Overvoltage suppression method and apparatus

Abstract

The application is suitable for the technical field of power grid control, and provides an overvoltage suppression method and device. The method comprises the following steps: obtaining a target overvoltage of a fault at an AC bus of a voltage source converter; obtaining a reactive power reference signal based on the target overvoltage; and suppressing the target overvoltage based on the actual output reactive power of the voltage source converter and the reactive power reference signal. The application can realize effective suppression of overvoltage at the AC bus of the voltage source converter by the hybrid power flow controller, enhance the suppression effect in the initial stage of suppression, and improve the response speed of suppression.

Description

Technical Field

[0001] This application belongs to the field of power grid control technology, and in particular relates to overvoltage suppression methods and devices. Background Technology

[0002] As renewable energy sources increasingly replace traditional thermal power generation in the power grid, their inherent uncertainties and volatility pose challenges to the dynamic control of power flow. This characteristic exacerbates the imbalance in power flow distribution, manifesting as excessive loads on certain transmission channels and nodes, localized voltage spikes, and particularly pronounced overload issues under N-1 conditions (where the system can still operate normally after any component failure). These problems coexist within the power grid, stemming from both transmission line bottlenecks and underutilization of transmission capacity, severely impacting the overall power supply capacity and system security and stability.

[0003] To address the aforementioned issues, hybrid power flow controllers have become a research hotspot. This device combines a large-capacity dual-core symmetrical phase-shifting transformer (PST) with a small-capacity voltage source converter (VSC), forming a novel hybrid power flow controller (HPFC). This controller can achieve precise and rapid control of power flow by flexibly and continuously adjusting the amplitude and phase of the line impedance. However, the overvoltage characteristics of this new device, combining traditional electromagnetic and power electronic equipment, are more complex. While combining the secondary side of the excitation transformer with the voltage source converter can improve the converter's overvoltage withstand capability, the voltage source converter, being a power electronic device, has limited voltage withstand capability. It can only withstand small overvoltage stress amplitudes and short durations, making it susceptible to damage and shutdown during overvoltage events. Therefore, suppressing transient overvoltages on the AC bus of the voltage source converter from the control level of the hybrid power flow controller is particularly important.

[0004] During normal operation, if the power flow of the line changes, the power flow is tracked by a discrete adjustment system using a dual-core symmetrical phase-shifting transformer, combined with a voltage source converter to achieve continuous and precise regulation. The voltage source converter control uses a proportional-integral (PI) controller to compensate for errors. However, the PI controller is a control mechanism that eliminates errors based on error feedback. When overvoltage occurs, the voltage source converter's continued PI regulation may introduce lag and significant fluctuations, which may not meet performance requirements in applications demanding rapid response and effective overvoltage suppression. Summary of the Invention

[0005] This application provides an overvoltage suppression method and apparatus to achieve effective suppression of overvoltage at the AC bus of a voltage source converter by a hybrid power flow controller, enhance the suppression effect in the initial stage of suppression, and improve the suppression response speed.

[0006] This application is achieved through the following technical solution:

[0007] In a first aspect, embodiments of this application provide an overvoltage suppression method, including:

[0008] Obtain the target overvoltage at the AC bus of the voltage source converter where the fault occurs.

[0009] Based on the target overvoltage, a reactive power reference signal is obtained.

[0010] Based on the actual output reactive power and reactive power reference signal of the voltage source converter, target overvoltage is suppressed.

[0011] In conjunction with the first aspect, among some possible implementations, target overvoltages are suppressed based on the actual output reactive power of the voltage source converter and the reactive power reference signal, including:

[0012] Calculate the difference between the actual output reactive power of the voltage source converter and the reactive power reference signal, and denot it as the first difference.

[0013] Based on the first difference, adjust the bandwidth of the hybrid power flow controller.

[0014] Based on the bandwidth of the hybrid power flow controller, the bandwidth of the linear expansion state observer is set to suppress the target overvoltage.

