point T03 becomes the count operation end point CT.

With this configuration, the system voltage V0 is set within a range in which the voltage rise can be suppressed by adjusting the output of the power conversion device 3 by controlling the output so that the system voltage V0 does not exceed the first set voltage value V01. Control that does not raise the voltage becomes possible, and effective utilization is possible without wasting the power generation capacity of the DC power source 2.

That is, as shown in FIG. 3, during the first output control operation OP1 between the time point T02 and the time point T03, the system voltage V0 maintains a voltage that does not become higher than the second settling voltage value V02, but is determined by counting. If the system voltage V0 is higher than the first set voltage value V01 even after the elapsed time T11 has elapsed, the second output control operation OP2 for controlling the output state of the power conversion unit 10 under new conditions is started. The system voltage V0 should not be higher than the first set voltage value V01. Here, the first set voltage value V01 in the second output control operation OP2 corresponds to the fourth voltage value of the present invention. That is, the fourth voltage value is the target voltage value for output control, and in the present embodiment, the fourth voltage value is the same as the first voltage value, the first set voltage value V01, but different values may be used.

The second output control operation OP2 may be shared by both output control that suppresses the output so that the system voltage V0 does not become higher than the first set voltage value V01 and phase advance reactive power control, and the system voltage V0 is It suffices if it can be controlled so as not to be higher than the first set voltage value V01. The first output control operation OP1 is preferably performed when the power is sold, the power is purchased, and the trading is 0, and the second output control operation OP2 is preferably performed when the power generation system 1 is selling power. It is not necessary to perform the second output control operation OP2 when the power is not sold. Therefore, ON / OFF of the second output control operation OP2 may be switched according to the power selling state and the power selling state. Further, the configuration may be such that the second output control operation OP2 is performed even if the power is not sold.

That is, the control device 13 of the present embodiment has a power purchase state in which power is received from the power system 5 and a power sale state in which predetermined power generated by the power conversion unit 10 is transmitted to the power system 5. It has a state recognition unit that recognizes a trading 0 state in which power is not received from the power system 5 and a predetermined power generated by the power conversion unit 10 is not transmitted to the power system 5. It is preferable to perform the second output control operation OP2 when it is recognized through the recognition unit that the power is being sold. With this configuration, when the power is sold, that is, when at least a part of the DC power generated by the DC power source 2 is output to the power system 5, the system voltage is obtained by performing the second output control operation OP2. Control that does not raise V0 can be easily performed, and by preventing unnecessary disconnection, steep fluctuations in the power system 5 can be prevented, and the power generation capacity of the DC power source 2 can be effectively utilized without wasting it.

<Third Embodiment>
Next, a third embodiment of the output control operation will be described with reference to FIG. The third embodiment is a modification of the second embodiment, and when the system voltage V0 drops below the second set voltage value V02 while the first output control operation OP1 is being performed, the first output control is once performed. This is an embodiment in which the operation OP1 is stopped.

When the first output control operation OP1 for controlling the output state of the power conversion unit 10 is performed so that the system voltage V0 does not become higher than the second set voltage value V02, the system voltage V0 becomes the second set voltage value at the time point T02a. When the voltage drops below V02, the first output control operation OP1 is temporarily stopped. Further, when the system voltage V0 is higher than the first settling voltage value V01 and lower than the second settling voltage value V02, the counting operation is continued. Then, when the system voltage V0 becomes higher than the second set voltage value V02 again, the first output control operation OP1 may be started again at the time point T02b.

<Fourth Embodiment>
The power conversion unit 10 and the control device 13 may be combined with another device, but the power conversion device 3 including the power conversion unit 10 and the control device 13 may be used. The configuration will be described with reference to FIGS. 1 to 3 as a fourth embodiment.

