JP3230392B2 - Thyristor rectifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thyristor rectifier, and more particularly to a phase control device having fixed phase control means.

[0002]

2. Description of the Related Art Conventionally, silicon rectifiers have been mainly used as rectifiers for DC electric railway substations. Recently, thyristor rectifiers have been used in order to reduce the voltage fluctuation range of "feeder lines". A system in which a DC output voltage is controlled by arc phase control has been adopted.

FIG. 2 shows a configuration of a thyristor rectifier for a DC electric railway substation. The AC power from the AC power supply 1 is converted into DC power whose voltage is controlled by the thyristor rectifier main body 2, guided to the electric wire 4 via the DC breaker 3 and the like, and supplied to the DC train 5.

[0004] A phase control device of the thyristor rectifier main body 2 will be described. The voltage control system sets the voltage Vset of the feeder line 4 by the DC voltage setting device 6, compares the voltage with the output voltage detection value Vdet of the thyristor rectifier main body 2, and sets the proportionality by the voltage control amplifier 7 according to the deviation. A voltage control output obtained by performing an integration operation or the like is obtained. The voltage detection is made up of a voltage detector 8 having a voltage dividing resistor configuration and an insulating amplifier 9 that insulates and extracts the detected voltage.

[0005] The current control system uses the output of the voltage control system as a current command, and detects the current detection value Idet of the thyristor rectifier main body 2.
And a current control output obtained by performing a proportional integral operation or the like by the current control amplifier 10 according to the deviation is obtained. The current detection includes a current transformer 11 for transforming an AC input current of the thyristor rectifier main body 2 and a rectifier circuit 12 for rectifying and smoothing the detected current.

The integrator 13 integrates the current control output from the current control system and removes noise components without impairing the response of the current control system. The phase control circuit 14 includes the integrator 13
Is taken as a phase control angle command, the set value of the fixed phase setter 15 for limiting the maximum value is taken in, a pulse of a corresponding phase is generated, and a gate signal of the thyristor rectifier main body 2 is obtained.

Reference numeral 16 denotes a DC side surge absorber circuit of the thyristor rectifier main body 2, which mainly absorbs a surge voltage from the train 5 side.

[0008]

The thyristor rectifier (or silicon rectifier) includes a snubber circuit for protecting the thyristor element from overvoltage and a DC side surge absorber circuit 16.
Is provided. Therefore, the capacitors provided in these circuits are charged to the peak voltage during the no-load operation, and the output voltage becomes extremely high.

At this time, since the thyristor rectifier main body 2 is controlled to keep the output voltage constant by its phase control device, the thyristor rectifier main body 2 is subjected to the phase control so that the thyristor rectifier maintains the rated voltage even during no-load operation. That is, the higher the charging voltage of the capacitor, the larger the phase control angle of the thyristor rectifier main body 2 (the smaller the output voltage).

[0010] In this state, when a load is suddenly applied by raising the pantograph of the train 5, the output voltage starts to fall below the set value. In response to this voltage drop, the phase control angle of the thyristor rectifier main body 2 is shifted from a large (closed) state to a small phase control angle (output voltage increase) side. However, this phase shift control is delayed due to a delay in the control system. It cannot follow, and the DC output voltage of the rectifier body 2 decreases.

In some cases, the operation of the circuit breaker 3 and the like, that is, the operation of the electric train 5 is stopped by the operation of the undervoltage protection relay on the electric train 5 due to the decrease of the feeder voltage. By the way, undervoltage protection relay is 800V in 1500V railway.
The protection operation is performed before and after.

In order to solve such a problem, the output voltage constant control is conventionally interrupted by the fixed phase control by the fixed phase setting unit 15 to restrict the aperture (maximum value) of the phase control angle by the control system. Ensure that the output voltage does not drop below a certain value regardless of the load. This voltage is, for example, 150 V, considering voltage drop due to feeder line and rectifier transformer.
In the 0V system, it is set to 1000 to 1200V.

However, in order to obtain this voltage, it is necessary to set the thyristor phase control angle α to 44 ° to 50 ° as a fixed phase. Output voltage is 18 by charging
It becomes high to about 50 to 1920V.

With this voltage, there is a possibility that the overvoltage protection relay operates on the train 5 side. The train 5 is provided with a filter circuit, and when the capacitor of this circuit is charged, the voltage becomes high until the auxiliary circuit operates.

The above problems are not limited to thyristor rectifiers for electric railways, but also to loads with large fluctuations.

