CN103199507A - Setting calculation extreme mode selecting method based on improved proximity set method - Google Patents

Abstract

A method for selecting the extreme mode of setting calculation based on the improved close neighbor set method, comprising the following steps: determining the impedance value of the grounding branch connected to the node where the plant station is located in each plant station mode; calculating the equivalent impedance, the equivalent impedance being the The change of the plant station from the maximum mode to the minimum mode is equivalent to connecting the ground branch of the equivalent impedance at the node where the plant station is located; calculate the impact on the self-impedance of the fault point when the plant station operation mode changes from maximum to minimum ; Calculate the relative variation of the self-impedance of the fault point as the size of the influence of the plant station. The positive effect of the present invention is: improve the adjacent set method to make the plant station equivalent value a ground branch, simulate the plant station mode change with the branch impedance change, and change the branch impedance change when the plant station mode changes from maximum to minimum The quantity indicates the change range of the plant station mode, which truly simulates the change of the plant station mode. Compared with the close neighbor set method, this method can more accurately delineate the influence domain of the plant station.

Description

A Method of Selecting Extreme Modes of Tuning Calculation Based on Improved Neighbor Set Method

technical field

The invention relates to the technical field of power systems, in particular to an extreme mode selection method for setting calculation based on the improved immediate set method.

Background technique

Determining the operation mode of the power system is a prerequisite for the calculation of relay protection setting. In the actual operation of the power system, the determined fixed value cannot be changed frequently, so the fixed value needs to be able to adapt to various operating modes of the system.

In the power system, the content of setting calculation includes different fault points (for example, any point on the line, terminal busbar, successive action, that is, the situation that the switch at the end of the line trips three phases first but the fault point still exists), different fault types (single Phase-to-ground, two-phase to ground, two-phase short-circuit, three-phase short-circuit) and different operation modes (such as cutting off power system components such as generators, lines, transformers) for various combination calculations and comparisons to determine the extreme operation mode and setting value. The extreme operation mode refers to the operation mode in which the protection is most difficult to meet the sensitivity requirements or the adjacent protection is the most difficult to meet the selectivity requirements among the possible operation modes of the system. Select the extreme operating modes from the possible operating modes of the system, and set the protection according to the requirements of sensitivity and selectivity in these modes, so as to ensure the correctness of the protection action when the operating mode of the system changes. Therefore, in the setting calculation process, in order to obtain a correct and reasonable setting value, it is necessary to consider various possible operating modes, and obtain the corresponding calculated values under these operating modes, so as to select the extreme operating mode and setting value.

However, with the expansion of the power system scale and the continuous change of the power grid structure, there are more and more operating modes of the power system, and the calculation of the setting value for all possible power system operating modes has problems such as large amount of calculation and long time consumption. . How to quickly select a representative system operation mode from the complex system operation mode to calculate the setting value and ensure that the result is appropriate and reasonable is a new task for the relay protection setting value calculation personnel and the relay protection setting value calculation software compiler. .

The existing traditional operation mode selection method only considers very few operation modes, which is too simple to consider, and the obtained fixed value is not very reliable, and there is also a certain irrationality. For example, through reasonable programming, let the computer combine all possible operation modes, and then select the required operation mode, which will not only greatly improve the efficiency of setting, but also improve the working performance of the protection device. However, if the step-by-step calculation is carried out according to the conventional sequential logic thinking method, various combinations of situations will be extremely numerous, the calculation workload will be very large, the calculation time will be too long, and the calculation ability and practicability of the setting program will be greatly reduced. However, it is too complicated to consider all possible operation modes of the whole network. In order to accurately and effectively determine the extreme operation mode of protection setting, it is necessary to consider the influence of network topology changes on fault current and protection setting in a large range and selectively. , reduce the number of way combinations, reduce the number of calculations, and shorten the calculation time.

Contents of the invention

The technical problem to be solved by the present invention is to provide an extreme mode selection method for setting calculation based on the improved immediate set method.

In order to solve the above-mentioned technical problems, the present invention is realized in the following manner: a method for selecting the extreme mode of setting calculation based on the improved immediate set method, comprising the following steps:

Determine the impedance value of the grounding branch connected to the node where the plant station is located in each plant station mode;

Calculate the equivalent impedance, the equivalent impedance is that the plant station changes from the maximum mode to the minimum mode, which is equivalent to connecting the grounding branch of the equivalent impedance at the node where the plant station is located;

Calculate the impact on the self-impedance of the fault point when the operation mode of the plant station is changed from maximum to minimum;

Calculate the relative variation of the self-impedance of the fault point as the size of the impact of the plant.

The positive effect of the present invention is: improve the adjacent set method to make the plant station equivalent value a ground branch, simulate the plant station mode change with the branch impedance change, and change the branch impedance change when the plant station mode changes from maximum to minimum The quantity indicates the change range of the plant station mode, which truly simulates the change of the plant station mode. Compared with the close neighbor set method, this method can more accurately delineate the influence domain of the plant station.

Description of drawings

Fig. 1 is a simple system equivalent explanatory diagram in the prior art;

Figure 2 shows the equivalent impedance corresponding to different plant and station modes

Figure 3 is the modification of the impedance corresponding to the change of the plant station mode

Detailed ways

1. The basic process of the traditional adjacent set method:

Define a quantity that represents the electrical closeness between nodes, which is called closeness, and the set of nodes that meet the standard of closeness is called closeness node set. The closeness between nodes is used as the basis for determining the range of components participating in the operation mode combination, that is, only the component changes on the nodes that fall into the adjacent node set have the most important impact on the short-circuit current, and the changes of components on other nodes can be Not considered, that is, not participating in the combination of methods.

In the system, the change of the operation mode of the plant station is mainly reflected in the change of the equivalent ground impedance of its nodes. Therefore, it is only necessary to change the equivalent ground impedance Cjj of node J to better simulate changes in the operation mode of the plant. When the operation mode of the plant is changed, that is, when the equivalent ground impedance of node J changes as p×Cjj, the self-impedance of the fault point changes as Relkj×Zkk. Because the magnitude of the fault current at the fault point is greatly affected by the self-impedance, the change multiple of the self-impedance Relkj can better reflect the influence of the change of the operation mode of the J point on the fault current of the K point, and Relkj is the degree of proximity.

With the plant as the node and the line as the branch, each plant pre-defines the maximum and minimum operation modes. The faulty node K and the station node J are retained, and the network is equivalent. The equivalent network is shown in Figure 1.

The meaning of each parameter is as follows:

Ckj——the equivalent impedance reflecting the electrical distance between K-J;

Ckk—Equivalent impedance to ground at the fault point;

Cjj—J node equivalent impedance to ground.

Node impedance matrix elements Zkk, Zkj, Zjj are related to Ckk, Ckj, Cjj as follows:

Zkk＝Ckk||(Ckj+Cjj) (1)

Zkj＝Ckk×Cjj/(Ckk+Ckj+Cjj) (2)

Zjj＝Cjj||(Ckj+Ckk) (3)

When the operation mode of the plant station changes, that is, when the equivalent ground impedance Cjj of node J changes p times, the self-impedance Zkk of the fault point changes Relkj times, then:

Relkj×Zkk＝Ckk(Ckj+p×Cjj)/(Ckk+Ckj+p×Cjj)

(4)

${\mathrm{<span\; class="notranslate">\; Rel</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Substituting (1), (2), and (3) into (5) after transformation:

${\mathrm{<span\; class="notranslate">\; Rel</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; p</span>}}{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

The obtained formula (6) is the closeness of point J to point K. It can be assumed that when p=10, 0.9≤q≤1.1 (q=Relkj) means that the self-impedance of point K changes little, and the short-circuit current changes little, so it is judged that point J has little influence on point K, that is, it does not enter The immediate node set; otherwise, enter the immediate node set. The algorithm of the above criterion is simple, only need to use the relevant elements of the impedance matrix of the original network.

2. The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The method for selecting the extreme mode of setting calculation based on the improved immediate set method described in the present invention has made corresponding improvements to the traditional adjacent set method. A grounding branch, the change in the way of the station is represented by the change of its impedance; the impedance value of the grounding branch corresponding to the different modes of each station is determined, and the change in the way of the station is represented by the change range from the maximum impedance value to the minimum impedance value magnitude.

Step 1. Determine the impedance value of the grounding branch connected to the node J where the plant station is located in each plant mode. Assume that the corresponding impedance is Zj in the maximum mode of the plant station, and Zj’ in the minimum mode, as shown in Figure 2.

