Flexible DC system high-frequency resonance suppression method

Abstract

The invention provides a high-frequency resonance suppression method for a flexible direct current system. The method comprises the following steps: acquiring a circuit state physical quantity after passing through a secondary cable and before entering a control link; determining the offset phase quantity of the circuit state physical quantity; and performing compensation processing on the acquired circuit state physical quantity according to the offset phase quantity so as to realize suppression of high-frequency resonance. The invention provides a new idea for solving the high-frequency resonance of the flexible direct current system, the method is not limited to the suppression of the high-frequency resonance in a control link, the situation of the high-frequency resonance of the system caused by introducing the high-frequency part of the system current into the control link is prevented, and the circuit is relatively simple, so that the stability margin of the flexible direct current system can be ensured, and the reliability of the system is improved. The maintenance cost of the flexible direct current system is saved, and the complexity of high-frequency resonance suppression is reduced.

Description

Technical Field

[0001] The present invention relates to the field of the stability of flexible DC transmission systems, and particularly to a method for suppressing high-frequency resonance in a flexible DC system. Background Art

[0002] High-frequency resonance refers to the resonance effect that occurs in a circuit when the inductance and capacitance parameters in the circuit can act together and their values match the frequency of the input signal. This effect causes the current and voltage in the circuit to increase significantly, forming high-frequency oscillations.

[0003] The flexible DC transmission system, abbreviated as the flexible DC system, has the characteristics of flexible control and good power quality, and has great advantages in the fields of asynchronous interconnection of AC power grids and offshore wind power transmission. The high-frequency resonance in the island operation mode of the converter station of the flexible DC system under no-load or low-load conditions is the most complex and typical, and is a multi-device and system-level problem involving primary equipment, secondary cables, and control systems. In the measurement link, the transfer and transformation characteristics of electromagnetic current transformers and their secondary cables are important factors inducing high-frequency resonance in the converter station of the flexible DC system.

[0004] Especially in the current and voltage measurement link after passing through the secondary cable and before introducing the control link, when encountering high-frequency components, it will cause the amplitude of this part of the high-frequency components to increase and the phase to drop, resulting in the lag of the high-frequency components in the current and voltage measurement link. After the high-frequency components generated after the change in the voltage and current measurement link of the flexible DC system enter the control link, due to their amplitude and phase characteristics, the negative feedback system cannot make a reasonable judgment, thus affecting the safe and stable operation of the flexible DC system. Therefore, the effective suppression of high-frequency resonance in the scenario where the high-frequency components of the current and the high-frequency components of the voltage lag in the current and voltage measurement link is very important for the safe and stable operation of the flexible DC transmission system.

[0005] Currently, the existing methods for suppressing high-frequency resonance all suppress high-frequency resonance in the control link. Since the circuit in the control link is relatively complex, the process of suppressing high-frequency resonance in the control link is complex and the required cost is high. Summary of the Invention

[0006] Aiming at the technical problem that the process of suppressing high-frequency resonance in the existing method for suppressing high-frequency resonance is complex and the required cost is high, a method for suppressing high-frequency resonance in a flexible DC system provided by the present invention compensates for the high-frequency components of the physical quantities of the circuit state after passing through the secondary cable and before entering the control link, while ensuring the stability margin of the flexible DC system, reducing the complexity and required cost of suppressing high-frequency resonance.

[0007] To solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a method for suppressing high-frequency resonance in a flexible DC system, the method comprising: collecting physical quantities of the circuit state after passing through the secondary cable and before entering the control link; determining the offset phase quantity of the physical quantities of the circuit state; and compensating the collected physical quantities of the circuit state according to the offset phase quantity to achieve suppression of high-frequency resonance.

[0009] Optionally, the determining the offset phase quantity of the physical quantities of the circuit state includes: determining the high-frequency resonance frequency of the physical quantities of the circuit state; determining the correspondence between the frequency and the offset phase after passing through the secondary cable; and matching the offset phase corresponding to the high-frequency resonance frequency from the correspondence between the frequency and the offset phase as the offset phase quantity.

[0010] Optionally, the determining the high-frequency resonance frequency of the physical quantities of the circuit state includes: sampling the physical quantities of the circuit state to obtain sampling values; obtaining an input sequence according to the sampling values; obtaining an output result according to the input sequence, where the output result includes the frequency of each sampling point, and the frequency of each sampling point includes the amplitude of the frequency; determining the harmonic content of each sampling point according to the amplitude of the frequency of each sampling point in the output result; and determining the high-frequency resonance of the physical quantities of the circuit state according to the frequency of each sampling point and the corresponding harmonic content.

[0011] Optionally, the determining the correspondence between the frequency and the offset phase after passing through the secondary cable includes: obtaining the correspondence between the frequency and the offset phase after passing through the secondary cable according to an objective function; the objective function includes:

[0012]

[0013] where, I 2a represents the current at the A-phase output terminal of the secondary cable of the current measurement link, I 1a represents the current at the A-phase input terminal of the secondary cable of the current measurement link, Z 1a represents Z sa 、Z pa 、Z a the equivalent impedance of the three, Z pa represents the impedance of the A-phase capacitor branch of the secondary cable of the current measurement link, Z a represents the A-phase measurement resistor in parallel with the capacitor at the output end of the secondary cable of the current measurement link, Z sa represents the impedance of the A-phase inductor branch of the secondary cable of the current measurement link.

[0014] Optionally, the compensating the collected physical quantities of the circuit state according to the offset phase quantity includes: determining a compensation parameter according to the offset phase quantity; and compensating the collected physical quantities of the circuit state according to the compensation parameter.

[0015] Optionally, determining a compensation parameter according to the offset phase amount includes: determining a compensation parameter according to the offset phase amount and a transfer function; the transfer function includes:

[0016]

[0017] where out represents the output quantity, in represents the input quantity, K1 and K2 both represent parameters set by the lead-lag compensator, and T s represents the unit time.

[0018] Optionally, the compensating the physical quantity of the circuit state collected according to the compensation parameter by the lead-lag compensation method includes:

[0019] determining a target lead-lag compensator according to the compensation parameter;

[0020] inputting the physical quantity of the circuit state into the target lead-lag compensator for compensation processing to obtain the compensated physical quantity of the circuit state.

