JP2013099228A - Estimation method and device for power generation output of photovoltaic power generation facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate power generation output of a plurality of photovoltaic power generation facilities connected to an electric power system for every varying period component.SOLUTION: Measurement data on power generation output of photovoltaic power generation facilities at a predetermined representative spot is decomposed into varying period components. Data of the decomposed varying period components at the representative point and an introduction amount of the photovoltaic power generation facilities of the electric power system are input to a model expression of each varying period component for computing the reduction ratio of output variation smoothed through the composition of previously derived photovoltaic power generation output at the representative point and photovoltaic power generation output at another spot of the electric power system to compute photovoltaic power generation output of each varying period component.

Description

  The present invention relates to estimation of power generation output of a plurality of photovoltaic power generation facilities installed in a power system, and particularly estimates power generation output of a plurality of photovoltaic power generation facilities installed for each fluctuation period component of output fluctuation.

  In recent years, the introduction of solar power generation facilities that convert solar light energy into electric energy has increased due to environmental problems. Solar power generation is an inexhaustible solar power generation method, so it is expected to expand as a clean energy that does not emit carbon dioxide during power generation. Due to the high cost, solar power generation systems with a relatively small capacity of about several kW, such as installation on the roof of houses, are being introduced. In the future, intensive introduction to housing estates and planned introduction to the entire region are being promoted, and a substantial expansion is expected in the future.

In addition, since solar power generation facilities can generate power only with solar light energy, for example, there are few restrictions on installation locations such as wind power generation facilities that are biased to specific areas with favorable wind conditions. Small-scale photovoltaic power generation facilities are expected to be widely distributed.
However, because the power output of the solar power generation equipment is derived from the light energy of the sun, it is an unstable power source that fluctuates greatly depending on weather conditions. When viewed from the system side, the load to be supplied varies greatly depending on the power generation status of the photovoltaic power generation facility.

In response to such fluctuations in generated power, electric utilities respond to instantaneous fluctuations in power demand through supply and demand control that adjusts a generator having mechanical inertia, such as thermal power generation and hydroelectric power generation.
In the future, in the situation where a large number of photovoltaic power generation facilities have been introduced, for example, if the fluctuation in the power generation output of the photovoltaic power generation facilities becomes larger than expected due to sudden changes in the weather, There are concerns about the occurrence of various problems related to the stable supply of power, such as difficulty in handling control and deterioration of power quality such as voltage fluctuations in the power system.

In order to respond to these, it is important to know in advance how much photovoltaic power output there is in the entire power system or in the region, and how much photovoltaic power output fluctuation occurs. It becomes.
In order to grasp the photovoltaic power generation output, it is possible to grasp the total photovoltaic power generation output and its fluctuations by measuring all the power generation amount of the installed photovoltaic power generation equipment. It is not realistic to measure the power generation amount of all of the photovoltaic power generation facilities distributed and installed and to collect data by communication or the like.
For this reason, solar power generation output and its fluctuations are estimated, and various necessary measures on the power system side are drawn up based on these estimated power generation outputs, and these measures must reduce the effects of solar power generation facilities. I must.

Patent Documents 1 and 2 disclose techniques for estimating the output of a photovoltaic power generation facility linked to a power system.
In Patent Document 1, the estimation method of the maximum power generation output of one or a plurality of solar power generation facilities connected to the power distribution system, the power generation output and solar radiation data of the solar power generation facilities measured in advance in the model area, Calculate the coefficient from the installed capacity of the photovoltaic power generation facility, and calculate and estimate the maximum generated power output using the coefficient from the installed capacity of the photovoltaic power generation facility connected to the distribution system and the maximum amount of solar radiation within the forecast period. Is disclosed.

  Similarly, in Patent Document 2, the power generation output amount (rate) of another solar power generation facility installed in the same system as the predetermined solar power generation facility connected to the distribution system is measured, and the power generation amount of both is actually measured. It is disclosed that an approximate expression indicating a correlation between values is derived, and a power generation amount of the predetermined solar power generation facility is used to estimate a power generation amount of another solar power generation facility based on the derived approximate expression. Has been.

