JP7020962B2 - Measurement correction device and measurement correction method - Google Patents

Description

The present invention relates to a measurement correction device and a measurement correction method, and is particularly suitable for application to a measurement correction device that corrects a measured value of an electric power system.

Conventionally, there has been a technique for performing measurement in a power system, particularly a plurality of switches distributed and arranged in a power distribution system, while synchronizing at the same timing (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-39375

In the above-mentioned prior art, since a device for generating a synchronization signal and superimposing it on the power line or a device for receiving the synchronization signal superimposed on the power line is used, it is necessary to add a device related to the above-mentioned synchronization function. Therefore, the equipment currently generally used (hereinafter referred to as "current organic device") cannot be used as it is. On the other hand, it may take a considerable long time to renew many of the current organic devices, and a responsive means has been desired.

The present invention has been made in consideration of the above points, and it is possible to carry out a correction for reducing the measurement error due to the deviation of the measurement time without adding hardware or software to the current organic device of the power system. We are trying to propose a measurement correction device and a measurement correction method that can be performed.

In order to solve such a problem, in the present invention, a first measuring unit that measures an apparent current or an amount of electricity that can be converted into an apparent power at a specific location in the power system in a relatively short cycle, and a change in the apparent current. A detection unit that detects the difference in the amount of change in the voltage drop with respect to the above, and a second measurement unit that measures in a relatively long cycle at a predetermined location under the specific location according to the difference in the amount of change in the voltage drop. Determination of the presence or absence of correlation used in the calculation method switching unit and the calculation method switching unit that switches the method that approximates the value measured by the second measurement unit to the value measured with a resolution of relatively long period or less. It is characterized by including a correction unit for correcting the value measured by the second measurement unit based on the above.

Further, in the present invention, the first measurement step of measuring the apparent current or the amount of electricity that can be converted into the apparent power at a specific point of the power system in a relatively short cycle, and the change of the voltage drop with respect to the change of the apparent current. A detection step for detecting a difference in quantity, a second measurement step for measuring at a predetermined location under the specific location in a relatively long cycle according to the difference in the amount of change in the voltage drop, and the second measurement. The second measurement unit using the calculation method switching step of switching the method of switching the method of approximating the value measured in the step to the value measured with the resolution of the relatively long cycle or less and the method switched in the calculation method switching step. It is characterized by having a correction step for correcting the value measured by.

According to the present invention, it is possible to carry out a correction for reducing the measurement error due to the deviation of the measurement time without adding hardware or software to the current organic device of the power system.

It is a figure which shows the configuration example of the electric power system to which the measurement correction apparatus by this embodiment is applied. It is a figure which shows an example of the flow of the measured value using the measurement correction method by this embodiment. It is a sequence chart which shows an example of the data collection method by the sequential polling. It is a figure which shows an example of the deviation of the measured value by the long-period measurement when there is no photovoltaic power generation (PV) interconnection. It is a figure which shows an example of the deviation of the measured value by the long-period measurement when there is PV interconnection. It is a figure which shows an example of the deviation of the measured value due to the deviation of the time within the measurement time of a long period. It is a figure which shows an example of the relationship between the fluctuation of a tidal current by PV and superficial electric power. It is a figure which shows an example of the relationship between the apparent power at the time of a light load, and the amount of voltage drop. It is a figure which shows an example of the relationship between the apparent power and the amount of voltage drop when it is not a light load. It is a block diagram which shows the functional configuration example which concerns on this embodiment. It is a flowchart which shows an example of the judgment-related processing. It is a sequence chart of the correction method which does not use the apparent power. It is a figure which shows an example of the processing of the correction method which does not use the apparent power. It is a figure which shows an example of the application result of the correction method which does not use the apparent power. It is a figure which shows an example of the application result of the correction method using superficial power.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(1) Configuration of the system according to the present embodiment FIG. 1 is a diagram showing a configuration example of a power system to which the measurement correction device according to the present embodiment is applied. As a main flow of the power system, the electric power generated in the power plant 101 is transmitted to the distribution line 105 via the transmission line 104 and the distribution substation 102 of several voltage classes. Of these, the amount of electricity is measured by some switches 200 and the like. Further, the electric power system is interconnected with loads such as a large consumer 106 and a small consumer 107, and a distributed power source such as a photovoltaic power generation device (hereinafter, also abbreviated as “PV”) 110.

