CN111064215B - Method and system for determining phase commutation fault of hybrid cascade direct-current transmission project - Google Patents
Method and system for determining phase commutation fault of hybrid cascade direct-current transmission project Download PDFInfo
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- CN111064215B CN111064215B CN201911266212.3A CN201911266212A CN111064215B CN 111064215 B CN111064215 B CN 111064215B CN 201911266212 A CN201911266212 A CN 201911266212A CN 111064215 B CN111064215 B CN 111064215B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
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Abstract
The invention provides a method and a system for determining a phase commutation fault of a hybrid cascade direct-current transmission project. According to the method and the system, the direct current bus voltage of the rectifying side of the power transmission project and the power transmitted by the converter station are measured, the key state quantity of the direct current power transmission project is calculated based on the measured value, when the direct current line current value in the state quantity and the direct current bus voltage value of the inverter side high-end converter station meet respective criteria at the same time, the phase commutation failure is determined, and the power speed reduction is carried out on the rectifying side of the direct current power transmission project. Compared with the prior art, the invention has the beneficial effects that: by utilizing a small amount of direct current parameter information obtained by a measuring device in the hybrid cascade direct current control protection system, through a small amount of calculation processes, the key state quantity of the hybrid cascade direct current can be obtained, the commutation failure fault of the direct current high-end inversion converter station can be further judged, and the commutation failure fault of the direct current high-end inversion converter station is controlled.
Description
Technical Field
The present invention relates to the field of direct current transmission, and more particularly, to a method and system for determining a commutation fault of a hybrid cascaded direct current transmission project.
Background
The traditional electromechanical transient simulation technology of the power system has great success in the simulation analysis work of the power system, and the operating state of the power system can be accurately reflected by both a tidal current solution and a time domain simulation curve.
However, the existing electromechanical transient simulation software of various power systems is difficult to be applied to a novel topological structure in a direct current transmission project in recent years, in particular to a direct current transmission project with a hybrid cascade structure. The hybrid cascade structure direct current transmission project generally has the following characteristics:
(1) the plurality of flexible direct current converter stations are in a parallel connection relationship, but a consistent control mode is not adopted, and a strong nonlinear coupling relationship exists among the plurality of parallel flexible direct current converter stations;
(2) in the mixed cascade structure direct current transmission project, a single conventional direct current converter station and a plurality of flexible direct current converter stations connected in parallel are in a series relation, the conventional direct current converter station is located at a high end, and the flexible direct current converter station is located at a low end. Due to the essential difference between the conventional direct current technology and the flexible direct current transmission technology, a strong nonlinear coupling relation exists between the high-end converter station and the low-end converter station;
(3) the high-end converter station and the low-end converter station are usually connected to different positions of an alternating current power grid, and the nonlinear coupling relation between the high-end converter station and the low-end converter station can be amplified by disturbance from the alternating current power grid.
For the reasons, the existing electromechanical transient simulation software of various power systems is difficult to acquire the key state quantity in the DC transmission project with the hybrid cascade structure, and the hybrid cascade DC can be precisely modeled from the level of elements only by an electromagnetic transient simulation tool with a large calculation quantity, so that the information of the internal state quantity of the DC is finally read. The process has extremely high requirements on the hardware capability of a computer for simulation, and measurement information obtained by a measurement device in the hybrid cascade direct current control protection system cannot be utilized. Under the condition of lacking of the internal state quantity of the hybrid cascade direct current, the commutation failure fault of the direct current high-end inversion converter station is difficult to judge, the commutation failure fault of the direct current high-end inversion converter station cannot be controlled, and research and analysis on the hybrid cascade direct current access to a large power grid are greatly hindered.
Disclosure of Invention
In order to solve the technical problems that the state quantity obtained by a measuring device in a hybrid cascade direct current control protection system cannot be utilized in the prior art, and the commutation failure fault of a direct current high-end inverter station cannot be judged very easily and the commutation failure fault of a direct current transmission side high-end inverter station cannot be controlled in the absence of the state quantity in a transmission project, the invention provides a method for determining the commutation failure of the hybrid cascade direct current transmission project, wherein the inverter side of the hybrid cascade direct current transmission project comprises 1 conventional direct current converter station and a plurality of flexible direct current converter stations, the flexible direct current converter stations are connected in parallel, the conventional direct current converter station is connected with the flexible direct current converter stations in series, the conventional direct current converter station is positioned at the high end, and the flexible direct current converter stations are positioned at the low end, the method comprises the following steps:
measuring the voltage of a direct-current bus at a rectification side of the hybrid cascade direct-current transmission project and the power transmitted by a converter station at the rectification side;
calculating the current value of a direct current line according to the power transmitted by the rectifying side and the voltage value of a direct current bus of the rectifying side;
calculating the direct-current bus voltage value of the high-end converter station at the inversion side and the power injected into an alternating-current system according to the power transmitted at the rectification side, the direct-current bus voltage value at the rectification side and the preset direct-current line unipolar loop resistance;
calculating the direct current bus voltage value of a single inversion side low-end converter station according to the direct current bus voltage value of the inversion side high-end converter station;
when the current value of the direct current line meets a preset current criterion and the voltage value of a direct current bus of the single inversion side low-end converter station meets a voltage criterion, determining that a phase change failure fault occurs on the inversion side of the hybrid cascade direct current transmission project;
and when the inversion side of the hybrid cascade direct current transmission project has a commutation failure fault, performing power quick reduction on the rectification side of the direct current transmission project, wherein the power quick reduction is the power injected into an alternating current system by the high-end converter station of the inversion side.
Further, the direct current line current value is calculated according to the power transmitted by the rectifying side and the direct current bus voltage value of the rectifying side, and the calculation formula is as follows:
in the formula I DC Is the current value, P, of the DC line of the mixed cascade DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The direct current bus voltage value at the rectification side of the power transmission project.
Further, the dc bus voltage value of the high-end converter station at the inverter side and the power injected into the ac system are calculated according to the power transmitted at the rectifier side, the dc bus voltage value at the rectifier side, and the preset dc line unipolar loop resistance, and the calculation formula is as follows:
in the formula of U Hinv Is the DC bus voltage value P of the inversion side high-end converter station of the mixed cascade DC transmission project Hinv Is the power P injected into the AC system by the high-end converter station at the inversion side of the DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The direct current bus voltage value at the rectification side of the power transmission project, and R is a preset single-pole loop resistor of a direct current line.
Further, the dc bus voltage value of a single inverter-side low-end converter station is calculated according to the dc bus voltage value of the inverter-side high-end converter station, and the calculation formula is as follows:
in the formula of U Linv Is the DC bus voltage value U of the single inversion side low-end converter station in the DC transmission project Hinv The voltage value of the direct current bus of the inversion side high-end converter station of the hybrid cascade direct current transmission project is shown.
Further, when the current value of the dc line meets a preset current criterion and the voltage value of the dc bus of the single inverter side low-end converter station meets a voltage criterion, it is determined that a phase commutation failure fault occurs on the inverter side of the hybrid cascade dc transmission project, where the calculation formulas of the current criterion and the voltage criterion are respectively:
U Linv ≤U 0
I DC ≥I 0
in the formula of U Linv Is the DC bus voltage value, I, of the single inversion side low-end converter station in the DC transmission project DC Is the current value of the DC line of the DC transmission project, U 0 Is a preset direct current bus voltage threshold value, I, of a single inversion side low-end converter station 0 Is a preset dc line current threshold.
