JP2011242195A - Phase discrimination method and phase discrimination apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply discriminate a phase of a distribution line of each phase constituting a high-voltage distribution line using an inexpensive apparatus in a phase discrimination portion.SOLUTION: A phase discrimination apparatus includes: firstly measuring a ground voltage and a zero-phase voltage of one distribution line, respectively; then acquiring a phase difference between the ground voltage and the zero-phase voltage; comparing the phase difference at this phase discrimination portion with a determined phase difference measured at a phase determination portion; and thereby discriminating a phase of the distribution line.

Description

  The present invention relates to a phase discrimination method for distribution lines of each phase constituting a high-voltage distribution line, and a phase discrimination device used for phase discrimination.

  In recent years, the adoption rate of all-electric houses has been increasing, and as a result, the capacity of single-phase transformers for supplying low voltage (200 V or 100 V) has been increasing. With the increase in capacity of this single-phase transformer, the problem of three-phase unbalance has emerged, such as the motor phase loss protection relay that protects the motor windings from burning out, etc., due to voltage imbalance It is in. In addition, it is predicted that this three-phase unbalance problem will become prominent due to the expansion of home-use distributed power sources that are expected to accelerate in the future.

  This three-phase imbalance can be suppressed and improved by connecting a newly installed single-phase transformer to a phase with less load. For this reason, it is necessary to perform phase discrimination at a construction site where a single-phase transformer is newly installed.

  As a method for performing phase discrimination, there are a visual method and a synchronous test method.

  Visual phase discrimination is performed by following the distribution line while visually observing from the location where the phase can be determined (phase determination location) such as a substation to the location where the phase is determined (phase discrimination location) such as the construction location. .

  On the other hand, the phase discrimination by the synchronization test is performed by measuring the amplitude and phase of the ground voltage of each phase at the phase determination location and the phase discrimination location and synchronizing the measurement results at both locations. This synchronization test is known to be performed using GPS (Global Positioning System) (see, for example, Patent Document 1 or 2) and performed using portable radio (for example, refer to Patent Document 3). Yes.

JP 2001-215248 A JP 2003-57286 A JP 2000-162258 A

  Here, the visual phase discrimination must be followed while visually checking the distribution line from the phase determination location to the phase discrimination location, which requires a great deal of labor.

  In addition, the device used for the phase discrimination by the synchronization test performed using the GPS is expensive. On the other hand, phase discrimination by synchronization verification performed using a portable radio requires two aerial work vehicles at the same time, and due to the digitization of radio, the currently used device can no longer be used.

  Therefore, the inventors of the present application conducted extensive research and found that the ground voltage of each phase and the zero-phase voltage that remained at all times due to the unbalanced relative ground capacitance and ground voltage of the distribution line. It was found that the phase difference hardly fluctuates with time, and the phase difference can be determined by the phase difference between the ground voltage of each phase and the zero-phase voltage.

  The present invention has been made in view of the problems of the above-described conventional phase determination methods, and the object of the present invention is to provide a distribution line for each phase that constitutes a three-phase high-voltage distribution line at the phase determination point. An object of the present invention is to provide a phase discrimination method for easily performing phase discrimination using an inexpensive device and a phase discrimination device used for phase discrimination.

  In order to achieve the above-described object, the method for discriminating the phases of the distribution lines of the respective phases constituting the three-phase distribution line of the present invention includes the following processes performed at the phase discrimination points.

  First, the ground voltage and the zero-phase voltage of at least one distribution line are measured. Next, the phase difference between the ground voltage and the zero-phase voltage is acquired. Next, the phase is discriminated by comparing the phase difference at the phase discriminating portion with the final phase difference measured at the phase finalizing portion.

  The phase discrimination device of the present invention includes three main high-voltage capacitors, three ground voltage measuring capacitors, and a zero-phase voltage measuring capacitor. One end of each of the three main high-voltage capacitors is connected to a three-phase distribution line. The three ground voltage measuring capacitors are respectively provided in series at the other ends of the three main high-voltage capacitors. The zero-phase voltage measuring capacitor has one end connected to three ground voltage measuring capacitors and the other end grounded.

