CN117639126A - Threshold value calculation method, device, equipment, storage medium and program product - Google Patents
Threshold value calculation method, device, equipment, storage medium and program product Download PDFInfo
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Abstract
The application relates to a threshold value calculation method, a threshold value calculation device, a threshold value calculation storage medium and a threshold value calculation program product. The method comprises the following steps: determining system operation data corresponding to a plurality of possible direct current power levels of a direct current system connected with the converter station respectively; for each possible direct current power level, determining a reactive power threshold value according to system operation data corresponding to the possible direct current power level; and the reactive power threshold value corresponding to each possible direct current power level is used for switching the alternating current filter according to the reactive power threshold value corresponding to each possible direct current power level by the power system when the converter station normally operates. The method can accurately calculate the reactive power threshold value of the switching of the alternating current filter under each possible direct current power level.
Description
Technical Field
The present disclosure relates to the field of direct current transmission control protection technologies, and in particular, to a threshold value calculation method, apparatus, device, storage medium, and program product.
Background
Reactive power balance between the converter station and the alternating current system can be achieved through switching of the alternating current filter, but switching of the alternating current filter is limited by the minimum filter requirement input group number, and excessive reactive power provided by the alternating current filter can cause problems of over-high alternating current bus voltage and the like. Since the reactive compensation capacity of the ac filter cannot be steplessly adjusted, a suitable threshold value needs to be set.
The high-voltage direct-current transmission project generally carries out deep research on setting of the switching reactive power threshold value of the alternating-current filter along the empirical threshold value of the prior ABB or SIEMENS project without published literature data.
However, the conventional switching reactive power threshold value of the ac filter is configured according to engineering experience, and cannot accurately reflect the switching reactive power threshold value of the ac filter under actual working conditions, and often, the switching of the ac filter due to the unreasonable setting of the switching reactive power threshold value is also caused, and when the frequent switching of the ac filter is serious, the whole dc transmission system may be shut down.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a threshold value calculating method, apparatus, device, storage medium and program product capable of accurately calculating the switching reactive power threshold value of an ac filter.
In a first aspect, the present application provides a method for calculating a threshold value, including: determining system operation data corresponding to a plurality of possible direct current power levels of a direct current system connected with the converter station respectively; for each possible direct current power level, determining a reactive power threshold value according to system operation data corresponding to the possible direct current power level; the reactive power threshold value corresponding to each possible direct current power level is used for switching the alternating current filter according to the reactive power threshold value corresponding to each possible direct current power level when the power system operates normally.
In one embodiment, the system operation data includes first system operation data of a dc system, second system operation data of an ac system connected to the converter station, and third system operation data corresponding to the ac filter, and determining the reactive power threshold value according to the system operation data corresponding to the possible dc power level includes: and calculating a reactive power threshold value corresponding to the possible direct current power level according to the first system operation data, the second system operation data and the third system operation data corresponding to the possible direct current power level.
In one embodiment, the first system operational data includes a dc voltage and a dc current, the second system operational data includes an ac bus voltage effective value and an ac voltage change rate, and determining system operational data corresponding to a plurality of possible dc power levels of a dc system connected to the converter station, respectively, includes: for each possible direct current power level, determining the direct current voltage, the direct current and the effective value of alternating current bus voltage corresponding to the possible direct current power level according to a pre-established high-voltage direct current transmission system model, and obtaining a pre-set alternating current voltage change rate.
In one embodiment, the third system operation data includes an ac filter input group number, and determining system operation data corresponding to each of a plurality of possible dc power levels of a dc system connected to the converter station includes: for each possible direct current power level, inquiring a pre-established corresponding relation table according to the possible direct current power level, wherein the corresponding relation table stores a plurality of groups of corresponding relations between the possible direct current power level and the input groups of the alternating current filter; and obtaining the input group number of the alternating current filter corresponding to the possible direct current power level according to the query result.
In one embodiment, determining the reactive power threshold value from system operation data corresponding to a possible dc power level includes: calculating a reactive power threshold based on a first formula; the first formula includes:
wherein Q is sys For the reactive power exchange between the converter station and the AC system, Q ref For minimum set value of reactive power, Q margin For reactive power threshold value, I d Is direct current, k is the transformation ratio of a converter transformer, U ac Is an alternating current motherEffective value of line voltage DeltaU ac For the rate of change of the alternating voltage, U d Is of direct current voltage, N c Input group number for AC filter, Q cN Is the rated capacity of a single set of variable current filters.
