JP2010172120A - Method and device for determining wire connection state of three-phase power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire connection state determining device embodying a wire connection state determining method for a three-phase power supply that surely determines a wire connection state (phase interruption or a live wire) of a three-phase power supply in a short period of measurement time. <P>SOLUTION: A non-contact sensor 16 is arranged close to each conductor 14 to be measured of an R-phase, an S-phase, and a T-phase of a three-phase power supply being a determination target of a wire connection state. The non-contact sensor acquires a correlation voltage signal of each phase flowing in each conductor 14 to be measured. A differential voltage generating means 17c generates a differential voltage between the R-phase and the S-phase, a differential voltage between the S-phase and the T-phase, and a differential voltage between the T-phase and the R-phase respectively after the correlation voltage signal of each phase passes through a low-pass filter 17a and a buffer 17b. Each differential voltage is inputted to each A/D converter input port AN0-2 of a microcomputer 18. An amplitude level pattern of each differential voltage signal is compared with preset wire connection state determination conditions so as to determine the wire connection state of the three-phase power supply and to notify the determination result by a notification circuit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a connection state determination method for detecting an open phase and a live line of a three-phase power supply, and a connection state determination device that embodies this method.

  Conventionally, as a method for detecting an open phase of a three-phase power source, a method for detecting whether or not a prescribed difference is maintained by monitoring a phase difference of each phase is generally performed. For example, the output of each phase (R phase, T phase, S phase) of a three-phase power supply is converted into a binary pulse via a photocoupler and input to the interrupt input terminal of the microcomputer. There is one that interrupts the microcomputer by ON / OFF due to change and detects the phase difference of each phase from the interrupt generation timing of each phase (see, for example, Patent Document 1).

  In such a phase difference detection device, the three-phase output becomes a three-phase pulse voltage having a phase difference of 120 degrees and is input to each interrupt input terminal of the microcomputer, and the falling (or rising) of the three-phase pulse is detected. ) Is set to generate an interrupt. When an interrupt is generated by a pulse input to an interrupt input terminal of a certain phase, the internal timer is activated using this interrupt as a trigger, and an interrupt is generated in the other two phases. Times T1 and T2 until measurement are measured, and the phase loss is determined based on the measurement times T1 and T2.

  For example, when the AC frequency is 50 Hz, it can be determined that there is no phase loss at T1≈3.3 (ms) and T2≈6.7 (ms), and when 60 Hz, T1≈2.8 (ms). , T2≈5.6 (ms), it can be determined that there is no phase loss. On the other hand, when there is one open phase, the two phases are in phase, and the remaining one phase has an inverted waveform that is 180 ° out of phase. At this time, which phase is in phase varies depending on the connected load, but from the viewpoint of the microcomputer, there is no particular difference. T1 = T2 (in the case of 50 Hz, T1 = T2 = 10 [ms], In the case of 60 Hz, T1 = T2 = 8.3 [ms]).

  In addition, as a voltage detector that detects the state of the open phase and the live wire, a detector that is electrically connected to the power detection unit by contact with the power detection unit is provided at the tip of the main body unit, An insulating grip extending from the base end is provided, and a small ground electrode electrically connected to the ground terminal portion of the detection circuit is provided in the main body, and the main body is gripped by the operator. When the detector at the tip of the contact portion is brought into contact with the power-to-be-tested portion, when the power-tested portion is in a live line state, with respect to the ground voltage E, the detector → the detection circuit portion → the ground electrode and the human body ( Since the closed circuit is formed by the path of the floating capacitance C1 formed between the worker) → the human body → the floating capacitance C2 formed between the human body and the ground → the ground, and the electrostatic induction current i flows, There is one in which the detection circuit unit detects the connection state of the power detection unit based on the detection signal ( Example, see Patent Document 2). In this voltage detector, the live line state of the voltage detection unit is notified by sound generation by a buzzer or light emission by an LED or the like.

JP 2003-153429 A JP 2002-148287 A

  However, in the conventional phase loss detection device described in Patent Document 1, in order to measure the phase difference of each phase at the fall (rise) of the pulse voltage, when noise is randomly superimposed on the waveform input to the microcomputer, In order to measure an ambiguous value even when a phase shift due to voltage imbalance occurs due to noise being measured as the falling edge of the pulse (rising edge), the connection state of the three-phase power supply is appropriate. There is a problem that it cannot be judged.

  In addition, when trying to determine the hot line state of a three-phase power source using the hot line state detection technique employed in the conventional voltage detector described in Patent Document 2, the generated electrostatic induction current is Since the human body (worker) is routed between the power-tested part and the ground, the voltage measured due to the state of contact between the power-tested part-worker-ground and external factors is not stable, When the measured value is replaced with a voltage waveform, there is a problem in that noise is superimposed on the measured waveform, which causes a problem that the live line state of the three-phase power source cannot be properly determined.

  The present invention solves such a conventional problem, and a method for determining a connection state of a three-phase power supply that can reliably determine the connection state (open phase or live line) of the three-phase power supply in a short measurement time, and this method An object of the present invention is to provide a connection state determination device that embodies the above.

  In order to solve the above-described problem, a connection state determination method for a three-phase power supply according to claim 1 acquires a correlation voltage signal of each phase in the three-phase power supply, and obtains three types of voltage signals that are differences between the voltage signals of each phase. A differential voltage signal is generated, each differential voltage signal is measured continuously for a measurement period of one cycle or more, and preset based on an amplitude level pattern of each differential voltage signal generated according to the connection state of the three-phase power source It is characterized in that the connection state of the three-phase power source is determined by determining the amplitude level pattern of each differential voltage signal within the measurement period under the connection state determination condition.

  According to a second aspect of the present invention, there is provided a three-phase power connection state determining apparatus, comprising: a phase signal acquiring unit that acquires a correlation voltage signal of each phase in a three-phase power source; and a voltage signal of each phase acquired by the phase signal acquiring unit. Difference voltage signal generation means for generating three types of difference voltage signals as differences, and connection state determination conditions set in advance based on the amplitude level pattern of each difference voltage signal generated according to the connection state of the three-phase power supply And a connection state determination means for determining the connection state of the three-phase power supply by determining the amplitude level pattern of each differential voltage signal within the measurement period.

  According to the connection state determination method of the three-phase power supply according to claim 1, the correlation voltage signal of each phase in the three-phase power supply is acquired, and three types of difference voltage signals that are the difference between the voltage signals of each phase are generated, Measuring each difference voltage signal continuously for a measurement period of one cycle or more, and based on the amplitude level pattern of each difference voltage signal generated according to the connection state of the three-phase power source, Since the connection state of the three-phase power supply is determined by determining the amplitude level pattern of each difference voltage signal within the measurement period, the connection state of the three-phase power supply can be determined with high accuracy in a short measurement time.

  According to a second aspect of the present invention, there is provided a three-phase power connection state determining apparatus, comprising: a phase signal acquiring unit that acquires a correlation voltage signal of each phase in a three-phase power source; and a voltage signal of each phase acquired by the phase signal acquiring unit. Difference voltage signal generation means for generating three types of difference voltage signals as differences, and connection state determination conditions set in advance based on the amplitude level pattern of each difference voltage signal generated according to the connection state of the three-phase power supply And a connection state determination means for determining the connection state of the three-phase power supply by determining the amplitude level pattern of each differential voltage signal within the measurement period, so that the three-phase power supply with high accuracy in a short measurement time. The connection state can be determined.

It is a functional block diagram which shows embodiment of the connection state determination apparatus of the three-phase power supply which concerns on this invention. It is a wave form diagram which shows an example of the difference voltage signal acquired when a three-phase power supply is normally connected. (A-1) is the correlation voltage signal of each phase in the live line state, (b-1) is the amplitude level pattern of the differential voltage signal in the live line state, and (a-2) is each phase in the R open phase state. (B-2) is the amplitude level pattern of the differential voltage signal in the R phase loss state, (a-3) is the correlation voltage signal of each phase in the S, T phase loss state, (b-3) is It is an amplitude level pattern of the differential voltage signal in the S, T phase loss state. It is a flowchart which shows the connection state determination process in the connection state determination apparatus of this embodiment.

  Next, an embodiment of a connection state determination apparatus that embodies a connection state determination method for a three-phase power source according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a functional block diagram showing a schematic configuration of a connection state determination device according to the present embodiment, and contacts the R-, S-, and T-phase measured conductors 14 of a three-phase power source that is a connection state determination target. The non-contact sensor 16 connected to the device main body 15 is arranged close to the measured conductors 14 of the R phase, T phase, and S phase so that the voltage can be measured in a state in which the current flows in the measured conductor 14. The correlation voltage signal is acquired by the electrostatic induction method. In the present embodiment, the non-contact sensor 16 is a phase signal acquisition unit. However, the present invention is not limited to this, and a contact sensor may be used.

  As described above, the correlation voltage signal of each phase acquired by the non-contact sensor 16 is input to the connection state determination circuit 17, and the determination result performed by the connection state determination circuit 17 is notified by the notification circuit (of the device body 15). (Visible display by turning on / off the LED provided at an appropriate place, sound output by a speaker, etc.).

