JPS6328282A - Braking method for generator - Google Patents

Abstract

PURPOSE:To safely and effectively stop the rotation of an armature by mechanically braking a generator by means of generative braking when the rotating speed of the generator becomes a predetermined speed or lower. CONSTITUTION:When a stop command is applied to stop the rotation of the armature of a generator 1, a breaker 3 for the generator and a field breaker 13 are first opened to interrupt a field current. Then, a disconnecting switch 2 is closed to shortcircuit an armature winding 1a. Thus, a generative braking is executed to mechanically brake the generator when the rotating speed of the armature becomes approx. 2% of a rated speed. When the generative brake malfunctions, a mechanical brake controller 51 mechanically brakes the generator by driving a mechanical brake 50 as the speed of the armature drops approx. 20% or lower of the rated speed after a counting timer 30 finishes counting of a predetermined time.

Description

[Detailed Description of the Invention] C & Field of Industrial Application] The present invention relates to a method for braking a generator, and more specifically, it proposes a braking method that performs mechanical braking after starting dynamic braking.

[Prior art]

In the case of modern generators that rotate at high speed due to increased capacity, the rotational energy of the armature is extremely large. Therefore, with mechanical braking, there are thermal constraints due to heat generation, and it takes a long time to stop.
The play 4/nu of the 9JJ device on the machine side was also severely worn. Therefore, attention is being paid to a method that performs dynamic braking during normal times and mechanical braking during emergencies.

For example, an electric circuit for braking a generator using the Cyrisk excitation method is as shown in FIG.
is connected to a main transformer 4 via a generator circuit breaker 3, and outputs the generated power boosted by the main transformer 4. Each end of the field winding 1b of the generator 1 is connected via a field circuit breaker 13.13 to the output side of a thyristor bridge 12 that controls the magnetizing current. The input side of the Cyrisk bridge 12 is connected to the 1-circuit l connecting the generator circuit breaker 3 and the electric machine r winding 1a via the AC side circuit breaker 14 and the excitation phase changer FF 6. It is connected to an in-house AC power source (not shown) via an AC circuit breaker I5. The -1 circuit ρ has 1tlir for dynamic braking! When 8 devices 2 are connected to 13, electricity is generated by closing this disconnector 2! 7
The first winding 1a is short-circuited. Also, the circuit p
Automatic voltage through the δ1 transformer 5! 1! J regulator 7, switching switch, 1,8 and day 1 pulse Q 'LA'
r+'' are connected in series, and the phase control of the thyristor bridge 12 is controlled by the firing signal of the D1-pulse generator 11, and the generated voltage of the generator 1 is automatically adjusted. The switching operation selects the automatic voltage regulator 7, the dynamic braking firing angle control circuit 9, and the inverter operation firing angle control circuit 10.

In this control circuit, when a stop command is given to stop the rotation of the generator 1, first the generator circuit breaker 3 and the field circuit breakers 13 and 13 are opened and the field of the generator 1 is turned off. Cut off the current. When the generated voltage of the generator 1 becomes only a residual voltage, the dynamic braking disconnector 2 is closed to short-circuit the armature winding 1a.

Subsequently, after opening the AC side circuit breaker 14, the changeover switch 8
Switch to the dynamic braking firing angle control circuit 9 side, field circuit breaker 1
3.13 and AC side circuit breaker 15 are closed.

Since the field circuit breaker 13.13 and the AC side circuit breaker 15 are closed, the field winding 1b of the power generator IJ31+ is controlled to fire from the station power source by the dynamic braking firing angle control circuit 9. An excitation current approximately equal to the rated current of the generator I is passed through the thyristor bridge 12.

This performs dynamic braking.

The current during this dynamic braking is However, I: Current during dynamic braking S: Slip ■= Generator voltage R: armature resistance Xd: synchronous reactance becomes.

Then, after confirming that the armature has stopped rotating, the field circuit breakers 13 and 13 are opened to complete the series of braking operations. A method of stopping the armature by performing such dynamic braking is described in patent 788904.80F+651,8]940
9, 1186744.1214436, etc.

