JP2024022452A - Power generation control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generation control system that can utilize a renewable energy obtained by photovoltaic power generation more efficiently.

SOLUTION: A power generation control system 100 has: a solar battery that outputs a power via a maximum power point tracking (MPPT) device; an accumulator battery that can charge the power of the solar battery; a power substation connected with a power grid and a load; a power conditioner (PCS) having a unidirectional inverter that outputs a DC power from the MPPT device and the accumulator battery to an AC side including the power substation; and a monitoring control device that controls the output of the PCS. The monitoring control device controls a power to be outputted from the PCS to the power substation so that a differential power obtained by subtracting a power flowing into the PCS from the power from the MPPT device is used for charging the accumulator battery in a case where the differential power is positive, or alternatively, so that the differential power is given to the PCS from the accumulator battery by discharging of the accumulator battery in a case where the differential power is negative.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a power generation control system.

A technology that promotes the use of clean energy and reduces fossil fuel consumption by using solar power in homes, offices, factories, etc. in addition to the power from the power grid supplied by power companies. There is a need to promote development.

For example, a power conditioner that controls the power generated by a solar cell, a power receiving and transforming section connected to the load, and a power generation control device that acquires the power consumption of the load and controls the output of the power conditioner, The control device calculates the output command value by setting the upper limit value of the generated power so that the difference between the upper limit value of the generated power and the power consumption becomes a linear function of the power consumption, and controls the power conditioner based on the output command value. There is a technology that avoids reverse power flow by controlling the generated power to be below an upper limit value (for example, see Patent Document 1).

The control unit is configured to be able to control a bidirectional inverter connected between an AC side including a load receiving power from the power grid and a DC side including a renewable energy power generation device and a power storage device. Obtain predicted values of the amount of power generated by the available energy power generation device and the amount of power consumed by the load at a plurality of times between a first time and a second time, and determine the target charging amount of the power storage device at the second time. Assuming that, the target charge amount at the first time is updated by applying the predicted value at each time from the second time to the first time to the assumed target charge amount, and updating the target charge amount at each time. There is a technology that calculates the amount of charge and causes a bidirectional inverter to perform a charging operation from the AC side to the DC side or a discharging operation from the DC side to the AC side based on the target amount of charge at the first time. (For example, see Patent Document 2).

Patent No. 6364567 Patent No. 6664680

The purpose of the disclosed technology is to provide a technology that can more efficiently utilize renewable energy obtained from solar power generation while suppressing the impact of reverse power flow on the grid using a simply configured system. do.

The disclosed technology includes a solar cell that outputs power through a maximum power tracking device, a storage battery that is connected to the maximum power tracking device and can charge the power of the solar cell, and a power receiving substation that is connected to a power grid and a load. a power conditioner having a one-way inverter that outputs DC power from the maximum power tracking device and the storage battery to an AC side including the power receiving and transforming unit; and a monitoring control that controls the output of the power conditioner. and a device, the monitoring and control device is configured to charge the storage battery with the difference in power when the difference in power obtained by subtracting the power from the maximum power tracking device by the power flowing into the power conditioner is positive. or so that when the differential power is negative, the storage battery is discharged so that the differential power can be provided from the storage battery to the power conditioner, A power generation control system is provided that controls power output from the power conditioner to the power receiving and transforming section.
Furthermore, in the disclosed technology, the supervisory control device is configured to provide power from the maximum power tracking device even if the power conditioner is capable of supplying power to the load using the power from the maximum power tracking device. the power conditioner from receiving a portion of the power, and replenishes the reduced power that can be provided from the power conditioner to the load due to the suppressed power. The power output from the power conditioner to the power receiving and transforming unit may be controlled so that the suppressed part of the power is used for charging the storage battery by supplying power acquired from the power grid to the load. good.
Furthermore, in the disclosed technology, the supervisory control device determines the maximum amount of power received in a day from the power grid based on information including power generation prediction data of the solar cells and power consumption prediction data of the load. The power output from the power conditioner to the power receiving and transforming unit may be controlled so that the value does not exceed a predetermined value.

Further, in the disclosed technology, the supervisory control device determines the maximum amount of power received from the power grid on the next day based on information including predicted power generation data of the solar cells and predicted power consumption data of the load on the next day. The amount of power stored in the storage battery carried over to the next day may be adjusted by controlling the output of the power conditioner so that the value decreases.

Further, in the disclosed technology, the supervisory control device determines that the total amount of electric power that can be charged to the storage battery is not exceeded, based on information including predicted power generation data of the solar cell and predicted power consumption data of the load. The output of the power conditioner may be controlled in this manner.

Further, in the disclosed technology, if the power consumption of the load is larger than a predetermined value, the supervisory control device may control the output of the power conditioner so that the received power does not exceed the predetermined value. good.
Furthermore, in the disclosed technology, the supervisory control device is configured such that when the power consumption of the load is smaller than a predetermined value, the power from the maximum power tracking device can be used to charge the storage battery. , the output of the power conditioner may be suppressed.
Further, in the disclosed technology, the supervisory control device receives the power generation amount prediction data of the solar cell and the power consumption prediction data of the load multiple times during a day, and receives the power generation amount prediction data of the solar cell. The power consumption prediction data of the load may include information for at least one day.

According to the disclosed technology, it is possible to provide a technology that can use renewable energy obtained from solar power generation more efficiently while suppressing the influence of reverse power flow on the grid using a simply configured system. can.

FIG. 1 is a block diagram showing the configuration of a power generation control system 100 according to an embodiment. FIGS. 2A to 2C are diagrams illustrating how the power generation control system 100 controls the power of each part in response to the operation of the UPR 122 (undervoltage relay). FIGS. 3A and 3B are diagrams showing control for avoiding or reducing adverse effects on the power grid 140 when it is detected that a small reverse power flow has occurred. FIGS. 4A to 4C are diagrams showing the interrelationships among load power, solar power generation power, storage battery charging/discharging power, received power, and the like. FIG. 5 is a diagram showing each hardware configuration that mainly executes processes related to various data collection, control commands, and AI processing in the embodiment. FIG. 6 is a diagram illustrating an example of an equivalent circuit for illustrating the operations of the solar cell, MPPT, storage battery, and PCS.

Embodiments of the disclosure will be described below with reference to the drawings. Each of the following embodiments is not exclusive, and a part of one embodiment may be incorporated into another embodiment, or a part of one embodiment may be replaced with a part of another embodiment. be able to.

Furthermore, each configuration of the disclosed embodiments may be realized by hardware or by a program installed on a computer.
<Embodiment 1>
FIG. 1 is a block diagram showing the configuration of a power generation control system 100 according to an embodiment.

The solar cell 102 converts sunlight energy into electric power. Solar cells typically include multiple cells connected in series or parallel. In the solar cell 102, an aggregate of a plurality of cells forms a solar cell module, and a plurality of solar cell modules may be prepared.

The MPPT 106 performs maximum power point tracking (MPPT) control. In the maximum power follow-up control, the DC voltage on the input side of the MPPT 106 is slightly varied, for example, at fixed time intervals, and the output power of the solar cell 102 at that time is measured. Then, a comparison is made with the previous output power of the solar cell 102, and by changing the DC voltage on the input side of the MPPT 106 in a direction that increases the power obtained from the solar cell 102, the output power from the solar cell 102 is increased. Controls the extraction of the . The MPPT 106 can efficiently supply the power obtained from the solar cell 102 to the output side by controlling the output current according to the voltage on the output side of the MPPT 106.
PCS 108 is a power conditioner, and "PCS" is an abbreviation for Power Conditioning System. In this specification, with the PCS 108 as a boundary, the solar cell side is referred to as the DC side, and the power grid side is referred to as the AC side. It converts the DC power from the DC side into AC power and outputs the AC power that can be used by the load 130 on the AC side. Therefore, the PCS 108 can convert direct current to alternating current using the one-way inverter 109 that converts direct current to alternating current.
Note that the PCS 108 may include a bidirectional inverter 109 having a bidirectional conversion function between DC and AC. The PCS 108 including the bidirectional inverter 109 can also convert alternating current power from the alternating current side into direct current, and supply the direct current power to the storage battery on the direct current side.
FIG. 6 is a diagram showing an example of an equivalent circuit for showing operations of the solar cell 102, MPPT 106, storage battery 104, and PCS 108.
In FIG. 6, the solar cell 102 outputs a current Ip with an electromotive force Vp. In this case, the power obtained from the solar cell is VpIp. The power from the solar cell 102 is affected by the degree of sunlight, temperature, etc., and Ip changes as Vp changes. In order to efficiently obtain power from the solar cell 102, it is preferable to use the MPPT 106 to search for a combination of Vp and Ip that maximizes VpIp.
The equivalent circuit of the MPPT 106 includes a SW that can change the on/off duty ratio, a diode D1, a coil L, a capacitance C, and a diode D2 for preventing backflow. The circuit shown in this MPPT 106 is an example of an equivalent circuit to show its operation. Therefore, it should be noted that MPPT 106 is not limited to this equivalent circuit. The equivalent circuits of the solar cell 102, the storage battery 104, and the PCS 108 are also examples.
As an example, the storage battery 104 is shown as an equivalent circuit in which a voltage source V and an internal resistance r are connected in series.
As an example, the PCS 108 is shown as an equivalent circuit in which the input impedance R changes.
In FIG. 6, by changing the on/off duty ratio of the SW of the MPPT 106, the electromotive force Vp and the output current Ip of the solar cell 102 are changed. Using a control circuit (not shown), to maximize the power VpIp from the solar cell 102, the on/off duty ratio of the SW is changed using, for example, a hill-climbing method, and environmental changes such as sunlight and temperature are adjusted. Maximum power can be extracted from the solar cell 102 depending on the amount of power.
The output of MPPT 106 is connected to storage battery 104 and PCS 108. Since the internal resistance r of the storage battery 104 is small, the output voltage of the MPPT 106 is almost controlled by the voltage of the voltage source V of the storage battery 104. Therefore, instead of maximizing VpIp, MPPT 106 may operate to maximize output current Iout of MPPT 106.
The PCS 108 operates to change the internal impedance R depending on the power supplied to the power receiving and transforming equipment 120.
In the case of the equivalent circuit shown in FIG. 6, the following equation holds.

rIc+R(Iin+Ic)=V (Formula 1)

Iout+Ic=Iin (Formula 2)

Here, Ic is the current flowing from the storage battery 104 to the PCS 108, r is the internal resistance of the storage battery 104, V is the open circuit voltage of the storage battery, Iout is the output current of the MPPT 106, and R is the input impedance of the PCS 108.
The following relationship is derived from the above equations 1 and 2.

Ic=(V-RIout)/(2R+r) (Formula 3)

Therefore, if V>RIout, Ic becomes positive, so power is supplied from the storage battery 104 to the PCS 108 and also from the MPPT 106 to the PCS 108.
Further, if V<RIout, Ic becomes negative, so power is supplied from the MPPT 106 to the storage battery 104 to perform power storage, and power is supplied from the MPPT 106 to the PCS 108.

Since the optimal operating point of the solar cell 102 varies depending on the installation location, weather, temperature, etc., the MPPT 106 makes it possible to extract more power from the solar cell 102. It is desirable that the MPPT 106 operates in cooperation with a PCS 108 (power conditioner) and/or a storage battery 104, which will be described below.

The storage battery 104 can store power by obtaining power from the solar cell 102 via the MPPT 106. Further, the storage battery 104 can supply stored power to the PCS 108.

PCS 108 can accept power from either or both of solar cell 102 and storage battery 104. The PCS 108 has an inverter 109 that converts the received DC power into AC power. The AC power converted by the inverter 109 is output to the power receiving and transforming equipment 120 . The inverter 109 may be a unidirectional inverter 109 that converts direct current to alternating current, or may be a bidirectional inverter 109 that further has a function of converting alternating current to direct current.

The power receiving and transforming equipment 120 is connected to a power system such as a power transmission and distribution company that provides power. The power receiving and transforming equipment 120 can supply power purchased from the power grid 140 and/or power supplied from the PCS 108 to the load 130 and the like.
The power receiving and transforming equipment 120 includes a UPR 122 (underpower relay) and an RPR 124 (reverse power relay).
The power receiving equipment 120 and the like can provide information regarding the operating state to the monitoring and control device 110 described below.

Supervisory control device 110 can receive the operating status of PCS 108 and can communicate commands to PCS 108 to control the operation of PCS 108 .

Further, the supervisory control device 110 can receive the predicted value of the power generated by the solar cell 102, the predicted value of the load power regarding the power required by the load, etc. through a network (not shown) such as the Internet. Further, predicted values of temperature and sunshine, etc. may be received.

The monitoring and control device 110 also detects, from various sensors 112 provided in various devices, the amount of power that can be stored in the storage battery 104, the amount of power generated by the solar cell 102, the temperature of various devices, and the temperature and humidity of the atmosphere. You may also receive weather forecast information, solar radiation, etc.

Note that the predicted power generation value may be predicted by the monitoring and control device 110 itself from predicted values of solar radiation and weather forecast information such as temperature, or this information may be provided from outside. In addition, the load prediction value is calculated by using AI to learn the past power consumption of the load over a certain period of time (one day, one week, season, etc.) and other factors (weather, etc.) to predict the future. Good too. The load prediction may be predicted by the supervisory control device 110, or this information may be provided from the outside via the network 515 (FIG. 5). Alternatively, the operator may provide load prediction information for the next day, one week, holidays, weekdays, etc., for example. Further, the monitoring and control device 110 may predict the load prediction value by being provided with an operation prediction of equipment such as a factory.
Additionally, the supervisory control device 110 may receive the operating status of the UPR 122 and the RPR 124.

The supervisory control device 110 gives an operation command to the PCS 108 based on the received information. The PCS 108 may determine the amount of power to be supplied to the power receiving and transforming equipment 120 based on this operation command.

Note that the PCS 108 may convert AC power from the power receiving and transforming equipment 120 into DC power and provide the DC power to the storage battery 104 . In this case, inverter 109 may be a bidirectional inverter 109. Note that the configuration of the PCS 108 can be simplified by using the inverter 109 included in the PCS 108 as a unidirectional inverter 109 that converts direct current to alternating current.
Note that when the PCS 108 includes the unidirectional inverter 109, power from the power grid 140 cannot be stored in the storage battery 104. However, in the embodiment described later, by supplying power from the power grid 140 to the load 130, it is suppressed that some (or all) of the power generated by the solar cell 102 is used for the load 103. This suppressed power can be used to charge the storage battery 104. By doing so, even if the PCS 108 has only the unidirectional inverter 109, the degree of freedom in the amount of power stored in the storage battery 104 can be increased.
Power storage from the solar cell 102 to the storage battery 104 is performed autonomously via the MPPT 106. Therefore, it is possible to adopt a configuration in which the PCS 108 and the like do not need to directly control this power storage, and the overall hardware configuration is simplified.
The MPPT 106 efficiently acquires power from the solar cell 102 by performing maximum power follow-up control as described above. The output voltage of MPPT 106 is controlled by the electromotive force of connected storage battery 104. This is because, as already stated, the internal resistance r of the storage battery 104 is a small value. When the power generation environment of the solar cell 102 is the same, if the electromotive force of the storage battery 104 increases, the output voltage of the MPPT 106 increases to the same extent as this electromotive force, and the output current decreases.
The relationship between the output power of the MPPT 106, the output power of the PCS 108, and the charging/discharging of the storage battery 104 is as follows.
(1) When output power of PCS 108<output power of MPPT 106 The supervisory control device 110 issues a command to the PCS 108 to adjust the input impedance R of the PCS 108 so that the above conditions are satisfied. By adjusting the input impedance R of the PCS 108, appropriate power flows from the MPPT 106 to the PCS 108, and surplus current Ic flows into the storage battery 104, thereby charging the storage battery 104.
Note that when the storage battery 104 is fully charged, it is desirable that a protection circuit (not shown) prevents the storage battery 104 from being overcharged. In this case, the surplus current Ic does not need to be used for storing power in the storage battery 104.
(2) When output power of PCS 108>output power of MPPT 106 The supervisory control device 110 issues a command to the PCS 108 to adjust the input impedance of the PCS 108 so that the above conditions are satisfied. By adjusting the input impedance of the PCS 108, all the power from the MPPT 106 flows into the PCS 108, and a current Ic corresponding to the insufficient power flows from the storage battery 104 into the PCS 108.
Note that when the amount of electricity stored in the storage battery 104 is zero, no current flows from the storage battery 104 to the PCS 108. In this case, the power receiving/transforming unit 120 may operate so that the insufficient power for the power supplied from the PCS 108 to the load 130 is supplied to the load 130 from the power grid 140 via the power receiving/transforming equipment 120.

The load 130 may be home appliances that consume AC power in a home, or machinery that consumes AC power in a factory, but is not limited thereto.

Note that in FIG. 1, each block is connected by a line with an arrow. It should be noted that the lines indicate primary information, power, etc. flows and the directions of those flows, but these are illustrative. As long as there is no contradiction, it goes without saying that various information or power may flow between certain blocks even if the arrow lines are not connected between them. Moreover, each block may be configured with hardware, or each block may be operated by a computer including a CPU and memory executing a program. Alternatively, multiple blocks may be implemented in one piece of hardware or computer, or one block may be distributed across multiple pieces of hardware or computers.

FIGS. 2A to 2C are diagrams illustrating how the power generation control system 100 controls the power of each part in response to the operation of the UPR 122 (undervoltage relay). FIG. 2A is a graph showing an example when the UPR 122 does not operate, and is a diagram to help understand FIGS. 2B and 2C when the UPR 122 operates.
The operation of the power generation control system 100 when the UPR 122 does not operate will be described using FIG. 2A.

Power obtained by adding the PCS 230 and the received power 220 is supplied to the load 130 via the power receiving and transforming equipment 120 as shown in the load power 210. In this case, the received power is below the predetermined first value 240 at time ta1. This predetermined first value 240 is set in advance to a value where the received power 220 is close to zero. The fact that the received power 220 falls below the predetermined first value 240, which is a value close to zero, at time ta1 indicates that the received power is decreasing. In this case, it can be known that there is a high possibility that the received power will further fall below zero and become a negative value. In FIG. 2A, the PCS output 230 is depicted as keeping a constant value, but this is for the sake of clarity, and it goes without saying that the PCS output 230 may vary depending on the operation of the PCS 108, etc. . This point also applies to other figures.

Note that when the received power 220 takes a negative value, this means that a reverse power flow occurs in which alternating current starts flowing from the power generation control system 100 to the power grid. If reverse power flow is allowed, a negative value of the received power 220 will not have a negative impact on the power grid. However, in order to allow reverse power flow, it is necessary to install equipment to measure the power of reverse power flow, and to make technical and contractual adjustments with the power grid. Therefore, when reverse power flow is allowed, it is necessary to prepare and operate more resources (equipment, etc.) than when reverse power flow is not allowed, and it is necessary to balance the electricity sales price with the cost of the required resources. It is also necessary to consider the following. Therefore, by adopting a system configuration that does not allow reverse power flow, there is an advantage that the power generation control system 100 can be simplified.

For this reason, each embodiment of this specification will be described on the premise that reverse power flow is prevented, or that control is performed to suppress reverse power flow when a slight reverse power flow occurs.

In FIG. 2A, the received power 220 is less than the first value 240 during the period from time ta1 to time ta2. Therefore, it is desirable to control the received power 220 to be equal to or greater than the first value 240 so as to reduce the possibility that the received power becomes negative during the period from time ta1 to time ta2.

FIG. 2B is a graph that sets the PCS output 231 to the second value 231a for a predetermined period t1 after detecting that the received power 220 has fallen below the first value 240.

In FIG. 2B, at time ta1, the UPR 122 detects that the value of the received power 222 has fallen below the first value 240. In response to this detection, UPR 122 transmits a first notification signal to supervisory control device 110.

In response to receiving this first notification signal, the supervisory control device 110 sets the PCS output 231 to (load power 210 - first value 240) for a predetermined period t1 to the PCS 108. It is preferable to send out a control signal (first command) to do so. Then, the PCS 108 provides power of (load power 210 - first value 240) to the power receiving equipment 120 for a predetermined period t1. Therefore, the received power 221 becomes the following power during the period t1.
Received power 221 = load power 210 - PCS output 231
= load power 210 - (load power 210 - first value 240)
= first value 240

In FIG. 2B, the time lag dt is the delay time from time ta1 when the received power 221 falls below the first value 240 until the PCS output 231 becomes (load power 210 - first value 240).
Then, when t1 has elapsed, the supervisory control device 110 stops sending out the control signal to the PCS 108.

In FIG. 2B, an event in which the received power falls below the first value 240 again after the period t1 has elapsed has occurred five times, so the PCS output 231 is (load power 210 - first value 240) during the five t1 periods. The value is 240).

In FIG. 2B, the received power 221 finally falls below the first value 240, time ta2 arrives during the time lag dt, and the received power 221 becomes greater than or equal to the first value during the time lag dt. . Even in this case, the received power 221 may be kept at the first value 240 because the PCS output becomes (load power 210 - first value 240) during the last t1.

In FIG. 2B, as described above, the received power is kept at the first value 240 except during the time lag dt, so it is possible to prevent the received power from becoming negative and causing a reverse power flow. can be prevented. However, if the load power 210 decreases due to a sudden decrease in the power consumption of the load, there is a possibility that the received power 221 becomes a negative value. However, since the output from the PCS 108 decreases, it is possible to effectively reduce the influence of the received power 221 on the power grid 140 due to negative power flow. Alternatively, in the case of instantaneous reverse power flow, there may be no impact on the power grid 140. Therefore, according to the embodiment having the above configuration, the adverse effects that the power generation control system 100 has on the power grid 140 due to reverse power flow can be avoided or reduced in most cases.

FIG. 2C is a graph showing a modification of FIG. 2B. In the case of FIG. 2C, it is a graph when the PCS output 232 during the period t1 is set to a value (231b) smaller than (load power 210 - first value 240).
PCS output 232<load power 210-first value 240
Control is performed so that In the case of FIG. 2C, the received power 222 at t1 has a higher value than the received power 221 in the case of FIG. 2B.
Therefore, the received power 222 in FIG. 2C has a higher value than the received power 221 in the case of FIG. 2B, so that reverse power flow is less likely to occur.

Note that, as already mentioned, in FIG. 2C, the PCS output 232 has returned to its original value after the end of t1. However, FIG. 2C is an example, and the supervisory control device 110 takes into account the PCS output 232, the received power 222, and the first value, and controls the PCS so that the received power does not fall below the first value again. Output 232 may also be controlled. In this case, it is possible to further reduce the possibility that the above notification signal (the notification signal generated when the received power falls below the first value) will occur for the second time or later.

Note that it is possible that the actual load power 210 suddenly decreases. Even in such a case, if the monitoring and control device 110 performs the control shown in FIG. 2B or 2C, there is a high possibility that the occurrence of reverse power flow can be prevented. Alternatively, even if a reverse power flow occurs, the adverse effect of the reverse power flow on the power grid 140 can be further reduced.
Note that in the case of the above embodiment, the inverter 109 may be either a unidirectional inverter or a bidirectional inverter. Note that when the inverter 109 is a bidirectional inverter and power is supplied from the AC side to the DC side by the PCS 108, reverse power flow does not occur in the first place. Therefore, it should be noted that when the inverter 109 is a bidirectional inverter, the above embodiment is applied when power is supplied from the PCS 108 to the AC side.

FIGS. 3A and 3B are diagrams illustrating control for avoiding or reducing adverse effects on the power grid 140 when it is detected that a small reverse power flow has occurred.

FIG. 3A is a graph showing an example in which the PCS output 330 is not controlled when the received power 320 becomes equal to or less than the third value 340, which is a negative value. In this case, received power 320 becomes load power 310 - PCS output 330. As shown in FIG. 3A, at time tb1, the received power 320 is equal to or less than the third value, and a reverse power flow occurs.

The third value is a negative value, and is preferably set to a negative value that does not adversely affect the power grid 140 even if reverse power flow occurs. By performing control to effectively prevent the occurrence of a reverse power flow larger than this third value, it is possible to avoid adverse effects on the power grid 140. Furthermore, by performing the control described below to suppress an increase in reverse power flow, the overall configuration of the power generation control system 100 is simplified.
FIG. 3B is a graph when the reverse power flow is effectively controlled so as not to increase.

The RPR 124 monitors the received power 321, and when the received power 321 becomes equal to or less than the third value at time tb1, the RPR 124 directly sends a second command to the PCS 108 to stop the PCS 108. Or, the output of the PCS 108 is made zero. In this case, since it is desirable to minimize the time lag (delay), it is desirable to send the second command directly from the RPR 124 to the PCS 108 without going through the supervisory control device 110 to control the PCS 108. It is desirable that the output of the PCS 108 be zero or approximately zero. Through this control, the PCS output 331 becomes zero for a predetermined time t2 from time tb1. During this period t2, the PCS output becomes zero, so the received power 321 becomes equal to the load power 310.

By the above control, the time period during which the received power 321 becomes negative and the reverse power flow continues can be effectively shortened, and the amount of power of the reverse power flow can be reduced. Furthermore, since the RPR 124 directly controls the PCS 108, the time lag until the PCS output 331 is reduced to zero can be reduced.

As shown in FIG. 3B, it is desirable to automatically restore the operation of the PCS 108 at time tb2 when time t2 has elapsed from time tb1. By doing so, the time during which the PCS 108 remains stopped can be shortened.
The third value is desirably set to a value that can minimize the impact on the power grid 140 even if reverse power flow occurs, or a negative value that does not have an adverse effect.
By doing the above, even if a reverse power flow occurs, the adverse effects of the reverse power flow can be reduced or eliminated.

Note that at t2, the supervisory control device 110 may perform control to restore the operation of the PCS 108. Therefore, it is desirable that commands from the RPR 124 be sent to the PCS 108 and the supervisory control device 110.

Note that in order to facilitate understanding, in the explanation of FIG. 3, the graph is drawn assuming that the control of FIG. 2 does not exist. Furthermore, in the explanation of FIG. 2, the graph is drawn assuming that the control of FIG. 3 is not provided.
However, in actual operation, it goes without saying that the controls in FIGS. 2 and 3 may be executed in a superimposed manner.

Furthermore, during the period t1 in FIG. 2 and the period t2 in FIG. 3, the output of the PCS 108 is suppressed or stopped, so that there is surplus power in the power that can be output from the PCS 108. In this case, it is desirable that all or part of the power flowing from the solar cell 102 to the PCS 108 via the MPPT 106 be stored in the storage battery 104.

Note that it is desirable that the MPPT 106 operates so that this surplus power is effectively charged into the storage battery. Since the MPPT 106 has the function of maximizing the power generated by the solar cell 102, by increasing the input impedance of the PCS 108 to the AC side, part of the power from the solar cell 102 is directed to the PCS 108. Instead, power is stored by directing the power to the storage battery 104.

As described above, reverse power flow is prevented or the value of reverse power flow is reduced to reduce the negative impact on the power grid 140 as much as possible, and the surplus power generated at this time is effectively used to store electricity in the storage battery 104. It can be used for.

<Embodiment 2>

FIGS. 4A to 4C are diagrams showing the interrelationships among load power, solar power generation power, storage battery charging/discharging power, received power, and the like. In addition, in FIGS. 4A to 4C, it is assumed that the power used for the MPPT 106, PCS 108, supervisory control device 110, power receiving and transforming equipment 120, various sensors 112, etc. is zero, and the power consumption due to the power conversion efficiency of various equipment is assumed to be zero. The explanation will be based on the assumption that the decrease is zero.

For example, it is assumed that the power generated by the solar cell 102 is used for the load 130 or charged into the storage battery 104 without any loss. Further, for example, it is assumed that the power stored in the storage battery 104 is used for the load 130 without loss. Further, for example, the following explanation will be based on the assumption that all of the amount of power that has flowed into the storage battery 104 to be stored in the storage battery 104 is stored, and that all of the stored amount of power can be provided from the storage battery 104 to the load 130. I do.

Although each component of an actual power generation control system is not 100% efficient, the following explanation will help those skilled in the art more easily understand the operation of an actual power generation control system, and Those skilled in the art will be able to easily apply this embodiment to an actual power generation control system based on the knowledge obtained through understanding under this assumption.

FIG. 4A is a graph showing the load power U1 and the generated power S1 of the solar cell 102 in one day. Note that the pattern of the load power U1 and the total amount of power in a day will vary depending on weekends, holidays, days when the user is away due to travel, etc. in the case of a household. In the case of a factory, the pattern of the load power U1 and the total amount of electric power in one day vary depending on the days when the factory is in operation and the days when the factory is not in operation.
This embodiment assumes that the power generation control system 100 suppresses reverse power flow and does not sell electricity. Further, this embodiment assumes a case where power from the power grid 140 is not stored in the storage battery 104. Therefore, it is assumed that the PCS 108 has only a unidirectional inverter that converts alternating current to direct current, or even if it has a bidirectional inverter, there is no power flow from the alternating current side to the direct current side. ing.

As shown in FIG. 1, in the power generation control system 100, when electricity is not sold by reverse power flow, the amount of power generated by the solar cell 102 in a certain period such as one week, one month, or one year is equal to the load power It is desirable not to significantly exceed the amount. This is because if the storage of surplus power tends to increase, even if it is stored in the storage battery 104 and used effectively, the amount of power stored in the storage battery 104 due to surplus power will gradually increase, and the storage battery 104 will not be able to be charged. This is because there is a high possibility that the total amount of electric power will be exceeded, and as a result, there is a high possibility that the amount of generated electric power will not be used because it cannot be charged.

Although it is desirable that the amount of power that can be stored in the storage battery 104 is large, the amount of power that can be stored in the storage battery 104 is determined in consideration of cost and the like. The larger the amount of power that can be stored, the more data can be used to predict the amount of power consumed and the amount of generated power over a longer period of time. For example, if the amount of power that can be stored in the storage battery 104 is half a day's worth of the average load power amount for one day, even if the storage battery 104 is fully charged, the next day will be cloudy and the average amount of power for the day will be If it is half of the typical generated power amount, it is assumed that the amount of power charged in the fully charged storage battery 104 will be used up. For example, if the amount of power that can be charged in the storage battery 104 is equivalent to one week's worth of the average daily load power amount, and the storage battery 104 is fully charged, the next day is cloudy and the average power generation for the day is Even if the storage battery 104 covers half of the amount of power and the insufficient load power, a considerable amount of the stored power remains in the storage battery 104.

The above shows the reason why the larger the amount of power that can be stored in the storage battery 104, the more it is possible to use data for predicting the amount of power consumption and power generation over a long period of time. .

An example of the evaluation value in the power generation control system 100 is to lower the power reception cost. A more specific indicator for lowering the power reception cost is to prevent the maximum amount of power in power reception from exceeding a predetermined value. Regarding the cost of power reception, it is possible to avoid an increase in the contract unit price by ensuring that the maximum power does not exceed a predetermined value in the contract with the power company. For this purpose, it is desirable to control the received power so that its peak does not exceed a predetermined value. Alternatively, another specific indicator for lowering the power reception cost is lowering the average received power. To this end, it is desirable to perform control so that the generated power is used up effectively by preventing the storage battery 104 from becoming fully charged.

In order to perform these controls, for example, it is necessary to prevent peak received power from exceeding a predetermined value, and to maintain the maximum demand power (demand power) purchased from the power grid 140 at a constant level for as long as possible during the day. The evaluation value is to increase the amount of generated electricity (solar power generation), and the various predicted values described above are used as input values, and the various control amounts described above are used as output values, and the AI is made to learn. This allows AI to perform control.
In addition, if the unit price of electricity from the power grid 140 differs depending on the time of day, for example, increase the power from the power grid 140 during the daytime when the power unit price is low, and increase the power from the power grid 140 during the night time when the unit price of power is high. One example of this is to reduce the power and increase the power consumption from the storage battery 104. In this case, Ai may be made to perform learning by using the electricity rate purchased from the power grid 140 as the evaluation value. Alternatively, even if the day and night power unit prices are opposite to the above, AI can perform appropriate control depending on the situation.
Alternatively, an evaluation value that reduces the overall amount of carbon dioxide (CO2) emissions, including power from sunlight and power received from the power grid 140, may be used to cause the AI to perform learning.
Below, an example of controlling the received power for one day will be explained as a specific example.

FIG. 4A shows the load power U1 and the generated power S1 of the solar cell 102 for one day. If the storage battery 104 does not exist, the amount of power U11 and the amount of power U12 cannot be covered by the amount of power generated by the solar cell 102, and therefore will be covered by the amount of received power.
When the storage battery 104 is not present, the generated power amount S12 is power that is not consumed and is discarded. The electric energy S13 is consumed by the load 130.

FIG. 4B is a graph illustrating the relationship between the amount of power generated, the amount of received power, the amount of power stored in the storage battery 104, and the amount of power discharged from the storage battery 104 when the storage battery 104 is used. .
FIG. 4B is a graph in which the various types of power described above are controlled so that the peak received power does not exceed a predetermined value WS.
In FIG. 4B, the amount of power divided by regions is as follows.
S12: Out of the amount of power generated by the solar cell 102, the amount of power stored in the storage battery 104.
S131a: This is the amount of received power consumed by the load 130, and the amount of power generated by the solar cell 102 that becomes surplus due to this received amount of power is stored in the storage battery 104. This power is power that can be provided from the solar cell 102 to the load 130, but is used to charge the storage battery 104 instead of being provided from the solar cell 1042 to the load 130. In this way, by suppressing the provision of part of the electric power from the solar cell 102 to the PCS 108, this suppressed electric power can be used for the power storage 104, so that the electric power stored in the storage battery 104 can be reduced. The amount can be controlled. Note that in S131a, the time period and power can be set by the supervisory control device 110 in any time period during which the solar cell 102 is generating power. By performing such control, even if the PCS 108 has only a unidirectional inverter 109, it is possible to freely supply power from the solar cell 102 to the storage battery 104 by supplying power from the power grid 140 to the load. degree increases.
S132: Out of the amount of power generated by the solar cell 102, the amount of power consumed by the load.
U111a: The amount of received power, which is the amount of power consumed by the load.
U112a: The amount of power consumed by the load 130, which is mainly the amount of power from the storage battery 104 stored on or before the previous day.
U121a: The amount of received power, which is the amount of power consumed by the load 130.
U122a: The amount of power from the storage battery 104 stored on the previous day or on this day, and the amount of power consumed by the load 130.

FIG. 4C is a graph comparing received power when power control is not performed and when power control is performed.

In FIG. 4C, received power 410 is a transition in received power corresponding to the power amount U11 and the power amount U12 in FIG. 4A. The received power 420 is the transition of the received power in FIG. 4B. Power amount U111b, power amount U112b, power amount S131b, power amount 122b, and power amount 121b in FIG. 4C correspond to power amount U111a, power amount U112a, power amount S131a, power amount 122a, and power amount 121a in FIG. 4B, respectively. .

As shown in FIG. 4C, when power control is not performed, the power peak of the received power 410 is W1, which exceeds the predetermined value WS, whereas when power control is performed, It can be seen that the power peak of the received power 420 is W2, which is less than the predetermined value WS.

In order to perform the power control shown in FIG. 4C, it is assumed that at least approximately the amount of power U112a of power is stored in the storage battery 104 before the previous day. Furthermore, on that day, the amount of power stored in the storage battery 104 on the previous day and the previous day and the amount of power S131a on that day are controlled so that at least approximately the amount of power U122a is stored in the storage battery 104. In addition, it is desirable to perform control so that the amount of power corresponding to the amount of power U112a for the next day is stored in the storage battery 104 at least today and is prepared for use on the next day. In order to perform these power controls, information regarding the state of the power generation control system 100 at the current time, a predicted generated power value, a predicted load power value, a storable power amount, etc. are used.

Furthermore, the amount of power stored in the storage battery 104, which is carried over to the next day, may be controlled by controlling the output of the PCS 108 so that the maximum value of received power on the next day is less than a predetermined value WS. By doing so, it is possible to control the received power so that it does not exceed the predetermined value WS even on the next day.

Furthermore, it is desirable that the output of the PCS 108 be controlled so as not to exceed the amount of power that can be charged to the storage battery 104 based on information including predicted data of the amount of power generated by the solar cell 102 and predicted data of power consumption of the load. .

In particular, when the power consumption of the load 130 is larger than the predetermined value WS, the PCS 108 controls the power from the solar cell 102 or the storage battery 104 to prevent the received power from exceeding the predetermined value WS. This is desirable.
For example, if the received power exceeds a predetermined value WS and the unit price of the power contract with the power grid 140 increases, control is performed so that the received power does not exceed the predetermined value WS. It is possible to prevent increases in unit prices. Note that in cases where the power consumption of the load 130 becomes extremely large, it is naturally possible to assume that the received power will exceed the predetermined value WS even if the second embodiment is used. 2, the probability of such an event occurring can be significantly reduced.

Further, when the power consumption of the load 130 is smaller than a predetermined value WS, the PCS 108 may be controlled so that the power from the solar cell 102 is stored in the storage battery 104.

In addition, it is desirable that the above-mentioned various kinds of prediction data include at least one day's worth of prediction data. Further, the above-mentioned various kinds of prediction data may be updated and provided multiple times in one day, or the power generation control system 100 may predict it by itself.

FIG. 5 is a diagram showing each hardware configuration that mainly executes processes related to various data collection, control commands, and AI processing in the embodiment. Needless to say, in addition to the hardware shown in FIG. 5, there is also hardware shown in FIG. 1 that performs various types of power control. The hardware configuration shown in FIG. 5 shows the configuration of a device including the supervisory control device 110 shown in FIG. 1 and/or a computer in a device (not shown) externally connected to the supervisory control device 110.

The hardware configuration controls a CPU 501, a ROM 502 and a RAM 503 in which the program and data of this embodiment may be stored, a network interface 505, an input interface 506, a display interface 507, and a storage medium 518 in which the program and data of this embodiment may be stored. It has an external memory interface 508 and an output interface 509. These hardwares are interconnected by a bus 504.

Further, the AI 521 that performs learning and outputs learning results may be connected to the network 512. Note that the AI 521 may be configured by independent hardware connected to the network 515, for example, or may be realized by a program executed by the CPU 501. Therefore, as for the processing of the AI 521, it goes without saying that the implementation form and the connection form with other hardware are not limited to this example. Learning of AI521 may be supervised learning or unsupervised learning.

Network interface 505 is connected to network 515. The network 515 includes a wired LAN, a wireless LAN, the Internet, a telephone network, and the like. An input section 516 is connected to the input interface 506. Signals from various sensors may be connected to the input section 516. A display unit 517 is connected to the display interface 507. A storage medium 518 is connected to the external memory interface 508. Storage medium 518 may be RAM, ROM, CD-ROM, DVD-ROM, hard disk, memory card, or the like. The storage medium 518 may store a program that implements this embodiment. An output unit 519 is connected to the output interface 509, and outputs control command signals and the like to various types of hardware.

A program implementing at least a portion of the embodiments described above may be executed by the hardware shown in FIG. Further, the program of the embodiment may be implemented as a method for causing a computer to execute the program. Part or all of the program of this embodiment may be executed by an operating system. Further, part of the program may be realized by hardware. The program may be stored in storage medium 518, ROM 502, or RAM 503.

Some programs of the embodiments may be implemented as a hardware device, such as the supervisory control device 110 in FIG. 1 .
It goes without saying that the above embodiments are not intended to limit the invention described in the claims, but are to be treated as illustrative.
It goes without saying that each of the embodiments described above is an illustration of the invention described in the claims, and is not intended to limit the invention.

100 Power generation control system 102 Solar cell 104 Storage battery 109 Inverter 110 Monitoring control device 112 Various sensors 120 Power receiving and transforming equipment 122 UPR (undervoltage relay)
124 RPR (Reverse Power Relay)
130 Load 140 Power grid

Claims (8)

a solar cell that outputs power via a maximum power tracking device;
a storage battery connected to the maximum power tracking device and capable of charging the power of the solar cell;
A power receiving and transforming section connected to the power grid and loads,
a power conditioner having a unidirectional inverter that outputs DC power from the maximum power tracking device and the storage battery to an AC side including the power receiving and transforming section;
a monitoring control device that controls the output of the power conditioner;
has
The supervisory control device includes:
If the power difference obtained by subtracting the power from the maximum power tracking device by the power flowing into the power conditioner is positive, the power difference can be used to charge the storage battery, or When the differential power is negative, the storage battery is discharged, and the differential power is output from the power conditioner to the power receiving and transforming unit so that the differential power can be given from the storage battery to the power conditioner. control power,
Power generation control system. The supervisory control device includes:
Even if the power conditioner is capable of providing power to a load with the power from the maximum power follower, the power conditioner receives part of the power from the maximum power follower. and supplying the load with the power obtained from the power grid so as to supplement the reduced power that can be provided from the power conditioner to the load due to the suppressed power. , controlling the power output from the power conditioner to the power receiving and transforming unit so that the suppressed part of the power is used for charging the storage battery;
The power generation control system according to claim 1. The supervisory control device includes:
Based on information including predicted power generation data of the solar cell and predicted power consumption data of the load, the power condition is adjusted so that the maximum value of received power in a day from the power grid does not exceed a predetermined value. controlling the power output from the na to the power receiving and transforming section;
The power generation control system according to claim 1. The supervisory control device includes:
The output of the power conditioner is adjusted so that the maximum value of received power from the power grid on the next day is reduced based on information including predicted data on the amount of power generated by the solar cell and predicted power consumption on the load on the next day. by controlling the amount of electricity stored in the storage battery that is carried over to the next day;
The power generation control system according to claim 1. The supervisory control device includes:
controlling the output of the power conditioner so as not to exceed the total amount of power that can be charged to the storage battery, based on information including predicted power generation data of the solar cell and power consumption predicted data of the load;
The power generation control system according to claim 1. The supervisory control device includes:
When the power consumption of the load is larger than a predetermined value, the output of the power conditioner is controlled so that the received power does not exceed the predetermined value.
The power generation control system according to claim 1. The supervisory control device includes:
When the power consumption of the load is smaller than a predetermined value, suppressing the output of the power conditioner so that the power from the maximum power tracking device can be used to charge the storage battery.
The power generation control system according to claim 1. The supervisory control device includes:
The power generation amount prediction data of the solar cell and the power consumption prediction data of the load are received multiple times during one day, and the power generation amount prediction data of the solar cell and the power consumption prediction data of the load are received for at least one day. Contains information on
The power generation control system according to any one of claims 1 to 7.

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