JP7523052B2 - Power generation control system and power generation control method - Google Patents

Description

The present invention relates to a power generation control program and a power generation control system that executes the program.

Conventionally, for example, in a photovoltaic power generation system, surplus power among generated power is reverse-flowed to a commercial power line based on a purchase contract with a power company. However, with an increase in distributed power sources such as photovoltaic power generation, a drawback of voltage fluctuation in the power system due to reverse flow may occur, and it has become necessary to control the amount of power generated by the solar cell. For example, Patent Documents 1 to 3 disclose a method of controlling the amount of power generated by the solar cell using a power conditioner (a power generation control device called PCS).
Generally, in small-scale power generation systems, a single power generation control device controls the power generation amount of the power generation device, but in medium-scale or larger power generation systems, it is common to adopt a power generation control system in which multiple power generation devices are controlled by multiple power generation control devices.

JP 2017-093127 A JP 2012-175858 A Patent No. 6364567

The requirements for a power generation control system are to obtain as much power generation as possible while controlling the amount of power generation so that reverse power flow can be avoided under any circumstances. However, one of the factors that makes it difficult to control the amount of power generation is a sudden fluctuation in power consumption. In particular, when the amount of power generation and the amount of power consumption are balanced, a sudden decrease in power consumption alone generates surplus power, which can lead to reverse power flow. In power generation systems that have storage batteries, the surplus power may be absorbed by charging the battery, but once the storage battery is fully charged, a sudden decrease in power consumption thereafter can cause reverse power flow.

The second problem is that the accuracy of predicting power consumption is not very high. Power consumption can fluctuate suddenly on a second-by-second basis, so if it were possible to predict power consumption a few seconds ahead with high accuracy based on past changes in power consumption, it would be possible to accurately control the amount of power generated even if power consumption suddenly changes. However, the reality is that even if we try to carry out this kind of "predictive control," the accuracy is not very high at present.

One of the causes of this is thought to be the "sampling interval" in the power generation control system. In other words, in conventional general power generation control systems, various data required for control (for example, the generated power of each power generation device, the power consumption of the load) is constantly acquired at a specified interval (sampling interval) in order to be monitored. In systems that perform predictive control, this also includes data that affects the amount of power generated, such as weather data. Conventionally, the sampling interval for acquiring all of this data was usually set at a fixed, uniform interval. In Japan, due to historical reasons, a system that samples every six seconds is widely used as the de facto standard.

In relatively large-scale power generation control systems, the generated power rarely fluctuates suddenly on a second-by-second basis due to reasons other than a malfunction, but more detailed control is required to keep up with the ever-changing power consumption of the load to which the power is supplied.

However, simply shortening the sampling interval does not allow the amount of power generation to be controlled in response to sudden changes in power consumption. The reason for this is that even if a command to control the amount of power generation is sent to the power generation control device, there is a "time lag" before the desired amount of power generation is achieved, making it impossible to follow sudden changes in the amount of power generation. This time lag becomes larger the larger the power generation system.

For example, consider a power generation system in which 10 solar power generation devices are operated by 10 power generation control systems, which was operating at 70% power generation, but then an increase in power consumption makes it necessary to increase power generation to 80%. In this case, a control command value is sent to each of the 10 power generation control devices to increase power generation to 80%. However, immediately after that, power consumption drops suddenly, making it necessary to reduce power generation to 40%. Since there is a time lag before the initial control command value increases power generation to 80%, the system is unable to keep up with the sudden drop in power consumption, resulting in a situation in which reverse power flow may occur.

The larger the power generation system, the more power generation control devices there are, the greater the time lag, and the more serious the impact of this problem. This problem is not limited to solar power generation, but is also the same in other power generation systems such as wind power generation, and especially in distributed power generation systems in which multiple power generation devices are controlled by multiple power generation control devices.

