A method for suppressing speed fluctuation of a gas turbine generator set

Abstract

The present invention discloses a method for suppressing speed fluctuations in a gas turbine generator set, comprising: real-time measurement of key parameters of a synchronous generator; performing speed feedforward compensation control to obtain a voltage control deviation ΔU, which is then input into the voltage control link; coordinate-shifting the output current value of the synchronous motor to form the actual value of a control signal; performing current feedback control based on the voltage control parameters obtained through the speed feedforward compensation control; and achieving speed regulation through space vector PWM control. Based on a dual-loop closed-loop control method of voltage and current, the present invention utilizes the speed fluctuation value of the gas turbine as a speed feedforward compensation signal and adds a voltage loop instruction. By altering the output characteristics of the DC voltage system, the method can reduce the generator speed fluctuation range when the generator load suddenly changes, achieve speed stability in a relatively short period of time, thereby suppressing generator speed fluctuations and reducing hardware costs.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion engine control, and in particular to a method for suppressing speed fluctuation of a gas turbine generator set. Background Art

[0002] Gas turbines are currently widely used in power systems, power plants, ship electrical systems, and aircraft engines, among other applications. A gas turbine's control unit primarily consists of a turbine and a generator, connected only by aerodynamic forces. This creates significant information transmission delays within the speed cascade closed-loop control system. Load fluctuations in the gas turbine cause fluctuations in the generator speed, especially during periods of drastic load changes (load rejection or sudden load surges). The information transmitted from the generator speed control system to the turbine control system is subject to significant time delays, making it difficult to maintain stable system operation during these periods.

[0003] The current solution is to add a signal acquisition module to the traditional speed cascade closed-loop control system to enable real-time acquisition of the permanent magnet synchronous generator's current and voltage signals and real-time calculation of load power changes. This allows the gas turbine's fuel supply to be adjusted accordingly, thereby suppressing generator speed fluctuations caused by sudden load fluctuations. This approach requires the addition of a signal acquisition and analysis module to predict load changes, which relies on high-precision voltage and current sampling and complex control algorithms. This not only increases hardware costs but also introduces new instabilities into the gas turbine's speed cascade control system. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0005] In view of the above-mentioned problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by the present invention is that the existing method requires the addition of a signal acquisition and analysis module to predict load changes, which relies on high-precision voltage and current sampling and complex control algorithms. This not only brings more hardware costs, but also introduces new instability factors to the speed cascade control system of the gas turbine.

[0007] To solve the above technical problems, the present invention provides the following technical solution: a method for suppressing speed fluctuations of a gas turbine generator set, comprising:

[0008] Real-time measurement of key parameters of synchronous generators;

[0009] Perform speed feedforward compensation control to obtain the voltage control deviation ΔU and put it into the voltage control link;

[0010] Performing coordinate changes on the output current value of the synchronous motor to form an actual value of a control signal;

[0011] Performing current feedback control in combination with the voltage control parameters obtained by the speed feedforward compensation control;

[0012] Speed ​​regulation is achieved through space vector PWM control.

[0013] As a preferred solution of the method for suppressing speed fluctuation of a gas turbine generator set according to the present invention, the key parameters include the actual speed ω m and the flux linkage angle θ e .

[0014] As a preferred solution of the method for suppressing speed fluctuation of a gas turbine generator set according to the present invention, the speed feedforward compensation control includes:

[0015] Calculate the actual speed ω m and target speed The gap Δω:

[0016]

[0017] The voltage control deviation ΔU is obtained after PI compensation adjustment.

[0018] As a preferred solution of the method for suppressing speed fluctuation of a gas turbine generator set according to the present invention, the voltage control link includes:

[0019] When the actual speed exceeds the limit, ΔU<0, when the actual speed decreases, ΔU>0;

[0020] Get voltage control parameters

[0021] in, It is the target voltage value of the PWM rectifier control output.

[0022] As a preferred solution of the method for suppressing speed fluctuation of a gas turbine generator set according to the present invention, the speed feedforward compensation control further comprises:

[0023] After obtaining the voltage control parameter U * Then, the voltage control parameter U * and load real-time voltage U dc The difference U after comparison *-U dc After PI compensation adjustment, the q-axis current control target value is obtained

[0024] As a preferred solution of the method for suppressing speed fluctuation of a gas turbine generator set described in the present invention, the coordinate change includes Park change and Clark change.

