Method and device for inhibiting sympathetic inrush current

Abstract

The invention provides a method and a device for suppressing sympathetic inrush current, and the method and the device are applied to any flexible direct current high-low voltage valve group in a high-voltage direct current transmission system, and the method comprises the steps: responding to a received converter transformer air-drop signal sent by other flexible direct current high-low voltage valve groups, and obtaining an electrical signal of a valve side; switching an electrical signal input to a control system of the high-voltage direct-current power transmission system to an electrical signal on the valve side; and current inner loop control parameters are corrected according to the electrical signal of the valve side so as to suppress the converter transformer valve side and sympathetic inrush current of the local flexible DC high-low voltage valve group. According to the invention, the valve side and sympathetic inrush current of the flexible direct current high-low voltage valve group are inhibited through the current inner ring, and the problem of bridge arm overcurrent of the valve group in normal operation caused by the sympathetic inrush current in the prior art is well solved, so that the loss is reduced, and the bridge arm overcurrent protection misoperation is avoided. And secondly, an original control structure of the system is reserved, and only a switching strategy for controlling electrical feedback signal input of the system is added, so that the cost is saved, and the original stability of the system is not influenced.

Description

Technical Field

[0001] The present invention relates to the technical field of power system operation and control, in particular to the technical field of relay protection of flexible DC converter stations, and specifically to a method and device for suppressing a response inrush current. Background Art

[0002] At present, vigorously developing new energy represented by wind power and photovoltaics has become an inevitable choice for energy transformation of major companies. However, primary energy and demand are distributed inversely, so it is necessary to realize power transmission through a high-voltage direct current transmission system (High Voltage Direct Current, HVDC). Compared with the traditional direct current high-voltage transmission system (Line-Commutated Converter based High Voltage Direct Current, LCC-HVDC), the high-voltage direct current transmission system based on voltage source converter (Voltage Source Converter based High Voltage Direct Current, VSC-HVDC) has the unique advantages of being able to supply power to passive systems, no risk of commutation failure, and fast control of power decoupling, and has a broader development prospect.

[0003] In order to achieve higher voltage levels and greater transmission capacity, the flexible DC converter station in the VSC-HVDC system usually adopts a high- and low-voltage valve group series topology. In the process of unlocking the flexible DC converter station and successively commissioning the high- and low-voltage valve groups, the converter transformers of the commissioned valve groups will be affected by the no-load commissioning of other valve group converter transformers, which will produce a response surge phenomenon. Due to the existence of response surges, the valve-side current of the commissioned valve group converter transformer will be greatly distorted. When the DC bias component and high-order harmonic components invade the DC side, it will cause the valve group bridge arm to overcurrent, resulting in large power loss, affecting the safety and life of the valve group power electronic equipment, and even causing the valve group bridge arm overcurrent protection to malfunction, thereby causing the flexible DC converter station to shut down.

[0004] In order to eliminate the influence of the inrush current, some scholars have studied the generation mechanism and suppression measures of the inrush current. After searching, the patent with application number CN201911225163.9 discloses a method for identifying the inrush current of the converter transformer based on the positive-sequence second harmonic. The method determines whether the inrush current occurs by detecting the positive-sequence second harmonic component of the AC current. However, the free component of the inrush current with slow decay can easily cause the current transformer to saturate, resulting in the inability to accurately detect the second harmonic content of the positive-sequence current, resulting in misjudgment of whether the inrush current exists, and thus the inrush current cannot be effectively suppressed.

[0005] In summary, it is necessary to propose a control method that can effectively suppress the surge flow on the valve side of the flexible direct current high and low pressure valve group converter and avoid overcurrent in the valve group bridge arm, so as to improve the ability of the flexible direct current high and low pressure valve group to resist the interference of surge flow. Summary of the invention

[0006] The method and device for suppressing the response surge current provided by the present invention are designed to solve the problem of false operation of the overcurrent protection of the bridge arm of the flexible direct current valve group caused by the response surge current, while considering suppressing the overcurrent of the bridge arm caused by the response surge current and retaining the original control structure without affecting the stability of the system.

[0007] In order to achieve the above-mentioned purpose, in the first aspect, the present invention provides a method for suppressing a surge current, which is applied to any flexible high- and low-pressure valve group in a high-voltage direct current transmission system, comprising:

[0008] In response to the received converter transformer airdrop signal sent by other flexible direct current high and low pressure valve groups, the electrical signal on the valve side is obtained;

[0009] Switching an electrical signal input to a control system of the high voltage direct current transmission system to an electrical signal on the valve side;

[0010] The current inner loop control parameters are corrected according to the electrical signal on the valve side to suppress the converter valve side and the inrush current of the local flexible direct current high and low pressure valve group.

[0011] In some embodiments of the present invention, the electrical signal is a dq axis component; the step of acquiring the electrical signal on the valve side includes:

[0012] Collect the grid-side voltage signal, grid-side current signal, valve-side voltage signal and valve-side current signal of the local transformer;

[0013] The dq-axis components of the valve side are acquired according to the grid-side voltage signal, the grid-side current signal, the valve-side voltage signal, and the valve-side current signal.

