Method and system for suppressing low frequency oscillations

Abstract

The application provides a method and system for inhibiting low-frequency oscillation, the system comprising: a frequency modulation control loop and an oscillation inhibition loop, an oscillation determination unit in the oscillation inhibition loop being used for determining low-frequency oscillation according to actual unit power output by the frequency modulation control loop and a unit side frequency signal; in response to no low-frequency oscillation, the oscillation determination unit controls a function switching switch to make a network frequency signal act on the frequency modulation control loop after passing through frequency difference functions F1(x) and F2(x); in response to low-frequency oscillation, the oscillation determination unit controls the function switching switch to select a corresponding function according to a low-frequency oscillation intensity level, and processes a unit side frequency signal after passing through the frequency difference functions F1(x) and F2(x) to act on the frequency modulation control loop to realize low-frequency oscillation inhibition. The application solves the problem that source side low-frequency oscillation cannot be monitored and actively prevented on the source side, and greatly avoids the occurrence of low-frequency oscillation accidents.

Description

Technical Field

[0001] This invention relates to the field of generator set frequency control technology, and in particular to a method and system for suppressing low-frequency oscillations. Background Technology

[0002] The large-scale integration of new energy power generation, due to its randomness, intermittency, and volatility, coupled with insufficient peak-shaving capacity of the power system, has led to frequent grid frequency fluctuations. Taking a certain regional power grid as an example, the number of primary frequency regulation actions (i.e., grid frequencies exceeding the dead zone ±2 rpm) in August, September, and October of 20xx were 65, 319, and 164 respectively, an increase of 5-8 times compared to other months year-on-year, and an increase of 8-10 times compared to the same months in previous years. On the other hand, many thermal power units have completed flexibility upgrades and are operating in deep peak-shaving ranges. Due to the change in the operating range of the main and auxiliary equipment of the units under this condition, the rotational inertia of the units is continuously reduced, and the anti-disturbance capability is continuously reduced. The simultaneous action of external or internal disturbances makes the units prone to triggering unit-level forced oscillations, especially low-frequency oscillation accidents of the units occur frequently. The supporting and regulating role of thermal power units is not only not reflected, but also poses a huge hidden danger to system stability, endangering the safe operation of the units and the power grid.

[0003] Low-frequency oscillations in power systems (also known as electromechanical oscillations or power oscillations) refer to the phenomenon where, when a power system is disturbed, the relative swaying of the rotors of parallel-operating synchronous generators causes varying degrees of oscillation in electrical quantities such as power, voltage, and power angle. The frequency of this sustained oscillation is often between 0.2 and 2.5 Hz, hence the name low-frequency oscillation. If the oscillation frequency is between 0.2 and 0.7 Hz, it is called an interval oscillation mode. This mode involves oscillations between two generator groups in different areas, with the oscillation power propagating throughout the system via tie lines. Interval oscillation modes are generally more hazardous. Currently, research on low-frequency oscillations largely focuses on excitation systems and PSS systems, primarily analyzing system modeling and damping characteristics. However, for low-frequency oscillations caused by thermal power units (prime movers), there is still no complete online active solution based on a DCS control system for addressing this problem.

[0004] The problem of low-frequency oscillation on the source side is mainly caused by two factors. One is the external objective factor, which is that due to the connection of a large number of new energy units to the grid, their inherent fluctuation characteristics lead to frequent grid frequency fluctuations. The other is that due to the operating conditions of the unit system and the parameters of the frequency regulation control loop, the large fluctuations in the frequency regulation loop lead to a significant decrease in the stability of the unit side, making it very easy for low-frequency oscillation to occur.

[0005] The typical control logic used in existing unit frequency control is as follows: Figure 1 As shown.

[0006] Figure 1In this process, the AGC command signal and the unit-side frequency (i.e., the grid frequency shown in the diagram) are superimposed using the frequency difference function F1(x) to form the PID control command SP. The actual generated power of the unit serves as the controlled variable of the PID. The PID control output, superimposed with the frequency difference function F2(x), forms the comprehensive flow command, which is applied to the turbine valve control. When the grid frequency is below 49.9667Hz, both the frequency difference functions F1(x) and F2(x) simultaneously apply to the PID load setpoint and the comprehensive flow command, causing the control valve opening to increase, thereby increasing the turbine steam intake and thus increasing the turbine output and the generator's active power. Conversely, when the grid frequency is above 50.033Hz, the valve opening is reduced, decreasing the turbine steam intake and reducing the generator's active power. The unit actively adjusts its output based on the frequency changes on the source side, proactively supporting the stability of the grid frequency.

