CN103823998A - Weak cross section determination method taking influence of network topology changes on power transmission capacity into consideration - Google Patents

Abstract

The invention provides a weak cross section determination method taking influence of network topology changes on the power transmission capacity into consideration. The weak cross section determination method comprises the following steps of calculating the static stable power transmission capacity of power transmission cross sections in which the network topology changes are taken into consideration, calculating the load rate of the power transmission cross sections, carrying out screening on the power transmission cross sections according to the degree of influence of the network topology changes on the power transmission capacity, and determining the weak cross section. According to the weak cross section determination method taking influence of the network topology changes on the power transmission capacity into consideration, evaluation is carried out on the normal operation state of the given cross sections and the state, generated after the network topology changes happen, of the given cross sections, the stability margin and the power transmission capacity in the normal state are evaluated according to the static power transmission capacity, the degree of influence on the system power transmission capacity and the system margin after the network topology changes happen is evaluated in a power transmission cross section line N-1 disconnection mode and multi-circuit line N-M disconnection mode, the degree of weakness of the cross sections is comprehensively evaluated, and the weak cross section is recognized.

Description

Consider the weak section determination method of network topology change on ability to transmit electricity impact

Technical field

The present invention relates to a kind of method of determining, be specifically related to a kind of weak section determination method of network topology change on ability to transmit electricity impact of considering.

Background technology

In Power System Off-line computational analysis, the section of care is determined substantially, but the weak degree of section changes along with the variation of actual conditions, need to constantly analyze judgement, therefore in calculated off-line analysis, has accumulated rich experience.

Determine weak transmission cross-section, in actual application, conventionally adopt a large amount of methods of calculating, for example, carry out a large amount of transient stabilities and calculate, find section, the oscillation center section etc. of easy unstability.To the section of being concerned about, conventionally need to adopt the transmit electricity calculating of the limit of electromechanical transient simulation software, consider the factor such as transient state, dynamic stability and overload of system, calculate the ability to transmit electricity of section, if the nargin with respect to current real power is less, it is more crucial section.Steady state stability limit is also one of important method of assessment section ability to transmit electricity, in real system, steady state stability limit is conventionally higher, therefore the method that does not conventionally adopt steady state stability limit to calculate, only just can carry out the calculating of static limit for weaker long distance transmission line or interconnection.But steady state stability limit and the transient stability limit, system stability level have close relationship, remain one of important method of assessment section vulnerability.

Also good method without comparison of the weak degree that judges section in on-line system, can use for reference calculated off-line and analyze experience, but online higher to the requirement of time, therefore can not depend on a large amount of calculating, therefore needs to study.

Summary of the invention

In order to overcome above-mentioned the deficiencies in the prior art, the invention provides a kind of weak section determination method of network topology change on ability to transmit electricity impact of considering, for given section, respectively for normal operating condition, state after network topology change is assessed, adopt stability margin and ability to transmit electricity under static ability to transmit electricity assessment normal condition, adopt transmission cross-section circuit N-1 to disconnect, influence degree to system ability to transmit electricity and nargin after the mode critic network structural change that multi circuit transmission lines N-M disconnects, the weak degree of last comprehensive evaluation section, identify weak section.

In order to realize foregoing invention object, the present invention takes following technical scheme:

The invention provides a kind of weak section determination method of network topology change on ability to transmit electricity impact of considering, said method comprising the steps of:

Step 1: calculate the transmission cross-section steady stability ability to transmit electricity of considering network topology change;

Step 2: the load factor of calculating transmission cross-section;

Step 3: according to network topology change, the influence degree of ability to transmit electricity is screened transmission cross-section, determine weak section.

In described step 1, transmission cross-section comprises single channel transmission cross-section and hyperchannel transmission cross-section; The steady stability ability to transmit electricity of described single channel transmission cross-section and hyperchannel transmission cross-section is used respectively P _maxwith

represent.