  According to the phase discrimination method and the phase discrimination device of the present invention, the phase discrimination is performed using the phase difference between the ground voltage of each phase and the zero-phase voltage, which hardly varies with time, so that an inexpensive device can be obtained. And phase discrimination can be easily performed.

It is a figure for demonstrating the relationship of a phase, b phase, c phase, and a zero phase. It is a figure which shows the measurement result of the zero phase voltage in the arbitrary days in a some substation. It is an equivalent circuit diagram which shows the measurement system of a zero phase voltage. It is a figure which shows the phase difference and voltage of a zero phase voltage in a bank with a comparatively small zero phase voltage. It is a figure which shows the phase difference and voltage of a zero phase voltage in a bank with a comparatively large zero phase voltage. It is a schematic diagram for demonstrating the phase discrimination method using ZPD for phase discrimination. It is a schematic diagram for demonstrating the experimental track | line of the phase discrimination test performed using ZPD for phase discrimination. It is a figure which shows the result of the phase discrimination test performed using ZPD for phase discrimination. It is a schematic diagram for demonstrating the 2nd example of the phase discrimination method. It is a figure which shows the waveform of the zero phase voltage which synthesize | combined the voltage waveform measured with the sensor for ground fault direction indicators and a memory high coder, and the voltage waveform of each of these phases. It is a figure which shows the extracted voltage waveform after a Fourier analysis.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the arrangement relationship of each component is merely schematically shown to the extent that the present invention can be understood. In the following, a preferred configuration example of the present invention will be described. However, the material and numerical conditions of each component are merely preferred examples. Therefore, the present invention is not limited to the following embodiments, and many changes or modifications that can achieve the effects of the present invention can be made without departing from the scope of the configuration of the present invention.

  With reference to FIG. 1, the three relative ground voltage and the zero phase voltage will be described. Hereinafter, for convenience, the three phases will be described as a phase, b phase and c phase. FIGS. 1A and 1B are diagrams for explaining the relationship among the a phase, the b phase, the c phase, and the zero phase. FIG. 1A is a schematic diagram showing the relationship between the a phase, the b phase, the c phase, and the zero phase. FIG. 1B is a diagram illustrating voltage waveforms of the a phase, the b phase, the c phase, and the zero phase. In FIG. 1B, the horizontal axis represents time (arbitrary unit) and the vertical axis represents ground voltage (unit: V) of each phase. In FIG. 1B, curves I, II, III, and IV show voltage waveforms of a phase, b phase, c phase, and zero phase, respectively. In addition, the voltage value of each relative ground voltage shown by FIG. 1 (B) is a measured value, and is obtained by dividing the voltage of a distribution line.

  The three relative ground voltages are 120 ° out of phase with each other. That is, the phase difference between the a phase, the b phase, and the c phase is 120 °. The phase difference between each of the three phases has little variation due to location or time. Therefore, if the phase of the zero-phase voltage does not vary with place or time, the phase can be determined based on the phase difference θ between the zero-phase voltage and the three relative ground voltages.

The zero phase voltage (V ₀ ) is given by equation (1). Here, Ca, Cb, and Cc are ground capacitances of each phase, Ea, Eb, and Ec are ground voltages of each phase, Rg is a ground fault resistance, and Rn is in the substation. This is a limiting resistance of an earthing voltage transformer (EVT) provided.

When the ground fault resistance Rg in Expression (1) is infinite, Expression (2) is obtained. From equation (2), the residual zero-phase voltage (V _0Z ) is generated by the unbalance of the ground capacitances Ca, Cb and Cc of each phase and the unbalance of the ground voltages Ea, Eb and Ec of each phase. I understand.

  In general, the zero-phase voltage refers to the one that occurs at the time of the ground fault, and the residual zero-phase voltage may refer to the one that is always occurring even when the ground fault has not occurred. In the description, the ground voltage at the neutral point of the three phases is referred to as zero phase voltage.

FIG. 1 shows an example in which the a phase is focused on as a single-phase distribution line, and the phase difference between the zero-phase voltage V ₀ and the a relative ground voltage is θ.