[0021] In a second aspect, the present invention provides a high-frequency resonance suppression device for a flexible DC system. The device includes: an information acquisition module, adapted to acquire the physical quantity of the circuit state after passing through a secondary cable and before entering a control link; an offset phase amount determination module, determining the offset phase amount of the physical quantity of the circuit state; a compensation module, adapted to compensate the physical quantity of the circuit state acquired according to the offset phase amount to achieve suppression of high-frequency resonance.

[0022] In a third aspect, the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the above method are implemented.

[0023] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above method are implemented.

[0024] In a fifth aspect, the present invention provides a computer program product, including computer programs / instructions. When the computer programs / instructions are executed by a processor, the steps of the above method are implemented.

[0025] As can be seen from the above description, the method for suppressing high-frequency resonance in the flexible DC system provided by the present invention compensates for the high-frequency components of physical quantities of circuit states such as current and voltage that lag in the measurement link of the secondary-side system, that is, compensates for the high-frequency components of physical quantities of circuit states before entering the control link. This is equivalent to providing a new idea for solving high-frequency resonance in the flexible DC system, rather than being limited to suppressing high-frequency resonance in the control link, preventing the occurrence of high-frequency resonance in the system caused by introducing the high-frequency part of the system current into the control link. Compared with suppressing high-frequency resonance in the control link, since the circuit is relatively simple, it can save the maintenance cost of the flexible DC system and reduce the complexity of suppressing high-frequency resonance while ensuring the stability margin of the flexible DC system.

[0026] In addition, instead of filtering out high-frequency quantities, this method compensates for them, so that the physical quantities of the circuit state introduced into the control link are more consistent with those of the circuit state passing through the measurement link, thereby further improving the stability margin of the system.

[0027] And since the lead-lag compensation method itself can improve the steady-state accuracy and anti-interference ability of the flexible DC system, compensating for the high-frequency components of the physical quantities of the circuit state before entering the control link based on the lead-lag compensation method can further improve the stability margin and transmission performance of the flexible DC system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a schematic diagram of the system-side current waveform of the present invention;

[0030] Figure 2 It is a schematic flowchart of the method for suppressing high-frequency resonance in the flexible DC system in the first embodiment of the present invention;

[0031] Figure 3 It is a schematic flowchart of step 200 in an embodiment of the present invention;

[0032] Figure 4 It is a schematic diagram of the fast Fourier transform analysis result of the high-frequency components of the present invention;

[0033] Figure 5 It is a schematic diagram of the corresponding relationship between frequency and offset phase of the present invention;

[0034] Figure 6Schematic flowchart of step 300 in an embodiment of the present invention;

[0035] Figure 7 Block diagram of the transfer function in an embodiment of the present invention;

[0036] Figure 8 Schematic diagram of the current of the flexible DC system with high-frequency lag compensation in an example of the present invention

[0037] Figure 9 Structure block diagram of the high-frequency resonance suppression device of the flexible DC system in an example of the present invention;

[0038] Figure 10 Schematic structure diagram of the electronic device in the embodiment of the invention. Detailed implementation manners

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Before elaborating on the technical solution of the present invention in detail, it should be noted that the acquisition, storage, use, processing, etc. of data in the technical solution of the present invention all comply with the relevant regulations of national laws and regulations.

[0041] The flexible DC system has characteristics such as flexible control and good power quality, and has great advantages in the fields of asynchronous interconnection of AC power grids and offshore wind power transmission. The high-frequency resonance under no-load or low-load conditions in the island operation mode of the flexible DC system converter station is the most complex and typical, and it is a multi-device and system-level problem involving primary equipment, secondary cables and control systems. Especially in the measurement link, the transfer and transformation characteristics of electromagnetic current transformers and their secondary cables are important factors inducing high-frequency resonance in the flexible DC system converter station.

[0042] Taking the electromagnetic current transformer and its secondary system current measurement link of the modular multilevel converter high-voltage direct current (MMC-HVDC) system as an example, it is verified that the current measurement link of the current transformer will cause high-frequency resonance in the flexible DC system. Specifically:

[0043] By simulating the no-load condition of the new energy consumption operation mode of the flexible DC transmission island, without adding any links and without changing any simulation conditions, resonance suddenly occurs during the stable operation of the system, and the current waveform on the system side is obtained as Figure 1 shown. From Figure 1 it can be seen that after considering the current measurement link of the electromagnetic current transformer and its secondary system, the waveform of the output current amplitude of the MMC-HVDC system diverges rapidly. Without protection action, the amplitude value can be as high as 2 kA, indicating that resonance has occurred in the MMC-HVDC system, which shows the accuracy and rationality of the conclusion that the current measurement link of the current transformer proposed by the present invention will cause high-frequency resonance in the flexible DC system.

[0044] The specific derivation process of the fact that the current measurement link of the current transformer will cause high-frequency resonance in the flexible DC system includes:

[0045] Let the transfer ratio of the output current to the input current of the secondary cable of the electromagnetic current transformer be:

[0046]

[0047] where

[0048]

[0049] A = (E + G L G c ) -1

[0050] In the formula, I2 represents, I1 represents, E represents the unit matrix, Z represents, G c represents, G L represents, A represents, L1 represents the inductance of the secondary cable of the current measurement link, C1 represents the capacitance of the two capacitor branches of the secondary cable of the current measurement link, ω0 represents a numerical constant, and the specific value can be set according to the actual application scenario. For example, the numerical constant can be 100π, and s represents.

[0051] Define the right side of formula (1) as the matrix G of the secondary cable of the electromagnetic current transformer current measurement link cable , that is, the following formula (2):

[0052]

[0053] Substitute the parameters such as the inductance and capacitance of the secondary cable of the electromagnetic current transformer into formula (1), and the analytical expression form of the matrix of the electromagnetic current transformer current measurement link can be obtained, as shown in formula (3):

[0054]

[0055] where

[0056]

[0057] According to the actual situation of the secondary system cable in the current measurement link of the project, determine the parameter range of the variables in formula (4). Let:

[0058]

[0059] Let the parasitic inductance L1 of the secondary system cable of the electromagnetic current transformer be 0.299 mH, the parasitic capacitance C1 be approximately 0.3305 μF, the characteristic frequency ω1 be approximately 16.0 kHz, and the value of ω0 be 100π. In formula (4), the order of magnitude of the second term in the denominator is approximately 10 -3 , and this term can be ignored. Then formula (4) can be simplified to:

[0060]

[0061] Therefore, for the convenience of analyzing the frequency characteristics of the transfer function by the limit method in a wide frequency range, taking 1 / 10 times and 10 times of the characteristic frequency of the secondary system of the electromagnetic current transformer as nodes, divide the low-frequency band, middle-frequency band, and high-frequency band of the current measurement link.

