A starting control method and system for a gas turbine starting frequency converter

Abstract

The present invention discloses a starting control method and system for a gas turbine starting frequency converter. The system includes an initial motor position detection module, a real-time detection module for motor rotor position and speed, a rotor angle selection module, a rotor sector determination module, an inverter bridge pulse trigger module, and an excitation current module. The initial motor position detection module detects the initial position of the generator in a stationary state. The real-time detection module for motor rotor position and speed real-time collects the three-phase voltage at the machine terminal and monitors the real-time position and speed of the rotor. The rotor angle selection module selects the rotor angle. The rotor sector determination module determines the rotor sector according to the rotor angle. The inverter bridge pulse trigger module determines the trigger pulse sequence of the inverter bridge according to the rotor sector. The excitation current module calculates and adjusts to obtain the rotor excitation current. The present invention can effectively prevent the gas turbine starting frequency converter from controlling the unit speed from smoothly rising without reverse rotation during the low-speed forced commutation stage, and realize the stable starting of the gas turbine unit.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control and power electronic conversion, and specifically, to a starting control method and system for a gas turbine starting frequency converter. Background Art

[0002] A gas turbine starting frequency converter is a device used for the static starting of a gas turbine. When a gas turbine power plant is put into grid-connected operation, the gas turbine needs to be dragged to a certain speed for ignition. After successful ignition, the gas turbine is continuously dragged to a speed above the self-sustaining speed to realize the grid-connected power generation of the gas turbine generator set. During the daily maintenance of the gas turbine, the starting device is also required to drag the gas turbine to a specific speed for water washing and rapid cooling.

[0003] A gas turbine starting frequency converter is a complex power electronic conversion device. The control system of the gas turbine starting frequency converter needs to control the operation of the rectifier bridge and the inverter bridge to realize the normal starting and operation and maintenance of the gas turbine unit. When the gas turbine starting frequency converter drags the gas turbine to start generating electricity normally, or for water washing or rapid cooling, it is necessary to stably and reliably drag the gas turbine unit from the turning speed or the stationary state to the target speed. The dragging process is generally divided into the forced commutation stage and the load commutation stage. In the forced commutation stage where the generator speed is relatively low, due to the low back electromotive force of the generator, it cannot be used for the load commutation of the inverter bridge. Therefore, forced commutation control is required in the low-speed dragging stage. During the low-speed dragging process, it is required to control the speed to rise smoothly and not reverse. If the speed fluctuates violently or even reverses, it is easy to cause damage to the gas turbine. Summary of the Invention

[0004] The present invention provides a starting control method and system for a gas turbine starting frequency converter, which can prevent the gas turbine starting frequency converter from controlling the speed of the gas turbine unit from rising smoothly without reversing in the low-speed forced commutation stage, prevent damage to the gas turbine during the dragging process, and realize the reliable and stable starting of the gas turbine unit.

[0005] The technical solution of the present invention is as follows:

[0006] A starting control method for a gas turbine starting frequency converter, and the process of starting control is as follows:

[0007] First, the three-phase terminal voltages of the generator of the gas turbine unit are collected in real time u uvw , the initial position of the generator in the stationary state is detected θ 0, and at the same time, the real-time position of the rotor of the generator is monitored θ r and the speed w r; Select the rotor angle for rotor sector determination, determine the rotor sector according to the selected rotor angle, then determine the trigger pulse sequence of the inverter bridge according to the rotor sector, and then according to the real-time position of the rotor θ r and the stator magnetic field vector angle θ s Calculate and adjust the rotor excitation current.

