JP3129780B2 - Excitation controller for synchronous machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excitation control apparatus for a synchronous machine, and more particularly to an excitation control apparatus for a synchronous machine multiplexed to improve reliability.

[0002]

2. Description of the Related Art In general, an excitation control device for a synchronous machine has a basic function of an automatic voltage adjusting function for controlling a terminal voltage of the synchronous machine to be constant, and as an additional function, operates the synchronous machine stably within its operating capacity limit. Over-excitation limit function and under-excitation limit function. Furthermore, it has many complicated control devices such as a secondary adjustment function for keeping the power factor and the reactive power constant.

When a failure occurs in the excitation control device, the control may be abnormal or the control operation may be stopped, and the operation of the synchronous machine may not be continued. Therefore, high reliability is required for the excitation control device. Particularly, in the case of a large-capacity synchronous generator of a commercial power generation facility, very high reliability is required due to its public nature and the social importance of power supply.

[0004] In such a control device requiring high reliability, the reliability of the control device itself is increased so that a failure does not occur, and the operation of the control target device can be continued even if a failure occurs. Is generally used. FIG. 5 is a configuration diagram showing a conventional example of a multiplexed excitation control device for a synchronous machine.

A field current is supplied to a field winding 2 of the synchronous machine 1 from a thyristor rectifier 4 having a three-phase uniform bridge connection via a field breaker 3, and an AC power supply E of the thyristor rectifier 4 is supplied.
A is supplied from the output of the synchronous machine 1 via the exciting transformer 5.

On the other hand, the automatic voltage adjusters 6a, 6b, 6c detect the terminal voltage of the synchronous machine 1 via the instrument transformer 7,
Control calculation is performed so that this terminal voltage becomes the target value,
It outputs control signals CA, CB and CC.

The phase control units 8a, 8b and 8c receive the AC power supply voltage EA via the transformer 9, and use the AC power supply voltage as a reference phase to change the phase signals PA and PA which change according to the control signals CA, CB and CC. PB and PC are output. The intermediate pulse selectors 10a, 10b, and 10c output the phase signals PA, PB, and PC.
Of the phase signals PLA,
Outputs PLB and PLC.

The pulse output units 11a, 11b and 11c each output a firing pulse at the phase indicated by the phase signals PLA, PLB and PLC. The PL is supplied to the thyristor rectifier 4.

During normal operation, automatic voltage regulators 6a, 6b,
6c and the phase control units 8a, 8b, 8c operate in the same way, but are controlled by terminal voltage detection errors of the automatic voltage adjustment units 6a, 6b, 6c and reference phase detection errors of the phase control units 8a, 8b, 8c. The signals CA, CB, CC and the phase signals PA, PB, PC each operate with a slight difference.

The intermediate pulse selectors 10a, 10b and 10c select and output an intermediate phase signal among the phase signals PA, PB and PC, so that the phase signals PLA, PLB and PLC are the same. Therefore, the pulse output units 11a, 11b, 11
The firing pulses output by c become the same signal, and the firing pulse PL obtained by ORing them is also the same signal.

FIG. 6 is a block diagram of the intermediate pulse selector 10a. Since the majority circuit is constituted by the logical product 12 and the logical sum 13, the phase signal PLA is converted to the phase signals PA, PB, PC.
Is the majority decision result. The intermediate pulse selectors 10b and 10c have the same configuration as the intermediate pulse selector 10a.

FIG. 7 is a waveform chart showing the operation of the conventional excitation control device. Since the thyristor rectifier 4 has a three-phase uniform bridge connection, the firing pulse PL and the phase signals PA, PB, P
Each of C, PLA, PLB, and PLC has a signal corresponding to six phases.
Also, since the phase signals PLA, PLB, and PLC are the same signal, only the phase signal PLA is shown.

