JP5221238B2 - Reactive power compensator ground fault detector - Google Patents

Description

  The present invention relates to a reactive power compensator that compensates reactive power of AC power flowing through an AC power system using a thyristor controlled reactor, and in particular, components such as wiring of the reactive power compensating device itself. The present invention relates to a ground fault detection device for a reactive power compensator that detects a ground fault.

  In general, as a reactive power compensator for compensating reactive power due to a phase difference of a current waveform with respect to a voltage waveform of AC power flowing through an AC power system, various methods have been put into practical use. A reactive power compensator adopting a thyristor controlled reactor method is shown.

  A thyristor control reactor 2, which is Δ-connected, is connected to a three-phase AC power system 1 a composed of three phases of U, V, and W. In the thyristor control reactor 2, as shown in the figure, three series circuits in which a pair of thyristors 4 connected in parallel with opposite polarities are interposed between the pair of coils 3 a and 3 b are Δ-connected.

  Further, the voltage of each phase of the three-phase AC power system 1 b is measured by a PT (voltage detector) 5 and sent to the thyristor control unit 7. Further, the current of each phase of the three-phase AC power system 1 b is measured by a CT (current detector) 6 and sent to the thyristor controller 7. The thyristor control unit 7 calculates the firing angle of the thyristor 4 for realizing the necessary reactive power from the detected voltage value and current value of each phase, and adjusts the reactive power by controlling the thyristor 4 to be energized. To do.

  In addition, when the zero-phase voltmeter 8 is provided in the three-phase AC power system 1a and the obtained zero-phase voltage exceeds the allowable value, it is determined that one of the three phases U, V, and W is grounded. it can.

  Further, Patent Document 1 proposes a static reactive power compensator in which a coil, a capacitor, and a thyristor are incorporated.

  FIG. 13 is a schematic configuration diagram of another reactive power compensator that employs a thyristor control reactor. In this reactive power compensator, the primary windings 11a and 11b of the high-impedance three-phase transformer 10 are connected via a circuit breaker 9 to a three-phase AC power system 1b composed of three phases U, V, and W. 11c are connected. Single-phase circuits 13a, 13b, and 13c are connected to secondary windings 12a, 12b, and 12c that are independent of each phase corresponding to the primary windings 11a, 11b, and 11c of the three-phase transformer 10, respectively. A pair of thyristors 14a, 14b, and 14c connected in parallel with opposite polarities are inserted at intermediate positions of the single-phase circuits 13a, 13b, and 13c.

  The single phase circuit 13a is composed of the u phase and the x phase, the single phase circuit 13b is composed of the v phase and the y phase, and the single phase circuit 13c is composed of the w phase and the z phase.

  Further, in the three-phase transformer 10, an electrostatic shield 15 is interposed between each primary winding 11a, 11b, 11c and each secondary winding 12a, 12b, 12c, and each primary winding. It is suppressed that the voltage applied to 11a, 11b, 11c leaks to each secondary winding 12a, 12b, 12c by electrostatic induction.

The thyristor control unit 7 calculates the firing angle of each thyristor 14a, 14b, 14c for realizing the necessary reactive power from the voltage value and current value of each phase detected by PT5, CT6. The thyristors 14a, 14b, and 14c are energized and controlled by the arc angle to adjust the reactive power.
JP-A-8-149694

  However, the reactive power compensator that employs the thyristor control reactor shown in FIG. 13 still has the following problems that should be improved.

  That is, in order to suppress an accident caused by the occurrence of a ground fault in each phase of the three-phase AC power system 1b, the zero-phase voltage (current) detector 8 shown in FIG. When the zero-phase voltage thus set exceeds the allowable value, it is determined that one of the three phases U, V, and W is grounded.

  However, in recent years, in addition to the above-described ground fault detection of the three-phase AC power system 1b, the reactive power compensator malfunctions due to the occurrence of a ground fault in each component such as the wiring of the reactive power compensator itself, In order to prevent a failure from occurring, it is required to detect a ground fault in the reactive power compensator.

  However, the reactive power compensator shown in FIG. 13 has a problem that the conventional method of detecting the zero-phase voltage of the three-phase circuit cannot be adopted as a method of detecting the ground fault of each phase of each single-phase circuit. . Hereinafter, the reason will be described with reference to FIGS.

FIG. 14 shows a waveform of the voltage Vu between the u-phase grounds (solid line) and a waveform of the voltage Vx between the grounds of the x-phase (dotted line) in one single-phase circuit 13a in the reactive power compensator configured as shown in FIG. Are described for each operating condition in the reactive power compensator. In particular,
As energization control for the thyristor 14a in the single-phase circuit 13a,
Not implemented (a) (b), firing angle 100 ° (c) (d) firing angle 150 ° (e) (f)
The conditions are shown. Also, as the presence or absence of ground fault,
Both u phase and x phase ... No ground fault (a) (c) (e) Only x phase ... Ground fault (b) (d) (f)
The conditions are shown. Furthermore, as the presence / absence of a voltage applied to the three-phase transformer 10,
Applied voltage: Yes (a) to (f) Applied voltage: No (g) (h)
Each condition is shown.

  Further, (i), (j), (k), and (l) in FIG. 15 are the electrostatic shields 15 of the three-phase transformer 10 under the conditions (a), (c), (e), and (g) in FIG. The waveform (solid line) of the voltage Vu between the grounds of the u phase under the condition in which is removed, and the waveform (dotted line) of the voltage Vx between the grounds of the x phase are shown.

  As described above, the voltage waveforms of the voltages Vu, Vx, Vv, Vy, Vw, and Vz of the respective phases u, x, v, y, w, and z of the single-phase circuits 13a, 13b, and 13c are high impedance three. Different voltage waveforms depending on the firing angle (100 °, 150 °, etc.) when the phase transformer 10 is not charged or receiving power, while the siries 14a, 14b, 14c are stopped or operating Become.

