Restart optimization method of converter valve, electronic equipment and computer readable storage medium

Abstract

The invention relates to the technical field of converter valves, and particularly provides a converter valve restart optimization method, electronic equipment and a computer readable storage medium, and the method comprises the steps: carrying out the vibration analysis of a converter valve, and determining a vibration value of the converter valve under a power restoration condition; constructing vibration characteristics of the converter valve based on the vibration signal of the converter valve; determining a target current control coefficient based on the dissipated energy accumulation function of the converter valve; and determining a target control level based on the target current control coefficient, the vibration value and the vibration characteristics, and inputting a control signal under the target control level to the converter valve. In this way, the converter valve restart characteristic can be optimized, and the safety and stability of a power transmission system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of converter valves, and in particular to a restart optimization method of a converter valve, an electronic device, and a computer-readable storage medium. Background Art

[0002] In the HVDC transmission system, the converter valve needs to be shut down for maintenance regularly. After the maintenance is completed, it needs to be restarted (or restored) and put back into the grid. However, during the restoration process, the converter valve may cause a secondary impact on the transmission system due to a fault, and in severe cases, it may even cause system instability.

[0003] At present, it is necessary to optimize the fluctuating operating characteristics of the converter valve during the restart process to ensure the safety and stability of the power transmission system. However, due to the complex operating conditions of the converter valve during the power restoration process, it is still impossible to improve the restart problem of the converter valve.

[0004] Therefore, how to optimize the restart of the converter valve to ensure the safety and stability of the transmission system has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the present invention provides a restart optimization method of a converter valve, an electronic device and a computer-readable storage medium, which can optimize the restart characteristics of the converter valve and improve the safety and stability of the power transmission system.

[0006] In order to solve the above technical problems, on the one hand, the present invention provides a restart optimization method for a converter valve, comprising: performing vibration analysis on the converter valve to determine the vibration value of the converter valve under power-on conditions; constructing the vibration characteristics of the converter valve based on the vibration signal of the converter valve; determining the target current control coefficient based on the dissipated energy accumulation function of the converter valve; determining the target control level based on the target current control coefficient, the vibration value and the vibration characteristics, and inputting the control signal under the target control level to the converter valve.

[0007] According to some embodiments of the present invention, the target current control coefficient includes a target control proportional coefficient and a target control time coefficient. The step of determining the target control level based on the target current control coefficient, the vibration value and the vibration characteristic includes: determining the target control level based on the target current control coefficient, the vibration value and the vibration characteristic using the following formula (1):

[0008] u=-f*han(a c ,c*z(t),K r , T r ) Formula (1)

[0009] In the above formula (1), u refers to the target control level, f refers to the external disturbance value, han refers to the feedback function, and ac refers to the vibration value, c refers to the compensation factor, z(t) refers to the vibration characteristic, K r Refers to the target control proportional coefficient, T r Refers to the target control time coefficient.

[0010] According to some embodiments of the present invention, the vibration value of the converter valve under the power-on condition is expressed as follows:

[0011]

[0012] In the above formula (2), λ s refers to the saturation magnetostriction coefficient, L refers to the elongation length under the action of magnetic field expansion, ω refers to the fundamental angular frequency, B 1 -B k Refers to the magnetic induction intensity corresponding to the 1-kth iron core, B s refers to the saturation flux density, and n refers to the total amount of the core.

[0013] According to some embodiments of the present invention, the vibration characteristics include vibration energy characteristics, and the steps of constructing the vibration characteristics of the converter valve based on the vibration signal of the converter valve include: removing the low frequency in the vibration signal to obtain an initialization signal; based on the initialization signal, decomposing the vibration signal to obtain multiple intrinsic mode function components; subtracting the initialization signal from the intrinsic mode function components to obtain residual components; and generating vibration energy characteristics based on the intrinsic mode function components and the residual components.

[0014] According to some embodiments of the present invention, based on an initialization signal, a vibration signal is decomposed to obtain a plurality of intrinsic mode function components, comprising the steps of: finding local extreme value points of the initialization signal; performing cubic spline function interpolation on the maximum and minimum values ​​of the initialization signal to generate upper and lower envelopes; determining the average values ​​of the upper and lower envelopes; and determining the intrinsic mode function components based on the average values ​​of the initialization signal and the upper and lower envelopes.

[0015] According to some embodiments of the present invention, the step of generating a vibration energy feature based on an intrinsic mode function component and a residual component includes: generating the vibration energy feature using the following formula (3):

[0016]

[0017] In the above formula (3), c i (t) refers to the intrinsic mode function component, r m (t) refers to the residual component corresponding to the mth initialization signal, and m refers to the total number of signals.

[0018] According to some embodiments of the present invention, the step of determining a target current control coefficient based on the dissipated energy accumulation function of the converter valve includes: constructing an extreme value form of the dissipated energy accumulation function based on the dissipated energy accumulation function; solving the extreme value form of the dissipated energy accumulation function using a particle swarm optimization algorithm to determine a target solution system of the current control coefficient; and determining the target current control coefficient based on the target solution system.

