JP2013110848A - Load device and power consumption control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load device and power consumption control method for the device capable of rapidly connecting to a system after power recovery without having a power conditioner reset in the case of an instantaneous voltage drop.SOLUTION: A power supply voltage monitoring part 11 always monitors DC output voltage of a power conditioner having a DC power supply function. When the monitored DC output voltage becomes lower than a given value width, an instantaneous voltage drop determination part 12 confirms a reduction amount per unit time (gradient of reduction) of a voltage value of the DC output voltage, and determines that reduction in power supply voltage has been caused by an instantaneous voltage drop when confirming that the reduction amount is within an instantaneous voltage drop determination reference value range. When the instantaneous voltage drop determination part 12 determines that the instantaneous voltage drop has occurred, a control part 15 instructs a power consumption control part 16 to suppress power consumption, and the power consumption control part 16 performs control so as to make power consumption of a DC apparatus 17 reduce by an amount corresponding to the reduction amount of the DC output voltage.

Description

  The present invention relates to a load device connected to a power conditioner with a DC power supply function that outputs a DC voltage supplied from a power supply device to the outside, and a power consumption control method thereof.

  With the recent increase in efforts to use renewable energy, the amount of power generation is becoming a situation that cannot be ignored. In particular, solar power generation systems are rapidly expanding, and when the ratio of total power generation output becomes high, if the solar power generation systems are disconnected from the system all at once due to system disturbance, the supply-demand balance in the system will be Can collapse, causing widespread power outages. For this reason, a photovoltaic power generation system that is expected to be introduced in large quantities is required to have a function (such as a Fault Ride Through (FRT) function) such as continuing operation without being disconnected when a system disturbance occurs.

  Now, in the case of a conventional power conditioner in which all the energy of the solar cell is converted into the power system, the system voltage disappears when the voltage drops instantaneously, especially when the voltage drops to 0 [V]. Because it becomes impossible to match the phase, the gate output is stopped for a short time by performing the gate block (Gate Block). In the meantime, the conventional power conditioner controls to maintain the link voltage constant by adjusting the power from the solar cell, and immediately increases the power generation amount of the solar cell and restores the inverter output when the system recovers. Therefore, it is possible to meet the requirements of FRT.

  FIG. 6 is a diagram illustrating a configuration of a conventional power conditioner. The operation | movement corresponding to the FRT requirement of the conventional power conditioner is demonstrated using FIG. A state in which the energy generated by the solar cell 101 is converted into a voltage by the DCDC converter 103 and AC-converted by the DCAC converter 104 and output to the power system 107 while being connected to the power system 107 is a power generation state. . Here, when a voltage sag (instantaneous voltage drop) occurs, the voltage detector (VT) 108 detects the voltage sag, generates a gate block signal in the gate block circuit 111, stops the operation of the DCAC converter 104, and DCDC The operation of the converter 103 is reduced to the extent that the self-power consumption is compensated.

  When the voltage drop exceeds a predetermined time or more, the interconnection relay 106 is disconnected as a power failure, an error display (not shown) is displayed, and the power conditioner transitions to a standby state. When the voltage drop is restored within a predetermined time, the gate block circuit 111 is released, the DCDC converter 103 is operated, the energy is again extracted from the solar cell 101, and the DCAC converter 104 is operated to operate the AC voltage. Is output to the power system 107.

JP 2011-101455 A

  By the way, a power conditioner with a direct current power supply function for outputting the energy stored in the link capacitor of the DCDC converter included in the conventional power conditioner to the outside as a direct current is considered. This power conditioner with DC power supply function detects the voltage drop and shuts off the connection to the power system with the gate block, while the power consumed by the device connected to the DC output is The power stored in the link capacitor is released, and the power conditioner control system is reset when the power for controlling the power conditioner itself is exhausted. Since it becomes impossible to connect to the power system, it is not possible to meet the above-mentioned FRT requirements.

  In addition, devices connected to the DC output are normally controlled so that the power consumption is constant. Therefore, if the link voltage of the power conditioner, which is the power supply source, decreases, a larger amount of current is consumed accordingly. This will accelerate the drop in the link voltage, so even if the power consumed by the equipment connected to the DC output is a little larger than the amount of power generated by the solar cell, In some cases, the control system is reset, the control system is reset, and connection to the power system cannot be performed promptly after power is restored, making it impossible to meet the FRT requirements described above.

  The present invention has been made in view of such problems, and an object of the present invention is to connect to the power system promptly after power recovery without resetting the power conditioner for an instantaneous drop. It is an object to provide a load device and a power consumption control method thereof.