[0008] According to the above starting control method, the specific implementation process is as follows:

[0009] After receiving the gas turbine start command, determine whether the current motor rotor is stationary. If the motor rotor is in a stationary state, give a step excitation signal through the generator excitation system, and calculate the initial position of the generator by detecting the three-phase voltage at the generator terminal; if the generator rotor is not in a stationary state, monitor the real-time position of the generator rotor θ r and the current rotor speed w r ; Compare the current rotor speed w r and the set threshold speed for exiting forced commutation w th : If w r > w th , then exit the current control mode, otherwise determine the rotor sector according to the current rotor angle; then determine the trigger pulse sequence of the inverter bridge according to the rotor sector and according to the real-time position of the rotor θ r and the motor stator magnetic field vector angle θ s Calculate and adjust the rotor excitation current.

[0010] The system for implementing the above gas turbine starting frequency converter starting control method specifically includes: a motor initial position detection module, a motor rotor position and speed real-time detection module, a rotor angle selection module, a rotor sector determination module, an inverter bridge pulse trigger module, and an excitation current module. Among them,

[0011] Apply a demagnetizing excitation current through the generator excitation winding. The motor initial position detection module is used to detect the generator terminal voltage and calculate the initial position of the generator according to the detected terminal voltage θ 0;

[0012] The motor rotor position and speed real-time detection module is used to calculate the real-time position of the generator rotor by detecting the terminal voltage θ r and the current speed w r ;

[0013] The rotor angle selection module selects the rotor angle for rotor sector determination. When the generator is in a stationary state, it selects the rotor position θ 0, otherwise it selects the rotor position θ r ;

[0014] The rotor sector determination module determines the rotor sector according to the rotor angle selected by the rotor angle selection module;

[0015] The inverter bridge pulse triggering module determines the trigger pulse sequence of the inverter bridge according to the rotor sector;

[0016] The field current module calculates and adjusts the rotor field current according to the real-time position of the rotor θ r , the stator magnetic field vector angle θ s ; I f ;

[0017] With the obtained trigger pulse sequence and rotor field current I f Effectively start and control the gas turbine unit.

[0018] Furthermore, the method for the motor initial position detection module to calculate the initial position of the generator θ 0 is as follows:

[0019]

[0020] Wherein, u u , u v , u w are the three-phase voltages at the machine terminal.

[0021] Furthermore, the specific calculation process of the real-time position θ r and the current speed w r of the generator rotor by the motor rotor position and speed real-time detection module is as follows: Perform a rotational coordinate transformation on the three-phase voltages u u , u v , u w at the machine terminal to obtain the direct-axis and quadrature-axis components u d , u q in the rotating coordinate system. For the d-axis component u dPerform PI operation to obtain the generator rotor speed w r , and then perform integration on the obtained generator rotor speed w r to obtain the angle of the generator rotor θ r .

[0022] Further, the rotor angle selection module selects the rotor angle for rotor sector determination. When the generator is in a stationary state, it selects the rotor position calculated by the motor initial position detection module θ 0, otherwise it selects the rotor position calculated by the motor rotor position and speed real-time detection module θ r .

[0023] Further, the correspondence between the rotor angle and the rotor sector of the inverter bridge pulse trigger module for determining the trigger pulse sequence is as follows:

[0024] When the rotor angle is in (0°, 60°], it corresponds to rotor sector 1;

[0025] When the rotor angle is in (60°, 120°], it corresponds to rotor sector 2;

[0026] When the rotor angle is in (120°, 180°], it corresponds to rotor sector 3;

[0027] When the rotor angle is in (-180°, -120°], it corresponds to rotor sector 4;

[0028] When the rotor angle is in (-120°, -60°], it corresponds to rotor sector 5;

[0029] When the rotor angle is in (-60°, 0°], it corresponds to rotor sector 6.

[0030] Further, the width of the pulse sequence t p is determined according to the current speed w r and the pulse width coefficient k p :

[0031] .

[0032] Further, the excitation current module calculates and adjusts the rotor excitation current I f in the following manner:

[0033]

[0034] Wherein: I0 is the reference value of the exciting current.

