CN105071386A - Method for evaluating voltage support capability of multi-infeed DC receiving-end power grid having STATCOM - Google Patents

Abstract

The invention provides a method for evaluating voltage support capability of a multi-infeed DC receiving-end power grid having a STATCOM. The method comprises the following steps: A) establishing a node admittance matrix Y of a receiving-end AC power grid; B) calculating a node impedance matrix Z, wherein the node impedance matrix Z is an inverse matrix of the node admittance matrix Y; C) calculating multi-infeed effective short-circuit ratio at the place of an infeed node to be detected of a direct current transmission system; D) calculating multi-infeed effective short-circuit ratio correction generated when the STATCOM is connected to the node to be detected; E) calculating multi-infeed effective short-circuit ratio of the node to be detected after being corrected; and F) carrying out evaluation on the voltage support capability at the place of the node to be detected. According to the method, the function of the STATCOM is converted into correction of the multi-infeed effective short-circuit ratio to correct the multi-infeed effective short-circuit ratio, so that the problem that the voltage support capability of the multi-infeed DC receiving-end power grid having the STATCOM has no effective evaluation index can be solved.

Description

Containing the evaluation method of the multi-infeed DC receiving end line voltage enabling capabilities of STATCOM

Technical field

The invention belongs to field of power, be specifically related to a kind of method evaluating the multi-infeed DC receiving end line voltage enabling capabilities containing STATCOM.

Background technology

In recent years, along with the operation successively of multinomial DC transmission engineering, the multi-infeed DC receiving end electrical network of a quasi-representative is formed in China.DC transmission system consumes a large amount of reactive power in running, proposes to be strict with to the equilibrium of supply and demand of power system reactive power.For this reason, a collection of STATCOM engineering now comes into operation successively, to meet the growing reactive power demand of electrical network.

Evaluate the voltage support ability of multi-infeed DC receiving end electrical network, for the planning of electric power system and operation work, all significant.For the receiving end electrical network not containing any dynamic reactive compensation device, current power industry circle adopts its voltage support ability of the effective short circuit ratio metrics evaluation of many feed-ins usually.But for the receiving end electrical network containing STATCOM, still do not evaluate the efficiency index of its voltage support ability at present.Owing to not counting the effect of STATCOM, directly apply mechanically the voltage support ability of the effective short circuit ratio metrics evaluation of many feed-ins containing the multi-infeed DC receiving end electrical network of STATCOM, very conservative estimation will be obtained, even mislead planning and the operation work of electric power system.

In view of this, existing evaluation method is urgently improved.

Summary of the invention

For the shortcoming of prior art, the object of this invention is to provide a kind of method evaluating the multi-infeed DC receiving end line voltage enabling capabilities containing STATCOM.

To achieve these goals, the invention provides a kind of evaluation method of the multi-infeed DC receiving end line voltage enabling capabilities containing STATCOM, it comprises the following steps:

A, set up the node admittance matrix Y of receiving end AC network;

B, computing node impedance matrix Z, described nodal impedance matrix Z is the inverse matrix of described node admittance matrix Y;

C, calculate the effective short circuit ratio of many feed-ins waiting to investigate DC transmission system feed-in Nodes;

The effective short circuit ratio correction of many feed-ins that investigation Nodes produces is being treated in D, calculating STATCOM access;

E, calculate wait investigating the effective short circuit ratio of many feed-ins after node regulation;

F, treat and investigate the voltage support ability of Nodes and evaluate.

In the present invention, STATCOM access is in the electrical network of specified running status, makes it exert oneself according to rated capacity.Under this condition, STATCOM can be similar to and be considered as ac current source.Under perunit value, its size of current equals its rated capacity; More delayed than its access node voltage-phase 90 ° of its current phase, flows into this node.

The access of STATCOM will produce the effective short circuit ratio correction of many feed-ins.Calculate the effective short circuit ratio of many feed-ins according to current practice, add that STATCOM accesses the correction produced, the evaluation index of the receiving end line voltage enabling capabilities containing STATCOM can be obtained.

According to another embodiment of the present invention, node admittance matrix Y comprises alternating current filter and the reactive-load compensation capacitor of DC transmission system, ignores the resistance of all transmission lines, and all physical quantitys adopt perunit value.

