CN114362245B - Wind farm attack method and system - Google Patents
Wind farm attack method and system Download PDFInfo
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- CN114362245B CN114362245B CN202210029825.0A CN202210029825A CN114362245B CN 114362245 B CN114362245 B CN 114362245B CN 202210029825 A CN202210029825 A CN 202210029825A CN 114362245 B CN114362245 B CN 114362245B
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Abstract
The application discloses a wind farm attack method and a system, wherein the method comprises the following steps: controlling a direct-hanging type disturbance current injection device to inject a broadband current signal into a system, acquiring a system admittance-frequency characteristic curve and a system admittance-frequency characteristic expression based on voltage and current signals at a grid-connected point, selecting attack modes, and sequencing the attack modes according to the damping ratio; injecting attack current under each attack mode according to the sequence, wherein each attack lasts for a preset time, monitoring whether grid-connected current has a divergence trend in each attack process, if so, the attack is successful, and otherwise, the attack is performed by using the attack current under the next attack mode; if all the attack currents are unsuccessful, and when the wind farm state or the power grid running state changes, the broadband current signal is injected again, and the attack mode is selected for attack until the attack is successful. According to the wind power plant weak point identification method, the disturbance signals are injected into the physical side, so that the accuracy and the efficiency of wind power plant weak point identification are improved, and the oscillation risk frequency is effectively identified.
Description
Technical Field
The application relates to the field of power system safety evaluation, in particular to a wind farm attack method and system.
Background
The large-scale renewable energy source is connected into a power grid through the power electronic converter, so that the power electronic equipment of the power system is increased continuously, and the modern power system is gradually developed towards the trend of power electronics. The characteristics of low inertia, weak immunity and strong non-linear and multi-time scale response increase the risk of the broadband oscillation of the power electronic power system caused by external risks.
Broadband oscillation refers to a dynamic process in which an electric quantity (such as voltage, current, power, etc.) caused by interaction between power electronic devices and a power grid of a power system is periodically fluctuated with time due to the influence of the power system or external factors, and the oscillation frequency is changed in a wider range. The interaction of multiple time scales in the wind power grid-connected system enables the system to have a potential weak damping oscillation mode, and when disturbance of corresponding frequency occurs in the system, the wind power grid-connected system can be forced to oscillate in a wide frequency band, and finally the system is unstable. The broadband oscillation problem caused by the wind power grid-connected system seriously affects the safety and the electricity quality of equipment, restricts the efficient consumption of wind power and threatens the safety and stability of a power grid.
Along with the gradual increase of the number and the gradual increase of the scale of wind power plants, the dynamic interaction among wind power grid-connected systems is gradually complicated, and the oscillation risk is greatly increased, so that the broadband attack on the wind power plants is very necessary, the oscillation risk frequency of the systems can be effectively identified, and effective information is provided for formulating a stable control strategy of the wind power plants.
Disclosure of Invention
Therefore, the technical problem to be solved by the application is to overcome the defect that the wind farm in the prior art is easy to generate broadband oscillation, so as to provide a wind farm attack method and system.
In order to achieve the above purpose, the present application provides the following technical solutions:
in a first aspect, an embodiment of the present application provides a wind farm attack method, including: the direct-hanging type disturbance current injection device is arranged in parallel at the grid-connected point of the wind power plant, and is controlled to inject a broadband current signal into the wind power grid-connected system, and the voltage and the current signal at the grid-connected point are collected; acquiring a system admittance-frequency characteristic curve based on the acquired voltage and current signals at the grid-connected point, identifying and obtaining an admittance-frequency characteristic expression of the system, and calculating the frequency and damping ratio of each mode of the system; according to the frequency and the damping ratio of each mode of the system, setting the mode with the damping ratio smaller than a preset damping value as an attack mode, and sequencing the attack modes according to the damping ratio; according to the sequence of the attack modes, sequentially injecting attack currents in each attack mode, continuously attacking for preset time, monitoring whether the grid-connected current of the wind power plant has a divergent trend in the attack time of each attack current, if so, successfully attacking, otherwise, carrying out attack again by using the attack current in the next attack mode; if the attack current in all the current attack modes is not successful, judging whether the wind power plant state and the power grid running state change or not in a first preset time interval, and returning to the step of controlling the direct hanging type disturbance current injection device to inject a broadband current signal into the wind power grid-connected system and collecting voltage and current signals at the grid-connected point until the attack is successful when the wind power plant state or the power grid running state changes.
