JPH0429600A - Starter device for gas turbine generator - Google Patents

Abstract

PURPOSE:To smoothly perform a changeover of power by detecting effective power, supplied to a generator, and effective power, generated from the generator, through a power relay and cutting off the effective power, supplied to the generator from a variable AC/DC converter, by a change of this detection. CONSTITUTION:A gas turbine 11 is rotated to a predetermined speed by an electric motor, a burner 14 is operated in combustion in a condition that an amount of air of minimum requirement limit or more can be ensured, combustion gas of the combustor is supplied to the gas turbine 11 and the gas turbine 11 is rotated by the combustion gas. When this gas turbine 11 is rotated further to a high speed where its self operation is made possible, the electric motor is operated to serve as a generator 13 by receiving power from the gas turbine 11, and power of the generator is supplied to a side of a bus line 15. A breaker 20 of an AC/DC converter 17 is cut off by detecting a change of direction of this power by a power relay 34,. Thereafter, the power is supplied to the bus line 15 from the generator 13 by closing a power circuit breaker 23.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a starting device for a gas turbine generator.

(Prior Art) In general, a gas turbine generator 10 has a gas turbine 11, an air compressor 12, and a generator 13 mechanically connected to each other as shown in FIG. The generator 13 rotates the generator 13 to supply electric power.

Compressed air compressed by the air compressor 12 and fuel supplied from a combustion supply device (not shown) are combusted in the combustor 14, and high temperature combustion gas obtained by this combustion is sent to the gas turbine 11.

Then, the high-temperature combustion gas is engraved within the gas turbine 11 to drive rotation.

In this gas turbine generator 10, in order to generate high-temperature combustion gas in the combustor 14, the air compressor 12 must feed the minimum necessary amount of air. Therefore, when starting up the gas turbine 11, the air compressor 1
3 must be rotated at a predetermined speed.

On the other hand, since the gas turbine 11 has a reactionary torque in the low speed range at startup, the gas turbine 11 cannot rotate independently only by engraving high-temperature combustion gas, and it is necessary to rotate this by some method. .

Therefore, to start this type of gas turbine generator, a method is usually adopted in which the generator 13 is used as an electric motor to rotate the gas turbine 11 and the air compressor 13. Therefore, an AC/DC converter 17 is connected to the bus bar 15 of the gas turbine generator 10 via a transformer 16 . This AC/DC converter 17 is controlled by control rectifying elements 18a, 18b such as SCR.
It is composed of a reactor 19 and the like, and converts commercial AC power into variable frequency power.

The power of this AC/DC converter 17 is sent to the generator 13 via the circuit breaker 20, and the generator 13 is driven as an electric motor.

This generator 13 includes an armature winding 13a and a field winding 13b.
An AC/DC converter 17 is connected to the armature winding 13a, and an excitation device 22 having a variable DC power supply 21 is connected to the field winding 13b. This field winding 13b
is supplied with a control field current from the excitation device 22, and when the armature winding 13a receives variable frequency power from the AC/DC converter 17, the generator 13 operates as an electric motor from low speed to low speed according to the frequency and power. It is rotated at high speed, causing the gas turbine 11 and air compressor 12 to rotate.

In this way, the gas turbine 11 and the air compressor 1
2 is rotated by an electric motor until it reaches a predetermined rotational speed N1, and when the combustor 14 receives a predetermined compressed air from the air compressor 12, the combustor 14 is ignited.

When the rotational speed of the gas turbine 11 increases to 67% (N2) of the rated rotational speed, the gas turbine 11 begins to operate independently using combustion gas. As a result, the power supplied from the variable AC/DC converter 17 to the generator 13 is no longer needed.

The regeneration timing of the generator 13 is determined by the rotational speed of the gas turbine 11, so this rotational speed is detected by a speed detector (not shown), and when the rotational speed of the gas turbine 11 reaches this rotational speed, the circuit breaker is activated. Open 20 and AC/DC converter 1
Cut off the power supply from 7.

