JP2019221036A - Output control system for photovoltaic power generation and power conditioner used for the same - Google Patents

Abstract

To provide a photovoltaic output control system for photovoltaic power generation that can be easily expanded and reduced and a power conditioner used for the same.SOLUTION: An output control system 1 for photovoltaic power generation includes: one or more solar power generators 2a to 2j; a plurality of power conditioners 3a to 3j; a storage battery 4; a DC bus 5 connected to an output terminal of each solar generator, input terminals of the power conditioners, and the input and output terminals of the storage battery; and a control unit 6 for performing on and off control of the power conditioners based on a direction and/or amount of current flowing to the input and output terminals of the storage battery. Each of the power conditioners has an output terminal connected to an output terminal on the system side. When switched on or off by the control unit, the output is increased or decreased by a change amount that makes a fluctuation rate of power flowing to the output terminal on the system side less than a desired value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an output control system for photovoltaic power generation that converts a DC output of a solar generator into an AC output and outputs the AC output to a power system, and a power conditioner used for the system.

  Conventionally, as shown in FIG. 10, one central large-sized power conditioner 101, one or more sets, for example, ten sets of solar power generators 102a to 102j, a storage battery 103, an output terminal of the solar power generator, and power An output control system 100 of a photovoltaic power generation including an input terminal of a conditioner and a DC bus 104 connected to an input / output terminal of a storage battery is known. The solar power generators 102a to 102j constitute a DC output unit including a solar cell having a plurality of solar cell panels and a DC / DC converter having an MPPT control or a PWM control function.

  For example, Patent Literature 1 discloses a system that controls power generation by solar power generation using one power conditioner (see FIG. 1 of Patent Literature 1).

JP-A-2017-195667

  The large central power conditioner not only has a large physical size, but also has difficulty in flexibly coping with system expansion and contraction. When increasing the number of solar cell panels to be connected, it was necessary to replace with a larger power conditioner or to prepare another power conditioner exclusively for the increased amount. When another power conditioner is prepared, control for suppressing output fluctuation to the power system is required, which leads to complication of the system.

  On the other hand, when reducing the number of solar cell panels to be connected, the physical size does not decrease unless the power conditioner is replaced with a smaller power conditioner.

  The present invention has been made in order to solve the problems of the above-described conventional example, and provides an output control system for a photovoltaic power generation capable of easily expanding and reducing the system, and a power conditioner used therefor. Aim.

  In order to achieve the above object, an output control system for photovoltaic power generation according to the present invention includes one or more solar power generators, a plurality of power conditioners, a storage battery, an output terminal of the one or more solar power generators, The input terminal of the power conditioner, and the DC bus connected to the input / output terminal of the storage battery, and the direction and amount of current flowing to the input / output terminal of the storage battery, based on one or more values, A control unit for performing on / off control of a plurality of power conditioners, wherein each of the plurality of power conditioners has an output terminal connected to a system-side output terminal, and is switched on by the control unit. In this case, the output is increased from 0 kW to a predetermined output by a predetermined change amount that makes the fluctuation rate of the power flowing to the output terminal on the system side less than a desired value, and is turned off by the control unit. Characterized in that it comprises an output decrease circuit for reducing the output at the amount of change when it is switched to 0 kW.

  Further, the control unit increases the number of power conditioners to be turned off when the current flowing to the input / output terminal of the storage battery is output to the DC bus, and when the current is input from the DC bus or When stopped, it is preferable to increase the number of power conditioners to be turned on.

  Further, the output increasing / decreasing circuit has a change amount setting unit for setting the change amount, and the change amount setting unit is electrically insulated from an input end and an output end of each power conditioner. It is preferred to have a physical switch to determine the volume.

  Further, the output increasing / decreasing circuit has a change amount setting unit for setting the change amount, and the change amount setting unit stores a change amount in a storage unit and an input terminal and an output terminal of each power conditioner. It is preferable to include a setting circuit that is insulated and sets and records the amount of change in the storage unit.