The steady stability ability to transmit electricity P of described single channel transmission cross-section _maxcomputation process is as follows:

1) impedance matrix of calculating single channel transmission cross-section two side gussets 1 and node 2, has:

$Z_{\mathrm{eq}}=\left[\begin{array}{cc}{Z}_{11}& Z_{12}\\ Z_{21}& Z_{22}\end{array}\right]---\left(1\right)$

Wherein, Z _eqrepresent the impedance matrix of single channel transmission cross-section two side gussets 1 and node 2, Z ₁₁, Z ₂₂be respectively the self-impedance of node 1, node 2, Z ₁₂and Z ₂₁be the transimpedance of node 1 and node 2;

2) admittance matrix of computing node 1 and node 2 correspondences, has:

$Y_{\mathrm{eq}}=Z_{\mathrm{eq}}^{-1}=\left[\begin{array}{cc}{Y}_{11}& Y_{12}\\ Y_{21}& Y_{22}\end{array}\right]---\left(2\right)$

Wherein, Y _eqrepresent the admittance matrix of node 1 and node 2 correspondences, Y ₁₁, Y ₂₂be respectively the self-admittance of node 1, node 2, Y ₁₂and Y ₂₁be the transimpedance of node 1 and node 2;

3) equivalent impedance of calculating single channel transmission cross-section, has:

$X_{\mathrm{\Σ}}=-\frac{1}{Y_{11}+Y_{12}}-\frac{1}{Y_{22}+Y_{21}}+\frac{1}{Y_{12}}---\left(3\right)$

Wherein, X _Σthe equivalent impedance of single channel transmission cross-section;

4) voltage of supposition node 1 and node 2 is 1, the steady stability ability to transmit electricity P of single channel transmission cross-section _maxcalculate according to following formula:

$P_{\max }=\frac{E_1{E}_2}{X_{\mathrm{\Σ}}}=\frac{1}{X_{\mathrm{\Σ}}}---\left(4\right)$

Wherein, E ₁and E ₂represent respectively the voltage of node 1 and node 2.

Be directed to hyperchannel transmission cross-section, all according to the following process computation transmission cross-section steady stability ability to transmit electricity under normal condition, under N-1 state and under N-M state respectively

wherein N represents hyperchannel transmission cross-section total loop number, and M represents the feeder number of a passage in hyperchannel transmission cross-section;

1) add up the node number of all transmission cross-section passages both sides, adopt the node of same node point number to merge;

2) impedance matrix of calculating hyperchannel transmission cross-section, has:

$Z_{\mathrm{eq}}^{\′}=\left[\begin{array}{cccccc}{Z}_{11}& Z_{12}& \·& \·& \·& Z_{1n}\\ Z_{21}& Z_{22}& .& .& .& Z_{2n}\\ .& .& & .& & .\\ .& .& & .& & .\\ .& .& & .& & .\\ Z_{n1}& Z_{n2}& .& .& .& Z_{\mathrm{nn}}\end{array}\right]---\left(5\right)$

Wherein,

represent the impedance matrix of single channel transmission cross-section, Z ₁₁, Z ₂₂..., Z _nnbe respectively node 1,2 ..., n self-impedance, Z ₁₂, Z ₂₁..., Z _1n, Z _n1for the internodal transimpedance of difference;

3) admittance matrix corresponding to computing node, has:

$Y_{\mathrm{eq}}^{\′}={Z_{\mathrm{eq}}^{\′}}^{-1}=\left[\begin{array}{cccccc}{Y}_{11}& Y_{12}& .& .& .& Y_{1n}\\ Y_{21}& Y_{22}& .& .& .& Y_{2n}\\ .& .& & .& & .\\ .& .& & .& & .\\ .& .& & .& & .\\ Y_{n1}& Y_{n2}& .& .& .& Y_{\mathrm{nn}}\end{array}\right]---\left(6\right)$

Wherein, represent admittance matrix corresponding to node, Y ₁₁, Y ₂₂..., Y _nnbe respectively node 1,2 ..., n self-admittance, Y ₁₂, Y ₂₁..., Y _1n, Y _n1for the internodal transimpedance of difference;

4) equivalent impedance of calculating hyperchannel transmission cross-section

In admittance matrix corresponding to described node, increase a line and row, then admittance matrix corresponding to node carried out to cancellation calculating, after calculating, obtain increasing the i.e. Equivalent admittance between two nodes of a line diagonal element

so equivalent impedance of hyperchannel transmission cross-section

be expressed as:

$X_{\mathrm{\Σ}}^{\′}=\frac{1}{y_{\mathrm{eq}}^{\′}}---\left(7\right)$

5) the steady stability ability to transmit electricity of hyperchannel transmission cross-section

be expressed as:

$P_{\max }^{\′}\frac{1}{X_{\mathrm{\Σ}}^{\′}}=y_{\mathrm{eq}}^{\′}---\left(8\right).$

In described step 2, the load factor of transmission cross-section represents have with η:

$\mathrm{\η}=\frac{P_{\mathrm{load}}}{P_{\max }}---\left(9\right)$

Wherein, P _loadrepresent the real power of transmission cross-section.