  FIG. 2 is a diagram illustrating an example of measurement results of zero-phase voltage at a plurality of substations. Many substations can measure zero-phase voltages above 14V. The zero-phase voltage measured at each substation is a minimum of 14 V, a maximum of 160 V, and an average of 51 V, and the zero-phase voltage is a value that can be measured in distribution transformers (banks) of almost all substations. ing. For this reason, the phase difference between the zero-phase voltage and the three relative ground voltages can be obtained at each substation. Therefore, the phase determination can be performed by using the phase difference between the three relative ground voltages and the zero-phase voltage at the phase determined location with these substations as the phase determined location.

First, the variation of the zero-phase voltage depending on the measurement location is examined. FIG. 3 is an equivalent circuit diagram showing a zero-phase voltage measurement system. The measurement of the zero phase voltage V ₀ corresponds to the measurement of the voltage across the limiting resistor Rn of the EVT. Therefore, the amplitude and phase are constant regardless of the portion of the distribution line (indicated by I in FIG. 3). That is, in the example shown in FIG. 3, the zero-phase voltages V ₀ 1, V ₀ 2 and V ₀ 3 measured at different locations on the distribution line have a relationship of V ₀ 1 = V ₀ 2 = V ₀ 3 = V ₀ . Fulfill. Thus, the amplitude and phase of the zero-phase voltage do not vary depending on the location.

  Next, the variation with time of the zero-phase voltage is examined. The phase difference between the zero-phase voltage and the a relative ground voltage and the zero-phase voltage were measured for about two weeks for each of the bank having a relatively small zero-phase voltage and the bank having a relatively large zero-phase voltage. The measurement results are shown in FIGS.

  FIG. 4 shows, as an example, the phase difference between the zero-phase voltage and the a relative ground voltage and the voltage value of the zero-phase voltage in a bank having a relatively small zero-phase voltage. In FIG. 4, the horizontal axis represents time, and the vertical axis represents the phase difference (°) between the zero-phase voltage and the a relative ground voltage and the voltage value (V) of the zero-phase voltage. In FIG. 4, a curve I indicates the phase difference between the zero-phase voltage and the a relative ground voltage, and a curve II indicates the voltage value of the zero-phase voltage.

  As shown in FIG. 4, in the normal system, the phase difference (I) was about 45 ° and there was no temporal variation, and the voltage value (II) was about 55 V and there was no variation. Further, when system switching was performed (portion indicated by III in FIG. 4), the phase difference fluctuated to about 70 °, and the voltage value fluctuated to about 20V.

  FIG. 5 shows, as another example, the phase difference between the zero-phase voltage and the a relative ground voltage and the voltage value of the zero-phase voltage in a bank having a relatively large zero-phase voltage. In FIG. 5, the horizontal axis indicates time, and the vertical axis indicates the phase difference (°) between the zero-phase voltage and the a-relative ground voltage and the voltage value (V) of the zero-phase voltage. In FIG. 5, a curve I indicates the phase difference between the zero-phase voltage and the a relative ground voltage, and a curve II indicates the voltage value of the zero-phase voltage.

  As shown in FIG. 5, in the normal system, the phase difference (I) was about 35 ° and there was no temporal variation, and the voltage value (II) was about 80 V and there was no variation. Further, when system switching was performed (portion indicated by III in FIG. 5), the phase difference fluctuated to about 18 °, and the voltage value fluctuated to about 50V. In FIG. 5, the case where the bank is stopped is indicated by IV.

  Thus, in the normal system, it was confirmed that the phase difference of the zero-phase voltage with respect to the three-phase voltage is substantially constant, and the phase of the zero-phase voltage does not vary with time.

(First example of phase discrimination method)
As described with reference to FIGS. 1 to 5, the phase difference between the ground voltage of each phase and the zero-phase voltage hardly varies depending on time and place. Therefore, when performing phase discrimination at the phase discrimination location, synchronization verification is not necessary.For example, after obtaining the phase difference at the phase determination location, the measurement device used at the phase determination location is used to determine the phase at the phase discrimination location. The phase can be determined by acquiring the phase difference and comparing the two.