[0035] The beneficial effects that the present invention can achieve are as follows:

[0036] (1) It can adapt to the static start and initial speed start of the gas turbine unit;

[0037] (2) By adjusting the exciting current according to the real-time position of the rotor, a constant driving torque can be achieved during the driving process, which is beneficial to the smooth start and acceleration of the generator unit;

[0038] (3) During the driving process, the rotor position of the motor is detected in real time, and the pulse sequence of the inverter bridge is determined through the rotor position, so that the position of the stator magnetic field vector applied to the generator can be adjusted in real time, effectively avoiding the fluctuation and reverse rotation of the generator speed during the driving process. Description of the Drawings

[0039] Figure 1 is a schematic diagram of the gas turbine starting system of the present invention.

[0040] Figure 2 is a schematic diagram of the connection relationship between the inverter bridge of the gas turbine starting system and the generator in the embodiment.

[0041] Figure 3 is a schematic diagram of the control of the gas turbine starting control method in the embodiment.

[0042] Figure 4 is a schematic diagram of the real-time detection module of the motor rotor position and speed in the embodiment.

[0043] Figure 5 is the corresponding relationship between the rotor position, rotor sector and inverter bridge pulse sequence in the embodiment.

[0044] Figure 6 is a schematic diagram of the implementation process of the starting control in the embodiment.

[0045] In the figure: 1 - transformation from abc stationary coordinate system to dq rotating coordinate system, 2 - proportional-integral control link, 3 - integral link. Detailed Embodiment

[0046] Next, the technical solution of the present invention will be further described in conjunction with the drawings in the embodiments.

[0047] As Figure 1 described, the gas turbine starting frequency converter mainly includes a rectifier bridge, a smoothing reactor, an inverter bridge and a control system. The rectifier bridge is used to control the current of the smoothing reactor, and the inverter bridge starts and controls the motor by controlling the stator current of the motor.

[0048] The midpoints of the three-phase bridge arms of the inverter bridge are respectively connected to the three-phase stator windings of the generator, and the switch numbers of the inverter bridge are asFigure 2 As shown, during the startup process, the excitation current tracks the excitation current command and cooperates with the startup process throughout.

[0049] This embodiment provides a starting frequency converter starting control system for a gas turbine, a system for a gas turbine starting frequency converter starting control method, specifically including: a motor initial position detection module, a motor rotor position and speed real-time detection module, a rotor angle selection module, a rotor sector determination module, an inverter bridge pulse trigger module, and an excitation current module. As Figure 3 shown, the steps of implementing the gas turbine starting frequency converter starting control method through this system are:

[0050] Real-time collect the three-phase terminal voltage of the generator of the gas turbine unit u uvw , and detect the initial position of the motor in the static state of the motor through the motor initial position detection module θ 0, and at the same time use the generator rotor position and speed real-time detection module to monitor the real-time position of the generator rotor θ r and the current speed w r ; the rotor angle selection module selects the rotor angle for rotor sector determination; the rotor sector determination module determines the rotor sector according to the rotor angle, the inverter bridge pulse trigger module determines the trigger pulse sequence of the inverter bridge according to the rotor sector, and the excitation current module calculates and adjusts the rotor excitation current according to the real-time position of the rotor θ r and the stator magnetic field vector angle of the motor θ s Calculate and adjust the rotor excitation current.

[0051] The motor initial position detection module induces a voltage at the generator terminal by applying a demagnetizing excitation current to the generator excitation winding, and calculates the initial position of the generator according to the detected terminal voltage as:

[0052]

[0053] The motor rotor position and speed real-time detection module calculates the real-time position and current speed of the generator rotor by detecting the terminal voltage. The specific calculation process: perform a rotational coordinate transformation on the three-phase terminal voltage u u , u v , u w to obtain the direct-axis and quadrature-axis components in the rotating coordinate system u d , u q , for the d-axis component u dPerform PI operation to obtain the rotor speed w r , Integrate the speed obtained from the PI operation to obtain the rotor angle θ r , as Figure 4 shown

[0054] The rotor angle selection module selects the angle for rotor sector determination. When the generator is in a stationary state, it selects the rotor position calculated by the motor initial position detection module θ 0, otherwise it selects the rotor position calculated by the motor rotor position and speed detection module θ r .

[0055] The correspondence between the motor rotor angle, rotor sector, and pulse sequence is as Figure 5 shown, specifically as follows:

[0056] When the rotor angle is in the range of (0°, 60°], it corresponds to rotor sector 1, and trigger pulses are applied to thyristors 2 and 3;

[0057] When the rotor angle is in the range of (60°, 120°], it corresponds to rotor sector 2, and trigger pulses are applied to thyristors 3 and 4;

[0058] When the rotor angle is in the range of (120°, 180°], it corresponds to rotor sector 3, and trigger pulses are applied to thyristors 4 and 5;

[0059] When the rotor angle is in the range of (-180°, -120°], it corresponds to rotor sector 4, and trigger pulses are applied to thyristors 5 and 6;

[0060] When the rotor angle is in the range of (-120°, -60°], it corresponds to rotor sector 5, and trigger pulses are applied to thyristors 6 and 1;

[0061] When the rotor angle is in the range of (-60°, 0°], it corresponds to rotor sector 6, and trigger pulses are applied to thyristors 1 and 2.

[0062] The width of the pulse sequence t p is determined according to the current speed of the generator w r and the pulse width coefficient k p :

[0063]

[0064] where the pulse width coefficient k p is related to the generator speed and generally takes a value of 0.7 - 0.9; t pThe value generally ranges from ten milliseconds to seconds.

[0065] The excitation current module calculates and adjusts the rotor excitation current according to the real-time position of the rotor θ r and the angle of the stator magnetic field vector of the motor θ s :

[0066]

[0067] Where: I 0 is the reference value of the excitation current, which is generally selected as the rated current value of the starting excitation device.

[0068] Furthermore, in this embodiment, the implementation process of the starting control method is as Figure 6 shown:

[0069] After receiving the gas turbine starting command, it is determined whether the current motor rotor is stationary. If the motor rotor is in a stationary state, a step excitation signal is given through the generator excitation system, and the initial position of the generator is calculated by detecting the three-phase voltage at the generator terminal through the motor initial position detection module.

[0070] If the generator rotor is not in a stationary state, the real-time position of the generator rotor is monitored by using the motor rotor position real-time detection module θ r and the rotational speed w r .

[0071] Compare the current motor speed w r with the set threshold of the exit forced commutation speed w th . If w r > w th , the current control mode is exited. Otherwise, the rotor sector is determined according to the current rotor angle; then the trigger pulse sequence of the inverter bridge is determined according to the rotor sector, and the rotor excitation current is calculated and adjusted according to the real-time position of the rotor θ r and the angle of the stator magnetic field vector of the motor θ s .