There are two types of power generation control: control (first control) that reduces the amount of power generation with the aim of "avoiding reverse power flow," and control (second control) that increases the amount of power generation by the power generation equipment in order to reduce the amount of power generation that must be purchased from the power company. The first control is essential for avoiding reverse power flow, and if this control is lost, the emergency device will be activated and power generation will stop. On the other hand, the second control is "more preferable," and even if the increase in power generation is delayed due to a time lag, it will only result in a loss of an opportunity to utilize the performance of the power generation equipment, and will not lead to a serious situation such as a stop in power generation. Therefore, of the two types of control, the first control is the one that should be emphasized.

In view of the above problems, the present invention aims to provide a control program for efficiently controlling the power supplied to a load in response to time-varying power consumption in a power generation control system equipped with multiple power generation devices and multiple power generation control devices, and a power generation control system for executing the control program.

The "time lag" between sending a power generation control command value and reaching the specified power generation amount increases as the number of power generation control devices (PCS) increases, resulting in slower response. Therefore, in the "first control" that reduces the power generation amount, the time lag can be reduced by reducing the number of power generation control devices that send control command values.

The power generation control program according to the present invention comprises:
A power generation control program that transmits a control command value, which is an upper limit value of a power generation amount, to a plurality of power generation control devices,
a power generation acquiring step of acquiring an output power from the power generation control device;
A power consumption acquisition step of acquiring a power consumption value ,
During normal operation, a command transmission step is performed at predetermined intervals to selectively transmit control command values to only some of the power generation control devices in response to fluctuations in a difference between a total power generation value obtained by adding up the output powers and the power consumption value .
When the power consumption is reduced , the control command value is selectively and urgently transmitted .

By configuring in this way, the number of power generation control devices that are the subject of power generation control can be reduced, which reduces the time lag between receiving a control command value and reaching the specified power generation amount, making it possible to quickly control the power generation amount in line with the power consumption.

It is assumed that this power generation control program will be used in a self-consumption power generation control system that requires the avoidance of reverse power flow, and it is particularly important that the interval at which the "power consumption acquisition step" is executed is "an interval that is short enough to enable rapid control of power generation in response to fluctuations in power consumption." On the other hand, generated power changes more slowly than power consumption and rarely fluctuates suddenly in a short period of time, such as on the order of seconds. Furthermore, even if the acquisition of this data is delayed, this will not result in serious consequences such as the occurrence of reverse power flow, so the interval at which power generation is acquired and the interval at which other data, such as weather data, are acquired can remain the same as before. As a result, it was decided to adopt a time interval that can rapidly track changes in power consumption as the "interval for acquiring power consumption that is the basis for power generation control."

The above configuration is the basic configuration of the control algorithm when the above-mentioned "first control" is performed, but a control algorithm for performing the "second control" may be prepared separately. The decision as to whether to perform the first control or the second control is preferably made "in accordance with the fluctuation of the difference between the upper limit of the total power generation and the power consumption value." However, even with only the first control, the controllability of the power generation amount is improved by the first control, which means that the system can be operated at the maximum possible output when the control is not working, and as a result, it is considered that the power generation efficiency of the entire system can be improved even without performing the second control.

In the above configuration, the control command value does not necessarily have to be the same value for each of the power generation control devices to which it is sent. "Not necessarily the same value for each of the destinations" includes both cases where some values are the same and others are different, and cases where all values are different.

For example, in a case where there are four power generation control devices (A, B, C, D), as a result of applying the algorithm of the above configuration, only A and B are selected as the control targets. At this time, the power generation power of C and D that were not selected will not change due to the transmission of the control command value, but rather than transmitting the same control command value uniformly to A and B that are the control targets (for example, when the current output of A is 70% and the current output of B is 40%, the output of both A and B is uniformly reduced to 45%), different control command values (for example, the output of A is reduced to 60% while the output of B is set to 30%) may be transmitted. This is because it is expected that the tracking ability will be improved if a value close to the current power generation amount is transmitted to each power generation control device. Alternatively, an algorithm may be considered in which the output of A is set to 0% to stop the output, and only B is the transmission target of the control command value until the control is relaxed from the following cycle .

Conversely, in the above basic configuration, the control command value may be the same for all destinations. The advantage of using the same value is that if the controllability (response characteristics) is sufficiently improved by limiting the number of operating power generation control devices (PCSs) to be controlled, the controllability can be sufficiently improved by controlling with the same value.