According to another embodiment of the present invention, node admittance matrix Y is:

$Y=\left(\begin{array}{ccccccc}{Y}_{11}& ...& Y_{1i}& ...& Y_{1j}& ...& Y_{1n}\\ \·& & \·& & \·& & \·\\ \·& & \·& & \·& & \·\\ \·& & \·& & \·& & \·\\ Y_{i1}& ...& Y_{ii}& ...& Y_{ij}& ...& Y_{in}\\ \·& & \·& & \·& & \·\\ \·& & \·& & \·& & \·\\ \·& & \·& & \·& & \·\\ Y_{j1}& ...& Y_{ji}& ...& Y_{jj}& ...& Y_{jn}\\ \·& & \·& & \·& & \·\\ \·& & \·& & \·& & \·\\ \·& & \·& & \·& & \·\\ Y_{n1}& ...& Y_{ni}& ...& Y_{nj}& ...& Y_{nn}\end{array}\right);$

Wherein, Y _iithe self-admittance of AC network i-th node, Y _ijbe the transadmittance between AC network i-th, a j node, n is the node total number of AC network, 1≤i < j≤n.

According to another embodiment of the present invention, nodal impedance matrix Z is the inverse matrix of node admittance matrix:

$Z=\left(\begin{array}{ccccccc}{Z}_{11}& ...& Z_{1i}& ...& Z_{1j}& ...& Z_{1n}\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ Z_{i1}& ...& Z_{ii}& ...& Z_{ij}& ...& Z_{in}\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ Z_{j1}& ...& Z_{ji}& ...& Z_{jj}& ...& Z_{jn}\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ Z_{n1}& ...& Z_{ni}& ...& Z_{nj}& ...& Z_{nn}\end{array}\right)$

Wherein, Z _iithe self-impedance of AC network i-th node, Z _ijit is the mutual impedance between AC network i-th, a j node.

According to another embodiment of the present invention, in step C, suppose that there is DC transmission system feed-in at node x place, make it be node to be investigated, then the effective short circuit ratio of this many feed-in in some place is:

${\mathrm{MIESCR}}_x=\frac{1}{\underset{k\&Element;N_{dc}}{\&Sigma;}{z}_k^x{P}_{dcn0k}}$

In formula, N _dcfor all set being connected with the node of DC transmission system, x, k ∈ N _dc, P _dcn0kfor the perunit value of the specified active power of node k place DC transmission system, for nodal impedance matrix xth row kth column element (being a pure imaginary number) turns clockwise 90 ° of gained real numbers.

According to another embodiment of the present invention, in step D, the effective short circuit ratio correction of the many feed-ins in node x place is:

${\mathrm{\&Delta;MIESCR}}_x=\frac{\underset{l\&Element;N_{stat}}{\&Sigma;}{z}_l^x{I}_{statl}}{\underset{k\&Element;N_{dc}}{\&Sigma;}{z}_k^x{P}_{dcn0k}}$

Wherein, N _statfor all set being connected with the node of STATCOM;

N _dcfor all set being connected with the node of DC transmission system;

L ∈ N _stat, x, k ∈ N _dc, I _statlfor the perunit value of node l place STATCOM rated capacity;

P _dcn0kfor the perunit value of the specified active power of node k place DC transmission system;

for nodal impedance matrix xth row l column element (being a pure imaginary number) turns clockwise 90 ° of gained real numbers;

for nodal impedance matrix xth row kth column element (being a pure imaginary number) turns clockwise 90 ° of gained real numbers.

According to another embodiment of the present invention, in step e, the node x place effective short circuit ratio of revised many feed-ins is:

MIESCR _x′＝MIESCR _x+ΔMIESCR _x。

According to another embodiment of the present invention, the Evaluation threshold in step F is:

Compared with prior art, the present invention possesses following beneficial effect:

In the present invention, the effect of STATCOM is converted to the correction of the effective short circuit ratio of many feed-ins, in order to revise the effective short circuit ratio of many feed-ins, the multi-infeed DC receiving end line voltage enabling capabilities that can solve containing STATCOM there is no the problem of effective evaluation index.

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

Accompanying drawing explanation

Fig. 1 is the flow chart of the evaluation method of the multi-infeed DC receiving end line voltage enabling capabilities containing STATCOM of embodiment 1;

Fig. 2 is the schematic diagram of the simulation model of embodiment 1.

