JP2011101455A - Device for controlling photovoltaic power generation facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for controlling photovoltaic power generation facilities for quick recovery up to the maximum output before short-time power failure when the short-time power failure occurs in a power system and the system recovers power. <P>SOLUTION: A system state decision unit 22 monitors a voltage of the power system 15 connected to a solar cell 11 to determine whether the power system 15 is in a power failure state, and stores an operating voltage V of the solar cell 11 immediately before power failure in an operating voltage memory 23 when the system state decision unit 22 determines that the power system 15 is in a power failure state. A maximum power following control unit 18 performs following control of voltage of the solar cell 11 to an optimum operating point from an operating voltage V1 of the solar cell 11 immediately before power failure stored in the operating voltage memory 23 when the power system 11 recovers from the power failure state. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for a photovoltaic power generation facility that controls the operation of a photovoltaic power generation facility that generates power using sunlight in conjunction with an electric power system.

  Because solar cells have different operating points that generate maximum power depending on solar radiation intensity and temperature, it is important to follow the optimal operating point that changes every moment in order to effectively use the power generated by solar cells. It becomes.

  In order to obtain such an optimal operating point for extracting the maximum power, maximum power tracking control {MPPT (Maximum Power Point Tracking) control} for tracking control to the optimal operating point at which the output of the solar cell is maximum is used. For example, the output power obtained at the current operating point is compared with the output power obtained at the operating point slightly moved from the current operating point to determine the direction to the optimal operating point, and to the optimal operating point. A hill-climbing method to be followed is used (see, for example, Patent Document 1).

  On the other hand, when a power failure occurs in the power system connected to the photovoltaic power generation facility, the output of the photovoltaic power generation facility is set to zero and the system is restarted after the power failure is restored for a short time. For example, when a single operation state occurs due to a short-time power failure for 2 seconds in the power system, the photovoltaic power generation equipment is stopped and restarted after 300 seconds of system power recovery.

  FIG. 13 shows a V-I characteristic showing the relationship between the output voltage V and the output current I of the photovoltaic power generation facility and a VP characteristic showing the relationship between the output voltage V and the output power P of the photovoltaic power generation facility. It is an example of a graph. As shown in FIG. 13, the solar power generation facility has a constant VI characteristic curve C1 and a constant VP characteristic curve P1 when the solar radiation intensity and temperature are constant, and the VI characteristic curve C1. It is the optimum operating point C11 {coordinate C11 (V1, I1)} at which the upper output power becomes the maximum output P1max. In normal times, the output voltage V of the photovoltaic power generation facility is controlled so as to reach the optimum operating point C11.

  FIG. 14 is a characteristic diagram of the output voltage V and the output power P showing the conventional operation characteristics of the photovoltaic power generation facility. In the initial state where the photovoltaic power generation facility is connected to the power system, the output voltage V is equal to the open circuit voltage Vo, and the output voltage V is adjusted to gradually increase the output power P from zero. That is, at the time point t0, the output voltage target value V1r gradually decreases from the open voltage Vo by the maximum power tracking control. Along with this, the output power P of the photovoltaic power generation facility increases stepwise, and when the optimum operating point C11 on the VI characteristic curve C1 is reached at the time point t1, the output power P of the photovoltaic power generation facility is at the maximum output P1max. It becomes almost constant.

  If the output power P of the photovoltaic power generation facility is operating at a substantially constant maximum output P1max, and if a short interruption occurs in the power system at time t2, the output voltage V of the photovoltaic power generation facility is open. The voltage is adjusted to Vo. As a result, the output power P of the photovoltaic power generation facility is adjusted from the maximum output P1max to zero at once. When the power system is restored at time t3, the photovoltaic power generation facility is restarted, and the output voltage target value V1r is gradually lowered from the open voltage Vo by the maximum power tracking control by the maximum power tracking control. Along with this, the output power P of the photovoltaic power generation facility rises in stages, and when the optimum operating point C11 on the VI characteristic curve C1 is reached at time t4, the output power P of the solar power generation facility is short before the power failure. The maximum output P1max is substantially constant.

JP 2004-295688 A

  However, when a short interruption occurs in a power system in which a large amount of photovoltaic power generation equipment is introduced, the output voltage V is adjusted to the open voltage Vo and the output power P becomes zero at the same time. The power supply / demand balance may be disrupted, which may greatly affect the operation of the power system. In particular, since photovoltaic power generation equipment is slowly climbed up to the maximum output operating voltage V1 by maximum power tracking control when restarting, it takes time to recover to the maximum output P1max before a short interruption, contributing to system stabilization. Can not. Therefore, it is required that the photovoltaic power generation equipment has a FRT (Fault Ride Through) function for overcoming a power failure for a short time and restarting at high speed.

  The objective of this invention is providing the control apparatus of the solar power generation facility which can be recovered | restored at high speed to the maximum output before a short-time power failure, when a short-time power failure generate | occur | produces in an electric power system and a system power recovery.

  A control device for a photovoltaic power generation facility according to the invention of claim 1 is a control device for a photovoltaic power generation facility in which a direct current generated by a solar cell is converted into an alternating current by a power converter and supplied to an electric power system. The maximum power follow-up control unit that obtains the maximum output of the solar cell by tracking the voltage of the solar cell to the optimum operating point at which the output of the maximum is monitored, and the power system monitors the voltage of the power system to which the solar cell is connected. An operating voltage storage that stores the operating voltage of the solar cell immediately before the power failure when the power system is determined to be in a power outage state by the system state determining unit that determines whether or not it is in a power outage state And when the power system is not in a power outage state, the output of the power converter is controlled so that the maximum output obtained by the maximum power follow-up control unit is obtained. And an output control unit that controls the output of the power converter so that the voltage of the solar cell becomes an open voltage of the solar cell, and when the power system returns from a power failure state, the maximum power follow-up control unit is The voltage of the solar cell is controlled to follow the optimum operating point from the operating voltage of the solar cell immediately before the power failure stored in the operating voltage storage unit.

