A method and system for analyzing DC bias risks under the action of multiple DC projects

Abstract

The present invention discloses a method and system for analyzing DC bias risk under the action of multiple DC projects. The method includes: obtaining the historical operation data of each DC grounding electrode to determine the probability of each DC grounding electrode operating in monopolar ground return mode alone; determining the probability of each DC grounding electrode in each multiple-DC-grounding-electrode combination operating in monopolar ground return mode simultaneously; selecting the multiple-DC-grounding-electrode combinations with probabilities greater than a preset probability value; determining the DC bias risk amount of the substation in the multiple-DC-grounding-electrode area when each DC grounding electrode operates in monopolar ground return mode alone; and vectorially superimposing the DC bias risk amounts of the substation in the multiple-DC-grounding-electrode area when each DC grounding electrode in each combination operates in monopolar ground return mode alone to obtain the DC bias risk amount under the action of multiple DC projects, so as to realize the analysis of DC bias risk. The present invention can effectively evaluate the DC bias risk of the substation in the multiple-DC-grounding-electrode area.

Description

Technical Field

[0001] The present invention relates to the technical field of HVDC transmission engineering, and particularly to a method and system for analyzing DC bias risks under the action of multiple HVDC projects. Background Art

[0002] The DC bias problem in AC power grids is a series of problems induced by the rapid development of high-voltage / ultra-high-voltage DC transmission in recent years. The main manifestations of DC bias risks are the saturation of the iron core of power transformers operating grounded in the power system due to the intrusion of DC current in the ground, as well as a series of abnormal operating states such as over-excitation, vibration, heating, and noise. With the continuous expansion of the power grid scale, large AC-DC hybrid transmission systems are currently facing greater pressure of DC over-standard: the increase in the number of HVDC transmission projects will lead to more serious DC bias risks in the power grid, which are mainly manifested in the following two aspects: on the one hand, the power grid is developing rapidly, and the difficulty of selecting the location of substations is also increasing continuously. It has become difficult to select the location of newly built power stations and lines far from the influence range of DC grounding electrodes; on the other hand, the distribution of DC grounding electrodes in some areas is relatively concentrated, and the operation mode of single-pole ground return may occur simultaneously for multiple DC grounding electrodes in a short period, resulting in the DC bias current of substations near the grounding electrode being more likely to exceed the safety limit.

[0003] Therefore, for areas where the distribution of DC grounding electrodes is relatively concentrated, a method for analyzing DC bias risks under the action of multiple DC projects is needed to solve the problem of effectively evaluating the DC bias risks of substations in multi-DC grounding electrode areas. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this reason, the first object of the present invention is to provide a method for analyzing DC bias risks under the action of multiple DC projects, which can achieve the purpose of effectively evaluating the DC bias risks of substations in multi-DC grounding electrode areas.

[0005] The second object of the present invention is to provide a system for analyzing DC bias risks under the action of multiple DC projects.

[0006] To achieve the above object, the present invention is realized through the following technical solutions:

[0007] A method for analyzing DC bias risks under the action of multiple DC projects includes:

[0008] Step S1: Obtain the historical operation data of each DC grounding electrode in the multi-DC grounding electrode area, and determine the probability of each DC grounding electrode operating in single-pole ground return alone according to the historical operation data;

[0009] Step S2: Determine several combinations of multiple DC grounding electrodes, and determine the probability that each DC grounding electrode in each combination of multiple DC grounding electrodes simultaneously operates in the monopolar ground return mode according to the probability that each DC grounding electrode independently operates in the monopolar ground return mode, so as to determine the probability corresponding to each combination of multiple DC grounding electrodes;

[0010] Step S3: Compare the probability corresponding to each combination of multiple DC grounding electrodes with a preset probability value, and select the combinations of multiple DC grounding electrodes that are greater than the preset probability value;

[0011] Step S4: Determine the DC bias risk amount of the substation in the multiple DC grounding electrode area when each DC grounding electrode independently operates in the monopolar ground return mode;

[0012] Step S5: For each combination of multiple DC grounding electrodes that is greater than the preset probability value, vectorially superimpose the DC bias risk amounts of the substation in the multiple DC grounding electrode area when each DC grounding electrode in the combination independently operates in the monopolar ground return mode, and take the absolute value to obtain the DC bias risk amount under the action of multiple DC projects, so as to realize DC bias risk analysis.

