JP7801720B2 - 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.

In the past, for example, in a solar power generation system, surplus power generated was reverse-flowed to commercial power lines based on a sales contract with an electric power company. However, with the increase in distributed power sources such as solar power generation, reverse-flow can cause adverse effects such as voltage fluctuations in the power grid, and it has become necessary to control the amount of power generated by solar cells. For example, Patent Documents 1 to 3 disclose methods for controlling the amount of power generated by solar cells using a power conditioner (a power generation control device called a 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.

Japanese Patent Application Laid-Open No. 2017-093127 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 sudden fluctuations in power consumption. In particular, if power generation and power consumption are balanced and there is a sudden decrease in power consumption alone, surplus power is generated, which can lead to reverse power flow. In power generation systems that include storage batteries, surplus power may be absorbed by charging the battery, but once the battery is fully charged, any sudden decrease in power consumption will cause reverse power flow.

The second problem is that the accuracy of power consumption predictions is not very high. Power consumption can fluctuate suddenly on a second-by-second basis, so if it were possible to accurately predict power consumption a few seconds into the future based on past changes in power consumption, it would be possible to accurately control power generation even if power consumption suddenly changes. However, the reality is that even if such "predictive control" is attempted, the accuracy is not currently very high.

One of the causes of this is thought to be the "sampling interval" in power generation control systems. In other words, in conventional general power generation control systems, various data required for control (for example, the power generated by each power generation device, the power consumption of the load) is constantly collected at predetermined intervals (sampling intervals) to be monitored. In systems that perform predictive control, this also includes data that affects the amount of power generated, such as weather data. Traditionally, the sampling interval for collecting all of this data has been uniformly set at a fixed interval. In Japan, for historical reasons, a system that samples every six seconds has become 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 causes 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 generated 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 generated 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 generated. This time lag becomes greater the larger the power generation system.

For example, consider a power generation system consisting of 10 solar power generation devices operated by 10 power generation control systems. The system was operating at 70% power generation, but an increase in power consumption meant that power generation had to be increased to 80%. In this case, a control command value to increase power generation to 80% is sent to each of the 10 power generation control devices. However, immediately afterward, power consumption suddenly drops, meaning that power generation must be reduced to 40%. Because 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, potentially resulting in reverse power flow.

The larger the power generation system, the greater the number of power generation control devices and the greater the time lag, making the impact of this problem more serious. This problem is not limited to solar power generation, but is also present in other power generation systems such as wind power generation, and particularly 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 power generation with the aim of "avoiding reverse power flow," and control (second control) that increases the power generation of 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 there is a time lag and the increase in power generation is delayed, 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 power generation stoppage. Therefore, of the two types of control, the first control is the one that should be emphasized.

In consideration of the above-mentioned 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 that executes this control program.

The "time lag" between transmitting 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 power generation amount, the time lag can be reduced by simply reducing the number of power generation control devices that transmit 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 power generation amounts, to a plurality of power generation control devices,
a power generation power acquisition step of acquiring 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 accordance with fluctuations in the difference between the total power generation power 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 using this configuration, the number of power generation control devices that are subject to 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 power consumption.

This power generation control program is intended to be used in a self-consumption power generation control system that requires the avoidance of reverse power flow. It is particularly important that the interval at which the "power consumption acquisition step" is executed is "short enough to enable rapid control of power generation in response to fluctuations in power consumption." However, power generation changes more slowly than power consumption, and rarely fluctuates suddenly over short periods of time, such as seconds. Even if the acquisition of this data were delayed, this would not result in serious repercussions such as the occurrence of reverse power flow. Therefore, 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, the "interval at which power consumption is acquired, which is the basis for power generation control," was set to a time interval that allows rapid tracking of changes in power consumption.

The above configuration is the basic configuration of the control algorithm when implementing the above-mentioned "first control," but a control algorithm for implementing "second control" may be prepared separately. The decision as to whether to implement first control or second control is preferably made "in response to fluctuations in the difference between the upper limit of total power generation and the power consumption value." However, even with only first control, the increased controllability of power generation amount achieved by first control means that operation can be performed at the maximum possible output when control is not in operation. Consequently, it is believed that the power generation efficiency of the entire system can be improved even without implementing second control.

