CN108429250B

CN108429250B - Equivalence method considering static frequency characteristics of external network

Info

Publication number: CN108429250B
Application number: CN201810115476.8A
Authority: CN
Inventors: 余娟; 林伟; 代伟; 刘林虎; 颜伟; 赵霞
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2018-02-06
Filing date: 2018-02-06
Publication date: 2021-07-30
Anticipated expiration: 2038-02-06
Also published as: CN108429250A

Abstract

The invention discloses an equivalence method considering static frequency characteristics of an external network, which mainly comprises the following steps: 1) and establishing an original power network model. 2) Inputting basic parameters of the power network in the original power network model. 3) And establishing an equivalent power network model by using an equivalent method of consistency of the power flow and the sensitivity. 4) And calculating the static frequency characteristic of the equivalent load according to the equivalent power network model. 5) And calculating the static frequency characteristic of the equivalent generator according to the equivalent power network model. The method effectively keeps the consistency of the trend and the sensitivity, effectively keeps the static frequency characteristic of the external network, and more truly reflects the actual operation characteristic of the power system.

Description

Equivalence method considering static frequency characteristics of external network

Technical Field

The invention relates to the field of static equivalence methods of power systems, in particular to an equivalence method considering static frequency characteristics of an external network.

Background

Along with the continuous rising of new energy permeability, the system uncertainty is gradually enhanced, and the out-of-limit risks such as frequency, branch power, voltage and the like in the system tide are increasingly prominent. Therefore, to reflect the actual operating characteristics of the power system, the static frequency characteristics reflecting the load and generator frequency response should be accounted for in the power flow analysis. In addition, modern power systems have been developed into large and complex power grids which are layered, partitioned and tightly interconnected, and the overall scale is large, detailed data among subsystems are difficult to interact in real time, so that integrated power flow analysis is difficult to implement, and power flow analysis accuracy without considering external network influence is poor. Therefore, an equivalent model containing static frequency characteristics needs to be established to improve the feasibility and the calculation accuracy of the power flow analysis.

The existing equivalent models of the conventional static topological method, such as a PV equivalent model, a Thevenin equivalent model, a Ward equivalent model and the like, do not consider the static characteristic frequency characteristic of an external network in an equivalent network. In the existing equivalent model research considering the static frequency characteristics of the external network, the static frequency characteristics of the external network load and the generator are uniformly equivalent to boundary nodes by using a Ward equivalent method based on a direct current power flow model, and the obvious difference between the static frequency characteristics of the load and the generator is ignored. Meanwhile, the Ward equivalence method can only ensure the consistency of the tidal current before and after equivalence, and cannot keep the consistency of the sensitivity before and after equivalence. Therefore, it cannot truly reflect the actual operation characteristics of the power system, and may be difficult to adapt to power flow analysis in consideration of frequency variation.

Disclosure of Invention

The present invention is directed to solving the problems of the prior art.

The technical scheme adopted for achieving the purpose of the invention is that an equivalent method considering the static frequency characteristic of an external network mainly comprises the following steps:

1) and establishing an original power network model.

2) Inputting basic parameters of the power network in the original power network model.

Further, the basic parameters of the power network mainly include element parameters in the original network, the topology structure of the original network and the calculation result of the load flow at the moment of approach.

The element parameters in the original network mainly comprise the admittance to the ground of all nodes, the connection load power of all nodes, the impedance of all lines, the susceptance to the ground of all lines, the constraint condition of line transmission power, the impedance of a transformer, the admittance to the ground of the transformer, the transformation ratio of the transformer, the constraint condition of transformer transmission power, the output of a generator, the constraint condition of the output of the generator, the power frequency static characteristic coefficient of the generator and the power frequency static characteristic coefficient of the load.

The original network topology mainly comprises the connection relation of all nodes and the network partition condition.

The near moment power flow calculation result mainly comprises a node admittance matrix, a node voltage matrix and a node injection current matrix.

3) And establishing an equivalent power network model by using an equivalent method of consistency of the power flow and the sensitivity.

Further, the main steps of establishing the equivalent power network model are as follows:

and 3.1) calculating equivalent parameters in the equivalent power network model by using an equivalent method of load flow and sensitivity consistency. The equivalent parameters mainly comprise equivalent branch admittance y_eqGij、y_eqBiAnd y_eqBijEquivalent ground branch admittance y_eqBi0Node voltage amplitude U of sum-equivalent generator_GeqBi。

And 3.2) establishing an equivalent power network model according to the equivalent parameters and the original power network model.

4) And calculating the static frequency characteristic of the equivalent load according to the equivalent power network model.

Further, the main steps of calculating the static frequency characteristic of the equivalent load are as follows:

4.1) calculating the equivalent load current I_Leq. Equivalent load current I_LeqAs follows:

in the formula I_LBThe load current of the original boundary network. I is_LEThe load current of the original external network. Y is_LLAnd the admittance submatrix is corresponding to the load node in the original external network. LB is the original boundary load node. LE is original outer net load node.

For said admittance submatrix Y_LLThe inverse matrix of (c).

4.2) according to the equivalent load current I_LeqCalculating the equivalent load power S_Leq. Equivalent load power S_LeqAs follows:

in the formula, S_LBIs the original boundary load power. S_LEIs the original outer net load power. U shape_{LB_diag}Representing main diagonal elements as boundary node voltages U_LBThe diagonal matrix of (a). U shape_{LE_diag}Representing the main diagonal element as the external load node voltage U_LEThe diagonal matrix of (a).

For said admittance submatrix

The companion matrix of (a).

For said admittance submatrix Y_LLThe companion matrix of (a). LB is the original boundary load node. LE is original outer net load node.

4.3) according to the equivalent load power S_LeqCalculating the equivalent active load P_LeqSum equivalent reactive load Q_Leq. The method mainly comprises the following steps:

4.3.1) setting an intermediate parameter H:

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

for said admittance submatrix

The companion matrix of (a).

For said admittance submatrix Y_LLThe companion matrix of (a). LB is the original boundary load node. LE is original outer net load node. U shape_{LE_diag}Representing main diagonalElement is external load node voltage U_LEThe diagonal matrix of (a).

4.3.2) equivalent active load P_LeqAs follows:

in the formula, P_LBThe active load for the original network boundary. P_LEIs the original active load of the external network. U shape_{LB_diag_real}Is a diagonal matrix U_{LB_diag}The real parts of the elements form a matrix. U shape_{LB_diag_imag}Is a diagonal matrix U_{LB_diag}The imaginary part of the element constitutes a matrix. H is an intermediate parameter. Q_LEIs the original outer net reactive load. U shape_{LB_diag}Representing main diagonal elements as boundary node voltages U_LBThe diagonal matrix of (a).

4.3.3) equivalent reactive load Q_LeqAs follows:

in the formula, Q_LBIs the original boundary reactive load. Q_LEIs the original outer net reactive load. U shape_{LB_diag_real}Is a diagonal matrix U_{LB_diag}The real parts of the elements form a matrix. U shape_{LB_diag_imag}Is a diagonal matrix U_{LB_diag}The imaginary part of the element constitutes a matrix. H is an intermediate parameter. U shape_{LB_diag}Representing main diagonal elements as boundary node voltages U_LBThe diagonal matrix of (a). P_LEIs the original active load of the external network.

4.4) setting a new energy station. And setting N as the new energy station node set. And setting L as the new energy station load node set. The new energy mainly comprises wind and light. And setting the new energy source to be a negative load, namely, transmitting the active load of the new energy source outwards.

Active load P of the new energy_LAs follows:

P_L＝P_LN+K_LP(f-f_N)。 (6)

in the formula, P_LIs the active load P of the ith node under the frequency f_LiThe constructed column vector. f is the frequency. f. of_NIs the nominal frequency. K_LPThe coefficient K of the active load power frequency static characteristic of the ith node_LPiThe constructed column vector. P_LNRated active load P for the ith node_LNiThe constructed column vector.

When in use_i∈LWhen is, P_LNiIs the rated active load of the ith node.

When i ∈ N, P_LNi＝P_prei+ΔP_prei。 (7)

In the formula, P_preiAnd predicting active power of the ith node of the new energy station. Delta P_preiAnd predicting an active power error for the ith node of the new energy station. And i is any node of the new energy station. And N is a node set of the new energy station. And L is a set of load nodes for searching the new energy station.

Reactive load Q of the new energy_LAs follows:

Q_L＝Q_LN+K_LQ(f-f_N)。 (8)

in the formula, Q_LRespectively the reactive load Q of the ith node under the frequency f_LiThe constructed column vector. Q_LNRated reactive load Q for the ith node_LNiThe constructed column vector. K_LQThe coefficient K of the power frequency static characteristic of the reactive load of the ith node_LQiThe constructed column vector. f. of_NIs the nominal frequency. f is the frequency.

4.5) dividing the active load P according to the original internal network, the original external network and the original boundary network nodes_LAnd reactive load Q_LThe following are respectively divided:

where LI represents the original internal network load node. K_LPIs the active negative of the ith nodeStatic characteristic coefficient K of charge power frequency_LPiThe constructed column vector. P_LNRated active load P for the ith node_LNiThe constructed column vector. P_LBThe active load for the original network boundary. P_LEThe original external network is loaded with power. P_LIThe original internal network is loaded with power.