[0007] However, the existing frequency regulation control strategies for thermal power units lack proactive defense control strategies against low-frequency oscillations caused by reciprocating frequency fluctuations. When low-frequency oscillations are induced by reduced stability of the control system due to large and repeated fluctuations in the external grid frequency and internal system issues, the necessary defense cannot be proactively implemented through the source-side drive end, failing to prevent further amplification of the oscillations, thus leading to a significant decrease in system stability. Summary of the Invention

[0008] In view of this, the present invention provides a method and system for suppressing low-frequency oscillations to solve at least one of the aforementioned problems.

[0009] To achieve the above objectives, the present invention adopts the following solution:

[0010] According to a first aspect of the present invention, an embodiment of the present invention provides a system for suppressing low-frequency oscillations. The system includes: a frequency modulation control loop and an oscillation suppression loop connected together. The oscillation suppression loop includes an oscillation determination unit and a function switching switch. The oscillation determination unit is used to determine low-frequency oscillations based on the actual power of the unit output by the frequency modulation control loop and the unit-side frequency signal. In response to the absence of low-frequency oscillations, the oscillation determination unit controls the function switching switch to apply the unit-side frequency signal to the frequency modulation control loop after passing through frequency difference functions F1(x) and F2(x), so that the frequency modulation control loop operates in its original mode. In response to the occurrence of low-frequency oscillations, the oscillation determination unit controls the function switching switch to select a corresponding function according to the intensity level of the low-frequency oscillations, processes the unit-side frequency signal after passing through the frequency difference functions F1(x) and F2(x), and then applies it to the frequency modulation control loop to achieve low-frequency oscillation suppression.

[0011] Preferably, in the system described above in this embodiment, in response to the occurrence of low-frequency oscillation, the oscillation determination unit is further configured to: determine the intensity level of low-frequency oscillation based on the characteristic quantities of low-frequency oscillation, wherein the characteristic quantities include oscillation amplitude, oscillation period and oscillation duration.

[0012] Preferably, in the system described above in this embodiment, when the load oscillation amplitude is less than 5MW, the oscillation period is greater than 5s, and the duration is less than 10s, the intensity level is determined to be low; when the load oscillation amplitude is greater than 5MW and less than 8MW, the oscillation period is less than 5s and greater than 0.2s, and the duration is greater than 10s and less than 15s, the intensity level is determined to be medium; when the load oscillation amplitude is greater than 8MW, the oscillation period is less than 5s and greater than 0.2s, and the duration is greater than 15s, the intensity level is determined to be high.

[0013] Preferably, in the above system of this embodiment, when the oscillation determination unit determines that the low-frequency oscillation is of low intensity, the oscillation determination unit controls the function switching switch to select the corresponding function according to the low-frequency oscillation intensity level. The low-frequency oscillation suppression is achieved by processing the unit-side frequency signal after passing through the frequency difference functions F1(x) and F2(x) and then applying it to the frequency modulation control loop. This includes: the oscillation determination unit controls the function switching switch to select the suppression function unit; the suppression function unit processes the unit-side frequency signal after passing through the frequency difference functions F1(x) and F2(x) and then applies it to the frequency modulation control loop, so that the starting segment of the frequency modulation action is activated according to the action values ​​of the frequency difference functions F1(x) and F2(x).

[0014] Preferably, in the above system of this embodiment, when the oscillation determination unit determines that the low-frequency oscillation is of medium intensity, the oscillation determination unit controls the function switching switch to select the corresponding function according to the intensity level of the low-frequency oscillation. The low-frequency oscillation suppression is achieved by processing the unit-side frequency signal after passing through the frequency difference functions F1(x) and F2(x) and then applying it to the frequency modulation control loop. This includes: the oscillation determination unit controls the function switching switch to select the forced landing function unit. The forced landing function unit processes the unit-side frequency signal after passing through the frequency difference functions F1(x) and F2(x) and then applies it to the frequency modulation control loop to achieve a significant attenuation of the frequency modulation action amplitude according to the frequency modulation load.

[0015] Preferably, in the above system of this embodiment, when the oscillation determination unit determines that the low-frequency oscillation is of a high intensity level, the oscillation determination unit controls the function switching switch to select the corresponding function according to the intensity level of the low-frequency oscillation. The low-frequency oscillation suppression is achieved by processing the unit-side frequency signal after passing through the frequency difference functions F1(x) and F2(x) and then applying it to the frequency modulation control loop. This includes: the oscillation determination unit controls the function switching switch to select the blocking function unit, and the blocking function unit blocks the unit-side frequency signal from acting on the frequency modulation control loop after passing through the frequency difference functions F1(x) and F2(x), thereby temporarily cutting off the frequency modulation function of the frequency modulation control loop.

[0016] According to a second aspect of the present invention, an embodiment of the present invention provides a method for suppressing low-frequency oscillations. The method includes: determining low-frequency oscillations based on the actual power of the unit output from the frequency modulation control loop and the unit-side frequency signal; in response to the absence of low-frequency oscillations, controlling a function switching switch to apply the unit-side frequency signal to the frequency modulation control loop after passing through frequency difference functions F1(x) and F2(x), so that the frequency modulation control loop operates in its original mode; in response to the occurrence of low-frequency oscillations, controlling the function switching switch to select a corresponding function according to the intensity level of the low-frequency oscillations, processing the unit-side frequency signal after passing through the frequency difference functions F1(x) and F2(x), and then applying it to the frequency modulation control loop to suppress low-frequency oscillations.

[0017] Preferably, in the above steps of this embodiment, in response to the occurrence of low-frequency oscillation, the method further includes: determining the intensity level of low-frequency oscillation based on low-frequency oscillation characteristic quantities, wherein the characteristic quantities include oscillation amplitude, oscillation period and oscillation duration.

[0018] Preferably, in the above steps of this embodiment, when the load oscillation amplitude is less than 5MW, the oscillation period is greater than 5s, and the duration is less than 10s, the intensity level is determined to be low intensity; when the load oscillation amplitude is greater than 5MW and less than 8MW, the oscillation period is less than 5s and greater than 0.2s, and the duration is greater than 10s and less than 15s, the intensity level is determined to be medium intensity; when the load oscillation amplitude is greater than 8MW, the oscillation period is less than 5s and greater than 0.2s, and the duration is greater than 15s, the intensity level is determined to be high intensity.

[0019] Preferably, in the above steps of this embodiment, when the low-frequency oscillation is determined to be of low intensity, the step of selecting the corresponding function according to the low-frequency oscillation intensity level control function switch, and processing the unit-side frequency signal after passing through the frequency difference function F1(x) and F2(x) and then applying it to the frequency modulation control loop to achieve low-frequency oscillation suppression includes: selecting the suppression function unit by the control function switch, and the suppression function unit processing the unit-side frequency signal after passing through the frequency difference function F1(x) and F2(x) and then applying it to the frequency modulation control loop to realize that the starting segment of the frequency modulation action is operated according to the action value of the frequency difference function F1(x) and F2(x).

[0020] Preferably, in the above steps of this embodiment, when the low-frequency oscillation is determined to be of medium intensity, the step of selecting the corresponding function according to the low-frequency oscillation intensity level control function switch, and processing the unit-side frequency signal after passing through the frequency difference function F1(x) and F2(x) and then applying it to the frequency modulation control loop to achieve low-frequency oscillation suppression includes: selecting the forced landing function unit by the control function switch, wherein the forced landing function unit processes the unit-side frequency signal after passing through the frequency difference function F1(x) and F2(x) and then applies it to the frequency modulation control loop to achieve a significant attenuation of the frequency modulation action amplitude according to the frequency modulation load.

[0021] Preferably, in the above steps of this embodiment, when the low-frequency oscillation is determined to be of a high intensity level, the step of selecting the corresponding function according to the low-frequency oscillation intensity level control function switch, and processing the unit-side frequency signal after passing through the frequency difference functions F1(x) and F2(x) and then applying it to the frequency modulation control loop to achieve low-frequency oscillation suppression includes: selecting the blocking function unit by the control function switch, wherein the blocking function unit blocks the unit-side frequency signal from acting on the frequency modulation control loop after passing through the frequency difference functions F1(x) and F2(x), thereby achieving the temporary cut-off function of the frequency modulation control loop.

[0022] According to a third aspect of the present invention, an electronic device is also provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-described method.

[0023] According to a fourth aspect of the present invention, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-described method.

[0024] According to a fifth aspect of the present invention, embodiments of the present invention also provide a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the above-described method.

[0025] The method and system for suppressing low-frequency oscillations proposed in this invention solve the problem that source-side low-frequency oscillations cannot be autonomously monitored and actively defended against, significantly reducing the occurrence of low-frequency oscillation accidents. Simultaneously, it effectively avoids misjudgments that lead to a decline in frequency regulation performance, which is of great significance for improving the safety and performance of unit frequency regulation. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0027] Figure 1 This is a typical control logic diagram for existing unit frequency control;

[0028] Figure 2 This is a schematic diagram of a system structure for suppressing low-frequency oscillations provided in an embodiment of this application;

[0029] Figure 3 It is a comparison curve of the unit's low-frequency oscillation and the trigger suppression function;

[0030] Figure 4 It is a comparison curve of the unit's low-frequency oscillation and the triggering of the emergency landing function;

[0031] Figure 5 It is a comparison curve of the unit's low-frequency oscillation and the triggering of the blocking function;

[0032] Figure 6 This is a flowchart illustrating a method for suppressing low-frequency oscillations provided in an embodiment of this application;

[0033] Figure 7 This is a flowchart illustrating a method for suppressing low-frequency oscillations according to another embodiment of this application;

[0034] Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0036] like Figure 2The diagram shown is a schematic representation of a system structure for suppressing low-frequency oscillations according to an embodiment of this application. The system includes a frequency modulation control loop 100 and an oscillation suppression loop, which are connected together. Figure 2 As can be seen, the oscillation suppression circuit of this application includes an oscillation determination unit 200, function switching switches S1 and S2, and a functional unit 300.

[0037] Among them, the frequency modulation control loop 100 and the existing technology Figure 1 The difference is that the frequency input of the two summing units in the control loop 100 is controlled by the oscillation suppression loop.

[0038] The oscillation determination unit 200 is used to determine the oscillation based on the actual power output of the unit from the frequency modulation control loop and the unit-side frequency signal (i.e., Figure 2 The low-frequency oscillation is determined by using the network frequency in the network, that is, to determine whether low-frequency oscillation has occurred.

[0039] When the oscillation determination unit 200 determines that no low-frequency oscillation has occurred, it controls the function switching switches S1 and S2, causing the unit-side frequency signal to act on the frequency modulation control loop 100 after passing through the frequency difference functions F1(x) and F2(x), indicating that... Figure 2 In the middle, function switching switches S1 and S2 can be switched to side 1, which means that the frequency modulation control circuit 100 can operate in the original working mode.

[0040] When the oscillation determination unit 200 determines that a low-frequency oscillation has occurred, the oscillation determination unit 200 will select the corresponding function in the function unit 300 according to the low-frequency oscillation intensity level control function switching switches S1 and S2, and then process the unit-side frequency signal after passing through the frequency difference function F1(x) and F2(x) and apply it to the frequency modulation control loop 100 to achieve low-frequency oscillation suppression.

[0041] Preferably, as an embodiment of the present invention, when the oscillation determination unit 200 determines that a low-frequency oscillation has occurred, it can further determine the intensity level of the low-frequency oscillation based on the characteristic quantities of the low-frequency oscillation, which may include the oscillation amplitude, oscillation period, and oscillation duration.

[0042] Preferably, the aforementioned low-frequency oscillation intensity levels can include three levels: low, medium, and high. Specifically, when the load oscillation amplitude is less than 5 MW, the oscillation period is greater than 5 s, and the duration is less than 10 s, the oscillation determination unit 200 determines the intensity level as low (safe level); when the load oscillation amplitude is greater than 5 MW and less than 8 MW, the oscillation period is less than 5 s and greater than 0.2 s, and the duration is greater than 10 s and less than 15 s, the oscillation determination unit 200 determines the intensity level as medium (dangerous level); when the load oscillation amplitude is greater than 8 MW, the oscillation period is less than 5 s and greater than 0.2 s, and the duration is greater than 15 s, the oscillation determination unit 200 determines the intensity level as high (extremely dangerous level).

[0043] Preferably, when the oscillation determination unit 200 determines that the low-frequency oscillation is of low intensity, the oscillation determination unit 200 will control the function switching switches S1 and S2 to switch them to the two sides, and switch them to the suppression function unit in the function unit 300. The suppression function unit will process the unit-side frequency signal through the frequency difference function F1(x) and F2(x) and then apply it to the frequency modulation control loop, so that the starting segment of the frequency modulation action of the frequency modulation control loop 100 will act according to the action value of the frequency difference function F1(x) and F2(x).

