JP2015180123A - Controller, power converter, power supply system, program, and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress harmful effect by reduction in accuracy of isolated operation detection caused by interference between reactive power control for detecting isolated operation and reactive power control for suppressing voltage rise.SOLUTION: A controller comprises: a first reactive power variation derivation unit for deriving, depending on a frequency deviation of an AC power supply, a variation in first reactive power that is phase advancing reactive power or phase lagging reactive power to be output by a power conversion unit interconnecting with the AC power supply; a second reactive power variation derivation unit for deriving a variation in second reactive power that is phase advancing reactive power to be output from the power conversion unit to suppress rise of voltage at an interconnection point between the power conversion unit and the AC power supply; and a power output control unit for making the power conversion unit stop outputting power when the variation in the second reactive power interferes with the variation in the first reactive power.

Description

  The present invention relates to a control device, a power conversion device, a power supply system, a program, and a control method.

Patent Document 1 discloses an isolated operation detection device that changes the reactive power supplied to the system power supply side according to the frequency deviation of the system power supply and detects the isolated operation of the power conditioner based on the frequency fluctuation of the reactive power. ing. Patent Document 2 discloses a distributed power supply interconnection system that suppresses an increase in voltage at an interconnection point with a distribution system by increasing reactive power.
Patent Document 1 Japanese Unexamined Patent Application Publication No. 2008-54366 Patent Document 2 Japanese Unexamined Patent Application Publication No. 2010-166759

  Interference between the reactive power control for detecting the isolated operation and the reactive power control for suppressing the voltage rise may reduce the accuracy of the isolated operation detection.

  In the control device according to one aspect of the present invention, a change in the first reactive power, which is a phase reactive power or a phase reactive power to be output by the power conversion unit linked to the AC power supply, according to the frequency deviation of the AC power supply. A first reactive power change amount deriving unit for deriving an amount, and a second reactive power that is a phase reactive power to be output from the power conversion unit in order to suppress an increase in voltage at a connection point between the power conversion unit and the AC power source A second reactive power variation deriving unit for deriving a power variation, and a power output for stopping output of power by the power conversion unit when the first reactive power variation is interfered by the second reactive power variation And a control unit.

  In the control device, the power output control unit is configured such that the amount of change in the first reactive power is the amount of change in the fast reactive power that changes in the direction in which the first reactive power increases, and the amount of change in the second reactive power is negative. If it is the value of, power output by the power conversion unit may be stopped.

  In the control device, the power output control unit may stop the output of the power by the power conversion unit when the first reactive power is the lagging reactive power and the change amount of the second reactive power is a positive value. .

  The power converter device which concerns on 1 aspect of this invention is provided with the said control apparatus and the power converter part which converts the direct current from direct-current power supply into alternating current, and is connected with alternating current power supply.

  The power supply system which concerns on 1 aspect of this invention is provided with the said power converter device and DC power supply.

  The program which concerns on 1 aspect of this invention is a program for functioning a computer as said control apparatus.

  A control method according to an aspect of the present invention provides a change in first reactive power that is a phase reactive power or a phase reactive power to be output by a power conversion unit linked to an AC power supply, in accordance with a frequency deviation of the AC power supply. A step of deriving an amount, and deriving a change amount of a second reactive power that is a phase reactive power to be output from the power conversion unit in order to suppress an increase in voltage at a connection point between the power conversion unit and the AC power source And a step of stopping output of power by the power converter when the change amount of the first reactive power interferes with the change amount of the second reactive power.

  The summary of the invention does not enumerate all the features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

It is a figure which shows an example of the system configuration | structure of the whole power supply system which concerns on this embodiment. It is a figure which shows an example of the functional block of the control apparatus which concerns on this embodiment. It is a figure which shows an example of the reactive power q1-frequency deviation characteristic. It is a flowchart which shows an example of the process sequence of suppression control of a voltage rise. It is a figure which shows an example of the mode of the time change of the voltage V3, the power factor, the reactive power q2, and the active power P at the time of performing suppression control of a voltage rise. It is a flowchart which shows an example of the process sequence regarding the stop process of the power conditioner performed by an electric power output control part. It is a figure which shows an example of the hardware constitutions of the control apparatus which concerns on this embodiment.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a diagram illustrating an example of a system configuration of the entire power supply system according to the present embodiment. The power supply system includes a solar cell array 200 and a power conditioner 10. The power conditioner 10 is an example of a power converter. The solar cell array 200 has a plurality of solar cell modules connected in series or in parallel. The solar cell array 200 is an example of a DC power source. The solar cell array 200 may be a single solar cell, a solar cell module in which solar cells are connected in series and in parallel, or the like. As the DC power source, a distributed power source other than the solar cell array 200 may be used. The distributed power source may be a gas engine, a gas turbine, a micro gas turbine, a fuel cell, a wind power generator, an electric vehicle, or a power storage system.

