CN115189335A - Method and device for determining severity of direct current fault - Google Patents
Method and device for determining severity of direct current fault Download PDFInfo
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- CN115189335A CN115189335A CN202210705245.9A CN202210705245A CN115189335A CN 115189335 A CN115189335 A CN 115189335A CN 202210705245 A CN202210705245 A CN 202210705245A CN 115189335 A CN115189335 A CN 115189335A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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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
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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
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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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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The application provides a method and a device for determining the severity of a direct current fault, which relate to the field of power equipment maintenance and comprise the following steps: extracting corresponding low-frequency band fault characteristic signals according to transient data of the alternating current and direct current power transmission system; determining equivalent electromagnetic power and an equivalent power angle of the alternating-current and direct-current power transmission system in a fault period according to the low-frequency band fault characteristic signal; and determining the severity of the direct current fault according to the equivalent electromagnetic power and the equivalent power angle. The method and the device can comprehensively consider the characteristics of the power angle in the alternating current-direct current power transmission system, judge the severity of different direct current faults and visually compare the impact influence of the different direct current faults on the power grid.
Description
Technical Field
The application relates to the field of power equipment maintenance, in particular to a method and a device for determining the severity of a direct-current fault.
Background
The high-voltage direct-current transmission has obvious advantages in the aspects of long-distance and large-capacity transmission, is widely applied to scenes such as clean energy delivery, trans-regional interconnection and the like, and plays an important role in the aspect of resource optimization and utilization. At present, ultrahigh voltage direct current projects are more, and direct current transmission lines are long in distance and complex in terrain environment along the lines and are easily affected by natural factors such as lightning stroke and windage yaw, so that direct current line faults are caused, and converter valves are locked. The converter valve is limited by the conditions of an external circuit, and when the converter valve is subjected to disturbance conditions such as failure of a trigger circuit at a rectification side and alternating voltage at an inversion side, phase change failure is easy to occur; such abnormal operating conditions provide a great challenge to the safe and stable operation of the power transmission system.
To improve the dc supply reliability, the dc line is typically restarted after a fault. After a first commutation failure of the converter valves, it is usually allowed to try commutation again, and only if the failure occurs after a certain number of attempts. However, under the current 'strong weak alternating current' power grid structure, the impact of the direct current restart strategy on the transmitting and receiving end alternating current systems may exceed the bearing capacity of the direct current restart strategy, so that the alternating current systems are unstable, and a cascading failure is caused; the transient overvoltage limit may be exceeded by a latch-up after a dc commutation failure. Therefore, before the lockout happens, the severity of different direct current faults is judged, and a reasonable fault post-control protection strategy is selected according to the severity, so that the impact on the system is reduced, and the stability of the system is improved.
In the prior art, the unbalanced energy difference is obtained by calculating the unbalanced energy impact of the system caused by unbalanced direct-current bipolar active power after different direct-current faults; integrating bipolar active power simulation curves in different fault periods, calculating generated system short-time backspacing energy, and solving the difference of the system short-time backspacing energy; and calculating the energy difference of the system during the fault by comprehensively considering the amount of system energy unbalance caused during the fault and the short-time rollback energy of the system, and further formulating a control protection strategy after the fault. However, the prior art has the following disadvantages: firstly, the influence degrees of different faults on the system are difficult to obtain visual comparison; second, when the system is weak and the dc power is large, it is difficult to determine the severity of the fault condition because a large amount of reactive power is absorbed during the successful dc restart.
Disclosure of Invention
Aiming at the problems in the prior art, the application provides a method and a device for determining the severity of a direct current fault, which can comprehensively consider the characteristics of a power angle in an alternating current-direct current power transmission system, judge the severity of different direct current faults and visually compare the impact influence of different direct current faults on a power grid.
In order to solve the technical problem, the application provides the following technical scheme:
in a first aspect, the present application provides a method for determining a severity of a dc fault, including:
extracting corresponding low-frequency band fault characteristic signals according to transient data of the alternating current and direct current power transmission system; the transient data includes: the generator end alternating voltage, the generator end alternating current and the rotor angle of each generator;
determining equivalent electromagnetic power and an equivalent power angle of the alternating-current and direct-current power transmission system in a fault period according to the low-frequency band fault characteristic signal;
and determining the severity of the direct current fault according to the equivalent electromagnetic power and the equivalent power angle.
Further, the method for determining the severity of the dc fault further includes:
acquiring corresponding transient data according to the running mode of the alternating current and direct current power transmission system; the operation mode comprises a full-starting mode and an overhauling mode of the generator set.
Further, determining the severity of the dc fault according to the equivalent electromagnetic power and the equivalent power angle, comprising:
determining system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts each restarting strategy to carry out system recovery after a fault according to the equivalent electromagnetic power and the equivalent power angle;
and determining the severity of the occurrence of the direct current fault according to the kinetic energy of the system.
Further, determining the severity of the dc fault according to the equivalent electromagnetic power and the equivalent power angle includes:
generating a relation curve graph of the equivalent electromagnetic power and the equivalent power angle;
determining the severity from the relationship graph.
Further, the low-band fault signature includes: voltage fault characteristic signals, current fault characteristic signals and rotor angle fault characteristic signals; the determining the equivalent electromagnetic power and the equivalent power angle of the alternating current-direct current transmission system in the fault time period according to the low-frequency band fault characteristic signal comprises the following steps:
determining the active power of each generator in the system fault time period according to the voltage fault characteristic signal and the current fault characteristic signal of each generator;
determining equivalent electromagnetic power of the alternating current-direct current power transmission system in a fault period according to the inertia time constant of each generator and the active power of each generator in the system fault period;
and determining the equivalent power angle of the alternating current-direct current power transmission system in the fault time period according to the inertia time constant of each generator and the rotor angle fault characteristic signal.
