JPS6032599A - Excitation controller for synchronous generator - Google Patents

Abstract

PURPOSE:To prevent the trip of a generator due to a field failure relay for insufficient excitation side defect of an AVR by mounting a low excitation limiter and a low excitation protecting unit similar in a hardware. CONSTITUTION:When an automatic voltage regulator 28 is used to control the terminal voltage of a synchronous generator 1 constant, a calculator 10 becomes defective and continuously outputs the maximum drop voltage. In this case, the field current of the generator 1 decreases to lower the terminal voltage of the generator. When the terminal voltage of the generator decreases, a leading phase reactive power flowed from the system side to the generator increases. When the reactive power reaches the prescribed value, a low excitation limiter 9 is operated to output a voltage rise signal. When the leading phase reactive power further increases, a low excitation protecting unit 16 is operated to switch from the regulator 28 to a field current controller 29. Thus, an excitation controller which has high reliability can be obtained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides an excitation control device for a synchronous generator, in which the excitation side f
The present invention relates to an excitation control device for a synchronous generator suitable for detecting a lower side failure of an i11 device and switching to a manual system or other automatic system to continue operation before the synchronous generator trips by a field loss relay.

[Background of the invention]

A conventional example is shown in FIG. In the figure, II'i1'pj
2 is a field winding, 3 is an excitation transformer, 4 is a thyristor rectifier, 5 and 6 are electric transformers, 7゜27
1 is a current transformer, 8 is a field loss relay (4 (11°28 is an automatic voltage regulator I A V R,), 29 is a manual field current suppressor I A E ), and 1. ), 9 is a low excitation limiter + UEL), 10.11 is an arithmetic circuit, 12
13 is a switching circuit that is closed when the automatic system is used, 13 is a switching circuit that is closed when the manual system is used, and 14 and 15 are Katehals generators that generate gate pulses for the thyristor.

In this system, automatic thread A V 11.28
In order to limit the terminal voltage of the synchronous generator 1 to a constant value using
The field current of the generator is changed by changing the control input of and controlling the firing phase side angle α of the thyristor 4. At night, the load on the grid is lighter, so when the voltage on the grid side rises, the excitation of the generator is weakened in an attempt to control the generator terminal voltage to a constant level, resulting in insufficient excitation and phase-advanced reactive power being generated from the grid side]. This may cause the synchronous generator to enter phase-advanced operation. When the phase-advanced reactive power Q of the synchronous generator increases, the stator end of the generator overheats and the stability of the system decreases. When the level is reached, a raise command is given to the AVR to limit the low excitation of the synchronous generator and ensure stable operation.

However, the AVR's arithmetic circuit 10 or pulse generator 1
Due to the failure of item 4, the AVR continues to output the maximum signal and the field current of the fc field generator rapidly decreases, resulting in a loss of field, which causes the generator to trip due to the field loss relay (40). was there.

FIG. 2 shows the interlock when the phase-advanced reactive power becomes large and when the field is lost.

If AV[ is normal, it will lead to field loss, UELkJ
Only the control of J work is available, but in case of AV general failure, UEL is available.
Since the limit is not effective, the field loss relay operates and the generator trips.

[Purpose of the invention]

An object of the present invention is to prevent a generator from tripping due to an underexcitation Ill failure in an AVR system, and to provide a highly reliable excitation side (n@ position).

[Summary of the invention]

The present invention is a low excitation limiting device ([Moon (L) and UF]).

In addition, another device is installed to detect the state of low excitation.
If this device operates, it will be treated as a failure of the AV 11, and the system will be switched to another control system.

[Embodiments of the invention]

The present invention will be explained in detail below.

The locus of effective force and reactive power at the time of yf-magnetic loss of the synchronous generator is shown in Fig. 3, and the locus of impedance is shown in Fig. 4. Now, in Figure @3, the synchronous light 1jj' hi is operating with active power Po and reactive power Qo (point A), and the A VR under-excitation side failure occurred at time [=0.9→Synchronized time 1 ．．
The operating point B of LIEI is reached, and the time shown in Fig. 4 [
3, the field loss relay reaches operating level I), leading to a generator trip.

This time varies depending on the excitation method depending on the synchronous power generation, and in the father-flow excitation method, L2 is about 2 to 3 seconds, L3I'i
Since the thyristor excitation method has a quick response, tl+t21 is about 1 second, and L3 is about 3 seconds. This means that when the field is lost due to an AVR failure, the UEL
It takes about 2 to 3 seconds for the father-flow exciter method and about 2 seconds for the thyristor excitation method until the field loss relay (40) operates after the operation of the field loss relay (40). ! : Became a VC.

Therefore, in addition to UEL, a low excitation limiting device i [JEl'] is installed to detect another low excitation state, and as shown in the third example, the UEP operating level 'e
ii side), UEP operates and fCts
＠ is regarded as a failure of AV ) (, and if the switch is made to another healthy control system within about 2 to 3 seconds after UEP starts operating, operation will continue without causing a Ko'tunki trip. be able to.