[0015] In conjunction with the first aspect, in some possible implementations, the bandwidth of the voltage source converter is adjusted based on the first difference, including:

[0016] When the first difference is greater than the first set value, the bandwidth is increased by the adaptive linear active disturbance suppression control hybrid power flow controller.

[0017] When the first difference is less than the first set value, the bandwidth is reduced by the adaptive linear active disturbance suppression control hybrid power flow controller.

[0018] In conjunction with the first aspect, in some possible implementations, when the first difference is greater than the first set value, the bandwidth is increased by the adaptive linear active disturbance suppression control hybrid power flow controller, including:

[0019] When the first difference is greater than the first set value, the bandwidth is increased by the adaptive linear active disturbance suppression control hybrid power flow controller in combination with the first formula.

[0020] The first formula is:

[0021] ω + =ω c0 +k(ln10(Q V -Q ref )+Q set )

[0022] Where, ω + ω represents the increased bandwidth. c0 Let Q represent the initial bandwidth, k represent the adaptive adjustment coefficient, and (Q) V -Q ref ) represents the first difference, Q set This indicates the first set value.

[0023] In conjunction with the first aspect, in some possible implementations, when the first difference is less than a first set value, the bandwidth is reduced by an adaptive linear active disturbance suppression control hybrid power flow controller, including:

[0024] When the first difference is less than the first set value, the bandwidth is reduced by the adaptive linear active disturbance suppression control hybrid power flow controller in conjunction with the second formula.

[0025] The second formula is:

[0026]

[0027] Where, ω - ω represents the reduced bandwidth. c0 Let Q represent the initial bandwidth, k represent the adaptive adjustment coefficient, and (Q) V -Q ref ) represents the first difference, Q set This indicates the first set value.

[0028] In conjunction with the first aspect, in some possible implementations, the bandwidth of the linearly extended state observer is 2 to 10 times the bandwidth of the hybrid power flow controller.

[0029] In conjunction with the first aspect, among some possible implementations, obtaining the target overvoltage at the AC bus of the voltage source converter during a fault includes:

[0030] Obtain the original overvoltage data at the AC bus of the voltage source converter where the fault occurred.

[0031] Based on a preset effective overvoltage range, effective overvoltages are selected from the original overvoltage data.

[0032] The effective overvoltage is limited to obtain the target overvoltage.

[0033] In conjunction with the first aspect, in some possible implementations, the preset effective overvoltage range is 1kV to 1.5kV.

[0034] In conjunction with the first aspect, in some possible implementations, a reactive power reference signal is obtained based on the target overvoltage, including:

[0035] Combining the third formula, a reactive power reference signal is obtained based on the target overvoltage.

[0036] The third formula is:

[0037]

[0038] Among them, Q ref This represents the reactive power reference signal, and v0 represents the per-unit value of the target overvoltage.

[0039] Secondly, embodiments of this application provide an overvoltage suppression device, comprising:

[0040] The data acquisition module is used to acquire the target overvoltage at the AC bus of the voltage source converter where the fault occurs.

[0041] The data calculation module is used to obtain the reactive power reference signal based on the target overvoltage.

[0042] The voltage suppression module is used to suppress target overvoltages based on the actual output reactive power and reactive power reference signal of the voltage source converter.

[0043] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0044] The beneficial effects of the embodiments in this application compared with the prior art are:

[0045] This application obtains the reactive power reference signal through target overvoltage calculation. Then, based on the actual output power and the reactive power reference signal, it can adaptively adjust the bandwidth of the hybrid power flow controller, thereby achieving the goal of enhancing the suppression effect and improving the suppression response speed. Compared with the traditional method of using a PI controller for adjustment, it is faster while ensuring the suppression effect.

[0046] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this specification. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic flowchart of an overvoltage suppression method provided in an embodiment of this application;

[0049] Figure 2 This is a block diagram of an overvoltage suppression strategy for a hybrid power flow controller that combines adaptive reactive power regulation and adaptive linear active disturbance suppression control, according to an embodiment of this application.

