JP4847771B2 - Grid-connected inverter device - Google Patents

Description

  The present invention determines an inverter output command value based on an inverter connected to a commercial system, a power supply device configured to output power supply power corresponding to the inverter output command value, and a target inverter output command value, The present invention relates to a grid-connected inverter device that includes an output control unit that operates an inverter and a power supply device according to an inverter output command value.

  As power supply devices connected to the commercial grid, power companies (general electric utilities) and specific-scale electric utilities, etc. installed as commercial power sources, individuals and groups other than electric utilities, There are distributed power supplies installed in various facilities. When power supply power is output from these power supply devices to a commercial system, the frequency of the power supply power is sent to match the reference frequency (50 Hz or 60 Hz). As a result, when the total power load by the power load device connected to the commercial system is balanced with the total power source power sent from the power unit, the frequency of power in the commercial system (hereinafter referred to as “commercial system frequency”) (Which may be described) is maintained at the reference frequency.

  In the commercial system as described above, when the total power source power and the total power load are not balanced, the commercial system frequency deviates from the reference frequency. Specifically, when the total power load is greater than the total power supply power, the commercial grid frequency is smaller than the reference frequency, and when the total power supply power is greater than the total power load, the commercial grid frequency is greater than the reference frequency. This causes a frequency deviation.

  Maintaining the commercial system frequency at the reference frequency to prevent the occurrence of frequency deviation as described above is necessary for the protection of the user's profit of the power, so the frequency deviation from the reference frequency of the commercial system frequency is acceptable. In order to be within the range, the electric power company performs frequency control such that the power source power output from the power plant is increased or decreased to balance the total power source power and the total power load (for example, see Non-Patent Document 1). .

Supervised by Ryuichi Yokoyama, “Liberalization of Electricity and Technology Development”, Tokyo Denki University Press, September 20, 2001, p. 133-135

  In commercial systems, power supply power is not only output from power plants maintained by power companies, but is also output from distributed power supply devices installed by individuals and organizations. The power supply power output from these distributed power supply devices to the commercial system tends to fluctuate due to the circumstances of the individual or organization installing them, and the output target value of the distributed power supply varies with the fluctuation of the commercial system frequency. It has been decided regardless. Since the commercial grid frequency is determined by the balance between the total power supply and the total power load in the commercial grid, the commercial grid frequency is likely to be disturbed if there are few generators that will correct this when the commercial grid frequency fluctuates. , There may be disadvantages for consumers and the entire grid.

  In addition, although the above-described distributed power supply apparatus may be connected to the commercial system via an inverter, the inverter only performs control to adjust the frequency of the output voltage to the frequency of the commercial system. In other words, the conventional inverter does not take measures to compensate for the frequency deviation of the commercial system frequency from the reference frequency.

  Furthermore, even if there is no frequency deviation from the reference frequency of the commercial system frequency, if the commercial system frequency changes, frequency control can be performed to pull back the change in order to stabilize the commercial system frequency. preferable.

  This invention is made | formed in view of said subject, The objective is to provide the grid connection inverter apparatus which can contribute to the frequency control of a commercial system frequency.

The characteristic configuration of the grid interconnection inverter device according to the present invention for achieving the above object is to determine an inverter output command value based on an inverter that links a power supply device to a commercial system and a target inverter output command value, A grid-connected inverter device comprising output control means for operating the inverter according to the inverter output command value,
Based on the monitoring result of the frequency monitoring means for monitoring the commercial system frequency in the commercial system, the output control means has the inverter output command value as the commercial system frequency increases when there is a change in the commercial system frequency. The inverter output command value is varied according to the setting relationship to reduce the value, and after operating the inverter, it is determined whether the actual inverter output value is equal to the target inverter output command value, and the actual inverter output value Is not equal to the target inverter output command value, the frequency change response control for operating the inverter is executed using the target inverter output command value as the inverter output command value. In this specification, “there is a change in the commercial system frequency” means that the commercial system frequency has changed from the current frequency (sometimes referred to as “set target frequency”).

According to the above characteristic configuration, the output control means varies the inverter output command value based on the monitoring result of the commercial system frequency monitored by the frequency monitoring means. As a result, since the total power source power and the total power load in the commercial system approach each other, the standard of the commercial system frequency in the commercial system that occurred when the total power source power and the total power load were deviated. Deviations from frequency will be compensated.
Therefore, it is possible to provide a grid-connected inverter device that can contribute to frequency control in a commercial system.
In addition, the output control means varies the inverter output command value in accordance with a setting relationship that decreases the inverter output command value as the commercial system frequency increases, so that the commercial system frequency increases (that is, the power supply power in the commercial system). When the total changes in a direction that increases relative to the total power load, the inverter output command value decreases, and when the commercial grid frequency decreases (that is, the total power supply power in the commercial grid decreases in a direction that decreases relative to the total power load) Then, the inverter output command value increases. Further, when the actual inverter output value is not equal to the target inverter output command value, the inverter output command value is changed so that the actual inverter output value is equal to the target inverter output value. As a result, even if the commercial system frequency changes, it is possible to contribute to stabilization of the commercial system frequency by performing frequency control that pulls back the change.
The output control means executes normal control for operating the inverter with the target inverter output command value as the inverter output command value when there is no change in the commercial system frequency.

