JP7098865B2 - Power system and battery power conditioner - Google Patents

Description

The present disclosure relates to a grid-connected electric power system, and particularly to an electric power system for controlling an adjusted electric power to a target electric power. The present disclosure also relates to a storage battery power conditioner included in this power system.

In recent years, power generation systems using renewable energy have become widespread. One example is a photovoltaic power generation system that uses sunlight. The photovoltaic system is equipped with a solar cell and a power conditioner. The solar cell generates DC power, and the power conditioner converts this DC power into AC power. The converted AC power is supplied to the power system. Solar power generation systems range from small-scale household systems to large-scale solar systems such as mega-solar systems. In such a photovoltaic power generation system, output fluctuations occur due to weather fluctuations and the like. In order to suppress this output fluctuation, a power conditioner in which a storage battery and a storage battery are connected may be provided.

For example, Patent Document 1 describes a solar cell, a first power conditioner connected to the solar cell, a storage battery, a second power conditioner connected to the storage battery, a first power conditioner, and a second power conditioner. A photovoltaic power generation system equipped with a centralized management device for management is disclosed. In this conventional photovoltaic power generation system, a centralized management device calculates an index for controlling a predetermined adjusted power to a target power, and the first power conditioner and the second power conditioner use the index in a distributed manner. It controls the output power. In such a solar power generation system, a characteristic value for limiting the input / output power at the time of charging / discharging of the storage battery is set in the second power conditioner. As this characteristic value, for example, there is a C rate. The C rate is a relative ratio of the current during charging or discharging to the total capacity of the storage battery, and 1C is when the total capacity of the storage battery is charged or discharged in one hour.

International Publication No. 2017/150376

In a conventional photovoltaic system, the total output power may change drastically. Such a sudden change in output power may occur, for example, when the C rate set in the second power conditioner is changed, which is a factor that adversely affects the power system. Therefore, there is still room for improvement in the conventional photovoltaic power generation system.

The electric power system according to the present disclosure has been conceived in view of the above circumstances, and an object thereof is to provide an electric power system and a storage battery power conditioner capable of suppressing a sudden change in the output power of the entire system. be.

The electric power system provided by the first aspect of the present disclosure includes a power control device for inputting electric power from a power generation device, a storage battery power conditioner for controlling charging / discharging of a storage battery, the power control device, and the storage battery power condition. It is provided with a power line to which a power supply is connected and connected to a power system, and a centralized management device for managing the power control device and the storage battery power conditioner. The storage battery power conditioner is used to charge the storage battery. A setting means for setting a characteristic value for limiting the input / output power at the time of discharging is provided, and the characteristic value set by the setting means is changed to a new set value, which is a specified value. It is characterized in that the current value currently set is gradually changed to the specified value. According to this configuration, since the characteristic value set in the storage battery power conditioner is changed stepwise, the input / output power limit at the time of charging / discharging of the storage battery is changed stepwise. Since the input / output power limit during charging and discharging of the storage battery is the limit of the output power of the storage battery power conditioner, when the characteristic value is changed, depending on the difference between the current value and the specified value, the storage battery power conditioner Input / output power may change rapidly. However, since the output power of the storage battery power conditioner is gradually changed by gradually changing the characteristic value, it is possible to suppress a sudden change in the output power of the storage battery power conditioner. Therefore, when changing the characteristic value in the storage battery power conditioner, it is possible to suppress a sudden change in the output power of the entire power system.

In a preferred embodiment of the power system, the centralized management device comprises a designated means for transmitting the designated value to the storage battery power conditioner, and the setting means is from the current value to the centralized management device. The characteristic value is changed stepwise up to the received specified value. According to this configuration, the storage battery power conditioner can change the set characteristic value step by step when the centralized management device instructs to change the set value of the characteristic value.

In a preferred embodiment of the power system, the storage battery power conditioner further comprises a connection determining means for determining whether or not it is connected to the power line, and the setting means is connected by the connection determining means. When it is determined that the characteristic value is not set, a predetermined value is set in the characteristic value, while when it is determined that the characteristic value is connected, the characteristic value is changed to the designated value. In a power system, when the storage battery power conditioner changes from being not connected to the power line to being connected to the power line, the output power of the storage battery power conditioner changes instantly, and the output power of the entire power system changes suddenly. I have something to do. According to this configuration, when the storage battery power conditioner changes from the state where it is not connected to the power line to the state where it is connected to the power line, the characteristic value is gradually changed from a predetermined value to a designated value by the setting means. As a result, the limit of the input / output power at the time of charging / discharging of the storage battery is changed stepwise according to the characteristic value, so that the output power of the storage battery power conditioner is gradually changed. Therefore, it is possible to suppress a sudden change in the output power of the entire power system.

In a preferred embodiment of the power system, the characteristic value is a C rate indicating the relative ratio of input / output currents during charging / discharging to the total capacity of the storage battery. According to this configuration, the input / output current at the time of charging / discharging of the storage battery can be limited by limiting the input / output current by setting the C rate.

In a preferred embodiment of the power system, the centralized management device calculates an index for controlling the adjusted power to the target power, and each of the power control device and the storage battery power conditioner uses the index. Control the individual output power based on the optimization problem used. According to this configuration, each of the power control device and the storage battery power conditioner controls the individual output power in a distributed manner based on the index calculated by the centralized management device. As a result, the electric power system can control the adjusted electric power to the target electric power.

In a preferred embodiment of the power system, the characteristic values are used as constraints in the optimization problem of the battery power conditioner. According to this configuration, the output power of the storage battery power conditioner can be limited by the characteristic value.

The storage battery power conditioner provided by the second aspect of the present disclosure is a storage battery power conditioner that is connected to a power line connected to a power system and controls input / output power during charging / discharging of the storage battery. The target power calculation means for calculating the individual target power which is the target value of the output power of the storage battery power conditioner, the output control means for controlling the individual output power so as to be the individual target power, and the charging / discharging of the storage battery. It is provided with a setting means for setting a characteristic value for limiting the input / output power of the above, and the setting means is currently set when the characteristic value is changed to a specified value which is a new setting value. It is characterized in that the current value is gradually changed to the specified value. According to this configuration, since the characteristic value set in the storage battery power conditioner changes stepwise, the input / output current limit at the time of charging / discharging of the storage battery changes stepwise. Since the input / output power limit during charging / discharging of the storage battery is the limit of the output power of the storage battery power conditioner, when the characteristic value is changed, depending on the difference between the current value and the specified value, the storage battery power conditioner The output power may change abruptly. However, since the output power of the storage battery power conditioner gradually changes as the characteristic value changes stepwise, it is possible to suppress a sudden change in the output power of the storage battery power conditioner. Therefore, when changing the characteristic value in the storage battery power conditioner, it is possible to suppress a sudden change in the output power of the entire power system.

In a preferred embodiment of the storage battery power conditioner, a receiving means for receiving an index for controlling input / output power at the time of charging / discharging of the storage battery, which is transmitted from a centralized management device that manages the storage battery power conditioner. Further, the target power calculation means calculates the individual target power based on the optimization problem using the index. According to this configuration, the battery power conditioner can control the individual output power based on the index.

According to the electric power system of the present disclosure, the characteristic value set in the storage battery power conditioner is gradually changed from the current set value to the new set value when the new set value is changed. As a result, it is possible to suppress a sudden change in the output power of the entire photovoltaic power generation system. Therefore, the adverse effect on the power system can be suppressed.

It is a figure which shows the whole structure of the solar power generation system which concerns on 1st Embodiment. It is a figure which shows the functional structure about the electric power control of the solar power generation system which concerns on 1st Embodiment. It is a figure which shows the relationship between the control index and individual output power in the power conditioner to which a solar cell is connected. It is a figure which shows the relationship between the control index and individual output power in the power conditioner to which a storage battery is connected. It is a figure which shows the verification result by the simulation which concerns on 1st Embodiment. It is a figure which shows the functional structure about the electric power control of the solar power generation system which concerns on 2nd Embodiment. It is a figure which shows the verification result (case 1) by the simulation which concerns on 2nd Embodiment. It is a figure which shows the verification result (case 2) by the simulation which concerns on 2nd Embodiment. It is a figure which shows the whole structure of the solar power generation system which concerns on 3rd Embodiment. It is a figure which shows the functional structure about the electric power control of the solar power generation system which concerns on 3rd Embodiment.

Hereinafter, embodiments of the power system of the present disclosure will be described by taking a grid-connected photovoltaic power generation system interconnected to the power system as an example. FIG. 1 shows the overall configuration of the photovoltaic power generation system PVS1 according to the first embodiment. As shown in FIG. 1, the photovoltaic power generation system PVS1 includes a power line 90, a power load L, a plurality of solar cells SP _i (i = 1, 2, ..., N; n is a positive integer), and a plurality of powers. It is equipped with a conditioner PCS _PVi , a plurality of storage batteries B _k (k = 1, 2, ..., M; m is a positive integer), a plurality of power conditioners PCS _Bk , and a centralized management device MC1. In the following description, when the power is output from the photovoltaic power generation system PVS1 to the power grid A, that is, when the power is reverse power flow, the interconnection point between the photovoltaic power generation system PVS1 and the power system A. The power in is assumed to be a positive value. On the other hand, when the electric power is output from the electric power system A to the photovoltaic power generation system PVS1, the electric power at the interconnection point is assumed to be a negative value.

The power line 90 is for constructing a power network in the photovoltaic power generation system PVS1. The power line 90 is connected to the power system A via an interconnection point. Further, a power load L, a plurality of power conditioners PCS _PVi , and a plurality of power conditioners PCS _Bk are connected to the power line 90.

The power load L consumes the supplied power. The power load L is supplied with power from the power system A, each power conditioner PCS _PVi , and PCS _Bk via the power line 90. An example of the power load L is a factory or a general household. The photovoltaic power generation system PVS1 does not have to have a power load L.

Each of the plurality of solar cells SP _i converts solar energy into electrical energy. Each solar cell SP _i is configured to include a plurality of solar cell panels connected in series or in parallel. The solar cell panel is, for example, a solar cell in which a plurality of solar cells made of a semiconductor such as silicon are connected and protected with a resin or tempered glass so that they can be used outdoors. Each solar cell SP _i outputs the generated power (DC power) to each power conditioner PCS _PVi . The maximum amount of power that can be generated in each solar cell SP _i is defined as the power generation amount P _i ^SP of the solar cell SP _i . The solar cell SP _i corresponds to the "power generation device" of the present invention.

Each of the plurality of power conditioners PCS _PVi converts the power generated by each solar cell SP _i (DC power) into AC power and outputs it. Each power conditioner PSC PV i performs maximum power point tracking control ( _MPPT control) so that the electric power generated by each solar cell SP _i can be output to the maximum. In the present embodiment, the power conditioner PCS _PVi operates with a responsiveness such that the output changes in a cycle of 1 sec, for example, in MPPT control. Note that this cycle is not limited to 1 sec. Each power conditioner PCS _PVi includes an inverter circuit, a transformer, a control circuit, and the like. In each power conditioner PCS _PVi , the inverter circuit converts the DC power input from the solar cell SP _i into AC power synchronized with the power system A. The transformer boosts (or steps down) the AC voltage output from the inverter circuit. The control circuit controls an inverter circuit or the like. The power conditioner PCS _PVi is not limited to the one configured as described above. The power conditioner PCS _PVi corresponds to the "power control device" of the present invention.

Each of the plurality of storage batteries B _k is a battery that can be repeatedly charged and discharged. The storage battery B _k is a secondary battery such as a lithium ion battery, a nickel hydrogen battery, a nickel cadmium battery, or a lead storage battery. Further, a capacitor such as an electric double layer capacitor may be used. The storage battery B _k discharges the stored electric power and supplies DC power to the power conditioner _PCS B k.

Each of the plurality of power conditioners PCS _Bk converts the DC power input from the storage battery B _k into AC power and outputs it. Further, each power conditioner PCS _Bk converts the AC power input from the power system A and each power conditioner PCS _PVi into DC power via the power line 90 and supplies the AC power to the storage battery B _k . Charge _k . Each power conditioner _PCS B k controls charging and discharging of each storage battery B _k . Therefore, each power conditioner PCS _Bk functions as a charging circuit for charging the storage battery B _k and a discharging circuit for discharging the storage battery B _k . In the present embodiment, the C rate is set in each power conditioner PCS _Bk as a characteristic value for limiting the input / output power at the time of charging / discharging of the storage battery B _k . The C rate in the present embodiment includes a C rate on the charging side and a C rate on the discharging side. The C rate on the charging side is a C rate with respect to the current when charging each storage battery B _k , and is referred to as a "charging rate" in the following description. The C rate on the discharge side is a C rate with respect to the current when each storage battery B _k is discharged, and is referred to as a "discharge rate" in the following description. That is, a discharge rate and a charge rate are set for each power conditioner PCS _Bk . The power conditioner PCS _Bk corresponds to the "storage battery power conditioner" of the present invention.

Assuming that the active power output from each power conditioner PCS _PVi is P _PVi ^out and the reactive power is Q _PVi ^out , the complex power of P _PVi ^out + j · Q _PVi ^out is output from each power conditioner PCS _PVi . If the active power output from each power conditioner PCS _Bk is P _Bk ^out and the reactive power is Q _Bk ^out , the complex power of P _Bk ^out + j · Q _Bk ^out is output from each power conditioner PCS _Bk . There is. Therefore, the complex power of the total (Σ _i P _PVi ^out + Σ _k P _Bk ^out ) + j (Σ _i Q _PVi ^out + Σ _k Q _Bk ^out ) is output from the plurality of power conditioners PCS _PVi and PCS _Bk . In this embodiment, the output control of the reactive powers Q _PVi ^out and Q _Bk ^out , which are mainly used for suppressing voltage fluctuations at the interconnection point, is not particularly considered. That is, the individual output powers controlled by the power conditioners PCS _PVi and PCS _Bk are the active powers P _PVi ^out and P _Bk ^out , respectively. Therefore, assuming that the individual output power of each power conditioner PCS _PVi is P _PVi ^out , the individual output power of each power conditioner PCS _Bk is P _Bk ^out , and the power consumption of the power load _L is PL, the power at the interconnection point is used. P (t) (hereinafter referred to as "interconnection point power") is the sum of the individual output powers P _PVi ^out and P _Bk ^out of each power conditioner PCS _PVi and PCS _Bk and the power consumption P _L of the power load L. Σ _i P _PVi ^out + Σ _k P _Bk ^out - _PL ).

The centralized management device MC1 centrally manages a plurality of power conditioners PCS _PVi and PCS _Bk . The centralized management device MC1 transmits and receives various information to and from each power conditioner PCS _PVi and PCS _Bk by, for example, wireless communication. Note that wired communication may be used instead of wireless communication.

In the photovoltaic power generation system PVS1 configured in this way, the centralized management device MC1 monitors a predetermined adjusted target power, and is adjusted based on the adjusted target power and the target power which is the target value of the adjusted target power. Calculate the index to make the power the target power. Then, each power conditioner PCS _PVi and PCS _Bk are controlled in a distributed manner using the index, and the adjusted power is set as the target power. The power to be adjusted is the output power of the entire photovoltaic power generation system PVS1. In the present embodiment, the output power of the entire photovoltaic power generation system PVS1 is the consumption of the individual output power P _PVi ^out of each power conditioner PCS _PVi , the individual output power P _Bk ^out of each power conditioner PCS _Bk , and the power load L. It is the sum of the electric power _PL . Further, as described above, the interconnection point power P (t) is the consumption of the individual output power P _PVi ^out of each power conditioner PCS _PVi , the individual output power P _Bk ^out of each power conditioner PCS _Bk , and the power load L. It is the sum of the electric power _PL . Therefore, in the present embodiment, the case where the interconnection point power P (t) is used as the power to be adjusted will be described. That is, the photovoltaic power generation system PVS1 controls the interconnection point power ^P (t) to be the target power PC.

Specifically, in the photovoltaic power generation system PVS1, the centralized management device MC1 monitors the interconnection point power P (t) and is an index for matching the interconnection point power ^P (t) with the target power PC. Is calculated. In the present embodiment, the control index pr _PV and the control index pr _B are calculated as indexes. The control index pr _PV is information for setting the interconnection point power P ( ^t ) to the target power PC, and is information for causing each power conditioner PCS _PVi to calculate the individual target power P _PVi ^ref . The individual target power P _PVi ^ref is the target value of the individual output power P _PVi ^out of the power conditioner PCS _PVi . The control index pr _B is information for setting the interconnection point power P (t) to the target power P ^C , and is information for causing each power conditioner PCS _Bk to calculate the individual target power P _Bk ^ref . The control index pr _B is also information for determining how much the storage battery B _k should be charged or discharged. The individual target power P _Bk ^ref is the target value of the individual output power P _Bk ^out of the power conditioner PCS _Bk . Then, the centralized management device MC1 transmits the control index pr _PV to each power conditioner PCS _PVi , and transmits the control index pr _B to each power conditioner PCS _Bk . Each power conditioner PCS _PVi calculates the individual target power P _PVi ^ref based on the control index pr _PV received from the centralized management device MC1, and the individual output power P _PVi ^out based on the calculated individual target power P _PVi ^ref . To control. Further, each power conditioner PCS _Bk calculates an individual target power P _Bk ^ref based on the control index pr _B received from the centralized management device MC1, and an individual output power P based on the calculated individual target power P _Bk ^ref . Control _Bk ^out . As a result, the interconnection point power P ( ^t ) is made to match the target power PC.

In the present embodiment, the suppression target value, the peak cut target value, the reverse power flow ^avoidance target value, the schedule target value, and the like are set as the target power PC. These are appropriately set according to various power controls performed by the photovoltaic power generation system PVS1.

The suppression target value is a target value for performing output suppression control for suppressing output power in accordance with an output suppression command instructed by an electric power company. When the photovoltaic power generation system ^PVS1 performs output suppression control, a suppression target value is set as the target power PC. In recent years, the number of photovoltaic power generation systems connected to the power system A has increased, and there is a possibility that the supply of power to the power system A will be excessive compared to the demand. In order to eliminate this oversupply condition, electric power companies and the like instruct each photovoltaic power generation system to suppress individual output power. Therefore, in order to suppress the power supplied to the power system ^A in accordance with the output suppression command from the electric power company or the like, a suppression target value is set as the target power PC. As a result, the interconnection point power P (t) is controlled to reach the suppression target value. That is, since the interconnection point power P (t) does not exceed the suppression target value, the power supplied to the power system A can be suppressed in accordance with the output suppression command.

The peak cut target value is a target value for performing peak cut control for suppressing the peak value of the electric power (power purchased) supplied from the electric power system A. When the photovoltaic power generation system ^PVS1 performs peak cut control, a peak cut target value is set as the target power PC. For example, when the photovoltaic power generation system PVS1 includes a power load L, power may be supplied from the power system A to the photovoltaic power generation system PVS1. At this time, the electric power is bought from the electric power company, and it is necessary to pay the electricity charge by this electric purchase. The higher the peak value of the purchased power, the higher the electricity price. Therefore, in order to suppress the peak value of the purchased power, a peak cut target value is set as the target power ^PC . As a result, the interconnection point power P (t) is controlled to reach the peak cut target value. That is, since the interconnection point power P (t) does not exceed the peak cut target value, the peak value of the power purchase power can be suppressed.

The reverse power flow avoidance target value is a target value for performing reverse power flow avoidance control for suppressing the occurrence of reverse power flow. When the photovoltaic power generation system ^PVS1 performs reverse power flow avoidance control, a reverse power flow avoidance target value is set as the target power PC. For example, when the photovoltaic power generation system PVS1 is a self-consumption type system, reverse power flow is prohibited. Therefore, in order to suppress the occurrence of reverse power flow, a reverse power flow ^avoidance target value is set as the target power PC. As a result, the interconnection point power P (t) is controlled to be the reverse power flow avoidance target value. That is, since the interconnection point power P (t) does not exceed the reverse power flow avoidance target value, reverse power flow can be avoided. Further, in the photovoltaic power generation system PVS1 in which reverse power flow is prohibited, it is necessary to install a reverse power relay at the interconnection point with the power system A. The reverse power relay is a kind of relay, and when it detects the occurrence of reverse power flow, it disconnects the photovoltaic power generation system PVS1 from the power system A. Therefore, reverse power flow avoidance control can prevent the reverse power relay from operating.

The schedule target value is a target value for performing schedule control for controlling the interconnection point power P (t) to a value freely set for each predetermined time zone. The predetermined time zone is a predetermined period in which one day is divided into a plurality of times, and can be set for each of 48 time zones when divided into, for example, every 30 minutes. The predetermined time zone is not limited to the above example, and may be divided into time zones such as morning, noon, evening, evening, and midnight, and the predetermined time zone may be divided into weekly units instead of daily units. You may divide it. When the photovoltaic power generation system ^PVS1 performs schedule control, a schedule target value is set as the target power PC. By setting the schedule target value as the target power P ^C , the interconnection point power P (t) is controlled to be the schedule target value set for each predetermined time zone. That is, the interconnection point power P (t) can be controlled to a free value for each predetermined time zone.

FIG. 2 shows the functional configuration of the control system related to the power control of the photovoltaic power generation system PVS1 shown in FIG. In FIG. 2, the solar cell SP _i and the storage battery B _k are not shown. Further, for a plurality of power conditioners PCS _PVi and PCS _Bk , only the first one (power conditioner PCS _PV1 and PCS _B1 ) is described.

As shown in FIG. 2, the centralized management device MC1 has a target power setting unit 11, an interconnection point power detection unit 12, an index calculation unit 13, a transmission unit 14, and a C rate designation unit 15 as control systems in power control. Includes.

The target power setting unit 11 sets a target value of the interconnection point power P (t). That is, the target power ^PC is set. As described above, the target power P ^C includes a suppression target value, a peak cut target value, a reverse power flow avoidance target value, a schedule target value, and the like, and one of these is set as the target power P ^C. To.

When the photovoltaic power generation system PVS1 performs output suppression control as power control, the target power setting unit 11 acquires an output command value commanded by the electric power company, and sets a suppression target value based on the acquired output command value as the target power P. Set as ^C. For example, when the output command value to be acquired is a value that specifies the upper limit value of the output power, the output command value is set as the suppression target value. Alternatively, when the output command value to be acquired is the output suppression rate [%], the output suppression rate [%] and the rated output of the entire solar power generation system PVS1 (that is, the total rated output of each power conditioner PCS _PVi ). Based on Σ _i P _PVi ^lmt , the upper limit of the output power is calculated, and this is set as the suppression target value. For example, when the target power setting unit 11 obtains a command that the output suppression rate is 20%, the upper limit of the output power is 80% (= 100-20) of the rated output Σ _i P _PVi ^lmt of the photovoltaic power generation system PVS1. Calculate as a value and set this as the suppression target value. It is not limited to those that directly acquire the output command value from the electric power company. For example, the user may manually input the output command value commanded by the electric power company to a predetermined computer, and the target power setting unit 11 may acquire the output command value from the computer. Alternatively, the configuration may be such that the output command value commanded by the electric power company is acquired by relaying another communication device.

When the photovoltaic power generation system ^PVS1 performs peak cut control as power control, the target power setting unit 11 sets the peak cut target value specified by the user as the target power PC. As the interconnection point power P (t) has a negative value and is smaller, the power supplied from the power system A becomes larger, so that the power purchased becomes larger. In the peak cut control, since the peak cut is a control for suppressing the peak value of the power purchased, the power purchased is controlled so as not to exceed the upper limit value specified by the user. Therefore, during peak cut control, the interconnection point power P (t) matches the peak cut target value so that the interconnection point power P (t) does not fall below the peak cut target value with the above upper limit value as a negative value. I'm letting you. Therefore, the peak cut target value is a negative value.