This rotational speed is normally possible at 67% of the rated rotational speed, but for safe operation, it is normally carried out at 70% of the rated rotational speed with a little margin.

These operating characteristics will be explained with reference to FIG.

That is, assuming that the horizontal axis is the rotational speed N of the gas turbine, etc., and the vertical axis is the torque T, the gas turbine 11 is gradually accelerated by the generator 13, and the reaction torque τg also gradually increases.

When the combustor 14 is ignited at the speed N1 and the gas turbine 11 receives the combustion gas, the reaction torque τg also gradually decreases. When the gas turbine 11 reaches the speed N2, self-sustaining operation becomes possible.

On the other hand, the output torque τm of the generator 13 is
1 is accelerated at a constant acceleration ratio, the reaction torque τg
and have a certain torque difference. This torque difference becomes acceleration energy Eg that rotates the gas turbine 11. This output torque τm is the rotational speed N at which self-sustaining operation is possible.
2, it decreases to mo, and becomes zero at a rotational speed N3 that slightly exceeds this rotational speed N2. At this rotational speed N3, the circuit breaker 20 is released and the power supplied from the AC/DC converter 17 to the generator 13 is cut off.

(Problem to be solved by the invention) As described above, the opening operation of the circuit breaker that cuts off the power supply to the generator is performed by detecting the rotational speed at which the gas turbine can operate independently using a detector, and then It is cut off when the speed is reached. However, since the rotational speed and reaction torque of a gas turbine are affected by the temperature of the combustion gas obtained from the combustion gas, the rotational speed and reaction torque usually fluctuate, and the rotational speed at which the gas turbine can operate independently also fluctuates. do. Therefore, in the case where the circuit breaker is opened according to the set rotation speed, the operation is performed while the gas turbine still has a reaction torque τg, and in the worst case, the rotation of the gas turbine may be stopped. be. In order to avoid this, the circuit breaker is opened at a rotational speed slightly higher than that at which self-sustaining operation is possible, leading to problems such as the power switching operation not being performed properly.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a starting device for a gas turbine generator that accurately captures the rotational speed at which the gas turbine can operate independently and properly opens and closes the AC/DC converter. .

[Structure of the invention]

(Means for Solving the Problems) The present invention is a starting device for a gas turbine generator that drives a gas turbine by burning compressed air and fuel from an air compressor connected to a gas turbine. an AC/DC converter that supplies current to the armature winding of the generator to drive the gas turbine and increase the rotation speed to a predetermined speed;
A power relay detects the direction of active power in the armature winding of the generator, and when the power relay detects a change in the polarity of the active power, current is supplied from the AC/DC converter to the armature winding of the generator. It is equipped with a circuit breaker that disconnects the

(Function) When the gas turbine starts up, it receives electric power from the generator or AC/DC converter to drive the gas turbine as an electric motor. This gas turbine is brought to a predetermined speed by an electric motor and burned in a combustor while ensuring a minimum amount of air.
The combustion gas is supplied to the gas turbine, and the gas turbine is rotated by the combustion gas. When this gas turbine further increases in speed and reaches a speed at which it can become self-sustaining, the electric motor receives power from the gas turbine and is operated as a generator, and the electric power is supplied to the bus bar side. This change in direction of power is detected by a power relay, and the circuit breaker of the AC/DC converter is shut off. Thereafter, the power circuit breaker is closed and power is supplied from the generator to the busbar.

(Example) Hereinafter, an example of the starting device for a gas turbine generator of the present invention will be described with reference to FIG.

Starting device 30 for the gas turbine generator in FIG.
Basically, it is almost the same as the conventional gas turbine generator starting device 10 explained in FIG. 2, so the same parts are given the same reference numerals and detailed explanation will be omitted.

A power relay 34 is connected between the circuit breaker 20 and the armature winding of the generator 13 via a voltage transformer 32 and a current transformer 33, and the direction of active power flowing to the armature winding is determined by the power relay. Detected by 34.