  Further, as shown in FIG. 15, depending on the presence or absence of the electrostatic shield 15 in the high-impedance three-phase transformer 10, the waveforms of the voltages Vu to Vz of the respective phases u to z of the single phase circuits 13a, 13b and 13c are also obtained. to differ greatly.

  As described above, the voltage waveform of the voltage of each phase to be inspected greatly changes according to each operation state (operation condition) in the reactive power compensator. Since this waveform change is larger than the waveform change with or without the occurrence of ground fault, the conventional zero-phase voltage measurement method cannot detect the ground fault of each phase.

  The present invention has been made in view of such circumstances, and various comparison operations are performed on the peak value of the voltage of each phase of each single-phase circuit connected to each secondary winding of the three-phase transformer. It is an object of the present invention to provide a ground fault detection device for a reactive power compensator that can detect the occurrence of a ground fault in each phase of each single-phase circuit and improve the reliability of the entire device.

  In the present invention, each primary winding of a three-phase transformer is connected between each phase of an AC power system, and a thyristor is inserted between both terminals of each phase independent secondary winding of this three-phase transformer. The reactive power compensator detects the ground fault of each phase of each single-phase circuit in the reactive power compensator that compensates the reactive power of the AC power system by connecting the phase circuit and controlling the firing angle of this thyristor. It is a fault detection device.

  And in order to eliminate the said subject, in the ground fault detection apparatus of Claim 1, the point of the thyristor in the compensation process of the several voltage measuring device which measures the ground voltage in each phase of each single phase circuit, and the reactive power compensation By performing a predetermined comparison calculation process on the peak voltage value of each ground voltage measured by each voltage measuring instrument having a special voltage waveform appearing in each phase of each single-phase circuit due to arc control. A ground fault detector for detecting that a ground fault has occurred in each phase of the single-phase circuit.

  In the ground fault detection device of the reactive power compensator configured as described above, the voltage waveform for one period (one wavelength) determined by the frequency of each phase of each single-phase circuit varies greatly according to each condition. The peak voltage value does not change greatly. As a result, it is possible to specify the occurrence of a ground fault in each phase of each single-phase circuit by performing various comparison calculation processes on this peak voltage value.

  According to a second aspect of the present invention, the ground fault detection unit in the ground fault detection device of the reactive power compensator according to the present invention has a peak voltage value in a period of one cycle of the AC power of the ground voltage measured by each voltage measuring device in advance. When the AC power system is in a power-applied state and below a predetermined lower limit value, a ground fault detection of the phase of the single-phase circuit provided with the voltage measuring device is output.

  In the ground fault detection apparatus configured as described above, when the peak voltage value of the voltage of each phase is equal to or lower than the lower limit value, it is determined that the corresponding phase is grounded.

  According to a third aspect of the present invention, the ground fault detector in the ground fault detector of the reactive power compensator of the present invention is a positive peak in a period of one cycle of the AC power of the ground voltage measured by each voltage measuring device. When the absolute value of the voltage value or the absolute value of the negative peak voltage value is equal to or lower than a predetermined lower limit value and the AC power system is in the power-applied state, the phase ground of the single-phase circuit in which the voltage measuring device is provided Outputs fault detection.

  In such a configuration, the ground fault determination process according to claim 2 is performed by distinguishing the positive side waveform and the negative side waveform in the voltage waveform from each other.

  According to a fourth aspect of the present invention, the ground fault detection unit in the ground fault detection device of the reactive power compensator of the present invention is one of the AC power of the ground voltage measured by the voltage measuring device of one phase of each single-phase circuit. When the peak voltage value in the period of the cycle is equal to or greater than a predetermined upper limit value, ground fault detection of the other phase of the same single-phase circuit is output.

  In the ground fault detection apparatus configured as described above, when the peak voltage value of one phase of two phases of one single-phase circuit is equal to or higher than the upper limit value, it is determined that the other phase is grounded.

  According to a fifth aspect of the present invention, the ground fault detection unit in the ground fault detection device of the reactive power compensator of the present invention has one cycle of the AC power measured by the voltage measuring device of one phase of each single-phase circuit. When the absolute value of the positive peak voltage value or the absolute value of the negative peak voltage value in the period is equal to or greater than a predetermined upper limit value, ground fault detection of the other phase of the same single-phase circuit is output.

  In such a configuration, the ground fault determination process according to claim 4 is performed by distinguishing the positive side waveform and the negative side waveform of the voltage waveform from each other.

  According to a sixth aspect of the present invention, the ground fault detection unit in the ground fault detection device of the reactive power compensator of the present invention is one of the AC power of the ground voltage measured by the voltage measuring device of one phase of each single-phase circuit. The peak in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of the other phase of the same single-phase circuit when the peak voltage value in the period is equal to or higher than a predetermined upper limit value When the voltage value is equal to or lower than a predetermined lower limit value, ground fault detection of the other phase is output.

  In the ground fault detection apparatus configured as described above, when the peak voltage value of one phase of two phases of one single-phase circuit is equal to or higher than the upper limit value and the peak voltage value of the other phase is equal to or lower than the lower limit value, It is judged that this other phase has a ground fault.

  According to a seventh aspect of the present invention, the ground fault detection unit in the ground fault detection device of the reactive power compensator of the present invention is one of the AC power of the ground voltage measured by the voltage measuring device of one phase of each single-phase circuit. When the absolute value of the positive-side peak voltage value or the negative-side peak voltage value in the period of the cycle is greater than or equal to a predetermined upper limit, and the voltage measuring device of the other phase of the same single-phase circuit When the absolute value of the positive-side peak voltage value or the negative-side peak voltage value is less than or equal to a predetermined lower limit value during one cycle of the AC power of the measured ground voltage, the ground fault of the other phase Output detection.