[Problem that the invention seeks to solve]

According to the conventional generator braking method described above, even if control is performed to perform dynamic braking, there may be a malfunction in the ignition control of the thyrisk bridge for passing excitation current to the field winding, or a malfunction of the generator. If the dynamic braking malfunctions due to a malfunction in the main circuit, etc., it will take a long time for the armature to stop rotating, and there is a risk of burning out the thrust bearing.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a braking method that safely and reliably stops the rotation of an armature even when dynamic braking is malfunctioning.

[Means for solving problems]

In the method for braking a generator according to the present invention, mechanical braking is performed after a predetermined period of time has elapsed after performing dynamic braking and when the number of rotations of the armature has decreased to a predetermined number of rotations or less.

[Effect]

After a predetermined period of time has elapsed with the start of dynamic braking, if the rotation speed of the armature of the generator is below the predetermined rotation speed, mechanical braking is performed. This ensures that the armature stops rotating in a short time.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments thereof.

FIG. 1 is a generator control circuit diagram for carrying out the method according to the invention. In FIG. 1, an armature winding 1a of a generator I is connected to a main transformer 4 via a generator circuit breaker 3, so that the boosted generated power is sent out via the main transformer 4. It has become. Further, the power generation unit 111 is provided with a rotation sensor 2o for detecting the rotation speed of an armature having an armature winding 1a. Field winding 1b of generator l
Each end of the field winding 1 is connected to the field winding 1 via a field circuit breaker 13.13.
It is connected to the output example of the silis bridge 12 that controls the current of b. The input side of the thyristor bridge 12 is connected to a main circuit p that connects the generator circuit breaker 3 and the armature winding 1a via an AC circuit breaker 14 and an excitation transformer 6.
It is also connected to an in-house AC power source (not shown) via an AC circuit breaker 15. A disconnector 2 for dynamic braking is connected to the main circuit p, and the closing of the disconnector 2 short-circuits the armature winding 1a. Also, the main circuit p
An automatic voltage regulator 7, a changeover switch 8, and a gate pulse generator 11 are connected in series via an instrument transformer 5, and the ignition signal of the gate pulse generator 11 activates the thyrisk bridge 12. I'm trying to turn on the arrogant Irista. Further, the automatic voltage regulator 7, the dynamic braking firing angle control circuit 9, and the inverter operation firing angle control circuit 10 can be selected by switching the changeover switch 8. 1. It's turning into a sea urchin. The dynamic braking firing angle control circuit 9 also includes a clock timer 30 that starts counting a predetermined time T from the start of braking when the firing angle control circuit 9 is operated to perform dynamic braking. It is set up. The predetermined time 'r is set to be slightly longer than the time required for the armature to stop rotating if the dynamic braking is performed reliably.

The clock timer 30 and the nI rotation sensor 20 detect the number of rotations.1. The signal is given to a mechanical brake control device 51 that drives a mechanical brake device 50 provided with brake shoes. When the dynamic braking is performed normally, when the rotational speed of the armature detected by the rotation sensor 20 drops to approximately 2% or less of the rated rotational speed, the mechanical braking control device 51 activates the mechanical braking device 1131. 50 to mechanically brake the armature. On the other hand, if the braking is malfunctioning even though the dynamic braking has been performed, it is after 1 o'clock of the predetermined time T determined by the clock timer 30, and the rotational speed of the armature detected by the rotation sensor 20 is the predetermined rotational speed. When the number, for example, becomes approximately 2% of the rated rotational speed or less, the mechanical braking control device 51 drives the mechanical braking device 50 to perform mechanical braking of the armature.

The braking operation of the generator by the generator control circuit configured in this way will be explained with reference to FIGS. 1 and 2. FIG. FIG. 2 is a braking characteristic curve in which the horizontal axis is time t and the vertical axis is the rotation speed N of the generator armature.