  In the phase determination method of this embodiment, first, the phase difference between the ground voltage and the zero-phase voltage of each phase is acquired as the determined phase difference at the phase determined location. Thereafter, the phase difference between the ground voltage and the zero-phase voltage of each phase is acquired at the phase discrimination point.

  In order to obtain the phase difference between the ground voltage and the zero-phase voltage of each phase, for example, a capacitor type zero-phase voltage detector for phase discrimination (ZPD for phase discrimination: zero phase potential device) can be used.

  FIG. 6 is a schematic diagram for explaining a phase discrimination method using a phase discrimination ZPD as a phase discrimination device as a first example of the phase discrimination method. The phase discrimination ZPD 10 includes three main high-voltage capacitors 12a, 12b and 12c, three ground voltage measuring capacitors 14a, 14b and 14c, and a zero-phase voltage measuring capacitor 16.

  The main high-voltage capacitor 12 and the ground voltage measuring capacitor 14 are provided for each phase. One end of the a-phase main high-voltage capacitor 12a is connected to the a-phase distribution line 20a, and the other end is connected to one end of the a-phase ground voltage measuring capacitor 14a. The b-phase main high-voltage capacitor 12b has one end connected to the b-phase distribution line 20b and the other end connected to one end of the b-phase ground voltage measuring capacitor 14b. The c-phase main high-voltage capacitor 12c has one end connected to the c-phase distribution line 20c and the other end connected to one end of the c-phase ground voltage measuring capacitor 14c.

  The other ends of the ground voltage measuring capacitors 14a, 14b and 14c opposite to the one connected to the main high voltage capacitors 12a, 12b and 12c are connected to one end of the zero phase voltage measuring capacitor 16. The other end of the zero-phase voltage measuring capacitor 16 is grounded.

  The phase determination ZPD further includes a voltage signal acquisition unit and a phase difference acquisition unit. The voltage signal acquisition unit acquires a plurality of voltage signals and stores them in a RAM (Random Access Memory) or the like as appropriate. The phase difference acquisition unit acquires a phase difference between the two voltage signals read out from the RAM, among the plurality of voltage signals acquired by the voltage signal acquisition unit. These voltage signal acquisition unit and phase difference acquisition unit can have any conventionally known and suitable configuration.

  Here, the voltage signal acquisition unit acquires the potential difference between both ends of the ground voltage measuring capacitor 14 as the ground voltage, and acquires the potential difference between both ends of the zero phase voltage measuring capacitor 16 as the zero phase voltage. The phase difference acquisition unit acquires a phase difference between at least one of the three-phase ground voltages and the zero-phase voltage.

  The ground voltage of the distribution line is divided by the ground voltage measuring capacitors 14a, 14b and 14c and the main high voltage capacitors 12a, 12b and 12c. For example, the main high voltage capacitors 12a, 12b and 12c have a capacitance of 5 to 6 pF, the ground voltage capacitors 14a, 14b and 14c have a capacitance of 1 μF, and the zero phase voltage capacitor 16 has a capacitance of 0.5 μF.

  Here, the main high-voltage capacitors 12a, 12b and 12c have three main high-voltage capacitors 12a, 12b and 12c in which the voltages of the main high-voltage capacitors 12a, 12b and 12c and the ground voltage measuring capacitors 14a, 14b and 14c are in phase. It is a condition that the electrostatic capacity of each has the same value.

  Next, a verification experiment performed using the phase determination ZPD described with reference to FIG. 6 will be described. FIG. 7 is a schematic diagram for explaining an experimental line for a phase discrimination test performed using a phase discrimination ZPD.

  In the experimental line, measurement was performed by generating a zero-phase voltage of 200 V by using four 0.5 μF capacitors and one 0.2 μF capacitor as the grounding capacitor 110, and making the ground capacitance unbalanced. went. Moreover, the tap of the automatic voltage regulator (SVR: Step Voltage Regulator) 120 was switched, and the change by pressure | voltage rise was measured.

  FIG. 8 is a diagram showing the results of the phase discrimination test performed using the phase discrimination ZPD, and shows the voltage waveforms of the a phase, b phase, c phase, and zero phase. In FIG. 8, the horizontal axis shows time (unit: ms), and the vertical axis shows voltage values (unit: V) of each relative ground voltage and zero-phase voltage (unit: V). Yes. In FIG. 8, curves I, II, III and IV show the voltage waveforms of the a phase, b phase, c phase and zero phase, respectively.

  As shown in Table 1, on the power supply side of the SVR 120 in the first feeder (feed line) 101 and the second feeder 102, the phase difference between the a phase and the zero phase is 305 ° to 307 °, which is very high. The phase difference matches with accuracy.

  On the load side of the second feeder (F-2) 102, when the tap of the SVR 120 is set to 3, the phase difference is 305 °, and the phase difference matches that of the first feeder (F-1) 101 and the like. Yes. However, when the tap of the SVR 120 is set to 6 and the pressure is increased, the phase difference is 352 ° and the phase is shifted.

  As described above, it has been confirmed that on the power source side of the SVR 120, phase discrimination can be performed with high accuracy using the phase discrimination ZPD. It should be noted that there is a case where the phase difference does not match between the power source side and the load side of the SVR 120, so that it is difficult to determine the phase with high accuracy on the load side of the SVR 120. Further, when the system is switched, the phase of the zero-phase voltage is shifted, so that the phase cannot be determined.

(Second example of phase discrimination method)
As a method of measuring the phase difference of the three-phase voltage with respect to the zero-phase voltage, a sensor for a device (for example, a high-voltage ground fault direction indicator manufactured by Denken Co., Ltd.) that displays the direction of the ground fault location on the distribution line (hereinafter, And a method using an instantaneous value measuring device capable of measuring and storing an instantaneous value, such as a memory high coder (for example, manufactured by HIoki Corporation).

  A second example of the phase discrimination method will be described with reference to FIG. FIG. 9 is a schematic diagram for explaining a second example of the phase discrimination method.

  In this method, three main high-voltage capacitors 32a, 32b and 32c, which are connected to the three-phase distribution lines 20a, 20b and 20c, respectively, and the other ends of the three main high-voltage capacitors 32 are provided in series. For the circuit including the three termination resistors 34a, 34b, and 34c, the voltage across the termination resistor 34 is acquired as the three relative ground voltages. The other end of the termination resistor 34 is grounded.

  For example, if the capacity of the main high voltage capacitor 32 is 10 pF and the termination resistance 34 is 100 kΩ, the measured voltage is about 0.324 V when the potential of the distribution line 20 is 3810 V.

  The zero-phase voltage waveform is obtained by synthesizing the voltage waveforms of the respective phases.

  FIG. 10 is a diagram illustrating an example of a voltage waveform measured by a ground fault direction indicator sensor and an instantaneous value measuring instrument, and a waveform of a zero-phase voltage obtained by synthesizing the voltage waveforms of these phases. In this measurement example, a harmonic waveform is amplified and distorted.

  Since it is difficult to determine the phase as it is, a 50 Hz component is extracted from the voltage waveform of the three relative ground voltages and the voltage waveform of the zero-phase voltage by Fourier analysis, and the phase comparison is performed. FIG. 11 is a diagram illustrating an extracted voltage waveform after Fourier analysis.

  10 and 11, the horizontal axis indicates time (unit: ms), and the vertical axis indicates the voltage value (unit: V) of each relative ground voltage and the voltage value (unit: V) of the zero-phase voltage. It shows. In FIGS. 10 and 11, curves I, II, III, and IV indicate voltage waveforms of a phase, b phase, c phase, and zero phase, respectively.

  Table 2 shows the phase difference between the three relative ground voltages and the zero-phase voltage obtained by this method.

  Table 2 shows the results of measurement performed by changing the feeder for each of the three banks. Here, the phase difference between the a phase (blue phase) visually confirmed in advance and the zero phase is examined.

  In each bank, two out of three places have almost the same phase, but one place cannot be determined to be in phase. This is because the three-phase waveform is synthesized when the voltage waveform of the zero-phase voltage is obtained, so that the dispersion is amplified, and as a result, the phase of the zero-phase voltage is shifted and an error occurs in the phase difference. It is done.