In the above configuration, the control command value does not necessarily have to be the same 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, suppose there are four power generation control devices (A, B, C, and D), and applying the algorithm described above selects only A and B as the control targets. In this case, the power generation power of the unselected devices C and D will not change when a control command value is sent. However, rather than sending the same control command value to both devices A and B (e.g., if A's current output is 70% and B's current output is 40%, then both A and B will be uniformly reduced to 45%), different control command values may be sent (e.g., reducing A's output to 60% and B's output to 30%). This is because sending values close to the current power generation amount to each power generation control device is expected to improve tracking. Alternatively, an algorithm could be considered in which A's output is set to 0%, stopping output, and only B is the target for sending control command values from subsequent cycles until control is relaxed.

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 controllability (response characteristics) is sufficiently improved by limiting the number of operating power generation control systems (PCSs) to be controlled, control using the same value will still sufficiently improve controllability.

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

When the "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, in any of the above configurations, the predetermined interval (sampling interval) may be, for example, six seconds. As mentioned above, six seconds is the de facto standard value in Japan, and there is little need to change it for data other than power consumption, as there are few sudden changes in that data.

In any of the above configurations, the emergency may be a time period of one second or less after a decrease in the power consumption is detected. 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 (shorter than conventional intervals). However, the sampling intervals for acquiring various data other than power consumption may remain the same as conventional intervals (longer than the power consumption acquisition interval), or all intervals may be uniformly set to the same interval as the power consumption acquisition interval. For example, it is possible to set all sampling intervals to one second. This is because adopting the configuration of the present invention improves the controllability of the power generation control device.

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

The power generation control system of the present invention comprises multiple 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 of the power generation control programs described above to control the output power from the power generation control device.

This 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 fluctuates over time.

FIG. 1 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. 10 is a graph showing changes in power consumption over time. FIG. 2 is a diagram showing the control status of output power 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 the control flow of a self-consumption power generation control system that combines predictive control.

The following describes 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. Furthermore, identical or similar components may be designated by the same reference numerals, and descriptions thereof 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 power generation device 1 (1a, 1b, 1c) and control the amount of power generated by the power generation devices.
The power generation control devices 2a, 2b, and 2c can control the amount 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, the 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 into AC power.
The power receiving and transforming unit 3 receives power from the power generation control devices 2a, 2b, and 2c via a power line L2 and power lines Lb2a, Lb2b, and Lb2c branching from it, and also receives power from a commercial power source 4, such as an electric power company, via a power line L4, and supplies power to loads 5a, 5b, and 5c via a power line L5.

The measurement control terminal 6 acquires the output power from the power generation control device 2, the power supply from the commercial power source 4 and the power consumption of the load 5 (5a, 5b, 5c), the power supply 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 by providing power meters 7 and 9 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 and 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 supply 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, and 2c (hereinafter referred to as total generated power). However, in order to accurately measure the power consumption, which fluctuates particularly greatly, the power consumption may also be measured directly using a power meter 9.

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

In order to avoid reverse power flow without paralleling off 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 (for example, 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 equal to or less than 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 the total power generation upper limit of 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.

The measurement control terminal 6 transmits control command values (hereinafter sometimes referred to as individual command values) specifying the upper limit values of individual 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 using, for example, the MPPT method, etc., 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 the 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.

In addition, if the PCS is allowed to set a new command value while searching for the maximum power generation value using the MPPT method, etc., i.e., at a cycle 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, and 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 a 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, fluctuating faster than the command interval. Therefore, the measurement control terminal 6 can independently set the sampling interval (period) for acquiring power consumption (hereinafter sometimes referred to as the detection interval) and the command interval (or command value transmission interval) for controlling each power generation control device 2, and set 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 power consumption in the near future from the measurement data of multiple power consumptions. For example, it becomes possible to predict the power consumption after the response time has elapsed.
In the case of n=2, the prediction is based on a linear function and is therefore limited to the prediction of 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 independently set the power consumption detection interval and the command interval for controlling the power generation control device 2, allowing the power consumption detection interval to be set short. 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, enabling swift power generation control and precise control.