FIG. 2 is a sequence chart showing an example of a flow of measured values of electric energy in an electric power system. The substation installation measuring device 210 collects the measurement results of the electric energy of the distribution system including the sending point of the distribution substation 102. Similarly, the substation installation measuring device 210 carries out the measurement process 211 for measuring the measurement data of the substation sending point in a short cycle. On the other hand, for example, the measurement data from the switches 2001, 2002, ..., 200n installed on the utility poles are collected in a long cycle via a communication line or the like.

(2) Regarding the timing of data collection
FIG. 3 is a system diagram shown in FIG. 2 and a timing chart serially showing the timing of data collection. FIG. 3 (A) represents the system diagram shown in FIG. 2, and FIG. 3 (B) represents a sequence chart related to the collection of measurement data.

In FIG. 3B, the substation installation measuring device 210 is defined as a “parent (also referred to as a“ master station ”)” according to its role in communication, while the switch (slave station) 200 described above is a “child”. (Also called "slave station") ". Here, on the master station 210 side, the amount of electricity at the transmission point of the substation is measured and collected in a short cycle. In the following description, when a plurality of slave stations 200 appear, the first slave station is assigned a code of 2001 and the second slave station is referred to as 2002 in order to distinguish each slave station 200 from each other. A code may be assigned, and a code of 200n may be assigned to the nth slave station. In addition, each of these slave stations 2001, 2002, ..., 200n shall be abbreviated as "child 1", "child 2", ..., "child n" in each drawing. ..

The short cycle refers to a short cycle such as, for example, in seconds. The above measurement can be performed in a short cycle because it is within the own station and there is no or slight communication load. The amount of electricity to be collected includes, for example, an apparent current (| I |), a voltage (V), and the like. It may be active power (P) or active power (Q), but it is not always measured at all points. Therefore, as the minimum common electric energy, the electric energy that can be converted (converted) into either the apparent current (| I |), the voltage (V), or both is used.

(3) Sequence for collecting measured values from the switch Next, a sequence for collecting measured values from the switch 200 will be described. The collection of measured values from the switch 200 is individually collected from the master station 210 for each switch 200 (first slave station 2001, second slave station 2002, ..., nth slave station 200n). It is carried out by polling.

For example, the master station 210 issues a telegram requesting a measured value to the first slave station 2001. Upon receiving the telegram, the first slave station 2001 performs measurement or transmits the latest measured value as a response message to the master station 210.

As a result, the master station 210 sequentially carries out the above-mentioned series of request and response message exchanges for all the target slave stations 2001, 2002, ..., 200n. Generally, the number of slave stations under a certain master station 210 is large. Therefore, from the time of polling start (mark S shown in FIG. 3: meaning of measurement start) to the first slave station 2001 (corresponding to the child 1 in the figure) which is the first slave station, the last slave station is the first slave station. Until the end of polling to the slave station 200n (corresponding to the child n in the figure) (mark E: meaning end in FIG. 3), there is a certain amount of time (the child time is Δt). Define).

The above-mentioned deviation of the measurement time cannot be avoided by the method of measuring by sequential polling even if the slave station does not use a synchronization mechanism such as a real-time clock or a GPS (Global Positioning System) receiver.

In FIG. 3B, the long-period measurement process 212 is described for only one cycle, but in reality, it is repeated for a plurality of cycles, for example, in a cycle of 1 hour or 15 minutes. The same applies to the measurement process 211 in a short cycle by the master station 210, and the measurement is repeated in a cycle such as seconds. The above measurement results are appropriately transmitted to the upper control system.

Next, regarding the effect of the deviation of the measurement time due to long-period measurement on the measured value, in the case of a system without interconnection with PV110 (hereinafter referred to as "PV interconnection") and in the case of a system with PV interconnection. It will be explained separately.

FIG. 4 schematically shows the deviation of the measured values due to the long-period measurement when there is no PV interconnection. The mark S in the figure indicates the start time of the measurement by the master station 210 in a long period, and is, for example, the time when the master station 210 starts polling to the first slave station 2001 which is the first. On the other hand, the mark E in the figure indicates the end time of the long-period measurement by the master station 210, which is the time when the master station 210 finishes polling the last nth slave station 200n.

