JP3619212B2 - Switchgear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a switchgear for cutting off current, and more particularly to a forced commutation cutoff type switchgear.
[0002]
[Prior art]
FIG. 6 shows a configuration diagram of this type of conventional forced commutation cutoff type switching device. In the figure, 1 is a main circuit switch, 2 is a main circuit power supply, and 6 is a load, which constitute a main circuit such as a power system. Reference numeral 7 denotes the inductance of the main circuit. 4 is a capacitor of the forced commutation circuit, 3 is a DC power source of the forced commutation circuit that charges and holds the capacitor 4 in the illustrated polarity, 11 is a forward closing switch for commutation, and 111 is a commutation switch. For the reverse commutation switch, 12 is a reactor of the forced commutation circuit, 15 is an energy absorption element, and these constitute a forced commutation circuit 60, and a high frequency current having a frequency determined by C of the capacitor 4 and L of the reactor 12 is generated. The main circuit current is superposed on the main circuit current to have a zero cross point. Further, 14 is a current sensor for detecting the direction of the main circuit current, abnormality, etc., 13 is a control device for controlling forced commutation cutoff, 22 is a current flowing through the main circuit switch 1, 23 is a high-frequency current to be superimposed, Reference numeral 24 denotes the total current.
[0003]
FIG. 7 shows an example of the configuration of the main circuit switch 1. In the figure, 90 is a vacuum valve, 91 is a fixed contact, 92 is a movable contact, 93 is a coil for opening, 94 is a coil for closing, 95 is a repulsion plate, 96 is a contact pressure generating opening holding spring, and 97 is an upper part. A terminal, 98 is a lower terminal, and 99 is a movable shaft. The main circuit current flows in the order of the upper terminal 97, the fixed contact 91, the movable contact 92, and the lower terminal 98, and the movable shaft is driven by the magnetic force (repulsive force) between the repulsion plate 95 and the opening coil 93 or the closing coil 94. The part from the movable contact 92 including 99 to the repulsion plate 95 moves up and down, and the connection between the fixed contact 91 and the movable contact 92 is disconnected in the vacuum valve 90. At this time, the contact pressure generating and opening holding spring 96 is a spring that generates a contact pressure in a closed state and provides a force for maintaining the opening at the time of opening.
[0004]
Next, the operation will be described. The main circuit switch 1 which is a mechanical switch does not have a self-extinguishing function, and the main circuit current flowing through the main circuit switch 1 cannot be interrupted unless the current is zero. When the AC circuit cuts off without waiting for the natural current zero point, or in the case of a DC circuit, the forced commutation cutoff switch (HSS) is in the opposite direction from the forced commutation circuit 60 including the reactor 12 and the capacitor 4 in the current of the circuit. The current is cut off by forcibly creating a current zero point by superimposing high-frequency currents of opposite polarity. In an AC circuit, the direction of current flow changes, and even in a DC circuit, the direction of current changes in the event of an accident, so a commutation circuit in both directions is required. However, for economic reasons, for example, only a unidirectional forced commutation circuit 60 in which the capacitor 4 is charged is provided so as to superimpose a high-frequency current having a reverse polarity on a current in the direction indicated by the current 22. When the current is cut off, a high frequency current of one cycle is superimposed to create a zero point of the current from the reverse direction and cut off. As a result, in addition to the main circuit current 22, a high-frequency current 23 having a large amplitude and a steep change flows between the contacts of the main circuit switch 1. Therefore, the main circuit switch 1 is required to have a high breaking performance. .
[0005]
In FIG. 8, when the current 22 in the reverse direction to the current 22 shown in FIG. 6 of the main circuit switch 1 is cut off, a current zero point from the reverse direction is created by superimposing one cycle of the high-frequency current 23 on the current 22. 6 shows a time chart of currents and voltages of the respective parts in FIG. 6 at the time of interruption, and the direction of the arrow in FIG. 6 is shown as positive. 8, 22-24 correspond to those shown in FIG. 6, 25 is the voltage of the capacitor 4, 26 is the travel state of the contacts 91, 92 shown in FIG. 7 of the main circuit switch 1, and 57 is the current sensor 14. The timing at which the control device 13 determines an accident and sends an opening command to the main circuit switch 1, 51 is the timing at which the contacts of the main circuit switch 1 are separated, 56 is at the time of turning on the forward and reverse closing switches 11, 111 The timing at which the high-frequency current is superimposed for one period is shown. FIG. 8 shows a state where the total current 24 cannot be cut off.