In described step 3, adopt following three cardinal rules to screen transmission cross-section, according to the load factor definite value of setting, adopt the mode debasing the standard step by step to determine final weak section;

(1), under normal condition, the transmission cross-section that load factor is higher should retain;

(2), under N-1 state, load factor changes greatly and higher should the retaining of N-1 back loading rate;

(3), under N-M state, load factor changes greatly and higher should the retaining of N-M back loading rate.

Compared with prior art, beneficial effect of the present invention is:

The method simple possible, the method for employing is that the expansion of basic theories method in complicated electric power system extended, method simple possible.

The method can be screened fast for a large amount of sections, and can consider that circuit disconnects the rear a large amount of calculating that derive sections that form and checks, and considers more comprehensive;

The method has adopted approximate computing method fast, can in the situation that guaranteeing certain precision, significantly improve computing velocity, has guaranteed the practicality under online condition.

Accompanying drawing explanation

Fig. 1 is simple two machine system schematic in the embodiment of the present invention;

Fig. 2 calculates the equivalent network schematic diagram that transmission cross-section two side gussets are port in the embodiment of the present invention;

Fig. 3 is the equivalent network schematic diagram that calculates the consideration both sides power supply that transmission cross-section two side gussets are port in the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

The invention provides a kind of weak section determination method of network topology change on ability to transmit electricity impact of considering, said method comprising the steps of:

Step 1: calculate the transmission cross-section steady stability ability to transmit electricity of considering network topology change;

Step 2: the load factor of calculating transmission cross-section;

Step 3: according to network topology change, the influence degree of ability to transmit electricity is screened transmission cross-section, determine weak section.

For simple two machine systems, as shown in Figure 1, suppose that the generator built-in potential of both sides can keep constant, both maximum exchange power are P _max, have:

$P_{\max }=\frac{E_1{E}_2}{X_{\mathrm{\Σ}}}=\frac{E_1{E}_2}{X_{s1}+X_L+X_{s2}}$

This formula has stricter theoretical foundation, can reflect to a certain extent the ability to transmit electricity of single system.From then on formula can be found out, except generator electromotive force, the system ability to transmit electricity of impact is mainly the equivalent reactance of system, and generator electromotive force part is decided by the voltage control capability of generator, and reaction component is also the reflection of system network architecture.

For practical large-scale electric system, can not realize by so simple computing formula the accurate evaluation of ability to transmit electricity.But the basic physical features of this formula reaction can be applied to the simple analysis of practical power systems equally, the size of equivalent reactance wherein can reflect the physical characteristics of actual electric network to a certain extent.Carry out the needs of rapid screening for the section of a large amount of search of reality, if power that can substantially qualitative reasonable reaction section is screened fast, reject most of unconcerned section, residue section is assessed in detail again, and to real system, application still has important value.

In described step 1, transmission cross-section comprises single channel transmission cross-section and hyperchannel transmission cross-section; The steady stability ability to transmit electricity of described single channel transmission cross-section and hyperchannel transmission cross-section is used respectively P _maxwith

represent.

The steady stability ability to transmit electricity P of described single channel transmission cross-section _maxcomputation process is as follows:

1) impedance matrix of calculating single channel transmission cross-section two side gussets 1 and node 2, has:

$Z_{\mathrm{eq}}=\left[\begin{array}{cc}{Z}_{11}& Z_{12}\\ Z_{21}& Z_{22}\end{array}\right]---\left(1\right)$

Wherein, Z _eqrepresent the impedance matrix of single channel transmission cross-section two side gussets 1 and node 2, Z ₁₁, Z ₂₂be respectively the self-impedance of node 1, node 2, Z ₁₂and Z ₂₁be the transimpedance of node 1 and node 2;

2) admittance matrix of computing node 1 and node 2 correspondences, has:

$Y_{\mathrm{eq}}=Z_{\mathrm{eq}}^{-1}=\left[\begin{array}{cc}{Y}_{11}& Y_{12}\\ Y_{21}& Y_{22}\end{array}\right]---\left(2\right)$

Wherein, Y _eqrepresent the admittance matrix of node 1 and node 2 correspondences, Y ₁₁, Y ₂₂be respectively the self-admittance of node 1, node 2, Y ₁₂and Y ₂₁be the transimpedance of node 1 and node 2;

3) equivalent impedance of calculating single channel transmission cross-section, has:

$X_{\mathrm{\Σ}}=-\frac{1}{Y_{11}+Y_{12}}-\frac{1}{Y_{22}+Y_{21}}+\frac{1}{Y_{12}}---\left(3\right)$

Wherein, X _Σthe equivalent impedance of single channel transmission cross-section;

4) voltage of supposition node 1 and node 2 is 1, the steady stability ability to transmit electricity P of single channel transmission cross-section _maxcalculate according to following formula:

$P_{\max }=\frac{E_1{E}_2}{X_{\mathrm{\Σ}}}=\frac{1}{X_{\mathrm{\Σ}}}---\left(4\right)$

Wherein, E ₁and E ₂represent respectively the voltage of node 1 and node 2.