[0019] According to some embodiments of the present invention, based on the target solution system, the step of determining the target current control coefficient includes: substituting the target solution system into the dissipated energy accumulation function, and screening out the minimum solution system in the target solution system; screening out the solution system whose corresponding dissipated energy accumulation value is less than the dissipated energy accumulation value during the system fault recovery period in the minimum solution system as the candidate solution system; and using the current control coefficient corresponding to the minimum value in the candidate solution system as the target current control coefficient.

[0020] In a second aspect, an embodiment of the present invention provides an electronic device, comprising: a processor; and a memory, wherein computer program instructions are stored in the memory.

[0021] When the computer program instructions are executed by the processor, the processor executes the restart optimization method of the converter valve in the above technical solution.

[0022] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor executes the restart optimization method of the converter valve in the above technical solution.

[0023] The above technical solution of the present invention has at least one of the following beneficial effects: by analyzing the vibration characteristics of the converter valve under complex working conditions (hereinafter referred to as "power restoration working conditions") during the power restoration process, the vibration value and vibration characteristics under the power restoration working conditions are extracted to provide a basis for identifying the operating state of the power transmission system. In addition, combined with the influence of the converter valve current control parameters on the total cumulative dissipated energy of the system, the converter valve is restarted and optimized from the two aspects of the vibration characteristics and dissipated energy of the converter valve, so that the operating characteristics of the converter valve during the restart process can be optimized, and the safety and stability of the power transmission system can be improved.

[0024] In addition, a compensation factor is set to enhance the stability of the converter valve optimization and suppress external disturbances to obtain the final target control level. This can take into account the changes in the system topology during the restart fault and the impact of the switching of the control strategy, and more accurately track and optimize the characteristics of the system during the entire restart and fault process, further improving the optimization effect of the converter valve restart.

[0025] In addition, by utilizing the differences in the characteristic distribution of vibration in the time domain, frequency domain and energy domain under different operating conditions, the one-dimensional vibration time series is converted into a two-dimensional multi-feature spectrum in the time domain, frequency domain and energy domain from the perspective of multi-dimensional features. Then, the feature spectrum is fused through the convolutional neural network to obtain the fused vibration feature, so as to realize the recognition of the operating status of the converter valve based on the multi-feature spectrum library. In this way, on the one hand, the information utilization rate and feature richness can be guaranteed; on the other hand, it can avoid the loss of some feature information due to excessive reliance on historical experience, and improve the real-time and accuracy of data recognition.

[0026] In addition, by analyzing the influence of the current control parameters of the converter valve on the total cumulative dissipated energy of the system during the restart recovery process, and obtaining and adjusting the current control parameters with the goal of minimizing the cumulative dissipated energy of the system, a target current control coefficient that can minimize the impact on the system during the fault recovery period is obtained, so that the fluctuating operation characteristics of the converter valve during the restart process can be optimized to improve the safety and stability of the system. Moreover, in this embodiment, a particle swarm optimization algorithm is first used to determine the solution system of the binary equation system about the target current control coefficient, and then the target current control coefficient can be screened through simple numerical calculations and logical judgments. This method has a small amount of calculation and high optimization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A flowchart of a method for optimizing the restart of a converter valve according to an embodiment of the present invention;

[0028] Figure 2 A wiring diagram of a converter valve in a power transmission system according to an embodiment of the present invention;

[0029] Figure 3 A flowchart of the steps of constructing a vibration characteristic of a converter valve based on a vibration signal of the converter valve in a method for optimizing the restart of a converter valve according to an embodiment of the present invention;

[0030] Figure 4 It is a flowchart of the step of determining the target current control coefficient based on the dissipated energy accumulation function of the converter valve in the restart optimization method of the converter valve according to the embodiment of the present invention;

[0031] Figure 5 Schematic diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The specific implementation of the present invention will be further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0033] In the HVDC transmission system, the converter valve needs to be shut down for maintenance regularly. After the maintenance is completed, it needs to be restarted (or restored) and put back into the grid. However, during the restoration process, the converter valve may cause a secondary impact on the transmission system due to a fault, and in severe cases, it may even cause system instability.

[0034] Specifically, when a DC line fault occurs, the rectifier station will enter the phase-shift trigger and de-ionization state to wait for the fault to be cleared and restart. If the fault in the DC line is not cleared at this time, the high DC impact current generated when the converter valve restarts will cause a secondary impact on the transmission system, which will cause the power angle of the synchronous generator on the rectifier side to swing greatly, and in severe cases may even cause the transmission system to become unstable.

[0035] At present, it is necessary to optimize the fluctuating operating characteristics of the converter valve during the restart process to ensure the safety and stability of the power transmission system. However, due to the complex operating conditions of the converter valve during the power restoration process, it is still impossible to improve the restart problem of the converter valve.

[0036] Therefore, how to optimize the restart of the converter valve to ensure the safety and stability of the transmission system has become a technical problem that needs to be solved urgently.