[0062] Next, analyze the characteristics of the middle-frequency band in the current measurement link:

[0063] When , at this time, the orders of magnitude of the two terms in the denominator of formula (5) are not much different and neither can be ignored. At this time, the current measurement link of the secondary system of the electromagnetic current transformer is in the middle-frequency band, and the frequency range is approximately 1.6 kHz to 27.7 kHz.

[0064] Similarly, taking G in formula (3) 11 as an example, substitute the current a into G 11 , and after simplification, we can get:

[0065]

[0066] From the above formula, it can be seen that the order of magnitude of the first term in the numerator of G 11 multiplied by the capacitance is approximately 10 -3 , and this term can be ignored. The orders of magnitude of the first three terms in the denominator of G 11 after mathematical calculation are approximately 10 -6 , 10 -9 , 10 -9 , which are very small compared to the constant 1, and these three terms can be ignored. Then G 11 is further simplified to:

[0067]

[0068] The same applies to the other three parameters in the matrix, that is, the matrix form of the current measurement link in the medium frequency band is obtained as follows:

[0069]

[0070] It can be seen from formula (8) that when the secondary system of the electromagnetic current transformer is in the medium frequency band, the current measurement link changes the amplitude and phase of the current measured by the system. Thus, it is deduced that the current measurement link of the current transformer will cause high-frequency resonance in the flexible DC system.

[0071] When the high-frequency part enters the measurement link, phase and amplitude offsets will occur. After this part of the component enters the control link, due to its amplitude and phase characteristics, the negative feedback system cannot make a reasonable judgment, thus affecting the safe and stable operation of the flexible DC system.

[0072] On the basis of verifying that when the high-frequency part enters the measurement link, phase and amplitude offsets will occur, thus affecting the safe and stable operation of the flexible DC system, the situation of high-frequency component lag generated by the measurement link is further described. Taking the current measurement link after passing through the secondary cable and before introducing the control link as an example, the situation of high-frequency component lag generated by the current measurement link is described as follows:

[0073] In the current measurement link after passing through the secondary cable and before introducing the control link, the amplitude of the current measurement link model of the electromagnetic current transformer and its secondary cable will gradually increase with the increase of frequency. For example, it reaches the peak at about 5 kHz. In the frequency range of 1 k - 10 kHz, the amplitude change rate also reaches the peak. In the same frequency band, the phase angle of the current measurement link slowly decreases from 0 with the increase of frequency. When the amplitude reaches the peak, the phase drops to -180°, there is a risk of changing the negative feedback control of the flexible DC system to positive feedback. It can be concluded that in the current measurement link after passing through the secondary cable and before introducing the control link, when encountering high-frequency components, this part of the high-frequency components will have an increased amplitude and a dropped phase, resulting in high-frequency component lag in the current measurement link. Due to its amplitude and phase characteristics, the negative feedback system cannot make a reasonable judgment, thus affecting the safe and stable operation of the flexible DC system.

[0074] The above primary equipment is electrical equipment directly involved in the production, transformation, transmission, distribution and use of electric energy. The main functions of the primary equipment are to ensure the normal flow and use of electric energy, and at the same time provide necessary protection and control functions. These equipment play a crucial role in the power system, and they jointly constitute the main structure of the power system.

[0075] Primary equipment generally includes the following categories: Generator: A device that converts mechanical energy into electrical energy and is the power source of the power system. Transformer: A device used to change voltage, usually for step-up and step-down in the power transmission and distribution process. Circuit breaker: A device used to cut off and connect circuits, with overload and short-circuit protection functions. Isolating switch: A switch used to isolate the power source and equipment, mainly for maintenance and safety isolation. Busbar: The conductive part that connects devices such as generators, transformers, and circuit breakers, used to transmit electrical energy. Transmission line: A wire used to transmit electrical energy from the power plant to the substation and the user end. Power cable: An insulated wire used to transmit electrical energy underground or underwater.

[0076] Secondary cables refer to important cables used to transmit electrical energy, signals, and control instructions in the power system. It usually consists of parts such as conductors, insulation layers, shielding layers, and protective layers. Secondary cables mainly include the following functions: 1) Transmitting electrical energy. In the power system, secondary cables are responsible for transmitting electrical energy from the power station to each electrical device, ensuring the continuity and stability of power supply. 2) Transmitting signals. Secondary cables also undertake the task of transmitting various control signals, protection signals, and monitoring data, providing support for the intelligent management of the power system. 3) Controlling the system. Through the connection of secondary cables, remote control and automated management of the power system are realized, improving the operation efficiency of the power system.

[0077] Therefore, for the effective suppression of high-frequency resonance in the scenario of high-frequency component lag in the measurement link of circuit state physical quantities such as current and voltage, it is very important for the safe and stable operation of the flexible DC transmission system.

[0078] Currently, the existing high-frequency resonance suppression methods all suppress high-frequency resonance in the control link. Whether there is high-frequency resonance or not, high-frequency resonance is suppressed, resulting in waste of resources due to hard compensation. And because the circuit in the control link is relatively complex, the process of suppressing high-frequency resonance in the control link is complex and the required cost is high.

[0079] To solve the technical problems of the complex process and high required cost of the existing high-frequency resonance suppression methods, the embodiments of the present invention provide a high-frequency resonance suppression method and device to solve the above technical problems.

[0080] It should be noted that the high-frequency resonance suppression method for the flexible DC system provided by the embodiments of the present invention is applied to the suppression of high-frequency resonance in the current and voltage measurement link after passing through the secondary cable and before introducing the control link, which is equivalent to providing a new idea for solving high-frequency resonance in the control link, rather than being limited to suppressing high-frequency resonance in the control link.

