CN115912392A - Method and system for suppressing low frequency oscillations - Google Patents
Method and system for suppressing low frequency oscillations Download PDFInfo
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Abstract
The invention provides a method and a system for inhibiting low-frequency oscillation, wherein the system comprises the following steps: the system comprises a frequency modulation control loop and an oscillation suppression loop, wherein an oscillation judgment unit in the oscillation suppression loop is used for judging low-frequency oscillation according to the actual power of the unit and the side frequency signal of the unit output by the frequency modulation control loop; in response to the low frequency oscillation not occurring, the oscillation determination unit controls the function changeover switch to pass the network frequency signal through the frequency difference function F 1 (x) And F 2 (x) Then acting on a frequency modulation control loop; in response to the low-frequency oscillation, the oscillation judging unit selects the corresponding function according to the low-frequency oscillation intensity level control function switch, and passes through the frequency difference function F 1 (x) And F 2 (x) And the processed unit side frequency signal acts on a frequency modulation control loop to realize low-frequency oscillation suppression. The invention solves the problem that the source side low-frequency oscillation cannot realize autonomous monitoring and active defense at the source side, and greatly avoids the occurrence of low-frequency oscillation accidents.
Description
Technical Field
The invention relates to the technical field of frequency control of generator sets, in particular to a method and a system for inhibiting low-frequency oscillation.
Background
The new energy power generation is accessed in a large amount, and due to the characteristics of randomness, intermittence and fluctuation, the peak regulation capacity of a power system is insufficient, so that the network frequency fluctuation is frequent. Taking a regional power grid as an example, the frequency modulation action times of 8, 9 and 10 months in 20xx year (namely the network frequency exceeds the dead zone +/-2 rpm) are respectively 65, 319 and 164, the action times are increased by 5-8 times compared with other months, and the action times of the ring are increased by 8-10 times compared with the same month in the previous year. On the other hand, a large number of thermal power generating units complete flexibility transformation and operate in a deep peak regulation interval, and because the working areas of main equipment and auxiliary equipment of the units are changed under the working condition, the rotational inertia of the units is continuously reduced, and the disturbance resistance is continuously reduced. The simultaneous action of external disturbance or internal disturbance causes that the unit is easy to trigger unit-level forced oscillation, particularly the low-frequency oscillation accident of the unit frequently occurs, the supporting and adjusting actions of the thermal power unit are not reflected, but huge hidden dangers are brought to the system stability, and the operation safety of the unit and a power grid is endangered.
Low-frequency oscillation (also called electromechanical oscillation, power oscillation) of the power system means: when an electric power system is disturbed, the relative swing between the rotors of the synchronous generators running in parallel causes the phenomenon that electric quantities such as power, voltage, power angle and the like oscillate in different degrees in the system. This constant oscillation is often between 0.2 and 2.5Hz and is therefore referred to as low frequency oscillation. If the oscillation frequency is between 0.2 Hz and 0.7Hz, the oscillation mode is called interval oscillation mode. The mode is the oscillation of a cluster between two areas, the oscillation power is transmitted to the whole system through a connecting line, and the harm of the oscillation mode between the areas is large generally. At present, the research on low-frequency oscillation is mostly concentrated on an excitation system and a PSS system, and mainly carries out analysis research on aspects such as system modeling and damping characteristics, but for the problem of low-frequency oscillation caused on a thermal power unit (prime mover) side, a complete online active solution aiming at the problem of low-frequency oscillation based on a DCS (distributed control system) is not available.
The problem of low-frequency oscillation at the source side is mainly caused by two factors, one of which is an external objective factor, and the network frequency fluctuation is frequent due to the inherent fluctuation characteristic of a large number of new energy units accessed into a power grid; and on the other hand, due to the problems of the working condition of the unit system, the parameters of the frequency modulation control loop and the like, the stability of the unit side is greatly reduced due to the large fluctuation of the frequency modulation loop, and the problem of low-frequency oscillation is easily caused.
A typical control logic used in the prior art frequency control of a plant is shown in fig. 1.
In fig. 1, the AGC command signal and the plant-side frequency (i.e., the network frequency shown in the figure) pass through a frequency difference function F 1 (x) Post-superposition as PID control instruction SP, and real power of unitThe PID control outputs a superposed frequency difference function F as the regulated quantity of the PID 2 (x) The action command(s) is/are used as a comprehensive flow command to act on the valve control of the steam turbine. When the network frequency is lower than 49.9667Hz, the frequency difference function F 1 (x) Sum and frequency difference function F 2 (x) The load set value and the comprehensive flow instruction of the PID are simultaneously acted, so that the opening of the regulating valve is increased, the steam inlet quantity of the steam turbine is increased, the output of the steam turbine is increased, and the active power generated by the generator is increased; otherwise, when the network frequency is higher than 50.033Hz, the opening degree of the valve is reduced, the steam inlet quantity of the steam turbine is reduced, and the active power of the generator is reduced. The unit actively changes the self output according to the frequency change at the source side, and actively supports the stability of the power grid frequency.
However, in the frequency modulation control strategy of the existing thermal power generating unit, an active defense control strategy aiming at low-frequency oscillation of the unit caused by frequency reciprocating fluctuation is not provided. When the stability of a control system of the unit is reduced due to the large and repeated fluctuation of the external network frequency, the system reason of the unit, and the like, and low-frequency oscillation is induced, the active intervention of the source side driving end cannot be used for necessary defense, further amplification of the oscillation cannot be prevented, and the stability of the system is greatly reduced.
Disclosure of Invention
Accordingly, the present invention is directed to a method and system for suppressing low frequency oscillations that solves at least one of the problems set forth above.
In order to achieve the purpose, the invention adopts the following scheme:
according to a first aspect of the present invention, an embodiment of the present invention provides a system for suppressing low-frequency oscillation, the system including: the frequency modulation control loop is connected with the oscillation suppression loop, the oscillation suppression loop comprises an oscillation judgment unit and a function switch, and the oscillation judgment unit is used for judging low-frequency oscillation according to the actual power of the unit and a unit-side frequency signal output by the frequency modulation control loop; in response to the low-frequency oscillation not occurring, the oscillation determination unit controls the function switch to pass the unit-side frequency signal through a frequency difference function F 1 (x) And F 2 (x) Rear endActing on the frequency modulation control loop to enable the frequency modulation control loop to operate in an original working mode; in response to the low-frequency oscillation, the oscillation judging unit controls the function selector switch to select the corresponding function according to the low-frequency oscillation intensity level, and the pass frequency difference function F 1 (x) And F 2 (x) And the processed unit side frequency signal acts on the frequency modulation control loop to realize low-frequency oscillation suppression.
Preferably, in the system of the present embodiment, in response to the low-frequency oscillation occurring, the oscillation determination unit is further configured to: and determining the low-frequency oscillation intensity level according to the low-frequency oscillation characteristic quantity, wherein the characteristic quantity comprises an oscillation amplitude, an oscillation period and an oscillation duration.
Preferably, in the system 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 severity level is determined to be a low severity level; when the load oscillation amplitude is larger than 5MW and smaller than 8MW, the oscillation period is smaller than 5s and larger than 0.2s, and the duration is larger than 10s and smaller than 15s, the intensity level is determined to be a medium intensity level; and 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, judging the intensity level to be a high intensity level.
Preferably, in the system of this embodiment, when the oscillation determining unit determines that the low-frequency oscillation is at the low intensity level, the oscillation determining unit controls the function switch to select the corresponding function according to the low-frequency oscillation intensity level, and passes through the frequency difference function F 1 (x) And F 2 (x) The step of processing the frequency signal at the side of the unit and then acting on the frequency modulation control loop to realize low-frequency oscillation suppression comprises the following steps: the oscillation determination unit controls the function changeover switch to select a suppression function unit that passes a frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop to realize the initial stage of frequency modulation action according to the frequency difference function F 1 (x) And F 2 (x) The operation value of (2) is operated.
Preferably, in the system of the present embodiment, when the oscillation determining unit determines a low-frequency oscillationWhen the oscillation intensity level is in the medium intensity level, the oscillation judging unit controls the function selector switch to select the corresponding function according to the low-frequency oscillation intensity level, and the pass frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal after handles and acts on the frequency modulation control circuit realizes that the low frequency oscillation suppresses including: the oscillation judging unit controls the function switch to select a forced landing function unit which passes through a frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop, and the function of greatly attenuating the frequency modulation action amplitude according to the frequency modulation load is achieved.
Preferably, in the system of this embodiment, when the oscillation determining unit determines that the low-frequency oscillation is at the high-intensity level, the oscillation determining unit controls the function switch to select the corresponding function according to the low-frequency oscillation intensity level, and passes through the frequency difference function F 1 (x) And F 2 (x) The step of processing the frequency signal at the side of the unit and then acting on the frequency modulation control loop to realize low-frequency oscillation suppression comprises the following steps: the oscillation judging unit controls the function selector switch to select a blocking function unit, and the blocking function unit blocks the unit side frequency signal from passing through a frequency difference function F 1 (x) And F 2 (x) And then acting on the frequency modulation control loop to realize the temporary cutting-off function of the frequency modulation control loop.
According to a second aspect of the present invention, an embodiment of the present invention provides a method for suppressing low-frequency oscillation, the method including: performing low-frequency oscillation judgment according to the actual power of the unit output by the frequency modulation control loop and a unit side frequency signal; in response to the low-frequency oscillation not occurring, controlling a function change-over switch to enable the unit side frequency signal to pass through a frequency difference function F 1 (x) And F 2 (x) Then acting on the frequency modulation control loop to enable the frequency modulation control loop to operate in the original working mode; responding to the low-frequency oscillation, controlling the function selector switch to select the corresponding function according to the low-frequency oscillation intensity level, and passing a frequency difference function F 1 (x) And F 2 (x) The processed unit side frequency signal acts on the frequency modulation control loop to realizeAnd (5) suppressing low-frequency oscillation.
Preferably, in the foregoing steps of this embodiment, in response to the low-frequency oscillation occurring, the method further includes: and determining the low-frequency oscillation intensity level according to the low-frequency oscillation characteristic quantity, wherein the characteristic quantity comprises an oscillation amplitude, an oscillation period and an oscillation duration.
Preferably, in the above step 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 a low intensity level; when the load oscillation amplitude is larger than 5MW and smaller than 8MW, the oscillation period is smaller than 5s and larger than 0.2s, and the duration is larger than 10s and smaller than 15s, the intensity level is determined to be a medium intensity level; and 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, judging the intensity level to be a high intensity level.
Preferably, in the above steps of this embodiment, when the low-frequency oscillation is determined to be of the low intensity level, the switch is controlled to select the corresponding function according to the low-frequency oscillation intensity level, and the pass frequency difference function F is obtained 1 (x) And F 2 (x) The step of processing the frequency signal at the side of the unit and then acting on the frequency modulation control loop to realize low-frequency oscillation suppression comprises the following steps: the control function switch selects a suppression function unit which passes through the frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop to realize the initial stage of frequency modulation action according to the frequency difference function F 1 (x) And F 2 (x) The operation value of (2) is operated.
Preferably, in the above steps of this embodiment, when the low-frequency oscillation is determined to be of the medium-intensity level, the switch is controlled to select the corresponding function according to the low-frequency oscillation intensity level, and the pass-through frequency difference function F is performed 1 (x) And F 2 (x) The unit side frequency signal after handles and acts on the frequency modulation control circuit realizes that the low frequency oscillation suppresses including: the control function switch selects the forced landing functional unit which passes through the frequency difference function F 1 (x) And F 2 (x) The frequency signal of the unit side is processed and then acts on the frequency modulation control loop,the function of greatly attenuating the frequency modulation action amplitude according to the frequency modulation load is realized.
Preferably, in the above steps of this embodiment, when it is determined that the low-frequency oscillation is at the high-intensity level, the switch is controlled to select the corresponding function according to the low-frequency oscillation intensity level, and the pass-through frequency difference function F is obtained 1 (x) And F 2 (x) The unit side frequency signal after handles and acts on the frequency modulation control circuit realizes that the low frequency oscillation suppresses including: the control function switch selects a blocking function unit, and the blocking function unit blocks the unit side frequency signal to pass through a frequency difference function F 1 (x) And F 2 (x) And then acting on the frequency modulation control loop to realize the temporary cutting-off function of the frequency modulation control loop.
According to a third aspect of the present invention, an embodiment of the present invention further provides an electronic device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor implements the steps of the above method when executing the computer program.
According to a fourth aspect of the present invention, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, which, when executed by a processor, implements the steps of the above-mentioned method.
According to a fifth aspect of the present invention, an embodiment of the present invention further provides a computer program product, which includes a computer program/instruction, and when the computer program/instruction is executed by a processor, the steps of the above method are implemented.
The method and the system for inhibiting the low-frequency oscillation solve the problem that the source side low-frequency oscillation cannot realize autonomous monitoring and active defense at the source side, and greatly avoid the occurrence of low-frequency oscillation accidents. Meanwhile, the frequency modulation performance can be effectively prevented from being reduced due to misjudgment, and the method has important significance for improving the frequency modulation safety and performance of the unit.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts. In the drawings:
FIG. 1 is a typical control logic diagram for existing unit frequency control;
fig. 2 is a schematic structural diagram of a system for suppressing low-frequency oscillation according to an embodiment of the present application;
FIG. 3 is a comparison graph of the low frequency oscillation of the unit after triggering the suppression function;
FIG. 4 is a graph comparing the low frequency oscillation of the unit with the forced landing triggering function;
FIG. 5 is a graph comparing the low frequency oscillation of the unit with the triggered blocking function;
FIG. 6 is a schematic flow chart of a method for suppressing low frequency oscillation according to an embodiment of the present disclosure;
FIG. 7 is a flow chart illustrating a method for suppressing low frequency oscillations according to another embodiment of the present application;
fig. 8 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.
Fig. 2 is a schematic structural diagram of a system for suppressing low-frequency oscillation according to an embodiment of the present application, where the system includes: the frequency modulation control circuit 100 and the oscillation suppression circuit are connected, and as can be seen from fig. 2, the oscillation suppression circuit of the present application includes an oscillation determination unit 200, function switches S1 and S2, and a function unit 300.
The frequency modulation control loop 100 is the same as that shown in fig. 1 in the prior art, except that the network frequency input of the two summing units in the modulation control loop 100 is controlled by the oscillation suppression loop.
The oscillation determining unit 200 is configured to determine low-frequency oscillation according to the actual power of the plant and the plant-side frequency signal (i.e., the grid frequency in fig. 2) output by the fm control loop, that is, determine whether low-frequency oscillation occurs.
When the oscillation determining unit 200 determines that the low frequency oscillation does not occur, the oscillation determining unit 200 controls the function switching switches S1 and S2 so that the unit side frequency signal passes through the frequency difference function F 1 (x) And F 2 (x) And then to the fm control circuit 100, as shown in fig. 2, the function switches S1 and S2 can be switched to side 1, that is, the fm control circuit 100 can operate in the original operation mode.
When the oscillation determining unit 200 determines that the low frequency oscillation occurs, the oscillation determining unit 200 selects the corresponding function in the function unit 300 according to the low frequency oscillation intensity level control function switches S1 and S2, and passes the frequency difference function F 1 (x) And F 2 (x) The later unit side frequency signal is correspondingly processed and then acts on the frequency modulation control loop 100 to realize low-frequency oscillation suppression.
Preferably, as an embodiment of the present invention, when determining that the low-frequency oscillation occurs, the oscillation determining unit 200 may further determine the low-frequency oscillation intensity level according to a characteristic quantity of the low-frequency oscillation, where the characteristic quantity may include an oscillation amplitude, an oscillation period, and an oscillation duration.
Preferably, the low-frequency oscillation intensity level may include three levels, i.e., low, medium and high, and specifically, when the load oscillation amplitude is less than 5MW, the oscillation period is greater than 5s, and the duration is less than 10s, the oscillation determining unit 200 determines that the intensity level is a low intensity level (safety level); 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 oscillation determination unit 200 determines that the intensity level is a medium intensity level (danger level); 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 oscillation determination unit 200 determines that the intensity level is a high intensity level (an extremely dangerous level).
Preferably, when the oscillation determining unit 200 determines that the low frequency oscillation is of a low intensity level, the oscillation determining unit 200 controls the function switches S1 and S2 to switch to the 2 side and to switch to the suppressing function unit in the function unit 300, which passes the frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop, so that the initial stage of the frequency modulation action of the frequency modulation control loop 100 is realized according to the frequency difference function F 1 (x) And F 2 (x) The operation value of (2) is operated.
E.g. a plant F 1 (x) Set up as in Table 1 below
TABLE 1
| Slip (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 |
When the safety level is judged, the current slip is-4 rpm (0.0667 Hz), the value of-15.7769 MW is directly set at the initial stage of the inhibiting action process, and after the slip is-4 rpm h in the later stage, the value is changed from-15.7769 MW to 0 immediately, but is changed to 0 through a certain speed. Also for F 2 (x) And acts similarly.
Preferably, when the oscillation determining unit 200 determines that the low-frequency oscillation is at the medium-intensity level, the oscillation determining unit 200 controls the function switches S1 and S2 to switch to the 3-side and switch to the forced-drop function unit in the function unit 300, which passes the frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop, so that the function of greatly attenuating the frequency modulation action amplitude according to the frequency modulation load is realized.
When the safety level is judged, the current slip is-4 rpm (0.0667 Hz), the value-15.7769 multiplied by the coefficient (the coefficient is far less than 1) is directly set at the initial stage of the forced landing action process, and the action amplitude is greatly reduced. Also for F 2 (x) And acts similarly.
Preferably, when the oscillation determining unit 200 determines that the low-frequency oscillation is of a high-intensity level, the oscillation determining unit 200 controls the function switches S1 and S2 to switch to the 4-side and to switch to the blocking function unit in the function unit 300, which blocks the unit-side frequency signal from passing through the frequency difference function F 1 (x) And F 2 (x) And then acting on the frequency modulation control loop to realize the temporary cutting-off function of the frequency modulation control loop.
The beneficial effects of the technical scheme of the present application are explained by several specific embodiments, taking the low-frequency oscillation phenomenon of a certain 350MW supercritical unit as an example, fig. 3 is a comparison graph of the low-frequency oscillation of the unit and the triggering suppression function, fig. 4 is a comparison graph of the low-frequency oscillation of the unit and the triggering forced landing function, and fig. 5 is a comparison graph of the low-frequency oscillation of the unit and the triggering blocking function.
As can be seen from FIG. 3, when the unit has no low-frequency oscillation forced landing function, the oscillation amplitude reaches 212.5MW-205.4MW, and the oscillation amplitude is 8MW between the maximum value and the minimum value. After the low-frequency oscillation forced-falling function is triggered, the load oscillation load is rapidly reduced to 209MW-210MW, only less than 1MW exists between the maximum value and the minimum value of the oscillation, and no periodic fluctuation phenomenon occurs.
As can be seen from FIG. 4, the oscillation amplitude of the unit reaches 212.5MW-205.4MW without the low-frequency oscillation forced landing function, and the oscillation amplitude is 8MW between the maximum value and the minimum value. After the low-frequency oscillation forced-falling function is triggered, the load oscillation load is rapidly reduced to 209MW-210MW, only less than 1MW exists between the maximum value and the minimum value of the oscillation, and no periodic fluctuation phenomenon occurs.
As can be seen from FIG. 5, the oscillation amplitude of the unit reaches 212.5MW-205.4MW without the low-frequency oscillation forced landing function, and the oscillation amplitude is 8MW between the maximum value and the minimum value. After the low-frequency oscillation forced-descending function is triggered, the load oscillation load is rapidly reduced to 209MW-210MW, only less than 1MW exists between the maximum value and the minimum value of the oscillation, and no periodic fluctuation phenomenon occurs.
Therefore, the system for suppressing the low-frequency oscillation provided by the embodiment of the present application solves the problem that the source-side low-frequency oscillation cannot realize autonomous monitoring and active defense at the source side, and greatly avoids the occurrence of the low-frequency oscillation accident. Meanwhile, the frequency modulation performance can be effectively prevented from being reduced due to misjudgment, and the frequency modulation performance cannot be guaranteed as long as a frequency modulation loop is cut off in the judgment without a three-level suppression mode, so that the three-level suppression mode has important significance for improving the frequency modulation safety and performance of the unit.
Fig. 6 is a schematic flow chart of a method for suppressing low-frequency oscillation according to an embodiment of the present application, where the method includes the following steps:
step S601: and judging low-frequency oscillation according to the actual power of the unit and the frequency signal at the side of the unit output by the frequency modulation control loop, if no low-frequency oscillation occurs, entering a step S602, otherwise, entering a step S603.
Step S602: the control function switch makes the unit side frequency signal pass through a frequency difference function F 1 (x) And F 2 (x) And then acting on the frequency modulation control loop to enable the frequency modulation control loop to operate in the original working mode.
Step S603: controlling the function selector switch to select corresponding function according to the low-frequency oscillation intensity level, and passing a frequency difference function F 1 (x) And F 2 (x) And the processed unit side frequency signal acts on the frequency modulation control loop to realize low-frequency oscillation suppression.
Therefore, the method for inhibiting the low-frequency oscillation solves the problem that the source side low-frequency oscillation cannot be monitored and defended automatically on the source side, and greatly avoids the occurrence of low-frequency oscillation accidents. Meanwhile, the frequency modulation performance can be effectively prevented from being reduced due to misjudgment, and the method has important significance for improving the frequency modulation safety and performance of the unit.
Fig. 7 is a schematic flow chart of a method for suppressing low-frequency oscillation according to another embodiment of the present application, where the method includes the following steps:
step S701: and judging low-frequency oscillation according to the actual power of the unit and the frequency signal at the side of the unit output by the frequency modulation control loop, if no low-frequency oscillation occurs, entering a step S702, otherwise, entering a step S703.