[0006]
[Problems to be solved by the invention]
As described above, in the conventional forced commutation cutoff type switchgear, only a unidirectional forced commutation circuit is provided for economy, and the zero point of the current from the reverse direction can be obtained by superimposing one cycle of high-frequency current. I made it and blocked it. As a result, the main circuit current that should be cut off by the main circuit switch 22 shown in FIG. 7 on which the high-frequency current is superimposed for one period has a large current amplitude and a sharp change. Between the contacts 91 and 92 in the vacuum valve 90 shown in FIG. 3, the density of ions and electrons ejected from the contacts by arc firing increases, and the vacuum arc extinction cannot catch up with the rate of current reduction. Had become difficult. Therefore, there is a problem that the main circuit switch is required to have a high breaking performance.
[0007]
The present invention has been made to solve the above-described problems, and is a forced commutation cutoff type opening and closing type capable of interrupting current in both directions in the main circuit switch with one forced commutation circuit without requiring high cutoff performance. An object is to provide an apparatus.
[0008]
[Means for Solving the Problems]
In view of the above-described object, the present invention provides a main circuit switch inserted in a main circuit, a current sensor for detecting a current flowing in the main circuit, and a first opposite to the main circuit current in the first direction of the main circuit switch. A capacitor charged so as to superimpose a high-frequency current in the direction of 2 and a reactor connected in series with the capacitor, and an anti-parallel connection that superimposes the high-frequency current on the main circuit current by connecting them in parallel to the main circuit switch A forced commutation circuit including a pair of forward and reverse input switches, polarity reversal means for reversing the polarity of the capacitor by exchanging charges through charge and discharge through a closed loop, and interruption of the main circuit current are required. Means for detecting the direction of the main circuit current by the current sensor, and if the direction of the main circuit current is the first direction, an opening command is sent to the main circuit switch. And a means for turning on the forward closing switch after a predetermined time to flow a high-frequency current in a second direction opposite to the first direction through the main circuit switch, and a direction of the main circuit current being the first If the second direction is opposite to the direction, the opening instruction is issued to the main circuit switch and the polarity of the capacitor is reversed by the polarity reversing means. And a means for supplying a high-frequency current in the first direction to the main circuit switch.
[0009]
The polarity reversing means comprises a closed loop composed of the forced commutation circuit and a main circuit switch, and the polarity reversal is performed via the main circuit switch by turning on the forward closing switch.
[0010]
The polarity reversing means may be a closed loop connected between both ends of the capacitor including a polarity reversing switch, and the polarity reversing switch is turned on to perform polarity reversal.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a forced commutation cutoff type switching device according to an embodiment of the present invention. In the figure, the same or corresponding parts as those in FIG. Reference numeral 13a denotes a control device comprising a microcomputer or the like under program control for performing forced commutation cutoff control according to the present invention, and BC is a cutoff command signal inputted from the outside by manual operation of a switch (not shown). 2 is a flowchart showing the control operation of the control device 13a according to the present invention, and FIG. 3 is a time chart of current and voltage of each part of FIG. 1 when the main circuit current in the direction of the current 22 shown in FIG. FIG. 4 is a time chart of currents and voltages of respective parts in FIG. 1 when the main circuit current in the direction opposite to that of the current 22 shown in FIG. 1 is cut off. The structure of the main circuit switch 1 is the same as that shown in FIG.
[0012]
3 and 4, numerals 22 to 24 correspond to those shown in FIG. 1, and currents and voltages are shown with the arrow and the direction of the sign in FIG. 1 as positive. Reference numeral 25 denotes a voltage of the capacitor 4, and 26 denotes a travel state of the contacts 91 and 92 shown in FIG. 7 of the main circuit switch 1. In FIG. 3, reference numeral 50 denotes, for example, that the control device 13 a determines an accident based on the current detection from the current sensor 14, or the cutoff command signal BC is input from the outside to the control device 13 a regardless of the accident and the main circuit current is cut off. Is determined, the direction of the main circuit current is determined based on the current detection from the current sensor 14 and the opening command is sent to the main circuit switch 1, 51 is the timing when the contacts of the main circuit switch 1 are separated, and 52 is the order The timing when the direction switch 11 is turned on to superimpose the high-frequency current, 53 indicates the timing when the main circuit current of the main circuit switch 1 becomes zero, and 54 indicates the timing when the regenerative current ends after the interruption.