When the photovoltaic power generation system ^PVS1 performs reverse power flow avoidance control as power control, the target power setting unit 11 sets the reverse power flow avoidance target value specified by the user as the target power PC. Since reverse power flow is generated when the interconnection point power P (t) is a positive value, the interconnection point power P (t) does not become a positive value in order to suppress the generation of reverse power flow. As such, the negative value should be maintained. Therefore, at the time of reverse power flow avoidance control, the interconnection point power P (t) is matched with the reverse power flow avoidance target value so that the interconnection point power P (t) becomes a negative value. Therefore, the reverse power flow avoidance target value is a negative value.

When the photovoltaic power generation system ^PVS1 performs schedule control as power control, the target power setting unit 11 sets the schedule target value specified by the user as the target power PC. In the schedule control, since the interconnection point power P (t) is controlled to a value preferred by the user, the schedule target value can be freely set.

The target power setting unit 11 outputs the set target power ^PC to the index calculation unit 13. When the target power setting unit 11 does not set the target power PC, the target power setting unit 11 ^notifies the index calculation unit 13 to that effect. For example, when there is no command to suppress the output of the electric power company or when the power generated by the solar cell SP _i is output to the maximum, the target power ^PC is not set. In the present embodiment, when the target power PC is not set, the target power setting unit 11 ^outputs a numerical value ^-1 as the target power PC to the index calculation unit 13. The method is not limited as long as it can be transmitted to the index calculation unit 13 that the target power ^PC is not set. For example, the target power ^setting unit 11 may be configured to transmit flag information indicating whether or not the target power PC is set to the index calculation unit 13. The flag information is, for example, "0" when the target power P ^C is not set, and "1" when the target power P ^C is set. If the target power P ^C is set (when the flag information is “1”), the setting of the target power P ^C may be transmitted to the index calculation unit 13 together with the flag information.

The interconnection point power detection unit 12 detects the interconnection point power P (t). Then, the detected interconnection point power P (t) is output to the index calculation unit 13. The interconnection point power detection unit 12 may be configured as a detection device different from the centralized management device MC1. In this case, the detection device (interconnection point power detection unit 12) transmits the detection value of the interconnection point power P (t) to the centralized management device MC1 by wireless communication or wire communication.

The index calculation unit 13 calculates an index for setting the interconnection point power ^P (t) to the target power PC. In the present embodiment, in the index calculation unit 13, the target power P ^C is input from the target power setting unit 11, and the control indexes pr _PV , pr _B for setting the interconnection point power P (t) to the target power P ^C. Is calculated. The index calculation unit 13 calculates the control indexes pr _PV and pr _B based on the following equations (1) and (2), where the Lagrange multiplier is λ, the gradient coefficient is ε (> 0), and the time is t. However, when the index calculation unit 13 inputs a numerical value -1 indicating that the target power ^PC is not set as the target power PC from the target power setting unit 11, the Lagrange multiplier λ is set to “ ⁰ ”. .. That is, both the control indexes pr _PV and pr _B are calculated as “0”. In the following equation (1), the target power is described as ^PC ( ^t ), assuming that the target power PC is a value that changes with respect to time t. The index calculation unit 13 calculates the control indexes pr _PV and pr _B at predetermined time intervals. In the present embodiment, the predetermined time is 1 [sec], but the predetermined time is not limited to this. The arithmetic expressions for calculating the control indexes pr _PV and pr _B are not limited to the following equations (1) and (2), and may be different arithmetic expressions.

The transmission unit 14 transmits the control indexes pr _PV and pr _B calculated by the index calculation unit 13 to the respective power conditioners PCS _PVi and PCS _Bk , respectively. The transmission unit 14 transmits the calculated control indexes pr _PV and pr _B each time the control indexes pr _PV and pr _B are calculated by the index calculation unit 13. Therefore, in the present embodiment, the control indexes pr _PV and pr _B are transmitted to the power conditioners PCS _PVi and PCS _Bk every 1 [sec].

The C rate designation unit 15 transmits the C rate value (hereinafter referred to as “C rate designated value”) set in the plurality of power conditioner PCS _Bk to each power conditioner PCS _Bk . For example, when a user performs an operation of specifying a C rate value (hereinafter referred to as "request value") to be set in a plurality of power conditioners PCS _Bk by using an operation device (not shown) provided in the centralized management device MC1. , The C rate designation unit 15 creates a C rate designation value based on the request value designated by this operation, and transmits it to each power conditioner PCS _Bk . In the present embodiment, the C rate specified value created is the same as the value (request value) specified by the user. The user instructs the photovoltaic power generation system PVS1 to change the set value of the C rate by designating a new value as the request value. The request value may be configured so that different values are specified for the charge rate and the discharge rate, or the same value may be specified. In the present embodiment, the C rate designation unit 15 shows a case where the C rate designation value is periodically transmitted at a predetermined cycle. It should be noted that the present invention is not limited to this, and may be transmitted only when, for example, the C rate specified value is changed. Further, the predetermined cycle is, for example, the same as, but not limited to, the calculation interval of the control indexes pr _PV and pr _B. In the present embodiment, the case where the C rate designation unit 15 directly transmits the C rate designation value to each power conditioner PCS _Bk is shown, but the present invention is not limited to this, and for example, transmission is performed via the transmission unit 14. Alternatively, the transmission may be performed via a transmission unit provided in the centralized management device MC1 separately from the transmission unit 14.

As shown in FIG. 2, each power conditioner PCS _PVi includes a receiving unit 21, a target power calculation unit 22, and an output control unit 23 as a control system related to power control.

The receiving unit 21 receives the control index pr _PV transmitted from the centralized management device MC1. The receiving unit 21 receives the control index pr _PV from the centralized management device MC1 by, for example, wireless communication. Note that wired communication may be used instead of wireless communication.

The target power calculation unit 22 calculates the individual target power P _PVi ^ref of the own device (power conditioner PCS _PVi ) based on the control index pr _PV received by the reception unit 21. Specifically, the target power calculation unit 22 calculates the individual target power P _PVi ^ref by solving the constrained optimization problem shown in the following equation (3). The following equation (3a) in the following equation (3) shows the evaluation function in the optimization problem. Further, the following equation (3b) and the following equation (3c) in the following equation (3) each indicate the constraint conditions in the optimization problem. Under the constraint conditions, the following equation (3b) is a constraint due to the rated output of each power conditioner PCS _PVi , and the following equation (3c) is an output current constraint of each power conditioner PCS _PVi . Instead of the output current constraint of each power conditioner PCS _PVi shown in the following equation (3c), the rated capacity constraint of the power conditioner PCS _PVi shown in the following equation (3d) may be used. Further, when the index calculation unit 13 calculates the control indexes pr _PV and pr _B by a calculation formula different from the above equation (1) and the above equation (2), the constraint set in the target power calculation unit 22. The attached optimization problem may be changed based on the different arithmetic expression.

In the above equation (3a), w _PVi represents the weight related to the active power suppression of the power conditioner PCS _PVi , and is a design value. Further, Pφ _i indicates a design parameter (hereinafter referred to as “priority parameter”) indicating whether or not to give priority to suppressing the individual output power P _PVi ^out of the power conditioner PCS _PVi , and is a design value. When the priority parameter Pφ _i is reduced, the charge amount of the storage battery B _k is reduced, and the individual output power P _PV i ^out is easily suppressed. On the other hand, when the priority parameter Pφ _i is increased, the charge amount of the storage battery B _k is increased, and it becomes difficult to suppress the individual output power P _PV i ^out . Therefore, it can be said that the priority parameter Pφ _i is a design parameter indicating whether or not to prioritize the charging of the storage battery B _k . Furthermore, it is considered that this priority parameter Pφ _i sets a pseudo output limit for the individual output power P _PVi ^out of the power conditioner PCS _PVi , in addition to the output limit due to the rated output of the power conditioner PCS _PVi . Will be. Therefore, the priority parameter Pφ _i can be said to be a pseudo effective output limit. The weight w _PVi and the priority parameter Pφ _i can be set and changed by the user.

In the above equation (3b), P _PVi ^lmt represents the rated output (output limit) of each power conditioner PCS _PVi . Therefore, the above equation (3b) limits the calculated individual target power P _PVi ^ref so as not to exceed the rated output P _PVi ^lmt .

In the above equation (3c), Q _PVi is the ineffective power of each power conditioner PCS _PVi , S _PVi ^d is the maximum apparent power that can be output by each power conditioner PCS _PVi , and V ₀ is the reference of the interconnection point at the time of design. The voltage and V _PVi represent the voltage at the interconnection point in each power conditioner PCS _PVi .

In the present embodiment, the weight w _PVi (see the above equation (3a)) relating to the active power suppression of each power conditioner PCS _PVi uses the value calculated by the following equation (4). In the following equation (4), pr _PV ^lmt indicates the control index limit. The control index limit pr _PV ^lmt is a control index when the individual output power P _PVi ^out is set to 0, that is, a control index when the individual output power P _PVi ^out is suppressed by 100%. Further, P _PVi ^lmt is the rated output of each of the above power conditioners PCS _PVi . Instead of the rated output P _PVi ^lmt of each power conditioner PCS _PVi , a pseudo effective output limit Pφ _i may be used. That is, the value calculated by the following equation (4') may be used. Alternatively, the same weight w _PVi for active power suppression may be used in a plurality of power conditioners PCS _PVi .
w _PVi = pr _PV ^lmt / (2 × P _PVi ^lmt ) ・ ・ ・ (4)
w _PVi = pr _PV ^lmt / (2 × Pφ _i ) ・ ・ ・ (4')

FIG. 3 shows the relationship between the control index pr _PV and the individual output power P _PVi ^out when the weight w _PVi relating to the active power suppression of each power conditioner PCS _PVi is used as described above. Note that FIG. 3 shows each of the three power conditioners PCS _PVi having different rated outputs P _PVi ^lmt . In the present embodiment, the individual output power P _PVi ^out is controlled to be the individual target power P _PVi ^ref calculated by the target power calculation unit 22, so that the figure shows the control index pr _PV and the individual target power. It can be said that it shows the relationship with P _PVi ^ref . In FIG. 3, the control index limit pr _PV ^lmt is set to 100. Further, in FIG. 3, the one with the rated output P _PVi ^lmt of 500 kW is shown by the solid line, the one with the rated output P _PVi ^lmt of 250 kW is shown by the broken line, and the one with the rated output P _PVi ^lmt of 100 kW is shown by the alternate long and short dash line.

As shown in FIG. 3, every time the control index pr _PV increases by 20 between 0 and 100 (control index limit pr _PV ^lmt ), the rated output P _PVi ^lmt is 100 kW when the rated output P PVi lmt is 500 kW, and the rated output P _PVi ^lmt is 250 kW. In the case of 50 kW, when the rated output P _PVi ^lmt is 100 kW, it decreases by 20 kW. This means that the rated output P _PVi ^lmt of each power conditioner PCS _PVi is reduced by 20%. That is, the individual output power P _PVi ^out is suppressed by the ratio of each power conditioner PCS _PVi to the rated output P _PVi ^lmt . Further, in each power conditioner PCS _PVi , the individual output power P _PVi ^out is 0 when the control index pr _PV is the control index limit pr _PV ^lmt . That is, it is suppressed 100%. Further, when the control index pr _PV is 0, the individual output power P _PVi ^out is the rated output P _PVi ^lmt . That is, the power that can be output to the maximum is output. Then, as shown in FIG. 3, the individual output power P _PVi ^out of each power conditioner PCS _PVi changes linearly between the control index pr _PV of 0 and the control index limit pr _PV ^lmt (100). .. Since each power conditioner PCS _PVi cannot output power equal to or higher than its rated output P _PVi ^lmt , when the control index pr _PV is a negative value, it is a constant value (rated output P) as shown in FIG. _PVi ^lmt ). From the above, by using the above equation (4) in setting the weight w _PVi related to active power suppression, the ratio of each power conditioner PCS _PVi to the rated output P _PVi ^lmt as the control index pr _PV changes. , Individual output power P _PVi ^out can be suppressed. Therefore, even if the rated output P _PVi ^lmt of multiple power conditioners PCS _PVi is different, the output of the individual output power P _PVi ^out is 100% when the control index pr _PV is the control index limit pr _PV ^lmt . It can be suppressed. When the same value is used as the weight w _PVi related to the active power suppression, the individual output power P _PVi ^out decreases uniformly by the same amount even if the rated output P _PVi ^lmt of each power conditioner PCS _PVi is different. Can be configured as follows.