  In addition, it is preferable that a connection unit that detachably electrically connects the setting circuit to the storage unit is provided between the storage unit and the setting circuit.

  Further, the power conditioner of the present invention includes an output terminal of one or more solar power generators, an input terminal of a plurality of power conditioners, and a DC bus connected to an input / output terminal of a storage battery, and A control unit that performs on / off control of the plurality of power conditioners based on at least one of the direction and amount of current flowing to the input / output terminal, an output control system for photovoltaic power generation. In the power conditioner, the output terminal of the power conditioner is connected to the output terminal of the system side, the power of the power flowing to the output terminal of the system side when switched on by the control unit. The output is increased from 0 kW to a predetermined output with a predetermined change amount in which the fluctuation rate is less than a desired value, and when the control unit switches off the output, the change amount is Characterized in that it comprises an output decrease circuit for reducing the force to 0 kW.

  Further, the output increasing / decreasing circuit has a change amount setting unit for setting the change amount, and the change amount setting unit is electrically insulated from an input end and an output end of each power conditioner. It is preferred to have a physical switch to determine the volume.

  Further, the output increasing / decreasing circuit has a change amount setting unit for setting the change amount, and the change amount setting unit stores a change amount in a storage unit and an input terminal and an output terminal of each power conditioner. It is preferable to include a setting circuit that is insulated and sets and stores the amount of change in the storage unit.

  In addition, it is preferable that a connection unit that detachably electrically connects the setting circuit to the storage unit is provided between the storage unit and the setting circuit.

  When the power conditioner of the present invention is switched on or off, the output increases from 0 kW to a predetermined output with a predetermined change amount in which the fluctuation rate of the power flowing to the output terminal on the system side is less than a desired value. Or an output increasing / decreasing circuit that reduces the output from 0 kW to 0 kW. For this reason, in the output control system for photovoltaic power generation using the power conditioner, the control unit performs on / off control of the power conditioner without considering output fluctuations to the power system when performing output control. It only needs to be performed, and as a result, the system can be expanded and reduced only by changing the number of power conditioners.

The block diagram of the output control system of the photovoltaic power generation which concerns on one Embodiment of this invention. 5 is a processing flowchart executed by a control unit. The front view of a power conditioner. The side view of a power conditioner. The back view of a power conditioner. FIG. 2 is a block diagram of a power conditioner. 9 is a flowchart of an output increase / decrease process. (A) is a graph of the inverter circuit output control when the power is on, and (b) is a graph of the inverter circuit output control when the power is off. The front view of the modification of a power conditioner. The block diagram of the output control system of the conventional solar power generation.

  The output control system for photovoltaic power generation according to the present invention is a small-output type power conditioner (hereinafter, abbreviated as PCS (Power Conditioning Subsystem)) that stably outputs a predetermined output after the power is turned on. A soft start function that increases the output from 0 kW to a predetermined output (unit: kW, hereinafter the same) with a change amount required for the output system when the power is off, and a software that reduces the output from the power when the power is turned off to 0 kW A plurality of PCSs having a stop function are used. The plurality of PCSs and the storage battery are connected to a DC bus, and the number of PCS to be turned on is controlled according to the charge / discharge state of the storage battery. By employing this configuration, a large central PCS is not required, space can be saved, and the system can be expanded and reduced only by increasing or decreasing the number of PCSs. The output change amount changes according to the total number of PCS used. The PCS of the present invention employs a configuration in which the amount of change in the soft start and the soft stop is set by a circuit or a switch electrically insulated from the DC bus. As a result, it has high noise immunity to lightning and the like, and enables more flexible expansion and contraction of the system.

