JPH0457851B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for starting a gas turbine.

[Conventional technology]

Figure 3 shows, for example, ASEA JOURNAL 1976
FIG. 3 is a circuit diagram showing a conventional starting device shown in VOLUME49 NUMBER3. In the figure, 1 is a thyristor type converter, 2 is a thyristor type separately excited inverter, and 3 is a DC reactor, and these constitute a variable voltage variable frequency power converter P. 4 is a commercial power supply, 5 is an input transformer for matching, and 6 is an output transformer for matching. The output transformer 6 is connected to the power converter P and the gas turbine generator 1 via changeover switches 7 and 8.
It is inserted between the second armature winding. 9 is a bypass switch, which is a changeover switch 7;
It is connected in parallel to a series circuit consisting of an output transformer 6 and a changeover switch 8. The generator 12 has a rotor position detector and is connected to a commercial power source 11 via a power switch 10. Reference numeral 13 denotes a field winding of the generator 12, to which field power is supplied from a field power supply 14. Reference numeral 15 denotes a gas turbine, which is connected to the generator 12 .

Next, the operation of this device will be explained.

Since the gas turbine 15 does not have self-starting capability until ignited, the generator 12 is started and operated as a thyristor motor in combination with the power converter P. During this start-up operation, in order to prevent the iron core of the output transformer 6 from being magnetically saturated by the exciting current in the low frequency region, the switch 9 is turned on and the changeover switches 7 and 8 are turned on.
is turned off and the output transformer 6 is bypassed, and when the generator 12 reaches a certain speed, the switch 9 is turned off and the changeover switches 7 and 8 are turned on and the generator is operated. The generator 12 has an ignition speed N1 of the gas turbine 15 (approximately 1/2 speed or less of the generator rated rotation speed)
The gas turbine 15 receives variable voltage and variable frequency power from the power converter P, and operates the electric motor at a predetermined voltage/frequency ratio with the rated field until the gas turbine 15 speeds up. After ignition, the gas turbine 15 speeds up by itself. do. When the speed of the gas turbine 15 increases to the rated rotational speed No. of the generator 12, the frequency, phase, and voltage of the generator 12 and the commercial power source 11 are matched, and then the power switch 10 is turned on.
is turned on, and the startup of the gas turbine generator 12 is completed.

[Problem that the invention seeks to solve]

By the way, in this conventional device, if the rated voltage of the power converter is matched to the rated voltage of the generator, an expensive power converter is required, so the rating of the power converter is lowered and the voltage is increased by a transformer. However, since the transformer is expensive, the cost of the equipment is still high, and as mentioned above, a bypass circuit is installed to prevent the iron core of the output transformer 6 from becoming magnetically saturated at low frequencies. There were problems such as the need for a switch for switching bypass.

[Means to solve the problem]

In order to achieve the above object, the present invention operates the electric motor by directly supplying power to the generator from a power converter by weakening the field of the generator, and when the generator speed reaches the ignition speed of the gas turbine, the generator voltage The power converter is started so that the value is almost equal to the rated value of the power converter.

[Effect]

In this invention, the generator is field-weakened and the motor is operated, and when the generator speed reaches the ignition speed of the gas turbine, the generator voltage is started to be almost equal to the rated value of the power converter, so matching is possible. It is possible to omit an output transformer for the output transformer, a switch circuit for bypassing the output transformer, a switch for switching the bypass, etc.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which the output of an inverter 2 is connected to the rotor of a generator 12 via a changeover switch 7, and the circuit diagram in FIG. 6. The difference is that the bypass switch 9 and the changeover switch 8 are omitted.

In this configuration, the field current of the generator 12 is lowered below the rated value so that the generator voltage when the rotational speed of the generator 12 reaches the ignition speed N1 of the gas turbine 15 becomes the rated voltage E2 of the inverter 2. The field is weakened to lower the voltage/frequency ratio below the predetermined voltage/frequency ratio described above, and the generator 12 is started as a thyristor motor. Generally, the generator 12
Since the rated capacity of is about 10 times the capacity required at startup, there is no problem even if the field current is significantly reduced.As shown in Figure 2, the above when starting with the field current at the rated value When the generator voltage at the ignition speed N1 is E1, the voltage E1 can be selected so that E1>E2. In FIG. 2, E is the rated voltage of the generator 12.

When the gas turbine 15 reaches the ignition speed N1 and ignites, the operation of the power converter P is stopped and the changeover switch 7 is opened, but during this time, the field current must be adjusted so that the voltage of the generator does not rise. is desirable. When the speed of the gas turbine 15 increases and reaches the rated speed No., the frequency, phase, and
The voltage is matched with that of the commercial power supply 11 and the power switch 10 is turned on to complete the startup.

In this embodiment, the field of the generator 12 is lowered to start the motor so that the generator voltage at the gas turbine ignition speed matches the output voltage of the inverter 2, so the electric power converter P is the most economical. You can use the rated one.

〔Effect of the invention〕

As explained above, this invention matches the voltages between the generator side and the power converter side by weakening the field of the generator, so the conventional matching output transformer can be omitted. Since a switch circuit for bypassing the transformer is also not required, the cost of the device can be reduced and the space required can be reduced compared to the conventional method.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of this invention, Fig. 2 is a circuit diagram showing an embodiment of the present invention;
The figure is a voltage-speed characteristic diagram for explaining the above embodiment, and FIG. 3 is a circuit diagram showing a conventional thyristor starting device. In the figure, 1...converter, 2...inverter, 3...DC reactor, 7...changeover switch, 1
0...power switch, 12...generator, 15...gas turbine. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. When a gas turbine generator is started, variable voltage variable frequency power is supplied from a power converter to the armature of the generator, and the generator is used as an electric motor to accelerate the gas turbine to its ignition speed. In the starting method, during the starting, power is supplied directly from the power converter by weakening the field of the generator, and at the ignition speed, the voltage of the generator is approximately equal to the rated output voltage value of the power converter. A method for starting a gas turbine, characterized by increasing the speed so that