WO2015016006A1 - System and method for controlling solar power generation system - Google Patents

Abstract

The present invention is a technology for optimally controlling the voltage during a power suppression release. A system for controlling a solar power generation system has an inverter (21), a measurement unit (22), an MPPT + power control unit (23), an AVR (24), and a PWM (25). The MPPT + power control unit (23) has a function unit for MPPT for calculating an operating voltage command value of a PV array (1) on the basis of an operating voltage and output current value of the PV array (1) as measured by the measurement unit (22), and a function unit of for power control unit for control by a voltage command output by maximum power point tracking at all times from sunrise until sunset, inclusive even of when insolation is low.

Description

Control system and control method for photovoltaic power generation system

The present invention relates to a control system and control method for a photovoltaic power generation system.

A photovoltaic power generation system (PV system) is a PV array in which solar cell modules (PV modules) are combined, and a power conditioner (PCS) that converts the operation of the PV array into a power form that actually uses the generated DC power. Consists of. The maximum power that can be taken out from the PV array varies depending on the operating environment such as temperature and solar radiation. A combination of voltage and current at which the PV array is operating is referred to as an operating point, but the operating point (maximum power point) at which the maximum generated power can be extracted also varies depending on the operating environment. For this reason, most PV systems incorporate a maximum power point tracking mechanism (MPPT) in the PCS that controls the operating point to track the maximum power point.

For example, when selling electric power generated by a PV array to an electric power company, in order to supply electric power to a commercial electric power system constructed by the electric power company, DC power is converted into alternating current so as not to disturb the commercial electric power system. And it is necessary to adjust the voltage and frequency according to the commercial power system. The PCS generates a voltage control command value by MPPT, converts it to a current control command value by proportional integral (PI) control according to the difference from the operating voltage of the PV array, and gate control signal based on the current control command value And the AC power is adjusted by a switching operation by PWM control of the inverter.

∙ The conversion capacity of PCS is usually set to a level that allows a slight margin from the rated power generation of the PV array to be controlled. For this reason, the power generation amount of the PV array may exceed the PCS conversion capacity, for example, when the temperature is low and the solar radiation is strong, or when the processing capacity deteriorates due to deterioration over time. In addition, the PCS may fail if power generation is maintained, such as when abnormal heating of the PCS occurs for some reason. In order to cope with such a situation, a power suppression function is added to the PCS. The power suppression function is a function of continuing power generation while avoiding the occurrence of PCS abnormality by moving the operating point from the maximum power point to a lower generated power point. Such a power suppression mechanism may be activated to protect the power system. This is a case where the abnormality is accelerated when the power supply is continued from the PV system with respect to the abnormality such as the voltage fluctuation generated on the power system side.

A method of power suppression in PCS is disclosed in Patent Document 1, for example. The power suppression method of Patent Document 1 converts a voltage control command value generated by MPPT based on the operating voltage value and output current of the PV array into a current control command value by PI control, and converts this command value to a limiter upper limit value. This is a method of realizing power suppression by comparing and outputting a current control value as necessary. In the configuration of FIG. 1 of Patent Document 1, the voltage and current output from the PV array are measured by the measurement unit, the power value calculated therefrom is MPPT, and the measured voltage value is AVR (Automatic Voltage Regulator). Each is output. In MPPT, the voltage command value of the next step is calculated based on the measured power value, and is output to the AVR. In AVR, a current command value for PWM control is output by PI control according to the difference between the voltage measurement value and the voltage command value. The output current command value is input to the power suppression unit. In the power suppression unit, a current control value for PWM control is generated so as to suppress the generated power in accordance with the power suppression signal. This is compared with the current command value, and a current value at which the inverter conduction ratio is reduced is output. That is, when a current control value resulting from the power suppression signal is output, the current command value resulting from MPPT is replaced with this.

JP 2012-113495 A

In the power suppression method of Patent Document 1 described above, since the current command value determined according to the voltage command value output from the MPPT is continuously replaced with the current value determined from the limiter control while the power suppression is performed, the power suppression is performed. This means that the MPPT control is not being performed while the operation is being performed. Therefore, when the PV array output falls below the power suppression value due to solar radiation fluctuations during power suppression, the PV array operating point is not properly controlled and it takes time to return to the maximum power point. This will result in power loss.

Therefore, the present invention has been made to solve such a problem, and a typical object of the present invention is to provide a technique for optimally performing voltage control during cancellation of power suppression from during power suppression. is there.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

(1) A control system for a typical photovoltaic power generation system sets an operating voltage of a solar cell array, converts an inverter DC power output from the solar cell array into AC, and outputs the solar cell array A measuring unit that measures current and voltage, and a maximum power point tracking unit that calculates an operating voltage command value of the solar cell array based on the operating voltage and output current value of the solar cell array measured by the measuring unit; Have Further, the operation voltage value of the solar cell array obtained from the measurement unit is compared with the operation voltage command value of the solar cell array set by the maximum power point tracking unit, and proportional integral control is performed based on the difference. And an automatic voltage adjusting unit that generates a gate signal of the inverter based on a current command value output from the automatic voltage adjusting unit. And it has the electric power control part always controlled by the voltage command output by the maximum electric power point tracking from the sunrise to the sunset including the case of the low solar radiation.

(2) A typical solar power generation system control method is a control of a solar power generation system including an inverter, a measurement unit, a maximum power point tracking unit, an automatic voltage adjustment unit, a pulse width modulation signal generation unit, and a power control unit. Is the method. In the control method of the solar power generation system, the power control unit performs control of the solar power generation system by a voltage command output based on maximum power point tracking from sunrise to sunset, even in the case of low solar radiation.

Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

That is, a typical effect is that voltage control can be optimally performed when power suppression is canceled during power suppression. As a result, it is possible to reduce the generated power loss at the time of solar radiation fluctuation during power suppression or when shifting from the power suppression state to the normal operation state.