Step S702: the control function switch enables the unit side frequency signal to pass through a frequency difference function F 1 (x) And F 2 (x) And then acting on the frequency modulation control loop to enable the frequency modulation control loop to operate in the original working mode.
Step S703: and determining the low-frequency oscillation intensity level according to the low-frequency oscillation characteristic quantity, wherein the characteristic quantity comprises an oscillation amplitude, an oscillation period and an oscillation duration. If the low frequency oscillation is of a low intensity level, the process proceeds to step S704, if the low frequency oscillation is of a medium intensity level, the process proceeds to step S705, and if the low frequency oscillation is of a high intensity level, the process proceeds to step S706.
Specifically, when the load oscillation amplitude is smaller than 5MW, the oscillation period is larger than 5s, and the duration is smaller than 10s, the intensity level is determined to be a low intensity level; when the load oscillation amplitude is larger than 5MW and smaller than 8MW, the oscillation period is smaller than 5s and larger than 0.2s, and the duration is larger than 10s and smaller than 15s, the intensity level is determined to be a medium intensity level; and 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, judging the intensity level to be a high intensity level.
Step S704: the control function switch selects a suppression function unit which passes through the frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop to realize the initial stage of frequency modulation action according to the frequency difference function F 1 (x) And F 2 (x) The operation value of (2) is operated.
Step S705: the control function switch selects the forced landing functional unit which passes through the frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop, and the function of greatly attenuating the frequency modulation action amplitude according to the frequency modulation load is achieved.
Step S706: the control function switch selects a blocking function unit, and the blocking function unit blocks the unit side frequency signal to pass through a frequency difference function F 1 (x) And F 2 (x) And then acting on the frequency modulation control loop to realize the temporary cutting-off function of the frequency modulation control loop.
In summary, the method for suppressing low-frequency oscillation provided by the embodiment of the present application solves the problem that the source-side low-frequency oscillation cannot be autonomously monitored and actively defended on the source side, and substantially avoids the occurrence of the low-frequency oscillation accident. Meanwhile, the frequency modulation performance can be effectively prevented from being reduced due to misjudgment, and the method has important significance for improving the frequency modulation safety and performance of the unit.
Fig. 8 is a schematic diagram of an electronic device provided in an embodiment of the present invention. The electronic device shown in fig. 8 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 the memory 802 are connected by a bus 803. The memory 802 is adapted to store one or more instructions or programs executable by the processor 801. The one or more instructions or programs are executed by the processor 801 to implement the steps in the above-described method of suppressing low frequency oscillations.
The processor 801 may be a stand-alone microprocessor or a collection of one or more microprocessors. Thus, the processor 801 implements the processing of data and the control of other devices by executing commands stored in the memory 802 to thereby execute the method flows of embodiments of the present invention as described above. The bus 803 connects the above-described components together, as well as to a display controller 804 and a display device and an input/output (I/O) device 805. Input/output (I/O) devices 805 may be a mouse, keyboard, modem, network interface, touch input device, motion sensing input device, printer, and other devices known in the art. Typically, input/output (I/O) devices 805 are connected to the system through an input/output (I/O) controller 806.
The memory 802 may store, among other things, software components such as an operating system, communication modules, interaction modules, and application programs. Each of the modules and applications described above corresponds to a set of executable program instructions that perform one or more functions and methods described in embodiments of the invention.
Embodiments of the present invention also provide a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements the steps of the above-mentioned method for suppressing low-frequency oscillations.
Embodiments of the present invention also provide a computer program product, which includes a computer program/instruction, and the computer program/instruction, when executed by a processor, implement the steps of the above method for suppressing low frequency oscillation.
In summary, the method and the device for suppressing low-frequency oscillation provided by the invention solve the problem that the source side low-frequency oscillation cannot realize autonomous monitoring and active defense at the source side, and greatly avoid the occurrence of low-frequency oscillation accidents. Meanwhile, the frequency modulation performance can be effectively prevented from being reduced due to misjudgment, and the method has important significance for improving the frequency modulation safety and performance of the unit.
The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. The many features and advantages of the embodiments are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the embodiments which fall within the true spirit and scope thereof. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the embodiments of the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope thereof.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may 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, and the like) having computer-usable program code embodied therein.
The present 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 flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may 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, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (15)
1. A system for suppressing low frequency oscillations, said system comprising: the frequency modulation control circuit is connected with the oscillation suppression circuit, the oscillation suppression circuit comprises an oscillation determination unit and a function switch,
the oscillation judgment unit is used for judging low-frequency oscillation according to the actual power of the unit and the side frequency signal of the unit output by the frequency modulation control loop;
in response to the low-frequency oscillation not occurring, the oscillation determination unit controls the function switch to pass the unit-side frequency signal through a frequency difference function F 1 (x) And F 2 (x) Then acting on the frequency modulation control loop to enable the frequency modulation control loop to operate in the original working mode;
in response to low frequency oscillations occurringThe oscillation judging unit controls the function selector switch to select corresponding functions according to the low-frequency oscillation intensity level, and the pass frequency difference function F 1 (x) And F 2 (x) And the processed unit side frequency signal acts on the frequency modulation control loop to realize low-frequency oscillation suppression.
2. The system for suppressing low frequency oscillations according to claim 1, characterized in that, in response to low frequency oscillations occurring, said oscillation decision unit is further adapted to: and determining the low-frequency oscillation intensity level according to the low-frequency oscillation characteristic quantity, wherein the low-frequency oscillation characteristic quantity comprises an oscillation amplitude, an oscillation period and an oscillation duration.
3. The system for suppressing low frequency oscillations according to claim 2, characterized in that, when the load oscillation amplitude is less than 5MW, the oscillation period is greater than 5s, and the duration is less than 10s, the severity level is determined to be a low severity level; when the load oscillation amplitude is larger than 5MW and smaller than 8MW, the oscillation period is smaller than 5s and larger than 0.2s, and the duration is larger than 10s and smaller than 15s, the intensity level is determined to be a medium intensity level; and 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, judging the intensity level to be a high intensity level.
4. The system for suppressing low frequency oscillation according to claim 3, wherein when the oscillation determining unit determines that the low frequency oscillation is at a low intensity level, the oscillation determining unit controls the function changeover switch to select the corresponding function according to the low frequency oscillation intensity level, and passes a frequency difference function F 1 (x) And F 2 (x) The step of processing the frequency signal at the side of the unit and then acting on the frequency modulation control loop to realize low-frequency oscillation suppression comprises the following steps:
the oscillation determination unit controls the function changeover switch to select a suppression function unit that passes a frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop to realize the initial stage of frequency modulation action according to the frequency difference function F 1 (x) And F 2 (x) The operation value of (2) is operated.
5. The system for suppressing low-frequency oscillation according to claim 3, wherein when the oscillation determining unit determines that the low-frequency oscillation is of a medium-intensity level, the oscillation determining unit controls the function switch to select the corresponding function according to the low-frequency oscillation intensity level, and passes a frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal after handles and acts on the frequency modulation control circuit realizes that the low frequency oscillation suppresses including:
the oscillation judging unit controls the function switch to select a forced landing function unit which passes through a frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop, and the function of greatly attenuating the frequency modulation action amplitude according to the frequency modulation load is achieved.
6. The system for suppressing low-frequency oscillation according to claim 3, wherein when the oscillation determining unit determines that the low-frequency oscillation is at a high intensity level, the oscillation determining unit controls the function switch to select the corresponding function according to the low-frequency oscillation intensity level, for passing through a frequency difference function F 1 (x) And F 2 (x) The step of processing the frequency signal at the side of the unit and then acting on the frequency modulation control loop to realize low-frequency oscillation suppression comprises the following steps:
the oscillation judging unit controls the function selector switch to select a blocking function unit, and the blocking function unit blocks the unit side frequency signal from passing through a frequency difference function F 1 (x) And F 2 (x) And then acting on the frequency modulation control loop to realize the temporary cutting-off function of the frequency modulation control loop.
7. A method of suppressing low frequency oscillations, the method comprising:
performing low-frequency oscillation judgment according to the actual power of the unit and a unit side frequency signal output by the frequency modulation control loop;
in response to the low-frequency oscillation not occurring, controlling a function change-over switch to enable the unit side frequency signal to pass through a frequency difference function F 1 (x) And F 2 (x) Then acting on the frequency modulation control loop to enable the frequency modulation control loop to operate in the original working mode;
responding to the low-frequency oscillation, controlling the function selector switch to select the corresponding function according to the low-frequency oscillation intensity level, and passing a frequency difference function F 1 (x) And F 2 (x) And the processed unit side frequency signal acts on the frequency modulation control loop to realize low-frequency oscillation suppression.
8. The method of suppressing low frequency oscillations according to claim 7, characterized in that, in response to low frequency oscillations occurring, said method further comprises: and determining the low-frequency oscillation intensity level according to the low-frequency oscillation characteristic quantity, wherein the low-frequency oscillation characteristic quantity comprises an oscillation amplitude, an oscillation period and an oscillation duration.
9. The method of suppressing low frequency oscillations according to claim 8, characterized in that, when the load oscillation amplitude is less than 5MW, the oscillation period is greater than 5s, and the duration is less than 10s, the severity level is determined to be a low severity level; when the load oscillation amplitude is larger than 5MW and smaller than 8MW, the oscillation period is smaller than 5s and larger than 0.2s, and the duration is larger than 10s and smaller than 15s, the intensity level is determined to be a medium intensity level; and 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, judging the intensity level to be a high intensity level.
10. The method of suppressing ringing in claim 9, wherein when the ringing is determined to be at a low severity level, said controlling the function switches to select the corresponding function according to the ringing severity level by passing through a frequency difference function F 1 (x) And F 2 (x) The step of processing the frequency signal at the side of the unit and then acting on the frequency modulation control loop to realize low-frequency oscillation suppression comprises the following steps:
control function selector switch to select a suppression function unit, the suppression function unitElement pair passing frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop to realize the initial stage of frequency modulation action according to the frequency difference function F 1 (x) And F 2 (x) The operation value of (2) is operated.
11. The method of suppressing ringing in claim 9, wherein when the ringing is determined to be of medium severity level, said controlling the function switches to select the corresponding function according to the ringing severity level, passes a frequency difference function F 1 (x) And F 2 (x) The step of processing the frequency signal at the side of the unit and then acting on the frequency modulation control loop to realize low-frequency oscillation suppression comprises the following steps:
the control function switch selects the forced landing functional unit which passes through the frequency difference function F 1 (x) And F 2 (x) The unit side frequency signal is processed and then acts on the frequency modulation control loop, and the function of greatly attenuating the frequency modulation action amplitude according to the frequency modulation load is achieved.
12. The method of suppressing low frequency oscillations according to claim 9, characterized in that, when it is determined that the low frequency oscillations are of high intensity level, said controlling the function switcher to select the corresponding function according to the low frequency oscillation intensity level, passes the frequency difference function F 1 (x) And F 2 (x) The step of processing the frequency signal at the side of the unit and then acting on the frequency modulation control loop to realize low-frequency oscillation suppression comprises the following steps:
the control function switch selects a blocking function unit, and the blocking function unit blocks the unit side frequency signal to pass through a frequency difference function F 1 (x) And F 2 (x) And then acting on the frequency modulation control loop to realize the temporary cutting-off function of the frequency modulation control loop.
13. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the steps of the method of any of claims 7 to 12 are implemented by the processor when executing the computer program.
14. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of any one of claims 7 to 12.
15. A computer program product comprising computer program/instructions, characterized in that said computer program/instructions, when executed by a processor, implement the steps of the method of any of claims 7 to 12.
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| CN202211231928.1A CN115912392A (en) | 2022-09-30 | 2022-09-30 | Method and system for suppressing low frequency oscillations |
| PCT/CN2023/118761 WO2024067120A1 (en) | 2022-09-30 | 2023-09-14 | Method and system for suppressing low-frequency oscillation |
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| WO2024067120A1 (en) * | 2022-09-30 | 2024-04-04 | 华北电力科学研究院有限责任公司 | Method and system for suppressing low-frequency oscillation |
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| CN102928695A (en) * | 2012-10-18 | 2013-02-13 | 中国电力科学研究院 | Method for judging negatively-damped oscillation and forced oscillation on basis of straight line method |
| CN103311939B (en) * | 2013-06-14 | 2014-12-31 | 华北电力大学（保定） | WAMS (wide area measurement system) based low-frequency oscillation coordinated damping control method for electric power system |
| CN204741274U (en) * | 2015-06-26 | 2015-11-04 | 四川大学 | Multifrequency section direct current additional damping controlling means based on it is multistage linear optimum theoretical |
| CN105098803B (en) * | 2015-10-08 | 2017-10-24 | 中南大学 | Wind power plant based on STATCOM is subsynchronous and low-frequency oscillation suppression method |
| CN110224394B (en) * | 2019-05-29 | 2020-08-28 | 海南电网有限责任公司电力科学研究院 | Fourier decomposition algorithm suitable for extracting characteristics of non-stationary power oscillation signal |
| CN110571830A (en) * | 2019-09-16 | 2019-12-13 | 国网河北省电力有限公司电力科学研究院 | emergency control method and device for externally-hung power system stabilizer |
| CN115912392A (en) * | 2022-09-30 | 2023-04-04 | 华北电力科学研究院有限责任公司 | Method and system for suppressing low frequency oscillations |
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