CN104408272B - A kind of D.C. magnetic biasing under mountain area environment influences evaluation system and method - Google Patents

Abstract

The present invention relates to a system and method for evaluating the influence of DC magnetic bias in a mountainous environment. The evaluation system includes: a mountainous environment model building module, which is used to build a mountainous environment model consistent with the actual environment; an evaluation model building module, which is used in The grid topology model is added to the mountainous environment model to form a complete evaluation model; the evaluation result acquisition module is used to obtain and output the DC bias magnetic impact results in the mountainous environment according to the evaluation model. Compared with the prior art, the invention has the advantages of high accuracy, applicable to complex environments and the like.

Description

A system and method for evaluating the impact of DC magnetic bias in a mountainous environment

technical field

The invention relates to the field of direct current magnetic bias control of substations, in particular to a system and method for evaluating the impact of direct current magnetic bias in a mountainous environment.

Background technique

It has been more than 20 years since the introduction of the DC transmission system in my country. The number of existing DC lines and the scale of the planned DC transmission system are the first in the world. In recent years, with the economic development of the eastern region, its demand for electricity is also increasing day by day. The concentration of power loads has caused a series of problems, and has also posed unprecedented challenges to the development of power technology. The grounding poles of foreign direct current transmission systems are usually selected in sparsely populated rivers, rivers, lakes and coastal areas, which often have little impact on other systems. But for the eastern part of China, due to factors such as dense population and rapid urbanization, it is difficult to select the location of the ground electrode of the DC system. The unipolar operation of the DC system will cause a significant change in the ground potential, which will affect the AC transmission system, communication system and other equipment sensitive to the ground potential.

Although there have been many studies on the ground potential and ground current distribution caused by the ground pole current during DC transmission unipolar operation, the influence of ground potential and DC bias magnetic field on complex terrain environments such as inland, mountainous, and basin In terms of evaluation, there are still some unresolved problems.

Contents of the invention

The object of the present invention is to provide a DC bias impact evaluation system and method with high accuracy and suitable for mountainous environments with complex environments in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

A DC magnetic bias impact evaluation system in mountainous environment, including:

The mountain environment model building module is used to establish a mountain environment model consistent with the actual environment;

An evaluation model building module is used to add a power grid topology model to the mountainous environment model to form a complete evaluation model;

The evaluation result obtaining module is used to obtain and output the result of DC bias magnetic influence in the mountainous environment according to the evaluation model.

The mountain environment model includes a mountain model and a basin model.

The evaluation result acquisition module includes:

a DC current calculation unit, used to calculate the DC current flowing through the neutral point of the AC transformer according to the evaluation model;

The evaluation result output unit obtains and outputs the result of direct current bias influence according to the calculated direct current.

A method for evaluating the influence of DC magnetic bias in a mountainous environment, comprising the following steps:

1) Establish a mountainous environment model consistent with the actual environment;

2) adding the grid topology model on the mountain environment model to form a complete evaluation model;

3) According to the evaluation model, the result of DC bias magnetic influence in the mountainous environment is obtained and output.

The mountain environment model established in the step 1) includes a mountain model and a basin model.

In the step 1), when the basin model is established, its soil resistance is in a horizontal layered structure, and the soil resistivity of each layer is set independently.

In the step 1), the mountain model and the basin model intersect to form a mountain environment model, and the soil resistance at the interface is horizontal and vertical.

The step 3) is specifically:

301) Calculate the DC current flowing through the neutral point of the AC transformer according to the evaluation model;

302) Obtain and output the DC bias influence result obtained from the calculated DC current.

In the step 301), CDEGS calculation software is used to obtain the DC current flowing through the neutral point of the AC transformer.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention accurately models the actual mountainous environment, improves the accuracy of DC bias impact evaluation, and is applicable to complex geological environments including mountains and basins.

(2) The present invention is simple and effective, and has high calculation precision.

Description of drawings

Fig. 1 is a schematic flow sheet of the present invention;

Fig. 2 is a schematic diagram of a mountainous environment model established by the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

An embodiment of the present invention provides a DC magnetic bias impact evaluation system in a mountain environment, including a mountain environment model establishment module, an evaluation model establishment module and an evaluation result acquisition module. The mountain environment model establishment module is used to establish a mountain environment model consistent with the actual environment, and the established mountain environment model includes a mountain model and a basin model. The evaluation model building module is used to add a power grid topology model to the mountain environment model to form a complete evaluation model. The power grid topology model is a commonly used model for describing power grid distribution. The evaluation result acquisition module is used to obtain and output the result of DC bias magnetic influence in mountainous environment according to the evaluation model. Wherein, the evaluation result obtaining module includes a direct current calculation unit for calculating the direct current flowing through the neutral point of the AC transformer according to the evaluation model, and a direct current bias influence result obtained and output according to the calculated direct current and an evaluation result output unit.