Embodiment

Embodiment 1

Consult Fig. 1, it is for the present embodiment is containing the flow chart of the evaluation method of the multi-infeed DC receiving end line voltage enabling capabilities of STATCOM.As shown in the figure, the method for the present embodiment comprises the following steps successively:

A, set up the node admittance matrix of AC network.In the present embodiment, the schematic diagram of simulation model as shown in Figure 2.STATCOM is arranged on direct current system 1 feed-in node and direct current system 2 feed-in Nodes, and its rated capacity is I _sTAT1=0.5, I _sTAT2=0.3, require the voltage support ability evaluating direct current system 3 feed-in Nodes.The nominal DC power of three DC transmission system is equal, P _dcn1=P _dcn2=P _dcn3=1.Each impedance is respectively:

Z ₁＜θ ₁＝0.6＜90°，Z ₂＜θ ₂＝0.3＜90°，Z ₃＜θ ₃＝0.5＜90°，Z ₁₂＜θ ₁₂＝

0.4＜90°，Z ₂₃＜θ ₂₃＝0.4＜90°，Z ₁₃＜θ ₁₃＝0.5＜90°。

Under specified operation conditions, the alternating current filter of DC transmission system and reactive-load compensation capacitor should the reactive powers that consume of compensating direct current transmission system just, are usually regarded as constant susceptance.In the present embodiment, B _c1=B _c2=B _c3=j0.59.

Substitute into above data, the node admittance matrix setting up AC network is as follows:

$Y=\left(\begin{array}{ccc}-j5.5767& j2.5000& j2.0000\\ j2.5000& -j7.7433& j2.5000\\ j2.0000& j2.5000& -j5.9100\end{array}\right)$

B, computing node impedance matrix.Above-mentioned node admittance matrix is inverted, obtains nodal impedance matrix:

$Z=\left(\begin{array}{ccc}j0.3101& j0.1552& j0.1706\\ j0.1552& j0.2272& j0.1486\\ j0.1706& j0.1486& j0.2898\end{array}\right)$

C, calculate the effective short circuit ratio of many feed-ins waiting to investigate DC transmission system feed-in Nodes.Suppose that there is DC transmission system feed-in at node x place, make it be node to be investigated, then the effective short circuit ratio of this many feed-in in some place is:

${\mathrm{MIESCR}}_x=\frac{1}{\underset{k\&Element;N_{dc}}{\&Sigma;}{z}_k^x{P}_{dcn0k}}$

In formula, N _dcfor all set being connected with the node of DC transmission system, x, k ∈ N _dc, P _dcn0kfor the perunit value of the specified active power of node k place DC transmission system, for nodal impedance matrix xth row kth column element (being a pure imaginary number) turns clockwise 90 ° of gained real numbers.

The present embodiment examination direct current system 3 feed-in node.The effective short circuit ratio of many feed-ins at this some place is:

${\mathrm{MIESCR}}_3=\frac{1}{0.1706\&times;1+0.1486\&times;1+0.2898\&times;1}=1.64$

The effective short circuit ratio correction of many feed-ins that investigation Nodes produces is being treated in D, calculating STATCOM access.The effective short circuit ratio correction of the many feed-ins in node x place is:

${\mathrm{\&Delta;MIESCR}}_x=\frac{\underset{l\&Element;N_{stat}}{\&Sigma;}{z}_l^x{I}_{statl}}{\underset{k\&Element;N_{dc}}{\&Sigma;}{z}_k^x{P}_{dcn0k}}$

In formula, N _statfor all set being connected with the node of STATCOM, N _dcfor all set being connected with the node of DC transmission system, l ∈ N _stat, x, k ∈ N _dc, I _statlfor the perunit value of node l place STATCOM rated capacity, P _dcn0kfor the perunit value of the specified active power of node k place DC transmission system, for nodal impedance matrix xth row l column element (being a pure imaginary number) turns clockwise 90 ° of gained real numbers, for nodal impedance matrix xth row kth column element (being a pure imaginary number) turns clockwise 90 ° of gained real numbers.

In the present embodiment, the effective short circuit ratio correction of many feed-ins of direct current system 3 feed-in Nodes is:

${\mathrm{\&Delta;MIESCR}}_3=\frac{0.1706\&times;0.5+0.1486\&times;0.3}{0.1706\&times;1+0.1486\&times;1+0.2898\&times;1}=0.08$

E, to calculate wait investigating the effective short circuit ratio of many feed-ins after node regulation.The node x place effective short circuit ratio of revised many feed-ins is:

MIESCR _x′＝MIESCR _x+ΔMIESCR _x

In the present embodiment, the effective short circuit ratio of the revised many feed-ins of direct current system 3 feed-in Nodes is:

MIESCR _x′＝1.64+0.08＝1.72

F, treat and investigate the voltage support ability of Nodes and evaluate.Described Evaluation threshold is:

In the present embodiment, during direct current system 3 feed-in Nodes voltage support ability is.

Although the present invention discloses as above with preferred embodiment, and is not used to limit scope of the invention process.Any those of ordinary skill in the art, not departing from invention scope of the present invention, when doing a little improvement, namely every equal improvement done according to the present invention, should be scope of the present invention and contained.