[0050] Figure 3 This is a topology diagram of a hybrid power flow controller provided in an embodiment of this application;

[0051] Figure 4 This is a schematic diagram of the principle of a hybrid power flow controller regulating power flow according to an embodiment of this application;

[0052] Figure 5 This is a schematic diagram illustrating the adjustment effect between a conventional method and the method of this application according to an embodiment of the present application;

[0053] Figure 6 This is a schematic diagram comparing the voltage changes of a conventional method and the method of this application according to an embodiment of the present application;

[0054] Figure 7 This is a schematic diagram comparing the reactive power changes of a conventional method and the method of this application according to an embodiment of the present application;

[0055] Figure 8 This is a schematic diagram of the overvoltage suppression device provided in one embodiment of this application. Detailed Implementation

[0056] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0057] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0058] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0059] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0060] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0061] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0062] This application provides an overvoltage suppression method.

[0063] Figure 1 This is a schematic flowchart of an overvoltage suppression method provided in an embodiment of this application, referring to... Figure 1 The overvoltage suppression method is described in detail below:

[0064] Step 101: Obtain the target overvoltage at the AC bus of the voltage source converter where the fault is located.

[0065] For example, step 101 may include:

[0066] Obtain the original overvoltage data at the AC bus of the voltage source converter where the fault occurred.

[0067] Based on a preset effective overvoltage range, effective overvoltages are selected from the original overvoltage data.

[0068] The effective overvoltage is limited to obtain the target overvoltage.

[0069] For example, the preset effective overvoltage range is 1kV to 1.5kV.

[0070] Specifically, because different faults cause different overvoltage levels, faults at the secondary side of the excitation transformer and the VSC AC bus cause very serious overvoltages, which cannot be effectively suppressed by controlling the VSC output alone. It is necessary to cooperate with the insulation. In order to ensure the effectiveness of the control strategy, it is necessary to screen the effective overvoltage signals and implement a limiting circuit.

[0071] Step 102: Obtain the reactive power reference signal based on the target overvoltage.

[0072] For example, step 102 may include:

[0073] Combining the third formula, a reactive power reference signal is obtained based on the target overvoltage.

[0074] The third formula can be:

[0075]

[0076] Among them, Q ref This represents the reactive power reference signal, and v0 represents the per-unit value of the target overvoltage.

[0077] Step 103: Suppress target overvoltage based on the actual output reactive power of the voltage source converter and the reactive power reference signal.

[0078] Specifically, the voltage level at the VSC AC bus needs to consider not only the impact of the fault location but also the influence of the control strategy. The voltage at the VSC AC bus is affected by the reactive power output of the VSC. When overvoltage occurs, the corresponding reactive power output of the VSC changes. To suppress overvoltage, the reactive power output of the VSC can be adaptively adjusted in reverse to achieve the goal of suppressing overvoltage. For different overvoltage levels, the correspondence between the output reactive power and the suppressed overvoltage level can be obtained. That is, the calculation of different reactive power reference signals corresponding to the target overvoltages within different value ranges is as follows.

[0079] For example, step 103 may include:

[0080] Calculate the difference between the actual output reactive power of the voltage source converter and the reactive power reference signal, and denot it as the first difference.

[0081] Based on the first difference, adjust the bandwidth of the hybrid power flow controller.

[0082] Based on the bandwidth of the hybrid power flow controller, the bandwidth of the linear expansion state observer is set to suppress the target overvoltage.

[0083] For example, adjusting the bandwidth of a voltage source converter based on a first difference may include:

[0084] When the first difference is greater than the first set value, the bandwidth is increased by the adaptive linear active disturbance suppression control hybrid power flow controller.

[0085] When the first difference is less than the first set value, the bandwidth is reduced by the adaptive linear active disturbance suppression control hybrid power flow controller.

[0086] For example, when the first difference is greater than a first set value, the bandwidth is increased by the adaptive linear active disturbance suppression control hybrid power flow controller, including:

[0087] When the first difference is greater than the first set value, the bandwidth is increased by the adaptive linear active disturbance suppression control hybrid power flow controller in combination with the first formula.