In order to simplify the explanation, the time difference between the transmission of the measurement value request in the master station 210 and the acquisition of the measurement value in the second slave stations 2001, 2002, ..., 200n, and the reception of the measurement value response and the second The time difference from the measurement of the slave station 200n of n is ignored and shown in the figure.

In a system without PV interconnection, the amount of fluctuation in load per hour is relatively small. Therefore, the amount of change in the tidal current value ( _ΔPL ) due to the timing difference (Δt) between the marks S and E is negligible. Therefore, in the general power system before the introduction of PV110 as a comparative example, the error caused by the difference in measurement time was negligible in the sequential polling method.

On the other hand, FIG. 5 schematically shows the deviation of the measured values due to the long-period measurement when there is PV interconnection in the present embodiment. The marked S and E in the figure indicate the start time and the end time of the long-period measurement, respectively, as described above.

When there is PV interconnection, the tidal current changes in a range that is significantly larger than the rated value of the system. This is because the load fluctuations occur in a timely manner except at the start of work or after noon, whereas the output fluctuations of the PV110 are the same as the rated values of the PV110 according to the amount of solar radiation. This is because it fluctuates in a range of degrees.

Therefore, the measured value of the electric energy at the time of the mark S shown in FIG. 5 and the measured value at the time of the mark E, which should be separated by only Δt, may be significantly different. Therefore, the difference in measured values (ΔP _PV ) within the long-period measurement cycle becomes so large that it cannot be ignored. In FIGS. 4 and 5, P and Q are used as an example of the amount of electricity, but in the sense of magnitude of fluctuation, the same applies to the use of apparent current (or apparent power).

6 (A) corresponds to the system diagram shown in FIGS. 2 and 3 (A), and FIGS. 6 (B) and 6 (C) show the times within the long-period measurement time, respectively. The distribution of the deviation of the measured value due to the deviation is schematically shown. In the illustrated example, the voltage drop amount Vd from the substation sending point is used as an example of the amount of electricity to be measured.

In the illustrated example, the deviation of the measured values within the same measurement cycle (within Δt) is shown. FIG. 6B shows an example in the case where there is no PV interconnection, and FIG. 6C shows an example in the case where there is PV interconnection.

In FIG. 6B (when there is no PV interconnection), the difference between the measured values whose measurement times are shifted by the maximum Δt is negligible. On the other hand, in FIG. 6C (when there is PV interconnection), the deviation of the measured value due to the deviation of the measurement time becomes relatively large. In FIGS. 6B and 6C, the vertical axis indicates the voltage drop amount Vd, and the horizontal axis indicates the distance from the distribution substation 102.

This indicates that it will be one of the measured values that varies as shown in the figure for each switch 200. Therefore, the measured values in the PV interconnection system are difficult to use in applications such as estimating the tidal current by comparing the measured values in the same measurement cycle relatively.

As described above, in the case of PV interconnection, the deviation of the measured value due to the deviation of the measurement time in the measured value of the general method collected by the sequential polling reduces the utility value of the data.

Therefore, in the present embodiment, at least a part of the method for correcting the error of the measured value due to the deviation of the measured time will be described. Here, attention is paid to the measurement process 211 in the short cycle shown in FIGS. 2 and 3.

The measurement process 211 in the short cycle is data obtained by measuring the apparent current (| I |) and the voltage (V) at the transmission point of the substation in a short cycle such as in seconds. The reason for paying attention to the measurement process 211 in the short cycle is that it is more convenient to be able to correct the deviation of the measurement time in real time, and the range of utilization is wide including the operation management of the system.

However, there are problems in utilizing the apparent current (| I |). This is because the conversion from the apparent current to the voltage drop amount Vd cannot always be performed directly. On the other hand, for example, when active power (P) or reactive power (Q) can be used, it can be directly linked to the voltage drop amount (Vd). For example, the amount of voltage drop can be expressed by using the equation Vd = (RP + XQ) / V, and the variables R and X represent the impedance of the system up to the point.

However, since the short-period measurement data that can be used this time is the apparent current (hereinafter, converted to apparent power by (√3) V | I |), some measures are required to use the apparent power. be.

Before considering such measures, examine the relationship between apparent power and voltage drop. The assumptions are as follows. It is assumed that the master station measures the apparent current (| I |) and the voltage (V) at the transmission point of the substation in a short cycle such as in seconds.