The output control unit 23 controls the inverter circuit to control the individual output power P _PVi ^out . The output control unit 23 sets the individual output power P _PVi ^out to the individual target power P _PVi ^ref calculated by the target power calculation unit 22.

As shown in FIG. 2, each power conditioner PCS _Bk includes a receiving unit 31, a C rate setting unit 32, a target power calculation unit 33, and an output control unit 34 as control systems related to power control.

The receiving unit 31 is configured in the same manner as the receiving unit 21, and receives the control index pr _B transmitted from the centralized management device MC1.

The C rate setting unit 32 receives the C rate specified value transmitted from the centralized management device MC1 and sets the C rate based on the received C rate specified value. Specifically, the C rate setting unit 32 sets the C rate by setting the C rate setting value of the own device (power conditioner PCS _Bk ) to the C rate specified value. In the present embodiment, the case where the C rate setting unit 32 receives the C rate specified value directly from the centralized management device MC1 is shown, but the present invention is not limited to this, and even if the C rate setting unit 32 receives the value via the receiving unit 31, for example. Alternatively, it may be received via a receiving unit provided in each power conditioner PCS _Bk separately from the receiving unit 31.

In the present embodiment, in each power conditioner PCS _Bk , the C rate specified value received from the centralized management device MC1 and the C rate set value at the time when the C rate specified value is received (hereinafter, “received set value””. If the above is different, the C rate setting value is changed by the C rate setting unit 32 (Note that if the reception setting value and the C rate specified value are the same, the C rate setting value is not changed). At this time, the C rate setting value is not changed from the reception setting value to the C rate specified value at once by the C rate setting unit 32, but is changed step by step. Specifically, when the reception setting value and the C rate specified value are different, the C rate setting unit 32 sets the C rate setting value in advance from the reception setting value to the C rate specified value in a predetermined update cycle. Change by the set unit update amount. The update cycle is a cycle for changing the set value of the C rate, and the update cycle in the present embodiment is the same as the calculation cycle (1 sec) of the control indexes pr _PV and pr _B by the centralized management device MC1. It may be different. The unit update amount is an amount to be changed for each update cycle, and is an amount to be changed at one time. In this embodiment, the unit renewal amount is 0.05C. Therefore, in the present embodiment, for example, when the reception setting value is 0C and the C rate designation value is 1C, the C rate setting unit 32 changes from the reception setting value to the C rate designation value over 20 seconds. .. The update cycle and unit update amount are not limited to the above values, and the time required to change the C rate setting value from 0C to the maximum value is within the range of 2 sec to 30 min (preferably 10 sec to 60 sec). It may be set appropriately so as to be. However, it is desirable that the update cycle is within the range of 1 sec to 10 sec and the unit update amount is within the range of 0.01 C to 0.1 C.

The target power calculation unit 33 calculates the individual target power P _Bk ^ref of the own device (power conditioner PCS _Bk ) based on the control index pr _B received by the reception unit 31. Specifically, the target power calculation unit 33 calculates the individual target power P _Bk ^ref by solving the optimization problem shown in the following equation (5). The following equation (5a) in the following equation (5) shows the evaluation function in the optimization problem. Further, the following equations (5b) to (5e) in the following equation (5) each indicate the constraint conditions in the optimization problem. Under the constraint conditions, the following equation (5b) is a constraint due to the rated output of each power conditioner PCS _Bk , the following equation (5c) is a C rate constraint of the storage battery B _k , and the following equation (5d) is a constraint of each storage battery B. The remaining amount constraint of _k , and the following equation (5e) is the output current constraint of each power conditioner PCS _Bk . Instead of the output current constraint of each power conditioner PCS _Bk shown in the following equation (5e), the rated capacity constraint of the power conditioner PCS _Bk shown in the following equation (5f) may be used. Further, when the index calculation unit 13 calculates the control indexes pr _PV and pr _B by a calculation formula different from the above equation (1) and the above equation (2), the constraint set in the target power calculation unit 33. The attached optimization problem may be changed based on the different arithmetic expression.

In the above equation (5a), w _Bk represents the weight of the power conditioner PCS _Bk with respect to the active power. The weight w _Bk can be set by the user. w _SOCk represents the weight of the storage battery B _k according to the SOC (States Of Charge). This weight w _SOCk is calculated by the following equation (6). In the following equation (6), A _SOC is the offset of the weight w _SOCk , K _SOC is the gain of the weight w _SOCk , s is the on / off switch of the weight w _SOCk (for example, 1 when on, 0 when off), SOC. _k indicates the SOC of the current storage battery B _k , and SOC _d indicates the reference SOC.

In the above equation (5b), P _Bk ^lmt represents the rated output (output limit) of each power conditioner PCS _Bk . Therefore, the above equation (5b) limits the calculated individual target power P _Bk ^ref so as not to exceed the rated output P _Bk ^lmt .

In the above equation (5c), P _SMk ^lmt represents the charge rated output of the storage battery B _k , and when the charge rate is C _rate ^M and the rated capacity of the storage battery B _k is WH _S ^lmt , -C _rate . It is calculated by ^M × WH _S ^lmt . In the charge rated output P _SMk ^lmt of the storage battery B _k , the correction start SOC is set to SOC _C , the charge limit threshold of SOC is set to cMAX, and the storage battery charge amount correction according to the SOC shown in the following equation (7) is taken into consideration. .. The storage battery charge amount correction is configured to operate normally until the correction start SOC, and to linearly correct the output so that the output becomes 0 at the SOC upper limit from the correction start SOC to the SOC upper limit. is doing. P _SPk ^lmt represents the discharge rated output of the storage battery B _k , and is obtained by C _rate ^P × WH _S ^lmt when the discharge rate is C _rate ^P and the rated capacity of the storage battery B _k is WH _S ^lmt . .. Therefore, in the above equation (5c), the calculated individual target power P _Bk ^ref is within the range of the charge rated output and the discharge rated output specified based on the set C rate (charge rate and discharge rate). It is restricted to fit in. That is, due to the restriction by the above equation (5c), the value obtained by dividing the output current (individual output power P _Bk ^out ) of each power conditioner PCS B k by the rated capacity of the storage battery B _{k should} not exceed the set C rate. Is controlled by. Therefore, the C rate can be said to be a characteristic value for limiting the output current (individual output power P _Bk ^out ) in each power conditioner PCS _Bk .

In the above equation (5d), α _k and β _k represent adjustment parameters that can be adjusted by the remaining amount of the storage battery B _k . For example, when the charge rate SOC _k of the storage battery B _k is 90% or more, by setting α _k to 0 and β _k to P _Bk ^lmt , it is possible to limit the discharge to only by the above equation (5d). Further, when the charge rate SOC _k of the storage battery B _k is 10% or less, by setting α _k to −P _Bk ^lmt and β _k to 0, it is possible to limit charging only by the above equation (5d). Furthermore, when the charge rate SOC _k of the storage battery B _k is between these (greater than 10% and less than 90%), by setting α _k as −P _Bk ^lmt and β _k as P _Bk ^lmt , the charge is also discharged. Can also be restricted to do.

In the above equation (5e), Q _Bk is the invalid power of each power conditioner PCS _Bk , S _Bk ^d is the maximum apparent power that can be output by each power conditioner PCS _Bk , and V ₀ is the reference of the interconnection point at the time of design. The voltage and V _Bk represent the voltage at the interconnection point in each power conditioner PCS _Bk .

In the present embodiment, the weight w _Bk (see the above equation (5a)) regarding the active power of each power conditioner PCS _Bk uses the value calculated by the following equation (8). In the following equation (8), pr _B ^lmt indicates the control index limit of the control index pr _B. The control index limit pr _B ^lmt is a control index when charging / discharging the storage battery B _k with the maximum output power, that is, when the individual output power P _Bk ^out is charged / discharged at 100% of the rated output P _Bk ^lmt . It is a control index of. Further, w _SOCk indicates the weight of the storage battery B _k according to the SOC, and P _Bk ^max is the power that can be output to the maximum when various restrictions in the storage battery B _k are taken into consideration (hereinafter, “restricted maximum output”). ".) Is shown. The constraint maximum output P _Bk ^max is set based on the charge rated output P _SMk ^lmt of the storage battery B _k , the discharge rated output P _SPk ^lmt of the storage battery B _k , and the rated output P _{Bk lmt} of the power conditioner PCS B k ^. .. Specifically, the value obtained by inverting the positive and negative signs of the charge rated output P _SMk ^lmt and the value of the discharge rated output P _SPk ^lmt are compared, and the larger value is obtained. Then, the larger value is compared with the value of the rated output P _Bk ^lmt , and the smaller value is set as the constraint maximum output P _Bk ^max . In addition, in a plurality of power conditioners PCS _Bk , the weight w _Bk relating to the same active power may be used.
w _Bk = pr _B ^lmt / (2 x w _SOCk x P _Bk ^max ) ... (8)

FIG. 4 shows the relationship between the control index pr _B and the individual output power P _Bk ^out when the weight w _Bk relating to the active power of each power conditioner PCS _Bk is used as described above. Note that FIG. 4 shows each of the three power conditioners PCS _Bk having different rated outputs P _Bk ^lmt . In the present embodiment, each power conditioner PCS _Bk charges the storage battery B _k when the individual output power P _Bk ^out is a negative value, and discharges the storage battery B _k when the individual output power P _Bk ^out is a positive value. do. Further, since the individual output power P _Bk ^out is controlled to be the individual target power P _Bk ^ref calculated by the target power calculation unit 33, the figure shows the control index pr _B and the individual target power P _Bk ^ref . It can be said that it shows the relationship between. In FIG. 4, the control index limit pr _B ^lmt is set to 100. Further, in FIG. 4, the one with the rated output P _Bk ^lmt of 500 kW is shown by the solid line, the one with the rated output P _Bk ^lmt of 250 kW is shown by the broken line, and the one with the rated output P _Bk ^lmt of 100 kW is shown by the alternate long and short dash line.

As shown in FIG. 4, the rated output is every time the control index pr _B increases by 20 between -100 (control index limit pr _B ^lmt is a negative value) and 100 (control index limit pr _B ^lmt ). When P _Bk ^lmt is 500 kW, it decreases by 100 kW, when the rated output P _Bk ^lmt is 250 kW, it decreases by 50 kW, and when the rated output P _Bk ^lmt is 100 kW, it decreases by 20 kW. This means that the rated output P _Bk ^lmt of each power conditioner PCS _Bk is reduced by 20%. That is, the individual output power P _Bk ^out is controlled by the ratio of each power conditioner PCS _Bk to the rated output P _Bk ^lmt . Therefore, even if the change amount of the same control index pr _B , the charge / discharge amount of the storage battery B _k ^{changes according to the rated output P Bk lmt} _{of the} power conditioner PCS B k. In addition, each power conditioner PCS _Bk has the same value as the rated output P _Bk ^lmt when the control index pr _B has the control index limit pr _B ^{lmt set} to a negative value (-pr _B ^lmt ). The storage battery B _k is discharged by the output power P B _k ^out . On the other hand, when the control index pr _B is the control index limit pr _B ^lmt , the storage battery B _k is charged with the individual output power P _Bk ^out having the same value as the rated output P _Bk ^lmt . That is, the storage battery B _k is charged and discharged with the electric power that can be output to the maximum. Further, when the control index pr _B is 0, the individual output power P _Bk ^out is 0. Then, as shown in FIG. 4, the individual output power P _Bk ^out changes linearly. From the above, by using the above equation (8) in the setting of the weight w _Bk regarding the active power, the ratio of each power conditioner PCS _Bk to the rated output P _Bk ^lmt as the control index pr _B changes. The storage battery B _k can be charged and discharged. Therefore, in a plurality of power conditioners PCS _Bk , even if their rated outputs P _Bk ^lmt are different, 100% of the rated outputs P _Bk ^lmt when the absolute value of the control index pr _B is the control index limit pr _B ^lmt . The storage battery B _k can be charged and discharged. Specifically, when the control index pr _B is a negative value of the control index limit pr _B ^lmt , the storage battery B _k is discharged at 100% of the rated output P _Bk ^lmt , and the control index pr _B is the control index limit pr. When the value is _B ^lmt , the storage battery B _k can be charged at 100% of the rated output P _Bk ^lmt . When the same value is used as the weight w _Bk for the active power, even if the rated output P _Bk ^lmt of each power conditioner PCS _Bk is different, the individual output power P _Bk ^out is uniformly reduced by the same amount. Can be configured.

