JPH0136359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an excitation control device for a synchronous machine, and particularly to an excitation control device suitable for performing gate control of a thyristor excitation device for a large-capacity synchronous generator.

Conventionally, a configuration using a thyristor rectifier, that is, a thyristor excitation device, has been known as an excitation device for a synchronous generator, but in response to the recent trend of increasing single generator capacity and long distance power transmission, From the point of view of transient stability, one effective method is to use a thyristor excitation device with a quick response as the excitation device.

Figure 1 is a schematic configuration diagram showing an example of a conventional excitation control device using a thyristor excitation device.
2 is the generator armature, 2 is the generator field, 3 is the field insulator and disconnector for intermittent field current, 4 is the discharge resistor, and 5 is the circuit that gives initial excitation to the field 2 from the DC power supply 22. 6 is a thyristor for initial excitation that controls initial excitation, 7 is a rectifier for commutation protection of the thyristor 6, and 8 is a thyristor excitation that controls the field 2. device, 10
is the power transformer of the thyristor excitation device 8, 13
14 is an automatic voltage regulator that receives the output of the voltage transformer 13 and provides a voltage control output; 15 is a gate for the thyristor excitation device 8 based on the voltage control output; A gate pulse generation circuit that generates pulses; 17 a gate pulse amplifier that amplifies the output of the gate pulse generation circuit 15 and supplies it to the thyristor excitation device 8; 12 an automatic voltage regulator 14, a gate pulse generation circuit 15, and a gate pulse amplifier; This is a transformer that supplies auxiliary power and synchronous power to 17.

In such a configuration, when establishing the voltage from the generator non-excitation state, after closing the field switch 3, the field switch 5 to which the initial excitation power supply 22 is applied is closed, Next, the initial excitation thyristor 6 is turned on. As a result, the field current from the initial excitation power supply 22 gradually increases according to the field circuit time constant, and the generator voltage, which is the voltage generated by the generator armature 1, also gradually increases accordingly. This generator voltage is connected to the automatic voltage regulator 14 and the gate pulse generation circuit 1.
When the voltage rises to such a level that the excitation control system consisting of the pulse amplifier 5 and the pulse amplifier 17 becomes operable, a gate pulse is applied from the excitation control system to the thyristor of the thyristor excitation device 8, making the thyristor conductive. Thereafter, current is supplied from the generator output to the field 2 via the power transformer 10 and the thyristor excitation device 8, and the generator voltage increases to a predetermined voltage by the action of the automatic voltage regulator 14.

However, when the generator capacity increases and stability is to be improved, the output voltage of the thyristor excitation device 8 becomes so large as to threaten the withstand voltage of the field 2. That is, it is known that the output voltage of the thyristor excitation device 8 rises above the peak value of the sine wave AC power supply during thyristor commutation. Some kind of measure will be needed.

An effective method that can be considered to deal with this is to connect two thyristor excitation devices with different power supply phases in series, and apply half the power supply voltage to each thyristor excitation device compared to when only one thyristor excitation device is used. . In this case, since the ignition times of the two thyristor excitation devices are different, the peak voltage generation times of the two thyristor excitation devices are different, and therefore the peak voltage can be made smaller than when one thyristor excitation device is used.

However, when two thyristor excitation devices are connected in series in this way, it is necessary to make the two thyristor excitation devices conductive at the same time when starting current to flow through the thyristor excitation devices, but these two thyristor excitation devices are usually different. Since a gate pulse is applied at the point when the voltage is reached, there is a problem in that effective startup is not possible.

Therefore, an object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide excitation control that suppresses the excitation voltage by using thyristor excitation devices connected in series with different gate timings, and also enables effective starting control. We are in the process of providing equipment.

More specifically, the present invention applies gate pulses to two thyristor excitation devices at the same time only when changing the two series-connected thyristor excitation devices whose AC power supply phases are different from a non-conducting state to a conductive state. The present invention provides an excitation control device configured to ensure reliable activation of the thyristor excitation device and to prevent the excitation voltage from increasing due to different shift pulses thereafter.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram of an excitation control device according to an embodiment of the present invention, in which 10a is a first power transformer whose secondary side is delayed in phase by 30 degrees with respect to the primary side. , 11 is a second power transformer with the same phase on the primary and secondary sides, 12a is an auxiliary transformer for the auxiliary power supply and synchronous power supply, and 8a is the first power transformer from the output of the generator armature 1.
The first
9 is a second thyristor excitation device supplied with power from the output of the generator armature 1 via the second power transformer 11; 15a is a phase control device according to the output of the automatic voltage regulator 14; a first pulse generator, 17a, which generates a gate pulse;
16 is a first pulse amplifier which amplifies the pulse of the pulse generator 15a and supplies it as a gate pulse to the first thyristor excitation device 8a, and 16 is a phase amplifier which amplifies the pulse of the pulse generator 15a and supplies it as a gate pulse to the first thyristor excitation device 8a. The second pulse generator to be controlled, 18, is a second pulse amplifier that amplifies the output of the second pulse generator 16 and provides it as a gate pulse to the second thyristor excitation device 9. Note that the first pulse generator 15a is connected to the first thyristor excitation device 8a via the phase delay device 19 from the auxiliary transformer 12a.
The second
The pulse generator 16 is connected to the second pulse generator from the auxiliary transformer 12a.
A synchronizing signal having the same phase as the AC power source of the thyristor excitation device 9 is given. Further, 20 is an AC voltage relay, and 20a is an AC voltage relay 20 that closes when the generator voltage is higher than the set value of the AC voltage relay 20.
The contact 20b is a contact of the AC voltage relay 20 which is closed when the generator voltage is lower than a set value, and the reference 21 is an instrument transformer provided on the output side of the transformer 11 to detect the generator voltage.