  A control device for a photovoltaic power generation facility according to a second aspect of the invention is a control device for a photovoltaic power generation facility in which a direct current generated by a solar cell is converted into an alternating current by a power converter and supplied to an electric power system. The maximum power follow-up control unit that obtains the maximum output of the solar cell by tracking the voltage of the solar cell to the optimum operating point at which the output of the maximum is monitored, and the power system monitors the voltage of the power system to which the solar cell is connected. An operating voltage storage that stores the operating voltage of the solar cell immediately before the power failure when the power system is determined to be in a power outage state by the system state determining unit that determines whether or not it is in a power outage state And when the power system is not in a power outage state, the output of the power converter is controlled so that the maximum output obtained by the maximum power follow-up control unit is obtained. And an output control unit that controls the output of the power converter so that the voltage of the solar cell becomes an open voltage of the solar cell, and when the power system returns from a power failure state, the maximum power follow-up control unit is The voltage of the solar cell is controlled to follow the optimum operating point by moving in the voltage decreasing direction from the operating voltage of the solar cell immediately before the power failure stored in the operating voltage storage unit.

  A control device for a photovoltaic power generation facility according to a third aspect of the invention is a control device for a photovoltaic power generation facility in which direct current generated by a solar cell is converted into alternating current by a power converter and supplied to an electric power system. The maximum power follow-up control unit that obtains the maximum output of the solar cell by tracking the voltage of the solar cell to the optimum operating point at which the output of the maximum is monitored, and the power system monitors the voltage of the power system to which the solar cell is connected. An operating voltage storage that stores the operating voltage of the solar cell immediately before the power failure when the power system is determined to be in a power outage state by the system state determining unit that determines whether or not it is in a power outage state And an output value storage unit that stores the output current value or power value of the solar cell immediately before the power outage when the power system is determined to be in a power outage state by the system state determination unit, and the power system is out of power When not in the state, the output of the power converter is controlled so that the maximum output obtained by the maximum power follow-up control unit is obtained, and when the power system is in a power failure state, the voltage of the solar cell is open to the solar cell. An output control unit that controls the output of the power converter so as to become a voltage, and when the power system is restored from the power failure state, the maximum power follow-up control unit stores the power failure stored in the operating voltage storage unit. It is determined whether or not the output value of the solar cell is equal to or greater than the output value immediately before the stop stored in the output value storage unit at the time of restart at the operating voltage of the solar cell immediately before, and the output value of the solar cell is the output immediately before the stop When the value is greater than or equal to the value, the voltage of the solar cell is controlled to follow the optimum operating point by moving in the direction of voltage increase from the operating voltage of the solar cell immediately before the power failure stored in the operating voltage storage unit.

  A control device for a photovoltaic power generation facility according to the invention of claim 4 is a control device for a photovoltaic power generation facility in which direct current generated by the solar cell is converted into alternating current by a power converter and supplied to an electric power system. The maximum power follow-up control unit that obtains the maximum output of the solar cell by tracking the voltage of the solar cell to the optimum operating point at which the output of the maximum is monitored, and the power system monitors the voltage of the power system to which the solar cell is connected. An operating voltage storage that stores the operating voltage of the solar cell immediately before the power failure when the power system is determined to be in a power outage state by the system state determining unit that determines whether or not it is in a power outage state An output value storage unit that stores the output value of the solar cell immediately before the power failure when the power system is determined to be in a power failure state by the power system state determination unit, and the power system is not in a power failure state The output of the power converter is controlled so as to be the maximum output obtained by the maximum power tracking control unit, and when the power system is in a power failure state, the voltage of the solar cell becomes the open voltage of the solar cell. And an output control unit for controlling the output of the power converter, and when the power system is restored from the power failure state, the maximum power follow-up control unit is configured to store the sun immediately before the power failure stored in the operating voltage storage unit. When restarting at the operating voltage of the battery, it is determined whether the output value of the solar cell is less than the output value immediately before stopping stored in the output value storage unit, and the output value of the solar cell is less than the output value immediately before stopping Is characterized in that it shifts the operating voltage of the solar cell immediately before the power failure stored in the operating voltage storage unit in the voltage decreasing direction to control the voltage of the solar cell to the optimum operating point.

  According to the invention of claim 1, when it is determined that the power system is in a power outage state, the operating voltage of the solar cell immediately before the power outage is stored in the operating voltage storage unit, and when the power system is restored from the power outage state, The maximum power tracking control unit controls the solar cell voltage to the optimum operating point from the operating voltage of the solar cell immediately before the power failure stored in the operating voltage storage unit, so it can recover at high speed to the maximum output before the power failure for a short time, It can contribute to the stabilization of the power system.

  According to the invention of claim 2, when the power system returns from the power failure state and controls the voltage of the solar cell to follow the optimum operating point, the voltage is calculated from the operating voltage of the solar cell immediately before the power failure stored in the operating voltage storage unit. Since the solar cell voltage is controlled to follow the optimum operating point by moving it in the downward direction, it is always output if the solar radiation intensity when the power system returns from the power failure state is smaller than the solar radiation intensity at the time of a short power failure. The power will increase. Therefore, when the solar radiation intensity is reduced when the power system returns from the power failure state, it is possible to prevent a temporary decrease in output power when the maximum power tracking control is resumed.

