Dual-shaft gas turbine power generation system, and control device and control method for gas turbine system

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.

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.

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.

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.

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.