Further, when it is determined that the ac/dc power transmission system adopts different restart strategies for system recovery after a fault according to the equivalent electromagnetic power and the equivalent power angle, the system kinetic energy generated by the ac/dc power transmission system includes:
determining an electromagnetic power fault value according to the equivalent electromagnetic power;
and determining the kinetic energy of the system according to the mechanical input power of the prime mover, the electromagnetic power fault value and the rotor angle of each generator.
Further, the determining the severity of the dc fault according to the kinetic energy of the system includes:
sorting the magnitude of system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts different restarting strategies to carry out fault recovery after a fault;
and determining the severity of the fault according to the sequencing result, and generating a corresponding strategy set.
In a second aspect, the present application provides an apparatus for determining a severity of a dc fault, including:
the low-frequency characteristic extraction unit is used for extracting corresponding low-frequency band fault characteristic signals according to transient data of the alternating current-direct current power transmission system; the transient data includes: the generator end alternating voltage, the generator end alternating current and the rotor angle of each generator;
the power angle determining unit is used for determining equivalent electromagnetic power and an equivalent power angle of the alternating current-direct current power transmission system in a fault period according to the low-frequency band fault characteristic signal;
and the severity determining unit is used for determining the severity of the occurrence of the direct current fault according to the equivalent electromagnetic power and the equivalent power angle.
Further, the apparatus for determining the severity of a dc fault further includes:
the transient data acquisition unit is used for acquiring corresponding transient data according to the running mode of the alternating current-direct current power transmission system; the operation mode comprises a full-starting mode and an overhauling mode of the generator set.
Further, the severity determination unit includes:
the system kinetic energy determining module is used for determining system kinetic energy generated by the alternating current-direct current power transmission system when the alternating current-direct current power transmission system adopts each restarting strategy to carry out system recovery after a fault according to the equivalent electromagnetic power and the equivalent power angle;
and the severity determining module is used for determining the severity of the occurrence of the direct current fault according to the kinetic energy of the system.
Further, the severity determination unit includes:
the relation curve generating module is used for generating a relation curve graph of the equivalent electromagnetic power and the equivalent power angle;
and the severity judging module is used for determining the severity according to the relation curve graph.
Further, the fault signature includes: voltage fault characteristic signals, current fault characteristic signals and rotor angle fault characteristic signals; the power angle determining unit includes:
the active power determining module is used for determining the active power of each generator in the system fault period according to the voltage fault characteristic signal and the current fault characteristic signal of each generator;
the electromagnetic power determination module is used for determining equivalent electromagnetic power of the alternating current-direct current power transmission system in a fault period according to the inertia time constant of each generator and the active power of each generator in the system fault period;
and the power angle determining module is used for determining the equivalent power angle of the alternating-current and direct-current power transmission system in the fault time period according to the inertia time constant of each generator and the rotor angle fault characteristic signal.
Further, the system kinetic energy determination module includes:
the fault value determining module is used for determining an electromagnetic power fault value according to the equivalent electromagnetic power;
and the system kinetic energy determining module is used for determining the system kinetic energy according to the mechanical input power of the prime mover, the electromagnetic power fault value and the rotor angle of each generator.
Further, the severity determination module includes:
the kinetic energy sequencing module is used for sequencing the magnitude of system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts different restarting strategies to carry out fault recovery after a fault;
and the strategy set module is used for determining the severity of the fault according to the sequencing result and generating a corresponding strategy set.
In a third aspect, the present application provides an electronic device including a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to implement the steps of the method for determining the severity of the dc fault.
In a fourth aspect, the present application provides a computer-readable storage medium having stored thereon a computer program which, when being executed by a processor, carries out the steps of the method for determining the severity of a dc fault.
In a fifth aspect, the present application provides a computer program product comprising computer program/instructions which, when executed by a processor, perform the steps of the method for determining the severity of a dc fault.
Aiming at the problems in the prior art, the method and the device for determining the severity of the direct current fault can acquire corresponding transient data according to the operation mode of the alternating current-direct current power transmission system, extract corresponding fault characteristic signals, further calculate the power and the power angle of the system, and finally determine the severity of the direct current fault according to the power and the power angle. Furthermore, a relation curve graph can be generated according to power and a power angle, the severity of the direct current fault can be judged through the relation curve graph, the kinetic energy of the alternating current-direct current power transmission system can be calculated according to the power and the power angle, and the severity of the direct current fault can be sequenced according to the kinetic energy, so that impact influences on the system caused by various direct current faults and different restarting strategies can be compared, the calculation process is clear, complex operation is not needed, a basis is provided for subsequently formulating a reasonable control protection strategy, and the operation stability of the system is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a method for determining the severity of a dc fault according to an embodiment of the present application;
FIG. 2 is a flowchart illustrating the determination of electromagnetic power and power angle during a fault phase according to an embodiment of the present disclosure;
FIG. 3 is a flow chart of determining kinetic energy of a system in an embodiment of the present application;
FIG. 4 is a flowchart of determining the severity of an occurrence of a DC fault in an embodiment of the present application;
FIG. 5 is a second flowchart of a method for determining the severity of a DC fault according to an embodiment of the present application;
fig. 6 is one of the configuration diagrams of a determination apparatus of the severity of a direct current fault in the embodiment of the present application;
fig. 7 is a structural diagram of a power angle determining unit in the embodiment of the present application;
FIG. 8 is a block diagram of a system kinetic energy determination module in an embodiment of the present application;
FIG. 9 is a block diagram of a severity determination module in an embodiment of the present application;
FIG. 10 is a block diagram of a severity determination module in an embodiment of the present application;
FIG. 11 is a block diagram of a severity determination unit in an embodiment of the present application;
FIG. 12 is a schematic diagram of a power angle curve in an embodiment of the present application;
FIG. 13 is a schematic diagram of an equivalent system in an embodiment of the present application;
FIG. 14 is a comparison of curves before and after active power filtering for strategy A in an embodiment of the present application;
FIG. 15 is a schematic diagram illustrating a comparison of curves before and after filtering of active power of strategy B in the embodiment of the present application;
FIG. 16 is a schematic diagram of a power angle curve of strategy A in an embodiment of the present application;
FIG. 17 is a schematic diagram of a power angle curve of strategy B in an embodiment of the present application;
FIG. 18 is a schematic view of a structure of an electronic device in an embodiment of the present application;
fig. 19 is an overall flowchart of a method for determining the severity of a dc fault in the embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.