[0088] The first formula can be:

[0089] ω + =ω c0 +k(ln10(Q V -Q ref )+Q set )

[0090] Where, ω + ω represents the increased bandwidth. c0 Let Q represent the initial bandwidth, k represent the adaptive adjustment coefficient, and (Q) V -Q ref ) represents the first difference, Q set This indicates the first set value.

[0091] For example, when the first difference is less than a first set value, the bandwidth is reduced by an adaptive linear active disturbance suppression control hybrid power flow controller, including:

[0092] When the first difference is less than the first set value, the bandwidth is reduced by the adaptive linear active disturbance suppression control hybrid power flow controller in conjunction with the second formula.

[0093] The second formula can be:

[0094]

[0095] Where, ω - ω represents the reduced bandwidth. c0 Let Q represent the initial bandwidth, k represent the adaptive adjustment coefficient, and (Q) V -Q ref ) represents the first difference, Q set This indicates the first set value.

[0096] Specifically, since the transient overvoltage caused by the fault is quite complex, using PI regulation to control reactive power output is a control method that eliminates errors based on errors. This method has a certain lag effect, and the effect of suppressing the initial stage of overvoltage and the system response speed cannot meet the actual engineering requirements.

[0097] At this point, based on the reactive power feedback value output by the VSC, an adaptive linear active disturbance rejection control (A-LADRC) method can be used to adaptively adjust the bandwidth parameters of the hybrid power flow controller to suppress overvoltage on the VSC AC bus. The A-LADRC parameters are designed based on the pole placement method of the characteristic equation of linear state error feedback (LSEF) control and linear extended state observer (LESO), and the selection of the hybrid power flow controller bandwidth parameters is designed accordingly.

[0098] 1) Linear state error feedback control

[0099] The linear state error feedback control loop can be represented as:

[0100] u0 = k p (R-z1)-k d z2

[0101]

[0102] Where u0 is the output control quantity of the linear state error feedback control loop; b0 is the gain coefficient; k p k d Z represents the gain coefficient of the hybrid power flow controller; Z1, Z2, and Z3 are the state variables of LESO, respectively; and R is the set system input value.

[0103] Considering that a second-order system can usually be represented as:

[0104]

[0105] Where a1 and a0 are control parameters.

[0106] Referring to the pole placement method, let the bandwidth of the hybrid power flow controller be ω. c The closed-loop poles of the system are set at -ω. c Obtained from:

[0107] s 2 +k d s+k p =(s+ωc ) 2

[0108] Accordingly, we can obtain:

[0109]

[0110] The bandwidth of a hybrid power flow controller is closely related to the system response speed, but it is difficult to achieve fast and accurate system adjustment by simply giving a value, which may result in a response speed that is too fast or too slow.

[0111] To address the aforementioned issues, this method employs an adaptive system bandwidth adjustment approach. By real-time acquisition of the difference between the reactive power output of the VSC and the reactive power reference signal, and comparing it with a first set value, the system bandwidth is altered to achieve precise and rapid adjustment.

[0112] Considering that the overvoltage magnitude and the reactive power output of VSC are within a certain range, k = 5 and Q can be set. set =4.

[0113] When the first difference is higher than the first set value, the bandwidth is increased to speed up the response; when the first difference is less than the first set value, the bandwidth is reduced to avoid oscillation.

[0114] 2) Linear extended state observer

[0115] LESO can estimate system state variables in real time based on system input and output information, and has good disturbance rejection performance for nonlinear systems. The linear extended state observer can be represented as:

[0116]

[0117] Where z1, z2, and z3 are state variables; β1, β2, and β3 are the gain parameters of the linearly extended state observer; and y is the output.

[0118] Considering the feasibility of applying A-LADRC in engineering and the difficulty of adjusting its control parameters, a pole-setting method can be adopted. Setting the bandwidth parameter of the linear extended state observer to ω0, we can obtain:

[0119] s 3 +β1s 2 +β2s+β3=(s+ω0) 3

[0120] Accordingly, we can obtain:

[0121]

[0122] By adjusting the bandwidth ω0 of the linearly extended state observer and the bandwidth ω of the hybrid power flow controller cController parameter design can be implemented. Typically, the observer bandwidth ω0 is taken as 4 to 10 times or 2 to 5 times ω. c Let ω c The control effect is optimal when ω = 500 (pu) and ω0 = 3000 (pu).