Claims (8)

1., containing an evaluation method for the multi-infeed DC receiving end line voltage enabling capabilities of STATCOM, it comprises the following steps:

A, set up the node admittance matrix Y of receiving end AC network;

B, computing node impedance matrix Z, described nodal impedance matrix Z is the inverse matrix of described node admittance matrix Y;

C, calculate the effective short circuit ratio of many feed-ins waiting to investigate DC transmission system feed-in Nodes;

The effective short circuit ratio correction of many feed-ins that investigation Nodes produces is being treated in D, calculating STATCOM access;

E, calculate wait investigating the effective short circuit ratio of many feed-ins after node regulation;

F, treat and investigate the voltage support ability of Nodes and evaluate.

2. evaluation method according to claim 1, is characterized in that, described node admittance matrix Y comprises alternating current filter and the reactive-load compensation capacitor of DC transmission system, ignores the resistance of all transmission lines, and all physical quantitys adopt perunit value.

3. evaluation method according to claim 2, is characterized in that, described node admittance matrix Y is:

$Y=\left(\begin{array}{ccccccc}{Y}_{11}& ...& Y_{1i}& ...& Y_{1j}& ...& Y_{1n}\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ Y_{i1}& ...& Y_{ii}& ...& Y_{ij}& ...& Y_{in}\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ Y_{j1}& ...& Y_{ji}& ...& Y_{jj}& ...& Y_{jn}\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ Y_{n1}& ...& Y_{ni}& ...& Y_{nj}& ...& Y_{nn}\end{array}\right);$

Wherein, Y _iithe self-admittance of AC network i-th node, Y _ijbe the transadmittance between AC network i-th, a j node, n is the node total number of AC network, 1≤i < j≤n.

4. evaluation method according to claim 3, is characterized in that, described nodal impedance matrix Z is the inverse matrix of node admittance matrix:

$Z=\left(\begin{array}{ccccccc}{Z}_{11}& ...& Z_{1i}& ...& Z_{1j}& ...& Z_{1n}\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ Z_{i1}& ...& Z_{ii}& ...& Z_{ij}& ...& Z_{in}\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ Z_{j1}& ...& Z_{ji}& ...& Z_{jj}& ...& Z_{jn}\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ \&CenterDot;& & \&CenterDot;& & \&CenterDot;& & \&CenterDot;\\ Z_{n1}& ...& Z_{ni}& ...& Z_{nj}& ...& Z_{nn}\end{array}\right)$

Wherein, Z _iithe self-impedance of AC network i-th node, Z _ijit is the mutual impedance between AC network i-th, a j node.

5. evaluation method according to claim 1, is characterized in that, in step C, supposes that there is DC transmission system feed-in at node x place, makes it be node to be investigated, then the effective short circuit ratio of this many feed-in in some place is:

${\mathrm{MIESCR}}_x=\frac{1}{\underset{k\&Element;N_{dc}}{\&Sigma;}{z}_k^x{P}_{dcn0k}}$

In formula, N _dcfor all set being connected with the node of DC transmission system, x, k ∈ N _dc, P _dcn0kfor the perunit value of the specified active power of node k place DC transmission system, for nodal impedance matrix xth row kth column element turn clockwise 90 ° of gained real numbers.

6. evaluation method according to claim 1, is characterized in that, in step D, the effective short circuit ratio correction of the many feed-ins in node x place is:

${\mathrm{\&Delta;MIESCR}}_x=\frac{\underset{l\&Element;N_{stat}}{\&Sigma;}{z}_l^x{I}_{statl}}{\underset{k\&Element;N_{dc}}{\&Sigma;}{z}_k^x{P}_{dcn0k}}$

Wherein, N _statfor all set being connected with the node of STATCOM;

N _dcfor all set being connected with the node of DC transmission system;

L ∈ N _stat, x, k ∈ N _dc, I _statlfor the perunit value of node l place STATCOM rated capacity;

P _dcn0kfor the perunit value of the specified active power of node k place DC transmission system;

for nodal impedance matrix xth row l column element turn clockwise 90 ° of gained real numbers;

for nodal impedance matrix xth row kth column element turn clockwise 90 ° of gained real numbers.

7. evaluation method according to claim 1, is characterized in that, in step e, the node x place effective short circuit ratio of revised many feed-ins is:

MIESCR _x′＝MIESCR _x+ΔMIESCR _x。

8. evaluation method according to claim 1, is characterized in that, the Evaluation threshold in step F is: