Ac-dc complementary resonance detection method and device, storage medium and computer device

Abstract

The application provides an alternating current-direct current complementary resonance detection method and device, a storage medium and computer equipment. The method comprises the following steps: obtaining a system stability parameter model of a direct current power transmission system when a complementary resonance condition is met; the complementary resonance condition is that the frequency of an alternating current side is a first frequency and the frequency of a direct current side is a second frequency; obtaining alternating current harmonic impedance and alternating current impedance phase angles of the alternating current side at the first frequency; obtaining direct current harmonic impedance and direct current impedance phase angles of the direct current side at the second frequency; respectively calculating a trigger angle curve and a commutation overlap angle curve of a converter working in a target power interval of the direct current side; using the system stability parameter model, calculating system stability parameters at different target powers; if the system stability parameters are less than 0, determining that there is a complementary resonance risk at the target power corresponding to the system stability parameters less than 0. The application can analyze the complementary harmonic risk in advance, which is beneficial to improving the system stability.

Description

Technical Field

[0001] This application relates to the field of DC power transmission technology, and in particular to an AC / DC complementary resonance detection method, device, storage medium, and computer equipment. Background Technology

[0002] When a conventional DC transmission system is in operation, based on the modulation effect of the converter, the harmonics on both sides of the converter (i.e., the DC side and the AC side) can be repeatedly transmitted to each other. The key to achieving this repeated transmission is the fundamental frequency impedance on the DC side and the second harmonic impedance on the AC side.

[0003] If the fundamental frequency impedance on the DC side is low, the fundamental frequency harmonic voltage will generate a large fundamental frequency harmonic current on the DC side. This current, after modulation by the converter, will generate a large second-sequence harmonic current on the AC side. If the second-sequence harmonic impedance on the AC side is high, the second-sequence harmonic current will generate a large second-sequence harmonic voltage. This results in a gradually increasing second-sequence harmonic component on the AC side and a gradually increasing power frequency component on the DC side during repeated transmission, leading to harmonic instability, i.e., AC / DC complementary resonance, and consequently, system instability. Currently, conventional complementary resonance detection is based on post-hoc analysis, which is not conducive to ensuring system stability. Summary of the Invention

[0004] Therefore, it is necessary to provide a method, device, storage medium, and computer equipment for detecting AC / DC complementary resonances that can analyze complementary harmonic risks in advance, in order to address the above-mentioned technical problems.

[0005] This application provides a method for detecting AC / DC complementary resonance, the method comprising:

[0006] Obtain the system stability parameter model of the DC transmission system when the complementary resonance condition is met; the complementary resonance condition is that the frequency on the AC side is the first frequency, the frequency on the DC side is the second frequency, and the sum of the second frequency and the power frequency is equal to the first frequency.

[0007] Obtain the AC harmonic impedance and AC impedance phase angle on the AC side at the first frequency;

[0008] Obtain the DC harmonic impedance and DC impedance phase angle on the DC side at the second frequency;

[0009] Calculate the firing angle curve and commutation overlap angle curve of the converter operating on the DC side within the target power range;

[0010] Using the system stability parameter model, the system stability parameters under different target powers are calculated based on the AC harmonic impedance, AC impedance phase angle, DC harmonic impedance, DC impedance phase angle, and the firing angle curve and commutation overlap angle curve within the target power range.

[0011] If the system stability parameter is less than 0, then it is determined that there is a risk of complementary resonance at the target power corresponding to the system stability parameter being less than 0.

[0012] In one embodiment, the system stability parameter model is as follows:

[0013]

[0014] Among them, Z acpx For positive-sequence AC harmonic impedance, Z acp Z is the sum of the positive-sequence AC harmonic impedance and the impedance of the transformer in the DC transmission system. acn Z is the sum of the negative-sequence AC harmonic impedance and the AC side impedance of the transformer in the DC transmission system. dcn denoted as DC-side impedance of the transformer, N as transformer turns ratio, A as transfer coefficient of the converter in the DC transmission system, α0 as converter firing angle, μ0 as converter commutation overlap angle, and X as transformer saturation coefficient.