This power relay 34 detects the voltage generated in the armature winding with a voltage transformer 32, detects the current flowing in the armature winding with a current transformer 33, and generates electricity from the AC/DC converter 17 based on both values. It is detected whether the active power being supplied to the generator 13 is the active power flowing from the generator 13 to the bus bar side, and when the active power flowing from the generator 13 to the bus bar side is detected, the power relay 34 circuit breaker 2 by the signal of
0 will be released.

In this gas turbine generator starting device 30, the generator 13 receives variable power from the AC/DC converter 17 and is operated as an electric motor, and the gas turbine 11 and air compressor 12
is rotated. The rotational speed of this gas turbine 11 is N1
When this happens, the combustor]4 is combusted and the rotational speed N2 is accelerated to allow self-sustaining operation.

At this speed N2, the gas turbine 11 moves to the combustor 14.
Since the combustion gas enables autonomous operation, the generator 13
There is no need for mechanical power to be applied to the gas turbine 11 from the above. Therefore, the power supplied from the AC/DC converter 17 to the generator 13 becomes zero.

When the gas turbine 11 is further accelerated and its speed approaches N3, the mechanical power of the gas turbine 11 is applied to the generator 13, and active power is supplied from the generator 13 to the busbar side. This power is determined by the speed of the gas turbine 11.

These changes in active power, that is, the supply of active power from the AC/DC converter 17 to the generator 13 and the supply of active power from the generator 13 to the busbar side, are detected by the power relay 34, and the power is zero, that is, self-sustaining operation is possible. When the rotation speed reaches N2, the circuit breaker 2° is released. After the circuit breaker 2o is released, the power circuit breaker 2o is adjusted while adjusting the voltage, phase, etc.
3 is closed, and power is supplied from the generator 13 to the bus bar 15.

Therefore, if this power relay 34 is employed, the state in which the reaction torque of the gas turbine 11 becomes zero can be accurately detected, and the circuit breaker 20 can be opened and closed in this state, so that the AC/DC converter 17 can be switched smoothly. be able to.

The gas turbine generator starting device of the present invention is particularly effective for starting a combined cycle that is composed of a plurality of gas turbine generators and each has a different self-sustaining speed. In this case, one power relay may be switched and used for each gas turbine generator.

〔Effect of the invention〕

The starting device for a gas turbine generator of the present invention uses a generator as an electric motor to rotationally drive a gas turbine, and when the gas turbine reaches a predetermined rotational speed, the electric motor becomes a generator, and the active power is supplied to the generator. and the active power generated from the generator are detected by a power relay, and the change in this detection cuts off the active power supplied to the generator from the variable AC/DC converter, ensuring the self-sustaining speed of the gas turbine. This allows for smooth power switching.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a starting device for a gas turbine generator according to the present invention, Fig. 2 is a block diagram of a starting device for a conventional gas turbine generator, and Fig. 3 is a block diagram of a starting device for a gas turbine generator commonly used. FIG. 3 is an explanatory diagram showing startup characteristics. 10.30... Gas turbine generator starting device, 11
...Gas turbine, 12...Air compressor, 13...
- Generator, 14... Combustor, 15... Bus bar, 16.
...Transformer, 17...AC/DC converter, 18a, 18b.
...Control rectifier, 19...Reactor, 20...
Circuit breaker, 21... Variable power supply, 22... Excitation device, 2
3... Power circuit breaker, 32... Voltage transformer, 33...
-Current transformer, 34...power relay. Applicant's agent Mr. Sato

Claims (1)

[Claims] A starting device for a gas turbine generator that drives the gas turbine by burning compressed air and fuel from an air compressor connected to the gas turbine, and supplies current to the armature winding of the generator during startup. an AC/DC converter that drives the gas turbine and increases it to a predetermined rotational speed; a power relay that detects the direction of active power in the armature winding of the generator; and this power relay that detects changes in the polarity of the active power. A starting device for a gas turbine generator, comprising: a circuit breaker that disconnects current supply from the AC/DC converter to the armature winding of the generator when detected.