Another characteristic configuration of the grid-connected inverter device according to the present invention includes: an inverter that links a power supply device to a commercial system; an inverter output command value that is determined based on a target inverter output command value; A grid-connected inverter device comprising output control means that operates according to an output command value,
The output control means has a change in the commercial system frequency based on the monitoring result of the frequency monitoring means for monitoring the commercial system frequency in the commercial system, and the frequency deviation from the reference frequency of the commercial system frequency is When the inverter output command value is fluctuated according to a setting relationship that decreases the inverter output command value as the commercial system frequency increases, the inverter output command value is operated, and the actual inverter output value is It is determined whether or not the fluctuation output value for reducing the frequency deviation is equal to the sum of the target inverter output command value and the actual inverter output value is the sum of the fluctuation output value and the target inverter output command value. Is not equal to the sum of the fluctuation output value and the target inverter output command value as the inverter output command value. In that it is configured to perform a frequency change and frequency deviation corresponding control to run the inverter.

  According to the above characteristic configuration, the output control means varies the inverter output command value based on the monitoring result of the commercial system frequency monitored by the frequency monitoring means. As a result, since the total power source power and the total power load in the commercial system approach each other, the standard of the commercial system frequency in the commercial system that occurred when the total power source power and the total power load were deviated. Deviations from frequency will be compensated.
  Therefore, it is possible to provide a grid-connected inverter device that can contribute to frequency control in a commercial system.
In addition, the output control means varies the inverter output command value in accordance with a setting relationship that decreases the inverter output command value as the commercial system frequency increases, so that the commercial system frequency increases (that is, the total power supply power in the commercial system). When the inverter output command value decreases and the commercial grid frequency decreases (that is, when the total power supply power in the commercial grid changes in a direction that decreases with respect to the total power load). ) The inverter output command value increases. Thereafter, when the actual inverter output value is not equal to the sum of the fluctuation output value and the target inverter output command value, the inverter is operated using the sum of the fluctuation output value and the target inverter output command value as the inverter output command value. As a result, even if the commercial system frequency changes, it is possible to contribute to the stabilization of the commercial system frequency by performing frequency control that pulls back the change, and to compensate for the generated frequency deviation. Frequency control can be performed to bring the commercial system frequency closer to the reference frequency.
The output control means normally operates the inverter with the target inverter output command value as the inverter output command value when there is no change in the commercial system frequency and there is no frequency deviation from the reference frequency of the commercial system frequency. Execute control.

Still another characteristic configuration of the grid-connected inverter device according to the present invention is that the output control means has a change in the commercial system frequency, and a frequency deviation from a reference frequency of the commercial system frequency is generated. When the commercial system frequency increases, the inverter output command value is changed according to a setting relationship that decreases the inverter output command value, and the inverter is operated, and then the actual inverter output value decreases the frequency deviation. To determine whether the actual output value is not equal to the sum of the fluctuation output value and the target inverter output command value. The inverter is operated using the sum of the fluctuation output value and the target inverter output command value as the inverter output command value. It performs frequency changes and frequency deviation corresponding control to,
When there is no change in the commercial system frequency and a frequency deviation from the reference frequency of the commercial system frequency occurs, the sum of the fluctuation output value for reducing the frequency deviation and the target inverter output command value , Using the inverter output command value, the frequency deviation corresponding control for operating the inverter is executed, and
When there is a change in the commercial system frequency and no frequency deviation from a reference frequency of the commercial system frequency occurs, the inverter is set according to a setting relationship in which the inverter output command value is decreased as the commercial system frequency increases. After the output command value is changed and the inverter is operated, it is determined whether the actual inverter output value is equal to the target inverter output command value, and the actual inverter output value is equal to the target inverter output command value. When they are not equal, the target inverter output command value is used as the inverter output command value, and frequency change response control for operating the inverter is executed.

  According to the above characteristic configuration, the output control means varies the inverter output command value based on the monitoring result of the commercial system frequency monitored by the frequency monitoring means. As a result, since the total power source power and the total power load in the commercial system approach each other, the standard of the commercial system frequency in the commercial system that occurred when the total power source power and the total power load were deviated. Deviations from frequency will be compensated.
  Therefore, it is possible to provide a grid-connected inverter device that can contribute to frequency control in a commercial system.
In addition, in the same way as the operations and effects of the above characteristic configuration, when the commercial system frequency changes and a frequency deviation from the reference frequency of the commercial system frequency occurs, a frequency that pulls back the change in the commercial system frequency. By performing the control, it is possible to contribute to stabilization of the commercial system frequency, and it is possible to bring the commercial system frequency closer to the reference frequency by performing frequency control so as to compensate for the generated frequency deviation.
Further, when the commercial system frequency does not change and a frequency deviation from the reference frequency of the commercial system frequency occurs, frequency control is performed so as to compensate for the generated frequency deviation. The frequency can be brought close to the reference frequency.
Furthermore, when the commercial system frequency changes and no frequency deviation from the reference frequency of the commercial system frequency occurs, frequency control is performed to pull back the change in the commercial system frequency to stabilize the commercial system frequency. Can contribute.