[0044] For example, the F1(x) settings of a certain factory are as follows: Table 1

[0045] Table 1

[0046] Slippage (rpm) -10.1 -4 -2.2 -2 2 2.1 4 10.1 Load (MW) -59.256 -15.7769 -1.03698 0 0 1.11105 15.92505 59.256

[0047] When the safety level is determined, assuming the current slip is -4 rpm (0.0667 Hz), the initial setting of the suppression action will be -15.7769 MW. After the slip reaches -4 rpm, it will not immediately change from -15.7769 MW to 0, but will change to 0 at a certain rate. The same action applies to F2(x).

[0048] Preferably, when the oscillation determination unit 200 determines that the low-frequency oscillation is of medium intensity, the oscillation determination unit 200 will control the function switching switches S1 and S2 to switch them to the 3rd side, so that they are switched to the forced landing function unit in the function unit 300. The forced landing function unit will process the unit-side frequency signal through the frequency difference function F1(x) and F2(x) and then apply it to the frequency modulation control loop, thereby realizing the function of significantly attenuating the frequency modulation action amplitude according to the frequency modulation load.

[0049] When the safety level is determined, assuming the current slip is -4 rpm (0.0667 Hz), the initial stage of the forced landing process will be directly set to -15.7769 × coefficient (the coefficient is much less than 1), and the action amplitude will be greatly reduced. A similar action will occur for F2(x).

[0050] Preferably, when the oscillation determination unit 200 determines that the low-frequency oscillation is of high intensity, the oscillation determination unit 200 will control the function switching switches S1 and S2 to switch them to the 4th side, and switch them to the blocking function unit in the function unit 300. The blocking function unit will block the generator side frequency signal from acting on the frequency modulation control loop after passing through the frequency difference functions F1(x) and F2(x), thereby realizing the temporary cut-off function of the frequency modulation control loop.

[0051] The beneficial effects of the technical solution of this application will be illustrated below through several specific embodiments, taking the low-frequency oscillation phenomenon of a 350MW supercritical unit as an example. Figure 3 This is a comparison curve of the unit's low-frequency oscillation and the effect of trigger suppression function. Figure 4 This is a comparison graph showing the low-frequency oscillation of the generator unit and the triggering of the emergency landing function. Figure 5 It is a comparison curve of the unit's low-frequency oscillation and the triggering of the blocking function.

[0052] Depend on Figure 3 It can be seen that when the low-frequency oscillation forced landing function is not activated, the oscillation amplitude of the unit reaches 212.5MW-205.4MW, with a range of 8MW between the maximum and minimum values. After the low-frequency oscillation forced landing function is activated, the load oscillation load drops rapidly to between 209MW-210MW, with a range of less than 1MW between the maximum and minimum values, and no periodic fluctuations are observed.

[0053] Depend on Figure 4 It can be seen that when the low-frequency oscillation forced landing function is not activated, the oscillation amplitude of the unit reaches 212.5MW-205.4MW, with a range of 8MW between the maximum and minimum values. After the low-frequency oscillation forced landing function is activated, the load oscillation load drops rapidly to between 209MW-210MW, with a range of less than 1MW between the maximum and minimum values, and no periodic fluctuations are observed.

[0054] Depend on Figure 5 It can be seen that when the low-frequency oscillation forced landing function is not activated, the oscillation amplitude of the unit reaches 212.5MW-205.4MW, with a range of 8MW between the maximum and minimum values. After the low-frequency oscillation forced landing function is activated, the load oscillation load drops rapidly to between 209MW-210MW, with a range of less than 1MW between the maximum and minimum values, and no periodic fluctuations are observed.

[0055] Therefore, in summary, the system for suppressing low-frequency oscillations provided in this application solves the problem that source-side low-frequency oscillations cannot be autonomously monitored and actively defended against, significantly reducing the occurrence of low-frequency oscillation accidents. Simultaneously, it effectively avoids the degradation of frequency modulation performance caused by misjudgments. Without a three-stage suppression method, the frequency modulation loop would have to be cut off upon each misjudgment, which would compromise frequency modulation performance. Therefore, the three-stage suppression method of this application is of great significance for the safety and performance improvement of unit frequency modulation.