When the above-mentioned configuration of "not necessarily the same value for each destination" is adopted, the command transmission step may be configured to select one or more power generation control devices that have the power generation command value set to the maximum output value and one power generation control device that has the power generation command value set to a value less than the maximum output, and to set the power generation command value for the non-selected power generation control devices to zero.

When the above-mentioned "same value for each destination" configuration is adopted, the selection step may be configured to set the power generation command value for one or more power generation control devices to zero, and set the power generation command values for all other power generation control devices to the same value greater than 0 and less than 100%.

Furthermore, the predetermined interval ( sampling interval ) in any of the above configurations may be, for example, six seconds, which is the de facto standard value in Japan as described above, and since there are few sudden changes in data other than power consumption, there is no particular need to change it.

In any of the above configurations, the emergency may be a time period of one second or less after it is detected that the power consumption has decreased . The lower limit value is a minimum value at which the controllability of the power generation control device can be maintained, and is naturally a value greater than zero.
As described above, in order to improve the controllability of the power generation control device, it is important to set at least the "interval for acquiring power consumption that is the basis for power generation control" (power consumption sampling interval) to a time interval that can quickly track changes in power consumption (in short, shorter than before), but the sampling interval for acquiring various data other than power consumption may be the same as before (longer than the interval for acquiring power consumption), or all intervals may be uniformly set to the same interval as the interval for acquiring power consumption. For example, it is possible to set all sampling intervals to 1 second. This is because the controllability of the power generation control device is improved by adopting the configuration of the present invention.

In any of the above configurations, the power consumption may be a predicted value predicted based on past time trends instead of a current measured value. Although predicting power consumption is relatively difficult, various improvements have improved the accuracy, and it can be combined with the power generation control program of the present invention.

The power generation control system of the present invention comprises a plurality of power generation devices, a power generation control device that controls the power generated by the power generation devices, and a measurement control terminal, and the measurement control terminal executes any one of the power generation control programs described above and controls the output power from the power generation control device.

The present invention improves the controllability of the power generation control system, making it possible to efficiently control the power supplied to the load in response to power consumption that varies over time.

FIG. 2 is a diagram showing the main configuration of a power generation control system. FIG. 2 is a diagram showing the main configuration of a measurement control terminal that controls the power generation control system. 1 is a graph showing changes in power consumption over time. FIG. 4 is a diagram showing the output power control status of a plurality of power generation control devices. FIG. 4 is a diagram showing the main flow of a power generation control program. FIG. 1 is a diagram showing a control flow of a self-consumption power generation control system that combines predictive control.

The following describes the embodiments with reference to the drawings. However, none of the following embodiments should be interpreted in a restrictive manner in determining the gist of the present invention. In addition, the same reference symbols are used for identical or similar components, and descriptions may be omitted.

(First embodiment)
The following description will be given taking as an example a power generation control system 100 that uses a solar cell as a power generation device.
FIG. 1 shows the main configuration of an embodiment of a power generation control system 100 .
The present invention can be similarly applied to other power generation devices such as wind power generation devices.

The power generation control system 100 includes a plurality of power generation devices 1 (1a, 1b, 1c) (e.g., solar cells, etc.) and a plurality of power generation control devices 2 (2a, 2b, 2c) (e.g., power conditioners ) that correspond to each of the power generation devices 1 (1a, 1b, 1c) and control the amount of power generated by the power generation devices 1 (1a, 1b, 1c).
The power generation control devices 2a, 2b, and 2c can control the amounts of power generated by the power generation devices 1a, 1b, and 1c.
For example, when controlling the amount of power generated by a solar cell as the power generation device 1, a power conditioner as the power generation control device 2 can control the output power by applying the MPPT method or the like in accordance with the IV characteristics.
Furthermore, when the output of the power generation device 1 is DC power, the power generation control device 2 can convert it to AC power.
The power receiving and transforming unit 3 receives power from the power generation control devices 2a, 2b, 2c via a power line L2 and power lines Lb2a, Lb2b, Lb2c branching off from it, and also receives power from a commercial power source 4 such as a power company via a power line L4, and supplies power to loads 5a, 5b, 5c via a power line L5.