Where LI represents the original internal network load node. Q_LNRated reactive load Q for the ith node_LNiThe constructed column vector. K_LQThe coefficient K of the power frequency static characteristic of the reactive load of the ith node_LQiThe constructed column vector. Q_LBIs the original boundary network reactive load. Q_LEIs the original external network reactive load. Q_LIIs the original internal network reactive load.

4.6) substituting the original external network load with the static frequency characteristic in the formula 9 and the formula 10 into the equivalent load of the formula 5 and the formula 6, thereby obtaining the equivalent active load and the equivalent reactive load with the static frequency characteristic. The method mainly comprises the following steps:

4.6.1) setting the parameter A₁Parameter A₂Parameter A₃And parameter A₄And calculating the parameter A in turn₁Parameter A₂Parameter A₃And parameter A₄。

A₁＝H_{_real}P_{LN_LE}-H_{_imag}Q_{LN_LE}。 (11)

In the formula, H_{_real}Is the real part of the intermediate parameter H. P_{LN_LE}The equivalent rated active load of the external network. Q_{LN_LE}The equivalent rated reactive load of the external network. H_{_imag}Is the imaginary part of the intermediate parameter H.

A₂＝H_{_imag}P_{LN_LE}+H_{_real}Q_{LN_LE}。 (12)

In the formula, H_{_imag}Is the imaginary part of the intermediate parameter H. P_{LN_LE}The equivalent rated active load of the external network. Q_{LN_LE}The equivalent rated reactive load of the external network. H_{_real}Is the real part of the intermediate parameter H.

A₃＝H_{_real}K_{LP_LE}-H_{_imag}K_{LQ_LE}。 (13)

In the formula, H_{_real}Is the real part of the intermediate parameter H. K_{LP_LE}The active load power frequency static characteristic coefficient K of the ith node in the external network_LPiThe constructed column vector. K_{LQ_LE}The coefficient K of the reactive load power frequency static characteristic of the ith node in the external network_LQiThe constructed column vector. H_{_imag}Is the imaginary part of the intermediate parameter H.

A₄＝H_{_imag}K_{LP_LE}+H_{_real}K_{LQ_LE}。 (14)

In the formula, H_{_imag}Is the imaginary part of the intermediate parameter H. K_{LP_LE}The active load power frequency static characteristic coefficient K of the ith node in the external network_LPiThe constructed column vector. K_{LQ_LE}The coefficient K of the reactive load power frequency static characteristic of the ith node in the external network_LQiThe constructed column vector. H_{_real}Is the imaginary part of the intermediate parameter H.

4.6.2) according to parameter A₃And parameter A₄Calculating power frequency static characteristic coefficient K of equivalent active load_{Leq_P}Power frequency static characteristic coefficient K of sum equivalent reactive load_{Leq_Q}。

Equivalent active load power frequency static characteristic coefficient K_{Leq_P}As follows:

K_{Leq_p}＝K_{LP_LB}-U_{LB_diag_real}A₃+U_{LB_diag_imag}A₄。 (15)

in the formula, K_{LP_LB}Active load power frequency static characteristic coefficient K of ith node of boundary network_{LPi_LB}The constructed column vector. U shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The real parts of the elements form a matrix. A. the₃Is a set parameter. A. the₄Is a set parameter. U shape_{LB_diag_imag}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The imaginary part of the element constitutes a matrix.

Equivalent reactive load power frequency static characteristic coefficient K_{Leq_Q}As follows:

K_{Leq_Q}＝K_{LQ_LB}-U_{LB_diag_real}A₄-U_{LB_diag_imag}A₃。 (16)

in the formula, K_{LQ_LB}The coefficient K of the power frequency static characteristic of the reactive load of the ith node of the boundary network_{LQi_LB}The constructed column vector. U shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The real parts of the elements form a matrix. A. the₃Is a set parameter. A. the₄Is a set parameter. U shape_{LB_diag_imag}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The imaginary part of the element constitutes a matrix.

4.6.3) according to the parameter A₁And parameter A₂Calculating equivalent rated active load P_{Leq_LN}Rated reactive load Q of sum equivalent_{Leq_LN}。

Equivalent rated active load P_{Leq_LN}As follows:

P_{Leq_LN}＝P_{LN_LB}-U_{LB_diag_real}A₁+U_{LB_diag_imag}A₂。 (17)

in the formula, P_{LN_LB}Is the equivalent rated active load of the boundary network. A. the₁Is a set parameter. A. the₂Is a set parameter. U shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The real parts of the elements form a matrix. U shape_{LB_diag_imag}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The imaginary part of the element constitutes a matrix.

Equivalent rated reactive load Q_{Leq_LN}As follows:

Q_{Leq_LN}＝Q_{LN_LB}-U_{LB_diag_real} A₂-U_{LB_diag_imag} A₁。 (18)

in the formula, Q_{LN_LB}Is the equivalent rated reactive load of the boundary network. U shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The real parts of the elements form a matrix. U shape_{LB_diag_imag}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The imaginary part of the element constitutes a matrix. A. the₁Is a set parameter. A. the₂Is a set parameter.

4.6.4) calculating the equivalent active load P_LeqSum equivalent reactive load Q_Leq。

Equivalent active load P_LeqAs follows:

P_Leq＝P_{Leq_LN}+K_{Leq_P}(f-f_N)。 (19)

in the formula, P_{Leq_LN}Is the equivalent rated active load. f is the frequency. f. of_NIs the nominal frequency. K_{Leq_P}The power frequency static characteristic coefficient is the equivalent power load.

Equivalent reactive load Q_LeqAs follows:

Q_Leq＝Q_{Leq_LN}+K_{Leq_Q}(f-f_N)。 (20)

in the formula, Q_{Leq_LN}The load is equivalent rated reactive load. f is the frequency. f. of_NIs the nominal frequency. Q_{Leq_P}The power frequency static characteristic coefficient is equivalent reactive load.

5) And calculating the static frequency characteristic of the equivalent generator according to the equivalent power network model.

Further, the main steps of calculating the static frequency characteristic of the equivalent generator are as follows:

5.1) calculating the Current I of the equivalent Generator node Geq_Geq. The method mainly comprises the following steps:

5.1.1) calculating the original network generator node injection current I_G：

In the formula I_GEIs the original external network generator node current. I is_GIIs the original internal network generator node current.

U_GEIs the original external network generator node voltage. U shape_GIIs the original external network generator voltage. U shape_LEIs the original external network voltage. U shape_LBIs the original boundary network voltage. U shape_LIIs the original internal network voltage.

Y_GG(GE)(GE)The admittance submatrix corresponding to the generator node in the original external network.

Y_GG(GI)(GI)The admittance submatrix corresponding to the generator node in the original internal network.

Y_GL(GE)(LE)And the admittance submatrices are corresponding to the generator nodes in the original external network and the nodes of the original external network.

Y_GL(GE)(LB)The method is characterized in that generator nodes are taken as corresponding rows and original boundary network nodes are taken as corresponding columns in an original external network, and therefore an admittance submatrix is generated.

GE is the original external network generator node. The GI is the original internal network generator node. GL is the original border network generator node. LI is the original internal network node. LB is the original border network node. The LE is the original external network node.

5.1.2) obtaining the original external network generator node voltage U according to the formula 21_GE. The original external network generator node voltage U_GEAs follows:

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

admittance submatrix Y corresponding to generator nodes in original external network_GG(GE)(GE)The inverse matrix of (c). I is_GEIs the generator node current in the original external network. U shape_LEIs the original external network voltage. U shape_LBIs the original boundary network voltage. Y is_GL(GE)(LE)In the original network, generator nodes of the original external network are taken as corresponding rows and original external network nodes are taken as corresponding columns, and therefore an admittance submatrix is generated. Y is_GL(GE)(LB)In the original network, generator nodes of the original external network are taken as corresponding rows, and original boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated.

5.1.3) obtaining equivalent generator node voltage U according to a static equivalence method based on consistency of power flow and sensitivity_Geq. The equivalent generator node voltage U_GeqAs follows:

in the formula of U_GEIs the original external network generator node voltage.

In the equivalent network, an admittance submatrix Y 'is generated by taking equivalent load nodes as corresponding rows and equivalent generator nodes as corresponding columns'_LGThe inverse matrix of (c). Y is_LGThe load nodes are used as corresponding rows and the generator nodes are used as corresponding columns in the original network, and therefore the admittance submatrix is generated. Y is_LLAnd the admittance submatrix is corresponding to the load node in the original external network.

For said admittance submatrix Y_LLThe inverse matrix of (c). LB is the original boundary load node. LE is original outer net load node. GE is the original external network generator node. Gep is an equivalent generator node.

5.1.4) calculating the injection current I 'of the generator node in the equivalent network'_G. Generator node injection current I 'in equivalent network'_GAs follows:

of formula (II) to (III)'_GG(Geq)(Geq)And obtaining the admittance submatrix corresponding to the generator node in the equivalent external network. Y is_GG(GI)(GI)The admittance submatrix corresponding to the generator node in the original internal network. U shape_GIIs the original external network generator voltage. U shape_GeqIs the equivalent network generator node voltage. Y'_GL(Geq)(LB)In the equivalent external network, equivalent generator nodes are taken as corresponding rows and equivalent boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated. Y'_GL(GI)(LB)In the equivalent network, generator nodes of an equivalent internal network are taken as corresponding rows, and equivalent boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated. Y'_GL(GI)(LI)In the equivalent network, generator nodes of the equivalent internal network are taken as corresponding rows and equivalent internal network nodes are taken as corresponding columns, so that the admittance submatrix is generated. U shape_LIIs the original internal network voltage. U shape_LBIs the original boundary network voltage.

5.1.5) from equation 24, the current I at the equivalent generator node Geq is obtained_Geq. Current I of the equivalent generator node Geq_GeqAs follows:

of formula (II) to (III)'_GG(Geq)(Geq)And obtaining the admittance submatrix corresponding to the generator node in the equivalent external network. Y is_LGThe load nodes are used as corresponding rows and the generator nodes are used as corresponding columns in the original network, and therefore the admittance submatrix is generated. Y is_LLAnd the admittance submatrix is corresponding to the load node in the original external network.

For said admittance submatrix Y_LLThe inverse matrix of (c). LB is the original boundary load node. LE is original outer net load node. GE is the original external network generator node. U shape_LBIs the original boundary network voltage. E_GEIs the original external network generator node voltage.

5.2) calculating to obtain the voltage U of the equivalent generator node_Geq. The method mainly comprises the following steps:

5.2.1) setting a constant matrix C, a constant matrix F and a constant matrix D.

The constant matrix C is shown below:

in the formula, Y_LLAnd the admittance submatrix is corresponding to the load node in the original external network.

For said admittance submatrix Y_LLThe inverse matrix of (c). LB is the original boundary load node. LE is original outer net load node. GE is the original external network generator node. Y is_LGThe load nodes are used as corresponding rows and the generator nodes are used as corresponding columns in the original network, and therefore the admittance submatrix is generated.

The constant matrix F is shown below:

The constant matrix D is as follows:

5.2.2) voltage U of the equivalent generator node according to the constant matrix C, the constant matrix F and the constant matrix D_GeqAs follows:

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

for outer net generator power matrix S_GEThe companion matrix of (a). The matrix C, the matrix F and the matrix D are respectively set constant matrixes. U shape_LBIs the original boundary network voltage.

5.3) calculating the equivalent generator output S_Geq. Equivalent generator output S_GeqAs follows:

in the formula I_{Geq_diag}Is composed of_GeqA diagonal matrix as a main diagonal element.

For the diagonal matrix I_{Geq_diag}The companion matrix of (a). U shape_GEQIs the voltage at the equivalent generator node.

5.4) according to the equivalent generator output S_GeqSum equivalent generator power S_GETo obtain the equivalent generator output S_GeqSum equivalent generator power S_GEThe analytic relationship of (1):

in the formula, the matrix C, the matrix F, and the matrix D are respectively set constant matrices.

For the diagonal matrix I_{Geq_diag}The companion matrix of (a). U shape_LBIs the original boundary network voltage.

For outer net generator power matrix S_GEThe companion matrix of (a).

5.5) according to the equivalent generator output S_GeqSum equivalent generator power S_GEThe equivalent generator active power P is obtained by analyzing the relation_Geq. The method mainly comprises the following steps:

5.5.1) setting the intermediate parameter H₁Intermediate parameter H₂Intermediate parameter H₂₁Intermediate parameter H₂₂Intermediate parameter H₂₃Intermediate parameter H₂₄Intermediate parameter H₂₅And an intermediate parameter H₂₆。

The intermediate parameter H₁As follows:

H₁＝I_{Geq_diag_real}C_real+I_{Geq_diag_imag}C_imag。 (32)

in the formula I_{Geq_diag_real}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The real parts of the elements form a matrix. I is_{Geq_diag_imag}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The imaginary part of the element constitutes a matrix. C_realA matrix formed by the real parts of the elements of the constant matrix C. C_imagBeing elements of a constant matrix CThe imaginary part constitutes a matrix.

The intermediate parameter H₂₁As follows:

H₂₁＝-I_{Geq_diag_real}C_imag-I_{Geq_diag_imag}C_real。 (33)

in the formula I_{Geq_diag_real}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The real parts of the elements form a matrix. I is_{Geq_diag_imag}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The imaginary part of the element constitutes a matrix. C_realA matrix formed by the real parts of the elements of the constant matrix C. C_imagA matrix formed by the imaginary parts of the elements of the constant matrix C.

The intermediate parameter H₂₂As follows:

in the formula, Y_{GG(GE)(GE)_real}A matrix formed by the real parts of the admittance submatrix elements corresponding to the generator nodes in the original external network. Y is_{GG(GE)(GE)_imag}A matrix formed by the imaginary parts of the admittance submatrix elements corresponding to the generator nodes in the original external network. U shape_{GE_imag}For the original external network generator node voltage U_GEThe imaginary part of (c). U shape_{GE_real}For the original external network generator node voltage U_GEThe real part of (a). U shape_{LE_real}For the original external network node voltage U_LEThe real part of (a). U shape_{LE_imag}For the original external network node voltage U_LEThe imaginary part of (c). Y is_{GL(GE)(LE)_imag}As an admittance sub-matrix Y_GL(GE)(LE)The imaginary part of the element constitutes a matrix. Y is_{GL(GE)(LE)_real}As an admittance sub-matrix Y_GL(GE)(LE)The real parts of the elements form a matrix.

The intermediate parameter H₂₃As follows:

in the formula, Y_{GG(GE)(GE)_real}Admittance submatrix Y corresponding to generator nodes in original external network_GG(GE)(GE)The real parts of the elements form a matrix. Y is_{GG(GE)(GE)_imag}Admittance submatrix Y corresponding to generator nodes in original external network_GG(GE)(GE)The imaginary part of the element constitutes a matrix. U shape_{GE_imag}For the original external network generator node voltage U_GEThe imaginary part of (c). U shape_{GE_real}For the original external network generator node voltage U_GEThe real part of (a). U shape_{LE_real}For the original external network node voltage U_LEThe real part of (a). U shape_{LE_imag}For the original external network node voltage U_LEThe imaginary part of (c). Y is_{GL(GE)(LE)_imag}As an admittance sub-matrix Y_GL(GE)(LE)The imaginary part of the element constitutes a matrix. Y is_{GL(GE)(LE)_real}As an admittance sub-matrix Y_GL(GE)(LE)The real parts of the elements form a matrix.

The intermediate parameter H₂₄As follows:

H₂₄＝-I_{Geq_diag_real}F_real+I_{Geq_diag_imag}F_imag。 (36)

in the formula I_{Geq_diag_real}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The real parts of the elements form a matrix. I is_{Geq_diag_imag}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The imaginary part of the element constitutes a matrix. F_realA matrix formed by the real parts of the elements of the constant matrix F. F_imagA matrix formed by the imaginary parts of the elements of the constant matrix F.

The intermediate parameter H₂₅As follows:

H₂₅＝I_{Geq_diag_real}F_imag-I_{Geq_diag_imag}F_real。 (37)

in the formula I_{Geq_diag_real}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The real parts of the elements form a matrix. I is_{Geq_diag_imag}Is composed of_GeqDiagonal as a primary diagonal elementMatrix I_{Geq_diag}The imaginary part of the element constitutes a matrix. F_realA matrix formed by the real parts of the elements of the constant matrix F. F_imagA matrix formed by the imaginary parts of the elements of the constant matrix F.

The intermediate parameter H₂₆As follows:

H₂₆＝-I_{Geq_diag_real}D_real-I_{Geq_diag_imag}D_imag。 (38)

in the formula I_{Geq_diag_real}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The real parts of the elements form a matrix. I is_{Geq_diag_imag}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The imaginary part of the element constitutes a matrix. D_realA matrix formed by the real parts of the elements of the constant matrix D. D_imagA matrix formed by the imaginary parts of the elements of the constant matrix D.

In the formula, H₂₁、H₂₂、H₂₃、H₂₄、H₂₅And H₂₆Respectively, the set intermediate parameters. Y is_{GL(GE)(LB)_imag}As an admittance sub-matrix Y_GL(GE)(LB)The imaginary part of the element constitutes a matrix. Y is_{GL(GE)(LB)_real}As an admittance sub-matrix Y_GL(GE)(LB)The real parts of the elements form a matrix. U shape_{GE_diag_real}Representing main diagonal elements as external network generator node voltages U_GEDiagonal matrix U of_{GE_diag}The real parts of the elements form a matrix. U shape_{GE_diag_imag}Representing main diagonal elements as external network generator node voltages U_GEDiagonal matrix U of_{GE_diag}The imaginary part of the element constitutes a matrix. U shape_{LB_imag}For the original border network node voltage U_LBThe imaginary part of (c). U shape_{LB_real}For the original border network node voltage U_LBThe real part of (a).

5.5.2) according to the set intermediate parameter H₁Intermediate parameter H₂Intermediate parameter H₂₁Intermediate parameter H₂₂Intermediate parameter H₂₃Intermediate parameter H₂₄Intermediate parameter H₂₅And an intermediate parameter H₂₆To obtain the equivalent generator active power P_Geq。

The equivalent generator active power P_GeqAs follows:

P_Geq＝H₁P_GE+H₂。 (40)

in the formula, H₁And H₂Respectively, the set intermediate parameters. P_GEThe active power of the external network node is equivalent.

5.6) active Power P of the Generator_GThe static frequency characteristic of (a) is as follows:

P_G＝P_Gmax-K_{G_diag}(f-f_Gmax)。 (41)

in the formula, P_GIs the active power output P of the generator from the ith node at the frequency f_GiThe constructed column vector. P_GmaxIs the maximum active power output P of the generator from the ith node_GmaxiThe constructed column vector. K_GFor the power frequency static characteristic coefficient K of the generator from the ith node_GiThe constructed column vector. f. of_GmaxFor the frequency inflection point f when the generator of the ith node no longer has primary frequency modulation capability_GmaxiThe constructed column vector. f is the frequency. K_{G_diag}Is composed of a power frequency static characteristic coefficient K_GAs a matrix of main diagonal elements.

5.7) dividing the active power P of the generator according to the internal network and the external network_GThe division is as follows:

in the formula, P_{Gmax_GI}Maximum active output P of generator at ith node of internal network_GmaxiThe constructed column vector. P_{Gmax_GE}The maximum active output P of the generator of the ith node of the external network_GmaxiThe constructed column vector. K_{G_GI}Power frequency of generator for ith node of internal networkCoefficient of static characteristics K_GiThe constructed column vector. K_{G_GE}Power frequency static characteristic coefficient K of generator for ith node of external network_GiThe constructed column vector. f. of_{Gmax_GI}Frequency inflection point f when generator no longer has primary frequency modulation capability for ith node of internal network_GmaxiThe constructed column vector. f. of_{Gmax_GE}Representing a column vector consisting of the frequency inflection points when the external network generator no longer has primary modulation capability. f is the frequency. P_GIThe equivalent internal network generator active power. P_GEThe equivalent external network generator active power.

5.8) active Power P of the external network Generator to have static frequency characteristics_GESubstituting into the active power of the equivalent generator to obtain the active power output P of the equivalent generator with the static frequency characteristic_Geq。

The equivalent generator active power output P with the static frequency characteristic_GeqAs follows:

P_Geq＝P_{Gmax_eq}-K_Geqf'。 (43)

wherein the column vector f' is an AND P composed of a state variable, i.e., a frequency f_GeqThe column vectors of the same dimension. K_GeqThe power frequency static characteristic coefficient of the equivalent network generator is obtained. P_{Gmax_eq}For the original maximum active output information P of the external network generator_{Gmax_GE}Equivalent information therein

Wherein, the original maximum active output information P of the external network generator_{Gmax_GE}Equivalent information P therein_{Gmax_eq}As follows:

P_{Gmax_eq}＝H₁P_{Gmax_GE}+H₂+K_Geqf_{Gmax_GE}。 (44)

in the formula, H₁And H₂Respectively, the set intermediate parameters. f. of_{Gmax_GE}Is a column vector consisting of the frequency inflection points when the external generator no longer has primary modulation capability. K_GeqThe power frequency static characteristic coefficient of the equivalent network generator is obtained.

Equivalent network generator power frequency static characteristic coefficient K_GeqAs follows:

K_Geq＝H₁K_{G_GE}。 (45)

in the formula, K_{G_GE}Power frequency static characteristic coefficient K of generator for ith node of external network_GiThe constructed column vector. H₁Is the set intermediate parameter. K_{G_GE}The power frequency static characteristic coefficient of the external grid generator is shown.

The technical effect of the present invention is undoubted. The invention provides an equivalence method considering the static frequency characteristics of an external network aiming at the deficiency of equivalence of the existing static topology method. The invention utilizes the equivalent method of the consistency of the tidal current and the sensitivity, improves the equivalence of the external network load and the external network generator, and introduces the equivalence of the static frequency characteristics of the external network load and the external network generator into the equivalence. The method effectively keeps the consistency of the trend and the sensitivity, effectively keeps the static frequency characteristic of the external network, and more truly reflects the actual operation characteristic of the power system.

Drawings

Fig. 1 is an equivalent network diagram.

Detailed Description

The present invention is further illustrated by the following examples, but it should not be construed that the scope of the above-described subject matter is limited to the following examples. Various substitutions and alterations can be made without departing from the technical idea of the invention and the scope of the invention is covered by the present invention according to the common technical knowledge and the conventional means in the field.

Example 1:

referring to fig. 1, an equivalent method considering the static frequency characteristics of an external network mainly includes the following steps:

1) and establishing an original power network model.

Further, the original power network model mainly includes an original external network E, an original network boundary, and an original internal network.

The original external network has E external network nodes.

There are B border nodes in the original network border.

The original internal network has I intranet nodes.The I intranet nodes comprise 1 balanced intranet node and I-1 unbalanced intranet nodes. The total number of elements in the original internal network is N. The number of available elements in the original internal network is N_f。

The basic parameters of the power network mainly comprise element parameters in an original network, an original network topology structure and a load flow calculation result at an approaching moment.

y_eqGijRepresenting the original external network at the equivalentAnd (3) equal-value branch admittance among generator nodes.

y_eqBijRepresenting the branch admittance between the original external network and the generator at the boundary nodes of the equivalence.

y_eqBiRepresenting the isoleg admittance of the original external network between the boundary node and the isogenerator.

And after the equivalent parameters are calculated, drawing an equivalent network map according to the equivalent parameters.

For said admittance submatrix Y_LLThe inverse matrix of (c).

in the formula, S_LBIs the original boundary load power. S_LEFor loading power to the original external network。U_{LB_diag}Representing main diagonal elements as boundary node voltages U_LBThe diagonal matrix of (a). U shape_{LE_diag}Representing the main diagonal element as the external load node voltage U_LEThe diagonal matrix of (a).

For said admittance submatrix

The companion matrix of (a).

4.3.1) setting an intermediate parameter H:

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

for said admittance submatrix

The companion matrix of (a).

For said admittance submatrix Y_LLThe companion matrix of (a). LB is the original boundary load node. LE is original outer net load node. U shape_{LE_diag}Representing the main diagonal element as the external load node voltage U_LEThe diagonal matrix of (a).

4.3.2) equivalent active load P_LeqAs follows:

4.3.3) equivalent reactive load Q_LeqAs follows:

Active load P of the new energy_LAs follows:

P_L＝P_LN+K_LP(f-f_N)。 (6)

in the formula, P_LIs the active load P of the ith node under the frequency f_LiThe constructed column vector. f is the frequency. f. of_NIs the nominal frequency. K_LPIs composed ofActive load power frequency static characteristic coefficient K of ith node_LPiThe constructed column vector. P_LNRated active load P for the ith node_LNiThe constructed column vector.

When i ∈ L, P_LNiIs the rated active load of the ith node.

When i ∈ N, P_LNi＝P_prei+ΔP_prei。 (7)

Reactive load Q of the new energy_LAs follows:

Q_L＝Q_LN+K_LQ(f-f_N)。 (8)

where LI represents the original internal network load node. K_LPThe coefficient K of the active load power frequency static characteristic of the ith node_LPiThe constructed column vector. P_LNRated active load P for the ith node_LNiThe constructed column vector. P_LBThe active load for the original network boundary. P_LEIs the original exteriorThe network active load. P_LIThe original internal network is loaded with power.

4.6.1) calculating the parameter A₁Parameter A₂Parameter A₃And parameter A₄。

A₁＝H_{_real}P_{LN_LE}-H_{_imag}Q_{LN_LE}。 (11)

In the formula, H_{_real}Is the real part of the intermediate parameter H. P_{LN_LE}The equivalent rated active load of the external network. Q_{LN_LE}The equivalent rated reactive load of the external network.

A₂＝H_{_imag}P_{LN_LE}+H_{_real}Q_{LN_LE}。 (12)

In the formula, H_{_imag}Is the imaginary part of the intermediate parameter H. P_{LN_LE}The equivalent rated active load of the external network. Q_{LN_LE}The equivalent rated reactive load of the external network.

A₃＝H_{_real}K_{LP_LE}-H_{_imag}K_{LQ_LE}。 (13)

In the formula, H_{_real}Is the real part of the intermediate parameter H. K_{LP_LE}For the ith section in the external networkActive load power frequency static characteristic coefficient K of point_LPiThe constructed column vector. K_{LQ_LE}The coefficient K of the reactive load power frequency static characteristic of the ith node in the external network_LQiThe constructed column vector. H_{_imag}Is the imaginary part of the intermediate parameter H.

A₄＝H_{_imag}K_{LP_LE}+H_{_real}K_{LQ_LE}。 (14)

K_{Leq_p}＝K_{LP_LB}-U_{LB_diag_real}A₃+U_{LB_diag_imag}A₄。 (15)

in the formula, K_{LP_LB}Active load power frequency static characteristic coefficient K of ith node of boundary network_{LPi_LB}The constructed column vector. U shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The real parts of the elements form a matrix. A. the₃Is a set parameter. A. the₄Is a set parameter.

K_{Leq_Q}＝K_{LQ_LB}-U_{LB_diag_real}A₄-U_{LB_diag_imag}A₃。 (16)

in the formula, K_{LQ_LB}The coefficient K of the power frequency static characteristic of the reactive load of the ith node of the boundary network_{LQi_LB}The constructed column vector. U shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}The real parts of the elements form a matrix. A. the₃Is a set parameter. A. the₄Is a set parameter.

Equivalent rated active load P_{Leq_LN}As follows:

P_{Leq_LN}＝P_{LN_LB}-U_{LB_diag_real}A₁+U_{LB_diag_imag}A₂。 (17)

Equivalent rated reactive load Q_{Leq_LN}As follows:

Q_{Leq_LN}＝_{QLN_LB}-U_{LB_diag_real} A₂-U_{LB_diag_imag} A₁。 (18)

Equivalence ofActive load P_LeqAs follows:

P_Leq＝P_{Leq_LN}+K_{Leq_P}(f-f_N)。 (19)

Equivalent reactive load Q_LeqAs follows:

Q_Leq＝Q_{Leq_LN}+K_{Leq_Q}(f-f_N)。 (20)

5.1.1) calculating the original network generator node injection current I_G：

Y_GG(GE)(GE)The admittance submatrix corresponding to the generator node in the original external network. Y is_GG(GI)(GI)Admittance for generator node correspondence in original internal networkA sub-matrix. Y is_GL(GE)(LE)And the admittance submatrices are corresponding to the generator nodes in the original external network and the nodes of the original external network. Y is_GL(GE)(LB)The method is characterized in that generator nodes are taken as corresponding rows and original boundary network nodes are taken as corresponding columns in an original external network, and therefore an admittance submatrix is generated.

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

in the formula of U_GEIs the original external network generator node voltage.

of formula (II) to (III)'_GG(Geq)(Geq)And obtaining the admittance submatrix corresponding to the generator node in the equivalent external network. Y is_GG(GI)(GI)The admittance submatrix corresponding to the generator node in the original internal network. U shape_GIIs the original external network generator voltage. U shape_GeqIs the equivalent network generator node voltage. Y'_GL(Geq)(LB)In the equivalent external network, equivalent generator nodes are taken as corresponding rows and equivalent boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated. Y'_GL(GI)(LB)In the equivalent network, generator nodes of an equivalent internal network are taken as corresponding rows, and equivalent boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated. Y'_GL(GI)(LI)For an equivalent network, with an equivalent internal networkThe generator nodes are corresponding rows, the equivalent internal network nodes are corresponding columns, and therefore the admittance submatrix is generated. U shape_LIIs the original internal network voltage. U shape_LBIs the original boundary network voltage.

The constant matrix C is shown below:

The constant matrix F is shown below:

The constant matrix D is as follows:

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

Is outsideNetwork generator power matrix S_GEThe companion matrix of (a).

The intermediate parameter H₁As follows:

H₁＝I_{Geq_diag_real}C_real+I_{Geq_diag_imag}C_imag。 (32)

The intermediate parameter H₂₁As follows:

H₂₁＝-I_{Geq_diag_real}C_imag-I_{Geq_diag_imag}C_real。 (33)

The intermediate parameter H₂₂As follows:

The intermediate parameter H₂₃As follows:

in the formula, Y_{GG(GE)(GE)_real}Admittance submatrix Y corresponding to generator nodes in original external network_GG(GE)(GE)The real parts of the elements form a matrix. Y is_{GG(GE)(GE)_imag}Admittance submatrix Y corresponding to generator nodes in original external network_GG(GE)(GE)The imaginary part of the element constitutes a matrix. U shape_{GE_imag}For the original external network generator node voltage U_GEThe imaginary part of (c). U shape_{GE_real}For the original external network generator node voltage U_GEThe real part of (a). U shape_{LE_real}For the original external network node voltage U_LEThe real part of (a). U shape_{LE_imag}For the original external network node voltage U_LEThe imaginary part of (c). Y is_{GL(GE)(LE)_imag}As an admittance sub-matrix Y_GL(GE)(LE)The imaginary part of the element constitutes a matrix. Y is_{GL(GE)(LE)_real}As an admittance sub-matrix Y_GL(GE)(LE)Element(s)The real part of (a).

The intermediate parameter H₂₄As follows:

H₂₄＝-I_{Geq_diag_real}F_real+I_{Geq_diag_imag}F_imag。 (36)

The intermediate parameter H₂₅As follows:

H₂₅＝I_{Geq_diag_real}F_imag-I_{Geq_diag_imag}F_real。 (37)

The intermediate parameter H₂₆As follows:

H₂₆＝-I_{Geq_diag_real}D_real-I_{Geq_diag_imag}D_imag。 (38)

in the formula I_{Geq_diag_real}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The real parts of the elements form a matrix. I is_{Geq_diag_imag}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}The imaginary part of the element constitutes a matrix. D_realA matrix formed by the real parts of the elements of the constant matrix D. D_imagBeing elements of a constant matrix DThe imaginary part constitutes a matrix.

The equivalent generator active power P_GeqAs follows:

P_Geq＝H₁P_GE+H₂。 (40)

P_G＝P_Gmax-K_{G_diag}(f-f_Gmax)。 (41)

in the formula (I), the compound is shown in the specification,P_Gis the active power output P of the generator from the ith node at the frequency f_GiThe constructed column vector. P_GmaxIs the maximum active power output P of the generator from the ith node_GmaxiThe constructed column vector. K_GFor the power frequency static characteristic coefficient K of the generator from the ith node_GiThe constructed column vector. f. of_GmaxFor the frequency inflection point f when the generator of the ith node no longer has primary frequency modulation capability_GmaxiThe constructed column vector. f is the frequency. K_{G_diag}Is composed of a power frequency static characteristic coefficient K_GAs a matrix of main diagonal elements.

in the formula, P_{Gmax_GI}Maximum active output P of generator at ith node of internal network_GmaxiThe constructed column vector. P_{Gmax_GE}The maximum active output P of the generator of the ith node of the external network_GmaxiThe constructed column vector. K_{G_GI}Power frequency static characteristic coefficient K of generator for ith node of internal network_GiThe constructed column vector. K_{G_GE}Power frequency static characteristic coefficient K of generator for ith node of external network_GiThe constructed column vector. f. of_{Gmax_GI}Frequency inflection point f when generator no longer has primary frequency modulation capability for ith node of internal network_GmaxiThe constructed column vector. f. of_{Gmax_GE}Representing a column vector consisting of the frequency inflection points when the external network generator no longer has primary modulation capability. f is the frequency. P_GIThe equivalent internal network generator active power. P_GEThe equivalent external network generator active power.

Said frequency has a static frequencyEquivalent generator active power output P of characteristic_GeqAs follows:

P_Geq＝P_{Gmax_eq}-K_Geqf'。 (43)

wherein the column vector f' is an AND P composed of a state variable, i.e., a frequency f_GeqThe column vectors of the same dimension. K_GeqThe power frequency static characteristic coefficient of the equivalent network generator is obtained. P_{Gmax_eq}For the original maximum active output information P of the external network generator_{Gmax_GE}Equivalent information within.

P_{Gmax_eq}＝H₁P_{Gmax_GE}+H₂+K_Geqf_{Gmax_GE}。 (44)

K_Geq＝H₁K_{G_GE}。 (45)

Example 2:

an experiment for verifying an equivalent method considering static frequency characteristics of an external network mainly comprises the following steps:

1) and establishing a test system.

In the IEEE9 node system, the system is divided into an external network, a border node, and an internal network: an external node: node 2, node 3, node 6 and node 7. Boundary nodes: node 5 and node 9. Internal nodes: node 1 and node 4, where node 1 is a balanced node. In the IEEE118 node system, the system is also divided into an external network, a border node, and an internal network: an external node: node 80, node 83 to node 112. Boundary nodes: node 81 and node 82. Internal nodes: node 1 to node 79, node 113 to node 118, with node 69 being a balanced node.

In both test systems, the correlation coefficient between the outer net loads was taken to be 0.1. And the power frequency static characteristic coefficient per unit values of the conventional active load and the conventional reactive load are respectively 2 and-1.5. And the power frequency static characteristic coefficient per unit value of the generator at the unbalanced node and the balanced node is respectively 20 and 25. The rated frequency of the system is 50Hz, and the upper and lower limits of the frequency are 50.2Hz and 49.8Hz respectively.

2) Different comparison models

In order to verify the correctness and the effectiveness of the equivalent method considering the static frequency characteristics of the external network, the following 4 load flow calculation methods are adopted for carrying out static safety analysis and comparison:

m0: load flow calculation method based on original network (reference method).

M1: the invention provides an equivalent load flow calculation method.

M2: the equivalent method based on the consistency of the power flow and the sensitivity (namely 'StaticEvalintMethodPasedConponentParalyticationRepression and Sensiwitness Consistence') is an equivalent power flow calculation method only considering the sensitivity of an external network.

M3: and the load flow calculation method is based on a method of equating the external network to be a balance node, a PV node or a PQ node. Using an absolute error index e₁And relative error index e₂And measuring the error of the M1-M3 method and the M0 method.

3) Simulation verification of static frequency characteristic of equivalent method

The internal network load of the IEEE9 node system and the IEEE118 node system is increased by 12% and 8% in the same proportion respectively, and static security analysis is performed by utilizing M0-M3 respectively.

Table 1 lists the error analysis results of the system frequency and the maximum error branch active power.

As can be seen from Table 1, as the load on the intranet increases, the original network-based M0 method and the textThe proposed M1 method has no out-of-limit frequency, and the difference between the two is small, the maximum absolute error e₁Only 0.03 HZ. However, the frequencies of the M2 and M3 models have been out of limit, with the maximum absolute error e₁Respectively reaching 0.06Hz and 1.11 Hz. Meanwhile, the branch with the largest active power error is selected for comparison (the node 9 system is a 1-4 branch, and the node 118 system is a 77-82 branch). For the M1 model proposed by the invention, the maximum relative error e of the branch active power₂Only 2.5%, while the maximum relative error e of the M2, M3 methods₂Respectively up to 18.4% and 430.92%. Therefore, the method can effectively retain the static frequency characteristic information of the external network and improve the static security analysis precision. Value and e in Table 1₁The units of (b) correspond to the units of f, P, respectively, Hz, MW. e.g. of the type₂The unit of (c) is%.

TABLE 1IEEE9 node system, IEEE118 node system frequency and error analysis results of maximum error branch active power

Therefore, the method effectively keeps the consistency of the trend and the sensitivity, effectively keeps the static frequency characteristic of the external network, and more truly reflects the actual operation characteristic of the power system.

Claims

1. An equivalence method considering static frequency characteristics of an external network is characterized by comprising the following steps:

1) establishing an original power network model;

2) inputting basic parameters of the power network in the original power network model;

3) establishing an equivalent power network model by using an equivalent method of consistency of power flow and sensitivity;

the equivalent power network model is established by the following steps:

3.1) calculating equivalent parameters in the equivalent power network model by using an equivalent method of consistency of power flow and sensitivity; the equivalence parameter comprises an equivalence branch guideNano y_eqGij、y_eqBiAnd y_eqBijEquivalent ground branch admittance y_eqBi0Node voltage amplitude U of sum-equivalent generator_GeqBi；

y_eqGijRepresenting the admittance of an equivalent branch between nodes of an equivalent generator of an original external network; y is_eqBijRepresenting the branch admittance between the boundary nodes of the equivalence of the original external network and the generator; y is_eqBiRepresenting the admittance of an equivalent branch between a boundary node and an equivalent generator of an original external network;

3.2) establishing an equivalent power network model according to the equivalent parameters and the original power network model;

4) calculating the static frequency characteristic of the equivalent load according to the equivalent power network model;

the steps of calculating the static frequency characteristic of the equivalent load are as follows:

4.1) calculating the equivalent load current I_Leq(ii) a Equivalent load current I_LeqAs follows:

in the formula I_LBLoad current of the original boundary network; i is_LEIs the load current of the original external network; y is_LLAn admittance submatrix corresponding to a load node in an original external network; LB is an original boundary load node; LE is original outer net load node;

for said admittance submatrix Y_LLThe inverse matrix of (d);

4.2) according to the equivalent load current I_LeqCalculating the equivalent load power S_Leq(ii) a Equivalent load power S_LeqAs follows:

in the formula, S_LBIs the original boundary load power; s_LEIs the original outer net load power; u shape_{LB_diag}Representing main diagonal elements as boundary node voltages U_LBA diagonal matrix of (a); u shape_{LE_diag}Representing the main diagonal element as the external load node voltage U_LEA diagonal matrix of (a);

for said admittance submatrix

The companion matrix of (a);

for said admittance submatrix Y_LLThe companion matrix of (a); LB is an original boundary load node; LE is original outer net load node;

4.3) according to the equivalent load power S_LeqCalculating the equivalent active load P_LeqSum equivalent reactive load Q_Leq(ii) a The method comprises the following steps:

4.3.1) setting an intermediate parameter H:

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

for said admittance submatrix

The companion matrix of (a);

for said admittance submatrix Y_LLThe companion matrix of (a); LB is an original boundary load node; LE is original outer net load node; u shape_{LE_diag}Indicating a major diagonal element as being externally negativeCharge node voltage U_LEA diagonal matrix of (a);

4.3.2) equivalent active load P_LeqAs follows:

in the formula, P_LBActive load for original network boundary; p_LEIs the original external network active load; u shape_{LB_diag_real}Is a diagonal matrix U_{LB_diag}A matrix of real parts of the elements; u shape_{LB_diag_imag}Is a diagonal matrix U_{LB_diag}A matrix of imaginary parts of the elements; h is an intermediate parameter; q_LEIs the original outer net reactive load; u shape_{LB_diag}Representing main diagonal elements as boundary node voltages U_LBA diagonal matrix of (a);

4.3.3) equivalent reactive load Q_LeqAs follows:

in the formula, Q_LBIs the original boundary reactive load; q_LEIs the original outer net reactive load; u shape_{LB_diag_real}Is a diagonal matrix U_{LB_diag}A matrix of real parts of the elements; u shape_{LB_diag_imag}Is a diagonal matrix U_{LB_diag}A matrix of imaginary parts of the elements; h is an intermediate parameter; u shape_{LB_diag}Representing main diagonal elements as boundary node voltages U_LBA diagonal matrix of (a); p_LEIs the original external network active load;

4.4) setting a new energy station; setting N as the new energy station node set; setting L as the new energy station load node set; the new energy comprises wind and light; setting the new energy source to be a negative load, namely, the active load of the new energy source is transmitted outwards;

active load P of the new energy_LAs follows:

P_L＝P_LN+K_LP(f-f_N)； (6)

in the formula, P_LIs the active load P of the ith node under the frequency f_LiA constructed column vector; f is the frequency; f. of_NIs a rated frequency; k_LPThe coefficient K of the active load power frequency static characteristic of the ith node_LPiA constructed column vector; p_LNRated active load P for the ith node_LNiA constructed column vector;

when i ∈ L, P_LNiRated active load of the ith node;

when i ∈ N, P_LNi＝P_prei+ΔP_prei； (7)

In the formula, P_preiPredicting active power for the ith node of the new energy station; delta P_preiPredicting an active power error for the ith node of the new energy station; i is any node of the new energy station; n is a node set of the new energy station; l is a set of load nodes for searching the new energy station;

reactive load Q of the new energy_LAs follows:

Q_L＝Q_LN+K_LQ(f-f_N)； (8)

in the formula, Q_LRespectively the reactive load Q of the ith node under the frequency f_LiA constructed column vector; q_LNRated reactive load Q for the ith node_LNiA constructed column vector; k_LQThe coefficient K of the power frequency static characteristic of the reactive load of the ith node_LQiA constructed column vector; f. of_NIs a rated frequency; f is the frequency;

wherein LI represents the original internal network load node; k_LPIs active from the ith nodeCoefficient of static characteristics of load power frequency K_LPiA constructed column vector; p_LNRated active load P for the ith node_LNiA constructed column vector; p_LBActive load for original network boundary; p_LEIs the original external network active load; p_LIIs the original internal network active load; LB is an original boundary load node; LE is original outer net load node;

wherein LI represents the original internal network load node; q_LNRated reactive load Q for the ith node_LNiA constructed column vector; k_LQThe coefficient K of the power frequency static characteristic of the reactive load of the ith node_LQiA constructed column vector; q_LBIs the original boundary network reactive load; q_LEIs the original external network reactive load; q_LIIs the original internal network reactive load;

4.6) substituting the original external network load with the static frequency characteristic in the formula (9) and the formula (10) into the equivalent load of the formula (5) and the formula (6) so as to obtain the equivalent active load and the equivalent reactive load with the static frequency characteristic; the method comprises the following steps:

4.6.1) setting the parameter A₁Parameter A₂Parameter A₃And parameter A₄And calculating A sequentially₁Parameter A₂Parameter A₃And parameter A₄；

A₁＝H_{_real}P_{LN_LE}-H_{_imag}Q_{LN_LE}； (11)

In the formula, H_{_real}Is the real part of the intermediate parameter H; p_{LN_LE}The equivalent rated active load of the external network; q_{LN_LE}The equivalent rated reactive load of the external network; h_{_imag}Is the imaginary part of the intermediate parameter H;

A₂＝H_{_imag}P_{LN_LE}+H_{_real}Q_{LN_LE}； (12)

in the formula, H_{_imag}Is the imaginary part of the intermediate parameter H; p_{LN_LE}The equivalent rated active load of the external network; q_{LN_LE}The equivalent rated reactive load of the external network; h_{_real}Is the real part of the intermediate parameter H;

A₃＝H_{_real}K_{LP_LE}-H_{_imag}K_{LQ_LE}； (13)

in the formula, H_{_real}Is the real part of the intermediate parameter H; k_{LP_LE}The active load power frequency static characteristic coefficient K of the ith node in the external network_LPiA constructed column vector; k_{LQ_LE}The coefficient K of the reactive load power frequency static characteristic of the ith node in the external network_LQiA constructed column vector; h_{_imag}Is the imaginary part of the intermediate parameter H;

A₄＝H_{_imag}K_{LP_LE}+H_{_real}K_{LQ_LE}； (14)

in the formula, H_{_imag}Is the imaginary part of the intermediate parameter H; k_{LP_LE}The active load power frequency static characteristic coefficient K of the ith node in the external network_LPiA constructed column vector; k_{LQ_LE}The coefficient K of the reactive load power frequency static characteristic of the ith node in the external network_LQiA constructed column vector; h_{_real}Is the imaginary part of the intermediate parameter H;

4.6.2) according to parameter A₃And parameter A₄Calculating power frequency static characteristic coefficient K of equivalent active load_{Leq_P}Power frequency static characteristic coefficient K of sum equivalent reactive load_{Leq_Q}；

K_{Leq_p}＝K_{LP_LB}-U_{LB_diag_real}A₃+U_{LB_diag_imag}A₄； (15)

in the formula, K_{LP_LB}Active load power frequency static characteristic coefficient K of ith node of boundary network_{LPi_LB}A constructed column vector; u shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}Of elementsA matrix of real parts; a. the₃Is a set parameter; a. the₄Is a set parameter; u shape_{LB_diag_imag}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}A matrix of imaginary parts of the elements;

K_{Leq_Q}＝K_{LQ_LB}-U_{LB_diag_real}A₄-U_{LB_diag_imag}A₃； (16)

in the formula, K_{LQ_LB}The coefficient K of the power frequency static characteristic of the reactive load of the ith node of the boundary network_{LQi_LB}A constructed column vector; u shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}A matrix of real parts of the elements; a. the₃Is a set parameter; a. the₄Is a set parameter; u shape_{LB_diag_imag}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}A matrix of imaginary parts of the elements;

4.6.3) according to the parameter A₁And parameter A₂Calculating equivalent rated active load P_{Leq_LN}Rated reactive load Q of sum equivalent_{Leq_LN}；

Equivalent rated active load P_{Leq_LN}As follows:

P_{Leq_LN}＝P_{LN_LB}-U_{LB_diag_real}A₁+U_{LB_diag_imag}A₂； (17)

in the formula, P_{LN_LB}The equivalent rated active load of the boundary network; a. the₁Is a set parameter; a. the₂Is a set parameter; u shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}A matrix of real parts of the elements; u shape_{LB_diag_imag}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}A matrix of imaginary parts of the elements;

equivalent rated reactive load Q_{Leq_LN}As follows:

Q_{Leq_LN}＝Q_{LN_LB}-U_{LB_diag_real}A₂-U_{LB_diag_imag}A₁； (18)

in the formula, Q_{LN_LB}Is the equivalent rated reactive load of the boundary network; u shape_{LB_diag_real}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}A matrix of real parts of the elements; u shape_{LB_diag_imag}Representing main diagonal elements as boundary node voltages U_LBDiagonal matrix U of_{LB_diag}A matrix of imaginary parts of the elements; a. the₁Is a set parameter; a. the₂Is a set parameter;

4.6.4) calculating the equivalent active load P_LeqSum equivalent reactive load Q_Leq；

Equivalent active load P_LeqAs follows:

P_Leq＝P_{Leq_LN}+K_{Leq_P}(f-f_N)； (19)

in the formula, P_{Leq_LN}Is the equivalent rated active load; f is the frequency; f. of_NIs a rated frequency; k_{Leq_P}The power frequency static characteristic coefficient is equivalent active load;

equivalent reactive load Q_LeqAs follows:

Q_Leq＝Q_{Leq_LN}+K_{Leq_Q}(f-f_N)； (20)

in the formula, Q_{Leq_LN}Is an equivalent rated reactive load; f is the frequency; f. of_NIs a rated frequency; q_{Leq_P}The power frequency static characteristic coefficient is equivalent reactive load;

5) calculating the static frequency characteristic of the equivalent generator according to the equivalent power network model;

the steps of calculating the static frequency characteristic of the equivalent generator are as follows:

5.1) calculating the Current I of the equivalent Generator node Geq_Geq(ii) a The method comprises the following steps:

5.1.1) calculating the original network generator node injection current I_G：

In the formula I_GEIs the original external network generator node current; i is_GIIs the original internal network generator node current;

U_GEis the original external network generator node voltage; u shape_GIIs the original external network generator voltage; u shape_LEIs the original external network voltage; u shape_LBIs the original boundary network voltage; u shape_LIIs the original internal network voltage;

Y_GG(GE)(GE)the admittance submatrix corresponding to the generator node in the original external network;

Y_GG(GI)(GI)the admittance submatrix corresponding to the generator node in the original internal network;

Y_GL(GE)(LE)the admittance submatrixes corresponding to the generator nodes in the original external network and the original external network nodes;

Y_GL(GE)(LB)in an original external network, generator nodes are taken as corresponding rows and original boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated;

GE is an original external network generator node; GI is the original internal network generator node; GL is an original boundary network generator node; LI is an original internal network node; LB is an original boundary network node; LE is original external network node;

5.1.2) obtaining the original external network generator node voltage U according to the formula (21)_GE(ii) a The original external network generator node voltage U_GEAs follows:

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

admittance submatrix Y corresponding to generator nodes in original external network_GG(GE)(GE)The inverse matrix of (d); i is_GEIs the generator node current in the original external network; u shape_LEIs the original external network voltage; u shape_LBIs the original boundary network voltage; y is_GL(GE)(LE)In the original network, generator nodes of the original external network are taken as corresponding rows and original external network nodes are taken as corresponding columns, so that an admittance submatrix is generated; y is_GL(GE)(LB)In the original network, generator nodes of the original external network are taken as corresponding rows and original boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated;

5.1.3) obtaining equivalent generator node voltage U according to a static equivalence method based on consistency of power flow and sensitivity_Geq(ii) a The equivalent generator node voltage U_GeqAs follows:

in the formula of U_GEIs the original external network generator node voltage;

in the equivalent network, an admittance submatrix Y 'is generated by taking equivalent load nodes as corresponding rows and equivalent generator nodes as corresponding columns'_LGThe inverse matrix of (d); y is_LGIn the original network, load nodes are used as corresponding rows, generator nodes are used as corresponding columns, and therefore an admittance submatrix is generated; y is_LLAn admittance submatrix corresponding to a load node in an original external network;

for said admittance submatrix Y_LLThe inverse matrix of (d); LB is an original boundary load node; LE is; GE is an original external network generator node; gep is an equivalent generator node;

5.1.4) calculating the injection current I 'of the generator node in the equivalent network'_G(ii) a Generator node injection current I 'in equivalent network'_GAs shown below：

Of formula (II) to (III)'_GG(Geq)(Geq)The admittance submatrix corresponding to the generator node in the equivalent external network; y is_GG(GI)(GI)The admittance submatrix corresponding to the generator node in the original internal network; u shape_GIIs the original external network generator voltage; u shape_GeqIs the equivalent network generator node voltage; y'_GL(Geq)(LB)In an equivalent external network, equivalent generator nodes are taken as corresponding rows and equivalent boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated; y'_GL(GI)(LB)In the equivalent network, generator nodes of an equivalent internal network are taken as corresponding rows, and equivalent boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated; y'_GL(GI)(LI)In the equivalent network, generator nodes of the equivalent internal network are taken as corresponding rows and equivalent internal network nodes are taken as corresponding columns, so that an admittance submatrix is generated; u shape_LIIs the original internal network voltage; u shape_LBIs the original boundary network voltage;

5.1.5) obtaining the current I of the equivalent generator node Geq according to equation (24)_Geq(ii) a Current I of the equivalent generator node Geq_GeqAs follows:

of formula (II) to (III)'_GG(Geq)(Geq)The admittance submatrix corresponding to the generator node in the equivalent external network; y is_LGIn the original network, load nodes are used as corresponding rows, generator nodes are used as corresponding columns, and therefore an admittance submatrix is generated; y is_LLAn admittance submatrix corresponding to a load node in an original external network;

for said admittance submatrix Y_LLThe inverse matrix of (d); LB is an original boundary load node; LE is original outer net load node; GE is an original external network generator node; u shape_LBIs the original boundary network voltage; e_GEIs the original external network generator node voltage;

5.2) calculating to obtain the voltage U of the equivalent generator node_Geq(ii) a The method comprises the following steps:

5.2.1) setting a constant matrix C, a constant matrix F and a constant matrix D;

the constant matrix C is shown below:

in the formula, Y_LLAn admittance submatrix corresponding to a load node in an original external network;

for said admittance submatrix Y_LLThe inverse matrix of (d); LB is an original boundary load node; LE is original outer net load node; GE is an original external network generator node; y is_LGIn the original network, load nodes are used as corresponding rows, generator nodes are used as corresponding columns, and therefore an admittance submatrix is generated;

the constant matrix F is shown below:

for said admittance submatrix Y_LLThe inverse matrix of (d); LB is an original boundary load node; LE is original outer net load node; GE is an original external network generator node; y is_LGIn the original network, the load node is used as a corresponding row, and the generator node is used as a pairAnd (2) applying the obtained array to generate an admittance submatrix;

admittance submatrix Y corresponding to generator nodes in original external network_GG(GE)(GE)The inverse matrix of (d); y is_GL(GE)(LB)In the original network, generator nodes of the original external network are taken as corresponding rows and original boundary network nodes are taken as corresponding columns, so that an admittance submatrix is generated;

the constant matrix D is as follows:

for said admittance submatrix Y_LLThe inverse matrix of (d); LB is an original boundary load node; LE is original outer net load node; GE is an original external network generator node; y is_LGIn the original network, load nodes are used as corresponding rows, generator nodes are used as corresponding columns, and therefore an admittance submatrix is generated; y is_GL(GE)(LE)In the original network, generator nodes of the original external network are taken as corresponding rows and original external network nodes are taken as corresponding columns, so that an admittance submatrix is generated;

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

for outer net generator power matrix S_GEThe companion matrix of (a); the matrix C, the matrix F and the matrix D are respectively set constant matrixes; u shape_LBIs the original boundary network voltage;

5.3) calculating the equivalent generator output S_Geq(ii) a Equivalent generator output S_GeqAs follows:

in the formula I_{Geq_diag}Is composed of_GeqA diagonal matrix as a primary diagonal element;

for the diagonal matrix I_{Geq_diag}The companion matrix of (a); u shape_GEQIs the voltage of the equivalent generator node;

in the formula, a matrix C, a matrix F and a matrix D are respectively set constant matrixes;

for the diagonal matrix I_{Geq_diag}The companion matrix of (a); u shape_LBIs the original boundary network voltage;

for outer net generator power matrix S_GEThe companion matrix of (a);

5.5) according to the equivalent generator output S_GeqSum equivalent generator power S_GEThe equivalent generator active power P is obtained by analyzing the relation_Geq(ii) a The method comprises the following steps:

5.5.1) setting the intermediate parameter H₁Intermediate parameter H₂Intermediate parameter H₂₁Intermediate parameter H₂₂Intermediate parameter H₂₃Intermediate parameter H₂₄Intermediate parameter H₂₅And an intermediate parameter H₂₆；

The intermediate parameter H₁As follows:

H₁＝I_{Geq_diag_real}C_real+I_{Geq_diag_imag}C_imag； (32)

in the formula I_{Geq_diag_real}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}A matrix of real parts of the elements; i is_{Geq_diag_imag}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}A matrix of imaginary parts of the elements; c_realA matrix formed by real parts of elements of a constant matrix C; c_imagA matrix formed by imaginary parts of elements of a constant matrix C;

the intermediate parameter H₂₁As follows:

H₂₁＝-I_{Geq_diag_real}C_imag-I_{Geq_diag_imag}C_real； (33)

the intermediate parameter H₂₂As follows:

in the formula, Y_{GG(GE)(GE)_real}Formation of real part of admittance submatrix elements corresponding to generator nodes in original external networkA matrix of (a); y is_{GG(GE)(GE)_imag}A matrix formed by imaginary parts of admittance submatrix elements corresponding to generator nodes in an original external network; u shape_{GE_imag}For the original external network generator node voltage U_GEAn imaginary part of (d); u shape_{GE_real}For the original external network generator node voltage U_GEThe real part of (a); u shape_{LE_real}For the original external network node voltage U_LEThe real part of (a); u shape_{LE_imag}For the original external network node voltage U_LEAn imaginary part of (d); y is_{GL(GE)(LE)_imag}As an admittance sub-matrix Y_GL(GE)(LE)A matrix of imaginary parts of the elements; y is_{GL(GE)(LE)_real}As an admittance sub-matrix Y_GL(GE)(LE)A matrix of real parts of the elements;

the intermediate parameter H₂₃As follows:

in the formula, Y_{GG(GE)(GE)_real}Admittance submatrix Y corresponding to generator nodes in original external network_GG(GE)(GE)A matrix of real parts of the elements; y is_{GG(GE)(GE)_imag}Admittance submatrix Y corresponding to generator nodes in original external network_GG(GE)(GE)A matrix of imaginary parts of the elements; u shape_{GE_imag}For the original external network generator node voltage U_GEAn imaginary part of (d); u shape_{GE_real}For the original external network generator node voltage U_GEThe real part of (a); u shape_{LE_real}For the original external network node voltage U_LEThe real part of (a); u shape_{LE_imag}For the original external network node voltage U_LEAn imaginary part of (d); y is_{GL(GE)(LE)_imag}As an admittance sub-matrix Y_GL(GE)(LE)A matrix of imaginary parts of the elements; y is_{GL(GE)(LE)_real}As an admittance sub-matrix Y_GL(GE)(LE)A matrix of real parts of the elements;

the intermediate parameter H₂₄As follows:

H₂₄＝-I_{Geq_diag_real}F_real+I_{Geq_diag_imag}F_imag； (36)

in the formula I_{Geq_diag_real}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}A matrix of real parts of the elements; i is_{Geq_diag_imag}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}A matrix of imaginary parts of the elements; f_realA matrix formed by real parts of elements of a constant matrix F; f_imagA matrix formed by imaginary parts of elements of a constant matrix F;

the intermediate parameter H₂₅As follows:

H₂₅＝I_{Geq_diag_real}F_imag-I_{Geq_diag_imag}F_real； (37)

the intermediate parameter H₂₆As follows:

H₂₆＝-I_{Geq_diag_real}D_real-I_{Geq_diag_imag}D_imag； (38)

in the formula I_{Geq_diag_real}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}A matrix of real parts of the elements; i is_{Geq_diag_imag}Is composed of_GeqDiagonal matrix I as main diagonal elements_{Geq_diag}A matrix of imaginary parts of the elements; d_realA matrix formed by real parts of elements of a constant matrix D; d_imagA matrix formed by imaginary parts of elements of a constant matrix D;

in the formula (I), the compound is shown in the specification,H₂₁、H₂₂、H₂₃、H₂₄、H₂₅and H₂₆Respectively set intermediate parameters; y is_{GL(GE)(LB)_imag}As an admittance sub-matrix Y_GL(GE)(LB)A matrix of imaginary parts of the elements; y is_{GL(GE)(LB)_real}As an admittance sub-matrix Y_GL(GE)(LB)A matrix of real parts of the elements; u shape_{GE_diag_real}Representing main diagonal elements as external network generator node voltages U_GEDiagonal matrix U of_{GE_diag}A matrix of real parts of the elements; u shape_{GE_diag_imag}Representing main diagonal elements as external network generator node voltages U_GEDiagonal matrix U of_{GE_diag}A matrix of imaginary parts of the elements; u shape_{LB_imag}For the original border network node voltage U_LBAn imaginary part of (d); u shape_{LB_real}For the original border network node voltage U_LBThe real part of (a);

5.5.2) according to the set intermediate parameter H₁Intermediate parameter H₂Intermediate parameter H₂₁Intermediate parameter H₂₂Intermediate parameter H₂₃Intermediate parameter H₂₄Intermediate parameter H₂₅And an intermediate parameter H₂₆To obtain the equivalent generator active power P_Geq；

The equivalent generator active power P_GeqAs follows:

P_Geq＝H₁P_GE+H₂； (40)

in the formula, H₁And H₂Respectively set intermediate parameters; p_GEThe active power of the equivalent external network node is obtained;

P_G＝P_Gmax-K_{G_diag}(f-f_Gmax)； (41)

in the formula, P_GIs the active power output P of the generator from the ith node at the frequency f_GiA constructed column vector; p_GmaxIs the maximum active power output P of the generator from the ith node_GmaxiA constructed column vector; k_GFor the power-frequency-static characteristics of the generator from the ith nodeCoefficient K_GiA constructed column vector; f. of_GmaxFor the frequency inflection point f when the generator of the ith node no longer has primary frequency modulation capability_GmaxiA constructed column vector; f is the frequency; k_{G_diag}Is composed of a power frequency static characteristic coefficient K_GA matrix as a main diagonal element;

in the formula, P_{Gmax_GI}Maximum active output P of generator at ith node of internal network_GmaxiA constructed column vector; p_{Gmax_GE}The maximum active output P of the generator of the ith node of the external network_GmaxiA constructed column vector; k_{G_GI}Power frequency static characteristic coefficient K of generator for ith node of internal network_GiA constructed column vector; k_{G_GE}Power frequency static characteristic coefficient K of generator for ith node of external network_GiA constructed column vector; f. of_{Gmax_GI}Frequency inflection point f when generator no longer has primary frequency modulation capability for ith node of internal network_GmaxiA constructed column vector; f. of_{Gmax_GE}A column vector representing a frequency inflection point when the external network generator no longer has primary frequency modulation capability; f is the frequency; p_GIThe equivalent internal network generator active power; p_GEThe equivalent external network generator active power;

5.8) active Power P of the external network Generator to have static frequency characteristics_GESubstituting into the active power of the equivalent generator to obtain the active power output P of the equivalent generator with the static frequency characteristic_Geq；

P_Geq＝P_{Gmax_eq}-K_Geqf'； (43)

wherein the column vector f' is a state variable, i.e. the frequency fOf structure and P_GeqA column vector of the same dimension; k_GeqThe power-frequency static characteristic coefficient of the equivalent network generator is obtained; p_{Gmax_eq}For the original maximum active output information P of the external network generator_{Gmax_GE}Equivalent information therein

P_{Gmax_eq}＝H₁P_{Gmax_GE}+H₂+K_Geqf_{Gmax_GE}； (44)

in the formula, H₁And H₂Respectively set intermediate parameters; f. of_{Gmax_GE}Is a column vector formed by frequency inflection points when the external generator no longer has primary frequency modulation capability; k_GeqThe power-frequency static characteristic coefficient of the equivalent network generator is obtained;

K_Geq＝H₁K_{G_GE}； (45)

in the formula, K_{G_GE}Power frequency static characteristic coefficient K of generator for ith node of external network_GiA constructed column vector; h₁Is a set intermediate parameter; k_{G_GE}The power frequency static characteristic coefficient of the external grid generator is shown.

2. An equivalence method considering the static frequency characteristics of the external network according to claim 1, wherein: the basic parameters of the power network comprise element parameters in an original network, an original network topological structure and a load flow calculation result at an approaching moment;

the element parameters in the original network comprise the admittance to the ground of all nodes, the connection load power of all nodes, the impedance of all lines, the susceptance to the ground of all lines, the constraint condition of line transmission power, the impedance of a transformer, the admittance to the ground of the transformer, the transformation ratio of the transformer, the constraint condition of transformer transmission power, the output of a generator, the constraint condition of the output of the generator, the power-frequency static characteristic coefficient of the generator and the power-frequency static characteristic coefficient of the load;

the original network topology structure comprises the connection relation of all nodes and the network partition condition;

and the near moment power flow calculation result comprises a node admittance matrix, a node voltage matrix and a node injection current matrix.