Further, by polling from the master station 210, the values measured by the switch 2001 and the like are sequentially acquired via the slave station 2001. The measured values in the switch 2001 are apparent current (| I |) and voltage.

Further, it is assumed that the cycle for measuring all the slave stations 2001, 2002, ..., 200n is, for example, one hour or 30 minutes, which is much longer than the measurement cycle in the master station 201. Hereinafter, the apparent current shall be converted into, for example, apparent power for use.

FIG. 7 shows the relationship between the fluctuation of the output fluctuation mode (hereinafter referred to as “tidal current”) of PV110 and the apparent power and the relationship of the voltage drop amount with respect to the fluctuation of the tidal current when there is PV interconnection. In FIG. 7, the vertical axis represents Q, the horizontal axis represents P, and the illustrated plane is also referred to as a “PQ plane”.

In the illustrated example, the characteristic A is the locus of the tidal current when it is assumed that only the loads of the large consumer 106 and the small consumer 107 are interconnected in the load characteristic. When the power factor is good, the slope of the characteristic A becomes gentler. The characteristics B and C shown by the dashed double-headed arrows are the trajectories when the output fluctuations of PV110 are superimposed, respectively. It corresponds to the case where there are many loads and the load is large to some extent.

Further, the tidal current corresponding to a certain apparent power value becomes concentric circles based on S ² = P ² + Q ² as in the characteristic D. The characteristic G shown by each two-dot chain line represents the drop mode of the voltage drop amount Vd in a contour line (hereinafter referred to as “contour line G”). The voltage of each contour line G shown by the two-dot chain line decreases from the lower left to the upper right in the figure.

The regions E and F represent regions in which the apparent power is not sensitive to changes in the tidal current, and the locus of the output fluctuation of the PV 110 is in the tangential direction of the concentric circles. Next, how to determine the areas E and F will be described. First, a straight line that passes through the origin and is orthogonal to the slope of the output fluctuation of PV110 is drawn. Next, draw two straight lines that also pass through the origin and are rotated by the same positive and negative angles with respect to this straight line. The range surrounded by these two straight lines is the area E and the area F.

Here, it is assumed that the tidal current follows the trajectory as shown in the characteristic B. At this time, the change direction of the concentric locus is a substantially tangential direction of the concentric circles, and the fluctuation of the apparent power is small. On the other hand, since the locus of the characteristic B is not parallel to the contour line G, the voltage drop amount Vd fluctuates.

The above contents show the condition that the voltage drop amount Vd cannot be calculated from the apparent power. This region is the range of characteristic E and characteristic F. On the other hand, when the locus of the tidal current is characteristic C, the locus of characteristic C changes in the substantially radial direction of concentric circles, and when the tidal current fluctuates, the apparent power also fluctuates, and the voltage drop amount Vd also fluctuates. Become. Therefore, under the latter condition), there is a possibility that the voltage drop amount Vd can be calculated from the apparent power.

Therefore, in the present embodiment, the relationship between the apparent power and the voltage drop amount Vd is verified by using the tidal current data in the actual system. In this verification, the voltage drop amount Vd is calculated by multiplying the power flow value (P, Q) at the transmission point of the distribution substation 102 by the impedance of the system.

FIG. 8 shows the relationship between the apparent power and the voltage drop amount Vd under the condition that the locus of the tidal current is in the range F (light load), and FIG. 9 shows the apparent power and the voltage drop amount Vd other than the characteristics E and F. Shows the relationship with.

Under the condition that the locus of the tidal current is in the range F (light load), as discussed with reference to FIG. 7, there is almost no sensitivity of the apparent power to the voltage drop amount Vd. That is, the correlation between the apparent power and the voltage drop amount Vd is small. Therefore, under the above conditions, the apparent power cannot be used to correct the measured value due to the deviation of the measured time for each switch, and another means (described later) is used.

On the other hand, under conditions other than light load (when the tidal current is in a range other than the characteristics E and F), as in the discussion using FIG. 7, there is the sensitivity of the apparent power to the voltage drop amount Vd.

That is, under the above conditions, there is a correlation between the apparent power and the voltage drop amount Vd. Therefore, it can be seen that the apparent power can be used to correct the measured value due to the deviation of the measured time for each switch 2001 or the like.