Now, when a stop command is given to stop the rotation of the armature of the generator 1, the generator circuit breaker 3 and the field circuit breaker 13, 13 are first opened to interrupt the field current. When the generated voltage of the generator 1 becomes only a residual voltage, the dynamic braking disconnector 2 is closed to short-circuit the armature winding 1a. As a result, the rotational speed N of the armature gradually decreases as shown by curve A from time point EO toward point 11. Subsequently, after opening the AC side circuit breaker 14, the changeover switch 8 is switched to the dynamic braking firing angle control circuit 9 side, and the field circuit breakers 13, 13 and the AC side circuit breaker 15 are closed.

As the field circuit breaker 13.13 and the AC side circuit breaker 15 are closed, the field winding 1b of the power generator 115Il is controlled to fire by the thyristor from the in-house AC power supply by the power generation braking firing angle control circuit 9. An excitation current approximately equal to the rated current of the power generation tJ3II is caused to flow through the silice bridge 12. As a result, dynamic braking is performed at the time point, and the time point [
1, the armature rotation speed N rapidly decreases as shown by curve B. Mechanical braking is performed when the rotational speed of the armature reaches approximately 2% of the rated rotational speed, and the rotation of the armature is completely stopped at time L2. Therefore, when the dynamic braking is performed normally, the 11 o'clock timer 30 is set to δ1 o'clock for the predetermined time T.
The braking operation ends before reaching .

By the way, as mentioned above, even though the dynamic braking was performed at time point [1], if the dynamic braking malfunctions due to the ignition of the syrisk bridge 12 or a malfunction in the circuit connected to the armature winding 1a, etc. In this case, the rotational speed N of the armature gradually decreases as shown by curve C. In parallel with this dynamic braking operation, the 81 o'clock timer 30 starts δ1 o'clock from time t1, and after finishing δ1 o'clock of the predetermined time T,
When the rotational speed N of the armature reaches a time point L3 at which it drops to approximately 20% or less of the rated rotational speed, the mechanical braking control device 51 drives the mechanical braking device 50 to perform mechanical braking. Therefore, the rotational speed N of the armature drops extremely rapidly as shown by the curved line, and the rotation is completely stopped within a short period of time.

In this way, the rotational speed of the armature is first lowered by dynamic braking, and after a predetermined period of time has elapsed since the dynamic braking, mechanical braking is performed when the rotational speed has fallen below the predetermined rotational speed. Therefore, even if the dynamic braking is malfunctioning, the rotation can be stopped in a short time without requiring a long period of time. Furthermore, since mechanical braking is performed until the rotational speed reaches a low rotational speed range, there is less wear on the brake shoes of the mechanical braking device. Furthermore, by bringing the high-speed rotating armature to a halt in a short period of time, the bearing of the thrust 1-hair ring is not damaged.

In this embodiment, mechanical braking was performed in parallel with the dynamic braking, but it goes without saying that the mechanical braking may be performed independently.

〔effect〕

As described in detail above, the present invention provides, after performing dynamic braking,
Apply mechanical braking to completely stop the rotation of the generator armature in a short time. Therefore, even in the unlikely event that the dynamic braking malfunctions, it will not take a long time to stop and the 7-ring thrust bearing will not be damaged.

In addition, since mechanical braking is performed when the rotation of the armature reaches a low speed range, excellent effects such as less wear on the brake ring 1- can be achieved.

[Brief explanation of drawings]

Fig. 1 is a control circuit diagram of a generator implementing the method of the present invention, Fig. 2 is a braking performance +') curve diagram of the armature according to the method of the present invention, and Fig. 3 is a diagram for performing the conventional braking method. FIG. 2 is a control circuit diagram of a generator. 1... Generator 1a... Armature winding 1b... Field winding 20... Rotation sensor 30... Clock timer 50
...Ta mechanical braking device 51... Mechanical braking control device In the drawings, the same reference numerals indicate the same or corresponding parts. Agent Masu Oiwa

Claims (1)

[Claims] 1. In a generator braking method that uses dynamic braking to stop the rotation of the generator, after a predetermined time has elapsed after starting dynamic braking, the rotation speed of the generator is equal to or lower than the predetermined rotation speed. A method for braking a generator, characterized in that mechanical braking is performed when .