JP 2010-193594 A JP 2009-50064 A

  The conventional technology estimates the power generation output or the maximum power generation output of one or a plurality of photovoltaic power generation facilities connected to a power distribution system. However, as described above, it is not sufficient to estimate the power generation output or maximum power generation output of a photovoltaic power generation facility connected to the grid (connected) for power system operation and control. The fluctuations must be estimated accurately.

In other words, in order to balance the demand and supply capacity that fluctuates from time to time in the power system, generally in the supply and demand control, fluctuations in a fast cycle such as minute fluctuations are governor-free (GF). Absorbed by the governor operation of the generator, the difference between the demand and the supply power is detected as a frequency deviation for the short period fluctuation, and the supply power is adjusted by load frequency control (LFC). Further, for load fluctuations corresponding to long-period fluctuations, the supply power is adjusted by economic load dispatching control (ELD) in consideration of economy.
Therefore, in the power supply and demand control of the power system, it is necessary to ensure that the supply power that can be adjusted is secured as the supply and demand adjustment power according to the magnitude of the fluctuation period component, even for the output fluctuation of the photovoltaic power generation equipment. Don't be.
The present invention responds to the spread and expansion of the installation of photovoltaic power generation equipment in the future, and in a situation where a large number of photovoltaic power generation equipment is widely distributed and installed, the power output of the photovoltaic power generation equipment that varies depending on the weather Corresponding to the aspect of supply and demand control of the system, the power generation output is estimated and grasped for each fluctuation period component.

  The first technical means of the present invention is based on the actual measurement data of the photovoltaic power generation output at the representative point among the plurality of photovoltaic power generation points introduced into the power system, and the introduction amount of the photovoltaic power generation in the power system. In the solar power generation output estimation method for estimating the solar power generation output in the electric power system using the model formula acquired in advance, the solar power generation output data at the representative point is decomposed into predetermined fluctuation period components, and the predetermined power acquired in advance Using the model formula for each fluctuation period component that calculates the reduction ratio of fluctuations in the photovoltaic power output that is smoothed by the synthesis of the photovoltaic power output at a plurality of locations that are distributed at an average distance of A photovoltaic power generation output estimation method that calculates a photovoltaic power generation output in the power system for each fluctuation period component based on a component and the amount of photovoltaic power generation introduced in the power system.

  The second technical means is the photovoltaic power output estimation method according to the first technical means, wherein the model formula is the number of other solar power output points to be combined with the solar power output of the representative point and the reduction ratio. A first relational expression indicating the relationship between the two and the combination ratio, and a second relational expression indicating the influence of the distance between the combining points on the reduction ratio. Calculating the influence on the average distance between points to be calculated, and deriving the formula obtained by converting the number of points in the first formula into the amount of installed photovoltaic power generation equipment by correcting the influence calculated by the average distance. It is characterized by.

  According to a third technical means, in the photovoltaic power generation output estimating method of the second technical means, the model formula includes measured data of the photovoltaic power generation output at the representative point, and the data and the sun at a plurality of other introduction points. The combined data obtained by averaging the measured data of the photovoltaic power generation is decomposed into the variable periodic components, and the periodic components are compared for each decomposed periodic component by comparing the decomposed periodic components of the representative point data and the combined data. For each, the first relational expression indicating the relationship between the reduction ratio and the number of combined points is derived, and the measured data of the photovoltaic power generation output at the representative point and the photovoltaic power generation for each point to be combined with the data The combined data obtained by averaging the actual measured output data is decomposed into variable periodic components, and the representative point data and the combined data of the two points are separated for each decomposed periodic component. Are compared with each of the decomposed periodic components, and a second relational expression indicating the influence of the distance between the combined points on the fluctuation reduction ratio is derived for each periodic component and for each combined point. To calculate the influence on the average distance between the combined points.

  According to a fourth technical means, in the photovoltaic power generation output estimation method of any one of the first to third technical means, the fluctuation period component of the estimated power generation output is at least a governor-free (GF) in power supply and demand control. A periodic component corresponding to the control region, a periodic component corresponding to the load frequency control (LFC) region, and a periodic component corresponding to the economic load distribution control (ELD) region.