  The correlation voltage signal of each phase input to the connection state determination circuit 17 passes through the low-pass filter 17a and the buffer 17b, and then generates a difference voltage signal that generates three types of difference voltage signals that are differences between the voltage signals of each phase. The differential voltage generation means 17c as the means generates a differential voltage between the R phase and the S phase, a differential voltage between the S phase and the T phase, and a differential voltage between the T phase and the R phase, respectively. The data is input to A / D converter input ports (AN0 to AN2) of the computer 18. FIG. 2 is a waveform diagram showing an example of a differential voltage signal obtained by monitoring each differential voltage signal that can be measured at AN0 to 2 when a voltage of about 200 V is applied to each phase of the conductor 14 to be measured. During normal connection, the signal amplitudes are equal and there is no waveform distortion.

  Here, the connection state determination method performed by the microcomputer 18 will be described in order.

  FIG. 3 shows the correlation between each correlation voltage signal and the difference voltage signal depending on the voltage applied to the conductor 14 to be measured. FIGS. 3 (a-1) and 3 (b-1) are all three phases. Shows the correlation voltage signal waveform of each phase in the live line state and the amplitude level pattern of the difference voltage, and FIGS. 3A-2 and 3B-2 show the correlation voltage signal waveform of each phase in the R open phase state. 3A and 3B show the correlation voltage signal waveform and the amplitude level pattern of each phase in the S and T open phase states.

  As shown in FIG. 3 (a-1), when the voltage E is applied to all of the R-phase, S-phase, and T-phase correlated voltage signals of each measured conductor 14, each phase and phase of the three-phase power source Since the voltage phase difference is 120 °, as shown in FIG. 3 (b-1), all the difference voltage signals are inputted to AN0-2 of the microcomputer 18 as a voltage of E × √3. That is, when all the phases of the three-phase power supply are in the live line state, the microcomputer 18 measures all the differential voltage signals as the same signal amplitude (E × √3).

  However, as shown in FIG. 3A-2, when the voltage E is applied only to the correlation voltage signal of the conductor 14 to be measured of the S phase and the T phase (when the R phase is an open phase), Since the voltage phase difference between the S phase and the T phase of the three-phase power supply that is in the state is 120 °, only the differential voltage signal of the S phase and the T phase, as shown in FIG. The difference voltage signal between the R phase and the S phase and the difference voltage signal between the T phase and the R phase are input to the microcomputer 18 as the E voltage because no voltage is applied to the R phase. That is, when one phase of the three-phase power supply is open, the microcomputer 18 sets the two signals to the same signal amplitude E and the remaining one signal to the signal amplitude √3E (√3 times the other two signals). The amplitude is measured as follows.

  Further, as shown in FIG. 3A-3, when the voltage E is applied only to the correlation voltage signal of the R-phase measured conductor 14 (when the two phases S and T are missing), 3 (b-3), since no voltage is applied to both the S phase and the T phase, no voltage is generated in the differential voltage signal between the S phase and the T phase, and the difference between the R phase and the S phase. Both the voltage signal and the T-phase-R differential voltage signal are input to the microcomputer 18 as E voltage. That is, when the two phases of the three-phase power supply are open, the microcomputer 18 measures two signals with the same signal amplitude E and the remaining one signal with no voltage.

  As described above, the connection state of the three-phase power supply can be determined by the combination of the amplitude level patterns of the differential voltage signals of the respective phases. That is, each differential voltage signal is continuously measured for a measurement period of one cycle or more, and based on the amplitude level pattern of each differential voltage signal generated according to the connection state of the three-phase power source, the connection state determination condition is set in advance. The connection state of the three-phase power supply can be determined by determining the amplitude level pattern of each differential voltage signal within the measurement period.

  Based on this, a specific example of the connection state determination process executed by the microcomputer 18 as the connection state determination means will be described with reference to FIG. It is assumed that a constant amplitude voltage threshold is set for all the difference voltage signal amplitudes in the preprocessing, and the condition that no voltage exists in all the difference voltage signals is excluded. Moreover, what is necessary is just to determine suitably about the regulation value used by an amplitude voltage threshold value and a connection state determination process according to a sampling period or the noise generation form.

  First, the differential voltage signal (R phase-S phase, S phase-T phase, T phase-R phase) of each phase is measured (step S1), and the signal amplitude of each measured differential voltage signal is calculated from the result, Each signal amplitude value and the magnitude relation between each signal amplitude are stored in a storage area in the microcomputer 18 (step S2). For example, the minimum amplitude value: MINVpp, the intermediate amplitude value: MIDPpp, and the maximum amplitude value: MAXVpp are stored. At this time, if the signal amplitude values are the same, they are stored in MAXVpp, MIDPpp, MINVpp according to a predetermined storage order, and the magnitude relationship of MAXVpp> MINVpp> MINVpp does not necessarily exist.

