JPS601783B2 - DC solid shredder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a two-terminal bidirectional DC solid-state device that can switch on and off the steady current of several hundred to several thousand V, several thousand to tens of thousands of A, or cut off the fault current in a DC main circuit from outside the SIRIS. Concerning a shredder.

DC solid-state shearing devices have no mechanical parts or movable contact parts, and when the sheathing occurs, the energy stored in the inductance of the circuit is consumed by the solid-state element, and the circuit can be opened and closed without an arc. It is being put into practical use as a replacement for high-speed breakers for electric railway substations and high-speed breakers for DC electric cars.

This DC solid state shearing device controls the opening and closing of a DC main circuit by gate control of an electric valve with a control pole such as a thyristor and commutation effect by discharge of a capacitor.

When using this as a high-speed circuit breaker, the main circuit current flowing through the power supply inductance and load inductance is generally bypassed to an external main circuit element when the electric valve with control pole is turned off. The problem is that we have a means to quickly eliminate them without causing any damage.
By the way, if the capacitance of a commutating capacitor is extremely increased as a means of reliably extinguishing the main circuit current of a two-terminal direct current or disconnection device, the disadvantage is that the entire device becomes larger and is economically disadvantageous. be. In addition, 3
There is also a method of connecting a large capacity capacitor and a freewheeling diode between the input/output terminal and the negative bus, but in this case, the attenuation rate of the main circuit current decreases significantly. The present invention has been made in view of the above circumstances,
By bypassing the main circuit current through a series circuit of a metal oxide non-linear resistor and a current reducing resistor, it is possible to quickly dissipate the current, thereby making the entire device smaller and more economical. It minimizes the amount of excess charge stored in the commutating capacitor immediately after a power disconnection, ensures that recharging is completed within a short time using a small-capacity recharging device, and provides a two-terminal system that can be re-disconnected after reclosing. The purpose of the present invention is to provide a bidirectional direct current solid shredding device.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the basic circuit of a two-terminal bidirectional direct current solid state shearing device. In the figure, reference numeral 10 denotes a DC power supply containing an inductance inside, and between both terminals of this power supply 10, a main thyristor 11 of a DC solid state insulation device is connected in antiparallel.
, 12 and an inductive load 20 are connected in series. A series circuit of a metal oxide nonlinear resistor 13 and a current reducing resistor 14 each having a constant voltage characteristic in parallel with the main thyristors 11 and 12, an auxiliary thyristor 15 with the polarity shown, a commutating capacitor 16, and a commutating reactor. Connect the series circuit with 17. The illustrated bypass diode 18 is connected to the auxiliary thyristor 15. Additionally, an auxiliary charging device 19 having the polarity shown is connected between the terminals of the commutating capacitor 16. Then,
Each of the thyristors 11, 12, and 15 is supplied with a predetermined ignition signal by an ignition device (not shown), and is controlled to be conductive.

It is assumed that the commutating capacitor 16 is charged to the illustrated polarity, and its charging voltage reaches the power supply voltage of the auxiliary charging device layer 19. Next, when a gate pulse is applied to the gates of the main thyristors 11 and 12, the main thyristor 11 becomes conductive, and a forward load current flows through the load 201, reaching a steady state. Since the magnitude and direction of the load current are constantly changing, the gating pulses of the main thyristors 11, 12 are preferably maintained until a gating signal is applied to the auxiliary thyristor 15 to begin cutting off the circuit current. To cut off the forward load current, the auxiliary thyristor 15 is turned on. When the auxiliary thyristor 15 is made conductive, the charge in the commutation capacitor 16 is transferred to the auxiliary thyristor 15, the main thyristor 11, and the commutation reactor 1.
7, but when the magnitude of the discharge current becomes greater than the load current, the main thyristor 11 turns off.
A portion of the discharge current that exceeds the load current is passed through the main thyristor 12. As a method of applying a gate pulse to the main thyristor 12 and igniting it, the gate pulse may be connected to the main thyristor 12 until the discharge current reaches a positive peak value. When the discharge current reaches a positive peak value, the charge on the commutating capacitor 16 becomes zero. When the discharge current exceeds a positive peak value, the commutating capacitor 16 is charged to a polarity opposite to that shown. When this current gradually decays and becomes equal to the load current again, the main thyristor 12 becomes blocked. The load current charges the commutating capacitor 6 until the terminal voltage of the commutating capacitor 16 becomes equal to the limiting voltage of the nonlinear resistor 13 having constant voltage characteristics. When the terminal voltage of the commutating capacitor 6 exceeds the voltage limit of the non-linear resistor 13, the load current is shunted into the series circuit of the non-linear resistor 13 and the dead current resistor 14. If the limiting voltage of the nonlinear resistor 13 is selected in advance to be 1.5 to several times the voltage of the DC power supply 10, a negative voltage will be applied to the terminals of the concessional load 19 during this period. The load current rapidly decays and disappears. When the charging current of the commutating capacitor 16 becomes 0, the auxiliary thyristor 15 is turned off. After a certain time period when the auxiliary thyristor 15 is turned off, the commutating capacitor 16 is charged to the original polarity shown by the auxiliary charging layer 19. Next, it is assumed that the back electromotive force from the inductive load 20 of the DC power supply 10' causes the load current to flow in the opposite direction through the main thyristor 12.