[0072] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A starting control method for a gas turbine starting frequency converter, characterized in that, The process of startup control is as follows: First, collect the three-phase terminal voltage of the generator of the gas turbine unit in real time u uvw , and detect the initial position of the generator in the stationary state θ 0, and at the same time monitor the real-time position of the generator rotor θ r and speed w r ; Select the rotor angle for rotor sector determination, determine the rotor sector according to the selected rotor angle, then determine the trigger pulse sequence of the inverter bridge according to the rotor sector, and then calculate and adjust the rotor excitation current according to the real-time position of the rotor θ r and the stator magnetic field vector angle θ s ; The specific implementation process is as follows: After receiving the gas turbine startup command, determine whether the current motor rotor is stationary. If the motor rotor is in a stationary state, give a step excitation signal through the generator excitation system, and calculate the initial position of the generator by detecting the three-phase voltage at the generator terminals; if the generator rotor is not in a stationary state, monitor the real-time position of the generator rotor θ r and the current rotor speed w r ; Compare the current rotor speed w r with the set threshold speed for exiting forced commutation w th : If w r > w th , then exit the current control mode; otherwise, determine the rotor sector according to the current rotor angle; then determine the trigger pulse sequence of the inverter bridge according to the rotor sector and calculate and adjust the rotor excitation current according to the real-time position of the rotor θ r and the angle of the motor stator magnetic field vector θ s ​ 2. A system for implementing the gas turbine starting frequency converter starting control method according to claim 1, characterized in that, It includes a motor initial position detection module, a real-time detection module for the position and speed of the motor rotor, a rotor angle selection module, a rotor sector determination module, an inverter bridge pulse trigger module, and an excitation current module. Among them, Applying a demagnetizing excitation current through the generator excitation winding, the motor initial position detection module is used to detect the generator terminal voltage, and the initial position of the generator is calculated based on the detected terminal voltage θ 0; The real-time detection module for the position and speed of the motor rotor calculates the real-time position of the generator rotor by detecting the terminal voltage of the machine θ r and the current speed w r ; The rotor angle selection module selects the rotor angle for rotor sector determination. When the generator is in a stationary state, it selects the rotor position θ 0, otherwise it selects the rotor position θ r ; The rotor sector determination module determines the rotor sector according to the rotor angle selected by the rotor angle selection module; The inverter bridge pulse trigger module determines the trigger pulse sequence of the inverter bridge according to the rotor sector; The excitation current module calculates and adjusts the rotor excitation current according to the real-time position of the rotor θ r , the stator magnetic field vector angle θ s ; I f ; By obtaining the trigger pulse sequence and the rotor excitation current I f Effectively start and control the gas turbine unit.

3. The gas turbine starting frequency converter starting control system according to claim 2, characterized in that The motor initial position detection module calculates the initial position of the generator θ The method for 0 is as follows: Among them, u u , u v , u w are the three-phase voltages at the generator terminal.

4. The gas turbine starting frequency converter starting control system according to claim 2, characterized in that, The real-time position of the generator rotor of the real-time detection module for the position and speed of the motor rotor θ r and the current speed w r The specific calculation process is as follows: Perform a rotating coordinate transformation on the three-phase voltages at the machine terminal u u 、 u v 、 u w to obtain the direct-axis and quadrature-axis components in the rotating coordinate system u d 、 u q Perform a PI operation on the d-axis component u d to obtain the generator rotor speed w r Then integrate the obtained generator rotor speed w r to obtain the angle of the generator rotor θ r 。 5. The gas turbine starting frequency converter starting control system according to claim 2, wherein, The rotor angle selection module selects the rotor angle for rotor sector determination. When the generator is in a stationary state, it selects the rotor position calculated by the motor initial position detection module. θ Otherwise, it selects the rotor position calculated by the motor rotor position and speed real-time detection module. θ r .

6. The gas turbine starting frequency converter starting control system according to claim 2, wherein The corresponding relationship between the rotor angle and the rotor sector for the inverter bridge pulse trigger module to determine the trigger pulse sequence is as follows: When the rotor angle is in (0°, 60°], it corresponds to rotor sector 1; When the rotor angle is in (60°, 120°], it corresponds to rotor sector 2; When the rotor angle is in (120°, 180°], it corresponds to rotor sector 3; When the rotor angle is in (-180°, -120°], it corresponds to rotor sector 4; When the rotor angle is in (-120°, -60°], it corresponds to rotor sector 5; When the rotor angle is in (-60°, 0°], it corresponds to rotor sector 6.

7. The gas turbine starting frequency converter starting control system according to claim 2 or 6, characterized in that, The width of the pulse sequence t p According to the current rotational speed w r and the pulse width coefficient k p determine: 。 8. The gas turbine starting frequency converter starting control system according to claim 2, characterized in that The excitation current module calculates and adjusts the rotor excitation current I f in the following manner: Wherein: I 0 is the reference value of the exciting current.

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