An object of the present invention is to provide a thyristor rectifier that prevents occurrence of overvoltage and undervoltage in a no-load state and a load connection.

[0017]

According to the present invention, there is provided a voltage control system for controlling a firing phase of a thyristor rectifier by comparing a DC output voltage of the thyristor rectifier with a set voltage. A thyristor rectifier for controlling the DC output voltage, a fixed phase setting circuit for limiting the phase control signal by the voltage control system to a plurality of stages, a current detection circuit for detecting a sudden increase in the output current of the load of the thyristor rectifier, A voltage detection circuit for detecting that the output voltage of the thyristor rectifier has approached an overvoltage level, and switching the setting of the fixed phase setting circuit to a maximum phase control angle when the thyristor rectifier is in a no-load state; At the time of detection, the setting of the fixed phase setting circuit is switched to the minimum phase control angle, and at the time of detection of the voltage detection circuit, the fixed phase setting circuit is switched. Setting intermediate switching and the phase control angle of the characterized by comprising a means for switching to the maximum phase control angle when said voltage detection continues beyond the predetermined period of time.

[0018]

Function The fixed phase control of the fixed phase setting circuit is switched in accordance with the change in the load state, and in a no-load state, the fixed phase control angle is maximized to prevent the output voltage from becoming excessive, and the connection to the load is fixed. The output voltage is increased by minimizing the phase control angle to prevent an undervoltage, and when an overvoltage is to be generated by this control, the fixed phase control angle is set at an intermediate level and further maximized to prevent the overvoltage.

[0019]

FIG. 1 is a block diagram showing an embodiment of the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals.

The current detector 21 is a surge absorber circuit 1
6 is detected, and the current change rate of the detected current is detected by the differentiating circuit 22. The comparator 23 detects that the detection level of the differentiating circuit 22 has exceeded a set level. With these current detection circuits, a sudden increase in current caused by raising the pantograph of the train 5 or the like is detected at an early stage.

The off-delay timer 24 obtains an ON signal (logic "1") upon detection by the comparator 23, and holds the signal for a certain period of time to obtain an OFF signal (logic "0").

The comparator 25 is a voltage detection circuit for detecting that the DC detection voltage obtained at the insulation amplifier 9 has risen to a value close to the overvoltage level.

In the flip-flop 26, the output of the off-delay timer 24 is set by a logical "1" signal passed through a NOR gate 27. In this set state, the fixed phase setting circuit 2
The switch 28A having the minimum fixed phase control angle of 8 is turned on. Further, the switch 28A is reset by the detection output of the comparator 25, and the switch 28A is turned off.

In the flip-flop 29, the output of the off-delay timer 24 is set by a logical "1" signal through the OR gate 27, and in the set state, the switch 28B of the fixed phase control angle in the middle of the fixed phase setting circuit 28 is turned on. To

The on-delay timer 30 obtains an on signal (logic "1") when the detection output of the comparator 25 continues for a predetermined time, and resets the flip-flop 29. In this reset, the switch 28B is turned off by the flip-flop 29.

The fixed phase setting circuit 28 includes a switch 28
In addition to setting the minimum and middle fixed layer control angles by the fixed phase setting devices 28C and 28D via the A and 28B, the maximum fixed phase control angle can be set by the fixed phase setting device 28E. Among them, the minimum value is selected by a selection circuit having a diode configuration.

Here, the setting unit 28C has a minimum fixed phase control angle (in the drawing, α = 45 °, the rectified output voltage has a maximum value), and the setting unit 28E has a maximum fixed phase control angle (in the drawing, α = 60 °, the rectified output voltage becomes the minimum value), so that the set voltage of the setter 28C becomes the maximum and the set voltage of the setter 28E becomes the minimum.

The phase control operation according to the above configuration will be described below.

First, in the no-load operation state, the flip-flops 26 and 29 are both in the reset state, the switches 28A and 28B of the fixed phase setting circuit 28 are off, and the phase control angle by the control system is α = 60 °. Limited. At this phase control angle, the output voltage of the thyristor rectifier main body 2 is reduced to prevent the DC charging voltage from increasing the peak charging voltage of the capacitor such as the surge absorber circuit 16 due to the DC output voltage.

Next, when a current flows from the thyristor rectifier main body 2 side to the load side by raising the pantograph of the train 5 or the like, a fast rising current flows from the surge absorber circuit 16 to the load side.

This current generation is detected by a current detection circuit comprising a current detector 21, a differentiating circuit 22 and a comparator 23, and the flip-flops 26 and 29 are set through an off-delay timer 24 for a fixed time.