[0013]
In FIG. 4, reference numerals 51, 53, and 54 correspond to those shown in FIG. 3, and reference numeral 55 indicates that the controller 13a determines an accident based on, for example, current detection from the current sensor 14, or is external regardless of the accident. Is inputted to the control device 13a to request the interruption of the main circuit current, and the direction of the main circuit current is determined based on the current detection from the current sensor 14, which is the opposite direction (the opposite direction to 22 in FIG. 1). ), The forward closing switch 11 is turned on to superimpose a half-cycle high-frequency current so that the polarity of the capacitor 4 is determined, and the opening instruction is sent to the main circuit switch 1. The timing at which the on-off switch 111 is turned on to superimpose the high-frequency current, that is, the state in which the entire current 24 cannot be interrupted is shown.
[0014]
That is, according to the present invention, when the main circuit current is in the direction indicated by 22 in FIG. 1 (first direction: positive direction), basically the same interruption operation as in the prior art is performed, and the main circuit current is shown in FIG. 1 is applied in the forward direction of FIG. 1, for example, before an opening command is given to the main circuit switch 1 and the contacts are actually separated from each other. One forced commutation circuit is configured such that the polarity of the capacitor 4 is reversed by switching the switch 11 through a half-cycle and switching the charge of the capacitor 4 through the closed loop circuit including the closing switch 11, the reactor 12, and the main circuit switch 1. 60, the high-frequency current having the opposite polarity to the main circuit current in the direction opposite to 22 in FIG.
[0015]
The operation will be described below with reference to FIGS. For example, when the controller 13a determines an accident based on the current detection from the current sensor 14 (a state in which the main circuit current value exceeds a predetermined value and the main circuit switch needs to be shut off), or a command to shut off from the outside regardless of the accident. When the signal BC is input to the control device 13a and a cutoff of the main circuit current is requested (step S1), the direction of the main circuit current is determined based on the current detection from the current sensor 14 (step S2).
[0016]
When the main circuit current is in the direction indicated by 22 in FIG. 1 (first direction: positive direction), basically the same interruption operation as in the prior art is performed, and an opening command is given to the main circuit switch 1 (step S3). ) When the predetermined time has elapsed after the contacts of the main circuit switch 1 have actually started to separate (the main circuit switch 1 has a switching mechanical time delay), 1, a high-frequency current 23 in the direction opposite to the current 22 (first direction) (second direction) is caused to flow and superimpose (step S3). Thereby, the current 22 of the main circuit switch 1, that is, the main circuit current is cut off (see FIG. 3 above).
[0017]
On the other hand, when the main circuit current is opposite to the direction indicated by 22 in FIG. 1 (second direction: reverse direction), the forward closing switch 11 is first turned on to allow the high-frequency current to flow for a half cycle and Invert the polarity. This may be performed before the opening instruction is given to the subsequent main circuit switch 1 and before the contacts actually start to separate (step S5). The subsequent steps are basically the same as those in the forward direction, and an opening command is given to the main circuit switch 1 (step S6). After a predetermined time elapses after the contacts of the main circuit switch 1 actually start to separate, The closing switch 111 is turned on, and the high frequency current 23 in the direction opposite to the current 22 (second direction) (first direction) is caused to flow and superimpose on the main circuit switch 1 (step S7). Thereby, the current 22 of the main circuit switch 1, that is, the main circuit current is cut off (see FIG. 4 above).
[0018]
As described above, when the current flowing through the main circuit switch 1 is in the reverse direction, the polarity of the capacitor 4 of the forced commutation circuit 60 is reversed by charging / discharging before the interruption, so that Similarly, forced commutation can be interrupted, and in particular, by charging and discharging the capacitor 4 via the main circuit switch 1 to perform polarity reversal, it is basically possible to implement only by changing the control.
[0019]
Embodiment 2. FIG.
