A multi-target cooperative network construction type converter fault ride-through method and device, electronic equipment and storage medium

Abstract

The application discloses a multi-target cooperative network-constructed converter fault ride-through method and device, electronic equipment and a storage medium. The method comprises the following steps: obtaining a feasible region of a voltage reference and an active reference under different grid voltage drop depths according to constraint targets such as synchronous stability, reactive power support requirements of grid connection guidelines and converter current stress; adaptively adjusting the voltage reference and the active reference based on the feasible region; and effectively inhibiting the impact current in the fault occurrence and clearing moment through an adaptive virtual resistance. The scheme provided by the application can ensure that the network-constructed converter meets the multi-target constraints such as synchronous stability, reactive power support requirements of grid connection guidelines and current stress during the fault ride-through, realizes reliable fault ride-through, and improves the safe and stable operation ability of the system.

Description

Technical Field

[0001] This invention relates to the field of grid-connected control technology for new energy power generation, and in particular to a multi-objective coordinated grid-connected converter fault ride-through method, device, electronic equipment, and storage medium. Background Technology

[0002] With the continuous increase in the proportion of renewable energy sources, such as wind power and photovoltaics, connected to the grid, their characteristics of dispersion, weak support, low inertia, and low disturbance immunity pose severe challenges to the safe and stable operation of new power systems. Grid-connected converters, with their voltage source control and excellent active support capabilities and low-disturbance stability, have become one of the mainstream solutions for grid-connected converters. However, under grid faults, grid-connected converters are highly susceptible to synchronous instability and current over-limit problems, leading to equipment damage or even system collapse. Furthermore, my country's guidelines for renewable energy grid connection have made explicit requirements for the reactive power support of converters under fault conditions. Therefore, fault ride-through methods for grid-connected converters that meet the constraints of synchronous stability, current limitation, and reactive power support have become a difficult problem of common concern to both academia and industry.

[0003] Because grid-connected converters are voltage source control devices, they cannot directly control active and reactive currents by changing current commands. Under fault conditions, grid-connected converters struggle to effectively limit overcurrent and respond to reactive current requirements of grid connection guidelines. Furthermore, complex coupling constraints exist among the multiple objectives of fault ride-through: transient synchronization constraints require the system to generate more active current, grid connection guidelines require the system to generate more reactive current, while current stress constraints require the system current to not exceed limits. Moreover, existing technologies often focus on one or two objectives, making it difficult to simultaneously address multiple constraints. In summary, achieving fault ride-through that satisfies multiple constraints while maintaining the voltage source characteristics of the converter is a critical technical challenge that urgently needs to be addressed and is crucial for the safe and stable operation of new power systems. Summary of the Invention

[0004] To address the technical problem that grid-connected converters cannot directly control the current and are difficult to achieve reliable fault ride-through under grid fault conditions, this invention provides a multi-objective coordinated grid-connected converter fault ride-through method, apparatus, electronic equipment, and storage medium.

[0005] The technical solution of this invention is implemented as follows:

[0006] This invention provides a multi-objective cooperative fault ride-through method for grid-type converters, the method comprising:

[0007] Step 101: Collect the grid connection point voltage of the grid-connected converter; determine the system status based on the grid connection point voltage;

[0008] If the system is in a fault state, then step 102 is executed: adjusting the voltage reference value and the active power reference value; wherein, adjusting the voltage reference value and the active power reference value includes: obtaining the constraint equation of the voltage reference value according to the reactive current requirement of the grid connection guideline, the converter current stress constraint, and the voltage deviation constraint; obtaining the feasible region of the voltage reference value according to the constraint equation of the voltage reference value, and adjusting the voltage reference value based on the feasible region of the voltage reference value; obtaining the constraint equation of the active power reference value according to the synchronous stability constraint and the converter current stress constraint; obtaining the feasible region of the active power reference value according to the constraint equation of the active power reference value, and adjusting the active power reference value based on the feasible region of the active power reference value;

[0009] Step 103: Collect the output current of the grid-type converter and determine whether the system current exceeds the limit based on the output current;

[0010] If the system current exceeds the limit, then step 104 is executed: using the output current and the preset current safety threshold, the resistance value of the adaptive virtual resistor is obtained; based on the resistance value of the adaptive virtual resistor and the output current, the virtual voltage drop is obtained, and the virtual voltage drop is fed back to the reactive power-voltage control loop.