The measurement control terminal 6 uniformly transmits to each of all power generation control devices 2a, 2b, and 2c 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).
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 amount of power generation is equally distributed to each of the power generation control devices 2a, 2b, and 2c. For example, if the total number of power generation control devices 2a, 2b, and 2c is Nc, the individual upper limit can be set to [upper limit of the total power generation]/Nc for each of the power generation control devices 2a, 2b, and 2c.

Furthermore, if the power generation control devices 2a, 2b, and 2c have different rated powers, individual upper limit values proportional to the rated powers 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 amount of power generation 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 capacity output from each power generation control device 2a, 2b, 2c varies from moment to moment because it depends on the installation status of the power generation devices 1a, 1b, 1c, the surrounding environment, and time. Therefore, individual upper limit values are set according to the actual power generation status.

In order to control the amount of power generation while avoiding reverse power flow and adjusting to fluctuations in power consumption, control is performed in accordance with 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, the total power generation must be reduced in line with the decrease in power consumption in order to avoid reverse power flow.
When the power consumption decreases as shown in region B in Fig. 3, the power consumption has a negative gradient with respect to time. Whether or not Case 1 applies is determined solely based on whether or not the power consumption has decreased, and a simultaneous decrease in the amount of power generation does not affect the control value.
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 in FIG. 3, the power consumption has a positive gradient with respect to time.

Generally, 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. Therefore, the controllability of the power generation in the entire power generation control system 100 including multiple power generation control devices 2 is improved.

In Case 1, the risk of reverse power flow occurring increases because power consumption decreases, so it becomes necessary to quickly control, or reduce, the power generation.
In particular, when the fluctuation in power consumption changes from an increase to a decrease (for example, P1 in Figure 3) or when the absolute value of the decrease in power consumption increases (for example, P2 in Figure 3), the speed of control can be improved by sending a command value to the selected power generation control device 2 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 a quick 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 using a specific example.

As shown in FIG. 4, at time _t0 , the upper limit of the total power generation 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.

If 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 PCS4 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 amount of power generation in the past can be selected. Therefore, the measurement control terminal 6 stores the cumulative amounts of power generation of all the power generation control devices 2 in the storage unit 63. By referring to the stored cumulative amounts of power generation, the measurement control terminal 6 can select a specific power generation control device 2.

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 prevent the power generation control device 2 from outputting 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 of the total power generation is reduced to 25 kW between time _t1 and 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.

If the upper limit of the total power generation is reduced to 10 kW from time _t2 to time _t3 , PCS4 will exceed the total power generation of 10 kW, so its command value is set to 0 kW. Since the output power of PCS3, 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 will command the power generation control device 2 selected from the power generation control devices 2 other than PCS3 to output the discrepancy (the difference between 10 kW and the output power of PCS3).

If 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, and so the PCS 3 equally distributes the output power of the deviation to the remaining power generation control devices 2 whose output is controlled to 0 kW. In other words, it commands the remaining power generation control devices 2 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 amount of power generation.
Furthermore, if there is a power generation control device 2 whose generated power cannot reach the set individual upper limit value (5 kW in Figure 4) 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 generated power (25 kW - (10 kW + 3 kW) = 12 kW) is evenly distributed among the other power generation control devices 2 (two PCSs, PCS2 and PCS4) to obtain a value (12 kW/2 = 6 kW) which is set 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 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. Therefore, 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 adjusts the individual upper limit of each power generation control device 2 to control the output power.

Furthermore, by allocating output power equally to all power generation control devices 2 that were not previously 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 power generation control devices 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 storage 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 power) 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, it is obtained directly.

The power consumption acquisition step is performed, for example, at intervals of one second. The generated power acquisition step may be performed at the same interval as the power consumption acquisition step, but can be performed at intervals of, for example, six 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 obtained. When comparing generated power and power consumption, it is not necessary to use generated power acquired at the same time. If the acquisition cycles for generated power and power consumption are different, the most recently acquired values for each can be used.

S2: Second step: From the acquired power consumption, 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.

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 (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 limit, 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) and change the individual upper limit, 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, 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, the regression curve for predicting power consumption needs to be a function with at least a second order or higher order for power consumption, which requires three or more past power consumption values.
The power consumption detection interval 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 the control flow of a self-consumption power generation control system that combines predictive control. In this flow, values of power consumption and power generation one second later are predicted using a quadratic function.