In one embodiment, the direct-hanging type disturbance current injection device is composed of a flying capacitor type three-level topological structure and a single-phase H-bridge cascading submodule power unit; the running state of the direct-hanging type disturbance current injection device is controlled by using a direct-current total voltage control method and a current control method, the single-phase H bridge cascade submodule is controlled by using a voltage balance control method, and the flying capacitor type three-level topological structure is controlled by using a direct-current voltage control method.
In one embodiment, the process of controlling the direct-hanging type disturbance current injection device to inject the broadband current signal into the wind power grid system comprises the following steps: obtaining a given broadband current signal based on a power spectrum of a random binary sequence and a preset multiple of rated current of a direct-hanging type disturbance current injection device; superposing a given broadband current signal and a DC side total voltage control output signal as a current control reference value; after the current loop controller and modulation, the direct-hanging type disturbance current injection device injects a broadband current signal into the wind power grid-connected system.
In one embodiment, the process of acquiring a system admittance-frequency characteristic curve based on the collected voltage and current signals at the grid-connected point, identifying and obtaining an admittance-frequency characteristic expression of the system, and calculating the frequency and damping ratio of each mode of the system comprises the following steps: carrying out frequency spectrum analysis on the collected voltage and current signals at the grid-connected point to obtain voltage phasors and current phasors under each frequency component, and calculating the system admittance value under each frequency component; connecting the real part and the imaginary part of the system admittance under each frequency component into a curve respectively to obtain a system admittance-frequency characteristic curve; identifying a system admittance-frequency characteristic curve by adopting a transfer function identification method to obtain an admittance-frequency characteristic expression of the system; and (3) enabling the admittance-frequency characteristic expression of the system to be zero, obtaining a plurality of zero points of the admittance-frequency characteristic expression of the system, and calculating the frequency and damping ratio of each oscillation mode based on the zero points.
In one embodiment, the process of obtaining the attack current in each attack mode includes: taking the frequency of the current attack mode as the frequency of a given current disturbance signal; obtaining the amplitude of a given current disturbance signal according to the capacity of the direct-hanging disturbance current injection device and the admittance actual value of the current attack mode; obtaining a given sinusoidal current disturbance signal according to the frequency of the given current disturbance signal and the amplitude of the given current disturbance signal; superposing a given sinusoidal current disturbance signal and a direct-current side total voltage control output signal as a current loop reference value; after the current loop controller and modulation, the direct-hanging disturbance current injection device outputs attack current.
In one embodiment, a process for monitoring whether wind farm grid-tie current has a tendency to diverge comprises: measuring current signals at the point of connection in real time; acquiring current data of the last second preset time interval every second preset time interval, and calculating the damping ratio of a current signal with the frequency of the current attack mode; and in the preset time of continuous attack of the attack current, if the damping ratio of the current signal with the frequency of the current attack mode is a negative value, judging that the grid-connected current of the wind power plant has a divergence trend.
In an embodiment, the process of determining whether the wind farm state and the grid operation state change in the first preset time interval includes: monitoring wind speed in a first preset time interval, and judging that the state of the wind power plant changes when the wind speed changes by more than a preset multiple of the rated wind speed; and if the state of the wind power plant is not changed within the first preset time interval, judging that the running state of the power grid is changed.
In a second aspect, an embodiment of the present application provides a wind farm attack apparatus, including: the acquisition module is used for installing the direct-hanging type disturbance current injection device in parallel at the grid-connected point of the wind power plant, controlling the direct-hanging type disturbance current injection device to inject a broadband current signal into the wind power grid-connected system, and acquiring voltage and current signals at the grid-connected point; the calculation module is used for acquiring a system admittance-frequency characteristic curve based on the acquired voltage and current signals at the grid-connected point, identifying and obtaining an admittance-frequency characteristic expression of the system, and calculating the frequency and damping ratio of each mode of the system; the ordering module is used for setting the mode with the damping ratio smaller than a preset damping value as an attack mode according to the frequency and the damping ratio of each mode of the system, and ordering the attack modes according to the damping ratio; the attack module is used for sequentially injecting attack currents in each attack mode according to the sequence of the attack modes, wherein each attack current continuously attacks for a preset time, monitoring whether the grid-connected current of the wind power plant has a divergent trend in the attack time of each attack current, if so, the attack is successful, otherwise, the attack is carried out again by using the attack current in the next attack mode; and the circulating attack module is used for judging whether the wind power plant state and the power grid running state change within a first preset time interval if the attack current in all the current attack modes is not successful, and returning to the step of controlling the direct hanging type disturbance current injection device to inject a broadband current signal into the wind power grid connection system and collecting the voltage and current signals at the grid connection point until the attack is successful when the wind power plant state or the power grid running state changes.