[0015] In one embodiment, the firing angle curve and commutation overlap angle curve of the converter operating on the DC side within the target power range are calculated, including:

[0016] Using the lower limit of the target power range as the initial power, and according to the preset power step size, the firing angle and commutation overlap angle of the converter are calculated at different target powers until the target power is equal to the upper limit of the target power range.

[0017] In one embodiment, the lower limit of the target power range is 0.1 pu rated power, and the upper limit of the target power range is 1.2 pu rated power.

[0018] In one embodiment, the preset power step size is 0.05 pu rated power.

[0019] In one embodiment, the method further includes:

[0020] Obtain the first and second frequencies of the DC transmission system that satisfy the complementary resonance condition.

[0021] In one embodiment, the first frequency is 100Hz and the second frequency is 50Hz.

[0022] This application also provides an AC / DC complementary resonance detection device, comprising:

[0023] The model acquisition module is used to acquire the system stability parameter model of the DC transmission system when the complementary resonance condition is met; the complementary resonance condition is that the frequency on the AC side is the first frequency, the frequency on the DC side is the second frequency, and the sum of the second frequency and the power frequency is equal to the first frequency.

[0024] The AC side parameter acquisition module is used to acquire the AC harmonic impedance and AC impedance phase angle of the AC side at the first frequency.

[0025] The DC-side parameter acquisition module is used to acquire the DC harmonic impedance and DC impedance phase angle on the DC side at the second frequency.

[0026] The first calculation module is used to calculate the firing angle curve and commutation overlap angle curve of the converter on the DC side operating in the target power range, respectively.

[0027] The second calculation module is used to calculate the system stability parameters under different target powers by using the system stability parameter model, based on the AC harmonic impedance, AC impedance phase angle, DC harmonic impedance, DC impedance phase angle, and the firing angle curve and commutation overlap angle curve within the target power range.

[0028] The risk assessment module is used to determine whether there is a complementary resonance risk at the target power corresponding to the system stability parameter being less than 0.

[0029] This application also provides a storage medium storing computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to perform the steps of the AC / DC complementary resonance detection method as described in any of the above embodiments.

[0030] This application also provides a computer device, including: one or more processors, and memory;

[0031] The memory stores computer-readable instructions, which, when executed by one or more processors, perform the steps of the AC / DC complementary resonance detection method as described in any of the above embodiments.

[0032] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0033] The AC / DC complementary resonance detection method, apparatus, storage medium, and computer equipment provided in this application obtain the AC harmonic impedance and AC impedance phase angle of the AC side of the DC transmission system at the first frequency, and the DC harmonic impedance and DC impedance phase angle of the DC side at the second frequency. They then calculate the firing angle curve and commutation overlap angle curve of the converter operating within the target power range on the DC side. Using a system stability parameter model of the DC transmission system satisfying the complementary resonance condition of the AC side frequency being the first frequency and the DC side frequency being the second frequency, they calculate whether the system stability parameters are less than 0 under different target power conditions. If the system stability parameters are less than 0 at a certain target power, it can be determined that the DC transmission system has a complementary resonance risk at that target power. In other words, by obtaining the physical parameters of the DC transmission system under different conditions through pre-analysis and using the system stability parameter model for judgment, detection can be performed before a fault occurs, thus avoiding faults caused by complementary resonance in advance and contributing to the stability of system operation. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart illustrating an AC / DC complementary resonance detection method in one embodiment.

[0036] Figure 2 This is a block diagram of the AC / DC complementary resonant detection device in one embodiment;

[0037] Figure 3 This is a diagram of the internal structure of a computer device in one embodiment. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] like Figure 1 As shown, this application provides an AC / DC complementary resonance detection method, including:

[0040] Step S101: Obtain the system stability parameter model of the DC transmission system when the complementary resonance condition is met.

[0041] In this model, the complementary resonance condition is defined as follows: the frequency on the AC side is the first frequency, the frequency on the DC side is the second frequency, and the sum of the second frequency and the power frequency equals the first frequency. The system stability parameter model refers to the equivalent model that the DC transmission system would satisfy when the operating frequency meets the complementary resonance condition but complementary resonance does not occur. The first frequency is the AC side operating frequency commonly associated with complementary resonance faults, and the second frequency is the DC side operating frequency commonly associated with complementary resonance faults.

[0042] Based on the equivalent circuit of the system's positive feedback resonant circuit, the model of the negative sequence current on the secondary side of the transformer can be derived:

[0043] I acnt =e -(a+bj)

[0044] Among them, I acnt Let a+bj be the negative sequence current on the secondary side of the transformer, where a represents the real part of the change and b represents the imaginary part. a represents the forced decay component, and b represents the periodic component of the sinusoidal change. By introducing the first and second frequencies into the above model for simplification, the system stability parameter model can be obtained. Since the simplification methods used in the equivalent treatment differ, the obtained system stability parameter model may also differ. It can be derived based on the considerations of those skilled in the art regarding the parameters affecting system stability.

[0045] Step S102: Obtain the AC harmonic impedance and AC impedance phase angle on the AC side at the first frequency.

[0046] Step S103: Obtain the DC harmonic impedance and DC impedance phase angle on the DC side at the second frequency.

[0047] Step S104: Calculate the firing angle curve and commutation overlap angle curve of the converter operating on the DC side within the target power range.

[0048] The formula for calculating the firing angle of the converter is as follows:

[0049]

[0050] The formula for calculating the commutation overlap angle is as follows:

[0051]

[0052] Among them, U dc U is the DC side voltage. di0 The open-circuit voltage, X c For commutation reactance, I dcE11 is the rated AC valve-side line voltage, where E11 is the DC-side current. The target power is equal to the ratio of the DC-side voltage to the DC-side current.

[0053] Step S105: Using the system stability parameter model, calculate the system stability parameters under different target powers based on the AC harmonic impedance, AC impedance phase angle, DC harmonic impedance, DC impedance phase angle, and the firing angle curve and commutation overlap angle curve within the target power range.

[0054] The system stability parameters are calculated using the system stability parameter model. When the system stability parameters are greater than 0, the system is determined to have no complementary resonance risk; when the system stability parameters are less than 0, the system is determined to have complementary resonance risk.

[0055] Step S106: If the system stability parameter is less than 0, then it is determined that there is a risk of complementary resonance at the target power corresponding to the system stability parameter being less than 0.

[0056] The AC / DC complementary resonance detection method provided in this application obtains the AC harmonic impedance and AC impedance phase angle of the AC side of the DC transmission system at the first frequency, and the DC harmonic impedance and DC impedance phase angle of the DC side at the second frequency. It then calculates the firing angle curve and commutation overlap angle curve of the converter operating within the target power range on the DC side. Using a system stability parameter model of the DC transmission system satisfying the complementary resonance condition of the AC side frequency being the first frequency and the DC side frequency being the second frequency, it calculates whether the system stability parameter is less than 0 at different target power levels. If the system stability parameter is less than 0 at a certain target power, it can be determined that the DC transmission system has a complementary resonance risk at that target power. In other words, by obtaining the physical parameters of the DC transmission system under different conditions through pre-analysis and using the system stability parameter model for judgment, it avoids detection after a fault occurs, thus proactively mitigating faults caused by complementary resonance and improving the stability of system operation.

[0057] In one embodiment, the system stability parameter model is as follows:

[0058]

[0059] Among them, Z acpx For positive-sequence AC harmonic impedance, Z acp Z is the sum of the positive-sequence AC harmonic impedance and the impedance of the transformer in the DC transmission system. acn Z is the sum of the negative-sequence AC harmonic impedance and the AC side impedance of the transformer in the DC transmission system. dcndenoted as DC-side impedance of the transformer, N as transformer turns ratio, A as transfer coefficient of the converter in the DC transmission system, α0 as converter firing angle, μ0 as converter commutation overlap angle, and X as transformer saturation coefficient.

[0060] In one embodiment, the firing angle curve and commutation overlap angle curve of the converter operating on the DC side within the target power range are calculated, including:

[0061] Using the lower limit of the target power range as the initial power, and according to the preset power step size, the firing angle and commutation overlap angle of the converter are calculated at different target powers until the target power is equal to the upper limit of the target power range.

[0062] In this embodiment, starting from the initial power, the firing angle and commutation overlap angle are calculated for power at preset power step intervals. Then, for each power, the system stability parameter model is calculated when the AC side operates at the first target frequency and the DC side operates at the second target frequency. This analysis examines at which target power the DC transmission system has, the AC side operates at the first target frequency, and the DC side operates at the second target power, where there is a risk of complementary resonance. This approach avoids risky operating parameters, reduces the occurrence of complementary resonance faults in the DC transmission system, and improves system stability.

[0063] In one embodiment, the lower limit of the target power range is 0.1 pu rated power, and the upper limit of the target power range is 1.2 pu rated power.

[0064] In one embodiment, the preset power step size is 0.05 pu rated power.

[0065] In one embodiment, the method further includes:

[0066] Obtain the first and second frequencies of the DC transmission system that satisfy the complementary resonance condition.

[0067] When the architecture or operating environment of a DC transmission system changes, the first and second frequencies that satisfy the complementary resonance condition may also change. They need to be set according to the actual situation. It is necessary to obtain the currently set first and second frequencies to improve the accuracy of complementary resonance risk detection.

[0068] In one embodiment, the first frequency is 100Hz and the second frequency is 50Hz.

[0069] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0070] The text processing apparatus provided in the embodiments of this application is described below. The text processing apparatus described below and the text processing method described above can be referred to in correspondence.

[0071] like Figure 2 As shown, in one embodiment, this application also provides an AC / DC complementary resonance detection device 200, comprising:

[0072] The model acquisition module 201 is used to acquire the system stability parameter model of the DC transmission system when the complementary resonance condition is met; the complementary resonance condition is that the frequency on the AC side is the first frequency, the frequency on the DC side is the second frequency, and the sum of the second frequency and the power frequency is equal to the first frequency.

[0073] The AC side parameter acquisition module 202 is used to acquire the AC harmonic impedance and AC impedance phase angle of the AC side at the first frequency.

[0074] The DC side parameter acquisition module 203 is used to acquire the DC harmonic impedance and DC impedance phase angle of the DC side at the second frequency.

[0075] The first calculation module 204 is used to calculate the firing angle curve and commutation overlap angle curve of the converter operating on the DC side within the target power range, respectively.

[0076] The second calculation module 205 is used to calculate the system stability parameters under different target powers by using the system stability parameter model, based on the AC harmonic impedance, AC impedance phase angle, DC harmonic impedance, DC impedance phase angle, and the firing angle curve and commutation overlap angle curve within the target power range.

[0077] The risk assessment module 206 is used to determine whether there is a complementary resonance risk at the target power corresponding to when the system stability parameter is less than 0.

[0078] Each module in the aforementioned AC / DC complementary resonant detection device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0079] In one embodiment, this application also provides a storage medium storing computer-readable instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of any of the AC / DC complementary resonance detection methods described in the above embodiments.

[0080] In one embodiment, this application also provides a computer device storing computer-readable instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of any of the AC / DC complementary resonance detection methods described in the above embodiments.

[0081] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 3 As shown, the computer device includes a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements an AC / DC complementary resonance detection method. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0082] Those skilled in the art will understand that the structure shown in Figure Y is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or may combine certain components, or may have different component arrangements.