  The fifth technical means includes a periodic component decomposition unit that decomposes the photovoltaic power generation output data of the measured representative point into a predetermined fluctuation periodic component, a photovoltaic power generation introduction amount setting unit in the power system, and a decomposed cycle And a smoothing calculation unit that calculates, for each periodic component, a reduction in output fluctuation that is smoothed by synthesis of the photovoltaic power generation output based on the components and the amount of input set in the setting unit. It is characterized by a photovoltaic power generation output estimation device that estimates output for each fluctuation period component.

  A sixth technical means is the solar power generation output estimation device according to the fifth technical means, further comprising a periodic component synthesis unit that synthesizes the solar power output estimated for each of the fluctuation periodic components, and the solar power generation in the power system. The output is estimated.

  A seventh technical means is a program for causing a computer to execute the method according to claim 1.

  According to the present invention, the power generation output of a plurality of photovoltaic power generation facilities introduced into the power system is estimated for each variation period component corresponding to the supply and demand control mode in the power system based on the actual measurement data of the photovoltaic power generation facilities at a predetermined representative point. can do. It is also possible to estimate the amount of introduction of solar power generation facilities that can be connected to the power system.

Explanatory drawing of the representative observation point of a solar power generation facility. Explanatory drawing of the electric power generation output estimation method of this invention. Explanatory drawing of the observation point in derivation | leading-out of the electric power generation output estimation model type | formula of this invention. Explanatory drawing of the derivation | leading-out method of the electric power generation output estimation model formula in this invention. Explanatory drawing of the model formula based on the amount of installed solar power generation facilities. The figure which shows the dispersion | variation in the parameter | index for model model derivation | leading-out. Explanatory drawing of the correction | amendment which considered the distance of the model type | formula. Explanatory drawing of the estimation procedure of the electric power generation output in this invention. Explanatory drawing of the power generation output estimation of the whole supply area.

  The cause of fluctuations in the power generation output of the photovoltaic power generation equipment is a change in weather, but the mutual weather changes at the installation points of the respective photovoltaic power generation equipment distributed in a given area are correlated but not uniform. . Since the fluctuations in the power generation output of each photovoltaic power generation facility are not uniform, the output fluctuation is smoother than the fluctuation in the power generation output of each individual photovoltaic power generation facility when the power generation output of each of the photovoltaic power generation facilities installed in a distributed manner is combined Smoothing effect is obtained.

However, the tendency of weather changes between the installation points of each of the photovoltaic power generation facilities installed in a distributed manner varies depending on the location of the installation points of the respective solar power generation facilities and the distance between the installation points. It differs depending on the distribution situation of solar power generation site.
Furthermore, since the influence of the change in the weather on the fluctuation of the power generation output is not uniform, the smoothing effect for each output fluctuation period is also different.
In the present invention, as described above, the location of solar power generation, the influence of the distance between location points, etc. are corrected, and the power generation output is estimated for each fluctuation period component.

  FIG. 1 is a diagram for explaining an example of estimating solar power generation output distributed over a wide area in the Tohoku region as an example. In Fig. 1, the entire Tohoku region is divided into “all areas”, each prefecture is classified as “wide area”, municipalities are classified as “regions”, and one of the photovoltaic power generation facilities distributed in each area is represented by the area. It shows that it is set as the photovoltaic power generation equipment at the point.

FIG. 2 is a diagram showing a basic method of the present invention. The measured value data 1 of the photovoltaic power generation output at the representative point is acquired and inputted to the photovoltaic power generation output estimating apparatus 10. The input photovoltaic power generation output data of the representative point that fluctuates is decomposed into a predetermined fluctuation period component by the period component decomposition unit 11 and input to the smoothing calculation unit 12 for each period component. The introduction amount setting unit 14 is set with a photovoltaic power generation introduction amount 2 corresponding to the number of solar power generation introduction points in the power system.
The smoothing calculation unit 12 is connected to the system and synthesized based on the photovoltaic power generation introduction amount set in the introduction amount setting unit 14 and the measured data decomposed into the periodic components of the representative points decomposed in the periodic component decomposition unit 11. The fluctuation reduction ratio of the photovoltaic power generation output to be smoothed is calculated for each fluctuation period component, and the power generation estimation output 3 for each fluctuation period component is calculated and output.
The calculation in the smoothing calculation unit 12 is performed by a model formula 13 that calculates a reduction ratio of fluctuation for each fluctuation period component of the photovoltaic power generation output that is smoothed by the synthesis obtained in advance.
The periodic component synthesizing unit 15 synthesizes the power generation estimation output 3 for each fluctuation period component to calculate and output the solar power generation estimation output 4 in the power system.