[0056] like Figure 6 The diagram shown is a flowchart illustrating a method for suppressing low-frequency oscillations according to an embodiment of this application. The method includes the following steps:

[0057] Step S601: Determine low-frequency oscillation based on the actual power output of the unit from the frequency modulation control loop and the unit-side frequency signal. If no low-frequency oscillation occurs, proceed to step S602; otherwise, proceed to step S603.

[0058] Step S602: The control function switching switch causes the unit-side frequency signal to act on the frequency modulation control loop after passing through the frequency difference functions F1(x) and F2(x), so that the frequency modulation control loop operates in the original working mode.

[0059] Step S603: Select the corresponding function by controlling the function switching switch according to the low-frequency oscillation intensity level, process the unit-side frequency signal after passing through the frequency difference function F1(x) and F2(x), and then apply it to the frequency modulation control loop to achieve low-frequency oscillation suppression.

[0060] As described above, the method for suppressing low-frequency oscillations provided in this application solves the problem that source-side low-frequency oscillations cannot be autonomously monitored and actively defended against, significantly reducing the occurrence of low-frequency oscillation accidents. Simultaneously, it effectively avoids misjudgments that could lead to a decline in frequency regulation performance, which is of great significance for improving the frequency regulation safety and performance of the generating unit.

[0061] like Figure 7 The diagram shown is a flowchart illustrating a method for suppressing low-frequency oscillations according to another embodiment of this application. The method includes the following steps:

[0062] Step S701: Determine low-frequency oscillation based on the actual power output of the unit from the frequency control loop and the unit-side frequency signal. If no low-frequency oscillation occurs, proceed to step S702; otherwise, proceed to step S703.

[0063] Step S702: The control function switching switch causes the unit-side frequency signal to act on the frequency modulation control loop after passing through the frequency difference functions F1(x) and F2(x), so that the frequency modulation control loop operates in the original working mode.

[0064] Step S703: Determine the intensity level of low-frequency oscillation based on its characteristic quantities, including oscillation amplitude, oscillation period, and oscillation duration. If the low-frequency oscillation is of low intensity, proceed to step S704; if it is of medium intensity, proceed to step S705; if it is of high intensity, proceed to step S706.

[0065] Specifically, when the load oscillation amplitude is less than 5 MW, the oscillation period is greater than 5 s, and the duration is less than 10 s, the intensity level is determined to be low; when the load oscillation amplitude is greater than 5 MW and less than 8 MW, the oscillation period is less than 5 s and greater than 0.2 s, and the duration is greater than 10 s and less than 15 s, the intensity level is determined to be medium; when the load oscillation amplitude is greater than 8 MW, the oscillation period is less than 5 s and greater than 0.2 s, and the duration is greater than 15 s, the intensity level is determined to be high.

[0066] Step S704: Select the suppression function unit by switching the control function. The suppression function unit processes the unit-side frequency signal through the frequency difference function F1(x) and F2(x) and then applies it to the frequency modulation control loop to realize that the starting segment of the frequency modulation action is based on the action value of the frequency difference function F1(x) and F2(x).

[0067] Step S705: Select the forced landing function unit by the control function switching switch. The forced landing function unit processes the unit-side frequency signal through the frequency difference function F1(x) and F2(x) and then applies it to the frequency modulation control loop to realize the function of significantly attenuating the frequency modulation action amplitude according to the frequency modulation load.

[0068] Step S706: The control function switching switch selects the blocking function unit. The blocking function unit blocks the frequency signal on the unit side from acting on the frequency modulation control loop after passing through the frequency difference functions F1(x) and F2(x), thereby realizing the temporary cut-off function of the frequency modulation control loop.

[0069] In summary, the method for suppressing low-frequency oscillations provided in this application solves the problem that source-side low-frequency oscillations cannot be autonomously monitored and actively defended against, significantly reducing the occurrence of low-frequency oscillation accidents. Simultaneously, it effectively avoids misjudgments that could lead to a decline in frequency regulation performance, which is of great significance for improving the safety and performance of unit frequency regulation.

[0070] Figure 8 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. Figure 8The illustrated electronic device is a general-purpose data processing apparatus, comprising a general-purpose computer hardware structure, including at least a processor 801 and a memory 802. The processor 801 and memory 802 are connected via a bus 803. The memory 802 is adapted to store one or more instructions or programs executable by the processor 801. These instructions or programs are executed by the processor 801 to implement the steps in the aforementioned method for suppressing low-frequency oscillations.

