JP5477038B2 - Photovoltaic power generation amount prediction method and distribution system control system - Google Patents

Description

  The present invention relates to a solar power generation amount prediction method for predicting the total power generation amount of a solar power generator connected to a power distribution system, and a power distribution system control system to which the method is applied.

  Conventionally, introduction of solar power generators that generate power by converting inexhaustible solar energy into electrical energy has been promoted. The introduction of solar power generators is expected to reduce the proportion of energy sources that depend on natural resources such as oil, leading to conservation of the global environment.

  In recent years, solar power generators are becoming popular in ordinary homes due to a decrease in the introduction price of solar power generators, an increase in environmental conservation awareness, and demand for conversion to alternative energy due to fluctuations in oil prices. In particular, in newly developed residential areas and the like, there are cases where large-scale solar power generation is performed by introducing solar power generators systematically throughout the region.

  Photovoltaic generators installed in ordinary households are linked to the transmission lines (distribution system) of electric utilities. And the surplus of the amount of power generated by the solar power generator is turned back to a grid system and sold to a predetermined electric utility. The amount of electricity sold is recorded in a power sale meter installed in each household.

  In the section where the photovoltaic generators are connected, if an accident occurs and a power failure occurs, the photovoltaic generators also stop generating power. This is to eliminate the possibility that an operator who is performing a power outage recovery work will receive an electric shock due to the power that the solar power generator returns to the system.

  The stopped solar generator cannot be restarted immediately after recovering from a power outage, and is linked to the grid with a delay of several minutes. For this reason, when recovering from a power outage, the load of the entire region (actual load) is usually generated by the power sent from the electric power company (substation) to the system, together with the power normally provided by the power generation of the solar power generator. I have to pay. However, from the electric power company (substation), only the amount of transmitted power sent from the system can be grasped, and the amount covered by the power generation of the solar power generator cannot be grasped. For this reason, there is a risk of being overloaded at the moment of recovery from a power outage and chaining to a secondary power outage accident.

  Therefore, conventionally, the electric power company adds the rated power generation capacity of the photovoltaic generator connected to the grid to the amount of power sent from the grid, and manages the distribution line load (system operation, that is, system switching). Etc.). In addition, distribution facilities have been constructed assuming the amount of power that needs to be sent to the grid at this time.

  However, the solar power generator can actually generate only about 70% to 80% of the rated power generation capacity. In addition, the amount of power provided by the solar generator increases or decreases depending on the time of day and the weather. Therefore, when the distribution line load management is performed according to the above-mentioned standard, an excessive capacity is prepared.

  In the future, it is expected that there will be a further increase in the number of interconnections to the PV generator system. Therefore, there is a technology that can grasp the total power generation amount of the PV generator and the actual load, and perform appropriate distribution line load management. It is desired. Therefore, Patent Document 1 discloses a technique for calculating the normal phase current and the reverse phase current from the measured value of the automatic switch having a current measuring function and predicting the total power generation amount of the solar power generator connected to the system. Proposed.

  Further, Patent Document 2 describes the amount of solar radiation generated during clear weather calculated from the position information and date, the total rated power generation capacity of the solar power generator, and a predetermined coefficient, based on the clear time of the solar power generator connected to the grid. Techniques have been proposed for predicting total power generation.

Japanese Patent Application No. 2009-185543 Japanese Patent Application No. 2009-034134

  With the technique of patent document 1, it can estimate to the fine fluctuation | variation of the total electric power generation amount of a solar power generator, without depending on the weather (refer patent document 1, FIG. 6). However, with this technique, an error of a certain level or more may occur very rarely. In addition, since the technique of Patent Document 2 generally predicts the total amount of power generation during clear weather, the amount of power generation may be lower during cloudy weather and there is room for further improvement.

  Therefore, an object of the present invention is to provide a photovoltaic power generation amount prediction method capable of accurately predicting the total power generation amount of a solar power generator connected to a distribution system, and a distribution system control system to which the method is applied.

In order to solve the above problems, a typical configuration of the photovoltaic power generation amount prediction method according to the present invention includes a three-phase alternating current unbalance rate caused by the power generation of a solar power generator connected to a distribution system, Approximate function that is a relational expression between the positive and negative phase currents of the three-phase AC of this system at the time of photovoltaic power generation, and the current of the positive and negative phase currents of the three-phase AC of this system at the time of prediction The first step of obtaining the unbalanced predicted total power generation amount of the solar power generator linked to this system based on the value, the amount of solar radiation at the time of fine weather calculated based on the position information and the date and time of the prediction target area, Based on the total rated power generation capacity of the solar power generator, the second step of obtaining the total predicted solar power generation amount, which is the total power generation amount when the solar power generator is clear, and the unbalanced predicted total power generation amount is the total predicted solar power generation amount. If the amount exceeds the limit, this unbalanced predicted total power generation will be reduced. Characterized in that it comprises a third step of correcting, the.