  According to the invention of claim 3, when the power system returns from the power failure state and controls the voltage of the solar cell to the optimum operating point, the maximum power tracking control unit has the output value of the solar cell at the time of restarting. When the output value stored in the output value storage unit is greater than or equal to the output value immediately before the stop, the solar cell voltage is controlled to follow the optimal operating point by moving it from the operating voltage stored in the operating voltage storage unit immediately before the power failure. Therefore, the maximum power follow-up control adapted to the VI characteristic curve in which the solar radiation intensity when the power system returns from the power failure state is larger than the solar radiation intensity at the time of a short power failure becomes possible.

  According to the invention of claim 4, when the power system returns from the power failure state and controls the voltage of the solar cell to the optimum operating point, the maximum power tracking control unit is configured so that the output value of the solar cell at the time of restart is When the output value is less than the output value immediately before stopping stored in the output value storage unit, the solar cell voltage is controlled to follow the optimum operating point by moving it from the operating voltage stored in the operating voltage storage unit immediately before the power failure. Therefore, the maximum power follow-up control adapted to the VI characteristic curve in which the solar radiation intensity when the power system returns from the power failure state is smaller than the solar radiation intensity during the short power failure is possible.

The block diagram of the control apparatus of the solar power generation facility concerning the 1st Embodiment of this invention. The graph of an example of the VI characteristic and VP characteristic of a solar power generation facility which shows an example of operation | movement of the control apparatus of the solar power generation facility concerning the 1st Embodiment of this invention. FIG. 3 is a characteristic diagram of an example of output voltage V and output power P in the operation characteristics of the photovoltaic power generation facility shown in FIG. 2. The graph of an example of VI characteristic and VP characteristic which made the solar radiation intensity the parameter which shows another example of operation | movement of the control apparatus of the solar power generation facility concerning the 1st Embodiment of this invention. The characteristic diagram of an example of the output voltage V and the output power P of a photovoltaic power generation facility in case the sunshine intensity | strength when a power grid | system returns to power is smaller than the sunshine intensity | strength when a power failure occurs for a short time. The characteristic diagram of an example of the output voltage V and the output power P of a photovoltaic power generation equipment in case the sunshine intensity | strength when an electric power grid returns is the same as the sunshine intensity | strength when a power failure occurs for a short time. The characteristic diagram of an example of the output voltage V and the output power P of the photovoltaic power generation equipment when the sunshine intensity when the power system is restored is greater than the sunshine intensity when the power failure occurs for a short time. The block diagram of the control apparatus of the solar power generation facility concerning the 2nd Embodiment of this invention. The graph of an example of the VI characteristic and VP characteristic of solar power generation equipment when the output electric power of the solar cell at the time of restart in the 2nd Embodiment of this invention is more than the output electric power just before a stop. The characteristic view of an example of the output voltage V and the output electric power P in the driving | running characteristic of the solar power generation equipment shown in FIG. The graph of an example of the VI characteristic and VP characteristic of solar power generation equipment when the output power of the solar cell at the time of restart in the 2nd Embodiment of this invention is less than the output power just before a stop. The characteristic view of an example of the output voltage V and the output electric power P in the driving | running characteristic of the solar power generation equipment shown in FIG. The graph of an example of the VP characteristic which showed the relationship between the output voltage V of solar power generation equipment, and the output voltage V of solar power generation equipment, and the relationship between the output voltage V of solar power generation equipment, and output electric power P. The characteristic diagram of the output voltage V and the output electric power P which show the conventional driving | running characteristic of a solar power generation facility.

  Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a control device for a photovoltaic power generation facility according to the first embodiment of the present invention.

  The DC power generated by the solar battery 11 of the photovoltaic power generation facility is converted into AC power by the power converter 12 and linked to the power system 15 via the transformer 13 and the switch 14. The output voltage Vd of the solar cell 11 is detected by the voltage detector 16, and the output current Id of the solar cell 11 is detected by the current detector 17 and input to the maximum power tracking control unit 18. The maximum power tracking control unit 18 performs tracking control of the output voltage Vd of the solar cell 11 at the optimum operating point where the output of the solar cell 11 is maximum, and obtains an output target value Pr for obtaining the maximum output Pmax of the solar cell 11. Output to the output control unit 19. The output control unit 19 outputs a gate drive signal to the gate drive circuit 20 so that the output of the power converter 12 becomes the output target value Pr from the maximum power follow-up control unit 18, and the power converter 12 is driven by the gate drive signal. Control.

  The AC voltage Va at the connection end of the power system 16 to which the solar battery 11 is connected is detected by the voltage detector 21 and input to the system state determination unit 22. The system state determination unit 22 monitors the AC voltage Va at the connection end of the power system 15 to which the solar battery is connected, and determines whether the power system 15 is in a power failure state. When it is determined that the power system 15 is in a power failure state, the system state determination unit 22 notifies the output control unit 19 and the operating voltage storage unit 23 that a power failure state has occurred.

  The operating voltage storage unit 23 stores the operating voltage V <b> 1 of the solar cell 11 immediately before the power failure when receiving a notification that the power system 15 is in a power failure state by the system state determination unit 22. On the other hand, when the output control unit 19 receives a notification that the power system 15 is in a power failure state by the system state determination unit 22, the output voltage Vd of the solar cell 11 becomes the open voltage Vo of the solar cell 11. That is, the output of the power converter 12 is controlled via the gate drive circuit 20 so that the output power P of the solar cell 11 becomes zero. Thereby, the output power P of the solar cell 11 is controlled to zero from the output target value Pr from the maximum power follow-up control unit 18.

  Next, when detecting that the power system 15 has recovered from the power failure state, the system state determination unit 22 notifies the maximum power tracking control unit 18 that the power system 15 has recovered. When the maximum power follow-up control unit 18 receives a notification from the system state determination unit 22 that the power system 15 has been restored, the maximum power follow-up control is performed from the operation voltage V1 of the solar cell 11 immediately before the power failure stored in the operation voltage storage unit 23. To resume. Thus, since maximum power follow-up control is restarted from the operating voltage V1 of the solar cell 11 immediately before the power failure of the power system 15, it is possible to recover to the maximum output before the power failure for a short time at high speed and contribute to the stabilization of the power system.

  FIG. 2 is a graph of an example of the VI characteristic and the VP characteristic of the solar power generation facility showing an example of the operation of the control device for the solar power generation facility according to the first embodiment of the present invention. As shown in FIG. 2, during normal times, the output control unit 19 controls the operation at the optimum operating point C11 {coordinate C11 (V1, I1)} at which the output power on the VI characteristic curve C1 is the maximum output P1max. ing. In this state, when the power system 15 is in a power failure state, the operating voltage storage unit 23 stores the operating voltage V1 of the solar cell 11 at that time, and the output control unit 19 sets the output voltage Vd of the solar cell 11 to that of the solar cell 11. The power converter 12 is controlled via the gate drive circuit 20 so that the open circuit voltage Vo is obtained, that is, the output power P1 of the solar battery 11 is zero.

  When the power system 15 returns from the power failure state, the maximum power tracking control unit 18 tracks the solar cell voltage to the optimum operating point from the operating voltage V1 of the solar cell 11 immediately before the power failure stored in the operating voltage storage unit 23. Since the control is performed, the optimum operating point C11 at which the output power P1 on the VI characteristic curve C1 becomes the maximum output P1max can be reached in a short time.

  FIG. 3 is a characteristic diagram of an example of the output voltage V and the output power P in the operation characteristics of the photovoltaic power generation facility shown in FIG. At the time point t0 in the initial state when the photovoltaic power generation facility is connected to the power system 15, the output voltage V is zero, and the output voltage P is gradually increased from zero after adjusting the output voltage V to the open circuit voltage Vo. That is, at the time point t0, the output voltage target value V1r gradually decreases from the open voltage Vo by the maximum power tracking control. Along with this, the output power P of the photovoltaic power generation facility increases stepwise, and when the optimum operating point C11 on the VI characteristic curve C1 is reached at the time point t1, the output power P of the photovoltaic power generation facility is at the maximum output P1max. It becomes almost constant.

  If the output power P of the photovoltaic power generation facility is operating at a substantially constant maximum output P1max, and if a short interruption occurs in the power system at time t2, the output voltage V of the photovoltaic power generation facility is open. The voltage is adjusted to Vo. As a result, the output power P of the photovoltaic power generation facility is adjusted from the maximum output P1max to zero at once. When the power system is restored at time t3, the photovoltaic power generation facility is restarted, and the maximum power follow-up control is restarted from the operating voltage V1 of the solar cell 11 immediately before the power failure by the maximum power follow-up control. The Therefore, the output power P of the photovoltaic power generation facility is controlled to the maximum output P1max from the vicinity of the optimum operating point C11 on the VI characteristic curve C1.

  Thus, when the power system 15 returns from the power failure state, the maximum power follow-up control is resumed from the operating voltage V1 of the solar cell 11 immediately before the power system 15 power failure. It can recover and contribute to the stabilization of the power system.

  In the above description, the direction in which the voltage is moved from the operating point V1 immediately before the power failure is not particularly determined in order to control the voltage of the solar cell 11 to follow the optimum operating point from the operating voltage V1 of the solar cell 11 immediately before the power failure. The voltage rising direction or voltage decreasing direction is selected depending on the state at that time, but as the direction to move the voltage from the operating voltage V1 immediately before the power failure, the first step at the start of the maximum power tracking control is always the voltage decreasing You may make it move to a direction and follow-up control to an optimal operating point.

  This is a preferable state for the power system 15 as the output power P of the solar power generation facility is larger when the power system 15 returns from the power failure state and the solar power generation facility is inserted into the power system 15. This is to ensure that the output power is always increased when the solar radiation intensity at the time of recovery from the power failure state is smaller than the solar radiation intensity at the time of a short power failure.

  FIG. 4 shows a V-I characteristic showing the relationship between the output voltage V and the output current I of the solar cell with the solar radiation intensity as a parameter, and V-P showing the relationship between the output voltage V and the output power P of the solar cell. It is a graph of an example of a characteristic. FIG. 4 shows a VI characteristic curve and a VP characteristic curve using the solar radiation intensity as a parameter when the temperature of the solar cell is constant. The VI characteristic curve C1 is a characteristic curve when the solar radiation intensity is intermediate, the VI characteristic curve C2 is a characteristic curve when the solar radiation intensity is high, and the VI characteristic curve C3 is a characteristic curve when the solar radiation intensity is low. .

  When the solar radiation intensity is intermediate, it is the optimum operating point at which the output power becomes maximum at the coordinates C11 (V1, I1) on the VI characteristic curve C1, and the VP characteristic curve P1 becomes the maximum power P1max. The open circuit voltage is Vo1. When the solar radiation intensity is high, the coordinate C22 (V2, I2) on the VI characteristic curve C2 is the optimum operating point at which the output power becomes maximum, and the VP characteristic curve P2 becomes the maximum power P2max and is opened. The voltage is Vo2. Similarly, when the solar radiation intensity is small, the coordinates C33 (V3, I3) on the VI characteristic curve C3 are the optimum operating points at which the output power becomes maximum, and the VP characteristic curve P3 becomes the maximum power P3max. The open circuit voltage is Vo3.

  FIG. 5 is a characteristic diagram of an example of the output voltage V and the output power P of the photovoltaic power generation facility when the sunshine intensity when the power system is restored is smaller than the sunshine intensity when the power failure occurs for a short time. Now, it is assumed that the solar radiation intensity is intermediate and the vehicle is operated on the VI characteristic curve C1. At the time point t0 in the initial state when the photovoltaic power generation facility is connected to the power system 15, the output voltage V is zero, and the output voltage P is gradually increased from zero after adjusting the output voltage V to the open circuit voltage Vo. That is, at the time point t0, the output voltage target value V1r gradually decreases from the open voltage Vo by the maximum power tracking control. Along with this, the output power P of the photovoltaic power generation facility increases stepwise, and when the optimum operating point C11 on the VI characteristic curve C1 is reached at the time point t1, the output power P of the photovoltaic power generation facility is at the maximum output P1max. It becomes almost constant.

  Assuming that a short interruption occurs in the power system at time t2 in a state where the output power P of the solar power generation facility is operating at a substantially constant maximum output P1max, the output voltage V of the solar power generation facility is V−I. It is adjusted to the open circuit voltage Vo1 on the characteristic curve C1. As a result, the output power P of the photovoltaic power generation facility is adjusted from the maximum output P1max to zero at once. Then, if the sunshine intensity decreases and becomes the VI characteristic curve C3 at time t2 ′ before time t3 when the power system 15 recovers, the open circuit voltage changes from Vo1 to Vo3, and the power system recovers at time t3. When the power is turned on, the photovoltaic power generation equipment restarts. In this case, since the solar radiation intensity at the time point t3 becomes small and becomes the VI characteristic curve C3, the solar power generation facility has changed from the operating voltage V1 of the solar cell 11 immediately before the power failure to the VI characteristic curve C3. Maximum power tracking control is resumed.

  Since the first step at the start of the maximum power tracking control is always moved in the voltage decreasing direction to control the tracking to the optimum operating point, the operating point is a VI characteristic curve with low sunshine intensity as shown in FIG. It moves in the voltage decreasing direction from the intersection X3 with the operating voltage V1 immediately before the power failure on C3. Accordingly, the output power P is increased, and the output power P of the photovoltaic power generation facility is controlled to the maximum output P3max at the optimum operating point C33 on the VI characteristic curve C3. As described above, when the solar radiation intensity is reduced when the power system 15 returns from the power failure state, the output power P at the time t3 when the control of the maximum power follow-up control is resumed is controlled to increase. Thus, it is possible to prevent a temporary decrease in the output power P.

  FIG. 6 is a characteristic diagram of an example of the output voltage V and the output power P of the photovoltaic power generation facility when the sunshine intensity when the power system is restored is the same as the sunshine intensity when the power failure occurs for a short time. . In this case, the first step at the start of the maximum power follow-up control is always moved in the voltage decreasing direction and controlled to follow the optimum operating point, so that the operating point is the same as that before the short interruption as shown in FIG. It moves in the voltage decreasing direction from the intersection C11 with the operating voltage V1 immediately before the power failure on the VI characteristic curve C1 that is the sunshine intensity. Accordingly, the output power P decreases, but from the second step, the output power P moves in the direction of increasing voltage so that the output power P increases on the VI characteristic curve C1 from time t3 ′ in FIG. The maximum power follow-up control toward the optimum operating point C11 is performed, and the output power P of the photovoltaic power generation facility is controlled to the maximum output P1max. Thus, when the solar radiation intensity is the same when the power system 15 returns from the power failure state, the output power P of the photovoltaic power generation facility is temporarily reduced in the first step, but the solar radiation intensity is There is no particular problem because the output power P is larger than when it is small.

  FIG. 7 is a characteristic diagram of an example of the output voltage V and the output power P of the photovoltaic power generation facility when the sunshine intensity when the power system is restored is larger than the sunshine intensity when the power failure occurs for a short time. As shown in FIG. 7, when the sunshine intensity increases and becomes the VI characteristic curve C2 at a time point t2 'before the time point t3 when the power system 15 recovers, the open circuit voltage changes from Vo1 to Vo3. In this case, the first step at the start of the maximum power follow-up control is always moved in the voltage decreasing direction to perform follow-up control to the optimum operating point. Therefore, as shown in FIG. It moves in the voltage decreasing direction from the intersection X2 with the operating voltage V1 immediately before the power failure on the I characteristic curve C2. Accordingly, the output power P decreases, but from the second step, the output power P moves in the direction of increasing the voltage so that the output power P increases. Therefore, from the time point t3 ′ in FIG. 7 on the VI characteristic curve C2. Maximum power follow-up control toward the optimum operating point C22 is performed, and the output power P of the photovoltaic power generation facility is controlled to the maximum output P2max. Thus, when the solar radiation intensity is large when the power system 15 returns from the power failure state, the output power P of the photovoltaic power generation facility is temporarily reduced in the first step, but the solar radiation intensity is reduced. Since the output power P is larger than that of the case, there is no problem.

  In this way, when the power system 15 returns from the power failure state and controls the solar cell voltage to follow the optimum operating point, the power system 15 is moved in the voltage decreasing direction from the operating voltage of the solar cell immediately before the power failure. When the solar radiation intensity when 15 returns from the power failure state is smaller than the solar radiation intensity during a short power failure, the output power always increases. Thereby, when the solar radiation intensity is decreasing, the optimum operating point can be reached earlier by one step, and the maximum output P3max can be reached earlier. When the solar radiation intensity is not decreasing, the optimum operating point is reached later by one step, but the output power P of the photovoltaic power generation equipment is larger than when the solar radiation intensity is small, so that Delay is allowed.

  Next, FIG. 8 is a block diagram of a control device for a photovoltaic power generation facility according to the second embodiment of the present invention. This second embodiment is different from the first embodiment shown in FIG. 1 when the power system 15 is determined to be in a power outage state by the system state determination unit 22 of the solar cell 11 immediately before the power outage. An output value storage unit 24 for storing the output value is additionally provided. When the power system 15 returns from the power failure state, the maximum power follow-up control unit 18 performs solar power when restarting at the operating voltage of the solar cell immediately before the power failure. It is determined whether or not the output value of the battery 11 is greater than or equal to the output value immediately before stopping stored in the output value storage unit 24. When the output value of the solar cell 11 is equal to or greater than the output value immediately before stopping, the operation voltage storage unit 23 stores the output value. When the output value of the solar cell 11 is less than the output value immediately before stopping, the solar cell immediately before the power failure stored in the operating voltage storage unit 23 is moved. 11 working voltage to under voltage It is moved in a direction, in which so as to follow the control voltage of the solar cell 11 to the optimum operating point. The same elements as those in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  When the system state determination unit 22 determines that the power system 15 is in a power failure state, the output value storage unit 24 outputs the solar cell 11 immediately before the power failure based on the output voltage Vd and the output current Id of the solar cell 11. The power P1 is calculated and stored. That is, the output value storage unit 24 always calculates the output power P of the solar cell 11 based on the output voltage Vd and the output current Id of the solar cell 11, and the power system 15 is disconnected from the system state determination unit 22. When the notification of the state is received, the output power P at that time is stored as the output power Px of the solar cell 11 immediately before the power failure.

  When the maximum power follow-up control unit 18 receives notification from the system state determination unit 22 that the power system 15 has been restored, the maximum power tracking control unit 18 stores it in the operating voltage storage unit 23 based on the output voltage Vd and the output current Id of the solar cell 11. The output power P at the operating voltage V1 of the solar cell immediately before the power failure is obtained as the output power Py of the solar cell 11 at the time of restart, and the output power Py of the solar cell 11 at the time of restart is stored in the output value storage unit 24 It is determined whether or not the output power Px is equal to or greater than the previous output power.

  When the output power Py of the solar cell 11 at the time of restart is equal to or higher than the output power Px immediately before the stop, the operation voltage is moved from the operating voltage of the solar cell 11 immediately before the power failure stored in the operating voltage storage unit 23 in the voltage increasing direction. Thereby, the maximum power follow-up control adapted to the VI characteristic curve in which the solar radiation intensity when the power system 15 returns from the power failure state is larger than the solar radiation intensity at the time of the power failure for a short time becomes possible.

  On the other hand, when the output power Py of the solar cell 11 at the time of restart is less than the output value immediately before the stop, the solar cell 11 is moved in the voltage decreasing direction from the operating voltage of the solar cell 11 immediately before the power failure stored in the operating voltage storage unit 23. The voltage of the battery 11 is controlled to follow the optimum operating point. Thereby, the maximum power follow-up control adapted to the VI characteristic curve in which the solar radiation intensity when the power system 15 returns from the power failure state is smaller than the solar radiation intensity at the time of the power failure for a short time becomes possible.

  FIG. 9 shows the VI characteristics and VP characteristics of the photovoltaic power generation facility when the output power Py of the solar cell 11 at the time of restart is equal to or higher than the output power Px immediately before the stop in the second embodiment of the present invention. It is an example of a graph. As shown in FIG. 9, during normal times, the output control unit 19 controls the operation at the optimum operating point C11 {coordinate C11 (V1, I1)} at which the output power on the VI characteristic curve C1 is the maximum output P1max. ing. In this state, when the power system 15 is in a power failure state, the operating voltage storage unit 23 stores the operating voltage V1 of the solar cell 11 at that time, and the output control unit 19 sets the output voltage Vd of the solar cell 11 to that of the solar cell 11. The power converter 12 is controlled via the gate drive circuit 20 so that the open circuit voltage Vo1 is obtained, that is, the output power P1 of the solar battery 11 is zero.

  If the sunshine intensity increases before the power system 15 recovers, the VI characteristic curve C1 becomes the VI characteristic curve C2, and the open circuit voltage changes from Vo1 to Vo2. In this state, when the power system 15 returns from the power failure state, the maximum power follow-up control unit 18 immediately before the power failure stored in the operating voltage storage unit 23 on the VI characteristic curve C2 where the sunshine intensity has increased. The output power Py of the solar cell 11 at the operating voltage V1 of the solar cell 11 is obtained. And it will be determined whether this output electric power Py is more than the output electric power Px immediately before a power failure. In this case, since the output power Py is equal to or higher than the output power Px, the maximum power follow-up control unit 18 moves in the voltage increasing direction from the operating voltage of the solar cell 11 immediately before the power failure stored in the operating voltage storage unit 23. . Thereby, the maximum power follow-up control adapted to the VI characteristic curve C2 in which the solar radiation intensity when the power system 15 returns from the power failure state is larger than the solar radiation intensity at the time of a short power failure becomes possible, and the solar radiation intensity is large. Maximum power follow-up control is performed at the optimum operating point C22 at which the output power P2 on the VI characteristic curve C2 becomes the maximum output P2max.

  FIG. 10 is a characteristic diagram of an example of the output voltage V and the output power P in the operation characteristics of the photovoltaic power generation facility shown in FIG. At the time point t0 in the initial state when the photovoltaic power generation facility is connected to the power system 15, the output voltage V is zero, and the output voltage P is gradually increased from zero after adjusting the output voltage V to the open circuit voltage Vo. That is, at the time point t0, the output voltage target value V1r is gradually lowered from the open voltage Vo1 by the maximum power tracking control. Along with this, the output power P of the photovoltaic power generation facility increases stepwise, and when the optimum operating point C11 on the VI characteristic curve C1 is reached at the time point t1, the output power P of the photovoltaic power generation facility is at the maximum output P1max. It becomes almost constant.

  If the output power P of the photovoltaic power generation facility is operating at a substantially constant maximum output P1max, and if a short interruption occurs in the power system at time t2, the output voltage V of the photovoltaic power generation facility is open. The voltage is adjusted to Vo1. As a result, the output power P of the photovoltaic power generation facility is adjusted from the maximum output P1max to zero at once. If the sunshine intensity increases and changes from the VI characteristic curve C1 to the VI characteristic curve C2 at time t2 ′ before time t3 when the power system 15 recovers, the open circuit voltage changes from Vo1 to Vo2. .

  After that, when the power system is restored at the time t3, the solar power generation facility is restarted. In this case, the solar power generation facility is at the time t3 because the solar radiation intensity is a VI characteristic curve C2 having a high solar radiation intensity. The maximum power follow-up control is resumed on the VI characteristic curve C2 from the operating voltage V1 of the solar cell 11 immediately before the power failure. In that case, since the output power Py of the solar cell 11 at the time of restart is equal to or higher than the output power Px immediately before the stop, the voltage is moved in the direction of increasing voltage from the operating voltage V1 of the solar cell 11 immediately before the power failure. This is because in the case of the VI characteristic curve C2 having a high solar radiation intensity, there is a maximum output point in the direction of voltage increase from the VI characteristic curve C1. Thus, the maximum output point C22 is reached earlier by one step.

  FIG. 11 shows the VI characteristics and VP characteristics of the photovoltaic power generation facility when the output power Py of the solar cell 11 at the time of restart is less than the output power Px immediately before stopping in the second embodiment of the present invention. It is an example of a graph. As shown in FIG. 11, in normal times, the output control unit 19 controls the operation at the optimum operating point C11 {coordinate C11 (V1, I1)} at which the output power on the VI characteristic curve C1 is the maximum output P1max. ing. In this state, when the power system 15 is in a power failure state, the operating voltage storage unit 23 stores the operating voltage V1 of the solar cell 11 at that time, and the output control unit 19 sets the output voltage Vd of the solar cell 11 to that of the solar cell 11. The power converter 12 is controlled via the gate drive circuit 20 so that the open circuit voltage Vo1 is obtained, that is, the output power P1 of the solar battery 11 is zero.

  If the sunshine intensity decreases before the power system 15 recovers, the VI characteristic curve C1 becomes the VI characteristic curve C3, and the open circuit voltage changes from Vo1 to Vo3. In this state, when the power system 15 returns from the power failure state, the maximum power follow-up control unit 18 immediately before the power failure stored in the operating voltage storage unit 23 on the VI characteristic curve C3 on which the sunshine intensity is reduced. The output power Py of the solar cell 11 at the operating voltage V1 of the solar cell 11 is obtained. And it will be determined whether this output electric power Py is more than the output electric power Px immediately before a power failure. In this case, since the output power Py is less than the output power Px, the maximum power follow-up control unit 18 moves in the voltage decreasing direction from the operating voltage of the solar cell 11 immediately before the power failure stored in the operating voltage storage unit 23. . Thereby, the maximum power follow-up control adapted to the VI characteristic curve C3 in which the solar radiation intensity when the power system 15 returns from the power failure state is smaller than the solar radiation intensity at the time of the power failure for a short time becomes possible, and the solar radiation intensity is small. Maximum power follow-up control is performed at the optimum operating point C33 at which the output power P3 on the VI characteristic curve C3 becomes the maximum output P3max.

  FIG. 12 is a characteristic diagram of an example of the output voltage V and the output power P in the operation characteristics of the photovoltaic power generation facility shown in FIG. At the time point t0 in the initial state when the photovoltaic power generation facility is connected to the power system 15, the output voltage V is zero, and the output voltage P is gradually increased from zero after adjusting the output voltage V to the open circuit voltage Vo. That is, at the time point t0, the output voltage target value V1r is gradually lowered from the open voltage Vo1 by the maximum power tracking control. Along with this, the output power P of the photovoltaic power generation facility increases stepwise, and when the optimum operating point C11 on the VI characteristic curve C1 is reached at the time point t1, the output power P of the photovoltaic power generation facility is at the maximum output P1max. It becomes almost constant.

  If the output power P of the photovoltaic power generation facility is operating at a substantially constant maximum output P1max, and if a short interruption occurs in the power system at time t2, the output voltage V of the photovoltaic power generation facility is open. The voltage is adjusted to Vo1. As a result, the output power P of the photovoltaic power generation facility is adjusted from the maximum output P1max to zero at once. Then, assuming that the sunshine intensity becomes small and changes from the VI characteristic curve C1 to the VI characteristic curve C3 at the time t2 ′ before the time t3 when the power system 15 recovers, the open circuit voltage changes from Vo1 to Vo3. .

  After that, when the power system is restored at the time t3, the solar power generation facility is restarted. In this case, the solar power generation facility is at the time t3 because the solar radiation intensity is a V-I characteristic curve C3. The maximum power follow-up control is resumed on the VI characteristic curve C3 from the operating voltage V1 of the solar cell 11 immediately before the power failure. In that case, since the output power Py of the solar cell 11 at the time of restart is less than the output power Px immediately before the stop, the voltage is moved in the voltage decreasing direction from the operating voltage V1 of the solar cell 11 immediately before the power failure. This is because in the case of the VI characteristic curve C3 having a low solar radiation intensity, there is a maximum output point in the voltage decreasing direction from the VI characteristic curve C1. Thus, the maximum output point C22 is reached earlier by one step.

  Thus, when the power system 15 returns from the power failure state and controls the voltage of the solar cell 11 to follow the optimum operating point, the output power Py of the solar cell 11 at the time of restart is stored in the output value storage unit 24. When the output power Px immediately before the stop is greater than or equal to the operating voltage V1 immediately before the power failure, the voltage is increased in the direction of voltage increase. The maximum output point can be reached by one step earlier, which can contribute to the stabilization of the power system.

