# US 9,520,757 B2 · Dual-shaft gas turbine power generation system, and control device and control method for gas turbine system

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- Number: US 9,520,757 B2
- Document ID: US9520757B2
- Status: Granted
- Kind: B2
- Application number: 14/412,488
- Filed: 2012-08-03
- Published: 2015-06-18
- Granted: 2016-12-13
- Earliest claimed: 2012-08-03
- Assignees: Hitachi, Ltd.
- Applicants: Noriaki Hino; Naohiro Kusumi; Kazuo Takahashi; Tomomichi Ito
- Inventors: Noriaki Hino; Naohiro Kusumi; Kazuo Takahashi; Tomomichi Ito
- Web page: https://patentgrep.com/patent/US9520757B2

## CPC

- F01D 15/10: Adaptations for driving, or combinations with, electric generators
- F02C 3/04: having a turbine driving a compressor (power transmission arrangements F02C7/36; control of working fluid flow F02C9/16)
- F02C 3/10: with another turbine driving an output shaft but not driving the compressor
- F02C 7/057: Control or regulation (conjointly with fuel supply control F02C9/50, with nozzle area control F02K1/16)
- F02C 7/36: Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user ({F02C3/107 - F02C3/13 and} F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H)
- F02C 9/00: Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants (controlling air intakes F02C7/057; controlling turbines F01D; controlling compressors F04D27/00; controlling in general G05)
- F02C 9/20: by throttling; by adjusting vanes
- F02C 9/54: by throttling the working fluid, by adjusting vanes
- H02J 3/34: Arrangements for transfer of electric power between networks of substantially different frequency
- H02K 7/1823: {structurally associated with turbines or similar engines}
- H02P 3/02: Details {of stopping control}
- F05D 2220/7642: of the synchronous type
- F05D 2270/053: Explicitly mentioned power
- F05D 2270/335: Output power or torque
- Y02E 60/32: Hydrogen storage
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

The dual-shaft gas turbine power generation system includes: a high-pressure gas turbine; a first rotating shaft connecting a compressor and the high-pressure gas turbine; an electric motor connected to the first rotating shaft; a governor which adjusts the amount of air taken into the compressor; a low-pressure gas turbine; a second rotating shaft connected to the low-pressure gas turbine; a synchronous power generator connected to the second rotating shaft; a frequency converter which converts the frequency of power transmitted between the synchronous power generator and the electric motor; and a control device which controls a frequency converter control device for controlling the frequency converter, and the governor, on the basis of a power output command value indicating the power to be outputted to an external grid.

## Claims

### Claim 1

A dual-shaft gas turbine power generation system comprising:
a compressor which pressurizes air and generates compressed air;
a combustor which mixes and combusts the compressed air and a fuel;
a high-pressure gas turbine which is driven by a combustion gas obtained in the combustor;
a first rotating shaft which connects the compressor and the high-pressure gas turbine;
an electric motor connected to the first rotating shaft;
a governor which adjusts an amount of air taken into the compressor thereby controlling an output of the high-pressure gas turbine;
a low-pressure gas turbine driven by the combustion gas after driving the high-pressure gas turbine;
a second rotating shaft connected to the low-pressure gas turbine;
a synchronous power generator connected to the second rotating shaft generating power of an external grid frequency and connected to an external grid;
a frequency converter which is disposed on a power transmission path for transmitting power between the synchronous power generator and the electric motor, and which converts a frequency of power to be transmitted between the synchronous power generator and the electric motor; and
a control device which controls a frequency converter control device for controlling the frequency converter and the governor, on the basis of a power output command value indicating power to be outputted to the external grid, and thus controls a total output of the gas turbines and the electric motor,
wherein a capacity of the electric motor is less than a capacity of the synchronous power generator.

### Claim 2 (depends on 1)

The dual-shaft gas turbine power generation system according to claim 1, further comprising an outside air state measuring device which measures a state of air taken into the compressor, wherein
the control device controls the frequency converter control device controlling the frequency converter, and the governor, on the basis of the power output command value and a result of measurement by the outside air state measuring device, and thus controls the total output of the gas turbine and the electric motor.

### Claim 3 (depends on 1)

The dual-shaft gas turbine power generation system according to claim 1, wherein
the electric motor comprises:
a stator including a stator iron core and a stator winding wound on the stator iron core; and
a rotor which includes a rotor iron core with a plurality of magnet insertion holes formed therein and a plurality of permanent magnets for forming magnetic poles, held inside the magnet insertion holes, and which is provided rotatably with respect to the stator.

### Claim 4 (depends on 1)

The dual-shaft gas turbine power generation system according to claim 1, wherein
the electric motor comprises:
a stator including a stator iron core and a stator winding wound on the stator iron core; and
a rotor provided with a rotor iron core with a plurality of conductive bar insertion holes formed therein and conductive bars inserted inside the conductive bar insertion holes and electrically connected at both ends of an axis, each via an end ring.