[0013] Optionally, the historical operation data includes the operation days of each DC grounding electrode and the number of times of monopolar ground return operation during the period from the initial operation time to the cut-off operation time of each DC grounding electrode.

[0014] Optionally, in step S1, determining the probability that each DC grounding electrode independently operates in the monopolar ground return mode according to the historical operation data includes: calculating the ratio of the number of times of monopolar ground return operation during the period from the initial operation time to the cut-off operation time of the DC grounding electrode to the operation days of the DC grounding electrode, so as to determine the probability that the corresponding DC grounding electrode independently operates in the monopolar ground return mode.

[0015] Optionally, the DC bias risk amount is the DC bias current.

[0016] Optionally, in step S5, vectorially superimpose the DC bias risk amounts of the substation in the multiple DC grounding electrode area when each DC grounding electrode in the combination independently operates in the monopolar ground return mode according to the polarity, so as to obtain the DC bias risk amount under the action of multiple DC projects corresponding to the polarity, and the polarity includes the same polarity and the opposite polarity.

[0017] To achieve the above object, the second aspect of the present invention provides a DC bias risk analysis system under the action of multiple DC projects, including:

[0018] An acquisition module, configured to acquire the historical operation data of each DC grounding electrode in the multiple DC grounding electrode area;

[0019] A determination module, configured to determine the probability of each DC grounding electrode operating in a single-pole ground return mode alone according to the historical operation data, and to determine several combinations of multiple DC grounding electrodes, and according to the probability of each DC grounding electrode operating in a single-pole ground return mode alone, determine the probability of each DC grounding electrode in each combination of multiple DC grounding electrodes operating in a single-pole ground return mode simultaneously, so as to determine the probability corresponding to each combination of multiple DC grounding electrodes;

[0020] A selection module, configured to compare the probability corresponding to each combination of multiple DC grounding electrodes with a preset probability value, and select the combinations of multiple DC grounding electrodes that are greater than the preset probability value;

[0021] The determination module is further configured to determine the DC bias risk amount of the substation in the multi-DC grounding electrode area when each DC grounding electrode operates in a single-pole ground return mode alone;

[0022] An analysis module, for each combination of multiple DC grounding electrodes that is greater than the preset probability value, vectorially superimpose the DC bias risk amounts of the substation in the multi-DC grounding electrode area when each DC grounding electrode in the combination operates in a single-pole ground return mode alone, and take the absolute value to obtain the DC bias risk amount under the action of multiple DC projects, so as to realize DC bias risk analysis.

[0023] Optionally, the historical operation data includes the operation days of each DC grounding electrode and the number of times of single-pole ground return operation of each DC grounding electrode during the period from the initial operation time to the cut-off operation time.

[0024] Optionally, when the determination module determines the probability of each DC grounding electrode operating in a single-pole ground return mode alone according to the historical operation data, it is specifically configured to: calculate the ratio of the number of times of single-pole ground return operation of the DC grounding electrode during the period from the initial operation time to the cut-off operation time to the operation days of the DC grounding electrode, so as to determine the probability of the corresponding DC grounding electrode operating in a single-pole ground return mode alone.

[0025] Optionally, the DC bias risk amount is a DC bias current.

[0026] Optionally, the analysis module vectorially superimposes the DC bias risk amounts of the substation in the multi-DC grounding electrode area when each DC grounding electrode in the combination operates in a single-pole ground return mode alone according to the polarity, so as to obtain the DC bias risk amount under the action of multiple DC projects corresponding to the polarity, and the polarity includes the same polarity and the opposite polarity.

[0027] The present invention has at least the following technical effects:

[0028] The present invention provides a method for analyzing the DC bias risk under the action of multiple DC projects in areas where some DC grounding electrodes are relatively concentrated. The specific method is to obtain the historical operation data of each DC grounding electrode in the multi-DC grounding electrode area, determine the probability of each DC grounding electrode operating in the single-pole ground return mode alone according to the historical operation data, then determine several multi-DC grounding electrode combinations, and determine the probability of each DC grounding electrode in each multi-DC grounding electrode combination operating in the single-pole ground return mode simultaneously according to the probability of each DC grounding electrode operating in the single-pole ground return mode alone, so as to determine the probability corresponding to each multi-DC grounding electrode combination, thereby clarifying the possible operation modes of the DC grounding electrode under the action of multiple DC projects. Further, the present invention compares the probability corresponding to each multi-DC grounding electrode combination with a preset probability value, selects the multi-DC grounding electrode combinations greater than the preset probability value, then determines the substations in the multi-DC grounding electrode area according to the action range of DC bias and the coupling relationship between them when each DC grounding electrode operates in the single-pole ground return mode, and determines the DC bias risk amount of the substations in the multi-DC grounding electrode area when each DC grounding electrode operates in the single-pole ground return mode alone. Then, for each multi-DC grounding electrode combination in the multi-DC grounding electrode combinations greater than the preset probability value, the DC bias risk amounts of the substations in the multi-DC grounding electrode area when each DC grounding electrode in the combination operates in the single-pole ground return mode alone are vectorially superimposed, and the absolute value is taken to obtain the DC bias risk amount under the action of multiple DC projects, so as to realize the analysis of the DC bias risk, thereby solving the problem of effectively evaluating the DC bias risk of substations in the multi-DC grounding electrode area.

[0029] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flowchart of a method for analyzing the DC bias risk under the action of multiple DC projects according to an embodiment of the present invention.

[0031] Figure 2 It is a relative position distribution diagram of multiple DC grounding electrodes according to an embodiment of the present invention.

[0032] Figure 3 It is a DC bias simulation calculation model diagram of a substation near a DC grounding electrode according to an embodiment of the present invention.

[0033] Figure 4 It is a structural block diagram of a DC bias risk analysis system under the action of multiple DC projects according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The present embodiment will be described in detail below. Examples of the embodiment are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0035] A method and system for analyzing DC bias risk under the action of multiple DC projects will be described below with reference to the accompanying drawings.

[0036] Figure 1 The flowchart of a method for analyzing DC bias risk under the action of multiple DC projects according to an embodiment of the present invention is as follows. Figure 1 As shown, the method includes:

[0037] Step S1: Obtain the historical operation data of each DC grounding electrode in the multi-DC grounding electrode area to determine the probability of each DC grounding electrode independently occurring in the single-pole ground return operation according to the historical operation data.

[0038] Specifically, the historical operation data of each DC grounding electrode in the multi-DC grounding electrode area can be counted. The historical operation data includes the operation days of each DC grounding electrode and the number of times of single-pole ground return operation during the period from the initial operation time to the cut-off operation time of each DC grounding electrode. Then, the probability of each DC grounding electrode independently occurring in the single-pole ground return operation is calculated according to these historical operation data.

[0039] Among them, determining the probability of each DC grounding electrode independently occurring in the single-pole ground return operation according to the historical operation data includes: calculating the ratio of the number of times of single-pole ground return operation during the period from the initial operation time to the cut-off operation time of the DC grounding electrode to the operation days of the DC grounding electrode to determine the probability of the corresponding DC grounding electrode independently occurring in the single-pole ground return operation.

[0040] For example, the probabilities of each DC grounding electrode A, B, and C independently occurring in the single-pole ground return operation are calculated as P1, P2, and P3 respectively.

[0041] Step S2: Determine several multi-DC grounding electrode combinations, and determine the probability that each DC grounding electrode in each multi-DC grounding electrode combination simultaneously occurs in the single-pole ground return operation according to the probability of each DC grounding electrode independently occurring in the single-pole ground return operation, so as to determine the probability corresponding to each multi-DC grounding electrode combination.

[0042] Among them, several multi-DC grounding electrode combinations are, for example, A, B; A, C; B, C; A, B, C. Then, according to P1, P2, and P3, determine the probability that A and B in each multi-DC grounding electrode combination such as A, B simultaneously occur in the single-pole ground return operation, that is, P1*P2, to determine the probability corresponding to the combination A, B. Thus, the probability corresponding to each combination can be determined, as shown in Table 1 specifically.

[0043] Table 1 Different operating modes of DC grounding electrodes and corresponding probabilities

[0044] The grounding electrode for monopolar ground return operation appears simultaneously Probability A, B <![CDATA[P1*P2]]> A, C <![CDATA[P1*P3]]> B, C <![CDATA[P2*P3]]> A, B, C <![CDATA[P1*P2*P3]]>

[0045] Step S3: Compare the probability corresponding to each multi-DC grounding electrode combination with a preset probability value, and select the multi-DC grounding electrode combinations that are greater than the preset probability value.

[0046] Since the value of P1*P2*P3 is small and it may be less than the preset probability value, combinations A, B, and C can be excluded, and multi-DC grounding electrode combinations A, B, A, C, and B, C are selected.

[0047] Step S4: Determine the DC bias risk amount of the substation in the multi-DC grounding electrode area when each DC grounding electrode independently operates in the single-pole ground return mode.

[0048] In this embodiment, the multi-DC grounding electrode area substation can be determined according to the action range of DC bias when each DC grounding electrode operates in the single-pole ground return mode. Then, for this multi-DC grounding electrode area substation, it is determined that when each of A, B, and C, i.e., each DC grounding electrode, independently operates in the single-pole ground return mode, the DC bias risk amount of this multi-DC grounding electrode area substation, that is, the DC bias currents are I A 、I B 、I C respectively.

[0049] Step S5: For each multi-DC grounding electrode combination in the multi-DC grounding electrode combinations greater than the preset probability value, vectorially superimpose the DC bias risk amounts of the multi-DC grounding electrode area substation when each DC grounding electrode in the combination independently operates in the single-pole ground return mode, and take the absolute value to obtain the DC bias risk amount under the action of the multi-DC project, so as to realize DC bias risk analysis.

[0050] Based on the above analysis, the multi-DC grounding electrode combinations greater than the preset probability value are A, B, A, C, and B, C respectively. For each combination among these three combinations, such as combination A, B, when the DC bias risk amount I A of the multi-DC grounding electrode area substation when the A DC grounding electrode independently operates in the single-pole ground return mode and the DC bias risk amount I B of the multi-DC grounding electrode area substation when the B DC grounding electrode independently operates in the single-pole ground return mode are vectorially superimposed according to their polarities respectively, and the absolute value is taken to obtain the DC bias risk amount, that is, the DC bias current, under the action of the multi-DC project corresponding to the polarity. The polarities include the same polarity and the opposite polarity, as shown in Table 2 specifically.

[0051] Table 2 DC bias current of the multi-DC grounding electrode area substation under the action of the multi-DC project

[0052] The grounding electrode for monopolar ground return operation appears simultaneously DC bias current A, B <![CDATA[|I A +I B | <!-- 4 -->]]> A, C <![CDATA[|I A +I c |]]> B, C <![CDATA[|I B +I C |]]>

[0053] To enable those skilled in the art to clearly understand the content of the present invention, the content of the present invention will be elaborated in detail below with specific examples:

[0054] As Figure 2 shown, for the area composed of the Songjiaba, Yidu, Jiangling, and Longquan / Tuanlin four DC grounding electrodes, calculate the DC bias risk of the substations in the area with multiple DC grounding electrodes, which is specifically divided into the following steps.

[0055] Step 1: Statistically analyze the historical operation data of each DC grounding electrode in the area with multiple DC grounding electrodes, as shown in Table 3. Then, calculate the probability of each DC grounding electrode operating in the single-pole ground return mode alone:

[0056] Table 3 Relevant data of each DC grounding electrode

[0057]

[0058]

[0059] Furthermore, calculate the probability of each DC grounding electrode operating in the single-pole ground return mode since its commissioning, with the unit of day:

[0060]

[0061] Among them, the number of times of operating in the single-pole ground return mode since commissioning is the number of times of operating in the single-pole ground return mode during the period from the initial commissioning time to the cut-off time of the DC grounding electrode. P is the probability of the DC grounding electrode operating in the single-pole ground return mode since its commissioning. Thus, the following can be obtained:

[0062] The probability P1 of the Longquan / Tuanlin grounding electrode operating in the single-pole ground return mode = 4.5*10 -3 ;

[0063] The probability P2 of the Yidu grounding electrode operating in the single-pole ground return mode = 4.8*10 -3 ;

[0064] The probability P3 of the Jiangling grounding electrode operating in the single-pole ground return mode = 6.7*10 -3 ;

[0065] The probability P4 of the Songjiaba grounding electrode operating in the single-pole ground return mode = 2.8*10 -2 ;

[0066] Step 2: Calculate the probability of two or more DC grounding electrodes operating in the single-pole ground return mode simultaneously, and determine the possible different operating modes of the DC grounding electrodes and the corresponding probabilities according to the actual engineering situation.

[0067] As can be seen from Step 1, the average probability P of a monopolar ground return operation occurring in a DC grounding electrode a is: P a =(P1 + P2 + P3 + P4) / 4 = 1.1*10 -2 . Therefore, the probability of a single DC grounding electrode undergoing monopolar ground return operation is about 1%, and the probability of two DC grounding electrodes simultaneously undergoing monopolar ground return operation is 1 / 10000. Therefore, in actual engineering, the situation of three DC grounding electrodes simultaneously undergoing monopolar ground return operation mode is no longer considered, and the different operation modes and corresponding probabilities of the DC grounding electrode are shown in Table 4 as follows.

[0068] Table 4 Different operation modes and corresponding probabilities of the DC grounding electrode

[0069]

[0070]

[0071] In this embodiment, when running on a computer, by setting a preset probability value, combinations of DC grounding electrodes with very small probabilities can be excluded, such as the combination of three DC grounding electrodes in this example, to meet the requirements of actual engineering.

[0072] Step 3: Calculate the DC bias current of the substation near the DC grounding electrode, that is, the substation in the multi-DC grounding electrode area, when each DC grounding electrode independently undergoes monopolar ground return operation.

[0073] In this embodiment, a DC bias simulation calculation model can be built as shown in the appendix Figure 3 . Then, when each DC grounding electrode independently undergoes monopolar ground return operation, the DC bias current of the Chaoyang 500 kV substation near the Songjiaba grounding electrode is shown in Table 5.

[0074] Table 5 DC bias current of the Chaoyang 500 kV substation when a single DC grounding electrode undergoes monopolar ground operation

[0075]

[0076] Step 4: For the Chaoyang 500 kV substation, vectorially superimpose the DC bias currents under the independent action of multiple DC grounding electrodes according to their polarities to obtain the DC bias current under the action of a multi-DC project as shown in Table 6, and use it for DC bias analysis.

[0077] Table 6 DC bias current of the Chaoyang 500 kV substation under the action of a multi-DC project

[0078]

[0079]

[0080] To verify the effectiveness of the method of the present invention, a DC bias risk model of Chaoyang 500 kV substation under different operation modes of multiple DC grounding electrodes was further established, and the DC bias current of Chaoyang 500 kV substation was calculated. The results were consistent with those calculated by the method proposed in the present invention, verifying the effectiveness of this method and greatly reducing the calculation amount at the same time.

[0081] Figure 4 It is a structural block diagram of a DC bias risk analysis system under the action of multiple DC projects according to an embodiment of the present invention. As Figure 4 shown, the DC bias risk analysis system 10 under the action of multiple DC projects includes an acquisition module 11, a determination module 12, a selection module 13, and an analysis module 14. The acquisition module 11, the determination module 12, the selection module 13, and the analysis module 14 are connected in sequence, and the analysis module is also connected to the determination module 12.

[0082] Among them, the acquisition module 11 is used to acquire the historical operation data of each DC grounding electrode in the multiple DC grounding electrode area; the determination module 12 is used to determine the probability of each DC grounding electrode independently occurring in the monopolar ground return operation according to the historical operation data, and is used to determine several combinations of multiple DC grounding electrodes, and according to the probability of each DC grounding electrode independently occurring in the monopolar ground return operation, determine the probability of each DC grounding electrode in each combination of multiple DC grounding electrodes simultaneously occurring in the monopolar ground return operation, so as to determine the probability corresponding to each combination of multiple DC grounding electrodes; the selection module 13 is used to compare the probability corresponding to each combination of multiple DC grounding electrodes with a preset probability value, and select the combinations of multiple DC grounding electrodes greater than the preset probability value; the determination module 12 is also used to determine the DC bias risk amount, that is, the DC bias current, of the substation in the multiple DC grounding electrode area when each DC grounding electrode independently occurs in the monopolar ground return operation; the analysis module 14 is used for each combination of multiple DC grounding electrodes greater than the preset probability value, vectorially superimpose the DC bias risk amounts of the substation in the multiple DC grounding electrode area when each DC grounding electrode in the combination independently occurs in the monopolar ground return operation, and take the absolute value to obtain the DC bias risk amount under the action of multiple DC projects, so as to realize DC bias risk analysis.

[0083] It should be noted that the historical operation data includes the operation days of each DC grounding electrode and the number of times of monopolar ground return operation occurred during the period from the initial operation time to the cut-off operation time of each DC grounding electrode.

[0084] Among them, when the determination module 12 determines the probability of each DC grounding electrode operating in monopolar ground return mode alone according to historical operation data, it is specifically used for: calculating the ratio of the number of times of monopolar ground return operation of the DC grounding electrode during the period from the initial operation time to the cut-off operation time to the number of days of operation of the DC grounding electrode, so as to determine the probability of the corresponding DC grounding electrode operating in monopolar ground return mode alone. Among them, the analysis module 14 vectorially superimposes the DC bias magnetic risk amounts of the substations in the multi-DC grounding electrode area when each DC grounding electrode in the combination operates in monopolar ground return mode alone according to the polarity, so as to obtain the DC bias magnetic risk amount under the action of multiple DC projects corresponding to the polarity, where the polarity includes the same polarity and the opposite polarity.

[0085] It should be noted that for the specific implementation manner of the DC bias magnetic risk analysis system under the action of multiple DC projects in this embodiment, reference can be made to the specific implementation manner of the DC bias magnetic risk analysis method under the action of multiple DC projects above. To avoid redundancy, it will not be elaborated here.

[0086] In summary, the present invention obtains the historical operation data of each DC grounding electrode in the multi-DC grounding electrode area, determines the probability of each DC grounding electrode operating in monopolar ground return mode alone according to the historical operation data, then determines several multi-DC grounding electrode combinations, and determines the probability of each DC grounding electrode in each multi-DC grounding electrode combination operating in monopolar ground return mode simultaneously according to the probability of each DC grounding electrode operating in monopolar ground return mode alone, so as to determine the probability corresponding to each multi-DC grounding electrode combination, thereby clarifying the possible operation modes of the DC grounding electrode under the action of multiple DC projects; further, the present invention compares the probability corresponding to each multi-DC grounding electrode combination with a preset probability value, selects the multi-DC grounding electrode combinations greater than the preset probability value, then determines the substations in the multi-DC grounding electrode area according to the action range of DC bias magnetic when each DC grounding electrode operates in monopolar ground return mode and the coupling relationship between them, determines the DC bias magnetic risk amount of the substations in the multi-DC grounding electrode area when each DC grounding electrode operates in monopolar ground return mode alone, and then for each multi-DC grounding electrode combination in the multi-DC grounding electrode combinations greater than the preset probability value, vectorially superimposes the DC bias magnetic risk amounts of the substations in the multi-DC grounding electrode area when each DC grounding electrode in the combination operates in monopolar ground return mode alone, and takes the absolute value to obtain the DC bias magnetic risk amount under the action of multiple DC projects, so as to realize the DC bias magnetic risk analysis, thereby solving the problem of effectively evaluating the DC bias magnetic risk of substations in the multi-DC grounding electrode area.

[0087] It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0088] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A method for analyzing DC bias risk under the action of multiple DC projects, characterized in that Including: Step S1: Obtain the historical operation data of each DC grounding electrode in the multi-DC grounding electrode area, and determine the probability of each DC grounding electrode operating in a single-pole ground return mode alone according to the historical operation data; Step S2: Determine several multi-DC grounding electrode combinations, and determine the probability of each DC grounding electrode operating in a single-pole ground return mode simultaneously in each multi-DC grounding electrode combination according to the probability of each DC grounding electrode operating in a single-pole ground return mode alone, so as to determine the probability corresponding to each multi-DC grounding electrode combination; Step S3: Compare the probability corresponding to each multi-DC grounding electrode combination with a preset probability value, and select the multi-DC grounding electrode combinations greater than the preset probability value; Step S4: Determine the DC bias risk amount of the substation in the multi-DC grounding electrode area when each DC grounding electrode operates in a single-pole ground return mode alone; Step S5: For each of the multi-DC grounding electrode combinations greater than the preset probability value, vectorially superimpose the DC bias risk amounts of the substation in the multi-DC grounding electrode area when each DC grounding electrode in the combination operates in a single-pole ground return mode alone, and take the absolute value to obtain the DC bias risk amount under the action of the multi-DC project, so as to realize DC bias risk analysis.

