JP2016192839A - Electric power substation connection direction determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power substation connection direction determination method of an automatic voltage controller installed on a distribution line.SOLUTION: An electric power substation connection direction is determined by comparing a primary impedance and a secondary impedance of an automatic voltage controller. When a determination result is different from the determination result of the last time, by returning a tap position to a position before the tap changeover and repeating the determination once again, the accuracy of the determination result is enhanced.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for determining a substation connection direction of an automatic voltage regulator installed on a distribution line.

  FIG. 1 is an equivalent circuit that simplifies a power distribution system in which an automatic voltage regulator (SVR) is installed. The SVR installed on the distribution line determines the connection direction of the substation and performs tap control so that the voltage on the load side, which is the opposite side, is maintained at an appropriate voltage (operating voltage). The connection direction of the substation is changed by switching the system.

  An example of determining the connection direction of a substation is disclosed in Patent Document 1 below.

JP 2003-102128 A

The determination method described in Patent Document 1 calculates the impedances Z ₁ and Z ₂ on the primary side and the secondary side viewed from the SVR, and determines the connection direction of the substation by comparing the magnitudes thereof. is there. Since the substation connection side is considered to be substantially connected to an infinite bus, the connection direction of the substation is determined based on the fact that the impedance on the substation connection side is smaller than the impedance on the load side.

Specifically, when the tap is switched, the primary side voltage V ₁ , the secondary side voltage V ₂ and the secondary side current I ₂ before and after the tap switching are measured, and the primary side voltage V ₁ is measured from each measured value. Change ΔV ₁ , secondary voltage V ₂ change ΔV _2, and secondary current change ΔI ₂ are calculated.

Then, the primary side current I ₁ is obtained by substituting the primary side voltage V ₁ , the secondary side voltage V ₂ and the secondary side current I ₂ into a predetermined formula, and the change ΔI ₁ is calculated. Is obtained as Z ₁ = ΔV ₁ / ΔI _{1 and} the impedance on the secondary side Z ₂ = ΔV ₂ / ΔI ₂ , and the magnitudes of Z ₁ and Z ₂ are compared.

  However, the determination method described in Patent Document 1 has a possibility that the determination accuracy is lowered at a location where the voltage / current fluctuation is large, and the connection direction of the substation may be erroneously determined.

  The present invention is disclosed as being able to eliminate the above drawbacks.

  The invention according to claim 1 calculates the impedance of the primary side distribution system from the amount of change in the primary side voltage and the primary side current generated before and after the switching of the tap of the automatic voltage regulator installed in the distribution line, Calculate the impedance of the secondary power distribution system from the amount of change in the secondary side voltage and secondary current generated before and after switching, and compare the magnitude of both impedances to determine whether the primary side or secondary side of the regulator If the determination result of the connection direction of the substation has been changed from the previous determination result, the determination is performed again at the stage where the tap position is returned to before tap switching. It has the characteristics.

  According to a second aspect of the present invention, in the first aspect of the invention, the amount of change in the difference voltage before and after tap switching between the primary voltage and the secondary voltage of the automatic voltage regulator exceeds a predetermined voltage value during a certain cycle. In this case, the first cycle exceeding the first cycle is detected as a tap switching completion point of the automatic voltage regulator.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the primary voltage, the secondary voltage and the primary current generated before and after the tap switching of the automatic voltage regulator, In measuring the amount of change in the secondary current, considering the voltage fluctuation of the distribution line, exclude the primary side voltage, the secondary side voltage, the primary side current, the number of sampling cycles of the secondary side current, and the measurement before and after tap switching. It is characterized in that the interval time is determined.

  According to the first aspect of the present invention, by repeatedly executing the determination of the substation connection direction, it is possible to reduce the probability of erroneous determination caused by the influence of voltage / current fluctuations occurring before and after tap switching.

  According to the second aspect of the present invention, since an accurate tap switching completion point can be detected, the determination data ranges of the primary side and secondary side impedance can be appropriately set.

  According to the third aspect of the invention, it is possible to appropriately acquire the determination data of the primary side and the secondary side impedance according to the voltage fluctuation of the distribution line and the transient phenomenon that occurs at the time of tap switching.

It is a simplified equivalent circuit of the distribution system. It is a time chart which shows the relationship between the tap switching completion point and the data range for impedance determination. It is a flowchart which shows the determination method of the substation connection direction which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3. In the equivalent circuit shown in FIG. 1, when determining whether the substation is connected to the primary side or the secondary side of the SVR, the primary side of the SVR before tap switching, as in the invention described in Patent Document 1 described above. The voltage V ₁ , the secondary side voltage V ₂ , the secondary side current I ₂ , the primary side voltage V ₁ ′, the secondary side voltage V ₂ ′, and the secondary side current I ₂ ′ after tap switching are measured.

The primary currents I ₁ and I ₁ ′ before and after the tap switching are the secondary currents I ₂ and I ₂ ′ before and after the tap switching, the primary voltages V ₁ and V ₁ ′, and the secondary voltages V ₂ and V ₂ ′. Calculated from the ratio of

Measurement of the data, for the primary voltage V ₁ of the previous tap changer and the secondary-side voltage V ₂ and the secondary current I _2, as shown in FIG. 2 (a), the tap switching of the tap changer completion temae Sample the number of operation cycles before the number of previous exclusion cycles.

The primary side voltage V ₁ , the secondary side voltage V ₂ and the secondary side current I ₂ after the tap switching sample the number of operation cycles after the tap switching exclusion cycle number after the tap switching completion point.

The primary side current I ₁ is calculated from the ratio of the secondary side current I ₂ to the primary side voltage V ₁ and the secondary side voltage V ₂ every sampling.

  The number of calculation cycles for data measurement before and after tap switching shown in FIG. 2A is for the purpose of shortening the interval time before and after tap switching as much as possible, and that the standard deviation σ of the voltage fluctuation of the distribution line is minimized at the number of cycles. Therefore, it is set for the purpose of improving the determination accuracy of the connection direction of the substation described later. Further, the number of excluded cycles after tap switching is set in consideration of a transient phenomenon after tap switching.

The tap switching completion points described above are the difference voltage V ₁₂ between the primary side voltage V ₁ and the secondary side voltage V ₂ before the tap switching, the primary side voltage V ₁ ′ and the secondary side voltage V ₂ ′ after the tap switching. At the first cycle when a cycle in which the difference ΔV ₁₂ between the difference voltages V ₁₂ ′ exceeds a voltage change for one tap (for example, 50 [V]) reaches a constant cycle (for example, 10 cycles) continuously. Detect as. The detection condition of the tap switching completion point is set for the purpose of shortening the tap switching interval as much as possible and enabling accurate tap switching point calculation.

The data V ₁ , V ₁ ′, V ₂ , V ₂ ′, I ₁ , I ₁ ′, I ₂ , I ₂ ′ before and after the tap switching sampled in this way indicate the magnitude of the primary side impedance of the SVR. | Z ₁ | = ΔV ₁ / ΔI ₁ , the secondary impedance of the SVR is calculated as | Z ₂ | = ΔV ₂ / ΔI ₂ , and the calculated magnitudes of both impedances | Z ₁ |, | Z ₂ | is compared, and in the case of | Z ₁ | ≦ | Z ₂ |, it is determined that a substation is connected to the primary side of the SVR as a forward feed, and | Z ₁ |> | Z ₂ | In the case of, it is determined that the substation is connected to the secondary side of the SVR as reverse transmission.

Thus, by comparing the magnitude of the primary side impedance | Z ₁ | and the secondary side impedance | Z ₂ |, it is possible to determine to which of the SVR the substation is connected with a certain accuracy. The invention is characterized in that such determination is executed a plurality of times.

FIG. 3 is a flowchart for explaining the determination method of the present invention. First, in the progressive state of step S _1, the SVR performs tap changer in step S ₂ in order to keep the load voltage to a proper voltage, the impedance described above in step _{S 3 | Z 1 |, |} Z 2 | of A size comparison is made, and it is determined whether forward or backward.

