JPS58157400A - Exciter for electric machine - Google Patents

Abstract

PURPOSE:To eliminate an exciting current transformer exclusively for excitation by supplying the current from an instrument current transformer to an exciting coil when the output current of a generator is abruptly increased or when the voltage of the generator is decreased. CONSTITUTION:A thyristor controller 11 normally conducts a bidirectional thyristor 12 to shortcircuit the output of an instrument current transformer 9. On the other hand, an automatic voltage regulator 5 controls the conduction of a thyristor 6 in response to the output of an instrument transformer 4. When a shortcircuit trouble occurs in the output circuit of a generator 1 and the detected voltage value at the transformer 4 is abnormally decreased or the detected current value of the transformer 9 is abruptly increased, the controller 11 interrupts the thyristor 12, and supplies the output of the transformer 9 through a rectifier 13 to an exciting coil 2. In this manner, the current necessary to recover the voltage of a generator or to operate a protecting relay is supplied.

Description

[Detailed description of the invention] The present invention relates to an excitation device for an electric machine.

A conventional excitation device of this type is shown in FIG. In the figure, / is the generator, /a is the 1 [mature winding of the generator /, /b is the excitation winding of the generator 7, /C is the rectifier, /d
is the alternating current generator, ko is the excitation winding of the alternator/d, 3 is the excitation transformer, da is the instrument transformer, S is the automatic voltage regulator,
6 is a thyristor, 7 is an exciting current transformer, and g is a rectifier.

Next, the operation will be explained. The voltage generated by the alternator /d corresponding to the DC current applied to the excitation winding @ , 2 K is rectified by the rectifier fii/c and applied to the excitation winding /b, whereby the generator / Line /a produces an output voltage on line l.

On the other hand, the output voltage of the generator 1 is controlled by controlling the secondary voltage of the excitation transformer 3 using a thyristor 6 and applying it to the excitation winding. This is done by converting the output voltage of the above generator using an instrument transformer and comparing it with a specified value using an automatic voltage regulator.

Also, the current of the excitation current transformer 7 is rectified by the rectifier t, and the same (
By applying it to the excitation winding λ, excitation proportional to the load current of the generator is obtained. In the event that the output circuit of the generator is short-circuited, the fault current required to operate the bare protection relay (not shown) must be supplied from the generator.
The fault current is supplied by applying the secondary current value in the excitation current transformer 7 to the excitation winding via the rectifier t.

In this way, output voltage control is performed by both voltage control at the instrument and excitation transformers DA and 3, and current control at the excitation current transformer. It is designed as a primary current value and a secondary current value that are proportional to the current.

Therefore, the excitation current generator 7 must be newly designed and manufactured for each generator so that the primary current value and secondary current value are proportional to the load current, and the switchboard that houses the excitation device must also be designed accordingly. The drawback was that a new design and manufacture had to be made each time.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above. During normal operation, the output from the voltage transformer is short-circuited by a bidirectional thyristor, and the output current of the generator increases rapidly. The bidirectional thyristor is made non-conductive and the excitation current is supplied from the measurement current transformer to the excitation winding of the generator when the generator voltage decreases. The object of the present invention is to provide an excitation device for an electric machine that does not require an excitation current transformer.

Hereinafter, one embodiment of the present invention will be described based on FIG. In FIG. 2, the excitation current transformer 7 shown in FIG.
and the rectifier g have been removed, and in their place is a thyristor control device l which inputs both the voltage signal from the instrument transformer 4 and the current signal passed through the measuring current transformer 9 and the measuring device io.
1 and a bidirectional thyristor saw connected to the output of the instrument IO. The bidirectional thyristor saw is controlled by the output signal of the thyristor controller // to determine whether to apply the output from the meter 10 to the excitation winding through the rectifier /3.

The other configurations are the same as those in FIG. 1, so their explanation will be omitted.

In the above configuration, the output voltage of the generator is controlled by controlling the continuity of the thyristor 6 using the instrument transformer q and the automatic voltage regulator to apply the secondary voltage of the excitation transformer 3 to the excitation winding q. This is done in the same way as in the conventional case, but the control by the excitation current transformer is not performed.

For example, if a short circuit occurs in the output circuit of the generator,
When the voltage detection value at the instrument transformer 4 drops abnormally or the current detection value at the measurement current transformer increases abnormally, the thyristor control device// detects an abnormality in either of them and switches the bidirectional control. The secondary current of the measuring current transformer is supplied to the excitation winding through the rectifier 3 with the thyristor saw non-conducting, thereby providing the current necessary for voltage recovery of the generator 1 or operation of the eel relay. We will be able to supply it.

In the above embodiment, the generator l is a single-phase alternating current generator with brushless excitation, but a three-phase alternating current generator may be used with other excitation devices, such as thyristor excitation, or a synchronous motor may be used. It's okay.

Furthermore, although a measurement current transformer is used in the embodiment, the same effect as in the above embodiment can be obtained even if a protection current transformer is used. Further, although the bidirectional thyristors are connected in parallel on the secondary side of the current transformer to be short-circuited during normal operation, they may be connected in series and controlled to be open during normal operation.

As described above, the present invention eliminates the need for excitation current transformers that were designed and manufactured exclusively for excitation for each generator.
The configuration uses general-purpose current transformers for measurement, protection, etc. to supply excitation only in abnormal situations such as accidents, so the types of excitation devices can be unified, and the switchboard that houses the excitation devices can be made smaller and cheaper. It has the effect of giving you something.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional excitation device, and FIG. 1 is a block diagram showing an excitation device according to an embodiment of the present invention. In the figure, / is the generator, ko is the excitation winding,
3 is the excitation transformer, DA is the instrument transformer, 5 is the automatic voltage p
4 is a rectifier, O is a thyristor, D is a measuring current transformer, 10 is a measuring instrument, // is a thyristor control device, l is a bidirectional thyristor, and /3 is a rectifier. Agent Shin Kuzuno −

Claims (1)

[Claims] (1) The output of the excitation transformer is applied to the excitation winding of the electric machine by controlling the conduction of the thyristor using the output of the instrument transformer that detects the voltage of the electric machine, and the voltage of the electric machine is adjusted. In an excitation device for an electric machine, the thyristor receives both a voltage detection value from the potential transformer and a current detection value from a current transformer that detects a load current of the electric machine. a control device; and a bidirectional thyristor connected between the current transformer and the excitation winding, the thyristor control device configured to disconnect the current transformer and the excitation winding under normal conditions. The bidirectional thyristor is controlled to control the tllll of the current transformer when the detected voltage value from the potential transformer abnormally decreases or the detected current value from the current transformer abnormally increases. An excitation device for an electric machine whose special purpose is to control the bidirectional thyristor so as to energize the excitation winding. (,2) The excitation device for an electric machine according to claim 1, wherein the Tlt transformer is a current transformer for measurement. (,7) An exciting device for an electric machine according to claim 1, wherein the current transformer is a protection current transformer.