In one embodiment, the method further comprises: acquiring the actual direct current power level of a direct current system in the working process of the converter station; determining a reactive power threshold value corresponding to the actual direct current power level according to the reactive power threshold values corresponding to the actual direct current power level and the multiple possible direct current power levels respectively; and switching the alternating current filter according to the reactive power threshold value corresponding to the actual direct current power level.
In a second aspect, the present application further provides a threshold value calculating apparatus, including:
a first determining module, configured to determine system operation data corresponding to a plurality of possible dc power levels of a dc system connected to the converter station, respectively; the second determining module is used for determining reactive power threshold values according to system operation data corresponding to the possible direct current power levels for all the possible direct current power levels; the reactive power threshold value corresponding to each possible direct current power level is used for switching the alternating current filter according to the reactive power threshold value corresponding to each possible direct current power level when the power system operates normally.
In one embodiment, the system operation data includes first system operation data of a direct current system, second system operation data of an alternating current system connected with the converter station, and third system operation data corresponding to the alternating current filter, and the second determining module is specifically configured to: and calculating a reactive power threshold value corresponding to the possible direct current power level according to the first system operation data, the second system operation data and the third system operation data corresponding to the possible direct current power level.
In one embodiment, the first system operation data includes a dc voltage and a dc current, the second system operation data includes an ac bus voltage effective value and an ac voltage change rate, and the first determining module is specifically configured to: for each possible direct current power level, determining the direct current voltage, the direct current and the effective value of alternating current bus voltage corresponding to the possible direct current power level according to a pre-established high-voltage direct current transmission system model, and obtaining a pre-set alternating current voltage change rate.
In one embodiment, the third system operation data includes an ac filter input group number, and the first determining module is specifically configured to: for each possible direct current power level, inquiring a pre-established corresponding relation table according to the possible direct current power level, wherein the corresponding relation table stores a plurality of groups of corresponding relations between the possible direct current power level and the input groups of the alternating current filter; and obtaining the input group number of the alternating current filter corresponding to the possible direct current power level according to the query result.
In one embodiment, the second determining module is specifically configured to: calculating a reactive power threshold based on a first formula; the first formula includes:
wherein Q is sys For the reactive power exchange between the converter station and the AC system, Q ref For minimum set value of reactive power, Q margin For reactive power threshold value, I d Is direct current, k is the transformation ratio of a converter transformer, U ac Is the effective value of the voltage of the alternating current bus, delta u ac For the rate of change of the alternating voltage, U d Is of direct current voltage, N c Input group number for AC filter, Q cN Is the rated capacity of a single set of variable current filters.
In one embodiment, the apparatus further comprises a third confirmation module; the third confirmation module is used for acquiring the actual direct current power level of the direct current system in the working process of the converter station; determining a reactive power threshold value corresponding to the actual direct current power level according to the reactive power threshold values corresponding to the actual direct current power level and the multiple possible direct current power levels respectively; and switching the alternating current filter according to the reactive power threshold value corresponding to the actual direct current power level.
In a third aspect, the present application also provides a computer device comprising a memory storing a computer program and a processor implementing the method of any of the first aspects above when executing the computer program.
In a fourth aspect, the present application also provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method of any of the first aspects described above.
In a fifth aspect, the present application also provides a computer program product comprising a computer program which, when executed by a processor, implements the method of any of the first aspects described above.
The threshold value calculating method, the device, the equipment, the storage medium and the program product firstly determine system operation data corresponding to a plurality of possible direct current power levels of a direct current system connected with a converter station respectively; determining reactive power threshold values according to system operation data corresponding to the possible direct current power levels for the possible direct current power levels; the reactive power threshold value corresponding to each possible direct current power level is used for switching the alternating current filter according to the reactive power threshold value corresponding to each possible direct current power level when the power system operates normally. Therefore, the reactive power threshold value of the alternating current filter switching under each possible direct current power level can be accurately calculated, frequent switching of the alternating current filter generated by the conventional engineering adopting the fixed switching limit value is avoided, faults of the alternating current filter can be reduced, the method has important significance for maintaining the stability of a direct current system and ensuring the normal operation of the power system, and the power system is prevented from being damaged more greatly.
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In order to more clearly illustrate the embodiments of the present application or the technical solutions in the related art, the drawings that are required to be used in the embodiments or the related technical descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for a person having ordinary skill in the art.
FIG. 1 is a flow chart of a threshold value calculation method in one embodiment;
FIG. 2 is a flowchart of a threshold value calculation method according to another embodiment;
FIG. 3 is a flowchart of a threshold value calculation method according to another embodiment;
FIG. 4 is a block diagram of a threshold calculation device in one embodiment;
FIG. 5 is a block diagram of a threshold calculation device in one embodiment;
fig. 6 is an internal structural diagram of a computer device in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
The high-voltage direct-current transmission project has important roles in the aspects of long-distance large-capacity transmission and grid interconnection, plays an important role in the construction of Western electric east transmission projects and alternating-current and direct-current interconnection grids in China, reactive power is required to be consumed in a rectification state or an inversion state of a converter station, a large number of harmonic waves are generated when the converter is in conversion, and therefore an alternating-current filter is required to be put into for filtering the harmonic waves, and reactive power is provided. Reactive power balance between the converter station and the alternating current system can be achieved through switching of the alternating current filter, but switching of the alternating current filter is limited by the minimum filter requirement input group number, and excessive reactive power provided by the alternating current filter can cause problems of over-high alternating current bus voltage and the like. Since the reactive compensation capacity of the ac filter cannot be steplessly adjusted, a suitable threshold value needs to be set.
The high-voltage direct-current transmission project generally carries out deep research on setting of the switching reactive power threshold value of the alternating-current filter along the empirical threshold value of the prior ABB or SIEMENS project without published literature data.
However, the conventional switching reactive power threshold value of the ac filter is configured according to engineering experience, and cannot accurately reflect the switching reactive power threshold value of the ac filter under actual working conditions, and often, the switching of the ac filter due to the unreasonable setting of the switching reactive power threshold value is also caused, and when the frequent switching of the ac filter is serious, the whole dc transmission system may be shut down.
In view of this, the present application provides a threshold value calculating method capable of accurately calculating the switching reactive power threshold value of the ac filter. In the threshold value calculating method provided in the embodiment of the present application, the execution body may be a threshold value calculating device, where the threshold value calculating device may be implemented by software, hardware, or a combination of software and hardware, and the threshold value calculating device may be disposed in the power system.
In an exemplary embodiment, as shown in fig. 1, a threshold value calculating method is provided, which includes the following steps 101 to 102. Wherein:
s101, determining system operation data corresponding to a plurality of possible direct current power levels of a direct current system connected with a converter station.
Alternatively, the direct current system may refer to a high voltage direct current transmission system, and the converter station may refer to a station established in the high voltage direct current transmission system for completing conversion from alternating current to direct current or from direct current to alternating current and meeting requirements of the power system on safety and stability and electric energy quality.
Alternatively, the system operation data corresponding to the dc power levels may be empirical data set according to engineering experience, or may be calculation data obtained after model simulation calculation is established.
S102, for each possible direct current power level, determining a reactive power threshold value according to system operation data corresponding to the possible direct current power level.
The reactive power threshold value corresponding to each possible direct current power level is used for switching the alternating current filter according to the reactive power threshold value corresponding to each possible direct current power level when the power system operates normally.
Alternatively, the reactive power control of the high-voltage direct-current transmission system has two operation modes, namely a fixed reactive power Mode (fixed Q-Mode) and a fixed alternating voltage Mode (fixed U-Mode). At present, most direct current projects are in a constant Q mode in a reactive power control mode under normal operation.
In one possible implementation, determining the reactive power threshold value from system operation data corresponding to the possible dc power level includes:
in the fixed reactive power control mode, the switching strategy of the alternating current filter is as follows:
(1) If Q sys ＞Q ref +Q margin If so, then a DC control system in the power system issues a cut-out set of AC filter commands.
(2) If Q sys <Q ref -Q margin If so, then a DC control system in the power system issues a set of input AC filter commands.
