JP2580009B2 - Operation control device for synchronous machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to an operation control device for main equipment such as a generator, a main transformer, and an in-house transformer of a hydroelectric power plant.

(Prior Art) The operation control device of a hydroelectric power plant shown in FIG.
At the time of starting, as shown in Fig. 3, excitation was applied at 80% of the generator rated rotation speed (time ta), and when the generator voltage phase and frequency matched the system bus voltage, phase, and frequency, Normally, startup control is performed so as to be arranged along the bus. The solid line in FIG. 3 represents a characteristic curve representing a change in the generator voltage V, and the dotted line represents a characteristic curve representing the generator speed N.

For example, if a system fault or the like occurs on the system bus 11A after the parallel operation, the generator voltage of the generator 17 falls, but the
Since the generator rotation speed of 17 is rotating at the rated rotation speed, the voltage / frequency (hereinafter referred to as V / F) value represented by the ratio between the generator voltage and the frequency is low.

On the other hand, when the trip coil (not shown) of the field breaker 18 is disconnected during the stop control and tripping is disabled, the generator voltage of the generator 17 is constant and the frequency is reduced, so that the V / F value is Get higher. When this V / F value becomes high, the generator 17 becomes overexcited and overheats.

The cause of this overheating is the saturation of magnetic flux caused by V / F overexcitation in the iron core, which is a magnetic circuit. It is caused by eddy current overheating. This results in V /
When the F value increases, the generator 17 overheats, and in some cases, may be damaged.

In order to avoid this damage, conventionally, a generator voltage is monitored by a voltage relay 41, a voltage value is set in advance, and a circuit is configured to stop the generator 17 when the voltage value exceeds the set value.

FIG. 2 shows a time chart at the time of stop control. The horizontal axis shows time, and the vertical axis shows generator speed 23, generator voltage 24, exciting current 25, and V / F value 26. 22 is the main engine data (generator speed).
23, generator voltage 24, exciting current 25, V / F value 26).

When the generator 17 is stopped, the main engine maintains the generator rotation speed 23, the generator voltage 24, and the V / F value 26 at the rated values until the system disconnection point 21.

When the system disconnection point 21 is reached, the line breaker 11 is opened and the generator 17 is disconnected from the system bus 11A, so that the generator speed 23 decreases.

After opening the in-line circuit breaker 11, the excitation circuit is disconnected and the generator voltage 24 decreases. (Not shown.) However, for some reason, the field circuit breaker 18
If the voltage is not released, the automatic voltage regulator 13
To maintain the rated value even after the system disconnection point 21, and to apply an excessive excitation current 25 to correct the decrease in the generator voltage 24 caused by the instantaneous decrease in the generator speed 23. Become. It is said that the excessive exciting current 25 becomes 4 to 5 times the rated value. On the other hand, the generator rotation speed 23 is
After that, the V / F value 26 rises because it also decreases. As a result, there is a problem that the main equipment of the power plant, such as the generator 17 and the main transformer 14, is placed in an overexcited state, causing a temperature rise and insulation deterioration.

[Problems to be solved by the invention]

As described in the related art, overheating of the main engine caused by the ratio of the V / F value occurs when the ratio between the generator voltage and the number of revolutions (frequency) of the generator exceeds an allowable value. Generally, the generator is operated so that the ratio between the voltage and the rotation speed does not exceed an allowable value.

Therefore, as a fundamental problem, the voltage and rotation
Therefore, there is a problem that the operation control of the main engine must be performed in view of the above ratio.

The voltage / frequency ratio of the main equipment such as the generator and the main transformer of the hydroelectric power station is increased, and the required equipment of the power station is prevented from being damaged due to overheating.

[Configuration of the invention]

 (Means for Solving the Problems) In order to achieve the above object, a description will be given with reference to the drawings.

FIG. 1 is a view showing one embodiment of the present invention.
That is, the parallel circuit breaker 11 connected in parallel to the system bus 11A
And the main transformer 14, which is connected in series with the parallel circuit breaker 11,
And a generator 17 connected in series with the main transformer 14. On the other hand, the automatic voltage regulator 13 for the excitation device is connected via the excitation transformer 12 and connected to the gate circuit of the excitation rectifier 19. The over-excitation relay 16 is connected to the main bus via the protection relay transformer 15.