The measurement control terminal 6 acquires the output power from the power generation control device 2, the power supplied from the commercial power source 4 and the power consumption of the load 5 (5a, 5b, 5c), the power supplied from the commercial power source 4, and the output power from each power generation control device 2 (2a, 2b, 2c).
The power consumption can be calculated as described below, but may also be measured directly using power meters 7 and 9 provided on the power lines L4 and L5, respectively, as shown in FIG.

The measurement control terminal 6 includes a measurement input/output unit 61 for communicating with the power generation control device 2 (and the power meters 7, 9), a calculation unit 62, a storage unit 63, and a control input/output unit 64 for communicating with the power generation control device 2 (FIG. 2).
The measurement control terminal 6 may acquire weather data. For example, a sunshine meter, a thermometer, and a hygrometer may be separately installed in the power generation device 1 or the power generation control device 2, and data from these instruments may be acquired via the measurement input/output unit 61.

The sum of the power supplied from the commercial power source 4 (system) and the total output power from the power generation control devices 2a, 2b, and 2c is equal to the power consumption of the loads 5a, 5b, and 5c.
Therefore, the power consumption can be calculated from the power supplied from the commercial power source 4 (system) (hereinafter referred to as commercial power) and the total output power from the power generation control devices 2a, 2b, 2c (hereinafter referred to as total generated power). However, in order to accurately measure the power consumption, which is particularly prone to fluctuations, the power consumption may also be measured directly using a power meter 9.

In order to avoid reverse power flow, a reverse power relay (RPR) 10 may be installed on the power line L2.

In order to avoid reverse power flow without disconnecting the reverse power relay 10, it is necessary to determine an upper limit value of the total power generation (hereinafter sometimes referred to as the total power generation upper limit value) by a known method (e.g., the methods disclosed in Patent Documents 1 to 3) so that the total power generation does not exceed the power consumption, and the power generation control device 2 needs to control the power generation device 1 so that the total power generation is below the total power generation upper limit value.
That is, when the difference between the total power generation and the power consumption decreases, the risk of reverse power flow increases, so the total power generation upper limit is decreased. On the other hand, when the difference between the total power generation and the power consumption increases, the risk of reverse power flow decreases, so the total power generation upper limit is increased.
Therefore, the measurement control terminal 6 acquires the power consumption, sets a total power generation upper limit value for the total power generation based on the power consumption in the calculation unit 62, and controls each power generation control device 2 based on the total power generation upper limit value.

The measurement control terminal 6 transmits control command values (hereinafter sometimes referred to as individual command values) that specify the upper limit of each output power (hereinafter sometimes referred to as individual upper limit values) to each power generation control device 2a, 2b, 2c via the control input/output unit 64 so that the total power generation is equal to or less than the total power generation upper limit value.

Each of the power generation control devices 2a, 2b, and 2c performs control, for example, by the MPPT method or the like, so as to output the maximum generated power within a range equal to or less than the individual upper limit value specified based on the individual command value. Each of the power generation control devices 2a, 2b, and 2c has a finite response speed, and requires a finite time (hereinafter referred to as response time) from when the individual upper limit value of the output power is specified until the maximum generated power is output within the individual upper limit value.
Each of the power generation control devices 2a, 2b, and 2c can reliably output its maximum power by controlling at intervals (cycles) longer than the intervals (cycles) determined by the response time.

If the PCS is allowed to set a new command value while searching for the maximum power generation value using the MPPT method or the like, i.e., at a period shorter than the response time, the PCS may be configured to control the output value again based on the new command value, or the PCS may be configured not to accept changes to the command value while searching using the MPPT method.

The control capabilities of the power generation control devices 2a, 2b, 2c are not necessarily the same, but depend on, for example, the manufacturer, the conditions of use, the number of years of use, and the like.
When the plurality of power generation control devices 2a, 2b, and 2c are controlled uniformly, the maximum response time of each of the power generation control devices 2a, 2b, and 2c can be set as the command interval (cycle).