From the above, it can be seen that one of the factors that determines the presence or absence of the correlation between the apparent power and the voltage drop amount Vd is the amount of load such as the large-scale consumer 106 and the small-scale consumer 107. Since the amount of load has different characteristics on a daily basis such as weekdays and holidays, it is highly convenient to use it for judgment.

Based on the above findings, in the present embodiment, the apparent power is used when correcting the measured value due to the deviation of the measurement time for each switch based on the presence or absence of the correlation between the apparent power and the voltage drop amount Vd. , Switch between methods that do not use apparent power.

Hereinafter, this embodiment will be described with reference to functional blocks. FIG. 10 is a functional block diagram showing a functional configuration example of the measurement correction device according to the present embodiment. This measurement correction device is installed in, for example, a distribution substation or an electric station that plays a role of collecting data measured by a switch. The measurement correction device may be installed in any place, not limited to the above-mentioned place, as long as it is connected via a low-delay and high-speed communication path.

The measurement correction device according to the present embodiment uses the input / output unit 322, the master station time holding unit 340, the correlation presence / absence determination unit 325, the calculation method switching unit 330, the integrated control unit 320, the measured value storage unit 323, and the apparent current. It is provided with the correction unit 331, the correction unit 332 that does not use the apparent current, and the polling control unit 321. On the other hand, each of the first slave station 2001 to the nth slave station 200n includes a slave station time holding unit 341.

The input / output unit 322 is an I / O device that communicates with the outside, and is mainly composed of a communication interface or the like. A console such as an operation console may be included.

The measurement value storage unit 323 stores measurement data and various settings from the subordinate switch slave stations.

The polling control unit 321 executes anomalous polling addressed to a specific slave station for sequential calling or correction without using the apparent current, which will be described later, when collecting measurement data from the subordinate switch slave stations. do.

The correlation presence / absence determination unit 325 has a function of determining the presence / absence of a correlation between the apparent current and the voltage drop amount (change amount of the voltage drop) (hereinafter referred to as “correlation presence / absence determination function”).

The calculation method switching unit 330 changes the measured values measured at each slave station 2001, 2002, ..., 200n according to the determination result of the correlation presence / absence determination function, for example, with a resolution of a relatively long cycle or less. Switch the calculation method that approximates the measured value (voltage drop).

The correction unit 331 using the apparent current has a function of correcting the voltage drop amount Vd by using the apparent current, and the measurement time between the switch slave stations is measured by using the apparent current measured in a short cycle by the master station. Correct the deviation of the measured value due to the deviation of.

The correction unit 332 that does not use the apparent current has a function of correcting the voltage drop amount Vd without using the apparent current, that is, it is due to the deviation of the measurement time between the switch slave stations by using the method described later without using the apparent current. It has a function to correct the deviation of the measured value.

The integrated control unit 320 comprehensively controls each of the above-mentioned functions. Specifically, the integrated control unit 320 is composed of a CPU that is an execution subject of operations and various processes, a scheduler that manages tasks, an OS, and the like.

The master station time holding unit 340 and the slave station time holding unit 341 have a function of holding the time in the master station 210 and each slave station 2001 to 200n, respectively, and specifically, tick the time like a real-time clock or the like. It also has a calendar function to hold the date.

The master station time holding unit 340 and the slave station time holding unit 341 are not indispensable configurations. These are shown in order to explicitly show that the times of the master station 210 and the slave stations 2001 to 200n are not synchronized. For example, if the slave stations 2001 to 200n have a function of responding to the measured value in response to the request of the master station 210, it is not always necessary to hold the time and the calendar.

Next, the correlation presence / absence determination unit 325, which is a characteristic configuration in the present embodiment, will be described. The correlation presence / absence determination unit 325 has a function of determining the presence / absence of a correlation between the apparent current and the voltage drop amount. It is determined whether or not there is a correlation between the apparent current and the voltage drop amount Vd.

The correlation presence / absence determination unit 325 determines that there is no correlation between the apparent current and the voltage drop amount Vd when the fluctuation range of the tidal current is mainly in the regions E and F shown in FIG. On the other hand, in cases other than the above, the correlation presence / absence determination unit 325 determines that there is a correlation between the apparent current and the voltage drop amount Vd.

The correlation presence / absence determination unit 325 may statistically calculate and determine the relationship between the past apparent current stored in the measured value storage unit 323 and the voltage drop amount Vd as the determination basis. Alternatively, the correlation presence / absence determination unit 325 may determine this according to the type such as weekdays or holidays. In any case, the correlation presence / absence determination unit 325 may determine by applying the determination basis shown in FIG. 7, for example, using the load status (P, Q) obtained from the upper system control system. ..