  The power conditioner 10 converts the DC voltage from the solar cell array 200 into an AC voltage and is connected to the system power supply 300. The system power supply 300 is an example of an AC power supply, and may be a single-phase three-wire power supply, for example. The system power supply 300 may be a three-phase power supply.

  The power conditioner 10 includes a control device 100 and a power conversion unit 101. The power conversion unit 101 converts the DC voltage output from the solar cell array 200 into an AC voltage that is phase-synchronized with the system AC voltage that is the AC voltage output from the system power supply 300, and outputs the AC voltage. The control device 100 controls the power conversion unit 101. The power conversion unit 101 includes a capacitor C1, a booster circuit 20, a capacitor C2, an inverter 30, a filter circuit 40, and a relay 50.

  One end of the capacitor C1 is electrically connected to the positive electrode of the solar cell array 200. The other end of the capacitor C1 is electrically connected to the negative electrode of the solar cell array 200. Capacitor C <b> 1 is an example of a noise reduction circuit that reduces noise included in the DC voltage output from solar cell array 200. In other words, the capacitor C1 is an example of a smoothing filter that smoothes the DC voltage output from the solar cell array 200.

  The booster circuit 20 boosts and outputs a DC voltage with reduced noise by the capacitor C1. The booster circuit 20 is an example of a non-insulated booster circuit. The booster circuit 20 may be a so-called chopper type switching regulator. The booster circuit 20 may be configured by an insulating booster circuit having a transformer winding such as a half-bridge booster circuit or a full-bridge booster circuit.

  Capacitor C2 smoothes the DC voltage output from booster circuit 20. In other words, the capacitor C <b> 2 reduces noise included in the DC voltage output from the booster circuit 20.

  The inverter 30 includes a switch. When the switch is turned on / off, the inverter 30 converts the DC voltage output from the booster circuit 20 into an AC voltage and outputs the AC voltage to the system power supply 300 side. The inverter 30 links the power from the solar cell array 200 with the power from the system power supply 300.

  The inverter 30 may be constituted by, for example, a single-phase full-bridge PWM inverter that includes four semiconductor switches that are bridge-connected. Of the four semiconductor switches, one pair of semiconductor switches is connected in series. Of the four semiconductor switches, the other pair of semiconductor switches are connected in series and connected in parallel with the one pair of semiconductor switches.

  The filter circuit 40 reduces noise included in the AC voltage output from the inverter 30. The filter circuit 40 includes a pair of coils L and a capacitor C3. One end of each of the pair of coils L is connected to the output end of the inverter 30. The other ends of the pair of coils L are connected to one end and the other end of the capacitor C3.

  The relay 50 is provided on the system power supply 300 side from the filter circuit 40. Relay 50 switches whether to electrically disconnect between inverter 30 and system power supply 300. When the relay 50 is turned on, the power conditioner 10 and the system power supply 300 are electrically connected. When the relay 50 is turned off, the power conditioner 10 and the system power supply 300 are electrically disconnected.

  The power conditioner 10 further includes an output terminal 52 and an output terminal 54. The output terminal 52 and the output terminal 54 are an example of a connection point between the power conversion unit 101 and the system power supply 300.

  The power conditioner 10 further includes voltage sensors 60, 62, 64 and current sensors 70, 72, and 74. The voltage sensor 60 detects a voltage V <b> 1 corresponding to the potential difference between both ends of the solar cell array 200. The voltage sensor 62 detects a voltage V2 corresponding to a potential difference between both ends on the output side of the booster circuit 20. The voltage sensor 64 detects a voltage V3 corresponding to the potential difference between the output terminal 52 and the output terminal 54 as the voltage at the connection point.

  The current sensor 70 detects a current I1 output from the solar cell array 200 and flowing to the input side of the booster circuit 20. The current sensor 72 detects the current I2 output from the booster circuit 20. Current sensor 74 detects current I3 output from inverter 30.

  Control device 100 controls the boosting operation of boosting circuit 20 and the DC / AC conversion operation of inverter 30 based on voltages V1, V2, V3, currents I1, I2, I3, and the like. The control device 100 includes a booster circuit based on the voltage detected by the voltage sensors 60, 62, 64 and the current detected by the current sensors 70, 72, 74 so that the maximum power can be obtained from the solar cell array 200. 20, the switching operation of inverter 30 is controlled, the DC voltage output from solar cell array 200 is boosted, the boosted DC voltage is converted into an AC voltage, and output to system power supply 300 side.