The power conversion device 3 according to the present embodiment can convert the DC power generated by the DC power source 2 into a predetermined AC power and output it to the power system 5. The DC power source 2 is connected to the input unit 14 of the power conversion device 3, and the input unit 14 is connected to the power conversion unit 10 inside the power conversion device 3. The power conversion unit 10 converts, for example, a DCDC converter unit that converts the DC voltage supplied from the DC power source 2 into a predetermined DC voltage and outputs it, and a DCDC converter unit that converts the DC voltage supplied from the DCDC converter unit into a predetermined AC voltage. The wiring that has an inverter unit that outputs the output and is connected to the DCDC converter unit and the inverter unit is called a DC bus. In this case, the first power conversion unit 11 described above corresponds to the DCDC converter unit, and the second power conversion unit 12 corresponds to the inverter unit. Further, the power conversion device 3 having only the inverter unit may be used. The output of the power conversion unit 10 is connected to the output unit 15 inside the power conversion device 3. The output unit 15 is configured to be connectable to the power system 5 and the load 6 via the switchboard 4.

Further, the power conversion device 3 may include a third power conversion unit 16 that charges and discharges the power of the storage battery 20. The control device 13 can control the third power conversion unit 16 and can control the connection and disconnection switching of the storage battery 20 and the charging / discharging operation of the storage battery 20. Then, the storage battery 20 may be connected to the power conversion device 3 to charge the surplus power of the DC power generated by the DC power source 2, and when the cost of the power purchased from the system power 5 such as at night is low, The storage battery 20 may be charged with electric power. A configuration having the storage battery 20 is preferable because the suppressed power can be used for charging the storage battery 20 and the generated power is not wasted.

The control device 13 included in the power conversion device 3 has a voltage acquisition unit, a storage unit, a counting unit, a comparison unit, an output control unit, an output stop unit, and a state recognition unit, as in the above-described embodiment. Further, the storage unit has a predetermined standby time T11 until a predetermined control operation for controlling the output of the power conversion unit 10 is started, and a set voltage value for controlling the power output to the power system 5. Between the first set voltage value V01, which is the threshold for performing the output control operation, the third set voltage value V03, which is the threshold for stopping the output, and the first set voltage value V01 and the third set voltage value V03. The second settling voltage value V02 provided in the above is stored. As described above, the second settling voltage value V02 may be a voltage about 1 volt lower than the third settling voltage value V03.

Then, as shown in FIG. 3, the counting operation is started from T01 when the system voltage V0 reaches the first settling voltage value V01, and when the system voltage V0 reaches the second settling voltage value V02 at the time point T02, the system The first output control operation OP1 for controlling the output state of the power conversion unit 10 is started so that the voltage V0 does not become higher than the second set voltage value V02, and the time T03 is reached when the predetermined standby time T11 elapses. When it is detected that the system voltage is higher than the first set voltage value V01, the output control unit controls the output state of the power conversion unit 10 so that the system voltage V0 does not exceed the first set voltage value V01. 2 Output control operation OP2 is started.

The first output control operation OP1 that controls the output state of the power conversion unit 10 so that the system voltage V0 does not become higher than the second set voltage value V02 stops when the system voltage V0 becomes lower than the second set voltage value V02. In the second output control operation OP2 that controls the output state of the power conversion unit 10 so that the system voltage V0 does not exceed the first set voltage value V01, the system voltage V0 becomes lower than the first set voltage value V01. You just have to stop when.

That is, according to the present embodiment, in a grid interconnection system that converts DC power into predetermined power and outputs it to the power system 5, control that does not increase the voltage value of the grid power can be easily performed, and unnecessary disconnection can be performed. By preventing this, it is possible to obtain a power conversion device 3 that can prevent abrupt fluctuations in the power system 5 and can be effectively used without wasting the power generation capacity of the DC power source 2.

<Control method of power converter>
Next, the control method of the power conversion device 3 will be described in detail using the flowchart of FIG.

The start of the output control operation starts by comparing the system voltage V0 with the first voltage value (first set voltage value V01), and when it is detected that the system voltage V0 becomes higher than the first voltage value (step S1). If YES in "V0 ≧ V01?"), The waiting time counting operation is started in step S2. When the system voltage V0 is lower than the first voltage value, the count unit is count reset (step S1A).

Even during the counting operation, when the system voltage V0 is detected and it is detected that the system voltage V0 has reached the second voltage value (second set voltage value V02) (V0 = V02? In step S3), Output control 1 is performed in the YES direction from step S3 so that V0 ≦ V02 in step S4. That is, the first output control operation OP1 for controlling the output state is started so that the system voltage V0 does not become higher than the second set voltage value V02. That is, the output control 1 corresponds to the first output control operation OP1.

If it is NO in step S3, it is determined in step S3A whether or not the output control 1 is being executed, and if it is being executed, the process proceeds to step S3B to stop the output control 1 and continue the counting operation. If it is determined in step S3A that the output control 1 has not been performed, the counting operation may be continued as it is.

The counting operation is continued even when the output control 1 is performed, and when the count reaches a predetermined standby time T11 (YES in T = T11? In step S5), the output control 1 ends (step S6). At this time, it is detected whether or not the system voltage V0 is higher than the first voltage value (first set voltage value V01) (V0 ≧ V01 in step S7?).

When it is detected in step S7 that the system voltage V0 is lower than the first set voltage value V01, the process proceeds in the NO direction from step S7, the operation ends, and the end is reached. When it is detected in step S7 that the system voltage V0 is higher than the first set voltage value V01, the process proceeds to step S8 in the YES direction, and output control 2 for setting V0 ≦ V01 is performed. That is, the second output control operation OP2 that controls the output state so that the system voltage V0 does not become higher than the first set voltage value V01 is started. That is, the output control 2 corresponds to the second output control operation OP2. That is, the control method of the present embodiment includes a first output control step and a second output control step.

The output control 2 continues while the system voltage V0 is higher than the first voltage value (first set voltage value V01), and stops when it detects that the system voltage V0 has become lower. That is, if YES in "V0 <V01?" In step S9, the output control 2 ends (step S10) and ends.

Even after the output control operation is completed, the detection operation for detecting the system voltage V0 is continued, and when it is detected that the system voltage V0 rises and reaches the first voltage value (first set voltage value V01), the next output is output. The control operation should be started.

As described above, the control method of the power conversion device 3 according to the present embodiment starts the counting operation when the system voltage V0 reaches the first voltage value, and the system voltage even if the elapsed time elapses the predetermined standby time T11. When V0 is higher than the first voltage value, a second output control operation for controlling the output state of the power conversion unit 10 is performed so that the system voltage V0 does not exceed the first voltage value, and a predetermined standby time is performed during the counting operation. Even if T11 is not reached, the first output control operation is started immediately when the system voltage V0 reaches the second voltage value, and the second output control operation is started after the count operation has elapsed the predetermined standby time T11. If the system voltage V0 becomes lower than the first voltage value during this second output control operation, the second output control operation is stopped.

That is, the control method having the above configuration includes a first output control step for controlling the output of the power conversion unit 10 so that the system voltage V0 does not become larger than the second voltage value, and a system voltage V0 after the first output control step. A second output control step is provided for controlling the output of the power conversion unit 10 so that the voltage is smaller than the second voltage value and does not become larger than a predetermined target voltage value. The target voltage value may be the first voltage value or a fourth voltage value different from the first voltage value. In this case, the first output control step is a control method of the power conversion device 3 performed when the system voltage V0 is larger than the fourth voltage value.

Although it has been described that the storage unit stores a plurality of set voltage values and target voltage values, these voltage values may be set by remote control or communication from the outside. Alternatively, it may be a value calculated in the CPU.

The predetermined standby time T11 may also be set by communication from the remote controller or the outside, or may be set in the storage unit in advance. Alternatively, it may be a value calculated in the CPU.

The method for determining whether or not the output control described above is performed is to determine that the output control is performed by checking the phase shift or power factor between the voltage and the current when injecting phase-advancing reactive power. can. Further, in the case of control for reducing the output power, one method can be determined by whether or not the maximum power of the DC power source to be input is output. For example, in the PV simulated power supply, a certain maximum power point can be determined. It suffices to make an input to have and confirm whether the PV is operating at that power point. As another method, since the DC bus voltage rises in the output control state as compared with the case where the output is not controlled, the output control state can be confirmed by detecting the DC bus voltage.

As described above, in the power conversion device 3 according to the present embodiment, the input unit 14 to which the DC power source 2 is connected, the output unit 15 connected to the power system 5, and the DC power input to the input unit 14 Is provided with a power conversion unit 10 that converts the power into a predetermined power and outputs the power to the output unit 15, and a control device 13 that controls the output of the power conversion unit 10. The control device 13 controls the output of the power conversion unit 10 according to the system voltage V0 of the power system 5, and also has a predetermined first voltage value and a third voltage value that serves as a threshold for stopping the output of the power conversion unit 10. And, based on the second voltage value set between the first voltage value and the third voltage value, the system voltage V0 becomes the first from the time when the system voltage V0 rises and becomes larger than the first voltage value. The output of the power conversion unit 10 is controlled so that the system voltage V0 does not exceed the second voltage value until the system voltage V0 drops to the first voltage value. After the system voltage V0 drops to the first voltage value, the system voltage V0 becomes The output of the power conversion unit 10 is controlled so as not to exceed the first voltage value.

With this configuration, output control is started when the system voltage V0 becomes higher than the predetermined first voltage value (first set voltage value V01), and the system voltage V0 becomes the second voltage value (second set voltage). Since the value is not higher than V02), the third voltage value (third set voltage value V03) for stopping the output is not reached, and the output of the power conversion unit 10 does not have to be stopped. Therefore, in a grid interconnection system that converts DC power into predetermined power and outputs it to the power system 5, control that does not raise the system voltage V0 can be easily performed, and by preventing unnecessary disconnection, the power system 5 is steep. It is possible to obtain a power conversion device 3 that prevents fluctuations and enables effective utilization without wasting the power generation capacity of the DC power source 2.

Further, in the power conversion device 3 according to the present invention, the input unit 14 to which the DC power source 2 is connected, the output unit 15 connected to the power system 5, and the DC power input to the input unit 14 are used as predetermined power. A power conversion unit 10 that converts to and outputs to the output unit 15 and a control device 13 that controls the output of the power conversion unit 10 are provided, and the control device 13 powers according to the system voltage V0 of the power system 5. The output of the conversion unit 10 is controlled, and the fourth voltage value, which is the target value of the output control, the third voltage value V03, which is the threshold for stopping the output of the power conversion unit 10, the fourth voltage value, and the third voltage value. From the time when the system voltage V0 rises and becomes larger than the fourth voltage value based on the second voltage value V02 set between the voltage value V03 and until the system voltage V0 falls to the fourth voltage value. During that time, the output of the power conversion unit 10 is controlled so that the system voltage V0 does not exceed the second voltage value V02, and after the system voltage V0 drops to the fourth voltage value, the system voltage V0 exceeds the fourth voltage value. The output of the power conversion unit 10 is controlled so as not to be present. Even with this configuration, in a grid interconnection system that converts DC power into predetermined power and outputs it to the power system 5, control that does not raise the system voltage V0 can be easily performed, and by preventing unnecessary disconnection, the power system 5 It is possible to obtain a power conversion device 3 that prevents abrupt fluctuations and enables effective utilization without wasting the power generation capacity of the DC power source 2.

Further, in the power conversion device 3 according to the present invention, the input unit 14 to which the DC power source 2 is connected, the output unit 15 connected to the system power, and the DC power input to the input unit 14 are converted into predetermined powers. A power conversion unit 10 that converts and outputs to the output unit 15 and a control device 13 that controls the output of the power conversion unit 10 are provided, and the control device 13 converts power according to the system voltage V0 of the power system 5. The output of the unit 10 is controlled, and when the system voltage V0 rises, the first output control is performed to control the output of the power conversion unit 10 so that the system voltage V0 does not exceed the second voltage value, and the first output is performed. After the control, the second output control for controlling the output of the power conversion unit 10 is performed so that the system voltage V0 does not exceed the fourth voltage value smaller than the second voltage value. Even with this configuration, in a grid interconnection system that converts DC power into predetermined power and outputs it to the power system 5, control that does not raise the system voltage V0 can be easily performed, and by preventing unnecessary disconnection, the power system 5 It is possible to obtain a power conversion device 3 that prevents abrupt fluctuations and enables effective utilization without wasting the power generation capacity of the DC power source 2.