The field winding of the generator 17 is connected to an excitation rectifier 19 via a field breaker 18.

The field breaker 18 is connected to a field break trip disable detector 18A for detecting a trip disabled state of the field breaker 18.

(Operation) When the generator 17 is stopped, the output of the generator 17 is reduced, the parallel circuit breaker 11 is opened with no load, the field circuit breaker 18 is cut off, and the generator 17 is stopped. In the case of an emergency stop, the field breaker 18 is released at the same time as the parallel breaker 11 is released, the excitation circuit is disconnected, and the generator 17 is normally controlled to stop. In order to detect the trip impossible state of the field breaker 18, the field breaker trip impossible detecting device 18
A, when the field breaker 18 cannot be tripped due to any cause such as disconnection of a trip coil (not shown), that is, up to the system disconnection point 21 as shown in FIG. The generator speed 23, generator voltage 24, and V / F value 26 maintain their respective rated values, but generator 17 was disconnected from the system 11A, but when the field breaker 18 became incapable of tripping, the generator Speed
23 decreases. However, the automatic voltage regulator 13 uses the generator voltage 24
Works to maintain the rated value at 22, the excessive excitation current 25 flows to compensate for the instantaneous voltage drop, while the generator speed
Since 23 falls, the V / F value 26 rises. At this time, the over-excitation relay 16 exceeds the set value, and the over-excitation relay 16 operates. At this time, an AND signal of the output signal and the output signal of the field breaker trip disable detection device 18A is input to the automatic voltage regulator 13, the gate is cut off, the exciting current 25 is cut off, and the V of the generator 17 in the stop control is controlled. Control can be performed to prevent the abnormal rise of the / F value 26 and to safely stop the generator 17.

Although the above example has been described using the generator, the protection control can be similarly performed even when the power generator (synchronous motor) is operating in cooperation with the system.

When the rotation speed of the generator / motor is reduced due to loss of input after the generator / motor is parallel to the system bus, when the V / F value exceeds a specified value set in advance by the overexcitation relay, the overexcitation relay Based on the output signal of the device and the output signal of the field breaker trip disable detection device, the gate of the exciting device is shut off via the automatic voltage regulator, the exciting current is interrupted, and the exciting current of the generator is reduced to generate power. Motivation can be safely stopped.

〔The invention's effect〕

As described above, according to the present invention, when the generator or the generator has a voltage drop due to a loss of input or a system failure during operation and the main engine is operated for emergency stop, the trip coil of the field breaker is operated. When the main engine is stopped in the event that it cannot be opened due to a failure due to disconnection or the like, control is performed so that the voltage and frequency ratio are kept to a certain value or less.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a time chart for explaining an operation at the time of stop, FIG. 3 is a time chart of a system parallel operation, and FIG. FIG. 11 ... Breaker for parallel insertion, 11A ... System bus 12 ... Transformer for excitation, 13 ... Automatic voltage regulator 14 ... Main transformer, 15 ... Transformer for protective relay 16 ... Overexcitation relay , 17… Power generator 18… Field circuit breaker 18 A… Field circuit breaker trip disabled detector 19… Excitation rectifier, 21… System disconnection point 22… Main engine rated value, N, 23: Generator speed V, 24: Generator voltage, 25: Excitation current 26: Voltage / frequency ratio, 41: Voltage relay

Claims (1)

(57) [Claims] An operation control device for a synchronous machine that operates in parallel with a system via an in-line circuit breaker for detecting a non-operation of a field circuit breaker during operation stop control of the synchronous machine. Circuit breaker disable detection means, overexcitation detection means for outputting an overexcitation signal when a ratio between the output voltage and the frequency of the synchronous machine is equal to or higher than a set value, and field breaker disable detection means When the magnetic circuit breaker is inactive and overexcitation is detected by the overexcitation detection means,
An operation control device for the synchronous machine, comprising: exciting means for stopping excitation of the synchronous machine.