Method and system for compositely judging commutation failure of high-voltage direct-current power transmission system

Abstract

The invention provides a commutation failure composite judgment method and system for a high-voltage direct-current power transmission system. The method comprises the following steps: acquiring an extinction angle of the high-voltage direct-current power transmission system in commutation control; determining a risk level of commutation failure of the high-voltage direct-current power transmission system based on the extinction angle; when the risk level is a second level, acquiring commutation equivalent inductance, commutation current, initial phase voltage and terminal phase voltage of the high-voltage direct-current power transmission system; based on the commutation equivalent inductance, the commutation current, the initial phase voltage and the end-point phase voltage, performing re-judgment by adopting a commutation voltage time area, and determining whether commutation of the high-voltage direct-current power transmission system fails or not; wherein the risk level comprises a first level and a second level. According to the technical scheme provided by the invention, multiple and massive integral operation of the commutation voltage time area is avoided, the requirement of online real-time calculation can be met, and the method has relatively high precision and relatively high judgment speed.

Description

Technical Field

[0001] The present application relates to the field of direct current transmission of electric power systems, and in particular to a composite judgment method and system for commutation failure in high-voltage direct current transmission systems. Background Art

[0002] The bipolar commutation converter type high voltage direct current system undertakes the important function of transmitting electricity from west to east and is an important part of the AC / DC hybrid large power grid. However, a simple AC fault at the AC bus near the receiving end may lead to a series of chain failures such as commutation failure and even DC blocking and power flow transfer. The main causes of commutation failure are the reduction of commutation voltage, the increase of DC current and the loss of trigger pulses.

[0003] At present, the amount of calculation required to judge commutation failure is large, resulting in slow judgment speed and low accuracy. Therefore, it is urgent to propose a solution that can quickly and accurately judge whether commutation has failed to ensure the safe and stable operation of the power grid. Summary of the invention

[0004] The present application provides a composite judgment method and system for commutation failure in a high-voltage direct current transmission system, so as to at least solve the technical problems of slow judgment speed and low accuracy.

[0005] The first embodiment of the present application provides a composite judgment method for commutation failure in a high-voltage direct current transmission system, the method comprising:

[0006] Obtaining the arc extinction angle in commutation control of high voltage direct current transmission system;

[0007] Determining a risk level of commutation failure in the high voltage direct current power transmission system based on the arc extinction angle;

[0008] When the risk level is the second level, obtaining the commutation equivalent inductance, commutation current, starting phase voltage, and ending phase voltage of the high voltage direct current transmission system;

[0009] Based on the commutation equivalent inductance, commutation current, starting phase voltage, and end phase voltage, and using the commutation voltage-time area for re-judgment, determining whether the high-voltage direct current transmission system has commutation failure;

[0010] The risk levels include: first level and second level.

[0011] Preferably, the risk of commutation failure occurring at the first level is smaller than the risk of commutation failure occurring at the second level.

[0012] Furthermore, before determining the risk level of commutation failure in the high-voltage direct current power transmission system based on the arc extinction angle, the method further includes:

[0013] Obtain the minimum arc extinction angle of the inverter side of the high voltage direct current transmission system when performing arc extinction angle control.

[0014] Furthermore, the determining the risk level of commutation failure in the high voltage direct current power transmission system based on the arc extinction angle includes:

[0015] It is determined whether the arc extinction angle is less than the minimum arc extinction angle. If so, it is determined that the risk level of commutation failure of the high-voltage direct current transmission system is the second level; otherwise, the risk level of commutation failure of the high-voltage direct current transmission system is the first level.

[0016] Furthermore, the determining whether the commutation failure of the high-voltage direct current power transmission system occurs based on the commutation equivalent inductance, the commutation current, the starting phase voltage, and the ending phase voltage and using the commutation voltage-time area for re-judgment includes:

[0017] Determine whether the formula is satisfied If yes, the commutation of the high-voltage direct current power transmission system is successful; otherwise, the commutation of the high-voltage direct current power transmission system fails;

[0018] Where, L c is the commutation equivalent inductance, i m is the commutation current, γmin is the minimum arc extinction angle, α is the leading firing angle in HVDC transmission control, ω is the rated operating parameter of the system, u n is the voltage of the terminal phase n, u m is the voltage of the starting phase m.

[0019] The second embodiment of the present application provides a high-voltage direct current transmission system commutation failure composite judgment system, including:

[0020] A first acquisition module is used to obtain an arc extinction angle in a commutation control of a high voltage direct current transmission system;

[0021] A first determination module is used to determine the risk level of commutation failure in the high voltage direct current power transmission system based on the arc extinction angle;

[0022] A second acquisition module is used to acquire the commutation equivalent inductance, commutation current, starting phase voltage, and end phase voltage of the high voltage direct current transmission system when the risk level is the second level;

[0023] A re-judgment module, used to determine whether the commutation of the high-voltage direct current transmission system fails based on the commutation equivalent inductance, the commutation current, the starting phase voltage, the ending phase voltage, and the commutation voltage-time area;

[0024] The risk levels include: first level and second level.

[0025] Preferably, the risk of commutation failure occurring at the first level is smaller than the risk of commutation failure occurring at the second level.

[0026] Furthermore, the system also includes:

[0027] The third acquisition module is used to obtain the minimum arc extinction angle when the inverter side of the high voltage direct current transmission system performs arc extinction angle control.

[0028] Furthermore, the first determining module is further configured to:

[0029] It is determined whether the arc extinction angle is less than the minimum arc extinction angle. If so, it is determined that the risk level of commutation failure of the high-voltage direct current transmission system is the second level; otherwise, the risk level of commutation failure of the high-voltage direct current transmission system is the first level.

[0030] Furthermore, the re-judgment module is also used for:

[0031] Determine whether the formula is satisfied If yes, the commutation of the high-voltage direct current power transmission system is successful; otherwise, the commutation of the high-voltage direct current power transmission system fails;

[0032] Where, L c is the commutation equivalent inductance, i m is the commutation current, γmin is the minimum arc extinction angle, α is the leading trigger angle in high-voltage DC transmission control, ω is the rated operating parameter of the system, and u n is the voltage of the terminal phase n, u m is the voltage of the starting phase m.

[0033] The technical solution provided by the embodiments of the present application brings at least the following beneficial effects:

[0034] The present application proposes a composite judgment method and system for commutation failure of a high-voltage direct current transmission system, the method comprising: obtaining the arc extinction angle of the high-voltage direct current transmission system in commutation control; determining the risk level of commutation failure of the high-voltage direct current transmission system based on the arc extinction angle; when the risk level is the second level, obtaining the commutation equivalent inductance, commutation current, starting phase voltage, and end phase voltage of the high-voltage direct current transmission system; based on the commutation equivalent inductance, commutation current, starting phase voltage, and end phase voltage, and using the commutation voltage time area for complex judgment, determine whether the high-voltage direct current transmission system has commutation failure; wherein the risk level includes: the first level and the second level. The technical solution proposed in the present application avoids multiple and large-scale integral operations of the commutation voltage time area, can meet the requirements of online real-time calculation, and has high accuracy and fast judgment speed.

[0035] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0037] Figure 1 A flowchart of a composite judgment method for commutation failure in a high-voltage direct current transmission system provided according to an embodiment of the present application;

[0038] Figure 2 A schematic diagram of the structure of a six-pulse inverter provided according to an embodiment of the present application;

[0039] Figure 3 A first structural diagram of a composite judgment system for commutation failure in a high-voltage direct current transmission system provided according to an embodiment of the present application;

[0040] Figure 4 This is a second structural diagram of a high-voltage direct current transmission system commutation failure composite judgment system provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0041] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0042] The present application proposes a composite judgment method and system for commutation failure of a high-voltage direct current transmission system, the method comprising: obtaining the arc extinction angle of the high-voltage direct current transmission system in commutation control; determining the risk level of commutation failure of the high-voltage direct current transmission system based on the arc extinction angle; when the risk level is the second level, obtaining the commutation equivalent inductance, commutation current, starting phase voltage, and end phase voltage of the high-voltage direct current transmission system; based on the commutation equivalent inductance, commutation current, starting phase voltage, and end phase voltage, and using the commutation voltage time area for composite judgment, determining whether the high-voltage direct current transmission system has commutation failure; wherein the risk level includes: the first level and the second level. The technical solution proposed in the present application avoids multiple and large-scale integral operations of the commutation voltage time area, can meet the requirements of online real-time calculation, and has high accuracy and fast judgment speed.

[0043] A method and system for composite determination of commutation failure in a high-voltage direct current transmission system according to an embodiment of the present application will be described below with reference to the accompanying drawings.

[0044] Embodiment 1

[0045] Figure 1 Flow chart of a composite judgment method for commutation failure of a high voltage direct current transmission system provided according to one embodiment of the present application, as shown in FIG. Figure 1 As shown, the method includes:

[0046] Step 1: Obtain the arc extinction angle in the commutation control of the HVDC transmission system.

[0047] It should be noted that before step 2, the following steps are also included:

[0048] Obtain the minimum arc extinction angle of the inverter side of the high voltage direct current transmission system when performing arc extinction angle control.

[0049] Step 2: Determine the risk level of commutation failure in the high-voltage direct current power transmission system based on the arc extinction angle; wherein the risk level includes: a first level and a second level.

[0050] It should be noted that the risk of commutation failure occurring at the first level is smaller than the risk of commutation failure occurring at the second level.

[0051] In the embodiment of the present disclosure, step 2 specifically includes:

[0052] Determine whether the arc extinction angle is less than the minimum arc extinction angle. If so, determine that the risk level of commutation failure in the high-voltage direct current transmission system is the second level, i.e., γ<γ min , where γ is the arc extinction angle in the commutation control of the HVDC transmission system, γmin is the minimum arc extinction angle;

[0053] Otherwise, the risk level of commutation failure in the high-voltage direct current power transmission system is the first level.

[0054] Step 3: When the risk level is the second level, the commutation equivalent inductance, commutation current, starting phase voltage, and ending phase voltage of the high voltage direct current transmission system are obtained.

[0055] Step 4: Based on the commutation equivalent inductance, commutation current, starting phase voltage, and ending phase voltage, a re-judgment is performed using the commutation voltage-time area to determine whether the high-voltage direct current transmission system has commutation failure.

[0056] In the embodiment of the present disclosure, step 4 specifically includes:

[0057] Determine whether the formula is satisfied If yes, the commutation of the high-voltage direct current power transmission system is successful; otherwise, the commutation of the high-voltage direct current power transmission system fails;

[0058] Where, L cis the commutation equivalent inductance, i m is the commutation current, γmin is the minimum arc extinction angle, α is the leading firing angle in HVDC transmission control, ω is the rated operating parameter of the system, u n is the voltage of the terminal phase n, u m is the voltage of the starting phase m.

[0059] Specifically, based on the method provided in this embodiment, it is possible to judge whether the commutation of the six-pulse inverter fails, wherein the six-pulse inverter is Figure 2 As shown, the judgment method is as follows:

[0060] Taking VT3→VT5 commutation as an example, the initial state is that VT3 and VT4 are turned on. When VT5 is turned on, VT3 starts to commutate to VT5. VT3 fails to complete the commutation or when VT3 is at the BC line voltage U bc If the blocking capability cannot be restored under the reverse voltage, VT3 will be turned on again immediately, and VT3→VT5 will fail to switch. min If the commutation is completed before then, the thyristor cannot recover its blocking capability, which will lead to commutation failure.

[0061] The present embodiment proposes a composite judgment method for commutation failure of a high-voltage direct current transmission system, which judges the risk of commutation failure based on the arc extinction angle, and selects whether to use the commutation voltage-time area for re-judgment according to the risk of commutation failure. This can avoid multiple and large-scale integral operations and meet the requirements of online real-time calculation.

[0062] In summary, the composite judgment method for commutation failure in a high-voltage direct current transmission system proposed in this embodiment avoids multiple and large-scale integral operations of commutation voltage, time and area, can meet the requirements of online real-time calculation, and has high accuracy and fast judgment speed.

[0063] Embodiment 2

[0064] Figure 3 FIG. 1 is a structural diagram of a high voltage direct current transmission system commutation failure composite judgment system according to an embodiment of the present application. Figure 3 As shown, the system comprises:

[0065] A first acquisition module 100 is used to acquire an arc extinction angle in a commutation control of a high voltage direct current transmission system;

[0066] A first determination module 200, configured to determine a risk level of commutation failure in the high voltage direct current power transmission system based on the arc extinction angle;

[0067] The risk levels include: first level and second level.

[0068] The risk of commutation failure occurring at the first level is smaller than the risk of commutation failure occurring at the second level.

[0069] A second acquisition module 300 is used to acquire the commutation equivalent inductance, commutation current, starting phase voltage, and end phase voltage of the high voltage direct current transmission system when the risk level is the second level;

[0070] A re-judgment module 400, configured to determine whether the HVDC power transmission system has failed in commutation based on the commutation equivalent inductance, commutation current, starting phase voltage, and ending phase voltage, and using the commutation voltage-time area for re-judgment;

[0071] In the embodiments of the present disclosure, Figure 4 As shown, the system also includes:

[0072] The third acquisition module 500 is used to acquire the minimum arc extinction angle when the inverter side of the high voltage direct current transmission system performs arc extinction angle control.

[0073] In the embodiment of the present disclosure, the first determining module 100 is further configured to:

[0074] It is determined whether the arc extinction angle is less than the minimum arc extinction angle. If so, it is determined that the risk level of commutation failure of the high-voltage direct current transmission system is the second level; otherwise, the risk level of commutation failure of the high-voltage direct current transmission system is the first level.