The operation of the configuration as described above will be explained below.

In a normal operating state in which the thyristor exciters 8a and 9 are conducting, the alternating current relay 20 is in an operating state because the generator voltage exceeds the set value. Therefore, the contact 20a is closed, and the contact 20b is opened. At this time, the first and second thyristor excitation devices 8a and 9 are connected to the first and second pulse generators 15 whose synchronization signals are signals synchronized with the output voltages of the respective AC power supplies, that is, the transformers 10a and 11.
A and 16 outputs are amplified by the first and second pulse amplifiers 17a and 18, and the pulses obtained are given as gate pulses. Therefore, the first and second thyristor excitation devices 8a and 9 are mutually Gate pulses will be received at different times. The first and second thyristor excitation devices 8a,
There is no particular problem when the field 9 is energized, and operation can be performed with the overvoltage of the field 2 suppressed.

On the other hand, when the first and second thyristor excitation devices 8a and 9 are brought into a conductive state from a non-conductive state, the AC relay 20 is in an inoperable state because the generator voltage has not been established. . Therefore, the contact 20a is in an open state, and the contact 20b is in an open state.
is in a closed circuit state. Therefore, at this time, the output of the first pulse generator 15a is given to both the first and second pulse amplifiers 17a and 18, and the outputs of the first and second pulse amplifiers 17a and 18 are simultaneously given to the first and second pulse amplifiers 17a and 18, respectively. and the second thyristor excitation devices 8a and 9. Therefore, the first and second thyristor excitation devices 8a and 9 can be made conductive at the same time.

Now, to explain the case where initial excitation is applied to the generator from a non-excited state to establish a voltage, the field breaker 3 is closed and the initial excitation breaker 5 is connected to the initial excitation DC power source 22. After closing the circuit, when the thyristor 6 is fired, the field current of the field 2 gradually increases, and the output voltage of the generator armature 1 also gradually increases. In this case, when the generator voltage has not been established to a certain level, the first and second pulse amplifiers 17
The inputs of a and 18 are open, so the first
and the second thyristor excitation devices 8a and 9, but when the generator voltage becomes larger than the setting value of the voltage relay mentioned above, the output of the first pulse generator 15a is transferred to the first and second pulse amplifiers. 17
Since it is given to a and 18 at the same time, the first and second
The thyristor excitation devices 8a and 9 are simultaneously conductive. Note that when the generator voltage is significantly lower than the set value of the automatic voltage regulator 14, the gate pulse generation phase advances to the closest point, but the first pulse generator 15a
Since the synchronization signal is delayed by 30 degrees from the AC power source of the second thyristor excitation device, the gate pulse phase will not be too advanced. In the case of the thyristor excitation device for a large-capacity generator considered here, the output of the generator armature 1 is connected to the thyristor excitation devices 8a and 9 via the power transformer, and the thyristor excitation device 8
a, 9 to the generator armature 1 via the generator field 2
Since the positive feedback circuit up to the output has a sufficient amplification factor of 1 or more, the generator voltage further increases due to self-feedback.

As described above, when the generator voltage is established and becomes larger than the set value of the AC voltage relay 20, the contact 20b of the AC voltage relay 20
is opened and the contact 20a is closed, so the input of the second pulse amplifier 18 is now given from the second pulse generator 16, and therefore the second thyristor excitation device 9 is in phase with the AC power supply. The second pulse generator 16, which is controlled by the synchronization signal, enters the normal operating state.

As described above, according to the present invention, two thyristor rectifiers with different AC power phases, which are expected to increase in the future as excitation devices in generators for large-capacity long-distance power transmission, are connected in series. The problem of the gate control phase difference at the start of conduction of the thyristor excitation device, which reduces the voltage applied to the field, can be solved by driving two thyristor excitation devices with a synchronous AC power supply only at the start of conduction. It is possible to obtain a new excitation control device that can solve the problem, and its usefulness is extremely large.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a conventional excitation control device using a thyristor excitation device, and FIG. 2 is a schematic configuration diagram of an excitation control device according to an embodiment of the present invention. 1... Generator armature, 2... Generator field, 8
a, 9...thyristor excitation device, 10, 10a,
11... Power transformer, 12, 12a... Auxiliary transformer, 14... Automatic voltage regulator, 15, 15a, 1
6... Pulse generator, 17, 17a, 18... Pulse amplifier, 19... Phase delay device.

Claims (1)

[Claims] 1 The first and second connected in series to the field of the synchronous machine
a thyristor rectifier; an automatic voltage regulator that detects the voltage of the synchronous machine and amplifies the deviation from the set voltage; a first AC power source that supplies an AC voltage to the first thyristor rectifier; a second AC power supply for supplying an AC voltage having a phase different from the first AC voltage to the thyristor rectifier; and generating a gate pulse synchronized with the first AC voltage based on the output of the automatic voltage regulator. a first gate control device that generates a gate pulse synchronized with the second alternating current voltage based on the output of the automatic voltage regulator; A gate pulse is supplied to the first and second thyristor rectifiers from either one of the first and second gate control devices, and after starting the synchronous machine, a gate pulse is supplied from the first gate control device to the first thyristor rectifier. , and from the second gate controller to the second
1. An excitation control device for a synchronous machine, comprising a switching circuit that switches to supply gate pulses to each of the thyristor rectifiers.