  If the connection state of the three-phase power supply is a three-wire live line (all live lines), the amplitude values of the differential voltage signals are all “E × √3” as described with reference to FIG. MAXVpp = MINVpp = MINVpp = E × √3, and the difference between the differential voltage signal amplitudes is only “0” (MAXVpp−MINVpp = MAXVpp−MINVpp = MINVpp−MINVpp = 0).

  If the connection state of the three-phase power source is a two-wire live line state, as described with reference to FIG. 3, since the amplitude is “E” is two lines and “E × √3” is one line, MAXVpp = E × √3 and MIdvpp = MINVpp = E, and the difference in the difference voltage signal amplitude is “0” at the minimum and “(E × √3) −E≈E × 0.732” at the maximum.

  If the connection state of the three-phase power supply is a one-wire live line state, as described with reference to FIG. 3, since the amplitude is “E” is two lines and “0” is one line, MAXVpp = MIDIVpp = E MINVpp = 0, and the difference between the differential voltage signals is “0” at the minimum and “E” at the maximum.

  That is, if the above-described amplitude level pattern is used, the connection state of each phase can be specified by determining the difference voltage signal amplitude as follows.

  Therefore, it is determined whether or not each differential voltage signal amplitude stored in step S2 satisfies the first relative amplitude determination condition (step S3). This first relative amplitude determination condition is for determining the three-wire live line state, and the differences between MAXVpp, MIDPpp, and MINVpp (MAXVpp-MIDEVpp, MAXVpp-MINVpp, MINVpp-MINVpp) are all {MINVpp × √3- MINVpp} ÷ 2.

  Specifically, in the case of a one-wire live line state, MINVpp = 0, so that {0 × √3-0} ÷ 2 = 0, and the maximum difference between the differential voltage signals is “E”. Therefore, if the first relative amplitude determination condition is not satisfied and the state is a two-wire live line, since MINVpp = E, {E × √3−E} /2≈E×0.366, which is the difference between the two. Since the maximum difference in voltage signal amplitude is “(E × √3) −E≈E × 0.732”, the first relative amplitude determination condition is not satisfied.

  However, if it is a three-wire live line state, MINVpp = E × √3, so {(E × √3) × √3− (E × √3)} / 2≈E × 0.634, Since the differences of the difference voltage signal amplitudes are all “0”, the first relative amplitude determination condition is satisfied. That is, if it is determined in step S3 that the first relative amplitude determination condition is satisfied, it can be determined that all of the R phase, the S phase, and the T phase are in the live line state, and a notification to that effect is given. (Step S4).

  On the other hand, if it is determined in step S3 that the first relative amplitude determination condition is not satisfied, it is determined whether or not each differential voltage signal amplitude stored in step S2 satisfies the second relative amplitude determination condition ( Step S5). The second relative amplitude determination condition is assumed to satisfy MINVpp−MINVpp ≦ (MINVpp × √3−MINVpp) / 2, or MAXVpp−MINVpp ≧ (MIdvpp × √3−MIDPpp) ÷ 2.

  More specifically, in the case of a one-line live line state, since MAXVpp = MINVpp = E and MINVpp = 0, E−0 ≦ (0 × √3−0) ÷ 2 = E ≦ 0, or E−E ≧ (E × √3−E) /2≈0≧E×0.366, which does not satisfy the second relative amplitude determination condition.

  However, in the case of a two-wire live line state, MAXVpp = E × √3 and MIdvpp = MINVpp = E, so that E−E ≦ (E × √3−E) ÷ 2≈0 ≦ E × 0.366. Or, E × √3−E ≧ (E × √3−E) /2≈E×0.732≧E×0.366, which satisfies the second relative amplitude determination condition. Since the difference voltage signal amplitude between the live wire phases becomes the maximum amplitude value, when MAXVpp is the difference voltage signal amplitude between the S phase and the T phase, the R phase is missing, and the S phase and the T phase are When it can be determined as a live line and MAXVpp is the difference voltage signal amplitude between T phase and R phase, it can be determined that S phase is open phase, R phase and T phase are live lines, and MAXVpp is between R phase and S phase. When it is the difference voltage signal amplitude, it can be determined that the T phase or the open phase, the R phase and the S phase are live lines, and this is notified (step S6).

