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CN-115861474-B - Drawing and using method of direct-current magnetic bias risk graph

CN115861474BCN 115861474 BCN115861474 BCN 115861474BCN-115861474-B

Abstract

The invention provides a drawing and using method of a direct current magnetic bias risk graph, which comprises the following steps of firstly establishing risk level division representation; the method comprises the steps of positioning the geographic positions of each direct current pole and each transformer substation, dividing risk areas by a direct current pole circle drawing method and a triangle area dividing method, processing risk areas such as risk overlapping areas and uncovered areas, and finishing drawing of a direct current magnetic bias risk map. And (3) selecting a serious or severe or general risk area from the direct-current magnetic bias risk map, and selecting a treatment scheme according to the grounding condition of the transformer substation, the distance from the grounding electrode and the current magnitude obtained by modeling calculation. The method establishes a predicted risk map of the DC magnetic bias risk, provides DC magnetic bias treatment schemes under different conditions of the power system, can provide theoretical reference and technical guidance for the power grid operation and maintenance departments aiming at the DC magnetic bias problem development treatment work, and helps to maintain the safe and reliable operation of the power transformer substation.

Inventors

  • ZOU GUOPING
  • AN SIGUANG
  • WANG WEI

Assignees

  • 中国计量大学

Dates

Publication Date
20260512
Application Date
20221108

Claims (8)

  1. 1. The drawing method of the direct current magnetic bias risk graph is characterized by comprising the following steps of: step one, establishing risk level classification representation; Positioning the geographic position of each direct current pole and each transformer substation and determining the risk level of each transformer substation based on the risk level classification representation; the third step is to divide the risk level area by using a direct current polar circle drawing method and a triangle area dividing method based on the risk level division, and the specific steps are as follows: The method comprises the steps of taking direct current as a circle center, dividing an area in the circle with 20km as a radius into areas with highest risk levels, connecting every two adjacent substations, equally dividing the connecting line according to the risk level difference of the adjacent substations, connecting equal dividing points, the substations and a grounding electrode O to form triangular areas, dividing the risk areas based on the risk levels of the substations adjacent to the triangular areas, wherein the same area is provided with a plurality of risk levels, covering low risk levels by adopting the high risk levels as the final risk level of the area, dividing the area outside an enclosed area by a direct current pole circle drawing method and a triangular area dividing method, extending the triangular side length of the triangular area to the boundary of the area, reducing the risk level of the area with the nearest risk level as a reference, and finally combining and drawing the areas with the same risk level to obtain the direct current bias magnetic risk map.
  2. 2. The method of claim 1, wherein the step one risk classification is based on the magnitude of the high voltage winding current and the common winding current, wherein the direct current is less than 1A as no risk, 1-5 a as mild risk, 5-10A as general risk, 10-20A as heavy risk, and greater than 20A as severe risk.
  3. 3. The method of claim 2, wherein the direct current pole circle drawing method of step three is that the area in the circle with the direct current as the center and the radius of 20km is divided into serious risk areas.
  4. 4. The method according to claim 1, wherein in the third step, the connecting line is equally divided according to the risk level difference of the adjacent substations, the equally divided points, the substations and the grounding electrode O are connected to form a triangle area, and the risk area is divided based on the risk level of the substations adjacent to the triangle area, specifically: If the risk levels of adjacent substations are the same, equally dividing the connecting line, namely not equally dividing the connecting line; if the risk level of the adjacent transformer substation is the adjacent risk level, halving the connecting line, and connecting the halving point, the transformer substation and the grounding electrode O to form two triangular areas, wherein the risk level of the two triangular areas is the same as the risk level of the included transformer substation; If the risk level of the adjacent transformer substation is the cross risk level, the connecting line is divided into multiple equal parts, the equal part value is the risk level difference value corresponding to the adjacent transformer substation, the equal part points, the transformer substation and the grounding electrode O are connected to form multiple triangular areas, wherein the risk level of the triangular areas of the adjacent transformer substations at the two ends is the same as the risk level of the transformer substation, and the triangular areas in the middle are sequentially lifted one by one according to the risk level lifting direction of the triangular areas at the two ends.
  5. 5. A method of using the dc bias risk map obtained by the drawing method according to any one of claims 1 to 4, comprising: (1) Selecting a risk area to be treated according to the risk level according to the direct current magnetic bias risk graph; (2) Judging whether the transformer substations and the transformer substations connected with the transformer substations in the region are grounded or not, if not, judging whether the positions of the transformer substations and the grounding electrode are smaller than 10km or not, if so, carrying out capacitance management, if so, carrying out modeling calculation on the power grid, carrying out direct current magnetic bias analysis on the transformer substations, managing the transformer substations, and selecting management schemes according to different winding currents.
  6. 6. The method of claim 5, wherein the risk areas to be treated in step (2) include areas with risk levels of general risk, severe risk and severe risk.
  7. 7. The method of claim 5, wherein the model modeled in step (2) comprises a calculation model of a power grid topology and a soil model of a relationship between soil resistivity and depth of a transformer substation site.
  8. 8. The method of claim 5, wherein in the step (2), for different winding currents, a treatment scheme is selected, specifically, the current is less than 10A, no treatment is performed, the current is between 10 and 50A, resistance treatment is performed, and the current is greater than 50A, and capacitance treatment is performed.

Description

Drawing and using method of direct-current magnetic bias risk graph Technical Field The invention relates to the technical field of power systems, in particular to a novel drawing and using method of a direct-current magnetic bias risk diagram. Background The high-voltage direct-current transmission has the advantages of large transmission capacity, long transmission distance, low line cost, small line loss and the like when the transmission capacity is the same, has been greatly developed in China in recent years, and effectively relieves the conditions of energy and load in direct-current transmission projects such as 'West electric east transmission'. The high-voltage direct-current transmission inevitably generates a monopole earth return operation mode, and a large amount of direct current flows into the earth through the direct-current grounding electrode at the moment, so that the direct-current magnetic bias risk is caused. Dc bias refers to the generation of a dc component in the transformer's past current, causing magnetic saturation of the transformer core half-cycles, and a series of electromagnetic effects caused by the magnetic saturation. The direct current magnetic bias can cause the mechanical vibration of the transformer to be aggravated, a large amount of higher harmonics are generated, reactive power consumption is increased, relay protection requirements are increased, and stable operation of a power system is affected. Therefore, the research of evaluating and managing the direct current magnetic bias has important theoretical and practical significance. The research direction of the related institutions of the domestic electric power scientific research on the direct current magnetic bias is mainly focused on two aspects, namely (1) the surface potential change when the single pole of the convertor station is operated in the earth, the distribution condition of the direct current in the regional power grid, and (2) the harm of the direct current magnetic bias to coil equipment such as transformers and the like and corresponding treatment measures. Disclosure of Invention The invention aims to provide a novel drawing and using method of a direct-current magnetic bias risk diagram, which intuitively reflects the direct-current magnetic bias risk of a region and provides a convenient and reliable scheme for direct-current magnetic bias treatment. In order to achieve the above purpose, the invention adopts the following technical scheme: a drawing method of a DC magnetic bias risk graph comprises the following steps: step one, establishing risk level classification representation; Positioning the geographic position of each direct current pole and each transformer substation and determining the risk level of each transformer substation based on the risk level classification representation; The method comprises the steps of dividing risk level areas based on risk level division, namely dividing the risk level areas by using a direct current pole circle drawing method and a triangle area dividing method, namely dividing an area in a circle with 20km as a radius into areas with highest risk levels, connecting every two adjacent substations, equally dividing the connecting lines according to the risk level differences of the adjacent substations, connecting equal division points, the substations and a grounding electrode O to form triangle areas, dividing the risk areas based on the risk levels of the substations adjacent to the triangle areas, wherein the same area is provided with a plurality of risk levels, a low risk level is covered with a high risk level to serve as a final risk level of the area, dividing the area outside a surrounding area by using the direct current pole circle drawing method and the triangle area dividing method, prolonging the triangle side length of the triangle area division to the boundary, reducing the risk level of one level to be the risk level of the area with the nearest risk level as a reference, and finally combining and drawing the areas with the same risk level to obtain a direct current magnetic bias map. The step one risk classification is based on the magnitude of the high-voltage winding current and the magnitude of the common winding current, and specifically, the direct current is less than 1A and is defined as no risk, 1-5A is defined as mild risk, 5-10A is defined as general risk, 10-20A is defined as heavy risk, and more than 20A is defined as serious risk. Further, the direct current pole circle drawing method in the third step is to divide an area in a circle with a radius of 20km by taking direct current as a circle center into serious risk areas. Further, in the third step, the connecting lines are equally divided according to the risk level differences of adjacent substations, the equally divided points, the substations and the grounding electrode O are connected to form a triangle area, and the risk area is divided based on the risk level