  In the power conditioner 10 configured as described above, when the system power supply 300 is stopped, the relay 50 must be turned off to electrically disconnect the power conditioner 10 and the system power supply 300. Further, the power conditioner 10 must control the voltage output from the power conditioner 10 so that the voltage at the connection point between the power conditioner 10 and the system power supply 300 does not exceed the upper limit voltage.

  The control device 100 adjusts the phase difference between the phase of the current output from the inverter 30 and the phase of the voltage, and the amplitude of the current output from the inverter 30, so that the phase advance is invalid on the system power supply 300 side. The desired reactive power, which is power or delayed phase reactive power, is supplied. The control device 100 detects the frequency fluctuation of the output voltage of the power conditioner 10 corresponding to the voltage at the connection point, so that the system power supply 300 is stopped, that is, the power conditioner 10 is operating independently. Is detected.

  In addition, when the voltage output from the power conditioner 10 is equal to or higher than the upper limit voltage, the control device 100 determines the phase difference between the phase of the current output from the inverter 30 and the phase of the voltage, and the inverter 30. The phase advance reactive power supplied to the system power supply 300 side is increased by adjusting the amplitude of the current output from. By increasing the phase advance reactive power, the current flowing from the system power supply 300 side becomes a delayed current, and the voltage at the connection point between the power conditioner 10 and the system power supply 300 decreases due to the action of the distribution line impedance. Accordingly, the control device 100 can control the voltage output from the power conditioner 10 to be smaller than the upper limit voltage.

  Here, the control device 100 supplies reactive power corresponding to the magnitude of the frequency deviation of the system power supply 300 to the system power supply 300 side, and detects the isolated operation based on the frequency fluctuation of the output voltage of the power conditioner 10. Sometimes. As the frequency deviation of the system power supply 300 increases, the variation in reactive power supplied to the system power supply 300 increases. When the system power supply 300 is stopped, the frequency deviation of the output voltage of the power conditioner 10 becomes large. Further, the greater the change in reactive power, the easier it is to detect the frequency variation of reactive power when the system power supply 300 is stopped.

  However, this corresponds to the case where the voltage output from the power conditioner 10 exceeds the upper limit voltage while the control device 100 is changing the reactive power supplied to the system power supply 300 to detect the isolated operation. In some cases, reactive power may be increased. In this case, there is a possibility that the reactive power change due to the frequency fluctuation is canceled by the reactive power to be increased, and the frequency fluctuation of the output voltage of the power conditioner 10 is hardly detected.

  Therefore, in the control device 100 according to the present embodiment, the amount of change in the reactive power derived for the detection of the isolated operation interferes with the amount of change in the reactive power derived for the suppression control of the voltage increase. When the amount of change in reactive power for detection of isolated operation interferes with the amount of change in reactive power derived for suppressing voltage rise, output of power by the power conversion unit 101 is stopped. The control device 100 turns off the relay 50 when the change amount of the reactive power derived for detecting the isolated operation interferes with the change amount of the reactive power derived for the suppression control of the voltage rise. The power conditioner 10 and the system power supply 300 are electrically disconnected. Further, the control device 100 stops the switching operation of the inverter 30.

  When the change in the reactive power based on the frequency variation is canceled and the frequency variation in the output voltage of the power conditioner 10 may be difficult to be detected, the control device 100 stops the power output by the power conversion unit 101 in advance. Let Therefore, the change amount of the reactive power derived for the detection of the isolated operation is interfered with the change amount of the reactive power derived for the suppression control of the voltage rise, so that the power conditioner 10 performs the isolated operation. It can be prevented that the power output by the power conversion unit 101 cannot be stopped without being detected. Therefore, the reactive power control for detecting the isolated operation and the reactive power control for suppressing the voltage increase interfere with each other, so that an adverse effect caused by a decrease in the accuracy of the isolated operation detection can be suppressed.

  FIG. 2 shows an example of functional blocks of the control device 100 according to the present embodiment. The control device 100 includes a frequency measurement unit 102, a moving average value deriving unit 104, a frequency deviation deriving unit 106, a first reactive power change deriving unit 108, an isolated operation detecting unit 110, a second reactive power change deriving unit 112, and an output. A voltage acquisition unit 114, a target reactive power deriving unit 116, a target active power deriving unit 118, a relay control unit 120, a PWM control unit 130, and a power output control unit 140 are provided. In addition, the control apparatus 100 may be provided outside the power conditioner 10 by modularizing. In this case, the control device 100 communicates with a control unit provided in the power conditioner 10 and outputs a control signal for controlling the output of the power conditioner 10 to the control unit provided in the power conditioner 10. May be.