To the appraisal procedure of section except needs are considered normal mode, also need to consider the impact after network topology change, because may produce considerable influence to the power of section after section part circuit disconnects, it may be the hiding factor that determines the weak program of section, but key factor, so network topology change need to be considered as an important index.

When section is carried out to above-mentioned equivalent calculation, need to carry out under normal condition, equivalent calculation under N-1 state and under N-M state, mainly according to the variation between three, critical failure is carried out to preliminary screening.

Equivalent calculation under normal condition

Under the complete condition of network section, carry out above-mentioned equivalent calculation, approximate treatment obtains whole equiva lent impedance, as the benchmark of follow-up consideration open-circuit line.

Equivalent calculation under N-1 state

Every interconnection in transmission cross-section is made respectively to N-1 successively to be disconnected, and take two end nodes of other interconnections as port, system is carried out to above-mentioned equivalent calculation, and the equivalent impedance after having calculated can change, and can reflect the ability to transmit electricity intensity of variation disconnecting behind a loop line road.

Equivalent calculation under N-M state

To containing the passway for transmitting electricity of double-circuit line or multi circuit transmission lines in section, disconnect this double-circuit line or multi circuit transmission lines, then calculate according to the method described above the equivalent impedance that other passage interconnection both sides are port.For actual electric network, if a section comprises many interconnections, disconnect a passage to impact is not necessarily very large generally, but under the few condition of interconnection, disconnect the variation that a passage may cause matter, become the key factor of restriction section power.

Be directed to hyperchannel transmission cross-section, all according to the following process computation transmission cross-section steady stability ability to transmit electricity under normal condition, under N-1 state and under N-M state respectively

wherein N represents hyperchannel transmission cross-section total loop number, and M represents the feeder number of a passage in hyperchannel transmission cross-section;

1) add up the node number of all transmission cross-section passages both sides, adopt the node of same node point number to merge;

2) impedance matrix of calculating hyperchannel transmission cross-section, has:

$Z_{\mathrm{eq}}^{\′}=\left[\begin{array}{cccccc}{Z}_{11}& Z_{12}& \·& \·& \·& Z_{1n}\\ Z_{21}& Z_{22}& .& .& .& Z_{2n}\\ .& .& & .& & .\\ .& .& & .& & .\\ .& .& & .& & .\\ Z_{n1}& Z_{n2}& .& .& .& Z_{\mathrm{nn}}\end{array}\right]---\left(5\right)$

Wherein,

represent the impedance matrix of single channel transmission cross-section, Z ₁₁, Z ₂₂..., Z _nnbe respectively node 1,2 ..., n self-impedance, Z ₁₂, Z ₂₁..., Z _1n, Z _n1for the internodal transimpedance of difference;

3) admittance matrix corresponding to computing node, has:

$Y_{\mathrm{eq}}^{\′}={Z_{\mathrm{eq}}^{\′}}^{-1}=\left[\begin{array}{cccccc}{Y}_{11}& Y_{12}& .& .& .& Y_{1n}\\ Y_{21}& Y_{22}& .& .& .& Y_{2n}\\ .& .& & .& & .\\ .& .& & .& & .\\ .& .& & .& & .\\ Y_{n1}& Y_{n2}& .& .& .& Y_{\mathrm{nn}}\end{array}\right]---\left(6\right)$

Wherein, represent admittance matrix corresponding to node, Y ₁₁, Y ₂₂..., Y _nnbe respectively node 1,2 ..., n self-admittance, Y ₁₂, Y ₂₁..., Y _1n, Y _n1for the internodal transimpedance of difference;

4) equivalent impedance of calculating hyperchannel transmission cross-section

In admittance matrix corresponding to described node, increase a line and row, then admittance matrix corresponding to node carried out to cancellation calculating, after calculating, obtain increasing the i.e. Equivalent admittance between two nodes of a line diagonal element

so equivalent impedance of hyperchannel transmission cross-section

be expressed as:

$X_{\mathrm{\Σ}}^{\′}=\frac{1}{y_{\mathrm{eq}}^{\′}}---\left(7\right)$

5) the steady stability ability to transmit electricity of hyperchannel transmission cross-section

be expressed as:

$P_{\max }^{\′}\frac{1}{X_{\mathrm{\Σ}}^{\′}}=y_{\mathrm{eq}}^{\′}---\left(8\right).$

In described step 2, the load factor of transmission cross-section represents have with η:

$\mathrm{\η}=\frac{P_{\mathrm{load}}}{P_{\max }}---\left(9\right)$

Wherein, P _loadrepresent the real power of transmission cross-section.

In described step 3, adopt following three cardinal rules to screen transmission cross-section, according to the load factor definite value of setting, adopt the mode debasing the standard step by step to determine final weak section;

(1), under normal condition, the transmission cross-section that load factor is higher should retain;

(2), under N-1 state, load factor changes greatly and higher should the retaining of N-1 back loading rate;

(3), under N-M state, load factor changes greatly and higher should the retaining of N-M back loading rate.

Based on above-mentioned several principles, can provide fast the section that needs concern, the concrete figure of merit adopting may have certain difference for different electrical networks, but can set certain value, adopts the mode debasing the standard step by step to search out the section of some scopes.

After weak section preliminary screening, now can adopt the methods such as steady state stability limit calculating to carry out the accurate calculating of section steady state stability limit, basic process is as follows:

Calculate the steady state stability limit of all sections, calculate steady stability nargin and can calculate the steady stability nargin that loses a loop line road simultaneously.

Calculate steady stability nargin, adopt steady state stability limit power and current power to calculate steady stability nargin

Carry out examination according to steady stability nargin, steady stability nargin is less is commonly referred to be weaker section, can be by all sections according to order sequence from small to large, set certain numerical value or select before several.

Finally should be noted that: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit, although the present invention is had been described in detail with reference to above-described embodiment, those of ordinary skill in the field are to be understood that: still can modify or be equal to replacement the specific embodiment of the present invention, and do not depart from any modification of spirit and scope of the invention or be equal to replacement, it all should be encompassed in the middle of claim scope of the present invention.

Claims (6)

1. consider the weak section determination method of network topology change on ability to transmit electricity impact, it is characterized in that: said method comprising the steps of:

Step 1: calculate the transmission cross-section steady stability ability to transmit electricity of considering network topology change;

Step 2: the load factor of calculating transmission cross-section;

Step 3: according to network topology change, the influence degree of ability to transmit electricity is screened transmission cross-section, determine weak section.

2. the weak section determination method of consideration network topology change according to claim 1 on ability to transmit electricity impact, is characterized in that: in described step 1, transmission cross-section comprises single channel transmission cross-section and hyperchannel transmission cross-section; The steady stability ability to transmit electricity of described single channel transmission cross-section and hyperchannel transmission cross-section is used respectively P _maxwith

represent.

3. the weak section determination method of consideration network topology change according to claim 2 on ability to transmit electricity impact, is characterized in that: the steady stability ability to transmit electricity P of described single channel transmission cross-section _maxcomputation process is as follows:

1) impedance matrix of calculating single channel transmission cross-section two side gussets 1 and node 2, has:

$Z_{\mathrm{eq}}=\left[\begin{array}{cc}{Z}_{11}& Z_{12}\\ Z_{21}& Z_{22}\end{array}\right]---\left(1\right)$

Wherein, Z _eqrepresent the impedance matrix of single channel transmission cross-section two side gussets 1 and node 2, Z ₁₁, Z ₂₂be respectively the self-impedance of node 1, node 2, Z ₁₂and Z ₂₁be the transimpedance of node 1 and node 2;

2) admittance matrix of computing node 1 and node 2 correspondences, has:

$Y_{\mathrm{eq}}=Z_{\mathrm{eq}}^{-1}=\left[\begin{array}{cc}{Y}_{11}& Y_{12}\\ Y_{21}& Y_{22}\end{array}\right]---\left(2\right)$

Wherein, Y _eqrepresent the admittance matrix of node 1 and node 2 correspondences, Y ₁₁, Y ₂₂be respectively the self-admittance of node 1, node 2, Y ₁₂and Y ₂₁be the transimpedance of node 1 and node 2;

3) equivalent impedance of calculating single channel transmission cross-section, has:

$X_{\mathrm{\Σ}}=-\frac{1}{Y_{11}+Y_{12}}-\frac{1}{Y_{22}+Y_{21}}+\frac{1}{Y_{12}}---\left(3\right)$

Wherein, X _Σthe equivalent impedance of single channel transmission cross-section;

4) voltage of supposition node 1 and node 2 is 1, the steady stability ability to transmit electricity P of single channel transmission cross-section _maxcalculate according to following formula:

$P_{\max }=\frac{E_1{E}_2}{X_{\mathrm{\Σ}}}=\frac{1}{X_{\mathrm{\Σ}}}---\left(4\right)$

Wherein, E ₁and E ₂represent respectively the voltage of node 1 and node 2.

