JP2644329B2 - Power switchgear - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to a power switching device, and in particular, to a power switching device in which a voltage increase phenomenon is prevented from occurring upon interruption of a small delay current. Related to the device.

(Prior Art) In general, in power transmission lines, shunt reactors are often connected for the purpose of improving the power factor of a system by compensating for reactive power flowing through the ground capacitance of a line or a cable. Also, it is normal for the power transmission system to be connected to a transformer, and this transformer is often in a loaded state. In such a case, the shunt reactor and the load transformer become almost purely inductive loads, and the electric phase of the current is delayed by 90 degrees in electrical angle from the phase of the voltage. A circuit breaker installed for opening and closing such a load cuts off the current near the maximum value of the voltage as shown in FIG. The phenomenon at this time will be described with reference to FIGS.

FIG. 4 shows a typical configuration example of a shunt reactor circuit. That is, in the figure, reference numeral 1 denotes a shunt reactor, and this inductance is LL. 2 is a shunt reactor switching gas circuit breaker (GCB), 3 and 4 are all parallel capacitance components on the power supply side and the load side, and their respective capacitances are Cs and Cl. Reference numerals 5 and 6 denote total series inductance components on the power supply side and the load side, and their values are Ls and Ll. Reference numeral 7 denotes a transformer, and reference numeral 8 denotes a power supply simulating system voltage.

In addition, in order to separate the shunt reactor 1, GC
The phenomenon when B2 is opened will be described with reference to FIGS. 5 and 6. FIG. That is, FIG. 5 shows transient changes in the GCB load side voltage (a) and the GCB current (b) when the shunt reactor is disconnected.

(1) Region I: The alternating current at the commercial frequency attenuates toward the current zero point. The shunt reactor current is usually 100 A, but the power gas circuit breaker has the ability to cut off a maximum of 40 to 50 KA, so the current may be forcibly cut off before reaching the original current zero point. This is called current cutoff, and it is assumed that the current cutoff occurs at time 9 in the example shown in FIG. Also, assume that the instantaneous value of the power supply voltage at this time is 10.

(2) Region II: At time 9 at which the current interruption occurs, the current is not the original current zero point, and at this moment, the current flows through the sun reactor 1. After the current is shut off by the GCB2, the shunt reactor 1 to the load-side capacitance 4
Flows through. As a result, the magnetic energy I ² · IL / 2 stored in the shunt reactor becomes the electric energy v ² · Cl
/ I (I and v are the current flowing through the shunt reactor 1 and the terminal voltage of the load-side capacitance 4), and the cut-off surge voltage 12 peaking at time 11 appears on the load side of the GCB2.
Occurs. The cutting surge voltage 12 oscillates at a frequency of several hundred Hz to several KHz around zero potential, and has a larger amplitude as the cutting current value increases.

On the other hand, a current voltage of a commercial frequency is applied to the power supply side of the GCB2. Therefore, the gap between GCB2 is shown in Fig. 5 (a).
A voltage corresponding to 13 will be applied.

Here, as described above, since the breaking capability of the GCB2 is sufficiently large with respect to the shunt reactor current, the current may be cut off before the distance between the electrodes is sufficiently separated to withstand the voltage 13 between the electrodes. . In this case, insulation breakdown called re-arcing occurs between the electrodes of the GCB2, and a re-arc surge voltage appears in the circuit. In FIG. 5 (a), time 14
, It is assumed that re-arcing has occurred at a gap voltage of 18, and the re-arcing surge voltage is 16.

(3) Region III: When re-arcing occurs and the electrodes of GCB2 are short-circuited, the load-side voltage converges to 17 while oscillating around voltage 17 determined by the ratio of capacitances 3 and 4. At this time, the maximum amplitude 15 becomes (17 + 18), and becomes larger as the cutting surge voltage 12 is larger and the value Cs of the power supply side capacitance 3 is larger. In addition, 18 is usually 0.8 to 0.95 x (12
Value).