[0081] Effectively suppress high-frequency resonance in the current and voltage measurement stage, so that there is no high-frequency resonance phenomenon in the voltage and current input to the control stage. Then, compared with the suppression of high-frequency resonance in the control stage, since the circuit is relatively simple, it is possible to reduce the complexity and required cost of high-frequency resonance suppression while ensuring the stability margin of the flexible DC system. In addition, instead of filtering out high-frequency components, this method compensates for them, making the current introduced into the control stage more consistent with the current passing through the measurement stage, thereby further improving the stability margin of the system.

[0082] The method for suppressing high-frequency resonance of the flexible DC system provided by the embodiment of the present invention is shown in Figure 2 , Figure 2 which is a schematic flowchart of the method for suppressing high-frequency resonance of the flexible DC system in an embodiment of the present invention. The method specifically includes the following steps:

[0083] Step 100: Collect the physical quantities of the circuit state after passing through the secondary cable and before entering the control stage.

[0084] The physical quantities of the circuit state are used to describe the operating state and characteristics of the power grid. The specific content of the physical quantities of the circuit state in the embodiments of the present invention is not limited. For example, the physical quantities of the circuit state can be any one or more of voltage, current, potential, electromotive force, and electric quantity. Further, the physical quantities of the circuit state can be voltage and / or current.

[0085] At this time, the embodiments of the present invention suppress the high-frequency resonance of the current and / or voltage measurement stage after passing through the secondary cable and before introducing it into the control stage. That is, it can be the suppression of the high-frequency resonance of the current after passing through the secondary cable and before introducing it into the control stage, or the suppression of the high-frequency resonance of the voltage after passing through the secondary cable and before introducing it into the control stage, or the simultaneous suppression of the high-frequency resonance of the current and voltage after passing through the secondary cable and before introducing it into the control stage.

[0086] Step 200: Determine the offset phase quantity of the physical quantity of the circuit state.

[0087] Step 300: Perform compensation processing on the collected physical quantities of the circuit state according to the offset phase quantity to achieve the suppression of high-frequency resonance.

[0088] As can be seen from the above description, the method for suppressing high-frequency resonance in the flexible DC system provided by the embodiment of the present invention compensates for the high-frequency components of the physical quantity of the circuit state lagging in the secondary system measurement link, that is, compensates for the high-frequency components of the physical quantity of the circuit state before entering the control link, which is equivalent to providing a new idea for solving high-frequency resonance in the flexible DC system, rather than being limited to suppressing high-frequency resonance in the control link, preventing the occurrence of high-frequency resonance in the flexible DC system caused by introducing the high-frequency part of the physical quantity of the system circuit state into the control link. Compared with suppressing high-frequency resonance in the control link, since the circuit in the measurement link is relatively simple, it can save the maintenance cost of the flexible DC system and reduce the complexity of suppressing high-frequency resonance while ensuring the stability margin of the flexible DC system. In addition, this method does not filter out high-frequency quantities, but compensates them, so that the physical quantity of the circuit state introduced into the control link is more consistent with the physical quantity of the circuit state passing through the measurement link, thereby further improving the stability margin of the system.

[0089] In some embodiments, as Figure 3 shown, step 200 may specifically include:

[0090] Step 210: Determine the high-frequency resonance frequency of the physical quantity of the circuit state.

[0091] Specifically, step 210 includes: First, sample the physical quantity of the circuit state to obtain a sampling value, and obtain an input sequence according to the sampling value. Then, obtain an output result according to the input sequence, where the output result includes the frequency of each sampling point, and the frequency of each sampling point includes the amplitude of the frequency. Determine the harmonic content of each sampling point according to the amplitude of the frequency of each sampling point in the output result, and then determine the high-frequency resonance of the physical quantity of the circuit state according to the frequency of each sampling point and the corresponding harmonic content.

[0092] The following gives a specific example of determining the high-frequency resonance frequency of the physical quantity of the circuit state:

[0093] 1) Sample the physical quantity of the circuit state according to a preset sampling frequency and a preset number of sampling points to obtain a sampling value N.

[0094] 2) Obtain an input sequence x(n) according to the sampling value, where n = 0, 1,..., N - 1.

[0095] 3) Input the input sequence into the objective function to obtain an output result. The output result includes the frequency of each sampling point, and the frequency of each sampling point is in complex form. The complex form includes the amplitude and phase of the frequency. The objective function includes:

[0096] X(k) = ∑[n = 0 to N - 1]x(n)×e (j2πkn / N)

[0097] Wherein, X(k) represents the frequency-domain signal of the physical quantity of the circuit state, x(n) represents the time-domain signal of the physical quantity of the circuit state, j represents the imaginary operator, and N represents the total number of sampling points.

[0098] 4) Determine the harmonic content of each sampling point according to the amplitude of the frequency of each sampling point in the output result.

[0099] 5) Determine the corresponding relationship between the frequency and the harmonic content according to the frequency and the corresponding harmonic content of each sampling point, and find out the frequency concentration region from the corresponding relationship, and use the frequency corresponding to the frequency concentration region as the high-frequency resonance of the physical quantity of the circuit state.

[0100] Taking the physical quantity of the circuit state after passing through the secondary cable and before entering the control link as an example of current, after performing a fast Fourier transform, the analysis result of the fast Fourier transform of the high-frequency component as shown in Figure 4 is obtained, Figure 4 where the abscissa represents the frequency and the ordinate represents the harmonic content. It can be seen from Figure 4 that the frequency corresponding to the harmonic content is concentrated at 2KHz, that is to say, the high-frequency resonance is 2KHz.

[0101] It should be noted that the above method for determining the high-frequency resonance frequency of the physical quantity of the circuit state can specifically be the fast Fourier transform method. Of course, it can also be other methods, as long as the high-frequency resonance frequency of the physical quantity of the circuit state can be determined.

[0102] Step 220: Determine the corresponding relationship between the frequency and the offset phase passing through the secondary cable.

[0103] Specifically, the corresponding relationship between the frequency and the offset phase passing through the secondary cable can be obtained according to the objective function.