According to another aspect of the present invention, a system for determining a commutation fault of a hybrid cascaded dc power transmission project is provided, where an inverter side of the hybrid cascaded dc power transmission project includes 1 conventional dc converter station and a plurality of flexible dc converter stations, the plurality of flexible dc converter stations are connected in parallel, the conventional dc converter station and the plurality of flexible dc converter stations are connected in series, the conventional dc converter station is located at a high end, and the flexible dc converter station is located at a low end, the system includes:
the data acquisition unit is used for measuring the voltage of a direct-current bus at the rectification side and the power transmitted by a converter station at the rectification side in the hybrid cascade direct-current transmission project;
the first calculation unit is used for calculating the direct current line current value according to the power transmitted by the rectification side and the direct current bus voltage value of the rectification side;
the second calculation unit is used for calculating the direct current bus voltage value of the high-end converter station at the inversion side and the power injected into the alternating current system according to the power transmitted at the rectification side, the direct current bus voltage value at the rectification side and the preset unipolar loop resistance of the direct current circuit;
the third calculating unit is used for calculating the direct current bus voltage value of a single inversion side low-end converter station according to the direct current bus voltage value of the inversion side high-end converter station;
the fault determining unit is used for determining that a commutation failure fault occurs on the inversion side of the hybrid cascade direct-current transmission project when the current value of the direct-current line meets a preset current criterion and the voltage value of the direct-current bus of the single inversion side low-end converter station meets a voltage criterion;
and the output control unit is used for performing power quick reduction on the rectification side of the direct current transmission project when a commutation failure fault occurs on the inversion side of the hybrid cascade direct current transmission project, wherein the power quick reduction is the power injected into the alternating current system by the high-end converter station on the inversion side.
Further, the first calculating unit calculates a dc line current value according to the power transmitted by the rectifying side and a dc bus voltage value of the rectifying side, and the calculation formula is as follows:
in the formula I DC Is the current value, P, of the DC line of the mixed cascade DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The voltage value of the direct current bus at the rectification side in the power transmission project.
Further, the second calculating unit calculates a dc bus voltage value of the high-end converter station at the inverter side and a power injected into the ac system according to the power transmitted at the rectifier side, the dc bus voltage value at the rectifier side, and a preset dc line unipolar loop resistance, and the calculation formula is as follows:
in the formula of U Hinv Is the DC bus voltage value P of the inversion side high-end converter station of the mixed cascade DC transmission project Hinv Is the power P injected into the AC system by the high-end converter station at the inversion side of the DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The direct current bus voltage value at the rectification side of the power transmission project, and R is a preset single-pole loop resistor of a direct current line.
Further, the third calculating unit calculates a dc bus voltage value of a single inverter-side low-end converter station according to the dc bus voltage value of the inverter-side high-end converter station, and the calculation formula is as follows:
in the formula of U Linv Is the direct current bus voltage value, U, of the single inversion side low-end converter station in the direct current transmission project Hinv The voltage value of the direct current bus of the inversion side high-end converter station of the hybrid cascade direct current transmission project is shown.
Further, when the current value of the dc line meets a preset current criterion and the voltage value of the dc bus of the single inverter side low-end converter station meets a voltage criterion, the fault determining unit determines that a phase commutation failure fault occurs on the inverter side of the hybrid cascade dc transmission project, where the current criterion and the voltage criterion have respective calculation formulas:
U Linv ≤U 0
I DC ≥I 0
in the formula of U Linv Is the DC bus voltage value, I, of the single inversion side low-end converter station in the DC transmission project DC Is the current value of the DC line of the DC transmission project, U 0 Of a single pre-arranged inverter-side low-end converter stationDC bus voltage threshold, I 0 Is a preset dc line current threshold.
According to the method and the system for determining the phase change fault of the hybrid cascade direct current transmission project, provided by the technical scheme of the invention, the direct current bus voltage at the rectification side of the transmission project and the power transmitted by the converter stations are measured, the key state quantity of the direct current transmission project is calculated based on the measured value, the key state quantity comprises the direct current line current value, the direct current bus voltage value of the high-end converter station at the inversion side and the power injected into an alternating current system, and the direct current bus voltage value of the low-end converter station at the single inversion side. Compared with the prior art, the invention has the beneficial effects that: by utilizing a small amount of direct current parameter information obtained by a measuring device in the hybrid cascade direct current control protection system, through a small amount of calculation processes, the key state quantity of the hybrid cascade direct current can be obtained, the commutation failure fault of the direct current high-end inversion converter station can be further judged, and the commutation failure fault of the direct current high-end inversion converter station is controlled.
Drawings
Exemplary embodiments of the invention may be more completely understood in consideration of the following drawings:
fig. 1 is a flow chart of a method for determining a commutation fault of a hybrid cascaded direct current transmission project according to a preferred embodiment of the present invention;
fig. 2 is a schematic structural diagram of a system for determining a commutation fault of a hybrid cascaded direct current transmission project according to a preferred embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flowchart of a method for determining a commutation fault of a hybrid cascaded direct current transmission project according to a preferred embodiment of the present invention. As shown in fig. 1, a method 100 for determining a commutation fault in a hybrid cascaded dc power transmission project according to the preferred embodiment starts with step 101.
In step 101, measuring the voltage of the direct current bus at the rectification side and the power transmitted by the converter station at the rectification side of the hybrid cascade direct current transmission project. The inversion side of the hybrid cascade direct current transmission project comprises 1 conventional direct current converter station and a plurality of flexible direct current converter stations, the flexible direct current converter stations are connected in parallel, the conventional direct current converter stations are connected with the flexible direct current converter stations in series, the conventional direct current converter stations are located at the high end, and the flexible direct current converter stations are located at the low end. The control protection system of the hybrid cascade direct current transmission project is internally provided with the measuring device, and the related parameters of the rectifier side converter station of the transmission project can be obtained through the device, so that the control protection system is very convenient.
In step 102, a direct current line current value is calculated according to the power transmitted by the rectifying side and the direct current bus voltage value of the rectifying side.
In step 103, the dc bus voltage value of the high-end converter station on the inverter side and the power injected into the ac system are calculated according to the power transmitted on the rectifier side, the dc bus voltage value on the rectifier side and the preset unipolar loop resistance of the dc line.
In step 104, the dc bus voltage value of the single inverter-side low-end converter station is calculated according to the dc bus voltage value of the inverter-side high-end converter station.
In step 105, when the current value of the direct current line meets a preset current criterion and the voltage value of the direct current bus of the single inversion side low-end converter station meets a voltage criterion, determining that a phase-change failure fault occurs on the inversion side of the hybrid cascade direct current transmission project;
in step 106, when a phase commutation failure fault occurs on the inversion side of the hybrid cascade direct current transmission project, performing power fast-reduction on the rectification side of the direct current transmission project, wherein the power fast-reduction is the power injected into the alternating current system by the high-end converter station on the inversion side.
Preferably, the dc line current value is calculated according to the power transmitted by the rectifying side and the dc bus voltage value of the rectifying side, and the calculation formula is as follows:
in the formula I DC Is the current value, P, of the DC line of the mixed cascade DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The direct current bus voltage value at the rectification side of the power transmission project.
Preferably, the dc bus voltage value of the high-end converter station on the inverter side and the power injected into the ac system are calculated according to the power transmitted on the rectifier side, the dc bus voltage value on the rectifier side, and a preset dc line unipolar loop resistance, and the calculation formula is as follows:
in the formula of U Hinv Is the DC bus voltage value P of the inversion side high-end converter station of the mixed cascade DC transmission project Hinv Is the power P injected into the AC system by the high-end converter station at the inversion side of the DC transmission project rec Is transmitting electricityPower, U, of engineering rectification side transmission rec The direct current bus voltage value at the rectification side of the power transmission project, and R is a preset single-pole loop resistor of a direct current line.
Preferably, the calculating formula of the dc bus voltage value of the single inverter-side low-end converter station according to the dc bus voltage value of the inverter-side high-end converter station is:
in the formula of U Linv Is the DC bus voltage value U of the single inversion side low-end converter station in the DC transmission project Hinv The voltage value of the direct current bus of the inversion side high-end converter station of the hybrid cascade direct current transmission project is shown.
Preferably, when the current value of the dc line meets a preset current criterion and the voltage value of the dc bus of the single inverter side low-end converter station meets a voltage criterion, it is determined that a phase commutation failure fault occurs on the inverter side of the hybrid cascade dc transmission project, where the calculation formulas of the current criterion and the voltage criterion are respectively:
U Linv ≤U 0
I DC ≥I 0
in the formula of U Linv Is the direct current bus voltage value, I, of the single inversion side low-end converter station in the direct current transmission project DC Is the current value of the DC line of the DC transmission project, U 0 Is a preset direct current bus voltage threshold value, I, of a single inversion side low-end converter station 0 Is a preset dc line current threshold.
Fig. 2 is a schematic structural diagram of a system for determining a commutation fault of a hybrid cascaded direct current transmission project according to a preferred embodiment of the present invention. As shown in fig. 1, a system 200 for determining a commutation fault in a hybrid cascaded dc power transmission project according to the preferred embodiment includes:
and the data acquisition unit 201 is used for measuring the voltage of the direct-current bus at the rectification side and the power transmitted by the converter station at the rectification side in the hybrid cascade direct-current transmission project. The inversion side of the hybrid cascade direct current transmission project comprises 1 conventional direct current converter station and a plurality of flexible direct current converter stations, the flexible direct current converter stations are connected in parallel, the conventional direct current converter stations and the flexible direct current converter stations are connected in series, the conventional direct current converter stations are located at the high end, and the flexible direct current converter stations are located at the low end.
A first calculating unit 202, configured to calculate a dc line current value according to the power transmitted by the rectifying side and a rectifying side dc bus voltage value;
a second calculating unit 203, configured to calculate a dc bus voltage value of the high-end inverter station on the inverter side and power injected into the ac system according to the power transmitted on the rectifier side, the dc bus voltage value on the rectifier side, and the preset unipolar loop resistance of the dc line;
a third calculating unit 204, configured to calculate a dc bus voltage value of a single inverter-side low-end converter station according to the dc bus voltage value of the inverter-side high-end converter station;
a fault determining unit 205, configured to determine that a phase change failure fault occurs on the inverter side of the hybrid cascade dc power transmission project when the dc line current value meets a preset current criterion and the dc bus voltage value of the single inverter side low-end converter station meets a voltage criterion;
and an output control unit 206, configured to, when a phase commutation failure fault occurs on the inversion side of the hybrid cascaded dc power transmission project, perform power fast-reduction on the rectification side of the dc power transmission project, where the power fast-reduction is power injected into an ac system by the high-end converter station on the inversion side.
Preferably, the first calculating unit 202 calculates a dc line current value according to the power transmitted by the rectifying side and a dc bus voltage value of the rectifying side, and the calculation formula is:
in the formula I DC Is the current value of the DC line of the mixed cascade DC transmission project，P rec Is the power transmitted by the rectifying side of the power transmission project, U rec The voltage value of the direct current bus at the rectification side in the power transmission project.
Preferably, the second calculating unit 203 calculates the dc bus voltage value of the high-end converter station on the inverter side and the power injected into the ac system according to the power transmitted on the rectifier side, the dc bus voltage value on the rectifier side, and the preset unipolar loop resistance of the dc line, and the calculation formula is as follows:
in the formula of U Hinv Is the DC bus voltage value P of the inversion side high-end converter station of the mixed cascade DC transmission engineering Hinv Is the power P injected into the AC system by the high-end converter station at the inversion side of the DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The direct current bus voltage value at the rectification side of the power transmission project, and R is a preset direct current line single-pole loop resistor.
Preferably, the third calculating unit 204 calculates a dc bus voltage value of a single inverter-side low-end converter station according to the dc bus voltage value of the inverter-side high-end converter station, and the calculation formula is as follows:
in the formula of U Linv Is the DC bus voltage value U of the single inversion side low-end converter station in the DC transmission project Hinv The voltage value of the direct current bus of the inversion side high-end converter station of the hybrid cascade direct current transmission project is shown.
Preferably, when the current value of the dc line meets a preset current criterion and the voltage value of the dc bus of the single inverter side low-end converter station meets a voltage criterion, the fault determining unit 205 determines that a phase commutation failure fault occurs on the inverter side of the hybrid cascade dc power transmission project, where the current criterion and the voltage criterion have the following calculation formulas:
U Linv ≤U 0
I DC ≥I 0
in the formula of U Linv Is the DC bus voltage value, I, of the single inversion side low-end converter station in the DC transmission project DC Is the current value of the DC line of the DC transmission project, U 0 Is a preset direct current bus voltage threshold value, I, of a single inversion side low-end converter station 0 Is a preset dc line current threshold.
The steps of judging the commutation failure fault of the direct current transmission line and implementing control by the system for determining the commutation fault of the hybrid cascade direct current transmission project are the same as the steps of the method for determining the commutation fault of the hybrid cascade direct current transmission project, the technical effects are the same, and the description is omitted here.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the ones disclosed above are equally possible within the scope of these appended patent claims, as these are known to those skilled in the art.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A method for determining a commutation fault of a hybrid cascade direct current transmission project, wherein an inversion side of the hybrid cascade direct current transmission project comprises 1 conventional direct current converter station and a plurality of flexible direct current converter stations, the flexible direct current converter stations are connected in parallel, the conventional direct current converter station and the flexible direct current converter stations are connected in series, the conventional direct current converter station is located at a high end, and the flexible direct current converter station is located at a low end, and the method comprises the following steps:
measuring the voltage of a direct-current bus at a rectification side of the hybrid cascade direct-current transmission project and the power transmitted by a converter station at the rectification side;
calculating the current value of a direct current line according to the power transmitted by the rectifying side and the voltage value of a direct current bus of the rectifying side;
calculating the voltage value of the direct current bus of the high-end converter station at the inversion side and the power injected into the alternating current system according to the power transmitted at the rectification side, the voltage value of the direct current bus at the rectification side and the preset unipolar loop resistance of the direct current circuit;
calculating the direct-current bus voltage value of a single inversion side low-end converter station according to the direct-current bus voltage value of the inversion side high-end converter station;
when the current value of the direct current line meets a preset current criterion and the voltage value of a direct current bus of the single inversion side low-end converter station meets a voltage criterion, determining that a phase change failure fault occurs on the inversion side of the hybrid cascade direct current transmission project;
and when the inversion side of the hybrid cascade direct current transmission project has a commutation failure fault, performing power quick reduction on the rectification side of the direct current transmission project, wherein the power quick reduction is the power injected into an alternating current system by the high-end converter station of the inversion side.
2. The method of claim 1, wherein the calculating of the dc link current value based on the power transmitted at the rectifying side and the rectifying side dc bus voltage value is performed by the formula:
in the formula I DC Is the current value, P, of the DC line of the mixed cascade DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The voltage value of the direct current bus at the rectification side in the power transmission project.
3. The method according to claim 1, wherein the dc bus voltage value of the high-end converter station at the inverting side and the power injected into the ac system are calculated according to the power transmitted at the rectifying side, the dc bus voltage value at the rectifying side and the preset unipolar loop resistance of the dc line, and the calculation formula is as follows:
in the formula of U Hinv Is the DC bus voltage value P of the inversion side high-end converter station of the mixed cascade DC transmission project Hinv Is the power P injected into the AC system by the high-end converter station at the inversion side of the DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The direct current bus voltage value at the rectification side of the power transmission project, and R is a preset direct current line single-pole loop resistor.
4. The method according to claim 1, wherein the calculating the dc bus voltage value of the single inverter-side low-end converter station according to the dc bus voltage value of the inverter-side high-end converter station comprises:
in the formula of U Linv Is the DC bus voltage value U of the single inversion side low-end converter station in the DC transmission project Hinv The voltage value of the direct current bus of the inversion side high-end converter station of the hybrid cascade direct current transmission project is shown.
5. The method according to claim 1, wherein when the value of the direct current line current meets a preset current criterion and the value of the direct current bus voltage of the single inversion side low-end converter station meets a voltage criterion, it is determined that a phase-change failure fault occurs on an inversion side of the hybrid cascade connection direct current transmission engineering, wherein the current criterion and the voltage criterion are respectively calculated according to the following formulas:
U Linv ≤U 0
I DC ≥I 0
in the formula of U Linv Is the direct current bus voltage value, I, of the single inversion side low-end converter station in the direct current transmission project DC Is the current value of the DC line of the DC transmission project, U 0 Is a preset direct current bus voltage threshold value, I, of a single inversion side low-end converter station 0 Is a preset dc line current threshold.