  The frequency measurement unit 102 acquires the voltage of the system power supply 300 via the voltage sensor 64 and measures the system frequency indicating the frequency of the system power supply 300 from the acquired voltage. The frequency measurement unit 102 measures, for example, a time difference between the intermediate value of the fall and rise of the voltage signal detected from the voltage sensor 64 and the intermediate value of the next fall and rise as one cycle. When the system period of the system power supply 300 is 50 Hz (one system period is 20 milliseconds), the measurement period of the system period may be 1/3 or less of the system period, for example, 5 milliseconds.

  The moving average value deriving unit 104 sequentially derives the moving average value of the system cycle for a predetermined moving average time based on the system cycle measured by the frequency measuring unit 102. The moving average time may be longer than one cycle of the system cycle, for example, 20 msec, and may be equal to or less than the time allowed until the isolated operation state is detected after entering the isolated operation state. The moving average time may be, for example, shorter than 100 milliseconds, and the moving average time may be, for example, 40 milliseconds.

  The frequency deviation deriving unit 106 includes the latest moving average value derived by the moving average value deriving unit 104 and a past moving average value from the latest moving average value, for example, the moving average value deriving unit 104 includes the latest moving average value. The difference from the past moving average value derived by the moving average value deriving unit 104 before a predetermined time (for example, 200 ms) from the end point of the latest system cycle used to derive the frequency is derived as a frequency deviation. . The frequency deviation deriving unit 106 may derive the frequency deviation every cycle that is the same as the measurement cycle of the system cycle, for example, every 5 milliseconds.

  The first reactive power change amount deriving unit 108 derives the current reactive power q1 based on the frequency deviation of the system power supply 300, and the amount of change in the reactive power q1 indicating the difference between the previous reactive power q1 and the current reactive power q1. Δq1 is derived. The first reactive power variation derivation unit 108 may derive the reactive power q1 variation Δq1 so that the reactive power q1 increases in proportion to the frequency deviation of the system power supply 300. For example, the first reactive power change amount deriving unit 108 refers to the reactive power q1−frequency deviation characteristic as illustrated in FIG. 3 to derive the current reactive power q1 corresponding to the frequency deviation, thereby changing the change amount Δq1. May be derived.

  The first reactive power change amount derivation unit 108 is phase reactive power that causes the power conditioner 10 to output a current whose phase is advanced with respect to the system frequency when the frequency deviation of the system power supply 300 is positive. The reactive power q1 is derived. On the other hand, when the frequency deviation of the system power supply 300 is negative, the first reactive power change amount deriving unit 108 is the slow reactive power that causes the power conditioner 10 to output a current whose phase is delayed with respect to the system frequency. A certain reactive power q1 is derived. Note that the change amount Δq1 derived by the first reactive power change amount deriving unit 108 is a change amount of the reactive power q1 per unit time, that is, when the time axis is the X axis and the change amount of the reactive power q1 is the Y axis. An inclination may be indicated. The change amount Δq1 derived by the first reactive power change amount deriving unit 108 may indicate a speed at which the reactive power q1 is changed.

  The isolated operation detection unit 110 detects the isolated operation of the power conditioner 10 connected to the system power supply 300 based on the frequency fluctuation of the output voltage of the power conditioner 10 corresponding to the voltage at the connection point. The isolated operation detection unit 110 does not detect voltage frequency fluctuations based on reactive power fluctuations when the system power supply 300 is operating normally. On the other hand, when an abnormality has occurred such as when the system power supply 300 is stopped, the isolated operation detection unit 110 detects the frequency variation of the voltage based on the variation of the reactive power, so that the power conditioner 10 Detects isolated operation.

  When the isolated operation detection unit 110 detects the isolated operation of the power conditioner 10, the relay control unit 120 turns off the relay 50 and electrically disconnects the power conditioner 10 and the system power supply 300.

  The output voltage acquisition unit 114 detects the voltage V <b> 3 that is the output voltage of the power conditioner 10 corresponding to the voltage at the connection point detected by the voltage sensor 64. The second reactive power change amount deriving unit 112 determines whether or not the detected voltage V3 is equal to or higher than a predetermined upper limit voltage Vth. When the detected voltage V3 is equal to or higher than the upper limit voltage Vth, the second reactive power change amount deriving unit 112 increases the phase reactive power to be supplied to the system power supply 300 side to increase the output voltage of the power conditioner 10. In order to suppress the increase, the present reactive power q2 is derived, and a change amount Δq2 of the reactive power q2 indicating the difference between the previous reactive power q2 and the current reactive power q2 is derived. Note that the change amount Δq2 derived by the second reactive power change amount deriving unit 112 is a change amount of the reactive power q2 per unit time, that is, when the time axis is the X axis and the change amount of the reactive power q2 is the Y axis. An inclination may be indicated. The change amount Δq2 derived by the second reactive power change amount deriving unit 112 may indicate a speed at which the reactive power q2 is changed.