FIG. 11 shows an example of the correction process. First, in step S461, the correlation presence / absence determination unit 325 confirms whether or not there is a correlation between the apparent current and the voltage drop amount Vd. In step S462, the calculation method switching unit 330 selects the correction method according to the presence or absence of the correlation determined by the correlation presence / absence determination unit 325.

If it is determined that there is a correlation, the calculation method switching unit 330 executes step S463 in order to select a correction method using the apparent current. In step S463, the correction unit 331 using the apparent current applies the correction method using the apparent current to perform the correction. This step corresponds to a functional block.

On the other hand, when it is determined that there is no correlation, the calculation method switching unit 330 executes step S464 to select a correction method that does not use the apparent current. In this step S464, the correction unit 332 that does not use the apparent current applies the correction method that does not use the apparent current to execute the correction.

This determination process may be performed on a daily basis, for example. A case where the execution of the determination process on a daily basis is sufficient is a case where the region of the fluctuation range of the tidal current based on the determination basis shown in FIG. 7 changes on a daily basis. Specifically, if the fluctuation range of the tidal current can be determined approximately on a daily basis between the days when the tidal current does not enter the region E and the region F and the days when the tidal current fluctuates, the determination process can be executed on a daily basis. ..

More specifically, when a day with a light load such as a holiday or a weekend falls into the area F shown in FIG. 7, a day with a heavy load such as a weekday can be regarded as hardly entering the area E or the area F. , Daily judgment can be applied. If the conditions of the capacity of the system and PV are met, the above switching may be performed on weekdays or holidays as a simple method.

Further, when applying the present embodiment, it is not necessary to actually draw the figure corresponding to FIG. 7. This is because the relationship between the apparent power and the voltage drop amount Vd can be understood from the information on P and Q in the higher system in addition to the analysis of the past data. Further, when another system has a PV output estimation function, it is often the case that information on the load characteristics (characteristic A shown in FIG. 7) and the PV rating has already been obtained. If the information possessed by the above-mentioned other system is used in the system to which the above-mentioned correction method is applied, the convenience can be expected to be improved.

Next, the function of correcting the voltage drop amount Vd using the apparent current by the correction unit 331 using the apparent current and the function of correcting the voltage drop amount Vd using the apparent current by the correction unit 332 not using the apparent current will be described. do.

In the correction method (of the voltage drop amount Vd) using the apparent current by the correction unit 331, although detailed description is omitted, the relationship shown in FIG. 9, for example, an approximate curve (including a straight line) may be used. In such a correction method, since the amount of deviation of the measured value due to the time deviation may be relatively obtained, for example, the correction may be performed using only the slope of the straight line.

Next, a method for correcting the voltage drop amount Vd without using the apparent current will be described. When the apparent current (or apparent power) is not used, the amount of electricity measured in a short cycle at the sending point of the distribution substation 102 cannot be used. Therefore, as an example, the correction unit 332 that does not use the apparent current can use the methods shown in FIGS. 12 and 13 described later. In this method, a switch is used as a target node to measure multiple times within the measurement cycle, and the difference between the measured values is internally and externally inserted.

FIG. 12 shows an example of a communication sequence when a correction method that does not use apparent power is adopted. In the illustrated example, the switch first slave station 2001 is defined as a pilot node, while the switch second slave station 2002 is defined as a target node.

The measurement process 543 is a measurement process relating to the first pilot node, the measurement process 544 is a measurement process relating to the target node, and the measurement process 545 is a measurement process relating to the second pilot node. The measurement time of each of the measurement processes 543, 544, 545 is t1, t2, t3.

FIG. 13 shows an example of a correction method that does not use apparent power. The voltage drop amount Vd corresponds to the voltage difference to each node (switch) with respect to the sending point of the substation 102 as described above.

Each of the reference numerals of these measurement processes 543, 544, 545 corresponds to the measurement process in the sequence shown in FIG. Here, the correction value Vd2 for correcting the measured value at the measurement time t2 of the target node to the value at the time t1 of the target node by using the difference Vd1 of the measured values of the pilot node is Vd2≈Vd1 * (C1). * Indicated by (C2).

