Dynamic reconfiguration control method, device and equipment for follow-up network construction equipment considering transient power angle stability and storage medium of follow-up network construction equipment

Abstract

The invention discloses a dynamic reconfiguration control method, device and equipment for follow-up network construction equipment considering transient power angle stability and a storage medium thereof, and relates to the technical field of new energy power generation systems. According to the method, simulation verification is carried out on the grid-connected system adopting the regulation and control strategy and the grid-connected system not adopting the regulation and control strategy by building the grid-connected system of the converter of the constructed network and setting the voltage drop fault of the power grid, so that the effectiveness of the provided regulation and control strategy is verified.

Description

Technical Field

[0001] This invention discloses a dynamic reconfiguration control method, device, equipment, and storage medium for grid-connected equipment that considers transient power angle stability, relating to the field of new energy power generation system technology. Background Technology

[0002] Traditional wind and solar power units are connected to the grid using grid-connected converters. However, due to the lack of voltage and frequency support capabilities for these units, large-scale grid connection leads to a decrease in the grid's short-circuit ratio, making the system highly susceptible to dynamic instability after disturbances. To support grid-friendly wind and solar power integration, the concept of grid-connected converters emerged. Grid-connected control, by simulating the dynamic characteristics of synchronous generators, provides voltage and inertia support to the grid. Therefore, it is widely used in renewable energy grid-connected systems to improve grid stability.

[0003] However, excessive output from grid-connected converters can reduce system transient stability and lead to power angle instability, while excessive capacity of grid-connected converters can result in insufficient voltage support, which also affects system stability. Therefore, how to regulate the output of grid-connected equipment in renewable energy grid-connected systems requires further in-depth research. Summary of the Invention

[0004] This invention addresses the problems of existing technologies by providing a dynamic reconfiguration control method, apparatus, device, and storage medium for network equipment that considers transient power angle stability. The technical solution adopted is as follows: Firstly, a dynamic reconfiguration control method for network equipment considering transient power angle stability includes: S1, Based on the mathematical model of the grid-connected system of the grid-connected converter, the power expression of the grid-connected converter is derived: (5) Among them, P GFM U represents the active power injected into the AC system by a grid-connected power source. GFM For the port voltage of the grid-type converter, , These are the equivalent conductances between the grid-connected converter and the power grid, and between the grid-connected converter and the synchronous condenser, respectively. U is the equivalent admittance between the grid-connected converter and the power grid. g For grid-side voltage, E SC To synchronize the camera port voltage, I GFL This refers to the injected current at node 1; S2, according to the power expression (5), draw different I GFL The P-δ curve at amplitude; by adjusting I GFL The amplitude is adjusted to control the transient stability of the grid converter; S3, set transient control coefficients k1 and k2, and adjust the injected current I GFL and P ref ; When the difference between the accelerating and decelerating areas of the grid-type converter is positive, it is in a transiently stable state. In some implementations, S1 includes: S11, Based on the mathematical model of the grid-connected system of the grid-connected converter, the node voltage equation is expressed as follows: (1) Where: I1, I2, I3, and I4 are the injected currents at nodes 1, 2, 3, and 4, respectively, and I1 = I GFL U GFL =U P +I1 / Y GFL ; S12, according to formula (1), the matrix can be simplified to obtain: (2) Output current of grid-type converter: (3) The complex output power of the grid-type converter is: (4) S13, by adding the formulas (2) and (3) to (4), the analytical expression of the output active power of the grid-type converter is obtained, as shown in formula (5).

[0005] In some implementations, S2 includes: S21, according to the P-δ curve, by increasing P ref The value of this value causes the system's phase trajectory to diverge and become unstable; S22, according to the P-δ curve, by reducing P ref The value is chosen to stabilize the phase trajectory of the system.

[0006] In some implementations, S2 also includes: S23, according to the formula (5), the active power δ is output through the grid-type converter. GFL When the coupling term is negative, the power angle equation of the grid converter, based on the rotor motion equation, is: (9) S24, according to the formula (9), the rotor motion equation of the synchronous condenser is: (10) In some implementations, S3 includes: S3, set transient control coefficients k1 and k2, and adjust the injected current IGFL and P ref When the difference between the acceleration area and the deceleration area of ​​the grid-type converter is positive, it is in a transient stable state.

[0007] S31, according to the I GFL With P ref Transient stability adjustment is performed according to formula (11): (11) S32, based on grid faults, controls are switched, changing the power control loop of the grid-connected converter. The power control equation is then changed to: (12) S33 obtains the acceleration and deceleration areas of the power angle curve of the grid-type converter output power as an indicator for determining transient stability.