In an embodiment, in order to comprehensively consider characteristics of a power angle in an ac/dc power transmission system, determine severity of different dc faults, and visually compare impact influences of the different dc faults on a power grid, referring to fig. 19, the present application provides a method for determining the severity of a dc fault, including:
s001: extracting corresponding low-frequency band fault characteristic signals according to transient data of the alternating current and direct current power transmission system; wherein the transient data comprises: the generator end alternating voltage, the generator end alternating current and the rotor angle of each generator on the alternating current side;
s002: determining equivalent electromagnetic power and an equivalent power angle of the alternating-current and direct-current power transmission system in a fault period according to the low-frequency band fault characteristic signal; wherein, the method for calculating the equivalent electromagnetic power and the equivalent power angle is detailed in the following;
s003: and determining the severity of the direct current fault according to the equivalent electromagnetic power and the equivalent power angle.
It can be understood that, in order to avoid the problem of DC shutdown caused by a DC line fault and the problem of overvoltage caused by the failed locking of the converter valve, and improve the DC operation reliability of the ac/DC power transmission system, a DC line fault restart sequence (DFRS for short) is set in the DC control protection system, and the maximum allowable number of times of the converter valve phase conversion failure is also set. However, a restart mechanism is used after a fault of a direct-current line occurs, and energy accumulated during fault processing brings impact to an alternating-current and direct-current power transmission system; different restarting strategies bring different degrees of impact on the AC/DC power transmission system. If the restart fails or the number of allowed phase change failures is too large, the action time of a safety control device in the alternating current and direct current power transmission system is directly influenced. Therefore, the impact of different dc faults on the severity of the ac/dc transmission system must be determined in order to select a suitable post-fault strategy.
The "restart strategy" can be understood as follows: in order to ensure the reliability of direct current power supply, when a direct current transmission system has faults such as direct current line faults or multiple phase conversion failures of a converter valve, a 'restart strategy' (similar to an alternating current line reclosing) is usually adopted for system recovery. For example, in practical engineering, the extra-high voltage dc restart strategy includes, but is not limited to: dc monopolar 2 restarts, dc bipolar 1 restart, and bipolar 2 restarts.
The embodiment of the application selects a device with lower sampling frequency, comprehensively considers the characteristics of power angles, provides a screening method for judging the severity of different direct current faults, solves the problem that the impact on a power grid caused by different direct current faults is difficult to visually compare, and mainly comprises the following steps: determining an operation mode, carrying out data acquisition, extracting fault characteristic signals, calculating equivalent electromagnetic power and an equivalent power angle, drawing a power angle curve and/or calculating system kinetic energy, determining the severity of the direct current fault and the like. The method overcomes the defects that various direct current faults are difficult to compare and different restarting strategies have influence on the system in the prior art, has clear judgment process, does not need complex calculation, and provides basis for formulating reasonable control protection strategies, thereby improving the stability of the system.
In the embodiment of the application, the method for determining the severity of the direct current fault can acquire corresponding transient data according to the operation mode of the alternating current/direct current power transmission system, extract corresponding fault characteristic signals, further calculate the power and the power angle of the system, and finally determine the severity of the direct current fault according to the power and the power angle.
In another embodiment, referring to fig. 1, the method for determining the severity of a dc fault provided in the present application includes:
s100: acquiring corresponding transient data according to the running mode of the alternating current and direct current power transmission system; the operation modes comprise a full-on mode and an overhauling mode of the generator set;
s101: extracting corresponding low-frequency band fault characteristic signals according to transient data of the alternating current and direct current power transmission system; the transient data includes: the generator end alternating voltage, the generator end alternating current and the rotor angle of each generator on the alternating current side; specifically, a synchronous phasor measurement device (also called PMU measurement unit) is used for collecting fault data of an AC/DC power transmission system, and the angular speed variation of a generator is used as a protection starting criterion to identify the occurrence time of the fault; extracting corresponding low-frequency band fault characteristic signals from the occurrence time of the fault;
s102: determining equivalent electromagnetic power and an equivalent power angle of the alternating-current and direct-current power transmission system in a fault period according to the low-frequency band fault characteristic signal;
s103: determining system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts different restarting strategies to recover the system after a fault according to the equivalent electromagnetic power and the equivalent power angle;
s104: and determining the severity of the occurrence of the direct current fault according to the kinetic energy of the system.
Specifically, firstly, the operation mode of an alternating current and direct current system is determined, and transient data are collected. The running mode of the alternating current and direct current system needs to determine the number of starting-up units, the access position and the actual output of the thermal power generating unit, the sending power of the direct current channel and the alternating current channel, the reactive power compensation parameters of the converter station and the like. For example, the generator set full start mode: the thermal power generating unit is completely started and operates at a rated power, the direct current operates at a limit power, the alternating current channel is overloaded, and the converter station excessively supplements a certain capacitance. The maintenance mode is as follows: half of the thermal power generating units are opened, the rest of the thermal power generating units are overhauled, the thermal power generating units operate at half rated power, direct current operates at limit power, an alternating current channel is lightly loaded, and a converter station excessively supplements a certain capacitance. Under the determined operation mode, the data of the generator terminal alternating voltage, the generator terminal alternating current and the rotor angle of each generator at the alternating current side in the extra-high voltage alternating current-direct current system and the rotor angle of the equivalent system are respectively acquired during different direct current faults and restarting strategies.
