Dual-motor variable frequency driving system for multi-shaft gas turbine

Abstract

The invention discloses a dual-motor variable frequency driving system for a multi-shaft gas turbine, and belongs to the field of multi-shaft gas turbine driving. The system adopts a master-slave control strategy and comprises a driving motor, a driven motor, a master frequency converter, a slave frequency converter, a gas turbine auxiliary gear box and a multi-shaft gas turbine, the main frequency converter controls the main motor to operate, the auxiliary frequency converter controls the auxiliary motor to synchronously operate along with the main motor according to current signals of the main motor, the main motor and the auxiliary motor are used for simultaneously driving the multi-shaft gas turbine to operate through the gas turbine auxiliary gearbox, and synchronous work of the two motors is effectively achieved. The problems of asynchronous rotating speed and unbalanced load in a traditional multi-motor driving system are avoided; according to the system, reliable and stable driving of the multi-shaft gas turbine is achieved, the service life of equipment can be remarkably prolonged, and the energy utilization efficiency of the system can be remarkably improved.

Description

Technical Field

[0001] The present application belongs to the field of multi-shaft gas turbine drive, and specifically relates to a dual-motor variable frequency drive system for a multi-shaft gas turbine. Background Art

[0002] In traditional gas turbine starting systems, high-power gas turbines and single-shaft gas turbines usually use load rectifier inverters (LCI) to drive the gas turbine rotor to rotate. This method is not suitable for multi-shaft gas turbine starting control because it cannot directly drive the compressor rotor to rotate. Multi-shaft gas turbines usually use diesel engines or single electric motors to drive the compressor rotor to rotate through the auxiliary gearbox of the gas turbine with the help of a torque converter. In some large multi-shaft gas turbine starting systems, due to the large power demand of the compressor, multiple electric motors are required to work together to improve the power density and reliability of the system. However, the use of a multi-motor drive system will face problems such as inconsistent motor speed and unbalanced load, resulting in reduced system efficiency, easy overload of the motor, and even affecting the operating stability of the compressor. Summary of the invention

[0003] In order to solve the problems of inconsistent motor speed and unbalanced load when multiple motors are used to drive a large multi-shaft gas turbine in the prior art, a dual-motor variable frequency drive system for a multi-shaft gas turbine is proposed;

[0004] A dual-motor variable frequency drive system for a multi-shaft gas turbine, comprising an active motor, a driven motor, a master frequency converter, a slave frequency converter and a gas turbine auxiliary gearbox;

[0005] The master inverter is used to generate a control signal according to the set speed, and control the operation of the master motor according to the control signal. The master inverter is also used to obtain the current signal of the master motor and send the current signal of the master motor to the slave inverter; the slave inverter is used to control the slave motor to run synchronously with the master motor according to the received current signal of the master motor;

[0006] The output shaft of the main motor is connected to the output shaft of the slave motor. After connection, the output shaft of the main motor and the output shaft of the slave motor are simultaneously connected to the input shaft of the auxiliary gearbox of the gas turbine. The output shaft of the auxiliary gearbox of the gas turbine is connected to the input shaft of the multi-shaft gas turbine. The main motor and the slave motor are used to drive the multi-shaft gas turbine to operate through the auxiliary gearbox of the gas turbine.

[0007] Beneficial Effects

[0008] The dual-motor variable frequency drive system for a multi-shaft gas turbine of the present invention adopts a master-slave control strategy, uses a master motor and a slave motor to simultaneously drive the multi-shaft gas turbine to operate through a gas turbine auxiliary gearbox, a master frequency converter controls the operation of the master motor, and a slave frequency converter controls the slave motor to follow the master motor to operate synchronously according to a current signal of the master motor, thereby effectively realizing synchronous operation of the two motors and avoiding the problems of asynchronous speed and unbalanced load in traditional multi-motor drive systems; the system can realize stable driving of the multi-shaft gas turbine, enable the multi-shaft gas turbine to operate smoothly, and can significantly improve the service life of the equipment and the energy utilization efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a structural diagram of a dual-motor variable frequency drive system for a multi-shaft gas turbine according to a specific embodiment of the present application;

[0010] Figure 2 This is a schematic diagram of a dual-motor variable frequency drive system for a multi-shaft gas turbine according to a specific implementation of the present application. DETAILED DESCRIPTION

[0011] Specific implementation method 1: The following will be combined with the attached embodiment of the present invention Figure 1 and attached Figure 2 , illustrate this implementation mode, and clearly and completely describe the technical solutions in the embodiments of the present invention:

[0012] A dual-motor variable frequency drive system for a multi-shaft gas turbine, comprising an active motor 1, a driven motor 2, a main frequency converter 3, a slave frequency converter 4 and a gas turbine auxiliary gearbox 5;

[0013] The main frequency converter 3 is used to generate a control signal according to the set speed, and control the operation of the main motor 1 according to the control signal. The main frequency converter 3 is also used to obtain the current signal of the main motor 1, and send the current signal of the main motor 1 to the slave frequency converter 4; the slave frequency converter 4 is used to control the slave motor 2 to follow the main motor 1 to run synchronously according to the received current signal of the main motor 1;

[0014] The output shaft of the main motor 1 is connected to the output shaft of the slave motor 2. After the connection, the output shaft of the main motor 1 and the output shaft of the slave motor 2 are simultaneously connected to the input shaft of the gas engine auxiliary gearbox 5. The output shaft of the gas engine auxiliary gearbox 5 is connected to the input shaft of the multi-shaft gas turbine 6. The main motor 1 and the slave motor 2 are used to drive the multi-shaft gas turbine 6 to operate through the gas engine auxiliary gearbox 5.

[0015] Specifically, the system includes two motors, namely a main motor 1 and a slave motor 2. The main motor 1 and the slave motor 2 transmit power to the multi-shaft gas turbine 6 compressor through the gas turbine auxiliary gearbox 5; the frequency converter of the main motor 1 is the main control frequency converter 3, and the frequency converter of the slave motor 2 is the slave control frequency converter 4. The main control frequency converter 3 adjusts the speed of the main motor 1 through the control signal, and the slave frequency converter 3 controls the slave motor 2 to follow the main motor 1 according to the current signal of the main motor 1 to run synchronously, thereby realizing the synchronous operation of the two motors and balancing the current load, thereby improving the efficiency and stability of the system.

[0016] Furthermore, the output shaft of the main motor 1 and the output shaft of the slave motor 2 are rigidly connected.

[0017] Specifically, the master motor 1 and the slave motor 2 are rigidly connected. In actual operation, if one motor encounters a relatively large resistance, the speed of the motor will decrease, while the other motor will continue to maintain its original speed, which will cause the two motors to be out of sync. Therefore, the torque synchronization master-slave control mode that controls the speed of the slave motor according to the current of the master motor allows the actual current of the host to limit the maximum current of the slave motor, ensuring that the speed of the master motor and the slave motor is consistent, which can avoid damage to the equipment.

[0018] Further, the multi-shaft gas turbine 6 includes a low-pressure compressor, a high-pressure compressor, a combustion chamber and a turbine;

[0019] The input shaft of the low-pressure compressor is connected to the output shaft of the auxiliary gearbox of the combustion engine. The low-pressure compressor is driven by the auxiliary gearbox of the combustion engine to compress the gas to produce low-pressure gas, and transmit the low-pressure gas to the high-pressure compressor; the rotating blades in the high-pressure compressor rotate under the drive of the input low-pressure gas to produce high-pressure gas, and transmit the high-pressure gas to the combustion chamber;

[0020] Fuel is arranged in the combustion chamber. After the high-pressure gas is input into the combustion chamber, it is used to cold-blow the combustion chamber after combustion of the multi-shaft gas turbine to reduce the temperature of the gas turbine, purge the residual fuel in the combustion chamber of the multi-shaft gas turbine before starting, or mix with the fuel to burn to produce high-temperature and high-pressure combustion gas; the combustion chamber is used to transmit the generated high-temperature and high-pressure combustion gas to the turbine; the turbine shaft in the turbine rotates under the action of the high-temperature and high-pressure combustion gas to output mechanical energy.

[0021] Specifically, the system uses two electric motors and two frequency converters. The two electric motors are rigidly connected to synchronously drive the compressor rotors in the multi-shaft gas turbine. The two electric motors directly drive the compressor rotors to rotate, which is convenient for starting and controlling the multi-shaft gas turbine. The system uses a master-slave control strategy. The slave motor adjusts its operation according to the current signal of the master motor. The speed of the master motor and the slave motor are consistent, effectively ensuring stable operation of the system.

[0022] Furthermore, the output frequencies of the main motor 1 and the slave motor 2 are both 25 Hz. After the high-pressure gas is input into the combustion chamber, it is used to cold-blow the combustion chamber of the multi-shaft gas turbine after combustion to reduce the temperature of the gas turbine or to purge the residual fuel in the combustion chamber of the multi-shaft gas turbine before startup.

[0023] Furthermore, the output frequencies of the main motor 1 and the slave motor 2 are both 50 Hz. After the high-pressure gas is input into the combustion chamber, it is used to mix with the fuel in the combustion chamber and burn to produce high-temperature and high-pressure combustion gas.

[0024] Specifically, the output frequency of the main motor and the slave motor is controlled to be 25Hz and run smoothly at the same time, realizing the cold blowing function of the gas turbine, that is, blowing the residual fuel in the combustion chamber of the multi-shaft gas turbine before starting the multi-shaft gas turbine, and reducing the combustion chamber temperature after the multi-shaft gas turbine burns. The output frequency of the main motor and the slave motor is controlled to be 25Hz and run smoothly, and the output frequency of the main motor and the slave motor is controlled to be 50Hz and run smoothly. After the high-pressure gas is input into the combustion chamber, it is used to mix with the fuel in the combustion chamber to burn and produce high-temperature and high-pressure gas, and the gas turbine outputs mechanical energy.

[0025] Furthermore, the rated voltage of the main motor 1 is 380V three-phase AC, the reference frequency is 50Hz, the nominal power is 45kW, and the synchronous speed is 3000rpm.

[0026] Furthermore, the rated voltage of the slave motor 2 is 380V three-phase AC, the reference frequency is 50Hz, the nominal power is 45kW, and the synchronous speed is 3000rpm.

[0027] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A dual-motor variable frequency drive system for a multi-shaft gas turbine, characterized in that: It comprises an active motor (1), a driven motor (2), a main frequency converter (3), a slave frequency converter (4) and a combustion engine auxiliary gearbox (5); The main frequency converter (3) is used to generate a control signal according to a set rotation speed, and control the operation of the main motor (1) according to the control signal. The main frequency converter (3) is also used to obtain a current signal of the main motor (1), and send the current signal of the main motor (1) to the slave frequency converter (4); the slave frequency converter (4) is used to control the slave motor (2) to follow the main motor (1) to operate synchronously according to the received current signal of the main motor (1); The output shaft of the main motor (1) is connected to the output shaft of the slave motor (2). After the connection, the output shaft of the main motor (1) and the output shaft of the slave motor (2) are simultaneously connected to the input shaft of the auxiliary gearbox (5) of the combustion engine. The output shaft of the auxiliary gearbox (5) of the combustion engine is connected to the input shaft of the multi-shaft gas turbine (6). The main motor (1) and the slave motor (2) are used to drive the multi-shaft gas turbine (6) to operate through the auxiliary gearbox (5) of the combustion engine.

2. A dual-motor variable frequency drive system for a multi-shaft gas turbine according to claim 1, characterized in that: The output shaft of the main motor (1) and the output shaft of the slave motor (2) are rigidly connected.

3. The dual-motor variable frequency drive system for a multi-shaft gas turbine according to claim 1, characterized in that: The multi-shaft gas turbine (6) comprises a low-pressure compressor, a high-pressure compressor, a combustion chamber and a turbine; The input shaft of the low-pressure compressor is connected to the output shaft of the auxiliary gearbox (5) of the combustion engine. The low-pressure compressor is driven by the auxiliary gearbox (5) of the combustion engine to compress gas to generate low-pressure gas, and transmits the low-pressure gas to the high-pressure compressor; the rotating blades in the high-pressure compressor rotate under the drive of the input low-pressure gas to generate high-pressure gas, and transmit the high-pressure gas to the combustion chamber; Fuel is arranged in the combustion chamber. After the high-pressure gas is input into the combustion chamber, it is used to cool the combustion chamber after combustion of the multi-shaft gas turbine to reduce the temperature of the multi-shaft gas turbine, purge the residual fuel in the combustion chamber of the multi-shaft gas turbine before starting, or mix with the fuel to burn to produce high-temperature and high-pressure combustion gas; the combustion chamber is used to transmit the generated high-temperature and high-pressure combustion gas to the turbine; the turbine shaft in the turbine rotates under the action of the high-temperature and high-pressure combustion gas to output mechanical energy.

4. A dual-motor variable frequency drive system for a multi-shaft gas turbine according to claim 3, characterized in that: The output frequencies of the main motor (1) and the slave motor (2) are both 25 Hz. After the high-pressure gas is input into the combustion chamber, it is used to cold-blow the combustion chamber of the multi-shaft gas turbine after combustion to reduce the temperature of the multi-shaft gas turbine or to purge the residual fuel in the combustion chamber of the multi-shaft gas turbine before starting.

5. The dual-motor variable frequency drive system for a multi-shaft gas turbine according to claim 3, characterized in that: The output frequencies of the main motor (1) and the slave motor (2) are both 50 Hz. After the high-pressure gas is input into the combustion chamber, it is mixed with the fuel in the combustion chamber and burned to generate high-temperature and high-pressure combustion gas.

6. The dual-motor variable frequency drive system for a multi-shaft gas turbine according to claim 1, characterized in that: The rated voltage of the main motor (1) is three-phase AC 380V, the base frequency is 50Hz, the nominal power is 45kW, and the synchronous speed is 3000rpm.

7. The dual-motor variable frequency drive system for a multi-shaft gas turbine according to claim 1, characterized in that: The rated voltage of the slave motor (2) is 380V three-phase AC, the base frequency is 50Hz, the nominal power is 45kW, and the synchronous speed is 3000rpm.

Images