Two-shaft gas turbine power generation equipment

1. A two-shaft gas turbine power generation equipment comprising:

a compressor having a compressor rotor and configured to compress air to produce compressed air by rotation of the compressor rotor;

a combustor configured to burn a fuel in the compressed air to produce a combustion gas;

a high-pressure turbine having a high-pressure turbine rotor that is mechanically coupled with the compressor rotor and in which the high-pressure turbine rotor is rotated by the combustion gas;

a low-pressure turbine having a low-pressure turbine rotor that is not coupled to the high-pressure turbine rotor and in which the low-pressure turbine rotor is rotated by the combustion gas exhausted from the high-pressure turbine;

a power generator configured to generate power in rotation of the low-pressure turbine rotor and electrically connected to a power system to which alternating current power flows;

an induction motor being electrically connected to the power system in parallel with the power generator and configured to receive/transmit the power from/to the power system;

a frequency converter being provided between the induction motor and the power system in an electrical connection relationship, configured to control reception/transmission of the power between the induction motor and the power system, convert a frequency of the power from the induction motor into a frequency of the power system when the power from the induction motor is transmitted toward the power system, and convert the frequency of the power from the power system to the frequency of the power from the induction motor when the power from the vicinity of the power system is received and supplied to the induction motor; and

a speed reducer configured to make a rotational speed of a motor rotor of the induction motor slower than a rotation speed of the compressor rotor,

wherein the speed reducer has:

a compressor-side shaft that is mechanically coupled with the compressor rotor;

a motor-side shaft that is disposed parallel to the compressor-side shaft at an interval to be non-movable relative to the motor rotor, and is mechanically coupled with the motor rotor;

a first compressor-side helical gear that is mounted on the compressor-side shaft and is rotated integrally with the compressor-side shaft;

a first motor-side helical gear that is mounted on the motor-side shaft, is rotated integrally with the motor-side shaft, and meshes with the first compressor-side helical gear;

a second compressor-side helical gear that is mounted on the compressor-side shaft and is rotated integrally with the compressor-side shaft; and

a second motor-side helical gear that is mounted on the motor-side shaft, is rotated integrally with the motor-side shaft, and meshes with the second compressor-side helical gear, and

wherein the number of teeth of the second compressor-side helical gear is different from the number of teeth of the first compressor-side helical gear.

2. The two-shaft gas turbine power generation equipment according to claim 1 , wherein the induction motor is configured such that output thereof is monotonously increased or reduced with respect to a change in rotational speed thereof in a rotational speed range including a rotational speed obtained by multiplying a rated rotational speed predetermined for the high-pressure turbine rotor by a reduction ratio based on the speed reducer.

3. The two-shaft gas turbine power generation equipment according to claim 2 , wherein the rated rotational speed of the high-pressure turbine rotor ranges from 4000 rpm to 7000 rpm.

4. The two-shaft gas turbine power generation equipment according to claim 1 , wherein a reduction ratio of the speed reducer ranges from 9/10 to 1/5.

5. The two-shaft gas turbine power generation equipment according to claim 1 , wherein a direction of a twist of each tooth trace of the second compressor-side helical gear is opposite to that of a twist of each tooth trace of the first compressor-side helical gear.

6. The two-shaft gas turbine power generation equipment according to claim 1 , wherein the speed reducer has one of a compressor-side coupling tool that mounts the first and second compressor-side helical gears to be non-rotatable relative to the compressor-side shaft and to be movable relative to the compressor-side shaft in a thrust direction in which the compressor-side shaft extends, and a motor-side coupling tool that mounts the first and second motor-side helical gears to be non-rotatable relative to the motor-side shaft and to be movable relative to the compressor-side shaft in the thrust direction in which the motor-side shaft extends.

7. The two-shaft gas turbine power generation equipment according to claim 1 , further comprising a coupling that mechanically couples the compressor rotor and the compressor-side shaft,

wherein the coupling has a displacement absorber configured to absorb displacement of the compressor rotor in at least one of a thrust direction of the compressor rotor and a radial direction of the compressor rotor.

8. The two-shaft gas turbine power generation equipment according to claim 7 , wherein the coupling is a diaphragm coupling.