[0014] In some embodiments of the present invention, obtaining the dq-axis components of the valve side according to the grid-side voltage signal, the grid-side current signal, the valve-side voltage signal, and the valve-side current signal includes:

[0015] Phase-locking the grid-side voltage signal and the valve-side voltage signal respectively to obtain a grid-side voltage phase and a valve-side voltage phase;

[0016] The grid-side voltage signal, the grid-side current signal, the valve-side voltage signal and the valve-side current signal are subjected to Park transformation according to the grid-side voltage phase and the valve-side voltage phase to obtain the dq-axis components of the valve side.

[0017] In some embodiments of the present invention, the step of switching the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal on the valve side includes:

[0018] Inputting the electrical signal of the control system into a series low-pass filter to filter the electrical signal;

[0019] The filtered electrical signal of the control system is switched to the electrical signal of the valve side.

[0020] In some embodiments of the present invention, the control parameter is an inductance control parameter; and the control parameter of the inner current loop is corrected according to the electrical signal on the valve side, including:

[0021] Establishing a relationship between the dq-axis components of the valve-side voltage modulation signal and the electrical signal on the valve side according to the structure of the current inner loop;

[0022] The inductance control parameter of the inner current loop is corrected according to the relationship.

[0023] In a second aspect, the present invention provides a device for suppressing a surge current, which is applied to any flexible high- and low-pressure valve group in a high-voltage direct current transmission system, and the device comprises:

[0024] An electrical signal acquisition module, used for acquiring the electrical signal on the valve side in response to the received inverter airdrop signal sent by other flexible direct current high and low pressure valve groups;

[0025] An electrical signal switching module, used for switching the electrical signal input to the control system of the high voltage direct current power transmission system to the electrical signal on the valve side;

[0026] The control parameter correction module is used to correct the current inner loop control parameters according to the electrical signal on the valve side to suppress the inrush current on the converter valve side of the local flexible direct high and low pressure valve group.

[0027] In some embodiments of the present invention, the electrical signal is a dq axis component; the electrical signal acquisition module includes:

[0028] A signal acquisition unit, used to acquire a grid-side voltage signal, a grid-side current signal, a valve-side voltage signal, and a valve-side current signal of a local transformer;

[0029] The dq axis component acquisition unit is used to acquire the dq axis component of the valve side according to the grid side voltage signal, the grid side current signal, the valve side voltage signal and the valve side current signal.

[0030] In some embodiments of the present invention, the dq-axis component acquisition unit includes:

[0031] a voltage phase acquisition unit, used to phase-lock the grid-side voltage signal and the valve-side voltage signal respectively, so as to acquire a grid-side voltage phase and a valve-side voltage phase;

[0032] The dq axis component acquisition subunit is used to perform Park transformation on the grid side voltage signal, grid side current signal, valve side voltage signal and valve side current signal according to the grid side voltage phase and the valve side voltage phase to obtain the dq axis component of the valve side.

[0033] In some embodiments of the present invention, the electrical signal switching module includes:

[0034] an electrical signal filtering unit, used for inputting the electrical signal of the control system into a series low-pass filter to filter the electrical signal;

[0035] The electrical signal switching unit is used to switch the filtered electrical signal of the control system to the electrical signal of the valve side.

[0036] In some embodiments of the present invention, the control parameter is an inductance control parameter; and the control parameter correction module includes:

[0037] A relationship establishing unit, used to establish a relationship between the dq-axis components of the valve-side voltage modulation signal and the electrical signal on the valve side according to the structure of the current inner loop;

[0038] A control parameter correction unit is used to correct the inductance control parameter of the current inner loop according to the relationship.

[0039] In a third aspect, the present invention provides a computer program product, comprising a computer program / instruction, which, when executed by a processor, implements the steps of a method for suppressing a response inrush current.

[0040] In a fourth aspect, the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of a method for suppressing a surge current when executing the program.

[0041] In a fifth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a method for suppressing a surge current.

[0042] From the above description, it can be seen that a method and device for suppressing response inrush current provided in an embodiment of the present invention are applied to any flexible direct current high and low pressure valve group in a high voltage direct current transmission system, and the corresponding method includes: first, responding to the converter transformer air drop signal received from other flexible direct current high and low pressure valve groups, and acquiring the electrical signal on the valve side; then, switching the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal on the valve side; finally, correcting the current inner loop control parameters according to the electrical signal on the valve side to suppress the response inrush current on the converter transformer valve side of the local flexible direct current high and low pressure valve group.

[0043] The corresponding device includes: an electrical signal acquisition module, which is used to obtain the electrical signal of the valve side in response to the received converter transformer air-drop signal issued by other flexible direct current high and low pressure valve groups; an electrical signal switching module, which is used to switch the electrical signal of the control system input to the high voltage direct current transmission system to the electrical signal of the valve side; a control parameter correction module, which is used to correct the current inner loop control parameters according to the electrical signal of the valve side to suppress the converter transformer valve side and the inrush current of the local flexible direct current high and low pressure valve group.