  Hereinafter, an output control system 1 for photovoltaic power generation according to an embodiment will be described with reference to the accompanying drawings. FIG. 1 shows the overall configuration of an output control system 1 for photovoltaic power generation. The system 1 includes one or more, in this embodiment, ten solar power generators 2a to 2j, a plurality of, in this embodiment, ten PCSs 3a to 3j, a storage battery 4, a DC bus 5, and PCSs 3a to 3j. / Off control. Solar power generators 2a to 2j each include a solar cell having a plurality of solar cell panels, and a DC output unit including a DC / DC converter with an MPPT control function for converting the electric power generated by the solar cell panels into DC and outputting the converted DC. Is composed. Each output terminal of the PCSs 3a to 3j is connected to an output terminal on the system side. The DC bus 5 is connected to output terminals of the solar power generators 2a to 2j, input terminals of the PCSs 3a to 3j, and input / output terminals of the storage battery 4. The control unit 6 receives information on the direction and amount of current flowing through the input / output terminal of the storage battery 4 from the measuring device 6a. The control unit 6 outputs a power-on signal or a power-off signal to the PCSs 3a to 3j based on at least one of the direction and amount of current flowing to the input / output terminal of the storage battery 4.

  The control unit 6 increases the number of PCS to be turned off when output to the DC bus 5 based on information on the direction and / or amount of current flowing to the input / output terminal of the storage battery 4, and inputs the PCS from the DC bus 5. If the input is stopped or the input is stopped, control is performed to increase the number of PCS to be turned on.

  FIG. 2 shows a processing flowchart relating to power plant operation performed by the control unit 6. At the start of operation, it waits until the voltage of the storage battery 4 is equal to or higher than a predetermined value or the moving average value of the charging current for a predetermined time T1 is equal to or higher than a predetermined value (No in step S1). Is satisfied (Yes in step S1), the PCS activation number control shown in the subsequent flow is performed. The predetermined time T1 refers to a time required for the control unit 6 to check the power generation tendency that changes depending on the weather of the solar power generators 2a to 2j, and is T1 = 3 to 10 minutes in the present embodiment.

  First, the control unit 6 starts n PCSs (where n = (storage battery charging current / rated DC current for one PCS)) (step S2). If the moving average value of the charging current of the storage battery 4 during the predetermined time T1 is in the discharging state (Yes in step S3) and the value exceeds the rated DC current value for one PCS (Yes in step S4), the time T2 After the lapse of time, the power of one PCS is turned off (step S5). The time T2 is a time for preventing chattering of the system, and means, for example, a time of about 30 seconds to 1 minute. If all the PCSs have not been powered off (No in step S6), the process returns to step S3. When all the PCSs are turned off (Yes in step S6), the power plant operation stop processing is performed (step S7), and the process returns to step S1.

  When the moving average value of the current of the storage battery 4 is not in the discharging state, that is, in the stopped or charged state (No in step S3), when the value is equal to or less than the rated DC current value of one PCS (No in step S8). ), And return to step S3. If the moving average value of the current of the storage battery 4 is stopped or in the charged state (No in step S3) and the value exceeds the rated DC current value of one PCS (Yes in step S8), the PCS1 after the elapse of the time T2. The power is turned on for each of the units (step S9). While all the PCSs are not powered on (No in step S10), the process returns to step S3 after the processing in step S9. If all the PCSs are turned on (Yes in step S10) and the voltage of the storage battery 4 or the SOC (remaining amount) is less than a predetermined value (No in step S11), step 3 is performed. Return to On the other hand, if the voltage of the storage battery 4 or the SOC (remaining amount) is equal to or higher than a predetermined value (Yes in step S11), it is determined that the battery is overcharged, the power plant is abnormally stopped, and the process is terminated. finish.

  3 is a front view of the PCSs 3a to 3j, FIG. 4 is a side view, and FIG. 5 is a bottom view. Each drawing shows the actual size (mm) of the PCS. The conventional central type PCS is of a size that can be stored in a board, but the PCSs 3a to 3j have an advantage that they are relatively small and take up little space, so that they can be easily arranged near a solar cell panel. ing.