  In order to achieve the above object, the present invention converts a DC voltage supplied from a power supply device into an AC voltage by an inverter, grids the power system via a grid connection protection device, and supplies it from the power supply device. A load device connected to a power conditioner with a DC power supply function for outputting the DC voltage to the outside, and when the DC voltage output from the power conditioner with a DC power supply function is reduced, the DC in unit time Check the amount of voltage decrease, and if the amount of decrease in DC voltage per unit time is within the range of the predetermined amount of decrease, determine that an instantaneous voltage drop has occurred in the power system and respond to the amount of decrease in DC voltage. Power consumption is reduced.

  It is preferable that the range of the predetermined decrease amount can be set in advance. In addition, when the direct current voltage of the power conditioner with the direct current power supply function fluctuates after determining that an instantaneous drop has occurred in the power system, it is preferable to change the amount of power consumption suppressed according to the fluctuation of the direct current voltage. .

  In addition, the present invention converts the DC voltage supplied from the power supply device into an AC voltage by an inverter, grids the power system via the grid connection protection device, and converts the DC voltage supplied from the power supply device. A method of controlling power consumption of a load device connected to a power conditioner with a DC power supply function that is output to the outside, wherein the DC in a unit time when the DC voltage output from the power conditioner with a DC power supply function decreases A step of confirming a voltage decrease amount, and when the DC voltage decrease amount per unit time is in a predetermined decrease amount range, it is determined that an instantaneous drop has occurred in the power system, and the DC voltage decrease amount And a step of suppressing power consumption according to the above.

  Since the present invention operates so as to suppress the voltage drop of the link capacitor during the voltage sag, the power conditioner is not reset with respect to the voltage sag and can be quickly connected to the power system after power recovery. It becomes possible.

It is a figure which shows the structure of the power conditioner with a direct-current power supply function to which the load apparatus of this invention is connected. It is a figure which shows the state by which the load apparatus of this invention was connected to the power conditioner with a DC power supply function. It is a lineblock diagram of a load device concerning an embodiment of the invention. It is a float chart explaining operation | movement of the load apparatus which concerns on embodiment of this invention. It is a timing chart explaining operation | movement of the load apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the conventional power conditioner.

  Before describing the embodiment of the present invention, first, a power conditioner with a DC power feeding function to which the load device of the present invention is connected will be described. FIG. 1 is a diagram showing a configuration of a power conditioner with a DC power feeding function to which a load device of the present invention is connected. In addition to the function of the power conditioner, the power conditioner with a direct current power supply function has a function of direct current power supply that outputs the energy stored in the link capacitor to the outside as a direct current.

  First, the function part of the inverter will be described. In FIG. 1, a solar cell 101 as a power supply device converts solar energy into a current. Usually, the photodiode portion of the solar cell 101 is a series-connected module, and generates a high voltage of about 200 V during power generation. The noise filter 102 prevents lightning and other external disturbances from entering. The DCDC converter 103 converts the voltage generated by the solar cell into a voltage that can be used for DCAC conversion (for example, 300 to 370 V for 200 V AC, hereinafter referred to as a link voltage). The power detector (P) 110 measures the amount of power generation. The DCAC converter 104 performs PWM (Pulse Width Modulation) control on the four switching elements, and converts the DC link voltage into a commercial 50 Hz or 60 Hz AC voltage. The voltage detector (VT) 108 measures the voltage after DCAC conversion, and the current detector (CT) 109 measures the current after DCAC conversion. Noise output to the power system 107 is eliminated by the noise filter 105. The interconnection relay 106 is turned off when disconnected from the power system 107 as necessary. The electric power system 107 is a commercial power source. The gate block circuit 111 urgently stops the DCAC converter 104 as necessary.

  Next, the function part of DC power supply will be described. In FIG. 1, the energy stored in the link capacitor of the DCDC converter 103 is branched as it is, passes through the power detector (R) 120 that detects the power of the output line, passes through the output adjustment circuit 121, Noise is removed by the noise filter 122, current is detected by the current detector (CT) 123, and output to a DC device (not shown).

  By configuring in this way, the power conditioner with a DC power feeding function outputs the power generation energy of the solar cell (PV) to the DC device and outputs the surplus to the power system 107. Further, in the case of a power conditioner with a DC power supply function, when the amount of solar radiation decreases, the DCAC converter 104 performs reverse operation to supplement the output to the DC equipment, that is, ACDC conversion is performed to remove power from the power system 107. Performs an operation to absorb energy and output it to a DC device.

  This power conditioner with DC power supply function is linked to the FRT requirement in the same process as a conventional power conditioner, when the amount of power generated by solar cells is not enough to cover the consumption of DC equipment. When the voltage is reduced and power is restored from an instantaneous drop, it becomes difficult to output the power system quickly.

  Next, the load device of the present invention will be described. FIG. 2 is a diagram illustrating a state in which the load device of the present invention is connected to a power conditioner with a DC power feeding function. The load device 125 of the present invention is a direct current device capable of controlling power consumption, and is connected to the direct current output of a power conditioner with a direct current power supply function, so that even if a voltage sag occurs, the load device 125 can be quickly connected to the power system after power recovery. Is possible.