  In such a configuration, the ground fault determination process according to claim 6 is performed by distinguishing the positive side waveform and the negative side waveform of the voltage waveform from each other.

  Further, in claim 8, the ground fault detection unit in the ground fault detection device of the reactive power compensator of the present invention is the AC power of the ground voltage measured by the voltage measuring device of one phase of the same single phase circuit. The deviation voltage value between the peak voltage value in one cycle period and the peak voltage value in one cycle period of the AC power of the ground voltage measured by the voltage measuring device of the other phase is greater than or equal to a predetermined allowable value. Output a ground fault detection of any one phase of the single-phase circuit.

  In such a configuration, when the voltage deviation between the two phases constituting one single-phase circuit becomes equal to or greater than an allowable value, one of them is grounded.

  In the ninth aspect of the present invention, the ground fault detection unit in the ground fault detection device of the reactive power compensator of the present invention is the AC power of the ground voltage measured by the voltage measuring device of one phase of the same single-phase circuit. Deviation between the absolute value of the positive peak voltage value in the period of one cycle and the absolute value of the negative peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of the other phase When the voltage value is equal to or greater than a predetermined allowable value, or the absolute value of the negative peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of one phase and the other When the deviation voltage value from the absolute value of the positive-side peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the phase voltage measuring device is equal to or greater than a predetermined allowable value, the other of the single-phase circuit Outputs the ground fault detection of the phase.

  In such a configuration, the ground fault determination process according to claim 8 is performed by distinguishing between the positive side waveform and the negative side waveform in the voltage waveform.

  Further, in claim 10, each voltage measuring device in the ground fault detection device of the reactive power compensator of the present invention is a secondary of a single-phase transformer inserted between each phase of each single-phase circuit and the ground. It is connected between both terminals of the load adjusting resistor connected between both terminals of the winding.

  In this way, by providing a resistance for adjusting the load, the influence of the transition voltage due to electrostatic induction from the primary winding to the secondary winding of the single-phase transformer is suppressed, and the voltage of each phase is averaged. Thus, the ground fault detection accuracy of each phase can be improved.

  In the eleventh aspect of the invention, a plurality of harmonic removal filters are provided for removing harmonic components contained in the ground voltage measured by each voltage measuring device in the ground fault detection device of the reactive power compensator of the present invention. .

  In this way, the harmonic removal filter removes harmonic components such as noise other than the operating conditions of the reactive power compensator described above, which are included in the ground voltage measured by the voltage measuring instrument. The ground fault detection accuracy can be further improved.

  In the present invention, even if the voltage waveform of the voltage of each phase of each single-phase circuit in the reactive power compensator is significantly changed according to various operating conditions in the reactive power compensator, each of the single-phase circuits The ground fault of the phase can be reliably detected, and the reliability of the reactive power compensator can be greatly improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing an overall configuration of a reactive power compensator in which a ground fault detection device according to a first embodiment of the present invention is incorporated. The ground fault detection apparatus of this embodiment is incorporated in the reactive power compensator shown in FIG. Therefore, the reactive power compensator shown in FIG. 1 has the same configuration as the reactive power compensator shown in FIG. Therefore, detailed description of the overlapping parts is omitted.

  In the first embodiment device, the primary windings 11a, 11b, and 11c of the three-phase transformer 10 are connected to the three-phase AC power system 1 via the circuit breaker 9. Single-phase circuits 13a, 13b, and 13c are connected to the independent secondary windings 12a, 12b, and 12c corresponding to the primary windings 11a, 11b, and 11c of the three-phase transformer 10, respectively. A pair of thyristors 14a, 14b, and 14c connected in parallel with opposite polarities are inserted at intermediate positions of the single-phase circuits 13a, 13b, and 13c.

  The single phase circuit 13a is composed of the u phase and the x phase, the single phase circuit 13b is composed of the v phase and the y phase, and the single phase circuit 13c is composed of the w phase and the z phase.

  In the three-phase transformer 10, an electrostatic shield 15 is interposed between the primary windings 11a, 11b, and 11c and the secondary windings 12a, 12b, and 12c.

  The thyristor control unit 7 is connected to points of the thyristors 14a, 14b, and 14c for realizing the reactive power required from the voltage value and current value of each phase detected by the PT (voltmeter) 5 and the CT (ammeter) 6. An arc angle is calculated, and the thyristors 14a, 14b, and 14c are energized and controlled at this ignition angle to adjust reactive power.

  Therefore, the voltage between the grounds of each phase u, x, v, y, w, z of each single-phase circuit 13a, 13b, 13c, and the voltage waveform of Vu, Vx, Vv, Vy, Vw, Vz are shown in FIG. As shown in FIG. 15, various changes are made according to various operating conditions in the reactive power compensator.

  Next, the ground fault detection apparatus incorporated in the reactive power compensator having such a configuration will be described. A single-phase transformer 16 is interposed between each phase u, x, v, y, w, z of each single-phase circuit 13a, 13b, 13c and the ground. A voltage measuring device 17 for measuring each voltage Vu, Vx, Vv, Vy, Vw, Vz between the grounds of u, x, v, y, w, z is connected to the next winding. The six voltages Vu, Vx, Vv, Vy, Vw, and Vz measured by each voltage measuring device 17 are sent to the ground fault detection unit 18, for example.

  Further, when the voltage is detected by the PT (voltmeter) 5, the applied voltage detection circuit 19 applies a high level voltage to the ground fault detector 18 because the voltage is applied to the three-phase transformer 10. An electric status signal a is sent out. Furthermore, if no voltage is detected by the PT (voltmeter) 5, the applied voltage detection circuit 19 is not applied with voltage to the three-phase transformer 10, and therefore the ground fault detection unit 18 is not charged with a low level. Send status. When the ground fault detection unit 18 detects a ground fault in each phase u to z of each single-phase circuit 13a, 13b, 13c, it outputs a cutoff command b to each circuit breaker 9, and makes the reactive power compensator three-phase AC. Disconnect from power system 1.