[0075] In the embodiment of the present disclosure, the re-judgment module 400 is further used for:

[0076] Determine whether the formula is satisfied If yes, the commutation of the high-voltage direct current power transmission system is successful; otherwise, the commutation of the high-voltage direct current power transmission system fails;

[0077] Where, L c is the commutation equivalent inductance, i m is the commutation current, γmin is the minimum arc extinction angle, α is the leading trigger angle in high-voltage DC transmission control, ω is the rated operating parameter of the system, and u n is the voltage of the terminal phase n, u m is the voltage of the starting phase m.

[0078] In summary, the composite judgment system for commutation failure of a high-voltage direct current transmission system proposed in this embodiment avoids multiple and large-scale integral operations of commutation voltage, time and area, can meet the requirements of online real-time calculation, and has high accuracy and fast judgment speed.

[0079] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0080] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0081] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A composite judgment method for commutation failure in a high voltage direct current transmission system, characterized in that: The method comprises: Obtaining the arc extinction angle in commutation control of high voltage direct current transmission system; Determining a risk level of commutation failure in the high voltage direct current power transmission system based on the arc extinction angle; When the risk level is the second level, obtaining the commutation equivalent inductance, commutation current, starting phase voltage, and ending phase voltage of the high voltage direct current transmission system; Based on the commutation equivalent inductance, commutation current, starting phase voltage, and end phase voltage, and using the commutation voltage-time area for re-judgment, determining whether the high-voltage direct current power transmission system has commutation failure; The risk levels include: first level and second level.

2. The method according to claim 1, characterized in that The risk of commutation failure occurring at the first level is smaller than the risk of commutation failure occurring at the second level.

3. The method according to claim 2, characterized in that Before determining the risk level of commutation failure in the high voltage direct current power transmission system based on the arc extinction angle, the method further includes: Obtain the minimum arc extinction angle of the inverter side of the high voltage direct current transmission system when performing arc extinction angle control.

4. The method according to claim 3, characterized in that The determining, based on the arc extinction angle, the risk level of commutation failure in the high voltage direct current transmission system comprises: It is determined whether the arc extinction angle is less than the minimum arc extinction angle. If so, it is determined that the risk level of commutation failure of the high-voltage direct current transmission system is the second level; otherwise, the risk level of commutation failure of the high-voltage direct current transmission system is the first level.

5. The method according to claim 4, characterized in that The method of determining whether the high-voltage direct current power transmission system fails in commutation based on the commutation equivalent inductance, the commutation current, the starting phase voltage, and the ending phase voltage and using the commutation voltage-time area for re-judgment includes: Determine whether the formula is satisfied If yes, the commutation of the high-voltage direct current transmission system is successful; otherwise, the commutation of the high-voltage direct current transmission system fails; Where, L c is the commutation equivalent inductance, i m is the commutation current, γmin is the minimum arc extinction angle, α is the leading firing angle in HVDC transmission control, ω is the rated operating parameter of the system, u n is the voltage of the terminal phase n, u m is the voltage of the starting phase m.

6. A high voltage direct current transmission system commutation failure composite judgment system, characterized in that: The system comprises: A first acquisition module is used to obtain an arc extinction angle in a commutation control of a high voltage direct current transmission system; A first determination module, configured to determine a risk level of commutation failure in the high voltage direct current power transmission system based on the arc extinction angle; A second acquisition module is used to acquire the commutation equivalent inductance, commutation current, starting phase voltage, and end phase voltage of the high voltage direct current transmission system when the risk level is the second level; A re-judgment module, used to determine whether the commutation of the high-voltage direct current transmission system fails based on the commutation equivalent inductance, the commutation current, the starting phase voltage, the ending phase voltage, and the commutation voltage-time area; The risk levels include: first level and second level.

7. The system according to claim 6, characterized in that The risk of commutation failure occurring at the first level is smaller than the risk of commutation failure occurring at the second level.

8. The system according to claim 7, characterized in that The system further comprises: The third acquisition module is used to obtain the minimum arc extinction angle when the inverter side of the high voltage direct current transmission system performs arc extinction angle control.

9. The system according to claim 8, characterized in that The first determining module is further used for: It is determined whether the arc extinction angle is less than the minimum arc extinction angle. If so, it is determined that the risk level of commutation failure of the high-voltage direct current transmission system is the second level; otherwise, the risk level of commutation failure of the high-voltage direct current transmission system is the first level.

10. The system according to claim 9, characterized in that The re-judgment module is also used for: Determine whether the formula is satisfied If yes, the commutation of the high-voltage direct current transmission system is successful; otherwise, the commutation of the high-voltage direct current transmission system fails; Where, L c is the commutation equivalent inductance, i m is the commutation current, γmin is the minimum arc extinction angle, α is the leading trigger angle in high-voltage DC transmission control, ω is the rated operating parameter of the system, and u n is the voltage of the terminal phase n, u m is the voltage of the starting phase m.

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