On the other hand, when the re-arc occurs, the electric charges stored in the capacitances 3 and 4 are changed from the power supply side capacitance 3 to the power supply side inductance 5.
GCGCB 2 負荷 load side inductance 6 負荷 discharge through the load side capacitance 4, resulting in a high frequency current of several hundred KHz. Further, a shunt reactor current flowing from the current side through the power supply side inductance 5, the GCB2, the load side inductance 6, and the shunt reactor 1 is also generated by the re-arcing. Therefore, a current in which the commercial frequency current and the high frequency current are superimposed flows in the GCB2. The initial amplitude of this high-frequency current is about KA, which is much larger than the reactor current when the GCB is turned on. The high-frequency current gradually attenuates due to the resistance component of the re-arc between the GCB electrodes and other circuit losses.

FIG. 5 (b) shows the GCB current in this case, and FIG. 6 is an enlarged view of the current waveform around time 14 at which the re-arcing occurred. As is clear from the figure, as a result of the superposition of the high-frequency current on the shunt reactor current, a new current zero (21,22,2
3,24,25 ...) appears, at which point the GCB current may be interrupted. Such a current interruption phenomenon is called a high-frequency arc extinguishing phenomenon.

If a high-frequency arc-extinguishing phenomenon occurs, the shunt reactor current is not zero at that moment, and a high-frequency arc-extinguishing surge voltage is generated on the load side of the GCB 2 by the same process as the above-described phenomenon in the region II. The value becomes larger as the occurrence of high-frequency arc extinction is closer to the peak of the shunt reactor current, and may possibly exceed the cutting surge voltage 12 in some cases.

With such a mechanism, when re-arcing to high-frequency arc extinction is repeated, the terminal voltage of the shunt reactor 1 increases sequentially,
It can be very large. This is called a voltage increase phenomenon. When such a voltage increase phenomenon occurs, there is a possibility that the insulation of the reactor and other devices may be threatened in some cases.

If re-arcing occurs and high-frequency extinction does not occur, the current is cut off at the zero point after 1/2 cycle of the commercial frequency. Therefore, in this case, there is no major problem.

As described above, the fundamental cause of abnormal voltages that threaten the insulation of equipment is re-arcing. Therefore, if the occurrence of re-arcing can be prevented, it is possible to prevent the occurrence of an abnormal voltage at the time of interruption of the small delay current. Here, for example, CIGRE International Conference
on Large High Voltage Electric Systems 1988 Sessi
on paper 13-16 “APPLICATION OF NETAL OXI
DE VARISTORS ON AN 800KV CIRCUIT BREAKER USED FOR
As described in "SHUNT REACTOR SWITCHING", etc., the occurrence of re-arcing is closely related to the arc time.The switchgear is determined by the equipment. Therefore, if the arc time is longer than this, re-arcing cannot occur, so if the opening time of the switchgear is controlled to artificially set the arc time during which re-arcing cannot occur, occurrence of re-arcing can be prevented. This can prevent the occurrence of abnormal voltage that threatens the insulation of the equipment.
ence on Large High Voltage Electric System 1988 Se
ssion paper 13-12 “SYNCHRONOUS ENERGIZIN
G OF SHUNT REACTORS AND SHUNT CAPACITORS ".

In a three-phase balanced circuit usually used in power systems,
The phase difference between the phases is shifted by 120 ° in electrical angle, and the current zero point occurs by 60 ° in electrical angle. Therefore, when the three-phase circuit is cut off, if the circuit breakers of each phase are driven with a time difference corresponding to the electrical angle of 60 °, re-arcing can be realized in all phases.

(Problems to be Solved by the Invention) However, in recent power circuit breakers, an operation method of collectively driving the three-phase arc-extinguishing chambers has been required due to a demand for downsizing of equipment and a reduction in the number of parts. It is becoming popular. In such a three-phase batch drive circuit breaker, it is difficult to perform a shut-off operation with a time difference between the phases. Must be equipped with a drive unit.
There is a drawback that the number of parts cannot be reduced.

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a power switch capable of preventing the occurrence of re-arcing when a shunt reactor current is interrupted. It is to provide a device.

[Structure of the Invention] (Means for Solving the Problems) The power switchgear of the present invention uses a single drive device to determine the time at which the electrodes of the arc extinguishing chambers of each phase in the three-phase circuit are opened. The time difference between the first phase and the second phase, and the time between the second phase and the third phase, which is the shortest time, corresponds to the electrical angle of the commercial frequency of 60 °. Time so that the time at which the contacts of the first phase are disconnected is earlier than the zero point of the current flowing through that phase by a time corresponding to 100 to 170 ° in electrical angle of the commercial frequency. The command is controlled.

