Wind field networking type SVG overcurrent suppression method and device, electronic equipment and medium

Abstract

The invention discloses a wind field networking type SVG overcurrent suppression method and device, electronic equipment and a medium, and belongs to the technical field of wind field grid-connected converter control. The invention aims to construct an effective current limiting method so as to prevent the wind field networking type SVG overcurrent suppression method and device caused by fault (or wind turbine generator switching) overcurrent, electronic equipment and a medium. The method comprises the steps of obtaining a virtual reactance initial value according to a rated capacity and a grid-connected voltage level of a wind field networking type SVG; designing a voltage difference between a virtual internal potential and a grid-connected point of the wind field networking type SVG, and converting the voltage difference to obtain a virtual reactance coefficient; the jth output current instruction value of the wind field networking type SVG is obtained; and embedding the virtual reactance coefficient and the wind field networking type SVG output current instruction value into the adaptive virtual reactance, and then performing adaptive adjustment on the virtual reactance in the inner potential control loop. According to the method, the equipment hardware manufacturing cost is saved, and the virtual impedance can be reasonably adjusted according to the out-of-limit degree of the output current of the network-forming SVG, so that the dynamic control performance of the equipment is improved, and the method has engineering practical value.

Description

Technical Field

[0001] The invention belongs to the technical field of wind farm grid-connected converter control. Background Art

[0002] In modern power systems, the proportion of renewable energy generation represented by wind power generation is growing. However, in the process of large-scale grid connection of wind power generation, SVG is not only required to regulate the reactive voltage of the wind farm system, but also the problem of regional system active power imbalance caused by the switching of wind turbines (or the switching of nearby loads) needs to be solved urgently.

[0003] As a new technology, the transformation of the grid-type SVG in the wind farm into a grid-type control has become a research hotspot in the field of new energy grid connection. The grid-type SVG not only retains its original reactive power compensation function, but also can perform short-term active power regulation of the system due to the installation of supercapacitors. The access of the grid-type SVG provides additional inertial support and damping for the wind farm, which can solve the stability problem caused by insufficient inertia and damping of the wind farm under weak system conditions.

[0004] However, compared with traditional synchronous generators, grid-type SVGs are limited by their control strategies and power devices, and their overcurrent tolerance is relatively weak. Summary of the invention

[0005] The purpose of the present invention is to construct an effective current limiting method to prevent the wind farm grid-type SVG overcurrent suppression method and device, electronic equipment and medium caused by overcurrent due to fault (or wind turbine switching).

[0006] The steps of the present invention are: Combined with the application scenario, according to the rated capacity of the wind farm grid-type SVG and the grid-connected voltage level, the initial value of the virtual reactance is calculated; according to the virtual reactance equivalent circuit equation and the initial value of the virtual reactance, the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid-connected point are designed, and the virtual reactance coefficient m is obtained by converting the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid-connected point; According to the internal potential control principle of wind farm grid-type SVG, the internal potential control loop output of the virtual reactance is designed, so as to obtain the j-th output current command value of the wind farm grid-type SVG; The virtual reactance coefficient m and the j-th output current command value of the wind farm grid-type SVG are embedded in the adaptive virtual reactance, and then the virtual reactance in the inner potential control loop is adaptively adjusted.

[0007] In combination with the application scenario, the present invention calculates the initial value of virtual reactance X according to the rated capacity of the wind farm grid-type SVG and the grid-connected voltage level by formula (1): adv0 : Where Un is the rated phase voltage of the wind farm grid-type SVG outlet, S n is the rated capacity of the wind farm grid-type SVG, ω n Rated angular velocity of the grid, L adv0 is the initial value of virtual inductance, X adv0 is the initial value of virtual reactance.

[0008] The present invention designs the virtual internal potential and the voltage difference of the wind farm grid-forming SVG grid connection point according to the virtual reactance equivalent circuit equation and the virtual reactance initial value: The current limiting measures need to meet the requirement that I is less than the maximum allowable current I max The basic premise is that I max =3I n , Construct the voltage difference formula (2) across the virtual reactance: In the formula, ΔU v is the voltage difference between the virtual internal potential and the grid-connected point of the wind farm grid-type SVG, I kmax is the maximum output current of the wind farm grid-type SVG during a fault, X adv0 is the initial value of virtual reactance, I th is the current threshold, ω n is the rated angular velocity of the grid.

[0009] The present invention converts the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid connection point to obtain the virtual reactance coefficient m: Perform logarithmic operations on both sides of equation (2) to obtain the virtual reactance coefficient m:

[0010] The present invention designs the jth current reference value of the internal potential control loop of the virtual reactance according to the internal potential control principle of the wind farm grid-type SVG, thereby obtaining the jth output current command value I of the wind farm grid-type SVG. rj : The jth d-axis and q-axis current reference values ​​output by the inner potential control loop of the virtual reactance are i drefj and i qrefj : In the formula, the virtual potential E ref Establish dq rotation coordinate system for d axis, u gdj and u gqj are the d-axis and q-axis components of the voltage measured at the grid-connected point of the wind farm grid-type SVG during the iteration process, and X advj is the virtual reactance value during the iteration process, j = 0, 1, 2, 3...N represents the number of iterations during which the virtual reactance changes with the current during the fault period; The jth output current command value I of the wind farm grid type SVG rj for: In the formula, E refj Represents the virtual excitation electromotive force during the iteration process.

[0011] The present invention converts the wind farm grid type SVG output current command value I rj With the set current threshold I th For comparison, if I th <I rj , using the adaptive virtual reactance adjustment algorithm to calculate X advj , and then adjust the output reference current Idref and Iqref of the inner potential control loop; if I th ≥I rj , then X advj =X adv0 : Finally, the j-th adaptive virtual reactance value is obtained.

[0012] The wind farm meshing type SVG output current instruction device of the present invention is used to obtain the wind farm meshing type SVG output current instruction, utilize the SVG outlet voltage transformer and current transformer to detect and obtain the meshing type SVG output voltage and current, and call the virtual reactance initial value acquisition module and the virtual reactance coefficient calculation module through the internal potential control module to output the SVG output current instruction.

[0013] The wind farm meshing type SVG output current instruction device of the present invention is used for adaptively adjusting the SVG virtual reactance. The SVG output current instruction provided by the wind farm meshing type SVG output current instruction device is used to call an adaptive virtual reactance adjustment module, and the SVG output current obtained by current transformer measurement is combined to adaptively adjust the virtual reactance of the meshing type SVG in real time according to the current overcurrent degree. By modulating the drive circuit, the trigger pulse width is affected, and the current limiting control of the SVG power device is performed.

[0014] A control program is stored on a readable storage medium of the electronic controller of the present invention. When the control program is executed by the controller, the wind farm grid-type SVG overcurrent adaptive suppression method as described in any one of claims 1 to 6 is implemented.

[0015] The electronic device of the present invention comprises: at least one processor and a memory; The memory stores computer-executable instructions; The at least one processor executes the computer-executable instructions stored in the memory, so that the at least one processor performs the wind farm grid-type SVG overcurrent adaptive suppression method according to any one of claims 1 to 6.

[0016] Under the premise of not changing the original control structure of the mesh-type SVG, the present invention realizes overcurrent suppression of the output current of the wind farm mesh-type SVG under fault conditions by adaptively adjusting the virtual impedance, which not only saves the equipment hardware manufacturing cost, but also can reasonably adjust the virtual impedance according to the degree of over-limit of the output current of the mesh-type SVG, thereby improving the dynamic control performance of the equipment and having engineering practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A structural diagram of a four-terminal interconnection system of a wind farm area provided in an embodiment of the present invention; Figure 2 A block diagram of internal potential control and current inner loop control based on adaptive virtual reactance provided in an embodiment of the present invention; Figure 3 A schematic diagram of the structure of an adaptive virtual reactance adjustment algorithm provided in an embodiment of the present invention; Figure 4 It is a main implementation flow chart of the adaptive virtual reactance control strategy provided in an embodiment of the present invention; Figure 5 A diagram showing specific execution steps of the adaptive virtual reactance control provided in an embodiment of the present invention; Figure 6 This is the output current curve of the meshed SVG using the traditional fixed value virtual reactance; Figure 7 The output current curve of the meshed SVG using adaptive virtual reactance is shown in Figure 2. Figure 8 This is the trend diagram of adaptive virtual reactance change. DETAILED DESCRIPTION

[0018] To solve the problem of damage to equipment caused by overcurrent of grid-type SVG output current when a wind farm system failure (or wind turbine switching) occurs under existing technical conditions, and to avoid the negative impact of equipment disconnection on the stable operation of the wind farm and regional power grid.

[0019] The present invention provides a method for adaptively suppressing overcurrent of a networked SVG, comprising: Combined with the rated capacity and grid-connected voltage level of the grid-connected SVG in the application scenario, the initial value of the virtual reactance is calculated; an adaptive virtual reactance adjustment algorithm is designed and embedded in the internal potential control loop based on the adaptive virtual reactance. Figure 2 As shown; according to the degree of over-limit of the output current of the meshed SVG, the virtual reactance coefficient m is calculated, and then the virtual reactance in the inner potential control loop is adaptively adjusted to realize the real-time current limiting control of the output current of the meshed SVG.

[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention: At present, the overcurrent limiting method of mesh-type SVG mainly faces two problems: Problem 1: Although the existing grid-type SVG overcurrent limiting strategy adopts the current limiting method of fixed virtual impedance, the fixed virtual impedance design method usually only considers small disturbance conditions and is not applicable to large disturbance conditions.

[0021] Question 2: The overcurrent limiting strategies used in previous grid-type converters are often accompanied by defects such as complex improved control strategies, difficulty in extracting required key information, low assumed voltage levels, and inaccurate theoretical models. They cannot be directly transplanted to grid-type SVGs for overcurrent limiting.

[0022] In view of this, the present invention provides a wind farm grid-type SVG overcurrent adaptive suppression method, combined with Figure 4 The main implementation process of the present invention includes: Process S1: Combined with the application scenario, according to the rated capacity of the wind farm grid-type SVG and the grid-connected voltage level, the initial value of the virtual reactance is calculated. Figure 1 shown.

[0023] Process S2, designing the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid-type point according to the virtual reactance equivalent circuit equation, and obtaining the virtual reactance coefficient m according to the conversion of the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid-type point.

[0024] Process S3, designing the internal potential control loop output of the virtual reactance according to the internal potential control principle of the wind farm grid-type SVG, so as to obtain the j-th output current command value of the wind farm grid-type SVG.

[0025] In process S4, the virtual reactance coefficient m and the j-th output current command value of the wind farm grid type SVG are embedded in the adaptive virtual reactance, and then the virtual reactance in the inner potential control loop is adaptively adjusted. Figure 2 shown.

[0026] Combine the following Figure 5 , the specific execution steps of the technical solution of the present invention are introduced in detail: Step 1. Determine the rated capacity and grid-connected voltage level of the grid-connected SVG in the actual project, and calculate the initial value of the virtual reactance X according to formula (1): adv0 : Where U n is the rated phase voltage of SVG outlet, is the rated capacity of SVG, ω n Rated angular velocity of the grid, L v0is the initial value of virtual inductance, X adv0 is the initial value of virtual reactance.

[0027] Step 2. Design the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid-connected point according to the virtual reactance equivalent circuit equation, and obtain the virtual reactance coefficient m according to the conversion of the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid-connected point.

[0028] The specific implementation methods are as follows: The current limiting measures need to meet the requirement that I is less than the maximum allowable current I max The basic premise is that I max =3I n , Construct the voltage difference formula (2) across the virtual reactance: In the formula, ΔU v is the voltage difference between the virtual internal potential and the SVG grid connection point, I kmax is the maximum output current during SVG fault, X adv0 is the initial value of virtual reactance, I th is the current threshold, ω n is the rated angular velocity of the grid.

[0029] Using equation (2) to perform logarithmic operations on both sides, we can obtain the virtual reactance coefficient m, which is calculated as shown in equation (3):

[0030] Step 3. According to the internal potential control principle of the wind farm grid-type SVG, the internal potential control loop of the virtual reactance is designed to output the jth current reference value, thereby obtaining the jth output current command value I of the wind farm grid-type SVG rj .

[0031] The specific implementation methods are as follows: The jth d-axis and q-axis current reference values ​​output by the inner potential control loop of the virtual reactance are i drefj and i qrefj : In the formula, the virtual potential E ref Establish dq rotation coordinate system for d axis, u gdj and u gqj are the d-axis and q-axis components of the voltage measured at the SVG grid connection point during the iteration process, X advj is the virtual reactance value during the iteration process, j = 0, 1, 2, 3...N represents the number of iterations during which the virtual reactance changes with the current during the fault (or wind turbine switching) period.

[0032] The jth output current instruction value of SVG is: In the formula, E refj Represents the virtual excitation electromotive force during the iteration process.

[0033] The wind farm grid type SVG output current command value I rj With the set current threshold I th For comparison, if I th <I rj , using the adaptive virtual reactance adjustment algorithm to calculate X advj , and then output the reference current I to the inner potential control loop dref ,I qref Make adjustments; if I th ≥I rj , then X advj =X adv0 : Finally, the j-th adaptive virtual reactance value is obtained.

[0034] Table 1 Electrical and control parameters of mesh-type SVG

[0035] The effectiveness of the wind farm grid-type SVG overcurrent adaptive suppression method of the present invention is verified by simulation to prove its technical effect: 1. Refer to the wind farm area system structure to be implemented by the invention and draw a wind farm area four-terminal interconnection system structure diagram (such as Figure 1 shown), according to Figure 1 The interconnected system structure shown in the figure is used to build an electromagnetic simulation model of the wind farm regional interconnected system with meshed SVG and synchronous generators installed; 2. According to the specific simulation parameters provided in Table 1, set the key electrical parameters and control parameters of the meshed SVG, including: filter inductance, number of submodules, capacitance of submodule supercapacitors, initial value of moment of inertia, initial value of damping coefficient, virtual reactance, current inner loop proportional coefficient, and current inner loop integral coefficient; 3. Start the electromagnetic simulation model of the wind farm regional interconnection system. When the simulation time reaches 7s, set a short circuit fault at point k of the wind farm outlet line. When the simulation time reaches 7.01s, clear the short circuit fault. 4. Observe the output current of the meshed SVG during the simulation process (such as Figure 6 As shown in Figure 2, at the time of short-circuit fault (7s), the output current of the meshed SVG using the traditional fixed virtual reactance is significantly greater than the output current of the meshed SVG using the adaptive virtual reactance. Figure 7It is proved that the present invention can effectively suppress the overcurrent of the output current of the grid-type SVG when a fault occurs; at the same time, Figure 8 The changing trend of the adaptive virtual reactance of the network-type SVG during the fault occurrence (and clearing) period after the invention is adopted is shown. Figure 8 It is proved that the present invention can realize adaptive adjustment of the virtual reactance of the meshed SVG during the fault occurrence (and clearing) period. Compared with the meshed SVG using the traditional fixed-value virtual reactance, the present invention has more flexible control over the virtual reactance.

[0036] The wind farm meshing type SVG output current instruction device of the present invention is characterized by: being used to obtain the wind farm meshing type SVG output current instruction, using the SVG outlet voltage transformer and current transformer to detect and obtain the meshing type SVG output voltage and current, and calling the virtual reactance initial value acquisition module and the virtual reactance coefficient calculation module through the internal potential control module to output the SVG output current instruction.

[0037] The wind farm meshing type SVG output current instruction device of the present invention is used for adaptively adjusting the SVG virtual reactance. The SVG output current instruction provided by the wind farm meshing type SVG output current instruction device is used to call an adaptive virtual reactance adjustment module, and the SVG output current obtained by current transformer measurement is combined to adaptively adjust the virtual reactance of the meshing type SVG in real time according to the current overcurrent degree. By modulating the drive circuit, the trigger pulse width is affected, and the current limiting control of the SVG power device is performed.

[0038] A control program is stored on a readable storage medium of the electronic controller of the present invention. When the control program is executed by the controller, the wind farm grid-type SVG overcurrent adaptive suppression method as described in any one of claims 1 to 6 is implemented.

[0039] The electronic device of the present invention comprises: at least one processor and a memory; The memory stores computer-executable instructions; The at least one processor executes the computer-executable instructions stored in the memory, so that the at least one processor performs the wind farm grid-type SVG overcurrent adaptive suppression method according to any one of claims 1 to 6.

Claims

1. A wind farm grid-type SVG overcurrent suppression method, characterized by: The steps are: Combined with the application scenario, according to the rated capacity of the wind farm grid-type SVG and the grid-connected voltage level, the initial value of the virtual reactance is calculated; according to the virtual reactance equivalent circuit equation and the initial value of the virtual reactance, the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid-connected point are designed, and the virtual reactance coefficient m is obtained by converting the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid-connected point; According to the internal potential control principle of wind farm grid-type SVG, the internal potential control loop output of the virtual reactance is designed, so as to obtain the j-th output current command value of the wind farm grid-type SVG; The virtual reactance coefficient m and the j-th output current command value of the wind farm grid-type SVG are embedded in the adaptive virtual reactance, and then the virtual reactance in the inner potential control loop is adaptively adjusted.

2. The wind farm grid-type SVG overcurrent suppression method according to claim 1 is characterized in that: Combined with the application scenario, according to the rated capacity of the wind farm grid-type SVG and the grid-connected voltage level, the initial value of the virtual reactance X is calculated by formula (1): adv0 : Where U n is the rated phase voltage of the wind farm grid-type SVG outlet, S n is the rated capacity of the wind farm grid-type SVG, ω n Rated angular velocity of the grid, L adv0 is the initial value of virtual inductance, X adv0 is the initial value of virtual reactance.

3. The wind farm grid-type SVG overcurrent suppression method according to claim 1 is characterized in that: According to the virtual reactance equivalent circuit equation and the initial value of virtual reactance, the virtual internal potential and the voltage difference of the wind farm grid-type SVG grid connection point are designed: The current limiting measures need to meet the requirement that I is less than the maximum allowable current I max The basic premise is that I max =3I n , Construct the voltage difference formula (2) across the virtual reactance: In the formula, ΔU v is the voltage difference between the virtual internal potential and the grid-connected point of the wind farm grid-type SVG, I kmax is the maximum output current of the wind farm grid-type SVG during a fault, X adv0 is the initial value of virtual reactance, I th is the current threshold, ω n is the rated angular velocity of the grid.

4. The wind farm grid-type SVG overcurrent suppression method according to claim 3 is characterized in that: The virtual reactance coefficient m is obtained by converting the virtual internal potential and the voltage difference between the wind farm grid-type SVG grid connection point: Perform logarithmic operations on both sides of equation (2) to obtain the virtual reactance coefficient m:

5. The wind farm grid-type SVG overcurrent suppression method according to claim 1 is characterized in that: According to the internal potential control principle of wind farm grid-type SVG, the internal potential control loop of the virtual reactance is designed to output the jth current reference value, so as to obtain the jth output current command value I of the wind farm grid-type SVG rj : The jth d-axis and q-axis current reference values ​​output by the inner potential control loop of the virtual reactance are i drefj and i qrefj : In the formula, the virtual potential E ref Establish dq rotation coordinate system for d axis, u gdj and u gqj are the d-axis and q-axis components of the voltage measured at the grid-connected point of the wind farm grid-type SVG during the iteration process, and X advj is the virtual reactance value during the iteration process, j = 0, 1, 2, 3...N represents the number of iterations during which the virtual reactance changes with the current during the fault period; The jth output current command value I of the wind farm grid type SVG rj for: In the formula, E refj Represents the virtual excitation electromotive force during the iteration process.

6. The wind farm grid-type SVG overcurrent suppression method according to claim 1 is characterized in that: The wind farm grid type SVG output current command value I rj With the set current threshold I th For comparison, if I th <I rj , using the adaptive virtual reactance adjustment algorithm to calculate X advj , and then adjust the output reference current Idref and Iqref of the inner potential control loop; if I th ≥I rj , then X advj =X adv0 : Finally, the j-th adaptive virtual reactance value is obtained.

7. A wind farm grid-forming SVG output current instruction device, characterized in that: It is used to obtain the output current instruction of the wind farm grid-forming SVG. The SVG output voltage and current are detected by using the SVG export voltage transformer and current transformer. Through the internal potential control module, the virtual reactance initial value acquisition module and the virtual reactance coefficient calculation module are called to output the SVG output current instruction.

8. The wind farm grid-type SVG output current instruction device according to claim 7, characterized in that: The method is used for adaptively adjusting the virtual reactance of SVG. The method utilizes the SVG output current instruction provided by the wind farm meshing SVG output current instruction device to call an adaptive virtual reactance adjustment module. The SVG output current obtained by measuring the current transformer is combined to adaptively adjust the virtual reactance of the meshing SVG in real time according to the current overcurrent degree. The drive circuit is modulated to affect the trigger pulse width, thereby performing current limiting control on the SVG power device.

9. An electronic controller readable storage medium, characterized in that: A control program is stored thereon, and when the control program is executed by the controller, the wind farm grid-type SVG overcurrent adaptive suppression method as described in any one of claims 1 to 6 is implemented.

10. An electronic device, characterized in that: include: at least one processor and memory; The memory stores computer-executable instructions; The at least one processor executes the computer-executable instructions stored in the memory, so that the at least one processor performs the wind farm grid-type SVG overcurrent adaptive suppression method according to any one of claims 1 to 6.

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