### Claim 5 (depends on 1)

The dual-shaft gas turbine power generation system according to claim 1, wherein
the power converter includes converters connected to both the side of the synchronous power generator and the side of the electric motor and having a function of converting power from AC to DC and a function of converting power from DC to AC.

### Claim 6 (depends on 1)

The dual-shaft gas turbine power generation system according to claim 1, wherein
the power converter includes a converter connected to one of the side of the synchronous power generator and the side of the electric motor and having a function of converting power from AC to DC and a function of converting power from DC to AC, and a rectifier connected to the other side and converting power from AC to DC.

### Claim 7 (depends on 1)

The dual-shaft gas turbine power generation system according to claim 1, wherein
the first rotating shaft connected to the compressor, and the electric motor are mechanically connected without having a gear in-between.

### Claim 8 (depends on 1)

The dual-shaft gas turbine power generation system according to claim 1, wherein
the second rotating shaft connected to the low-pressure turbine, and the synchronous power generator are mechanically connected without having a gear in-between.

### Claim 9

A dual-shaft gas turbine power generation system comprising:
a compressor which pressurizes air and generates compressed air;
a combustor which mixes and combusts the compressed air and a fuel;
a high-pressure gas turbine which is driven by a combustion gas obtained in the combustor;
a first rotating shaft which connects the compressor and the high-pressure gas turbine;
an electric motor connected to the first rotating shaft;
a governor which adjusts an amount of air taken into the compressor thereby controlling an output of the high-pressure gas turbine;
a low-pressure gas turbine driven by the combustion gas after driving the high-pressure gas turbine;
a second rotating shaft connected to the low-pressure gas turbine;
a synchronous power generator connected to the second rotating shaft generating power of an external grid frequency and connected to an external grid;
a frequency converter which is disposed on a power transmission path for transmitting power between the synchronous power generator and the electric motor, and which converts a frequency of power to be transmitted between the synchronous power generator and the electric motor;
a control device which controls a frequency converter control device for controlling the frequency converter and the governor, on the basis of a power output command value indicating power to be outputted to the external grid, and thus controls a total output of the gas turbines and the electric motor;
a transformer which converts a voltage outputted from the synchronous power generator to the external grid;
a circuit breaker provided in such a way as to be able to cut off power transmitted to the external grid via the transformer;
a voltage measuring device which measures a voltage on the side of the external grid, in the circuit breaker; and
an abnormality control device which detects a voltage abnormality generated in the external grid on the basis of a result of comparison between a preset reference value for voltage abnormality in the external grid and a result of measurement by the voltage measuring device, and which controls the frequency converter control device such that a load by the electric motor as viewed from the high-pressure turbine via the first rotating shaft decreases relatively, if a voltage abnormality is detected.

### Claim 10 (depends on 9)

The dual-shaft gas turbine power generation system according to claim 9, further comprising a resistance circuit connected in parallel between the synchronous power generator and the transformer and provided with a switching device for switching between connection and cut-off between the synchronous power generator and the transformer, wherein
the abnormality control device switches the switching device of the resistance circuit from cut-off to connection if a voltage abnormality generated in the external grid is detected.

### Claim 11

A dual-shaft gas turbine power generation system comprising:
a compressor which pressurizes air and generates compressed air;
a combustor which mixes and combusts the compressed air and a fuel;
a high-pressure gas turbine which is driven by a combustion gas obtained in the combustor;
a first rotating shaft which connects the compressor and the high-pressure gas turbine;
an electric motor connected to the first rotating shaft;
a governor which adjusts an amount of air taken into the compressor thereby controlling an output of the high-pressure gas turbine;
a low-pressure gas turbine driven by the combustion gas after driving the high-pressure gas turbine;
a second rotating shaft connected to the low-pressure gas turbine;
a synchronous power generator connected to the second rotating shaft generating power of an external grid frequency and connected to an external grid;
a frequency converter which is disposed on a power transmission bath for transmitting power between the synchronous power generator and the electric motor, and which converts a frequency of power to be transmitted between the synchronous power generator and the electric motor;
a control device which controls a frequency converter control device for controlling the frequency converter and the governor, on the basis of a power output command value indicating power to be outputted to the external grid, and thus controls a total output of the gas turbines and the electric motor;
a transformer which converts a voltage outputted from the synchronous power generator to the external grid;
a circuit breaker provided in such a way as to be able to cut off power transmitted to the external grid via the transformer;
a voltage measuring device which measures a voltage on the side of the external grid, in the circuit breaker;
a resistance circuit connected in parallel between the synchronous power generator and the transformer and provided with a switching device for switching between connection and cut-off between the synchronous power generator and the transformer; and
an abnormality control device which detects a voltage abnormality generated in the external grid on the basis of a result of comparison between a preset reference value for voltage abnormality in the external grid and a result of measurement by the voltage measuring device, and which switches the switching device of the resistance circuit from cut-off to connection if a voltage abnormality is detected.