[0083] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0084] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0085] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0086] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0087] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting AC / DC complementary resonance, characterized in that the method... include: Obtain the system stability parameter model of the DC transmission system when the complementary resonance condition is met; The complementary resonance condition is that the frequency on the AC side is the first frequency, the frequency on the DC side is the second frequency, and the sum of the second frequency and the power frequency is equal to the first frequency. Obtain the AC harmonic impedance and AC impedance phase angle on the AC side at the first frequency; Obtain the DC harmonic impedance and DC impedance phase angle on the DC side at the second frequency; Calculate the firing angle curve and commutation overlap angle curve of the converter operating on the DC side within the target power range; Using the system stability parameter model, the system stability parameters under different target powers are calculated based on the AC harmonic impedance, AC impedance phase angle, DC harmonic impedance, DC impedance phase angle, and the firing angle curve and commutation overlap angle curve within the target power range. If the system stability parameter is less than 0, then it is determined that there is a risk of complementary resonance at the target power corresponding to the system stability parameter being less than 0. The system stability parameter model is as follows: in, For positive-sequence AC harmonic impedance, This is the sum of the positive-sequence AC harmonic impedance and the impedance of the transformer in the DC transmission system. This is the sum of the negative-sequence AC harmonic impedance and the AC side impedance of the transformer in the DC transmission system. Here, N is the DC-side impedance of the transformer, N is the transformer turns ratio, and A is the transfer coefficient of the converter in the DC transmission system. The firing angle of the converter, X is the commutation overlap angle of the converter, and X is the transformer saturation coefficient.

2. The AC / DC complementary resonance detection method according to claim 1, characterized in that, Calculate the firing angle curve and commutation overlap angle curve of the converter operating on the DC side within the target power range, including: Using the lower limit of the target power range as the initial power, and according to the preset power step size, the firing angle and commutation overlap angle of the converter are calculated at different target powers until the target power is equal to the upper limit of the target power range.

3. The AC / DC complementary resonance detection method according to claim 2, characterized in that, The lower limit of the target power range is 0.1 pu rated power, and the upper limit of the target power range is 1.2 pu rated power.

4. The AC / DC complementary resonance detection method according to claim 2, characterized in that, The preset power step size is 0.05 pu rated power.

5. The AC / DC complementary resonance detection method according to claim 1, characterized in that, Also includes: Obtain the first and second frequencies of the DC transmission system that satisfy the complementary resonance condition.

6. The AC / DC complementary resonance detection method according to any one of claims 1 to 5, characterized in that, The first frequency is 100Hz, and the second frequency is 50Hz.

7. An AC / DC complementary resonance detection device, characterized in that, include: The model acquisition module is used to acquire the system stability parameter model of the DC transmission system when the complementary resonance condition is met; The complementary resonance condition is that the frequency on the AC side is the first frequency, the frequency on the DC side is the second frequency, and the sum of the second frequency and the power frequency is equal to the first frequency. The AC side parameter acquisition module is used to acquire the AC harmonic impedance and AC impedance phase angle of the AC side at the first frequency. The DC-side parameter acquisition module is used to acquire the DC harmonic impedance and DC impedance phase angle on the DC side at the second frequency. The first calculation module is used to calculate the firing angle curve and commutation overlap angle curve of the converter on the DC side operating within the target power range, respectively. The second calculation module is used to calculate the system stability parameters under different target powers by using the system stability parameter model, based on the AC harmonic impedance, AC impedance phase angle, DC harmonic impedance, DC impedance phase angle, and the firing angle curve and commutation overlap angle curve within the target power range. The risk assessment module is used to determine whether there is a complementary resonance risk at the target power corresponding to when the system stability parameter is less than 0. The system stability parameter model is as follows: in, For positive-sequence AC harmonic impedance, This is the sum of the positive-sequence AC harmonic impedance and the impedance of the transformer in the DC transmission system. This is the sum of the negative-sequence AC harmonic impedance and the AC side impedance of the transformer in the DC transmission system. Here, N is the DC-side impedance of the transformer, N is the transformer turns ratio, and A is the transfer coefficient of the converter in the DC transmission system. The firing angle of the converter, X is the commutation overlap angle of the converter, and X is the transformer saturation coefficient.

8. A storage medium, characterized in that: The storage medium stores computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to perform the steps of any of the AC / DC complementary resonance detection methods as claimed in claims 1 to 6.

9. A computer device, characterized in that, include: One or more processors, and memory; The memory stores computer-readable instructions, which, when executed by one or more processors, perform the steps of any one of the AC / DC complementary resonance detection methods as claimed in claims 1 to 6.

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