The output control unit 34 is configured in the same manner as the output control unit 23. The output control unit 34 controls the discharge and charge of the storage battery B _k to set the individual output power P _Bk ^out to the individual target power P _Bk ^ref calculated by the target power calculation unit 33. Specifically, when the individual target power P _Bk ^ref calculated by the target power calculation unit 33 is a positive value, the power (DC power) stored in the storage battery B _k is converted into AC power and passed through the power line 90. And output. That is, the power conditioner PCS _Bk is made to function as a discharge circuit. On the other hand, when the individual target power P _Bk ^ref is a negative value, the AC power input via the power line 90 is converted into DC power and supplied to the storage battery B _k . That is, the power conditioner PCS _Bk is made to function as a charging circuit.

Next, in the solar power generation system PVS1 according to the first embodiment, the operation when changing the set value of the C rate of each power conditioner PCS _Bk will be described.

For example, in order to change the C rate setting value of each power conditioner PCS _Bk , the user specifies a new setting value (request value) different from the current setting value, which is an operation device of the centralized management device MC1. By using (not shown), the C rate designation unit 15 creates a C rate designation value based on the request value designated by this operation, and transmits this to each power conditioner PCS _Bk . For example, it is assumed that the current C rate setting value in each power conditioner PCS _Bk is 0C, and 1C is specified as a new setting value (request value). At this time, the C rate designation unit 15 transmits 1C, which is a request value, to each power conditioner PCS _Bk as a C rate designation value.

Next, in each power conditioner PCS _Bk , the C rate setting unit 32 receives the C rate designation value transmitted from the C rate designation unit 15 of the centralized management device MC1. Then, when the C rate setting value (the above-mentioned reception setting value) at the time when the C rate specified value is received and the received C rate specified value are different, the C rate setting unit 32 sets the C rate setting value. The value is changed step by step from the set value at the time of reception to the specified value of C rate. Specifically, the C rate setting unit 32 changes the C rate setting value from the reception setting value to the C rate specified value by a preset unit update amount for each predetermined update cycle. For example, when the reception setting value is 0C and the received C rate designation value is 1C, the reception setting value and the C rate designation value are different. Therefore, the C rate setting unit 32 sets the C rate setting value. , From 0C, which is the set value at the time of reception, to 1C, which is the C rate specified value, the value is increased by 0.05C (unit update amount) every 1 sec (every update cycle) after the C rate specified value is received. Therefore, in this case, the C rate setting unit 32 changes the C rate setting value in each power conditioner PCS _Bk step by step over 20 sec.

As described above, when the user performs an operation to change the C rate setting value in the centralized management device MC1, the C rate setting value is changed from the reception setting value to the C rate in each power conditioner PCS _Bk . It is changed step by step up to the specified value.

Next, in the photovoltaic power generation system PVS1, the change in the output power of the photovoltaic power generation system PVS1 when the set value of the C rate was changed was verified by simulation. Further, the simulation was similarly performed in the conventional solar power generation system PVS0. The conventional photovoltaic power generation system PVS0 uses the power conditioner PCS _Bk'instead of the power conditioner PCS _Bk according to the photovoltaic power generation system PVS1 of the present embodiment. The power conditioner PCS _Bk'is provided with a conventional C rate setting unit instead of the C rate setting unit 32 of the power conditioner PCS _Bk , and the other configurations are the same as those of the power conditioner PCS _Bk . When changing the C rate setting value, the conventional C rate setting unit does not change it step by step like the C rate setting unit 32, but changes it all at once (changes according to the C rate specified value). Is.

In this simulation, the set value of the discharge rate C _rate ^P was changed from 0C to 1C. Further, in this simulation, the control index pr _B was fixed to -100, assuming that the power conditioners PCS _Bk'and PCS _Bk have the control index limit pr _B ^lmt of 100 (see FIG. 4).

FIG. 5A shows the simulation results of the conventional photovoltaic system PVS0, and FIG. 5B shows the simulation results of the photovoltaic system PVS1 of the present embodiment. In FIGS. 5A and 5B, the upper time chart (upper diagram) shows the time change of the control index pr _B with respect to the power conditioner PCS _{Bk'and PCS Bk ,} and the middle time chart (middle diagram) shows the power conditioner. The time change of the set value of the C rate (discharge rate C _rate ^P ) in PCS _Bk'and PCS _Bk is shown in the time chart (lower figure) of the power conditioner PCS _Bk'and the individual output power P _Bk ^out in PCS _Bk . It shows the time change of each. The broken line shown in the middle diagram of FIGS. 5A and 5B shows the time change of the C rate specified value transmitted from the centralized management device MC1. Further, the lower view of FIGS. 5A and 5B shows the power conditioner PCS _Bk ', which is one of the plurality of power conditioners PCS _Bk'and PCS _Bk included in the solar power generation systems PVS0 and PVS1. This is the simulation result of the power conditioners PCS _Bk'and PCS _Bk , which are PCS _Bk and have a rated output of 250 kW.

In the photovoltaic power generation system PVS0, as shown in FIG. 5A, the period from the start of the simulation to the change of the C rate specified value of the discharge rate C _rate ^P (time t = 0 to 10 [sec]]. ), 0C is set as the set value of the discharge rate C _rate ^P. Therefore, the individual target power P _Bk ^ref calculated by the target power calculation unit 33 is 0 kW due to the C rate constraint shown in the above equation (5c). In the power conditioner PCS _Bk ', the individual output power P _Bk ^out is controlled by the output control unit 34 so as to be the individual target power P _Bk ^ref . Therefore, as shown in the lower diagram of FIG. 5A, the individual output power P _Bk ^out is 0 kW. Then, when the C rate specified value of the discharge rate C _rate ^P is changed at time t = 10 [sec], the set value of the discharge rate C _rate ^P is changed from 0C to 1C as shown in the middle diagram of FIG. 5 (a). Has been changed to. As a result, as shown in the lower diagram of FIG. 5A, the individual output power P _Bk ^out is instantaneously 250 kW at time t = 10 [sec]. If the PV system PVS0 is equipped with one power conditioner PCS _Bk ', the change is only 250 kW, but if it is equipped with 100 power conditioner PCS _Bk ', for example, the rated output is 250 kW. , 25 MW of power will change instantaneously. This may adversely affect the power system A as described above. In addition, the power control of the photovoltaic power generation system PVS0 may not be properly performed.

On the other hand, in the photovoltaic power generation system PVS1, as shown in FIG. 5B, the period t = 0 to 10 [sec] is the same as that of the conventional photovoltaic power generation system PVS0. However, when the C rate specified value of the discharge rate C _rate ^P is changed at time t = 10 [sec], the set value of the discharge rate C _rate ^P is 1 sec as shown in the middle diagram of FIG. 5 (b). It increases by 0.05C with each passage. This is because the C rate setting unit 32 increases the set value of the discharge rate C _rate ^P by 0.05 C each time 1 sec elapses. At this time, as the set value of the discharge rate C _rate ^P increases by 0.05 C, the individual output power P _Bk ^out increases by about 12.5 kW as shown in the lower diagram of FIG. 5 (b). This is because the upper limit of the C rate constraint is 12.5 kW (= 0.05 [C] × 250 [kW]) in the C rate constraint (formula (5c)) of the optimization problem (formula (5) above). This is because it increases little by little. Therefore, the calculated individual target power P _Bk ^ref increases by 12.5 kW, and the individual output power P _Bk ^out increases by 12.5 kW. Then, when 20 seconds have elapsed since the C rate specified value of the discharge rate C _rate ^P was changed (time t = 30 [sec]), the set value of the discharge rate C _rate ^P became 1C, and the individual output power P. _Bk ^out is 250 kW, which is the rated output of the power conditioner PCS _Bk .

In the above simulation, the case where the set value of the discharge rate C _rate ^P is increased is shown, but similarly, when the set value of the discharge rate C _rate ^P is decreased, the set value of the discharge rate C _rate ^P is stepwise. Therefore, the output power (individual output power P _Bk ^out ) is gradually reduced.

From the above, in the photovoltaic power generation system PVS1, the interconnection point power P (t) suddenly increases even when the operation to change the set value of the C rate (discharge rate C _rate ^P ) is performed. It is possible to suppress the change to. That is, it is possible to suppress a sudden change in the output power of the photovoltaic power generation system PVS1. In the above simulation, the case where the set value of the discharge rate C _rate ^P is changed is shown, but even when the set value of the charge rate C _rate ^M is changed, each power conditioner can be changed step by step. The output power from the _PCS B _k to the storage battery B k can be changed stepwise. That is, the photovoltaic power generation system PVS1 can similarly suppress a sudden change in the output power of the photovoltaic power generation system PVS1 even when the storage battery B _k is charged.

Next, the operation and effect of the photovoltaic power generation system PVS1 according to the first embodiment will be described.

According to the first embodiment, the C rate setting unit 32 sets the C rate as the C rate setting value based on the C rate designation value received from the C rate designation unit 15, and determines the C rate when the C rate designation value is received. Change step by step from the set value (set value at the time of reception) to the C rate specified value. As a result, the calculated individual target power P _Bk ^ref changes stepwise in the same manner as the change in the C rate set value, so that the individual output power P _Bk ^out also changes in the same manner as the change in the C rate set value. It changes in stages. From the above, even when the C rate specified value is changed, the C rate setting value is not changed at once, so that it is possible to suppress a sudden change in the output power of the photovoltaic power generation system PVS1. Therefore, it is possible to suppress an adverse effect on the power system A due to a sudden change in the output power of the photovoltaic power generation system PVS1. Further, by suppressing a sudden change in the output power of the photovoltaic power generation system PVS1, it is possible to suppress that the power control using the control indexes pr _PV and pr _B cannot be appropriately performed.

In the first embodiment, a case where a user performs an operation of designating a request value by using an operation device (not shown) of the centralized management device MC1 is shown, but the present invention is not limited to this. For example, it may be a management device for collectively managing a plurality of photovoltaic power generation systems PVS1 and may be configured so that a request value can be specified in a central management device higher than the centralized management device MC1. In this case, when the user performs an operation of specifying a request value in the central management device, the request value specified by this operation is transmitted to the centralized management device MC1. Then, the request value received by the centralized management device MC1 is set as a C rate specified value and transmitted to each power conditioner PCS _Bk .

In the first embodiment, the C rate specified value is transmitted from the centralized management device MC1, and each power conditioner PCS _Bk that receives the C rate specified value steps the C rate set value from the received set value to the C rate specified value. However, the case is not limited to this. For example, it can be transformed as follows. When the user performs an operation to change the request value to the centralized management device MC1, the C rate designation unit 15 of the centralized management device MC1 changes the C rate from the request value before the change operation to the request value after the change operation. The specified value is changed step by step, and each time it is changed, it is transmitted to each power conditioner PCS _Bk . Then, each power conditioner PCS _Bk sets the C rate setting value to the received C rate specified value. Even with such a configuration, since the set value of the C rate of each power conditioner PCS _Bk is changed stepwise, it is possible to suppress a sudden change in the output power of the photovoltaic power generation system PVS1. When the user can specify the request value in the central management device as described above, the specified request value is transmitted from the central management device to the central management device MC1, and the central management device MC1 is the central management device. Based on the request value received from, the C rate specified value to be changed stepwise may be configured to be transmitted to each power conditioner PCS _Bk .

In the first embodiment, the case where the C rate setting value is changed by the user operation is shown, but the change of the C rate setting value is not limited to this. Since the C rate setting value may be changed even in the following situations, the C rate setting value may be changed stepwise even in such a situation.

For example, at the time of peak cut control, the discharge of the storage battery B _k is prioritized, and the electric power stored in the storage battery B _k is reduced. Therefore, there is a possibility that the power required for the storage battery B _k is not stored even though the storage battery B _k is desired to be discharged by the peak cut control. Therefore, the set value of the charge rate C _rate ^M may be changed to control the charging of the storage battery B _k , and the storage battery B _k may be charged in preparation for the discharge by the next peak cut control. For example, when the set value of the charge rate C _rate ^M is 0C, it is possible not to charge the battery, and the larger the set value of the charge rate C _rate ^M is, the faster the charging speed can be. Even when the set value of the charge rate C _rate ^M is changed in such control, the output of the photovoltaic power generation system PVS1 can be output by gradually changing the set value of the C rate (charge rate C _rate ^M ). It is possible to suppress a sudden change in electric power.

Further, for example, during reverse power flow avoidance control, charging of the storage battery B _k is prioritized, and electric power is stored in the storage battery B _k . Therefore, although it is desired to charge the storage battery B _k by reverse power flow avoidance control, there is a possibility that the storage battery B _k is fully charged and the storage battery B _k cannot be charged. Therefore, the set value of the discharge rate C _rate ^P may be changed to control the discharge of the storage battery B _k , and the storage battery B _k may be discharged in preparation for the next charge by the reverse power flow avoidance control. For example, when the set value of the discharge rate C _rate ^P is 0C, the discharge can be prevented, and the larger the set value of the discharge rate C _rate ^P , the faster the discharge rate. Even when the set value of the discharge rate C _rate ^P is changed in such control, the output of the photovoltaic power generation system PVS1 can be output by gradually changing the set value of the C rate (discharge rate C _rate ^P ). It is possible to suppress a sudden change in electric power.

The case where the C rate setting value is changed is not limited to the above two examples, and in other cases, the photovoltaic power generation system PVS1 sets the C rate setting value of each power conditioner PCS _Bk . It may be changed step by step.

Next, the solar power generation system PVS2 according to the second embodiment will be described. The same or similar configurations as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. The overall configuration of the photovoltaic power generation system PVS2 is the same as that of the photovoltaic power generation system PVS1 according to the first embodiment shown in FIG.

FIG. 6 shows the mechanism configuration of the control system related to the power control of the photovoltaic power generation system PVS2. As shown in the figure, the photovoltaic power generation system PVS2 is different from the photovoltaic power generation system PVS1 in that each power conditioner PCS _Bk further includes a connection determination unit 35.

The connection determination unit 35 determines whether or not the own device (power conditioner PCS _Bk ) is connected to the power line 90. In the following description, the state of being connected to the power line 90 is referred to as a "connected state", and the state of not being connected to the power line 90 is referred to as a "non-connected state". Each power conditioner PCS _Bk can charge and discharge the storage battery B _k when it is in the connected state, and cannot charge and discharge the storage battery B _k when it is in the non-connected state. Whether the connected state or the disconnected state is determined is determined based on, for example, the state of a switch (not shown) for connecting each power conditioner PCS _Bk to the power line 90. The connection determination unit 35 determines that the power conditioner PCS _Bk is in the connected state when the switch is in the conductive state, and the power conditioner PCS _Bk is in the non-connected state when the switch is in the cutoff state. Judge.

Even if the C rate setting unit 32 in the second embodiment receives the C rate designation value transmitted from the centralized management device MC1 (C rate designation unit 15), the connection determination unit 35 determines that the connection is not connected. If so, the C rate setting value is not set to the received C rate specified value, but is set to a predetermined predetermined value. In this embodiment, 0C is used as a predetermined value, but the present invention is not limited to this. On the other hand, when the connection determination unit 35 determines that the connection state is established, the C rate setting value is set to the received C rate specified value. Therefore, when the C rate designation value received from the C rate designation unit 15 is different from the above predetermined value, it is necessary to change the C rate setting value when the non-connection state is switched to the connection state. For example, when each power conditioner PCS _Bk is newly connected to the power line 90, each power conditioner PCS _Bk switches from the non-connected state to the connected state. Therefore, the C rate setting unit 32 gradually changes the C rate setting value from the above-mentioned predetermined value to the C rate specified value when the non-connected state is switched to the connected state. The method in which the C rate setting unit 32 changes the C rate setting value stepwise is the same as the C rate setting unit 32 according to the first embodiment.

Next, in the photovoltaic power generation system PVS2, the output power of the power conditioner PCS _Bk (individual output power P _Bk ^out ) when the power conditioner PCS _Bk having a rated output of 250 kW changes from the non-connected state to the connected state. The change in was verified by simulation. Similar to the first embodiment, the simulation was also performed in the conventional solar power generation system PVS0.

In this simulation, it is assumed that 1C is transmitted from the centralized management device MC1 to each power conditioner, PCS _Bk ', and PCS _Bk as the C rate specified value of the discharge rate C _rate ^P. Further, the control index pr _B was fixed to -100 as in the simulation in the first embodiment.

FIG. 7A shows the simulation results of the conventional photovoltaic system PVS0, and FIG. 7B shows the simulation results of the photovoltaic system PVS2 of the present embodiment. In FIGS. 7 (a) and 7 (b), the upper time chart (upper figure) shows the time change of the control index pr _B with respect to the power conditioner PCS _{Bk'and PCS Bk ,} and the middle time chart (middle figure) shows the power condition. The time change of the set value of the C rate (discharge rate C _rate ^P ) in PCS _Bk'and PCS _Bk is shown in the time chart (lower figure) of the power conditioner PCS _Bk'and the individual output power P _Bk ^out in PCS _Bk . It shows the time change of each. In the lower part of FIGS. 7A and 7B, as in FIG. 5, the power of any one of the plurality of power conditioners PCS _Bk'and PCS _Bk included in the solar power generation systems PVS0 and PVS1 is shown. These are the simulation results of the power conditioners PCS _{Bk'and PCS Bk ,} which are conditioners PCS _Bk'and PCS _Bk and have a rated output of 250 kW. In this simulation, it is assumed that the power conditioners PCS _{Bk'and PCS Bk are} switched from the non-connected state to the connected state at time t = 5 [sec]. That is, at time t = 0 to 5 [sec], the power conditioner PCS _{Bk'and PCS Bk are} disconnected, and at time t = 5 to 35 [sec], the power conditioner PCS _Bk'and PCS are disconnected. _Bk is assumed to be connected.

In the photovoltaic power generation system PVS0, even if the power conditioner PCS _Bk'is not connected, if the C rate specified value is received from the centralized management device MC1, the C rate setting value is the C rate. It was configured to be the specified value. Therefore, as shown in the middle diagram of FIG. 7 (a), the period in which the power conditioner PCS _Bk'is in the non-connected state (time t = 0 to 5 [sec]) and the period in which the power conditioner is in the connected state (time t =). In both 5 to 35 [sec]), 1C is set as the set value of the discharge rate C _rate ^P. Further, in the photovoltaic power generation system PVS0, as shown in the lower diagram of FIG. 7A, the power conditioner PCS _Bk'is used for power during the non-connected period (time t = 0 to 5 [sec]). Is not possible, so even if 1C is set as the set value of the discharge rate C _rate ^P , the individual output power P _Bk ^out is 0 kW. On the other hand, since power can be output during the connected state (time t = 5 to 35 [sec]), the individual output power P _Bk ^out is 250 kW according to the set value (1C) of the discharge rate C _rate ^P. .. Therefore, at the same time that the power conditioner PCS _Bk'changes from the disconnected state to the connected state, the individual output power P _Bk ^out instantly rises to the rated output of 250 kW. In the photovoltaic power generation system PVS0, when one power conditioner PCS _Bk'is changed from the disconnected state to the connected state, the change is 250 kW, but many power conditioners PCS _Bk'are changed from the disconnected state all at once. When the connection state is established, the output power of the photovoltaic power generation system PVS0 changes abruptly. This may adversely affect the power system A. In addition, the power control of the photovoltaic power generation system PVS0 may not be properly performed.

On the other hand, in the photovoltaic power generation system _PVS2 , as shown in the middle diagram of FIG. 7B, the power conditioner is in the non-connected state (time t = 0 to 5 [sec]). Even if the PCS _Bk receives the C rate specified value from the centralized management device MC1, the set value of the discharge rate C _rate ^P is a predetermined value (0C). Then, when the power conditioner PCS _Bk changes from the non-connected state to the connected state at time t = 5 [sec], the set value of the discharge rate C _rate ^P changes once from the predetermined value (0C) to the C rate specified value (1C). It does not change to, but increases by 0.05C every 1 sec from the predetermined value (0C). Then, at time t = 25 [sec], the set value of the discharge rate C _rate ^P becomes the C rate designated value (1C). Therefore, as shown in the middle diagram of FIG. 7B, the set value of the discharge rate C _rate ^P is a predetermined value (0C) when the power conditioner PCS _Bk is in the non-connected state, and is connected from the non-connected state. In the state, it can be seen that the C rate specified value (1C) received from the centralized management device MC1 is gradually changed (increased). Further, as shown in the lower diagram of FIG. 7B, the individual output power P _Bk ^out is the above-mentioned solar power during the period (time t = 0 to 5 [sec]) in which the power conditioner PCS _Bk is not connected. It is 0 kW as in the power generation system PVS0, but it can be seen that after the connection state is established, the voltage gradually increases according to the change in the set value of the discharge rate C _rate ^P. Also in this simulation, since the set value of the discharge rate C _rate ^P changes by 0.05 C every 1 sec, the individual output power P _Bk ^out increases by 12.5 kW every 1 sec. is doing. Then, at time t = 25 [sec], the individual output power P _Bk ^out becomes 250 kW, which is the rated output of the power conditioner PCS _Bk . From the above, the photovoltaic power generation system PVS2 can suppress a sudden change in the output power of the photovoltaic power generation system PVS2 even when the power conditioner PCS _Bk changes from the disconnected state to the connected state. There is.

Furthermore, the case where the photovoltaic power generation system PVS2 is a self-consumption type was verified by simulation. In this simulation, it is assumed that the photovoltaic power generation system PVS2 has a reverse power relay installed and reverse power flow avoidance control is performed. Further, in this simulation, it is assumed that the photovoltaic power generation systems PVS2 and PVS0 consume 200 kW of power due to the power load L, and have one power conditioner PCS _Bk having a rated output of 250 kW. Was assumed. Further, in this simulation, the predetermined value when the power conditioner PCS _Bk is in the non-connected state is set to 0C, and the C rate specified value is set to 1C. In this simulation, unlike the other simulations described above, the control index pr _B is changed depending on the interconnection point power ^P (t) and the target power PC (reverse power flow avoidance target value).

FIG. 8A shows the simulation results of the photovoltaic system PVS0, and FIG. 8B shows the simulation results of the photovoltaic system PVS2. In FIGS. 8A and 8B, the upper time chart (upper figure) shows the time change of the control index pr _B with respect to the power conditioner PCS _{Bk'and PCS Bk ,} and the middle time chart (middle figure) shows the sunlight. The time change of the interconnection point power P (t) in the power generation systems PVS0 and PVS2 is shown, and the time chart of the lower time chart (lower figure) shows the time change of the individual output power P _Bk ^out in the power conditioner PCS _Bk'and PCS _Bk , respectively. ing. In the middle diagram of FIGS. 8A and 8B, the alternate long and short dash line indicates the operation level of the reverse power relay, and the alternate long and short dash line indicates the reverse power flow avoidance target value. In this simulation as well, it is assumed that the power conditioners PCS _{Bk'and PCS Bk are} switched from the non-connected state to the connected state at time t = 5 [sec] as in the simulation shown in FIG.