And secondly, extracting low-frequency-band fault signals and calculating the electromagnetic power of each generator. And decomposing the acquired power signal into a sub-band space, and further acquiring a low-frequency range of a proper signal (on the basis of keeping the original fault characteristics, the acquisition frequency is reduced as much as possible). According to the embodiment of the application, the calculated active power variable at the outlet of the generator is decomposed to a subband space by using the Butterworth low-pass filter, the interference of high-frequency noise of a line is filtered, and a sampled signal is 0-200 Hz.
Thirdly, the system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts different restarting strategies to recover the system after the fault can be determined according to the equivalent electromagnetic power and the equivalent power angle. The step can be used for comparing direct current faults, such as two commutation failure faults, a single-pole grounding fault and the like, and can distinguish the influence of different faults on an alternating current and direct current power transmission system in the same time; the method can also be used for the influence degree of different restarting strategies on the system after the same direct current fault.
Fourthly, determining the severity of the direct current fault according to the kinetic energy of the system. After the fault, some faults are instantaneous faults, direct current can be recovered as soon as possible through a restarting strategy, and safety and stability measures after the fault can be effectively guided by determining the faults and screening the severity of the influence of restarting after the fault on a system.
According to the method for determining the severity of the direct current fault, the kinetic energy of the alternating current-direct current power transmission system can be calculated according to the power and the power angle, and the severity of the direct current fault is sequenced according to the kinetic energy, so that impact influences on the system caused by various direct current faults and different restarting strategies can be compared, the calculation process is clear, complex operation is not needed, a basis is provided for subsequently formulating a reasonable control protection strategy, and the operation stability of the system is improved.
In one embodiment, referring to fig. 2, the fault signature comprises: voltage fault characteristic signals, current fault characteristic signals and rotor angle fault characteristic signals; determining the electromagnetic power and the power angle of the alternating current-direct current power transmission system in the fault time period according to the fault characteristic signal, wherein the determining comprises the following steps:
s201: determining the active power of each generator in the system fault time period according to the voltage fault characteristic signal and the current fault characteristic signal of each generator;
s202: determining equivalent electromagnetic power of the alternating current-direct current power transmission system in a fault period according to the inertia time constant of each generator and the active power of each generator in the system fault period;
s203: and determining the equivalent power angle of the alternating current-direct current power transmission system in the fault time period according to the inertia time constant of each generator and the rotor angle fault characteristic signal.
It will be appreciated that, referring to fig. 12, the three-phase power is a phase a, a phase B, and a phase C in this order, wherein
The phase A instantaneous voltage of the ith generator,
the phase A is instantaneous current of the ith generator.
The equivalent electromagnetic power and the equivalent power angle of the alternating-current and direct-current power transmission system are calculated by adopting an extended equal area method (EEAC), and particularly, a generator set in the system is researched. The cluster with serious disturbance is divided into S, other clusters are divided into A, for example, the extra-high voltage AC line fault at the DC transmitting end, the extra-high voltage set (or in the three-level connection) with the electrical distance closer to the fault position is divided into the serious cluster S, and the DC receiving end set is divided into A. The rotor angles of the units in the clusters are not relatively swung. The equivalent electrical output power and the equivalent power angle are as follows:
in the formula: p i And P j Active power for each generator; delta i And delta j For each generator rotor angle; m i And M j Is the inertia time constant of each generator; p and delta are equivalent electromagnetic power and equivalent power angle of an equivalent system.
As can be seen from the above description, the method for determining the severity of the dc fault provided by the present application can determine the electromagnetic power and the power angle of the ac/dc power transmission system in the fault period according to the fault characteristic signal.
In an embodiment, referring to fig. 3, when determining, according to respective electromagnetic powers and power angles of the ac/dc power transmission system in a fault time period and a steady-state time period, that the ac/dc power transmission system adopts different post-fault restart strategies for fault recovery, system kinetic energy generated by the ac/dc power transmission system includes:
s301: determining an electromagnetic power fault value according to the equivalent electromagnetic power;
s302: and determining the kinetic energy of the system according to the mechanical input power of the prime mover, the electromagnetic power fault value and the rotor angle of each generator.
It is understood that the dc fault includes, but is not limited to, a single pole ground fault, a two commutation failure fault, a three commutation failure fault, and the like. In steps S301 to S302, it is necessary to calculate the kinetic energy of the system during the system recovery period using different restart strategies after the same dc fault occurs. Strategies such as bipolar twice full-voltage one-time buck restart, bipolar twice full-voltage restart, unipolar twice full-voltage one-time buck while blocking the antipodal restart function, bipolar one-time restart, etc.)
In the formula A 1 Kinetic energy of an equivalent system; p M Is the mechanical input power of the prime mover in the equivalent system, per unit value; p is EMi The peak value and the per unit value of the electromagnetic power of the generator are obtained; i is the time period number, i =1 is the steady state stage before failure (t)<t 0 ) I =2 is the fault phase (t) 0 ～t c ) I =3 is the post fault clearing stage (t)>t c ) (ii) a Delta is the generator rotor angle in rad. Wherein, A is calculated 1 When considering only the failure phase (t) 0 ～t c )。
As can be seen from the above description, the method for determining the severity of a dc fault provided in the present application can determine, according to the respective electromagnetic powers and power angles of the ac/dc power transmission system in the fault time period and the steady-state time period, the system kinetic energy generated by the ac/dc power transmission system when the ac/dc power transmission system adopts different restart strategies after the fault for fault recovery.
In one embodiment, referring to fig. 4, the determining the severity of the dc fault according to the kinetic energy of the system includes:
s401: sorting the magnitude of system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts different restarting strategies to carry out fault recovery after a fault;
s402: and determining the severity of the fault according to the sequencing result, and generating a corresponding strategy set.
It can be understood that the kinetic energy of the system obtained under different direct current faults and different restart strategies form a set A = { A = } 1 ,A 2 …A n }. Sequencing example A is carried out on system kinetic energy under all faults from large to small 1 >A 2 …A n The larger the kinetic energy of the system is, the larger the impact on the system is, and then a fault screening set is obtained.
From the above description, the method for determining the severity of the dc fault provided by the present application can determine the severity of the dc fault according to the kinetic energy of the system.
In one embodiment, referring to fig. 5, determining the severity of the dc fault according to the equivalent electromagnetic power and the equivalent power angle includes:
s501: generating a relation curve graph of the equivalent electromagnetic power and the equivalent power angle;
s502: determining the severity from the relationship graph.
It is understood that with reference to fig. 12, steady state refers to both pre-fault and post-fault, transient states in the fault. Wherein, the normal operation mode: the point a is the normal generator operating point, and the corresponding power angle is delta 0 (ii) a And (3) a fault stage: the power characteristic is immediately reduced to P2 after the fault, the rotor angle cannot change suddenly due to the inertia of the rotor, the operating point is immediately changed from the point a to the point b, and the rotor angle of the generator accelerates to move from the operating point b to the operating point c due to the fact that the prime mover is unchanged and is larger than the electromagnetic power; timely fault removal: the power characteristic of the generator becomes P3 and the generator operating point abruptly changes from c to e. The electromagnetic power of the generator is larger than the mechanical power of the prime motor, and the rotor angle is decelerated. The larger the area of A1, the greater the influence on the system.
From the above description, the method for determining the severity of the dc fault provided by the present application can determine the severity according to the relationship graph.
To more clearly illustrate the methods provided herein, an example will now be given.
In simulation analysis, generally, the feasibility of a screening method for judging the severity of different direct current faults will be discussed first; and then, based on the data obtained by simulation, data processing is carried out, the severity of different faults to the power grid is sequenced, and theoretical reference is provided for the operation mode of the power grid.
An actual engineering alternating-current and direct-current combined outgoing system (equivalent to an alternating-current and direct-current power transmission system in the embodiment of the application) is built based on an RTDS simulation platform, a direct-current sending end alternating-current system is equivalent, the equivalent impedance of a sending end is X =0.02313pu, and an equivalent system diagram is shown in FIG. 13. The external 12 thermal power generating units that connect of alternating current system, 6 among them thermal power generating unit insert 1050kV side bus, 6 insert 525kV side bus. The direct current system adopts a bipolar wiring mode, a receiving end is connected in a layering mode, the direct current rated voltage is +/-800 kV, and the rated capacity is 10000MW.
In a certain alternating current-direct current system shown in fig. 13, the direct current power is 4500MW, a filter provides 1938MVar reactive power, 9 thermal power generating units are turned on, a unipolar ground fault occurs at the first section of a 0.5s bipolar line, the fault lasts for 100ms, verification is performed by taking two faults, namely a bipolar 2-time full-voltage restart success (strategy a) and a bipolar 1-time full-voltage restart success (strategy B), as examples, and other fault calculation methods are the same.
Step one, determining an initial alternating current/direct current operation mode: 9 thermal power generating units are started and run at rated power, the direct current power is 4500MW, the alternating current channel power is 1130MW, and the converter station capacitor provides reactive power 1938MVar; acquiring transient data: and respectively acquiring data of machine end alternating voltage, machine end alternating current and a rotor angle of 9 machine sets and a rotor angle of an equivalent power grid.
And step two, performing low-pass filtering on the calculated active power of the generator. According to the embodiment of the application, the calculated active power variable at the outlet of the generator is decomposed to a subband space by using the Butterworth low-pass filter, the interference of high-frequency noise of a line is filtered, and a sampled signal is 0-200 Hz. When the system is restored by using the strategy a, waveforms before and after active power filtering are shown in fig. 14. When the system is restored by using the strategy B, waveforms before and after active power filtering are shown in fig. 15. As can be seen from fig. 14 and 15, the main waveform characteristics are retained after filtering.
And step three, calculating equivalent electrical output power and an equivalent power angle.
And step four, drawing a power angle curve, wherein the strategy A corresponds to the graph 16, and the strategy B corresponds to the graph 17.
Step five: and calculating the system kinetic energy of the direct current fault.
A1 Strategy A ＝358.5493
A1 Policy B ＝213.9555
Step six: and comparing the system kinetic energy values of the strategy A and the strategy B, and sequencing the system kinetic energy values from large to small, wherein the larger the value is, the smaller the impact capacity on the system is, and the final fault screening set is obtained.
1) Under the condition of keeping original signal characteristics, the frequency of the sampling device is reduced, a screening method for judging the severity of different direct current faults is provided, and the purchase cost of the device is reduced.
2) The principle is simple, complex calculation is not needed, the impact degree influence on the power grid under various fault conditions is visually given, and a reference suggestion is provided for the actual power grid operation mode.
3) The method can calculate the direct current line fault, various restarting strategies, abnormal operation conditions of commutation failure and the like, and has wide application range.
Based on the same inventive concept, the present application further provides a device for determining the severity of a dc fault, which can be used to implement the method described in the foregoing embodiments, as described in the following embodiments. Because the principle of solving the problems of the determining device for determining the severity of the direct current fault is similar to the method for determining the severity of the direct current fault, the implementation of the determining device for the severity of the direct current fault can refer to the implementation of the determining method based on the software performance standard, and repeated parts are not repeated. As used hereinafter, the term "unit" or "module" may be a combination of software and/or hardware that implements a predetermined function. While the system described in the embodiments below is preferably implemented in software, implementations in hardware, or a combination of software and hardware are also possible and contemplated.
In an embodiment, referring to fig. 6, in order to comprehensively consider characteristics of a power angle in an ac/dc power transmission system, determine severity of different dc faults, and visually compare impact influences of the different dc faults on a power grid, the present application provides an apparatus for determining severity of a dc fault, including: a low frequency feature extraction unit 701, a power angle determination unit 702, and a severity determination unit 703.
A low-frequency feature extraction unit 701, configured to extract a corresponding low-frequency band fault feature signal according to transient data of the ac/dc power transmission system; the transient data includes: the generator-end alternating voltage, the generator-end alternating current and the rotor angle of each generator;
a power angle determining unit 702, configured to determine, according to the low-frequency band fault characteristic signal, an equivalent electromagnetic power and an equivalent power angle of the ac-dc power transmission system in a fault time period;
and a severity determining unit 703, configured to determine a severity of the dc fault according to the equivalent electromagnetic power and the equivalent power angle.
In an embodiment, the apparatus for determining the severity of a dc fault further includes:
the transient data acquisition unit is used for acquiring corresponding transient data according to the running mode of the alternating current-direct current power transmission system; the operation mode comprises a full-on mode and an overhauling mode of the generator set.
In an embodiment, referring to fig. 11, the severity determining unit 703 includes: a system kinetic energy determination module 1101 and a severity determination module 1102.
A system kinetic energy determining module 1201, configured to determine, according to the equivalent electromagnetic power and the equivalent power angle, system kinetic energy generated by the ac/dc power transmission system when the ac/dc power transmission system adopts each restart strategy to perform system recovery after a fault;
a severity determination module 1202, configured to determine a severity of the dc fault according to the kinetic energy of the system.
In an embodiment, referring to fig. 10, the severity determining unit 703 includes: a relationship curve generation module 1301 and a severity degree judgment module 1302.
A relation curve generating module 1301, configured to generate a relation curve graph of the equivalent electromagnetic power and the equivalent power angle;
a severity determination module 1302, configured to determine the severity according to the relationship graph.
In one embodiment, referring to fig. 7, the fault signature includes: voltage fault characteristic signals, current fault characteristic signals and rotor angle fault characteristic signals; the power angle determining unit 702 includes: an active power determination module 801, an electromagnetic power determination module 802, and a power angle determination module 803.
An active power determining module 801, configured to determine active power of each generator in a system fault period according to the voltage fault characteristic signal and the current fault characteristic signal of each generator;
an electromagnetic power determining module 802, configured to determine equivalent electromagnetic power of the ac/dc power transmission system in a fault period according to the inertia time constant of each generator and the active power of each generator in the system fault period;
a power angle determining module 803, configured to determine an equivalent power angle of the ac/dc power transmission system in a fault time period according to the inertia time constants of the generators and the rotor angle fault characteristic signal.
In one embodiment, referring to fig. 8, system kinetic energy determination module 1201 includes: a fault value determination module 901 and a system kinetic energy determination module 902.
A fault value determining module 901, configured to determine an electromagnetic power fault value according to the equivalent electromagnetic power;
a system kinetic energy determining module 902, configured to determine the system kinetic energy according to the mechanical input power of the prime mover, the electromagnetic power failure value, and the rotor angle of each generator.
In one embodiment, referring to FIG. 9, the severity determination module 1202 includes: a kinetic energy ordering module 1001 and a policy aggregation module 1002.
A kinetic energy sorting module 1001, configured to sort the magnitudes of system kinetic energy generated by the ac/dc power transmission system when the ac/dc power transmission system adopts different restart strategies for fault recovery after a fault;
and the policy set module 1002 is configured to determine the severity of the fault according to the sorting result, and generate a corresponding policy set.
In order to comprehensively consider the characteristics of the power angle in the ac/dc power transmission system, determine the severity of different dc faults, and visually compare the impact influence of different dc faults on the power grid, the present application provides an embodiment of an electronic device for implementing all or part of the contents in the method for determining the severity of a dc fault, where the electronic device specifically includes the following contents:
a Processor (Processor), a Memory (Memory), a communication Interface (Communications Interface) and a bus; the processor, the memory and the communication interface complete mutual communication through the bus; the communication interface is used for realizing information transmission between the determining device of the severity of the direct current fault and relevant equipment such as a core service system, a user terminal, a relevant database and the like; the logic controller may be a desktop computer, a tablet computer, a mobile terminal, and the like, but the embodiment is not limited thereto. In this embodiment, the logic controller may be implemented with reference to the embodiment of the method for determining the severity of a dc fault and the embodiment of the apparatus for determining the severity of a dc fault in the embodiments, and the contents of the embodiments are incorporated herein, and repeated descriptions are omitted.
It is understood that the user terminal may include a smart phone, a tablet electronic device, a network set-top box, a portable computer, a desktop computer, a Personal Digital Assistant (PDA), an in-vehicle device, a smart wearable device, and the like. Wherein, intelligence wearing equipment can include intelligent glasses, intelligent wrist-watch, intelligent bracelet etc..
In practical applications, part of the method for determining the severity of the dc fault may be performed on the electronic device side as described above, or all operations may be performed in the client device. The selection may be specifically performed according to the processing capability of the client device, the limitation of the user usage scenario, and the like. This is not a limitation of the present application. The client device may further include a processor if all operations are performed in the client device.
The client device may have a communication module (i.e., a communication unit), and may be in communication connection with a remote server to implement data transmission with the server. The server may include a server on the side of the task scheduling center, and in other implementation scenarios, the server may also include a server on an intermediate platform, for example, a server on a third-party server platform that is communicatively linked to the task scheduling center server. The server may include a single computer device, or may include a server cluster formed by a plurality of servers, or a server structure of a distributed apparatus.
Fig. 18 is a schematic block diagram of a system configuration of an electronic device 9600 according to the embodiment of the present application. As shown in fig. 18, the electronic device 9600 can include a central processor 9100 and a memory 9140; the memory 9140 is coupled to the central processor 9100. Notably, this fig. 18 is exemplary; other types of structures may also be used in addition to or in place of the structures to implement telecommunications or other functions.