3-7 is a figure explaining the said model type | formula, FIG. 3 has shown typically distribution of the photovoltaic power generation distributed in the certain area of FIG.
In deriving the model formula, first, representative points (points) in the region are determined. Representative points should be selected based on weather forecast classification and solar climate classification.
The photovoltaic power generation output at the selected representative point is measured, and as shown in FIG. 4, the measured power generation output data is decomposed into predetermined fluctuation period components to calculate data A to E.

In FIG. 4, the periodic component to be decomposed corresponds to a control mode for output fluctuations in the power system, and is a periodic component of 5 minutes or less (E in FIG. 4) corresponding to the control region of governor-free (GF), load frequency control (LFC). ) 5 to 20 minute period component (same D) corresponding to the region, 20 minute or more period component corresponding to the economic load distribution control (ELD) region, corresponding to the region corresponding to the automatic control in the supply and demand operation of the day Among the 20 to 90 minute periodic components (C) and 90 minute or more periodic components corresponding to the target area of the next day's supply and demand operation plan based on the demand assumption, a period of 480 minutes or more representing basic weather characteristics It is broken down into five components, the component (same A) and the other 90-480 minute periodic components (same B).
These five classifications are not essential, but at least a governor-free (GF) control area, a load frequency control (LFC) area, and an economic load distribution control (ELD) area are necessary.

The vertical axis of the figure showing the periodic components A to E in the figure indicates the ratio of the photovoltaic power generation output at the representative point to the rated output, and the horizontal axis is the time of the day.
The actual measurement data of the power generation output is obtained, for example, by measuring every 0.2 seconds and averaging in units of 1 second.
In decomposing into periodic components, for example, time-series power generation output data is subjected to Fourier transform and converted into frequency space output data, and a frequency component corresponding to the fluctuation period is extracted by a bandpass filter, and then subjected to inverse Fourier transform. As a result, the time-series data of the period can be calculated.

From the decomposed power generation output data, power generation output values and output fluctuation indices r _{1A to} r _1E for each periodic component are calculated. As the index r ₁ , a statistical value such as a standard deviation or a root mean square of the output value of the period and a maximum fluctuation range are appropriately selected and used.
Next, the average power generation output data obtained by sequentially selecting the solar power generation output at any point including the representative point and averaging the actual measurement data of the solar power generation output at 2 to N points (points) is as shown in FIG. In the same manner, each of the periodic components is decomposed, and an index r _{NA to} r _NE representing the output value and the magnitude of the output fluctuation is calculated for each decomposed periodic component.

Since the fluctuation of the power generation output obtained by combining the N-point solar power generation output is smoothed and the output fluctuation is reduced as described above, the correspondence between the fluctuation reduction ratio R ′ and the number of points N to be synthesized is decomposed by Equation 1. Calculate for each periodic component.
R ′ _N = r _N / r ₁ Formula 1

The illustrated experimental example uses data obtained by measuring the power generation output for one day from 4 o'clock to 20 o'clock for one month. However, depending on the purpose of estimating the power generation output, any desired time zone can be selected. R ′ may be calculated by dividing the data length.
In the experiment, it was calculated by selecting and observing 10 sites on the assumption that solar power generation facilities of approximately the same scale are distributed. Table 1 shows the variation reduction ratio R ′ for each calculated point number N and each calculated periodic component.

  Based on Table 1, an approximate curve is calculated using a least square method or the like, and a result of deriving a relational expression between the variation reduction ratio (R ′) for each decomposed periodic component and the number N of installation points (measurement points) is shown. It shows in Table 2.