### Claim 12

A control method for a gas turbine system including a compressor which pressurizes air and generates compressed air, a combustor which mixes and combusts the compressed air and a fuel, a high-pressure gas turbine which is driven by a combustion gas obtained in the combustor, a first rotating shaft which connects the compressor and the high-pressure gas turbine, an electric motor connected to the first rotating shaft, a governor which adjusts an amount of air taken into the compressor and thus controls an output of the high-pressure gas turbine, a low-pressure gas turbine driven by the combustion gas after driving the high-pressure gas turbine, a second rotating shaft connected to the low-pressure gas turbine, a synchronous power generator connected to the second rotating shaft, and a frequency converter which is provided on a power transmission path for transmitting power between the synchronous power generator and the electric motor,
the method comprising generating power with the synchronous power generator at an external grid frequency and outputting the generated power to the external grid, converting a frequency of the power transmitted between the synchronous power generator and the electric motor, and controlling the frequency converter and the governor, on the basis of a power output command value indicating power to be outputted to the external grid, thus controlling a total output of the gas turbines and the electric motor,
wherein the gas turbine system includes a transformer which converts a voltage outputted from the synchronous power generator to the external grid, and a circuit breaker provided in such a way as to be able to cut off power transmitted to the external grid via the transformer, and
wherein the method further comprises:
a procedure of measuring a voltage on the side of the external grid, in the circuit breaker;
a procedure of detecting a voltage abnormality generated in the external grid on the basis of a result of comparison between a preset reference value for voltage abnormality in the external grid and a result of measurement of the voltage; and
further controlling the frequency converter control device in such a way that a load by the electric motor as viewed from the high-pressure turbine via the first rotating shaft decreases relatively, if a voltage abnormality is detected.

### Claim 13

A control device for a gas turbine system including a compressor which pressurizes air and generates compressed air, a combustor which mixes and combusts the compressed air and a fuel, a high-pressure gas turbine which is driven by a combustion gas obtained in the combustor, a first rotating shaft which connects the compressor and the high-pressure gas turbine, an electric motor connected to the first rotating shaft, a governor which adjusts an amount of air taken into the compressor and thus controls an output of the high-pressure gas turbine, a low-pressure gas turbine driven by the combustion gas after driving the high-pressure gas turbine, a second rotating shaft connected to the low-pressure gas turbine, a synchronous power generator connected to the second rotating shaft, and a frequency converter which is provided on a power transmission path for transmitting power between the synchronous power generator and the electric motor, wherein the synchronous power generator generates power at an external grid frequency and outputs the generated power to the external grid, the frequency converter converts a frequency of the power transmitted between the synchronous power generator and the electric motor,
wherein the frequency converter and the governor, are controlled on the basis of a power output command value indicating power to be outputted to the external grid, to control a total output of the gas turbines and the electric motor,
wherein the gas turbine system further includes a transformer which converts a voltage outputted from the synchronous power generator to the external grid, a circuit breaker provided in such a way as to be able to cut off power transmitted to the external grid via the transformer, and a voltage measuring device which measures a voltage on the side of the external grid, in the circuit breaker, and
wherein a voltage abnormality generated in the external grid is detected on the basis of a result of comparison between a preset reference value for voltage abnormality in the external grid and a result of measurement by the voltage measuring device, and if a voltage abnormality is detected, the frequency converter control device is controlled in such a way that a load by the electric motor as viewed from the high-pressure turbine via the first rotating shaft decreases relatively.

### Claim 14

A dual-shaft gas turbine power generation system comprising:
a compressor which pressurizes air and generates compressed air;
a combustor which mixes and combusts the compressed air and a fuel;
a high-pressure gas turbine which is driven by a combustion gas obtained in the combustor;
a first rotating shaft which connects the compressor and the high-pressure gas turbine;
an electric motor connected to the first rotating shaft;
a governor which adjusts an amount of air taken into the compressor thereby controlling an output of the high-pressure gas turbine;
a low-pressure gas turbine driven by the combustion gas after driving the high-pressure gas turbine;
a second rotating shaft connected to the low-pressure gas turbine;
a synchronous power generator connected to the second rotating shaft generating power of an external grid frequency and connected to an external grid;
a frequency converter which is disposed on a power transmission path for transmitting power between the synchronous power generator and the electric motor, and which converts a frequency of power to be transmitted between the synchronous power generator and the electric motor;
a control device which controls a frequency converter control device for controlling the frequency converter and the governor, on the basis of a power output command value indicating power to be outputted to the external grid, and thus controls a total output of the gas turbines and the electric motor; and
a transformer which adjusts a voltage of power transmitted between the synchronous power generator and the frequency converter.