[0123] For example, the bandwidth of the linearly extended state observer is 2 to 10 times the bandwidth of the hybrid power flow controller.

[0124] The above-mentioned overvoltage suppression method obtains the reactive power reference signal through target overvoltage calculation. Then, based on the actual output power and the reactive power reference signal, it can adaptively adjust the bandwidth of the hybrid power flow controller, thereby achieving the goal of enhancing the suppression effect and improving the suppression response speed. Compared with the traditional method of using a PI controller for adjustment, it is faster while ensuring the suppression effect.

[0125] To facilitate understanding of this solution, combined with Figure 2-7 This section introduces the overall logic and effects of the proposed solution.

[0126] exist Figure 2 In the diagram, E1 and E2 are the voltages across the power supply, Z1 and Z2 are the corresponding line impedances, and P is the voltage across the power supply. L2 The output power of the line where HPFC is located, U S U L This indicates the voltage across the phase-shifting transformer PST, P L1 For the output power of transmission line L1, U E2 For the secondary side output voltage of the excitation transformer, K E The current voltage ratio of the PST range, z1, z2, and z3 are state variables; β1, β2, and β3 are the gain parameters of the linearly extended state observer; y is the output; b0 is the gain coefficient; ω c U2 is the bandwidth of the hybrid power flow controller; U2 is the compensation amount; ω0 is the bandwidth of the linearly extended state observer; P ref k is the reference power, u0 is the output control quantity of the linear state error feedback control loop; p k d U1 is the gain coefficient of the hybrid power flow controller, U2 is the VSC regulation voltage, U3 is the output voltage of the VSC during normal operation, and U4 is the output voltage of the hybrid power flow controller. T1 For the primary side voltage of the excitation transformer, U qref Given the q-axis voltage component.

[0127] In this embodiment, the Hybrid Power Flow Controller (HPFC) comprises two parts: a Phase Shift Transformer (PST) and a Voltage Controller (VSC). During normal operation, the VSC compensates the system voltage to coordinate with the PST and control the system's power flow. During overvoltage periods, the control loop includes a Linear Extended State Observer (LESO) and a Linear State Error Feedback (LSEF) control, forming an Adaptive Linear Active Disturbance Rejection Control (A-LADRC) control.

[0128] When a three-phase ground fault occurs on the primary side of the excitation transformer in the HPFC system, the fault causes the voltage on the secondary side of the excitation transformer to drop to zero. The current on the connection line between the VSC and the secondary side of the excitation transformer increases. At this time, the reactive power consumed by the VSC increases, and an overvoltage occurs at the AC bus of the VSC.

[0129] To achieve overvoltage suppression, reactive power can be suppressed by controlling the VSC to reverse its reactive power supply. The overvoltage signal at the VSC AC bus is used as input to obtain the corresponding reactive power reference signal Q. ref To ensure the validity of the reactive power reference signal output by the VSC, it needs to be limited.

[0130]

[0131] Among them, Q ref This represents the reactive power reference signal, and v0 represents the overvoltage magnitude (per unit value).

[0132] When dealing with transient overvoltage problems caused by faults, the traditional PI control method will have a certain lag, and often cannot meet the actual engineering requirements in the initial stage of overvoltage suppression and system response speed. To solve this problem, adaptive linear active disturbance rejection control (A-LADRC) technology can be used based on the reactive power feedback value of the VSC output. By adaptively adjusting the controller bandwidth parameter, the linear state error feedback control and linear state extension observer parameters in A-LADRC are designed to effectively suppress the overvoltage phenomenon of the VSC AC bus.