<First Embodiment>
Below, the grid connection inverter apparatus 10 of 1st Embodiment of this invention is demonstrated with reference to drawings.
In the schematic diagram of the commercial system shown in FIG. 1, a power plant 30 and power load devices 2 and 40 that consume power in the commercial system 50 are connected to the commercial system 50. Further, the power supply device 1 is connected to the commercial system 50 via the inverter 11 of the grid interconnection inverter device 10. Note that a larger number of power supply devices 1, power plants 30, power load devices 2, 40, and the like may be connected to the commercial system 50.

  The power plant 30 connected to the commercial system 50 is, for example, a thermal power plant installed by an electric power company (general electric utility) or the like. Some of such power plants 30 have a frequency deviation that occurs when the commercial system frequency deviates from the reference frequency (50 Hz or 60 Hz), so that its output is immediately changed to compensate for the frequency deviation. An operation (a so-called governor characteristic) is performed. For example, when the commercial grid frequency is lower than the reference frequency (that is, when the total power supply power in the commercial grid 50 is smaller than the total power load), the power output from the power plant 30 to the commercial grid 50 is increased. Further, when the commercial system frequency increases from the reference frequency (that is, when the total power supply power in the commercial system 50 becomes larger than the total power load), the power output from the power plant 30 to the commercial system 50 is decreased.

  The power supply device 1 is controlled by the grid-connected inverter device 10 so as to output power supply power corresponding to the inverter output command value, and the generated power is at least one of the power load device 2 and the commercial system 50 via the inverter 11. To be supplied. Various devices can be used as the power supply device 1, for example, a power generation device such as a fuel cell or a gas engine power generation device, a storage battery, or the like.

The grid-connected inverter device 10 determines the inverter output command value based on the inverter 11 that links the power supply device 1 to the commercial system 50 and the target inverter output command value, and the inverter 11 receives the inverter output command value. Output control means 13 that operates according to the above.
Further, the grid interconnection inverter device 10 is provided with frequency monitoring means 12 for monitoring the commercial system frequency in the commercial system 50, and the output control means 13 is configured to output the inverter output command based on the monitoring result of the frequency monitoring means 12. It is configured to vary the value. Furthermore, the grid-connected inverter device 10 has a function of measuring an actual inverter output value from the inverter 11 to the commercial system 50 (may be described as “actual inverter output value”).

  As described above, the output control means 13 included in the grid interconnection inverter device 10 is configured to vary the inverter output command value based on the monitoring result of the frequency monitoring means 12. Specifically, based on the monitoring result of the frequency monitoring unit 12, the output control unit 13 performs any of normal control, frequency change and frequency deviation correspondence control, frequency deviation correspondence control, and frequency change correspondence control, which will be described later. Execute.

  The output control means 13 indicates that the monitoring result of the frequency monitoring means 12 has no change in the commercial system frequency (as will be described later, the commercial system frequency has not changed from the set target frequency that is the current commercial system frequency). When the frequency deviation from the reference frequency of the commercial system frequency does not occur, normal control for operating the inverter 11 is executed with the target inverter output command value as the inverter output command value.

  Further, when the monitoring result of the frequency monitoring unit 12 indicates that the commercial system frequency has changed and the frequency deviation from the reference frequency of the commercial system frequency has occurred, the output control unit 13 After the inverter is operated by changing the inverter output command value according to the setting relationship (corresponding to the “droop characteristic” described later with reference to FIG. 7) that decreases the inverter output command value as the system frequency increases, the actual inverter It is determined whether the output value is equal to the sum of the fluctuation output value for reducing the frequency deviation and the target inverter output command value, and the actual inverter output value is the difference between the fluctuation output value and the target inverter output command value. If it is not equal to the sum, the inverter 11 is operated with the sum of the fluctuation output value and the target inverter output command value as the inverter output command value. Performing frequency changes and frequency deviation corresponding control.

The fluctuation output value is derived based on the frequency bias characteristic shown in FIG. In the frequency bias characteristic illustrated in FIG. 8, the fluctuation output value corresponding to the frequency deviation is such that the frequency deviation is between the setting lower limit value: Δf _L and the setting upper limit value: Δf _H. It is determined in a relationship that monotonously decreases at a predetermined rate of change (C1, C2) as it increases. Further, in this frequency bias characteristic, dead band widths A1 and A2 of frequency deviation are set between −Δf _L and Δf _L , and an upper limit width B2 and a lower limit width B1 of the fluctuation output value are set.
As a result, when a positive frequency deviation occurs (that is, when the total power supply power in the commercial system 50 is larger than the total power load), the inverter output value of the inverter 11 is reduced to reduce the power supply in the commercial system 50. In order to contribute to reducing the total power, the variable output value is set to zero or a negative value. When a negative frequency deviation occurs (that is, when the total power source power in the commercial system 50 is smaller than the total power load), the inverter output value of the inverter 11 is increased to increase the power source power in the commercial system 50. In order to contribute to increasing the total, the variable output value is set to zero or a positive value.