DESCRIPTION OF SYMBOLS 11 ... Solar cell, 12 ... Power converter, 13 ... Transformer, 14 ... Switch, 15 ... Electric power system, 16 ... Voltage detector, 17 ... Current detector, 18 ... Maximum power tracking control part, 19 ... Output control , 20 ... Gate drive circuit, 21 ... Voltage detector, 22 ... System state determination unit, 23 ... Operating voltage storage unit, 24 ... Output value storage unit

Claims (4)

In a control device for a photovoltaic power generation facility in which direct current generated by a solar cell is converted into alternating current by a power converter and supplied to an electric power system, the voltage of the solar cell is set to an optimum operating point at which the output of the solar cell is maximized. A maximum power tracking control unit that obtains a maximum output of the solar cell by performing tracking control, the system state determination unit that monitors the voltage of the power system to which the solar cell is connected and determines whether the power system is in a power failure state, and When it is determined by the system state determination unit that the power system is in a power outage state, an operating voltage storage unit that stores the operating voltage of the solar cell immediately before the power outage, and when the power system is not in a power outage state, the maximum power follow-up The output of the power converter is controlled so as to obtain the maximum output obtained by the control unit, and when the power system is in a power outage state, the power of the solar cell becomes the open circuit voltage of the solar cell. An output control unit that controls the output of the converter, and when the power system returns from the power failure state, the maximum power follow-up control unit operates the solar cell immediately before the power failure stored in the operating voltage storage unit. A control device for photovoltaic power generation equipment, which controls the voltage of the solar cell to follow an optimum operating point from the voltage. In a control device for a photovoltaic power generation facility in which direct current generated by a solar cell is converted into alternating current by a power converter and supplied to an electric power system, the voltage of the solar cell is set to an optimum operating point at which the output of the solar cell is maximized. A maximum power tracking control unit that obtains a maximum output of the solar cell by performing tracking control, the system state determination unit that monitors the voltage of the power system to which the solar cell is connected and determines whether the power system is in a power failure state, and When it is determined by the system state determination unit that the power system is in a power outage state, an operating voltage storage unit that stores the operating voltage of the solar cell immediately before the power outage, and when the power system is not in a power outage state, the maximum power follow-up The output of the power converter is controlled so as to obtain the maximum output obtained by the control unit, and when the power system is in a power outage state, the power of the solar cell becomes the open circuit voltage of the solar cell. An output control unit that controls the output of the converter, and when the power system returns from the power failure state, the maximum power follow-up control unit operates the solar cell immediately before the power failure stored in the operating voltage storage unit. A control device for photovoltaic power generation equipment, wherein the voltage of the solar cell is controlled to follow the optimum operating point by moving the voltage in a voltage decreasing direction. In a control device for a photovoltaic power generation facility in which direct current generated by a solar cell is converted into alternating current by a power converter and supplied to an electric power system, the voltage of the solar cell is set to an optimum operating point at which the output of the solar cell is maximized. A maximum power tracking control unit that obtains a maximum output of the solar cell by performing tracking control, the system state determination unit that monitors the voltage of the power system to which the solar cell is connected and determines whether the power system is in a power failure state, and When it is determined by the system state determination unit that the power system is in a power failure state, an operating voltage storage unit that stores the operating voltage of the solar cell immediately before the power failure, and the power system is in a power outage state by the system state determination unit When it is determined that there is an output value storage unit that stores the output value of the solar cell immediately before the power failure, and when the power system is not in a power failure state, the maximum output obtained by the maximum power tracking control unit is obtained. An output control unit for controlling the output of the power converter so that the output of the power converter is controlled so that when the power system is in a power failure state, the voltage of the solar cell becomes the open voltage of the solar cell. When the power system returns from the power failure state, the maximum power follow-up control unit outputs the output value of the solar cell at the time of restart at the operating voltage of the solar cell immediately before the power failure stored in the operating voltage storage unit Is greater than or equal to the output value immediately before the stop stored in the output value storage unit, and when the output value of the solar cell is equal to or greater than the output value immediately before the stop, the sun immediately before the power failure stored in the operating voltage storage unit A control apparatus for a photovoltaic power generation facility, wherein the control voltage of the solar battery is controlled to follow an optimum operating point by moving the battery from an operating voltage in a voltage increasing direction. In a control device for a photovoltaic power generation facility in which direct current generated by a solar cell is converted into alternating current by a power converter and supplied to an electric power system, the voltage of the solar cell is set to an optimum operating point at which the output of the solar cell is maximized. A maximum power tracking control unit that obtains a maximum output of the solar cell by performing tracking control, the system state determination unit that monitors the voltage of the power system to which the solar cell is connected and determines whether the power system is in a power failure state, and When it is determined by the system state determination unit that the power system is in a power failure state, an operating voltage storage unit that stores the operating voltage of the solar cell immediately before the power failure, and the power system is in a power outage state by the system state determination unit When it is determined that there is an output value storage unit that stores the output value of the solar cell immediately before the power failure, and when the power system is not in a power failure state, the maximum output obtained by the maximum power tracking control unit is obtained. An output control unit for controlling the output of the power converter so that the output of the power converter is controlled so that when the power system is in a power failure state, the voltage of the solar cell becomes the open voltage of the solar cell. When the power system returns from the power failure state, the maximum power follow-up control unit outputs the output value of the solar cell at the time of restart at the operating voltage of the solar cell immediately before the power failure stored in the operating voltage storage unit Is less than the output value immediately before the stop stored in the output value storage unit, and when the output value of the solar cell is less than the output value immediately before the stop, the sun immediately before the power failure stored in the operating voltage storage unit A control device for a photovoltaic power generation facility, wherein the control voltage of the solar battery is controlled to follow the optimum operating point by moving the battery from the operating voltage in a voltage decreasing direction.

Images