It is a block diagram which shows an example of a structure of the solar energy power generation system in Embodiment 1 of this invention. In Embodiment 1 of this invention, it is a flowchart which shows an example of maximum electric power point tracking. In Embodiment 1 of this invention, it is a figure which shows an example of the voltage-power characteristic of a solar cell array, and an operating point when electric power suppression is imposed. In Embodiment 1 of this invention, it is a time chart which shows an example of the maximum electric power point tracking control at the time of electric power suppression. It is a block diagram which shows an example of a structure of the solar energy power generation system in Embodiment 2 of this invention. In Embodiment 2 of this invention, it is a flowchart which shows an example of maximum electric power point tracking. It is a flowchart which shows an example of the determination of the voltage command value by MPPT in FIG. In Embodiment 2 of this invention, it is a time chart which shows an example of the maximum electric power point tracking control at the time of electric power suppression. In Embodiment 3 of this invention, it is a flowchart which shows an example of maximum electric power point tracking. 10 is a flowchart illustrating an example of determination of a voltage command value by MPPT in FIG. 9. In Embodiment 3 of this invention, it is a figure which shows an example of the creation method of the look-up table in the operating voltage setting method of maximum power point tracking. In Embodiment 3 of this invention, it is a figure which shows an example of the lookup table produced by FIG. In Embodiment 3 of this invention, it is a time chart which shows an example of the maximum electric power point tracking control at the time of electric power suppression. In Embodiment 4 of this invention, it is a figure which shows an example of the operating voltage setting method at the time of the electric power suppression cancellation | release using the threshold value determined from the minimum operating voltage of a photovoltaic power generation system. In Embodiment 5 of this invention, it is a flowchart which shows an example of the control which outputs the command value of a constant voltage as a part of maximum power point tracking control also in the case of the fixed voltage operation | movement at the time of low solar radiation. In Embodiment 5 of this invention, it is a figure which shows an example of the voltage-power relationship in the solar energy power generation system for description of the constant voltage control at the time of low solar radiation. In Embodiment 5 of this invention, it is a time chart which shows an example of the maximum electric power point tracking control at the time of electric power suppression.

In the following embodiments, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant and one is the other. There are some or all of the modifications, details, supplementary explanations, and the like. Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say. Similarly, in the following embodiments, when referring to the shapes, positional relationships, etc. of the components, etc., the shapes are substantially the same unless otherwise specified, or otherwise apparent in principle. And the like are included. The same applies to the above numerical values and ranges.

[Outline of the embodiment]
First, an outline of the embodiment will be described. In the present embodiment, a technique for optimally performing voltage control when canceling power suppression is realized. Specifically, a method of enabling MPPT control even when power is suppressed and continuing MPPT even when power suppression is canceled, and further, when calculating the operating voltage command value of the solar cell array after canceling power suppression, a photovoltaic power generation system In this method, the MPPT voltage command value calculation method is changed according to the magnitude relationship between the voltage threshold value determined from the operation lower limit value and the voltage measurement value. In order to enable the MPPT control at the time of power suppression, the voltage command value for controlling the state of the solar cell array is not compared with the current control value that causes power suppression in the state converted to the current control signal, but replaced by the voltage The control value may be updated by comparing the power corresponding to the control value with the power value to be suppressed.

Next, in the outline of the embodiment, a control system and a control method of a typical solar power generation system will be described. In the outline of the present embodiment, as an example, the description will be given with parentheses corresponding constituent elements, reference numerals and the like in parentheses.

(1) The control system (the power conditioner 2 of FIG. 1 and the power conditioner 2a of FIG. 5) of the typical photovoltaic power generation system of this Embodiment sets the operating voltage of a solar cell array (PV array 1). And an inverter (inverter 21) that converts DC power output from the solar cell array into AC, a measurement unit (measurement unit 22) that measures current and voltage output from the solar cell array, and the measurement unit. A maximum power point tracking unit (MPPT + MPPT of the power control unit 23, MPPT23a) that calculates an operating voltage command value of the solar cell array based on the measured operating voltage and output current value of the solar cell array. Further, the operation voltage value of the solar cell array obtained from the measurement unit is compared with the operation voltage command value of the solar cell array set by the maximum power point tracking unit, and proportional integral control is performed based on the difference. An automatic voltage adjustment unit (automatic voltage adjustment unit 24) that performs the above and a pulse width modulation signal generation unit (pulse width modulation signal generation) that generates a gate signal of the inverter based on a current command value output from the automatic voltage adjustment unit Part 25). And it has the power control part (the power control part of the power control part 23, the power control part 23b) always controlled by the voltage command output by the maximum power point tracking from the sunrise to the sunset including the case of the low solar radiation.

(2) A typical solar power generation system control method according to the present embodiment includes an inverter, a measurement unit, a maximum power point tracking unit, an automatic voltage adjustment unit, a pulse width modulation signal generation unit, and a power control unit. It is the control method (FIG. 2, FIG. 6 and FIG. 7, FIG. 9, FIG. 10, FIG. 15) of a photovoltaic system. In the control method of the solar power generation system, the power control unit (the power control unit of the MPPT + power control unit 23 in FIG. 1 and the power control unit 23b in FIG. 5) controls the solar power generation system from sunrise to sunset. Up to and including the case of low solar radiation, the voltage command output always follows the maximum power point.

Hereinafter, each embodiment based on the outline of the above-described embodiment will be described in detail based on the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted.

[Embodiment 1]
The control system and control method of the photovoltaic power generation system according to Embodiment 1 will be described with reference to FIGS.

<System configuration>
First, the structure of the solar power generation system in this Embodiment is shown in FIG. FIG. 1 is a block diagram illustrating an example of the configuration of the photovoltaic power generation system according to the present embodiment. More specifically, FIG. 1 shows an example of the configuration of a power conditioner that enables MPPT control even when power is suppressed.

The solar power generation system includes a solar cell (PV) array 1, a power conditioner 2 connected to the PV array 1, and a power system 3 connected to the power conditioner 2.

The power conditioner 2 includes an inverter 21, a measurement unit 22, a maximum power point tracking unit (MPPT) + power control unit 23, an automatic voltage adjustment unit (AVR) 24, and a pulse width modulation signal generation unit (PWM) 25. It consists of.

The inverter 21 is an inverter that sets the operating voltage of the PV array 1 and converts DC power output from the PV array 1 into AC.

The measuring unit 22 is a measuring unit that measures the current and voltage output from the PV array 1.

The MPPT + power control unit 23 includes an MPPT function unit and a power control unit function unit. The functional unit of the MPPT is a maximum power point tracking unit that calculates the operating voltage command value of the PV array 1 based on the power (calculated from the operating voltage and the output current value) of the PV array 1 measured by the measuring unit 22. The function unit of the power control unit is a power control unit that always receives a power suppression signal as input and controls the voltage command output by MPPT from sunrise to sunset, including the case of low solar radiation. More specifically, the function unit of the power control unit has a function of setting the operating voltage of the solar cell array by the MPPT even when the power of the solar power generation system is suppressed, and also when the control voltage of the solar power generation system is kept constant. It has a function of setting the operating voltage of the solar cell array by MPPT.