On the other hand, power consumption changes from moment to moment, and fluctuates faster than the command interval. Therefore, the measurement control terminal 6 can independently set the sampling interval (period) (hereinafter sometimes referred to as the detection interval) for acquiring power consumption and the command interval (or the transmission interval of command values) for controlling each power generation control device 2, and sets the detection interval for acquiring power consumption shorter than the command interval. For example, it is set to 1/n of the minimum response time Tmin of each power generation control device 2a, 2b, 2c. Here, n is a natural number greater than or equal to 2.

The measurement control terminal 6 can acquire n pieces of measurement data of power consumption during a command interval.
Therefore, the measurement data acquired via the measurement input/output unit 61 is stored in the storage unit 63, and the calculation unit 62 can predict the upcoming power consumption from the measurement data of a plurality of power consumptions. For example, it is also possible to predict the power consumption after the response time has elapsed.
In addition, when n=2, the prediction is based on a linear function and is therefore limited to a monotonous increase or decrease. Therefore, more preferably, n can be a natural number of 3 or more.

In this way, the measurement control terminal 6 can set the power consumption detection interval and the command interval for controlling the power generation control device 2 independently, and can set the power consumption detection interval to a short value. For example, the command interval can be set to 6 seconds and the detection interval to 1 second. As a result, the measurement control terminal 6 can quickly detect fluctuations in power consumption and perform rapid power generation control, enabling precise control.

The measurement control terminal 6 uniformly transmits a command value (hereinafter referred to as an individual command value) specifying the upper limit value of power generation (hereinafter referred to as an individual upper limit value) to each of all the power generation control devices 2a, 2b, 2c.
For example, an individual command value equal to the upper limit of the total power generation determined based on the power consumption can be transmitted to each of the power generation control devices 2a, 2b, and 2c. That is, the power generation amount is equally allocated to each of the power generation control devices 2a, 2b, and 2c. For example, if the total number of the power generation control devices 2a, 2b, and 2c is Nc, [upper limit of the total power generation]/Nc can be specified as the individual upper limit for each of the power generation control devices 2a, 2b, and 2c.

Furthermore, when the rated power of each of the power generation control devices 2a, 2b, 2c is different, individual upper limit values proportional to the rated power may be specified.
The rated power of the power generation control device 2i may be PRi, and the individual upper limit value may be [individual upper limit value]=[upper limit value of total generated power]PRi/SPR.
Here, SPR is the sum of the rated powers of all the power generation control devices 2 (ΣPRi).
That is, the equal distribution is corrected to distribute the power generation amounts to each of the power generation control devices 2a, 2b, and 2c.

In either case, it goes without saying that in order to ensure stable operation of the power generation control device 2, the generated power output will not exceed the rated power of the power generation control device 2.

A control method for controlling the amount of power generation more efficiently will be described below.
The power generation output from each of the power generation control devices 2a, 2b, and 2c varies from moment to moment because it depends on the installation conditions of the power generation devices 1a, 1b, and 1c, the surrounding environment, and time. Therefore, individual upper limit values are set according to the actual power generation conditions.

In order to control the amount of power generation while avoiding reverse power flow and adjusting to fluctuations in power consumption, control is performed according to the fluctuation trends in power consumption, i.e., downward and upward trends.

Case 1: Strengthening control of total power generation (reducing the upper limit of total power generation)
When power consumption decreases, in order to avoid reverse power flow, it is necessary to reduce the total generated power in response to the decrease in power consumption.
In addition, when the power consumption decreases as shown in region B of Fig. 3, the power consumption has a negative gradient with respect to time. In addition, the determination of whether or not the case 1 applies is made only based on whether or not the power consumption has decreased, and the control value is not affected even if the amount of power generation decreases at the same time.
Case 2: Relaxing the control of total power generation (increasing the upper limit of total power generation)
Increasing power consumption makes it possible to increase the total power generation, thereby increasing the proportion of self-power consumption.
When the power consumption increases as shown in region A of FIG. 3, the power consumption has a positive gradient with respect to time.