2. The method for analyzing DC bias risk under the action of multiple DC projects according to claim 1, wherein The historical operation data includes the operation days of each DC grounding electrode and the number of times of operating in a single-pole ground return mode during the period from the initial operation time to the cut-off operation time of each DC grounding electrode.

3. The method for analyzing DC bias risk under the action of multiple HVDC projects according to claim 2, wherein In the step S1, determining the probability of each DC grounding electrode operating in a single-pole ground return mode alone according to the historical operation data includes: calculating the ratio of the number of times of operating in a single-pole ground return mode during the period from the initial operation time to the cut-off operation time of the DC grounding electrode to the operation days of the DC grounding electrode, so as to determine the probability of the corresponding DC grounding electrode operating in a single-pole ground return mode alone.

4. The method for analyzing DC bias risk under the action of multiple DC projects according to claim 1, wherein The DC bias risk amount is the DC bias current.

5. The method for analyzing DC bias risk under the action of multiple DC projects according to any one of claims 1-4, characterized in that In the step S5, vectorially superimpose the DC bias risk amounts of the substation in the multi-DC grounding electrode area when each DC grounding electrode in the combination operates in a single-pole ground return mode alone according to the polarity to obtain the DC bias risk amount under the action of the multi-DC project corresponding to the polarity, and the polarity includes the same polarity and the opposite polarity.

6. A DC bias risk analysis system under the action of multiple DC projects, characterized in that, Including: An acquisition module for acquiring the historical operation data of each DC grounding electrode in the multi-DC grounding electrode area; A determination module for determining the probability of each DC grounding electrode operating in a single-pole ground return mode alone according to the historical operation data, and for determining several multi-DC grounding electrode combinations, and for determining the probability of each DC grounding electrode operating in a single-pole ground return mode simultaneously in each multi-DC grounding electrode combination according to the probability of each DC grounding electrode operating in a single-pole ground return mode alone, so as to determine the probability corresponding to each multi-DC grounding electrode combination; A selection module for comparing the probability corresponding to each multi-DC grounding electrode combination with a preset probability value and selecting the multi-DC grounding electrode combinations greater than the preset probability value; The determination module is further configured to determine the DC bias risk amount of the substation in the multi-DC grounding electrode area when each DC grounding electrode operates in a single-pole ground return mode alone; An analysis module is configured to, for each multi - DC grounding electrode combination with a probability greater than the preset probability value, vectorially superimpose the DC bias magnetic risk amounts of the multi - DC grounding electrode area substation when each DC grounding electrode in the combination operates in monopolar ground return mode alone, and take the absolute value to obtain the DC bias magnetic risk amount under the action of multiple DC projects, so as to achieve DC bias magnetic risk analysis.

7. The DC bias risk analysis system under the action of multiple DC projects according to claim 6, characterized in that, The historical operation data includes the operation days of each DC grounding electrode and the number of times of monopolar ground return operation of each DC grounding electrode during the period from the initial operation time to the cut - off operation time.

8. The DC bias risk analysis system under the action of multiple DC projects as described in claim 7, wherein When the determination module determines the probability of each DC grounding electrode operating in monopolar ground return mode alone according to the historical operation data, it is specifically configured to: calculate the ratio of the number of times of monopolar ground return operation of the DC grounding electrode during the period from the initial operation time to the cut - off operation time to the operation days of the DC grounding electrode, so as to determine the probability of the corresponding DC grounding electrode operating in monopolar ground return mode alone.

9. The DC bias risk analysis system under the action of multiple DC projects as described in claim 6, characterized in that, The DC bias magnetic risk amount is the DC bias magnetic current.

10. The DC bias risk analysis system under the action of multiple DC projects according to any one of claims 6-9, characterized in that, The analysis module vectorially superimposes the DC bias magnetic risk amounts of the multi - DC grounding electrode area substation when each DC grounding electrode in the combination operates in monopolar ground return mode alone according to the polarity, so as to obtain the DC bias magnetic risk amount under the action of multiple DC projects corresponding to the polarity, and the polarity includes the same polarity and the opposite polarity.

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