  In this configuration, when the unbalanced predicted total power generation amount is equal to or greater than the solar radiation predicted total power generation amount, which is the total power generation amount during clear weather, correction is made so that the unbalanced predicted total power generation amount becomes small. Therefore, the possibility that the unbalanced predicted total power generation amount may greatly exceed the actual total power generation amount can be eliminated. The prediction target time is an arbitrary time during solar power generation.

  In the third step, correction may be performed based on the ratio of the predicted total solar power generation amount to the unbalanced predicted total power generation amount before the prediction target time point. The error between the unbalanced predicted total power generation amount and the actual total power generation amount tends to occur at a constant rate (proportional) regardless of the time, at least on the same day. From this, it becomes possible to approximate the actual total power generation amount by performing correction based on the ratio of the solar radiation predicted total power generation amount to the unbalanced predicted total power generation amount before the prediction target time point.

  The approximate function in the first step may be derived from a normal phase current and a negative phase current in a range where the load fluctuation rate after sunset is not more than a predetermined value. Thereby, the accuracy of the unbalanced predicted total power generation amount obtained in the first step can be improved.

In order to solve the above problems, a typical configuration of a distribution system control system according to the present invention includes a three-phase AC unbalance rate caused by the power generation of a photovoltaic generator linked to the distribution system, and non-sunlight. The approximate function , which is the relational expression between the positive and negative phase currents of this system during power generation, and the current values of the positive and negative phase currents of this system at the time of the prediction Is a distribution system control system that calculates the unbalanced predicted total power generation amount of the solar power generator connected to this system and operates this system, and is connected to the solar radiation amount in clear weather and the system Based on the total rated power generation capacity of the solar power generator, a maximum value calculation unit that calculates the total predicted solar power generation amount when the solar power generator is clear, and the total unbalanced predicted power before the prediction target time Deriving a correction formula based on the ratio of predicted total solar power generation to solar power generation When the formal derivation unit, the unbalanced predicted total power generation amount is equal to or greater than the solar radiation predicted total power generation amount, the correction unit for correcting the unbalanced predicted total power generation amount based on the correction formula, and the corrected unbalanced predicted total power generation amount And a switching control unit for operating the system.

  According to this configuration, when the unbalanced predicted total power generation amount ≧ the solar radiation predicted total power generation amount, the system is operated based on the corrected unbalanced predicted total power generation amount. When the unbalanced predicted total power generation amount falls below the solar radiation predicted total power generation amount, the system is operated based on the unbalanced predicted total power generation amount that has not been corrected. Therefore, the system can be operated based on a more accurate unbalanced predicted total power generation amount. In addition, the component corresponding to the technical idea in the photovoltaic power generation amount prediction method mentioned above and its description are applicable also to the said distribution system control system.

  The power distribution system control system further includes a relative ratio data table in which a ratio of the solar radiation predicted total power generation amount to the unbalanced predicted total power generation amount is stored every predetermined time, and the correction formula deriving unit refers to the relative ratio data table. Thus, it is preferable to derive a correction formula. Thereby, a correction formula can be derived suitably.

  ADVANTAGE OF THE INVENTION According to this invention, the solar power generation amount prediction method which can estimate the total electric power generation amount of the solar power generator linked to the power distribution system correctly, and a power distribution system control system which applied this can be provided.

It is a figure explaining a power distribution system. It is a figure which illustrates the composition of a power distribution system control system. It is a figure which illustrates the outline | summary of a solar power generator data table. It is a figure which illustrates the daily load fluctuation of a power distribution system. It is a figure which illustrates the outline | summary of a relative ratio data table. It is a figure explaining the photovoltaic power generation amount prediction method. It is a figure explaining calculation of unbalanced prediction total power generation amount. It is the figure which compared the unbalanced prediction total power generation amount which the predicted value calculation part calculated with the actual total power generation amount. It is a figure explaining the correction method of unbalanced prediction total power generation amount It is a figure explaining other correction methods of unbalanced prediction total power generation amount.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

[Distribution system 100]
FIG. 1 is a diagram for explaining a power distribution system 100. In particular, FIG. 1A shows the distribution system 100 during solar power generation, FIG. 1B shows the power distribution system 100 during non-solar power generation, and FIG. 1C shows the connection of the solar power generator 130. The form is shown by way of example.

  The distribution system 100 is a three-phase alternating current, and supplies the current sent from the substation 110a (110b) to a plurality of general households 140 and the like. As shown in FIGS. 1 (a) and 1 (b), in a general household 140 or the like, at the time of solar power generation, the power distribution system 100 and the solar power generator 130 (in FIG. 1, PV is solar power generation (Photovoltaic power generation). Electricity is supplied from both sides, and necessary power is supplied only by the distribution system 100 during non-solar power generation. Here, the electric power generated by the solar power generator 130 is illustrated as being consumed by the general household 140 or the like.

  As shown in FIG.1 (c), the solar power generator 130 connects to arbitrary two phases among the three phases (U, V, W) in the power distribution system 100 via the light transformer 132. FIG. Therefore, the power generation amount of the solar power generator 130 affects the unbalance rate of the three-phase alternating current. Which two phases are to be connected is determined in consideration of connection conditions in the vicinity when the solar power generator 130 is installed. Information on the connection mode (connection phase and rated power generation capacity) of the solar power generator 130 is managed by an electric power company.

  The distribution system 100 is provided with a sensor built-in automatic switch 120 as a measuring device for each distribution section 122. The sensor built-in automatic switch 120 is an electronically controlled switch that opens and closes the line (ON / OFF), and further has a function of measuring electrical parameters such as current, voltage, and power factor. By controlling a plurality of sensor built-in automatic switches 120, the route of the power distribution system 100 can be switched.

  Therefore, for example, when an accident occurs, power supply to the power distribution section 122 can be stopped by switching the route of the nearby sensor built-in automatic switch 120. In such a case, power may be temporarily stopped in the section adjacent to the accident section, but power cannot be supplied to only one distribution section 122 from one substation 110a. Since power can only be supplied by power transmission (power transmission in the normal power transmission direction), power supply can be restored early by reverse power transmission from another substation 110b (power transmission in the reverse power transmission direction) or the like.

  The sensor built-in automatic switch 120 transmits the measured electrical parameter data to a power distribution system control system 200 (see FIG. 2) described later. Specifically, the measured current and voltage are converted into a complex vector including phase information and transmitted. Since this conversion method is well known to those skilled in the art, a description thereof will be omitted.

[Power Distribution System Control System 200]
FIG. 2 is a diagram illustrating a configuration of the power distribution system control system 200. As illustrated in FIG. 2, the power distribution system control system 200 includes a system control unit 210, an input unit 212, an output unit 214, a storage unit 216, a predicted value calculation unit 220, a maximum value calculation unit 230, a correction formula derivation unit 240, A correction unit 250 and a switching control unit 260 are included.

  The system control unit 210 is a computer system that includes a central processing unit (CPU) and controls the entire power distribution system control system 200.

  The input unit 212 inputs predetermined information from the outside through a keyboard, a mouse, a touch panel, a file input / output device, data communication through a network, or the like. For example, the data of the solar power generator 130 connected to the power distribution system 100 is input to the solar power generator data table 216a described later.

  The output unit 214 includes a display, a printer, and the like, and displays information to the user and performs printing. It is also possible to save the output content as data in a recording medium, or to perform data communication or web display over a network.

  The storage unit 216 includes a ROM, a RAM, an EEPROM, a nonvolatile RAM, a flash memory, an HDD, and the like. The storage unit 216 stores measurement data of the sensor built-in automatic switch 120, and includes a solar power generator data table 216a and a relative ratio data table 216b described later.

  FIG. 3 is a diagram illustrating an outline of the solar power generator data table 216a. As illustrated in FIG. 3, the solar power generator data table 216 a stores connection phases and rated power generation capacities of the solar power generators 130 connected to the power distribution system 100. The solar power generator data table 216a is preferably a database that can be updated at any time, and is composed of a storage medium such as a hard disk or a CD-ROM.

(Configuration for obtaining unbalanced predicted total power generation)
The predicted value calculation unit 220 includes a first calculation unit 222, a second calculation unit 224, a third calculation unit 226, and a fourth calculation unit 228, and calculates the unbalanced predicted total power generation amount of the solar power generator 130.

The first calculation unit 222, with reference to the solar power generator data table 216a, each connection phase of the distribution system _{100 (P WU, P UV,} P VW) Get the total rated power generation capacity, the rated power between each line Current values (I _WU , I _UV , I _VW ) are calculated. Then, the rated generated current between the lines is converted into a single-phase rated generated current (I _U , I _V , I _W ) based on the following formulas 1 to 3.
I _U = I _WU −I _UV (Formula 1)
I _V = I _UV −I _VW (Formula 2)
I _W = I _VW −I _WU (Formula 3)

Further, the first calculation unit 222 converts the rated power generation current (I _U , I _V , I _W ) into a normal phase current and a reverse phase current, and generates a three-phase alternating current caused by the power generation of the solar power generator 130. The unbalance rate α is calculated (that is, the unbalance rate due to the solar power generator 130 is a calculated value by desk calculation). The solar power generator 130 connected to the power distribution system 100 generally operates in the same manner (generally, the amount of power generation increases during clear weather, and generally decreases during cloudy weather), and this balance is maintained because the balance of three-phase alternating current is maintained. It can be considered that the equilibrium rate is always constant. Note that the power generation by the solar power generator 130 in this embodiment is assumed to be due to power generation by the solar power generator 130 only.

  The second calculation unit 224 derives approximate functions of the positive-phase current and the negative-phase current of the three-phase alternating current caused by the load. Since this approximate function is directly related to the accuracy of the unbalanced predicted total power generation amount, it is optimal if the solar power generator 130 is disconnected from the distribution system 100 and can be derived from the daytime normal phase current and the negative phase current as the prediction target time point. It is. However, it is impossible to disconnect all the linked solar power generators 130.

  Therefore, the second calculation unit 224 refers to the measurement data at the time of non-solar power generation of the sensor built-in automatic switch 120 stored in the storage unit 216, and the normal-phase current and the reverse of the three-phase AC caused by the load. The approximate function of the phase current is derived. This is because the life pattern of the customer is generally constant unless special electrical equipment is used, and the tendency of the load between lines can be considered to be uniform regardless of day or night.

  In the present embodiment, in order to reflect the daytime load tendency as much as possible, the second calculation unit 224 derives an approximate function from the positive phase current and the negative phase current in a range where the load fluctuation rate after sunset is not more than a predetermined value. FIG. 4 is a diagram illustrating a daily load fluctuation of the distribution system 100. As illustrated in FIG. 4, the range in which the load fluctuation rate is less than or equal to a predetermined value is 20:00 to 23:00. Note that this predetermined range or less can be appropriately selected (arbitrarily determined) according to circumstances.

  More specifically, non-solar power generation is assumed to be after sunset (at night) and in the rain. However, in order to know that it is raining, weather information must be obtained separately and collated, and depending on the day, the weather is unstable, such as being able to see a clear sky during rainy weather. On the other hand, it is easy to handle after sunset because it can be said that solar power is not generated.

  Even after sunset, it is preferable to select a time zone that has a load tendency similar to that in the daytime. As shown in Table 1, the approximation derived from the normal phase current and the negative phase current from 20:00 to 23:00 as compared with the approximate function derived from the positive phase current and the negative phase current from 20:00 to 3:30. Using the function, the average error from the actual total power generation is lower when the unbalanced predicted total power generation is calculated. This is thought to be due to the tendency to load differently from daytime because the hot water heater and the like are turned on near the morning.

  Moreover, as shown in Table 1, the average error with the actual total power generation is lower when the unbalanced predicted total power generation is calculated using the approximate function derived on the same day. This is because the load tendency tends to be similar on the same day. Therefore, as a preferred specific example, an approximate function may be derived from the positive phase current and the negative phase current from 20:00 to 23:00 on the same day of the week before obtaining the unbalanced predicted total power generation amount. In addition, the replacement on weekdays in Table 1 is the case where the unbalanced predicted total power generation amount for holidays is obtained using an approximate function derived from measurement data on weekdays, or the approximate function derived from measurement data on holidays is used. This is a case where the unbalanced predicted total power generation on weekdays is obtained.

  The third calculation unit 226 calculates a positive current of a three-phase alternating current that can be caused by the power generation and load of the solar power generator 130 connected to the power distribution system 100 from the measurement data of the sensor built-in automatic switch 120 at the prediction target time point. The current value of the reverse phase current is calculated. “Present” here is not limited to the time when calculation is being performed, but refers to the time when it is desired to know the amount of photovoltaic power generation (that is, the prediction target time), and the non-solar power generation time is a past value. It is expressed as “present” in contrast to.

  In addition, at the time when the power distribution system 100 recovers from the power failure, naturally, the current values of the normal phase current and the reverse phase current at the time of recovery cannot be obtained. However, when recovering within a few minutes after a power failure, the current values of the positive phase current and the reverse phase current immediately before the power failure may be applied, and the unbalanced predicted total power generation can be obtained with almost good accuracy. .

  The fourth calculation unit 228 is based on the unbalance rate calculated by the first calculation unit 222, the approximate function derived by the second calculation unit 224, and the current values of the positive phase current and the negative phase current calculated by the third calculation unit 226. Thus, the unbalanced predicted total power generation amount of the solar power generator 130 in the distribution system 100 is obtained. A specific method for obtaining the unbalanced predicted total power generation amount will be described later.

(Configuration for calculating the total amount of solar radiation predicted power generation)
The maximum value calculation unit 230 includes a solar radiation amount calculation unit 232 and a power generation amount calculation unit 234, and calculates a solar radiation predicted total power generation amount that is a total power generation amount when the solar power generator 130 is clear.

  The solar radiation amount calculation unit 232 calculates the solar radiation amount during clear weather based on Equation 4. In the present embodiment, it is assumed that the solar power generator 130 is installed at an angle of 30 ° with respect to the horizontal plane with respect to the horizontal plane, and the amount of solar radiation when the solar power generator 130 is sunny is calculated. In addition, the solar altitude, the atmospheric solar radiation intensity, the atmospheric transmittance, and the atmospheric mass in Expression 4 are calculated from position information (latitude, longitude, altitude) and date / time of the prediction target area. Since these calculation methods are well known to those skilled in the art, a detailed description thereof will be omitted.

The power generation amount calculation unit 234 is the amount of solar radiation calculated when the solar radiation amount calculation unit 232 is clear, the total rated power generation capacity of the solar power generator 130 in the prediction target area acquired from the solar power generator data table 216a, and a predetermined coefficient. Is used to calculate the total predicted solar radiation power generation based on Equation 5.
Total amount of solar radiation predicted power generation = amount of solar radiation x total rated power generation capacity x coefficient (Formula 5)

  The predetermined coefficient is determined by performing regression analysis based on Equation 5 using actual data (actual measurement value) in a model region or the like. The accuracy of such a coefficient is maintained by setting it in an arbitrary unit period (for example, every month). The predetermined coefficient may be stored in advance in the storage unit 216 or may be input from the input unit 212.

(Configuration for correcting unbalanced predicted total power generation)
As described above, the predicted value calculation unit 220 determines the unbalanced predicted total power generation amount, and the maximum value calculation unit 230 determines the solar radiation predicted total power generation amount. FIG. 5 is a diagram illustrating an outline of the relative ratio data table 216b. As illustrated in FIG. 5, the relative ratio data table 216b stores an unbalanced predicted total power generation amount and a solar radiation predicted total power generation amount every predetermined time (for example, every minute).

  When the unbalanced predicted total power generation amount ≧ the solar radiation predicted total power generation amount, the correction formula deriving unit 240 stores the ratio of the solar radiation predicted total power generation amount to the unbalanced predicted total power generation amount in the relative ratio data table 216b (the solar radiation predicted total power generation amount / (Unbalanced predicted total power generation) is stored. When the unbalanced predicted total power generation amount <the solar radiation predicted total power generation amount, 1 is stored as the ratio.

The correction formula deriving unit 240 derives the following correction formula (Formula 6) with reference to the relative ratio data table 216b. Here, the correction term A is the ratio of the prediction target time points (during power failure) stored in the relative ratio data table 216b or the average value of the ratios near the prediction target time points. For example, the average value of the ratios for 30 minutes immediately before the prediction target time of this ratio can be used. In addition, although Formula 6 is illustrated as a very simple proportional formula, a constant may be added and a multi-element polynomial may be used.
Unbalanced predicted total power generation after correction = Unbalanced predicted total power generation × correction term A (Formula 6)

  The correction unit 250 corrects the unbalanced predicted total power generation amount based on the correction formula (Formula 6) derived by the correction formula deriving unit 240. Here, since 1 is stored as the ratio in the case of the unbalanced predicted total power generation <the solar radiation predicted total power generation, as a result, only when the unbalanced predicted total power generation ≧ the solar radiation predicted total power generation Correction is made so that the equilibrium predicted total power generation amount becomes smaller. Note that the correction unit 250 may compare the unbalanced predicted total power generation amount with the solar radiation predicted total power generation amount and perform correction only when the unbalanced predicted total power generation amount is larger.

  In other words, since it is not normal to generate electricity beyond the amount of solar radiation in clear weather, the amount of power generation based on the calculation of solar radiation can be considered as the maximum amount of power generation. Those exceeding this are corrected to be small. In addition, if the unbalanced predicted total power generation amount can be appropriately predicted, the power generation amount is equal to or less than the power generation amount based on the amount of solar radiation when the weather is fine. As a result, it is possible to always predict an appropriate value that exceeds the power generation amount and is as small as possible.

  The switching control unit 260 performs distribution line load management (operation of the distribution system 100, that is, switching of the distribution system 100, etc.) based on the corrected unbalanced predicted total power generation amount. Thereby, since it is not necessary to secure an unnecessarily large amount of current, there are effects such as cost reduction and improvement in supply reliability.

[Solar power generation forecasting method]
Hereinafter, the photovoltaic power generation amount prediction method applied by the power distribution system control system 200 will be specifically described. FIG. 6 is a diagram illustrating a photovoltaic power generation amount prediction method. FIG. 7 is a diagram for explaining the calculation of the unbalanced predicted total power generation amount.

  As shown in FIG. 6, first, the unbalanced predicted total power generation amount and the solar radiation predicted total power generation amount at the prediction target time point are obtained. The unbalanced predicted total power generation amount is calculated by the predicted value calculation unit 220 through S302 to S314. In the following, when obtaining the unbalanced predicted total power generation amount in a specific section, the section current obtained by subtracting the downstream side from the upstream side is used.

(Prediction method of power generation based on unbalance rate)
Specifically, first, the prediction target area and the date and time are input from the input unit 212 (S302). And based on this prediction object area, the 1st calculating part 222 refers to the solar power generator data table 216a, the connection form (connection phase and rated power generation) of each solar power generator 130 connected to the power distribution system 100. The total rated power generation capacity for each connected phase is acquired from (capacity) (S304). And the 1st calculating part 222 calculates the unbalance rate (alpha) of the three-phase alternating current which makes the factor the electric power generation of the solar power generator 130 based on the calculation mentioned above (S306). In other words, the unbalance rate α indicates what locus the load on the distribution system 100 fluctuates when the solar power generator 130 generates power.

  The above process is represented as shown in FIG. 7A on the graph of the positive phase current and the negative phase current. That is, the positive phase current and the reverse phase current obtained from the connected phase and the rated power generation capacity of each solar power generator 130 are plotted on a graph, and the slope (proportional constant) of the straight line connected to the zero value (origin) is calculated. The reciprocal is the unbalance rate α.

  Next, the second calculation unit 224 refers to the measurement data of the sensor built-in automatic switch 120 stored in the storage unit 216 and derives an approximate function from the positive-phase current and the negative-phase current of the three-phase AC of the power distribution system 100. (S308). In this embodiment, in order to improve the accuracy of this approximate function, in particular, on the same day as the prediction target time point, using the positive phase current and the negative phase current with the load fluctuation rate after sunset within a predetermined range, An approximate function is derived.

  The above process is represented as shown in FIG. 7B on the graph of the positive phase current and the negative phase current. In other words, the approximate function derived in S308 is an approximate expression for plotting the positive phase current and the negative phase current in a range where the load fluctuation rate after sunset is below a predetermined value. In FIG. 7B, this approximate function is illustrated as a linear function. However, the present embodiment is not limited to this, and the approximate function may be any function (a multi-order function such as a linear function or a quadratic function).

  Next, the 3rd calculating part 226 calculates the present value of a positive phase current and a negative phase current based on the measurement data of the sensor built-in automatic switch 120 in the prediction object time (S310).

  The above process is represented as shown in FIG. 7C on the graph of the positive phase current and the negative phase current. That is, the current values of the positive phase current and the negative phase current in S310 are expressed as plot I.

  Next, the fourth computing unit 228 derives a first-order approximation function that includes the current value and uses the reciprocal of the unbalance rate α calculated in S306 as a slope (proportional constant). And the approximate function derived in S308 (plot M) are determined (S312). Then, a vector from the current value to this intersection is calculated to determine the unbalanced predicted total power generation amount (S314).

  The above process is represented as shown in FIG. 7D and FIG. 7E on the graph of the positive phase current and the negative phase current. That is, a linear approximation function is derived so as to pass the plot I with the reciprocal of the unbalance rate α as a slope, and the intersection (plot M) in S312 is determined. Then, a vector from plot I to plot M is calculated, and the unbalanced predicted total power generation in S314 is obtained as the magnitude of this vector. The magnitude of the vector from the zero value (origin) to the plot M represents the actual load in the distribution system 100, and the magnitude of the vector from the zero value (origin) to the plot I represents the power supplied from the distribution system 100. Represent.

  If the reciprocal of the unbalance rate α calculated in S306 (the slope of the first order approximation function) coincides with the slope of the approximation function in S308 (the unbalance rate), the vector is calculated. I can't. In such a case, the installation position of the sensor built-in automatic switch 120 is changed so as to expand or contract the prediction target section, and the prediction condition (any value of the slope of each approximation function) may be changed. . As a result, the vector can be calculated because the balance of the three-phase alternating current is lost.

(Prediction method of power generation based on solar radiation)
On the other hand, the solar radiation predicted total power generation amount is calculated by the maximum value calculation unit 230 through S302 to S304 and S320 to S322. More specifically, first, the prediction target area and the date and time are input by the input unit 212 (S302). Then, the power generation amount calculation unit 234 acquires the total rated power generation capacity of the solar power generator 130 in this prediction target area with reference to the solar power generator data table 216a (S304).

  Next, based on the prediction target area and the date and time input in S302, the solar radiation amount calculation unit 232 calculates the solar radiation amount during clear weather based on Equation 4 (S320).

  Next, the power generation amount calculation unit 234 calculates the solar radiation predicted total power generation amount of the solar power generator 130 based on Equation 5 using the sunny solar radiation amount calculated in S320 and the total rated power generation capacity acquired in S304 ( S322).

  Note that either the calculation of the unbalanced predicted total power generation amount (S302 to S314) or the calculation of the solar radiation predicted total power generation amount (S302 to S304, S320 to S322) may be performed first.

(Correction method for unbalanced predicted total power generation)
FIG. 8 is a diagram comparing the unbalanced predicted total power generation amount calculated by the predicted value calculation unit 220 with the actual total power generation amount. The unbalanced predicted total power generation amount obtained by the above-described method almost reflects the actual total power generation amount as shown in FIG. However, as shown in FIG. 8 (b), although rare, if the load tendency of the distribution system 100 is significantly different from the approximate function derived in S306, an error of a certain level or more may occur.

  The error between the unbalanced predicted total power generation and the actual total power generation tends to occur at a constant rate regardless of the time (at least on the same day). Become). That is, when the unbalanced predicted total power generation amount is expanded or reduced vertically, it substantially matches the actual total power generation amount.

  In this embodiment, every time the unbalanced predicted total power generation amount is calculated, the correction formula deriving unit 240 compares the unbalanced predicted total power generation amount with the solar radiation predicted total power generation amount (that is, the maximum value) that is the total power generation amount during clear weather. (S324). When the unbalanced predicted total power generation amount is equal to or greater than the solar radiation predicted total power generation amount (S324 Yes), the ratio (solar radiation predicted total power generation amount / unbalanced predicted total power generation amount) is stored in the relative ratio data table 216b (S326). When the unbalanced predicted total power generation amount is lower than the solar radiation predicted total power generation amount (S324 No), 1 is stored as the ratio (S328).

  Then, the correction formula deriving unit 240 derives a correction formula at the prediction target time (S330). Next, the correction unit 250 applies the correction formula to the unbalanced predicted total power generation amount to calculate the corrected unbalanced predicted total power generation amount (S332).

  The correction formula deriving unit 240 may store the ratio for each predetermined time in the relative ratio data table 216b at any time, and the application of the corrections in S330 and S332 may be performed under specific conditions. For example, only when the prediction target time is input from the input unit 212 and an instruction to predict the total power generation amount of the solar power generator 130 at that time is given, the correction is performed with reference to the ratio input at any time. It shall be.

  FIG. 9 is a diagram illustrating a method for correcting the unbalanced predicted total power generation amount. FIG. 9A shows the unbalanced predicted total power generation amount before correction, and FIG. 9B shows the unbalanced predicted total power generation amount after correction. Here, the unbalanced predicted total power generation amount is corrected using the correction term A as an average value for 30 minutes immediately before the prediction target time point of the ratio stored in the relative ratio data table 216b.

  Table 2 shows the unbalanced predicted total power generation amount before correction and the average error and the maximum error of the unbalanced predicted total power generation amount after correction in the system where the distribution line allowable current is 600A. As shown in Table 2, when such correction is performed, both the average error and the maximum error are reduced. Here, as a result of the correction, it is understood that safe distribution line load management can be performed only by estimating an error of the sensor built-in automatic switch 120 by about 50A.

