Oscillation suppression method for thermal power unit and gas turbine unit based on station communication

Abstract

The application provides a kind of oscillation suppression control method of thermal power generating unit and gas turbine unit based on plant communication, it is related to electric power system control field, it aims at solving how to suppress the oscillation between thermal power generating unit and gas turbine unit.The oscillation suppression method provided by the present application is implemented by unit internal calculation module, plant communication module and controller control module for this purpose.The method specifically includes that frequency measuring device in the unit real-time acquires the port frequency of each generator and calculates the frequency disturbance of the unit port;Network terminal acquires the frequency disturbance of each unit, calls unit data, calculates and sends the control input instruction of each unit;Each unit controller receives input instruction and calculates, outputs according to respective controller model, and is compensated to the excitation regulation system of each generator.Based on the above structure, the method provided by the present application can effectively suppress the oscillation between each unit, so as to solve the above problem.

Description

Technical Field

[0001] This invention relates to the field of power system control, and more specifically to a method for oscillation suppression of thermal power units and gas turbine units based on plant communication. Background Technology

[0002] With the large-scale integration of renewable energy, the energy structure of new power systems is transforming. Simultaneously, the volatility and randomness of renewable energy significantly increase the demand for flexibility resources in power systems. Gas turbines, with their superior performance in rapid start-up and deep peak shaving, provide support for the flexible regulation of new power systems. However, when system disturbances occur, due to the significant difference in response rates between gas turbines and traditional thermal power units, the system will experience substantial oscillations, potentially leading to system instability. Summary of the Invention

[0003] To address the aforementioned problems in the prior art, specifically how to suppress oscillations between thermal power units and gas turbine units, this invention proposes an oscillation suppression method for thermal power units and gas turbine units based on plant communication. First, the average frequencies of the output ports of the thermal power unit and the internal combustion engine unit are obtained, and then the frequency disturbance of each port is calculated. Second, the mutual frequency disturbances are obtained through the plant communication network, and the difference between the two disturbances is used as the input to the control system. Then, the parameters of the active disturbance rejection controller are selected based on the system model of the thermal power unit and the gas turbine unit. Finally, the controller output is introduced as a voltage deviation into the voltage control of each excitation regulation system.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0005] A method for oscillation suppression control of thermal power units and gas turbine units based on plant communication, wherein the thermal power unit includes multiple sub-units, the gas turbine unit includes multiple sub-units, each sub-unit is equipped with a controller, and each sub-unit includes one or more generators;

[0006] The method includes the following steps:

[0007] Step 1: Obtain the average frequency of each sub-unit output port in the thermal power unit and internal combustion engine unit, and calculate the frequency disturbance of each sub-unit output port.

[0008] Step 2: Obtain the frequency disturbance of each sub-unit's output port through the plant communication network, and calculate the difference between the frequency disturbance of each sub-unit and other sub-units as the input of their respective controllers;

[0009] Step 3: Select controller parameters based on the system model of the thermal power unit and the gas turbine unit;

[0010] Step 4: Introduce the controller output as voltage deviation into the voltage control of the excitation regulation system of each sub-unit.

[0011] Furthermore, step 1 includes:

[0012] 1) The frequency of the generators of each sub-unit is collected by a measuring device, and the average frequency of the output port of each sub-unit is calculated. Each generator is controlled by its own speed governor. The average frequency of the output port of each sub-unit is expressed as:

[0013]

[0014] The meanings of the parameters in formula (1.1) are as follows:

[0015] w gi Let w be the average frequency of the output port of the i-th sub-unit. gij Let n be the output frequency of the j-th generator of the i-th unit. i Let i be the number of generators inside the i-th unit;

[0016] 2) Calculate the frequency disturbance at the output port of each sub-unit. The expression is as follows:

[0017]

[0018] The parameters in formula (1.2) have the following meanings:

[0019] Δw gi Let be the frequency disturbance at the output port of the i-th sub-unit. This is the frequency reference value for the i-th sub-unit.