(Operation) In the power switchgear of the present invention, the time at which the electrodes of the arc extinguishing chambers of each phase open in the three-phase circuit corresponds to an electrical angle of 60 ° of the AC voltage frequency while using a single driving device. As a result, the arc time can be set to a value which does not cause re-arcing in the arc extinguishing chambers of all three phases.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to FIGS. 1 and 2. The same members as those of the conventional circuit breaker shown in FIG. 3 and below are denoted by the same reference numerals, and description thereof is omitted.

First Embodiment In the present embodiment, as shown in FIG. 1, a control circuit is configured to shunt a single shutoff control command and to guide the shunt to a shutoff coil of each phase. That is, the contact 32 is connected to the power supply circuit 31, and by turning on the contact 32, the cut-off coils 33a, 33b, 33c of each phase that drive an operation mechanism (not shown) to perform the cut-off operation of the circuit breaker. It is configured so that instructions can be transmitted. The circuit for transmitting the shutoff command to each phase is provided with delay circuits 35a, 35b and 35c composed of waveform shaping circuits 34a, 34b and 34c and CR.

The delay time of each of the delay circuits 35a to 35c is set to a different value for each phase.
The difference in the time required until the cutoff designation is given to .about.33c is shifted by 60 degrees in terms of the electrical angle of the commercial frequency. Further, in the arc extinguishing chamber of the circuit breaker (not shown), the moment when the contact is opened is, for example, CIGRE In.
ternational Conference on Large High Voltage Elect
RIC System 1988 Session Paper 13-12 “SYN
CHRONOUS ENERGIZING OF SHUNT REACTORS AND SHUNT CA
PACITORS "and the like, controlled by a phase control device, and an electrical angle of 100 ° to 1 ° with respect to the zero point of the current flowing through each phase.
It is set to be earlier by a time equivalent to 70 ゜.

In the power switchgear of the present embodiment having the above configuration, the time at which the contacts of the arc extinguishing chambers of each phase are opened can be shifted by a time corresponding to the electrical angle of 60 ° at the frequency of the AC voltage. . On the other hand, in the three-phase balanced circuit, the voltage and the current deviate from each other by 120 ° in terms of electrical angle. However, if only the absolute value is considered regardless of the polarity, the voltage and current deviate by 60 ° in electrical angle. Therefore, the current phase at the time when the contacts of the circuit breaker of this embodiment are opened is set to be substantially equal for the three-phase circuit.

It is generally well-known that in the case of interruption of a small delay current, a re-arc does not occur within a time range in which the arc time corresponds to an electrical angle of 100 ° to 170 ° of the AC voltage frequency. Therefore, if the phase control of the shutoff command is performed in the a-phase arc-extinguishing chamber so that the contacts are opened before the time corresponding to the electrical angle of 100 ° to 170 ° before the current zero point, the b-phase and the c-phase are controlled. In the arc extinguishing chamber, almost the same phase control is performed. As a result, for all three phases, the arc time can be set to a time corresponding to the electrical angle of 100 ° to 170 ° of the AC voltage frequency.

As described above, according to the present embodiment, the time when the electrodes of the arc extinguishing chambers of each phase open in the three-phase circuit is set to the time corresponding to the electrical angle of 60 ° of the AC voltage frequency while using a single driving device. As a result, the arc time can be set to a value that does not cause re-arcing in all three-phase arc-extinguishing chambers, so that downsizing and the number of parts can be reduced. In addition, it is possible to prevent occurrence of an abnormal voltage at the time of interrupting the small delay current.

It should be noted that the present invention is not limited to the above-described embodiment, and similar effects can be obtained even if the delay circuits are not provided in all three phases, but are provided in only the b and c phases.

Second Embodiment In this embodiment, as shown in FIG. 2, a case where a hydraulic circuit having a hydraulic cylinder of a differential piston type is used as an opening / closing operation mechanism of a circuit breaker is shown. That is,
The main part of the hydraulic mechanism is a hydraulic pressure generator 41, an accumulator
42, hydraulic cylinders 44a, 4 connected to opening / closing parts 43a, 43b, 43c
4b, 44c, etc. The hydraulic pressure generating device 41 is a device for supplying high-pressure hydraulic oil for opening and closing a hydraulic cylinder, and includes a pump 45, an electric motor 46, a pressure switch 47, an oil tank 48, and the like.