[0008] In some implementations, S33 includes: S331, Let the acceleration area of ​​the grid-type converter during the transient process be: (13) The power before the fault occurred was P. GFM1 During the fault, the power becomes P GFM2 After the fault is cleared, it becomes P. GFM3 Power reference value P ref The power angle is δ1 during steady-state operation, δ2 when the fault is cleared, and δ3 at the unstable equilibrium point. S332, deceleration area is: (14) S333 defines the transient synchronous stability criterion for a grid-type converter as ΔS, i.e.: (15) In some implementations, S333 includes: S3331, when ΔS>0, the system is transiently stable. After adopting the transient control strategy described in this paper, P in the transient process... GFM and P ref The changes occur, but the calculation principles for the acceleration and deceleration areas remain the same, that is: (16) (17) (18) When S3332, ΔS<0, k1 and k2 are adjusted to adjust I during the transient process. GFL With P refThe size of ΔS after the change * If the value is greater than 0, the system achieves transient stability.

[0009] In a second aspect, embodiments of the present invention provide a dynamic reconfiguration control device for network equipment that considers transient power angle stability, comprising, according to the method described in the first aspect above: The model building unit is used to derive the power expression for the grid-connected converter based on the mathematical model of the grid-connected converter system. (5) Among them, P GFM U represents the active power injected into the AC system by a grid-connected power source. GFM For the port voltage of the grid-type converter, , These are the equivalent conductances between the grid-connected converter and the power grid, and between the grid-connected converter and the synchronous condenser, respectively. U is the equivalent admittance between the grid-connected converter and the power grid. g For grid-side voltage, E SC To synchronize the camera port voltage, I GFL This refers to the injected current at node 1; The steady-state adjustment unit is used to plot different I values ​​according to the power expression (5). GFL The P-δ curve at amplitude; by adjusting I GFL The amplitude is adjusted to control the transient stability of the grid converter; The dynamic reconfiguration unit is used to set transient control coefficients k1 and k2, and adjust the injected current I. GFL and P ref When the difference between the acceleration area and the deceleration area of ​​the grid-type converter is positive, it is in a transient stable state.

[0010] Thirdly, embodiments of the present invention provide an electronic device, including a memory and a processor, wherein the memory is used to store one or more computer instructions, wherein when the one or more computer instructions are executed by the processor, they implement the method described in the first aspect above. Fourthly, embodiments of the present invention provide a computer storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, it implements the method described in the first aspect.

[0011] One or more embodiments of the present invention can bring at least the following beneficial effects: This invention improves the overall transient stability of a grid-connected system by dynamically changing the control strategy of the control loop during transient processes. This adjusts the converter output in the grid-connected system and enhances the overall transient stability of the system, enabling the grid-connected system to maintain stable operation during faults. The invention is constructed as follows... Figure 1 The grid-connected system with the grid converter shown is simulated and verified by setting a grid voltage drop fault, with the grid-connected system using the above-mentioned control strategy and the system without the above-mentioned control strategy, so as to verify the effectiveness of the proposed control strategy. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a grid-connected system structure diagram of a grid-connected converter, which is based on a grid-connected equipment dynamic reconfiguration control method that considers transient power angle stability, provided by an embodiment of the present invention. Figure 2 This is a schematic diagram of the phase relationship of the control coordinate system in a dynamic reconfiguration control method for network equipment that considers transient power angle stability, provided by an embodiment of the present invention. Figure 3 This is an example of an embodiment of the present invention providing a dynamic reconfiguration control method for network equipment considering transient power angle stability, showing output power angle curves of different IGFL network types. Figure 4 This is a schematic diagram of the transient process phase trajectory at different Pref times in a dynamic reconfiguration control method for network equipment that considers transient power angle stability, provided by an embodiment of the present invention. Figure 5 This is a transient control flowchart of a dynamic reconfiguration control method for network equipment that considers transient power angle stability, provided by an embodiment of the present invention. Figure 6 This is a modified control structure diagram of a dynamic reconfiguration control method for network equipment that considers transient power angle stability, provided by an embodiment of the present invention. Figure 7 This is a comparison diagram of the system response before and after adopting the control strategy of a dynamic reconfiguration control method for network equipment that considers transient power angle stability, provided by an embodiment of the present invention. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0015] Example 1: This invention provides a dynamic reconfiguration control method for network equipment that considers transient power angle stability, comprising: S1. Construct a mathematical model of the grid-connected system of the grid-connected converter and derive the expression for the output power of the grid-connected converter.