In the photovoltaic power generation system PVS0, when the power conditioner PCS _Bk'changes from the disconnected state to the connected state at time t = 5 [sec], the individual output power P is shown in the lower diagram of FIG. 8 (a). _Bk ^out has risen to 250kW instantly. As a result, as shown in the middle diagram of FIG. 8A, the interconnection point power P (t) becomes a positive value and exceeds the operation level (0 kW) of the reverse power relay. Therefore, the reverse power flow is established and the reverse power relay operates. As a result, the photovoltaic power generation system PVS0 is disconnected from the power system A by the reverse power relay.

On the other hand, in the photovoltaic power generation system PVS2, when the power conditioner PCS _Bk changes from the non-connected state to the connected state at time t = 5 [sec], the set value of the discharge rate C _rate ^P is changed stepwise. As shown in the lower part of FIG. 8B, the individual output power P _Bk ^out gradually increases. Therefore, as shown in the middle diagram of FIG. 8B, the interconnection point power P (t) is also gradually increased. Then, when the interconnection point power P (t) exceeds the reverse power flow avoidance target value, the reverse power flow avoidance control is performed so that the interconnection point power P (t) matches the reverse power flow avoidance target value. As a result, as shown in the upper diagram of FIG. 8B, the control index pr _B starts to rise from -100 at time t = 15 [sec] (the absolute value of the control index pr _B decreases, that is, that is, It begins to change to approach 0). As a result, at time t = 20 [sec], as shown in the lower diagram of FIG. 8B, the individual output power P _Bk ^out is suppressed, and the increase changes to a decrease. Therefore, as shown in the middle diagram of FIG. 8B, the interconnection point power P (t) also changes from decreasing to increasing, and the interconnection point power P (t) is controlled to be the reverse power flow avoidance target value. ing. At time t = 15 to 20 [sec], the control index pr _B is rising (because the absolute value of the control index pr _B is decreasing), so that the individual output power P _Bk ^out is suppressed. However, the individual output power P _Bk ^out is not suppressed and rises as it is (see the lower diagram in FIG. 8 (b)). This is due to an increase in the set value of the discharge rate C _rate ^P (C rate constraint (formula (5c))) rather than the individual target power P _Bk ^ref (see equation (5a) above) calculated by the control index pr _B. This is because the individual target power P _Bk ^ref determined according to the increase in the upper limit value) is smaller, and the individual target power P _Bk ^ref finally calculated by the target power calculation unit 33 is according to the discharge rate C _rate ^P. Since it is determined, the individual output power P _Bk ^out is not suppressed and is increasing. After time t = 20 [sec], the individual target power P _Bk ^ref calculated by the control index pr _B is determined according to the increase in the set value of the discharge rate C _rate ^P , rather than the individual target power P _Bk . Since the ^ref becomes large, the individual target power P Bk ref finally calculated by the target power calculation unit 33 decreases as the control index pr _B rises (the absolute value of the control index pr _B decreases), and the individual target power P _Bk ^ref decreases. Output power P _Bk ^out is suppressed.

From the simulation results shown above, the photovoltaic power generation system PVS2 can suppress a rapid increase in the interconnection point power P (t). Further, the photovoltaic power generation system PVS2 can prevent the interconnection point power P (t) from exceeding the operation level (0 kW) of the reverse power relay by changing the C rate setting value and the control index pr _B. .. That is, the photovoltaic power generation system PVS2 can appropriately perform power control using the control indexes pr _PV and pr _B , and can suppress the operation of the reverse power relay.

In the two simulations according to the present embodiment shown above, the case where the set value of the discharge rate C _rate ^P increases is shown, but the case where the set value of the discharge rate C _rate ^P is decreased is also the same as the power condition. When the PCS _Bk changes from the disconnected state to the connected state, the set value of the discharge rate C _rate ^P gradually decreases, so that the output power (individual output power P _Bk ^out ) gradually decreases. Further, in these simulations, the case where the set value of the discharge rate C _rate ^P is changed is shown, but the setting value of the charge rate C _rate ^M is similarly changed when the set value of the charge rate C _rate ^M is changed. By changing the value stepwise, the output power from each power conditioner PCS _Bk to the storage battery _Bk can be changed stepwise. That is, the photovoltaic power generation system PVS2 can similarly suppress a sudden change in the output power of the photovoltaic power generation system PVS2 even when the storage battery B _k is charged.

Next, the operation and effect of the photovoltaic power generation system PVS2 according to the second embodiment will be described.

According to the second embodiment, the C rate setting unit 32 sets the C rate to a predetermined value when each power conditioner PCS _Bk is not connected, and when each power conditioner PCS _Bk is connected, the C rate setting unit 32 becomes a predetermined value. The C rate setting value is set to the C rate specified value. Then, when each power conditioner PCS _Bk changes from the non-connected state to the connected state and the C rate setting value needs to be changed, the C rate setting unit 32 specifies the C rate setting value from the predetermined value. The value was changed step by step. As a result, when each power conditioner PCS _Bk changes from the non-connected state to the connected state, it is possible to suppress a sudden change in the individual output power P _Bk ^out of each power conditioner PCS _Bk . Therefore, since it is possible to suppress a sudden change in the output power of the photovoltaic power generation system PVS2, it is possible to suppress an adverse effect on the power system and the inability to properly control the power using the control indicators pr _PV and pr _B. In particular, as can be seen from the simulation results shown in FIG. 8, when the photovoltaic power generation system PVS2 is a self-consumption type, the C rate setting value of each power conditioner PCS _Bk is changed stepwise to be a photovoltaic power generation system. By suppressing the sudden change in the output power of the PVS2, it is possible to reduce the possibility that the photovoltaic power generation system PVS2 is disconnected from the power system A.

According to the second embodiment, 0C is used as a predetermined value in the non-connected state. As a result, each power conditioner PCS _Bk can limit the individual target power P _Bk ^ref calculated by the C rate constraint of the optimization problem shown in the above equation (5) to 0 (the above equation (5c)). can. That is, each individual output power P _Bk ^out of each power conditioner PCS _Bk can be limited to 0. Therefore, when each power conditioner PCS _Bk changes from the non-connected state to the connected state, each individual output power P _Bk ^out can be changed from 0 kW.

In the second embodiment, the case where the C rate specified value is received from the centralized management device MC1 even in the power conditioner PCS _Bk in the non-connected state has been described, but the present invention is not limited to this. For example, the power conditioner PCS _Bk does not receive the C rate specified value transmitted from the centralized management device MC1 when it is in the disconnected state, and the C rate transmitted from the centralized management device MC1 when it is in the connected state. It may be configured to receive a specified value.

In the second embodiment, each power conditioner PCS _Bk determines whether it is in the disconnected state or the connected state, and if it is in the disconnected state, the set value of the C rate is set to a predetermined value. Not limited to this. For example, if the centralized management device MC1 can determine whether each power conditioner PCS _Bk is in a connected state or a disconnected state, it may be configured as follows. That is, the centralized management device MC1 transmits the above-mentioned predetermined value as the C rate specified value to the power conditioner PCS _Bk in the disconnected state, and the C rate is specified to the power conditioner PCS _Bk in the connected state. Send the request value as the value. Then, when the power conditioner PCS _Bk , which is in the disconnected state, becomes connected, the C rate designation unit 15 of the centralized management device MC1 changes the C rate designation value while gradually changing it from the predetermined value to the request value. Each time, the C rate specified value at that time is transmitted to the power conditioner PCS _Bk that has changed from the non-connected state to the connected state. The power conditioner PCS _Bk sets the set value of the C rate to the received C rate specified value. Even in such a configuration, since the C rate setting value of each power conditioner PCS _Bk is changed stepwise, it is possible to suppress a sudden change in the output power of the photovoltaic power generation system PVS2. ..

In the second embodiment, the case where the power conditioner PCS _Bk is changed from the disconnected state to the connected state has been described, but it is also possible to change all or part of the power conditioner PCS _PVi from the disconnected state to the connected state. .. That is, it is conceivable that the power conditioner PCS _PVi is newly connected to the power line 90. At this time, immediately after the power conditioner PCS _PVi is connected, the interconnection point power P (t) may change abruptly due to solar radiation conditions or the like. However, the power conditioner PCS _PVi performs maximum power point tracking control (MPPT control) as described above, and the individual output power P _PVi ^out of the power conditioner PCS _PVi is set to a predetermined cycle (this implementation) by the MPPT control. In the form, it changes stepwise in 1 sec). Further, the power conditioner PCS _PVi is controlled by using the control index pr _PV , and the individual target power P _PVi ^ref is calculated in the calculation cycle of the control index pr _PV (1 sec in this embodiment). By these controls, it is possible to control each individual output power P _PVi ^out so as not to change suddenly.

Next, the solar power generation system PVS3 according to the third embodiment will be described. In the first and second embodiments, the case where the interconnection point power P (t) detected by the interconnection point power detection unit 12 is used as the adjustment target power is shown. In the present embodiment, the sum of the individual output powers P _PVi ^out , P _Bk ^out of each power conditioner PCS _PVi and PCS _Bk and the power consumption PL of the power load _L is calculated, and this is used as the power to be adjusted. show. In the following description, the sum of the individual output powers P _PVi ^out , P _Bk ^out of each power conditioner PCS _PVi and PCS _Bk and the power consumption PL of the power load _L is referred to as “system total output”. Therefore, the photovoltaic power generation system ^PVS3 controls the total output of the system to be the target power PC.

FIG. 9 shows the overall configuration of the photovoltaic power generation system PVS3. As shown in the figure, the photovoltaic power generation system PVS3 includes a plurality of solar cells SP _i , a plurality of power conditioners PCS _PVi , a plurality of storage batteries B _k , a plurality of power conditioners PCS _Bk , and a centralized management device MC3. Consists of having.

The photovoltaic power generation system PVS3 according to the present embodiment does not detect the interconnection point power P (t), and the individual output powers P _PVi ^out , P _Bk ^out , and the power load L of each power conditioner PCS _PVi and PCS _Bk . Calculate the total power consumption P _L (total system output P _total (t)). The total system output P _total (t) is obtained by the arithmetic expression “Σ _i P _PVi ^out + Σ _k P _Bk ^out _−PL ”. Then, the calculated total system output P _total (t) is controlled as the output (adjustment target power) of the entire photovoltaic power generation system ^PVS3 so as to match the target power PC. That is, the photovoltaic power generation system PVS3 performs various power controls using the system total output P _total (t) instead of the interconnection point power P (t).

FIG. 10 shows the functional configuration of the control system related to the power control of the photovoltaic power generation system PVS3 shown in FIG. In FIG. 10, the solar cell SP _i and the storage battery B _k are not shown. Moreover, only the first power conditioners PCS _PVi and PCS _Bk are described, respectively. The photovoltaic power generation system PVS3 is different in that it includes a centralized management device MC3 instead of the centralized management device MC1 according to the first embodiment. In addition, the configurations of each power conditioner PCS _PVi and PCS _Bk are also different.

In the third embodiment, each power conditioner PCS _PVi further includes an output power detection unit 24 and a transmission unit 25 as a control system in power control, as shown in FIG. Further, as shown in FIG. 10, each power conditioner PCS _Bk further includes an output power detection unit 36 and a transmission unit 37 as a control system in power control.

The output power detection unit 24 is provided in each power conditioner PCS _PVi , and detects the individual output power P _PVi ^out of the own device. The output power detection unit 36 is provided in each power conditioner PCS _Bk , and detects the individual output power P _Bk ^out of the own device.

The transmission unit 25 transmits the individual output power P _PVi ^out detected by the output power detection unit 24 to the centralized management device MC3. The transmission unit 37 transmits the individual output power P _Bk ^out detected by the output power detection unit 36 to the centralized management device MC3.

As shown in FIG. 10, the centralized management device MC3 has a target power setting unit 11, a reception unit 16, a total output calculation unit 17, an index calculation unit 18, a transmission unit 14, and a C rate designation as control systems in power control. Includes part 15. That is, as compared with the centralized management device MC1 according to the first embodiment, instead of the interconnection point power detection unit 12 and the index calculation unit 13, the reception unit 16, the total output calculation unit 17, and the index calculation unit 18 are used. It differs in that it has.

The receiving unit 16 receives the individual output powers P _PVi ^out and P _Bk ^out transmitted from the respective power conditioners PCS _PVi and PCS _Bk . Further, the receiving unit 16 receives the power consumption PL transmitted from the power load _L.

The total output calculation unit 17 calculates the system total output P _total (t), which is the sum of the individual output powers P _PVi ^out and P _Bk ^out received by the reception unit 16 and the power consumption P _L of the power load L. In the present embodiment, the total output calculation unit 17 calculates the system total output P _total (t) by adding all the input individual output powers P _PVi ^out , P _Bk ^out and the power consumption P _L of the power load L. do.

The index calculation unit 18 calculates an index (control index pr _PV , pr ^B ) for making the system total output P _total (t) calculated by the total output calculation unit 17 into the target power _PC . At this time, the index calculation unit 18 calculates the Lagrange multiplier λ by using the system total output P _total (t) instead of the interconnection point power P (t) in the above equation (1). Then, the Lagrange multiplier λ calculated by the above equation (2) is calculated as the control indexes pr _PV and pr _B. The calculated control index pr _PV is transmitted to each power conditioner PCS _PVi via the transmission unit 14. Further, the calculated control index pr _B is transmitted to each power conditioner PCS _Bk via the transmission unit 14.

Similarly to the first embodiment, the solar power generation system PVS3 configured as described above can be configured so that the set value of the C rate of each power conditioner PCS _Bk is changed stepwise. .. Thereby, as in the first embodiment, even when the C rate designated value is changed, it is possible to suppress the sudden change in the output power of the photovoltaic power generation system PVS3.

The photovoltaic power generation system PVS3 according to the third embodiment has a total system output P _total (t) instead of the interconnection point power P (t) as the adjustment target power in the photovoltaic power generation system PVS1 according to the first embodiment. However, in the photovoltaic power generation system PVS2 according to the second embodiment, the system total output P _total (t) is used instead of the interconnection point power P (t) as the adjustment target power. It may be configured. In this case, as in the second embodiment, even when each power conditioner PCS _Bk is changed from the non-connected state to the connected state, it is possible to suppress a sudden change in the output power of the photovoltaic power generation system PVS3.

Further, in the schedule control in the third embodiment, the output power of the entire photovoltaic power generation system PVS3 (system total output P _total (t)) is not used as the power to be adjusted, but a plurality of power conditioners PCS _PVi , PCS. The output power of each group when _Bk is divided into a plurality of groups may be used. In this case, a target power is set for each group, and schedule control is performed so that the output power in each group becomes the target power of the group.

In the first to third embodiments, the case where the set value of the C rate in each power conditioner PCS _Bk is changed by a preset unit update amount (for example, 0.05 C) is shown, but the present invention is limited to this. Not done. For example, the C rate setting unit 32 may appropriately change the unit update amount based on the difference between the reception set value and the C rate specified value each time the C rate specified value is changed. Specifically, the time required to change from the reception set value to the C rate specified value (hereinafter referred to as "necessary time") and the above-mentioned update cycle are set in advance in each power conditioner PCS _Bk . Then, when the C rate specified value is changed, the difference (target update amount) between the reception set value and the C rate specified value is calculated, and the calculated target update amount, the required time, and the update cycle are used. , "Target update amount ÷ (required time ÷ update cycle)" is calculated. This calculation result is used as the unit update amount. For example, it is assumed that 20 sec is set as the required time and 1 sec is set as the update cycle, and the C rate specified value is changed from 0C to 0.5C. That is, it is assumed that the reception setting value of 0C is changed to the C rate specified value of 0.5C over a required time of 20 seconds with an update cycle of 1 sec. At this time, the C rate setting unit 32 first calculates the difference (0.5C-0C) between the reception set value and the C rate designated value, and calculates the target update amount as 0.5C. Next, the C rate setting unit 32 uses the calculated target update amount to set the unit update amount to 0.025 C (= 0.5 [C] ÷ (20 [sec] ÷ 1 [sec]] by the above calculation formula. )). Therefore, the unit update amount in this case is 0.025C. Further, when changing from 0C, which is the set value at the time of reception, to 2C, which is the C rate specified value, over a required time of 20 sec with an update cycle of 1 sec, the unit update amount is calculated by the C rate setting unit 32 in the same manner. Is 0.1C (= 2 [C] ÷ (20 [sec] ÷ 1 [sec])). As described above, the unit update amount may be changed each time the C rate specified value is changed. The above numerical values are examples and are not limited to these.

When changing the unit update amount as described above, an upper limit of the unit update amount is set, and if the calculated unit update amount exceeds the set upper limit, it is limited by this upper limit. It is good to configure it in. By doing so, it is possible to prevent the unit update amount from becoming too large and the individual output power P _Bk ^out of each power conditioner PCS _Bk from suddenly changing. Further, depending on the calculated target update amount, either the first unit update amount or the second unit update amount different from each other may be used. Specifically, when the calculated target update amount is less than the predetermined threshold value, the C rate setting unit 32 uses the preset first unit update amount, and when the calculated target update amount is equal to or more than the threshold value. It may be configured to use a preset second unit update amount. The second unit update amount is larger than the first unit update amount. Further, for either the first unit update amount or the second unit update amount, the unit update amount obtained by the above calculation formula (“target update amount ÷ (necessary time ÷ update cycle)”) may be used. good.

In the first to third embodiments, the case where the "characteristic value" of the present invention is the C rate has been described as an example, but the present invention is not limited thereto. For example, a constraint condition different from the constraint condition in the optimization problem shown in the above equation (5) is used, and a characteristic value that limits the input / output power at the time of charging / discharging of the storage battery B _k is used as the constraint condition. In some cases, the setting value of this characteristic value may be changed stepwise instead of the setting value of the C rate.

In the first to third embodiments, the case where the centralized management device MC1 (MC3) calculates the control indexes pr _PV and pr _B is shown, but the present invention is not limited thereto. For example, the centralized management device MC1 (MC3) calculates the individual target powers P _PVi ^ref and P _Bk ^ref for each of a plurality of power conditioners PCS _PVi and PCS _Bk instead of the control indexes pr _PV and pr _B. May be good. In this case, the centralized management device MC1 (MC3) has a plurality of power conditioners PCS _PVi , based on the adjustment target power (interconnection point power P (t) or system total output P _total (t)) and the target power. Calculate the individual target power P _PVi ^ref and P _Bk ^ref for each PCS _Bk . Then, each power conditioner PCS _PVi and PCS _Bk acquire the individual target powers P _PVi ^ref and P _Bk ^ref for their own device from the centralized management device MC1 (MC3), and the individual output powers P _PVi ^out and P _Bk ^out are individual. The target power is controlled to be P _PVi ^ref and P _Bk ^ref . At this time, each power conditioner PCS _Bk is limited to the input / output power at the time of charging / discharging of the storage battery B _k , that is, the individual output power P _Bk ^out , based on the set value of the set C rate. Even in such a case, the C rate setting unit 32 can suppress a sudden change in the output power of the photovoltaic power generation system by changing the C rate setting value stepwise.

In the first to third embodiments, the case where the electric power system of the present disclosure is a solar power generation system has been described as an example, but the present invention is not limited to this. The power system may be another power generation system. Other power generation systems include, for example, a wind power generation system, a fuel cell power generation system, a rotary generator power generation system, and a virtual power generation system that manages the load of consumers by an aggregator that conducts negative watt trading. Conceivable. It should be noted that the aggregator does not actually generate electricity because it considers the electricity saved by the negawatt transaction to be the generated electricity. Even in the case of these power generation systems, the centralized management device detects the interconnection point power or calculates the sum of the individual output powers to be the adjustment target power, calculates the index, and transmits it to each power control device. Then, the power control device of each power generation system calculates the individual target power of its own device based on the optimization problem using the received index, and controls the individual output power so as to be the individual target power. In the case of solar power generation systems, wind power generation systems and fuel cell power generation systems, the power control device is a power conditioner. Further, in the case of a power generation system using a rotary machine type generator, the power control device is a generator and a control device for controlling the generator. Further, in the case of a power generation system using an aggregator, the power control device is a load of the consumer and a control device for controlling the load. In the power generation system using the aggregator, the saved power is regarded as the generated power, so the power reduced from the normal power consumption of the load of the consumer is the individual output power. Further, the electric power system may be used in combination with the power generation system described above. For example, a rotary generator is added to the PV system, and the centralized management device sends an index to each power conditioner of the PV system and the controller of the generator to control the overall output. May be.

The power system and the storage battery power conditioner according to the present disclosure are not limited to the above-described embodiment, and the specific configuration of each part can be freely redesigned as long as the contents described in the claims are not deviated. Is.

PVS1 to PVS3: Photovoltaic power generation system A: Power system L: Power load MC1, MC3: Centralized management device 11: Target power setting unit 12: Interconnection point power detection unit 13: Index calculation unit 14: Transmission unit 15: C rate Designated unit 16: Receiving unit 17: Total output calculation unit 18: Index calculation unit SP _i : Solar cell PCS _PVi : Power conditioner 21: Receiving unit 22: Target power calculation unit 23: Output control unit 24: Output power detection unit 25 : Transmission unit B _k : Storage battery PCS _Bk : Power conditioner 31: Reception unit 32: C rate setting unit 33: Target power calculation unit 34: Output control unit 35: Connection determination unit 36: Output power detection unit 37: Transmission unit 90 : Power line

Claims (8)

A power control device that receives power from a power generation device, and
A storage battery power conditioner that controls the charging and discharging of the storage battery,
A power line to which the power control device and the storage battery power conditioner are connected and connected to a power system,
The electric power control device and the centralized management device for managing the storage battery power conditioner are provided.
The storage battery power conditioner is provided with a setting means for setting a characteristic value for limiting the input / output power at the time of charging / discharging of the storage battery.
The characteristic value set by the setting means is gradually changed from the currently set current value to the specified value when the new set value is changed to the specified value .
The unit update amount of the characteristic value at the time of changing the characteristic value is changed based on the difference between the current value and the designated value.
A power system characterized by that. The centralized management device includes a designated means for transmitting the designated value to the storage battery power conditioner.
The setting means gradually changes the characteristic value from the current value to the designated value received from the centralized management device.
The power system according to claim 1. The storage battery power conditioner further includes a connection determination means for determining whether or not the storage battery power conditioner is connected to the power line.
When it is determined by the connection determination means that the setting means is not connected, a predetermined value is set in the characteristic value, while when it is determined that the setting means is connected, the characteristic value is set to the specified value. change,
The power system according to claim 1 or 2. The characteristic value is a C rate indicating a relative ratio of input / output current during charging / discharging to the total capacity of the storage battery.
The electric power system according to any one of claims 1 to 3. The centralized management device calculates an index for controlling the power to be adjusted to the target power, and calculates the index.
Each of the power controller and the storage battery power conditioner controls the individual output power based on the optimization problem using the index.
The electric power system according to any one of claims 1 to 4. The characteristic value is used as a constraint condition in the optimization problem of the storage battery power conditioner.
The power system according to claim 5. It is a storage battery power conditioner that is connected to the power line connected to the power system and controls the input / output power during charging and discharging of the storage battery.
A target power calculation means for calculating an individual target power, which is a target value of the output power of the storage battery power conditioner, and
An output control means that controls the individual output power so as to be the individual target power,
A setting means for setting a characteristic value for limiting the input / output power during charging / discharging of the storage battery, and
Equipped with
When the characteristic value is changed to a designated value which is a new set value, the setting means gradually changes from the currently set current value to the designated value , and when the characteristic value is changed, the setting means concerned. The unit update amount of the characteristic value is changed based on the difference between the current value and the specified value.
A storage battery power conditioner that features that. Further, it is provided with a receiving means for receiving an index for controlling the input / output power at the time of charging / discharging of the storage battery, which is transmitted from the centralized management device that manages the storage battery power conditioner.
The target power calculation means calculates the individual target power based on the optimization problem using the index.
The storage battery power conditioner according to claim 7.

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