  On the other hand, if it is determined in step S5 that the second relative amplitude determination condition is not satisfied, it is determined whether each differential voltage signal amplitude stored in step S2 satisfies the third relative amplitude determination condition ( Step S7). It is assumed that the third relative amplitude determination condition is MINVpp−MINVpp ≧ (MINVpp × √3−MINVpp) / 2 and MAXVpp−MINVpp ≦ (MINVpp × √3−MINVpp) ÷ 2.

  That is, in the case of a one-wire live line state, since MAXVpp = MINVpp = E and MINVpp = 0, E−0 ≧ (0 × √3−0) ÷ 2 = E ≧ 0 and E−E ≦ (E × √3−E) ÷ 2≈0 ≦ E × 0.366, which satisfies the third relative amplitude determination condition. Since the difference voltage signal amplitude between the open phases becomes the minimum amplitude value, when MINVpp is the differential voltage signal amplitude between the S phase and the T phase, the R phase is a live line, and the S phase and the T phase are open phases. MINVpp is the difference voltage signal amplitude between the T phase and the R phase, it can be determined that the S phase is a live line, the R phase and the T phase are open phases, and the MINVpp is a difference voltage between the R phase and the S phase. If it is the signal amplitude, it can be determined that the T phase is a live line, and the R phase and the S phase are open phases, and this is notified (step S8).

  Furthermore, if the condition of the third relative amplitude determination condition does not apply in step S7, it is determined that an abnormal signal has been input due to the influence of noise and voltage imbalance, and a determination abnormality is informed ( Step S9). As described above, if the connection state is determined based on the first to third relative amplitude determination conditions, it is possible to avoid erroneous determination of an abnormal measurement result in which an open phase cannot be specified, and the reliability becomes high. If this high-accuracy connection state determination function is installed in a voltage detector or phase detector, it is less affected by the voltage to ground and the state at the time of measurement, and the connection state can be determined accurately. It becomes highly reliable as a voltage detector or phase detector.

  As described above, according to the connection state determination device of the present embodiment, the connection state of the three-phase power supply can be determined with high accuracy in a short measurement time of one cycle or more. In addition, although the connection state can be determined even from the measurement of the difference voltage waveform of one cycle, in order to improve the accuracy, the measurement period is set long (for example, the measurement period of two cycles or more is set) or multiple times By detecting the crossing voltage signal and reporting all the detection results as the same determination result, this can be reported as the final determination result, so that a more accurate connection state determination can be performed. it can. Moreover, the connection state determination conditions used for determination are not limited to those using the first to third relative amplitude determination conditions described above, and may be set as appropriate. For example, if it is sufficient to determine only the presence / absence of an open phase, only the first relative amplitude determination condition may be set as the connection state determination condition.

  Moreover, although the connection state determination apparatus of this embodiment shall perform the determination of a connection state with respect to the star connection three-phase power supply, the three-phase power supply which is the object of a connection state determination is not limited to this. In addition, it can be used for a three-phase power source of other specifications such as delta connection. Furthermore, in this embodiment, the function of the connection state determination unit is realized by a microcomputer, but the function of the connection state determination unit may be configured by an analog circuit.

  The embodiment of the connection state determination device to which the connection state determination method of the three-phase power supply according to the present invention has been described above based on the accompanying drawings, but the inclusion range of the present invention is limited to this embodiment Instead, it may be realized by appropriately diverting known methods.

14 Conductor under test (3-phase power supply: R phase, S phase, T phase)
15 Device body (voltage detector or phase detector)
16 Non-contact sensor 17 Connection state determination circuit 17c Difference voltage generation means 18 Microcomputer (connection state determination means)

Claims (2)

  Acquire the correlation voltage signal of each phase in the three-phase power supply, generate three kinds of difference voltage signals that are the difference between the voltage signals of each phase, measure each difference voltage signal continuously for a measurement period of one cycle or more, By determining the amplitude level pattern of each difference voltage signal within the measurement period under predetermined connection state determination conditions based on the amplitude level pattern of each difference voltage signal generated according to the connection state of the three-phase power supply A method for determining a connection state of a three-phase power supply, wherein the connection state of the three-phase power supply is determined. Phase signal acquisition means for acquiring a correlation voltage signal of each phase in a three-phase power supply;
Difference voltage signal generation means for generating three types of difference voltage signals, which are differences between the voltage signals of the respective phases acquired by the phase signal acquisition means;
Based on the amplitude level pattern of each difference voltage signal generated according to the connection state of the three-phase power supply, the amplitude level pattern of each difference voltage signal in the measurement period is determined under a predetermined connection state determination condition. By means of connection state determination means for determining the connection state of the three-phase power supply,
A connection state determination device for a three-phase power source, comprising:

Images