By correcting the measured value in the measurement process 545 with the correction value Vd2, the target node correction result 546 can be obtained. Although it is a value that cannot be actually measured, there is also an ideal value 547 of the target node.

The coefficient C1 is the ratio of the voltage fluctuation amount of the pilot node to the voltage fluctuation amount of the target node. When the active power (P) and the active power (Q) are known, the ratio of the system impedance and the voltage drop due to the power flow can be easily calculated, but in the case of this embodiment, only the apparent power is known. Further, the correction unit 332 that does not use the apparent current is used on the premise that there is at least no apparent power sensitivity. Therefore, the ratio of the voltage fluctuation amount of each node is used. The past data accumulated in the measured value storage unit 323 can be used to calculate the ratio of the voltage fluctuation amount of the node.

Here, the ratio of the voltage fluctuation amount cannot be expected to be a value close to a constant value under general conditions without any particular restriction. However, under the condition that the correction unit 332 that does not use the apparent current should be operated, it can be expected that the value will be close to a certain level. This is because the condition for applying the correction unit 332 that does not use the apparent current is a day with a light load such as a holiday or a weekend, and the target for applying the correction unit 332 that does not use the apparent current is a short time. This is because the conditions can be narrowed down because it is the correction of the voltage fluctuation due to the output fluctuation of the PV. On the other hand, the variable C2 described above indicates the ratio of the measurement time differences, and is represented by C2 = (t2-t1) / (t3-t1).

FIG. 14 shows an example of the application result of the correction method that does not use apparent power. This result was obtained by calculating the voltage drop amount Vd using the tidal current measurement data in the actual system. FIG. 14A shows an example in the case where the correction is not performed. The horizontal axis of FIG. 14A is the correct value at time t1 of the target node (ideal value 547 in FIG. 13). Similarly, the vertical axis is the value at time t2 of the target node (measured value 545 in FIG. 13).

FIG. 14B shows an example of the case where the correction is performed. The horizontal axis of FIG. 14 (B) is the correct value at the measurement time t1 of the target node (value 547 of FIG. 13) as in FIG. 14 (A), and the vertical axis is the target corrected with the value of the target node at time t2. It is an estimated value at time t1 of the node (value 546 in FIG. 13). The closer the shape of the distribution is to the straight line with the slope 1 (the thinner it is), the closer it is to the ideal value. Compared with the distribution shown in FIG. 14 (A), the distribution shown in FIG. 14 (B) is narrower, and it can be seen that the correction effect is obtained. In the present embodiment, the error can be reduced by about 30% as compared with the case where the correction is not performed.

FIG. 15 is an example of the application result of the correction method using apparent power. The vertical axis of the figure is the amount of voltage drop Vd from the substation sending point, and the horizontal axis is the time T with a full span of about 20 minutes. Here, the illustrated "child 2_ideal value" indicates a value when it is assumed that there is no deviation from a certain reference time, and is a target value. The illustrated "child 2_measured value" indicates a value that can be actually measured, and is a value having a deviation from a certain reference time. In the figure, "child 2_corrected" means a value obtained by adding correction to the second slave station 2002_measured value using the apparent power measured in a short cycle in the master station. As can be seen from the figure, in the correction using the apparent power, the voltage drop amount Vd is shifted from the value VA to the value VB, and it can be seen that the time lag can be effectively corrected.

According to the method of this embodiment, the correction method using the apparent power capable of highly accurate correction and the correction method using the apparent power having a wide range of application are clearly defined as shown in FIG. 7, for example, as described above. You can switch on the grounds.

That is, under the condition that there is a correlation between the apparent current and the voltage drop amount Vd, the correction accuracy is higher when the voltage drop is calculated using the apparent power (apparent current). On the other hand, since there are some conditions where there is no correlation between the apparent power and the amount of voltage drop, a method that does not use the apparent power (internal / external insertion, etc.) is used because the accuracy is low but the applicable conditions are wide. In the present embodiment, by selecting a correction method having a higher effect according to such a condition, it is possible to improve the effect of reducing the error due to the difference in the measurement time. It should be noted that the above method is advantageous because it uses only consistency as an evaluation function and is based on a clear basis as compared with, for example, a correction obtained by a metaheuristic method.

Further, conventionally, it has been necessary to take a large voltage margin or the like in consideration of the deviation of the measured value due to the time difference, but by improving the measurement accuracy, it becomes possible to make an appropriate margin. If an appropriate margin can be provided, the amount of PV introduced can be increased. Alternatively, the measurement period until the amount of electricity with the same accuracy can be obtained can be shortened. Therefore, the period required for determining whether or not to introduce PV can be shortened, which gives an advantage in responding to the rapidly changing renewable energy-related products.

(4) Other Embodiments The above embodiments are examples for explaining the present invention, and the present invention is not intended to be limited only to these embodiments. The present invention can be carried out in various forms as long as it does not deviate from the gist thereof. For example, in the above embodiment, the processing of various programs has been described sequentially, but the present invention is not particularly particular. Therefore, as long as there is no contradiction in the processing results, the processing order may be changed or the processing may be configured to operate in parallel.

INDUSTRIAL APPLICABILITY The present invention can be widely applied to a measurement correction device that corrects a measurement value of an electric power system.

101 …… Power plant, 102 …… Substation, 103 …… Measurement point, 104 …… Transmission line, 105 …… Distribution line, 106 …… Large consumer, 107 …… Small consumer, 110 …… PV (Sun) Photoelectric power generation) device, 200 ... switch, 210 ... substation installation measuring device, 211 ... short cycle measurement processing at the substation sending point, 212 ... long cycle measurement processing with switch, 320 ... ... General control unit, 321 ... Polling control unit, 322 ... Input / output unit, 323 ... Data storage unit, 325 ... Correlation presence / absence determination unit, 330 ... Calculation method switching unit, 331 ... Apparent current was used. Correction unit 332: Correction unit that does not use apparent current.

Claims (5)

The first measuring unit that measures the apparent current or the amount of electricity that can be converted into apparent power at a specific point in the power system in a relatively short cycle,
A determination unit for determining the presence or absence of a correlation between the apparent current and the voltage drop amount,
A second measuring unit that measures at a predetermined location under the specific location with a relatively long cycle, and
The value measured by the second measuring unit is approximated to the value measured with a resolution of a relatively long period or less according to the determination result of the presence or absence of the correlation between the apparent current and the voltage drop amount by the determination unit. Calculation method switching unit that switches the method to be used, and
A correction unit that corrects the value measured by the second measurement unit based on the method switched by the calculation method switching unit, and a correction unit.
A measurement correction device characterized by being equipped with. It has a load determination unit that determines the difference in the amount of change in the amount of voltage drop based on the amount of load in the power system.
The calculation method switching unit is
Instead of the determination unit, a value measured in a relatively long cycle at a predetermined location under the specific location is measured according to the difference in the amount of change in the voltage drop detected according to the determination result by the load determination unit. The measurement correction device according to claim 1, further comprising switching a method that approximates a value measured with a resolution of a long measurement cycle or less. Equipped with a type determination unit that determines the difference in the amount of change in the voltage drop based on the type of weekday or holiday.
The calculation method switching unit is
Instead of the determination unit, a value measured in a relatively long cycle at a predetermined location under the specific location is measured according to the difference in the amount of change in the voltage drop detected according to the determination result by the type determination unit. The measurement correction device according to claim 2, wherein a method that approximates a value measured with a resolution of a long measurement cycle or less is switched. It has a determination switching unit that switches between the determination unit, the load determination unit, and the type determination unit.
The calculation method switching unit is
A value measured in a relatively long cycle at a predetermined location under the specific location according to the execution result of any of the determination unit, the load determination unit, and the type determination unit switched by the determination switching unit. The measurement correction device according to claim 3, further comprising switching a method that approximates a value measured with a resolution of a long measurement cycle or less. The first measurement step of measuring the apparent current or the amount of electricity that can be converted into apparent power at a specific point in the power system in a relatively short cycle, and
A determination step for determining the presence or absence of a correlation between the apparent current and the voltage drop amount,
A second measurement step of measuring at a predetermined location under the specific location with a relatively long cycle, and
The value measured in the second measurement step is approximated to the value measured with a resolution of a relatively long cycle or less according to the determination result of the presence or absence of the correlation between the apparent current and the voltage drop amount by the determination step. Calculation method switching step to switch the method to be performed, and
A correction step for correcting the value measured by the second measurement step based on the method switched in the calculation method switching step, and a correction step.
A measurement correction method characterized by having.

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