CN116613752B - New energy affected range and voltage calculation method and system under main network fault - Google Patents

New energy affected range and voltage calculation method and system under main network fault Download PDF

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CN116613752B
CN116613752B CN202310889360.0A CN202310889360A CN116613752B CN 116613752 B CN116613752 B CN 116613752B CN 202310889360 A CN202310889360 A CN 202310889360A CN 116613752 B CN116613752 B CN 116613752B
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new energy
node
fault
voltage
grid
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CN116613752A (en
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李子秀
陈宁
曲立楠
唐冰婕
钱敏慧
贾一超
张红颖
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China Electric Power Research Institute Co Ltd CEPRI
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China Electric Power Research Institute Co Ltd CEPRI
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/16—Matrix or vector computation, e.g. matrix-matrix or matrix-vector multiplication, matrix factorization
    • 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
    • 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
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • 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
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
    • 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
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Abstract

A method and a system for calculating the affected range and voltage of new energy under the failure of a main network comprise the following steps: based on the response of the synchronous generator, the static load and the new energy source during the fault period, calculating the fault voltage of the main network node by adopting a Thevenin equivalent method; according to the new energy access scene type and the main network node fault voltage, combining the new energy grid-connected point and the upper-level 220kV node voltage relation of the new energy grid-connected point, and calculating the new energy grid-connected point voltage; and obtaining the affected range and the affected degree of the new energy affected by the fault according to the voltage of the new energy grid-connected point and the set threshold. According to the method, the main network node fault voltage is calculated based on the Thevenin equivalent method and the response of the synchronous generator, the static load and the new energy source during the fault period, the fault influence range and degree are determined by combining the main network fault voltage with the association relation, the contribution of the short circuit current is considered, the new energy source access scene difference is fully considered, and the affected range and degree of the new energy source can be more accurately estimated.

Description

New energy affected range and voltage calculation method and system under main network fault
Technical Field
The invention relates to the technical field of power systems and new energy power generation, in particular to a method and a system for calculating the affected range and voltage of new energy under the fault of a main network.
Background
The new energy power generation is mainly connected into a power grid through a current source type inverter, and adopts a current source control mode to enable a power system to have the characteristics of space nonlinear distribution, time discontinuous distribution and the like, and the transient process after the power grid fault cannot be directly analyzed by an alternating current power grid fault analysis method based on the Thevenin equivalent circuit theory. The traditional alternating current fault analysis method is represented by a normalized computer fault analysis calculation method, and any fault in the power system is represented by the influence of all-network Thevenin equivalent superposition fault branches at fault ports on network topology. In the method for solving the equivalent parameters of the whole network Thevenin, a node admittance matrix inversion-based method is an important branch, a modified node admittance matrix is constructed according to the running state of the system, and the self-impedance of an equivalent node can be obtained as Thevenin equivalent impedance by obtaining the modified node impedance matrix through inversion.
In an Italian local power grid with new energy power generation access, each point fault in a power transmission grid is subjected to simulation scanning, each node voltage after the fault is obtained, the relationship between the fault position and the node voltage is represented by utilizing a thermodynamic diagram, and an analytical expression of the relationship is deduced according to an impedance matrix calculated based on short circuit.
The method is based on time domain simulation, and has the following problems: the modeling is complex, and the calculation time is long; (2) The influence of new energy power generation is not considered, the deduced relation expression between the fault position and the node voltage is not accurate enough, and the voltage of the new energy power generation grid-connected point cannot be quantitatively estimated.
Gu Ke, hou Lai, bi Tianshu et al published in 2021 under the name of "engineering practical new energy short-circuit current calculation based on local iteration of fault area", obtain each node voltage before and after the fault by using a traditional short-circuit current calculation method, in order to eliminate the influence of the node voltage initial value on the partition, calculate the amplitude ratio of the node voltage after the fault to the voltage before the fault as the voltage drop coefficient of the node, set the partition critical voltage coefficient to be 0.9 according to the measured data of the new energy short-circuit current, and finally combine the node set of the fault area roughly divided by the connection relation between the nodes.
The method divides the fault area by considering the voltage drop difference, and has the following problems: (1) Short-circuit current contribution of new energy power generation during faults is not considered enough; (2) The difference of new energy access scenes is not fully considered, and when a synchronous generator is accessed in a middle-low voltage power grid, a certain supporting effect is achieved on the voltage of a nearby node, so that the fault areas are possibly not communicated.
Disclosure of Invention
In order to solve the problems that modeling in the prior art is complex, calculation consumes a long time, the influence of new energy power generation is not considered, the pushed relation expression between the fault position and the node voltage is not accurate enough, the short-circuit current contribution of the new energy power generation in the fault period is not considered enough, the new energy access scene difference is not fully considered, when a synchronous generator is accessed in a low-voltage power grid, a certain supporting effect is brought about on the voltage of a nearby node, and the fault area is possibly not communicated, the invention provides a method for calculating the affected range and the voltage of the new energy under the fault of a main network, which comprises the following steps:
based on the response of the synchronous generator, the static load and the new energy source during the fault period, calculating the fault voltage of the main network node by adopting a Thevenin equivalent method;
According to the new energy access scene type and the main network node fault voltage, calculating the new energy grid-connected point voltage by combining the new energy grid-connected point and the upper 220kV node voltage relation;
and obtaining the affected range and the affected degree of the new energy affected by the fault according to the voltage of the new energy grid-connected point and the set threshold.
Optionally, the calculating the main network node fault voltage by using the davin equivalent method based on the responses of the synchronous generator, the static load and the new energy during the fault includes:
the static characteristics of static load are approximately used as a fault calculation model, the synchronous generator adopts an engineering practical fault calculation model and is overlapped on corresponding self admittances in a node admittance matrix obtained by power flow analysis of the power system, and a corrected node admittance matrix is obtained;
correcting the corrected node admittance matrix by using a Gaussian elimination method, and obtaining a corrected node impedance matrix of nodes above 220kV by matrix inversion;
calculating fault current generated by a fault branch based on the node impedance matrix of the corrected 220kV and above nodes;
the parallel impedance from the photovoltaic power generation access point to the external node except the upper-level power substation, the self impedance of the substation node and the rated current of the photovoltaic power generation are combined with the sudden increase calculation to obtain a sudden increase part of the output current of the photovoltaic power generation at the moment of the fault of the photovoltaic power generation upper-level power substation;
And combining the node impedance matrix of the corrected nodes of 220kV and above, fault current generated by a fault branch and a sudden increase part of the photovoltaic power generation output current at the moment of the fault with a node voltage calculation formula after the fault to obtain the node fault voltage of the main network.
