Transient stability adaptive damping control method and system for multi-network power supply system

Abstract

The invention discloses a transient stability adaptive damping control method and system for a multi-network power supply system. The method comprises the following steps: acquiring an adaptive coefficient of a virtual synchronous machine of the multi-network power supply system under a current working condition; obtaining an angular frequency deviation according to the converter output angular frequency instruction value and the converter output angular frequency actual value at the previous moment; obtaining a dynamic damping increment according to the adaptive coefficient and the angular frequency deviation; equivalent damping is obtained according to the virtual damping and the dynamic damping increment; and according to the equivalent damping, the virtual inertia, a converter output active power actual value and an active power instruction value, a converter output angular frequency instruction value and a converter output angular frequency actual value at the previous moment, performing active power control of the virtual synchronous machine by using an active power control equation after the self-adaptive damping coefficient is introduced. And obtaining a current converter output angular frequency actual value.

Description

Technical Field

[0001] This application relates to a transient stability adaptive damping control method and system for multi-grid power systems, belonging to the field of power system automation technology. Background Technology

[0002] Stable synchronous support is the fundamental prerequisite for grid-connected converters to achieve continuous power transmission and grid support, thereby providing a solid guarantee for new power systems. Maintaining voltage phase synchronization is crucial for achieving continuous and reliable power supply in scenarios without an external voltage reference. Grid-connected converters can autonomously establish voltage amplitude and phase references on the AC side, making them an effective means of supporting weak grids and even islanded grids. Among these, virtual synchronous generators (VSGs), which simulate rotor swing equations to provide virtual inertia and damping for the system, have been widely adopted. Unlike traditional synchronous machines, the inertia, damping, and voltage parameters of a VSG can be flexibly set, creating unique conditions for its online adaptive regulation.

[0003] However, fixed damping coefficients are still widely used in engineering, which have limited ability to suppress power angle sway during large disturbances and are prone to transient loss of synchronism. Summary of the Invention

[0004] Objective: In view of the inherent defect of existing virtual synchronous machines using fixed damping coefficients, which makes it difficult to effectively suppress large disturbance power angle oscillations, this application provides a transient stability adaptive damping control method and system for multi-grid power systems. The damping generation structure of the VSG active loop is reconstructed, and a nonlinear element that is adaptively enhanced with angular frequency deviation is introduced to enable the system to obtain a matching damping strength during large disturbances.

[0005] Without changing the steady-state operating point, this application fully utilizes the advantages of the VSG active power loop control structure being simple and easy to adjust, and directly reconstructs the damping within the active power channel, enabling it to automatically increase or decrease with angular frequency deviation, thereby achieving adaptive adjustment of transient intensity.

[0006] The technical solution adopted in this application is:

[0007] In a first aspect, this application provides a transient stability adaptive damping control method for a multi-grid power system, including:

[0008] Obtain the adaptive coefficient k of the virtual synchronous machine of the multi-grid power system under the current operating conditions;

[0009] The angular frequency deviation ω-ω0 is obtained based on the converter output angular frequency command value ω0 and the actual value ω of the converter output angular frequency at the previous moment.

[0010] The dynamic damping increment k(ω-ω0) is obtained based on the adaptive coefficient k and the angular frequency deviation. 2 ;

[0011] The equivalent damping D is obtained based on the virtual damping D and the dynamic damping increment. eq =D+k(ω-ω0) 2 ;

[0012] According to the equivalent damping D eq Virtual inertia J, actual value of converter output active power P e and active power command value P ref The converter output angular frequency command value ω0 and the actual value ω of the converter output angular frequency at the previous moment are used to perform virtual synchronous machine active power control using the active power control equation after introducing the adaptive damping coefficient, so as to obtain the actual value ω of the converter output angular frequency at the current moment.

[0013] In some embodiments, each grid-type converter in a multi-grid power system is controlled by a virtual synchronous machine, and the active power control equation is:

[0014] ;

[0015] Where J and D are virtual inertia and virtual damping, respectively; t is time; ω and ω0 are the actual and commanded values ​​of the converter output angular frequency, respectively; P e and P ref These represent the actual and commanded values ​​of the converter's output active power, respectively; D eq =D+k(ω-ω0) 2 For equivalent damping, k is a non-negative adaptive coefficient.

[0016] During steady-state operation, ω - ω0 = 0, the dynamic damping increment is zero, and the governing equation naturally degenerates into: It does not change the steady-state power flow and operating point of the system.

[0017] During the transient process, as the angular frequency deviation increases, the equivalent damping dynamically changes with the angular frequency deviation, forming a nonlinear damping mechanism with time-varying dissipation characteristics, which effectively improves the system's synchronization stability. As the equivalent damping continues to increase with the angular frequency, the out-of-synchronization unit re-converges to a new stable equilibrium point during subsequent oscillations, achieving resynchronization.

[0018] In some embodiments, obtaining the adaptive coefficient k of the virtual synchronous machine of the multi-grid power system under the current operating condition includes:

[0019] For the selected representative fault location, the most severe fault type at the representative fault location is selected, and the maximum allowable clearing time of the relay protection is taken as the clearing time. The adaptive coefficient value is scanned offline within the preset observation period to obtain the critical adaptive coefficient value of the system from sliding to resynchronization. This critical adaptive coefficient value is used as the set value of the adaptive coefficient k to complete the tuning.

[0020] Secondly, this application provides a transient stability adaptive damping control system for a multi-grid power system, including a processor and a storage medium;

[0021] The storage medium is used to store instructions;

[0022] The processor is configured to operate according to the instructions to execute the method described in accordance with the first aspect.

[0023] Thirdly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in the first aspect.

[0024] Fourthly, this application provides a computer device including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method described in the first aspect.

[0025] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the method described in the first aspect.

[0026] Beneficial Effects: The transient stability adaptive damping control method and system for multi-grid power systems provided in this application have the following advantages: This application introduces a feedback term proportional to the square of the angular frequency deviation (speed deviation) into the damping channel of the active power control loop of the virtual synchronous generator. This causes the equivalent damping coefficient to automatically increase with the disturbance intensity during transients and automatically return to zero in steady state. Thus, without changing the system's steady-state operating point, it significantly suppresses power angle swing and effectively improves system stability. For multi-grid converter systems, this method requires no additional communication to achieve distributed adaptive enhancement of damping for each unit, improving the transient synchronization stability margin of the regional power grid. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the VSG control principle in an embodiment of this application.

[0028] Figure 2 This is a schematic diagram of the active power control principle of the VSG fixed damper in the embodiment.

[0029] Figure 3 This is a schematic diagram of the active power control principle of the adaptive damping control proposed in this application.

[0030] Figure 4 A three-machine, nine-node system for verifying the validity of this application.

[0031] Figure 5 This is a phase plane diagram under different adaptive coefficients in the embodiments of this application.

[0032] Figure 6 The diagram shows the power angle characteristic curves under different adaptive coefficients in the embodiments of this application. Detailed Implementation

[0033] The present application will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and should not be used to limit the scope of protection of the present application.

[0034] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0035] In the description of this application, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0036] The term "and / or" simply describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0037] To address the inherent limitation of existing virtual synchronous generators (VSGs) using fixed damping coefficients, which struggle to effectively suppress large disturbance power angle oscillations, this application proposes a new approach for multi-grid power systems (ignoring nonlinear limiting elements). This approach introduces a feedback term proportional to the square of the angular frequency deviation into the damping channel of the active power control loop of the VSG. This causes the equivalent damping coefficient to automatically increase with disturbance intensity during transients and automatically return to zero in steady state. This significantly suppresses power angle oscillations and effectively improves system stability without altering the system's steady-state operating point. For multi-grid converter systems, this method eliminates the need for additional communication, enabling distributed adaptive enhancement of damping for each generator unit and improving the transient synchronization stability margin of the regional power grid.

[0038] Example 1: This example provides a transient stability adaptive damping control method for a multi-grid power system, including:

[0039] Obtain the adaptive coefficient k of the virtual synchronous machine of the multi-grid power system under the current operating conditions;

[0040] The angular frequency deviation ω-ω0 is obtained based on the converter output angular frequency command value ω0 and the actual value ω of the converter output angular frequency at the previous moment.

[0041] The dynamic damping increment k(ω-ω0) is obtained based on the adaptive coefficient k and the angular frequency deviation. 2 ;

[0042] The equivalent damping D is obtained based on the virtual damping D and the dynamic damping increment. eq =D+k(ω-ω0) 2 ;

[0043] According to the equivalent damping D eq Virtual inertia J, actual value of converter output active power P e and active power command value P ref The converter output angular frequency command value ω0 and the actual value ω of the converter output angular frequency at the previous moment are used to perform virtual synchronous machine active power control using the active power control equation after introducing the adaptive damping coefficient, so as to obtain the actual value ω of the converter output angular frequency at the current moment.

[0044] In some embodiments, such as Figure 1 As shown, the circuit topology of the virtual synchronous machine is a three-phase inverter circuit, with a DC side voltage of U. dc The output side is filtered by resistor R. f Filter inductor L f and filter capacitor C f The filter circuit is connected to a common grid connection point; the control method of the virtual synchronous machine includes:

[0045] The instantaneous three-phase voltage U was obtained by sampling at the public grid connection point. abc With the instantaneous value of current I abc After coordinate transformation and power calculation, the actual value of the output active power P is obtained. e The actual value of reactive power Q;

[0046] The active power loop is based on the active power command value P ref With the actual value of active power P e The deviation is determined by combining the actual value of the virtual angular frequency ω with the command value of the angular frequency ω0. The actual value of the angular frequency ω is dynamically adjusted by simulating the rotor motion equation of the synchronous generator and the internal electromotive force phase θ is obtained by integration.

[0047] The reactive power loop is based on the reactive power command value Q. ref The deviation from the actual reactive power value Q is included, along with the grid connection point voltage U and the grid connection point voltage reference value U. ref Adjustments are made to determine the internal potential amplitude E;

[0048] The three-phase internal potential E is synthesized from the internal potential amplitude E and the internal potential phase θ. abc Three-phase internal potential E abc The modulated voltage signal V in the dq coordinate system is obtained through inner loop control. dq V dq The modulation wave V in the three-phase stationary coordinate system is obtained by inverse Parker transformation. abc Finally, the signal is sent to the PWM module to generate the switching signal that drives the inverter bridge.

[0049] S1: In response to the detection of a line fault, acquire the disturbed electromechanical transient trajectories of each virtual synchronous machine in the multi-network power system.

[0050] like Figure 2 The diagram shown illustrates the active power control principle of a VSG with fixed damping. Its active power control equation is as follows:

[0051] ;

[0052] In the formula: J and D are virtual inertia and virtual damping, respectively; t is time; ω and ω0 are the actual and commanded values ​​of the converter output angular frequency, respectively; P e and P ref These are the actual and commanded values ​​of the converter's output active power, respectively.

[0053] In virtual synchronous control, the damping term not only performs primary frequency regulation but also suppresses oscillations. Its typical value is significantly higher than that of traditional synchronous generators, having a crucial impact on system transient stability. Therefore, the magnitude of the virtual damping term D plays a critical role in transient stability.

[0054] Figure 3This is a schematic diagram of the active power control principle of the adaptive damping control proposed in this application. The active power control equation after introducing the adaptive damping coefficient is as follows:

[0055]

[0056] In the formula: D eq =D+k(ω-ω0) 2 is the equivalent damping coefficient, and k is a non-negative adaptive coefficient.

[0057] In the above formula, k(ω-ω0) 2 This constitutes the dynamic damping increment, making the equivalent damping coefficient D eq =D+k(ω-ω0) 2 It changes dynamically with the angular frequency deviation. In steady-state operation, ω - ω0 = 0, the dynamic damping increment is zero, and the governing equation naturally degenerates to: This does not change the steady-state power flow and operating point of the system. During the transient process, as the angular frequency deviation increases, the equivalent damping dynamically changes and strengthens with the angular frequency deviation, forming a nonlinear damping mechanism with time-varying dissipation characteristics, which effectively improves the synchronization stability of the system. As the equivalent damping continues to increase with the angular frequency, the out-of-synchronization unit reconverges to a new stable equilibrium point during subsequent oscillations, achieving resynchronization.

[0058] In this embodiment, a feedback term proportional to the square of the angular frequency deviation is introduced into the damping channel of the active power control loop of the Virtual Synchronous Generator (VSG). This forms an equivalent damping that increases with the increase of disturbance and automatically returns to zero in steady state. It does not change the power flow or primary frequency regulation and still has autonomous resynchronization capability after sliding. This link is embedded in each grid-connected converter, and each unit independently completes the damping enhancement according to its own angular frequency deviation, realizing multi-machine distributed coordination and improving the transient synchronization stability margin of the regional power grid.

[0059] In some embodiments, obtaining the adaptive coefficient k of the virtual synchronous machine of the multi-grid power system under the current operating condition includes:

[0060] For the selected representative fault location, the most severe fault type at the representative fault location is selected, and the maximum allowable clearing time of the relay protection is taken as the clearing time. The adaptive coefficient value is scanned offline within the preset observation period to obtain the critical adaptive coefficient value of the system from sliding to resynchronization. This critical adaptive coefficient value is used as the set value of the adaptive coefficient k to complete the tuning.

[0061] Furthermore, the most severe fault type is a three-phase metallic short circuit. Under the same fault condition, the value of the adaptive coefficient k is changed successively. For each simulation, the values ​​are continuously observed for 30 to 50 power frequency cycles. The critical adaptive coefficient value at which the power angle trajectory transitions from sliding to synchronous and stable operation is recorded. The critical adaptive coefficient value is used as the minimum set value of the adaptive coefficient k. The system can be put into operation after a single setting.

[0062] It should be noted that the value of the adaptive coefficient k is fixed under the same working conditions.

[0063] Simulation verification: The VSG system uniformly uses, for example... Figure 3 The active power control of the adaptive damping control shown is built in the PSCAD / EMTDC simulation platform as follows: Figure 4 The three-machine, nine-node system shown has a constant impedance load within it, and is set to operate at a constant impedance for 3 seconds. Figure 4 A three-phase short-circuit fault occurred at point ①. The relay protection was set to activate after 3.13 seconds, and the faulty line was cleared. The fault clearing time significantly exceeded the limit clearing time under the traditional fixed damping condition, which can fully expose the shortcomings of fixed damping and provide a comparative space for the adjustment effect of the adaptive damping of this application.

[0064] Example 1: The fault trajectory is collected. Based on the power angle trajectory shape, n disturbed electromechanical transient trajectories are projected onto a one-dimensional power angle axis at each sampling time and arranged in ascending order of value to generate n-1 adjacent gaps. Among the n-1 adjacent gaps, if a gap grows unbounded over time, it is determined to be an unbounded position gap (UPG). The virtual synchronous machine in the multi-network power system is divided into the leading group (S group) with power angle above the unbounded position gap and the remaining group (A group) with power angle below the unbounded position gap.

[0065] It should be noted that a multi-grid power system contains n virtual synchronous machines. Therefore, for any virtual synchronous machine, the rotor motion equation of the i-th virtual synchronous machine is:

[0066] ;

[0067] In the formula: J i and D i Let be the virtual inertia and virtual damping of the i-th virtual synchronizer, respectively; For time; ω i ωi is the actual output angular frequency of the i-th virtual synchronizer, and ω0 is the commanded output angular frequency value of the virtual synchronizer; P ei and P refi These are the actual and commanded values ​​of the output active power of the i-th virtual synchronous machine, respectively.

[0068] Verification Example 1: Building a system on the PSCAD / EMTDC platform, such as... Figure 4 The three-machine, nine-node system shown has VSG1~VSG3 connected to the network via a step-up transformer. A schematic diagram of its active power loop control principle is shown below. Figure 3 ,exist Figure 4 A three-phase short-circuit fault is set at node ①, with a fault duration of 0.103s. The swing equation of the VSG is:

[0069]

[0070] In the formula: subscripts 1, 2, and 3 represent the relevant variables of the grid-type converters VSG1, VSG2, and VSG3, respectively.

[0071] Based on the power angle trajectories of the three VSGs, VSG1 is assigned to the leading group, while VSG2 and VSG3 are assigned to the remaining group (Group A). ​​Aggregating the remaining group yields:

[0072]

[0073] The difference in work angle between the leading group and the remaining groups is Δδ=δ S −δ A With the horizontal axis as the derivative corresponding to the power angle difference, i.e., the speed difference Δω = ω S −ω A Using the vertical axis as the ordinate, plot the phase plane trajectory. If the trajectory crosses a point that cannot cross zero and continues to expand outward, the system is considered unstable; if the trajectory is captured by the attraction domain and eventually returns to the stable equilibrium point, the system is considered stable. In a single fault scenario, this application uses a bisection method to quickly search for the critical adaptive coefficient k. min The initial interval is set to 0 and an upper limit of an appropriate size. Simulations are performed each time using the midpoint k value of the interval. It is observed whether the power angle trajectory changes from a sliding step to a stable initial swing within 30-50 power frequency cycles. The interval is then narrowed down by bisection based on the trajectory shape until the difference between the endpoints of the interval is less than the set resolution, and finally k is obtained. min =44.63. Figure 5 The phase plane trajectories for four cases are given: k=0 (without the adaptive damping control described in this paper), k=44.62, k=44.63, and k=100. The k=0 trajectory rapidly crosses the unstable equilibrium point and continues to expand outwards. The k=44.62 trajectory exhibits a typical sliding and then resynchronizing pattern, with the phase point initially moving outwards, then being captured by the attraction domain and slowly returning to the next stable equilibrium point. The k=44.63 phase trajectory separates precisely from the k=44.62 curve near ω=0; the former's phase point is captured by the attraction domain, crosses the horizontal axis, and then slowly moves back to the equilibrium point along the stable manifold, thus confirming the critical k value obtained by the bisection method. The k=100 trajectory converges rapidly. This graphically verifies the enhancement effect of this application on the transient synchronization stability of multi-machine systems.

[0074] For the two groups after the split, we have:

[0075]

[0076] Then, through equal-value aggregation, we get:

[0077]

[0078] In the formula:

[0079]

[0080] In the formula: , , , , These are the equivalent virtual power angle value, equivalent virtual inertia value, equivalent output active power actual value, equivalent active power command value, and equivalent damping power value of the equivalent single unit, respectively. , These are the aggregated virtual inertia and aggregated virtual power angle values ​​of the virtual synchronizers in the leading group, respectively. , These are the aggregated values ​​of the actual and commanded active power outputs of the virtual synchronizers in the leading group, respectively. , These are the aggregated values ​​of virtual inertia and virtual power angle for the virtual synchronizers in the remaining group, respectively. , These are the aggregated values ​​of the actual and commanded active power outputs of the virtual synchronizers in the remaining groups, respectively. , These are the virtual damping values ​​for the i-th virtual synchronizer of the leading group and the j-th virtual synchronizer of the remaining group, respectively. , These are the actual output angular frequencies of the i-th virtual synchronizer in the leading group and the j-th virtual synchronizer in the remaining groups, respectively. This is the output angular frequency command value of the virtual synchronizer.

[0081] Based on phase plane comparison, the extended equal area criterion is further used to quantitatively analyze the disturbed trajectory: as described in the above formula derivation, the three-machine high-dimensional trajectory is reduced to a single-machine equivalent system by grouping and aggregation, and the P-δ curves of equivalent mechanical power and electromagnetic power as a function of power angle are obtained. Then, the integral is completed according to the traditional definition of acceleration area and deceleration area, and the critical energy is calculated by introducing a fictitious power curve, and finally the stability margin η under different k is obtained.

[0082] Acceleration and deceleration area:

[0083]

[0084] In the formula, Ainc To accelerate the area, A dec δ is the acceleration area; δ0 is the power angle during steady-state operation; δ c For fault clearing angle; P meq The equivalent mechanical power is P. refeq -P Deq ;δ u When the system is stable, it represents the power angle at the farthest point; when the system is unstable, it represents the power angle at the unstable equilibrium point.

[0085] Stability margin:

[0086]

[0087] In the formula, η is the stability margin, and A inc To accelerate the area, A dec To accelerate the area, A dec.pot The hypothetical area is the minimum additional kinetic energy required to make the system at its farthest point just lose its synchronous stability. This value can be calculated using the extended equal area rule.

[0088] Table 1 summarizes the acceleration area A corresponding to typical k values. inc Deceleration area A dec and stability margin η: when k = 0, A inc Significantly greater than A dec When η is -29.2% < 0, the system is unstable; when k = k min At that time, A inc With A dec They are almost equal, η≈0%, and are at critical stability; as k continues to increase, A inc The transient stability margin increases monotonically, while η increases monotonically and turns from negative to positive and continues to rise. For example, from k=0 to k=100, the stability margin increases from -29.2% to 18.9%, indicating a significant improvement in transient stability margin. This quantitative result is completely consistent with the phase diagram observation, numerically confirming the effectiveness of the proposed method. Figure 6 P-δ curves were plotted for k=0, k=50, and k=100 in Table 1.

[0089] Table 1: Acceleration / deceleration area and stability margin under different adaptive coefficients

[0090]

[0091] Therefore, based on this verification example, it can be seen that the transient stability adaptive damping control method for multi-grid power systems proposed in this application can improve the effectiveness and accuracy of the transient synchronization stability of multi-grid power systems, guide the parameter adjustment and control optimization of grid-type converter systems, and help improve the synchronization stability of grid-type converter systems.

[0092] Example 2: Based on Example 1, this example provides a transient stability adaptive damping control system for a multi-grid power system, including a processor and a storage medium;

[0093] The storage medium is used to store instructions;

[0094] The processor is configured to operate according to the instructions to execute the method according to Embodiment 1.

[0095] Example 3: Based on Example 1, this example provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method described in Example 1.

[0096] Example 4: Based on Example 1, this example provides a computer device, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the method described in Example 1.

[0097] Example 5: Based on Example 1, this example provides a computer program product, including a computer program that, when executed by a processor, implements the method described in Example 1.

[0098] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0099] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0100] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0101] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0102] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A transient stability adaptive damping control method for a multi-grid power system, characterized in that, include: Obtain the adaptive coefficient k of the virtual synchronous machine of the multi-grid power system under the current operating conditions; The angular frequency deviation ω-ω0 is obtained based on the converter output angular frequency command value ω0 and the actual value ω of the converter output angular frequency at the previous moment. The dynamic damping increment k(ω-ω0) is obtained based on the adaptive coefficient k and the angular frequency deviation. 2 ; The equivalent damping D is obtained based on the virtual damping D and the dynamic damping increment. eq =D+k(ω-ω0) 2 ; According to the equivalent damping D eq Virtual inertia J, actual value of converter output active power P e and active power command value P ref The converter output angular frequency command value ω0 and the actual value ω of the converter output angular frequency at the previous moment are used to perform virtual synchronous machine active power control using the active power control equation after introducing the adaptive damping coefficient, so as to obtain the actual value ω of the converter output angular frequency at the current moment.

2. The method according to claim 1, characterized in that, Each grid-type converter in a multi-grid power system is controlled by a virtual synchronous machine, and the active power control equation is as follows: ； Where J and D are virtual inertia and virtual damping, respectively; t is time; ω and ω0 are the actual and commanded values ​​of the converter output angular frequency, respectively; P e and P ref These represent the actual and commanded values ​​of the converter's output active power, respectively; D eq =D+k(ω-ω0) 2 For equivalent damping, k is a non-negative adaptive coefficient.

3. The method according to claim 2, characterized in that, During steady-state operation, ω - ω0 = 0, the dynamic damping increment is zero, and the governing equation naturally degenerates into: It does not change the steady-state power flow and operating point of the system.

4. The method according to claim 2, characterized in that, During the transient process, as the angular frequency deviation increases, the equivalent damping dynamically changes with the angular frequency deviation, forming a nonlinear damping mechanism with time-varying dissipation characteristics, which effectively improves the system's synchronization stability. As the equivalent damping continues to increase with the angular frequency, the out-of-synchronization unit re-converges to a new stable equilibrium point during subsequent oscillations, achieving resynchronization.

5. The method according to claim 1, characterized in that, Obtain the adaptive coefficient k of the virtual synchronous machine of the multi-grid power system under the current operating conditions, including: For the selected representative fault location, the most severe fault type at the representative fault location is selected, and the maximum allowable clearing time of the relay protection is taken as the clearing time. The adaptive coefficient value is scanned offline within the preset observation period to obtain the critical adaptive coefficient value of the system from sliding to resynchronization. This critical adaptive coefficient value is used as the set value of the adaptive coefficient k to complete the tuning.

6. The method according to claim 5, characterized in that, The most severe fault type is a three-phase metallic short circuit. Under the same fault condition, the value of the adaptive coefficient k is changed successively. Each simulation is observed for 30 to 50 power frequency cycles. The critical adaptive coefficient value at which the power angle trajectory changes from sliding to synchronous and stable operation is recorded. The critical adaptive coefficient value is used as the minimum set value of the adaptive coefficient k.

7. The method according to claim 1, characterized in that, The circuit topology of the virtual synchronous machine is a three-phase inverter circuit, with a DC side voltage of U. dc The output side is filtered by resistor R. f Filter inductor L f and filter capacitor C f The filter circuit is then connected to a common grid connection point. The control method for the virtual synchronizer includes: The instantaneous three-phase voltage U was obtained by sampling at the public grid connection point. abc With the instantaneous value of current I abc After coordinate transformation and power calculation, the actual value of the output active power P is obtained. e The actual value of reactive power Q; The active power loop is based on the active power command value P ref With the actual value of active power P e The deviation is determined by combining the actual value of the virtual angular frequency ω with the command value of the angular frequency ω0. The actual value of the angular frequency ω is dynamically adjusted by simulating the rotor motion equation of the synchronous generator and the internal electromotive force phase θ is obtained by integration. The reactive power loop is based on the reactive power command value Q. ref The deviation from the actual reactive power value Q is included, along with the grid connection point voltage U and the grid connection point voltage reference value U. ref Adjustments are made to determine the internal potential amplitude E; The three-phase internal potential E is synthesized from the internal potential amplitude E and the internal potential phase θ. abc Three-phase internal potential E abc The modulated voltage signal V in the dq coordinate system is obtained through inner loop control. dq V dq The modulation wave V in the three-phase stationary coordinate system is obtained by inverse Parker transformation. abc Finally, the signal is sent to the PWM module to generate the switching signal that drives the inverter bridge.

8. A transient stability adaptive damping control system for a multi-grid power system, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the method according to any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method according to any one of claims 1 to 7.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1 to 7.

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