[0104] The objective function here is the transfer function of the output physical quantity and the input physical quantity of the secondary system of the measurement link in the stationary coordinate system. The objective function includes:

[0105]

[0106] In the formula, I 2a represents the current at the A-phase output end of the secondary cable of the current measurement link, I 1a represents the current at the A-phase input end of the secondary cable of the current measurement link, Z 1a represents the impedance equivalent to the three of Z sa , Z pa , Z a , Z pa represents the impedance of the A-phase capacitance branch of the secondary cable of the current measurement link, Z a represents the A-phase measurement resistor in parallel with the capacitance at the output end of the secondary cable of the current measurement link, Z saIt represents the impedance of the A-phase inductive branch of the secondary cable in the current measurement section.

[0107] Taking the physical quantity of the circuit state as current as an example, the objective function here is the transfer function of the output current and the input current of the secondary system in the measurement section in the stationary coordinate system. According to the objective function, the phase shift Bode plot can be obtained, as Figure 5 shown. Figure 5 It shows the corresponding relationship between frequency and offset phase.

[0108] Step 230: Match the offset phase corresponding to the high-frequency resonance frequency from the corresponding relationship between frequency and offset phase as the offset phase quantity.

[0109] Similarly, taking the physical quantity of the circuit state as current, if the high-frequency resonance is Figure 4 2KHz determined in Figure 5 as an example, then find the offset phase corresponding to the high-frequency resonance frequency of 2KHz from the phase shift Bode plot shown in

[0110] The offset phase is approximately -20°, that is, the high frequency lags. It can be seen from the above that through fast Fourier transform analysis, the signal can be transformed from the time domain to the frequency domain, so as to more deeply understand the characteristics of the signal, making the phase analysis more in-depth and accurate, thereby improving the accuracy of high-frequency resonance suppression. And the complexity of fast Fourier transform analysis is low, greatly reducing the calculation time, which makes the speed of phase analysis of the physical quantity of the circuit state faster, thereby improving the efficiency of high-frequency resonance suppression.

[0111] In order to further improve the stability margin and transmission performance of the flexible DC system, in some embodiments, as Figure 6 shown, step 300 may specifically include:

[0112] Step 310: Determine the compensation parameter according to the offset phase quantity.

[0113] Specifically, first determine the compensation parameter according to the offset phase quantity and the transfer function. The transfer function block diagram is as Figure 7 shown, then the transfer function corresponding to Figure 7 includes:

[0114]

[0115] where out represents the output quantity, in represents the input quantity, K1 and K2 both represent the parameters set by the lead-lag compensator, and T s represents the unit time.

[0116] Determining the compensation parameter through the transfer function is a prior art and will not be elaborated here. All implementation methods of determining the compensation parameter according to the transfer function are within the protection scope of the embodiments of the present invention.

[0117] After determining the transfer function, the corresponding relationship between the offset phase quantity and the compensation parameter can be determined. Then, the compensation parameter corresponding to the currently determined offset phase quantity can be found from the corresponding relationship between the offset phase quantity and the compensation parameter. The corresponding relationship between the offset phase quantity and the compensation parameter is common knowledge to those skilled in the art and is well-known technology, so it will not be elaborated here.

[0118] Step 320: Compensate the physically measured circuit state quantity collected according to the compensation parameter.

[0119] Specifically, first, the target lead-lag compensator can be determined according to the compensation parameter. That is to say, the parameters of the lead-lag compensator are set as the compensation parameter. Then, the physically measured circuit state quantity is input into the target lead-lag compensator for compensation processing to obtain the compensated physically measured circuit state quantity. That is, the physically measured circuit state quantity passes through the target lead-lag compensator, and the compensated physically measured circuit state quantity is output.

[0120] Taking the physically measured circuit state quantity as current and high-frequency lag as an example, then the current passes through the target lead-lag compensator, and the compensated current is output, and the compensated current can be applied to the control link. Since the high-frequency lag has been compensated, under normal circumstances, the current in the flexible DC system is normal and there is no high-frequency lag situation. The current at this time is as Figure 8 shown, that is, the current in the flexible DC system after high-frequency lag compensation is as Figure 8 shown, and the current is in a normal situation without high-frequency lag phenomenon.

[0121] As can be seen from the above, the high-frequency component of the physically measured circuit state quantity before entering the control link is compensated by the lead-lag compensation method, which is equivalent to providing a new idea for solving the high-frequency resonance of the flexible DC system, rather than being limited to suppressing the high-frequency resonance in the control link, preventing the situation of system high-frequency resonance caused by introducing the high-frequency part of the system current into the control link. Compared with the suppression of high-frequency resonance in the control link, since the circuit is relatively simple, it can save the maintenance cost of the flexible DC system and reduce the complexity of high-frequency resonance suppression while ensuring the stability margin of the flexible DC system. In addition, since the lead-lag compensation method itself can improve the steady-state accuracy and anti-interference ability of the flexible DC system, compensating the high-frequency component of the physically measured circuit state quantity before entering the control link based on the lead-lag compensation method can further improve the stability margin and transmission performance of the flexible DC system.

[0122] Those skilled in the art know that the embodiments of the present invention can be implemented as a system, device, equipment, method, or computer program product. Therefore, the present disclosure can be specifically implemented in the following forms: completely hardware, completely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0123] Based on the same inventive concept as the above flexible DC system high-frequency resonance suppression method, an embodiment of the present invention also provides a flexible DC system high-frequency resonance suppression device. Since the principle of this device for solving problems is similar to that of the flexible DC system high-frequency resonance suppression method, the implementation of this device can refer to the implementation of the method, and the repeated parts will not be elaborated.

[0124] Figure 9 It is the structural block diagram of the flexible DC system high-frequency resonance suppression device in the embodiment of the present invention. As Figure 9 shown, the waveform sample generation device for power system protection testing includes:

[0125] An information acquisition module 910, adapted to acquire the physical quantity of the circuit state after passing through the secondary cable and before entering the control link.

[0126] An offset phase quantity determination module 920, which determines the offset phase quantity of the physical quantity of the circuit state.

[0127] A compensation module 930, adapted to perform compensation processing on the acquired physical quantity of the circuit state according to the offset phase quantity to achieve the suppression of high-frequency resonance.

[0128] In one embodiment, the offset phase quantity determination module 920 includes:

[0129] A high-frequency resonance frequency determination module, adapted to determine the high-frequency resonance frequency of the physical quantity of the circuit state.

[0130] A correspondence determination module, adapted to determine the correspondence between the frequency passing through the secondary cable and the offset phase.