  As shown in FIG. 3, when the PCSs 3 a to 3 j are switched on by the control unit 6, the output is scheduled to be from 0 kW with a variation amount that makes the fluctuation rate of the power flowing to the output terminal on the system side less than a desired value. , For example, the rated output, and when the control unit 6 switches the output off, the control unit 6 includes output increase / decrease circuits 7a to 7j that reduce the output from the off state to 0 kW by the change amount. . The output increase / decrease circuits 7a to 7j include change amount setting units 11a to 11j (see FIG. 6) for setting the change amounts, respectively. The change amount setting section 11a has a change amount setting circuit 13a (see FIG. 6). As shown in FIG. 3, the setting circuit 13a includes a display unit 131 for displaying a change amount, a change amount setting start button 132, a numerical value increase / decrease button 133, a change amount setting button 134, and a programmable logic for controlling these. And a device (hereinafter, referred to as a PLD (abbreviation of programmable logic device)) 135 (see FIG. 6). After the change amount setting start button 132 is pressed, the numerical value increase / decrease button 133 is operated, and when the change amount displayed on the display unit 131 reaches a desired value, the change amount setting button 134 is pressed. And set the value.

  FIG. 6 shows the configuration of the PCS 3a as an example. The PCSs 3a to 3j have the same configuration, and for convenience of description, each component of the PCS 3a is indicated by the letter "a". The PCS 3a includes an output increasing / decreasing circuit 7a and an inverter circuit 8a. The inverter circuit 8a increases or decreases the output from 0 kW to a predetermined output, for example, a rated output, based on the inverter output control signal output from the output increasing / decreasing circuit 7a. The scheduled output may be set to a value several kW smaller than the rated output (the same applies in the following description). In this case, long-term stable operation of the PCS is expected. The inverter output control is realized by a known technique, for example, PWM control. The output increasing / decreasing circuit 7a and the inverter circuit 8a receive power directly from the DC bus 5 connected to the storage battery 4. Therefore, when the power-off signal from the control unit 6 is input, the inverter circuit 8a is not immediately stopped, and the output change rate of the system is set to a desired value based on the output control signal from the output increasing / decreasing circuit 7a. In addition, the output can be reduced from the output at the time of inputting the off signal, for example, from the rated output to 0 kW with a predetermined change amount. When a power-on signal is input from the control unit 6, the output of the inverter circuit 8a is changed from 0 kW based on the output control signal from the output increasing / decreasing circuit 7a so that the output change rate of the system falls within a desired value. The output is increased to a rated output by a predetermined change amount.

  The output increase / decrease circuit 7a includes a CPU 9a, a ROM 10a, and a change amount setting unit 11a driven by power supply from the DC bus. The change amount setting unit 11a stores a change amount determined based on the number of PCSs connected to the DC bus 5 in the storage unit 12a that keeps a state in which the written data is stored even after the power is turned off. And a setting circuit 13a for setting and recording. The storage unit 12a uses, for example, an SRAM (non-volatile memory). The setting circuit 13a includes a display unit 131, a change amount setting start button 132, a numerical value increase / decrease button 133, a change amount setting button 134, and a battery 136, centered on the PLD 135, as indicated by the dotted line. I have. The setting circuit 13a is driven by a battery 136 which is electrically insulated from the input and output terminals of each PCS and the DC bus 5. By employing this configuration, it is possible to prevent the PCS from malfunctioning with an undesired change amount due to unexpected noise such as lightning.

  The amount of change determined by the change amount setting unit 11a is set by a physical switch such as a dip switch or a jumper switch instead of the storage unit 12a and the setting circuit 13a, and the CPU 9a sets the amount of change determined by the electric resistance value. May be adopted. By employing this configuration, it is possible to prevent the PCS from malfunctioning with an undesired change amount due to unexpected noise such as lightning.