  FIG. 3 is a configuration diagram of the load device according to the embodiment of the present invention. 3 includes a power supply voltage monitoring unit 11, a voltage sag determination unit 12, a voltage sag determination reference value storage unit 13, a voltage sag determination reference value setting unit 14, a control unit 15, and power consumption. A control unit 16 and a DC device 17 are provided.

  The power supply voltage monitoring unit 11 monitors the DC output voltage of the power conditioner with a DC power supply function. The voltage sag determination reference value setting unit 14 sets a range of voltage sag determination reference values (a range of a predetermined decrease amount). The range of the sag determination reference value is a range of a decrease amount of the DC output voltage per unit time for determining the sag, and is set in advance based on the power consumption of the DC device 17 and the power generation amount of the solar cell. To do. The voltage drop determination reference value storage unit 13 stores the set voltage drop determination reference value.

  The voltage sag determination unit 12 checks whether or not the amount of decrease in the DC output voltage per unit time of the power conditioner with a DC power supply function is within the range of the voltage sag determination reference value, In some cases, it is determined that the voltage is low. The control unit 15 instructs the power consumption control unit 16 to suppress power consumption when the voltage drop determination unit 12 determines that the voltage drop is instantaneous. The power consumption control unit 16 controls the power consumption of the DC device 17. The DC device 17 is, for example, LED lighting, a DC drive air conditioner, or the like.

  DC devices such as LED lighting are designed to be able to be driven in response to a wide range of power supply voltages. Normally, when the power supply voltage decreases, the state at that time is maintained. For example, in the case of LED lighting, the DC device operates such that the amount of current consumption is increased and the supplied power is constant in order to maintain brightness. However, if such control is performed while power is being supplied from a power conditioner with a DC power supply function, the power consumption of the DC equipment will be reduced by the power conditioner with a DC power supply function when an instantaneous drop occurs. If the amount exceeds that, the DC output voltage of the power conditioner with DC power supply function will gradually decrease.However, as the voltage decreases, the amount of current consumption increases and is stored inside the power conditioner. As a result, the control power of the power conditioner is lost before the double power generation from the sag, the power conditioner control system is reset, and the FRT requirement cannot be met. End up.

  Therefore, when the load device according to the embodiment of the present invention detects a voltage drop of the power supplied to the load device and determines that an instantaneous drop has occurred from the slope of the amount of reduction per unit time. For example, when the load device is LED lighting, the power consumption is reduced by controlling the lighting to be gradually darkened, thereby reducing the DC output voltage of the power conditioner with a DC power feeding function. Then, when the power consumption is reduced to some extent, when the drop in the power supply voltage stops, the suppression of power consumption is stopped, and control is performed so that a voltage equal to or higher than that voltage is maintained. Further, when the power supply voltage starts to rise while continuing such a control state, control is performed so that the power consumption is gradually returned to the original power consumption state in accordance with the voltage increase.

  Next, the operation of the load device according to the embodiment of the present invention will be described based on the float chart of FIG.

  First, the power supply voltage monitoring unit 11 of the load device 125 constantly monitors the DC output voltage of the power conditioner with a DC power supply function (S11). Then, the power supply voltage monitoring unit 11 determines whether or not the monitored DC output voltage has fallen below a certain value range (S12), and when it falls below the certain value range (Yes in S12), the instantaneous drop determination unit 12 Confirms the amount of decrease (gradient of decrease) per unit time in the voltage value of the DC output voltage (S13) and confirms that it is within the range of the sag determination criterion value, for example, 50 to 100 V / msec. If it is confirmed (Yes in S13), it is determined that the power supply voltage is reduced due to the instantaneous drop (S14).

  In S12, when the monitored voltage does not fall below a certain value range (in the case of No in S12), and in S13, the amount of decrease in the voltage value per unit time is not within the predetermined range (S13). In the case of No), the process returns to S11.

  When the control unit 15 determines that the instantaneous drop determination unit 12 is instantaneously low, the control unit 15 instructs the power consumption control unit 16 to suppress power consumption. The power consumption control unit 16 corresponds to the amount of decrease in the DC output voltage. Only the power consumption of the DC device 17 is controlled to be reduced. Then, the power consumption control unit 15 repeats from the monitoring of the DC output voltage to the adjustment of power consumption until the decrease in the DC output voltage stops and stabilizes (S15). During this repetition or after the DC output voltage has stabilized, for example, if the DC output voltage may increase due to an increase in the amount of power generated by the solar cell due to factors such as an increase in the amount of solar radiation, Control is performed to increase the power consumption of the DC device 17. The control in the increasing direction is increased up to a value before the start of the suppression control, that is, a state where the suppression control is not performed.