When cutting off the load current in the opposite direction, the auxiliary thyristor 1
5 becomes conductive. When the auxiliary thyristor 15 is made conductive,
The charge in the commutating capacitor 16 is discharged through the auxiliary thyristor 15, the main thyristor 12, and the commutating reactor 17.
At this time, a discharge current flows through the main circulator 12 in a manner superimposed on the load current iL. When the discharge current reaches a positive peak value, the charge on the commutating capacitor 16 becomes zero. When the discharge current exceeds a positive peak value, the commutating capacitor 16 is charged with a polarity opposite to that shown. When the charging current becomes 0, the charge in the commutation capacitor 6 is then discharged through the commutation reactor 17, the main thyristor 12, and the bypass diode 18, but when the magnitude of the discharge current becomes equal to the load current,
Main thyristor 12 is turned off. The discharge current continues until the terminal voltage of the commutating capacitor 16 becomes equal to the limiting voltage of the non-linear resistor 13 having constant voltage characteristics.
6 to the polarity shown. When the terminal voltage of the commutating capacitor 16 exceeds the voltage limit of the non-linear resistor 13, the load current is shunted into the series circuit of the non-linear resistor 13 and the dead current resistor 14. The limited voltage of the nonlinear resistor 13 is set in advance to the DC power supply 1.
If the value is selected to be 1.5 to several times the voltage at zero, the inductive load 20 that generates back electromotive force during this period
A high positive voltage is applied to the terminals of , and the load current rapidly decays and disappears. When the charging current of the commutating capacitor 16 becomes 0, the bypass diode 18 enters a blocking state. The commutating capacitor 16 is charged to the original polarity shown even without the action of the auxiliary charger layer 19. The process of breakage of fault current is very similar to that of load current.