The period t ₁ of the AC power supply EA indicates a normal operation, and the phase signals PA, PB, PC are signals proportional to the control signals CA, CB, CC, respectively, based on the phase of the AC power supply EA. The phase signal PLA is the same signal as the phase signal PA because the majority of the phase signals PA, PB, and PC is obtained.
That is, the phase signal PLA is composed of three phase signals PA, P
This means that the phase signal PA indicating the intermediate phase is selected from B and PC. The firing pulse PL becomes a pulse signal having a desired width from the rising of the phase signal PLA.

Next, the automatic voltage adjusting section 6a and the phase control section 8
a or both of the phase signals PA
Shown in period t ₂ the operation when but are no longer output. In this case, the phase signal PLA is a logical product of the phase signals PB and PC, and thus becomes the same signal as the phase signal PC.

Further, in a state where the phase signal PA is no longer output, the operation when one or both of the automatic voltage adjusting unit 6b and the phase control unit 8b fail and the phase signal PB is no longer output is set to a period t. _{See Figure 3} . In this case, since the phase signal PLA is not output, the firing pulse PL is not output.

[0016]

As described above, in a conventional synchronous machine excitation device (hereinafter, referred to as a control device),
Even if one of the tripled automatic voltage adjustment unit and the phase control unit fails, a normal phase signal is selected from the three phase signals input to the intermediate pulse selection unit. The ignition pulse PL is output from the pulse output unit according to the signal.
Is output to the thyristor rectifier, so that normal operation can be continued.

However, in the conventional control device, since there is no failure detection means, continuous operation is performed even if one system is faulty.
If another system breaks down, there is a problem that normal operation cannot be performed.

Therefore, an object of the present invention is to reduce the time from the occurrence of a failure to the repair of the failure by reliably and accurately detecting a series of failures in the tripled control device, and to reduce the operating rate of the control device. It is an object of the present invention to obtain a highly-reliable synchronous machine exciting device that can increase the power consumption.

[0019]

In order to achieve the above object, according to the present invention, there are provided three automatic voltages for inputting a terminal voltage of a synchronous machine and outputting a control signal for adjusting the terminal voltage. An adjustment unit; three phase control units that convert each control signal output from the automatic voltage adjustment unit to a phase signal and output the phase signal; Three intermediate value selection units for selecting and outputting values, and a difference between a phase signal output from the phase control unit and a phase signal output from the intermediate value selection unit is equal to or more than a set value and continues for more than a set value time Then, three failure detection units that output an alarm, three pulse output units that output a firing pulse based on the phase signal selected by the intermediate value selection unit, and three output units that are output from the pulse output unit Of the firing pulse A synchronous machine excitation control device, comprising: a logical sum unit that performs processing; and a thyristor rectifier that is controlled by a signal output from the logical sum and outputs an exciting current to a field winding of the synchronous machine. provide.

[0020]

According to the above arrangement, when one of the tripled automatic voltage regulators and the phase controller fails, the failed one is replaced with the phase signal input to the intermediate value selector and the intermediate value selector. By comparing with the phase signal output from, the detection is performed reliably and promptly, and an alarm is output.

[0021]

FIG. 1 is a block diagram showing an excitation control device for a synchronous machine according to an embodiment of the present invention.

A field current is supplied to a field winding 2 of the synchronous machine 1 from a thyristor rectifier 4 having a three-phase uniform bridge connection via a field circuit breaker 3.
A is supplied from the output of the synchronous machine 1 via the exciting transformer 5.

On the other hand, the automatic voltage adjusters 6a, 6b, 6c detect the terminal voltage of the synchronous machine 1 via the instrument transformer 7,
Control calculation is performed so that this terminal voltage becomes the target value,
It outputs control signals CA, CB and CC.

The phase control units 8a, 8b and 8c receive the AC power supply voltage EA via the transformer 9 and use the AC power supply voltage as a reference phase to change the phase signals PA and PA which change according to the control signals CA, CB and CC. PB and PC are output.

The intermediate pulse selectors 10a, 10b, 10c select an intermediate phase signal among the phase signals PA, PB, PC and output phase signals PLA, PLB, PLC. That is, as shown in FIG.
Since a majority voting circuit is composed of 12 and OR 13,
For example, the phase signal PLA is a majority result of the phase signals PA, PB, PC. The failure detectors 14a, 14b, and 14c output the phase signals P input to the intermediate pulse selectors 10a, 10b, and 10c.
A, PB, PC and output phase signals PLA, PLB, PLC
In the comparison process, when a difference occurs between the value of the input signal and the value of the output signal, failure signals DA, DB, and DC are output. The comparison processing in the failure detection unit will be described later in detail.

The pulse output units 11a, 11b, and 11c each output a firing pulse at the phase indicated by the phase signals PLA, PLB, and PLC. The arrangement is such that the arc pulse PL is supplied to the thyristor rectifier 4. FIG. 3 is a circuit configuration diagram of the failure detection units 15a, 15b, and 15c.

Since the thyristor rectifier 4 has a three-phase uniform bridge connection, the phase signals PA, PB and PC and the phase signal PL
Each of A, PLB, and PLC has a signal for six phases, and FIG. 3 shows a signal for one phase.

The exclusive logic 14 calculates an exclusive OR of the phase signal PA output from the phase control unit 8a and the phase signal PLA output from the intermediate pulse selection unit 10a, and outputs the signal D1.
Is output.

The off-delay timer 17 sets the signal D2 to H when the signal D1 is on (hereinafter referred to as H at the signal level).
And the signal D1 is off (hereinafter referred to as L at the signal level)
Is continued for ta seconds, the signal D2 is set to L. The on-delay timer 17 sets the failure signal DA to H when the signal D2 remains H for tb seconds, and sets the failure signal DA to L when the signal D2 is L.

The failure detectors 14b and 14c are respectively
14a, and the phase signal PA
, The phase signals PB and PC are input, and the phase signal PL
The phase signals PLB and PLC are input instead of A, and the fault signals DB and DC are output instead of the fault signal DA. FIG. 4 is a waveform chart showing the operation of the failure detection unit 14a.

Since the thyristor rectifier 4 has a three-phase uniform bridge connection, the phase signals PA, PB, PC and the phase signal PL
A, PLB, and PLC each have signals for six phases, and FIG. 4 shows signals for one phase. Period t ₄
Indicates that the phase signal PA has a normal value and the phase signal P
Since the value is the same as LA, the signal D1 indicates L, and the signal D2 and the fault signal DA also indicate L.

The period t ₅ indicates a state in which the phase signal PA has a normal value but has a slight difference from the phase signal PLA. Since the signal D 1 becomes H during the period of the difference, the signal D 2
Also goes high, but after ta seconds goes low, so the fault signal DA remains low.

The period t ₆ is a state in which an abnormality has occurred in the automatic voltage adjustment unit 6a or the phase control unit 8a and the phase signal PA has an abnormal value, and the signal D1 has a difference from the phase signal PLA only during the period. Becomes H, the signal D2 also becomes H, and since the period of the signal D1 being L is shorter than ta seconds, the signal D2 becomes H.
And the failure signal DA becomes H after tb seconds.

The time period ta of the off-delay timer 17 is the period of the AC power supply EA (0.02 seconds when the AC power supply EA is 50 Hz).
Therefore, when the difference between the phase signal PA and the phase signal PLA becomes 10% or more of the cycle of the AC power supply EA, the signal D2 continues to be in the H state. The time period tb of the on-delay timer 18 is set to five times the cycle of the AC power supply EA. If the signal D2 is kept at H for tb seconds or more, the failure signal DA becomes H. The time period ta of the off-delay timer 17 and the time period tb of the on-delay timer 17 can be changed.

As described above, the failure detection unit 15a detects a state in which an abnormality has occurred in the automatic voltage adjustment unit 6a or the phase control unit 8a and the phase signal PA indicates an abnormal value, and the failure signal D
A is output.

The failure detectors 15b and 15c are respectively
As in the case of 15a, an abnormality occurs in the automatic voltage adjusting units 6b, 6c or the phase control units 8b, 8c, and the phase signals PB, PC
Detects a state in which an abnormal value is indicated, and outputs a failure signal DB,
Output DC.

As described above, when a failure occurs in one of the tripled automatic voltage regulators 6a, 6b, 6c and the phase controllers 8a, 8b, 8c, the failure is detected by the failure detector.
15a, 15b, 15c to detect reliably and quickly,
Failure signals DA, DB, and DC can be output. The present invention is not limited to the above embodiment.

The setting of the time period ta of the off-delay timer 17 and the time period tb of the on-delay timer 17 can be changed.
The performance and characteristics of 15a, 15b and 15c may be changed.

Further, a self-diagnosis function for detecting its own abnormality and outputting a failure signal is added to the automatic voltage adjusting units 6a, 6b, 6c and the phase control units 8a, 8b, 8c, and the failure signal and the failure signal DA are added. , DB, and DC together to output an alarm does not change the gist of the present invention.

[0040]

As described above, according to the present invention,
Since a series of failures in the triple control device can be detected reliably and promptly, the average repair time can be reduced and the operation rate can be increased. In other words, when a failure is detected, the time from the occurrence of the failure to the repair can be shortened by immediately repairing the failure while the operation is continued.

As a result, an extremely reliable synchronous machine excitation control device can be provided in which the average repair time can be greatly reduced as compared with the case where the occurrence of a failure cannot be detected, and therefore a remarkable effect can be obtained in improving the operation rate. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an excitation control device of a synchronous machine according to an embodiment.

FIG. 2 is a configuration diagram of an intermediate pulse selection unit and a failure detection unit according to the embodiment.

FIG. 3 is a circuit configuration diagram of a failure detection unit according to the embodiment.

FIG. 4 is an operation waveform diagram of a failure detection unit according to the embodiment.

FIG. 5 is a configuration diagram of a conventional excitation control device for a synchronous machine.

FIG. 6 is a configuration diagram of a conventional intermediate pulse selection unit.

FIG. 7 is an operation waveform diagram of a conventional excitation control device for a synchronous machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Synchronous machine, 2 ... Field winding, 3 ... Field circuit breaker, 4 ... Thyristor rectifier, 5 ... Transformer for excitation, 6a, 6b, 6c ...
Automatic voltage regulator, 7… Transformers for instruments, 8a, 8b, 8c
... Phase control unit, 9 ... Transformer, 10a, 10b, 10c ... Intermediate pulse selection unit, 11a, 11b, 11c ... Pulse output unit, 12 ... Logical sum unit, 13 ... Logical product, 14 ... Logical sum, 15a, 15b , 15c ...
Failure detection unit, 16: exclusive OR, 17: off-delay timer, 18: on-delay timer, CA, CB, CC: control signal, EA: AC power supply voltage, PA, PB, PC, PL
A, PLB, PLC: phase signal, PL: firing pulse, D
A, DB, DC: Failure signal.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02P 9/30

Claims (1)

(57) [Claims] 1. Three automatic voltage adjusters for inputting terminal voltages of a synchronous machine and outputting control signals for adjusting the terminal voltages, respectively; and control signals output from the automatic voltage adjusters, respectively. A phase signal from each of the phase controllers, three intermediate value selectors for selecting and outputting an intermediate value among the three inputs, and Three fault detectors that output an alarm when the difference between the phase signal output from the controller and the phase signal output from the intermediate value selector is equal to or greater than a set value and continues for a set time or more; Three pulse output units for outputting a firing pulse based on the phase signal selected in the above; a logical sum unit for performing a logical sum process on the three firing pulses output from the pulse output unit; By the signal output from the sum And a thyristor rectifier that is controlled and outputs an exciting current to a field winding of the synchronous machine.