  Then, the power consumption control unit 16 controls until the DC output voltage increases and does not suppress the power (S16), and when the DC output voltage is confirmed to have returned to the original value, the instantaneous drop ends. Then, it is determined that the power has been doubled (S17), and the power consumption suppression control of the DC device 17 is terminated (S18).

  FIG. 5 is a timing chart for explaining the operation of the load device according to the embodiment of the present invention.

  The power consumption suppression control in the load device of the present invention is started when the load device detects a decrease in the DC power supply voltage (DC output voltage) of the power conditioner with a DC power supply function, which is caused by an instantaneous drop in the system voltage. Is done. When an instantaneous drop occurs in the system voltage and the DC power supply voltage decreases, the load device of the present invention starts suppressing power consumption. And the amount of suppression of current consumption is fixed when the DC power supply voltage is stabilized. After that, when the DC power supply voltage rises according to the change in solar radiation, control is performed in a direction to increase the power consumption amount according to the increased amount, and when the DC power supply voltage decreases, control is performed to reduce the power consumption.

  When power is restored from an instantaneous drop, the power conditioner with a DC power supply function releases the gate block, and when the power generation amount of the solar cell exceeds the power consumption of the load device, the DC output is generated by the power from the solar cell. When the surplus is output to the power system with AC, and the amount of power generated by the solar cell is less than the power consumption of the load device, the power received from the power system compensates for the shortage of DC output. The supply of DC power is stabilized at a specified value, and the load device of the present invention can cancel the suppression of power consumption and perform stable driving.

  In the above-described embodiment, the load device includes a DC device and a control unit that controls power consumption of the DC device, but the DC device and a control unit that controls power consumption of the DC device. Etc. may be separated.

  In the above-described embodiment, the load device according to the present invention has been described by taking the power supply device as a solar cell and taking as an example a power conditioner with a DC power supply function that supplies a DC voltage boosted from the solar cell through a booster circuit. The power supply device may be a fuel cell, a wind power generation device, a storage battery, etc., and the power conditioner to which the load device of the present invention is connected receives a DC voltage supplied from the power supply device such as a fuel cell, a wind power generation device, or a storage battery. A power conditioner with a DC power supply function that outputs to the outside may be used.

  As described above, since the present invention operates so as to suppress the voltage drop of the link capacitor during the voltage sag, the power system is promptly after the power recovery without resetting the power conditioner with respect to the voltage sag. It becomes possible to connect to.

  In addition, even if a sag occurs, the present invention suppresses power consumption so that the power generation amount of the solar cell is less than that, so that the power conditioner continues to operate until double power without losing the control power supply. it can.

DESCRIPTION OF SYMBOLS 11 Power supply voltage monitoring part 12 Instantaneous drop determination part 13 Instantaneous drop judgment reference value memory | storage part 14 Instantaneous drop judgment reference value setting part 15 Control part 16 Power consumption control part 17 DC apparatus 101 Solar cell (PV)
102, 105, 122 Noise filter 103 DCDC converter 104 Inverter 106 Interconnection relay 107 Power system 108 Voltage detector (VT)
109, 123 Current detector (CT)
110, 120 Power detection circuit 121 Output adjustment circuit 124 DC equipment 125 Load device

Claims (4)

DC power supplied from the power supply device is converted into AC voltage by an inverter and connected to the power system via the grid connection protection device, and the DC voltage supplied from the power supply device is output to the outside. A load device connected to a functional inverter,
When the DC voltage output from the power conditioner with the DC power supply function decreases, the amount of decrease in the DC voltage per unit time is confirmed, and the amount of decrease in the DC voltage per unit time is within a predetermined amount of decrease. When the load device determines that an instantaneous drop has occurred in the power system, the load device suppresses power consumption according to the amount of decrease in the DC voltage.   The load device according to claim 1, wherein the range of the predetermined decrease amount can be set in advance.   When the direct current voltage of the power conditioner with the direct current power supply function varies after determining that an instantaneous drop has occurred in the electric power system, the amount of power consumption is changed according to the variation of the direct current voltage. The load device according to claim 1 or 2. DC power supplied from the power supply device is converted into AC voltage by an inverter and connected to the power system via the grid connection protection device, and the DC voltage supplied from the power supply device is output to the outside. A method for controlling power consumption of a load device connected to a power conditioner having a function,
When the DC voltage output by the power conditioner with the DC power supply function is reduced, checking the amount of decrease in the DC voltage per unit time;
Determining that an instantaneous drop has occurred in the power system when the amount of decrease in the DC voltage in a unit time is within a predetermined amount of decrease, and suppressing power consumption according to the amount of decrease in the DC voltage; ,
A power consumption control method for a load device, comprising:

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