[0133] Q ref As the setpoint input for linear state error feedback control, referring to the pole placement method, let the bandwidth of the hybrid power flow controller be ω. c The closed-loop poles of the system are set at -ω. c The relationship between the bandwidth of the hybrid power flow controller and the controller gain coefficient is as follows:

[0134]

[0135] Adjusting the system bandwidth alone is insufficient for rapid and precise control. A better approach is to monitor the difference between the actual and reference values ​​of the reactive power output from the VSC in real time, compare this difference with the power setpoint, and adjust the system bandwidth accordingly. The setpoint power value is defined as Q. set .make:

[0136]

[0137] Where k is the adaptive adjustment coefficient; Q V For VSC, output reactive power; Q ref This is a reference value for reactive power; ω c0 This is the initial bandwidth.

[0138] Considering that the overvoltage magnitude and the reactive power output of VSC are within a certain range, k = 5 and Q can be set. set =4.

[0139] When the first difference is higher than the first set value, the bandwidth is increased to speed up the response; when the first difference is less than the first set value, the bandwidth is reduced to avoid oscillation.

[0140] To improve the system's disturbance rejection performance, the linear extended state observer collects system inputs and outputs and estimates system state variables in real time. The linear extended state observer can be represented as:

[0141]

[0142] Where z1, z2, and z3 are state variables; β1, β2, and β3 are the gain parameters of the linearly extended state observer; and y is the output.

[0143] Referring to the pole placement method, the relationship between the observer gain parameter and the bandwidth parameter is obtained as follows:

[0144]

[0145] By adjusting the bandwidth ω0 of the linear state observer and the bandwidth ω of the hybrid power flow controller c It allows for system parameter design. Ultimately, it enables rapid and effective suppression of overvoltage at the VSC AC bus.

[0146] exist Figure 3The paper details the structure of a hybrid power flow controller, combining a power transfer stage (PST) with a voltage regulator (VSC) for continuous and precise control of line power flow. The PST employs a dual-core symmetrical phase-shifting transformer, consisting of a series transformer (ST) and an excitation transformer (ET). The PST is connected in series with the transmission line, and by changing the voltage across the transmission line, it regulates the voltage at the L-end of the transmission line, thereby achieving power flow regulation. Figure 3 The primary side of the ST is connected in series with the transmission line, and the secondary side is delta connected; the primary and secondary sides of the ET are both star connected.

[0147] PST structure as follows Figure 3 As shown. The PST is connected in series in the transmission line. By changing the voltage connected in series with the transmission line, the voltage at terminal L of the transmission line is adjusted, where K... E K represents the ET ratio. S This indicates the ST ratio.

[0148] Taking phase A as an example, the excitation transformer obtains voltage from the transmission line, and the primary and secondary voltages of the excitation transformer are U. E1A U E2A The voltage across PST is The phase difference between the two ends is e jδ The compensation voltage of the series transformer connected in series with the transmission line is U. stA :

[0149] U stA =K S (U E2C -U E2B )

[0150] U E2A =K E U E1A

[0151] U SA -U LA =U stA

[0152]

[0153] Change K by adjusting the ET tap E This changes the secondary voltage U. E2A Then adjust ST ratio K S It can change the voltage of the line inserted in series, thereby changing the line voltage and power flow.

[0154] On the secondary side of the excitation transformer, a VSC is connected in series and used in conjunction with a phase-shifting transformer. Utilizing the adjustable output voltage characteristic of the VSC, the output voltage U is adjusted according to the target power flow. E3A With the secondary voltage U of ET E2ACoaxial superposition further adjusts the voltage returned to the line by ET, thereby adjusting the phase difference and power flow at both ends of PST, and finely regulating the power flow of the system.

[0155] Taking phase A as an example, when PST operates independently, the phase difference between the two ends of the line is δ1, while the phase difference corresponding to the target power is δ2. At this time, by controlling the output of VSC and U... E2A Voltage U in phase E3A By ensuring the phase difference between the two ends of the line reaches the target value δ2, the power flow of the line can reach the target value, specifically as follows: Figure 4 As shown.