[0131] An offset phase difference determination module, adapted to match the offset phase corresponding to the high-frequency resonance frequency from the correspondence between the frequency and the offset phase as the offset phase quantity.

[0132] In one embodiment, the high-frequency resonance frequency determination module includes:

[0133] A sampling sub-module, adapted to sample the physical quantity of the circuit state to obtain a sampling value;

[0134] An input sequence determination sub-module, adapted to obtain an input sequence according to the sampling value.

[0135] An output result determination sub-module, adapted to obtain an output result according to an input sequence, wherein the output result includes the frequency of each sampling point, and the frequency of each sampling point includes the amplitude of the frequency.

[0136] A sampling point harmonic content determination sub-module, adapted to determine the harmonic content of each sampling point according to the amplitude of the frequency of each sampling point in the output result.

[0137] A high-frequency resonance frequency determination sub-module, adapted to determine the high-frequency resonance of the physical quantity of the circuit state according to the frequency of each sampling point and the corresponding harmonic content.

[0138] In one embodiment, the correspondence determination module includes:

[0139] A correspondence determination sub-module, adapted to obtain the correspondence between the frequency passing through the secondary cable and the offset phase according to the objective function.

[0140] The objective function includes:

[0141]

[0142] Wherein, I 2a represents the current at the A-phase output end of the secondary cable of the current measurement link, I 1a represents the current at the A-phase input end of the secondary cable of the current measurement link, Z 1a represents Z sa 、Z pa 、Z a The equivalent impedance of the three, Z pa represents the impedance of the A-phase capacitance branch of the secondary cable of the current measurement link, Z a represents the A-phase measurement resistor connected in parallel with the capacitance at the output end of the secondary cable of the current measurement link, Z sa represents the impedance of the A-phase inductance branch of the secondary cable of the current measurement link.

[0143] In one embodiment, the compensation module 930 includes:

[0144] A compensation parameter determination module, adapted to determine compensation parameters according to the offset phase amount.

[0145] A first compensation sub-module, adapted to perform compensation processing on the collected physical quantity of the circuit state according to the compensation parameters.

[0146] In one embodiment, the compensation parameter determination module includes:

[0147] Determine compensation parameters according to the offset phase amount and the transfer function.

[0148] The transfer function includes:

[0149]

[0150] Among them, out represents the output quantity, in represents the input quantity, and K1 and K2 both represent the parameters set by the lead-lag compensator, and T s represents the unit time.

[0151] In one embodiment, the first compensation sub-module includes:

[0152] A compensation lag determiner, adapted to determine a target lead-lag compensator according to the compensation parameters.

[0153] A second compensation sub-module, adapted to input the physical quantity of the circuit state into the target lead-lag compensator.

[0154] The high-frequency resonance suppression device for the flexible DC system provided by the embodiment of the present invention compensates for the high-frequency components of the physical quantity of the circuit state that lags in the secondary system measurement link, that is, compensates for the high-frequency components of the physical quantity of the circuit state before entering the control link, which is equivalent to providing a new idea for solving the high-frequency resonance of the flexible DC system, rather than being limited to suppressing the high-frequency resonance in the control link, preventing the occurrence of high-frequency resonance of the flexible DC system caused by introducing the high-frequency part of the physical quantity of the system circuit state into the control link. Compared with the suppression of high-frequency resonance in the control link, since the circuit of the measurement link is relatively simple, it can save the maintenance cost of the flexible DC system and reduce the complexity of high-frequency resonance suppression while ensuring the stability margin of the flexible DC system. In addition, this method does not filter out the high-frequency quantity, but compensates it, so that the physical quantity of the circuit state introduced into the control link is more consistent with the physical quantity of the circuit state passing through the measurement link, thereby further improving the stability margin of the system.

[0155] Figure 10 It is a schematic block diagram of the system composition of the electronic device 10600 according to an embodiment of the present application. As Figure 10 shown, the electronic device 10600 may include a central processing unit 10100 and a memory 10140; the memory 10140 is coupled to the central processing unit 10100. It should be noted that this Figure 10 is exemplary; other types of structures may also be used to supplement or replace this structure to implement telecommunication functions or other functions.

[0156] In one embodiment, the function of the high-frequency resonance suppression method for the flexible DC system may be integrated into the central processing unit 10100. Among them, the central processing unit 10100 may be configured to perform the following controls:

[0157] Step 100: Collect the physical quantity of the circuit state after passing through the secondary cable and before entering the control link.

[0158] Step 200: Determine the offset phase quantity of the physical quantity of the circuit state.

[0159] Step 300: Compensate the collected physical quantity of the circuit state according to the offset phase quantity to suppress high-frequency resonance.

[0160] As can be seen from the above description, the high-frequency resonance suppression device for the flexible DC system provided by this application compensates the high-frequency components of the physical quantity of the circuit state that lags in the secondary system measurement link, that is, compensates the high-frequency components of the physical quantity of the circuit state before entering the control link. This is equivalent to providing a new idea for solving high-frequency resonance in the flexible DC system, rather than being limited to suppressing high-frequency resonance in the control link. It prevents the occurrence of high-frequency resonance in the flexible DC system caused by introducing the high-frequency part of the physical quantity of the system circuit state into the control link. Compared with suppressing high-frequency resonance in the control link, since the circuit in the measurement link is relatively simple, it can achieve saving the maintenance cost of the flexible DC system and reducing the complexity of high-frequency resonance suppression while ensuring the stability margin of the flexible DC system. In addition, this method does not filter out high-frequency quantities, but compensates them, so that the physical quantity of the circuit state introduced into the control link is more consistent with the physical quantity of the circuit state passing through the measurement link, thereby further improving the stability margin of the system.

[0161] In another embodiment, the high-frequency resonance suppression device for the flexible DC system can be separately configured from the central processor 10100. For example, the high-frequency resonance suppression device for the flexible DC system can be configured as a chip connected to the central processor 10100, and the functions of the high-frequency resonance suppression method for the flexible DC system are realized through the control of the central processor.

[0162] As Figure 10 shown, the electronic device 10600 may further include: a communication module 10110, an input unit 10120, an audio processor 10130, a display 10160, and a power supply 10170. It should be noted that the electronic device 10600 does not necessarily have to include all the components shown in Figure 10 ; in addition, the electronic device 10600 may further include components not shown in Figure 10 , and reference can be made to the prior art.