Optionally, the correcting the node admittance matrix by using a gaussian elimination method, and obtaining a corrected node impedance matrix of 220kV and above nodes by matrix inversion includes:
reserving the nodes with the voltage of 220kV and above in the corrected node admittance matrix by using a Gaussian elimination method to obtain a node admittance matrix of the nodes with the voltage of 220kV and above;
and inverting the node admittance matrix of the 220kV and above nodes to obtain a corrected node impedance matrix of the 220kV and above nodes.
Optionally, the calculating the fault current generated by the fault branch based on the node impedance matrix of the corrected 220kV and above nodes includes:
calculating the Norton equivalent admittance and current of the fault port according to the node impedance matrix of the corrected nodes of 220kV and above;
and calculating the fault current generated by the fault branch based on the Norton equivalent admittance and the current of the fault port.
Optionally, the mutation calculation formula is as follows:
In the method, in the process of the invention,a sudden increase part of output current of the photovoltaic power generation at the moment of failure; />The parallel impedance from the photovoltaic power generation access point to the external node except the upper-level 220kV transformer substation is provided; />Self-impedance of the substation node; />Is rated current of photovoltaic power generation.
Optionally, the node voltage calculation formula after the fault is as follows:
in the method, in the process of the invention,the voltage of each node after the fault; />The voltage of each node before failure; />Is->Neutralization nodei，jOf corresponding columnsNA x 2 order matrix; />Fault current generated for the fault branch; />Is->Intermediate nodes s1, s2, …, slOf corresponding columnsN×lA rank matrix; />A node impedance matrix for the modified 220kV and above nodes; />The sudden increase part of the output current of the photovoltaic power generation is the moment of failure.
Optionally, the calculating the voltage of the new energy grid-connected point according to the new energy access scene type and the fault voltage of the main network node and combining the voltage relation between the new energy grid-connected point and the 220kV node at the upper stage of the new energy grid-connected point comprises:
judging the type of a new energy access scene;
when the type of the scene is a new energy access scene, acquiring node voltage from the new energy access scene, and deducing new energy grid-connected point voltage in the new energy access scene by using a superposition theorem from the node voltage and the main network node fault voltage;
When the types of the scenes are synchronous generators and new energy access scenes, node voltages are obtained from the synchronous generators and the new energy access scenes, and the node voltages and the main network node fault voltages are used for deducing new energy grid-connected point voltages in the synchronous generators and the new energy access scenes by using a superposition theorem;
wherein, the types of the scene include: the system has a new energy access scene, a synchronous generator and a new energy access scene.
Optionally, the new energy grid-connected point voltage in the new energy access scene is calculated according to the following formula:
wherein,for 110kV line impedance, ">For the voltage of a new energy grid-connected point in a scene with new energy access, the voltage is +.>220kV node voltage in main network node fault voltage, < ->Equivalent impedance of static load, +.>For 220/110kV transformer impedance, Z 3 10kV line impedance, ">Is a new energy fault current.
Optionally, the voltage of the new energy grid-connected point in the synchronous generator and the new energy access scene is calculated according to the following formula:
in the method, in the process of the invention,the method comprises the steps of connecting a synchronous generator and new energy into voltage of a new energy grid-connected point in a scene, and adding +.>For the subsynchronous current of synchronous generators, +.>For subsynchronous reactance of synchronous generator, Z 4 And j is an imaginary unit for the line impedance between the access point and the parallel point of the synchronous generator.
Optionally, the obtaining the affected range and the affected degree of the new energy affected by the fault according to the voltage combination of the new energy grid-connected point and the set threshold includes:
judging whether the voltage of the new energy grid-connected point is smaller than a set threshold value, if so, the new energy grid-connected point is the grid-connected point of the affected new energy, otherwise, the new energy grid-connected point is a normal operation node;
calculating the affected degree by the voltage of the grid connection point of the affected new energy;
acquiring line impedance between a grid-connected point superior 220kV node of the affected new energy source and the grid-connected point of the affected new energy source;
calculating the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy based on the self impedance of the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy and the mutual impedance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy;
and calculating an affected range by combining the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy source and the line impedance between the upper-level 220kV node of the grid-connected point of the affected new energy source and the grid-connected point of the affected new energy source.
Optionally, the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy source is calculated according to the following formula:
in the method, in the process of the invention,is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqAn electrical distance therebetween;and->Respectively, are fault nodespIs connected with the upper 220kV node of the point of sale of new energy under the influence and self-impedance of (a)qIs a self-impedance of (2);and->Respectively, are fault nodespIs connected with the upper 220kV node of the point of sale of new energy under the influence and the trans-impedance of (2)qIs a trans-impedance of (c).
Optionally, the affected range is calculated as follows:
in the method, in the process of the invention,for affected area +.>Is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqElectrical distance between->The method is the line impedance between the upper 220kV node of the grid connection point of the affected new energy source and the grid connection point of the affected new energy source.
In still another aspect, the present invention further provides a system for calculating a new energy affected range and voltage under a main network fault, including:
the node fault calculation module is used for calculating the node fault voltage of the main network by adopting a Thevenin equivalent method based on the responses of the synchronous generator, the static load and the new energy during the fault period;
the grid-connected voltage calculation module is used for calculating the voltage of a new energy grid-connected point according to the type of a new energy access scene and the fault voltage of the main network node and combining the voltage relation between the new energy grid-connected point and the 220kV node at the upper level of the new energy grid-connected point;
And the influence calculation module is used for obtaining the influenced range and the influenced degree of the new energy influenced by the fault according to the voltage combination set threshold value of the new energy grid-connected point.
Optionally, the node fault calculation module includes:
the correction sub-module is used for using the static characteristics of the static load as a fault calculation model, and the synchronous generator adopts an engineering practical fault calculation model and is overlapped on corresponding self admittances in the node admittance matrix obtained by power flow analysis of the power system to obtain a corrected node admittance matrix;
the elimination processing submodule is used for correcting the corrected node admittance matrix by using a Gaussian elimination method, and obtaining a corrected node impedance matrix of nodes of 220kV and above by matrix inversion;
the fault current calculation sub-module is used for calculating the fault current generated by the fault branch circuit based on the node impedance matrix of the corrected 220kV and above nodes;
the sudden increase part calculation submodule is used for combining the parallel impedance from the photovoltaic power generation access point to the node except the external node of the upper-level substation, the self impedance of the substation node and the rated current of the photovoltaic power generation with the sudden increase calculation to obtain a sudden increase part of the photovoltaic power generation output current at the moment of the fault of the photovoltaic power generation upper-level substation;
And the fault voltage calculation sub-module is used for obtaining the main network node fault voltage by combining the node impedance matrix of the corrected nodes above 220kV, the fault current generated by the fault branch and the sudden increase part of the photovoltaic power generation output current at the moment of the fault with the node voltage calculation formula after the fault.
Optionally, the cancellation processing submodule is specifically configured to:
reserving the nodes with the voltage of 220kV and above in the corrected node admittance matrix by using a Gaussian elimination method to obtain a node admittance matrix of the nodes with the voltage of 220kV and above;
and inverting the node admittance matrix of the 220kV and above nodes to obtain a corrected node impedance matrix of the 220kV and above nodes.
Optionally, the fault current calculation submodule is specifically configured to:
calculating the Norton equivalent admittance and current of the fault port according to the node impedance matrix of the corrected nodes of 220kV and above;
and calculating the fault current generated by the fault branch based on the Norton equivalent admittance and the current of the fault port.
Optionally, the mutation calculation formula is as follows:
in the method, in the process of the invention,a sudden increase part of output current of the photovoltaic power generation at the moment of failure; />The parallel impedance from the photovoltaic power generation access point to the external node except the upper-level 220kV transformer substation is provided; / >Self-impedance of the substation node; />Is rated current of photovoltaic power generation.
Optionally, the node voltage calculation formula after the fault is as follows:
in the method, in the process of the invention,the voltage of each node after the fault; />The voltage of each node before failure; />Is->Neutralization nodei，jOf corresponding columnsNA x 2 order matrix; />Fault current generated for the fault branch;/>is->Intermediate nodes s1, s2, …, slOf corresponding columnsN×lA rank matrix; />A node impedance matrix for the modified 220kV and above nodes; />The sudden increase part of the output current of the photovoltaic power generation is the moment of failure.
Optionally, the grid-connected voltage calculation module is specifically configured to:
judging the type of a new energy access scene;
when the type of the scene is a new energy access scene, acquiring node voltage from the new energy access scene, and deducing new energy grid-connected point voltage in the new energy access scene by using a superposition theorem from the node voltage and the main network node fault voltage;
when the types of the scenes are synchronous generators and new energy access scenes, node voltages are obtained from the synchronous generators and the new energy access scenes, and the node voltages and the main network node fault voltages are used for deducing new energy grid-connected point voltages in the synchronous generators and the new energy access scenes by using a superposition theorem;
Wherein, the types of the scene include: the system has a new energy access scene, a synchronous generator and a new energy access scene.
Optionally, the new energy grid-connected point voltage in the new energy access scene is calculated according to the following formula:
wherein,is 110kVLine impedance,/->For the voltage of a new energy grid-connected point in a scene with new energy access, the voltage is +.>220kV node voltage in main network node fault voltage, < ->Equivalent impedance of static load, +.>For 220/110kV transformer impedance, Z 3 10kV line impedance, ">Is a new energy fault current.
Optionally, the voltage of the new energy grid-connected point in the synchronous generator and the new energy access scene is calculated according to the following formula:
in the method, in the process of the invention,the method comprises the steps of connecting a synchronous generator and new energy into voltage of a new energy grid-connected point in a scene, and adding +.>For the subsynchronous current of synchronous generators, +.>For subsynchronous reactance of synchronous generator, Z 4 And j is an imaginary unit for the line impedance between the access point and the parallel point of the synchronous generator.
Optionally, the influence calculation module is specifically configured to:
judging whether the voltage of the new energy grid-connected point is smaller than a set threshold value, if so, the new energy grid-connected point is the grid-connected point of the affected new energy, otherwise, the new energy grid-connected point is a normal operation node;
Calculating the affected degree by the voltage of the grid connection point of the affected new energy;
acquiring line impedance between a grid-connected point superior 220kV node of the affected new energy source and the grid-connected point of the affected new energy source;
calculating the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy based on the self impedance of the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy and the mutual impedance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy;
and calculating an affected range by combining the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy source and the line impedance between the upper-level 220kV node of the grid-connected point of the affected new energy source and the grid-connected point of the affected new energy source.
Optionally, the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy source is calculated according to the following formula:
in the method, in the process of the invention,is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqAn electrical distance therebetween;and->Respectively, are fault nodespIs connected with the upper 220kV node of the point of sale of new energy under the influence and self-impedance of (a) qIs a self-impedance of (2);and->Respectively, are fault nodespIs connected with the upper 220kV node of the point of sale of new energy under the influence and the trans-impedance of (2)qIs a trans-impedance of (c).
Optionally, the affected range is calculated as follows:
in the method, in the process of the application,for affected area +.>Is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqElectrical distance between->The method is the line impedance between the upper 220kV node of the grid connection point of the affected new energy source and the grid connection point of the affected new energy source.
In yet another aspect, the present application also provides a computing device comprising: one or more processors;
a processor for executing one or more programs;
when the one or more programs are executed by the one or more processors, the method for calculating the affected range and the voltage of the new energy under the main network fault is realized.
In still another aspect, the present application further provides a computer readable storage medium, on which a computer program is stored, where the computer program is executed to implement a method for calculating an affected range and voltage of a new energy under a main network fault as described above.
Compared with the prior art, the application has the beneficial effects that:
the application provides a new energy affected range and voltage calculation method under a main network fault, which comprises the following steps: based on the response of the synchronous generator, the static load and the new energy source during the fault period, calculating the fault voltage of the main network node by adopting a Thevenin equivalent method; according to the new energy access scene type and the main network node fault voltage, calculating the new energy grid-connected point voltage by combining the new energy grid-connected point and the upper 220kV node voltage relation; and obtaining the affected range and the affected degree of the new energy affected by the fault according to the voltage of the new energy grid-connected point and the set threshold. According to the method, the main network node fault voltage and fault current are calculated by considering the responses of the synchronous generator, the static load and the new energy source during the fault based on the Thevenin equivalent method, the fault influence range is determined by combining the fault current with the association relation, the contribution of the short circuit current is considered, the new energy source access scene difference is fully considered, the new energy source influence range can be more accurately estimated, modeling is not needed, the influence of new energy source power generation is considered, and the deduced relation between the fault position and the node voltage is more accurate.
Drawings
FIG. 1 is a flow chart of a method for calculating the affected range and voltage of new energy under the failure of a main network;
fig. 2 is a flowchart of an implementation of a method for calculating a new energy affected area and voltage under a main network fault according to the present invention.
Detailed Description
In order to overcome the defects of the prior art, the invention scientifically evaluates the influence range and the influence degree of severe faults of a power transmission network on new energy sources, provides a method for calculating the influence range and the voltage of the new energy sources under the faults of a main network, evaluates the influence degree of the faults by adopting a method for calculating the voltage of each node after the faults based on the Thevenin equivalent, summarizes the common scenes of the power distribution network, and evaluates the influence range of the faults with the apparent line length.
The technical scheme adopted by the invention is suitable for analyzing a power system containing high-proportion new energy, and provides a new energy affected range and voltage calculation method under the condition of main network faults, which can be used for evaluating the affected range and the affected degree of the severe faults of the power transmission network on the new energy, is beneficial to providing requirements for the power generation grid-connection performance of the new energy according to local conditions, and assists a power grid dispatching department to reasonably formulate treatment measures and plans and support power grid dispatching operation decisions.
Example 1:
a new energy affected range and voltage calculation method under a main network fault is shown in figure 1, and comprises the following steps:
step 1: based on the response of the synchronous generator, the static load and the new energy source during the fault period, calculating the fault voltage of the main network node by adopting a Thevenin equivalent method;
step 2: according to the new energy access scene type and the main network node fault voltage, calculating the new energy grid-connected point voltage by combining the new energy grid-connected point and the upper 220kV node voltage relation;
step 3: and obtaining the affected range and the affected degree of the new energy affected by the fault according to the voltage of the new energy grid-connected point and the set threshold.
The present invention is described in detail below, and a method for calculating the affected range and voltage of a new energy under a main network fault, as shown in fig. 2, includes:
the step 1 is based on the response of the synchronous generator, the static load and the new energy source during the fault period, and the main network node fault voltage is calculated by adopting a Thevenin equivalent method, and comprises the following steps:
the static characteristics of static load are approximately used as a fault calculation model, the synchronous generator adopts an engineering practical fault calculation model and is overlapped on corresponding self admittances in a node admittance matrix obtained by power flow analysis of the power system, and a corrected node admittance matrix is obtained;
Correcting the corrected node admittance matrix by using a Gaussian elimination method, and obtaining a corrected node impedance matrix of 220kV and above nodes by matrix inversion;
calculating fault current generated by a fault branch based on the node impedance matrix of the corrected 220kV and above nodes;
the parallel impedance from the photovoltaic power generation access point to the external node except the upper-level power substation, the self impedance of the substation node and the rated current of the photovoltaic power generation are combined with the sudden increase calculation to obtain a sudden increase part of the output current of the photovoltaic power generation at the moment of the fault of the photovoltaic power generation upper-level power substation;
and combining the node impedance matrix of the corrected nodes of 220kV and above, fault current generated by a fault branch and a sudden increase part of the photovoltaic power generation output current at the moment of the fault with a node voltage calculation formula after the fault to obtain the node fault voltage of the main network.
Step 1 is described in detail below:
link 1: based on the Thevenin equivalent method, a computer fault analysis and calculation method for correcting and normalizing the response of the synchronous generator, static load and new energy during the fault period is considered, and the fault voltage of a 220kV node is calculated;
link 1-1: based on a typical mode of operation, power system flow calculations are performed and a node admittance matrix of the system is calculated.
Link 1-2: the synchronous generator adopts an engineering practical calculation model, namely a sub-transient potential series connection sub-transient reactanceFurther converted to a current source parallel impedance model using the davit-norton transform. The fault calculation model is approximately established according to the static characteristics of the static load, and is as follows:
in the method, in the process of the invention,equivalent impedance of static load, +.>For the voltage at the load node in the initial load flow result,the conjugate of the apparent power of the load constant impedance part of the node, the outflow node is positive, +.>Active power for static load, +.>And j is an imaginary unit, which is reactive power of a static load.
Links 1-3: incorporating a fault calculation model of the synchronous generator and static load into the node admittance matrix to synchronize the generator access nodesiLoad access nodejFor example, the correction method is as follows:
in the method, in the process of the invention,for counting the nodes after the synchronous generator fault calculation modeliSelf-admittance of->Calculating a model-based node for load faultsjSelf-admittance of->And->Is a nodei、jSelf-admittance of->For access nodesiSub-transient reactance of synchronous generator, +.>For access nodesjIs a load equivalent impedance of the load.
Links 1-4: retaining the modified node admittance matrix using Gaussian elimination 220kV and above, the node admittance matrix of 220kV and above>The method comprises the following steps:
wherein:to preserve the modified node admittance matrix +.>A self-impedance matrix for 220kV and above nodes;and->The transimpedance matrix is a transimpedance matrix of nodes of 220kV and above and nodes of 220kV and below; />Self-impedance matrix for nodes below 220kV, < ->Node admittance matrix for 220kV and above nodes.
Links 1-5: node admittance matrix for 220kV and above nodesInverting to obtain node impedance matrix of corrected 220kV and above nodes>Set up failure port->The nodes at the two ends arei，jNorton equivalent admittance of the failed portAnd current->：
In the method, in the process of the invention,norton equivalent admittance for the failed port, < ->Norton current for the failed port, +.>Is the inverse of the equivalent impedance of the failed port Thevenin, < >>Is->Middle nodeiSelf-impedance of->And->Is->Middle nodei、jMutual impedance between->Is->Middle nodejSelf-impedance of->For injecting nodes before failureiIs of (a)Flow (I)>For injecting nodes before failurejCurrent of->Is a node before failureiVoltage of>Is a node before failurejIs set in the above-described voltage range.
Links 1-6: and calculating the fault current generated by the three-phase short-circuit grounding fault. When a failure portA kind of electronic devicekThree-phase short circuit grounding is generated at the point, and the grounding admittance is Y F ，kThe line admittance on both sides of the dot is +.>And->Fault current generated by fault branch +.>The method comprises the following steps:
in the method, in the process of the invention,variation of node admittance matrix for faulty branch,/->And->Is thatkLine admittance on both sides of the dot, +.>For the ground admittance +.>Fault current generated for a faulty branch, +.>Norton equivalent admittance for the failed port, < ->Is the norton current of the failed port.
Links 1-7: and the overcurrent capacity of new energy sources at the moment of failure is considered. In normal operation, photovoltaic power generation is taken as an example, unit power factor control is generally adopted, and the output active and reactive currents are as follows:
wherein:active current which is a new energy source; />Reactive current as new energy; />Is the active reference current;the voltage at the grid-connected point is the voltage; />Is the active reference power; />Is the reactive reference current. />
At the moment of failure occurrence, voltage at the photovoltaic power generation grid-connected point drops, and according to the response characteristic of the inner ring, in order to keep the active output as a given reference value, the active reference current is increased, and the active current output by the photovoltaic power generation is changed into:
in the method, in the process of the invention,outputting the amplitude of active current for the photovoltaic power generation at the moment of failure; />Is the active reference power; />The amplitude of the voltage of the photovoltaic generator terminal at the moment of failure; / >Maximum current allowed to be output for photovoltaic power generation; />The fault current is output by the photovoltaic power generation at the moment of fault; />Is->J is an imaginary unit; />The voltage at the grid-connected point of photovoltaic power generation is the moment of failure.
From the above, the maximum value of the photovoltaic power generation output current at the moment of failure is determined by the tolerance of the power electronic device, and the accurate value is obtained by iterative calculation, so as to avoid the iterative calculationThe convergence problem in the power grid application adopts engineering practical values. According to the actual measurement data, the current output by the photovoltaic power generation at the moment of failure generally reaches 1.1-1.3 times of the rated current, and in order to ensure the conservation of the result, the multiple is 1.1, and the current is calculated to an upper-level 220kV transformer substation. Let the number of nodes in the power networkNWhereinl220kV nodes (denoted as s1, s2, …, s)l) The lower network has new energy access and voltage of each node after failureThe method comprises the following steps:
in the method, in the process of the invention,a sudden increase part of output current of the photovoltaic power generation at the moment of failure; />The parallel impedance from the photovoltaic power generation access point to the external node except the upper-level 220kV transformer substation is provided; />Self-impedance of the substation node; />Rated current for photovoltaic power generation; />The voltage of each node after the fault; / >The voltage before the node failure is 220kV and above; />Is->Neutralization nodei，jOf corresponding columnsNA x 2 order matrix; />Fault current generated for the fault branch; />Is->Intermediate nodes s1, s2, …, slOf corresponding columnsN×lA rank matrix; />Is made of->，/>,…,/>A composed current column vector, wherein +.>,/>And->Representing the moment of failure nodes s1, s2, s, respectivelylAnd a sudden increase part of the photovoltaic power generation output current.
In the step 2, according to the new energy access scene type and the main network node fault voltage, combining the relation between the new energy grid-connected point and the upper 220kV node voltage, calculating the new energy grid-connected point voltage, including:
judging the type of a new energy access scene;
when the type of the scene is a new energy access scene, acquiring node voltage from the new energy access scene, and deducing new energy grid-connected point voltage in the new energy access scene by using a superposition theorem from the node voltage and the main network node fault voltage;
when the types of the scenes are synchronous generators and new energy access scenes, node voltages are obtained from the synchronous generators and the new energy access scenes, and the node voltages and the main network node fault voltages are used for deducing new energy grid-connected point voltages in the synchronous generators and the new energy access scenes by using a superposition theorem;
Wherein, the types of the scene include: the system has a new energy access scene, a synchronous generator and a new energy access scene.
Step 2 is described in detail below:
link 2: analyzing and extracting a new energy access scene, and constructing a voltage relation between a new energy grid-connected point and a 220kV node, wherein the method comprises the following steps of:
link 2-1: according to different influence mechanisms of synchronous generators, loads and new energy sources on transmission network fault propagation characteristics, four power distribution network scenes are extracted: and the load is only below 220kV, the synchronous generator is connected, the new energy is connected, and the synchronous generator and the new energy are connected. The scheme of the invention is applied to new energy sources in two typical power distribution network scenes of new energy source access, synchronous generator access and new energy source access, as shown in figure 2.
Link 2-2: according to 220kV node voltage in the main network node fault voltage obtained in the step 2And deducing the voltage of the new energy grid-connected point in the new energy access scene by using the superposition theorem. Is provided withWherein->For the scenario with new energy access, the new energy grid-connected point voltage can be expressed as:
wherein Z is T2 Is the impedance of the 110/35kV transformer,for 110kV line impedance, Z T3 Impedance of 35/10kV transformer, Z 2 For 35kV line impedance, ">New energy grid-connected point voltage in scene with new energy access, +.>220kV node voltage in main network node fault voltage, < ->Equivalent impedance of static load, +.>For 220/110kV transformer impedance, Z 3 10kV line impedance, ">Is a new energy fault current.
For the scene with synchronous generator and new energy access, the new energy grid-connected point voltage can be expressed as:
in the method, in the process of the invention,the method comprises the steps of connecting a synchronous generator and new energy into voltage of a new energy grid-connected point in a scene, and adding +.>For the subsynchronous current of synchronous generators, +.>For subsynchronous reactance of synchronous generator, Z 4 The impedance of the line between the access point and the grid-connected point of the synchronous generator is obtained.
In step 3, obtaining the affected degree and the affected range of the new energy affected by the fault according to the voltage combination set threshold value of the new energy grid-connected point, including:
judging whether the voltage of the new energy grid-connected point is smaller than a set threshold value, if so, the new energy grid-connected point is the grid-connected point of the affected new energy, otherwise, the new energy grid-connected point is a normal operation node;
calculating the degree of influence of faults according to the voltage of the grid connection point of the new energy;
acquiring line impedance between a grid-connected point superior 220kV node of the affected new energy source and the grid-connected point of the affected new energy source;
Calculating the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy based on the self impedance of the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy and the mutual impedance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy;
and calculating an affected range by combining the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy source and the line impedance between the upper-level 220kV node of the grid-connected point of the affected new energy source and the grid-connected point of the affected new energy source.
Step 3 is described in detail below:
step 3, setting a threshold value according to the results of the step 1 and the step 2 to obtain the affected range and the affected degree of the new energy affected by the fault, wherein the steps comprise:
link 3-1: the setting threshold value can be set based on a regulation, or can be set empirically, in this embodiment, the low voltage crossing threshold value of the photovoltaic power station is regulated to be 0.9p.u. in GB/T19964-2012 photovoltaic power station access power system technical regulation, and a value of 0.9p.u., namely 0.9 per unit is selected as the threshold value for determining that the new energy is affected by the fault;
link 3-2: the grid connection point of the affected new energy can be determined by links 2-2 and 3-1 kAnd then the grid connection point of new energy sources can be obtainedkSuperior 220kV nodeqPoint of attachmentkLine impedance between. For looped networks of 220kV and above, fault nodes are usedpAnd nodeqImpedance electrical distance between->And evaluating the fault influence range. Finally will->And->Summing can be used for fault nodepTo new energykThe electrical distance represents the affected range->：
In the method, in the process of the invention,is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqAn electrical distance therebetween; />And->Respectively, are fault nodespSuperior 220kV node of grid-connected point of affected new energyqIs a self-impedance of (2); />And->Respectively, are fault nodespSuperior 220kV node of grid-connected point of affected new energyqIs a trans-impedance of (c).
The affected range is calculated as follows:
in the method, in the process of the invention,for affected area +.>Is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqElectrical distance between->The method is the line impedance between the upper 220kV node of the grid connection point of the affected new energy source and the grid connection point of the affected new energy source.
In order to more intuitively represent the range of the new energy affected by the fault, by combining the characteristic that the voltage class network below 220kV is radial, the line length can be calculated by utilizing the line impedance and the corresponding line parameters, and the fault influence range can be quantified by using the physical distance;
Link 3-3: the voltage of the affected new energy grid-connected point can be obtained through the link 2-2, and the voltage value of the affected new energy grid-connected point is used as the affected degree of the fault.
Compared with the prior art, the method has the advantages that a new energy equivalent model related to various factors such as a control mode, a voltage level, a power supply type and the like is not required to be established, and the method can be better applied to fault calculation of large power grids at regional level and above;
the invention summarizes the differences of the two scenes of the new energy access, the synchronous generator access and the new energy access below 220kV, fully considers the influence of the supporting function of the synchronous generator and the new energy overcurrent capacity, can evaluate the voltage drop condition of different positions more accurately compared with the prior art, and is beneficial to more reasonably providing requirements for the new energy grid-connected performance;
the invention reserves the equivalent model of each voltage class line in the power distribution network, adopts the line length to quantitatively evaluate the range of fault influence, and can more intuitively determine the scale of the influenced new energy compared with the abstract electric distance.
The invention also reflects the new energy condition influenced by the fault from two directions of the degree influenced by the fault and the influence range by taking the voltage value at the moment of the fault of the new energy grid-connected point as the degree influenced by the fault.
Example 2:
in still another aspect, the present invention further provides a system for calculating a new energy affected range and a fault voltage under a power transmission network fault, including:
the node fault calculation module is used for calculating the node fault voltage of the main network by adopting a Thevenin equivalent method and the response of new energy based on the synchronous generator and the static load during the fault period;
the grid-connected voltage calculation module is used for calculating the voltage of a new energy grid-connected point according to the type of a new energy access scene and the fault voltage of the main network node and combining the voltage relation between the new energy grid-connected point and the 220kV node at the upper level of the new energy grid-connected point;
and the influence calculation module is used for obtaining the influenced range and the influenced degree of the new energy influenced by the fault according to the voltage combination set threshold value of the new energy grid-connected point.
Optionally, the node fault calculation module includes:
the correction sub-module is used for using the static characteristics of the static load as a fault calculation model, and the synchronous generator adopts an engineering practical fault calculation model and is overlapped on corresponding self admittances in the node admittance matrix obtained by power flow analysis of the power system to obtain a corrected node admittance matrix;
The elimination processing submodule is used for correcting the corrected node admittance matrix by using a Gaussian elimination method, and obtaining a corrected node impedance matrix of 220kV and above nodes by matrix inversion;
the fault current calculation sub-module is used for calculating the fault current generated by the fault branch circuit based on the node impedance matrix of the corrected 220kV and above nodes;
the sudden increase part calculation submodule is used for combining the parallel impedance from the photovoltaic power generation access point to the node except the external node of the upper-level substation, the self impedance of the substation node and the rated current of the photovoltaic power generation with the sudden increase calculation to obtain a sudden increase part of the photovoltaic power generation output current at the moment of the fault of the photovoltaic power generation upper-level substation;
and the fault voltage calculation sub-module is used for obtaining the main network node fault voltage by combining the node impedance matrix of the corrected nodes of 220kV and above, the fault current generated by the fault branch and the sudden increase part of the photovoltaic power generation output current at the moment of the fault with the node voltage calculation formula after the fault.
Optionally, the cancellation processing submodule is specifically configured to:
reserving the nodes with the voltage of 220kV and above in the corrected node admittance matrix by using a Gaussian elimination method to obtain a node admittance matrix of the nodes with the voltage of 220kV and above;
And inverting the node admittance matrix of the 220kV and above nodes to obtain a corrected node impedance matrix of the 220kV and above nodes.
Optionally, the fault current calculation submodule is specifically configured to:
calculating the Norton equivalent admittance and current of the fault port according to the node impedance matrix of the corrected nodes of 220kV and above;
and calculating the fault current generated by the fault branch based on the Norton equivalent admittance and the current of the fault port.
Optionally, the mutation calculation formula is as follows:
in the method, in the process of the invention,instantaneous photovoltaic power generation for faultsA sudden increase portion of the output current; />The parallel impedance from the photovoltaic power generation access point to the external node except the upper-level 220kV transformer substation is provided; />Self-impedance of the substation node; />Is rated current of photovoltaic power generation.
Optionally, the node voltage calculation formula after the fault is as follows:
in the method, in the process of the invention,the voltage of each node after the fault; />The voltage of each node before failure; />Is->Neutralization nodei，jOf corresponding columnsNA x 2 order matrix; />Fault current generated for the fault branch; />Is->Intermediate nodes s1, s2, …, slOf corresponding columnsN×lA rank matrix; />A node impedance matrix for the modified 220kV and above nodes; / >For the sudden increase of the output current of the photovoltaic power generation at the moment of failure, by +.>，/>,…,/>A composed current column vector, wherein +.>,/>And->Representing the moment of failure nodes s1, s2, s, respectivelylAnd a sudden increase part of the photovoltaic power generation output current.
Optionally, the grid-connected voltage calculation module is specifically configured to:
judging the type of a new energy access scene;
when the type of the scene is a new energy access scene, acquiring node voltage from the new energy access scene, and deducing new energy grid-connected point voltage in the new energy access scene by using a superposition theorem from the node voltage and the main network node fault voltage;
when the types of the scenes are synchronous generators and new energy access scenes, node voltages are obtained from the synchronous generators and the new energy access scenes, and the node voltages and the main network node fault voltages are used for deducing new energy grid-connected point voltages in the synchronous generators and the new energy access scenes by using a superposition theorem;
wherein, the types of the scene include: the system has a new energy access scene, a synchronous generator and a new energy access scene.
Optionally, the new energy grid-connected point voltage in the new energy access scene is calculated according to the following formula:
wherein,for 110kV line impedance, " >For the voltage of a new energy grid-connected point in a scene with new energy access, the voltage is +.>220kV node voltage in main network node fault voltage, < ->Equivalent impedance of static load, +.>For 220/110kV transformer impedance, Z 3 10kV line impedance, ">Is a new energy fault current.
Optionally, the voltage of the new energy grid-connected point in the synchronous generator and the new energy access scene is calculated according to the following formula:
in the method, in the process of the invention,the method comprises the steps of connecting a synchronous generator and new energy into voltage of a new energy grid-connected point in a scene, and adding +.>For the subsynchronous current of synchronous generators, +.>For subsynchronous reactance of synchronous generator, Z 4 And j is an imaginary unit for the line impedance between the access point and the parallel point of the synchronous generator.
Optionally, the influence calculation module is specifically configured to:
judging whether the voltage of the new energy grid-connected point is smaller than a set threshold value, if so, the new energy grid-connected point is the grid-connected point of the affected new energy, otherwise, the new energy grid-connected point is a normal operation node;
calculating the degree of influence of faults according to the voltage of the grid connection point of the new energy;
acquiring line impedance between a grid-connected point superior 220kV node of the affected new energy source and the grid-connected point of the affected new energy source;
calculating the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy based on the self impedance of the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy and the mutual impedance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy;
And calculating an affected range by combining the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy source and the line impedance between the upper-level 220kV node of the grid-connected point of the affected new energy source and the grid-connected point of the affected new energy source.