In a third aspect, an embodiment of the present application provides a computer apparatus, including: the wind farm attack system comprises at least one processor and a memory communicatively connected with the at least one processor, wherein the memory stores instructions executable by the at least one processor to cause the at least one processor to perform the wind farm attack method of the first aspect of the embodiment of the present application.
In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, where computer instructions are stored, where the computer instructions are configured to cause a computer to perform the wind farm attack method according to the first aspect of the embodiment of the present application.
The technical scheme of the application has the following advantages:
according to the wind farm attack method and system, the direct-hanging type disturbance current injection device is installed in parallel at the grid-connected point of the wind farm, and the direct-hanging type disturbance current injection device is controlled to inject broadband current signals into the wind grid-connected system, so that accuracy and efficiency of identifying weak points of the wind farm are improved; acquiring a system admittance-frequency characteristic curve and an admittance-frequency characteristic expression of the system based on voltage and current signals at the grid-connected point, and calculating the frequency and damping ratio of each mode of the system; selecting an attack mode, and sorting the attack modes according to the damping ratio; sequentially injecting attack currents in each attack mode according to the sequence of the attack modes, wherein each attack current continuously attacks for a preset time, monitoring whether the grid-connected current of the wind power plant has a divergent trend in the attack time of each attack current, if so, the attack is successful, otherwise, the attack is carried out again by using the attack current in the next attack mode; if the attack current in all the current attack modes is not successful, and when the wind farm state or the power grid running state changes, the broadband current signal is injected again, and the attack mode is selected for attack until the attack is successful. According to the wind power station weak point identification method, the parallel disturbance device is used for directly injecting disturbance signals into the physical side, so that the accuracy and the efficiency of wind power station weak point identification are improved; the system effectively recognizes the oscillation risk frequency existing in the system, provides effective information for formulating a stable control strategy of the wind power plant, can be used for testing grid-connected stability of the wind power plant, and verifies small interference stability of the wind power plant after being connected into a large power grid.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flowchart of a specific example of a wind farm attack method according to an embodiment of the present application;
FIG. 2 is a block diagram of a specific example of a direct-hanging disturbance current injection device according to an embodiment of the present application;
FIG. 3 is a flowchart of another specific example of a wind farm attack method provided by an embodiment of the present application;
FIG. 4 is a flowchart of another specific example of a wind farm attack method provided by an embodiment of the present application;
FIG. 5 is a flowchart of another specific example of a wind farm attack method provided by an embodiment of the present application;
FIG. 6 is a flowchart of another specific example of a wind farm attack method provided by an embodiment of the present application;
FIG. 7 is a flowchart of another specific example of a wind farm attack method provided by an embodiment of the present application;
FIG. 8 is a block diagram of a specific example of a wind farm attack system provided by an embodiment of the present application;
fig. 9 is a composition diagram of a specific example of a computer device according to an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the application are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In the description of the present application, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; the two components can be directly connected or indirectly connected through an intermediate medium, or can be communicated inside the two components, or can be connected wirelessly or in a wired way. The specific meaning of the above terms in the present application will be understood in specific cases by those of ordinary skill in the art.
In addition, the technical features of the different embodiments of the present application described below may be combined with each other as long as they do not collide with each other.
Example 1
An embodiment of the present application provides a wind farm attack method, as shown in fig. 1, including:
step S11: the direct-hanging type disturbance current injection device is arranged in parallel at the grid-connected point of the wind power plant, and is controlled to inject broadband current signals into the wind power grid-connected system, and voltage and current signals at the grid-connected point are collected.