[0025] As a preferred solution of the method for suppressing speed fluctuation of a gas turbine generator set according to the present invention, wherein:

[0026] The current feedback control includes:

[0027] The current value i detected by the sensor a 、i b After the Clark transformation and the Park transformation, the direct axis current i is obtained. d and the quadrature axis current and i q ;

[0028] Then compare with the target current value and the current control target value Make a comparison.

[0029] As a preferred solution of the method for suppressing speed fluctuation of a gas turbine generator set according to the present invention, the comparison is as follows: the direct axis current i d and the quadrature axis current and i q and the target current value respectively and current control target value Make the difference and get the difference as Δi d and Δi q .

[0030] As a preferred solution of the method for suppressing speed fluctuation of a gas turbine generator set according to the present invention, the current feedback control further comprises:

[0031] The Δi d and Δi q As the input of the current PI regulator, the reference output voltage is obtained and The input U of the SVPWM module is transformed by the Park transformation. d and U q .

[0032] As a preferred solution of the method for suppressing speed fluctuations of a gas turbine generator set described in the present invention, the space vector PWM control is: the pulse signal generated by the PWM module controls the switch closing time of the three-phase inverter, adjusts the size of the input current, and completes the speed regulation.

[0033] The beneficial effects of the present invention are as follows: The present invention is based on a dual-loop closed-loop control method of voltage and current, adopts the speed fluctuation value of the gas turbine as the speed feedforward compensation signal, adds a voltage loop instruction, and changes the output characteristics of the DC voltage system. When the generator load changes suddenly, the fluctuation range of the generator speed can be reduced, and the speed can be stabilized in a shorter time, thereby suppressing the fluctuation of the generator speed and reducing the hardware cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0035] Figure 1 A control flow chart of a method for suppressing speed fluctuations of a gas turbine generator set provided by one embodiment of the present invention;

[0036] Figure 2 A schematic block diagram of a specific process control of a method for suppressing speed fluctuations of a gas turbine generator set provided by one embodiment of the present invention;

[0037] Figure 3 A schematic diagram of a control system architecture for a method for suppressing speed fluctuations of a gas turbine generator set provided by one embodiment of the present invention;

[0038] Figure 4 A diagram showing motor speed simulation results of a method for suppressing speed fluctuations of a gas turbine generator set provided by a second embodiment of the present invention;

[0039] Figure 5 A diagram showing output voltage simulation results of a method for suppressing speed fluctuations of a gas turbine generator set provided by a second embodiment of the present invention;

[0040] Figure 6 This is another output voltage simulation result diagram of a method for suppressing speed fluctuations of a gas turbine generator set provided by the second embodiment of the present invention. DETAILED DESCRIPTION

[0041] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0043] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0044] The present invention is described in detail with reference to schematic diagrams. For ease of illustration, cross-sectional views of device structures may be partially enlarged and not to scale when describing embodiments of the present invention. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual production, the three-dimensional dimensions of length, width, and depth should be included.

[0045] In the description of the present invention, it should be noted that the terms "upper, lower, inner, and outer" and other references to orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first, second, or third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0046] In this disclosure, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they may refer to fixed, removable, or integral connections. They may also refer to mechanical, electrical, or direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure.

[0047] Example 1

[0048] Reference Figures 1 to 3 , as one embodiment of the present invention, provides a method for suppressing speed fluctuations of a gas turbine generator set, comprising:

[0049] S1: Real-time measurement of key parameters of synchronous generators;

[0050] It should be noted that the permanent magnet synchronous generator is driven by the gas turbine and is connected to an equivalent load Z through pulse width modulation (PWM) rectifier control. The gas turbine control adopts speed cascade control to control the speed of the gas turbine turbine. The generator control unit includes a permanent magnet synchronous generator and a three-phase voltage type PWM rectifier, see Figure 3 .

[0051] Specifically, the key parameters include the actual speed ω m and the flux linkage angle θ e .

[0052] It should be noted that the real-time monitoring of the generator speed is done by combining the speed sensor with the phase measurement to measure the speed of the synchronous generator in real time. m and the flux linkage angle θ e , used for subsequent calculations.

[0053] S2: Perform speed feedforward compensation control to obtain the voltage control deviation ΔU and put it into the voltage control link;

[0054] Furthermore, the speed feedforward compensation control includes:

[0055] Calculate the actual speed ω m and target speed The gap Δω:

[0056]

[0057] After PI compensation adjustment, the voltage control deviation ΔU is obtained.