[0044] First, the present invention suppresses the surge current on the valve side of the flexible high and low pressure valve group through the current inner loop, which effectively solves the problem of overcurrent in the bridge arm of the normal operation valve group caused by the surge current in the prior art, thereby reducing losses and avoiding malfunction of the bridge arm overcurrent protection. Secondly, the present invention retains the original control structure of the system and only adds the switching strategy of the electrical feedback signal input of the control system, thus saving costs and not affecting the original stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 A schematic flow chart of a method for suppressing a response surge provided in an embodiment of the present invention;

[0047] Figure 2 A schematic flow chart of step 100 of a method for suppressing a surge current provided in an embodiment of the present invention;

[0048] Figure 3 1 is a flow chart of step 102 of a method for suppressing a surge current provided in an embodiment of the present invention;

[0049] Figure 4 A schematic flow chart of step 200 of a method for suppressing a surge current provided in an embodiment of the present invention;

[0050] Figure 5 A schematic flow chart of step 300 of a method for suppressing a surge current provided in an embodiment of the present invention;

[0051] Figure 6 A schematic flow chart of a method for suppressing a surge current provided in a specific application example of the present invention;

[0052] Figure 7 It is a schematic diagram of the flexible direct current high and low pressure valve group topology and the network side valve side electrical quantity collection provided in the specific application example of the present invention;

[0053] Figure 8 A logic diagram for selecting an electrical feedback input signal of a control system provided in a specific application example of the present invention;

[0054] Fig. 9 The current inner loop control frame provided in the specific application example of the present invention Figure 1 ;

[0055] Fig.10 The current inner loop control frame provided in the specific application example of the present invention Figure 2 ;

[0056] Fig.11 It is a schematic diagram of the simulation results of the three-phase current on the side of the operated valve group converter transformer when the grid-side electrical signal control is adopted in the specific application example of the present invention;

[0057] Fig.12 It is a schematic diagram of the simulation results of the three-phase current on the valve side of the operated valve group converter transformer when the valve side electrical signal control is adopted in the specific application example of the present invention;

[0058] Fig.13 A schematic diagram of the structure of a device for suppressing a surge current provided in an embodiment of the present invention;

[0059] Fig.14 It is a structural schematic diagram of the electrical signal acquisition module 10 provided in an embodiment of the present invention;

[0060] Fig.15 Schematic diagram of the structure of the dq-axis component acquisition unit 10b provided in an embodiment of the present invention;

[0061] Fig.16 It is a structural schematic diagram of the electrical signal switching module 20 provided in an embodiment of the present invention;

[0062] Fig.17 It is a structural schematic diagram of a control parameter correction module 30 provided in an embodiment of the present invention;

[0063] Fig.18It is a schematic diagram of the structure of an electronic device in an embodiment of the present invention. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention 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.

[0066] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatuses.

[0067] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0068] In addition, the patent application number CN202111240329.1 (locking method for preventing transformer differential protection from malfunction caused by inrush current) provides a method, which includes: calculating the three-phase differential current value of the transformer; judging whether there is a phase difference between the second harmonic phase in the differential current and the 2 times fundamental current phase when the transformer generates inrush current; when judging that there is a phase difference between the second harmonic phase in the differential current and the 2 times fundamental current phase when the transformer generates inrush current, calculating the second harmonic proportion value when the transformer generates inrush current and fails; judging whether the second harmonic proportion value is not less than the proportion coefficient Kd; judging that the second harmonic proportion value is less than the proportion coefficient Kd, judging whether the current value of the differential current is not less than the set value Iset; when judging that the current value of the differential current is less than the set value Iset, locking the differential protection. And the application number CN202310883119.7 (Identification method of summed surge current and short-circuit current in transformer differential protection) provides a method, which includes: using the characteristic that the phase difference of the differential current is greater than the phase difference when the summed surge current occurs and is greater than the phase difference when the current transformer is saturated when a short-circuit fault occurs during the summed surge current, as the phase difference step criterion of the differential current under different circumstances, and identifying the summed surge current and short-circuit current in the transformer based on the phase difference step criterion.

[0069] The above two methods can accurately identify the response surge current through the phase difference, thereby avoiding false protection operation, but they do not suppress the response surge current, and the bridge arm overcurrent phenomenon still exists, which not only causes losses but also affects the safety and life of the valve group power electronic equipment.

[0070] Based on the above reasons, the embodiment of the present invention provides a specific implementation method of a method for suppressing a surge current, which is applied to any flexible high and low pressure valve group in a high voltage direct current transmission system, see Figure 1 , the method specifically includes the following contents:

[0071] Step 100: Responding to the received inverter drop signal sent by other flexible direct current high and low pressure valve groups, obtaining the valve side electrical signal;

[0072] Step 200: Switching the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal on the valve side;

[0073] Step 300: Correct the current inner loop control parameters according to the electrical signal on the valve side to suppress the inrush current on the converter valve side of the local flexible direct current high and low pressure valve group.