The direct-hanging type disturbance current injection device is not limited to structures such as mature converters in the prior art, the converters are required to inject broadband current signals into a wind power grid-connected system, and the direct-hanging type disturbance current injection device is not limited. Specifically, the topology structure of the direct-hanging type disturbance current injection device according to the embodiment of the present application is shown in fig. 2, which is composed of a Flying Capacitor (FC) three-level topology structure and a single-phase H-bridge cascade submodule power unit, and the number of each phase of H-bridge cascade submodule in fig. 2 is 4, but this is only an example and not a limitation.
Specifically, the direct-hanging type disturbance current injection device provided by the embodiment of the application adopts double closed-loop control, namely, the running state of the direct-hanging type disturbance current injection device is controlled by using a direct-current total voltage control method and a current control method, and in addition, a single-phase H bridge cascade submodule is controlled by using a voltage balance control method and a flying capacitor type three-level topological structure is controlled by using a direct-current voltage control method.
Specifically, the H bridge cascade submodule of the embodiment of the application adopts carrier phase shift modulation, and the FC three-level power unit adopts nearest level approach modulation; the switching function of the FC three-level power unit has the following relation with the modulation reference signal of the H-bridge cascade submodule power unit:
wherein u is chjref Phase voltages for H-bridge cascaded submodule power cells, u jref For the direct hanging disturbance current injection device to output voltage reference value S FCj Switching function for FC three-level power cell, u dc And the DC bus voltage of the FC three-level power unit.
It should be noted that, the control method and the modulation method are all mature methods in the prior art, and are not described herein again, and in addition, the embodiments of the present application are not limited to the control method and the modulation method, and are not limited herein.
Specifically, as shown in fig. 3, the process of controlling the direct-hanging type disturbance current injection device to inject the broadband current signal into the wind power grid system is performed by steps S21 to S23, which is specifically as follows:
step S21: and obtaining a given broadband current signal based on a power spectrum of the random binary sequence and a preset multiple of rated current of the direct-hanging type disturbance current injection device.
Specifically, the power spectrum of the random binary sequence can be expressed as:
where q is the frequency number of the power spectrum, a is the signal amplitude, and N is the signal length.
Setting the amplitude of a given broadband current signal, wherein the value range is 1% -5% of the rated current of the system, and obtaining the given broadband current signal according to the formula (2) and the amplitude.
Step S22: and superposing the given broadband current signal and the direct-current side total voltage control output signal as a current control reference value.
Step S23: after the current loop controller and modulation, the direct-hanging type disturbance current injection device injects a broadband current signal into the wind power grid-connected system.
It should be noted that, in the direct-hanging type disturbance current injection device of the embodiment of the present application, the wind power grid-connected system needs to inject a broadband current signal, and the control method of the direct-hanging type disturbance current injection device is double closed loop control, so that the broadband current signal needs to be obtained in step S22 and step S23, and if the direct-hanging type disturbance current injection device adopts other control methods, the step S22 and step S23 can also be adaptively transplanted.
Step S12: based on the collected voltage and current signals at the grid-connected point, a system admittance-frequency characteristic curve is obtained, an admittance-frequency characteristic expression of the system is identified, and the frequency and damping ratio of each mode of the system are calculated.
Specifically, in order to obtain the system oscillation mode under the injection of the broadband current signal, the embodiment of the present application needs to perform spectrum analysis on the voltage signal and the current signal, as shown in fig. 4, step S12 is performed by steps S31 to S34, as follows:
step S31: and carrying out frequency spectrum analysis on the collected voltage and current signals at the grid-connected point to obtain voltage phasors and current phasors under each frequency component, and calculating the system admittance value under each frequency component.
The embodiment of the application utilizes fast Fourier transform (Fast Fourier Transform, FFT) to carry out spectrum analysis on the sampled voltage and current signals to obtain voltage phasors under each frequency componentAnd current phasor->And calculates the system admittance value at each frequency component.
Step S32: and respectively connecting the real part and the imaginary part of the system admittance under each frequency component into a curve to obtain a system admittance-frequency characteristic curve.
Step S33: and identifying the admittance-frequency characteristic curve of the system by adopting a transfer function identification method to obtain an admittance-frequency characteristic expression of the system.
Specifically, a transfer function identification method is adopted to identify a system admittance-frequency characteristic curve, namely the following optimization problem is solved:
wherein Y (jω) is an actual value of the system admittance-frequency characteristic, Y eq (jω) is an identification value of the system admittance-frequency characteristic.
Step S34: and (3) enabling the admittance-frequency characteristic expression of the system to be zero, obtaining a plurality of zero points of the admittance-frequency characteristic expression of the system, and calculating the frequency and damping ratio of each oscillation mode based on the zero points.
Specifically, let Y eq (s) =0, zero s of the system admittance-frequency characteristic expression is calculated i ＝α i ±jω i And (3) carrying out stability judgment according to the real part and the imaginary part of each zero point to obtain a plurality of oscillation modes. Calculating the frequency f of the oscillation mode according to the following formula i And damping ratio xi i 。
Step S13: and setting the mode with the damping ratio smaller than the preset damping value as an attack mode according to the frequency and the damping ratio of each mode of the system, and sequencing the attack modes according to the damping ratio.
Specifically, in all oscillation modesSelecting damping ratio smaller than preset damping valueδAll oscillation modes in min are taken as attack modes, and the number is N; ordering the attack modes according to the damping ratio so that ζ is 1 ≤ξ 2 ≤...≤ξ n ≤...≤ξ N 。
Step S14: according to the sequence of the attack modes, the attack current in each attack mode is sequentially injected, each attack current continuously attacks for a preset time, whether the grid-connected current of the wind power plant has a divergent trend or not is monitored in the attack time of each attack current, if the grid-connected current of the wind power plant has the divergent trend, the attack is successful, and otherwise, the attack is carried out again by using the attack current in the next attack mode.
Specifically, it is assumed that after a broadband current signal is currently injected and a voltage and current signal is acquired, three attack modes (attack mode #1, attack mode #2 and attack mode #3 are sequenced as attack mode # 1- & gt, attack mode # 2- & gt, attack is performed by using the attack current #1 under the attack mode #1, if the grid-connected current of the wind farm has no divergence tendency in the attack process of the attack current #1, the attack is failed by using the attack current #2 under the attack mode #2, if the grid-connected current of the wind farm has no divergence tendency in the attack process of the attack current #2, the attack is failed by using the attack current #3 under the attack mode #3, and if the grid-connected current of the wind farm has no divergence tendency in the attack process of the attack current #3, the attack is failed.
Specifically, as shown in fig. 5, the process of obtaining the attack current in each attack mode includes steps 41 to 45, as follows:
step S41: the frequency of the current attack mode is taken as the frequency of a given current disturbance signal.
Step S42: and obtaining the amplitude of the given current disturbance signal according to the capacity of the direct-hanging disturbance current injection device and the admittance actual value of the current attack mode.
Specifically, according to a system admittance-frequency characteristic curve, an admittance actual value of a current attack mode is obtained, and the amplitude of a given current disturbance signal is calculated according to the following formula:
wherein S is max Is the maximum output capacity of the direct-hanging type disturbance current injection device.
Step S43: and obtaining a given sinusoidal current disturbance signal according to the frequency of the given current disturbance signal and the amplitude of the given current disturbance signal.
Step S44: and superposing the given sinusoidal current disturbance signal and the direct-current side total voltage control output signal as a current loop reference value.
Step S45: after the current loop controller and modulation, the direct-hanging disturbance current injection device outputs attack current.
Specifically, after the attack current continues for the preset time, the amplitude of the given sinusoidal current disturbance signal is set to zero.
It should be noted that, in the embodiment of the present application, the direct-hanging type disturbance current injection device needs to inject the attack current into the wind power grid-connected system, and the control method of the direct-hanging type disturbance current injection device is double closed loop control, so that the attack current needs to be obtained in step S44 and step S45, and if the direct-hanging type disturbance current injection device adopts other control methods, the step S44 and the step S45 can also be adaptively transplanted.
Specifically, as shown in fig. 6, the process of monitoring whether the grid-connected current of the wind farm has a divergent trend includes steps S51 to S53, as follows:
step S51: the current signal at the point of the parallel network is measured in real time.
Step S52: and acquiring current data of the last second preset time interval at intervals of the second preset time interval, and calculating the damping ratio of the current signal with the frequency of the current attack mode.
Specifically, in the process of each attack current carrying out attack, within the preset time of continuous attack of the attack current, current data within the last Δt time is taken every a second preset time interval Δt, and the frequency f in the current signal is calculated by adopting a Prony algorithm i Is provided.
Step S53: and in the preset time of continuous attack of the attack current, if the damping ratio of the current signal with the frequency of the current attack mode is a negative value, judging that the grid-connected current of the wind power plant has a divergence trend.
Step S15: if the attack current in all the current attack modes is not successful, judging whether the wind power plant state and the power grid running state change or not in a first preset time interval, and returning to the step of controlling the direct hanging type disturbance current injection device to inject a broadband current signal into the wind power grid-connected system and collecting voltage and current signals at the grid-connected point until the attack is successful when the wind power plant state or the power grid running state changes.
Specifically, it is assumed that after the broadband current signal is currently injected and the voltage and current signals are collected, three attack modes exist, if attack current in the three attack modes fails, the wind farm state and the power grid running state may change, and when one of the wind farm state and the power grid running state changes, the broadband current signal is re-injected, the attack mode and the attack current are re-selected, and the attack is performed again.
Specifically, as shown in fig. 7, the process of determining whether the wind farm status and the grid operation status change in the first preset time interval includes steps S61 to S62, as follows:
step S61: monitoring the wind speed in a first preset time interval, and judging that the state of the wind power plant changes when the wind speed changes by more than a preset multiple of the rated wind speed.
Step S62: and if the state of the wind power plant is not changed within the first preset time interval, judging that the running state of the power grid is changed.
Specifically, if the wind speed change does not exceed the preset multiple of the rated wind speed within the first preset time interval, the running state of the power grid is determined to be changed.
Example 2
An embodiment of the present application provides a wind farm attack apparatus, as shown in fig. 8, including:
the acquisition module 1 is used for installing the direct-hanging type disturbance current injection device in parallel at the grid-connected point of the wind power plant, controlling the direct-hanging type disturbance current injection device to inject a broadband current signal into the wind power grid-connected system, and acquiring voltage and current signals at the grid-connected point; this module performs the method described in step S11 in embodiment 1, and will not be described here.
The computing module 2 is used for acquiring a system admittance-frequency characteristic curve based on the acquired voltage and current signals at the grid-connected point, identifying and obtaining an admittance-frequency characteristic expression of the system, and computing the frequency and damping ratio of each mode of the system; this module performs the method described in step S12 in embodiment 1, and will not be described here.
The ordering module 3 is used for setting the mode with the damping ratio smaller than the preset damping value as the attack mode according to the frequency and the damping ratio of each mode of the system, and ordering the attack modes according to the damping ratio; this module performs the method described in step S13 in embodiment 1, and will not be described here.
The attack module 4 is used for sequentially injecting attack currents in each attack mode according to the sequence of the attack modes, wherein each attack current continuously attacks for a preset time, monitoring whether the grid-connected current of the wind power plant has a divergent trend in the attack time of each attack current, if so, the attack is successful, otherwise, the attack is carried out again by using the attack current in the next attack mode; this module performs the method described in step S13 in embodiment 1, and will not be described here.
The circulating attack module 5 is used for judging whether the wind power plant state and the power grid running state change in a first preset time interval if the attack current in all the current attack modes is not successful, and returning to the step of controlling the direct hanging type disturbance current injection device to inject a broadband current signal into the wind power grid-connected system and collecting the voltage and current signals at the grid-connected point until the attack is successful when the wind power plant state or the power grid running state changes; this module performs the method described in step S14 in embodiment 1, and will not be described here.
Example 3
An embodiment of the present application provides a computer device, as shown in fig. 9, including: at least one processor 401, such as a CPU (Central Processing Unit ), at least one communication interface 403, a memory 404, at least one communication bus 402. Wherein communication bus 402 is used to enable connected communications between these components. The communication interface 403 may include a Display screen (Display) and a Keyboard (Keyboard), and the optional communication interface 403 may further include a standard wired interface and a wireless interface. The memory 404 may be a high-speed RAM memory (Ramdom Access Memory, volatile random access memory) or a non-volatile memory (non-volatile memory), such as at least one disk memory. The memory 404 may also optionally be at least one storage device located remotely from the aforementioned processor 401. Wherein the processor 401 may perform the wind farm attack method of embodiment 1. A set of program codes is stored in the memory 404, and the processor 401 calls the program codes stored in the memory 404 for executing the wind farm attack method of embodiment 1.