4. the weak section determination method of consideration network topology change according to claim 2 on ability to transmit electricity impact, it is characterized in that: be directed to hyperchannel transmission cross-section, all according to the following process computation transmission cross-section steady stability ability to transmit electricity under normal condition, under N-1 state and under N-M state respectively

wherein N represents hyperchannel transmission cross-section total loop number, and M represents the feeder number of a passage in hyperchannel transmission cross-section;

1) add up the node number of all transmission cross-section passages both sides, adopt the node of same node point number to merge;

2) impedance matrix of calculating hyperchannel transmission cross-section, has:

$Z_{\mathrm{eq}}^{\′}=\left[\begin{array}{cccccc}{Z}_{11}& Z_{12}& \·& \·& \·& Z_{1n}\\ Z_{21}& Z_{22}& .& .& .& Z_{2n}\\ .& .& & .& & .\\ .& .& & .& & .\\ .& .& & .& & .\\ Z_{n1}& Z_{n2}& .& .& .& Z_{\mathrm{nn}}\end{array}\right]---\left(5\right)$

Wherein,

represent the impedance matrix of single channel transmission cross-section, Z ₁₁, Z ₂₂..., Z _nnbe respectively node 1,2 ..., n self-impedance, Z ₁₂, Z ₂₁..., Z _1n, Z _n1for the internodal transimpedance of difference;

3) admittance matrix corresponding to computing node, has:

$Y_{\mathrm{eq}}^{\′}={Z_{\mathrm{eq}}^{\′}}^{-1}=\left[\begin{array}{cccccc}{Y}_{11}& Y_{12}& .& .& .& Y_{1n}\\ Y_{21}& Y_{22}& .& .& .& Y_{2n}\\ .& .& & .& & .\\ .& .& & .& & .\\ .& .& & .& & .\\ Y_{n1}& Y_{n2}& .& .& .& Y_{\mathrm{nn}}\end{array}\right]---\left(6\right)$

Wherein,

represent admittance matrix corresponding to node, Y ₁₁, Y ₂₂..., Y _nnbe respectively node 1,2 ..., n self-admittance, Y ₁₂, Y ₂₁..., Y _1n, Y _n1for the internodal transimpedance of difference;

4) equivalent impedance of calculating hyperchannel transmission cross-section

In admittance matrix corresponding to described node, increase a line and row, then admittance matrix corresponding to node carried out to cancellation calculating, after calculating, obtain increasing the i.e. Equivalent admittance between two nodes of a line diagonal element so equivalent impedance of hyperchannel transmission cross-section

be expressed as:

$X_{\mathrm{\Σ}}^{\′}=\frac{1}{y_{\mathrm{eq}}^{\′}}---\left(7\right)$

5) the steady stability ability to transmit electricity of hyperchannel transmission cross-section

be expressed as:

$P_{\max }^{\′}\frac{1}{X_{\mathrm{\Σ}}^{\′}}=y_{\mathrm{eq}}^{\′}---\left(8\right).$

5. the weak section determination method of consideration network topology change according to claim 1 on ability to transmit electricity impact, is characterized in that: in described step 2, the load factor of transmission cross-section represents have with η:

$\mathrm{\η}=\frac{P_{\mathrm{load}}}{P_{\max }}---\left(9\right)$

Wherein, P _loadrepresent the real power of transmission cross-section.

6. the weak section determination method of consideration network topology change according to claim 1 on ability to transmit electricity impact, it is characterized in that: in described step 3, adopt following three cardinal rules to screen transmission cross-section, according to the load factor definite value of setting, adopt the mode debasing the standard step by step to determine final weak section;

(1), under normal condition, the transmission cross-section that load factor is higher should retain;

(2), under N-1 state, load factor changes greatly and higher should the retaining of N-1 back loading rate;

(3), under N-M state, load factor changes greatly and higher should the retaining of N-M back loading rate.

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