By setting the flip-flops 26 and 29, the switches 28A and 28B of the fixed phase setter 28 are set.
Are turned on, but since the set voltage of the setter 28C is lower than the set voltages of the setters 28D and 28E, the minimum phase control angle (α = 45 °) is selected as the fixed phase set value, and the thyristor is set. The output voltage of the rectifier body 2 is forced to increase regardless of the control delay of the voltage control system.

When the load increases in this phase control state, the output voltage is set to approximately 1200 V by the fixed phase control with the phase control angle α = 45 °, and thereafter the voltage is increased to 1500 V by the control of the voltage control system. I do.

If the increase in the load current ends only with the inrush current of the capacitor of the filter of the train 5,
The snubber circuit, the absorber circuit, and the capacitor on the train 5 side are charged at a peak, and the output voltage of the thyristor rectifier main body 2 rapidly rises and tends to rise to about 1900V.

In the course of the voltage increase, when 1800 V is passed, the comparator 25 operates and the flip-flop 26 is reset. At this time, flip-flop 29 is still in the set state. As a result, only the switch 28A of the fixed phase setting unit 28 changes to the off state, the switch 28B maintains the on state, and the setting unit 28
The fixed phase is set based on the set voltage (intermediate phase control angle) α of D = 52 °, and the phase control angle is set so as to suppress the voltage rise and to cope with the rise in the load current (start of operation of the train).

In the above-mentioned state, when the state of only raising the pantograph continues and there is no load, the output voltage does not decrease until the degree of increase is suppressed. At this time, the comparator 25 continues to operate. When this state exceeds the time limit of the on-delay timer 30, the on-delay timer 30
Resets the flip-flop 29 and outputs α
The setting of = 52 ° is also cut off, and the setting returns to the setting of α = 60 °, and the output voltage settles to about 1400V.

With the above operation, the output voltage of the thyristor rectifier main body 2 fluctuates, but the output of the thyristor rectifier main body 2 is prevented from being overvoltage and undervoltage without any delay in detecting the overvoltage of the train 5.

The comparator 31 is used as a backup for the current detection circuit (comparator 23, etc.), and sets the flip-flop 26 through the NOR gate 27 when the output voltage becomes equal to or lower than the set value (for example, 1000 V), thereby reducing the voltage drop. To prevent.

In this embodiment, the case where the generation of the load current is detected from the current of the DC surge absorber circuit 16 at an early stage is shown. The operation and effect can be obtained.

The fixed phase switching circuit including the flip-flops 26 and 29 and the timers 24 and 30 is appropriately designed and changed.

The switching of the fixed phase is not limited to three stages.
The configuration may be such that the number of detection stages of the comparator 25 is two or more and the fixed phase switching is four or more stages.

[0042]

As described above, according to the present invention, the fixed phase control of the fixed phase setting circuit is switched in accordance with the change of the load state. The output voltage can be increased by minimizing the fixed phase control angle when the load is connected to prevent an undervoltage, and when the overvoltage is going to occur with this control, the fixed phase control angle can be Further, there is an effect that the overvoltage can be prevented by maximizing the voltage.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a conventional configuration diagram.

[Explanation of symbols]

 2 ... Thyristor rectifier body 7 ... Voltage control amplifier 10 ... Current control amplifier 14 ... Phase control circuit 16 ... DC surge absorber circuit 22 ... Differentiator circuit 23, 25, 31 ... Comparator 24 ... Off delay timer 28 ... Phase setting circuit 30 ... On Delay timer

Claims (1)

(57) [Claims] 1. A thyristor rectifier having a voltage control system for controlling a firing phase of the thyristor rectifier by comparing a DC output voltage of the thyristor rectifier with a set voltage, wherein the thyristor rectifier controls a DC output voltage. A fixed phase setting circuit for limiting the phase control signal to a plurality of stages; a current detection circuit for detecting a sudden increase in the output current of the load of the thyristor rectifier; and detecting that the output voltage of the thyristor rectifier approaches an overvoltage level. When the voltage detection circuit and the thyristor rectifier are in a no-load state, the setting of the fixed phase setting circuit is switched to the maximum phase control angle, and the setting of the fixed phase setting circuit is set to the minimum phase control angle when the current detection circuit detects. When the voltage detection circuit detects, the setting of the fixed phase setting circuit is switched to an intermediate phase control angle, and the voltage detection is performed. Thyristor rectifier, characterized in that it comprises means for switching to the maximum phase control angle when continuing the constant time or more.