[0011] In one embodiment, determining the system state based on the grid connection point voltage includes:

[0012] Based on the grid connection point voltage, the system status is determined using the following formula:

[0013]

[0014] Here, Flag represents the system status: Flag = 1 indicates the system is in a fault state; Flag = 0 indicates the system is in a normal state; U g This is the voltage at the grid connection point.

[0015] In one embodiment, the voltage reference range that satisfies the reactive current requirements of the grid connection guidelines is:

[0016]

[0017] Among them, V n U is the voltage reference value. g K is the voltage at the grid connection point. q I is the reactive power loop droop factor. n I is the rated current of the converter. th X is the safe threshold for converter current. g Q is the line impedance. ref This is a reference for reactive power.

[0018] In one embodiment, the voltage reference value range that satisfies the converter current stress constraint requirement is:

[0019]

[0020] Among them, V n U is the voltage reference value. g K is the voltage at the grid connection point. q I is the reactive power loop droop factor. th X is the safe threshold for converter current. g Q is the line impedance. ref This is a reference for reactive power.

[0021] In one embodiment, the voltage reference value range that satisfies the voltage deviation constraint requirement is:

[0022]

[0023] Among them, V n K is the voltage reference value. q V is the reactive power loop droop factor. n0 U is the rated voltage of the converter. g I is the grid connection point voltage. th X is the safe threshold for converter current. g Q is the line impedance. ref This is a reference for reactive power.

[0024] In one embodiment, the active power reference range that satisfies the synchronization stability constraint and the converter current stress constraint is:

[0025] P ref =min{P e,max ,P n}

[0026] Among them, P ref P is the active power reference value. n P is the rated capacity of the converter. e,max The maximum active power that a grid-type converter can deliver to meet the requirements of synchronous stability and current stress constraint is expressed as:

[0027]

[0028] Among them, X g U is the line impedance. g I is the grid connection point voltage. th K is the safe threshold for converter current. q V is the reactive power loop droop factor. n Q is the voltage reference value. ref This is a reference for reactive power.

[0029] In one embodiment, the expression for the adaptive virtual resistance is:

[0030]

[0031] Among them, R v For adaptive virtual resistance, k r The proportional gain is the virtual resistance, and I is the output current. th This is the safe threshold for converter current.

[0032] This invention also provides a multi-objective collaborative grid-connected converter fault ride-through device, comprising: a first acquisition module for acquiring the grid-connected converter grid-connected point voltage; determining the system state based on the grid-connected point voltage; and a first regulation module for regulating the voltage reference value and active power reference value if the system is in a fault state. The regulation of the voltage reference value and active power reference value includes: obtaining a constraint equation for the voltage reference value based on the reactive current requirements of the grid connection guidelines, converter current stress constraints, and voltage deviation constraints; obtaining a feasible region for the voltage reference value based on the constraint equation; and regulating the voltage reference value based on the feasible region. The system uses a second acquisition module to collect the output current of the grid-connected converter and determine whether the system current exceeds the limit based on the output current. The second control module, if the system current exceeds the limit, uses the output current and a preset current safety threshold to obtain the resistance value of an adaptive virtual resistor. Based on the resistance value of the adaptive virtual resistor and the output current, a virtual voltage drop is obtained and fed back to the reactive power-voltage control loop.

[0033] In one embodiment, determining the system state based on the grid connection point voltage includes:

[0034] Based on the grid connection point voltage, the system status is determined using the following formula:

[0035]

[0036] Here, Flag represents the system status: Flag = 1 indicates the system is in a fault state; Flag = 0 indicates the system is in a normal state; U g This is the voltage at the grid connection point.

[0037] In one embodiment, the voltage reference range that satisfies the reactive current requirements of the grid connection guidelines is:

[0038]

[0039] Among them, V n U is the voltage reference value. g K is the voltage at the grid connection point. q I is the reactive power loop droop factor. n I is the rated current of the converter. th X is the safe threshold for converter current. g Q is the line impedance. ref This is a reference for reactive power.

[0040] In one embodiment, the voltage reference value range that satisfies the converter current stress constraint requirement is:

[0041]

[0042] Among them, V n U is the voltage reference value. g K is the voltage at the grid connection point. q I is the reactive power loop droop factor. th X is the safe threshold for converter current. g Q is the line impedance. ref This is a reference for reactive power.

[0043] In one embodiment, the voltage reference value range that satisfies the voltage deviation constraint requirement is:

[0044]

[0045] Among them, V n K is the voltage reference value. q V is the reactive power loop droop factor. n0 U is the rated voltage of the converter. g I is the grid connection point voltage. th X is the safe threshold for converter current. g Q is the line impedance. ref This is a reference for reactive power.

[0046] In one embodiment, the active power reference range that satisfies the synchronization stability constraint and the converter current stress constraint is:

[0047] P ref =min{P e,max ,P n}

[0048] Among them, P ref P is the active power reference value. n P is the rated capacity of the converter. e,max The maximum active power that a grid-type converter can deliver to meet the requirements of synchronous stability and current stress constraint is expressed as:

[0049]

[0050] Among them, X g U is the line impedance. g I is the grid connection point voltage. th K is the safe threshold for converter current. q V is the reactive power loop droop factor. n Q is the voltage reference value. ref This is a reference for reactive power.

[0051] In one embodiment, the expression for the adaptive virtual resistance is:

[0052]

[0053] Among them, R v For adaptive virtual resistance, k r The proportional gain is the virtual resistance, and I is the output current. th This is the safe threshold for converter current.

[0054] This invention also provides an electronic device, including: a processor and a memory for storing a computer program capable of running on the processor; wherein, when the processor runs the computer program, it performs the steps of the method described above.

[0055] This invention also provides a storage medium storing a computer program, which, when executed by a processor, implements the steps of the method described above.

[0056] Compared with the prior art, the beneficial effects of this embodiment are:

[0057] This invention, based on the synchronous stability constraints, current stress constraints, and reactive power support constraints of grid-connected converters, derives constraint equations for voltage and active power reference values ​​that satisfy multiple objectives. It further obtains the feasible region for these reference values ​​and adjusts them based on this region to ensure that synchronous stability, fault current limiting, and reactive power support are met during fault steady-state conditions. An adaptive virtual resistor is designed based on the output current and current safety threshold, enabling active switching and adaptive resistance adjustment of the virtual resistor, effectively suppressing the inrush current during fault occurrence and clearance. This invention ensures that the entire fault process meets the constraints of synchronous stability, current limiting, and reactive power support, achieving reliable fault ride-through for grid-connected converters and effectively improving their safe and stable operation. Attached Figure Description

[0058] Figure 1This is a control structure diagram of a multi-objective cooperative grid-type converter fault ride-through method according to an embodiment of the present invention;

[0059] Figure 2 This is a voltage and current phasor diagram of a grid-type converter under power grid fault conditions according to an embodiment of the present invention;

[0060] Figure 3 The voltage reference V under multi-objective constraints in the embodiments of the present invention n The feasible region graph;

[0061] Figure 4 The active power reference P under multi-objective constraints in this embodiment of the invention ref and voltage reference V n A three-dimensional feasible region graph;

[0062] Figure 5 This is a simulation comparison diagram of a multi-objective cooperative adaptive fault-crossing method and a traditional method under minor faults, according to an embodiment of the present invention; wherein, Figure 5 (a) shows the simulation results under the traditional control method; Figure 5 (b) shows the simulation results of the multi-objective cooperative adaptive fault-crossing method in this embodiment;

[0063] Figure 6 This is a simulation comparison diagram of a multi-objective cooperative adaptive fault-crossing method and a traditional method under severe fault conditions, according to an embodiment of the present invention; wherein, Figure 6 (a) shows the simulation results under the traditional control method; Figure 6 (b) shows the simulation results of the multi-objective cooperative adaptive fault traversal method in this embodiment. Detailed Implementation

[0064] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0065] Figure 1 This is a control structure diagram of a multi-objective cooperative grid-type converter fault ride-through method according to an embodiment of the present invention. In the main circuit section, the converter, filter circuit, and transformer are connected in sequence, with the transformer connected to the power grid. g V and V represent the grid voltage and the terminal voltage of the grid-connected converter, respectively; I is the grid-connected current; L f and C f These are the filter inductor and the filter capacitor, respectively; X g The equivalent grid impedance can be approximated as purely inductive. The grid configuration mainly includes active power control (APC), reactive power control (RPC), and a voltage-current inner loop. The mathematical expression for APC can be represented by equation (1):

[0066]

[0067] Where J and D are the virtual inertia and damping, respectively; P ref and P e These are the active power reference value and the output active power, respectively; δ and ω △ These are the phase difference and angular frequency difference between the terminal voltage of the grid-connected converter and the grid voltage, respectively, and they are related.

[0068]

[0069] The mathematical expression for RPC can be represented by equation (2):

[0070]

[0071] Among them, K q Q is the reactive power loop droop factor. ref and Q e These are the reactive power reference value and the output reactive power, respectively; V ref V represents the terminal voltage amplitude generated by the RPC. n This is the voltage reference value. Since the voltage and current inner loop bandwidth of a grid-type converter is much larger than the power outer loop bandwidth, the equivalent gain of the inner loop can be considered to be 1, i.e., V = V0. ref Based on equation (2), the expression for V can be further obtained as shown in equation (3):

[0072]

[0073] According to the national standards GB / T 19963.1-2021 "Technical Specifications for Wind Farm Access to Power Systems Part 1: Onshore Wind Power" and GB / T 19964-2024 "Technical Specifications for Photovoltaic Power Station Access to Power Systems", when the grid connection point voltage drops below 0.9 pu, the system is considered to be in a fault state, requiring the system to generate additional reactive current to support the grid connection point voltage; otherwise, the system is considered to be in a normal state. The specific rules for the system status flag bit (Flag) are shown in equation (4):

[0074]

[0075] Here, Flag represents the system status: Flag = 1 indicates the system is in a fault state; Flag = 0 indicates the system is in a normal state; U g This is the voltage at the grid connection point.

[0076] The specific requirements for reactive current in the grid connection guidelines are shown in equation (5):

[0077]

[0078] Among them, I q I is the reactive current output by the converter. nThis is the rated current of the converter.

[0079] Grid-type converters use voltage source control, meaning their output current is uncontrollable. Although grid-type converters have a current loop, their current reference value is automatically generated by the voltage loop, lacking control freedom. Forcibly changing the current reference value will switch the control mode from grid-type to grid-following mode, introducing a series of instability risks. Therefore, it is necessary to fully explore the control potential of grid-type converters to achieve current control during fault ride-through without altering the grid-type control mechanism.

[0080] Figure 2 This is a voltage and current phasor diagram of a grid-type converter under grid fault conditions according to an embodiment of the present invention. Wherein, I th This is the current safety threshold for the converter. During a fault, constrained by the current stress of the converter, the current should be limited within the safety threshold to avoid damage to the converter's semiconductor devices. Based on engineering experience, this paper takes I. th =1.5 pu. According to Figure 2 Therefore, the expression for the current I is shown in equation (6):

[0081]

[0082] According to equation (6), the expression for the work angle can be obtained as shown in equation (7):

[0083]

[0084] according to Figure 1 From equation (7), we can obtain the expression for the reactive current of the grid-type converter as shown in equation (8):

[0085]

[0086] As shown in equation (8), the reactive current of a grid-connected converter is controlled by the terminal voltage V. Substituting equation (8) into equation (5), the range of terminal voltages that meet the reactive power support requirements of the grid connection guideline is shown in equation (9):

[0087]

[0088] Substituting equation (9) into equation (3), we can obtain the voltage reference V that satisfies the reactive power support requirements of grid-connected conductors. n The range is shown in equation (10):

[0089]

[0090] Therefore, by converting the reactive current requirement of the grid connection guidelines into an equivalent constraint on the voltage reference in the RPC through (10), reactive current response can be achieved without changing the grid-type control characteristics. When equation (10) holds true, the reactive current support requirement of the grid connection guidelines can be satisfied, and V takes the lower limit value V. min ,like Figure 2 Point A is shown in the diagram.

[0091] During a fault, the terminal voltage V of a grid-type converter increases with the increase of its output capacitive reactive power. When the short-circuit capacity is entirely used for reactive power support, i.e., I = -I... th When V reaches its maximum value V max ,like Figure 2 Point B is shown in the equation. Therefore, the range of V that satisfies the current stress constraint is shown in equation (11):

[0092] V≤U g +I th X g (11)

[0093] In addition, the national standard GB / T 12325-2008 "Power Quality - Voltage Deviation" requires that the voltage deviation shall not exceed ±7%, as shown in equation (12):

[0094] V≤1.07V n0 (12)

[0095] Among them, V n0 This is the rated voltage of the converter.

[0096] Substituting (11) and (12) into equation (3) respectively, we can obtain V that satisfies the current stress constraint and voltage deviation requirements. n The ranges are shown in equations (13) and (14), respectively:

[0097]

[0098] Figure 3 The voltage reference V under multi-objective constraints in this embodiment of the invention n The feasible region graph can be obtained through equations (10), (13) and (14).

[0099] To meet synchronous stability constraints, the imbalance between active power input and output of grid-connected converters during faults should be avoided. This can be achieved by controlling the active power reference. Furthermore, during grid faults, active power should be generated as much as possible within the allowable capacity of the generating units, while ensuring reactive power support. According to equation (6), the current of a grid-connected converter is affected by both the terminal voltage V and the power angle δ. The voltage V can be controlled by the voltage reference V. n Control. According to APC, the active power reference P can be controlled.ref Control δ. Therefore, according to equations (2), (3) and (7), the maximum active power P that the grid-type converter can generate under current limitation and reactive power support constraint can be obtained. e,max As shown in equation (15):

[0100]

[0101] During the fault, the active power will be referenced to P. ref Set to the maximum allowed value P e,max This can simultaneously satisfy both current stress and synchronous stability constraints. Therefore, P ref The adjustment should satisfy equation (16):

[0102] P ref =min{P e,max , P n} (16)

[0103] Among them, P n This refers to the rated capacity of the converter.

[0104] Figure 4 The active power reference P under multi-objective constraints in this embodiment of the invention ref and voltage reference V n The three-dimensional feasible region diagram is obtained through equations (10), (13), (14) and (16). Based on this feasible region, adaptive multi-objective cooperative control during faults can be realized.