There are various rated output solar power generation facilities installed on the roof of a house, etc., but on average, it can be regarded as a facility of almost the same scale, so as shown in FIG. N in the relational expression is converted into the introduction amount of solar power generation equipment (P = N × k), and Expression 2 is obtained.
R ′ = f (P) (2)

  In the experiment, assuming that 4 kW is a general rated output of the photovoltaic power generation equipment installed in a general house, N = P / 4, and the fluctuation reduction ratio R ′ with respect to the introduction amount P (kW) of the photovoltaic power generation equipment. The following relational expression was obtained as shown in Table 3.

FIG. 6 shows calculation data for one month of the fluctuation reduction ratio R ′ when N = 10 (P = 40 kW) as an experimental result, and there are variations depending on the day. Therefore, in calculating R ′ in Equation 2, statistical values such as a monthly average value and a maximum value are used.

  In addition, the correlation between fluctuations in power generation output due to daily weather changes is considered to differ depending on the distance between measurement points for each solar power output. .

As shown in FIG. 7, the correction method similarly decomposes the photovoltaic power generation output at the representative point into fluctuation period components, and calculates fluctuation indices r _{1A to} r _1E of the respective period components. Next, for the point that combines the photovoltaic power generation output that is separated from the representative point by xkm, the average power generation output data obtained by averaging the actual measurement data of the representative point with the actual measurement data of other points (points) to be combined for each point is used as the fluctuation cycle component. decomposing, calculating a fluctuation index _r 2AX _{~r 2EX} of each periodic component, the variation reduction ratio R _"x corresponding to the distance between two points for each point is obtained by equation 3.
_{R "x = r 1 / r} 2x ··· Formula 3
In addition, the display which shows each periodic component in FIG. 7 is the same as the example of FIG.

  Table 4 shows the experimental results showing the fluctuation reduction ratio corresponding to the distance between the combined points of the photovoltaic power generation output for each periodic component.

  From the data in Table 4, calculate the approximate straight line or curve using the least squares method for the relationship between the distance between the two points and the fluctuation reduction ratio indicating the degree of smoothing of the photovoltaic power generation output value and output fluctuation. Then, a relational expression between the point-to-point distance x (km) and the fluctuation reduction ratio R ″ in each periodic component is derived as shown in Table 5.

Based on this relational expression, introduction of photovoltaic power generation using the fluctuation reduction ratio R ″ (x0) at the average point-to-point distance x0 (km) of each photovoltaic power generation facility installed in the assumed area of the municipal level range By correcting the relationship of the fluctuation reduction ratio R with respect to the amount P, the following expression 4 is calculated in consideration of the output value of the photovoltaic power generation facility according to the distance between points and the smoothing degree of the output fluctuation.
R = R ′ / R ″ (x0) = f (P) / R ″ (x0) Equation 4

  In the experimental results, an average point-to-point distance x0 (km) in the assumed area is assumed to be 10 (km), and a model of the fluctuation reduction ratio is obtained as follows.

FIG. 8 illustrates the estimation method of the present invention. The representative point actual measurement data 1 is decomposed into periodic components as shown in the figure by the periodic component decomposition unit 11 and input to the smoothing calculation unit 12. Further, the amount of photovoltaic power generation introduction 2 of the system set in the introduction amount setting unit 14 is input, and the power generation output 3 is estimated and output for each variation period component in the system by the model expression 13 for each period component shown in Expression 4. To do. Further, the estimated output 3 for each fluctuation cycle component is synthesized by the cycle component synthesis unit 15 to estimate the photovoltaic power generation output of the system.
The display of the periodic component in FIG. 8 is also the same as in the example of FIG. 4, and the vertical axis indicates the ratio to the rated output of the photovoltaic power generation facility.

Since the photovoltaic power generation output installed in the regional grid is linked to a wider area and the entire area via the higher-level grid, the power generation output for each fluctuation period component estimated for each area as shown in FIG. It is possible to estimate the photovoltaic power generation output 6 in the entire supply area by adding the solar power generation output 5 in a wide area and further adding the totals in consideration of constants related to losses in the system.
In the above, the estimation of the power generation output for each output fluctuation period of the photovoltaic power generation equipment introduced (installed) in the region has been described. Since the photovoltaic power generation output for each fluctuation period can be estimated based on the introduction amount expected to be installed every time, it is possible to accurately take necessary measures in advance in the power system.
Furthermore, it is also possible to estimate the amount of solar power generation equipment that can be connected according to the power supply and demand adjustment capability of the power system.

