阅读说明：本技术 对等控制方式下低压交直流系统可扩展建模及分析方法 (Extensible modeling and analyzing method for low-voltage alternating current-direct current system in peer-to-peer control mode ) 是由 吴琦 邓卫 裴玮 杨艳红 张国驹 孔力 于 2021-06-18 设计创作，主要内容包括：本发明涉及一种对等控制方式下低压交直流系统可扩展建模及分析方法,包括：步骤一：构建单站的状态矩阵与输入矩阵；依据下垂控制策略,建立各站的状态空间模型,并形成其状态矩阵与输入矩阵；步骤二：构建所有换流站的整体状态矩阵与输入矩阵；将单站状态矩阵与输入矩阵进行拼接,整合形成N个换流站的整体状态矩阵与输入矩阵；步骤三：构建直流网络矩阵,根据基尔霍夫电压定理、基尔霍夫电流定理,建立N端直流网络的模型,并整合形成直流网络矩阵；步骤四：构建系统整体状态空间矩阵,将N个换流站整体状态矩阵与输入矩阵、直流网络矩阵进行模块化拼接,得到N端直流系统的完整状态空间矩阵；步骤五：将完整状态空间矩阵进行特征值分析,研究系统运行机理。(The invention relates to an extensible modeling and analyzing method for a low-voltage alternating current-direct current system in a peer-to-peer control mode, which comprises the following steps: the method comprises the following steps: constructing a state matrix and an input matrix of a single station; establishing a state space model of each station according to a droop control strategy, and forming a state matrix and an input matrix of each station; step two: constructing an integral state matrix and an input matrix of all converter stations; splicing the single-station state matrix and the input matrix, and integrating to form an integral state matrix and an input matrix of the N converter stations; step three: constructing a direct current network matrix, establishing a model of an N-end direct current network according to kirchhoff voltage theorem and kirchhoff current theorem, and integrating to form the direct current network matrix; step four: constructing a system overall state space matrix, and modularly splicing the N converter station overall state matrixes with an input matrix and a direct current network matrix to obtain an overall state space matrix of the N-terminal direct current system; step five: and analyzing the characteristic value of the complete state space matrix and researching the operation mechanism of the system.)

1. A low-voltage alternating current and direct current system extensible modeling and analysis method under an equivalent control mode is characterized by comprising the following steps:

the method comprises the following steps: constructing a state matrix and an input matrix of a single station; establishing a state space model of each station according to a droop control strategy, forming a state matrix and an input matrix of each station, and using the state matrix and the input matrix as input of the second step;

step two: constructing an integral state matrix and an input matrix of all converter stations; splicing the single-station state matrix and the input matrix in the step one, integrating to form an integral state matrix and an input matrix of the N converter stations, and taking the integral state matrix and the input matrix as the input of the step four;

step three: constructing a direct current network matrix, establishing a model of an N-end direct current network according to kirchhoff voltage theorem and kirchhoff current theorem, integrating to form the direct current network matrix, and using the direct current network matrix as the input of the fourth step;

step four: constructing a system overall state space matrix, modularly splicing the N converter station overall state matrixes in the step two with the input matrix and the direct current network matrix in the step three to obtain an overall state space matrix of the N-terminal direct current system, and using the overall state space matrix as the input in the step five;

step five: and C, analyzing the characteristic value of the complete state space matrix in the step four, and researching the system operation mechanism.

2. The method according to claim 1, wherein the step one of constructing the state matrix and the input matrix of the single station specifically comprises:

according to the voltage loop and current loop structure of the droop controller of the voltage source type converter station, a state space model of the single-station VSCn is obtained, and the conditions are met:

in the formula, A_{droop_n}、B_{droop_n}、Δx_{droop_n}、Δu_{droop_n}Respectively a state matrix, an input matrix, a state vector and an input vector of the converter station VSCn; the specific expression satisfies:

in the formula (I), the compound is shown in the specification,

is a scaling factor of the outer loop of the voltage,for the voltage outer loop integration parameter,is the proportion parameter of the inner ring of the active current,an active current inner loop integral parameter; l is_acn、R_acn、U_acdn0、U_cdn0、i_dn0、P_dcn0The method comprises the steps that a converter station VSCn alternating-current side inductor, an alternating-current side resistor, an alternating-current side grid-connected voltage d-axis component steady-state value, an alternating-current side output voltage d-axis component steady-state value, an alternating-current side grid-connected current d-axis component steady-state value and a direct-current power steady-state value are obtained; i.e. i_qn0Obtaining a steady-state value of a grid-connected current q-axis component at the AC side of the converter station VSCn; u shape_n0、C_nThe voltage is a steady-state value of the direct current side voltage of the converter station VSCn and the direct current side capacitance; omega is the angular speed of the power grid; k is a radical of_nIs the droop coefficient of the converter station VSCn.

3. The scalable modeling and analysis method for the low-voltage alternating current-direct current system under the peer-to-peer control mode according to claim 1, characterized in that the second step: constructing an integral state matrix and an input matrix of all converter stations, which specifically comprises the following steps:

n is A_{droop_n}And n number of B_{droop_n}Integrating to obtain an integral state matrix A of the N converter stations_droopAnd input matrix B_droopAnd satisfies the following conditions:

in the formula, A_{droop_1}、A_{droop_n}、A_{droop_N}、B_{droop_1}、B_{droop_n}、B_{droop_N}The state matrix of the converter station VSC1, the state matrix of the converter station VSCn, the input matrix of the converter station VSC1, the input matrix of the converter station VSCn, respectively.

4. The extensible modeling and analysis method for the low-voltage alternating current and direct current system in the peer-to-peer control mode according to claim 1, characterized in that the third step: the constructing of the direct current network matrix specifically comprises the following steps:

the line at the direct current bus end meets the KCL equation:

in the formula, U, U₀Respectively are the steady-state values of the direct-current bus voltage and the direct-current bus voltage; i.e. i₁、i_n、i_NRespectively, the direct current side current of the converter station VSC1, the direct current side current of the converter station VSCn and the direct current side current of the converter station VSCN; p_eqThe equivalent power of the constant power load at the side of the direct current bus is obtained; c is a direct current bus capacitor;

the direct-current side circuit of the converter VSCn meets the KVL equation:

in the formula, L_n、R_n、i_nRespectively providing a converter station VSCn direct current side line inductor, a direct current side line resistor and a direct current side current; u shape_nU is direct current side voltage and direct current bus voltage of the converter station VSCn respectively;

establishing a converter station direct current side network matrix Net according to the formula_droopNetwork matrix Net on side of direct current bus_{DC_bus}And satisfies the following conditions:

in the formula, U, U₀Respectively are the steady-state values of the direct-current bus voltage and the direct-current bus voltage; i.e. i₁、i_n、i_NRespectively, the direct current side current of the converter station VSC1, the direct current side current of the converter station VSCn and the direct current side current of the converter station VSCN; p_eqThe equivalent power of the constant power load at the side of the direct current bus is obtained; c is a direct current bus capacitor; l is_n、R_nThe direct current side line inductance and the direct current side line resistance of the converter station VSCn are respectively; l is₁、R₁The direct current side line inductance and the direct current side line resistance of the converter station VSC1 are respectively; l is_N、R_NThe direct current side line inductance and the direct current side line resistance of the VSCN of the converter station are respectively.

5. The scalable modeling and analysis method for the low-voltage AC/DC system under the peer-to-peer control mode according to claim 1, characterized in that the fourth step is: the method for constructing the system overall state space matrix specifically comprises the following steps:

integrating the state matrix A of N converter stations_droopInput matrix B_droopNetwork matrix Net on direct current side_droopNetwork matrix Net on side of direct current bus_{DC_bus}Carrying out modularization splicing to obtain a system overall state space matrix A, satisfying:

6. the scalable modeling and analysis method for the low-voltage AC/DC system under the peer-to-peer control mode according to claim 1, characterized in that the step five: analyzing the characteristic value of the complete state space matrix in the step four, researching the system operation mechanism, and specifically comprising the following steps:

drawing a characteristic value distribution diagram of the A matrix;

when the right half-plane characteristic value exists, the system is unstable;

when the characteristic value is positioned on the virtual axis, the system is critically stable;

when all the characteristic values are positioned on the left half plane, the system is stable.

Technical Field

The invention relates to the field of electric power, in particular to an extensible modeling and analyzing method for a low-voltage alternating current-direct current system in a peer-to-peer control mode.

Background

The distributed energy becomes the core of energy transformation work in China due to the advantages of strong complementarity, nearby consumption and the like. Although the power distribution network in the present stage of China still mainly uses alternating current, distributed energy sources such as wind power and photovoltaic are connected into the power grid in a direct current mode, so that the current conversion link can be reduced, the efficiency is improved, and the harmonic content is reduced; direct current loads such as electric automobile charging pile and energy storage equipment are widely popularized, and the development of direct current power distribution is greatly promoted by the factors.

Fig. 1 illustrates an equivalent circuit of a low-voltage multi-terminal ac/dc distribution system, in which an ac system 1, an ac system 2 … …, an ac system N … …, an ac system N, and the like are interconnected through a dc system, ac sides of a VSC1 and a VSC2 … … VSCn … … VSCn are respectively connected to the ac system 1 and the ac system N … …, and dc sides thereof flow into a dc bus through a line. The direct current system can be connected with wind power, photovoltaic and other renewable energy sources, an energy storage system, an electric automobile and other direct current loads, and when the voltage grade of the equipment is not matched with the voltage grade of the direct current bus, the DC/DC converter can be reasonably configured for conversion. Each converter station adopts a droop control mode, and the power balance of the system is shared while the voltage of each direct current end is controlled to be stable.

Because the power electronization degree in the direct current system is high, the direct current system has the characteristics of obvious weak damping, low inertia and the like. In addition, droop control is used as a main coordination control mode of a multi-terminal direct current system, power equalization among stations is achieved under the condition of low communication requirement, the stable control effect on direct current voltage is sacrificed to a certain extent, and the problem of system stability is more prominent. In view of the above problems, a series of studies have been conducted by a large number of scholars, but the study is mainly focused on a single bus system or a double-ended system, while a generalized stability analysis method for a low-voltage multi-terminal dc system structure is less mentioned, and a technical gap still exists in how to effectively reduce the complexity of a high-order low-voltage multi-terminal dc system.

Disclosure of Invention

Aiming at the technical problem, the invention provides a flexible and extensible modular modeling method capable of quickly building a system model, and the efficiency of system stability analysis is obviously improved.

The technical scheme of the invention is as follows: a low-voltage alternating current and direct current system extensible modeling and analysis method under a peer-to-peer control mode specifically comprises five steps:

the method comprises the following steps: and constructing a state matrix and an input matrix of the single station. Establishing a state space model of each station according to a droop control strategy, forming a state matrix and an input matrix of each station, and using the state matrix and the input matrix as input of the second step;

step two: an overall state matrix and input matrix for all converter stations is constructed. Splicing the single-station state matrix and the input matrix in the step one, integrating to form an integral state matrix and an input matrix of the N converter stations, and taking the integral state matrix and the input matrix as the input of the step four;

step three: and constructing a direct current network matrix. Establishing a model of an N-terminal direct current network according to kirchhoff voltage theorem and kirchhoff current theorem, integrating to form a direct current network matrix, and taking the direct current network matrix as the input of the fourth step;

step four: and constructing a system overall state space matrix. Modularly splicing the N convertor station overall state matrixes, the input matrix and the direct current network matrix in the third step to obtain an overall state space matrix of the N-terminal direct current system, and using the overall state space matrix as the input in the fifth step;

step five: and C, analyzing the characteristic value of the complete state space matrix in the step four, and researching the system operation mechanism.

Specifically, the first step: and constructing a state matrix and an input matrix of the single station.

According to the voltage loop and current loop structure of the droop controller of the voltage source type converter station, a state space model of the single-station VSCn is obtained, and the conditions are met:

in the formula (I), the compound is shown in the specification,

is a scaling factor of the outer loop of the voltage,for the voltage outer loop integration parameter,is the proportion parameter of the inner ring of the active current,and (4) an active current inner loop integral parameter. L is_acn、R_acn、U_acdn0、U_cdn0、i_dn0、P_dcn0The method comprises the steps that a converter station VSCn alternating-current side inductor, an alternating-current side resistor, an alternating-current side grid-connected voltage d-axis component steady-state value, an alternating-current side output voltage d-axis component steady-state value, an alternating-current side grid-connected current d-axis component steady-state value and a direct-current power steady-state value are obtained; i.e. i_qn0Obtaining a steady-state value of a grid-connected current q-axis component at the AC side of the converter station VSCn; u shape_n0、C_nThe voltage is a steady-state value of the direct current side voltage of the converter station VSCn and the direct current side capacitance; omega is the angular speed of the power grid; k is a radical of_nIs the droop coefficient of the converter station VSCn.

Further, step two: an overall state matrix and input matrix for all converter stations is constructed.

N is A_{droop_n}And n number of B_{droop_n}Integrating to obtain an integral state matrix A of the N converter stations_droopAnd input matrix B_droopAnd satisfies the following conditions:

in the formula, A_{droop_1}、A_{droop_n}、A_{droop_N}、B_{droop_1}、B_{droop_n}、B_{droop_N}The state matrix of the converter station VSC1, the state matrix of the converter station VSCn, the input matrix of the converter station VSC1, the input matrix of the converter station VSCn, respectively.

Further, step three: and constructing a direct current network matrix.

The line at the direct current bus end meets the KCL equation:

in the formula, U, U₀Respectively are the steady-state values of the direct-current bus voltage and the direct-current bus voltage; i.e. i₁、i_n、i_NRespectively, the direct current side current of the converter station VSC1, the direct current side current of the converter station VSCn and the direct current side current of the converter station VSCN; p_eqThe equivalent power of the constant power load at the side of the direct current bus is obtained; c is a direct current bus capacitor.

The direct-current side circuit of the converter VSCn meets the KVL equation:

in the formula, L_n、R_n、i_nRespectively providing a converter station VSCn direct current side line inductor, a direct current side line resistor and a direct current side current; u shape_nAnd U is direct current side voltage and direct current bus voltage of the converter station VSCn respectively.

According to the above formula, the method comprises the following steps,establishing a network matrix Net at the direct current side of the converter station_droopNetwork matrix Net on side of direct current bus_{DC_bus}And satisfies the following conditions:

in the formula, U, U₀Respectively are the steady-state values of the direct-current bus voltage and the direct-current bus voltage; i.e. i₁、i_n、i_NRespectively, the direct current side current of the converter station VSC1, the direct current side current of the converter station VSCn and the direct current side current of the converter station VSCN; p_eqThe equivalent power of the constant power load at the side of the direct current bus is obtained; c is a direct current bus capacitor; l is_n、R_nThe direct current side line inductance and the direct current side line resistance of the converter station VSCn are respectively; l is₁、R₁The direct current side line inductance and the direct current side line resistance of the converter station VSC1 are respectively; l is_N、R_NThe direct current side line inductance and the direct current side line resistance of the VSCN of the converter station are respectively.

Further, step four: and constructing a system overall state space matrix.

Integrating the state matrix A of N converter stations_droopInput matrix B_droopNetwork matrix Net on direct current side_droopNetwork matrix Net on side of direct current bus_{DC_bus}Carrying out modularization splicing to obtain a system overall state space matrix A, satisfying:

further, step five: and C, analyzing the characteristic value of the complete state space matrix in the step four, and researching the system operation mechanism.

And drawing a characteristic value distribution graph of the A matrix.

When the right half-plane characteristic value exists, the system is unstable;

when the characteristic value is positioned on the virtual axis, the system is critically stable;

when all the characteristic values are positioned on the left half plane, the system is stable.

Has the advantages that:

according to the extensible modeling and analyzing method for the low-voltage alternating current and direct current system in the peer-to-peer control mode, the space state matrix of the multi-terminal alternating current and direct current power distribution and utilization system based on droop control is constructed, and the dynamic characteristics of each part of a main circuit, a control system and the like in the alternating current and direct current power distribution and utilization system can be visually reflected. Meanwhile, when the system increases or decreases the converter stations, the method can quickly update the state matrix, is convenient for carrying out real-time stability analysis on the system, avoids the defects of difficult modeling and low flexibility of the traditional small signal stability analysis method, fills up the technical blank and has wide application prospect.

Drawings

FIG. 1 is an equivalent circuit of a low-voltage multi-terminal AC/DC power distribution system;

FIG. 2 is a schematic diagram of a VSC main circuit;

FIG. 3 is a view of a droop control structure;

FIG. 4 is a flow chart of the method of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person skilled in the art based on the embodiments of the present invention belong to the protection scope of the present invention without creative efforts.

Fig. 1 illustrates an equivalent circuit of a low-voltage multi-terminal ac/dc distribution system, in which an ac system 1, an ac system 2 … …, an ac system N … …, an ac system N, and the like are interconnected through a dc system, ac sides of a VSC1 and a VSC2 … … VSCn … … VSCn are respectively connected to the ac system 1 and the ac system N … …, and dc sides thereof flow into a dc bus through a line. The direct current system can be connected with renewable energy sources such as wind power, photovoltaic and the like, direct current loads such as an energy storage system and an electric automobile, and when the voltage level of the equipment is not matched with the voltage level of the direct current bus, the DC/DC converter can be reasonably configured for conversion. Each converter station adopts a droop control mode, and the power balance of the system is shared while the voltage of each direct current end is controlled to be stable.

FIG. 2 is a schematic diagram of a VSC main circuit, wherein R is_aciAnd L_aciRespectively representing the equivalent resistance and the equivalent inductance of the alternating current side of the ith VSC; u shape_aci、I_aci、U_ciRepresenting grid-connected voltage, grid-connected current and output voltage of the ith VSC alternating current side; p_aciAnd Q_aciThe active power and the reactive power of the ith VSC alternating current side are represented; r_i、L_i、C_iRepresenting the line resistance, line inductance and direct current capacitance of the ith VSC direct current side; u shape_i、I_i、P_dciAnd U represents the i-th VSC dc side voltage, dc current, dc power and dc bus voltage.

In the distributed energy and user alternating current and direct current power distribution and utilization system, each converter adopts droop control, and the power balance of the system is shared while the voltage of each direct current end is controlled to be stable.

FIG. 3 shows a droop control structure, where U^* _i、U^* _acdiRespectively represent U_iAnd U_acdiA reference value of (d); i is_di、I_qiIs represented by_aciD-q axis component of (I)_di,ref、I_qi,refRespectively represent I_di、I_qiA reference value of (d); u shape_acdi、U_acqiRepresents U_aciD-q axis component of (a); u shape_cdi、U_cqiRepresents U_ciThe d-q axis component of (a).Is a voltage outer loop controller parameter;parameters of the alternating current outer ring controller;active current inner loop controller parameters;parameters of a reactive current inner loop controller; k is a radical of_iIs the droop coefficient of the converter station VSCi.

In addition, setting C represents a dc bus capacitance; p_eq、P_iThe equivalent power at the dc bus and the equivalent power absorbed by the slave station i are shown respectively.

According to an embodiment of the present invention, as shown in fig. 4, a method for extensible modeling and analysis of a low-voltage ac/dc system under an equivalent control mode specifically includes the following steps:

the method comprises the following steps: and constructing a state matrix and an input matrix of the single station. Establishing a state space model of each station according to a droop control strategy, forming a state matrix and an input matrix of each station, and using the state matrix and the input matrix as input of the second step;

step two: an overall state matrix and input matrix for all converter stations is constructed. Splicing the single-station state matrix and the input matrix in the step one, integrating to form an integral state matrix and an input matrix of the N converter stations, and taking the integral state matrix and the input matrix as the input of the step four;

step three: and constructing a direct current network matrix. Establishing a model of an N-terminal direct current network according to kirchhoff voltage theorem and kirchhoff current theorem, integrating to form a direct current network matrix, and taking the direct current network matrix as the input of the fourth step;

step four: and constructing a system overall state space matrix. Modularly splicing the N convertor station overall state matrixes, the input matrix and the direct current network matrix in the third step to obtain an overall state space matrix of the N-terminal direct current system, and using the overall state space matrix as the input in the fifth step;

step five: and C, analyzing the characteristic value of the complete state space matrix in the step four, and researching the system operation mechanism.

According to the embodiment of the invention, the specific steps are as follows:

the method comprises the following steps: and constructing a state matrix and an input matrix of the single station.

According to the voltage loop and current loop structure of the droop controller of the voltage source type converter station, a state space model of the single-station VSCn is obtained, and the conditions are met:

in the formula, A_{droop_n}、B_{droop_n}、Δx_{droop_n}、Δu_{droop_n}Respectively state matrix, input matrix, state vector, input vector of the converter station VSCn. The specific expression satisfies:

in the formula (I), the compound is shown in the specification,

is a scaling factor of the outer loop of the voltage,for the voltage outer loop integration parameter,is the proportion parameter of the inner ring of the active current,and (4) an active current inner loop integral parameter. L is_acn、R_acn、U_acdn0、U_cdn0、i_dn0、P_dcn0The method comprises the steps that a converter station VSCn alternating-current side inductor, an alternating-current side resistor, an alternating-current side grid-connected voltage d-axis component steady-state value, an alternating-current side output voltage d-axis component steady-state value, an alternating-current side grid-connected current d-axis component steady-state value and a direct-current power steady-state value are obtained; i.e. i_qn0Obtaining a steady-state value of a grid-connected current q-axis component at the AC side of the converter station VSCn; u shape_n0、C_nThe voltage is a steady-state value of the direct current side voltage of the converter station VSCn and the direct current side capacitance; omega is the angular speed of the power grid; k is a radical of_nIs the droop coefficient of the converter station VSCn.

Step two: an overall state matrix and input matrix for all converter stations is constructed.

N is A_{droop_n}And n number of B_{droop_n}Integrating to obtain an integral state matrix A of the N converter stations_droopAnd input matrix B_droopAnd satisfies the following conditions:

in the formula, A_{droop_1}、A_{droop_n}、A_{droop_N}、B_{droop_1}、B_{droop_n}、B_{droop_N}The state matrix of the converter station VSC1, the state matrix of the converter station VSCn, the input matrix of the converter station VSC1, the input matrix of the converter station VSCn, respectively.

Step three: and constructing a direct current network matrix.

The line at the direct current bus end meets the KCL equation:

in the formula, U, U₀Respectively are the steady-state values of the direct-current bus voltage and the direct-current bus voltage; i.e. i₁、i_n、i_NRespectively, the direct current side current of the converter station VSC1, the direct current side current of the converter station VSCn and the direct current side current of the converter station VSCN; p_eqThe equivalent power of the constant power load at the side of the direct current bus is obtained; c is a direct current bus capacitor.

The direct-current side circuit of the converter VSCn meets the KVL equation:

in the formula, L_n、R_n、i_nRespectively providing a converter station VSCn direct current side line inductor, a direct current side line resistor and a direct current side current; u shape_nAnd U is direct current side voltage and direct current bus voltage of the converter station VSCn respectively.

Establishing a converter station direct current side network matrix Net according to the formula_droopNetwork matrix Net on side of direct current bus_{DC_bus}And satisfies the following conditions:

in the formula, U, U₀Respectively are the steady-state values of the direct-current bus voltage and the direct-current bus voltage; i.e. i₁、i_n、i_NRespectively, the direct current side current of the converter station VSC1, the direct current side current of the converter station VSCn and the direct current side current of the converter station VSCN; p_eqThe equivalent power of the constant power load at the side of the direct current bus is obtained; c is a direct current bus capacitor; l is_n、R_nThe direct current side line inductance and the direct current side line resistance of the converter station VSCn are respectively; l is₁、R₁The direct current side line inductance and the direct current side line resistance of the converter station VSC1 are respectively; l is_N、R_NThe direct current side line inductance and the direct current side line resistance of the VSCN of the converter station are respectively.

Step four: and constructing a system overall state space matrix.

Integrating the state matrix A of N converter stations_droopInput matrix B_droopNetwork matrix Net on direct current side_droopNetwork matrix Net on side of direct current bus_{DC_bus}Carrying out modularization splicing to obtain a system overall state space matrix A, satisfying:

step five: and C, analyzing the characteristic value of the complete state space matrix in the step four, and researching the system operation mechanism.

And drawing a characteristic value distribution graph of the A matrix.

When the right half-plane characteristic value exists, the system is unstable;

when the characteristic value is positioned on the virtual axis, the system is critically stable;

when all the characteristic values are positioned on the left half plane, the system is stable.

The method constructs the space state matrix of the multi-terminal AC/DC power distribution system based on droop control, and can visually reflect the dynamic characteristics of each part of a main circuit, a control system and the like in the AC/DC power distribution system. Meanwhile, when the system increases or decreases the converter stations, the method can quickly update the state matrix, is convenient for carrying out real-time stability analysis on the system, avoids the defects of difficult modeling and low flexibility of the traditional small signal stability analysis method, fills up the technical blank and has wide application prospect.

Although illustrative embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, but various changes may be apparent to those skilled in the art, and it is intended that all inventive concepts utilizing the inventive concepts set forth herein be protected without departing from the spirit and scope of the present invention as defined and limited by the appended claims.