  Further, the output control means 13 indicates that the monitoring result of the frequency monitoring means 12 indicates that there is no change in the commercial system frequency and that a frequency deviation from the reference frequency of the commercial system frequency has occurred. Frequency deviation corresponding control for operating the inverter is executed with the sum of the fluctuation output value for reducing the frequency deviation and the target inverter output command value as the inverter output command value.

  Further, when the monitoring result of the frequency monitoring unit 12 indicates that the commercial system frequency has changed and the frequency deviation from the reference frequency of the commercial system frequency has not occurred, the output control unit 13 After operating the inverter by changing the inverter output command value according to the setting relationship that decreases the inverter output command value as the system frequency increases, determine whether the actual inverter output value is equal to the target inverter output command value. When the actual inverter output value is not equal to the target inverter output command value, the frequency change corresponding control for operating the inverter 11 is executed using the target inverter output command value as the inverter output command value.

Next, referring to the main control flow shown in FIG. 2, the sub-control flow shown in FIGS. 3 to 5 and the graph of the transition of the commercial system frequency and the inverter output value shown in FIG. 6, the grid interconnection inverter of the present invention. The operation of the apparatus will be described.
As shown in the main control flow of FIG. 2, in step S1, the output control means 13 determines whether or not the commercial system frequency has changed from the set target frequency based on the monitoring result of the frequency monitoring means 12, that is, the commercial system frequency. It is determined whether or not there is a change. When the commercial system frequency has changed from the set target frequency, the process proceeds to step S2, and when the commercial system frequency has not changed from the set target frequency, the process proceeds to step S3.
In step S <b> 2, the output control unit 13 determines whether or not a frequency deviation from the reference frequency (60 Hz in the present embodiment) of the commercial system frequency has occurred based on the monitoring result of the frequency monitoring unit 12. Then, the output control means 13 proceeds to step S10 when the frequency deviation occurs, executes the frequency and frequency deviation correspondence control described later with reference to FIG. 3, and performs the step when the frequency deviation does not occur. Shifting to S20, the frequency change control described later with reference to FIG. 4 is executed.

  In step S3, the output control means 13 determines whether or not a frequency deviation from the reference frequency of the commercial system frequency has occurred based on the monitoring result of the frequency monitoring means 12. Then, the output control means 13 shifts to step S30 when the frequency deviation occurs, executes frequency deviation corresponding control described later with reference to FIG. 5, and proceeds to step S4 when the frequency deviation does not occur. Then, the inverter 11 is operated with the target inverter output command value as the inverter output command value (normal control).

  In the specific example shown in FIG. 6, the target inverter output command value is maintained at P1, and the inverter output command value and the actual inverter output value correspond to changes in the commercial system frequency from time t1 to time t6. P1 → P2 → P3 → P4 → P1.

The frequency change and frequency deviation corresponding control (step S10) executed when there is a change in the commercial system frequency and a frequency deviation from the reference frequency of the commercial system frequency is generated (step S10) will be described below. This will be described with reference to the control flow.
First, the transition of the commercial system frequency up to time t3 shown in FIG. 6 and the transition of the actual inverter output value (inverter output command value) will be described.
Until time t1 in FIG. 6, as in step S4 described above, the output control means 13 operates the inverter 11 using the target inverter output command value: P1 as the inverter output command value. Further, the inverter 11 controls the power output of the power supply device 1 in order to achieve the inverter output command value.
Then, in step S11 of FIG. 3, the output control unit 13 changes the commercial system frequency from f1 (reference frequency: 60 Hz), which is the set target frequency at this time, to f2, based on the drooping characteristic A shown in FIG. Then, the inverter output command value: P2 corresponding to the commercial system frequency after change: f2 is derived. This drooping characteristic A is set by a straight line with a predetermined slope passing through the set target frequency: f1 and the inverter output command value: P1, and a setting relationship is defined in which the inverter output command value decreases as the commercial system frequency increases. It is. Specifically, when the commercial system frequency is maintained at the set target frequency: f1, the inverter output command value is the target inverter output command value: P1, but when the commercial system frequency changes to f2, the output control means 13 Derives the inverter output command value as P2 based on the drooping characteristic A. In step S12, the output control means 13 controls the operation of the inverter 11 according to the inverter output command value: P2. Further, in step S13, the output control means 13 thereafter sets the changed commercial system frequency: f2 to the set target frequency.
In step S14, the output control means 13 derives a fluctuation output value: ΔP for reducing the frequency deviation: (f2-60) Hz based on the frequency bias characteristic shown in FIG.

  As the output control means 13 performs the control as described above, after the commercial system frequency changes from f1 to f2 at time t1, as shown in FIG. 6, the inverter output command value changes from P1 to P2, The inverter output value also becomes P2 at time t2.

  Next, in step S15, the output control means 13 determines whether or not the actual inverter output value is equal to the sum of the target inverter output command value: P1 and the fluctuation output value: ΔP: P3. Then, when the actual inverter output value is not equal to the sum of the target inverter output command value: P1 and the fluctuation output value: ΔP: P3, the process proceeds to step S16. On the other hand, when the actual inverter output value is equal to the sum P3 of the target inverter output command value: P1 and the fluctuation output value: ΔP, the main control flow of FIG. 2 is performed without changing the inverter output command value. Return.

In step S16, the output control means 13 determines the sum P3 of the target inverter output command value: P1 and the fluctuation output value: ΔP as the inverter output command value. In step S17, the output control means 13 operates the inverter 11 according to the inverter output command value P3 determined in step S16.
In step S18, the output control means 13 changes and sets the drooping characteristic to the drooping characteristic B that passes through the set target frequency: f2 and the inverter output command value: P3 at that time.

  When the output control means 13 performs the control as described above, after the actual inverter output value becomes P2 at time t2 shown in FIG. 6, the inverter output command value changes from P2 to P3, and the actual inverter output The value also becomes P3 at time t3.

Next, the transition of the commercial system frequency from time t3 to time t4 in FIG. 6 and the transition of the actual inverter output value (inverter output command value) will be described.
When the sub-control flow of the frequency change and frequency deviation corresponding control shown in FIG. 3 is completed at time t3 in FIG. 6, there is no change in the commercial system frequency and a frequency deviation from the reference frequency of the commercial system frequency occurs. Therefore, the output control means 13 executes frequency deviation corresponding control (sub control flow shown in FIG. 5) in step S30 (step S1, step S3, step S30 in FIG. 2).

  In step S31 of FIG. 5, the output control means 13 derives a fluctuation output value: ΔP for reducing the frequency deviation: (f2-60) Hz based on the frequency bias characteristic shown in FIG. Next, in step S32, the output control means 13 determines whether or not the actual inverter output value is equal to the target inverter output command value: P1 and the fluctuation output value: ΔP: P3. Then, when the actual inverter output value is not equal to the target inverter output command value: P1 and the sum of the fluctuation output value: ΔP: P3, the process proceeds to step S33. On the other hand, when the actual inverter output value is equal to the sum of the target inverter output command value: P1 and the fluctuation output value: ΔP: P3, the main control flow of FIG. Return.

  In step S33, the output control means 13 determines the sum of the target inverter output command value: P1 and the fluctuation output value: ΔP: P3 as the inverter output command value. In step S34, the output control means 13 operates the inverter 11 according to the inverter output command value P3 determined in step S33.

  When the output control means 13 performs the control as described above, the inverter output command value is maintained at P3 from time t3 to time t4 shown in FIG. 6, and the actual inverter output value is also maintained at P3. Become.

Next, the transition of the commercial system frequency from time t4 to time t6 in FIG. 6 and the transition of the actual inverter output value (inverter output command value) will be described.
When time t4 in FIG. 6 is reached, since there is a change in the commercial system frequency and no frequency deviation from the reference frequency of the commercial system frequency has occurred, the output control means 13 performs frequency change control (step S20). 4 is executed (step S1, step S2, step S20 in FIG. 2).

  In step S21 of FIG. 4, when the commercial system frequency changes from f2 (set target frequency at this time) to f1, the output control means 13 changes the commercial system frequency after the change based on the drooping characteristic B shown in FIG. An inverter output command value P4 corresponding to f1 is derived. This drooping characteristic B is set by a straight line passing through the set target frequency: f2 and the inverter output command value: P3 at this time, and a setting relationship is defined in which the inverter output command value decreases as the commercial system frequency increases. It is. In step S22, the output control means 13 controls the operation of the inverter 11 according to the inverter output command value: P4. Further, in step S23, the output control means 13 sets the changed commercial system frequency: f1 to the set target frequency thereafter.

  When the output control means 13 performs the above control, as shown in FIG. 6, after the commercial system frequency changes from f2 to f1 at time t4, the inverter output command value changes from P3 to P4. The inverter output value also becomes P4 at time t5.

  Next, in step S24, the output control means 13 determines whether or not the actual inverter output value is equal to the target inverter output command value: P1. Then, when the actual inverter output value is not equal to the target inverter output command value: P1, the process proceeds to step S25. On the other hand, when the actual inverter output value is equal to the target inverter output command value: P1, the process returns to the main control flow of FIG. 2 without changing the inverter output command value.

In step S25, the output control means 13 determines the target inverter output command value: P1 as the inverter output command value. In step S26, the output control means 13 operates the inverter 11 according to the inverter output command value P1 determined in step S25.
In step S27, the output control means 13 changes and sets the drooping characteristic to a drooping characteristic A that passes through the set target frequency: f1 and the inverter output command value: P1 at that time.

  When the output control means 13 performs the control as described above, after the actual inverter output value becomes P4 at time t5 shown in FIG. 6, the inverter output command value changes from P4 to P1, and the actual inverter output The value also becomes P1 at time t6.

< Other embodiments>
As shown in the main control flow of FIG. 9, the grid-connected inverter device 10 of this embodiment relative to the first embodiment determines whether or not a frequency deviation has occurred (step S3), and the frequency monitoring means 12 When the monitoring result shows that there is a frequency deviation from the reference frequency of the commercial grid frequency, the sum of the fluctuation output value for reducing the frequency deviation and the target inverter output command value is the inverter output command. As a value, frequency deviation corresponding control for operating the inverter 11 is executed (step S30). That is, in this embodiment, the output control means 13 performs control irrespective of whether there is a change in the commercial system frequency (whether the commercial system frequency is different from the set target frequency). Below, although the grid connection inverter apparatus 10 of this embodiment is demonstrated, description is abbreviate | omitted about the structure similar to 1st Embodiment.

Next, the operation of this grid-connected inverter device will be described with reference to the main control flow shown in FIG. 9, the sub-control flow shown in FIG. 5, and the graph of the transition of the commercial grid frequency and inverter output value shown in FIG. To do.

  As shown in the main control flow of FIG. 9, in step S3, the output control means 13 determines whether or not a frequency deviation from the reference frequency of the commercial system frequency has occurred based on the monitoring result of the frequency monitoring means 12. To do. Then, the output control means 13 shifts to step S30 when the frequency deviation occurs, executes frequency deviation corresponding control described later with reference to FIG. 5, and proceeds to step S4 when the frequency deviation does not occur. Then, the inverter 11 is operated with the target inverter output command value as the inverter output command value (normal control).

  When the commercial system frequency changes from f1 (reference frequency 60 Hz) to f2 at time t10 shown in FIG. 10 and a frequency deviation from the reference frequency of the commercial system frequency occurs, output control means in step S31 of FIG. 13 derives the fluctuation output value: ΔP for reducing the frequency deviation: (f2-60) Hz based on the frequency bias characteristic shown in FIG. Next, in step S32, the output control means 13 determines whether or not the actual inverter output value is equal to the target inverter output command value: P1 and the fluctuation output value: ΔP: P3. Then, when the actual inverter output value is not equal to the target inverter output command value: P1 and the sum of the fluctuation output value: ΔP: P3, the process proceeds to step S33. On the other hand, when the actual inverter output value is equal to the sum of the target inverter output command value: P1 and the fluctuation output value: ΔP: P3, the main control flow of FIG. 9 is performed without changing the inverter output command value. Return.

  In step S33, the output control means 13 determines the sum of the target inverter output command value: P1 and the fluctuation output value: ΔP: P3 as the inverter output command value. In step S34, the output control means 13 operates the inverter 11 according to the inverter output command value P3 determined in step S33. When the output control means 13 performs the control as described above, the inverter output command value is set to P3 from time t11 shown in FIG. 10, and the actual inverter output value is also changed from P1 to P3 between time t11 and time t12. Will fluctuate.

While the frequency deviation is occurring, the inverter output command value is maintained at P3, and the actual inverter output value is also maintained at P3.
On the other hand, when the commercial system frequency changes from f2 to f1 at time t13 shown in FIG. 10 and the frequency deviation from the reference frequency of the commercial system frequency disappears, step S4 of the main control flow shown in FIG. 9 is executed. Will be. That is, the output control means 13 sets the target inverter output command value: P1 as the inverter output command value, and operates the inverter 11 according to the inverter output command value: P1. As a result, as shown in FIG. 10, the actual inverter output value also changes from P3 to P1 between time t14 and time t15.

Second Embodiment
As shown in the main control flow of FIG. 11, the grid-connected inverter device 10 of the second embodiment determines whether or not there is a change in the commercial system frequency (that is, whether or not the commercial system frequency is different from the set target frequency). When the output control means 13 shows that the monitoring result of the frequency monitoring means 12 shows a change in the commercial system frequency, the inverter output command value is increased as the commercial system frequency increases. After operating the inverter by changing the inverter output command value according to the setting relationship to be reduced, determine whether the actual inverter output value is equal to the target inverter output command value, and the actual inverter output value is the target inverter output command When it is not equal to the value, the frequency at which the inverter 11 is operated with the target inverter output command value as the inverter output command value Executing a reduction corresponding control (step S20). That is, in this embodiment, the output control means 13 performs control irrespective of the frequency deviation from the reference frequency of the commercial system frequency.
Below, although the grid connection inverter apparatus 10 of 2nd Embodiment is demonstrated, description is abbreviate | omitted about the structure similar to 1st Embodiment.

  Next, referring to the main control flow shown in FIG. 11, the sub-control flow shown in FIG. 4, and the graph of the transition of the commercial system frequency and the inverter output value shown in FIG. 12, the operation of the grid-connected inverter device of the present invention. Will be described.

  As shown in the main control flow of FIG. 11, in step S1, the output control means 13 determines whether or not the commercial system frequency has changed from the set target frequency, that is, whether or not the commercial system frequency has changed. Then, when the commercial system frequency has changed from the set target frequency, the routine proceeds to step S20, where frequency change control described later with reference to FIG. 4 is executed, and when no frequency change has occurred, the routine proceeds to step S4. Then, the inverter 11 is operated with the target inverter output command value as the inverter output command value (normal control).

  When the commercial system frequency changes from f1 to f2 at time t21 shown in FIG. 12, in step S21 of FIG. 4, the output control means 13 changes the commercial system frequency to f2 after the change based on the drooping characteristic A shown in FIG. A corresponding inverter output command value P2 is derived. This drooping characteristic A is set by a straight line passing through the set target frequency: f1 and the inverter output command value: P1 at this time, and a setting relationship is defined in which the inverter output command value decreases as the commercial system frequency increases. It is. In step S22, the output control means 13 controls the operation of the inverter 11 according to the inverter output command value: P2. Further, in step S23, the output control means 13 sets the changed commercial system frequency: f2 to the set target frequency thereafter.

  When the output control means 13 performs the control as described above, after the commercial system frequency changes from f1 to f2 at time t21 as shown in FIG. 12, the inverter output command value changes from P1 to P2, The inverter output value also becomes P2 at time t22.

  Next, in step S24, the output control means 13 determines whether or not the actual inverter output value is equal to the target inverter output command value: P1. Then, when the actual inverter output value is not equal to the target inverter output command value: P1, the process proceeds to step S25. On the other hand, when the actual inverter output value is equal to the target inverter output command value: P1, the process returns to the main control flow of FIG. 11 without changing the inverter output command value.

In step S25, the output control means 13 determines the target inverter output command value: P1 as the inverter output command value. In step S26, the output control means 13 operates the inverter 11 according to the inverter output command value P1 determined in step S25.
In step S27, the output control means 13 changes and sets the drooping characteristic to the drooping characteristic C that passes through the set target frequency: f2 and the inverter output command value: P1 at that time.

  When the output control means 13 performs the control as described above, after the actual inverter output value becomes P2 at time t22 shown in FIG. 12, the inverter output command value changes from P2 to P1, and the actual inverter output The value also becomes P1 at time t23.

  Thereafter, when the commercial system frequency changes from f2 (set target frequency at this time) to f1 at time t24 shown in FIG. 12, the output control means 13 in step S21 of FIG. 4 is based on the drooping characteristic C shown in FIG. Then, the inverter output command value: P5 corresponding to the commercial system frequency after change: f1 is derived. This drooping characteristic C is set by a straight line passing through the set target frequency: f2 and the inverter output command value: P1 at this time, and a setting relationship is defined in which the inverter output command value decreases as the commercial system frequency increases. It is. In step S22, the output control means 13 controls the operation of the inverter 11 according to the inverter output command value: P5. Further, in step S23, the output control means 13 sets the changed commercial system frequency: f1 to the set target frequency thereafter.

  When the output control means 13 performs the control as described above, after the commercial system frequency changes from f2 to f1 at time t24 as shown in FIG. 12, the inverter output command value changes from P1 to P5. The inverter output value also becomes P5 at time t25.

  Next, in step S24, the output control means 13 determines whether or not the actual inverter output value is equal to the target inverter output command value: P1. Then, when the actual inverter output value is not equal to the target inverter output command value: P1, the process proceeds to step S25. On the other hand, when the actual inverter output value is equal to the target inverter output command value: P1, the process returns to the main control flow of FIG. 11 without changing the inverter output command value.

In step S25, the output control means 13 determines the target inverter output command value: P1 as the inverter output command value. In step S26, the output control means 13 operates the inverter 11 according to the inverter output command value P1 determined in step S25.
In step S27, the output control means 13 changes and sets the drooping characteristic to a drooping characteristic A that passes through the set target frequency: f1 and the inverter output command value: P1 at that time.

  When the output control means 13 performs the control as described above, after the actual inverter output value becomes P5 at time t25 shown in FIG. 12, the inverter output command value changes from P5 to P1, and the actual inverter output The value also becomes P1 at time t26.

< Other embodiments>
As shown in the control flow of FIG. 13, the grid-connected inverter device 10 of this embodiment with respect to the embodiments that have been described so far determines whether or not the commercial system frequency has changed (step S41). When the commercial system frequency obtained as a monitoring result of the monitoring unit 12 changes, the frequency change corresponding control is performed to change the inverter output command value according to the setting relationship in which the inverter output command value is decreased as the commercial system frequency increases. Has been. That is, in this embodiment, the output control means 13 controls the inverter 11 based on the inverter output command value as a function of the commercial system frequency shown in FIG. Therefore, in the present embodiment, there is no target inverter output command value as in the first to second embodiments.

Next, the operation of this grid-connected inverter device will be described with reference to the control flow shown in FIG.
As shown in the control flow of FIG. 13, in step S41, the output control means 13 determines whether or not there is a change in the commercial system frequency. Then, when there is a change in the commercial system frequency, the output control means 13 proceeds to step S42, and in step S42, based on the drooping characteristics shown in FIG. 7, the inverter output command value corresponding to the changed commercial system frequency. Is derived. Next, in step S43, the output control means 13 operates the inverter 11 according to the derived inverter output command value.

<Another embodiment>
<1>
In the above embodiment, the grid interconnection inverter device 10 including the inverter 11 and the frequency monitoring unit 12 and the output control unit 13 has been described. However, the frequency monitoring unit 12 and the output control unit 13 are separated from the inverter 11. The provided inverter control device 20 can also be configured. For example, as shown in the schematic diagram of the commercial system in FIG. 14, the inverter control device 20 includes a frequency monitoring unit 12 that monitors the commercial system frequency in the commercial system 50, and an inverter output command value based on the target inverter output command value. And an output control means 13 for operating the inverter 11 and the power supply device 1 according to the inverter output command value. The functions of the frequency monitoring unit 12 and the output control unit 13 are the same as those in the above embodiment.

<2>
In the above embodiment, the drooping characteristic and the frequency bias characteristic have been described with reference to FIGS. 7 and 8. However, the slope (change rate) of the straight line representing the drooping characteristic and the dead band width representing the frequency bias characteristic: A1, A2, upper limit Width: B2 and lower limit width: B1, change rate: C1, C2 can be changed as appropriate.

  The grid-connected inverter device of the present invention can be used to stabilize the commercial system frequency in the commercial system near the reference frequency.

Schematic diagram of commercial system Main control flow of the first embodiment Sub-control flow of the first embodiment Sub-control flow of the first embodiment Sub-control flow of the first embodiment The graph which shows transition of the commercial system frequency of 1st Embodiment, and an actual inverter output value Graph showing drooping characteristics Graph showing frequency bias characteristics Main control flow of other embodiment The graph which shows transition of commercial system frequency of other embodiments, and actual inverter output value Main control flow of the second embodiment The graph which shows transition of the commercial system frequency of 2nd Embodiment, and an actual inverter output value Control flow of other embodiments Schematic diagram of commercial system

DESCRIPTION OF SYMBOLS 1 Power supply device 2 Electric power load apparatus 10 Grid connection inverter apparatus 11 Inverter 12 Frequency monitoring means 13 Output control means 50 Commercial system

Claims (3)

A grid connection comprising: an inverter that links a power supply device to a commercial system; and output control means that determines an inverter output command value based on a target inverter output command value and operates the inverter according to the inverter output command value System inverter device,
Based on the monitoring result of the frequency monitoring means for monitoring the commercial system frequency in the commercial system, the output control means has the inverter output command value as the commercial system frequency increases when there is a change in the commercial system frequency. The inverter output command value is varied according to the setting relationship to reduce the value, and after operating the inverter, it is determined whether the actual inverter output value is equal to the target inverter output command value, and the actual inverter output value Is not equal to the target inverter output command value, the system-connected inverter device is configured to execute frequency change corresponding control for operating the inverter, using the target inverter output command value as the inverter output command value. . A grid connection comprising: an inverter that links a power supply device to a commercial system; and output control means that determines an inverter output command value based on a target inverter output command value and operates the inverter according to the inverter output command value System inverter device,
The output control means has a change in the commercial system frequency based on the monitoring result of the frequency monitoring means for monitoring the commercial system frequency in the commercial system, and the frequency deviation from the reference frequency of the commercial system frequency is When the inverter output command value is fluctuated according to a setting relationship that decreases the inverter output command value as the commercial system frequency increases, the inverter output command value is operated, and the actual inverter output value is It is determined whether or not the fluctuation output value for reducing the frequency deviation is equal to the sum of the target inverter output command value and the actual inverter output value is the sum of the fluctuation output value and the target inverter output command value. Is not equal to the sum of the fluctuation output value and the target inverter output command value as the inverter output command value. System interconnection inverter device configured to perform a frequency change and frequency deviation corresponding control to run the inverter. A grid connection comprising: an inverter that links a power supply device to a commercial system; and output control means that determines an inverter output command value based on a target inverter output command value and operates the inverter according to the inverter output command value System inverter device,
The output control means has a change in the commercial system frequency based on the monitoring result of the frequency monitoring means for monitoring the commercial system frequency in the commercial system, and the frequency deviation from the reference frequency of the commercial system frequency is When the inverter output command value is fluctuated according to a setting relationship that decreases the inverter output command value as the commercial system frequency increases, the inverter output command value is operated, and the actual inverter output value is It is determined whether or not the fluctuation output value for reducing the frequency deviation is equal to the sum of the target inverter output command value and the actual inverter output value is the sum of the fluctuation output value and the target inverter output command value. Is not equal to the sum of the fluctuation output value and the target inverter output command value as the inverter output command value. It performs frequency changes and frequency deviation corresponding control to run the inverter,
  When there is no change in the commercial system frequency and a frequency deviation from the reference frequency of the commercial system frequency occurs, the sum of the fluctuation output value for reducing the frequency deviation and the target inverter output command value , Using the inverter output command value, the frequency deviation corresponding control for operating the inverter is executed, and
  When there is a change in the commercial system frequency and no frequency deviation from a reference frequency of the commercial system frequency occurs, the inverter is set according to a setting relationship in which the inverter output command value is decreased as the commercial system frequency increases. After the output command value is changed and the inverter is operated, it is determined whether the actual inverter output value is equal to the target inverter output command value, and the actual inverter output value is equal to the target inverter output command value. When they are not equal, a grid-connected inverter device configured to execute frequency change control for operating the inverter with the target inverter output command value as the inverter output command value.

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