Control begins in step Sb1. Power consumption is measured in step Sb2. A predicted value for power consumption one second from now is calculated in step Sb3, and the available 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 available power generation one second from now exceeds the predicted power consumption one second from now, 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 surplus power can be allocated to charging the storage battery, the conditions under which reverse power flow may occur will be different; in such cases, an additional algorithm is used to calculate the available power generation.

If it is determined in step Sb4 that "control should be strengthened," a list of "emergency control messages with a narrower range of PCSs to be transmitted" is generated in step Sb5. Next, in step Sb6, the control values for each PCS are recalculated. Next, in step Sb7, one emergency control message is transmitted. 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 step Sb4 determines that "increased control is not necessary," 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 example is not essential, but since the interval is shorter than conventionally, it is expected that prediction accuracy will improve. Therefore, by combining control using prediction with this invention, it is expected that the controllability of the power generation control system will be further improved.

This 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 time-varying power consumption. It improves the power generation efficiency of a power generation system equipped with multiple power generation control devices while also making it possible to avoid reverse power flow, making it highly applicable in industry.

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 Power receiving and transforming 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 (6)

A power generation control program that transmits a control command value that is an upper limit value of power generation power to a plurality of power generation control devices,
a power generation power acquisition step of acquiring output power from the power generation control device;
a power consumption acquisition step of acquiring a power consumption value,
a command transmission step of selectively transmitting control command values to only some of the power generation control devices in accordance with fluctuations in the difference between the total power generation power value obtained by adding up the output powers and the power consumption value, at predetermined intervals;
the command transmission step increases an upper limit value of the total power generation power in accordance with a change in the difference value when the power consumption increases;
A power generation control program characterized in that, if the control command value can be sent only to one of the power generation control devices with the highest output power to keep up with the increase in the upper limit value of the total power generation power, the control command value is sent only to that one device . A power generation control program that transmits a control command value that is an upper limit value of power generation power to a plurality of power generation control devices,
a power generation power acquisition step of acquiring output power from the power generation control device;
a power consumption acquisition step of acquiring a power consumption value,
a command transmission step of selectively transmitting control command values to only some of the power generation control devices in accordance with fluctuations in the difference between the total power generation power value obtained by adding up the output powers and the power consumption value, at predetermined intervals;
the command transmission step increases an upper limit value of the total power generation power in accordance with a change in the difference value when the power consumption increases;
A power generation control program characterized in that, when the increase in the upper limit value of the total power generation power can be kept up with by sending the control command value to only one of the power generation control devices that is closest to the rated power, the control command value is sent to only that one device . A power generation control program that transmits a control command value that is an upper limit value of power generation power to a plurality of power generation control devices,
a power generation power acquisition step of acquiring output power from the power generation control device;
a power consumption acquisition step of acquiring a power consumption value,
a command transmission step of selectively transmitting control command values to only some of the power generation control devices in accordance with fluctuations in the difference between the total power generation power value obtained by adding up the output powers and the power consumption value, at predetermined intervals;
the command transmission step increases an upper limit value of the total power generation power in accordance with a change in the difference value when the power consumption increases;
A power generation control program characterized in that, when there is a power generation control device whose output is controlled to 0 kW and a power generation control device whose output is controlled to other than 0 kW, the increase in the upper limit value of the total power generation power is reflected evenly in the power generation control device whose output is controlled to 0 kW. The power generation control program described in claim 3, characterized in that if there is an upper limit-not-reached power generation control device whose generated power does not reach the upper limit value for each of the equally distributed power generation control devices, the control command value of the upper limit-not-reached power generation control device is reset to the maximum output of the upper limit-not-reached power generation control device, and for the remaining power generation control devices subject to equal distribution, the control command value is set to a value obtained by equally redistributing the power obtained by subtracting the maximum output of the upper limit-not-reached power generation control device from the increase. The power generation control program according to any one of claims 1 to 4, wherein the power consumption and/or the generated power are both predicted values after a certain period of time. The power generation control program according to any one of claims 1 to 4, wherein the power consumption acquisition step is performed every second, and the power generation acquisition step is performed every six seconds, and the most recently acquired value is used in each step.