(Other correction methods for unbalanced predicted total power generation)
FIG. 10 is a diagram for explaining another correction method for the unbalanced predicted total power generation amount. In the above-described embodiment, the description has been made so that the unbalanced predicted total power generation amount is corrected by multiplying by the ratio of the solar radiation predicted total power generation amount / unbalanced predicted total power generation amount. On the other hand, as shown in FIGS. 10A and 10B, correction is made so that the value of the predicted total solar power generation amount is used (cut) at the time when the unbalanced predicted total power generation amount exceeds the predicted total solar power generation amount. May be. However, since the unbalanced predicted total power generation at the time when the unbalanced predicted total power generation is lower than the solar radiation predicted total power generation can be reduced by using the ratio as in the above embodiment, it is smaller. It is possible to predict an appropriate value.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. According to the photovoltaic power generation amount prediction method (distribution system control system 200) described above, since the unbalanced predicted total power generation amount is corrected when the unbalanced predicted total power generation amount ≧ the solar radiation predicted total power generation amount, It becomes possible to obtain the total power generation amount of the solar power generator 130 with a predetermined accuracy.

  Needless to say, the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, the amount of solar radiation during clear weather may be calculated using observation data such as AMEDAS. Moreover, you may employ | adopt another calculation for calculation of each parameter, without using the formula disclosed by this embodiment.

  INDUSTRIAL APPLICABILITY The present invention can be used for a photovoltaic power generation amount prediction method for predicting the total power generation amount of a solar power generator linked to a distribution system, and a distribution system control system to which the method is applied.

DESCRIPTION OF SYMBOLS 100 ... Distribution system, 110a, 110b ... Substation, 120 ... Automatic switch with built-in sensor, 122 ... Distribution section, 130 ... Solar power generator, 132 ... Light transformer, 140 ... General household, 200 ... Distribution system control system, 210 ... System control unit, 212 ... Input unit, 214 ... Output unit, 216 ... Storage unit, 216a ... Photovoltaic generator data table, 216b ... Relative ratio data table, 220 ... Predicted value calculation unit, 222 ... First calculation unit 224 ... second calculation unit, 226 ... third calculation unit, 228 ... fourth calculation unit, 230 ... maximum value calculation unit, 232 ... irradiation amount calculation unit, 234 ... power generation amount calculation unit, 240 ... correction formula derivation unit, 250 ... correction unit, 260 ... switching control unit

Claims (5)

Relational expression between the unbalance rate of the three-phase alternating current caused by the power generation of the solar power generator connected to the distribution system, and the positive and negative phase currents of the three-phase alternating current of the system during non-solar power generation Based on the approximate function and the current values of the positive and negative phase currents of the three-phase alternating current of the system at the prediction target time, the unbalanced predicted total power generation amount of the solar power generator connected to the system is calculated. A first step to find,
Based on the location information of the prediction target area and the sunny day solar radiation amount calculated based on the date and time, and the total rated power generation capacity of the solar power generator, the solar power generation is the total solar power generation amount during sunny weather. A second step for obtaining a predicted total power generation amount;
A third step of correcting the unbalanced predicted total power generation amount to be smaller when the unbalanced predicted total power generation amount is equal to or greater than the solar radiation predicted total power generation amount;
A method for predicting the amount of photovoltaic power generation, comprising:   The solar power generation amount prediction according to claim 1, wherein the third step performs correction based on a ratio of the solar radiation predicted total power generation amount to the unbalanced predicted total power generation amount before the prediction target time point. Method.   The method for predicting the amount of photovoltaic power generation according to claim 1 or 2, wherein the approximate function in the first step is derived from a normal phase current and a reverse phase current having a load fluctuation rate after sunset of a predetermined range or less. . Relational expression between the unbalance rate of the three-phase alternating current caused by the power generation of the solar power generator connected to the distribution system, and the positive and negative phase currents of the three-phase alternating current of the system during non-solar power generation Based on the approximate function and the current values of the positive and negative phase currents of the three-phase alternating current of the system at the prediction target time, the unbalanced predicted total power generation amount of the solar power generator connected to the system is calculated. A distribution system control system for operating the system,
Based on the amount of solar radiation during clear weather and the total rated power generation capacity of the solar power generator connected to the grid, the maximum value for calculating the predicted total amount of solar radiation, which is the total amount of power generated during clear weather of the solar power generator A calculation unit;
A correction formula deriving unit for deriving a correction formula based on a ratio of the solar radiation predicted total power generation amount to the unbalanced predicted total power generation amount before the prediction target time point;
A correction unit that corrects the unbalanced predicted total power generation amount based on the correction formula when the unbalanced predicted total power generation amount is equal to or greater than the solar radiation predicted total power generation amount;
A distribution system control system comprising: a switching control unit that operates the system based on the corrected unbalanced predicted total power generation amount. The distribution system control system further includes a relative ratio data table in which a ratio of the solar radiation predicted total power generation amount to the unbalanced predicted total power generation amount is stored every predetermined time,
The distribution system control system according to claim 4, wherein the correction formula deriving unit derives the correction formula with reference to the relative ratio data table.

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