  The target reactive power deriving unit 116 is derived by the previous target reactive power Qc, the variation Δq1 of the reactive power q1 derived by the first reactive power variation deriving unit 108, and the second reactive power variation deriving unit 112. The current target reactive power Qt is derived using the amount of change Δq2 of the reactive power q2. The target reactive power deriving unit 116 may derive the current target reactive power Qt by adding the previous target reactive power Qc, the change amount Δq1, and the change amount Δq2. The target reactive power deriving unit 116 provides the derived current target reactive power Qt to the PWM control unit 130. Note that the target reactive power deriving unit 116 uses the previous and current reactive power q1 and the previous and current reactive power q2 as the first reactive power instead of the reactive power q1 variation Δq1 and the reactive power q2 variation Δq2. The target reactive power Qt of this time may be derived using the previous and current reactive power q1 and the previous and current reactive power q2 obtained from the change amount deriving unit 108 and the second reactive power change amount deriving unit 112. .

  The target active power deriving unit 118 derives the target active power P to be output from the power conditioner 10. The target active power deriving unit 118 derives the target active power P so that, for example, a maximum or maximum output can be obtained from the power conditioner 10. The target active power deriving unit 118 provides the derived target active power P to the PWM control unit 130.

  The PWM control unit 130 performs PWM control on the inverter 30 so that the maximum or maximum active power can be obtained from the solar cell array 200 based on the target active power P. Further, the PWM control unit 130 adjusts the phase difference between the phase of the current output from the inverter 30 and the phase of the voltage based on the current target reactive power Qt provided from the target reactive power deriving unit 116. Thus, the reactive power supplied to the system power supply 300 side is controlled.

  The power output control unit 140 causes the change amount of the first reactive power derived by the first reactive power change amount deriving unit 108 to interfere with the change amount of the second reactive power derived by the second reactive power change amount deriving unit 112. If so, the relay control unit 120 is instructed to turn off the relay 50. The power output control unit 140 instructs the relay control unit 120 to turn off the relay 50, so that the relay control unit 120 turns off the relay 50. Thereby, the power conditioner 10 and the system power supply 300 are electrically disconnected. Therefore, the amount of change in the reactive power derived for the suppression control of the voltage rise interferes with the amount of change in the reactive power derived for the detection of the isolated operation, so that the power conditioner 10 performs the isolated operation. It can be prevented that the power output by the power conversion unit 101 cannot be stopped without being detected.

  FIG. 4 is a flowchart illustrating an example of a procedure of voltage rise suppression control executed by the control device 100. The control device 100 periodically executes the procedure shown in FIG. The output voltage acquisition unit 114 acquires the voltage V3 that is the output voltage of the power conditioner 10 corresponding to the voltage at the connection point via the voltage sensor 64 (S100). The second reactive power change amount derivation unit 112 determines whether or not the voltage V3 is an upper limit voltage, for example, 107 V or more (S102). When the voltage V3 is equal to or higher than the upper limit voltage, the second reactive power change amount deriving unit 112 determines whether or not the power factor is higher than a lower limit threshold, for example, 0.85.

  When the power factor is larger than the lower limit threshold, the second reactive power variation deriving unit 112 derives the variation Δq2 of the reactive power q2 so that the fast reactive power increases (S106). On the other hand, when the power factor is equal to or lower than the lower limit threshold, the target active power deriving unit 118 derives the target active power P so as to decrease the active power (S108).

  When the voltage V3 is smaller than the upper limit voltage, the target active power deriving unit 118 determines whether or not the current active power is suppressed (S110). That is, the target active power deriving unit 118 determines whether the current active power is maximum or maximum, for example. If it is not the maximum or maximum, the target active power deriving unit 118 derives the target active power P so that the active power becomes maximum or maximum (S112).

  When the current active power is not suppressed, that is, when the target active power deriving unit 118 determines that the current active power is maximum or maximum, the second reactive power change amount deriving unit 112 It is determined whether q2 is 0 (S114). When the reactive power q2 is not 0, the second reactive power variation deriving unit 112 derives the variation Δq2 of the reactive power q2 so that the reactive power q2 that is the fast reactive power decreases (S116).

  The control device 100 controls the output of the power conditioner 10 so that the voltage at the interconnection point does not become higher than the upper limit voltage by repeating the above processing.

  FIG. 5 is a diagram illustrating an example of a time change state of the voltage V3, the power factor, the reactive power q2, and the active power P when the control device 100 executes the suppression control for increasing the voltage according to the flowchart illustrated in FIG. It is.