In one embodiment, the method for determining the severity of a dc fault may be integrated into the central processor 9100. The central processor 9100 may be configured to control as follows:
s001: extracting corresponding low-frequency band fault characteristic signals according to transient data of the alternating current and direct current power transmission system; wherein the transient data comprises: the generator end alternating voltage, the generator end alternating current and the rotor angle of each generator on the alternating current side;
s002: according to the low-frequency band fault characteristic signal, determining equivalent electromagnetic power and an equivalent power angle of the alternating current-direct current power transmission system in a fault period; wherein, the method for calculating the equivalent electromagnetic power and the equivalent power angle is detailed in the following;
s003: and determining the severity of the occurrence of the direct current fault according to the equivalent electromagnetic power and the equivalent power angle.
In the embodiment of the application, the method for determining the severity of the direct current fault can acquire corresponding transient data according to the operation mode of the alternating current/direct current power transmission system, extract corresponding fault characteristic signals, further calculate the power and the power angle of the system, and finally determine the severity of the direct current fault according to the power and the power angle.
In another embodiment, the dc fault severity determining apparatus may be configured separately from the central processing unit 9100, for example, the dc fault severity determining apparatus may be configured as a chip connected to the central processing unit 9100, and the function of the dc fault severity determining method may be implemented by the control of the central processing unit.
As shown in fig. 18, the electronic device 9600 may further include: a communication module 9110, an input unit 9120, an audio processor 9130, a display 9160, and a power supply 9170. It is noted that the electronic device 9600 also does not necessarily include all of the components shown in fig. 18; in addition, the electronic device 9600 may further include components not shown in fig. 18, which can be referred to in the prior art.
As shown in fig. 18, the central processor 9100, which is sometimes referred to as a controller or operational control, can include a microprocessor or other processor device and/or logic device, the central processor 9100 receives input and controls the operation of the various components of the electronic device 9600.
The memory 9140 can be, for example, one or more of a buffer, a flash memory, a hard drive, a removable media, a volatile memory, a non-volatile memory, or other suitable device. The information relating to the failure may be stored, and a program for executing the information may be stored. And the central processing unit 9100 can execute the program stored in the memory 9140 to realize information storage or processing, or the like.
The input unit 9120 provides input to the central processor 9100. The input unit 9120 is, for example, a key or a touch input device. Power supply 9170 is used to provide power to electronic device 9600. The display 9160 is used for displaying display objects such as images and characters. The display may be, for example, an LCD display, but is not limited thereto.
The memory 9140 can be a solid state memory, e.g., read Only Memory (ROM), random Access Memory (RAM), a SIM card, or the like. There may also be a memory that holds information even when power is off, can be selectively erased, and is provided with more data, an example of which is sometimes called an EPROM or the like. The memory 9140 could also be some other type of device. Memory 9140 includes a buffer memory 9141 (sometimes referred to as a buffer). The memory 9140 may include an application/function storage part 9142, the application/function storage part 9142 being used to store application programs and function programs or a flow for executing the operation of the electronic device 9600 by the central processing unit 9100.
The memory 9140 can also include a data store 9143, the data store 9143 for storing data, such as contacts, digital data, pictures, sounds, and/or any other data used by the electronic device. The driver storage portion 9144 of the memory 9140 may include various drivers for the electronic device for communication functions and/or for performing other functions of the electronic device (e.g., messaging applications, contact book applications, etc.).
The communication module 9110 is a transmitter/receiver 9110 that transmits and receives signals via an antenna 9111. The communication module (transmitter/receiver) 9110 is coupled to the central processor 9100 to provide input signals and receive output signals, which may be the same as in the case of a conventional mobile communication terminal.
Based on different communication technologies, a plurality of communication modules 9110, such as a cellular network module, a bluetooth module, and/or a wireless lan module, may be disposed in the same electronic device. The communication module (transmitter/receiver) 9110 is also coupled to a speaker 9131 and a microphone 9132 via an audio processor 9130 to provide audio output via the speaker 9131 and receive audio input from the microphone 9132, thereby implementing ordinary telecommunication functions. The audio processor 9130 may include any suitable buffers, decoders, amplifiers and so forth. In addition, the audio processor 9130 is also coupled to the central processor 9100, thereby enabling recording locally through the microphone 9132 and enabling locally stored sounds to be played through the speaker 9131.
An embodiment of the present application further provides a computer-readable storage medium capable of implementing all the steps in the method for determining the severity of a dc fault whose execution subject is a server or a client in the foregoing embodiments, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the computer program implements all the steps in the method for determining the severity of a dc fault whose execution subject is a server or a client in the foregoing embodiments, for example, when the processor executes the computer program, the processor implements the following steps:
s001: extracting corresponding low-frequency band fault characteristic signals according to transient data of the alternating current and direct current power transmission system; wherein the transient data comprises: the generator end alternating voltage, the generator end alternating current and the rotor angle of each generator on the alternating current side;
s002: according to the low-frequency band fault characteristic signal, determining equivalent electromagnetic power and an equivalent power angle of the alternating current-direct current power transmission system in a fault period; wherein, the method for calculating the equivalent electromagnetic power and the equivalent power angle is detailed in the following;
s003: and determining the severity of the direct current fault according to the equivalent electromagnetic power and the equivalent power angle.
In the embodiment of the application, the method for determining the severity of the direct current fault can acquire corresponding transient data according to the operation mode of the alternating current/direct current power transmission system, extract corresponding fault characteristic signals, further calculate the power and the power angle of the system, and finally determine the severity of the direct current fault according to the power and the power angle.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, apparatus, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention 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 invention has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (devices), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams 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.
The principle and the implementation mode of the invention are explained by applying specific embodiments in the invention, and the description of the embodiments is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (17)
1. A method for determining the severity of a dc fault, comprising:
extracting corresponding low-frequency band fault characteristic signals according to transient data of the alternating current and direct current power transmission system;
according to the low-frequency band fault characteristic signal, determining equivalent electromagnetic power and an equivalent power angle of the alternating current-direct current power transmission system in a fault period;
and determining the severity of the occurrence of the direct current fault according to the equivalent electromagnetic power and the equivalent power angle.
