JPS6236475B2 - - Google Patents

Description

[Detailed description of the invention] This invention can simplify the device configuration,
The present invention also relates to an electric brake device for a generator that can be used not only for electric braking but also for inspecting busbars. As is well known, electric braking is a method in which the generator circuit is short-circuited, a short-circuit current of about the rated current is applied, and the generator is braked by the I ² R loss schedule of the generator. As generators have become faster and larger these days, the rotational energy of the rotating parts is also large, and mechanical brakes are therefore subject to thermal constraints, which not only lengthens the stopping time but also increases the wear and tear of the brake shoes. Therefore, maintenance is also difficult. Therefore, the idea of using an electric brake to stop a regular generator and using a mechanical brake only in an emergency has been gaining attention.

An example of an electric brake in the case of a conventional low-pressure synchronous system will be explained with reference to FIG. 1 using a pumped storage power plant as an example. 1 is a generator motor, 2 is a disconnect switch for electric brakes, 3 and 4 are phase switching disconnect switches, and 3 is a reversible generator motor in which the direction of rotation of the generator motor is opposite during generation operation and pumping operation. is closed during power generation operation,
4 is a phase switching disconnector that is closed during pumping operation. 5
6 is a main transformer, 7 is a potential transformer (PT), 8 is an automatic voltage regulator (AVR), 9 is a ignition circuit (GPG), 1 is a rectifier circuit such as a thyristor bridge, 11 is an excitation transformer, 12 is a field breaker, 13 is a field discharge suppressor, 14 is an initial exciter and electric brake breaker, and 15 is a thyristor bridge therefor.

Next, the operation will be explained. When operating the generator 1, one of the phase switching disconnectors 3 and 4 is closed, and the edge breaker 5, field edge breaker 12, and edge breaker 14 are turned on. (However, the breaker 14 is only turned on at startup). Then, the output of the excitation transformer 11 is supplied to the field winding via the rectifier circuit 10 and the field cutter 12, and the generator 1 is operated.

Next, when stopping the operation of the generator 1, the shield disconnector 5 and the field shield disconnector 12 are opened, and when the terminal voltage of the generator 1 becomes only the residual voltage, the braking disconnector 2 is opened. is closed to short-circuit each phase of the generator 1. Then, the circuit breaker 14 is turned on, and current is supplied from the thyristor bridge 15 to the field winding so that the short circuit current flowing through the brake disconnector 2 is about the rated current, and the electric brake is applied. .

The current during electric braking in the conventional system is given by the following equation.

Here, I: Current during electric braking S: Slip V: Generator voltage R: Armature resistance It had to be fully insulated, and could not be used for busbar inspection.Also, even if there was a disconnector for busbar inspection, it did not have the closing capacity, so it could not be used for electric brakes. Furthermore, as an excitation device for the electric brake, a rotary exciter directly connected to a generator requires a separate excitation device, and a self-excited thyristor type requires a separate excitation device. The present invention devises the ignition control circuit of the excitation device by grounding the neutral point of the disconnector that has the closing capacity due to the residual voltage of the generator, and connecting the excitation transformer to the main transformer side of the generator and disconnector. This is an attempt to eliminate the above-mentioned conventional drawbacks.

An embodiment of the present invention will be described below with reference to the drawings. In Fig. 2, 16 is a switching circuit that switches between normal AVR operation and excitation during electric braking, 17 is a firing angle control circuit used during electric braking, 18 is an electromagnetic winding, and 20 is a brake whose neutral point is grounded. It is a disconnector for The excitation transformer 11 is connected between the edge breaker 5 and the main transformer 6, so that even when the edge breaker 5 is open, output is supplied to the rectifier circuit 10. . Furthermore, the disconnector 14 and thyristor bridge 15 shown in FIG. 1 are omitted, simplifying the device configuration.

Next, the operation will be explained. In response to the stop command, the field breaker 5 and then the field breaker 12 are opened, and the field energy of the generator 1 is discharged through the field discharge resistor 13, and the output voltage of the generator 1 becomes only the residual voltage. The disconnector 20 is then turned on. Switching circuit 16
is switched from the AVR 8 side to the firing angle control circuit 17 side. When the rotational speed of the generator 1 drops to about 50%, the field magnet and disconnector 12 are turned on again and the electric brake is applied. The firing angle control circuit 17 controls the firing of the rectifier circuit 10 so that the output rectified current of the rectifier circuit 10 gradually decreases to zero.

Since the brake disconnector 20 has its neutral point grounded, it can be used when inspecting not only the electric brake but also the generator 1 and its main circuit, drying the generator coil, and the characteristics of the generator. It can also be used when conducting tests, etc.

As described above, according to the present invention, a firing angle control circuit is provided which is connected to the firing angle during electric braking, and the connection point on the primary side of the excitation transformer is devised, and the Since the electrical point is grounded, the device can be simplified, and the brake disconnector can also be used for applications other than electric brakes.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional electric brake device for a generator, and FIG. 2 is a circuit diagram showing an electric brake device for a generator according to the present invention. 1 is the generator, 5 is the breaker, 6 is the main transformer, 8
9 is an automatic voltage regulator, 9 is an ignition circuit, 10 is a rectifier circuit, 11 is an excitation transformer, 17 is an ignition angle control circuit, and 20 is a braking disconnector. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1 The main transformer connected to the generator via the disconnector, the excitation transformer that supplies power to the rectifier circuit for the field winding of the generator, and the ignition control of the rectifier circuit are automatically controlled. An electric brake device for a generator includes an ignition circuit that performs ignition based on an output signal from a voltage regulator, and a braking disconnector that applies electrical braking to the generator when the generator is stopped. A firing angle control circuit is provided which is connected to the firing circuit during braking and controls the firing angle of the rectifier circuit so that the field current of the generator is reduced; An electric brake device for a generator, characterized in that a side of the brake disconnector is connected between the main transformer and the shield disconnector, and a neutral point of the brake disconnector is grounded.