  In the ground fault detector 18, as shown in FIG. 2, a total of six phase ground fault detectors 20 for each phase u, x, v, y, w, z of each single-phase circuit 13a, 13b, 13c. Is incorporated. Since each phase ground fault detection unit 20 has the same configuration, the u phase phase ground fault detection unit 20 will be described as an example.

  For example, the voltage Vu of the voltage waveform having the positive side component and the negative side component shown in FIG. 14 that changes with time of the u phase measured by the u phase voltage measuring device 17 of each single-phase circuit 13a is removed by harmonics. After the high-frequency noise component is removed by the filter 35, the absolute value calculation unit 21 and the one-cycle holding unit 23 correspond to a period corresponding to one cycle of the three-phase AC power system 1 (0.02 seconds at 50 Hz). The absolute value | Vu | indicating the one-sided amplitude of the voltage waveform is calculated.

  Then, the absolute value | Vu | of the u-phase voltage Vu calculated over this one cycle (0.02 seconds at 50 Hz) is calculated by the next level detection unit 22 in the absolute value | Vu | Is less than or equal to a predetermined lower limit value VK. That is, it indicates that it is determined whether or not the peak voltage value in one period of AC power of the measured voltage Vu is equal to or lower than a predetermined lower limit value VK.

  And the determination result confirms that the same determination result is output by the state confirmation part 24 continuously for 5 seconds, for example. In the case of 50 Hz as described above, a high-level u-phase ground fault signal is applied to one input terminal of the next AND gate 25 when the peak voltage value is lower than the lower limit value VK for 250 consecutive times. . It should be noted that the state confirmation unit 24 prevents erroneous generation of a ground fault even if a voltage waveform having a peak voltage value equal to or lower than the lower limit value VK occurs due to noise or the like.

  The applied voltage signal a is applied from the applied voltage detection circuit 19 to the other input terminal of the AND gate 25. Therefore, the AND gate 25 has a high-level u-phase input from the state confirmation unit 24 under the condition that a high-level applied state signal a indicating the applied state to the three-phase transformer 10 is applied. The ground fault signal c is output from the u-phase phase ground fault detector 20. The high-level u-phase ground fault signal c output from the u-phase phase ground fault detection unit 20 is input to the cutoff output unit 27 via the OR gate 26. The cutoff output unit 27 sends a cutoff command to each of the circuit breakers 9. b is output, and the reactive power compensator is disconnected from the three-phase AC power system 1.

  In the state where no voltage is applied to the three-phase transformer 10, the voltage Vu is unconditionally 0 as shown in FIGS. 14 (g) and 14 (h). The output of the phase ground fault signal c is prevented.

  In this way, the u-phase phase ground fault detection unit 20 has the absolute value | Vu | as the peak voltage value in the period of one cycle of the AC power of the voltage Vu measured by the u-phase voltage measuring device 17 as the lower limit value. When the AC power system 1 is in the applied state, the u-phase ground fault detection signal c of the single-phase circuit 13a provided with the voltage measuring device 17 is output and the reactive power compensator is set to the three-phase AC power. Disconnect from system 1.

  Each of the x, v, y, w, and z phase ground fault detection units 20 other than the u phase incorporated in the ground fault detection unit 18 of FIG. Detects the occurrence of a ground fault in the phase.

  In the ground fault detection device of the reactive power compensator of the first embodiment configured as described above, the voltage waveform of each phase of each single-phase circuit 13a, 13b, 13c is in accordance with each condition as shown in FIG. Although it varies greatly, the absolute value | Vu | as the peak voltage value does not vary greatly. Therefore, when the peak voltage value of the voltage of each phase is equal to or lower than the lower limit value VM, it can be determined that the corresponding phase is grounded, so that the ground fault of each phase can be reliably detected.

(Second Embodiment)
FIG. 3 is a schematic configuration diagram of the u-phase phase ground fault detection unit 20a incorporated in the ground fault detection unit 18 of the ground fault detection device according to the second embodiment of the present invention. The same parts as those of the u-phase phase ground fault detection unit 20 of the first embodiment shown in FIG. 2 are denoted by the same reference numerals, and detailed description of the overlapping parts is omitted. Other configurations are the same as those of the first embodiment.

  In the second embodiment, the voltage waveform having a positive-side component and a negative-side component shown in FIG. 14, for example, that changes with time of the u-phase measured by the u-phase voltage measuring device 17 of the single-phase circuit 13a. The voltage Vu is divided into a positive voltage Vup and a negative voltage Vun by the positive / negative divider 28 after the high frequency noise component is removed by the harmonic elimination filter 35.

  Whether or not the absolute value | Vup | as the peak voltage value for one cycle of the positive side voltage Vup is equal to or lower than the lower limit value VK is determined by the absolute value calculation unit 21a, the one cycle holding unit 23a, and the level detection unit 22a. judge. Also, whether or not the absolute value | Vun | as the peak voltage value for one cycle of the negative voltage Vun is equal to or lower than the lower limit value VK in the absolute value calculation unit 21b, the one cycle holding unit 23b, and the level detection unit 22b. judge.

  The determination results of the positive side voltage Vup and the negative side voltage Vun are logically summed by the OR gate 29 and applied to one input terminal of the next AND gate 25. The applied voltage signal a is applied from the applied voltage detection circuit 19 to the other input terminal of the AND gate 25. Therefore, the AND gate 25 has the peak voltage value of the positive side voltage Vup or the negative side voltage Vun under the condition that the high level applied state signal a indicating the applied state to the three-phase transformer 10 is applied. When the peak voltage value becomes equal to or lower than the lower limit value VK, a high-level u-phase ground fault signal is output from the u-phase phase ground fault detection unit 20a.

