JPS6022561B2 - Linear motor power supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to a near-motor power supply device equipped with a reactive power compensation device for compensating for reactive power of a load connected to an AC power source.

[Prior art]

Fluctuations in reactive power in the power system due to large power consumption such as arc furnaces cause fluctuations in voltage drop due to the reactance of the power transmission system, which also fluctuates the voltage of other consumers connected to the same system, and in severe cases can cause lighting flicker problems. arise.

Therefore, in order to suppress this voltage fluctuation, a reactive power compensator is connected in parallel with the fluctuating load and controlled according to the fluctuation of the load to reduce the fluctuation of reactive power in the power system. As this reactive power compensator, a synchronous phase modifier, a saturated reactor, a capacitor opening/closing using a thyristor switch, a reactor control using a thyristor, etc. are used, but reactor control using a thyristor has recently been commonly used. Fig. 1 is a configuration diagram of a combination system of capacitors and thyristor-controlled reactors divided into multiple banks, where capacitors C, to C4 are thyristor switches m, depending on the magnitude of reactive power QF of load F,
These capacitors roughly compensate for the reactive power QF of the load F, and the capacitor C. ~C4
By controlling the phase of the IJ actor L, which has a size equal to the unit capacitance of controlled by. In this way, in the circuit system shown in Figure 1, the reactor capacitance only needs to be equal to the unit capacitance Qcu of the capacitors divided into multiple banks, so the high-frequency current generated when the phase of the reactor is controlled by a thyristor is extremely small. In addition, when the reactor capacity is small and the reactive power of the load is zero, the loss is reduced by opening both the capacitor and the reactor.

The operation of the circuit shown in FIG. 1 will be explained using the operation diagram shown in FIG. 2.

When using a linear motor with load F, and assuming that the active power P of load F changes from A to A along the straight line shown by the dotted chain line with respect to the change in time T corresponding to the speed change, the reactive power QP of load F The operation shown in FIG. 1 will be described when the load F varies as shown by the solid line A and the reactive power QF of the load F is about four times the capacitance per division of the capacitor (unit capacitance Qc.). For convenience of explanation, levels 1 to 4 in FIG. 1A are provided, and level 1 is provided with the size of QcU, and level 2 is provided with the size of Shigeru cU. Reactor L is placed on the positive side from 0 in Figure 2B.
In addition, from 0 to the negative side, the leading phase reactive power Qc due to capacitors C and C4 is shown.

When time T is 0, all capacitors C and ~C4 whose reactive power QF of load F is maximum are switched to thyristor switch H.
A command is generated by h, to m4. When time T reaches T, the reactive power QF of load F becomes equal to level 3, but in the period from time T from 0 to T, reactor L
The reactive power QL is controlled by the thyristor Th so that QL=4QU-QF. When T, is reached, the bell becomes 3, so thyristor switch Th4 is released, and at the same time thyristor Th is also released, capacitor C4 and reactor L are both opened, and after that, reactor L is controlled by thyristor m, and reactor The reactive power QL of L is QL
=$ is also slightly compensated for the period from T to T2 so that it becomes U-QF. The same operation as described above is performed from time T2 to T4, and when T4 is reached, the reactive power QF of load F becomes zero, so capacitors C, ~C4 and reactor L are opened. be done.

When the opening/closing control of the capacitors C, ~C4 and the reactor L control are performed as described above, the capacitors C, ~C4
QF, which is the total reactive power due to the actuator L, is the second
The reactive power Qs from the fin source E becomes zero because it is controlled to cancel the reactive power QF of the load F shown by the dashed line at the bottom of FIG. However, as shown in Fig. 1, in a circuit system that connects a reactive power compensator in parallel to the power system to compensate for the reactive power of the load, the thyristor Th and thyristor switch Th,
~ If an abnormal condition occurs in which one of Th4 becomes unable to ignite or is destroyed, the lagging reactive power increases or the leading reactive power increases more than the reactive power QF consumed by the load F. Increasing power system i.e.
There was a drawback that the voltage of the AC power supply E fluctuated significantly, causing great damage to general consumers connected to the same power system.

[Object of the Invention] The present invention eliminates the above-mentioned drawbacks of conventional reactive power compensators, and when a linear motor is used as a load, a simple circuit configuration enables the reactive power compensator to compensate for the power system when an abnormal state occurs. [Summary of the Invention] The present invention is characterized by a reactive power compensator and a power converter. Means for detecting abnormalities in the devices, and means for disconnecting the power converter and the reactive power compensator from the power source when any of these detecting means is activated, and connecting a dynamic braking resistor to the output side of the power converter. It is to establish the following.

[Explanation of Embodiment] Fig. 3 shows an embodiment of the present invention of a single wire connection applied to a linear motor power supply device, where T is a running body, LM,
~LM4 is a linear motor propulsion coil, SW, ~SW4 is a box division switch, F,, F2 is a feeder line, Tr is a power transformer, S, ~S3 is a switch, CC,, CC2 is a power converter, R,, R2 are braking resistors, P, Tr are potential transformers, Tr,, Tr2 are reactive power compensators, TQ,, TQ
2 transformer, CT, is a current transformer that detects the power supply current, CL
, CT3 is a current transformer that detects the output current of each of the power converters CC and CC2, 10 is a phase difference detection circuit, 3
1, 41 is a positive/negative distribution circuit composed of a transformer P, an operational amplifier, etc. that distributes the waveform of the secondary current 1 of T to a current transformer for detecting the secondary voltage V of Tr and a power supply current as positive or negative; 32;
34 is a first-order delay circuit for the positive and negative waveforms of voltage V; 33;
35 is a waveform shaping circuit, 51 and 54 are AND circuits, d, ~
d8 is composed of a backflow blocking diode.

60, 60' are failure detection circuits for power converters CC, CC2, lp is a current command signal, and 61' is a current command signal lp.
, 62 is a power conversion device CC, . An absolute value circuit for the secondary current lu of L is installed in the current transformer for detecting the output current of CC2.
63 is a subtracter, 64 is a delay circuit, 65 is a comparator, d7 is a backflow blocking diode, and other symbols are shown by the same symbols as in FIG. 1, so their explanation will be omitted.

Next, to explain the general operation of the power supply device for the linear motor in the circuit shown in FIG. 3, when the traveling body T straddles the propulsion coil L ground and the propulsion coil LM3 as shown in FIG. and SW3 are closed, power is supplied by power converters CC and CC2, and the traveling body T connects to the propulsion coil L.
When exiting M2, the power supply to the power converter CC2 is stopped,
Power is supplied only by CC until just before entering the propulsion coil LM4. The period in which power is supplied to CC and CC2 at the same time is when the traveling body T straddles two sections, and by performing such power supply control, the propulsion of the traveling body T does not fluctuate and the traveling body T can travel in the section. can be done.

In such an operation, power converters CC, CC2
To explain the operation of FIG. 3 when is normal, capacitors C and C4 are connected to power transformer Tr, power converters CC, CC
2 and propulsion coils LM, ~LM4.
The thyristor switch T depends on the magnitude of the reactive power QF of
These capacitors roughly compensate for the reactive power QF of the load F, and the capacitors C, ~C4
By controlling the phase of the IJ actor L, which has a size equal to the unit capacitance of controlled by.

Next, to explain the operation of the failure detection device 60 in FIG. 3 when the load F is normal using the operating waveform diagram in FIG. 4, the absolute value of the current command signal lp (output waveform 610 of the absolute value circuit 61)
, the absolute value of the output current lu of the power converter CC,
The output waveform 620) of the absolute value circuit 62 is shown by a solid line in FIG. 4, and the output waveform of the subtracter 63 is shown by a solid line 630.

In this case, the comparison level of the comparator 65 is set to 1△lp on the negative side, as is known from the output waveform 630 of the subtracter 63 when the load F is normal. During switching (assuming that the power converter CC is composed of thyristor converters connected in antiparallel), the deviation signal is △lp or more even under normal conditions (■ in Fig. 4 when the current command signal lp is large). , ■ period)), this is to cut this situation. In addition, the delay circuit 64 absorbs the noise with the time constant of the delay circuit when the output of the subtracter 63 exceeds the detection level of the comparator 65 for a short period of time caused by noise or the like. This prevents the comparator 65 from malfunctioning. Next, in the operating waveform diagram of FIG. 2, time T
To explain the operation shown in FIG. 3 when an abnormal condition such as a short circuit occurs on the load side of the power converter CC shown in FIG. Since the waveform of the output current lu is oscillatory as shown by the broken line 621 in FIG. 4, the deviation signal 631 of the subtracter 63 exceeds the set value ΔTp (at the time of ■ in FIG. 4), so the comparator 65 operates (output waveform 650), the abnormal state of the memory circuit 2 is memorized (output waveform 200), and the switch S, is shut off, and the operation of the power converter tC, is stopped and the power is restored. It is possible to prevent the slow phase reactive power Qs from increasing when an abnormality occurs on the load side of the converter CC, and to turn on the braking resistor R via the switch S2 to stably stop the traveling body T.

Here, the OR circuit 30 operates when any of the power converters CC, . This circuit outputs an output even if CC2 becomes abnormal at the same time. On the other hand, if an abnormal condition occurs in which the traveling body T is short-circuited at any time between T and -L in Fig. 2, the reactive power QF of the load F increases more than QF in Fig. 2, so the Since the phase difference detection circuit 10 outputs an output,
The phase difference detection circuit 10 also connects the switch S. and a command to stop the operation of power converter CC, and switch S.
A command to input 2 is generated.

Also, at any time between T and -L in FIG. 2, the power converter C
If an abnormal state occurs in which CC suddenly stops operating, the failure detection device 60 cannot detect this abnormal state because the output current lu of the power converter CC is smaller than the current command signal lp. Since the lagging reactive power QF of the load F suddenly decreases, the reactive power QF from the reactive power compensator becomes phase advanced, so the phase difference detection circuit 10 outputs an output. The fin force converter is stopped and the braking resistance R is turned on via the switch S2.
, is turned on, it is possible to control voltage fluctuations in the power system, and to prevent adverse effects on other devices.

As described above in detail, according to an embodiment of the present invention, a failure detection device is used when a power converter, etc. has a failure in which the output current of the power converter becomes larger than the current command signal regardless of the magnitude of the current command signal. Alternatively, it is detected by the phase difference detection circuit, and this output is used to close the switch and generate a command to stop the operation of the power converter and a command to close the switch S2.

In addition, if the power converter fails or the reactive power compensator becomes abnormal, the output current of the power converter becomes smaller than the current command signal regardless of the magnitude of the current command signal, these abnormalities can be detected by the phase difference detection circuit. is detected, and this output disconnects the switching diagram S, and stops the operation of the power converter, and the control resistor R is turned on via the switch S2.
Voltage fluctuations in the electric power system during these abnormalities are ``suppressed from adverse effects on other consumers in the same electric power system, and are prevented from adverse effects on other healthy equipment that constitutes var compensators, power converters, etc.'' The present invention is not limited to the above-described embodiment, and when the number of power converters increases, the number of reactive power compensators also increases. However, it goes without saying that the present invention can be applied to such a circuit configuration, and also to a circuit configuration in which only the number of reactive power compensators is increased.

[Brief explanation of the drawings] Figure 1 is a single connection diagram showing a conventional reactive power compensator;
The figure is an explanatory diagram of the operation of Figure 1, Figure 3 is a circuit diagram of an embodiment of the present invention in a single wire connection applied to a linear motor power supply device, and Figure 4 is an operation waveform diagram of the failure detection circuit of Figure 3. . 8... AC power supply, Qs... Reactive power flowing out from AC power supply B, QF... Reactive power consumed by load F, Qc... Phase advancing reactive power due to capacitor C, Qp... Qc + QL, C
, ~C4...Capacitor, L...Rear little, Th, ~Th
4... Thyristor switch, Th... Thyristor, F.
...Load, ×s...Power source impedance, T...Travelling object, L
M, ~LM4...Propulsion coil, SW,...SW4...Turtle division switch, F, ~F2...Feeder, S, ~S3...Switch,
lp... Current command signal, Tr, ~Tr2... Transformer for reactive power compensator "PTr... Potential transformer, Tr
...Power transformer, CC, ~CC2...Power converter, R
, ~R2...braking resistance, 30...OR circuit ~CT,
... Current transformer t for power supply current detection 20, 20'... Memory circuit, 51, 54... AND circuit, 33, 35... Waveform shaping circuit, third group, 41... Positive/negative distribution circuit, 32, 34... 1
Next delay circuit, 42943... Number inversion circuit, 61,6
2... Absolute value circuit, 64... Delay circuit, 66...
Comparator L○, ~D7... Backflow blocking diode, 10
...Phase difference detection circuit, 60, 60'...Failure detection device, TQ
,~TQ2... reactive power compensator, CT2~CT3...
Current transformer for power converter output current detection. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1 A propulsion coil installed on the track side and divided into many parts,
a power converter for feeding power to the propulsion coil; a large number of feeder section switches that connect the propulsion coils of the multiple sections and the power converter; and compensation for reactive power on the AC input power source side of the power converter. and detecting an abnormal state of the reactive power compensator in a linear motor power supply device that supplies power to the propulsion coil while sequentially switching the feeder section switch as the traveling body traveling on the propulsion coil advances. means for detecting an abnormal state of the power converter, and disconnecting the power converter and the reactive power compensator from the power source in response to output from any of the abnormal state detecting means; A linear motor power supply device comprising: means for connecting a dynamic braking resistor to the output side of the power conversion device.