Modeling and transient stability analysis method for grid-connected new energy unit

Abstract

The invention discloses a modeling and transient stability analysis method for a grid-connected new energy unit. The modeling method comprises the following steps: establishing a nonlinear full-order model of a grid-connected new energy unit system by adopting a state space modeling method, performing order reduction processing on the established nonlinear full-order model, and performing linearization processing on a nonlinear part; according to the system transient synchronization stability analysis method, the problem of constructing the maximum estimation attraction domain of the system is converted into the problem of solving optimization, and the maximum estimation attraction domain of the system is solved by adopting an LMI optimization theory. The influence of a phase-locked loop and a current loop of the system is fully considered when the full-order model is constructed, order reduction processing and linearization processing are performed on the full-order model, the obtained simplified model can accurately simulate the original full-order model, and the difficulty of subsequent transient stability analysis is reduced; an LMI optimization method is adopted to solve the maximum estimation attraction domain of the system, and the constructed maximum estimation attraction domain can accurately reflect the transient stability boundary of the system and is low in conservative property.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy grid-connected and microgrid, and in particular to a method for analyzing the synchronization stability of a grid-connected new energy inverter. Background Art

[0002] With the continuous growth of global energy demand and the improvement of environmental protection awareness, the development and utilization of renewable energy has become an important way to achieve sustainable development. In recent years, new energy technologies such as solar energy and wind energy have developed rapidly and gradually replaced traditional fossil energy to become an important part of the power system; however, due to the intermittent and volatile nature of its energy source, the grid connection of new energy has brought new challenges to the stable operation of the power system. While providing clean electricity, new energy generation has also caused pressure on the stability and power quality of the power grid, making the operating characteristics of the power system more complex.

[0003] In this context, transient stability analysis of grid-connected inverters for new energy sources is particularly necessary. In grid-connected new energy generating units, the inverter is the core device for converting DC to AC, and its transient stability is directly related to the safe operation of the power grid. In particular, with the continuous increase in the installed capacity of new energy sources, the power grid will become weaker and weaker, and the stability problems caused by the interaction between the grid-connected inverter and the power grid under weak power grid conditions are more prominent. Therefore, constructing an accurate model of grid-connected inverters for new energy sources under weak power grids and analyzing their transient stability problems have become the focus of current research.

[0004] At present, there are many academic papers and patents at home and abroad that study the modeling of new energy grid-connected inverters and their synchronous stability analysis, and propose solutions, such as:

[0005] 1. B. Wen et al. applied the impedance measurement method to the AC system and established an impedance model of the grid-connected inverter in the dq coordinate system, which can easily and conveniently analyze and predict the stability of the system, but did not consider the impact of the phase-locked loop.

[0006] 2. Based on the quadratic principle, Li Xilin et al. constructed a quadratic Lyapunov function to analyze the transient stability of the isolated island microgrid system, estimated the power angle stability boundary under different forms of disturbances, and explored the sensitivity of the isolated island microgrid to different forms of disturbances. However, this study only focused on the phase-locked loop system and did not consider the current loop control.

[0007] 3. Goksu O et al. used the Lyapunov function method to analyze the global stability of renewable energy units under different grid impedances. Although the Lyapunov function method is universal, as the system order increases, not only is it difficult to obtain the Lyapunov function, which makes the analysis difficult, but the analysis results are relatively conservative, making it difficult to obtain an accurate transient stability boundary. Summary of the invention

[0008] In view of this, the purpose of the present invention is to provide a grid-connected new energy unit system modeling method and a system transient stability analysis method to solve the technical problems of accurate modeling and transient stability analysis of the grid-connected new energy unit system.

[0009] Modeling method of grid-connected new energy unit system of the present invention:

[0010] 1) The grid-connected new energy generator system includes a three-phase grid-connected inverter, a DC power supply connected to the DC side of the three-phase grid-connected inverter, an LC filter circuit connected to the AC side of the three-phase grid-connected inverter, a power grid connected to the LC filter circuit, an SVPWM modulation module for controlling the three-phase grid-connected inverter, a phase-locked loop module and a current loop module for controlling the input signal of the SVPWM modulation module, and a state space modeling method is used to establish a nonlinear full-order model of the grid-connected new energy generator system, including:

[0011] The system phase-locked loop equation is established as:

[0012]

[0013] In the formula is the first-order derivative of the phase-locked deviation angle with respect to time, Δω is the output of the phase-locked loop PI controller, is the first-order derivative of the phase-locked loop PI controller output with respect to time, u oq is the q-axis component of the grid-connected point voltage, is the first-order derivative of the q-axis component of the grid-connected point voltage with respect to time, k p is the proportional parameter of the phase-locked loop PI controller, k i is the integral parameter of the phase-locked loop PI controller;

[0014] The system current loop equation is established as:

[0015]

[0016] In the formula, u d To consider the d-axis component of the current loop output before the control delay, u q To consider the q-axis component of the current loop output before the control delay, k pc is the proportional coefficient of the current loop PI controller, k ic is the integral coefficient of the current loop PI controller, i odref is the d-axis component of the current loop setting value, i oqref is the q-axis component of the current loop set value, GVF is the voltage feedforward coefficient, u od is the d-axis component of the grid-connected point voltage, ω PLL is the phase-locked loop angular frequency, L fis the filter inductance of the LC filter, i gd is the d-axis component of the grid current, i gq is the q-axis component of the grid current;

[0017] Establish the system delay control equation:

[0018]

[0019] Where e d To consider the d-axis component of the current loop output after the control delay, e q To consider the q-axis component of the current loop output after the control delay, for e d The first derivative with respect to time, for e q The first derivative with respect to time, T d is the delay coefficient, for u d The first derivative with respect to time, for u q First derivative with respect to time;

[0020] Establish the system voltage and current equation:

[0021]

[0022] In the formula is the second-order derivative of the d-axis component of the inductor current with respect to time, is the second-order derivative of the d-axis component of the grid current with respect to time, i Lq is the q-axis component of the inductor current, is the first-order derivative of the d-axis component of the grid-connected point voltage with respect to time, U g is the grid voltage, R d is the internal resistance of the filter inductor, R g is the equivalent resistance between the grid connection point and the grid, L g is the equivalent inductance between the grid connection point and the grid, C f is the filter capacitor of the LC filter, i Ld is the axis component of the filter output current d; i Lq is the q-axis component of the filter output current;

[0023] Take the system state variable as x full =[x1,x2,…,x 12 ] T =[δ,Δω,u d ,u q ,e d ,e q ,i Ld ,i Lq ,u od ,uoq ,i od ,i oq ] T , the full-order model represented by the above equations (1) to (4) is arranged into a standard form to obtain a set of 12-order nonlinear differential equations, which is the nonlinear full-order model of the new energy grid-connected inverter system:

[0024]

[0025] Where δ is the phase angle θ of the phase-locked loop output in the system controller coordinate system PLL The phase angle θ with the actual coordinate system of the power grid g The deflection angle between PLL is the phase-locked loop angular frequency ω PLL and grid angular frequency ω g difference;

[0026] 2) Ignoring the electromagnetic transient state and current inner loop dynamics of the LC filter in the grid-connected new energy unit system, the nonlinear full-order model established in step 1) is reduced in order, including:

[0027] Establish the grid connection point voltage U o With grid voltage U g The relationship equation is:

[0028] U o =U g +Z g I o =U g +(R g +jω PLL L g )I o (6)

[0029] Where Z g is the line equivalent impedance, I o is the grid-connected point current;

[0030] Multiply both sides of formula (6) by e -jθPLL , and then sort out the grid connection point voltage U o The expression in the synchronously rotating coordinate system is:

[0031]

[0032] Take the state variable as [x1,x2] = [δ,ki∫U oq dt], we get:

[0033]

[0034] Where I od is the d-axis component of the grid-connected point current, Ioq is the q-axis component of the grid-connected point current;

[0035] Move the system to the equilibrium point for analysis, that is, let:

[0036]

[0037] get:

[0038]

[0039] Among them, x 1,e The horizontal coordinate of the equilibrium point is:

[0040]

[0041] Let U0 = R g +ω g L g I od , and replace it with [x1,x2] The simplified model of the system is:

[0042]

[0043] 3) Linearize the nonlinear part of the simplified model represented by equation (12) to obtain a linearized reduced-order model. The linearization process includes:

[0044] For sin(x1+x 1,e ) Perform Taylor expansion at x1 = 0, and use the 11th-order Taylor expansion to replace the nonlinear part of the original function, that is:

[0045]

[0046] Where n is the number of Taylor expansions.

[0047] The present invention provides a method for analyzing transient synchronization stability of a system based on the above linearized reduced-order model, which comprises:

[0048] The Jacobian matrix of the system is obtained as:

[0049]

[0050] The Lyapunov function of the system is obtained as:

[0051] V = [x1, x2] W [x1, x2] T (15)

[0052] Where W is the positive definite matrix of the Lyapunov function to be constructed;

[0053] According to Lyapunov's theorem, for the system The sufficient condition for the Lyapunov function v(x) to be a subset of the system's attraction domain is:

[0054]

[0055] In the formula, Ω v is the region determined by v(x), R n represents the n-dimensional real number field, represents the gradient, and x represents the variable;

[0056] Find the Ω with the largest volume v , in order to obtain the largest possible attraction domain, v(x) is limited to polynomial type to reduce the difficulty of solving, and only needs to satisfy:

[0057]

[0058] In the formula, q(x) is the auxiliary polynomial, c represents the parameter to be optimized;

[0059] Use (c / trace(Λ)) k Approximate the maximum estimated attraction domain, k represents a positive real number, and the problem of constructing the maximum estimated attraction domain is transformed into solving an optimization problem:

[0060]

[0061] Where P(c,Q,Λ)+L(α) is the complete square sum matrix form matrix of p(x); Q=diag(Q1,Q2); Λ, Q1 and Q2 are the complete square sum matrix forms of v(x), q1(x) and q2(x), respectively, q1(x) and q2(x) are auxiliary polynomial functions; trace(Q1) is the trace of matrix Q1.

[0062] Furthermore, the LMI optimization theory is used to solve the maximum estimated attraction domain of the system.

[0063] Beneficial effects of the present invention:

[0064] 1. The modeling method of the grid-connected new energy unit system of the present invention fully considers the influence of the system's phase-locked loop and current loop when constructing the full-order model, reduces the order and linearizes the full-order model, and eliminates the influence of non-critical states and control links. The model after the reduction and linearization processing can not only accurately simulate the original full-order model, but also greatly reduces the difficulty of subsequent transient stability analysis.

[0065] 2. The present invention analyzes the transient synchronous stability of the system based on the simplified model obtained by the grid-connected new energy unit system modeling method, and adopts the LMI optimization method to obtain the maximum estimated attraction domain of the system. The constructed maximum estimated attraction domain can accurately reflect the transient stability boundary of the system and has low conservatism. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 This is the structure diagram of the grid-connected new energy inverter system. In the figure, U dc is the DC side voltage of the inverter, U o is the grid voltage, U g is the grid voltage, L f and C f is the filter inductance and filter capacitance of the LC filter, R g and L g is the equivalent resistance and equivalent inductance between the grid connection point and the grid, θ PLL The phase angle determined by the phase-locked loop, [I od ,I oq ] is the dq axis component of the grid-connected point current, [I odref ,I oqref ] is the dq-axis component of the current loop set value.

[0067] Figure 2 The structure diagram of the phase-locked loop is shown in Figure 1. p , k i are the proportional and integral parameters of the phase-locked loop PI controller, Δω pll is the phase-locked loop angular frequency ω PLL and grid angular frequency ω g The difference, Δω pll =ω PLL -ω g . DETAILED DESCRIPTION

[0068] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0069] The grid-connected new energy generator system described in this embodiment adopts the grid-following inverter to connect to the grid. Figure 1 As shown, it includes a three-phase grid-connected inverter, a DC power supply connected to the DC side of the three-phase grid-connected inverter, an LC filter circuit connected to the AC side of the three-phase grid-connected inverter, a power grid connected to the LC filter circuit, an SVPWM modulation module for controlling the three-phase grid-connected inverter, a phase-locked loop module and a current loop module for controlling the input signal of the SVPWM modulation module, and a state space modeling method is used to establish a nonlinear full-order model of the grid-connected new energy unit system.

[0070] The modeling method of the grid-connected new energy unit system in this embodiment includes:

[0071] 1) The state space modeling method is used to establish a nonlinear full-order model of the grid-connected new energy unit system, including:

[0072] The system phase-locked loop equation is established as:

[0073]

[0074] In the formula is the first-order derivative of the phase-locked deviation angle with respect to time, Δω is the output of the phase-locked loop PI controller, is the first-order derivative of the phase-locked loop PI controller output with respect to time, u oq is the q-axis component of the grid-connected point voltage, is the first-order derivative of the q-axis component of the grid-connected point voltage with respect to time, k p is the proportional parameter of the phase-locked loop PI controller, k i is the integral parameter of the phase-locked loop PI controller.

[0075] The system current loop equation is established as:

[0076]

[0077] In the formula, u d To consider the d-axis component of the current loop output before the control delay, u q To consider the q-axis component of the current loop output before the control delay, k pc is the proportional coefficient of the current loop PI controller, k ic is the integral coefficient of the current loop PI controller, i odref is the d-axis component of the current loop setting value, i oqref is the q-axis component of the current loop set value, GVF is the voltage feedforward coefficient, u od is the d-axis component of the grid-connected point voltage, ω PLL is the phase-locked loop angular frequency, L f is the filter inductance of the LC filter, i gd is the d-axis component of the grid current, i gq is the q-axis component of the grid current.

[0078] Establish the system delay control equation:

[0079]

[0080] Where e d To consider the d-axis component of the current loop output after the control delay, e q To consider the q-axis component of the current loop output after the control delay, for e d The first derivative with respect to time, for e q The first derivative with respect to time, Td is the delay coefficient, for u d The first derivative with respect to time, for u q The first derivative with respect to time.

[0081] Establish the system voltage and current equation:

[0082]

[0083] In the formula is the second-order derivative of the d-axis component of the inductor current with respect to time, is the second-order derivative of the d-axis component of the grid current with respect to time, i Lq is the q-axis component of the inductor current, is the first-order derivative of the d-axis component of the grid-connected point voltage with respect to time, U g is the grid voltage, R d is the internal resistance of the filter inductor, R g is the equivalent resistance between the grid connection point and the grid, L g is the equivalent inductance between the grid connection point and the grid, C f is the filter capacitor of the LC filter, i Ld is the axis component of the filter output current d; i Lq is the q-axis component of the filter output current.

[0084] Take the system state variable as x full =[x1,x2,…,x 12 ] T =[δ,Δω,u d ,u q ,e d ,e q ,i Ld ,i Lq ,u od ,u oq ,i od ,i oq ] T , the full-order model represented by the above equations (1) to (4) is arranged into a standard form to obtain a set of 12-order nonlinear differential equations, which is the nonlinear full-order model of the new energy grid-connected inverter system:

[0085]

[0086] Where δ is the phase angle θ of the phase-locked loop output in the system controller coordinate system PLL The phase angle θ with the actual coordinate system of the power grid g The deflection angle between PLL is the phase-locked loop angular frequency ω PLL and grid angular frequency ωg difference.

[0087] 2) Ignoring the electromagnetic transient state and current inner loop dynamics of the LC filter in the grid-connected new energy unit system, the nonlinear full-order model established in step 1) is reduced in order, including:

[0088] Establish the grid connection point voltage U o With grid voltage U g The relationship equation is:

[0089] U o =U g +Z g I o =U g +(R g +jω PLL L g )I o (6)

[0090] Where Z g is the line equivalent impedance, I o is the grid-connected point current.

[0091] Multiply both sides of formula (6) by e -jθPLL , and then sort out the grid connection point voltage U o The expression in the synchronously rotating coordinate system is:

[0092]

[0093] Take the state variable as [x1,x2] = [δ,ki∫U oq dt], we get:

[0094]

[0095] Where I od is the d-axis component of the grid-connected point current, I oq It is the q-axis component of the grid-connected point current.

[0096] Move the system to the equilibrium point for analysis, that is, let:

[0097]

[0098] get:

[0099]

[0100] Among them, x 1,e The horizontal coordinate of the equilibrium point is:

[0101]

[0102] Let U0 = R g+ω g L g I od , and replace it with [x1,x2] The simplified model of the system is:

[0103]

[0104] 3) Linearize the nonlinear part of the simplified model represented by equation (12) to obtain a linearized reduced-order model. The linearization process includes:

[0105] For sin(x1+x 1,e ) Perform Taylor expansion at x1 = 0, and use the 11th-order Taylor expansion to replace the nonlinear part of the original function, that is:

[0106]

[0107] Where n is the number of Taylor expansions.

[0108] In this embodiment, the transient synchronous stability analysis method of the grid-connected new energy unit system based on the above linearized reduced-order model includes:

[0109] After reducing the order and simplifying the nonlinear full-order model of the grid-connected renewable energy unit system through linearization, the Jacobian matrix of the system is obtained as follows:

[0110]

[0111] The Lyapunov function of the system is:

[0112] V = [x1, x2] W [x1, x2] T (15)

[0113] Where W is the positive definite matrix of the Lyapunov function to be constructed.

[0114] According to Lyapunov's theorem, for the system The sufficient condition for the Lyapunov function v(x) to be a subset of the system's attraction domain is:

[0115]

[0116] In the formula, Ω v is the region determined by v(x), R n represents the n-dimensional real number field, represents the gradient and x represents the variable.

[0117] Find the Ω with the largest volume v , in order to obtain the largest possible attraction domain, v(x) is limited to polynomial type to reduce the difficulty of solving, and only needs to satisfy:

[0118]

[0119] In the formula, q(x) is the auxiliary polynomial, and c represents the parameter to be optimized.

[0120] Use (c / trace(Λ)) k Approximate the maximum estimated attraction domain, k represents a positive real number, and the problem of constructing the maximum estimated attraction domain is transformed into solving an optimization problem:

[0121]

[0122] Where P(c,Q,Λ)+L(α) is the complete square sum matrix form matrix of p(x); Q=diag(Q1,Q2); Λ, Q1 and Q2 are the complete square sum matrix forms of v(x), q1(x) and q2(x), respectively, q1(x) and q2(x) are auxiliary polynomial functions; trace(Q1) is the trace of matrix Q1.

[0123] In this embodiment, the LMI optimization theory is used to solve the maximum estimated attraction domain of the system. The specific process is: first, the initial Lyapunov function of the system and the system equivalent reduced-order model are calculated; then, the optimal Lyapunov function is iterated using the LMI optimization method; finally, the corresponding maximum estimated attraction domain is drawn.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A modeling method for a grid-connected new energy unit system, characterized in that: 1) The grid-connected new energy generator system includes a three-phase grid-connected inverter, a DC power supply connected to the DC side of the three-phase grid-connected inverter, an LC filter circuit connected to the AC side of the three-phase grid-connected inverter, a power grid connected to the LC filter circuit, an SVPWM modulation module for controlling the three-phase grid-connected inverter, a phase-locked loop module and a current loop module for controlling the input signal of the SVPWM modulation module, and a state space modeling method is used to establish a nonlinear full-order model of the grid-connected new energy generator system, including: The system phase-locked loop equation is established as: In the formula is the first-order derivative of the phase-locked deviation angle with respect to time, Δω is the output of the phase-locked loop PI controller, is the first-order derivative of the phase-locked loop PI controller output with respect to time, u oq is the q-axis component of the grid-connected point voltage, is the first-order derivative of the q-axis component of the grid-connected point voltage with respect to time, k p is the proportional parameter of the phase-locked loop PI controller, k i is the integral parameter of the phase-locked loop PI controller; The system current loop equation is established as: In the formula, u d To consider the d-axis component of the current loop output before the control delay, u q To consider the q-axis component of the current loop output before the control delay, k pc is the proportional coefficient of the current loop PI controller, k ic is the integral coefficient of the current loop PI controller, i odref is the d-axis component of the current loop setting value, i oqref is the q-axis component of the current loop set value, GVF is the voltage feedforward coefficient, u od is the d-axis component of the grid-connected point voltage, ω PLL is the phase-locked loop angular frequency, L f is the filter inductance of the LC filter, i gd is the d-axis component of the grid current, i gq is the q-axis component of the grid current; Establish the system delay control equation: Where e d To consider the d-axis component of the current loop output after the control delay, e q To consider the q-axis component of the current loop output after the control delay, for e d The first derivative with respect to time, for e q The first derivative with respect to time, T d is the delay coefficient, for u d The first derivative with respect to time, for u q First derivative with respect to time; Establish the system voltage and current equation: In the formula is the second-order derivative of the d-axis component of the inductor current with respect to time, is the second-order derivative of the d-axis component of the grid current with respect to time, i Lq is the q-axis component of the inductor current, is the first-order derivative of the d-axis component of the grid-connected point voltage with respect to time, U g is the grid voltage, R d is the internal resistance of the filter inductor, R g is the equivalent resistance between the grid connection point and the grid, L g is the equivalent inductance between the grid connection point and the grid, C f is the filter capacitor of the LC filter, i Ld is the axis component of the filter output current d; i Lq is the q-axis component of the filter output current; Take the system state variable as x full =[x1,x2,…,x 12 ] T =[δ,Δω,u d ,u q ,e d ,e q ,i Ld ,i Lq ,u od ,u oq ,i od ,i oq ] T , the full-order model represented by the above equations (1) to (4) is arranged into a standard form to obtain a set of 12-order nonlinear differential equations, which is the nonlinear full-order model of the new energy grid-connected inverter system: Where δ is the phase angle θ of the phase-locked loop output in the system controller coordinate system PLL The phase angle θ with the actual grid coordinate system g The deflection angle between PLL is the phase-locked loop angular frequency ω PLL and grid angular frequency ω g difference; 2) Ignoring the electromagnetic transient state and current inner loop dynamics of the LC filter in the grid-connected new energy unit system, the nonlinear full-order model established in step 1) is reduced in order, including: Establish the grid connection point voltage U o With grid voltage U g The relationship equation is: U o =U g +Z g I o =U g +(R g +jω PLL L g )I o (6) Where Z g is the line equivalent impedance, I o is the grid-connected point current; Multiply both sides of formula (6) by e -jθPLL , and then sort out the grid connection point voltage U o The expression in the synchronously rotating coordinate system is: Take the state variable as [x1,x2] = [δ,ki∫U oq dt], we get: Where I od is the d-axis component of the grid-connected point current, I oq is the q-axis component of the grid-connected point current; Move the system to the equilibrium point for analysis, that is, let: get: Among them, x 1,e The horizontal coordinate of the equilibrium point is: Let U0 = R g +ω g L g I od , and replace it with [x1,x2] The simplified model of the system is: 3) Linearize the nonlinear part of the simplified model represented by equation (12) to obtain a linearized reduced-order model. The linearization process includes: For sin(x1+x 1,e ) Perform Taylor expansion at x1 = 0, and use the 11th-order Taylor expansion to replace the nonlinear part of the original function, that is: Where n is the number of Taylor expansions.

2. A method for analyzing transient synchronous stability of a system according to the linearized reduced-order model of claim 1, characterized in that: include: The Jacobian matrix of the system is obtained as: The Lyapunov function of the system is obtained as: V=[x1,x2]W[x1,x2] T (15) Where W is the positive definite matrix of the Lyapunov function to be constructed; According to Lyapunov's theorem, for the system The sufficient condition for the Lyapunov function v(x) to be a subset of the system's attraction domain is: In the formula, Ω v is the region determined by v(x), R n represents the n-dimensional real number field, represents the gradient, and x represents the variable; Find the Ω with the largest volume v , in order to obtain the largest possible attraction domain, v(x) is limited to polynomial type to reduce the difficulty of solving, and only needs to satisfy: In the formula, q(x) is the auxiliary polynomial, c represents the parameter to be optimized; Use (c / trace(Λ)) k Approximate the maximum estimated attraction domain, k represents a positive real number, and the problem of constructing the maximum estimated attraction domain is transformed into solving an optimization problem: Where P(c,Q,Λ)+L(α) is the complete square sum matrix form matrix of p(x); Q=diag(Q1,Q2); Λ, Q1 and Q2 are the complete square sum matrix forms of v(x), q1(x) and q2(x), respectively, q1(x) and q2(x) are auxiliary polynomial functions; trace(Q1) is the trace of matrix Q1.

3. The system transient synchronous stability analysis method according to claim 2 is characterized in that: The LMI optimization theory is used to solve the maximum estimated attraction domain of the system.

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