Further, the present invention is a power conversion device 3 including a power conversion unit 10 that converts the DC power generated by the DC power source 2 into a predetermined power and outputs the DC power to the power system 5, and a predetermined system voltage V0 is predetermined. The output of the power conversion unit 10 is controlled by comparing with the voltage value of the above, and as the predetermined voltage value, the first voltage value which is the threshold for starting the output control operation and the output of the power conversion unit 10 are stopped. It has a third voltage value that serves as a threshold value and a second voltage value provided between the first voltage value and the third voltage value, and when the system voltage V0 reaches the first voltage value, a predetermined standby time T11 After the lapse, the count operation for executing the output control operation is started, and when the system voltage V0 reaches the second voltage value during the count operation, the system voltage V0 becomes the second voltage even if the elapsed time does not reach the standby time T11. It is characterized by including a control device 13 for starting the first output control operation OP1 that controls the output state of the power conversion unit 10 so as not to be higher than the value.

With this configuration, the counting operation is started when the system voltage V0 becomes higher than the first voltage value (first set voltage value V01), and the system voltage V0 becomes the second voltage value (second set setting) during the counting operation. When the voltage value V02) is reached, even if the elapsed time does not reach the standby time T11, the first output control operation OP1 for controlling the output state of the power conversion unit 10 is started, and the system voltage V0 becomes the second voltage value ( Since the voltage is not higher than the second set voltage value V02), the third voltage value (third set voltage value V03) that stops the output is not reached, and the output of the power conversion unit 10 does not stop. Will also get better. Therefore, in a grid interconnection system that converts DC power into predetermined power and outputs it to the power system 5, control that does not raise the system voltage V0 can be easily performed, and by preventing unnecessary disconnection, the power system 5 is steep. It is possible to obtain a power conversion device 3 that prevents fluctuations and enables effective utilization without wasting the power generation capacity of the DC power source 2.

Further, the control device 13 includes a voltage acquisition unit, a storage unit, a counting unit, a comparison unit, an output control unit, and an output stop unit, and the voltage acquisition unit is a power system 5 to which the power conversion unit 10 is connected. The storage unit acquires the voltage value of, and the storage unit includes a predetermined standby time T11 and a first voltage value and a second voltage value until a predetermined control operation for controlling the output of the power conversion unit 10 is started. The third voltage value and the third voltage value are stored, the counting unit performs a counting operation, counts the elapsed time from the time when the system voltage V0 reaches each voltage value, and the comparison unit performs the elapsed time and the predetermined predetermined time. The standby time T11 and the system voltage V0 are compared with each voltage value, the output control unit executes the output control operation of the power conversion unit 10, and the output stop unit reaches the third voltage value of the system voltage V0. It is characterized in that the output of the power conversion unit 10 is stopped when the voltage is changed. With this configuration, it is possible to obtain a power conversion device 3 capable of reliably executing an operation of comparing the system voltage V0 with each voltage value, an elapsed time counting operation, an output control operation, and the like.

Further, in the power conversion device 3 having the above configuration, the first output control operation OP1 is in the output state of the power conversion unit 10 so that the system voltage V0 does not exceed the second voltage value until at least the predetermined standby time T11 elapses. It is preferable to control. With this configuration, the system voltage V0 does not exceed the second voltage value (second settling voltage value V02) until the predetermined standby time T11 elapses, so that the output of the power conversion unit 10 is not stopped. , It becomes possible to continue power generation.

Further, in the power conversion device 3 having the above configuration, when it is detected that the system voltage V0 reaches the second voltage value during the counting operation, it is preferable to immediately start the first output control operation OP1. With this configuration, the output can be controlled so that the system voltage V0 does not exceed the second voltage value as soon as the system voltage V0 reaches the second voltage value (second set voltage value V02), so that the system voltage V0 becomes the second. It is possible to reliably prevent the third voltage value (third set voltage value V03) higher than the voltage value from being reached.