This time of 2 to 3 seconds is sufficient time to exclude the failed AVR and switch to a healthy control system.

In FIG. 5 where UEP is provided, 2 and 1 to 15.27 are the same as in FIG. 1, and 16 is UEP.

Like the UEL, the UEP is a device that detects when the reactive VIE force of the synchronous generator decreases and enters a low excitation state. In this system, during operation with AVR, 2B, which is an automatic thread, at time [=0, A, V H, calculation circuit 1
If a failure occurs at 0 and AVJ (, continues to output a signal below the maximum value), then the firing phase control angle α of the gate pulse generator 14 is adjusted to reduce the output voltage of the iris 4.
In order to maximize this, the field current of the generator decreases and the generator terminal voltage decreases. As the generator terminal voltage decreases, the phase-advanced reactive power flowing into the generator from the grid increases, and UEL decreases to 14 Vr- at time 1. 2, it operates and gives the AVR a high signal, but the AVR's arithmetic circuit is malfunctioning, so the generator voltage continues to drop dramatically.
The operating point B of L is exceeded and the operating point C of U E I' is reached at time L2.

Therefore, UEPtfc detected (F) A V RO under excitation side failure due to the operation of (JEL and UE 1).
'lj is disconnected, the automatic system is switched to the manual system, and the thyristor output voltage is almost restored to the value before the failure, thereby preventing the generator from tripping due to field loss relay (40) and allowing operation to continue. . -! Even if the automatic system gate pulse generator 14 has an under-excitation failure due to pulse loss, the automatic system can be switched to the manual system and the operation can be continued.

FIG. 6 shows another embodiment as a modification.

The difference from Figure 5 is that the manual system is replaced by the automatic system AVR.
This is an example of duplicating VR, with A system A and VR-A3
0, j3 system kAVR, -831.

In this system, in the A VR-A30, the under-excitation side failure occurs during operation, and similarly, UEPf'
fL can switch to the B system and continue operation by the operation of UEL and tJEP.

FIG. 7 shows an interlock against an under-excitation side failure in the embodiments shown in FIGS. 5 and 6. UEP
The automatic tracking device I FLUCl is locked by the operation to avoid unsatisfactory tracking of the manual system and B output, and the failed AVR is
shall be excluded and switched to a healthy manual thread or B system.

〔Effect of the invention〕

According to the present invention, by simply installing a drinking/excitation holding circulation device (t) which is similar in terms of hardware to the low excitation limiting device (f), the field loss relay (( 40), and it is possible to provide an excitation side n device that is reliable and inexpensive without having to use a /2 system configuration such as triplexing.

[Brief explanation of the drawing]

Fig. 1 shows an example of a conventional embodiment, Fig. 2 shows a conventional interlock in the case of under-excitation side failure, Fig. 3 shows the active reactive power trajectory when the field is lost, and Fig. 4 shows the impedance trajectory when the 51i-magnetic field is lost. , @5 is one embodiment of the present invention, FIG. 6 is another embodiment of the present invention, and FIG. 7 is an interlock in the case of an AVR non-excitation side failure in the second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Synchronous generator, 2... Field winding, 3... Excitation power supply transformer, 4... Thyristor rectifier, 5, 6.2
1... Voltage transformer, 7, 22.27... Current transformer, 8... Field loss relay (40), 9.23... Low excitation limiting device ([JEL), 10... automatic system calculation circuit,
11°°. Manual system calculation circuit, 12... Automatic system switching circuit, 13...
- Manual thread switching circuit, 14... Automatic system gate pulse generator, 15... Manual system gate pulse generator, 16.24
...Low excitation protection device + [JEP], 17...A thread switching circuit, 18...B thread switching circuit, 19...A system gate pulse generator, 20...B system gate balne generator ,
25...A thread calculation circuit, 26...B thread calculation circuit, 2
8...Self! l1II voltage adjustment device (AVRJ, 29.
...Field current control device (AER), 30...A thread automatic voltage regulator +AVI (, -A,), 31...B
Thread automatic voltage regulator + AVI (, -B), 32... Phase advanced reactive power large, 33... Low excitation limiter operation, 34.
...Alarm, 35...Field loss relay operation, 36...
Unit trip, 37... Departure output curve,
38... LIEL operation level, 39... UEP operation level, 40... Active/reactive power trajectory at the time of field loss,
41... Impedance locus when field is lost, 42...
- Field loss relay (40) operating area.

Claims (1)

[Claims] 1. Automatic 1L that controls the terminal voltage of the synchronous generator at a constant level.
A synchronous system consisting of a voltage regulator, a gate pulse generator that generates a thyristor firing pulse in accordance with the output of the automatic voltage regulator, and a thyristor rectifier that controls the field current of a synchronous generator or AC exciter. The excitation control side 1 device for power generation monitoring is equipped with a low excitation limiting device that limits underexcitation of the synchronous generator and a low excitation protection device that detects when the low excitation limit value is exceeded. An excitation open side 1 device for a synchronous generator characterized by detecting a failure on the magnetic loss side and switching to another healthy system to continue operation before the generator trips due to a field loss relay.