As shown in Figure 1, the evaluation method of the DC bias magnetic impact evaluation system in the above-mentioned mountainous environment specifically includes the following steps:

In step 101, a mountain environment model, a mountain model and a basin model consistent with the actual environment are established. Among them, the mountain model describes mountains with high surface soil resistivity. The soil is dominated by rocks, and the soil resistivity is above several thousand ohms. The soil resistivity can be specified arbitrarily when building a mountain model. The basin model describes a basin with a low surface soil resistivity. The soil has a horizontal layered structure and may contain groundwater. The surface soil resistivity is low and the underlying soil resistivity is high. When the basin model is established, the soil resistance is horizontal. Layered structure, the resistivity of each layer can be set independently. The established mountain model and basin model intersect to form a mountain environment model, and the soil resistance at the interface is horizontal and vertical.

In step 102, the grid topology model is added to the mountain environment model to form a complete evaluation model.

In step 103, according to the evaluation model, CDEGS calculation software is used to calculate the DC current flowing through the neutral point of the AC transformer.

In step 104, the calculated DC current obtains the DC bias influence result and outputs it.

The effectiveness of the present invention will be described below by taking the evaluation results of the DC bias level of the actual regional power grid as an example.

There is a regional power grid near the DC grounding pole, and the impact level of DC bias magnetic field needs to be evaluated. The evaluation scope includes 2 500kV AC substations and 9 220kV AC substations.

Table 1 shows the comparison of the traditional DC bias evaluation mode without considering the mountain range, the present invention and the actual measurement results. Table 2 shows the deviation between the calculation results obtained by the present invention and the measured results without considering the DC magnetic bias evaluation mode under the condition of mountains.

Table 1 DC bias current flowing in each phase winding of AC main transformer in substation (unit: A)

substation Voltage level traditional model Invention model Measured A 500kV 4.26 6.45 3.3 B 500kV 2.75 0.41 2.2 C 220kV 13.11 6.75 6.4 D. 220kV 20.05 23.60 20.6 E. 220kV 1.93 3.10 2.6 f 220kV 1.09 4.61 1.9 G 220kV 2.22 4.30 4.6 h 220kV 0.26 3.39 3.7 I 220kV 16.33 17.64 21.8 J 220kV 0.07 8.70 3.2 K 220kV 2.01 0.63 0.03

Table 2 Calculation result deviation distribution statistical table (unit: A)

The results in Table 2 show that the calculated results of the present invention have less deviation from the measured results, which is more in line with the actual situation.

Claims (5)

1. A DC magnetic bias impact evaluation system under a mountainous environment, characterized in that it comprises: The mountain environment model building module is used to establish a mountain environment model consistent with the actual environment, including a mountain model and a basin model; An evaluation model building module is used to add a power grid topology model to the mountainous environment model to form a complete evaluation model; An evaluation result acquisition module, used to obtain and output the DC bias magnetic influence result under the mountainous environment according to the evaluation model; The mountain model describes mountains with surface soil resistivity above several thousand ohms, and its soil is dominated by rocks. The basin model describes basins with low surface soil resistivity, and its soil is in a horizontally layered structure , the lower soil resistivity is greater than the surface soil resistivity. When establishing a basin model, its soil resistance is a horizontal layered structure, and the soil resistivity of each layer is set independently. The mountain model and basin model intersect to form a mountain environment model. At the interface, the soil Resistors are horizontal and vertical. 2. the DC magnetic bias impact evaluation system under the mountainous environment according to claim 1, is characterized in that, described evaluation result acquisition module comprises: a DC current calculation unit, used to calculate the DC current flowing through the neutral point of the AC transformer according to the evaluation model; The evaluation result output unit obtains and outputs the result of direct current bias influence according to the calculated direct current. 3. A method for evaluating the impact of DC magnetic bias in a mountain environment, characterized in that it comprises the following steps: 1) Establish a mountainous environment model consistent with the actual environment, including a mountain model and a basin model. The mountain model describes a mountain with surface soil resistivity above several thousand ohms. For basins with lower surface soil resistivity, the soil has a horizontal layered structure, and the lower soil resistivity is greater than the surface soil resistivity. When building a basin model, the soil resistance is a horizontal layered structure, and the soil resistivity of each layer is independent. Setting, the mountain model and the basin model intersect to form a mountain environment model, and the soil resistance at the interface is horizontal and vertical; 2) adding the grid topology model on the mountain environment model to form a complete evaluation model; 3) According to the evaluation model, the result of DC bias magnetic influence in the mountainous environment is obtained and output. 4. the DC magnetic bias impact evaluation method under the mountainous environment according to claim 3, is characterized in that, described step 3) is specially: 301) Calculate the DC current flowing through the neutral point of the AC transformer according to the evaluation model; 302) Obtain and output the DC bias influence result obtained from the calculated DC current. 5. The method for evaluating the impact of DC magnetic bias in a mountainous environment according to claim 4, characterized in that, in the step 301), the CDEGS calculation software is used to obtain the DC current flowing through the neutral point of the AC transformer.