Wherein Q is sys For the reactive power exchange between the converter station and the AC system, Q ref For minimum set value of reactive power, Q margin Is a threshold value for reactive power.
Optionally, calculating the reactive power exchange quantity Q between each converter station and the alternating current system according to the system operation data corresponding to each possible direct current power level sys And respectively divide each Q sys Is carried into a switching strategy, and the reactive power exchange quantity Q between the convertor station and the alternating current system is realized sys Just meets the condition of inputting an alternating current filter, when a group of alternating current filters are input, the reactive power exchange quantity Q between a converter station and an alternating current system sys+△ And meet the condition of cutting off a group of filters, at this time Q margin The reactive power threshold value of the current operation mode.
Alternatively, Q margin The calculation formula of (2) is as follows:
in another possible implementation, determining the reactive power threshold value from the system operation data corresponding to the possible dc power level includes:
in the fixed reactive power control mode, the switching strategy of the alternating current filter is as follows:
(1) If Q sys ＞Q ref +Q cN +Q margin If so, then a DC control system in the power system issues a set of input AC filter commands.
(2) If Q sys <Q ref If so, then a DC control system in the power system issues a cut-out set of AC filter commands.
Wherein Q is cN Is the rated capacity of a single set of variable current filters.
Optionally, calculating the reactive power exchange quantity Q between each converter station and the alternating current system according to the system operation data corresponding to each possible direct current power level sys And respectively divide each Q sys Is carried into a switching strategy, and the reactive power exchange quantity Q between the convertor station and the alternating current system is realized sys Just meets the condition of inputting an alternating current filter, when a group of alternating current filters are input, the reactive power exchange quantity Q between a converter station and an alternating current system sys+△ And meet the condition of cutting off a group of filters, at this time Q margin The reactive power threshold value of the current operation mode.
Alternatively, Q margin The calculation formula of (2) is as follows:
optionally, after determining the reactive power threshold according to the system operation data corresponding to the possible dc power levels, a table of correspondence between each possible dc power level and the corresponding reactive power threshold is established, as shown in table 1, and the possible dc power level ranges from 0.1pu to 0.4 pu.
TABLE 1
| DC power level P d | Reactive power threshold value Q margin |
| 0.1pu | |
| 0.2pu | |
| 0.3pu | |
| 0.4pu |
The system operation data corresponding to each of the plurality of possible dc power levels of the dc system connected to the converter station is first determined, then for each of the possible dc power levels, the reactive power threshold value is determined according to the system operation data corresponding to the possible dc power levels, the switching reactive power threshold value of the ac filter corresponding to each of the possible dc power levels can be accurately calculated based on the switching strategy by the system operation parameters corresponding to the possible dc power levels, and frequent switching of the ac filter can be avoided by switching based on the reactive power threshold value.
In an exemplary embodiment, optionally, on the basis of the above embodiment, the system operation data includes first system operation data of a dc system, second system operation data of an ac system connected to the converter station, and third system operation data corresponding to the ac filter, and determining the reactive power threshold value according to the system operation data corresponding to the possible dc power level includes: and calculating a reactive power threshold value corresponding to the possible direct current power level according to the first system operation data, the second system operation data and the third system operation data corresponding to the possible direct current power level.
Alternatively, depending on the high voltage dc transmission characteristics, the reactive power relationships may be expressed by the following formulas:
Q sys ＝Q d -Q f
wherein Q is d For reactive power consumed by the converter, Q f Reactive power provided to the ac filter. Wherein Q is sys To positively represent the AC system to deliver reactive power, Q sys The negative phase represents that the alternating current system absorbs reactive power from the converter station.
Optionally, calculating reactive power Q consumed by the converter corresponding to each DC power level according to the first system operation data, the second system operation data and the third system operation data corresponding to the possible DC power levels d And reactive power Q provided by an AC filter f And further calculating a reactive power threshold value corresponding to the possible direct current power level.
In an exemplary embodiment, optionally, on the basis of the above embodiment, the first system operation data includes a dc voltage and a dc current, the second system operation data includes an ac bus voltage effective value and an ac voltage change rate, and determining system operation data corresponding to each of a plurality of possible dc power levels of a dc system connected to the converter station includes: for each possible direct current power level, determining the direct current voltage, the direct current and the effective value of alternating current bus voltage corresponding to the possible direct current power level according to a pre-established high-voltage direct current transmission system model, and obtaining a pre-set alternating current voltage change rate.
Alternatively, a high-voltage direct-current transmission system model can be established based on EMTDC/PSCAD simulation software, and relevant simulation parameter setting is completed according to direct-current engineering actual parameters, wherein the EMTDC/PSCAD is implemented by using extensive electromagnetic transient simulation softwareEMTDC is its simulated computational core, and PSCAD provides a graphical operation interface for EMTDC. Based on the simulation, DC running states of a plurality of possible DC power levels are simulated, and DC voltages U corresponding to the plurality of possible DC power levels are obtained d Direct current I d And an effective value U of the alternating current bus voltage ac 。
Optionally, according to the simulation result, an information database table is established, which stores possible DC power levels and DC voltages U d Direct current I d And an effective value U of the alternating current bus voltage ac For example, the information database table may be as shown in table 2, with possible dc power levels ranging from 0.1pu to 0.4 pu.
TABLE 2
| DC power level P d | DC voltage U d | Direct current I d | AC voltage U ac |
| 0.1pu | |||
| 0.2pu | |||
| 0.3pu | |||
| 0.4pu |
Alternatively, the reactive power Q consumed by the converter may be derived based on the first system operating parameter and the second system operating parameter according to the high voltage dc operating characteristics d Is calculated according to the formula:
wherein I is d Is direct current, k is the transformation ratio of a converter transformer, U ac Is the effective value of the voltage of the alternating current bus, U d Is a direct current voltage.
Optionally, according to Q/GDW146-2014, reactive compensation and configuration technical guidelines of high-voltage direct-current convertor stations, the alternating-current voltage change rate caused by switching of a group of alternating-current filters is generally not more than 1.5% -2%; most of the existing direct current engineering design specifications are designed according to the fact that the alternating current voltage change rate caused by switching of a small group of alternating current filters is not more than 1%, so that in the embodiment of the application, the preset alternating current voltage change rate is considered according to the fact that the alternating current voltage change rate is not more than 1%.
In an exemplary embodiment, based on the above embodiment, optionally, the third system operation data includes an ac filter input group number, determining system operation data corresponding to each of a plurality of possible dc power levels of a dc system connected to the converter station, including: for each possible direct current power level, inquiring a pre-established corresponding relation table according to the possible direct current power level, wherein the corresponding relation table stores a plurality of groups of corresponding relations between the possible direct current power level and the input groups of the alternating current filter; and obtaining the input group number of the alternating current filter corresponding to the possible direct current power level according to the query result.
Alternatively, the pre-established corresponding relation table may be a reactive power switching strategy table of the high-voltage direct-current transmission system, where the corresponding relation table stores the number N of input groups of the alternating-current filter corresponding to the possible direct-current power level c As shown in table 3, examples of possible dc power levels range from 0.1pu to 1.2 pu.
TABLE 3 Table 3
Alternatively, the reactive power Q provided by the ac filter may be derived based on the second system operating parameter and the third system operating parameter according to the dc-dc operating characteristic f Is calculated according to the formula:
wherein N is c Input group number for AC filter, Q cN Is the rated capacity of a single set of variable current filters.
In an exemplary embodiment, optionally, based on the above embodiment, determining the reactive power threshold according to the system operation data corresponding to the possible dc power level includes:
calculating a reactive power threshold based on a first formula; the first formula includes:
wherein Q is sys For the reactive power exchange between the converter station and the AC system, Q ref For minimum set value of reactive power, Q margin For reactive power threshold value, I d Is direct current, k is the transformation ratio of a converter transformer, U ac Is the effective value of the voltage of the alternating current bus, delta U ac For the rate of change of the alternating voltage, U d Is of direct current voltage, N c Input group number for AC filter, Q cN Is the rated capacity of a single set of variable current filters.
Optionally, the Q is calculated from system operation data corresponding to the possible dc power level sys I.e.
Optionally, Q corresponding to each possible DC power level sys Is carried into a switching strategy, and the reactive power exchange quantity Q between the convertor station and the alternating current system is realized sys Just meets the condition of inputting an alternating current filter, when a group of alternating current filters are input, the reactive power exchange quantity Q between a converter station and an alternating current system sys+Δ And meet the condition of cutting off a group of filters, at this time Q margin The reactive power threshold value of the current operation mode.
Alternatively, the reactive power threshold value may also be calculated based on a second formula comprising:
based on the formula, the reactive power threshold value of the alternating current filter under different possible direct current power levels can be accurately calculated, and frequent switching of the alternating current filter caused by adopting a fixed empirical value in the existing engineering is avoided.
In an exemplary embodiment, as shown in fig. 2, the method further comprises steps 201 to 203, optionally on the basis of the above embodiment. Wherein:
s201, acquiring the actual direct current power level of a direct current system in the working process of the converter station.
S202, determining a reactive power threshold value corresponding to the actual direct current power level according to the reactive power threshold values corresponding to the actual direct current power level and the multiple possible direct current power levels respectively.
Alternatively, reactive power threshold values corresponding to the multiple possible dc power levels may be stored in a correspondence table, and the reactive power threshold value corresponding to the actual dc power level may be determined by querying the correspondence table according to the actual dc power level.
S203, switching the alternating current filter according to the reactive power threshold value corresponding to the actual direct current power level.
It should be noted that, when the reactive power threshold value corresponding to the actual dc power level is brought into the switching strategy of the ac filter, the frequent switching phenomenon just occurs, so the actual reactive power threshold value corresponding to the actual dc power levelCan be larger than the reactive power threshold value to avoid frequent switching.
Optionally, the actual reactive power threshold value corresponding to the actual DC power levelIn the switching strategy of the AC filter, whether the current DC control system needs to send out a command for switching or cutting off a group of AC filters or not is judged, and the power system switches the AC filter according to the command.
The actual direct current power level of the direct current system in the working process of the converter station is obtained; determining a reactive power threshold value corresponding to the actual direct current power level according to the reactive power threshold values corresponding to the actual direct current power level and the multiple possible direct current power levels respectively; the alternating current filter is switched according to the reactive power threshold value corresponding to the actual direct current power level, so that frequent switching of the alternating current filter can be effectively avoided.
It should be understood that, although the steps in the flowcharts related to the embodiments described above are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts described in the above embodiments may include a plurality of steps or a plurality of stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily performed sequentially, but may be performed alternately or alternately with at least some of the other steps or stages.
As an optional implementation manner, as shown in fig. 3, the threshold value calculating method provided in the embodiment of the present application may include the following specific steps:
s301, for each possible direct current power level, determining the direct current voltage, direct current and alternating current bus voltage effective values corresponding to the possible direct current power level according to a pre-established high-voltage direct current transmission system model, and obtaining a pre-set alternating current voltage change rate.
S302, inquiring a pre-established corresponding relation table according to the possible direct current power level, wherein the corresponding relation table stores a plurality of groups of corresponding relations between the possible direct current power level and the input groups of the alternating current filter; and obtaining the input group number of the alternating current filter corresponding to the possible direct current power level according to the query result.
S303, calculating a reactive power threshold value based on a first formula; the first formula includes:
wherein Q is sys For the reactive power exchange between the converter station and the AC system, Q ref For minimum set value of reactive power, Q margin For reactive power threshold value, I d Is direct current, k is the transformation ratio of a converter transformer, U ac Is the effective value of the voltage of the alternating current bus, delta U ac For the rate of change of the alternating voltage, U d Is of direct current voltage, N c Input group number for AC filter, Q cN Is the rated capacity of a single set of variable current filters.
S304, acquiring the actual direct current power level of the direct current system in the working process of the converter station.
S305, determining a reactive power threshold value corresponding to the actual direct current power level according to the reactive power threshold values corresponding to the actual direct current power level and the multiple possible direct current power levels respectively.
S306, switching the alternating current filter according to the reactive power threshold value corresponding to the actual direct current power level.
Based on the same inventive concept, the embodiment of the application also provides a threshold value calculating device for realizing the threshold value calculation. The implementation of the solution provided by the device is similar to the implementation described in the above method, so the specific limitation in the embodiments of the one or more threshold value calculating devices provided below may refer to the limitation of the threshold value calculating method hereinabove, and will not be repeated here.
In an exemplary embodiment, as shown in fig. 4, there is provided a threshold value calculating apparatus 400, including: a first determination module 401 and a second determination module 402, wherein:
a first determining module 401 is configured to determine system operation data corresponding to a plurality of possible dc power levels of a dc system connected to the converter station, respectively.
A second determining module 402, configured to determine, for each possible dc power level, a reactive power threshold according to system operation data corresponding to the possible dc power level; the reactive power threshold value corresponding to each possible direct current power level is used for switching the alternating current filter according to the reactive power threshold value corresponding to each possible direct current power level when the power system operates normally.
In an optional embodiment of the present application, the system operation data includes first system operation data of a dc system, second system operation data of an ac system connected to the converter station, and third system operation data corresponding to the ac filter, and the second determining module 402 is specifically configured to calculate, according to the first system operation data, the second system operation data, and the third system operation data corresponding to the possible dc power level, a reactive power threshold corresponding to the possible dc power level.
In an alternative embodiment of the present application, the first system operation data includes a dc voltage and a dc current, the second system operation data includes an ac bus voltage effective value and an ac voltage change rate, and the first determining module 401 is specifically configured to determine, for each possible dc power level, the dc voltage, the dc current, and the ac bus voltage effective value corresponding to the possible dc power level according to a pre-established hvdc power transmission system model, and obtain a pre-set ac voltage change rate.
In an optional embodiment of the present application, the third system operation data includes an ac filter input group number, and the first determining module 401 is specifically configured to query, for each possible dc power level, a pre-established correspondence table according to the possible dc power level, where the correspondence table stores multiple sets of correspondence between the possible dc power level and the ac filter input group number; and obtaining the input group number of the alternating current filter corresponding to the possible direct current power level according to the query result.
In an alternative embodiment of the present application, the second determining module 402 is specifically configured to calculate the reactive power threshold value based on the first formula; the first formula includes:
wherein Q is sys For reactive power between the converter station and the ac systemRate exchange, Q ref For minimum set value of reactive power, Q margin For reactive power threshold value, I d Is direct current, k is the transformation ratio of a converter transformer, U ac Is the effective value of the voltage of the alternating current bus, delta U ac For the rate of change of the alternating voltage, U d Is of direct current voltage, N c Input group number for AC filter, Q cN Is the rated capacity of a single set of variable current filters.
In an alternative embodiment of the present application, as shown in fig. 5, the apparatus further includes a third confirmation module 403; the third confirmation module 403 is configured to obtain an actual dc power level of the dc system during operation of the converter station; determining a reactive power threshold value corresponding to the actual direct current power level according to the reactive power threshold values corresponding to the actual direct current power level and the multiple possible direct current power levels respectively; and switching the alternating current filter according to the reactive power threshold value corresponding to the actual direct current power level.
The modules in the threshold value calculation device may be implemented in whole or in part by software, hardware, or a combination thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
In one exemplary embodiment, a computer device is provided, which may be a server, the internal structure of which may be as shown in fig. 6. The computer device includes a processor, a memory, an Input/Output interface (I/O) and a communication interface. The processor, the memory and the input/output interface are connected through a system bus, and the communication interface is connected to the system bus through the input/output interface. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The database of the computer device is for storing data. The input/output interface of the computer device is used to exchange information between the processor and the external device. The communication interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a threshold value calculation method.
It will be appreciated by those skilled in the art that the structure shown in fig. 6 is merely a block diagram of some of the structures associated with the present application and is not limiting of the computer device to which the present application may be applied, and that a particular computer device may include more or fewer components than shown, or may combine certain components, or have a different arrangement of components.
In an exemplary embodiment, a computer device is provided, comprising a memory and a processor, the memory having stored therein a computer program, the processor performing the steps of the method embodiments described above when the computer program is executed.
In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored which, when executed by a processor, implements the steps of the method embodiments described above.