  FIG. 7 is a flowchart of the output increasing / decreasing process executed by the CPU 9a. When the power-on signal is input from the control unit 6 (Yes in step S20), the output is increased from 0 kW to the rated output by the change amount per minute (kW) recorded in the storage unit 12a. And outputs a control signal to the inverter circuit 8a (step S21). On the other hand, when the power-off signal is input (No in step S20, Yes in step S22), the output is reduced from the rated output to 0 kW by the change per minute (kW) recorded in the storage unit 12a. To output a control signal to the inverter circuit 8a (step S23). After the processing of step S21 or step S23, the process returns to step S20 and waits for the input of the next power off or on signal.

  FIG. 8A shows the output of the inverter circuit 8a that increases stepwise by ΔP from 0 kW to the rated output at one-minute intervals in response to a power-on signal input from the control unit 6 to the output increasing / decreasing circuit 7a. The waveform is shown. This graph shows a case where the output reaches the rated output from 0 kW in 10 minutes. FIG. 8 (b) shows the output of the inverter circuit 8a that decreases stepwise by ΔP from the rated output to 0 kW at one-minute intervals in response to a power-off signal input from the control unit 6 to the output increasing / decreasing circuit 7a. The waveform is shown. This graph shows a case where the rated output reaches 0 kW in 10 minutes.

  Depending on the region, utilities demand that the rate of change in power plant output per minute be no more than 1% or 2%. For example, in a power plant with a rated output of 1,000 kW, if the change in output per minute is required to be within 1%, it is necessary to increase or decrease the output from 0 kW to 1,000 kW with one central PCS. Requires a change per minute of 10 kW or less. However, if this is shared by the ten PCSs 3a to 3j as in the present embodiment, the change per minute may be 10 kW or less at a rated output of 100 kW. That is, the individual PCS may be controlled so that the output change per minute is 10% or less, and there is an advantage that the control accuracy is reduced by the number of PCS used. In the case of this example, in the graphs of FIGS. 8A and 8B, ΔP is 10 kW.

  FIG. 9 shows a PCS 3'a according to a modification of the PCS 3a. The same components as those of the PCS 3a are described using the same reference numerals. The PCS 3'a includes a main body portion 20 and a setting circuit 13'a that is electrically detachable from the main body portion. The main body 20 includes an outlet 21 internally connected to the storage unit 12a. The configuration of the setting circuit 13′a is the same as that of the setting circuit 13a, but includes a plug 22 that can be electrically connected to the outlet 21. By connecting this plug 22 to the outlet 21, the change amount setting unit 11a Is configured. The outlet 21 and the plug 22 function as a connection unit 23 that detachably and electrically connects the setting circuit 13'a to the storage unit 12a.

  The present invention is not limited to the configurations of the various embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, the solar power generator is not limited to the one including the DC / DC converter having the MPPT control function, and may be the one including the DC / DC converter having the PWM control function. The output control performed by each PCS is not limited to the PWM control of the inverter circuit, and is realized by, for example, a method of providing an output transistor in the inverter circuit 8a and controlling the duty ratio of an output signal applied to the gate of the output transistor. May be.

  The output increasing / decreasing circuits 7a to 7j not only supply power from the DC bus, but instead have a sub-battery. After the sub-battery inputs a power-off signal from the control unit 6, the output increasing / decreasing circuits 7a to 7j A configuration that enables operation until the stop is completed may be adopted.

  The change amount determined by the change amount setting unit 11a is provided in the setting circuit 13a with an input unit for the number of PCS connected to the DC bus, and the change amount is set based on a correspondence table between the number of connected PCs and the change amount. Alternatively, a configuration of a lookup table format may be adopted. In the case of the PCS 3a, the change amount is set by pressing the change amount setting start button 132, operating the numerical value increase / decrease button 133, and setting the change amount when the number of connected units displayed on the display unit 131 reaches a desired value. This is performed by pressing the button 134. In response to the pressing of the change amount setting button 134, the PLD 135 records the change amount in the storage unit 12a with reference to the storage unit 12a or the lookup table of the number of connected devices-change amount stored in the PLD 135 in advance. I do. The same applies to PCS3'a.