[0074] From the above description, it can be seen that a method for suppressing response inrush current provided in an embodiment of the present invention is applied to any flexible direct current high and low pressure valve group in a high voltage direct current transmission system, comprising: first, responding to the converter transformer drop signal received from other flexible direct current high and low pressure valve groups, and acquiring the electrical signal on the valve side; then, switching the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal on the valve side; finally, correcting the current inner loop control parameters according to the electrical signal on the valve side to suppress the response inrush current on the converter transformer valve side of the local flexible direct current high and low pressure valve group.

[0075] After receiving the airdrop signal of other valve group converters, the present invention switches the electrical feedback signal input to the control system from the grid side to the valve side, thereby relying on the advantages of high current control accuracy and fast dynamic response of the current inner loop current, quickly suppressing the valve side and the surge current of the flexible high and low pressure valve group, and solving the problem of overcurrent in the bridge arm of the normal operation valve group caused by the surge current in the prior art, thereby reducing losses and avoiding malfunction of the bridge arm overcurrent protection. The present invention retains the original control structure of the system and only adds the switching strategy of the electrical feedback signal input of the control system, thus saving costs and not affecting the original stability of the system.

[0076] With respect to step 100, the main function of the flexible DC high and low pressure valve group is to adjust the voltage and frequency of AC power by controlling DC current, so as to realize energy conversion and management in the DC transmission system. Specifically:

[0077] The commutation process, when AC passes through the converter valve, it is converted into DC, and similarly, when DC passes through the converter valve, it is converted back into AC. This conversion process requires fast and precise control to ensure the stability of the entire system.

[0078] Converter assembly: The converter valve is usually composed of multiple parts, including IGBT driver board, water-melting board, etc. These parts are crimped together to form a complete flexible DC module. This module is one of the central equipment of the converter station, responsible for completing the conversion from AC to DC and DC to AC.

[0079] In addition, the method of steps 100 to 300 uses the commutation transformer air-drop signal of other valve groups as the enable signal, that is, when the commutation transformer air-drop signal of other valve groups is received, the method of steps 100 to 300 is enabled, and at other times, the above method is not started, and the conventional control method based on the grid-side electrical signal is adopted.

[0080] When step 200 is implemented, the electrical feedback signal input to the control system of the high voltage direct current transmission system is switched from the grid side to the valve side.

[0081] For step 300, the current inner loop control is performed on the basis of the voltage outer loop control, and its goal is to adjust and maintain the current signal stable. A PI controller can be used to correct the current error. Specifically, the output of the PI controller adjusts the current output according to the accumulation of the current current error and the integral current error. When the current error is large, the PI controller will output a large correction signal to increase the current output. When the current error is small, the PI controller will output a small correction signal to reduce the current output. Through this adjustment method, the current can be kept near the set value.

[0082] In some embodiments of the present invention, the electrical signal is a dq axis component; see Figure 2 , step 100 comprises:

[0083] Step 101: collecting a grid-side voltage signal, a grid-side current signal, a valve-side voltage signal, and a valve-side current signal of a local transformer;

[0084] Specifically, the grid-side voltage signal u of the transformer is collected. g And the grid-side current signal i g ; Collect the transformer valve side voltage signal u v And the valve side current signal i v .

[0085] Step 102: Acquire the dq-axis components of the valve side according to the grid-side voltage signal, the grid-side current signal, the valve-side voltage signal, and the valve-side current signal.

[0086] In some embodiments of the present invention, see Figure 3 , step 102 comprises:

[0087] Step 1021: respectively phase-locking the grid-side voltage signal and the valve-side voltage signal to obtain a grid-side voltage phase and a valve-side voltage phase;

[0088] Through the grid-side voltage signal u g Phase lock, obtain the grid side voltage phase θ g ; Through the valve side voltage signal u v Phase lock, obtain the valve side voltage phase θ v ;

[0089] Step 1022: Perform Park transformation on the grid-side voltage signal, grid-side current signal, valve-side voltage signal and valve-side current signal according to the grid-side voltage phase and the valve-side voltage phase to obtain the dq-axis components of the valve side.

[0090] According to the grid-side and valve-side voltage phases, Park transformation is performed on the grid-side and valve-side electrical signals to obtain the dq-axis components of the grid-side and valve-side electrical signals, which can be specifically expressed as:

[0091]

[0092] In the formula, u ga 、u gb 、u gc are the grid-side phase a, phase b, and phase c voltages respectively; u va 、u vb 、u vc are the voltages of phase a, phase b, and phase c on the valve side respectively; u gd 、u gq are the d-axis and q-axis components of the grid-side voltage respectively; u vd 、u vq are the d-axis and q-axis components of the valve side voltage respectively; i ga 、i gb 、i gc are the grid-side phase a, phase b, and phase c currents respectively; i va 、i vb 、i vc are the currents of phase a, phase b, and phase c on the valve side respectively; i gd 、i gq are the d-axis and q-axis components of the grid-side current respectively; i vd 、i vq are the d-axis and q-axis components of the valve side current respectively; T abc2dq (θ) is the fundamental frequency Parker transform, where:

[0093]

[0094] In some embodiments of the present invention, see Figure 4 , step 200 comprises:

[0095] Step 201: Inputting the electrical signal of the control system into a series low-pass filter to filter the electrical signal;

[0096] A series low-pass filter is used to reduce the portion of a signal above a certain cutoff frequency while allowing low-frequency signals to pass.

[0097] The basic working principle of the series low-pass filter is to use the frequency-dependent characteristics of inductance and capacitance to achieve frequency selection of the signal. In a simple RC (resistance-capacitance) or RL (resistance-inductance) low-pass filter, the input signal passes through the filter elements connected in series, and the output is taken at the node between the resistor and the capacitor or inductor.

[0098] RC low-pass filter: In an RC filter, as the frequency increases, the impedance of the capacitor (i.e., the resistance to current flow) decreases, causing high-frequency signals to leak out mainly through the capacitor, while low-frequency signals are able to pass through the circuit due to the higher impedance of the capacitor.

[0099] RL low-pass filter: In an RL filter, the inductor has a smaller impedance to low-frequency signals, allowing them to pass through; while for high-frequency signals, the impedance of the inductor increases, limiting the passage of the signal.

[0100] Step 202: Switch the filtered electrical signal of the control system to the electrical signal on the valve side.

[0101] In step 201 and step 202, due to the difference between the electrical signals on the grid side and the valve side, a low pass filter (LPF) needs to be connected in series in the dq axis component input channel of the control system electrical feedback signal to achieve smooth switching of the input signal. Specifically: the electrical feedback signal input to the control system is switched from the grid side to the valve side, that is:

[0102]

[0103] Among them, u d 、u q Respectively represent the d-axis and q-axis components of the voltage feedback signal input to the control system; i d 、i q They represent the d-axis and q-axis components of the current feedback signal input to the control system respectively; θ represents the phase-locked phase input to the control system.

[0104] In some embodiments of the present invention, the control parameter is an inductance control parameter, see Figure 5 , step 300 comprises:

[0105] Step 301: establishing a relationship between the dq-axis components of the valve-side voltage modulation signal and the electrical signal of the valve-side according to the structure of the current inner loop;

[0106] Specifically, the dq axis components of the valve side voltage modulation signal are established according to the current inner loop structure: The electrical signal u on the valve side d 、u q 、i d 、i q The relationship between .

[0107] Step 302: Correct the inductance control parameter of the inner current loop according to the relationship.

[0108] In some embodiments of the present invention, the other valve group commutation change empty drop signal is used as the enable signal EN of the method for suppressing the inrush current provided in the embodiment of the present invention, that is, when the other valve group commutation change empty drop signal is not received, EN is set to 0, the method is not started, and the conventional control method based on the grid-side electrical signal is adopted; after the other valve group commutation empty drop signal is received, EN is set to 1 to enable the method:

[0109]

[0110] From the above description, it can be seen that a method for suppressing response inrush current provided in an embodiment of the present invention is applied to any flexible direct current high and low pressure valve group in a high voltage direct current transmission system, comprising: first, responding to the converter transformer drop signal received from other flexible direct current high and low pressure valve groups, and acquiring the electrical signal on the valve side; then, switching the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal on the valve side; finally, correcting the current inner loop control parameters according to the electrical signal on the valve side to suppress the response inrush current on the converter transformer valve side of the local flexible direct current high and low pressure valve group.

[0111] Based on the advantages of high current control accuracy and fast dynamic response of the current inner loop, the present invention switches the electrical feedback signal input to the control system from the grid side to the valve side after receiving the air-drop signal of the converter transformer of other valve groups, thereby using the current inner loop to quickly suppress the valve side of the converter transformer and the inrush current.

[0112] See also Figure 6 To further illustrate the present solution, the present invention also provides a specific application example of a method for suppressing a surge flow, which specifically includes the following steps.

[0113] First, a flexible DC converter station model with high and low pressure valve groups in series is built, such as Figure 7 For the convenience of explanation, the low-pressure valve group of the flexible DC converter station is put into operation first. At 1.5s, the high-pressure valve group converter transformer is put into no-load operation.

[0114] S1: Obtain the dq-axis components of the electrical signals on the grid side and valve side;

[0115] See also Figure 7 First, collect the grid-side voltage signal u of the transformer g And the grid-side current signal i g ; Next, collect the transformer valve side voltage signal u v And the valve side current signal i v ; Through the grid-side voltage signal u g Phase lock, obtain the grid side voltage phase θ g ; Through the valve side voltage signal u v Phase lock, obtain the valve side voltage phase θ v ; Finally, Parker transformation is performed on the grid side and valve side electrical signals based on the grid side and valve side voltage phases to obtain the dq axis components of the grid side and valve side electrical signals.

[0116] S2: Set the airdrop signal of other valve group commutation transformers to enable signal EN;

[0117] Specifically, when no airdrop signal is received from other valve groups, EN is set to 0, and the method described in steps S1 to S4 is not started, and the conventional control method based on the grid-side electrical signal is adopted; after receiving the airdrop signal from other valve groups, EN is set to 1, and the method from steps S1 to S4 is enabled.

[0118] S3: Switch the electrical feedback signal input to the control system;

[0119] like Figure 8 As shown, after the method described in step S1 to step S4 of the present invention is enabled, the electrical feedback signal input to the control system is switched from the grid side to the valve side.

[0120] In this specific application example, before 1.5s, the electrical feedback signal input to the low-pressure valve group control system is a grid-side electrical signal, namely:

[0121]

[0122] After 1.5s, the electrical feedback signal input to the low-pressure valve group control system is the valve side electrical signal:

[0123]

[0124] See next Figure 8 After the electrical input signal of the low-pressure valve group control system is switched, the dq-axis components of the voltage and current achieve a smooth transition after passing through the LPF link.

[0125] S4: Correct the current inner loop control parameters according to the electrical feedback signal in step S3.

[0126] The specific method for correcting the current inner loop control parameters is as follows: Fig. 9 The current inner loop structure shown in the figure shows the dq axis components of the valve side voltage modulation signal. with u d 、u q 、i d 、i q The expression between can be expressed as:

[0127]

[0128] In the formula, is the current reference value of the inner current loop dq axis, G PI is the PI controller transfer function, and L is the equivalent inductance parameter of the AC line.

[0129] When conventional control based on grid-side electrical signals is adopted, the AC line equivalent inductance parameters are; when the control method provided by the present invention is adopted, the AC line equivalent inductance parameters are. Fig.10As shown, the current inner loop inductance control parameter can be selected according to the enable signal EN, that is:

[0130]

[0131] Among them, L t is the commutation inductance parameter, L arm Indicates the inductance of the valve group bridge arm.

[0132] In this specific application example, before 1.5s, Fig. 9 as well as Fig.10 The inductance parameter of the inner current loop is set to After 1.5s, Fig. 9 as well as Fig.10 The inductance parameter of the inner loop of the medium current is corrected to The final electromagnetic transient simulation results are as follows: Fig.11 , Fig.12 shown.

[0133] See first Fig.11 Before the high-pressure valve group converter transformer was put into operation, the low-pressure valve group operated normally, and the three-phase current on the valve side of the low-pressure valve group converter transformer was symmetrical. The amplitude was about 0.94kA. At 1.5s, the high-pressure valve group converter transformer was put into operation without load. Since the low-pressure valve group adopted conventional control based on the grid-side electrical signal, it could not suppress the inrush current phenomenon, and the valve side current of the low-pressure valve group converter transformer was obviously distorted. The maximum instantaneous amplitude of the transient single-phase current was 1.35kA, and there was an obvious DC bias. This DC bias component will invade the DC side, causing the low-pressure valve group bridge arm to overcurrent, which will not only cause large power loss, but also threaten the safety of the converter valve power electronic devices, and even trigger the bridge arm overcurrent protection, causing the converter station to shut down.

[0134] See next Fig.12 Since the low-voltage valve group adopts the inrush current suppression control based on the valve-side electrical signal, at 1.5s, after the high-voltage valve group converter transformer is put into operation without load, the valve-side current of the low-voltage valve group converter transformer has no obvious harmonic components, and it can be approximately considered that the three-phase current is approximately symmetrical. Since there is no obvious DC bias component, the low-voltage valve group bridge arm will not have overcurrent, and the inrush current suppression effect is obvious.

[0135] From the above description, it can be seen that a method for suppressing the response surge current provided by a specific application example of the present invention is applied to any flexible direct current high and low pressure valve group in a high voltage direct current transmission system. After receiving the airdrop signal of the converter of other valve groups, this method switches the electrical feedback signal input to the control system from the grid side to the valve side, and quickly suppresses the response surge current on the valve side of the flexible direct current high and low pressure valve group by virtue of the advantages of high current control accuracy and fast dynamic response of the current inner loop. This method solves the problem of overcurrent in the bridge arm of the normal operation valve group caused by the response surge current in the prior art, thereby reducing losses and avoiding false operation of the bridge arm overcurrent protection, and retains the original control structure of the system, only increasing the input feedback signal switching strategy of the control system, thus saving costs and not affecting the original stability of the system.

[0136] Based on the same inventive concept, the embodiments of the present application also provide a device for suppressing a surge, which can be used to implement the method described in the above embodiments, such as the following embodiments. Since the principle of solving the problem by the device for suppressing a surge is similar to that of the method for suppressing a surge, the implementation of the device for suppressing a surge can refer to the implementation of the method for suppressing a surge, and the repeated parts will not be repeated. As used below, the terms "unit" or "module" can be a combination of software and / or hardware that implements a predetermined function. Although the system described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0137] The embodiment of the present invention provides a specific implementation of a device for suppressing a corresponding surge current that can realize a method for suppressing a corresponding surge current. The device is applied to any flexible high and low pressure valve group in a high voltage direct current transmission system. Fig.13 A device for suppressing a surge flow specifically includes the following contents:

[0138] The electrical signal acquisition module 10 is used to obtain the electrical signal of the valve side in response to the received inverter airdrop signal sent by other flexible direct current high and low pressure valve groups;

[0139] An electrical signal switching module 20, used to switch the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal on the valve side;

[0140] The control parameter correction module 30 is used to correct the current inner loop control parameters according to the electrical signal on the valve side to suppress the inrush current on the converter valve side of the local flexible direct current high and low pressure valve group.

[0141] In some embodiments of the present invention, the electrical signal is a dq axis component; see Fig.14 , the electrical signal acquisition module 10 comprises:

[0142] The signal acquisition unit 10a is used to acquire the grid-side voltage signal, grid-side current signal, valve-side voltage signal and valve-side current signal of the local transformer;

[0143] The dq axis component acquisition unit 10b is used to acquire the dq axis components of the valve side according to the grid side voltage signal, the grid side current signal, the valve side voltage signal and the valve side current signal.

[0144] In some embodiments of the present invention, see Fig.15 , the dq axis component acquisition unit 10b includes:

[0145] A voltage phase acquisition unit 10b1, used to phase-lock the grid-side voltage signal and the valve-side voltage signal respectively to acquire a grid-side voltage phase and a valve-side voltage phase;

[0146] The dq axis component acquisition subunit 10b2 is used to perform Park transformation on the grid side voltage signal, grid side current signal, valve side voltage signal and valve side current signal according to the grid side voltage phase and the valve side voltage phase to obtain the dq axis component of the valve side.

[0147] In some embodiments of the present invention, see Fig.16 , the electrical signal switching module 20 includes:

[0148] An electrical signal filtering unit 20a, used to input the electrical signal of the control system into a series low-pass filter to filter the electrical signal;

[0149] The electrical signal switching unit 20b is used to switch the filtered electrical signal of the control system to the electrical signal of the valve side.

[0150] In some embodiments of the present invention, the control parameter is an inductance control parameter; see Fig.17 , the control parameter correction module 30 includes:

[0151] A relationship establishing unit 30a, used to establish a relationship between the dq-axis components of the valve-side voltage modulation signal and the electrical signal of the valve side according to the structure of the current inner loop;

[0152] The control parameter correction unit 30b is used to correct the inductance control parameter of the current inner loop according to the relationship.

[0153] From the above description, it can be seen that an apparatus for suppressing response inrush current provided in an embodiment of the present invention is applied to any flexible direct current high and low pressure valve group in a high voltage direct current transmission system, and includes: an electrical signal acquisition module, used to obtain the electrical signal of the valve side in response to the received converter transformer air drop signal issued by other flexible direct current high and low pressure valve groups; an electrical signal switching module, used to switch the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal of the valve side; a control parameter correction module, used to correct the current inner loop control parameters according to the electrical signal on the valve side, so as to suppress the response inrush current on the converter transformer valve side of the local flexible direct current high and low pressure valve group.

[0154] First, the present invention suppresses the surge current on the valve side of the flexible high and low pressure valve group through the current inner loop, which effectively solves the problem of overcurrent in the bridge arm of the normal operation valve group caused by the surge current in the prior art, thereby reducing losses and avoiding malfunction of the bridge arm overcurrent protection. Secondly, the present invention retains the original control structure of the system and only adds the switching strategy of the electrical feedback signal input of the control system, thus saving costs and not affecting the original stability of the system.

[0155] The embodiments of the present application also provide a specific implementation of an electronic device capable of implementing all steps in the method for suppressing the inrush current in the above embodiments, see Fig.18 , electronic equipment specifically includes the following:

[0156] Processor (processor) 1201, memory (memory) 1202, communication interface (CommunicationsInterface) 1203 and bus 1204;

[0157] The processor 1201 , the memory 1202 , and the communication interface 1203 communicate with each other via the bus 1204 ; the communication interface 1203 is used to realize information transmission between relevant devices such as the server-side device, the power measurement device, and the user-side device.

[0158] The processor 1201 is used to call the computer program in the memory 1202. When the processor executes the computer program, all steps in the method for suppressing the inrush current in the above embodiment are implemented. The method is applied to any flexible high and low pressure valve group in the high voltage direct current transmission system. For example, when the processor executes the computer program, the following steps are implemented:

[0159] Step 100: Responding to the received inverter drop signal sent by other flexible direct current high and low pressure valve groups, obtaining the valve side electrical signal;

[0160] Step 200: Switching the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal on the valve side;

[0161] Step 300: Correct the current inner loop control parameters according to the electrical signal on the valve side to suppress the inrush current on the converter valve side of the local flexible direct current high and low pressure valve group.

[0162] The embodiments of the present application also provide a computer-readable storage medium capable of implementing all the steps of the method for suppressing the combined surge in the above embodiments. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, all the steps of the method for suppressing the combined surge in the above embodiments are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0163] Step 100: Responding to the received inverter drop signal sent by other flexible direct current high and low pressure valve groups, obtaining the valve side electrical signal;

[0164] Step 200: Switching the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal on the valve side;

[0165] Step 300: Correct the current inner loop control parameters according to the electrical signal on the valve side to suppress the inrush current on the converter valve side of the local flexible direct current high and low pressure valve group.

[0166] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0167] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0168] Although the present application provides method operation steps such as embodiments or flow charts, more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the order of many steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in the order of the method shown in the embodiments or the drawings or in parallel (for example, in a parallel processor or multi-threaded processing environment).

[0169] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes 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 a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0170] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0171] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0172] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for suppressing a surge flow, characterized in that: Applicable to any flexible high and low pressure valve group in the HVDC transmission system, including: In response to the received converter transformer airdrop signal sent by other flexible direct current high and low pressure valve groups, the electrical signal on the valve side is obtained; Switching an electrical signal input to a control system of the high voltage direct current transmission system to an electrical signal on the valve side; The current inner loop control parameters are corrected according to the electrical signal on the valve side to suppress the converter valve side and the inrush current of the local flexible direct current high and low pressure valve group.

2. The method for suppressing the response surge according to claim 1, characterized in that: The electrical signal is a dq axis component; the electrical signal on the valve side is obtained, including: Collect the grid-side voltage signal, grid-side current signal, valve-side voltage signal and valve-side current signal of the local transformer; The dq-axis components of the valve side are acquired according to the grid-side voltage signal, the grid-side current signal, the valve-side voltage signal, and the valve-side current signal.

3. The method for suppressing the response surge according to claim 2, characterized in that: Acquiring the dq-axis components of the valve side according to the grid side voltage signal, the grid side current signal, the valve side voltage signal, and the valve side current signal, including: Phase-locking the grid-side voltage signal and the valve-side voltage signal respectively to obtain a grid-side voltage phase and a valve-side voltage phase; The grid-side voltage signal, the grid-side current signal, the valve-side voltage signal and the valve-side current signal are subjected to Park transformation according to the grid-side voltage phase and the valve-side voltage phase to obtain the dq-axis components of the valve side.

4. The method for suppressing the response surge according to claim 1, characterized in that: The step of switching the electrical signal input to the control system of the high voltage direct current transmission system to the electrical signal on the valve side includes: Inputting the electrical signal of the control system into a series low-pass filter to filter the electrical signal; The filtered electrical signal of the control system is switched to the electrical signal of the valve side.

5. The method for suppressing the response surge according to any one of claims 1 to 4, characterized in that: The control parameter is an inductance control parameter; the control parameter of the inner current loop is corrected according to the electrical signal on the valve side, including: Establishing a relationship between the dq-axis components of the valve-side voltage modulation signal and the electrical signal on the valve side according to the structure of the current inner loop; The inductance control parameter of the inner current loop is corrected according to the relationship.

6. A device for suppressing a surge flow, characterized in that: Applicable to any flexible high and low pressure valve group in the HVDC transmission system, including: An electrical signal acquisition module, used for acquiring the electrical signal on the valve side in response to the received inverter airdrop signal sent by other flexible direct current high and low pressure valve groups; An electrical signal switching module, used for switching the electrical signal input to the control system of the high voltage direct current power transmission system to the electrical signal on the valve side; The control parameter correction module is used to correct the current inner loop control parameters according to the electrical signal on the valve side to suppress the inrush current on the converter valve side of the local flexible direct high and low pressure valve group.

7. The device for suppressing the induced surge according to claim 6, characterized in that: The electrical signal is a dq axis component; the electrical signal acquisition module comprises: A signal acquisition unit, used to acquire a grid-side voltage signal, a grid-side current signal, a valve-side voltage signal, and a valve-side current signal of a local transformer; The dq axis component acquisition unit is used to acquire the dq axis component of the valve side according to the grid side voltage signal, the grid side current signal, the valve side voltage signal and the valve side current signal.

8. The device for suppressing the induced surge according to claim 7, characterized in that: The dq axis component acquisition unit comprises: a voltage phase acquisition unit, used to phase-lock the grid-side voltage signal and the valve-side voltage signal respectively, so as to acquire a grid-side voltage phase and a valve-side voltage phase; The dq axis component acquisition subunit is used to perform Park transformation on the grid side voltage signal, grid side current signal, valve side voltage signal and valve side current signal according to the grid side voltage phase and the valve side voltage phase to obtain the dq axis component of the valve side.

9. The device for suppressing the induced surge according to claim 6, characterized in that: The electrical signal switching module comprises: an electrical signal filtering unit, used for inputting the electrical signal of the control system into a series low-pass filter to filter the electrical signal; The electrical signal switching unit is used to switch the filtered electrical signal of the control system to the electrical signal of the valve side.

10. The device for suppressing the induced surge according to any one of claims 6 to 9, characterized in that: The control parameter is an inductance control parameter; The control parameter correction module comprises: A relationship establishing unit, used to establish a relationship between the dq-axis components of the valve-side voltage modulation signal and the electrical signal on the valve side according to the structure of the current inner loop; A control parameter correction unit is used to correct the inductance control parameter of the current inner loop according to the relationship.

11. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method for suppressing the surge current described in any one of claims 1 to 5 are implemented.

12. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the method for suppressing the surge current described in any one of claims 1 to 5 are implemented.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for suppressing the inrush current described in any one of claims 1 to 5 are implemented.

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