The communication bus 402 may be a peripheral component interconnect standard (peripheral component interconnect, PCI) bus or an extended industry standard architecture (extended industry standard architecture, EISA) bus, among others. Communication bus 402 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one line is shown in fig. 9, but not only one bus or one type of bus.
Wherein the memory 404 may include volatile memory (English) such as random-access memory (RAM); the memory may also include a nonvolatile memory (english: non-volatile memory), such as a flash memory (english: flash memory), a hard disk (english: hard disk drive, abbreviated as HDD) or a solid-state drive (english: SSD); memory 404 may also include a combination of the above types of memory.
The processor 401 may be a central processor (English: central processing unit, abbreviated: CPU), a network processor (English: network processor, abbreviated: NP) or a combination of CPU and NP.
Wherein the processor 401 may further comprise a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a Programmable Logic Device (PLD), or a combination thereof (English: programmable logic device). The PLD may be a complex programmable logic device (English: complex programmable logic device, abbreviated: CPLD), a field programmable gate array (English: field-programmable gate array, abbreviated: FPGA), a general-purpose array logic (English: generic array logic, abbreviated: GAL), or any combination thereof.
Optionally, the memory 404 is also used for storing program instructions. Processor 401 may invoke program instructions to implement the wind farm attack method as in embodiment 1 of the present application.
The embodiment of the application also provides a computer readable storage medium, and the computer readable storage medium stores computer executable instructions thereon, wherein the computer executable instructions can execute the wind farm attack method of the embodiment 1. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a Flash Memory (Flash Memory), a Hard Disk (HDD), or a Solid-State Drive (SSD); the storage medium may also comprise a combination of memories of the kind described above.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present application.
Claims (10)
1. A method of wind farm attack, comprising:
the method comprises the steps of installing a direct-hanging type disturbance current injection device in parallel at a grid-connected point of a wind power plant, controlling the direct-hanging type disturbance current injection device to inject a broadband current signal into a wind power grid-connected system, and collecting voltage and current signals at the grid-connected point; the direct-hanging type disturbance current injection device comprises a current transformer;
acquiring a system admittance-frequency characteristic curve based on the acquired voltage and current signals at the grid-connected point, identifying and obtaining an admittance-frequency characteristic expression of the system, and calculating the frequency and damping ratio of each mode of the system;
according to the frequency and the damping ratio of each mode of the system, setting the mode with the damping ratio smaller than a preset damping value as an attack mode, and sequencing the attack modes according to the damping ratio;
according to the sequence of the attack modes, sequentially injecting attack currents in each attack mode, continuously attacking for preset time, monitoring whether the grid-connected current of the wind power plant has a divergent trend in the attack time of each attack current, if so, successfully attacking, otherwise, carrying out attack again by using the attack current in the next attack mode;
if the attack current in all the current attack modes is not successful, judging whether the wind power plant state and the power grid running state change or not in a first preset time interval, and returning to the step of controlling the direct hanging type disturbance current injection device to inject a broadband current signal into the wind power grid-connected system and collecting voltage and current signals at the grid-connected point until the attack is successful when the wind power plant state or the power grid running state changes.
2. A method of wind farm attack according to claim 1, wherein,
the direct-hanging type disturbance current injection device is composed of a flying capacitor type three-level topological structure and a single-phase H-bridge cascading submodule power unit;
the running state of the direct-hanging type disturbance current injection device is controlled by using a direct-current total voltage control method and a current control method, the single-phase H bridge cascade submodule is controlled by using a voltage balance control method, and the flying capacitor type three-level topological structure is controlled by using a direct-current voltage control method.
3. The method for attacking a wind farm according to claim 2, wherein said controlling said on-hook disturbance current injection means to inject a broadband current signal into a wind grid-connected system comprises:
obtaining a given broadband current signal based on a power spectrum of a random binary sequence and a preset multiple of rated current of a direct-hanging type disturbance current injection device;
superposing a given broadband current signal and a DC side total voltage control output signal as a current control reference value;
after the current loop controller and modulation, the direct-hanging type disturbance current injection device injects a broadband current signal into the wind power grid-connected system.