DESCRIPTION OF SYMBOLS 1 ... Output measurement data of the photovoltaic power generation equipment of a representative point, 2 ... Introduction amount of photovoltaic power generation, 3 ... Estimated value of photovoltaic power generation output for every fluctuation period component, 4 ... Estimated value of photovoltaic power generation output, 10 ... Photovoltaic power generation output estimation device, 11 ... periodic component decomposition unit, 12 ... smoothing calculation unit, 13 ... model formula, 14 ... introduction amount setting unit, 15 ... periodic component synthesis unit, 4a-n ... solar power generation output in the area 5a to m ... Estimated value of photovoltaic power generation output in a wide area, 6 ... Estimated value of photovoltaic power generation output in the entire area.

Claims (7)

Based on the measured data of the photovoltaic power generation output at the representative point among the plurality of photovoltaic power generation points introduced into the power system and the amount of photovoltaic power generation introduced in the power system, using the model formula obtained in advance In the solar power output estimation method for estimating the solar power output in the grid,
Photovoltaic power output that is obtained by decomposing the solar power output data of the representative point into predetermined fluctuation period components and smoothing it by synthesizing the solar power output at a plurality of points that are dispersed and located at a predetermined average distance. Using the model formula for each fluctuation period component that calculates the fluctuation reduction ratio of the fluctuation, the photovoltaic power generation output in the power system is fluctuated based on each decomposed periodic component and the amount of photovoltaic power generation introduced in the power system A photovoltaic power generation output estimation method characterized by calculating for each periodic component.   The model formula derives a first relational expression indicating the relationship between the number of other solar power output points to be combined with the solar power output at the representative point and the reduction ratio, and further, between the points to be combined A second relational expression indicating the influence of the distance of the distance on the reduction ratio is derived, and the influence on the average distance between the combined points is calculated by the second relational expression, and the ground of the first expression is calculated. The photovoltaic power generation output estimation method according to claim 1, wherein a formula obtained by converting the number of points into the amount of installed solar power generation equipment is corrected and derived by the influence calculated by the average distance.   The model formula decomposes the measured data of the photovoltaic power generation output at the representative point, and the combined data obtained by averaging the data and the measured data of the photovoltaic power generation output at a plurality of other introduction points into the fluctuation period components, respectively. The first relational expression showing the relationship between the reduction ratio and the number of synthesized points for each periodic component by comparing the decomposed periodic components of the representative point and the synthesized data for each decomposed periodic component And further decomposing the synthesized data obtained by averaging the measured data of the photovoltaic power generation output at the representative point and the measured data of the photovoltaic power generation output for each point to be combined into the fluctuation period component, For each periodic component, the data of the representative point and the decomposed periodic component of the combined data of the two points are compared, and each periodic component is synthesized. A second relational expression indicating the influence of the distance between the combined points on the fluctuation reduction ratio is derived for each point, and the influence on the average distance between the combined points is calculated by the second relational expression. The solar power generation output estimation method according to claim 2.   The fluctuation period component of the power generation output to be estimated includes at least a periodic component corresponding to a governor-free (GF) control region in power supply and demand control, a periodic component corresponding to a load frequency control (LFC) region, and economic load distribution control ( The photovoltaic power generation output estimation method according to any one of claims 1 to 3, further comprising a periodic component corresponding to an ELD) region.   A periodic component decomposition unit that decomposes the measured photovoltaic power generation output data of the representative point into predetermined fluctuation periodic components, an introduction amount setting unit for photovoltaic power generation in the power system, and a decomposed periodic component and setting in the setting unit A smoothing calculation unit that calculates, for each periodic component, a reduction in output fluctuation that is smoothed by synthesizing the photovoltaic power generation based on the added amount, and for each fluctuation periodic component A photovoltaic power generation output estimation device characterized by estimating.   The photovoltaic power generation output estimation apparatus according to claim 5, further comprising a periodic component synthesis unit that synthesizes the photovoltaic power generation output estimated for each fluctuation periodic component, and estimates the photovoltaic power generation output in the power system. .   The program for making a computer perform the method in any one of Claims 1-4.

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