FIG. 2 shows a configuration diagram of a forced commutation cutoff type switchgear according to another embodiment of the present invention. In this embodiment, a closed loop 114 dedicated to the polarity inversion of the capacitor 4 including the polarity inversion switch 112 and the reactor 113 is provided, and the polarity inversion is performed when the current 22 of the main circuit switch 1 is in the opposite direction to FIG. The switch 112 was turned on so as to be reversed. Others are the same as in the above embodiment.
[0020]
When a large current flows through the main circuit switch 1, a force for separating the contacts 91 and 92 of the main circuit switch 1 shown in FIG. 7 is generated. Usually, the contact is generated between the contacts by a contact pressure generating opening holding spring 96. I try to press it. In this embodiment, when the polarity of the capacitor 4 is reversed, a high-frequency current of the same polarity does not flow superimposed on the main circuit current 22 as shown in FIG. The structure of the main circuit switch 1 such as the contact pressure generating and opening retaining spring 96 can be simplified.
[0021]
When the control device 13a determines that an accident has occurred based on the current detection from the current sensor 14 as a state in which the main circuit current needs to be interrupted, an interrupt command signal BC is input to the control device 13a from the outside regardless of the accident. For example, when based on current detection from the current sensor 14, for example, a current waveform that is used as a reference is stored in a memory (not shown) or the like that checks the current level. There is a check. In addition, a voltmeter (not shown) for measuring the main circuit voltage is further provided. Similarly, a voltage waveform to be used as a reference is stored in a memory (not shown) or the like for checking the voltage level. It is good also as checking.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a forced commutation cutoff type switching device according to an embodiment of the present invention;
FIG. 2 is a flowchart showing a control operation of the control device according to the present invention.
FIG. 3 is a time chart of currents and voltages at various parts in FIG. 1 when the main circuit current in the positive direction of the device according to the present invention is cut off.
FIG. 4 is a time chart of currents and voltages at various parts in FIG. 1 when the main circuit current in the reverse direction of the device according to the present invention is cut off.
FIG. 5 is a diagram showing a configuration of a forced commutation cutoff type switching device according to another embodiment of the present invention.
FIG. 6 is a diagram showing a configuration of a conventional forced commutation cutoff type opening / closing device of this type.
FIG. 7 is a diagram illustrating an example of a configuration of a main circuit switch.
8 is a time chart of currents and voltages at various parts in FIG. 6 for explaining a conventional operation.
[Explanation of symbols]
1 main circuit switch, 2 main circuit power supply, 3 DC power supply for forced commutation circuit, 4 capacitor for forced commutation circuit, 6 load, 7 inductance of main circuit, 11 forward switch, 12 reactor for forced commutation circuit , 13a Control device, 14 current sensor, 15 energy absorbing element, 60 forced commutation circuit, 111 reverse direction switch.

Claims (3)

A main circuit switch inserted in the main circuit;
A current sensor for detecting the current flowing in the main circuit;
A capacitor charged so as to superimpose a high-frequency current in a second direction opposite to the main circuit current in the first direction of the main circuit switch, a reactor connected in series with the capacitor, and these in parallel with the main circuit switch A forced commutation circuit including a pair of forward and reverse input switches connected in reverse parallel to superimpose a high frequency current on the main circuit current
Polarity reversing means for reversing the polarity of the capacitor by exchanging charges by charging and discharging through a closed loop;
Means for detecting a direction of the main circuit current by the current sensor when the interruption of the main circuit current is requested;
If the direction of the main circuit current is the first direction, an opening command is issued to the main circuit switch, and after a predetermined time has elapsed, the forward direction switch is turned on and the main circuit switch is turned on with the first direction. Means for flowing a high-frequency current in the opposite second direction;
If the direction of the main circuit current is the second direction opposite to the first direction, an opening command is issued to the main circuit switch, and the polarity of the capacitor is inverted by the polarity inversion means, and after a predetermined time has elapsed, Means for turning on a reverse turn-on switch to flow a high-frequency current in the first direction to the main circuit switch;
A switchgear characterized by comprising: The polarity inversion means comprises a closed loop composed of the forced commutation circuit and a main circuit switch, and the polarity inversion is performed via the main circuit switch by turning on the forward closing switch. Switchgear. 2. The polarity inversion means comprises a closed loop connected between both ends of the capacitor including a polarity inversion switch, and the polarity inversion is performed through the polarity inversion switch. The switchgear described.

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