CN116882115A - Transient stability analysis method, device, equipment and medium of new energy grid-connected system - Google Patents

Transient stability analysis method, device, equipment and medium of new energy grid-connected system Download PDF

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Publication number
CN116882115A
CN116882115A CN202310994584.8A CN202310994584A CN116882115A CN 116882115 A CN116882115 A CN 116882115A CN 202310994584 A CN202310994584 A CN 202310994584A CN 116882115 A CN116882115 A CN 116882115A
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China
Prior art keywords
fault
inverter
power angle
grid
new energy
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Inventor
韩子娇
谢小荣
龚振
贾祺
那广宇
苏禹泽
屈超
董文凯
窦文雷
佟永吉
芦思晨
董鹤楠
张强
李欣蔚
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Tsinghua University
State Grid Liaoning Electric Power Co Ltd
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Tsinghua University
State Grid Liaoning Electric Power Co Ltd
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Priority to CN202310994584.8A priority Critical patent/CN116882115A/en
Publication of CN116882115A publication Critical patent/CN116882115A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/18—Network design, e.g. design based on topological or interconnect aspects of utility systems, piping, heating ventilation air conditioning [HVAC] or cabling
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/06—Power analysis or power optimisation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin

Abstract

The application relates to a transient stability analysis method, a device, equipment and a medium of a new energy grid-connected system, wherein the method comprises the following steps: constructing a fault front power angle function model and a fault back power angle function model of a new energy grid-connected single machine infinite system adopting droop control; drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model; and analyzing transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve. Therefore, the problems that the influence of the interaction of the output currents of the multiple power electronic devices on the transient stability is not considered, the transient stability performance cannot be analyzed and improved through multiple machine grid connection and the like in the prior art are solved.

Description

Transient stability analysis method, device, equipment and medium of new energy grid-connected system
Technical Field
The application relates to the technical field of disturbance stability analysis of a new energy grid-connected system, in particular to a transient stability analysis method, a device, equipment and a medium of the new energy grid-connected system.
Background
The new energy generator set generally adopts a voltage source type inverter to convert direct current into alternating current so as to be connected with an alternating current power grid, so that the transient stability of the inverter under large disturbance is analyzed and improved, and the power grid can be maintained safely and stably. According to the definition of power system stability, large disturbance stability problems include transient stability (i.e., synchronous stability) and large disturbance voltage stability, which relate to the ability of the power system to remain synchronous.
In the conventional power grid, since the synchronous generator is used as a main power source, a great deal of research is accumulated in terms of transient stability of the synchronous generator, and it is required to design and operate the power grid according to transient stability-related boundary conditions. In the new power system, with the access of high-proportion new energy and power electronic equipment, the transient stability problem related to the operation characteristics of the inverter is also gradually highlighted. Among them, the inverter based on droop control (or virtual synchronous machine control) also has transient stability problems due to its analog synchronous generator power angle characteristics, and is related to output current clipping. In addition, the output currents of the multiple inverters are mutually influenced at the collecting bus, so that the transient stability of the grid-connected system is easily and negatively influenced.
Compared with the small disturbance stability analysis, the large disturbance stability analysis method for the new energy grid-connected system is still in a starting stage at present.
At present, under the condition that the related technology can control sagging, experiments prove that the transient stability of a grid-connected system can be seriously affected after the output current of an inverter is excessively limited; in addition, in the related art, under two working conditions of disturbance and fault of the output power of the inverter, a virtual power angle is provided to quantify the influence mechanism of current amplitude limiting on transient stability, and the active frequency droop characteristic is improved, so that the grid-connected transient stability of a single inverter is improved.
In summary, the existing transient stability performance improving method only focuses on the transient stability of a single inverter connected with an infinite power grid, lacks knowledge of the influence mechanism of multiple machine grid connection on the transient stability, does not consider the interaction of output currents of multiple power electronic devices, has influence on the transient stability improvement, and is difficult to provide a reliable scheme for safe operation control design, so that the problem needs to be solved.
Disclosure of Invention
The application provides a transient stability analysis method, device, equipment and medium of a new energy grid-connected system, which are used for solving the problems that the influence of the interaction of output currents of multiple power electronic equipment on the transient stability is not considered in the prior art, the transient stability performance cannot be analyzed and improved through multiple machine grid connection, and the like.
An embodiment of a first aspect of the present application provides a transient stability analysis method for a new energy grid-connected system, including the following steps: constructing a fault front power angle function model and a fault back power angle function model of a new energy grid-connected single machine infinite system adopting droop control; drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model; and analyzing transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve.
Optionally, in one embodiment of the present application, the drawing the pre-fault angle characteristic curve and the post-fault angle characteristic curve based on the pre-fault angle function model and the post-fault angle function model includes: judging whether the output current of each inverter in the new energy grid-connected single machine infinite system is smaller than a preset protection threshold value, if so, equivalent each inverter to a controlled voltage source, and constructing a first inverter grid-connected system equivalent model; based on the equivalent model of the first inverter grid-connected system, acquiring an inverter outlet voltage phase and an alternating current bus voltage phase, and calculating a first power angle and first output power of the inverter according to the inverter outlet voltage phase and the alternating current bus voltage phase; and drawing the characteristic curve of the pre-fault angle according to the first power angle and the first output power of each inverter.
Optionally, in one embodiment of the present application, the drawing the pre-fault angle characteristic curve and the post-fault angle characteristic curve based on the pre-fault angle function model and the post-fault angle function model further includes: if the output current of each inverter is greater than or equal to the preset protection threshold, each inverter is equivalent to a current source mode, and a second inverter grid-connected system equivalent model is built; acquiring output current of each inverter based on the equivalent model of the second inverter grid-connected system, and calculating a second power angle and second output power of each inverter according to the output current of each inverter; and drawing the post-fault indicator angle characteristic curve according to the second power angle and the second output power of each inverter.
Optionally, in an embodiment of the present application, the analyzing transient stability performance of the stand-alone infinity system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve includes: calculating a limit cut angle of each inverter based on a preset power reference value and the post-fault indicator angle characteristic curve; comparing the limit cutting angle with the second power angle to obtain a comparison result; if the comparison result is that the second power angle is smaller than the limit cutting angle, the new energy grid-connected single machine infinite system is in a transient state; and if the comparison result shows that the second power angle is larger than or equal to the limit cutting angle, the new energy grid-connected single machine infinite system is in a transient state unstability state.
Optionally, in an embodiment of the present application, the analyzing the transient stability performance of the stand-alone infinity system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve further includes: after the output current of each inverter is collected, determining a collected total current value of all inverters based on the phase of the output current of each inverter; when the phases of the output currents of the inverters are consistent, the total current value is the largest, and the transient stability performance of the new energy grid-connected single machine infinite system is the best; when the phases of the output currents of the inverters are opposite, the total current value is the smallest, and the transient stability performance of the new energy grid-connected single machine infinite system is the worst.
An embodiment of a second aspect of the present application provides a transient stability analysis device of a new energy grid-connected system, including: the modeling module is used for constructing a pre-fault power angle function model and a post-fault power angle function model of a new energy grid-connected single machine infinite system adopting droop control; the drawing module is used for drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model; and the analysis module is used for analyzing the transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve.
Optionally, in one embodiment of the present application, the drawing module includes: the judging unit is used for judging whether the output current of each inverter in the new energy grid-connected single-machine infinite system is smaller than a preset protection threshold value, if the output current of each inverter is smaller than the preset protection threshold value, the each inverter is equivalent to a controlled voltage source, and an equivalent model of a first inverter grid-connected system is built; the first calculating unit is used for acquiring an inverter outlet voltage phase and an alternating current bus voltage phase based on the equivalent model of the first inverter grid-connected system, and calculating a first power angle and first output power of the inverter according to the inverter outlet voltage phase and the alternating current bus voltage phase; and the first drawing unit is used for drawing the characteristic curve of the pre-fault angle according to the first power angle and the first output power of each inverter.
Optionally, in one embodiment of the present application, the drawing module further includes: the equivalent unit is used for equivalent each inverter to a current source mode and constructing a second inverter grid-connected system equivalent model if the output current of each inverter is greater than or equal to the preset protection threshold value; the second calculating unit is used for obtaining the output current of each inverter based on the equivalent model of the second inverter grid-connected system and calculating a second power angle and second output power of each inverter according to the output current of each inverter; and the second drawing unit is used for drawing the post-fault indicator angle characteristic curve according to the second power angle and the second output power of each inverter.
Optionally, in one embodiment of the present application, the analysis module includes: a third calculation unit for calculating a limit cut angle of each inverter based on a preset power reference value and the post-fault indicator characteristic curve; the comparison unit is used for comparing the limit cutting angle with the second power angle to obtain a comparison result; the stabilizing unit is used for enabling the new energy grid-connected single machine infinite system to be in a transient stable state if the comparison result is that the second power angle is smaller than the limit cutting angle; and the destabilizing unit is used for enabling the new energy grid-connected single machine infinite system to be in a transient destabilizing state if the comparison result is that the second power angle is larger than or equal to the limit cutting angle.
Optionally, in one embodiment of the present application, the analysis module further includes: a determining unit configured to determine, after the output currents of the inverters are collected, a collected total current value of all the inverters based on a phase of the output current of the inverters; the optimal unit is used for maximizing the total current value when the phases of the output currents of the inverters are consistent, and optimizing the transient stability of the new energy grid-connected single machine infinite system; and the worst unit is used for minimizing the total current value when the phases of the output currents of the inverters are opposite, and the transient stability performance of the new energy grid-connected single machine infinite system is worst.
An embodiment of a third aspect of the present application provides an electronic device, including: the system comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the program to realize the transient stability analysis method of the new energy grid-connected system.
An embodiment of the fourth aspect of the present application provides a computer readable storage medium storing a computer program which, when executed by a processor, implements the method for transient stability analysis of a new energy grid-connected system as above.
Thus, embodiments of the present application have the following beneficial effects:
the embodiment of the application can be used for constructing a pre-fault power angle function model and a post-fault power angle function model of a new energy grid-connected single machine infinite system by adopting droop control; drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model; and analyzing transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve. According to the application, the sag control new energy grid-connected single machine infinite system fault pre-fault and post-fault power angle function models are established, and the pre-fault and post-fault power angle characteristic curves are drawn, so that the interaction of multiple machine output currents is utilized to analyze the transient stability performance of the system, thereby having a guiding effect on the aspect of maintaining stable operation of the new energy centralized grid-connected system under large disturbance, and providing a reliable scheme for safe operation control design. Therefore, the problems that the influence of the interaction of the output currents of the multiple power electronic devices on the transient stability is not considered, the transient stability performance cannot be analyzed and improved through multiple machine grid connection and the like in the prior art are solved.
Additional aspects and advantages of the application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the application.
Drawings
The foregoing and/or additional aspects and advantages of the application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
fig. 1 is a flowchart of a transient stability analysis method of a new energy grid-connected system according to an embodiment of the present application;
fig. 2 (a) is a schematic logic architecture diagram of a transient stability analysis method of a new energy grid-connected system according to an embodiment of the present application;
FIG. 2 (b) is a schematic diagram of a droop control active control loop according to an embodiment of the present application;
FIG. 2 (c) is a schematic diagram of a droop control reactive control loop according to an embodiment of the present application;
FIG. 3 is a schematic diagram of an equivalent model of a new energy grid-connected system based on droop control when current is not limited according to an embodiment of the present application;
FIG. 4 is a graph of the characteristic of the power angle of an current without clipping according to one embodiment of the application;
fig. 5 is a schematic diagram of a grid-connected equivalent model of a current clipping droop control inverter according to an embodiment of the present application;
FIG. 6 is a schematic diagram of transient dynamic characteristics of a power angle according to an embodiment of the present application;
FIG. 7 (a) is an equivalent topology diagram of a multi-machine grid-connected system according to an embodiment of the present application;
FIG. 7 (b) is a schematic diagram of current vector superposition of a multi-machine grid-connected system according to an embodiment of the present application;
FIG. 8 is an exemplary diagram of a transient stability analysis device of a new energy grid-connected system according to an embodiment of the present application;
fig. 9 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
The system comprises a transient stability analysis device of a 10-new energy grid-connected system, a 100-modeling module, a 200-drawing module, a 300-analysis module, a 901-memory, a 902-processor and a 903-communication interface.
Detailed Description
Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present application and should not be construed as limiting the application.
The transient stability analysis method, device, equipment and medium of the new energy grid-connected system in the embodiment of the application are described below with reference to the accompanying drawings. Aiming at the problems in the background art, the application provides a transient stability analysis method of a new energy grid-connected system, wherein in the method, a pre-fault power angle function model and a post-fault power angle function model of a new energy grid-connected single machine infinite system adopting droop control are constructed; drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model; and analyzing transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve. According to the application, the sag control new energy grid-connected single machine infinite system fault pre-fault and post-fault power angle function models are established, and the pre-fault and post-fault power angle characteristic curves are drawn, so that the interaction of multiple machine output currents is utilized to analyze the transient stability performance of the system, thereby having a guiding effect on the aspect of maintaining stable operation of the new energy centralized grid-connected system under large disturbance, and providing a reliable scheme for safe operation control design. Therefore, the problems that the influence of the interaction of the output currents of the multiple power electronic devices on the transient stability is not considered, the transient stability performance cannot be analyzed and improved through multiple machine grid connection and the like in the prior art are solved.
Specifically, fig. 1 is a flowchart of a transient stability analysis method of a new energy grid-connected system provided by an embodiment of the present application.
As shown in fig. 1, the transient stability analysis method of the new energy grid-connected system comprises the following steps:
in step S101, a pre-fault power angle function model and a post-fault power angle function model of a new energy grid-connected single machine infinity system adopting droop control are constructed.
In step S102, a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve are drawn based on the pre-fault power angle function model and the post-fault power angle function model.
In the embodiment of the application, the power angle function models before and after the fault can be constructed for the new energy grid-connected single machine infinite system adopting droop control, and then the power angle characteristic curves before and after the fault are respectively drawn according to the constructed power angle function models before and after the fault, so that guidance and basis are provided for transient stability analysis of the new energy grid-connected system.
Optionally, in one embodiment of the present application, drawing the pre-fault and post-fault power angle characteristic curves based on the pre-fault and post-fault power angle function models includes: judging whether the output current of each inverter in the new energy grid-connected single machine infinite system is smaller than a preset protection threshold value, if so, equivalent each inverter to a controlled voltage source, and constructing an equivalent model of a first inverter grid-connected system; based on a first inverter grid-connected system equivalent model, acquiring an inverter outlet voltage phase and an alternating current bus voltage phase, and calculating a first power angle and first output power of the inverter according to the inverter outlet voltage phase and the alternating current bus voltage phase; and drawing a characteristic curve of the pre-fault angle according to the first power angle and the first output power of each inverter.
It should be noted that, the embodiment of the application can draw the fault pre-work angle characteristic curve of the new energy grid-connected single-machine infinite system by using the fault pre-work angle function model of the new energy grid-connected single-machine infinite system.
Specifically, in the embodiment of the application, a new energy grid-connected single machine infinite system adopting droop control is shown in fig. 2 (a), fig. 2 (b) and fig. 2 (c), wherein the inner loop control comprises a voltage outer loop and a current inner loop, and the time scale is far smaller than that of a power loop, so that the embodiment of the application ignores the influence of dynamic characteristics of the inner loop control on transient stability and only considers the influence of the dynamic of the power outer loop on the transient stability.
When the new energy grid-connected single machine infinite system is in a normal running state, namely before large disturbance occurs, the amplitude of the output current of the inverter is near a reference value and cannot exceed a set saturation threshold, namely, the threshold is not 'top limit'; at this time, the inverter can be equivalently used as a controlled voltage source, the phase and amplitude of the inverter are obtained by p-f and Q-V droop characteristics, and if the inner loop control dynamics are ignored, an equivalent model of the inverter grid-connected system can be constructed, and the model is shown in fig. 3.
Transient stability of an inverter is defined as the ability to remain synchronized with the grid when the inverter is subject to large disturbances such as voltage dips, particularly where the power angle of the inverter can be restored to the original equilibrium state or transitioned to a new stable equilibrium point after the transient process, where the power angle is defined herein as the difference δ between the inverter outlet voltage phase θ and the ac bus voltage phase, where the power angle δ satisfies the following equation:
Wherein θ g For the phase of the ac bus voltage, k p For the active sag factor, P ref And P is the active power output by the inverter for the active reference value.
When the output current does not exceed the limit, the inverter output active power may be expressed as:
wherein E is the outlet voltage of the inverter, X is the inductance of the AC transmission line, delta is the phase difference between the outlet voltage of the inverter and the AC system voltage, i.e. the power angle, V g Is equivalent voltage of an alternating current system, P m Is the output power amplitude.
Therefore, the pre-fault angle characteristic is shown in FIG. 4, wherein point a is the steady-state operating point, at which the output power P is equal to the reference value P ref Equal, the system keeps stable, and the power angle is stabilized at delta a And (5) a dot.
Therefore, the embodiment of the application draws the pre-fault power angle characteristic curve of the new energy grid-connected single infinite system based on the pre-fault power angle function model of the new energy grid-connected single infinite system, thereby providing theoretical support for drawing the post-fault power angle characteristic curve and analyzing the transient stability of the new energy grid-connected system.
Optionally, in an embodiment of the present application, drawing the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model further includes: if the output current of each inverter is greater than or equal to a preset protection threshold value, each inverter is equivalent to a current source mode, and an equivalent model of a second inverter grid-connected system is built; acquiring output current of each inverter based on an equivalent model of a second inverter grid-connected system, and calculating a second power angle and second output power of each inverter according to the output current of each inverter; and drawing a fault post-work angle characteristic curve according to the second power angle and the second output power of each inverter.
In addition, the embodiment of the application can also draw the post-fault power angle characteristic curve of the new energy grid-connected single infinite system by utilizing the post-fault power angle function model of the new energy grid-connected single infinite system.
Specifically, when a fault occurs, the system voltage drops greatly, the inverter output current exceeds the set protection threshold value and is "top limit", at this time, the inverter can be equivalent to a current source mode, and constant current is output, so that an equivalent model of the second inverter grid-connected system can be obtained, and the equivalent model is shown in fig. 5.
During the current clipping phase, the inverter output current is represented by the following equation:
P＝V g I max cosδ＝V g I max sin(δ+90°)＝P s sin(δ+90°) (3)
wherein I is max Represents the maximum value after the output current is limited, P s And the amplitude of the output power after the amplitude limiting of the output current is obtained.
Therefore, the embodiment of the application can draw the post-fault power angle characteristic curve, as shown in the solid line curve of fig. 6, wherein the dotted line curve is the power angle characteristic curve when the current is not limited, and the dash-dot line curve is the power angle characteristic curve in the current limiting state after the fault recovery.
Therefore, the embodiment of the application further improves the data basis and the reliability of subsequent analysis with powerful guarantee for analyzing the transient stability performance of the single-machine infinite system and the multi-machine grid-connected system by drawing the fault post-work angle characteristic curve.
In step S103, transient stability performance of the stand-alone infinity system and the multi-machine grid-connected system is analyzed according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve.
After the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve are drawn, the embodiment of the application can further analyze transient stability criteria of a single-machine infinite system and a multi-machine grid-connected system, thereby obtaining accurate and reliable analysis results and having a guiding effect on the aspect of keeping stable operation of the new energy centralized grid-connected system under large disturbance.
Optionally, in one embodiment of the present application, analyzing transient stability performance of the stand-alone infinity system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve includes: calculating a limit cut angle of each inverter based on a preset power reference value and a fault-following power angle characteristic curve; comparing the limit cutting angle with the second power angle to obtain a comparison result; if the comparison result shows that the second power angle is smaller than the limit cutting angle, the new energy grid-connected single machine infinite system is in a transient stable state; if the comparison result is that the second power angle is larger than or equal to the limit cutting angle, the new energy grid-connected single machine infinite system is in a transient state unstability state.
It should be noted that in the embodiment of the present application, the transient stability criterion analysis of the stand-alone infinite system may be performed first according to the pre-fault angle characteristic curve and the post-fault angle characteristic curve.
Specifically, as can be seen from fig. 6, p=p when the stand-alone infinity system is operating normally ref The operating point is at point a. When the single machine infinite system fails, the current increases and limits amplitude, the operation point transits from the point a to the point a', and at the moment, P ref >P, the power angle delta increases, the operation point transits from a ' to b ', if the fault is recovered, the voltage amplitude increases, the power angle characteristic curve becomes a dot-dash curve, as shown in FIG. 6, the b ' operation point transits to b point on the dot-dash curve, P ref <And P is that the power angle delta is reduced, the point b is transited to the point c, and then the point a is restored to the point a balance point, and the single machine infinite system is restored to be stable.
However, the fault does not recover when the operating point is at point b ', point b' continues to transition to point d ', and if the fault recovers at this time, point d' transitions to point d; at this time because of P ref >And P, the power angle delta is increased continuously, so that the single machine infinite system is unstable.
In conclusion, fault recoveryThere is again a limit cut angle delta max The following formula is shown:
power angle delta when fault is recovered <δ max The single machine infinite system can be judged to meet the transient stability condition; when delta>δ max The transient instability of the stand-alone infinite system can be determined. Thus, the limit cut angle delta is increased max The transient stability margin of a stand-alone infinite system can be improved.
Optionally, in an embodiment of the present application, the analyzing the transient stability performance of the stand-alone infinity system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve further includes: after the output currents of the inverters are collected, determining a collected total current value of all the inverters based on the phase of the output current of each inverter; when the phases of the output currents of the inverters are consistent, the total current value is the largest, and the transient stability performance of the new energy grid-connected single machine infinite system is optimal; when the phases of the output currents of the inverters are opposite, the total current value is minimum, and the transient stability performance of the new energy grid-connected single machine infinite system is worst.
Furthermore, the embodiment of the application can also analyze the transient stability characteristics of the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve.
Specifically, as can be seen from formula (4), δ max And an active reference value P ref And power value P at current clipping s In relation to, without changing P ref On the premise of (1), P is increased s The limit cutting angle delta can be increased max Thereby improving the transient stability margin.
Further, in a multiple-inverter output current I in a multiple-machine grid-connected system max After the current is gathered, when the current phases are consistent, the total current after the gathering is maximum, at the moment P s Maximum; when the phase difference of the output currents of the inverters is 180 DEG, the total current is minimum, at the moment P s Minimum, system transient stabilityThe fixed performance is the worst.
As shown in fig. 7 (a), the equivalent schematic diagram of the multi-machine grid connection is that the respective current phases are determined by the active sagging characteristics of the respective collector lines, so that the current synthesis vector at the PCC point is the superposition of the respective current vectors, and the superposition rule is that, as shown in fig. 7 (b), when the respective inverter output ac current phases are identical, the busbar output current I is collected as shown in fig. 7 (b) sum The amplitude reaches the maximum value, at this time P s Maximum, limit cut angle delta is known from formula (4) max The maximum transient stability margin of the multi-machine grid-connected system is the maximum; when theta is as 1 、θ 2 When the equiphase settings are improper, even 180 degrees different from each other, the current I is collected sum The amplitude is minimum, and the transient stability performance of the multi-machine grid-connected system is worst, so that the occurrence of the situation is avoided to the greatest extent.
It can be understood that the transient stability analysis strategy based on the limit cutting angle in the embodiment of the application has clear and simple logic, is easy to understand, can be popularized to the multi-machine coordination control with/without communication so as to improve the transient stability characteristic, and has important guiding and reference significance for future practical engineering.
The following will describe the execution logic of the transient stability analysis method of the new energy grid-connected system according to the present application by a specific embodiment.
In a specific embodiment of the application, taking a photovoltaic power plant with two current collecting lines as an example, the influence of direct current side dynamics on the overall transient stability is ignored, and the transient stability of a photovoltaic power generation grid-connected system adopting droop control is analyzed to illustrate the effectiveness of a method for analyzing the transient stability of a new energy grid-connected system considering multi-machine interaction, wherein the specific steps for analyzing the transient stability of the photovoltaic power generation grid-connected system adopting droop control in the specific embodiment are as follows:
step 1, a new energy grid-connected model considering multi-machine interaction is established:
establishing a multi-machine grid-connected model based on droop control, designing a maximum allowable current output value of each inverter during a fault period, and judging the influence of the phase difference of the output current of the inverter on stability; in a specific embodiment, assuming that the maximum value of the output currents of the two inverters is 1.5p.u., the amplitude of the current sent out by the collecting bus is 3p.u. when the phases are consistent; if the current phase is different by 30 degrees, the current amplitude sent out by the collecting bus is 2.8p.u.;
Step 2, drawing a characteristic curve of the angle of work before and during the fault and after the fault of the new energy grid-connected single machine infinite system:
constructing a single machine infinity equivalent model of the multi-machine grid-connected system, drawing a power angle characteristic curve according to the voltage of a machine end before a fault and the voltage of the system, drawing the power angle characteristic curve during the fault by limiting current and the voltage of the system during the fault, drawing a power angle curve after the fault by limiting current and the voltage of the system after the fault is recovered, analyzing transient stability according to the track of an operating point, and recording the power angle value during fault removal; in a specific embodiment, the design fault depth reaches 0.5p.u., the fault duration is 0.7s, such that the fault cut angle reaches 1.22rad;
step 3, a transient stability analysis criterion of the new energy grid-connected system considering multi-machine interaction is calculated:
when the phases of the multiple output currents are consistent, calculating a fault limit removal angle of the grid-connected system, comparing the fault limit removal angle measured in the step 2 with the limit value, and judging that the transient state of the system is stable when the fault removal angle is smaller than the limit value; when the fault angle is larger than the limit value, judging that the system is unstable; in a specific embodiment, the fault-limited current is 3p.u., the system rated voltage is 380V, the reference power is 10kW, and the calculated limit cut angle is 1.23rad; step 2 shows that the fault removal angle is 1.22rad and is smaller than the limit removal angle, and the system meets the transient stability;
Step 4, analyzing transient stability of the grid-connected system adopting the traditional droop control:
as a comparison with the transient stability of the step 3, aiming at a multi-machine grid-connected system adopting the traditional droop control, measuring the output current during the fault period of the alternating current collecting bus, calculating the system limit cutting angle under the traditional droop control method, recording the power angle value during fault cutting, and comparing with the limit power angle to judge the stability; in a specific embodiment, according to the step 1, the fault limiting current is known to be 2.8p.u., other electrical parameters are the same as those of the step 3, and the limit cutting angle is calculated to be 1.20rad, at this time, the fault cutting angle is 1.22rad and is larger than the limit cutting angle, so that it is determined that the grid-connected system in the conventional control mode is in a transient unstable state.
According to the transient stability analysis method of the new energy grid-connected system, which is provided by the embodiment of the application, a pre-fault power angle function model and a post-fault power angle function model of a new energy grid-connected single machine infinite system adopting droop control are constructed; drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model; and analyzing transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve. According to the application, the sag control new energy grid-connected single machine infinite system fault pre-fault and post-fault power angle function models are established, and the pre-fault and post-fault power angle characteristic curves are drawn, so that the interaction of multiple machine output currents is utilized to analyze the transient stability performance of the system, thereby having a guiding effect on the aspect of maintaining stable operation of the new energy centralized grid-connected system under large disturbance, and providing a reliable scheme for safe operation control design.
Next, a transient stability analysis device of the new energy grid-connected system according to the embodiment of the present application is described with reference to the accompanying drawings.
Fig. 8 is a schematic block diagram of a transient stability analysis device of the new energy grid-connected system according to an embodiment of the present application.
As shown in fig. 8, the transient stability analysis device 10 of the new energy grid-connected system includes: modeling module 100, rendering module 200, and analysis module 300.
The modeling module 100 is configured to construct a pre-fault power angle function model and a post-fault power angle function model of a new energy grid-connected single machine infinite system adopting droop control.
And the drawing module 200 is used for drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model.
And the analysis module 300 is used for analyzing the transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve.
Optionally, in one embodiment of the present application, the drawing module 200 includes: the device comprises a judging unit, a first calculating unit and a first drawing unit.
The judging unit is used for judging whether the output current of each inverter in the new energy grid-connected single-machine infinite system is smaller than a preset protection threshold value, if the output current of each inverter is smaller than the preset protection threshold value, the each inverter is equivalent to a controlled voltage source, and an equivalent model of the first inverter grid-connected system is built.
The first calculating unit is used for obtaining the phase of the outlet voltage of the inverter and the phase of the alternating current bus voltage based on the equivalent model of the grid-connected system of the first inverter, and calculating the first power angle and the first output power of the inverter according to the phase of the outlet voltage of the inverter and the phase of the alternating current bus voltage.
And the first drawing unit is used for drawing a characteristic curve of the work angle before the fault according to the first power angle and the first output power of each inverter.
Optionally, in one embodiment of the present application, the drawing module 200 further includes: an equivalent unit, a second calculation unit and a second drawing unit.
The equivalent unit is used for equivalent each inverter to a current source mode and constructing a second inverter grid-connected system equivalent model if the output current of each inverter is greater than or equal to a preset protection threshold value;
the second calculation unit is used for obtaining the output current of each inverter based on the equivalent model of the second inverter grid-connected system and calculating the second power angle and the second output power of each inverter according to the output current of each inverter;
and the second drawing unit is used for drawing a post-fault indicator angle characteristic curve according to the second power angle and the second output power of each inverter.
Alternatively, in one embodiment of the application, the analysis module 300 includes: the device comprises a third calculation unit, a comparison unit, a stabilization unit and a destabilization unit.
And a third calculation unit for calculating a limit cut angle of each inverter based on the preset power reference value and the post-fault power angle characteristic curve.
And the comparison unit is used for comparing the limit cutting angle with the second power angle to obtain a comparison result.
And the stabilizing unit is used for enabling the new energy grid-connected single machine infinite system to be in a transient stable state if the comparison result is that the second power angle is smaller than the limit cutting angle.
And the destabilizing unit is used for enabling the new energy grid-connected single machine infinite system to be in a transient destabilizing state if the comparison result is that the second power angle is larger than or equal to the limit cutting angle.
Optionally, in one embodiment of the present application, the analysis module 300 further includes: a determining unit, an optimizing unit and a worst unit.
And the determining unit is used for determining the total current value of all the inverters based on the phase of the output current of each inverter after the output current of each inverter is converged.
And the optimal unit is used for maximizing the total current value when the phases of the output currents of the inverters are consistent, and optimizing the transient stability performance of the new energy grid-connected single machine infinite system.
And the worst unit is used for minimizing the total current value when the phases of the output currents of the inverters are opposite, and the transient stability performance of the new energy grid-connected single machine infinite system is worst.
It should be noted that the foregoing explanation of the embodiment of the transient stability analysis method of the new energy grid-connected system is also applicable to the transient stability analysis device of the new energy grid-connected system of the embodiment, and is not repeated herein.
The transient stability analysis device of the new energy grid-connected system provided by the embodiment of the application comprises a modeling module, a fault pre-power angle function model and a fault post-power angle function model, wherein the modeling module is used for constructing a new energy grid-connected single machine infinite system adopting droop control; the drawing module is used for drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model; and the analysis module is used for analyzing the transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve. According to the application, the sag control new energy grid-connected single machine infinite system fault pre-fault and post-fault power angle function models are established, and the pre-fault and post-fault power angle characteristic curves are drawn, so that the interaction of multiple machine output currents is utilized to analyze the transient stability performance of the system, thereby having a guiding effect on the aspect of maintaining stable operation of the new energy centralized grid-connected system under large disturbance, and providing a reliable scheme for safe operation control design.
Fig. 9 is a schematic structural diagram of an electronic device according to an embodiment of the present application. The electronic device may include:
memory 901, processor 902, and a computer program stored on memory 901 and executable on processor 902.
The processor 902 implements the transient stability analysis method of the new energy grid-connected system provided in the above embodiment when executing the program.
Further, the electronic device further includes:
a communication interface 903 for communication between the memory 901 and the processor 902.
Memory 901 for storing a computer program executable on processor 902.
Memory 901 may comprise high-speed RAM memory or may also include non-volatile memory (non-volatile memory), such as at least one disk memory.
If the memory 901, the processor 902, and the communication interface 903 are implemented independently, the communication interface 903, the memory 901, and the processor 902 may be connected to each other through a bus and perform communication with each other. The bus may be an industry standard architecture (Industry Standard Architecture, abbreviated ISA) bus, an external device interconnect (Peripheral Component, abbreviated PCI) bus, or an extended industry standard architecture (Extended Industry Standard Architecture, abbreviated EISA) bus, among others. The buses may be divided into address buses, data buses, control buses, etc. For ease of illustration, only one thick line is shown in fig. 9, but not only one bus or one type of bus.
Alternatively, in a specific implementation, if the memory 901, the processor 902, and the communication interface 903 are integrated on a chip, the memory 901, the processor 902, and the communication interface 903 may communicate with each other through internal interfaces.
The processor 902 may be a central processing unit (Central Processing Unit, abbreviated as CPU) or an application specific integrated circuit (Application Specific Integrated Circuit, abbreviated as ASIC) or one or more integrated circuits configured to implement embodiments of the present application.
The embodiment of the application also provides a computer readable storage medium, on which a computer program is stored, which when being executed by a processor, realizes the transient stability analysis method of the new energy grid-connected system.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or N embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, "N" means at least two, for example, two, three, etc., unless specifically defined otherwise.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and additional implementations are included within the scope of the preferred embodiment of the present application in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order from that shown or discussed, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the embodiments of the present application.
Logic and/or steps represented in the flowcharts or otherwise described herein, e.g., a ordered listing of executable instructions for implementing logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or N wires, a portable computer cartridge (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer readable medium may even be paper or other suitable medium on which the program is printed, as the program may be electronically captured, via optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It is to be understood that portions of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the N steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, may be implemented using any one or combination of the following techniques, as known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.
Those of ordinary skill in the art will appreciate that all or a portion of the steps carried out in the method of the above-described embodiments may be implemented by a program to instruct related hardware, where the program may be stored in a computer readable storage medium, and where the program, when executed, includes one or a combination of the steps of the method embodiments.
In addition, each functional unit in the embodiments of the present application may be integrated in one processing module, or each unit may exist alone physically, or two or more units may be integrated in one module. The integrated modules may be implemented in hardware or in software functional modules. The integrated modules may also be stored in a computer readable storage medium if implemented in the form of software functional modules and sold or used as a stand-alone product.
The above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, or the like. While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the application, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the application.

Claims (12)

1. The transient stability analysis method of the new energy grid-connected system is characterized by comprising the following steps of:
constructing a fault front power angle function model and a fault back power angle function model of a new energy grid-connected single machine infinite system adopting droop control;
drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model;
and analyzing transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve.
2. The method of claim 1, wherein the plotting a pre-fault and post-fault power angle characteristic based on the pre-fault and post-fault power angle function models comprises:
Judging whether the output current of each inverter in the new energy grid-connected single machine infinite system is smaller than a preset protection threshold value, if so, equivalent each inverter to a controlled voltage source, and constructing a first inverter grid-connected system equivalent model;
based on the equivalent model of the first inverter grid-connected system, acquiring an inverter outlet voltage phase and an alternating current bus voltage phase, and calculating a first power angle and first output power of the inverter according to the inverter outlet voltage phase and the alternating current bus voltage phase;
and drawing the characteristic curve of the pre-fault angle according to the first power angle and the first output power of each inverter.
3. The method of claim 2, wherein the plotting a pre-fault and post-fault power angle characteristic based on the pre-fault and post-fault power angle function models further comprises:
if the output current of each inverter is greater than or equal to the preset protection threshold, each inverter is equivalent to a current source mode, and a second inverter grid-connected system equivalent model is built;
Acquiring output current of each inverter based on the equivalent model of the second inverter grid-connected system, and calculating a second power angle and second output power of each inverter according to the output current of each inverter;
and drawing the post-fault indicator angle characteristic curve according to the second power angle and the second output power of each inverter.
4. The method of claim 3, wherein analyzing transient stability performance of the stand-alone infinity system and the multi-machine grid-connected system based on the pre-fault and post-fault power angle characteristics comprises:
calculating a limit cut angle of each inverter based on a preset power reference value and the post-fault indicator angle characteristic curve;
comparing the limit cutting angle with the second power angle to obtain a comparison result;
if the comparison result is that the second power angle is smaller than the limit cutting angle, the new energy grid-connected single machine infinite system is in a transient state;
and if the comparison result shows that the second power angle is larger than or equal to the limit cutting angle, the new energy grid-connected single machine infinite system is in a transient state unstability state.
5. The method of claim 4, wherein analyzing transient stability performance of a stand-alone infinity system and a multi-machine grid-connected system based on the pre-fault and post-fault power angle characteristics, further comprises:
after the output current of each inverter is collected, determining a collected total current value of all inverters based on the phase of the output current of each inverter;
when the phases of the output currents of the inverters are consistent, the total current value is the largest, and the transient stability performance of the new energy grid-connected single machine infinite system is the best;
when the phases of the output currents of the inverters are opposite, the total current value is the smallest, and the transient stability performance of the new energy grid-connected single machine infinite system is the worst.
6. The transient stability analysis device of the new energy grid-connected system is characterized by comprising the following components:
the modeling module is used for constructing a pre-fault power angle function model and a post-fault power angle function model of a new energy grid-connected single machine infinite system adopting droop control;
the drawing module is used for drawing a pre-fault power angle characteristic curve and a post-fault power angle characteristic curve based on the pre-fault power angle function model and the post-fault power angle function model;
And the analysis module is used for analyzing the transient stability performance of the single-machine infinite system and the multi-machine grid-connected system according to the pre-fault power angle characteristic curve and the post-fault power angle characteristic curve.
7. The apparatus of claim 6, wherein the rendering module comprises:
the judging unit is used for judging whether the output current of each inverter in the new energy grid-connected single-machine infinite system is smaller than a preset protection threshold value, if the output current of each inverter is smaller than the preset protection threshold value, the each inverter is equivalent to a controlled voltage source, and an equivalent model of a first inverter grid-connected system is built;
the first calculating unit is used for acquiring an inverter outlet voltage phase and an alternating current bus voltage phase based on the equivalent model of the first inverter grid-connected system, and calculating a first power angle and first output power of the inverter according to the inverter outlet voltage phase and the alternating current bus voltage phase;
and the first drawing unit is used for drawing the characteristic curve of the pre-fault angle according to the first power angle and the first output power of each inverter.
8. The apparatus of claim 7, wherein the rendering module further comprises:
The equivalent unit is used for equivalent each inverter to a current source mode and constructing a second inverter grid-connected system equivalent model if the output current of each inverter is greater than or equal to the preset protection threshold value;
the second calculating unit is used for obtaining the output current of each inverter based on the equivalent model of the second inverter grid-connected system and calculating a second power angle and second output power of each inverter according to the output current of each inverter;
and the second drawing unit is used for drawing the post-fault indicator angle characteristic curve according to the second power angle and the second output power of each inverter.
9. The apparatus of claim 8, wherein the analysis module comprises:
a third calculation unit for calculating a limit cut angle of each inverter based on a preset power reference value and the post-fault indicator characteristic curve;
the comparison unit is used for comparing the limit cutting angle with the second power angle to obtain a comparison result;
the stabilizing unit is used for enabling the new energy grid-connected single machine infinite system to be in a transient stable state if the comparison result is that the second power angle is smaller than the limit cutting angle;
And the destabilizing unit is used for enabling the new energy grid-connected single machine infinite system to be in a transient destabilizing state if the comparison result is that the second power angle is larger than or equal to the limit cutting angle.
10. The apparatus of claim 9, wherein the analysis module further comprises:
a determining unit configured to determine, after the output currents of the inverters are collected, a collected total current value of all the inverters based on a phase of the output current of the inverters;
the optimal unit is used for maximizing the total current value when the phases of the output currents of the inverters are consistent, and optimizing the transient stability of the new energy grid-connected single machine infinite system;
and the worst unit is used for minimizing the total current value when the phases of the output currents of the inverters are opposite, and the transient stability performance of the new energy grid-connected single machine infinite system is worst.
11. An electronic device, comprising: a memory, a processor and a computer program stored on the memory and executable on the processor, the processor executing the program to implement the method for transient stability analysis of a new energy grid-connected system as claimed in any one of claims 1-5.
12. A computer-readable storage medium having stored thereon a computer program, wherein the program is executed by a processor for implementing the transient stability analysis method of the new energy grid-tie system of any one of claims 1 to 5.
CN202310994584.8A 2023-08-07 2023-08-07 Transient stability analysis method, device, equipment and medium of new energy grid-connected system Pending CN116882115A (en)

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