[0037] In order to solve the above technical problems, the embodiment of the present application proposes a restart optimization method for the converter valve, which analyzes the vibration characteristics of the converter valve under complex working conditions during the power restoration process (hereinafter referred to as "power restoration conditions"), extracts the vibration value and vibration characteristics under the power restoration conditions, and provides a basis for identifying the operating state of the power transmission system. In addition, combined with the influence of the converter valve current control parameters on the total cumulative dissipated energy of the system, the converter valve is restarted and optimized from the two aspects of the converter valve's vibration characteristics and dissipated energy, which can achieve the optimization of the converter valve's operating characteristics during the restart process and improve the safety and stability of the power transmission system.

[0038] The restart optimization method of the converter valve proposed in the embodiment of the present application is described in detail below. Figure 1 The following steps are shown.

[0039] Step 110: Perform vibration analysis on the converter valve to determine the vibration value of the converter valve under power restoration conditions.

[0040] By combining the vibration theory of the converter valve, the vibration value and the following vibration characteristics of the converter valve under the power-on condition can be determined, thereby accurately reflecting the current operating state of the converter valve and preparing for the subsequent restart optimization of the converter valve. The specific vibration analysis process is described in detail in the following embodiment and will not be described here for the time being.

[0041] Step 120: constructing a vibration characteristic of the converter valve based on the vibration signal of the converter valve.

[0042] In one embodiment, the vibration characteristics may include vibration energy characteristics, and the vibration energy characteristics of the converter valve may be generated by utilizing the characteristic distribution of vibration in the energy domain under different operating conditions.

[0043] In one embodiment, the vibration characteristics may also include fused vibration characteristics. The differences in the characteristic distribution of vibration in the time domain, frequency domain and energy domain under different operating conditions can be used to convert the one-dimensional vibration time series into a two-dimensional multi-feature spectrum in the time domain, frequency domain and energy domain from the perspective of multi-dimensional characteristics, and then the feature spectrum is fused through the convolutional neural network to obtain the fused vibration characteristics, so as to realize the identification of the operating state of the converter valve based on the multi-feature spectrum library. In this way, on the one hand, the information utilization rate and feature richness can be guaranteed; on the other hand, it can avoid excessive reliance on historical experience that may lead to the loss of some feature information, thereby improving the real-time and accuracy of data identification.

[0044] Step 130: Determine a target current control coefficient based on the dissipated energy accumulation function of the converter valve.

[0045] The dissipated energy accumulation function is used to represent the influence of the current control parameters of the converter valve on the accumulated dissipated energy of the system during the restart and recovery process of the power transmission system, or to generate the dissipated energy accumulation function by analyzing the influence of the current control parameters on the accumulated dissipated energy. According to the dissipated energy accumulation function, the current appropriate current control coefficient (i.e., the target current control coefficient) can be determined to optimize the restart process of the converter valve in the power transmission system in a targeted manner. In one example, the current control parameter may include a proportional coefficient and a time coefficient of the current control link.

[0046] In one embodiment, the current control parameter corresponding to the minimum value in the dissipated energy accumulation function can be selected as the target current control coefficient, and the target current control coefficient is the optimal control parameter that can minimize the impact on the system during fault recovery. The construction process of the dissipated energy accumulation function is described in detail in the following embodiments and is not described here for the time being.

[0047] Step 140: Determine a target control level based on the target current control coefficient, the vibration value, and the vibration characteristic, and input a control signal at the target control level to the converter valve.

[0048] This embodiment can work together on restart optimization from two aspects of vibration characteristics and dissipated energy, and optimize the power transmission system by adjusting the target control level, which can improve the restart optimization effect of the converter valve and improve the safety and stability of the power transmission system.

[0049] In one embodiment, the target current control coefficient may include a target control proportional coefficient and a target control time coefficient. The above step 140, i.e., the step of determining the target control level based on the target current control coefficient, the vibration value and the vibration characteristics, may specifically include: determining the target control level based on the target current control coefficient, the vibration value and the vibration characteristics using the following formula (1):

[0050] u=-f*han(a c ,c*z(t),K r , T r ) Formula (1)

[0051] In the above formula (1), u refers to the target control level, f refers to the external disturbance value, han refers to the feedback function, and a c refers to the vibration value, c refers to the compensation factor, z(t) refers to the vibration characteristic, K r Refers to the target control proportional coefficient, T r Refers to the target control time coefficient.

[0052] It can be understood that the external disturbance value f can be detected by detection technology, and the compensation factor c can be set according to actual conditions, which is not limited here.

[0053] This embodiment sets a compensation factor to enhance the stability of the converter valve optimization and suppress external disturbances to obtain the final target control level. It can take into account the changes in the system topology during the restart fault process and the impact of the switching of the control strategy, and more accurately track and optimize the characteristics of the system during the entire restart fault process, further improving the optimization effect of the converter valve restart. Specifically, this embodiment can significantly reduce the peak value of the DC impact current and the maximum peak-to-valley difference of the generator power angle that appear in the initial stage of restarting the fault, and can achieve good optimization effects during multiple restarts during the fault, which can better meet the requirements of actual engineering for optimizing fault characteristics.

[0054] The above steps 110, 120 and 130 are described in detail below.

[0055] Firstly, the re-energizing conditions and vibration characteristics of the converter valve are introduced.

[0056] like Figure 2 As shown, Figure 2The wiring diagram of the converter valve in the power transmission system is shown in the figure. The converter valve is connected to the AC grid through the knife switch V1, which is used to convert AC power into DC power and transmit DC power through the knife switches V2, V3 and the transmission line. The power restoration working conditions of the converter valve may include charging closing, on-load tap changer (OLTC) action, converter valve unlocking and power transmission, etc. Among them, under different working conditions during the power restoration process, the conduction states of knife switches V1, V2, V3 and converter valves are different, which are introduced one by one below.

[0057] Under the charging closing condition, the knife switch V1 is closed (i.e., the conducting state), the knife switches V2 and V3 are disconnected (i.e., the shut-off state), and the converter valve is locked (i.e., the shut-off state). The charging closing condition is that the converter valve switches from the shutdown state to the voltage state. At this time, the grid-side winding is connected to the AC grid. Since the converter valve is locked, no load current flows through the converter transformer winding (including the valve-side winding and the grid-side winding).

[0058] When the on-load tap changer is in operation, the switch V1 is closed, the switches V2 and V3 are disconnected, and the converter valve is locked. At this time, the converter transformer winding still has no load current flowing through it and operates in a no-load state.

[0059] Under the condition of the converter valve unlocking and transmitting power, the knife gates V1, V2, and V3 are closed, and the converter valve is unlocked (i.e., in the on state), and current begins to flow in the transmission line. It can be understood that the converter valve is usually in a locked state before starting to prevent power conversion under inappropriate conditions. Unlocking the converter valve means putting it in an operational state, allowing it to start controlling the conversion of power.

[0060] From the above content, it can be seen that in the charging closing condition and the on-load tap changer operation condition, both of them work in the no-load operation state of the converter valve, and the converter valve unlocking and power transmission condition occurs during the switching from the no-load state to the load state. It can be understood that in order to achieve the effect of converter valve restart optimization, this application mainly targets the charging closing condition.

[0061] The vibration characteristics under the charging closing condition are introduced below. The vibration under the charging closing condition is similar to the vibration under the no-load test condition, which is mainly manifested as the iron core vibration of the box. Therefore, when analyzing the vibration under the charging closing condition, the influence of the iron core vibration is mainly considered.

[0062] In one embodiment, the vibration value of the converter valve in step 110 under the power-on condition can be specifically expressed as follows:

[0063]

[0064] In the above formula (2), λ s refers to the saturation magnetostriction coefficient, L refers to the elongation length under the action of magnetic field expansion, ω refers to the fundamental angular frequency, B 1-B k Refers to the magnetic induction intensity corresponding to the 1-kth iron core, B s refers to the saturation flux density, and n refers to the total amount of the core.

[0065] In one embodiment, the vibration characteristics include vibration energy characteristics. The vibration signal may be an original multi-frequency signal with rich frequencies. The multi-frequency vibration signal may be decomposed into single-frequency signals, and then the vibration energy characteristic distribution is extracted from each single-frequency signal to obtain the vibration energy characteristic. The above step 120, i.e., the step of constructing the vibration characteristics of the converter valve based on the vibration signal of the converter valve, is described in detail below. The specific processing steps are as follows: Figure 3 The following steps are shown.

[0066] Step 121: Remove the low frequency in the vibration signal to obtain an initialization signal.

[0067] Step 122: Based on the initialization signal, the vibration signal is decomposed to obtain a plurality of intrinsic mode function components.

[0068] In one embodiment, the above step 122 may specifically include: finding the local extreme point of the initialization signal. Performing cubic spline function interpolation on the maximum and minimum of the initialization signal to generate upper and lower envelopes. Determining the average value of the upper and lower envelopes. Determining the intrinsic mode function component based on the average value of the initialization signal and the upper and lower envelopes.

[0069] In one example, the initialization signal and the average value of the upper and lower envelopes can be subtracted to obtain the intrinsic mode function component. For example, the initialization signal is s(t), the average value of the upper and lower envelopes is m(t), and the intrinsic mode function component is c(t), and the following relationship exists: c(t) = s(t) - m(t).

[0070] It can be understood that if the value obtained by subtracting the initialization signal from the average value of the upper and lower envelopes is not an intrinsic mode function component, the above step 122 can be re-executed to re-determine the intrinsic mode function component.

[0071] Step 123: Subtract the initialization signal from the intrinsic mode function component to obtain a residual component.

[0072] In one embodiment, after obtaining an intrinsic mode function component using step 122, it can be determined whether the number of extreme points of the residual component is greater than 2; if the number of extreme points is greater than 2, return to the above step 122 to continue decomposition; if the number of extreme points is less than or equal to 2, the decomposition is terminated to obtain all intrinsic mode function components.

[0073] Step 124: Generate a vibration energy signature based on the intrinsic mode function component and the residual component.

[0074] In one example, the step of generating a vibration energy feature based on the intrinsic mode function component and the residual component may include: generating the vibration energy feature using the following formula (3):

[0075]

[0076] In the above formula (3), c i (t) refers to the intrinsic mode function component, r m (t) refers to the residual component corresponding to the mth initialization signal, and m refers to the total number of signals.

[0077] In another embodiment, the vibration characteristics of the converter valve may also include fused vibration characteristics. The above step 120 may include: converting the one-dimensional vibration time series into a two-dimensional time domain, frequency domain, and energy domain multi-feature spectrum from the perspective of multi-dimensional characteristics, and then fusing the feature spectrum through a convolutional neural network to obtain a fused vibration feature. In other words, in addition to the vibration energy feature, the fused vibration feature also includes vibration time domain features and vibration frequency domain features. In this way, the advantages of computers in image recognition can be combined to ensure information utilization and feature richness, providing a good foundation for subsequent restart optimization.

[0078] The construction process of the vibration time domain feature map and the vibration frequency domain feature map is introduced in detail below.

[0079] The construction process of the vibration time domain feature map is mainly to transform the discrete one-dimensional vibration time domain sequence into a two-dimensional feature map through Gramian Angular Field (GAF) transformation and pseudo-color image processing. The detailed process of constructing the time domain feature map includes time domain signal scaling, coordinate system conversion, custom feature matrix calculation, and matrix pseudo-color processing as shown below.

[0080] "Time domain signal scaling" means: using the time series as the horizontal axis and the vibration amplitude as the vertical axis, scaling the vibration time domain sequence to the interval [-1, 1]. 1 , z 2 , ..., z n} as an example, the specific calculation method is shown in the following formula (4):

[0081]

[0082] In the above formula (4), z' refers to the scaled time domain sequence.

[0083] “Coordinate system conversion” refers to converting the scaled time domain sequence z' into polar coordinates. The specific conversion method is shown in the following equation (5):

[0084]

[0085] In the above formula (5), z'={z 1 ', z 2 ', ..., z n '}, θ i The amplitude of the scaled time series z' is retained in the form of angle in polar coordinates, t i Refers to the time point z in the time series z' i The timestamp of ' is used to form the radius r of the polar coordinates, and N refers to the number of all time points contained in the time series z'. Through the polar coordinate system conversion, the amplitude and time information in the time domain sequence z' has no information loss during the data conversion process.

[0086] "Custom matrix calculation" means: by defining a special inner product calculation method: or The Gram angle sum field (GASF) and the Gram angle difference field (GADF) are obtained, which are specifically shown in the following equation (6):

[0087]

[0088] It can be seen from the above formula (6) that the time order of the original sequence is retained on the diagonal elements from the upper left corner to the lower right corner. For the vibration signal with an original time series length of n, a series of n×n matrices are obtained after GAF transformation.

[0089] "Matrix pseudo-color processing" means: converting the values ​​of different elements in the matrix into grayscale values ​​of the grayscale image and corresponding them to different colors (i.e. performing pseudo-color processing), thereby converting the one-dimensional vibration time domain sequence into a two-dimensional vibration time domain feature map.

[0090] The construction process of the vibration frequency domain feature map is basically the same as that of the vibration time domain feature map. The difference is that before establishing the vibration frequency domain feature map, the vibration time domain sequence needs to be converted to the frequency domain through Fourier transform. Then, using a process similar to the above-mentioned vibration time domain feature map construction process, the frequency and corresponding amplitude information are saved in matrix form through Gram angular field transformation, and finally a two-dimensional vibration frequency domain feature map is formed through matrix pseudo-color processing.

[0091] The above method can accurately extract the features of the vibration time domain, frequency domain and energy domain characteristic maps of the converter valve, avoiding interference from the external environment and affecting the recognition of the operating status of the converter valve. Compared with the traditional classification and recognition method, the recognition accuracy of this method is greatly improved, thus laying a solid foundation for the optimization of the converter valve.

[0092] The above step 130, i.e., the step of determining the target current control coefficient based on the dissipated energy accumulation function of the converter valve, is described in detail below.

[0093] First, the construction process of the dissipated energy accumulation function is introduced.

[0094] The rectifier subsystem of the system generally adopts constant current control, and its output is the trigger lead angle β rec , which is related to the trigger angle α rec The relationship between is: rec =π-α rec The control equation on the rectifier side is shown in equation (7):

[0095]

[0096] In the above formula (7), α rec is the rectifier starting angle, I d-ref is the DC current command value on the rectifier side, i dc is the DC current measurement value.

[0097] Set the trigger pulse arrival time of the converter valve as the reference zero point, and the intersection of the phase voltage as the absolute zero point. When the converter valve is operating in normal working state, t p2Y and t p2Δ The trigger angle is the same, that is, α(t p2Y )=α(t p2Δ ). At this time P 2Y With P 2Δ The electrical angle difference is 30°, and the first conduction interval in a commutation cycle is [0, 30° / ω] (in terms of P 2Y is the reference zero point). When a fault occurs in the DC line, affected by the constant current controller, t p2Y and t p2Δ The trigger angles of P are different. 2Y With P 2Δ The angle difference will be 30°+α rec (t p2Y )+α rec (t p2Δ ). And the first conduction interval will become [0°, (30°+α rec (t p2Y )+α rec (t p2Δ )) / ω].

[0098] Converter valve trigger angle α rec is a function of time t. Therefore, during the fault period, in different conduction intervals of the converter valve, α rec The expression is the time-varying function α rec(t). Taking the D bridge as the conducting valve VT1 and VT6, and the Y bridge as the conducting valve VT1 and VT2 as an example, the Y bridge valve conduction time can be set as t p2Y , the D-bridge converter valve shut-off time is t p2Δ , corresponding to the above conduction interval, the trigger angle expressions corresponding to the start time and the end time are shown in the following formula (8) and formula (9) respectively:

[0099]

[0100] The time length corresponding to the above conduction interval is shown in the following formula (10):

[0101]

[0102] The above formula can be written as H(K r , T r ), which is about K r , T r The implicit function of .

[0103] YD bridge converter valve conduction time t p2Y , t p2Δ and the trigger angle α at the corresponding moment rec (t p2Y ), α rec (t p2Δ ) are as follows: p2Y =(0°+α rec (t p2Y )) / ω;t p2Δ =(30°+α rec (t p2Δ )) / ω.

[0104] From the above content, we can know that t p2Y , t p2Δ The proportional coefficient K of the constant current control link on the rectifier side r and time factor T r A transcendental equation containing an implicit function is formed. During the entire restart-fault and phase-shift triggering process, the cumulative value of the dissipated energy emitted by the synchronous generator on the rectifier side (i.e., the cumulative function of the dissipated energy) is shown in the following equation (11):

[0105] W ∑ =∑W G ( n )(K r , T r , t P2Y , t P2Δ ) Formula (11)

[0106] In the above formula (11), n ​​represents the nth conduction interval.

[0107] The dissipated energy accumulation function refers to the constant current control proportional coefficient K of the rectifier side converter valve. r and time factor T r The process of determining the target current control coefficient using the dissipated energy accumulation function can be understood as the process of obtaining the optimal current control parameters of the system during fault recovery. r and T r The impact on the cumulative value of dissipated energy, combined with system operation constraints and first-wave smoothing requirements, can achieve targeted optimization of system characteristics.

[0108] The above step 130, i.e., the step of determining the target current control coefficient based on the dissipated energy accumulation function of the converter valve, is described in detail below. Figure 4 The following steps are shown:

[0109] Step 131: Based on the dissipated energy accumulation function, construct an extreme value formula of the dissipated energy accumulation function.

[0110] As an example, the dissipated energy accumulation function shown in the above formula (11) can be G The integrand is denoted as f n (t), and set the upper and lower limits of the integral of each interval to ζ n (K r , T r ) and ζ n+1 (K r , T r ), the cumulative energy dissipated by the system during fault recovery is W ∑ Current control coefficient K r and T r The partial derivative expression of is shown in formula (12):

[0111]

[0112] From the above formula (12), we can see that when W ∑ When there is an extreme value, the extreme value formula is as shown in formula (13):

[0113]

[0114] Step 132: using a particle swarm optimization algorithm to solve the extreme value form of the dissipated energy accumulation function, and determine the target solution system of the current control coefficient.

[0115] The particle swarm optimization algorithm is used to solve the extreme value form of the dissipated energy accumulation function shown in the above formula (13) to determine the set of solutions of the current control coefficient, that is, the target solution system. Among them, the particle swarm optimization algorithm (Particle Swarm Optimization, PSO) is a conventional algorithm in the field of data optimization, and this application does not introduce the particle swarm optimization algorithm in detail.

[0116] Step 133: Determine the target current control coefficient based on the target solution system.

[0117] In one embodiment, the current control parameter corresponding to the solution system that meets the optimization condition and has the smallest value may be selected from the target solution system as the target current control coefficient.

[0118] Specifically, in one example, the above step 133, i.e., the step of determining the target current control coefficient based on the target solution system, may specifically include: substituting the target solution system into the dissipated energy accumulation function, and screening the minimum solution system in the target solution system. Screening out the solution system whose corresponding dissipated energy accumulation value is less than the dissipated energy accumulation value during the system fault recovery period in the minimum solution system as the candidate solution system. The current control coefficient corresponding to the minimum value in the candidate solution system is used as the target current control coefficient.

[0119] In one example, in the above-mentioned process of screening the target current control coefficient, the following two factors can also be considered. First, in practical applications, the target current control parameter can avoid using boundary values ​​to prevent the system from entering a critical stable state when the current control coefficient adopts the boundary value of the system constraint range, resulting in poor anti-interference ability. Second, the change in the target current control coefficient and the current current control coefficient can be controlled to be within a preset fluctuation range to prevent the change in the target current control coefficient from exceeding the preset fluctuation range, causing the system to become unstable, the operating characteristics to deteriorate, and the equipment to be damaged. In other words, even if the target current control coefficient meets the above-mentioned condition of the minimum cumulative value of dissipated energy, if the change exceeds the preset fluctuation range, it should be regarded as an invalid solution. It can be understood that the preset fluctuation range can be set according to actual conditions and is not limited here.

[0120] This embodiment analyzes the influence of the current control parameters of the converter valve on the total cumulative dissipated energy of the system during the restart recovery process, and obtains and adjusts the current control parameters with the goal of minimizing the cumulative dissipated energy of the system, thereby obtaining a target current control coefficient that can minimize the impact on the system during the fault recovery period, thereby optimizing the fluctuating operating characteristics of the converter valve during the restart process to improve the safety and stability of the system. In addition, this embodiment first uses a particle swarm optimization algorithm to determine the solution system of the binary equation system about the target current control coefficient, and then screens the target current control coefficient through simple numerical calculations and logical judgments. This method has a small amount of calculation and high optimization efficiency.

[0121] An embodiment of the present invention also provides an electronic device, which includes a processor and a memory, wherein the memory stores at least one instruction or at least one program, and the at least one instruction or the at least one program is loaded and executed by the processor to implement the restart optimization method of the converter valve provided in the above method embodiment.

[0122] The memory can be used to store software programs and modules. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, application programs required for functions, etc.; the data storage area can store data created according to the use of the device, etc. In addition, the memory can include a high-speed random access memory and can also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other volatile solid-state storage devices. Accordingly, the memory can also include a memory controller to provide the processor with access to the memory.

[0123] In a specific embodiment, Figure 5 A schematic diagram of the structure of an electronic device for implementing an embodiment of the present invention is shown. The electronic device may be a computer terminal, a mobile terminal or other devices.

[0124] like Figure 5 As shown, an embodiment of the present invention provides an electronic device 500, including: a processor 501 and a memory 502, wherein computer program instructions are stored in the memory 502, wherein when the computer program instructions are executed by the processor, the processor 501 executes the restart optimization method of the converter valve as described in the above embodiment.

[0125] Furthermore, if Figure 5 As shown, the electronic device 500 further includes a network interface 503 , an input device 504 , a hard disk 505 , and a display device 506 .

[0126] The above-mentioned interfaces and devices can be interconnected through a bus architecture. The bus architecture can be a bus and bridge that can include any number of interconnected buses. Specifically, one or more central processing units (CPUs) represented by processor 501 and various circuits of one or more memories represented by memory 502 are connected together. The bus architecture can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits together. It can be understood that the bus architecture is used to achieve connection and communication between these components. In addition to the data bus, the bus architecture also includes a power bus, a control bus, and a status signal bus, which are all well known in the art, so they are not described in detail herein.

[0127] The network interface 503 can be connected to a network (such as the Internet, a local area network, etc.), obtain relevant data from the network, and save it in the hard disk 505.

[0128] The input device 504 can receive various instructions input by the operator and send them to the processor 501 for execution. The input device 504 can include a keyboard or a pointing device, such as a mouse, a trackball, a touch pad or a touch screen.

[0129] The display device 506 can display the result obtained by the processor 501 executing the instruction.

[0130] The memory 502 is used to store programs and data necessary for the operation of the operating system, as well as data such as intermediate results during the calculation process of the processor 501.

[0131] It is understood that the memory 502 in the embodiment of the present invention may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. The memory 502 of the apparatus and method described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0132] In some implementations, the memory 502 stores the following elements, executable modules or data structures, or a subset thereof, or an extended set thereof: an operating system 5021 and an application 5022 .

[0133] The operating system 5021 includes various system programs, such as a framework layer, a core library layer, a driver layer, etc., which are used to implement various basic services and process hardware-based tasks. The application 5022 includes various application programs, such as a browser, etc., which are used to implement various application services. The program for implementing the method of the embodiment of the present invention can be included in the application 5022.

[0134] The processor 501, when calling and executing the application and data stored in the memory 502, specifically, the program or instruction stored in the application 5022, executes the restart optimization method of the converter valve as described in the above embodiment.

[0135] The method disclosed in the above embodiment of the present invention can be applied to the processor 501, or implemented by the processor 501. The processor 501 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the hardware integrated logic circuit in the processor 501 or the instruction in the form of software. The above processor 501 can be a general processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, and can implement or execute the methods, steps and logic block diagrams disclosed in the embodiments of the present invention. The general processor can be a microprocessor or the processor can also be any conventional processor. The steps of the method disclosed in the embodiment of the present invention can be directly embodied as a hardware decoding processor to be executed, or the hardware and software modules in the decoding processor can be combined to be executed. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 502, and the processor 501 reads the information in the memory 502 and completes the steps of the above method in combination with its hardware.

[0136] It is understood that the embodiments described herein can be implemented in hardware, software, firmware, middleware, microcode or a combination thereof. For hardware implementation, the processing unit can be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), general purpose processors, controllers, microcontrollers, microprocessors, other electronic units for performing the functions described in the present application or a combination thereof.

[0137] For software implementation, the techniques described herein can be implemented by modules (e.g., procedures, functions, etc.) that perform the functions described herein. The software code can be stored in a memory and executed by a processor. The memory can be implemented in the processor or outside the processor.

[0138] In addition, an embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor executes the restart optimization method of the converter valve as described in the above embodiment.

[0139] In the several embodiments provided in the present application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0140] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may be physically included separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0141] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform some steps of the sending and receiving method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, referred to as ROM), random access memory (RandomAccess Memory, referred to as RAM), disk or optical disk and other media that can store program codes.

[0142] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for optimizing the restart of a converter valve, characterized in that: The steps include: Conduct vibration analysis on the converter valve to determine the vibration value of the converter valve under power restoration conditions; Based on the vibration signal of the converter valve, the vibration characteristics of the converter valve are constructed; Determine the target current control coefficient based on the dissipated energy accumulation function of the converter valve; Based on the target current control coefficient, the vibration value and the vibration characteristic, a target control level is determined, and a control signal at the target control level is input to the converter valve.

2. The restart optimization method of the converter valve according to claim 1, characterized in that: The target current control coefficient includes a target control proportional coefficient and a target control time coefficient. The step of determining a target control level based on the target current control coefficient, the vibration value and the vibration characteristic includes: The target control level is determined based on the target current control coefficient, the vibration value and the vibration characteristic using the following formula (1): u = -f * han(a c , c * z(t), K r , T r ) Equation (1) In the above formula (1), u refers to the target control level, f refers to the external disturbance value, han refers to the feedback function, and a c refers to the vibration value, c refers to the compensation factor, z(t) refers to the vibration characteristic, K r Refers to the target control proportional coefficient, T r Refers to the target control time coefficient.

3. The restart optimization method of the converter valve according to claim 1, characterized in that: The vibration value of the converter valve under the power-on condition is as follows: In the above formula (2), λ s refers to the saturation magnetostriction coefficient, L refers to the elongation length under the action of magnetic field expansion, ω refers to the fundamental angular frequency, B1-B k Refers to the magnetic induction intensity corresponding to the 1-kth iron core, B s refers to the saturation flux density, and n refers to the total amount of the core.

4. The restart optimization method of the converter valve according to claim 1, characterized in that: The vibration characteristics include vibration energy characteristics. The step of constructing the vibration characteristics of the converter valve based on the vibration signal of the converter valve includes: Removing low frequencies from the vibration signal to obtain an initialization signal; Based on the initialization signal, the vibration signal is decomposed to obtain a plurality of intrinsic mode function components; Subtracting the initialization signal from the intrinsic mode function component to obtain a residual component; The vibration energy signature is generated based on the intrinsic mode function component and the residual component.

5. The restart optimization method of the converter valve according to claim 4, characterized in that: The step of decomposing the vibration signal based on the initialization signal to obtain a plurality of intrinsic mode function components comprises: Finding the local extreme point of the initialization signal; Performing cubic spline function interpolation on the maximum and minimum values ​​of the initialization signal to generate upper and lower envelopes; Determining the average values ​​of the upper and lower envelopes; The intrinsic mode function component is determined based on the initialization signal and an average value of the upper and lower envelopes.

6. The restart optimization method of the converter valve according to claim 4, characterized in that: The step of generating the vibration energy feature based on the intrinsic mode function component and the residual component comprises: The vibration energy signature is generated using the following formula (3): In the above formula (3), c i (t) refers to the intrinsic mode function component, r m (t) refers to the residual component corresponding to the mth initialization signal, and m refers to the total number of signals.

7. The restart optimization method of the converter valve according to claim 4, characterized in that: The step of determining the target current control coefficient based on the dissipated energy accumulation function of the converter valve comprises: Based on the dissipated energy accumulation function, constructing an extreme value formula of the dissipated energy accumulation function; Using a particle swarm optimization algorithm to solve the extreme value formula of the dissipated energy accumulation function, and determine the target solution system of the current control coefficient; Based on the target solution system, the target current control coefficient is determined.

8. The restart optimization method of the converter valve according to claim 7, characterized in that: The step of determining the target current control coefficient based on the target solution system includes: Substituting the target solution system into the dissipated energy accumulation function, and screening out a minimum value solution system in the target solution system; Selecting a solution system whose corresponding cumulative value of dissipated energy is less than the cumulative value of dissipated energy during system fault recovery from the minimum solution system as a candidate solution system; The current control coefficient corresponding to the minimum value in the candidate solution system is used as the target current control coefficient.

9. An electronic device, characterized in that: include: processor; and a memory having computer program instructions stored therein, Wherein, when the computer program instructions are executed by the processor, the processor is enabled to execute the restart optimization method for the converter valve according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions, and when the computer program instructions are executed by a processor, the processor executes the restart optimization method for a converter valve according to any one of claims 1 to 8.

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