Further, in the power conversion device 3 having the above configuration, when it is detected that the system voltage V0 is higher than the first voltage value when the elapsed time reaches the predetermined standby time T11, the system voltage V0 sets the first voltage value. It is preferable to start the second output control operation OP2 that controls the output state of the power conversion unit 10 so as not to exceed it. With this configuration, by controlling the output so that the system voltage V0 does not exceed the first voltage value (first set voltage value V01), control that does not increase the system voltage V0 can be easily performed, and unnecessary disconnection can be achieved. By preventing this, abrupt fluctuations in the power system 5 can be prevented, and the power generation capacity of the DC power source 2 can be effectively utilized without wasting it.

Further, in the power conversion device 3 having the above configuration, a power purchase state in which power is received from the power system 5 and a power sale state in which predetermined power generated by the power conversion unit 10 is transmitted to the power system 5 It has a state recognition unit that recognizes a trading 0 state in which power is not received from the power system 5 and a predetermined power generated by the power conversion unit 10 is not transmitted to the power system 5, and the state recognition unit is used. It is preferable to perform the second output control operation OP2 when it is recognized that the power is sold. With this configuration, when the power is sold, that is, when at least a part of the DC power generated by the DC power source 2 is output to the power system 5, the system voltage V0 is performed by performing the second output control operation. It is possible to easily control the power system without increasing the power generation rate, prevent sudden fluctuations in the power system 5 by preventing unnecessary disconnection, and effectively utilize the power generation capacity of the DC power source 2 without wasting it.

Further, in the power conversion device 3 having the above configuration, the second output control operation OP2 may be performed even when it is recognized through the state recognition unit that the power is not in the selling state. By performing the second output control operation OP2 even when the power is not sold, it is possible to easily control the system voltage V0 so that the system voltage V0 is not increased when the power is sold, and unnecessary disconnection can be performed even when the power is not sold. By preventing this, it is possible to prevent sudden fluctuations in the power system 5.

Further, the present invention is a control method of a power conversion device 3 including a power conversion unit 10 that converts DC power generated by a DC power source 2 into a predetermined power and outputs the DC power to the power system 5. When the voltage V0 rises, the system voltage V0 changes after the first output control step that controls the output of the power conversion unit 10 so that the system voltage V0 does not become larger than the second voltage value, and the first output control step. It is a control method of the power conversion device 3 including a second output control step for controlling the output of the power conversion unit 10 so as not to be larger than the fourth voltage value smaller than the second voltage value.

With this configuration, in a grid interconnection system that converts DC power into predetermined power and outputs it to the power system 5, control that does not raise the system voltage V0 can be easily performed, and the power system can be prevented from unnecessary disconnection. It is possible to obtain a control method for the power conversion device 3 that prevents abrupt fluctuations in 5 and enables effective utilization without wasting the power generation capacity of the DC power source 2.

Further, in the control method of the power conversion device 3 having the above configuration, the second voltage value is smaller than the third voltage value which is the threshold value for stopping the output of the power conversion unit 10. With this configuration, the third voltage value (third set voltage value V03) that stops the output is not reached, the disconnection of the power conversion device 3 can be prevented, and the power system 5 suddenly fluctuates. Can be suppressed.

Further, the present invention is a control method of a power conversion device 3 including a power conversion unit 10 that converts the DC power generated by the DC power source 2 into a predetermined power and outputs the DC power to the power system 5, and the system voltage V0 and a predetermined value. The output of the power conversion unit 10 is controlled by comparing with the voltage value of the above, and as the predetermined voltage value, the first voltage value which is the threshold for starting the output control operation and the output of the power conversion unit 10 are stopped. A third voltage value that serves as a threshold value and a second voltage value provided between the first voltage value and the third voltage value are set in advance, and when the system voltage V0 reaches the first voltage value, a predetermined standby time is set. After the lapse, the count operation for executing the output control operation is started, and when the system voltage V0 reaches the second voltage value during the count operation, the system voltage V0 becomes the second voltage even if the elapsed time does not reach the standby time T11. It is characterized in that the first output control operation OP1 for controlling the output state of the power conversion unit 10 is started so that the value does not exceed the value.

With this configuration, even if the system voltage V0 reaches the first voltage value (first set voltage value V01), the system voltage V0 is the output of the power conversion unit 10 during the counting operation until the output control operation is started. Since it can be controlled so as not to be higher than the second voltage value (second set voltage value V02), which is lower than the third voltage value (third set voltage value V03), which is the threshold for stopping the DC power, the DC power is set to a predetermined power. In a grid interconnection system that converts and outputs to the power system 5, control that does not raise the grid voltage V0 can be easily performed, and by preventing unnecessary disconnection, sudden fluctuations in the power system can be prevented, and the DC power source 2 can be used. It is possible to obtain a control method for the power conversion device 3 that can be effectively utilized without wasting the power generation capacity.

Further, in the control method having the above configuration, when the system voltage V0 reaches the first voltage value, the counting operation is started, and when the system voltage V0 is higher than the first voltage value even after the elapsed time elapses from the predetermined standby time T11, The second output control operation OP2 that controls the output state of the power conversion unit 10 is performed so that the system voltage V0 does not exceed the first voltage value, and even if the predetermined standby time T11 is not reached during the counting operation, the system voltage When V0 reaches the second set voltage value V02, the first output control operation OP1 is immediately started, and after the count operation elapses the predetermined standby time T11, the second output control operation OP2 is started, and this second output control operation Among them, the second output control operation OP2 is stopped when the system voltage V0 becomes lower than the first voltage value. With this configuration, when the system voltage V0 reaches the first voltage value (first set voltage value V01), the count operation as an output control operation is started, and the system voltage V0 becomes the second voltage value (second set voltage value). When V02) is reached, the first output control operation OP1 for controlling the output of the power conversion unit 10 is started, and when the predetermined standby time T11 elapses, the system voltage V0 exceeds the first voltage value (first set voltage value V01). Since the output is controlled so as not to be generated, the power generation capacity of the DC power source 2 can be effectively utilized without wasting it.

Further, the present invention may be a power generation system 1 including a power conversion device 3 having the above configuration and a DC power source 2 for supplying power to the power conversion device 3. With this power generation system 1, control that does not raise the system voltage can be easily performed, sudden fluctuations in the power system can be prevented by preventing unnecessary disconnection, and the power generation capacity of the DC power source can be effectively utilized without wasting it. It is possible to obtain a power generation system 1 that enables it.

As described above, according to the present invention, in a grid interconnection system that converts DC power into a predetermined power and outputs it to a power system, control that does not raise the grid voltage can be easily performed, and unnecessary disconnection can be prevented. It is possible to obtain a power conversion device, a control method for the power conversion device, and a power generation system that can prevent sudden fluctuations in the power system and can be effectively used without wasting the power generation capacity of the DC power source.

Therefore, the power conversion device, the control method of the power conversion device, and the power generation system according to the present invention can be suitably used for a grid interconnection system provided with a DC power source and causing excess power to flow back to the power system. ..

1 Power generation system 2 DC power source 3 Power converter 4 Distribution board 5 Power system 6 Load 10 Power converter 11 1st power converter (DCDC converter)
12 Second power conversion unit (inverter unit)
13 Control device 14 Input unit 15 Output unit 16 Third power conversion unit 20 Storage battery V0 System voltage V01 First set voltage value (first voltage value)
V02 Second set voltage value (second voltage value)
V03 3rd set voltage value (3rd voltage value)
OP1 1st output control operation OP2 2nd output control operation T11 Standby time

Claims (12)

The input section to which the DC power source is connected and
The output unit connected to the power system and
A power conversion unit that converts the DC power input to the input unit into a predetermined power and outputs the power to the output unit.
A control device for controlling the output of the power conversion unit is provided.
The control device controls the output of the power conversion unit according to the system voltage of the power system.
When the system voltage rises, the first output control is performed to control the output of the power conversion unit so that the system voltage does not exceed the second voltage value, and the system voltage becomes the second voltage value after the first output control. A power conversion device characterized in that a second output control for controlling the output of the power conversion unit is performed so as not to exceed a fourth voltage value smaller than that. A power conversion device including a power conversion unit that converts DC power generated by a DC power source into predetermined power and outputs it to a power system.
The system voltage is compared with a predetermined voltage value to control the output of the power conversion unit and control the output.
As the predetermined voltage value, a first voltage value which is a threshold value for starting the output control operation, a third voltage value which is a threshold value for stopping the output of the power conversion unit, and the first voltage value and the third voltage value. It has a second voltage value provided between and
When the system voltage reaches the first voltage value, the counting operation for counting the elapsed time is started, and
After the elapsed time elapses, the output control operation is executed.
When the system voltage reaches the second voltage value during the counting operation, the output state of the power conversion unit is changed so that the system voltage does not become higher than the second voltage value even if the elapsed time does not reach the standby time. A power conversion device comprising a control device for initiating a first output control operation to be controlled. First output control operation, at least until the predetermined waiting time has elapsed according to claim 2, characterized by controlling the output state of the power conversion unit so that the system voltage does not exceed the second voltage value Power converter. The power conversion device according to claim 2 or 3 , wherein when the system voltage reaches the second voltage value during the counting operation, the first output control operation is immediately started. When it is detected that the system voltage is higher than the first voltage value when the elapsed time reaches the predetermined standby time, the output state of the power conversion unit is prevented so that the system voltage does not exceed the first voltage value. The power conversion device according to any one of claims 2 to 4, wherein a second output control operation for controlling the power is started. The control device further includes a power purchase state in which power is received from the power system, a power sale state in which predetermined power generated by the power conversion unit is transmitted to the power system, power reception, and power transmission. It has a state recognition unit that recognizes no buying and selling 0 state,
The power conversion device according to claim 5 , wherein the second output control operation is performed when the power is recognized as being sold through the state recognition unit. The power conversion device according to claim 6 , wherein the second output control operation is performed even when it is recognized through the state recognition unit that the power is not in the selling state. It is a control method of a power conversion device including a power conversion unit that converts DC power generated by a DC power source into predetermined power and outputs it to a power system.
A first output control step that controls the output of the power conversion unit so that the system voltage does not become larger than the second voltage value when the system voltage of the power system rises.
After the first output control step, a second output control step for controlling the output of the power conversion unit so that the system voltage does not become larger than the fourth voltage value smaller than the second voltage value is provided. How to control the power converter. The control method for a power conversion device according to claim 8 , wherein the second voltage value is smaller than the third voltage value, which is a threshold value for stopping the output of the power conversion unit. It is a control method of a power conversion device including a power conversion unit that converts DC power generated by a DC power source into predetermined power and outputs it to a power system.
The system voltage is compared with a predetermined voltage value to control the output of the power conversion unit and control the output.
The predetermined voltage value is provided between the first voltage value which is the threshold value for starting the output control operation, the third voltage value which is the threshold value for stopping the output, and the first voltage value and the third voltage value. Set the second voltage value in advance and
When the system voltage reaches the first voltage value, the counting operation for counting the elapsed time is started, and
After the elapsed time elapses, the output control operation is executed.
When the system voltage reaches the second voltage value during the counting operation, the output state of the power conversion unit is changed so that the system voltage does not become higher than the second voltage value even if the elapsed time does not reach the standby time. A control method for a power converter, which comprises initiating a first output control operation to be controlled. When the system voltage is higher than the first constant voltage value even after the elapsed time elapses, the second output controls the output state of the power conversion unit so that the system voltage does not exceed the first voltage value. Perform control operations
Even if the predetermined standby time is not reached during the counting operation, the first output control operation is immediately started when the system voltage reaches the second voltage value.
The second output control operation is started after the count operation has elapsed a predetermined standby time, and the second output control operation is stopped when the system voltage becomes lower than the first voltage value during the second output control operation. The control method of the power conversion device according to claim 10. A power generation system comprising the power conversion device according to any one of claims 1 to 7 and a DC power source for supplying power to the power conversion device.

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