The AVR 24 compares the operation voltage value of the PV array 1 obtained from the measurement unit 22 with the operation voltage command value of the PV array 1 set by the MPPT + power control unit 23, and performs proportional-integral control based on the difference. An automatic voltage adjustment unit.

PWM25 is a pulse width modulation signal generation unit that generates a gate signal of the inverter 21 based on a current command value output from the AVR 24.

In the solar power generation system, the DC power generated by the PV array 1 is converted into AC by the inverter 21 in the power conditioner 2 and is reversely flowed to the power system 3. The output current and voltage of the PV array 1 are measured by the measuring unit 22, the power value is passed to the MPPT + power control unit 23, and the voltage value is passed to the AVR 24. The MPPT + power control unit 23 obtains a power measurement value corresponding to the output power command value, and determines a voltage command value for the next step based on those values. The voltage command value used for determining the voltage command value of the next step and the power measurement value corresponding to the voltage command value are not necessarily limited to those of the immediately preceding step, but are determined according to the MPPT method to be used. Many proposals have already been made for the MPPT method, and any of these methods may be used.

<Operation flow>
In the present embodiment, a method of suppressing power in a state where MPPT control is enabled even when power is suppressed will be described by taking a hill climbing method as an example. FIG. 2 shows an operation flow of a block indicated by the MPPT + power control unit 23 in FIG. FIG. 2 is a flowchart illustrating an example of maximum power point tracking that enables maximum power point tracking control even during power suppression.

First, in step S101, an initial voltage value V ₀ , a voltage update width ΔV, and a direction sign (← + 1) are set. In step S <b> 102, V ₀ is output as the initial voltage command value, and the power measurement value P ₀ at V ₀ is acquired from the measurement unit 22. Next, in steps S103 and S104, a voltage V ₁ that is larger than V ₀ by ΔV is output as a voltage command value (V ₁ ← V ₀ + sign × ΔV), and a power measurement value P ₁ for V ₁ is obtained from the measurement unit 22. To do.

In step S105, the values of P ₀ and P ₁ are compared (P ₁ > P ₀ ?), And it is determined whether the voltage command value to be updated is in the direction in which the voltage increases or decreases. The greater the direction of P ₁ (S105-Yes), so that the next voltage instruction value becomes greater than _{V 1,} adding ΔV to _{V 1.} On the other hand, if P ₀ is larger (S105-No), ΔV is subtracted from V ₁ so as to decrease the voltage. Actual update of the voltage command value is performed in the calculation of _{V 1} at step S110, the sign of the computation time of ΔV in accordance with the magnitude relationship between _{P 0} and _{P 1,} step S106A (sign ← + 1 × sign ) or step The determination is made in S106B (sign ← −1 × sign).

Thereafter, in step S107, the power suppression value P _limit is updated. If power suppression is not required, the rated power of the PCS may be input to P _limit . In step S108, you compare the _{P 1} and _{P limit} and _{(P limit> P} 1?), The smaller the better of _{P 1} (S108-Yes), it proceeds to step S110, the voltage command value and a power measurement as an unnecessary power throttle The value is updated (V ₁ ← V ₁ + sign × ΔV, P ₀ ← P ₁ ). On the other hand, if P ₁ exceeds P _limit (S108-No), since power suppression is necessary, the search direction of the voltage command value is reversed (sign ← −1 × sign) in step S109, and step S110. Proceed to

In step S105 and step S106A or S106B, the search direction of the voltage command value is set to increase or decrease the voltage in the direction in which the power increases. Therefore, in step S109, reversing the search direction in the direction in which the power decreases. This means that the voltage command value is set.

Since the voltage command value has been updated as described above, the process returns to step S104 in FIG. 2, the power value for the new voltage command value is acquired, and the above steps are repeated.

The voltage command value output from the MPPT + power control unit 23 is input to the AVR 24 as shown in FIG. In the AVR 24, PI (proportional integration) control is performed according to the difference between the voltage measurement value obtained from the measurement unit 22 and the voltage command value obtained from the MPPT + power control unit 23, and a current command value serving as a PWM control signal is transferred to the PWM 25. Output. The PWM 25 outputs a gate signal corresponding to the current command value, changes the conduction rate of the inverter 21, and sets the operating voltage of the PV array 1 to the voltage command value. The operation voltage control of the PV array 1 by the AVR 24, PI control, PWM 25, and inverter 21 is a general control method, and can be realized by a known method.

By the above flow, it is possible to suppress power while performing voltage control by MPPT.

<Voltage-power characteristics of PV array>
The voltage-power characteristics of the PV array are shown in FIG. FIG. 3 is a diagram illustrating an example of voltage-power characteristics of a PV array and operating points when power suppression is imposed. In FIG. 3, the horizontal axis is voltage, the vertical axis is power, 30 is a voltage-power characteristic curve of the PV array, 31 is one of operating points when power suppression is imposed (point A), 32 Indicates another operating point (point B) when power suppression is imposed. MPP is the maximum power point, V _mpp is the voltage corresponding to the maximum power point, P _mpp is the power corresponding to the maximum power point, P _limit-1 is _one of the power suppression values, and P _limit-2 is another power suppression. Value.

When the voltage command value is smaller than V _mpp when the power suppression is imposed, the operating point converges within ± ΔV with the A point 31 as the center by the control shown in FIG. On the other hand, when the voltage command value is larger than V _mpp when the power suppression is imposed, the operating point converges within ± ΔV with the B point 32 as the center. If it is desired to limit the point of convergence to either one, the sign sign may be limited to either + or-in step S109 in FIG. In the case of +, it converges to the B point 32, and in the case of-, it converges to the A point 31. When converged to the point B 32, the current value is smaller than the point A 31, so there is an advantage that heat generation in the wiring portion can be suppressed.

<Time chart>
FIG. 4 shows a time chart of control according to the flow of FIG. FIG. 4 is a time chart showing an example of maximum power point tracking control during power suppression. 4, the horizontal axis represents time, the vertical axis represents the voltage command value, power, and sign, 40 represents the power value after update (P _{1 in} FIG. 2), and 41 represents the power value one step before (FIG. 2). Of P ₀ ). In FIG. 4, power suppression is applied at the position of P _limit-1 , but the value of power suppression changes to the position of P _limit-2 at Step-A. P _limit-2 is a suppression at a power value larger than P _mpp which is the maximum power point, and there is virtually no suppression. After that, at Step-B, it again changes to power suppression at P _limit-1 (see FIG. 3).

<Effect of Embodiment 1>
As described above, according to the control system and control method of the photovoltaic power generation system in the present embodiment, inverter 21, measurement unit 22, maximum power point tracking unit + power control unit 23, automatic voltage adjustment unit 24, and pulse width. By including the modulation signal generation unit 25, it is possible to realize a technique for optimally performing voltage control from the time of power suppression to the cancellation of power suppression. As a result, it is possible to suppress the generated power loss to a low level when a PV array output change occurs due to fluctuations in solar radiation during power suppression, or when shifting from the power suppression state to the normal operation state. Specifically, MPPT control can be validated even when power is suppressed, and MPPT can be continued even when power suppression is released. In order to enable the MPPT control at the time of power suppression, the voltage command value for controlling the state of the PV array 1 is replaced with a current control value that causes power suppression in a state converted to a current control signal as in the past. Instead, it can be realized by updating the control value by comparing the power according to the voltage control value with the power value to be suppressed.

[Embodiment 2]
A control system and control method for the photovoltaic power generation system according to Embodiment 2 will be described with reference to FIGS. In the following, differences from the first embodiment will be mainly described.

In this embodiment, another configuration of a power conditioner that enables MPPT control even when power is suppressed will be described. FIG. 5 is a block diagram showing an example of the configuration of a photovoltaic power generation system including a power conditioner, and FIGS. 6 and 7 are flowcharts showing an example of maximum power point tracking (the control flow of the power control unit and MPPT shown in FIG. 5). ). FIG. 8 is a time chart showing an example of maximum power point tracking control at the time of power suppression according to these flows.

<System configuration>
In FIG. 5, the power conditioner 2a includes an inverter 21, a measurement unit 22, a maximum power point tracking unit (MPPT) 23a, a power control unit 23b, an automatic voltage adjustment unit (AVR) 24, and a pulse width modulation signal. And a generation unit (PWM) 25. The difference from FIG. 1 is that MPPT 23a and power control unit 23b have separate block configurations.

The MPPT 23a is a maximum power point tracking unit that calculates the operation voltage command value of the PV array 1 based on the power (operation voltage and output current value) of the PV array 1 measured by the measurement unit 22 through the power control unit 23b. is there.

The power control unit 23b receives the voltage command value output from the MPPT 23a and the power suppression signal based on the power of the PV array 1 measured by the measurement unit 22, and includes the case of low solar radiation from sunrise to sunset. This is a power control unit that is always controlled by a voltage command output by tracking the maximum power point. More specifically, the power control unit 23b uses the MPPT to maintain a constant control voltage of the solar power generation system, a function of setting the operating voltage of the solar battery array by the MPPT even when the power of the solar power generation system is suppressed. It has a function of setting the operating voltage of the solar cell array.

In FIG. 5, the power value is provided to the MPPT 23a through the power control unit 23b. However, this configuration is not necessarily required, and the measurement unit 22 may directly input the MPPT 23a.

<Operation flow>
In FIG. 6, first, in step S201, the voltage initial value V ₀ of the voltage command value is set by MPPT. In addition, the voltage update width ΔV, sign ₀ (← + 1), sign ₁ (← + 1) are also set. In step S <b> 202, the power measurement value P ₀ at V ₀ is acquired from the measurement unit 22. Next, in step S203, from _{V 0} by a voltage update width [Delta] V to set a large voltages _{V 1} as the voltage command value _{(V 1 ← V 0 + sign} 0 × sign 1 × ΔV).

Next, in the branch of step S204, it is determined whether power suppression is imposed (power suppression signal On). If power suppression is not imposed (S204-No), the process proceeds to step S205, where the power command value of MPPT is set. Set up. This flow is repeated unless power suppression is imposed.

On the other hand, if power suppression is imposed, the process branches to step S206 in step S204 (Yes), and steps S206 to S211 are performed in order. That is, (acquires _{P (V 1) (= P} 1) in _{V 1)} step S206, performs step _{S207 (the} updated _{P limit).} Furthermore, step S208 (P _limit > P ₁ ?), Step S209 (sign ₀ ← sign ₁ , sign ₁ ← + 1 × sign ₁ ), step S210 (sign ₀ ← sign ₁ , sign ₁ ← −1 × sign ₁ ) Do. Then, step S211 (V ₁ ← V ₁ + sign ₀ × sign ₁ × ΔV, P ₀ ← P ₁ ) is performed.

In this way, immediately before monotonically increase or decrease the voltage command value by voltage update width ΔV from the voltage command value, the power measurement P ₁ continues to update to below power suppression value P _limit. This is because the voltage-power characteristics of the PV array have an upwardly convex shape as shown in FIG. 3, and therefore the power is always reduced by monotonously increasing or decreasing the voltage command value.

FIG. 7 shows a flow of determining the voltage command value by the MPPT shown in step S205 of FIG. 7, (acquires _{P 1} in _{V 1)} Step S2051, Step _{S2052 (P 1> P 0?} ), Step _{S2053 (sign 0 ← sign 1,} sign 1 ← + 1 × sign 1), step S2054 (sign ₀ ← sign ₁ , sign ₁ ← −1 × sign ₁ ), step S 2055 (V ₁ ← V ₁ + sign ₀ × sign ₁ × ΔV, P ₀ ← P ₁ ) are sequentially performed.

<Time chart>
FIG. 8 shows a time chart of control according to the flow of FIG. In FIG. 8, the horizontal axis represents time, and the vertical axis represents the voltage command value, power, sign ₁ , sign _0, and power suppression signal. In FIG. 8, it is determined whether power suppression is imposed (ON) or not (OFF) depending on ON / OFF of the power suppression signal.

<Effect of Embodiment 2>
As described above, according to the control system and the control method of the photovoltaic power generation system in the present embodiment, the MPPT 23a and the power control unit 23b are configured as separate blocks, thereby providing an effect different from that of the first embodiment. The following effects can be obtained. For example, since it is not necessary to consider power suppression in the MPPT 23a, there is an advantage that the MPPT algorithm can be easily implemented. Further, since branching to the power suppression process is determined by ON / OFF of the power suppression signal, the processing time when power suppression is not required can be shortened. As described above, since the power suppression process is separated in the configuration of the present embodiment, as the power suppression process, different power suppression methods such as using the power to be suppressed for charging the storage battery instead of suppressing the generated power, for example. There is an advantage that it is easier to introduce than the configuration of the first embodiment.