[0105] Steady-state overcurrent during a fault can be controlled by coordinating V n and P ref While achieving effective limiting, it generates a large fault inrush current during fault occurrence and clearance. The current expression of the grid-type converter during a fault is shown in equation (17):

[0106]

[0107] It can be seen that i(t) consists of two parts, one of which is the steady-state periodic component i p This can be effectively limited through the control methods mentioned above. Another is the transient DC component i. dc , is the main component of the impulse current. It can be observed that i dc The amplitude is positively correlated with the line impedance and negatively correlated with the voltage drop depth. Furthermore, it decays exponentially over time, with a decay coefficient of R0. g / L g However, due to R g <<L g The inrush current decays extremely slowly. Therefore, a virtual resistor method is proposed to suppress the inrush current. After introducing the virtual resistor, the transient DC current idc The expression is shown in equation (18):

[0108]

[0109] Among them, R v The virtual resistor is introduced to reduce the amplitude of the transient DC current while increasing the decay rate, effectively suppressing the fault inrush current. Although the virtual resistor does not actually consume active power, it exacerbates the power coupling effect of the grid-type converter and deteriorates the transient stability during the fault duration. Therefore, the virtual resistor is adaptively switched and its parameters are adjusted by the difference between the fault current and the threshold current, as shown in equation (19):

[0110]

[0111] In the formula, k r This is the proportional gain of the virtual resistor. The control structure for the virtual resistor is as follows: Figure 1 As shown, this indicates that only when the fault current I exceeds the threshold I... th The virtual resistor is only enabled under normal operating conditions, meaning it will not be activated until the overcurrent increases. Furthermore, the value of the virtual resistor increases with increasing overcurrent, achieving adaptive parameter adjustment.

[0112] In summary, the multi-objective cooperative fault ride-through method for grid-type converters proposed in this embodiment can be implemented through the following steps:

[0113] Step 101: Collect the grid connection point voltage U of the grid-connected converter g ; using U g Determine the system status and obtain the system status flag bit; if the system is in a fault state, proceed to step 102.

[0114] Step 102: Adjust the voltage reference value and active power reference value, including the following steps:

[0115] Step 01: Based on the reactive current requirements of the grid connection guidelines, the current stress constraints of the converter, and the power quality standards, obtain the voltage reference value V. n The constraint equations are shown in equations (10), (13) and (14); according to V n The constraint equations are obtained to obtain V. n Feasible region, and for V n To regulate;

[0116] Step 02: Based on the synchronous stability constraint and the converter current stress constraint, obtain the active power reference value P. ref The constraint equations are shown in equation (16); according to P ref The constraint equations are obtained to obtain P.ref Feasible region, and for P ref To regulate;

[0117] Step 103: Collect the output current I of the grid-type converter. Based on the output current I, determine whether the system current exceeds the limit. If the system current exceeds the limit, proceed to step 104:

[0118] Step 104: Utilize I and the preset current safety threshold I th The resistance value R of the adaptive virtual resistor is obtained. v As shown in equation (19); then multiplied by the current I, we obtain the virtual voltage drop V. Rv Feedback is sent to the reactive power-voltage control loop.

[0119] Figure 5 The figure shows a comparison of simulation results between the proposed multi-objective constrained adaptive fault ride-through method and traditional control when the grid voltage drops to 0.6 pu. Figure 5 (a) shows the simulation results under conventional control; Figure 5 (b) Simulation results of the multi-objective cooperative adaptive fault ride-through method proposed in this embodiment. The parameters of the grid-type converter are shown in Table 1. To demonstrate the effectiveness of the multi-objective cooperative fault ride-through control method proposed in this embodiment, a voltage dip fault occurs in the grid at 2.5s in the simulation, and the fault is cleared after 2s. Figure 5 (a) It can be seen that when the grid voltage drops to 0.6 pu, although the grid-connected converter under traditional control does not experience synchronous instability and the reactive current meets the grid connection guidelines, it suffers from severe overcurrent problems. The fault steady-state current reaches 1.88 pu, and the fault inrush current during fault occurrence and clearing is as high as 2.34 pu, severely exceeding the converter's current safety threshold and potentially damaging its semiconductor devices. In contrast, the simulation using the multi-objective cooperative control proposed in this embodiment... Figure 5 As shown in (b), the grid-connected converter can maintain synchronous stability during the fault period, and the output reactive current meets the grid connection guidelines. Furthermore, it meets the current stress constraint throughout the fault cycle, and the current is always controlled within the safe threshold. Figure 5 The implementation case of the medium-grid converter can fully verify the effectiveness of the multi-objective constraint adaptive fault ride-through method proposed in this embodiment in the case of minor faults. It can meet the objectives of synchronous stability, current stress constraint, grid-connected reactive power support requirements during the fault period.

[0120] Figure 6 The figure shows a comparison of simulation results between the proposed multi-objective constrained adaptive fault ride-through method and traditional control when the grid voltage drops to 0.2 pu. Figure 6 (a) shows the simulation results under conventional control; Figure 6(b) shows the simulation results of the multi-objective cooperative adaptive fault-crossing method proposed in this embodiment. Figure 6 (a) It can be seen that when the grid voltage drops to 0.2 pu, the grid-connected converter under traditional control experiences synchronous instability, with voltage, current, and power all oscillating. The fault current exceeds the threshold and the reactive current cannot be stably output, failing to meet the grid connection guidelines. However, the simulation using the multi-objective cooperative control proposed in this embodiment shows... Figure 6 As shown in (b), the grid-connected converter can maintain synchronous stability during the fault period and can stably output 1.4pu of reactive current, which meets the grid connection guidelines and satisfies the current stress constraint throughout the fault cycle, with the current always controlled within the safe threshold of 1.5pu. Figure 6 The implementation case of the medium-grid converter can fully verify the effectiveness of the multi-objective constraint adaptive fault ride-through method proposed in this embodiment under severe faults. It can meet the objectives of synchronous stability, current stress constraint, grid-connected reactive power support requirements during the fault period.

[0121] In summary, the multi-objective collaborative fault ride-through method for grid-connected converters described in this embodiment has the following significant advantages: 1) The control structure is simple and easy to implement in engineering. 2) During grid faults, it meets the objectives of synchronous stability, reactive power support as required by grid connection guidelines, and current stress constraints, achieving reliable fault ride-through for grid-connected converters. 3) This embodiment is not only applicable to improving grid-connected converter equipment but can also be applied to other grid-connected equipment, demonstrating strong versatility.

[0122] Table 1: Key Parameters of Network Converters

[0123] Rated capacity (kW) 10 Line inductance (pu) 0.26 Rated voltage (V) 380 Virtual inertia (pu) 1.5 Rated frequency (Hz) 50 Damping coefficient (pu) 30 Filter inductor (pu) 0.07 reactive power loop droop factor (pu) 0.1 Filter capacitor (pu) 0.23 Virtual resistance gain (pu) 3.0

[0124] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0125] The above are merely embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A multi-objective cooperative fault ride-through method for grid-type converters, characterized in that, The method includes: Step 101: Collect the grid connection point voltage of the grid-connected converter; determine the system status based on the grid connection point voltage; If the system is in a fault state, then proceed to step 102: Based on the reactive current requirements of the grid connection guidelines, the converter current stress constraint, and the voltage deviation constraint, obtain the constraint equation for the voltage reference value; based on the constraint equation for the voltage reference value, obtain the feasible region of the voltage reference value, and adjust the voltage reference value based on the feasible region; based on the synchronous stability constraint and the converter current stress constraint, obtain the constraint equation for the active power reference value; based on the constraint equation for the active power reference value, obtain the feasible region of the active power reference value, and adjust the active power reference value based on the feasible region; Step 103: Collect the output current of the grid-type converter and determine whether the system current exceeds the limit based on the output current; If the system current exceeds the limit, then step 104 is executed: using the output current and the preset current safety threshold, the resistance value of the adaptive virtual resistor is obtained; based on the resistance value of the adaptive virtual resistor and the output current, the virtual voltage drop is obtained, and the virtual voltage drop is fed back to the reactive power-voltage control loop; The voltage reference range that satisfies the reactive current requirements of the grid connection guidelines is: in, This is the voltage reference value. The voltage at the grid connection point. This is the reactive power loop droop factor. This is the rated current of the converter. The current safety threshold for the converter. For line impedance, This is a reference for reactive power.

2. The multi-objective cooperative grid-type converter fault ride-through method according to claim 1, characterized in that, Based on the grid connection point voltage, determine the system status, including: Based on the grid connection point voltage, the system status is determined using the following formula: in, Indicates the system status. A value of 1 indicates that the system is in a fault state; A value of 0 indicates that the system is in a normal state; This is the voltage at the grid connection point.

3. The multi-objective cooperative grid-type converter fault ride-through method according to claim 1, characterized in that, The voltage reference range that meets the converter current stress constraint requirements is: in, This is the voltage reference value. The voltage at the grid connection point. This is the reactive power loop droop factor. The current safety threshold for the converter. For line impedance, This is a reference for reactive power.

4. The multi-objective cooperative grid-type converter fault ride-through method according to claim 1, characterized in that, The voltage reference range that meets the voltage deviation constraint requirements is: in, This is the voltage reference value. This is the reactive power loop droop factor. The rated voltage of the converter. The voltage at the grid connection point. The current safety threshold for the converter. For line impedance, This is a reference for reactive power.

5. The multi-objective cooperative grid-type converter fault ride-through method according to claim 1, characterized in that, The active power reference range that satisfies both synchronous stability constraints and converter current stress constraints is as follows: in, This is a reference value for active power. For the rated capacity of the converter, The maximum active power that a grid-type converter can deliver to meet the requirements of synchronous stability and current stress constraint is expressed as: in, For line impedance, The voltage at the grid connection point. The current safety threshold for the converter. This is the reactive power loop droop factor. This is the voltage reference value. This is a reference for reactive power.

6. The multi-objective cooperative grid-type converter fault ride-through method according to claim 1, characterized in that, The expression for the adaptive virtual resistor is: in, For adaptive virtual resistance, The proportional gain of the virtual resistance. For output current, This is the safe threshold for converter current.

7. A multi-objective cooperative grid-type converter fault ride-through device, characterized in that, The multi-objective cooperative grid-type converter fault ride-through device includes: The first acquisition module acquires the grid-connected voltage of the grid-connected converter; and determines the system status based on the grid-connected voltage. The first control module is used to, if the system is in a fault state, derive the constraint equation for the voltage reference value based on the reactive current requirements of the grid connection guidelines, the converter current stress constraint, and the voltage deviation constraint; derive the feasible region of the voltage reference value based on the constraint equation of the voltage reference value, and control the voltage reference value based on the feasible region; derive the constraint equation for the active power reference value based on the synchronous stability constraint and the converter current stress constraint; derive the feasible region of the active power reference value based on the constraint equation of the active power reference value, and control the active power reference value based on the feasible region; the voltage reference value range that satisfies the reactive current requirements of the grid connection guidelines is: in, This is the voltage reference value. The voltage at the grid connection point. This is the reactive power loop droop factor. This is the rated current of the converter. The current safety threshold for the converter. For line impedance, For reactive power reference; The second acquisition module is used to acquire the output current of the grid-type converter and determine whether the system current exceeds the limit based on the output current. The second control module is used to obtain the resistance value of the adaptive virtual resistor by using the output current and a preset current safety threshold if the system current exceeds the limit; to obtain the virtual voltage drop based on the resistance value of the adaptive virtual resistor and the output current, and to feed the virtual voltage drop back to the reactive power-voltage control loop.

8. An electronic device, characterized in that, include: A processor and a memory for storing a computer program capable of running on the processor; wherein, when the processor is used to run the computer program, it performs the steps of the method according to any one of claims 1 to 6.

9. A storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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