6. The utility model provides a system for confirm mixed cascade direct current transmission engineering commutation fault, mixed cascade direct current transmission engineering's contravariant side includes 1 conventional direct current converter station and a plurality of flexible direct current converter station, a plurality of flexible direct current converter station parallel connection, conventional direct current converter station and a plurality of flexible direct current converter station are established ties, and conventional direct current converter station is located the high-end, and flexible direct current converter station is located the low-end, its characterized in that, the system includes:
the data acquisition unit is used for measuring the voltage of a direct-current bus at the rectification side and the power transmitted by a converter station at the rectification side in the hybrid cascade direct-current transmission project;
the first calculating unit is used for calculating the current value of a direct current line according to the power transmitted by the rectifying side and the voltage value of a direct current bus at the rectifying side;
the second calculation unit is used for calculating the direct current bus voltage value of the high-end converter station at the inversion side and the power injected into the alternating current system according to the power transmitted at the rectification side, the direct current bus voltage value at the rectification side and the preset unipolar loop resistance of the direct current circuit;
the third calculating unit is used for calculating the direct current bus voltage value of a single inversion side low-end converter station according to the direct current bus voltage value of the inversion side high-end converter station;
the fault determining unit is used for determining that a commutation failure fault occurs on the inversion side of the hybrid cascade direct-current transmission project when the current value of the direct-current line meets a preset current criterion and the voltage value of the direct-current bus of the single inversion side low-end converter station meets a voltage criterion;
and the output control unit is used for performing power quick reduction on the rectification side of the direct current transmission project when a commutation failure fault occurs on the inversion side of the hybrid cascade direct current transmission project, wherein the power quick reduction is the power injected into the alternating current system by the high-end converter station on the inversion side.
7. The system of claim 6, wherein the first computing unit computes the dc link current value according to the power transmitted by the rectifying side and the rectifying side dc bus voltage value, and the computation formula is:
in the formula I DC Is the current value, P, of the DC line of the mixed cascade DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The direct current bus voltage value at the rectification side of the power transmission project.
8. The system according to claim 6, wherein the second calculating unit calculates the dc bus voltage value of the high-end converter station at the inverting side and the power injected into the ac system according to the power transmitted at the rectifying side, the dc bus voltage value at the rectifying side and the preset unipolar loop resistance of the dc line, and the calculation formula is as follows:
in the formula of U Hinv Is the DC bus voltage value P of the inversion side high-end converter station of the mixed cascade DC transmission engineering Hinv Is the power P injected into the AC system by the high-end converter station at the inversion side of the DC transmission project rec Is the power transmitted by the rectifying side of the power transmission project, U rec The direct current bus voltage value at the rectification side of the power transmission project, and R is a preset single-pole loop resistor of a direct current line.
9. The system according to claim 6, wherein the third calculating unit calculates the DC bus voltage value of a single inverter-side low-end converter station according to the DC bus voltage value of the inverter-side high-end converter station, and the calculation formula is:
in the formula of U Linv Is the DC bus voltage value U of the single inversion side low-end converter station in the DC transmission project Hinv The voltage value of the direct current bus of the inversion side high-end converter station of the hybrid cascade direct current transmission project is shown.
10. The system according to claim 6, wherein the fault determining unit determines that a phase-change failure fault occurs on the inversion side of the hybrid cascaded direct current transmission project when the direct current line current value meets a preset current criterion and the direct current bus voltage value of the single inversion side low-end converter station meets a voltage criterion, wherein the current criterion and the voltage criterion are respectively calculated according to the following formulas:
U Linv ≤U 0
I DC ≥I 0
in the formula of U Linv Is the DC bus voltage value, I, of the single inversion side low-end converter station in the DC transmission project DC Is the current value of the DC line of the DC transmission project, U 0 Is a preset direct current bus voltage threshold value, I, of a single inversion side low-end converter station 0 Is a preset dc line current threshold.
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| CN103500261A (en) * | 2013-10-22 | 2014-01-08 | 国家电网公司 | Method for fault simulation of direct current transmission system |
| CN110417042A (en) * | 2019-08-16 | 2019-11-05 | 国网山东省电力公司电力科学研究院 | A kind of method of controlling security and system inhibiting the continuous commutation failure of direct current system |
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| CN103500261A (en) * | 2013-10-22 | 2014-01-08 | 国家电网公司 | Method for fault simulation of direct current transmission system |
| CN110417042A (en) * | 2019-08-16 | 2019-11-05 | 国网山东省电力公司电力科学研究院 | A kind of method of controlling security and system inhibiting the continuous commutation failure of direct current system |
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