4. The method for attacking a wind farm according to claim 1, wherein the process of obtaining a system admittance-frequency characteristic curve based on the collected voltage and current signals at the grid-connected point, identifying an admittance-frequency characteristic expression of the system, and calculating the frequency and damping ratio of each mode of the system comprises the following steps:
performing frequency spectrum analysis on the collected voltage and current signals at the grid-connected point to obtain voltage phasors and current phasors under each frequency component, and calculating a system admittance value under each frequency component;
connecting the real part and the imaginary part of the system admittance under each frequency component into a curve respectively to obtain a system admittance-frequency characteristic curve;
identifying the admittance-frequency characteristic curve of the system by adopting a transfer function identification method to obtain an admittance-frequency characteristic expression of the system;
and enabling the admittance-frequency characteristic expression of the system to be zero, obtaining a plurality of zero points of the admittance-frequency characteristic expression of the system, and calculating the frequency and damping ratio of each oscillation mode based on the zero points.
5. The method of wind farm attack according to claim 4, wherein the process of deriving an attack current for each attack modality comprises:
taking the frequency of the current attack mode as the frequency of a given current disturbance signal;
obtaining the amplitude of a given current disturbance signal according to the capacity of the direct-hanging disturbance current injection device and the admittance actual value of the current attack mode;
obtaining a given sinusoidal current disturbance signal according to the frequency of the given current disturbance signal and the amplitude of the given current disturbance signal;
superposing a given sinusoidal current disturbance signal and a direct-current side total voltage control output signal as a current loop reference value;
after the current loop controller and modulation, the direct-hanging disturbance current injection device outputs attack current.
6. A method of wind farm attack according to claim 1, wherein the process of monitoring whether there is a tendency for wind farm grid-tie current to diverge comprises:
measuring current signals at the point of connection in real time;
acquiring current data of the last second preset time interval every second preset time interval, and calculating the damping ratio of a current signal with the frequency of the current attack mode;
and in the preset time of continuous attack of the attack current, if the damping ratio of the current signal with the frequency of the current attack mode is a negative value, judging that the grid-connected current of the wind power plant has a divergence trend.
7. The method of claim 1, wherein the step of determining whether the wind farm status and the grid operation status change within a first predetermined time interval comprises:
monitoring wind speed in a first preset time interval, and judging that the state of the wind power plant changes when the wind speed changes by more than a preset multiple of the rated wind speed;
and if the state of the wind power plant is not changed within the first preset time interval, judging that the running state of the power grid is changed.
8. A wind farm attack apparatus, comprising:
the acquisition module is used for installing the direct-hanging type disturbance current injection device in parallel at the grid-connected point of the wind power plant, controlling the direct-hanging type disturbance current injection device to inject a broadband current signal into the wind power grid-connected system, and acquiring voltage and current signals at the grid-connected point; the direct-hanging type disturbance current injection device comprises a current transformer;
the calculation module is used for acquiring a system admittance-frequency characteristic curve based on the acquired voltage and current signals at the grid-connected point, identifying and obtaining an admittance-frequency characteristic expression of the system, and calculating the frequency and damping ratio of each mode of the system;
the ordering module is used for setting the mode with the damping ratio smaller than a preset damping value as an attack mode according to the frequency and the damping ratio of each mode of the system, and ordering the attack modes according to the damping ratio;
the attack module is used for sequentially injecting attack currents in each attack mode according to the sequence of the attack modes, wherein each attack current continuously attacks for a preset time, monitoring whether the grid-connected current of the wind power plant has a divergent trend in the attack time of each attack current, if so, the attack is successful, otherwise, the attack is carried out again by using the attack current in the next attack mode;
and the circulating attack module is used for judging whether the wind power plant state and the power grid running state change within a first preset time interval if the attack current in all the current attack modes is not successful, and returning to the step of controlling the direct hanging type disturbance current injection device to inject a broadband current signal into the wind power grid-connected system and collecting the voltage and current signals at the grid-connected point until the attack is successful when the wind power plant state or the power grid running state changes.
9. A computer device, comprising: at least one processor, and a memory communicatively coupled to the at least one processor, wherein the memory stores instructions executable by the at least one processor to cause the at least one processor to perform the wind farm attack method of any of claims 1-7.
10. A computer readable storage medium having stored thereon computer instructions for causing the computer to perform the wind farm attack method according to any of claims 1-7.
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