  The output control system of the photovoltaic power generation of the present invention can easily expand and reduce the system by increasing or decreasing the number of solar power generators, and can be implemented as a main system or a system using an existing large central type PCS. It can also be implemented as a subsystem that supplements the above.

1 Output control system 2a-2j for solar power generation Solar power generators 3a-3j Power conditioner (PCS)
4 Storage Battery 5 DC Bus 6 Control Unit 6a Measuring Device 7a Output Increase / Decrease Circuit 8a Inverter Circuit 9a CPU
10a ROM
11a Change amount setting section 12a Storage section 13a Setting circuit 21 Outlet 22 Plug 23 Connection section

Claims (9)

One or more solar generators,
With multiple inverters,
Storage batteries,
An output terminal of the one or more solar power generators, an input terminal of the plurality of power conditioners, and a DC bus connected to an input / output terminal of the storage battery;
A control unit that performs on / off control of the plurality of power conditioners based on one or more values of a direction and a current amount of a current flowing to an input / output terminal of the storage battery,
Each of the plurality of power conditioners has an output terminal connected to a system-side output terminal, and when the controller is turned on by the control unit, the rate of change in power flowing to the system-side output terminal is less than a desired value. An output increasing / decreasing circuit that increases the output from 0 kW to a predetermined output with a predetermined change amount, and reduces the output to 0 kW with the change amount when switched off by the control unit. The output control system of the photovoltaic power generation.   The control unit increases the number of power conditioners to be turned off when the current flowing to the input / output terminal of the storage battery is output to the DC bus, and when the current is input from the DC bus or stops inputting. 2. The photovoltaic power output control system according to claim 1, wherein the number of power conditioners to be turned on is increased when the power conditioner is turned on. The output increase / decrease circuit has a change amount setting unit that sets the change amount,
The photovoltaic power generation system according to claim 1, wherein the change amount setting unit includes a physical switch that determines the change amount and is electrically insulated from an input end and an output end of each power conditioner. Output control system. The output increase / decrease circuit has a change amount setting unit that sets the change amount,
The change amount setting unit includes a change amount storage unit, and a setting circuit that is electrically insulated from an input end and an output end of each power conditioner, and sets and records the change amount in the storage unit. An output control system for photovoltaic power generation according to claim 1.   The output control system for photovoltaic power generation according to claim 4, further comprising a connection unit that detachably electrically connects the setting circuit to the storage unit between the storage unit and the setting circuit. DC buses connected to the output terminals of one or more solar power generators, the input terminals of a plurality of power conditioners, and the input / output terminals of the storage battery, and the direction and current of the current flowing to the input / output terminal of the storage battery A control unit for performing on / off control of the plurality of power conditioners based on one or more values of the amount, a power conditioner used in an output control system of a photovoltaic power generation,
The power conditioner has an output terminal connected to a system-side output terminal, and sets a variation rate of power flowing to the system-side output terminal when the controller is turned on by the control unit to be less than a desired value. An output increasing / decreasing circuit for increasing the output from 0 kW to a predetermined output at the changed amount, and decreasing the output to 0 kW at the changed amount when switched off by the control unit. Power conditioners used in photovoltaic output control systems. The output increase / decrease circuit has a change amount setting unit that sets the change amount,
The power conditioner according to claim 6, wherein the change amount setting unit includes a physical switch that determines the change amount and is electrically insulated from an input terminal and an output terminal of each power conditioner. The output increase / decrease circuit has a change amount setting unit that sets the change amount,
The change amount setting unit includes a change amount storage unit, and a setting circuit that is electrically insulated from an input end and an output end of each power conditioner, and sets and stores the change amount in the storage unit. A power conditioner according to claim 6. 9. The power conditioner according to claim 8, further comprising a connection unit that detachably electrically connects the setting circuit to the storage unit between the storage unit and the setting circuit. 10.