Further, in the hydraulic cylinders 44a to 44c of the differential piston type, the pistons 51a, 51b, and 50b are utilized by utilizing the difference in the effective area between the piston rod side 49a, 49b, 49c and the opposite rod side 50a, 50b, 50c in the cylinder. It is configured to supply or discharge hydraulic oil to the opposite rod side of 51c. That is, hydraulic oil is supplied from the pump 45 to the hydraulic oil port on the rod side, the oil port on the opposite rod side is switched to the oil discharge port by the operation of the operation valve, and the opening direction is changed by the hydraulic oil on the opposite rod side (see FIG. 2). It moves in the piston down direction). In the opposite closing operation, when the operation valve 52 returns, hydraulic oil is supplied from the oil pump or the accumulator to the non-rod side ports 50a to 50c, and the piston is closed. By these operations, the pistons 51a to 51c are driven, and the movable parts of the opening and closing units 43a to 43c are driven to perform the opening and closing operation.

In this embodiment, the transmission time of the high-pressure oil can be made different for each phase by the throttles 53b1, 53b2, 53c1, and 53c2 provided in the hydraulic path. That is, the opening / closing section 43a of the a-phase and the opening / closing section 4 of the b-phase
3b, and the b-phase switch 43b and the c-phase switch 4
3c is set such that the time difference required to start the cutoff operation is a time corresponding to the electrical angle of 60 ° of the commercial frequency.

Further, at the moment when the contacts are opened in the switching part of the circuit breaker, for example, the CIGRE International Conference on Larg
Paper 13−12 “SYNCHRONOUS ENERGIZING OF SHUNT” at e High Voltage Electric System 1988 Session
REACTORS AND SHUNT CAPACITORS "and the like, and are set so as to be before the time corresponding to the electrical angle of 100 ° to 170 ° with respect to the zero point of the current flowing through each phase.

In the power switching device of the present embodiment having the above-described configuration, the time at which the contacts of the switching units 43a to 43c are opened,
It can be shifted by a time corresponding to the electrical angle of 60 ° at the frequency of the AC voltage. On the other hand, in the three-phase balanced circuit, the voltage and the current deviate from each other by 120 ° in terms of electrical angle. However, if only the absolute value is considered regardless of the polarity, the voltage and current deviate by 60 ° in electrical angle. Therefore, the current phases at the time when the contacts of the switching units 43a to 43c of the circuit breaker of the present embodiment are opened are set to be substantially equal for the three-phase circuit.

It is generally well-known that in the case of interruption of a small delay current, a re-arc does not occur within a time range in which the arc time corresponds to an electrical angle of 100 ° to 170 ° of the AC voltage frequency. Therefore, if the phase control of the shutoff command is performed in the shutoff unit 43a so that the contacts are opened before the current zero point by a time corresponding to the electrical angle of 100 ° to 170 °, the shutoff unit 43b
And 43c, almost the same phase control is performed. As a result, for all three phases, the arc time can be set to a time corresponding to the electrical angle of 100 ° to 170 ° of the AC voltage frequency.

As described above, according to the present embodiment, the time when the electrodes of the arc extinguishing chambers of each phase open in the three-phase circuit is set to the time corresponding to the electrical angle of 60 ° of the AC voltage frequency while using a single driving device. As a result, the arc time can be set to a value that does not cause re-arcing in all three-phase arc-extinguishing chambers, so that downsizing and the number of parts can be reduced. In addition, it is possible to prevent occurrence of an abnormal voltage at the time of interrupting the small delay current.

The present invention is not limited to the above-described embodiment, and the throttle provided in the high-pressure oil transmission circuit is provided only in the b-phase and the c-phase in the embodiment shown in FIG. However, the same effect can be obtained by providing the same for all three phases.