[0156] like Figure 5 As shown, the overvoltage suppression strategy provided in this embodiment can quickly and effectively suppress overvoltage at the VSC AC bus.

[0157] in, Figure 5 Taking phase A as an example, the proposed method of controlling the reactive power output of VSC to suppress overvoltage at the VSC AC bus has been proven effective. The HPFC overvoltage suppression effect, which combines reactive power adaptive regulation and A-LADRC control, is significantly better than the traditional PI regulation, and the suppression speed is faster. Figure 6 The system characterizes the voltage amplitude change at the VSC AC bus. Compared with traditional PI regulation, the HPFC overvoltage suppression strategy, which combines reactive power adaptive regulation and A-LADRC control, has a faster system response speed, effectively solves the problem of lag effect in traditional PI regulation, and has a more obvious suppression effect in the initial stage. Figure 7 Characterizing the change in reactive power output of VSC, compared with traditional PI regulation, the method provided in this example, which combines reactive power adaptive regulation and HPFC overvoltage suppression controlled by A-LADRC, can better regulate the reactive power of VSC, effectively reduce the difficulty of parameter design, shorten the system's stabilization time, and achieve better suppression effect in the initial stage.

[0158] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0159] Corresponding to the overvoltage suppression method described in the above embodiments, Figure 8 A structural block diagram of an overvoltage suppression device provided in an embodiment of this application is shown. For ease of explanation, only the parts related to the embodiment of this application are shown.

[0160] See Figure 8 The overvoltage suppression device in this application embodiment may include:

[0161] The data acquisition module 201 is used to acquire the target overvoltage at the AC bus of the voltage source converter where the fault occurs.

[0162] The data calculation module 202 is used to obtain the reactive power reference signal based on the target overvoltage.

[0163] The voltage suppression module 203 is used to suppress target overvoltage based on the actual output reactive power and reactive power reference signal of the voltage source converter.

[0164] For example, the voltage suppression module 203 can be used to:

[0165] Calculate the difference between the actual output reactive power of the voltage source converter and the reactive power reference signal, and denot it as the first difference.

[0166] Based on the first difference, adjust the bandwidth of the hybrid power flow controller.

[0167] Based on the bandwidth of the hybrid power flow controller, the bandwidth of the linear expansion state observer is set to suppress the target overvoltage.

[0168] For example, the voltage suppression module 203 can also be used for:

[0169] When the first difference is greater than the first set value, the bandwidth is increased by the adaptive linear active disturbance suppression control hybrid power flow controller.

[0170] When the first difference is less than the first set value, the bandwidth is reduced by the adaptive linear active disturbance suppression control hybrid power flow controller.

[0171] For example, the voltage suppression module 203 can also be used for:

[0172] When the first difference is greater than the first set value, the bandwidth is increased by the adaptive linear active disturbance suppression control hybrid power flow controller in combination with the first formula.

[0173] The first formula can be:

[0174] ω + =ω c0 +k(ln10(Q V -Q ref )+Q set )

[0175] Where, ω + ω represents the increased bandwidth. c0 Let Q represent the initial bandwidth, k represent the adaptive adjustment coefficient, and (Q) V -Q ref ) represents the first difference, Q set This indicates the first set value.

[0176] For example, the voltage suppression module 203 can also be used for:

[0177] When the first difference is less than the first set value, the bandwidth is reduced by the adaptive linear active disturbance suppression control hybrid power flow controller in conjunction with the second formula.

[0178] The second formula can be:

[0179]

[0180] Where, ω - ω represents the reduced bandwidth. c0 Let Q represent the initial bandwidth, k represent the adaptive adjustment coefficient, and (Q) V -Q ref ) represents the first difference, Q set This indicates the first set value.

[0181] For example, the bandwidth of the linearly extended state observer is 2 to 10 times the bandwidth of the hybrid power flow controller.

[0182] For example, the data acquisition module 201 may include:

[0183] Obtain the original overvoltage data at the AC bus of the voltage source converter where the fault occurred.

[0184] Based on a preset effective overvoltage range, effective overvoltages are selected from the original overvoltage data.