  The subsequent operation is the same as that of the u-phase phase ground fault detection unit 20 of the first embodiment shown in FIG. Therefore, substantially the same effect as the ground fault detection device of the first embodiment described above can be obtained.

  Furthermore, in the second embodiment, the ground fault determination of each phase is performed by distinguishing between the positive waveform and the negative waveform in the voltage waveform, so that the ground fault factor can be clarified in more detail.

(Third embodiment)
FIG. 4 is a diagram showing an overall configuration of a reactive power compensator in which a ground fault detection device according to a third embodiment of the present invention is incorporated. The same parts as those in the first embodiment shown in FIG.

  In the ground fault detection apparatus according to the third embodiment, the applied voltage detection circuit 19 in FIG. 1 is not provided.

  In the ground fault detection unit 18 in the ground fault detection device of the third embodiment, as shown in FIG. 5, for each phase u, x, v, y, w, z of each single-phase circuit 13a, 13b, 13c. A total of six phase ground fault detectors 20b are incorporated. However, the x-phase voltage Vx is input to the u-phase phase ground fault detection unit 20b, and the u-phase voltage Vu is input to the x-phase phase ground fault detection unit 20b. Thus, the voltage of the other phase belonging to the single-phase circuit to which the phase belongs is input to each phase ground fault detection unit 20b. The u phase phase ground fault detection unit 20b will be described as an example.

  For example, the voltage Vx of the voltage waveform having the positive side component and the negative side component shown in FIG. 14 after the high frequency noise component is removed by the harmonic elimination filter 35, the absolute value calculating unit 21, The absolute value | Vx | as a peak voltage value for one cycle is obtained by the one-cycle holding unit 23. Then, the level detection unit 30 determines whether or not the absolute value | Vx | as the peak voltage value for one cycle is equal to or greater than a predetermined upper limit value VM. The state confirmation unit 24 confirms that the determination result is continued for 5 seconds.

  That is, when the absolute value | Vx | as the peak voltage value for one cycle is greater than or equal to a predetermined upper limit VM, it belongs to the same single-phase circuit 13a as shown in FIGS. Since it is assumed that the u phase is grounded, after confirming that the ground fault state of the u phase is continued for 5 seconds, the ground fault signal c of the high level u phase is detected. Output from the unit 20b.

  The subsequent operation is the same as that of the u-phase phase ground fault detection unit 20 of the first embodiment shown in FIG. Therefore, substantially the same effect as the ground fault detection device of the first embodiment described above can be obtained.

  Similarly, the ground fault of the x phase of the same single phase circuit 13a can be detected by the u phase voltage Vu measured by the u phase voltage measuring device 17 of the single phase circuit 13a.

(Fourth embodiment)
FIG. 6 is a schematic configuration diagram of a u-phase phase ground fault detection unit 20c incorporated in the ground fault detection unit 18 of the ground fault detection device according to the fourth embodiment of the present invention. The same parts as those of the u-phase phase ground fault detection unit 20b of the third embodiment shown in FIG. 5 are denoted by the same reference numerals, and detailed description of the overlapping parts is omitted. Other configurations are substantially the same as those of the first and third embodiments.

  In the fourth embodiment, a voltage waveform having a positive-side component and a negative-side component shown in FIG. 14, for example, that changes with time in the x-phase measured by the x-phase voltage measuring device 17 of the single-phase circuit 13a. The voltage Vx is divided into a positive voltage Vxp and a negative voltage Vxn by the positive / negative divider 28 after the high frequency noise component is removed by the harmonic elimination filter 35.

  Then, the absolute value calculation unit 21a, the one cycle holding unit 23a, and the level detection unit 30a determine whether the absolute value | Vxp | as the peak voltage value for one cycle of the positive side voltage Vxp is equal to or higher than the upper limit value VM. .

  Similarly, the absolute value calculation unit 30b, the one cycle holding unit 23b, and the level detection unit 30b determine whether the absolute value | Vxn | as the peak voltage value for one cycle of the negative side voltage Vxn is equal to or higher than the upper limit value VM. To do.

  Then, each determination result of the positive side voltage Vxp and the negative side voltage Vxn is logically ORed by the OR gate 29, and the next state check unit 24 confirms that the same determination result such as 5 seconds has continued.

  That is, when the absolute value | Vxp |, | Vxn | as the peak voltage value of either the positive side voltage Vxp or the negative side voltage Vxn of the x-phase voltage Vx is equal to or higher than the upper limit value VM, A high-level u-phase ground fault signal c indicating that a fault has occurred is output from the u-phase ground fault detector 20c.

  The subsequent operation is the same as that of the u-phase phase ground fault detection unit 20 of the first embodiment shown in FIG. Therefore, substantially the same effect as the ground fault detection device of the first embodiment described above can be obtained.

(Fifth embodiment)
FIG. 7 is a schematic configuration diagram of the ground fault detection unit 18 of the ground fault detection apparatus according to the fifth embodiment of the present invention. The same parts as those of the u-phase phase ground fault detection unit 20b of the third embodiment shown in FIG. 5 are denoted by the same reference numerals, and detailed description of the overlapping parts is omitted. Other configurations are substantially the same as those of the first and third embodiments.

  In the ground fault detector 18 of the fifth embodiment, a total of six phase ground fault detectors 20c for each phase u, x, v, y, w, z of each single-phase circuit 13a, 13b, 13c are provided. It is incorporated. However, the x-phase voltage Vx and the u-phase voltage Vu are input to the u-phase phase ground fault detection unit 20c, and the u-phase voltage Vu and the x-phase voltage Vx are input to the x-phase phase ground fault detection unit 20c. Are entered. Thus, each phase ground fault detector 20c receives the voltages of the two phases belonging to the single-phase circuit to which the phase belongs. The u-phase ground fault detector 20c will be described as an example.