Optionally, the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy source is calculated according to the following formula:
in the method, in the process of the invention,is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqAn electrical distance therebetween;and->Respectively, are fault nodespIs connected with the upper 220kV node of the point of sale of new energy under the influence and self-impedance of (a)qIs a self-impedance of (2);and->Respectively, are fault nodespIs connected with the upper 220kV node of the point of sale of new energy under the influence and the trans-impedance of (2)qIs a trans-impedance of (c).
Optionally, the affected range is calculated as follows:
in the method, in the process of the invention,for affected area +.>Is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqElectrical distance between->The method is the line impedance between the upper 220kV node of the grid connection point of the affected new energy source and the grid connection point of the affected new energy source.
Example 3:
based on the same inventive concept, the invention also provides a computer device comprising a processor and a memory for storing a computer program comprising program instructions, the processor for executing the program instructions stored by the computer storage medium. The processor may be a central processing unit (Central Processing Unit, CPU), but may also be other general purpose processor, digital signal processor (Digital Signal Processor, DSP), application specific integrated circuit (ApplicationSpecificIntegrated Circuit, ASIC), off-the-shelf Programmable gate array (FPGA) or other Programmable logic device, discrete gate or transistor logic device, discrete hardware components, etc., which are the computational core and control core of the terminal and are adapted to implement one or more instructions, in particular to load and execute one or more instructions in a computer storage medium to implement the corresponding method flow or corresponding functions, to implement the steps of the new energy affected range and voltage calculation method under a main network fault in the above embodiments.
Example 4:
based on the same inventive concept, the present invention also provides a storage medium, in particular, a computer readable storage medium (Memory), which is a Memory device in a computer device, for storing programs and data. It is understood that the computer readable storage medium herein may include both built-in storage media in a computer device and extended storage media supported by the computer device. The computer-readable storage medium provides a storage space storing an operating system of the terminal. Also stored in the memory space are one or more instructions, which may be one or more computer programs (including program code), adapted to be loaded and executed by the processor. The computer readable storage medium herein may be a high-speed RAM memory or a non-volatile memory (non-volatile memory), such as at least one magnetic disk memory. One or more instructions stored in a computer-readable storage medium may be loaded and executed by a processor to implement the steps of a method for calculating a voltage and an affected range of a new energy under a main network fault in the above embodiment.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, 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 is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. 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.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof, but rather as providing for the use of additional embodiments within the spirit and scope of the present invention.

Claims (16)

1. The utility model provides a new energy affected range and voltage calculation method under a main network fault, which is characterized by comprising the following steps:
Based on the response of the synchronous generator, the static load and the new energy source during the fault period, calculating the fault voltage of the main network node by adopting a Thevenin equivalent method;
according to the new energy access scene type and the main network node fault voltage, calculating the new energy grid-connected point voltage by combining the new energy grid-connected point and the upper-level 220kV node voltage relation of the new energy grid-connected point;
obtaining the affected range and the affected degree of the new energy affected by the fault according to the voltage combination set threshold value of the new energy grid-connected point;
the main network node fault voltage is calculated by adopting a Thevenin equivalent method based on the response of the synchronous generator, the static load and the new energy during the fault, and the method comprises the following steps:
the static characteristics of static load are approximately used as a fault calculation model, the synchronous generator adopts an engineering practical fault calculation model and is overlapped on corresponding self admittances in a node admittance matrix obtained by power flow analysis of the power system, and a corrected node admittance matrix is obtained;
correcting the corrected node admittance matrix by using a Gaussian elimination method, and obtaining a corrected node impedance matrix of 220kV and above nodes by matrix inversion;
calculating fault current generated by a fault branch based on the node impedance matrix of the corrected 220kV and above nodes;
The parallel impedance from the photovoltaic power generation access point to the external node except the upper-level power substation, the self impedance of the substation node and the rated current of the photovoltaic power generation are combined with the sudden increase calculation to obtain a sudden increase part of the output current of the photovoltaic power generation at the moment of the fault of the photovoltaic power generation upper-level power substation;
and combining the node impedance matrix of the corrected nodes of 220kV and above, fault current generated by a fault branch and a sudden increase part of the photovoltaic power generation output current at the moment of the fault with a node voltage calculation formula after the fault to obtain the node fault voltage of the main network.
2. The method of claim 1, wherein said correcting the node admittance matrix using gaussian elimination to obtain a corrected node impedance matrix for 220kV and above nodes from matrix inversion comprises:
reserving the nodes with the voltage of 220kV and above in the corrected node admittance matrix by using a Gaussian elimination method to obtain a node admittance matrix of the nodes with the voltage of 220kV and above;
and inverting the node admittance matrix of the 220kV and above nodes to obtain a corrected node impedance matrix of the 220kV and above nodes.
3. The method of claim 1, wherein said calculating fault currents generated by a faulty branch based on the modified node impedance matrix of 220kV and above nodes comprises:
Calculating the Norton equivalent admittance and current of the fault port according to the node impedance matrix of the corrected nodes of 220kV and above;
and calculating the fault current generated by the fault branch based on the Norton equivalent admittance and the current of the fault port.
4. The method of claim 1, wherein the bump calculation is as follows:
in the method, in the process of the invention,a sudden increase part of output current of the photovoltaic power generation at the moment of failure; />The parallel impedance from the photovoltaic power generation access point to the external node except the upper-level 220kV transformer substation is provided; />Self-impedance of the substation node; />Is rated current of photovoltaic power generation.
5. The method of claim 1, wherein the post-fault node voltage calculation is as follows:
in the method, in the process of the invention,the voltage of each node after the fault; />The voltage of each node before failure; />Is->Neutralization nodei，jOf corresponding columnsNA x 2 order matrix; />Fault current generated for the fault branch; />Is->Intermediate nodes s1, s2, …, slOf corresponding columnsN×lA rank matrix; />A node impedance matrix for the modified 220kV and above nodes; />The sudden increase part of the output current of the photovoltaic power generation is the moment of failure.
6. The method of claim 1, wherein the calculating the new energy grid-connected point voltage according to the new energy access scene type and the main network node fault voltage and combining the new energy grid-connected point and the new energy grid-connected point upper 220kV node voltage relationship comprises:
Judging the type of a new energy access scene;
when the type of the scene is a new energy access scene, acquiring node voltage from the new energy access scene, and deducing new energy grid-connected point voltage in the new energy access scene by using a superposition theorem from the node voltage and the main network node fault voltage;
when the types of the scenes are synchronous generators and new energy access scenes, node voltages are obtained from the synchronous generators and the new energy access scenes, and the node voltages and the main network node fault voltages are used for deducing new energy grid-connected point voltages in the synchronous generators and the new energy access scenes by using a superposition theorem;
wherein, the types of the scene include: the system has a new energy access scene, a synchronous generator and a new energy access scene.
7. The method of claim 6, wherein the new energy grid-tie voltage in the new energy access scenario is calculated as follows:
wherein,for 110kV line impedance, ">For the voltage of a new energy grid-connected point in a scene with new energy access, the voltage is +.>220kV node voltage in main network node fault voltage, < ->Equivalent impedance of static load, +.>For 220/110kV transformer impedance, Z 3 10kV line impedance, " >Is a new energy fault current.
8. The method of claim 7, wherein the new energy grid-tie point voltage in the synchronous generator and new energy access scenario is calculated as follows:
in the method, in the process of the invention,the method comprises the steps of connecting a synchronous generator and new energy into voltage of a new energy grid-connected point in a scene, and adding +.>For the subsynchronous current of synchronous generators, +.>For subsynchronous reactance of synchronous generator, Z 4 And j is an imaginary unit for the line impedance between the access point and the parallel point of the synchronous generator.
9. The method of claim 1, wherein the obtaining the affected range and the affected extent of the new energy affected by the fault according to the new energy grid-connected point voltage in combination with the set threshold value comprises:
judging whether the voltage of the new energy grid-connected point is smaller than a set threshold value, if so, the new energy grid-connected point is the grid-connected point of the affected new energy, otherwise, the new energy grid-connected point is a normal operation node;
calculating the affected degree by the voltage of the grid connection point of the affected new energy;
acquiring line impedance between a grid-connected point superior 220kV node of the affected new energy source and the grid-connected point of the affected new energy source;
calculating the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy based on the self impedance of the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy and the mutual impedance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy;
And calculating an affected range by combining the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy source and the line impedance between the upper-level 220kV node of the grid-connected point of the affected new energy source and the grid-connected point of the affected new energy source.
10. The method of claim 9, wherein an electrical distance between the failed node and a point-of-sale superior 220kV node of the affected new energy source is calculated as follows:
in the method, in the process of the invention,is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqAn electrical distance therebetween; />And->Respectively, are fault nodespIs connected with the upper 220kV node of the point of sale of new energy under the influence and self-impedance of (a)qIs a self-impedance of (2); />And->Respectively, are fault nodespIs connected with the upper 220kV node of the point of sale of new energy under the influence and the trans-impedance of (2)qIs a trans-impedance of (c).
11. The method of claim 9, wherein the affected area is calculated as:
in the method, in the process of the invention,for affected area +.>Is a fault nodepSuperior 220kV node of grid-connected point of affected new energyqElectrical distance between->The method is the line impedance between the upper 220kV node of the grid connection point of the affected new energy source and the grid connection point of the affected new energy source.
12. The utility model provides a new forms of energy affected area and voltage computing system under main network trouble which characterized in that includes:
the node fault calculation module is used for calculating the node fault voltage of the main network by adopting a Thevenin equivalent method based on the responses of the synchronous generator, the static load and the new energy during the fault period;
the grid-connected voltage calculation module is used for calculating the voltage of a new energy grid-connected point according to the type of a new energy access scene and the fault voltage of the main network node and combining the voltage relation between the new energy grid-connected point and the 220kV node at the upper level of the new energy grid-connected point;
the influence calculation module is used for obtaining the influenced range and the influenced degree of the new energy influenced by the fault according to the voltage combination set threshold value of the new energy grid-connected point;
the node fault calculation module includes:
the correction sub-module is used for using the static characteristics of the static load as a fault calculation model, and the synchronous generator adopts an engineering practical fault calculation model and is overlapped on corresponding self admittances in the node admittance matrix obtained by power flow analysis of the power system to obtain a corrected node admittance matrix;
the elimination processing submodule is used for correcting the corrected node admittance matrix by using a Gaussian elimination method, and obtaining a corrected node impedance matrix of nodes of 220kV and above by matrix inversion;
The fault current calculation sub-module is used for calculating the fault current generated by the fault branch circuit based on the node impedance matrix of the corrected 220kV and above nodes;
the sudden increase part calculation submodule is used for combining the parallel impedance from the photovoltaic power generation access point to the node except the external node of the upper-level substation, the self impedance of the substation node and the rated current of the photovoltaic power generation with the sudden increase calculation to obtain a sudden increase part of the photovoltaic power generation output current at the moment of the fault of the photovoltaic power generation upper-level substation;
and the fault voltage calculation sub-module is used for obtaining the main network node fault voltage by combining the node impedance matrix of the corrected nodes above 220kV, the fault current generated by the fault branch and the sudden increase part of the photovoltaic power generation output current at the moment of the fault with the node voltage calculation formula after the fault.
13. The system of claim 12, wherein the grid-tie voltage calculation module is specifically configured to:
judging the type of a new energy access scene;
when the type of the scene is a new energy access scene, acquiring node voltage from the new energy access scene, and deducing new energy grid-connected point voltage in the new energy access scene by using a superposition theorem from the node voltage and the main network node fault voltage;
When the types of the scenes are synchronous generators and new energy access scenes, node voltages are obtained from the synchronous generators and the new energy access scenes, and the node voltages and the main network node fault voltages are used for deducing new energy grid-connected point voltages in the synchronous generators and the new energy access scenes by using a superposition theorem;
wherein, the types of the scene include: the system has a new energy access scene, a synchronous generator and a new energy access scene.
14. The system of claim 12, wherein the influence calculation module is specifically configured to:
judging whether the voltage of the new energy grid-connected point is smaller than a set threshold value, if so, the new energy grid-connected point is the grid-connected point of the affected new energy, otherwise, the new energy grid-connected point is a normal operation node;
calculating the affected degree by the voltage of the grid connection point of the affected new energy;
acquiring line impedance between a grid-connected point superior 220kV node of the affected new energy source and the grid-connected point of the affected new energy source;
calculating the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy based on the self impedance of the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy and the mutual impedance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy;
And calculating an affected range by combining the electrical distance between the fault node and the upper-level 220kV node of the grid-connected point of the affected new energy source and the line impedance between the upper-level 220kV node of the grid-connected point of the affected new energy source and the grid-connected point of the affected new energy source.
15. A computer device, comprising: one or more processors;
the processor is used for storing one or more programs;
when the one or more programs are executed by the one or more processors, the method for calculating the affected range and voltage of new energy under the failure of the main network according to any one of claims 1 to 11 is implemented.
16. A computer readable storage medium, having stored thereon a computer program which, when executed, implements a new energy affected area and voltage calculation method under a main network failure as claimed in any one of claims 1 to 11.
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