[Effects of the Invention] As described above, according to the present invention, while using a single drive device, the time at which the electrode of each phase extinguishing chamber in the three-phase circuit is opened is different for each phase, The time differences between the cut-off first phase and the cut-off second phase, and the cut-off second phase and the cut-off third phase, which are the shortest, are the times corresponding to the electrical angle of 60 ° of the commercial frequency, respectively. The shutdown command is controlled so that the time at which the contact of one phase is opened is earlier than the zero point of the current flowing in that phase by a time corresponding to an electrical angle of commercial frequency of 100 to 170 °. By doing so, it is possible to provide a power switchgear that can prevent the occurrence of re-arcing when the shunt reactor current is interrupted.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a puffer type gas circuit breaker using a three-phase collective drive system, showing a first embodiment of a power switchgear of the present invention;
FIG. 2 is a block diagram showing a second embodiment of the present invention, FIG. 3 is a waveform showing a current-voltage time relationship for explaining a shunt reactor switching phenomenon, and FIG. 4 is a conventional shunt reactor circuit. FIG. 5 is a circuit diagram showing the configuration, FIG. 5 is a diagram showing a voltage waveform (a) and a current waveform (b) for explaining an electrical phenomenon at the time of shunt reactor disconnection, and FIG.
It is the elements on larger scale of the current waveform shown in the figure. 1 ... shunt reactor, 2 ... gas circuit breaker, 3 ...
Power supply side capacitance, 4… Load side capacitance, 12… Cutting surge voltage, 16… Return arc surge voltage, 21,22,23,24,25…
… Current zero generated by high-frequency current associated with re-arcing, 33
a, 33b, 33c …… cutoff coil, 35a, 35b, 35c …… delay circuit,
43a, 43b, 43c Opening / closing section, 44a, 44b, 44c Hydraulic cylinder, 51a, 51b, 51c Hydraulic piston, 53b1, 53b2, 53c1, 53
c2 …… Squeeze.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Toda 2-1 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Hamakawasaki Plant (72) Inventor Tetsuya Nakamoto No. 2, Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 Inside the Toshiba Hamakawasaki Plant

Claims (2)

(57) [Claims] 1. A puffer chamber having a fixed contact and a movable contact which can be brought into contact with and separated from each other in a container filled with an arc-extinguishing gas, and comprising a puffer piston and a puffer cylinder provided in the movable contact portion. A three-phase arc-extinguishing chamber for compressing the gas to guide the gas to the nozzle portion and cooling and extinguishing the arc generated between the fixed and movable arc contacts; and In a power switchgear that drives the arc extinguishing chamber for each phase according to a single control command and shuts off the three-phase circuit at a time, the single shutoff control command is divided and guided to the shutoff coil of each phase. The control circuit is configured as described above, and a delay circuit is provided in an energizing path during which the control command is led to the cutoff coil of each phase, and the time required for driving the cutoff coil of each phase is different for each phase. The first phase and the The time difference between the two phases, the interrupted second phase and the interrupted third phase is the time corresponding to the electrical angle of 60 ° of the commercial frequency, respectively, and the time at which the contacts of the interrupted first phase are opened is the phase. Electrical angle of the commercial frequency from the zero point of the current flowing through
A switchgear for electric power, characterized in that the shut-off command is controlled so as to be earlier by a time corresponding to 100 to 170 °. 2. A puffer chamber comprising a fixed contact and a movable contact which are detachable from each other in a container filled with an arc-extinguishing gas, and a puffer piston and a puffer cylinder provided in the movable contact portion. Has a three-phase arc extinguishing chamber that compresses the gas by compressing it and guides it to the nozzle part, and cools and extinguishes the arc generated between the fixed and movable arc contacts,
Further, in the power switching device for driving the arc extinguishing chambers for the three phases by a single control command and shutting off the three-phase circuit at a time, the single control device drives a hydraulic cylinder for each phase. It is composed of an electromagnetic coil that drives an operating valve and a pilot valve, and a throttle is provided in the hydraulic path that connects this operating valve to each hydraulic cylinder, so that the time required for each hydraulic cylinder to operate can be determined. The time difference between the first phase and the second phase, and the time difference between the second phase and the third phase, each of which is the shortest, corresponds to the electrical angle 60 ° of the commercial frequency. And the time at which the contacts of the first phase of disconnection are opened is before the zero point of the current flowing in that phase by a time corresponding to an electrical angle of the commercial frequency of 100 to 170 °. Controlled for electric power. Apparatus.