[Embodiment 3]
A control system and a control method for the photovoltaic power generation system according to Embodiment 3 will be described with reference to FIGS. In the following, differences from the first and second embodiments will be mainly described.

In this embodiment, a different control example using the configuration of FIG. 5 that enables MPPT even when power is suppressed will be described. The control flow is shown in FIG. 9 and FIG. Although it is almost the same as the control flow shown in FIGS. 6 and 7, the control when the power suppression signal is ON is different. In the control flow shown in FIGS. 6 and 7, the power command value is measured while updating the voltage command value to determine the voltage command value. In FIGS. 9 and 10, this process is replaced using a table. That is, a look-up table (LUT) of a list corresponding to the rated power generation amount of the photovoltaic power generation system is prepared in advance. In the LUT, a voltage command value is described according to the ratio of the power suppression value to the maximum generated power of the solar power generation system. An example is shown in FIGS. A time chart is shown in FIG.

<Operation flow>
9 and 10 are flowcharts showing an example of maximum power point tracking.

In FIG. 9, first, in step S301, a voltage initial value V ₀ , a voltage update width ΔV, a power difference threshold value ΔP, and sign (← + 1) are set by MPPT. Then, (acquires _{P 0} in _{V 0)} step S302, performs the step _{S303 (V 1 ← V 0 +} sign × ΔV).

Next, in the branch of step S304, it is determined whether or not power suppression is imposed (power suppression signal On). Set up. This flow is repeated unless power suppression is imposed.

On the other hand, if power suppression is imposed, the process branches to step S306 in step S304 (Yes), step S306 (updates P _limit ), step S307 (V _LUT corresponding to P _limit / P _mpp is acquired from the LUT), step _{S308 (V 1 ← V LUT)} , perform _(P (V 1) acquires (= _{P 1)} in _{V 1)} step S309.

Next, in the branch of step S310, it is determined whether P _limit −P ₁ is 0 or more and ΔP or less (ΔP ≧ P _limit −P ₁ ≧ 0?). If it is 0 or more and ΔP or less (S310—Yes), Proceeding to step S304, this flow is repeated until it is not less than 0 and not more than ΔP.

On the other hand, if P _limit −P ₁ is not less than 0 and not more than ΔP (S310—No), the process branches to step S311, and step S311 (P ₀ ← P ₁ , V ₁ ← V ₁ + sign × ΔV), step S312 ( performing _P (V 1) acquires (= _{P 1))} in V _1.

Next, in the branch of step S313, whether towards _{P 1} is greater than _{P 0 (P 1> P 0} ?) Is determined, the larger the better in _{P 1} (S313-Yes), the step S314 (sign ← + 1 × performs sign), it is larger in _{P 0} (S313-No), performs step S315 to (sign ← -1 × sign).

Next, a _(P (V 1) acquires (= _{P 1)} in _{V 1)} Step _{S316 (P 0 ← P 1,} V 1 ← V 1 + sign × ΔV), step S317. Then, in the branch of step S318, it is determined whether P _limit −P ₁ is greater than 0 and less than ΔP (ΔP> P _limit −P ₁ > 0?). If it is greater than 0 and less than ΔP (S318—Yes), step S318 is performed. The process proceeds to S304, and if it is greater than 0 and less than ΔP (S318-No), the process proceeds to step S313, and this flow is repeated.

FIG. 10 shows a flowchart for determining the voltage command value by the MPPT shown in step S305 of FIG. 10, (acquires _{P 1} in _{V 1)} Step S3051, Step _{S3052 (P 1> P 0?} ), Step S3053 (sign ← + 1 × sign ), step S3054 (sign ← -1 × sign) , step S3055 (V ₁ ← V ₁ + sign × ΔV, P ₀ ← P ₁ ) are sequentially performed.

<Characteristics of solar power generation system and lookup table>
FIG. 11 is a diagram illustrating an example of a method for creating a lookup table in the operation voltage setting method for maximum power point tracking. FIG. 12 is a diagram showing an example of the created lookup table.

In FIG. 11, the horizontal axis represents voltage, the vertical axis represents power suppression value P _limit / maximum generated power P _max , 90 is a voltage-power characteristic curve (characteristic 1) with respect to the PV array rating, and 91 is a decrease in solar radiation. The voltage-power characteristic curve (characteristic 2) of the PV array is shown.

With respect to the characteristic 1 (90) shown in FIG. 11, the maximum generated power P _max of the solar power generation system is set to 1, and the voltage command value is obtained from the characteristics of the solar power generation system for every arbitrary ratio of the electric power. For example, when the power suppression value P _limit is 0.6 with respect to P _max (P _limit / P _max = 0.6), the voltage command value is V _6L or V _6H . FIG. 12 shows an example in which this is summarized in a lookup table (LUT) for each P _limit / P _max .

The voltage command value (V _dc-low , V _dc-high ) can be one for each P _limit , and a total of two voltage command values can be taken. What is necessary is just to determine arbitrarily according to the request | requirement of a system. The voltage-power characteristics shown in FIG. 11 change due to solar radiation, temperature, shade, etc., but these generally affect the direction in which the generated power decreases. If a table is created from the characteristics of the photovoltaic power generation system with respect to the rating, the actual generated power is lower than the generated power corresponding to the voltage command value obtained from the LUT. For this reason, power suppression works in an excessive direction and does not adversely affect the photovoltaic power generation system.

Since the power generation may exceed the rated power generation amount when the weather meets certain conditions, such as on a sunny day with a relatively low temperature, the generated power corresponding to the voltage command value obtained from the LUT is obtained from P _limit . There is a possibility of growing. However, as shown in FIGS. 9 and 10, since the voltage command value corresponding to P _limit is continuously updated, P _limit is updated to a smaller value as necessary, and the required power is suppressed. Also, when there is a difference between the power value obtained from the voltage command value by the LUT and the power value assumed from the rated power generation amount, the voltage command value is set as shown in the flow from step S313 to S318 in FIG. This difference can be eliminated by the updating control.