[0020] Furthermore, step 2 includes:

[0021] The frequency disturbance values ​​at the output ports of each sub-unit calculated in step 1 are transmitted without delay through the plant communication network. The difference between the frequency disturbance values ​​of each sub-unit and those of other sub-units is calculated, and its expression is as follows:

[0022]

[0023] The parameters in formula (1.3) have the following meanings:

[0024] Δw ek S is the difference in frequency disturbance between the k-th unit and the other m-1 units. n and S k These represent the total capacity of the nth and kth generating units, respectively.

[0025] Furthermore, in step 3, the controller is selected from a first-order active disturbance rejection controller, a second-order active disturbance rejection controller, a PI controller, or an improved controller thereof.

[0026] Furthermore, in step 4, when the parameters of each generator in the sub-unit are the same or similar, the same controller output is selected.

[0027] Furthermore, the present invention is not limited to the number of thermal power units and gas turbine units and the number of generators inside them, nor is it limited to the internal structure and control method of the units.

[0028] The method proposed in this invention can effectively suppress oscillations between units, thereby solving the above-mentioned problems. Attached Figure Description

[0029] Figure 1 This is a simplified block diagram of the oscillation suppression strategy based on plant communication in an embodiment of the present invention;

[0030] Figure 2 This is a block diagram of a typical first-order active disturbance rejection controller used in the embodiments of the present invention;

[0031] Figure 3 This is a simplified simulation model covering thermal power units and gas turbine units in an embodiment of the present invention;

[0032] Figure 4 This is a frequency simulation waveform diagram of an embodiment of the present invention without implementing the oscillation suppression method;

[0033] Figure 5 This is a frequency simulation waveform diagram of the oscillation suppression method implemented in an embodiment of the present invention. Detailed Implementation

[0034] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0035] The following description, in conjunction with the accompanying drawings, illustrates a method for suppressing oscillations in thermal power units and gas turbine units based on plant communication, provided by the present invention. The thermal power unit comprises multiple sub-units, and the gas turbine unit comprises multiple sub-units. Each sub-unit is equipped with a corresponding controller, and each sub-unit includes one or more generators.

[0036] Figure 1 A simplified block diagram of an oscillation suppression strategy based on plant communication is shown as an example in this embodiment. Figure 1 As shown, the suppression strategy in this embodiment is mainly implemented through the unit's internal computing module, the plant communication module, and the controller control module.

[0037] Combination Figure 1The present invention discloses a method for suppressing oscillations between thermal power units and gas turbine units based on plant communication. The specific implementation steps are as follows:

[0038] Step 1: Obtain the average frequency of each sub-unit output port in the thermal power unit and internal combustion engine unit, and calculate the frequency disturbance of each port.

[0039] This invention employs a multi-generator parallel operation mode, where each generator is controlled by its own speed governor. The frequency of each generator is collected using a measuring device, and the average frequency at each generator's port is calculated as follows:

[0040]

[0041] The meanings of the parameters in formula (1.1) are as follows:

[0042] w gi Let w be the average frequency of the port of the i-th sub-unit. gij Let n be the output frequency of the j-th generator in the i-th sub-unit. i Let represent the number of generators inside the i-th subunit.

[0043] Furthermore, the frequency disturbance at each sub-unit port is obtained, and its numerical expression is as follows:

[0044]

[0045] The parameters in formula (1.2) have the following meanings:

[0046] Δw gi Let be the frequency disturbance at the port of the i-th unit. This is the frequency reference value for the i-th unit.

[0047] Specifically, in this embodiment, each sub-unit within the generator set is equipped with a frequency measurement device, which collects the port frequency of each generator in real time. Each sub-unit calculates the frequency disturbance Δw at its port using formulas (1.1) and (1.2). gi Each sub-unit transmits the frequency disturbance Δw via the plant communication system. gi The data is uploaded to the plant's network terminal for further calculations.