If the test result in step S ₃ is the feed forward, because there is no change in the state of step S _1, it determines that the substation is connected in a direction that has been determined to the power supply side in Step S _1. Conversely, if the decision result in the step S ₃ was a backhaul, changes in the connection direction of the substation by line switching換等is considered to have occurred. In this case, instead of performing tap changer in order to keep the voltage determined load side receives the determination result of step S ₃ to a proper voltage, in step S _4, the once before switching the taps from the viewpoint of safety conditions after returning to again in step S _5, it is determined whether progressive or backhaul. Thus, the final determination accuracy can be improved by repeating the determination with a certain accuracy a plurality of times.

If the test result in step S ₅ is a feed forward, since the determination result of step S ₃ is that was wrong, the load side voltage of the SVR as no change in the substation connecting direction returns to step S ₁ Continue control to keep it appropriate. If the decision result in the step S ₅ was the reverse feeding, as the determination result of step S ₃ is correct, the process proceeds to step S _6, it is determined that there is a change in the substation connection direction, and the opposite side The control which maintains the load side voltage of SVR which becomes becomes appropriate is performed.

After that, when tap switching of the SVR load side voltage is performed in step S ₇ , the magnitudes of the impedances | Z ₁ | and | Z ₂ | are again compared in step S ₈ to determine whether forward feeding or backward feeding is performed. Do.

If the test result in step S ₈ is a backhaul, since there is no change in the state of step S _6, it determines that the substation in a direction that has been determined to the power supply side in step S ₆ is connected. If conversely the determination result in step S ₈ is was fed forward, since changes in the connection direction of the substation by line switching換等is considered to have occurred, in step S _9, the tap from the viewpoint of safety temporarily switching after returning to the previous state, again in step S _10, performs a determination of whether progressive or backhaul, increasing the final determination accuracy.

If the test result in step S ₁₀ is the backhaul, as the determination result of step S ₈ it was erroneous, the proper load side voltage of the SVR as no change in the connection direction of the substation back to Step S ₆ Continue to maintain control. If the test result in step S ₁₀ is the feed forward, as the determination result of step S ₈ is correct, the process proceeds to step S _1, when there is a change in the connection direction of the substation, the opposite load Executes control to keep the side voltage properly.

  As described above, the determination method of the substation connection direction according to the present invention, when it is determined that the forward / reverse state has been changed from the current state, repeats the forward / reverse determination again, thereby finally Therefore, it is possible to improve the accuracy of determination and determine the connection direction of the substation with high accuracy.

  Further, when the forward / reverse determination is repeated, the state before the tap is switched is temporarily returned, so that safety is improved.

  Furthermore, since the optimum interval time before and after the tap switching and the number of cycles of the AC voltage / AC current used for calculating the voltage / current change amount are determined, the determination accuracy of the substation connection direction can be improved.

  In addition, since the tap switching completion point can be accurately detected, it is possible to appropriately set the determination data range of the primary side impedance and the secondary side impedance.

  The present invention is used in a power distribution automatic adjustment device.

Claims (3)

  Calculate the impedance of the primary distribution system from the change in primary voltage and primary current generated before and after the tap switching of the automatic voltage regulator installed in the distribution line, and generate the secondary side before and after the tap switching. Whether the substation is connected to the primary side or secondary side of the regulator by calculating the impedance of the secondary distribution system from the amount of change in voltage and secondary current and comparing the magnitude of both impedances If the determination result of the connection direction of the substation is changed from the previous determination result, the tap position is returned to the position before the tap switching and the determination is performed again. .   The automatic voltage regulator detects the first cycle time when the difference in voltage change before and after tap switching between the primary voltage and the secondary voltage of the automatic voltage regulator exceeds a predetermined voltage as a tap switching completion point of the automatic voltage regulator. The substation connection direction determination method according to claim 1.   In measuring the amount of change in the primary side voltage, secondary side voltage and primary side current, and secondary side current generated before and after the tap switching of the automatic voltage regulator, the primary side voltage The substation according to claim 1, wherein the sampling time of the secondary side voltage, the primary side current, and the secondary side current and the sampling period before and after the tap change are determined. Connection direction determination method.

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