[0016] Since the bandwidth of the phase-locked loop (PLL) is much lower than that of the current loop, when analyzing transient synchronization stability problems on the PLL timescale, the adjustment process of the current loop can be ignored, and the current loop response can be considered to have reached a quasi-steady state, i.e., the injection current I from the GFL to the grid... GFL_dq equals I GFL_dq * Therefore, in terms of external characteristics, the GFL can be regarded as having an amplitude of I. GFL The phase angle is δ GFL +θ IGFL The current source.

[0017] Similarly, the response speed of the inner voltage loop of the GFM is much faster than that of the outer power loop, so the voltage loop can be ignored, and U can be considered as... GFM =U GFMref δ GFM =θ GFM In terms of external characteristics, GFM can be equivalent to a voltage source.

[0018] The established parallel system, such as Figure 1 As shown. Where U P U is the voltage at point PCC. g E is the grid-side voltage. SC To synchronize the camera port voltage, U GFL U GFM The port voltages of the grid-connected converter and the grid-connected converter are respectively, and the active power and reactive power injected into the AC system by the grid-connected power supply are respectively P. GFM Q GFM Ignore ground capacitance. To simplify the analysis, take an infinite AC system as an example, assuming the bus voltage amplitude U gThe phase angle δ is a constant value 1p.u. g The phase relationship between each control coordinate system and the reference coordinate system is as follows: Figure 2 As shown.

[0019] Write the nodal voltage equations: (1) Where: I1, I2, I3, and I4 are the injected currents at nodes 1, 2, 3, and 4, respectively, and I1 = I GFL U GFL =U P +I1 / Y GFL .

[0020] Simplifying from the first line, we get: (2) Output current of grid-type converter: (3) The complex output power of the grid-type converter is: (4) Substituting equations (2) and (3) into equation (4), we obtain the analytical expression for the output active power of the grid-type converter: (5) The admittance angle is simplified and defined as follows: (6) (7) Similarly, the analytical expression for the active power output of the synchronous modulator is: (8) S2. Plot the power angle curve and phase plane diagram, and analyze the impact of different reference values ​​on transient stability: Based on the power expression (5) derived above, plot different I GFL The P-δ curve at amplitude, as shown Figure 3 As shown, it can be seen that with I GFL As the amplitude increases, the power angle curve shifts to the upper right, and the deceleration area increases after the fault ends, indicating that appropriately increasing I... GFL The amplitude is beneficial to the transient stability of grid-type converters.

[0021] I GFL The magnitude is determined by I GFL_dq * Determine, different I GFL_dq * The value of the active and reactive current outputs of the grid converter will also affect the transient stability of the system.

[0022] After a grid fault occurs, if the current injected into the grid by the grid-connected converter is a pure reactive current, that is... I GFL_d * =0, its output frequency ω PLL This will decrease, resulting in its work angle δ GFL The value is negative and gradually decreases, while the grid-type converter and synchronous condenser will undergo accelerated motion, and the power angle δ GFM With δ SC As the value gradually increases, combined with equation (5), it can be seen that the active power output of the grid-type converter involves δ. GFL The coupling term is negative, which will increase the overall output active power. The power angle equation of the grid converter is based on the rotor motion equation, and is: (9) From the above formula, we can see that when P GFM As ω increases, the rate of increase of δ will decrease. GFM The changes will slow down, which will help the power angle to recover and stabilize after a fault.

[0023] The equation of motion for the synchronous condenser rotor is: (10) Similarly, when P SC As ω increases, the rate of increase of δ will decrease. SC The changes will slow down, which is beneficial for the power angle to recover and stabilize after a fault. Therefore, injecting pure reactive current into the grid through a grid-connected converter is beneficial for improving the transient stability of the grid-connected converter and the synchronous condenser.

[0024] Based on equation (9), draw different P ref Phase plane diagrams at the time of value selection, for analyzing P ref The effect of the selected value on the transient stability of the system is shown in the figure.

[0025] As can be seen, when P ref When the value of P is large, the system phase trajectory diverges and becomes unstable; as P... ref Decreasing P causes the phase trajectory to converge to the equilibrium point, improving system stability. Therefore, decreasing P... ref It helps improve the transient stability of the system.

[0026] S3 increases the transient control coefficient, changes the output during the transient period, and improves the transient stability of the system.

[0027] Based on the aforementioned analysis, consider changing I during the transient process. GFL With P ref Size to improve transient stability: (11) Where k1 and k2 are transient control coefficients, the specific values ​​of which can be changed according to the actual application scenario.

[0028] When a grid fault occurs, control switching is performed, changing the power control loop of the grid-connected converter. The power control equation is then changed to: (12) After adding the above control strategy, the rate of increase of the system power angle during transient processes will decrease, and transient stability will be improved.

[0029] The acceleration and deceleration areas of the power angle curve of the grid-type converter output power are used as indicators to determine transient stability. Let the power before the fault occur be P. GFM1 During the fault, the power becomes P GFM2 After the fault is cleared, it becomes P. GFM3 Power reference value P ref The power angle is δ1 during steady-state operation, δ2 during fault clearing, and δ3 at the unstable equilibrium point. Therefore, the acceleration area of ​​the grid-type converter during the entire transient process is: (13) The deceleration area is: (14) The transient synchronous stability criterion for a grid-type converter is defined as ΔS, i.e.: (15) When ΔS > 0, the system is transiently stable. After adopting the transient control strategy described in this paper, P in the transient process... GFM and P ref The changes occur, but the calculation principles for the acceleration and deceleration areas remain the same, that is: (16) (17) (18) When the system becomes transiently unstable, i.e., ΔS < 0, k1 and k2 can be adjusted to regulate I during the transient process. GFL With P ref The size of ΔS after the change * When ΔS > 0, the system achieves transient stability. When ΔS > 0 but the system's transient stability margin is small and it is nearing the instability boundary, k1 and k2 can be adjusted to make ΔS > 0. * Increase the value of the control coefficient to improve the transient stability margin of the system. The control coefficient that satisfies the transient stability requirements under the given scenario can be determined based on the control flow shown. The modified control structure is as follows: Figure 6 As shown.

[0030] Example 2: This invention provides a dynamic reconfiguration control device for network equipment that considers transient power angle stability. The method described in the above embodiments includes: The model building unit is used to derive the power expression for the grid-connected converter based on the mathematical model of the grid-connected converter system. (5) Among them, P GFM U represents the active power injected into the AC system by a grid-connected power source. GFM For the port voltage of the grid-type converter, , These are the equivalent conductances between the grid-connected converter and the power grid, and between the grid-connected converter and the synchronous condenser, respectively. U is the equivalent admittance between the grid-connected converter and the power grid. g For grid-side voltage, E SC To synchronize the camera port voltage, I GFL This refers to the injected current at node 1; The steady-state adjustment unit is used to plot different I values ​​according to the power expression (5). GFL The P-δ curve at amplitude; by adjusting I GFL The amplitude is adjusted to control the transient stability of the grid converter; The dynamic reconfiguration unit is used to set transient control coefficients k1 and k2, and adjust the injected current I. GFL and P ref When the difference between the acceleration area and the deceleration area of ​​the grid-type converter is positive, it is in a transient stable state.

[0031] Example 3: This embodiment also provides an electronic device, including a memory and a processor, wherein the memory is used to store one or more computer instructions, wherein the one or more computer instructions are executed by the processor to implement the method of Embodiment 1; In practical applications, the processor can be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller unit (MCU), microprocessor, or other electronic components to execute the methods described in the above embodiments.

[0032] The method implemented in this embodiment is as shown in Embodiment 1.

[0033] Example 4: This embodiment also provides a computer storage medium, in which a computer program is stored, and when the computer program is executed by one or more processors, it implements the method of embodiment one. The computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0034] The method implemented in this embodiment is as shown in Embodiment 1.

[0035] In the several embodiments provided in this invention, it should be understood that the disclosed systems and methods can also be implemented in other ways. The system and method embodiments described above are merely illustrative.

[0036] It should be noted that, in this document, the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. 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 a process, method, article, or apparatus. Without further limitations, 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 said element.

[0037] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A dynamic reconfiguration control method for network equipment considering transient power angle stability, characterized in that, include: S1, Based on the mathematical model of the grid-connected system of the grid-connected converter, the power expression of the grid-connected converter is derived: (5) Among them, P GFM U represents the active power injected into the AC system by a grid-connected power source. GFM For the port voltage of the grid-type converter, , These are the equivalent conductances between the grid-connected converter and the power grid, and between the grid-connected converter and the synchronous condenser, respectively. U is the equivalent admittance between the grid-connected converter and the power grid. g For grid-side voltage, E SC To synchronize the camera port voltage, I GFL This refers to the injected current at node 1; S2, according to the power expression (5), draw different I GFL The P-δ curve at amplitude; by adjusting I GFL The amplitude adjusts the transient stability of the grid converter; S3, set transient control coefficients k1 and k2, and adjust the injected current I GFL and P ref ; When the difference between the acceleration area and the deceleration area of ​​the grid-type converter is positive, it is in a transient stable state.