[0048] Step 2: Obtain the frequency disturbance of each sub-unit's output port through the plant communication network, and calculate the difference between the frequency disturbance of each sub-unit and other sub-units as the input of their respective controllers;

[0049] The sub-units described in this invention are all located within a single plant or are close to each other, and the data communication delay between each sub-unit is negligible.

[0050] Based on the frequency disturbance values ​​of each sub-unit port calculated in step 1, delay-free data transmission is performed through the communication network, and the difference between the frequency disturbance values ​​of each sub-unit and other sub-units is calculated. The value is as follows:

[0051]

[0052] The parameters in formula (1.3) have the following meanings:

[0053] Δw ek S is the difference in frequency disturbance between the k-th unit and the other m-1 units. k and S k These represent the total capacity of the nth and kth generating units, respectively.

[0054] Specifically, in this embodiment, the network terminal collects the frequency disturbance Δw of each sub-unit. gi It then calls up the unit data and calculates the control input command Δw for each sub-unit using formula (1.3). ek The network terminal sends the instruction to the controller of each sub-unit via communication.

[0055] Step 3: Using a first-order active disturbance rejection controller as the controller, select the active disturbance rejection controller parameters based on the system model of the thermal power unit and the gas turbine unit.

[0056] Based on the system model, the nonlinear uncertain object under unknown disturbances is defined as follows:

[0057]

[0058] The parameters in formula (1.4) have the following meanings:

[0059] is an unknown function; w(t) is an unknown external disturbance; x(t) is the measurement input; u is the controller output; b is the controller output coefficient.

[0060] Furthermore, the controller model can be written as:

[0061]

[0062] The parameters in formula (1.5) have the following meanings:

[0063] R t α0, δ, β1, α1, δ1, β2, β3, α2, and δ2 are all parameters of the active disturbance rejection controller. They can be tuned separately according to different control models. 11 z 21 z 22 ε, ε1, and u0 are all intermediate variables. The expression for the nonlinear function fal is:

[0064]

[0065] In this embodiment, each sub-unit controller receives input commands and performs calculations and outputs according to its respective controller model. For example... Figure 2 The first-order active disturbance rejection controller shown in the diagram receives the network terminal's command as input to the controller's input terminal, x(t). The voltage bias command V is obtained through the controller's output. offset That is, u(t).

[0066] Step 4: Introduce the controller output as a voltage deviation into the voltage control of each excitation regulation system. Specifically, use the controller output u(t) obtained in Step 3 as the voltage bias V in the excitation regulation system. offset This is corrected, thus achieving voltage compensation. When the parameters of each generator in the unit are the same or similar, the same controller output u(t) can be selected to reduce economic costs, i.e., as shown below. Figure 1 It is sent directly to each unit.

[0067] The present invention employs both traditional excitation regulation system voltage control strategies for thermal power units and gas turbine units, but is not limited to traditional control strategies.

[0068] Furthermore, the present invention provides the following two optional technical solutions:

[0069] Option 1: The controller is not limited to a first-order active disturbance rejection controller, but also includes: a second-order active disturbance rejection controller, a PI controller and its improved controllers, etc.

[0070] Option 2: The system is not limited to the control strategy between two units, a thermal power unit and an internal combustion engine unit, but also includes the control strategy between multiple units.

[0071] The following description, in conjunction with the accompanying drawings, details this embodiment. Figure 3 The plant and its simulation results are explained.

[0072] See appendix Figure 3 This embodiment uses Huaneng Taicang Power Plant and its surrounding power grid as an example for illustration. This embodiment includes the external main grid, Xiangtang and Jiuqu load areas, and Huaneng Taicang Power Plant, wherein the power plant contains 14 18MW gas turbine units and 2 320MW thermal power units.

[0073] This embodiment describes the gas turbine unit and the thermal power unit as two units in the plant, and each generator adopts the traditional excitation and control method. Figure 4 and Figure 5 The simulation results of the above system using MATLAB software are shown as an example. See Appendix. Figure 4At 20s, when the external load changes abruptly and the power plant does not adopt the oscillation suppression strategy described in this invention, both the primary and secondary frequency regulation of the system will be activated. However, due to the large difference in response rates between the two types of units, the power distribution is difficult to balance quickly. At this time, large oscillations will occur between the units, especially the thermal power units with slower response, which will produce more intense oscillations and easily cause equipment damage.

[0074] Please refer to the appendix for further details. Figure 5 , same as attached Figure 4 Similarly, at 20 seconds, the external load experiences a similar sudden change, and the power plant already has the oscillation suppression strategy described in this invention. It can be seen that the oscillations between units have been largely suppressed, and the frequency changes almost smoothly.

[0075] Although the steps in the above embodiments are described in the above order, those skilled in the art will understand that in order to achieve the effect of this embodiment, different steps do not need to be executed in such an order. They can be executed simultaneously (in parallel) or in a reverse order. These simple variations are all within the protection scope of this invention.

[0076] Those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims of this invention, any of the claimed embodiments can be used in any combination.

[0077] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, the word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed PC.

[0078] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for oscillation suppression control of thermal power units and gas turbine units based on plant communication, characterized in that, The thermal power unit includes multiple sub-units, the gas turbine unit includes multiple sub-units, each sub-unit is equipped with a controller, and each sub-unit includes one or more generators. The method includes the following steps: Step 1: Obtain the average frequency of each sub-unit output port in the thermal power unit and internal combustion engine unit, and calculate the frequency disturbance of each sub-unit output port. Step 2: Obtain the frequency disturbance of each sub-unit's output port through the plant communication network, and calculate the difference between the frequency disturbance of each sub-unit and other sub-units as the input of each controller; Step 3: Select controller parameters based on the system model of the thermal power unit and the gas turbine unit; Step 4: Introduce the controller output as voltage deviation into the voltage control of the excitation regulation system of each sub-unit.

2. The oscillation suppression control method for thermal power units and gas turbine units based on plant communication as described in claim 1, characterized in that, Step 1 includes: 1) Collect the frequency of the generators of each sub-unit using a measuring device, and calculate the average frequency of the output port of each sub-unit; wherein, each generator is controlled by its own speed governor, and the average frequency of the output port of each sub-unit is expressed as: The meanings of the parameters in formula (1.1) are as follows: ω gi Let ω be the average frequency of the output port of the i-th sub-unit. gij Let n be the output frequency of the j-th generator of the i-th unit. i Let i be the number of generators inside the i-th unit; 2) Calculate the frequency disturbance at the output port of each sub-unit. The expression is as follows: The parameters in formula (1.2) have the following meanings: Δω gi Let be the frequency disturbance at the output port of the i-th sub-unit. This is the frequency reference value for the i-th sub-unit.

3. The oscillation suppression control method for thermal power units and gas turbine units based on plant communication as described in claim 2, characterized in that, Step 2 includes: The frequency disturbance values ​​at the output ports of each sub-unit calculated in step 1 are transmitted without delay through the plant communication network. The difference between the frequency disturbance values ​​of each sub-unit and those of other sub-units is calculated, and its expression is as follows: The parameters in formula (1.3) have the following meanings: Δω ek S is the difference in frequency disturbance between the k-th unit and the other m-1 units. n and S k These represent the total capacity of the nth and kth generating units, respectively.

4. The oscillation suppression control method for thermal power units and gas turbine units based on plant communication as described in claim 1, characterized in that: In step 3, the controller is selected from a first-order active disturbance rejection controller, a second-order active disturbance rejection controller, a PI controller, or an improved controller thereof.

5. The oscillation suppression control method for thermal power units and gas turbine units based on plant communication as described in claim 1, characterized in that: In step 4, when the parameters of each generator in the sub-unit are the same or similar, the same controller output is selected.

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