<Time chart>
FIG. 13 shows a time chart of control according to the flow of FIGS. 9 and 10 using the LUT shown in FIG. In FIG. 13, the horizontal axis represents time, and the vertical axis represents the voltage command value, power, power suppression value P _limit / maximum generated power P _max , sign, and power suppression signal.

The situation from Steps S313 to S318 in FIG. 9 described above is shown in the vicinity of Step-C in FIG. _Assume that the characteristic 1 and the characteristic 2 in FIG. 11 are switched at Step-C as shown in the graph of P _limit / P _{mpp in} FIG. 13 due to the fluctuation of solar radiation. If P _limit / P _max = 0.6 and power suppression is working, the voltage command value from the LUT is V _{6L in} FIG. (V _6H may be used, but V _6L is used for easy understanding of the drawing.) However, when the characteristic at the time of actual operation is characteristic 2, the power suppression state is the same P _limit / P _max = 0.6. Even so, the operating voltage is slightly higher than V _9L . If the voltage command value indicated by the LUT remains, the characteristic 2 operates in the vicinity of P _limit / P _{max ≈0.4 where the} power is significantly lower than the power suppression value. The voltage command value is updated by the flow of steps S313 to S318 in FIG. 9, and the operating point is changed to near P _limit / P _max = 0.6 even in the characteristic 2. Changes in the voltage command value and power after Step-C in FIG. 13 correspond to this process.

The method using the LUT shown in the present embodiment needs to store the table in the control system, but does not need to suppress power by gradually updating V _dc , so the processing becomes faster. . In Steps A and B in FIG. 13, since the power suppression signal is ON, the voltage command value is changed by the LUT, and the power value changes sharply accordingly. On the other hand, the change in the voltage command value in the vicinity of Step-D is a change due to the hill-climbing method because the power suppression signal is OFF, and the change in power gradually changes accordingly. When both are compared, it is clear that there is a large difference in the number of steps required for the change.

<Effect of Embodiment 3>
As described above, according to the control system and the control method of the photovoltaic power generation system in the present embodiment, the power suppression value prepared in advance for the voltage setting method during power suppression and the voltage command value corresponding to this power suppression value The following effects can be obtained as effects different from those of the first and second embodiments. For example, the method using the look-up table has an advantage that the processing is fast because it is not necessary to suppress the power by gradually updating the voltage command value by storing the table in the control system.

[Embodiment 4]
A control system and a control method for the photovoltaic power generation system according to Embodiment 4 will be described with reference to FIG. In the following, differences from the first to third embodiments will be mainly described.

In this embodiment, as a different control example using the configuration of FIG. 5 that enables MPPT even when power is suppressed, after calculating the voltage command value for operating the PV array after canceling power suppression, A method for changing the method of calculating the voltage command value in the MPPT according to the magnitude relationship between the voltage threshold value determined from the operation lower limit value and the voltage measurement value will be described. This method is shown in FIG.

<Voltage-power characteristics of photovoltaic power generation system>
FIG. 14 is a diagram illustrating an example of an operating voltage setting method at the time of canceling power suppression using a threshold value determined from the minimum operating voltage of the photovoltaic power generation system. FIG. 14 shows a voltage-power characteristic curve of the photovoltaic power generation system. Characteristic 1 is a characteristic corresponding to the rated output of the system, and characteristics 2 to 4 are characteristics when the output is lower than that of characteristic 1, such as in the case of low solar radiation. The voltage V _min is the minimum operating voltage of the photovoltaic power generation system, and when only a voltage lower than this is output, the system enters a standby state or a stopped state. Therefore, when the output is lower than the characteristic (characteristic 4) in which V _min is the maximum power point (MPP) voltage, there is no need to perform MPPT control. Empirically, it is known that the ratio V _pmax / V _oc of the open circuit voltage V _oc and the maximum power point voltage V _pmax is about 0.8, but if this relationship is used, the release voltage V _oc4 of the characteristic 4 is ,
V _oc4 ≈ V _min /0.8
It becomes.

こ の With this voltage as a threshold, the MPPT voltage command value calculation method is changed according to the magnitude relationship between the operating voltage (voltage measurement value) and the threshold when power suppression is changed from ON to OFF. For example, when searching for an MPP by the hill-climbing method, the search width is changed with the threshold as a boundary, and when the binary search method is used, the initial value of the search width is changed with the threshold as a boundary. Hereinafter, switching of search methods with a threshold as a boundary will be described by taking a binary search as an example.

In the state in which power suppression is applied at the position of P _{limit in} the characteristic 1 of FIG. 14, the operating point by MPPT is either a straight line connecting A1 and B1. When the operating point is A1, if the characteristic 1 changes to the characteristic 2 due to solar radiation fluctuation or the like, the operating point moves to A2, but the power suppression is removed, so the MPPT starts searching for the maximum power point. In the binary search method, two points for determining a search range are determined, the range is divided into two, and a search is performed by comparing the representative points of the range. Therefore, you must first specify two points that determine the range.

If the operating voltage as point A2 belongs to the range 1, the operating voltage V _A of the initial value one for a point A2 of the two points _may be selected one from the inside of the two points of V _A and the threshold voltage. For example, if the voltage search width of the hill-climbing method is ΔV, depending on the difference between V _A and V _oc4 , another point that does not exceed V _oc4 from ΔV × n (n = 1, 2, 3, 4,...) Decide. This limits the search range and eliminates the possibility of specifying an excessive voltage. For example, when a transition is made from the characteristic 1 to the characteristic 3 in a state where the voltage is suppressed, there is a possibility that a voltage larger than V _oc4 is designated as one end of the search width and a voltage command value where the generated power is 0 is designated. If the voltage is lower than V _oc4 , there is no such fear.

On the other hand, when the operating point transitions from B1 to B2, the binary search is limited to V _B and V _oc4 , that is, the range 2, and the search width can be made larger than that of the range 1. The initial value of the search width is V _{oc4 at} one end, and the other end is selected from V _oc4 + ΔV × n (n = 1, 2, 3, 4,...) _That does not exceed V _B. As in the case of the A2 point of the characteristic 2, the MPP may not always be reached by the binary search alone, but in this case, the hill climbing method may be used after the binary search.

Thus, by setting the threshold value and changing the MPPT search method, the search can be performed efficiently, and the risk of searching for an inappropriate voltage command value is reduced. Furthermore, this voltage threshold can be uniquely determined with reasonableness from the minimum voltage of the photovoltaic power generation system.

In the above description, the influence of temperature was not considered, but in reality, the influence of temperature needs to be considered. The number of series modules in the system is N ₁ , the number of cells constituting the module is N ₂ , the temperature difference between the module operating temperature and 25 ° C. is ΔT, the temperature coefficient indicating the temperature dependence of the voltage is β, and the voltage variation is ΔV. Then
ΔV = β × ΔT × N ₁ × N ₂
V _oc4 = V _oc4 (25 ° C.) − _ΔV
It becomes.

Here, the module operating temperature when V _min = 350 V, β is 2 mV / ° C., and the air temperature is 25 ° C., the air temperature + 18.4 ° C. = 43.4 ° C., N ₁ = 16, N ₂ = 60 in accordance with JIS C8907: 2005. Then,
V _oc4 (25 ° C.) = 350 / 0.8 = 437.5
ΔV = 2 × 10 ⁻³ × 18.4 × 16 × 60 = 35.3
V _oc4 = 437.5-35.3 ≒ 402 (V)
It becomes.

<Effect of Embodiment 4>
As described above, according to the control system and the control method of the photovoltaic power generation system in the present embodiment, the voltage threshold value for switching the plurality of voltage command value setting methods is determined from the minimum startup voltage value of the photovoltaic power generation system, By determining the search width initial value of the binary search method with this voltage threshold as a boundary, the following effects can be obtained as effects different from those of the first to third embodiments. For example, by providing a voltage threshold and changing the MPPT search method, it is possible to search for a voltage command value efficiently, and to reduce the risk of searching for an inappropriate voltage command value.

[Embodiment 5]
A control system and a control method for the photovoltaic power generation system according to Embodiment 5 will be described with reference to FIGS. In the following, differences from the first to fourth embodiments will be mainly described.

In this embodiment, control during low solar radiation will be described. When the amount of solar radiation is small, such as at sunrise or sunset, the power conditioner performs control to fix the operating voltage of the PV array to a constant voltage instead of setting it with MPPT. Therefore, if the part that performs this constant voltage control is output as a voltage command value by MPPT, the operating voltage of the PV array can be controlled by MPPT while the power conditioner is activated. Such control can be realized by the flow shown in FIG. 15, for example, using the configuration of FIG. Consider the case of sunrise as an example of low solar radiation. The voltage-power characteristics are shown in FIG. 16, and the time chart is shown in FIG.

<Control during low solar radiation>
FIG. 15 is a flowchart showing an example of control for outputting a constant voltage command value as part of the maximum power point tracking control even during a constant voltage operation during low solar radiation. FIG. 16 is a diagram illustrating an example of a voltage-power relationship in the photovoltaic power generation system for explaining the constant voltage control during low solar radiation. FIG. 17 is a time chart illustrating an example of maximum power point tracking control during power suppression.

In FIG. 15, initial values are set in steps S401 and S402 (minimum voltage V _min , constant operating voltage V _{dc_const ′} , minimum power P _min , initial voltage value V ₀ , voltage update width ΔV, sign ← + 1, P ₀ = P _min ), the open circuit voltage _VOC is measured in step S403. If sunrise after the sunlight is weak, when the open circuit voltage _{V oc} to the characteristic 1 of Fig. 16 is lower than the minimum operating voltage _{V min} of the system, steps S403 and _S404 repeatedly _{(V OC> V min?)} , The voltage rises Wait until

As shown in characteristic 2 in FIG. 16, when V _oc reaches V _min , the process proceeds to step S405, and the photovoltaic power generation system starts power generation at a predetermined constant voltage V _{dc_const} . Unless there are special circumstances, V _{dc_const} = V _min may be set. _Even in the _case of a constant voltage operation at V _{dc_const} , it is important to output the operation voltage as the MPPT voltage command value as shown in FIGS. 15 and 17.

After that, the amount of power generation increases as the solar radiation increases, and when the generated power P (V _dc ) acquired in step S406 exceeds a certain threshold value P _min (step S407), the maximum power point is obtained from _{Vmin as} shown in characteristics 4 and 5. Since it is located on the high voltage side, it shifts to a voltage command value setting method based on a maximum power point search such as constant voltage control or hill-climbing method (steps S408 to S417). The threshold power P _min is the maximum power having such characteristics that the generated power is maximum when the voltage is V _min . In FIG. 16, the power value (= P _min ) of the maximum power point MPP3 of characteristic 3 is the threshold value.

Even when performing maximum power point operation of the MPPT, by comparing with a threshold P _min of the amount of power generation P ₁ power for the voltage command value as shown in step S410, the detection of the decrease in the generated power. When the amount of solar radiation decreases as at sunset, the generated power decreases and falls below _Pmin . At that time, the control branches to B (No) in step S410 of FIG. 15, and returns to step S403. Thereafter, according to the algorithm already described, a constant voltage operation is performed with a certain amount of solar radiation. When the amount of solar radiation further decreases, power generation is stopped and the open voltage monitoring state is entered.

As described above, it is possible to output and control the voltage value as a command value even in the case of constant voltage operation during low solar radiation. What is important is that a constant voltage value is input to the AVR as a command value, and that value is converted into an inverter control signal through the same control path as the MPPT control, thereby controlling the operating voltage of the PV array. . Thereby, the voltage of the PV array can be controlled based on the command value from the MPPT for the constant voltage operation at the time of low solar radiation represented by sunrise and sunset as well as the power suppression. That is, voltage control by MPPT is possible consistently from sunrise to sunset.

<Effect of Embodiment 5>
As described above, according to the control system and the control method of the photovoltaic power generation system in the present embodiment, the part that performs constant voltage control when the amount of solar radiation is small is configured to output a voltage command value with the MPPT. As effects different from those of the first to fourth embodiments, the following effects can be obtained. For example, a voltage value can be output as a command value and controlled even during a constant voltage operation during low solar radiation. As a result, there is an advantage that voltage control by MPPT can be consistently performed from sunrise to sunset.

Although the invention made by the present inventor has been specifically described based on the first to fifth embodiments, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, Embodiments 1 to 5 described above have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. . Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. Furthermore, the form which combines each embodiment can also be changed as the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Solar cell (PV) array, 2, 2a ... Power conditioner, 3 ... Electric power system,
DESCRIPTION OF SYMBOLS 21 ... Inverter, 22 ... Measurement part, 23 ... Maximum electric power point tracking part (MPPT) + electric power control part, 23a ... Maximum electric power point tracking part (MPPT), 23b ... Electric power control part, 24 ... Automatic voltage adjustment part (AVR) 25. Pulse width modulation signal generator (PWM),
30 ... Voltage-power characteristic curve of the solar cell array, 31 ... One of operating points when power suppression is imposed, 32 ... Another operating point when power suppression is imposed,
40 ... updated power value, 41 ... 1 step previous power value,
90: Voltage-power characteristic curve with respect to the rating of the solar cell array, 91: Voltage-power characteristic curve of the solar cell array when solar radiation is lowered.

Claims (15)

1. An inverter that sets an operating voltage of the solar cell array and converts DC power output from the solar cell array into AC;
   A measurement unit for measuring current and voltage output from the solar cell array;
   A maximum power point tracking unit that calculates an operating voltage command value of the solar cell array based on the operating voltage and output current value of the solar cell array measured by the measuring unit;
   The operation voltage value of the solar cell array obtained from the measurement unit is compared with the operation voltage command value of the solar cell array set by the maximum power point tracking unit, and proportional-integral control is performed based on the difference. An automatic voltage regulator,
   A pulse width modulation signal generation unit that generates a gate signal of the inverter based on a current command value output from the automatic voltage adjustment unit;
   From sunrise to sunset, including the case of low solar radiation, a power control unit that always controls by voltage command output by maximum power point tracking,
   A control system for a photovoltaic power generation system.
2. In the control system of the photovoltaic power generation system according to claim 1,
   The said power control part is a control system of a solar power generation system which sets the operating voltage of the said solar cell array by the said maximum power point tracking part also at the time of the electric power suppression of the said solar power generation system.
3. In the control system of the photovoltaic power generation system according to claim 2,
   The said electric power control part is a control system of the solar power generation system which sets the operating voltage of the said solar cell array by the said maximum power point tracking part, also when keeping the control voltage of the said solar power generation system constant.
4. In the control system of the photovoltaic power generation system according to claim 2,
   In the method for setting the operating voltage of the solar cell array at the time of power suppression, the power control unit compares a power measurement value for each operating voltage setting of the solar cell array at the maximum power point tracking unit with a power suppression value. A control system for a photovoltaic power generation system that determines a voltage setting value.
5. In the control system of the photovoltaic power generation system according to claim 2,
   The power control unit has a voltage setting method by the maximum power point tracking unit and a voltage setting method at the time of power suppression in an operating voltage setting method of the solar cell array at the time of power suppression. A control system for a photovoltaic power generation system that determines a voltage setting method based on a comparison between a power suppression value and a power measurement value.
6. In the control system of the photovoltaic power generation system according to claim 2,
   The power control unit has a voltage setting method by the maximum power point tracking unit and a voltage setting method at the time of power suppression in an operating voltage setting method of the solar cell array at the time of power suppression. A control system for a photovoltaic power generation system, which is selected from a list of power suppression values prepared in advance for a voltage setting method and voltage command values corresponding to the power suppression values.
7. In the control system of the photovoltaic power generation system according to claim 2,
   In the control of the photovoltaic power generation system, the power control unit has a plurality of voltage command value setting methods at the time of canceling power suppression, and sets a voltage threshold value for switching the plurality of voltage command value setting methods to the solar power generation system. A control system for a photovoltaic power generation system, determined from the minimum starting voltage value.
8. In the control system of the solar power generation system according to claim 7,
   The plurality of voltage command value setting methods include a binary search method and a hill-climbing method,
   The said binary search method is a control system of a solar power generation system which determines the search width initial value of the said binary search method on the boundary of the voltage threshold value determined from the minimum starting voltage of the said solar power generation system.
9. An inverter that sets an operating voltage of the solar cell array and converts DC power output from the solar cell array into AC;
   A measurement unit for measuring current and voltage output from the solar cell array;
   A maximum power point tracking unit that calculates an operating voltage command value of the solar cell array based on the operating voltage and output current value of the solar cell array measured by the measuring unit;
   The operation voltage value of the solar cell array obtained from the measurement unit is compared with the operation voltage command value of the solar cell array set by the maximum power point tracking unit, and proportional-integral control is performed based on the difference. An automatic voltage regulator,
   A pulse width modulation signal generation unit that generates a gate signal of the inverter based on a current command value output from the automatic voltage adjustment unit;
   A power control unit;
   A solar power generation system control method comprising:
   The said electric power control part is a control method of the solar power generation system which performs control of the said solar power generation system by the voltage command output by a maximum power point tracking always from the sunrise to the sunset including the case of a low solar radiation.
10. In the control method of the photovoltaic power generation system according to claim 9,
    The said electric power control part is a control method of the solar power generation system which sets the operating voltage of the said solar cell array by the said maximum power point tracking part also at the time of the electric power suppression of the said solar power generation system.
11. In the control method of the solar power generation system according to claim 10,
    The method for controlling a solar power generation system, wherein the power control unit sets an operating voltage of the solar cell array by the maximum power point tracking unit even when the control voltage of the solar power generation system is kept constant.
12. In the control method of the solar power generation system according to claim 10,
    In the method for setting the operating voltage of the solar cell array at the time of power suppression, the power control unit compares a power measurement value for each operating voltage setting of the solar cell array at the maximum power point tracking unit with a power suppression value. A method for controlling a photovoltaic power generation system that determines a voltage setting value.
13. In the control method of the solar power generation system according to claim 10,
    The power control unit has a voltage setting method by the maximum power point tracking unit and a voltage setting method at the time of power suppression in an operating voltage setting method of the solar cell array at the time of power suppression. A control method for a photovoltaic power generation system, wherein a voltage setting method is determined based on a comparison between a power suppression value and a power measurement value.
14. In the control method of the solar power generation system according to claim 10,
    The power control unit has a voltage setting method by the maximum power point tracking unit and a voltage setting method at the time of power suppression in an operating voltage setting method of the solar cell array at the time of power suppression. The control method of a solar power generation system which selects from the list | wrist of the electric power suppression value which prepared the voltage setting method in advance, and the voltage command value corresponding to the said electric power suppression value.
15. In the control method of the solar power generation system according to claim 10,
    In the control of the photovoltaic power generation system, the power control unit has a plurality of voltage command value setting methods at the time of canceling power suppression, and sets a voltage threshold value for switching the plurality of voltage command value setting methods to the solar power generation system. A method for controlling a photovoltaic power generation system, which is determined from a minimum starting voltage value.

Images