2. The method according to claim 1, characterized in that, S1 includes: S11, Based on the mathematical model of the grid-connected system of the grid-connected converter, the node voltage equation is expressed as follows: (1) Where: I1, I2, I3, and I4 are the injected currents at nodes 1, 2, 3, and 4, respectively, and I1 = I GFL U GFL =U P +I1 / Y GFL ; S12, according to formula (1), the matrix can be simplified to obtain: (2) Output current of grid-type converter: (3) The complex output power of the grid-type converter is: (4) S13, by adding the above formulas (2) and (3) to (4), the analytical expression of the output active power of the grid-type converter is obtained, as shown in formula (5).

3. The method according to claim 2, characterized in that, S2 include: S21, according to the P-δ curve, by increasing P ref The value of this value causes the system's phase trajectory to diverge and become unstable; S22, according to the P-δ curve, by reducing P ref The value is chosen to stabilize the phase trajectory of the system.

4. The method according to claim 2, characterized in that, S2 also includes: S23, according to the formula (5), the active power δ is output through the grid-type converter. GFL When the coupling term is negative, the power angle equation of the grid converter, based on the rotor motion equation, is: （9） S24, according to the formula (9), the rotor motion equation of the synchronous condenser is: （10）。 5. The method according to claim 4, characterized in that, S3 include: S31, according to the I GFL With P ref Transient stability adjustment is performed according to formula (11): (11) S32, based on grid faults, control switching is performed, changing the power control loop of the grid-connected converter, and the power control equation is changed to: (12) S33 obtains the acceleration and deceleration areas of the power angle curve of the grid-type converter output power as an indicator for determining transient stability.

6. The method according to claim 5, characterized in that, S33 includes: S331, Let the acceleration area of ​​the grid-type converter during the transient process be: (13) The power before the fault occurred was P. GFM1 During the fault, the power becomes P GFM2 After the fault is cleared, it becomes P. GFM3 Power reference value P ref The power angle is δ1 during steady-state operation, δ2 when the fault is cleared, and δ3 at the unstable equilibrium point. S332, deceleration area is: (14) S333 defines the transient synchronous stability criterion for a grid-type converter as ΔS, i.e.: (15)。 7. The method according to claim 6, characterized in that, S333 includes: S3331, when ΔS>0, the system is transiently stable. After adopting the transient control strategy described in this paper, P in the transient process... GFM and P ref The changes occur, but the calculation principles for the acceleration and deceleration areas remain the same, that is: (16) (17) (18) When S3332, ΔS<0, k1 and k2 are adjusted to adjust I during the transient process. GFL With P ref The size of ΔS after the change * If the value is greater than 0, the system achieves transient stability.

8. A dynamic reconfiguration control device for network equipment considering transient power angle stability, wherein the method according to any one of claims 1-7 is characterized in that, include: The model building unit is used to derive the power expression for the grid-connected converter based on the mathematical model of the grid-connected converter system. (5) Among them, P GFM U represents the active power injected into the AC system by a grid-connected power source. GFM For the port voltage of the grid-type converter, , These are the equivalent conductances between the grid-connected converter and the power grid, and between the grid-connected converter and the synchronous condenser, respectively. U is the equivalent admittance between the grid-connected converter and the power grid. g For grid-side voltage, E SC To synchronize the camera port voltage, I GFL This refers to the injected current at node 1; The steady-state adjustment unit is used to plot different I values ​​according to the power expression (5). GFL The P-δ curve at amplitude; by adjusting I GFL The amplitude adjusts the transient stability of the grid converter; The dynamic reconfiguration unit is used to set transient control coefficients k1 and k2, and adjust the injected current I. GFL and P ref When the difference between the acceleration area and the deceleration area of ​​the grid-type converter is positive, it is in a transient stable state.

9. An electronic device, characterized in that, The device includes a memory and a processor, the memory being used to store one or more computer instructions, wherein the one or more computer instructions, when executed by the processor, implement the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, is used to implement the method as described in any one of claims 1-7.

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