[0185] The effective overvoltage is limited to obtain the target overvoltage.

[0186] For example, the preset effective overvoltage range is 1kV to 1.5kV.

[0187] For example, the data computing module 202 may include:

[0188] Combining the third formula, a reactive power reference signal is obtained based on the target overvoltage.

[0189] The third formula can be:

[0190]

[0191] Among them, Q ref This represents the reactive power reference signal, and v0 represents the per-unit value of the target overvoltage.

[0192] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0193] Those skilled in the art will recognize that the templates, units, and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0194] If the module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various overvoltage suppression method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0195] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. An overvoltage suppression method, characterized in that, include: Obtain the target overvoltage at the AC bus of the voltage source converter where the fault occurs; Based on the target overvoltage, a reactive power reference signal is obtained; Based on the actual output reactive power and reactive power reference signal of the voltage source converter, the target overvoltage is suppressed; The method of suppressing the target overvoltage based on the actual output reactive power and reactive power reference signal of the voltage source converter includes: Calculate the difference between the actual output reactive power of the voltage source converter and the reactive power reference signal, and denote it as the first difference; Based on the first difference, adjust the bandwidth of the hybrid power flow controller; Based on the bandwidth of the hybrid power flow controller, the bandwidth of the linear expansion state observer is set to suppress the target overvoltage; Wherein, adjusting the bandwidth of the voltage source converter based on the first difference includes: When the first difference is greater than the first set value, the bandwidth of the hybrid power flow controller is increased by adaptive linear active disturbance suppression control. When the first difference is less than the first set value, the bandwidth of the hybrid power flow controller is reduced by adaptive linear active disturbance suppression control. When the first difference is greater than a first set value, the hybrid power flow controller increases the bandwidth through adaptive linear active disturbance suppression control, including: When the first difference is greater than the first set value, the bandwidth of the hybrid power flow controller is increased by combining the first formula through adaptive linear active disturbance suppression control. The first formula is: in, This indicates the increased bandwidth. Indicates the initial bandwidth. This represents the adaptive adjustment coefficient. This represents the first difference. This represents the first set value.

2. The overvoltage suppression method as described in claim 1, characterized in that, When the first difference is less than the first set value, the hybrid power flow controller reduces the bandwidth by adaptive linear active disturbance suppression control, including: When the first difference is less than the first set value, the bandwidth of the hybrid power flow controller is reduced by using the second formula through adaptive linear active disturbance suppression control. The second formula is: in, This indicates the reduced bandwidth. Indicates the initial bandwidth. This represents the adaptive adjustment coefficient. This represents the first difference. This represents the first set value.

3. The overvoltage suppression method as described in claim 1, characterized in that, The bandwidth of the linearly extended state observer is 2 to 10 times the bandwidth of the hybrid power flow controller.

4. The overvoltage suppression method as described in claim 1, characterized in that, The acquisition of the target overvoltage at the AC bus of the voltage source converter includes: Acquire the original overvoltage data at the AC bus of the voltage source converter where the fault occurred; Based on a preset effective overvoltage range, effective overvoltages are selected from the original overvoltage data; The effective overvoltage is limited to obtain the target overvoltage.

5. The overvoltage suppression method as described in claim 4, characterized in that, The preset effective overvoltage range is 1kV to 1.5kV.

6. The overvoltage suppression method as described in claim 1, characterized in that, The process of obtaining the reactive power reference signal based on the target overvoltage includes: Based on the target overvoltage, the reactive power reference signal is obtained by combining the third formula. The third formula is: in, This represents the reactive power reference signal. This represents the per-unit value of the target overvoltage.

7. An overvoltage suppression device for performing the overvoltage suppression method according to any one of claims 1 to 6, characterized in that, include: The data acquisition module is used to acquire the target overvoltage at the AC bus of the voltage source converter where the fault occurs; The data calculation module is used to obtain a reactive power reference signal based on the target overvoltage; The voltage suppression module is used to suppress the target overvoltage based on the actual output reactive power of the voltage source converter and the reactive power reference signal.

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