  For example, the voltage Vx of the voltage waveform having the positive side component and the negative side component shown in FIG. 14 that changes with time measured by the x phase voltage measuring device 17 of the single phase circuit 13a is a harmonic elimination filter. After the high-frequency noise component is removed in 35, the absolute value calculation unit 21 and the 1-cycle holding unit 23 obtain an absolute value | Vx | as a peak voltage value for one cycle, and the level detection unit 30 It is determined whether the absolute value | Vx | as a peak voltage value for one cycle is equal to or greater than a predetermined upper limit VM.

  Further, for example, the voltage Vu of the voltage waveform having the positive side component and the negative side component shown in FIG. 14 which changes with time measured by the u-phase voltage measuring device 17 of the single-phase circuit 13a is a harmonic. After the high-frequency noise component is removed by the removal filter 35, the absolute value | Vu | as a peak voltage value for one cycle is obtained by the absolute value calculation unit 21 and the one-cycle holding unit 23, and the level detection unit 22 It is determined whether the absolute value | Vu | as the peak voltage value for one cycle is equal to or lower than a predetermined lower limit value VK.

  When the x-phase peak voltage value is equal to or higher than the upper limit value VM and the supplemental u-phase peak voltage value is equal to or lower than the lower limit value, the AND gate 31 is established, and the high-level u-phase ground fault signal is in the state It is sent to the confirmation unit 24. For example, after confirming that the high-level u-phase ground fault signal continues for 5 seconds, the state confirmation unit 24 detects a high-level u-phase ground fault signal c from the u-phase phase ground fault detection unit 20c. Is output.

  Thus, when the peak voltage value of one phase belonging to the same single-phase circuit is low and the peak voltage of the other phase is high, it is determined that the phase with the lower peak voltage is grounded. Detecting ground faults. Accordingly, it is possible to achieve substantially the same operational effects as the above-described embodiments.

(Sixth embodiment)
FIG. 8 is a schematic configuration diagram of a u-phase phase ground fault detection unit 20d incorporated in the ground fault detection unit 18 of the ground fault detection device according to the sixth embodiment of the present invention. The same parts as those of the u-phase phase ground fault detection unit 20c of the fifth embodiment shown in FIG. 7 are denoted by the same reference numerals, and detailed description of the overlapping parts is omitted. Other configurations are substantially the same as those of the first and third embodiments.

  In the sixth embodiment, in the u-phase phase ground fault detector 20d, the x component having the positive side component and the negative side component shown in FIG. The phase voltage Vx is divided into the positive side voltage Vxp and the negative side voltage Vxn by the positive / negative division unit 28 after the harmonic component such as noise is removed by the harmonic elimination filter 35, and the absolute value is calculated. The peak voltage values | Vxp | and | Vxn | for one cycle of the positive side voltage Vxp and the negative side voltage Vxn are calculated by the units 21a and 21b and the one cycle holding units 23a and 23b. Then, the level detection units 30a and 30b determine whether the peak voltage values | Vxp | and | Vxn | are equal to or higher than the upper limit value VK.

  Further, the u-phase voltage Vu having a positive side component and a negative side component in the phase ground fault detection unit 20d shown in FIG. After the harmonic components such as noise are removed in 35, the positive / negative divider 28 divides the positive voltage Vup and the negative voltage Vun into absolute value calculators 21a and 21b and a one-cycle holding unit 23a, respectively. , 23b, the peak voltage values | Vup |, | Vun | for one cycle of the positive side voltage Vup and the negative side voltage Vun are calculated. Then, the level detectors 22a and 22b determine whether or not the peak voltage values | Vup | and | Vun | are equal to or lower than the lower limit value VK.

  When the x-phase positive peak voltage value | Vxp | is not less than the upper limit value VK and the u-phase negative peak voltage value | Vun | is not more than the lower limit value VK (and gate 31a), The ground fault is sent to the state confirmation unit 24 via the OR gate 29.

  Even when the negative peak voltage value | Vxn | of the x phase is equal to or higher than the upper limit value VK and the positive peak voltage value | Vup | of the u phase is equal to or lower than the lower limit value VK (and gate 31b), the u phase Is sent to the state confirmation unit 24 via the OR gate 29.

  When the state confirmation unit 24 confirms that the above-described two-phase ground fault determination of the two conditions continues for, for example, 5 seconds or more, the u-phase ground fault detection unit 20d receives the u-phase ground fault detection signal c. Is output.

  Thus, when the peak voltage value of one phase belonging to the same single-phase circuit is low and the peak voltage of the other phase is high, it is determined that the phase with the lower peak voltage is grounded. Detecting ground faults. Accordingly, it is possible to achieve substantially the same operational effects as the ground fault detection device of the fifth embodiment described above.

(Seventh embodiment)
FIG. 9 is a schematic configuration diagram of the ground fault detection unit 18 of the ground fault detection device according to the seventh embodiment of the present invention. Other configurations are substantially the same as those of the first and third embodiments.

  In the ground fault detection unit 18 of the seventh embodiment, the u and x phase ground fault detection units 20e of the single phase circuit 13a, the v and y phase phase ground fault detection units 20e of the single phase circuit 13b, A phase ground fault detector 20e for the w and z phases of the phase circuit 13c is provided.

  In the u- and x-phase phase ground fault detector 20e of the single-phase circuit 13a, the voltages Vu and Vx measured by the voltage measuring devices 17 are individually harmonics such as noise by the harmonic elimination filter 35. After the components are removed, the deviation voltage | Vd | between the peak voltage | Vu | of the u-phase voltage Vu and the peak voltage | Vx | .

  When the deviation voltage | Vd | is equal to or greater than the allowable value VD, the level detection unit 33 determines that a ground fault has occurred in either the u phase or the x phase. Then, the high-level u and x-phase ground fault signals are sent to the state confirmation unit 24. For example, after confirming that the high-level u and x-phase ground fault signals continue for 5 seconds, the state confirmation unit 24 receives the high-level u and x-phase from the u and x-phase ground fault detection unit 20e. The phase ground fault signal c is output.

  In the seventh embodiment having such a configuration, when the voltage deviation between a pair of phases belonging to the same single-phase circuit is greater than or equal to an allowable value, it is determined that one of the phases is grounded, A fault is detected. Accordingly, it is possible to achieve substantially the same operational effects as the above-described embodiments.

(Eighth embodiment)
FIG. 10 is a schematic configuration diagram of the u-phase phase ground fault detection unit 20f incorporated in the ground fault detection unit 18 of the ground fault detection device according to the eighth embodiment of the present invention. The same parts as those of the u- and x-phase phase ground fault detection unit 20e of the seventh embodiment shown in FIG. 9 are denoted by the same reference numerals, and detailed description of the overlapping parts is omitted. Other configurations are substantially the same as those of the first and third embodiments.

  In the eighth embodiment, in the u-phase phase ground fault detection unit 20f of FIG. 10, the harmonic component such as noise is removed from the x-phase voltage Vx by the harmonic removal filter 35, and then the positive / negative division unit 28 And divided into a positive side voltage Vxp and a negative side voltage Vxn. Further, after removing harmonic components such as noise from the u-phase voltage Vu by the harmonic elimination filter 35, the positive / negative division unit 28 divides the u-phase voltage Vu into the positive side voltage Vup and the negative side voltage Vun.

  Then, peak voltage values | Vxp | and | Vxn | for one cycle of the positive side voltages Vxp and Vup, the negative side voltage Vxn and Vun, respectively, with the absolute value calculation units 21a and 21b and the one cycle holding units 23a and 23b. , | Vup |, | Vun |

  Then, the subtraction units 32a and 32b obtain the respective deviation voltages | Vdp | = | Vxp | − | Vun | and deviation voltage | Vdn | = | Vxn | − | Vup |.

  Next, the level detectors 33a and 33b determine whether or not the deviation voltages | Vdp | and | Vdn | are each equal to or greater than the allowable value VD.

  When the deviation voltage | Vdp | obtained by subtracting the u-phase negative peak voltage | Vun | from the x-phase positive peak voltage value | Vxp | is equal to or greater than the allowable value VD, and the x-phase negative side When the deviation voltage | Vdn | obtained by subtracting the peak voltage value | Vup | on the positive side of the u phase from the peak voltage value | Vxn | is equal to or greater than the allowable value VD (OR gate 29), a ground fault has occurred in the u phase. judge.

  The high-level u-phase ground fault signal is sent to the state confirmation unit 24. For example, after confirming that the high-level u-phase ground fault signal continues for 5 seconds, the state confirmation unit 24 detects a high-level u-phase ground fault signal c from the u-phase phase ground fault detection unit 20f. Is output.

  In the eighth embodiment having such a configuration, when a deviation between different polarities (positive and negative) in a pair of phase voltages belonging to the same single-phase circuit is greater than or equal to an allowable value, the value of the deviation is smaller. It is determined that a ground fault has occurred in the phase. Accordingly, it is possible to achieve substantially the same operational effects as the above-described embodiments.

(Ninth embodiment)
FIG. 11 is a diagram showing an overall configuration of a reactive power compensator in which a ground fault detection device according to a ninth embodiment of the present invention is incorporated. The same parts as those in the first embodiment shown in FIG.

  In the ground fault detection device of the tenth embodiment, the single-phase transformer 16 inserted between each phase u, x, v, y, w, z and the ground in each single-phase circuit 13a, 13b, 13c. A load adjusting resistor 34 is connected between both terminals of the secondary winding.

  In this way, by providing the load adjusting resistor 34, the influence of the transition voltage due to electrostatic induction from the primary winding to the secondary winding of the single-phase transformer 16 is suppressed, and the voltage of each phase is averaged. By doing so, the ground fault detection accuracy of each phase can be improved.

The figure which shows the whole structure of the reactive power compensation apparatus with which the ground fault detection apparatus concerning 1st Embodiment of this invention was integrated. The block diagram which shows the structure of the ground fault detection part in the ground fault detection apparatus of the embodiment The u-phase phase ground fault detection unit incorporated in the ground fault detection device according to the second embodiment of the present invention. The figure which shows the whole structure of the reactive power compensation apparatus with which the ground fault detection apparatus concerning 3rd Embodiment of this invention was integrated. The block diagram which shows the structure of the ground fault detection part in the ground fault detection apparatus of the embodiment The block diagram which shows the structure of the phase ground fault detection part of u phase incorporated in the ground fault detection apparatus concerning 4th Embodiment of this invention. The block diagram which shows the structure of the phase ground fault detection part of each phase incorporated in the ground fault detection apparatus concerning 5th Embodiment of this invention. The block diagram which shows the structure of the phase ground fault detection part of u phase incorporated in the ground fault detection apparatus concerning 6th Embodiment of this invention. The block diagram which shows the ground fault detection part structure incorporated in the ground fault detection apparatus concerning 7th Embodiment of this invention. The block diagram which shows the structure of the phase ground fault detection part of u phase incorporated in the ground fault detection apparatus concerning 8th Embodiment of this invention. The figure which shows the whole structure of the reactive power compensation apparatus with which the ground fault detection apparatus concerning 9th Embodiment of this invention was integrated. General reactive power compensator configuration diagram Schematic configuration diagram of reactive power compensator using thyristor controlled reactor The figure which shows the waveform of the voltage between the ground of each phase of each single phase circuit in the reactive power compensator The figure which similarly shows the waveform of the voltage between ground of each phase of each single phase circuit

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 1a, 1b ... Three-phase alternating current power system, 5 ... PT, 6 ... CT, 7 ... Thyristor control part, 9 ... Circuit breaker, 10 ... Three-phase transformer, 13a, 13b, 13c ... Single phase circuit, 14a, 14b, 14c ... Thyristor, 15 ... Electrostatic shield, 16 ... Single-phase transformer, 17 ... Voltage measuring device, 18 ... Ground fault detection unit, 19 ... Voltage detection circuit, 20, 20a, 20b, 20d, 20e, 20f ... Phase ground fault detection unit, 21, 21a, 21b ... Absolute value calculation unit, 22, 22a, 22b, 30, 30a, 30b, 33, 33a, 33b ... Level detection unit, 23, 23a, 23b ... 1 cycle holding unit , 24 ... Status confirmation section, 25, 31 ... AND gate, 26, 29 ... OR gate, 27 ... Cut-off output section, 28 ... Positive / negative division section, 32, 32a, 32b ... Subtraction section, 34 ... Load adjusting resistor, 35 ... Harmonic rejection filter

Claims (11)

Connect each primary winding of the three-phase transformer between each phase of the AC power system, and connect a single-phase circuit with a thyristor inserted between both terminals of the independent secondary winding of this three-phase transformer. And detecting a ground fault in the reactive power compensator for detecting a ground fault in each phase of each single-phase circuit in the reactive power compensator for compensating the reactive power in the AC power system by controlling the firing angle of the thyristor. A device,
A plurality of voltage measuring devices for measuring a ground voltage in each phase of each single-phase circuit;
Due to the ignition control of the thyristor in the reactive power compensation process, the peak voltage value of each ground voltage measured by each voltage measuring device having a special voltage waveform appearing in each phase of each single-phase circuit. A ground fault detection unit for detecting that a ground fault has occurred in each phase of each single-phase circuit by performing a predetermined comparison operation process on the ground fault of the reactive power compensator, Detection device. The ground fault detector is
When the peak voltage value of one period of the AC power of the ground voltage measured by each voltage measuring instrument is equal to or lower than a predetermined lower limit value and the AC power system is in a power-applied state, the voltage measuring instrument is The ground fault detection device for a reactive power compensator according to claim 1, wherein the ground fault detection of the phase of the provided single phase circuit is output. The absolute value of the positive peak voltage value or the absolute value of the negative peak voltage value in the period of one cycle of the AC power of the ground voltage measured by each of the voltage measuring devices is below a predetermined lower limit value, 3. A ground fault detection device for a reactive power compensator according to claim 2, wherein when the AC power system is in a power-applied state, ground fault detection of a phase of a single-phase circuit provided with the voltage measuring device is output. . The ground fault detector is
When the peak voltage value in one period of the AC power of the ground voltage measured by the voltage measuring device of one phase of each single-phase circuit is equal to or higher than a predetermined upper limit value, the other of the same single-phase circuit The ground fault detection device of the reactive power compensator according to claim 1, wherein the ground fault detection of the phase is output. The absolute value of the positive-side peak voltage value or the absolute value of the negative-side peak voltage value in a period of one cycle of the AC power measured by the voltage measuring device of one phase of each single-phase circuit is predetermined. 5. The ground fault detection device for a reactive power compensator according to claim 4, wherein the ground fault detection of the other phase of the same single-phase circuit is output when the upper limit value is exceeded. The ground fault detector is
When the peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of one phase of each single-phase circuit is equal to or greater than a predetermined upper limit value, and the same single-phase circuit When the peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of the other phase of the other phase is equal to or lower than a predetermined lower limit value, the ground fault detection of the other phase is output The ground fault detection apparatus of the reactive power compensator according to claim 1. The absolute value of the positive-side peak voltage value or the negative-side peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of one phase of each single-phase circuit is previously determined. The absolute value of the positive peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of the other phase of the same single-phase circuit when the value is equal to or more than a predetermined upper limit value or 7. The ground fault detection device for a reactive power compensator according to claim 6, wherein when the absolute value of the negative peak voltage value is equal to or less than a predetermined lower limit value, ground fault detection of the other phase is output. . The ground fault detector is
The AC voltage of the ground voltage measured by the voltage measuring device of the other phase and the peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of one phase of the same single phase circuit The ground fault detection of any one phase of the said single phase circuit is output when the deviation voltage value with respect to the peak voltage value in the period of 1 cycle is more than a predetermined tolerance. Fault detection device for reactive power compensator. The ground fault detector is
The absolute value of the positive peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of one phase of the same single-phase circuit and the voltage measuring device of the other phase When the deviation voltage value with respect to the absolute value of the negative peak voltage value in the period of one cycle of the AC power of the ground voltage is equal to or greater than a predetermined allowable value,
Or, the absolute value of the negative peak voltage value in the period of one cycle of the AC power of the ground voltage measured by the voltage measuring device of the one phase and the ground voltage measured by the voltage measuring device of the other phase When the deviation voltage value with respect to the absolute value of the positive peak voltage value in the period of one cycle of the AC power is equal to or greater than a predetermined allowable value,
The ground fault detection device for a reactive power compensator according to claim 1, wherein ground fault detection of the other phase of the single phase circuit is output.   Each voltage measuring instrument is connected between both terminals of a load adjusting resistor connected between both terminals of a secondary winding of a single phase transformer inserted between each phase of each single phase circuit and ground. The ground fault detection device for a reactive power compensator according to any one of claims 1 to 9, wherein the ground fault detection device is used.   11. The reactive power compensator according to claim 1, further comprising a plurality of harmonic removal filters that remove harmonic components contained in the ground voltage measured by each of the voltage measuring devices. Ground fault detection device.

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