JPS60207419A - Method of protecting control rectifier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for protecting a controlled rectifier that drives an inductive load.

[Technical background of the invention and its problems]

Traditionally, the protection methods for sub-control rectifiers are gate shift (GS) → gate block (GB) → AC breaker trip (CRT) or bypass pair (BPP) → gate block (CB) → AC breaker trip ( CBT)
protection interlocking is used. Gate shift is to greatly delay the firing angle of the controlled rectifier and operate in the inverse conversion region (90° to 180° firing angle), transferring the energy from the DC side to the AC side (twice and reducing the current to zero). Bypass pairing is an operation in which a pair of control rectifiers of the same phase on the AC side (two connected control rectifiers) are simultaneously turned on and the load is short-circuited.
The DC circuit and AC circuit are separated, the AC current becomes zero, and I
The K flow core flow attenuates with the time constant of the load. Gate blocking is a controlled rectifying element (2) that blocks the ignition pulse given.

FIG. 1 shows a block diagram of a conventional controlled rectifier for protection. To simplify the explanation of failure factors, only DC overcurrent and current generator transformer failure are shown. Figure 1 (2, 1 is a switchboard, Makoto, 2 is an AC breaker, 3 is a rectifier transformer, 4 is an i-j control rectifier, 5-1
~ 5-6 is a controlled rectifying element that purchases the controlled rectifying device 4;
6 is a load, 7 is a DC photodetector that detects DC upstream, 8
1 is a transformer failure detector for detecting a failure of the rectifier transformer 3, 9 is a DC overcurrent detector, 10-1 to 0-3 are OR circuits, and 11-1 to 11-3 are delay circuits. Reference numeral 12 denotes a phase control circuit that performs gate shifting, bypass pairing, and gate blocking of the control rectifier 4 using the output signals of the OR circuits 10-1 to 10-3.

Tentative title 2: Failure to gate shift the control rectifier 4.
For example, if a current is generated through the DC overcurrent 14, the output of the DC overcurrent detector is inputted to the phase control circuit 124 through the OR circuit 1O-1, and the control rectifier WL4 is gate-shifted. Thereafter, when the delay circuit 11-1 ζ2 and the set time have elapsed, the OR circuit 10-3 (2, the phase control circuit 12 (2) and the control rectifier 4 are gate-blocked. When the time set in 11-3 has elapsed, the output of the delay circuit 11-3 becomes 1'', and the crossover breaker 2 is tripped.
3-) Sequential control is performed by taking a time interlock with GB - + CRT.Also, if a failure occurs that requires the temporary control rectifier WL4 to be a bypass pair, for example, a rectifier transformer failure occurs, the OR circuit 1O -2, the phase control circuit 124 signal enters, the control rectifier 4 becomes a bypass pair, and then the delay circuit 11-2, 11-3.
The gate block and AC breaker trip are controlled sequentially according to the time set in .

By the way, as seen in nuclear fusion power supplies, etc. (2) When the load on the control rectifier is large, the accelerator is too low, and the time constant is large (2) A state in which the normal protection interlock described above does not operate and AC current is flowing. When the AC breaker is tripped by
There is a problem in that the controlled rectifying element ζ is destroyed when the energizing voltage is applied. FIG. 2 is an explanatory diagram illustrating the circuit magnetic pressure when the AC breaker trips.

In Fig. 2 (-, the same elements as in Fig. 1 are given the same reference numerals and explanations are omitted. -3 indicates the element of each phase of the AC breaker, and 15-1 to 15-3 indicate the leakage reactance of each phase of the rectifier transformer.

The + and - symbols indicate the polarity of the voltage, and the + and - symbols are positive and -, respectively, are negative. FIG. 2 3 = As shown, control!
When the AC breaker is opened while the IIL element 5-1.5-6 is energized, the current attenuation rate di/dt and
The product Ldi/dt of the inductance value of the load (:) An overvoltage Ed = Ldi/dt is generated, and Ed is applied to the control rectifier elements 5-3, 5-4, and the control rectifier elements 5-2.
5-5 had a problem in that Ed/2 was applied and the control rectifying element was destroyed.

Possible causes for failure to perform normal protective operation include AC voltage drop (normal commutation is not performed between two voltages), etc.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned problems and provide a safe method of protecting a controlled rectifier.

[Summary of the invention]

In order to achieve the above object, the present invention provides two ignition pulses to the control rectifier element 6 when the AC breaker is tripped during a protection stop, and the ignition pulse is applied to the AC breaker after the AC breaker is tripped. This is what I decided to do.

[Embodiments of the invention]

FIG. 3 (2) Shows the configuration of an embodiment of the present invention. FIG. 3 1=
1, the same elements as in FIG. 1 are given the same reference numerals and their explanation will be omitted.

11-4 is a delay circuit that delays the AC breaker trip signal 56 for a certain period of time. Signal 51 is a DC overcurrent compensation signal;
Signal 52 is a failure signal of the rectifier transformer 3, signal 53 is a gate shift command signal, signal 54 is a signal to delay the gate shift command signal device for a certain period of time and perform bypass pair operation, signal 55 is a bypass pair command signal, and the signal amount is The AC breaker trip command signal, signal 57, which delays the bypass pair command signal 55 for a certain period of time and trips the AC breaker 3, is a gate block command signal.

Fig. 4 shows a time chart when two DC overcurrents occur and a term chart when the fifth factor ζ rectifier transformer 3 fails.

Hereinafter, the working port of the present invention will be explained with reference to FIGS. 3, 4, and 5. In FIG. 3, if a failure that requires a gate shift of the control rectifier 4 occurs, for example, a DC stray current occurs, the signal 51 becomes 1", passes through the 9-OR circuit 1O-1, and the gate shift command signal 53 becomes 11". No, control***
Position 4 is gate shifted. Gate shift delay circuit 1
When the set time elapses, the signal 54.5
5 becomes 11'', the controlled rectifier outputs an ignition pulse to create a bypass pair.Then, the delay circuit 11'-2
When the time set in Jt has elapsed, the signal 56 becomes 1'', and the AC breaker 2 is tripped.After that, when the time set in the delay circuit 11-4+2 has elapsed, the gate block command 57 is activated. 1” Tonashi control rectifier 4
becomes a gate block. Figure 4 shows the above explanation using a time chart. GS −+ BPP → CB
T-) CB and controlled. The delay circuit 11-1 is set so that the current is sufficiently zero (2) due to the gate shift, the delay circuit 11-2 is set to be longer than the time required to input the bypass pair, and the delay circuit 11-4 is set so that the current is zero (2). is set longer than the delay time for tripping.

Next (=, failure that should cause the control rectifier 4 to be bypass bare,
For example, if a failure occurs in the rectifier transformer 3, the signal 52 becomes 1'', the bypass pair command signal 55 becomes '1'' through the shear circuit 1O-2, and the multi-control rectifier 4 becomes a bypass pair. . After that, the AC disconnector trip command signal 56 becomes "1", and the AC iAf, L and disconnector 3 are tripped, and then the gate block command signal 57 becomes "1"9, and the control rectifier 4 is gate blocked. .

The time chart for the above explanation is shown in Figure 5 (two are added together).

The controlled rectifier 4 is controlled as follows: BPP→CBT→GB.

FIG. 6 1: shows another embodiment of the present invention. In FIG. 6 (2), the same elements as in FIG. This is an AND circuit that performs logical product.In this embodiment, after confirming that the AC breaker 2 is definitely opened using the auxiliary contact of the AC breaker 2, the output of the AND circuit 16 (control Gate block the rectifier 4.

〔Effect of the invention〕

As explained above, according to the method for protecting a controlled rectifier of the present invention, when an AC breaker is cut off (2 is always ≦2, AC side - phase c: l - a pair of connected controlled rectifier elements are ignited). Since the pulse is applied, even if some kind of malfunction occurs, the above-mentioned F, d = L
From dL/dt l'-, the control rectifier is energized and can be safely stopped (=stopped) without causing an overvoltage.

[Brief explanation of drawings]

Figure 1 is a block diagram of a protection device for a conventional controlled rectifier.
Figure 2 is an explanatory diagram of the operation when the AC breaker trips;
FIG. 4 is a block diagram showing an embodiment of the present invention, FIGS. 4 and 5 are time charts explaining the present invention in detail, and FIG.
The figure is a block diagram showing another embodiment of the invention. 1... AC bus bar 2... AC breaker 3... Rectifier transformer 4... Control rectifier 5-1 to 5-6...
・Control rectifier element 6...Load 7...DC current detector 8...Transformer failure detector 9...DC current detector
1O-1 to 1O-3...OR circuit 11-1 to 11-4
... Delay circuit 12 ... Phase control circuit 13-1 to 13
-3... Equivalent AC voltage source 14-1-14-3... AC breaker element 15-1 to 15-3... Leakage reactor 16... AND circuit 51... DC overcurrent 4 current signal 5
2... Mal change fault is No. 53... Gate shift command signal 54... Bypass pair request signal 55... Bypass pair command 1 word Koku... AC power analyzer trifling instruction word 57...Gate block command signal (7317) Agent Patent attorney Noriyuki Chika (Haga1
Name) Figure 1 4 Figure 2 5-, s To Figure 3 Figure 4 B 67 Figure 5 B 37

Claims (1)

[Claims] When performing a protective stop at a controlled rectifying device (=) that drives an inductive load, the AC side of the controlled rectifying device - phase (:. While giving an ignition pulse to a pair of connected controlled rectifying elements A method for protecting a controlled rectifier, characterized by cutting off an AC breaker and then performing gate blocking.