[0071] The processor 801 described above can be a standalone microprocessor or a collection of one or more microprocessors. Thus, the processor 801 executes commands stored in the memory 802, thereby performing the method flow of the embodiments of the present invention as described above to process data and control other devices. The bus 803 connects the aforementioned components together, and also connects these components to the display controller 804, the display device, and the input / output (I / O) device 805. The input / output (I / O) device 805 can be a mouse, keyboard, modem, network interface, touch input device, motion-sensing input device, printer, and other devices known in the art. Typically, the input / output (I / O) device 805 is connected to the system via an input / output (I / O) controller 806.

[0072] The memory 802 can store software components, such as an operating system, a communication module, an interaction module, and application programs. Each of the modules and application programs described above corresponds to a set of executable program instructions that perform one or more functions and the methods described in the embodiments of the invention.

[0073] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method for suppressing low-frequency oscillations described above.

[0074] This invention also provides a computer program product, including a computer program / instruction that, when executed by a processor, implements the steps of the method for suppressing low-frequency oscillations described above.

[0075] In summary, the method and apparatus for suppressing low-frequency oscillations proposed in this invention solve the problem of the inability to achieve autonomous monitoring and active defense against low-frequency oscillations at the source side, significantly reducing the occurrence of low-frequency oscillation accidents. Simultaneously, it effectively avoids the degradation of frequency regulation performance due to misjudgments, which is of great significance for the safety and performance improvement of unit frequency regulation.

[0076] Preferred embodiments of the invention have been described above with reference to the accompanying drawings. Many features and advantages of these embodiments are apparent from this detailed description, and therefore the claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since many modifications and alterations will readily occur to those skilled in the art, the embodiments of the invention are not intended to be limited to the precise structures and operations illustrated and described, but rather to encompass all suitable modifications and equivalents falling within their scope.

[0077] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0078] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0079] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0080] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0081] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for suppressing low-frequency oscillations, characterized in that, The system includes a frequency modulation control loop and an oscillation suppression loop, the frequency modulation control loop and the oscillation suppression loop being connected together. The oscillation suppression loop includes an oscillation determination unit and a function switching switch. The oscillation determination unit is used to determine low-frequency oscillations based on the actual power output of the unit from the frequency control loop and the unit-side frequency signal, and to determine the intensity level of low-frequency oscillations based on the characteristic quantities of low-frequency oscillations. When the load oscillation amplitude is less than 5MW, the oscillation period is greater than 5s, and the duration is less than 10s, the intensity level is determined to be low. When the load oscillation amplitude is greater than 5MW and less than 8MW, the oscillation period is less than 5s and greater than 0.2s, and the duration is greater than 10s and less than 15s, the intensity level is determined to be medium. When the load oscillation amplitude is greater than 8MW, the oscillation period is less than 5s and greater than 0.2s, and the duration is greater than 15s, the intensity level is determined to be high. In response to the absence of low-frequency oscillation, the oscillation determination unit controls the function switching switch to cause the unit-side frequency signal to pass through the frequency difference function. and It then acts on the frequency modulation control loop, causing the frequency modulation control loop to operate in its original mode. In response to the occurrence of low-frequency oscillations, the oscillation determination unit controls the function switching switch to select the corresponding function based on the intensity level of the low-frequency oscillations, and performs a frequency difference function. and The unit-side frequency signal is processed and then applied to the frequency modulation control loop to suppress low-frequency oscillations.

2. The system for suppressing low-frequency oscillations as described in claim 1, characterized in that, When the oscillation determination unit determines that the low-frequency oscillation is of low intensity, the oscillation determination unit controls the function switching switch to select the corresponding function based on the intensity level of the low-frequency oscillation, and performs a frequency difference function. and The processed unit-side frequency signal is then applied to the frequency modulation control loop to suppress low-frequency oscillations, including: The oscillation determination unit controls the function switch to select the suppression function unit, and the suppression function unit controls the frequency difference function. and The unit-side frequency signal is processed and applied to the frequency modulation control loop to achieve the initial stage of frequency modulation based on the frequency difference function. and The action value is used to perform the action.

3. The system for suppressing low-frequency oscillations as described in claim 1, characterized in that, When the oscillation determination unit determines that the low-frequency oscillation is of medium intensity, the oscillation determination unit controls the function switching switch to select the corresponding function based on the intensity level of the low-frequency oscillation, and performs a frequency difference function. and The processed unit-side frequency signal is then applied to the frequency modulation control loop to suppress low-frequency oscillations, including: The oscillation determination unit controls the function switching switch to select the forced landing function unit, and the forced landing function unit uses the frequency difference function. and The unit-side frequency signal is processed and applied to the frequency modulation control loop to achieve a significant attenuation of the frequency modulation amplitude according to the frequency modulation load.

4. The system for suppressing low-frequency oscillations as described in claim 1, characterized in that, When the oscillation determination unit determines that the low-frequency oscillation is of high intensity, the oscillation determination unit controls the function switching switch to select the corresponding function based on the intensity level of the low-frequency oscillation, and performs a frequency difference function. and The processed unit-side frequency signal is then applied to the frequency modulation control loop to suppress low-frequency oscillations, including: The oscillation determination unit controls the function switching switch to select the blocking function unit, which blocks the unit-side frequency signal from passing through the frequency difference function. and It then acts on the frequency modulation control loop to temporarily cut off the frequency modulation function of the frequency modulation control loop.

5. A method for suppressing low-frequency oscillations, characterized in that, The method includes: Low-frequency oscillation is determined based on the actual power output of the unit from the frequency modulation control loop and the frequency signal on the unit side. The intensity level of low-frequency oscillations is determined based on the characteristic quantities of low-frequency oscillations. When the load oscillation amplitude is less than 5 MW, the oscillation period is greater than 5 s, and the duration is less than 10 s, the intensity level is determined to be low. When the load oscillation amplitude is greater than 5 MW and less than 8 MW, the oscillation period is less than 5 s and greater than 0.2 s, and the duration is greater than 10 s and less than 15 s, the intensity level is determined to be medium. When the load oscillation amplitude is greater than 8 MW, the oscillation period is less than 5 s and greater than 0.2 s, and the duration is greater than 15 s, the intensity level is determined to be high. In response to the absence of low-frequency oscillation, the control function switching switch causes the unit-side frequency signal to pass through the frequency difference function. and It then acts on the frequency modulation control loop, causing the frequency modulation control loop to operate in its original mode. In response to the occurrence of low-frequency oscillations, the function switching switch is controlled to select the corresponding function based on the intensity level of the low-frequency oscillations, and the frequency difference function is applied. and The unit-side frequency signal is processed and then applied to the frequency modulation control loop to suppress low-frequency oscillations.

6. The method for suppressing low-frequency oscillations as described in claim 5, characterized in that, When the low-frequency oscillation is determined to be of low intensity, the corresponding function is selected by the low-frequency oscillation intensity level control switch, and the frequency difference function is applied. and The processed unit-side frequency signal is then applied to the frequency modulation control loop to suppress low-frequency oscillations, including: The control function switch selects the suppression function unit, which controls the frequency difference function. and The unit-side frequency signal is processed and applied to the frequency modulation control loop to achieve the initial stage of frequency modulation based on the frequency difference function. and The action value is used to perform the action.

7. The method for suppressing low-frequency oscillations as described in claim 5, characterized in that, When the low-frequency oscillation is determined to be of medium intensity, the corresponding function is selected by the low-frequency oscillation intensity level control switch, and the frequency difference function is applied. and The processed unit-side frequency signal is then applied to the frequency modulation control loop to suppress low-frequency oscillations, including: The control function switch selects the forced landing function unit, which is related to the frequency difference function. and The unit-side frequency signal is processed and applied to the frequency modulation control loop to achieve a significant attenuation of the frequency modulation amplitude according to the frequency modulation load.

8. The method for suppressing low-frequency oscillations as described in claim 5, characterized in that, When the low-frequency oscillation is determined to be of high intensity, the corresponding function is selected by the low-frequency oscillation intensity level control switch, and the frequency difference function is applied. and The processed unit-side frequency signal is then applied to the frequency modulation control loop to suppress low-frequency oscillations, including: The control function switch selects the blocking function unit, which blocks the unit-side frequency signal from passing through the frequency difference function. and It then acts on the frequency modulation control loop to temporarily cut off the frequency modulation function of the frequency modulation control loop.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 5 to 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 5 to 8.

11. A computer program product, comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 5 to 8.

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