2. The method for determining the severity of a dc fault according to claim 1, further comprising:
acquiring corresponding transient data according to the running mode of the alternating current and direct current power transmission system; the operation mode comprises a full-starting mode and an overhauling mode of the generator set; the transient data includes: the generator-side alternating voltage, the generator-side alternating current and the rotor angle of each generator.
3. The method for determining the severity of a dc fault according to claim 2, wherein the determining the severity of the dc fault according to the equivalent electromagnetic power and the equivalent power angle comprises:
determining system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts each restarting strategy to carry out system recovery after a fault according to the equivalent electromagnetic power and the equivalent power angle;
and determining the severity of the occurrence of the direct current fault according to the kinetic energy of the system.
4. The method for determining the severity of a dc fault according to claim 2, wherein the determining the severity of the dc fault according to the equivalent electromagnetic power and the equivalent power angle comprises:
generating a relation curve graph of the equivalent electromagnetic power and the equivalent power angle;
determining the severity from the relationship graph.
5. The method of claim 2, wherein the low-band fault signature comprises: voltage fault characteristic signals, current fault characteristic signals and rotor angle fault characteristic signals; the determining the equivalent electromagnetic power and the equivalent power angle of the alternating current-direct current transmission system in the fault time period according to the low-frequency band fault characteristic signal comprises the following steps:
determining active power of each generator in a system fault period according to the voltage fault characteristic signal and the current fault characteristic signal of each generator;
determining equivalent electromagnetic power of the alternating current-direct current power transmission system in a fault period according to the inertia time constant of each generator and the active power of each generator in the system fault period;
and determining the equivalent power angle of the alternating current-direct current power transmission system in the fault time period according to the inertia time constant of each generator and the rotor angle fault characteristic signal.
6. The method for determining the severity of a dc fault according to claim 3, wherein the determining, according to the equivalent electromagnetic power and the equivalent power angle, the system kinetic energy generated by the ac/dc power transmission system during system recovery by using each restart strategy after the fault comprises:
determining an electromagnetic power fault value according to the equivalent electromagnetic power;
and determining the kinetic energy of the system according to the mechanical input power of the prime mover, the electromagnetic power fault value and the rotor angle of each generator.
7. The method for determining the severity of a dc fault according to claim 3, wherein the determining the severity of the dc fault according to the kinetic energy of the system comprises:
sorting the magnitude of system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts each restarting strategy to carry out fault recovery after a fault;
and determining the severity of the fault according to the sequencing result, and generating a corresponding strategy set.
8. An apparatus for determining the severity of a dc fault, comprising:
the low-frequency characteristic extraction unit is used for extracting corresponding low-frequency band fault characteristic signals according to transient data of the alternating current-direct current power transmission system;
the power angle determining unit is used for determining equivalent electromagnetic power and an equivalent power angle of the alternating current-direct current power transmission system in a fault period according to the low-frequency band fault characteristic signal;
and the severity determining unit is used for determining the severity of the occurrence of the direct current fault according to the equivalent electromagnetic power and the equivalent power angle.
9. The apparatus for determining the severity of a dc fault according to claim 8, further comprising:
the transient data acquisition unit is used for acquiring corresponding transient data according to the running mode of the alternating current-direct current power transmission system; the operation mode comprises a full-starting mode and an overhauling mode of the generator set; the transient data includes: the generator side alternating voltage, the generator side alternating current and the rotor angle of each generator.
10. The apparatus for determining severity of dc fault according to claim 9, wherein said severity determining unit comprises:
the system kinetic energy determining module is used for determining system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts each restarting strategy to carry out system recovery after a fault according to the equivalent electromagnetic power and the equivalent power angle;
and the severity determining module is used for determining the severity of the occurrence of the direct current fault according to the kinetic energy of the system.
11. The apparatus for determining the severity of a dc fault according to claim 9, wherein said severity determining unit comprises:
the relation curve generating module is used for generating a relation curve graph of the equivalent electromagnetic power and the equivalent power angle;
and the severity judging module is used for determining the severity according to the relation curve graph.
12. The dc fault severity determination apparatus of claim 9, wherein said fault signature signal comprises: voltage fault characteristic signals, current fault characteristic signals and rotor angle fault characteristic signals; the power angle determining unit includes:
the active power determining module is used for determining the active power of each generator in the system fault period according to the voltage fault characteristic signal and the current fault characteristic signal of each generator;
the electromagnetic power determining module is used for determining equivalent electromagnetic power of the alternating current-direct current transmission system in a fault period according to the inertia time constant of each generator and the active power of each generator in the system fault period;
and the power angle determining module is used for determining an equivalent power angle of the alternating current-direct current power transmission system in a fault period according to the inertia time constant of each generator and the rotor angle fault characteristic signal.
13. The apparatus for determining severity of dc fault of claim 10, wherein said system kinetic energy determination module comprises:
the fault value determining module is used for determining an electromagnetic power fault value according to the equivalent electromagnetic power;
and the system kinetic energy determining module is used for determining the system kinetic energy according to the mechanical input power of the prime mover, the electromagnetic power fault value and the rotor angle of each generator.
14. The apparatus for determining severity of dc fault according to claim 10, wherein said severity determination module comprises:
the kinetic energy sequencing module is used for sequencing the magnitude of system kinetic energy generated by the AC/DC power transmission system when the AC/DC power transmission system adopts each restarting strategy to carry out fault recovery after a fault;
and the strategy set module is used for determining the severity of the fault according to the sequencing result and generating a corresponding strategy set.
15. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the method for determining the severity of a dc fault of any one of claims 1 to 7 when executing the program.
16. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method for determining the severity of a dc fault of any one of claims 1 to 7.
17. A computer program product comprising computer program/instructions, characterized in that the computer program/instructions, when executed by a processor, implement the steps of the method for determining the severity of a dc fault according to any one of claims 1 to 7.
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