[0058] Furthermore, the voltage control link includes:

[0059] When the actual speed exceeds the limit, ΔU<0, when the actual speed decreases, ΔU>0;

[0060] Get voltage control parameters

[0061] in, It is the target voltage value of the PWM rectifier control output.

[0062] Furthermore, the speed feedforward compensation control also includes:

[0063] After obtaining the voltage control parameter U * Then, the voltage control parameter U * and load real-time voltage U dc The difference U after comparison * -U dc After PI compensation adjustment, the q-axis current control target value is obtained is the control signal of the current link.

[0064] S3: Change the coordinates of the synchronous motor output current value to form the actual value of the control signal;

[0065] Furthermore, the coordinate change includes Park change and Clark change.

[0066] It should be noted that coordinate transformation allows each physical quantity to be converted to a synchronously rotating coordinate system, simplifying the calculation process and achieving real-time calculation and control. By controlling the motor in real time according to the target given quantity, control performance similar to that of a DC motor can be achieved.

[0067] Specifically, the Clark transformation transforms from the natural coordinate system ABC axis to the stationary coordinate system αβ axis, and the Park transformation transforms from the stationary coordinate system ABC axis to the synchronously rotating coordinate system dq axis.

[0068] Clark transformation can be expressed as:

[0069] [f a f β f0] T =T 3s / 2s [f A f B f C ] T (1)

[0070]

[0071] Where f can represent variables such as voltage, current or magnetic flux; T 3s / 2s is the coordinate transformation matrix.

[0072] The coordinate transformation from the stationary coordinate system αβ to the natural coordinate system ABC is the inverse Clark transformation, which can be expressed as:

[0073] [f A f B f C ] T =T 3s / 2s [f a f β f0] T (3)

[0074]

[0075] Specifically, Park transformation: The transformation transforms the stationary coordinate system αβ to the synchronous rotating coordinate system dq axis, and its expression is as follows:

[0076] [f d fq ]T =T 2s / 2r [f α f β ] T (5)

[0077]

[0078] Among them, θ e Magnetic flux angle, T 2s / 2r is the coordinate transformation matrix. Conversely, the coordinate transformation that transforms the synchronous rotating coordinates dq to the stationary coordinate system αβ is called the inverse Park transformation and can be expressed as:

[0079] [f a f β ] T =T 2r / 2s [f d f q ] T (7)

[0080]

[0081] Transform the natural coordinate system ABC to the synchronous rotating coordinate system dq. The conversion relationship between the variables is:

[0082] [f a f q f0] T =T 3s / 2r [f A f B f C ] T (9)

[0083]

[0084] The coordinate transformation relationship of transforming the synchronous rotating coordinate system dq to the natural coordinate system ABC is:

[0085] [f A f B f C ] T =T 2r / 3s [f a f q f0] T (11)

[0086]

[0087] S4: Current feedback control is performed by combining the voltage control parameters obtained by speed feedforward compensation control;

[0088] Furthermore, current feedback control includes:

[0089] The current value i detected by the sensor a 、i b After Clark transformation and Park transformation, the direct axis current i is obtained. d and the quadrature axis current and i q ;

[0090] Then compare with the target current value and Make a comparison.

[0091] Furthermore, the comparison is: the direct axis current i d and the quadrature axis current and i q and the target current value respectively and Make the difference, and get the difference as Δi d and Δi q .

[0092] Furthermore, current feedback control also includes:

[0093] Δi d and Δi q As the input of the current PI regulator, the reference output voltage is obtained and The input U of the SVPWM module is converted into modularization through Park transformation d and U q .

[0094] S5: Speed ​​regulation is achieved through space vector PWM control.

[0095] Furthermore, space vector PWM control is as follows: the pulse signal generated by the PWM module controls the switch closing time of the three-phase inverter, adjusts the input current, and completes the speed regulation.

[0096] In the above, by setting the speed feedforward compensation link, dual closed-loop control of voltage and current is achieved to realize DC voltage stability, and the DC voltage output characteristics of the system are adjusted to match the load change rate on the load side.

[0097] Example 2

[0098] Reference Figure 4-6 , is an embodiment of the present invention. In order to verify and illustrate the technical effects adopted in this method, this embodiment adopts simulation experiments to verify the real effects of this method by means of scientific demonstration.