[0163] As Figure 10 shown, the central processor 10100 is sometimes also referred to as a controller or an operation control, and may include a microprocessor or other processor devices and / or logic devices. The central processor 10100 receives inputs and controls the operations of the various components of the electronic device 10600.

[0164] Among them, the memory 10140 can be, for example, one or more of a buffer, a flash memory, a hard drive, a removable medium, a volatile memory, a non-volatile memory, or other suitable devices. The above information related to failures can be stored, and in addition, a program for executing relevant information can also be stored. And the central processing unit 10100 can execute the program stored in the memory 10140 to achieve information storage or processing, etc.

[0165] The input unit 10120 provides input to the central processing unit 10100. The input unit 10120 is, for example, a key or a touch input device. The power supply 10170 is used to supply power to the electronic device 10600. The display 10160 is used to display display objects such as images and texts. The display can be, for example, an LCD display, but is not limited thereto.

[0166] The memory 10140 can be a solid-state memory. For example, it can be a read-only memory (ROM), a random access memory (RAM), a SIM card, etc. It can also be a memory that stores information even when powered off, can be selectively erased, and has more data. An example of such a memory is sometimes referred to as an EPROM, etc. The memory 10140 can also be some other type of device. The memory 10140 includes a buffer 10141 (sometimes referred to as a buffer memory). The memory 10140 can include an application / function storage unit 10142, which is used to store application programs and function programs or the processes for operating the electronic device 10600 through the central processing unit 10100.

[0167] The memory 10140 can also include a data storage unit 10143, which is used to store data, such as contacts, digital data, pictures, sounds, and / or any other data used by the electronic device. The driver storage unit 10144 of the memory 10140 can include various drivers of the electronic device for communication functions and / or for executing other functions of the electronic device (such as a messaging application, an address book application, etc.).

[0168] The communication module 10110 is a transmitter / receiver 10110 that transmits and receives signals via the antenna 10111. The communication module (transmitter / receiver) 10110 is coupled to the central processing unit 10100 to provide input signals and receive output signals, which can be the same as in the case of a conventional mobile communication terminal.

[0169] Based on different communication technologies, in the same electronic device, multiple communication modules 10110 can be provided, such as a cellular network module, a Bluetooth module, and / or a wireless local area network module, etc. The communication module (transmitter / receiver) 10110 is also coupled to a speaker 10131 and a microphone 10132 via an audio processor 10130 to provide an audio output via the speaker 10131 and receive an audio input from the microphone 10132, so as to implement normal telecommunication functions. The audio processor 10130 can include any suitable buffers, decoders, amplifiers, etc. Additionally, the audio processor 10130 is also coupled to a central processor 10100, enabling recording on the device through the microphone 10132 and playing the sounds stored on the device through the speaker 10131.

[0170] An embodiment of the present invention also provides a computer-readable storage medium capable of implementing all the steps in the high-frequency resonance suppression method of the flexible DC system in the above embodiment. A computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, all the steps in the high-frequency resonance suppression method of the flexible DC system in the above embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0171] Step 100: Collect the physical quantity of the circuit state after passing through the secondary cable and before entering the control link.

[0172] Step 200: Determine the offset phase quantity of the physical quantity of the circuit state.

[0173] Step 300: Perform compensation processing on the collected physical quantity of the circuit state according to the offset phase quantity to achieve the suppression of high-frequency resonance.

[0174] In summary, the computer-readable storage medium of the embodiment of the present invention compensates the high-frequency components of the physical quantity of the circuit state that lags in the secondary system measurement link, that is, compensates the high-frequency components of the physical quantity of the circuit state before entering the control link, which is equivalent to providing a new idea for solving the high-frequency resonance of the flexible DC system, rather than being limited to suppressing high-frequency resonance in the control link, preventing the occurrence of high-frequency resonance of the flexible DC system caused by introducing the high-frequency part of the physical quantity of the system circuit state into the control link. Compared with the suppression of high-frequency resonance in the control link, since the measurement link circuit is relatively simple, it can achieve saving the maintenance cost of the flexible DC system and reducing the complexity of high-frequency resonance suppression while ensuring the stability margin of the flexible DC system. In addition, this method does not filter out high-frequency quantities but compensates them, so that the physical quantity of the circuit state introduced into the control link is more consistent with the physical quantity of the circuit state passing through the measurement link, thereby further improving the stability margin of the system.

[0175] An embodiment of the present invention further provides a computer program product capable of implementing all steps in the high-frequency resonance suppression method for the flexible DC system in the above embodiments. The computer program product includes a computer program / instructions, and when the computer program / instructions are executed by a processor, all steps in the high-frequency resonance suppression method for the flexible DC system in the above embodiments are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0176] Step 100: Collect physical quantities of the circuit state after passing through the secondary cable and before entering the control link.

[0177] Step 200: Determine the offset phase quantity of the physical quantity of the circuit state.

[0178] Step 300: Perform compensation processing on the collected physical quantities of the circuit state according to the offset phase quantity to achieve suppression of high-frequency resonance.

[0179] In summary, the computer program product of the embodiment of the present invention compensates for the high-frequency components of the physical quantity of the circuit state lagging in the secondary system measurement link, that is, compensates for the high-frequency components of the physical quantity of the circuit state before entering the control link, which is equivalent to providing a new idea for solving the high-frequency resonance of the flexible DC system, rather than being limited to suppressing high-frequency resonance in the control link, preventing the occurrence of high-frequency resonance of the flexible DC system caused by introducing the high-frequency part of the physical quantity of the system circuit state into the control link. Compared with the suppression of high-frequency resonance in the control link, since the circuit in the measurement link is relatively simple, it is possible to save the maintenance cost of the flexible DC system and reduce the complexity of high-frequency resonance suppression while ensuring the stability margin of the flexible DC system. In addition, this method does not filter out high-frequency quantities but compensates them, so that the physical quantity of the circuit state introduced into the control link is more consistent with the physical quantity of the circuit state passing through the measurement link, thereby further improving the stability margin of the system.

[0180] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program type embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiments.

[0181] The above describes specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be executed in a different order than in the embodiments and still achieve the desired results. Additionally, the processes depicted in the figures do not necessarily require the particular order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0182] Although the present application provides method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on routine or non-creative labor. The step sequences listed in the embodiments are merely one way among numerous step execution sequences and do not represent the only execution sequence. When the actual device or client product is executed, it may be executed in the method sequence shown in the embodiments or the drawings or executed in parallel (such as in an environment of parallel processors or multi-threaded processing).

[0183] Although the embodiments of the present specification provide method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on routine or non-creative means. The step sequences listed in the embodiments are merely one way among numerous step execution sequences and do not represent the only execution sequence. When the actual device or terminal product is executed, it may be executed in the method sequence shown in the embodiments or the drawings or executed in parallel (such as in an environment of parallel processors or multi-threaded processing, or even in a distributed data processing environment). The term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, product or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, product or device. Without further limitation, there is no exclusion of additional identical or equivalent elements in the process, method, product or device comprising the said elements.

[0184] For convenience of description, the above device is described by dividing it into various modules according to functions. Of course, when implementing the embodiments of the present specification, the functions of each module can be implemented in the same or multiple software and / or hardware, or the modules implementing the same function can be realized by a combination of multiple sub-modules or sub-units, etc. The device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, 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 displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0185] Those skilled in the art also know that, in addition to implementing the controller in the form of pure computer-readable program code, the method steps can be logically programmed to enable the controller to be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. to achieve the same functions. Therefore, such a controller can be regarded as a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as either software modules for implementing the method or the structures within the hardware component.

[0186] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0187] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0188] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0189] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and a memory.

[0190] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM) and / or non-volatile memory such as read-only memory (ROM) or flash RAM. The memory is an example of computer-readable media.

[0191] Computer-readable media includes both permanent and non-permanent, removable and non-removable media implemented by any method or technology for information storage. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile discs (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices, or any other non-transitory media that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transitory media such as modulated data signals and carrier waves.

[0192] Those skilled in the art will appreciate that the embodiments of this specification may be provided as a method, system, or computer program product. Accordingly, the embodiments of this specification may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the embodiments of this specification may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0193] The embodiments in this specification may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The embodiments of this specification may also be practiced in a distributed computing environment where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including storage devices.

[0194] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and the differences between each embodiment and other embodiments are emphasized. In particular, for system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and reference can be made to the corresponding parts of the method embodiments for relevant details. In the description of this specification, the description of reference terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of this specification. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0195] The above is only the embodiments of the embodiments of this specification and is not used to limit the embodiments of this specification. For those skilled in the art, various changes and modifications can be made to the embodiments of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the embodiments of this specification shall be included within the scope of the claims of the embodiments of this specification.

Claims

1. A method for suppressing high-frequency resonance in a flexible DC system, characterized in that, The method includes: Collecting the physical quantity of the circuit state after passing through the secondary cable and before entering the control link; Determining the offset phase quantity of the physical quantity of the circuit state; Performing compensation processing on the collected physical quantity of the circuit state according to the offset phase quantity to achieve the suppression of high-frequency resonance.

2. The high-frequency resonance suppression method according to claim 1, characterized in that The determining the offset phase quantity of the physical quantity of the circuit state includes: Determining the high-frequency resonance frequency of the physical quantity of the circuit state; Determining the correspondence between the frequency passing through the secondary cable and the offset phase; Matching the offset phase corresponding to the high-frequency resonance frequency from the correspondence between the frequency and the offset phase as the offset phase quantity.

3. The high-frequency resonance suppression method according to claim 2, characterized in that, The determining the high-frequency resonance frequency of the physical quantity of the circuit state includes: Sampling the physical quantity of the circuit state to obtain a sampling value; Obtaining an input sequence according to the sampling value; Obtaining an output result according to the input sequence, where the output result includes the frequency of each sampling point, and the frequency of each sampling point includes the amplitude of the frequency; Determining the harmonic content of each sampling point according to the amplitude of the frequency of each sampling point in the output result; Determining the high-frequency resonance of the physical quantity of the circuit state according to the frequency of each sampling point and the corresponding harmonic content.

4. The high-frequency resonance suppression method according to claim 2, wherein The determining the correspondence between the frequency passing through the secondary cable and the offset phase includes: Obtaining the correspondence between the frequency passing through the secondary cable and the offset phase according to the objective function; The objective function includes: Among them, I 2a represents the current at the A-phase output terminal of the secondary cable of the current measurement link, I 1a represents the current at the A-phase input terminal of the secondary cable of the current measurement link, Z 1a represents Z sa , Z pa , Z a The equivalent impedance of the three, Z pa represents the impedance of the A-phase capacitor branch of the secondary cable of the current measurement link, Z a represents the A-phase measurement resistor connected in parallel with the capacitor at the output terminal of the secondary cable of the current measurement link, Z sa represents the impedance of the A-phase inductor branch of the secondary cable of the current measurement link.

5. The high-frequency resonance suppression method according to any one of claims 1 to 4, characterized in that, The performing compensation processing on the collected physical quantity of the circuit state according to the offset phase quantity includes: Determining a compensation parameter according to the offset phase quantity; Performing compensation processing on the collected physical quantity of the circuit state according to the compensation parameter.

6. The high-frequency resonance suppression method according to claim 5, wherein Determining a compensation parameter according to the offset phase quantity includes: Determining a compensation parameter according to the offset phase quantity and the transfer function; The transfer function includes: Among them, out represents the output quantity, in represents the input quantity, and K1 and K2 both represent the parameters set by the lead-lag compensator, and T s represents the unit time.

7. The high-frequency resonance suppression method according to claim 5, wherein The performing compensation processing on the collected physical quantity of the circuit state according to the compensation parameter includes: Determining a target lead-lag compensator according to the compensation parameter; Inputting the physical quantity of the circuit state into the target lead-lag compensator for compensation processing to obtain the compensated physical quantity of the circuit state.

8. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and running on the processor, characterized in that, When the processor executes the program, the steps of the HVDC system high-frequency resonance suppression method according to any one of claims 1 to 7 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the HVDC system high-frequency resonance suppression method according to any one of claims 1 to 7 are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, the steps of the HVDC system high-frequency resonance suppression method according to any one of claims 1 to 7 are implemented.

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