  Therefore, in implementing the second example of this phase discrimination method, it is necessary to consider the influence of the amplitude error of each phase.

(Third example of phase discrimination method)
As a method of measuring the phase difference of the three-phase voltage with respect to the zero-phase voltage, obtain the voltage waveform of the three-phase voltage using the sensor for the ground fault direction indicator and the instantaneous value measuring device, etc. There is also a method of obtaining from a high voltage switch built in the ZPD and an instantaneous value measuring device.

  The zero-phase voltage acquired from the high-voltage switch with built-in ZPD is out of phase due to the specifications of the equipment, and the ground voltage of the ground fault direction indicator sensor is measured on the R side of the RC series circuit. Out of phase. Table 3 shows the calculated phase differences in consideration of these deviations.

  The phase difference obtained by the three switches has a value of 15 ° to 31 °. Thus, the phase differences at the three locations coincide within a range of about ± 8 °, and sufficient accuracy is obtained for phase discrimination.

10 Phase detection ZPD
12 Main high voltage capacitor
14 Capacitor for measuring ground voltage 16 Capacitor for measuring zero-phase voltage 20 Distribution line 101, 102 Feeder 110 Capacitor for grounding 120 SVR

Claims (9)

A method for determining the phase of each distribution line constituting a three-phase distribution line,
At the phase discrimination point,
Measuring a ground voltage and a zero-phase voltage of at least one of the distribution lines, and
Obtaining a phase difference between the ground voltage and the zero-phase voltage;
A phase discriminating method comprising: a step of discriminating a phase by comparing a phase difference between a ground voltage and a zero-phase voltage measured in advance at a phase-determined portion and the phase difference. The phase discrimination method according to claim 1,
A phase discrimination method characterized by simultaneously measuring a ground voltage and a zero-phase voltage of at least one of the distribution lines at the phase discrimination location. The phase discrimination method according to claim 1,
In the phase discrimination point, measure the ground voltage of the three distribution lines,
A phase discrimination method comprising: synthesizing ground voltages of three distribution lines to obtain a zero-phase voltage. The phase discrimination method according to claim 2,
further,
Performed in advance at the phase determination point,
A process of simultaneously measuring a ground voltage and a zero-phase voltage of each of the three distribution lines;
A phase discrimination method comprising: obtaining a definite phase difference between the ground voltage of each phase and the zero-phase voltage. The phase discrimination method according to claim 3,
further,
Performed in advance at the phase determination point,
Measuring the ground voltage of the three distribution lines, and synthesizing the ground voltages of the three distribution lines to obtain a zero-phase voltage;
A phase discrimination method comprising: obtaining a definite phase difference between the ground voltage of each phase and the zero-phase voltage. The phase discrimination method according to claim 2 or 4,
Three main high-voltage capacitors each connected at one end to the three-phase distribution line;
Three ground voltage measuring capacitors respectively provided in series at the other end of the three main high-voltage capacitors;
A phase discrimination method comprising: a phase discrimination device having one end connected to the three ground voltage measurement capacitors and the zero phase voltage measurement capacitor having the other end grounded. The phase discrimination method according to claim 6,
A voltage signal acquisition unit that acquires a potential difference between both ends of the capacitor for ground voltage measurement as a ground voltage, and acquires a potential difference between both ends of the capacitor for zero phase voltage measurement as a zero phase voltage;
A phase discrimination method comprising: a phase discrimination device including a phase difference acquisition unit that acquires a phase difference between the ground voltage and the zero phase voltage. Three main high-voltage capacitors each connected to a three-phase distribution line,
Three ground voltage measuring capacitors respectively provided in series at the other end of the three main high-voltage capacitors;
A phase discrimination apparatus comprising: a zero-phase voltage measurement capacitor having one end connected to the three ground voltage measurement capacitors and the other end grounded. A voltage signal acquisition unit that acquires a potential difference between both ends of the capacitor for ground voltage measurement as a ground voltage, and acquires a potential difference between both ends of the capacitor for zero phase voltage measurement as a zero phase voltage;
The phase determination device according to claim 8, further comprising a phase difference acquisition unit that acquires a phase difference between the ground voltage and the zero-phase voltage.

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