[0099] The permanent magnet synchronous motor has a rated power of 320kW, a rated speed of 6000 rpm, a stator resistance of 0.027 ohm, a D-axis stator inductance of 0.175mH, a Q-axis stator inductance of 0.359mH, and a permanent magnet flux of 0.27Wb.

[0100] The simulation conditions are as follows:

[0101] The load circuit voltage is 720V, and the load is linearly reduced from 62 ohms to 2 ohms within 20 seconds. The speed feedforward compensation strategy is added at the 40th second, and a 7kW load is suddenly added at the 60th second. The results are as follows: Figure 4-5 :

[0102] The simulation results show that without speed feedforward compensation, the gas turbine's output speed fluctuated by approximately 500 rpm. However, after the speed compensation algorithm was implemented at 40 seconds, the gas turbine's output speed quickly stabilized at 6000 rpm. Furthermore, the bus voltage of the generator rectifier continued to fluctuate without speed feedforward compensation, indicating that voltage stability was affecting the stability of the gas turbine's output speed. After implementing the speed feedforward compensation algorithm at 40 seconds, the generator rectifier's output voltage remained stable at around 720 V. When a 7 kW load was added at 60 seconds, the gas turbine's output speed remained stable with the speed feedforward compensation algorithm. By modifying the DC system's output voltage characteristics as power increases, speed fluctuations can be effectively suppressed.

[0103] The test was conducted based on an actual motor, where the gas turbine speed was stabilized at 5800r / min, the output power was 112kW, and the output DC PWM rectifier voltage was 700V. The simulation results are shown in the figure below. Figure 6 :

[0104] As can be seen, when the load power increased by 7kW at the 8th second, the gas turbine output speed dropped from 5800 rpm to 5564 rpm, with a speed fluctuation range of nearly 236 rpm, and it took a long time to stabilize at 5800 rpm. After the speed feedforward compensation algorithm was added, the load power increased by another 7kW at the 69th second, and the speed dropped to 5655 rpm, with a fluctuation of 145 rpm, a 38% reduction compared to the previous fluctuation.

[0105] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for suppressing speed fluctuation of a gas turbine generator set, characterized in that: include: Real-time measurement of key parameters of synchronous generators; The key parameters include the actual speed ω m and the flux linkage angle θ e ; Perform speed feedforward compensation control to obtain the voltage control deviation ΔU and put it into the voltage control link; The speed feedforward compensation control includes: Calculate the actual speed ω m and target speed The gap Δω: The voltage control deviation ΔU is obtained after PI compensation adjustment; The voltage control link includes: When the actual speed exceeds the limit, ΔU<0, when the actual speed decreases, ΔU>0; Get voltage control parameters in, The target voltage value of the PWM rectifier control output; Performing coordinate changes on the output current value of the synchronous generator to form an actual value of a control signal; Performing current feedback control in combination with the voltage control parameters obtained by the speed feedforward compensation control; The speed feedforward compensation control further includes: After obtaining the voltage control parameter U * Then, the voltage control parameter U * and load real-time voltage U dc The difference U after comparison * -U dc After PI compensation adjustment, the q-axis current control target value is obtained The current value i detected by the sensor a 、i b After coordinate transformation, the direct axis current i is obtained d and the quadrature axis current i q ; The direct axis current i d and the quadrature axis current i q Respectively with the target current value and current control target value Make the difference and get the difference as Δi d and Δi q ; The current difference is input into the current PI regulator to obtain the reference output voltage which is converted into the input voltage of the SVPWM module through coordinate transformation; Speed ​​regulation is achieved through space vector PWM control.

2. The method for suppressing speed fluctuation of a gas turbine generator set according to claim 1, wherein: The current feedback control includes: The current value i detected by the sensor a 、i b After Clark transformation and Park transformation, the direct axis current i is obtained d and the quadrature axis current i q ; Then compare with the target current value and the current control target value Make a comparison.

3. The method for suppressing speed fluctuation of a gas turbine generator set according to claim 2, wherein: The current feedback control further includes: The Δi d and Δi q As the input of the current PI regulator, the reference output voltage is obtained and The input U of the SVPWM module is transformed by the Park transformation. d and U q .

4. The method for suppressing speed fluctuation of a gas turbine generator set according to claim 3, wherein: The space vector PWM control is as follows: the pulse signal generated by the PWM module controls the switch closing time of the three-phase inverter, adjusts the input current, and completes the speed regulation.

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