In an embodiment, a computer program product is provided, comprising a computer program which, when executed by a processor, implements the steps of the method embodiments described above.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, database, or other medium used in the various embodiments provided herein may include at least one of non-volatile and volatile memory. The nonvolatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, high density embedded nonvolatile Memory, resistive random access Memory (ReRAM), magnetic random access Memory (Magnetoresistive Random Access Memory, MRAM), ferroelectric Memory (Ferroelectric Random Access Memory, FRAM), phase change Memory (Phase Change Memory, PCM), graphene Memory, and the like. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory, and the like. By way of illustration, and not limitation, RAM can be in the form of a variety of forms, such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM), and the like. The databases referred to in the various embodiments provided herein may include at least one of relational databases and non-relational databases. The non-relational database may include, but is not limited to, a blockchain-based distributed database, and the like. The processors referred to in the embodiments provided herein may be general purpose processors, central processing units, graphics processors, digital signal processors, programmable logic units, quantum computing-based data processing logic units, etc., without being limited thereto.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the present application. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application shall be subject to the appended claims.
Claims (10)
1. A method for calculating a threshold value, the method comprising:
determining system operation data corresponding to a plurality of possible direct current power levels of a direct current system connected with the converter station respectively;
for each possible direct current power level, determining a reactive power threshold value according to system operation data corresponding to the possible direct current power level;
and the reactive power threshold value corresponding to each possible direct current power level is used for switching the alternating current filter according to the reactive power threshold value corresponding to each possible direct current power level by the power system when the converter station normally operates.
2. The method of claim 1, wherein the system operation data includes first system operation data of the dc system, second system operation data of an ac system connected to the converter station, and third system operation data corresponding to an ac filter, and wherein determining the reactive power threshold value based on the system operation data corresponding to the possible dc power level includes:
and calculating a reactive power threshold value corresponding to the possible direct current power level according to the first system operation data, the second system operation data and the third system operation data corresponding to the possible direct current power level.
3. The method of claim 2, wherein the first system operating data comprises a dc voltage and a dc current, the second system operating data comprises an ac bus voltage effective value and an ac voltage change rate, and the determining system operating data corresponding to each of a plurality of possible dc power levels of a dc system connected to the converter station comprises:
for each possible direct current power level, determining the direct current voltage, direct current and alternating current bus voltage effective values corresponding to the possible direct current power level according to a pre-established high-voltage direct current transmission system model, and acquiring the pre-set alternating current voltage change rate.
4. The method of claim 2, wherein the third system operation data includes an ac filter input group number, and wherein the determining system operation data corresponding to each of a plurality of possible dc power levels of a dc system connected to the converter station includes:
for each possible direct current power level, inquiring a pre-established corresponding relation table according to the possible direct current power level, wherein the corresponding relation table stores a plurality of groups of corresponding relations between the possible direct current power level and the input groups of the alternating current filter; and obtaining the input group number of the alternating current filter corresponding to the possible direct current power level according to the query result.
5. The method of claim 2, wherein determining the reactive power threshold value based on the system operation data corresponding to the possible dc power level comprises:
calculating the reactive power threshold value based on a first formula;
the first formula includes:
wherein Q is sys For the reactive power exchange between the converter station and the AC system, Q ref For minimum set value of reactive power, Q margin For reactive power threshold value, I d Is direct current, k is the transformation ratio of a converter transformer, U ac Is the effective value of the voltage of the alternating current bus, delta U ac For the rate of change of the alternating voltage, U d Is of direct current voltage, N c Input group number for AC filter, Q cN Is the rated capacity of a single set of variable current filters.
6. The method according to any one of claims 1 to 5, further comprising:
acquiring the actual direct current power level of the direct current system in the working process of the converter station;
determining the reactive power threshold value corresponding to the actual direct current power level according to the reactive power threshold values corresponding to the actual direct current power level and the multiple possible direct current power levels respectively;
and switching an alternating current filter according to the reactive power threshold value corresponding to the actual direct current power level.
7. A threshold value calculation apparatus, the apparatus comprising:
a first determining module, configured to determine system operation data corresponding to a plurality of possible dc power levels of a dc system connected to the converter station, respectively;
the second determining module is used for determining reactive power threshold values according to system operation data corresponding to the possible direct current power levels for each possible direct current power level;
and the reactive power threshold value corresponding to each possible direct current power level is used for switching the alternating current filter according to the reactive power threshold value corresponding to each possible direct current power level by the power system when the converter station normally operates.
8. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any of claims 1 to 6 when the computer program is executed.
9. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 6.
10. A computer program product comprising a computer program, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 6.
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