In general, the higher the output power of the power generation device 1 is and the closer it is to the rated power, the higher the conversion efficiency (ratio of output power/input power) of the power generation control device 2 is.
Therefore, when there are a plurality of power generation control devices 2, the power generation control device 2 with the largest output power is selected, and control is performed to bring the total generated power closer to the upper limit value.
Furthermore, the fewer the number of power generation control devices 2 to be controlled, the fewer the number of times control is performed by the measurement control terminal 6. This improves the controllability of the entire power generation control system 100 including a plurality of power generation control devices 2.

In case 1, the risk of reverse power flow occurring increases because power consumption decreases. Therefore, it becomes necessary to quickly control, that is, reduce, the generated power.
In particular, when the fluctuation in power consumption changes from increasing to decreasing (for example, P1 in Figure 3) or when the absolute value of the amount of decrease in power consumption increases (for example, P2 in Figure 3), the rapidity of control can be improved by sending a command value to the power generation control device 2 selected at the time the change is detected, regardless of the command interval.
The power consumption detection interval is shorter than the command interval, allowing for rapid response.

In addition, when a decrease in power consumption is detected, the power generation control device 2 is selected in order of the power generation power, thereby limiting the number of power generation control devices 2 to be controlled and improving response performance.
The procedure for selecting the power generation control device 2 will be described in detail below with a specific example.

As shown in FIG. ₄ , at time t0, the upper limit of the total generated power is 80 kW, and the power outputs of all four power generation control devices 2 (PCS1, PCS2, PCS3, and PCS4 in FIG. 4) are 20 kW.

When the upper limit of the total power generation is reduced from 80 kW to 35 kW from time t0 _to time _t1 , the measurement control terminal 6 instructs the power conditioners PCS1 to 4 to output a maximum output power of 0 kW for PCS1, 0 kW for PCS2, 20 kW for PCS3, and 15 kW for PCS4 .
As a result, PCS1 and PCS2 essentially stop issuing commands at time t1 , and the number of power generation control devices 2 that actually control the output power is reduced to two, PCS3 and PCS4 , improving responsiveness.
In the above case, any of the power generation control devices 2, PCS1, PCS2, PCS3, and PCS4, may be selected, but the power generation control device 2 with the smallest cumulative power generation amount in the past can be selected. Therefore, the measurement control terminal 6 stores the cumulative power generation amounts of all the power generation control devices 2 in the storage unit 63. The measurement control terminal 6 can select a specific power generation control device 2 by referring to the stored cumulative power generation amount.

The power generation control device 2 has a finite response time, but sending command values to the power generation control device 2 at intervals (periods) shorter than the response time may mean that the power generation control device 2 is unable to output maximum power. However, if power consumption decreases, the risk of reverse power flow increases, so the control method of the measurement control terminal 6 is a control method that prioritizes avoiding reverse power flow.

When the upper limit value of the total power generation is reduced to 25 kW from time t1 _to time _t2 , the measurement control terminal 6 selects the PCS 4, which is one of the power generation control devices 2 that outputs the maximum power output value of 15 kW.

When the upper limit value of the total power generation is reduced to 10 kW from time t2 _to time _t3 , PCS4 exceeds the total power generation of 10 kW, so the command value is set to 0 kW. Since the output power of PCS3, which is the remaining power generation control device 2, is 10 kW, PCS3 is selected. If the output power of PCS3 is less than 10 kW, the measurement control terminal 6 commands the power generation control device 2 selected from the power generation control devices 2 other than PCS3 to output the discrepancy amount (the difference between 10 kW and the output power of PCS3).

When the upper limit of the total power generation increases to 25 kW from time t3 _to time _t4 , the PCS 3 that is outputting power at that time has a deviation from the upper limit of the total power generation, so that the output power of the PCS 3 that is outputting power at that time is equally distributed to the remaining power generation control devices 2 whose output is controlled to 0 kW. In other words, the remaining power generation control devices 2 are commanded to the same individual upper limit value.
At this time, the interval at which the measurement control terminal 6 issues commands to the power generation control device 2 is set to a value equal to or greater than the response time of the power generation control device 2, and preferably equal to the response time. This makes it possible to slow down the increase in the total power generation amount.
Furthermore, if there is a power generation control device 2 whose power generation cannot reach the individual upper limit value (5 kW in Figure 4) set due to weather conditions or other reasons, that is, if it is found that the maximum output (for example, 3 kW) of that power generation control device 2 is less than the individual upper limit value (3 kW < 5 kW), the individual upper limit value of that power generation control device 2 (for example, PCS1) is reset to its maximum output (individual upper limit value = 3 kW), and the difference between the output power of PCS3 and PCS1 and the upper limit value of the total power generation (25 kW - (10 kW + 3 kW) = 12 kW) is evenly distributed to the other power generation control devices 2 (two PCSs, PCS2 and PCS4) to obtain the value (12 kW/2 = 6 kW) as the individual upper limit value (6 kW) of the other power generation control devices 2 (PCS2, PCS4).

In this way, when power consumption increases and the upper limit of the total power generation can be increased, the interval at which the measurement control terminal 6 issues commands to the power generation control device 2 is equal to or greater than the response time of the power generation control device 2, so the monitoring device 6 monitors and determines whether the power output by each power generation control device 2 can actually reach its individual upper limit, and then modifies the individual upper limit of each power generation control device 2 to control the output power.

In addition, by equally allocating output power to all power generation control devices 2 that were not output controlled, it is possible to verify whether each power generation control device 2 can actually output the specified individual upper limit value of power. Because the power output capacity of multiple power generation control devices 2 changes due to environmental changes, it is also possible to search for a power generation control device 2 that can output high power.

As described above, by controlling the amount of power generated by the power generation control system 100, it is possible to improve the overall power generation efficiency of the power generation control system 100 while avoiding reverse power flow.

FIG. 5 shows the flow of the power generation control program for the power generation control system 100.
This program is stored in the memory unit 63 of the measurement control terminal 6, and is read and executed by the calculation unit 62.

S1: First Step This step includes a power generation power acquisition step of acquiring the output power from each power generation control device 2, and a power consumption acquisition step of acquiring the value of power consumption.
The output power (power generation) from each power generation control device 2 is output to the measurement control terminal 6. Furthermore, the power consumption is calculated as the sum of the total generated power and commercial power, or, if a power meter 7 or a power meter 9 is provided, is obtained directly.

The power consumption acquisition step is executed at intervals of, for example, 1 second. The generated power acquisition step may be executed at the same intervals as the power consumption acquisition step, but can be executed at intervals of, for example, 6 seconds to match the response speed of the power generation control device 2. In the latter case, the output power from the power generation control device 2 is determined, and the maximum output power from the power generation device 1 within the control range of the power generation control device 2 can be acquired. When comparing the generated power and power consumption, it is not necessary to use the generated power acquired at the same time. If the acquisition cycles for the generated power and power consumption are different, it is sufficient to use the most recently acquired values for each.

S2: Second step An upper limit value (total power generation upper limit value) for the total power generation, which is the sum of the output power of all the power generation control devices 2, is calculated from the acquired power consumption.

S3: Third step The output power from each power generation control device 2 is summed to calculate the total generated power (actual measured value), and the total generated power is compared with the total power generation upper limit value (calculated value).
(1) If the total power generation = the total power generation upper limit, go to step 1. (2) If the total power generation < the total power generation upper limit, increase the number of power generation control devices and change the individual upper limits, then go to step 1. (3) If the total power generation > the total power generation upper limit, select a power generation control device (reduce the number of devices), change the individual upper limits, then go to step 1.

By executing the above steps, the measurement control terminal 6 is able to control power generation in the power generation control system 100.

In the second step, in order to calculate the total power generation upper limit value, a predicted value of power consumption after the command interval has elapsed or at the time when the next control command value is transmitted may be calculated taking into consideration the response time of the power generation control device 2. When predicting power consumption, data on power consumption at several points is required.
Since power consumption does not increase or decrease monotonically but fluctuates, a regression curve for predicting power consumption needs to have a function with at least a second degree for power consumption, and therefore three or more past power consumption values are required.
The detection interval of the power consumption is preferably 1/n of the command interval of the power generation control device 2, where n is an integer of 3 or more.

(Example)
6 is a diagram showing a control flow of a self-consumption type power generation control system combined with predictive control. In this flow, values of power consumption and power generation one second later predicted by a quadratic function are used.

Control is started in step Sb1. Power consumption is measured in step Sb2. A predicted value of power consumption one second later is calculated in step Sb3, and the possible power generation is calculated based on this predicted value. In prediction step Sb4, it is determined whether it is necessary to reduce the amount of power generation, i.e., to "strengthen control." If the possible power generation one second later exceeds the predicted power consumption one second later, surplus power will be generated and reverse power flow may occur. In such a case, it is determined that "strengthen control" is necessary. Note that, for example, if a storage battery is connected and the surplus power can be allocated to charging the storage battery, the conditions under which reverse power flow may occur will be different, but in such a case, an additional algorithm is used to calculate the possible power generation.

If it is determined in step Sb4 that "control should be strengthened," a list of "emergency control messages with a limited number of PCSs to be transmitted" is generated in step Sb5. Next, the control value for each PCS is recalculated in step Sb6. Next, one emergency control message is transmitted in step Sb7. In step Sb8, it is determined whether transmission of all emergency control messages has been completed. If not, step Sb7 is executed again. If completed, step Sb2 is executed again.

If it is determined in step Sb4 that "there is no need to strengthen the control," the 6-second interval is maintained and step Sb9 is executed. In step Sb9, it is determined whether the 6-second value is a confirmed timing control. If the answer is Yes, step Sb10 is executed and the control value for each PCS is recalculated. If the answer is No, step Sb11 is executed and one measurement/control message is sent.

Control using "prediction" as shown in this embodiment is not essential, but since the interval is shorter than before, it is expected that the prediction accuracy will improve. Therefore, by combining this invention with control using prediction, it is expected that the controllability of the power generation control system will be further improved.

The present invention improves the controllability of the power generation control system, making it possible to efficiently control the power supplied to the load in response to the power consumption that varies over time. It is possible to improve the power generation efficiency of a power generation system equipped with multiple power generation control devices while also avoiding reverse power flow, and has great industrial applicability.

100 Power generation control system 1, 1a, 1b, 1c Power generation device 2, 2a, 2b, 2c Power generation control device L2, L4, Lb2a, Lb2b, Lb2c, L5 Power line 3 Substation unit 4 Commercial power source 5, 5a, 5b, 5c Load 6 Measurement control terminal 7, 9 Power meter (optional)
10 Reverse Power Relay (RPR)
61: Measurement input/output unit 62: Calculation unit 63: Storage unit 64: Control input/output unit

Claims (7)

A power generation control program that transmits a control command value, which is an upper limit value of a power generation amount, to a plurality of power generation control devices,
a power generation acquiring step of acquiring an output power from the power generation control device;
A power consumption acquisition step of acquiring a power consumption value,
During normal operation, a command transmission step is performed at predetermined intervals to selectively transmit control command values to only some of the power generation control devices in response to fluctuations in a difference between a total power generation value obtained by adding up the output powers and the power consumption value .
A power generation control program, comprising: a power generation control unit that selectively and urgently transmits the control command value when the power consumption is reduced. The power generation control program according to claim 1, characterized in that the control command value is not necessarily the same value for each of the power generation control devices to which it is sent. The power generation control program according to claim 1, characterized in that the control command value is the same for all destinations. The power generation control program according to any one of claims 1 to 3, characterized in that the predetermined interval is 6 seconds. The power generation control program according to any one of claims 1 to 4, characterized in that the emergency is a time period of 1 second or less after detecting a decrease in the power consumption. The power generation control program according to any one of claims 1 to 5, characterized in that the power consumption is a predicted value based on past temporal changes instead of a current measured value. The power generation system includes a plurality of power generation devices, a power generation control device that controls the power generated by the power generation devices, and a measurement control terminal,
7. A power generation control system, comprising: said measurement control terminal executing said power generation control program according to claim 1, and controlling an output power from said power generation control device.

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