Step 2. The factory station changes from the maximum mode to the minimum mode, which is equivalent to connecting a grounding branch with impedance ΔZj at the node where the factory station is located, as shown in Figure 3.

Step 3. When the operation mode of the plant station is changed from maximum to minimum, the influence on the self-impedance of the fault point is as follows:

${\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&Delta;Z</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

Step 4. The relative variation of the self-impedance at the fault point is:

$\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&Delta;Z</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

The above formula is the calculation formula for improving the delimitation index of the influence area of Jifa Station.

From the above process, it can be seen that the improvement of the adjacent set method makes the station equivalent to a ground branch, and the change of the branch impedance is used to simulate the change of the station mode, and the change of the branch impedance when the station method changes from the maximum to the minimum The quantity indicates the change range of the plant station mode, which truly simulates the change of the plant station mode. Compared with the close neighbor set method, this method can more accurately delineate the influence domain of the plant station.

The change of line operation mode will affect both the positive sequence and zero sequence elements of the impedance matrix, especially the zero sequence mutual inductance branch, whose outage cannot be simply expressed by adding a negative impedance branch. Therefore, if the impedance matrix is still used as the discrimination Indicators will cause the problem of excessive calculation, and cannot guarantee the rapidity of delimiting the impact domain.

3. Improving the delineation process of the line influence domain of the adjacent set method

Based on the existing method for delineating the influence domain of the line, and based on the subgraph decomposition and loop search technology of graph theory, some basic principles for delineating the influence domain of the line are given below:

(1) The connection line on the busbar at both ends of the setting protection and coordination protection shall be assigned to the line influence domain.

(2) Disconnect some lines with weak connections in the power network, and divide them into several connected subgraphs. The influence domain of the protection lines in each subgraph only considers the weak lines connected to the lines in the same subgraph and the subgraph. The impact of mode changes does not consider the impact of line mode changes in other subgraphs.

(3) Determine the number of loops including the line where the protection is located and the lines that form a loop with the line where the protection is located. If after a line is disconnected, the more the number of protection circuits is reduced, the greater the impact of the change of the line mode on protection, and the line should be classified into the line influence domain.

(4) For multi-circuit double-ended common-ended lines, if their parameters are inconsistent, only the one with the largest impedance should be assigned to the line influence domain; if the parameters are consistent, arbitrarily select a line to be assigned to the line influence domain.

Claims (5)

1. A method for selecting the extreme mode of setting calculation based on the improved close neighbor set method, is characterized in that, comprises the following steps: Determine the impedance value of the grounding branch connected to the node where the plant station is located in each plant station mode; Calculate the equivalent impedance, the equivalent impedance is that the plant station changes from the maximum mode to the minimum mode, which is equivalent to connecting the grounding branch of the equivalent impedance at the node where the plant station is located; Calculate the impact on the self-impedance of the fault point when the operation mode of the plant station is changed from maximum to minimum; Calculate the relative variation of the self-impedance of the fault point as the size of the impact of the plant. 2. A method for selecting the extreme mode of setting calculation based on the improved immediate set method according to claim 1, characterized in that: the determination of the impedance value of the grounding branch connected to the node where the plant station is located in each plant station mode specifically includes : It is determined that the corresponding impedance in the maximum mode of the plant station is Zj, and the corresponding impedance in the minimum mode is Zj'. 3. A kind of method for selecting the extreme mode of setting calculation based on the improved close neighbor set method according to claim 1, characterized in that: said calculation equivalent impedance is specifically calculated according to the following formula: ${\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; .</span>$ 4. A kind of method for selecting the extreme mode of setting calculation based on the improved close neighbor set method according to claim 1, characterized in that: the influence of the calculation plant station operation mode on the self-impedance of the fault point when it changes from maximum to minimum is specifically Calculate according to the following formula: ${\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; .</span>$ 5. A kind of setting calculation extreme mode selection method based on the improved immediate neighbor set method according to claim 1, characterized in that: the relative variation of the self-impedance of the calculation fault point, as the size of the impact of the plant station is specifically Calculate according to the following formula: $\mathrm{<span\; class="notranslate">\; \&delta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kj</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; jj</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&Delta;Z</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; kk</span>}}}<span\; class="notranslate">\; .</span>$

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