  In section 1, the voltage V3 rises as the voltage at the interconnection point rises, and the active power P also rises. In section 1, the power factor is 1 and reactive power q2 is zero. When the voltage V3 reaches the upper limit voltage, the process shifts to section 2, and in section 2, the reactive power q2 that is the fast reactive power increases until the power factor reaches 0.85 that is the lower limit threshold. When the power factor reaches 0.85, the section 3 is entered. When the voltage V3 still exceeds the upper limit voltage, the active power P decreases in the section 3. When the voltage V3 becomes smaller than the upper limit voltage, the process proceeds to the section 4. In section 4, the active power P increases until it reaches a maximum or a maximum. When the active power P is no longer suppressed, the process proceeds to the section 5, and in the section 5, the phase advance reactive power q <b> 2 decreases and the power factor returns to 1.

  When the first reactive power change amount deriving unit 108 derives the change amount Δq1 of the reactive power q1 that is the fast phase reactive power or the slow phase reactive power in accordance with the frequency deviation of the system power supply 300 in the process described above. There is. For example, when the first reactive power change amount deriving unit 108 derives the delay reactive power change amount Δq1 as the change amount Δq1 of the reactive power q1 in the section 2, it is derived by the second reactive power change amount deriving unit 112. Since reactive power q2 is a fast phase reactive power, change amount Δq1 of reactive power q1 and change amount Δq2 of reactive power q2 interfere with each other.

  Using the amount of change Δq1 of reactive power q1, the amount of change Δq2 of reactive power q2, and the previous target reactive power Qc, for example, the target reactive power deriving unit 116 uses the target reactive power deriving unit 116 according to the formula: Qt = Qc + Δq1 + Δq2. When deriving the power Qt, there is a possibility that the change amount Δq1 of the reactive power q1 may be interfered by the change amount Δq2 of the reactive power q2. When the change amount Δq1 of the reactive power q1 interferes with the change amount Δq2 of the reactive power q2, the independent operation detection unit 110 outputs the reactive power output from the power conditioner 10 even when the power conditioner 10 is operating alone. Therefore, there is a possibility that the frequency fluctuation of the system power supply 300 cannot be detected.

  As shown in section 3 and section 5, when reactive power q2, which is the fast reactive power, is changing in a decreasing direction, first reactive power change amount deriving unit 108 responds to the frequency deviation of system power supply 300. Thus, even when the amount of change Δq1 of the fast reactive power is derived as the amount of change Δq1 of the reactive power q1, the amount of change Δq1 of the reactive power q1 and the amount of change Δq2 of the reactive power q2 interfere with each other.

  As shown in section 2 and section 4, when reactive power q2, which is the fast reactive power, changes in the increasing direction, first reactive power change amount deriving unit 108 changes the amount of reactive power q1. When the amount of change in fast reactive power is derived as Δq1, the amount of change Δq1 in reactive power q1 and the amount of change Δq2 in reactive power q2 do not interfere. Further, as shown in section 3 and section 5, when the reactive power q2 that is the fast reactive power is changing in a decreasing direction, the first reactive power change amount deriving unit 108 changes the reactive power q1 change amount. Even when the amount of change in slow reactive power is derived as Δq1, the amount of change Δq1 in reactive power q1 and the amount of change Δq2 in reactive power q2 do not interfere.

  As described above, the power based on the target reactive power Qt derived from the reactive power q1 variation Δq1 and the reactive power q2 variation Δq2 depending on the values of the reactive power q1 variation Δq1 and the reactive power q2 variation Δq2. Due to the reactive power output by the conditioner 10, the isolated operation of the power conditioner 10 may not be detected normally.

  Therefore, according to the control device 100 according to the present embodiment, the first reactive power change amount deriving unit 108 derived from the second reactive power change amount derived by the second reactive power change amount deriving unit 112. When the amount of change in reactive power interferes, the power output control unit 140 turns off the relay 50 via the relay control unit 120 and stops the power output by the power conversion unit 101. As a result, since the independent operation of the power conditioner 10 is not normally detected, the power conditioner 10 continues to output power even though the power conditioner 10 has to stop outputting power. Can be prevented.

  FIG. 6 is a flowchart illustrating an example of a processing procedure related to a power conditioner stop process executed by the power output control unit 140. In the power output control unit 140, the first reactive power change amount deriving unit 108 and the second reactive power change amount deriving unit 112 change the reactive power q1 variation Δq1 and the reactive power q2 variation Δq2 according to the processing procedure illustrated in FIG. May be executed each time

  The power output control unit 140 uses the first reactive power change amount derivation unit 108 to detect the amount of change Δq1 of the reactive power q1 derived for the isolated operation detection and the second reactive power change amount derivation unit 112 to suppress the voltage increase. The amount of change Δq2 of the derived reactive power q2 is acquired (S200).

  The power output control unit 140 determines whether or not the change amount Δq1 of the reactive power q1 is zero (S202). If the change amount Δq1 of the reactive power q1 is zero, the change amount Δq1 of the reactive power q1 and the change amount Δq2 of the reactive power q2 do not interfere with each other, and the power output control unit 140 ends the processing.

  When the change amount Δq1 of the reactive power q1 is not zero, the power output control unit 140 determines whether or not the change amount Δq2 of the reactive power q2 is zero (S204). If the change amount Δq2 of the reactive power q2 is zero, the change amount Δq1 of the reactive power q1 and the change amount Δq2 of the reactive power q2 do not interfere with each other, and the power output control unit 140 ends the processing.

  When both the amount of change Δq1 in reactive power q1 and the amount of change Δq2 in reactive power q2 are not zero, power output control section 140 determines whether or not reactive power q1 is a fast reactive power (S206). When reactive power q1 is not fast reactive power, that is, when reactive power q1 is slow reactive power, power output control unit 140 determines whether or not change amount Δq2 of reactive power q2 is smaller than zero. (S208). The power output control unit 140 determines whether or not the change amount Δq2 of the reactive power q2 is a negative value, that is, the power output control unit 140 changes the change amount Δq2 of the reactive power q2 in a direction in which the reactive power q2 decreases. It is determined whether it is a value.

  If change amount Δq2 of reactive power q2 is not smaller than zero, power output control unit 140 turns off relay 50 via relay control unit 120 to electrically connect power conversion unit 101 and system power supply 300 to each other. It shuts off and stops outputting electric power from the power converter 101 (S210). If reactive power q1 is slow reactive power and change amount Δq2 of reactive power q2 is a positive value, that is, change amount Δq2 of reactive power q2 is a value that changes in a direction in which reactive power q2 increases. For example, the power output control unit 140 turns off the relay 50 through the relay control unit 120 to electrically disconnect between the power conversion unit 101 and the system power supply 300, and power is output from the power conversion unit 101. Stop it.

  If reactive power q1 is lagging reactive power and change amount Δq2 of reactive power q2 is smaller than zero, change amount Δq1 of reactive power q1 and change amount Δq2 of reactive power q2 do not interfere with each other. Ends the process.

  When the reactive power q1 is the fast reactive power, the power output control unit 140 determines whether or not the change amount Δq2 of the reactive power q2 is smaller than zero (S212). When the change amount Δq2 of the reactive power q2 is smaller than zero, if the change amount Δq2 of the reactive power q2 is not smaller than zero, the power output control unit 140 turns off the relay 50 via the relay control unit 120 to convert power. The unit 101 and the system power supply 300 are electrically disconnected from each other, and power output from the power conversion unit 101 is stopped (S210). When the reactive power q1 is a fast reactive power and the amount of change Δq2 of the reactive power q2 indicates a negative value, the power output control unit 140 stops outputting power from the power conversion unit 101.

  If reactive power q1 is a fast reactive power and reactive power q2 variation Δq2 is greater than zero, reactive power q1 variation Δq1 and reactive power q2 variation Δq2 do not interfere with each other. Ends the process.

  As described above, according to the power supply system according to the present embodiment, the change in the reactive power q1 derived for the detection of the isolated operation by the amount of change Δq2 in the reactive power q2 derived for the suppression control of the voltage rise. When the amount Δq <b> 1 is interfered, the power output control unit 140 stops outputting power from the power conversion unit 101. When the change in the reactive power based on the frequency fluctuation is canceled and the frequency fluctuation of the output voltage of the power conditioner 10 may be difficult to be detected, the output of power by the power conversion unit 101 is stopped in advance.

  Therefore, the change amount of the reactive power derived for the detection of the isolated operation is interfered with the change amount of the reactive power derived for the suppression control of the voltage rise, so that the power conditioner 10 performs the isolated operation. It can be prevented that the power output by the power conversion unit 101 cannot be stopped without being detected. Therefore, the reactive power control for detecting the isolated operation and the reactive power control for suppressing the voltage increase interfere with each other, so that an adverse effect caused by a decrease in the accuracy of the isolated operation detection can be suppressed.

  In addition, each part with which the control apparatus 100 which concerns on this embodiment is provided is a computer-readable recording medium which performs the various processes regarding the pressure | voltage rise operation of the power conditioner 10, a direct current alternating current conversion operation, islanding operation detection control, and voltage rise suppression control. May be configured by installing the program recorded in the above and causing the computer to execute the program. That is, by causing the computer to execute programs for performing various processes relating to the boosting operation, DC / AC conversion operation, isolated operation detection control, and voltage rise suppression control of the power conditioner 10, the computer is caused to function as each unit included in the control device 100. Thus, the control device 100 may be configured.

  FIG. 7 is a diagram illustrating an example of a hardware configuration of the control device 100 according to the present embodiment. The control device 100 according to the present embodiment includes a CPU peripheral unit having a CPU 904 and a RAM 906 that are connected to each other by a host controller 902, a ROM 910 that is connected to the host controller 902 by an input / output controller 908, and a communication interface 912.

  The host controller 902 connects the RAM 906 and the CPU 904 that accesses the RAM 906 at a high transfer rate. The CPU 904 operates based on programs stored in the ROM 910 and the RAM 906 to control each unit. The input / output controller 908 connects the host controller 902, the communication interface 912 that is a relatively high-speed input / output device, and the ROM 910.

  The communication interface 912 communicates with the voltage sensors 60, 62, 64, the current sensors 70, 72, 74, and the like. The ROM 910 stores programs and data used by the CPU 904 in the control device 100. The ROM 910 stores a boot program that the control device 100 executes at startup, a program that depends on the hardware of the control device 100, and the like.

  A program provided to the ROM 910 via the RAM 906 is stored in a computer-readable recording medium such as a CD-ROM or a USB memory and provided by the user. The program is read from the recording medium, installed in the ROM 910 in the control apparatus 100 via the RAM 906, and executed by the CPU 904.

  A program that is installed and executed in the control device 100 works on the CPU 904 and the like, and causes the control device 100 to perform the frequency measurement unit 102, the moving average value derivation unit 104, the frequency deviation derivation unit 106 described with reference to FIGS. First reactive power variation derivation unit 108, islanding operation detection unit 110, second reactive power variation derivation unit 112, output voltage acquisition unit 114, target reactive power derivation unit 116, target reactive power derivation unit 118, relay control unit 120 , Function as a PWM control unit 130 and a power output control unit 140.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 Power conditioner 20 Booster circuit 30 Inverter 40 Filter circuit 50 Relay 52, 54 Output terminal 60, 62, 64 Voltage sensor 70, 72, 74 Current sensor 72 Current sensor 74 Current sensor 100 Control apparatus 101 Power conversion part 102 Frequency measurement part 104 Moving average value deriving unit 106 Frequency deviation deriving unit 108 First reactive power change deriving unit 110 Isolated operation detecting unit 112 Second reactive power change deriving unit 114 Output voltage acquiring unit 116 Target reactive power deriving unit 118 Target active power deriving Unit 120 Relay Control Unit 130 PWM Control Unit 140 Power Output Control Unit 200 Solar Cell Array 300 System Power Supply 902 Host Controller 904 CPU
906 RAM
908 I / O controller 910 ROM
912 Communication interface

Claims (7)

A first reactive power change amount for deriving a change amount of the first reactive power which is a fast reactive power or a slow reactive power to be output by the power conversion unit linked to the AC power supply according to a frequency deviation of the AC power supply. A derivation unit;
Second reactive power for deriving the amount of change in second reactive power, which is a fast reactive power to be output from the power converter, in order to suppress an increase in voltage at the connection point between the power converter and the AC power supply A variation derivation unit;
A control apparatus comprising: a power output control unit that stops output of power by the power conversion unit when the change amount of the first reactive power interferes with the change amount of the second reactive power.   In the power output control unit, the change amount of the first reactive power is a change amount of the fast reactive power that changes in a direction in which the first reactive power increases, and the change amount of the second reactive power is negative. The control device according to claim 1, wherein when the value is a value, output of power by the power conversion unit is stopped.   The power output control unit stops output of power by the power conversion unit when the first reactive power is slow phase reactive power and the amount of change in the second reactive power is a positive value. The control device according to claim 1 or 2. A control device according to any one of claims 1 to 3,
A power conversion apparatus comprising: the power conversion unit that converts a direct current from a direct current power source into an alternating current and links the alternating current power source. The power conversion device according to claim 4,
A power supply system comprising the DC power supply.   The program for functioning a computer as a control apparatus as described in any one of Claims 1-3. Deriving the amount of change in the first reactive power that is the fast reactive power or the slow reactive power to be output by the power conversion unit linked to the alternating current power supply according to the frequency deviation of the alternating current power supply;
Deriving the amount of change in the second reactive power, which is a fast reactive power to be output from the power conversion unit, in order to suppress an increase in voltage at the connection point between the power conversion unit and the AC power source;
And a step of stopping the output of power by the power converter when the change amount of the first reactive power interferes with the change amount of the second reactive power.

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