FIGS. 2 and 3 are oscillograms at the time of fault current shear breakage using the DC solid state shear breakage device of the present invention. In FIG. 2, when gate pulses eGMF and eGMR are applied to the gates of main thyristors 11 and 12, respectively, main thyristor 1
1 is conductive, and the load current iL flows to reach the steady current lo. Assuming that a short circuit fault occurs inside the inductive load 19 at time L, the load current iL is rapidly increasing toward the estimated short circuit current le. At time T, the load current iL is the set value of the disconnector (steady forward current) ls
When it reaches, a gate pulse eG^ is applied to the gate of the auxiliary thyristor 15 to make the auxiliary thyristor 15 conductive.
When the auxiliary thyristor 15 is made conductive, the charge in the commutation capacitor 6 is discharged through the auxiliary thyristor 15, the main thyristor 11, and the commutation reactor 17. Pre-discharge current i.
The rate of increase in the fault current (load current) iL is selected to be much larger than the rate of increase in the fault current (load current) iL. When the magnitude of the discharge current iC becomes larger than the set value ls of the breaker, the main thyristor 11 is turned off. Discharge current i. The portion exceeding the set value ls of the insulator and disconnector is passed to the main thyristor 12. The method of applying a gate pulse to the main thyristor 12 and igniting it is T=T, and instead of removing the gate pulse eGMF of the main thyristor 12, the main thyristor 11 is gated until the discharge current iC reaches a positive peak value lpf'. It is sufficient to connect the pulse eGMR. Discharge current i. When the voltage reaches the positive peak value lpf, the electric charge on the commutating capacitor 16 becomes zero. When the discharge current iC exceeds a positive peak value, the commutating capacitor 16 is charged with a polarity opposite to that shown in FIG. When this current gradually attenuates and becomes equal to the set value ls of the breaker again at T2, the main thyristor 12
becomes blocked. The fault current (load current) iL charges the commutating capacitor 16 until the terminal voltage of the commutating capacitor 6 becomes equal to the limiting voltage of the nonlinear resistor 13. When the terminal voltage of the commutating capacitor 16 exceeds the voltage limit of the non-linear resistor 13, the fault current iL is shunted into the series circuit of the non-linear resistor 13 and the current reducing resistor 14. After this, the energy stored in the inductance of the circuit is transferred to the non-linear resistor 13.
and the current reducing resistor 14, the fault current iL rapidly attenuates and disappears at T4. Charging current i of commutating capacitor 16. When becomes 0, the auxiliary thyristor 15 is turned off. When the induced voltage of the inductive load 20 is higher than the voltage of the DC power supply 10, the main thyristor 11,
Gate pulses eGMF and eGM are applied to each of the 12 gates.
When R is applied, the main thyristor 12 conducts and the load current iL
flows and reaches a steady current lo'. Assuming that a short-circuit accident occurs inside the DC power supply 10 at time To', the load current iL rapidly increases toward the estimated short-circuit current le'. At time T,', the load current iL reaches the set value of the circuit breaker (steady reverse current) ls', and at this time, when a gate pulse eG^ is applied to the gate of the auxiliary thyristor 15 to make the auxiliary thyristor 16 conductive, commutation occurs. The charge in the capacitor 16 is discharged through the auxiliary thyristor 15, the main thyristor 12, and the commutation reactor 17. When the discharge current iC reaches the positive peak value lpf, the charge on the commutating capacitor 16 becomes zero. When the discharge current iC exceeds the positive peak value lpf, the commutating capacitor 16 is charged with a polarity opposite to that shown in FIG. When the charging current becomes 0, the charge in the commutation capacitor 16 is transferred to the commutation reactor 17, the main thyristor 12,
Discharge occurs through the bypass diode 18, and when the magnitude of the discharge current iC at L' becomes equal to the set value ls' of the circuit breaker, the main thyristor 12 is turned off. The fault current iL is caused by the terminal voltage of the commutating capacitor 16 being the non-linear resistor 1.
The commutating capacitor 16 is charged until it becomes equal to the limit voltage of 3. When the terminal voltage of the commutating capacitor 16 exceeds the voltage limit of the non-linear resistor 13, the fault current iL is shunted into the series circuit of the non-linear resistor 13 and the dead current resistor 14. After this, the energy stored in the inductance of the circuit is consumed by the nonlinear resistor 13 and the current reducing resistor 14, and the fault current rapidly attenuates and disappears at T4'. When the charging current iC of the commutating capacitor becomes 0, the bypass diode 18 enters the blocking state. For the non-linear resistor 13 having constant voltage characteristics used in such a DC solid state breaker, a metal oxide sintered material containing zinc oxide or zinc oxide and magnesium oxide as main components is suitable.

This type of non-linear resistor has the disadvantage that its deterioration accelerates significantly if DC voltage is left applied for a long period of time, but high-speed flea breakers and breakers for DC electric railway substations are generally used. When a disconnector is connected in series and the load circuit is left open for a long time, the disconnector is opened. It only takes a few tens of seconds from immediately after that until the circuit is reclosed or the disconnector is opened. A current reducing resistor 14 connected in series with the non-linear resistor 13 serves to bear a portion of the voltage shared by the relatively expensive non-linear resistor 13 and to attenuate the charging and discharging current of the commutating LC circuit. FIG. 4 shows another embodiment of the present invention, in which a DC power supply 10 is used in common for a plurality of loads (here, another concessional load 30 is added to the embodiment of FIG. 1). Connect as shown in the figure, and each inductive load 20, 30
It is constructed so that the current flowing through it can be cut off.

In this case, the commutating reactor 27, the commutating capacitor 26, and the auxiliary charging layer 19 are used as a common disconnector, and the main thyristors I1, 12, 21, 22, and the nonlinear resistor 1
3, 23, current reducing resistor 14, 24, auxiliary thyristor 15
, 25 and bypass diodes 18, 28 are connected as shown in the figure. With such a configuration, when multiple load currents are to be cut off, it is possible to arrange the cutting-off devices shown in Fig. 1 according to the number of loads, but compared to this, the commutation reactor 27 and commutation capacitor 26
Since these are common, the configuration is simple. Furthermore, since the solid shear breaker with the above-mentioned configuration does not generate direct current or disconnection arcs, it is recommended to The thyristors can be housed in a common tank, making it lighter and more compact than conventional systems that use high-speed direct current or disconnectors.

In addition, since each main thyristor can be housed in a common tank, the cooler for the main thyristor, which especially requires cooling, can be shared in one unit, making it possible to increase the number of coolers commensurate with the capacity of the DC power supply 10, that is, the rectifier. The total capacity can be reduced. In addition, various modifications can be made without changing the gist of the invention. As described above, the present invention improves the circuit configuration of a DC solid state shunt breaker that controls the opening and closing of a DC main circuit by gate control of an electric valve with a control pole such as a thyristor and commutation action by discharging a commutation capacitor. It has two terminals, which enables the main circuit to be opened using a single-pole disconnector, and in the event of an accident, the energy stored in the inductance on the power supply side and the load side can be transferred to a series circuit with a metal oxide nonlinear resistor and a current reducing resistor. This makes it possible to quickly eliminate the current by consuming it in
By selecting the limiting voltage of the non-linear resistor to be 1.5 to several times higher than the DC power supply voltage, the insulation resistance between the terminals becomes virtually infinite after the fault current disappears, and the circuit can be placed in an open state with a simple circuit. This makes it possible to miniaturize the entire device, manufacture it at low cost, and provide a two-terminal bidirectional DC solid state shearing device that can be reclosed and re-broken after shearing.

[Brief explanation of drawings]

Figure 1 is a wiring diagram showing one embodiment of the present invention, Figures 2 and 3 are
The figure is an oscillogram for explaining the operation of the same embodiment, and FIG. 4 is a wiring diagram showing another embodiment of the present invention. 10...DC power supply, 11, 12...Main thyristor, 13...Non-linear resistor, 14...Reducing current resistor, 15...Auxiliary thyristor, 16...・・・・・・
Commutation capacitor, 17... Commutation reactor, 1
8... Bypass diode, 19...
Auxiliary charging layer, 20... Inductive load, 21, 22...
...Main thyristor, 23...Non-linear resistor, 24...Reducing current resistor, 25...Auxiliary thyristor, 26... current capacitor, 27.
... Commutation reactor, 28 ... Bypass diode, 30 ... Inductive load. Figure 2 Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] 1. A main thyristor that can supply current from a DC power source to a load and is connected in antiparallel; a commutating reactor, a commutating capacitor, and an auxiliary thyristor that are connected in parallel to the main thyristor; and the auxiliary thyristor. a commutation circuit for turning off the main thyristor consisting of a series circuit of bypass diodes connected in antiparallel to the main thyristor; and a series circuit of a metal oxide nonlinear resistor and a current reducing resistor connected in parallel to the main thyristor. A bidirectional direct current solid state shielding device comprising a current reducing circuit consisting of a current reducing circuit and an auxiliary charging device for charging the commutating capacitor. 2. A main thyristor that can supply current to the load from a DC power source and is connected in anti-parallel; a commutating reactor, a commutating capacitor, and an auxiliary thyristor that are connected in parallel to this main thyristor; and a thyristor that is connected in anti-parallel to this auxiliary thyristor. a commutation circuit for turning off the main thyristor consisting of a series circuit of bypass diodes; a current reduction circuit connected in parallel to the main thyristor and consisting of a series circuit of a non-linear resistor and a current reduction resistor; At least two sets of DC solid-state shearing devices equipped with an auxiliary charging device for charging the capacitor are provided, one set each of the above-mentioned DC power supply and the above-mentioned auxiliary charging device are used, and these are shared by the above-mentioned DC solid-state shearing device. A bidirectional DC solid shredding device featuring: