CN114460414A - Method for verifying breaking capacity of breaker of power grid bus - Google Patents
Method for verifying breaking capacity of breaker of power grid bus Download PDFInfo
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Abstract
The invention provides a method for checking the breaking capacity of a breaker of a power grid bus, which comprises the following steps: calculating the basic short-circuit current of a fault bus of a power grid without a new energy power station and flexible direct current; calculating a short-circuit current direct-current component attenuation time constant of the fault bus, and calculating the alternating-current short-circuit on-off capacity of the breaker after the direct-current component is considered according to the short-circuit current direct-current component attenuation time constant of the fault bus and the shortest on-off time of the breaker of the fault bus; calculating short-circuit current provided by a new energy power station in a power grid; calculating short-circuit current provided by flexible direct current in a power grid; and judging whether the on-off capability of the breaker meets the requirements or not according to the AC short-circuit on-off capability of the breaker after considering the DC component, the basic short-circuit current, the short-circuit current provided by a new energy power station in the power grid and the short-circuit current provided by the flexible DC in the power grid. The invention can more accurately judge whether the breaking capacity of the circuit breaker meets the requirement.
Description
Technical Field
The invention relates to the technical field of power grids, in particular to a method for verifying the breaking capacity of a breaker of a power grid bus.
Background
The transformation is upgraded to a novel power system taking new energy as a main body in China, and the control of the short-circuit current of a power grid faces more challenges, on one hand, after a large amount of novel power electronic equipment such as a wind power plant, a photovoltaic power station, flexible alternating current and direct current equipment and the like are connected into the power grid, the short-circuit current can be provided for the power grid in a current source mode; on the other hand, because the clean power resources and the load development in China are unbalanced, a network frame with a higher voltage level needs to be built to meet the demand of power exchange between areas, and with the non-sectional promotion of the voltage level, the reactance/resistance ratio of a power grid is continuously increased, and the problem of the direct-current component of the short-circuit current is increasingly highlighted. The invention provides a method for checking the breaking capacity of a circuit breaker by considering a new energy power station, flexible direct current grid connection and short-circuit current direct current components in response to the new potential.
The defects and shortcomings of the prior art are as follows: at present, most of wind power, photovoltaic power and flexible direct current power transmission are connected to the power grid through a full-power converter, and the short-circuit current characteristic provided by the full-power converter to the power grid is greatly different from that of a traditional rotary generator. At present, a method for calculating a short-circuit current provided by a new energy plant or a flexible direct-current transmission body generally needs to perform detailed electromagnetic transient modeling. For the calculation of the direct current component, a formula for calculating the non-periodic component Idc of the short-circuit current by adopting an equivalent frequency method is given in the short-circuit current calculation of a three-phase alternating current system (GB/T15544.1-2013).
At present, a method for calculating a short-circuit current provided by a new energy plant or flexible direct-current transmission generally needs to perform detailed electromagnetic transient modeling, only considers the short-circuit current injected by a body, is not organically combined with an equivalent voltage source calculation method recommended in the three-phase alternating-current system short-circuit current calculation (GB/T15544.1-2013), is not beneficial to quickly judging the boosting effect of a transformer substation in a power system, and is very complicated in planning, operation and engineering use. On the other hand, in general power grid planning operation, only the calculation of the alternating current component of the short-circuit current is considered, and in national standards, only the calculation method of the non-periodic component of the short-circuit current is provided, but the calculation method cannot be considered with the alternating current, namely the periodic component, to guide and judge whether the comprehensive breaking capacity of the circuit breaker meets the requirement.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for checking the on-off capacity of a breaker of a power grid bus, which comprehensively considers the influence of various factors on short-circuit current under a novel power system, superposes the short-circuit current provided by a new energy power station and flexible direct-current transmission on the alternating-current short-circuit current of a traditional network, so that the obtained short-circuit current is more real and accurate, and attenuates the on-off capacity of the breaker by using the attenuation time constant of the direct-current component of the short-circuit current of a fault bus, so that the on-off capacity of the breaker is more real and accurate, and whether the on-off capacity of the breaker meets the requirements or not can be more accurately judged.
The technical scheme adopted by the invention is as follows:
a method for verifying the breaking capacity of a breaker of a power grid bus comprises the following steps: calculating the basic short-circuit current of a fault bus of a power grid without a new energy power station and flexible direct current; calculating a short-circuit current direct-current component attenuation time constant of the fault bus, and calculating the alternating-current short-circuit on-off capacity of the breaker after the direct-current component is considered according to the short-circuit current direct-current component attenuation time constant of the fault bus and the shortest on-off time of the breaker of the fault bus; calculating short-circuit current provided by a new energy power station in the power grid; calculating short-circuit current provided by flexible direct current in the power grid; and judging whether the on-off capability of the breaker meets the requirements or not according to the AC short-circuit on-off capability of the breaker after the DC component is considered, the basic short-circuit current, the short-circuit current provided by the new energy power station in the power grid and the short-circuit current provided by the flexible DC in the power grid.
Calculating the AC short circuit breaking capacity of the breaker after considering the DC component according to the following formula:
wherein S isfRFor the AC short-circuit breaking capability of the circuit breaker after taking into account the DC component, SfNRated breaking capacity, t, of the circuit breakerminIs the minimum breaking time, T, of the circuit breakerdcf.RDecay time constant, T, of short-circuit current DC component of said faulty busdcf.NA decay time constant for a rated dc component of the circuit breaker.
Calculating short-circuit current provided by a new energy power station in the power grid, and specifically comprising the following steps: judging whether each new energy power station is connected to a main power grid through boosting; if a certain new energy power station is connected to a main power grid through boosting, the preset injection current is used as the short-circuit current provided by the new energy power station; if a new energy power station is not connected into a main power grid through boosting, calculating the maximum short-circuit current of the new energy power station at the action moment of the circuit breaker, calculating the impedance between the new energy power station and a short-circuit point and the system impedance of the short-circuit point, and calculating the short-circuit current provided by the new energy power station according to the maximum short-circuit current of the new energy power station at the action moment of the circuit breaker, the impedance between the new energy power station and the short-circuit point and the system impedance of the short-circuit point; and accumulating the short-circuit current provided by all the new energy power stations in the power grid.
If a new energy power station is connected to the main power grid through boosting, the short-circuit current provided by the new energy power station is as follows:
wherein, IREiRepresents the short-circuit current, U, provided by the ith new energy power stationiIs the bus voltage value of the ith new energy power station, INiThe rated current of the ith new energy power station.
If a new energy power station is not connected to the main power grid through boosting, the short-circuit current provided by the new energy power station is as follows:
IREi＝IREi,max×Xsysi/(Xsysi+Xfi)
wherein, IREi,maxThe maximum short-circuit current, X, of the ith new energy power station at the action moment of the circuit breakerfiIs the impedance between the ith new energy power station and the short-circuit point, XsysiAnd the system impedance is the system impedance of the short circuit point corresponding to the ith new energy power station.
Calculating short-circuit current provided by flexible direct current in the power grid, specifically comprising: calculating the maximum short-circuit current of each flexible direct current at the action moment of the circuit breaker; judging whether each flexible direct current generates reactive power during the fault period; if a certain flexible direct current generates reactive power in a fault period, calculating the impedance between the flexible direct current and a short-circuit point and the impedance of a short-circuit point system, and calculating the short-circuit current provided by the flexible direct current according to the maximum short-circuit current of the flexible direct current at the action moment of the circuit breaker, the impedance between the flexible direct current and the short-circuit point and the impedance of the short-circuit point system; and accumulating the short-circuit current provided by all the flexible direct currents in the power grid.
If a certain flexible direct current generates reactive power during a fault, the short-circuit current provided by the flexible direct current is as follows:
IVSCj＝IVSCj,max×Xsysj/(Xsysj+Xfj)
wherein, IVSCjDenotes the short-circuit current, X, supplied by the jth flexible DCfjIs the jth flexible straightImpedance between flow and short-circuit point, XsysjAnd the system impedance is the short-circuit point corresponding to the jth flexible direct current.
Judging whether the on-off capability of the breaker meets the requirements or not according to the alternating-current short-circuit on-off capability of the breaker after considering the direct-current component, the basic short-circuit current, the short-circuit current provided by the new energy power station in the power grid and the short-circuit current provided by the flexible direct current in the power grid, and specifically comprising the following steps: judging whether S existsRf＞If0+∑IREi+∑IVSCjWherein, If0For the basic short-circuit current, ∑ IREiAccumulated value, sigma I, of short-circuit current provided by all new energy power stations in the power gridVSCjThe accumulated value of the short-circuit current provided for all the flexible direct currents in the power grid; if so, the breaking capacity of the circuit breaker meets the requirement, otherwise, the breaking capacity of the circuit breaker does not meet the requirement.
The invention has the beneficial effects that:
the invention calculates the attenuation time constant of the direct-current component of the short-circuit current of the fault bus, calculates the AC short-circuit breaking capacity of the breaker after considering the direct-current component based on the attenuation time constant, calculates the short-circuit current provided by the new energy power station and the short-circuit current provided by the flexible direct current in the power grid, and judges whether the breaking capacity of the breaker of the fault bus meets the requirement or not based on the short-circuit current and the AC short-circuit breaking capacity of the breaker after considering the direct-current component based on the attenuation time constant of the direct-current component of the short-circuit current, thereby comprehensively considering the influence of various factors under the novel power system on the short-circuit current and superposing the short-circuit current provided by the new energy power station and the flexible direct-current transmission on the AC short-circuit current of the traditional network to ensure that the obtained short-circuit current is more real and accurate and attenuate the breaking capacity of the breaker by the attenuation time constant of the direct-current component of the short-circuit current of the fault bus, the obtained breaking capacity of the circuit breaker is more real and accurate, and whether the breaking capacity of the circuit breaker meets requirements or not can be judged more accurately.
Drawings
Fig. 1 is a flowchart of a method for verifying the breaking capability of a circuit breaker of a power grid bus according to an embodiment of the present invention;
fig. 2 is a flowchart of a method for verifying the breaking capability of a circuit breaker of a power grid bus according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a power grid structure according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, the method for verifying the breaking capability of the circuit breaker of the power grid bus according to the embodiment of the present invention includes the following steps:
and S1, calculating the basic short-circuit current of the fault bus of the power grid without the new energy power station and the flexible direct current.
In the embodiment of the invention, the new energy power station can be a wind power station or a photovoltaic power station and the like. When a certain bus of a power grid has a fault, the basic short-circuit current I of the fault bus f under the condition that the new energy power station and the flexible direct current conversion station are not included can be calculated firstlyf0。
And S2, calculating the attenuation time constant of the short-circuit current direct-current component of the fault bus, and calculating the alternating-current short-circuit breaking capacity of the breaker after considering the direct-current component according to the attenuation time constant of the short-circuit current direct-current component of the fault bus and the shortest breaking time of the breaker of the fault bus.
In one embodiment of the present invention, the ac short circuit breaking capability of the circuit breaker after considering the dc component can be calculated according to the following formula:
wherein S isfRFor the purpose of considering the AC short-circuit breaking capacity of the circuit breaker after the DC component, SfNRated breaking capacity, t, of the circuit breakerminFor the minimum breaking time, T, of the circuit breakerdcf.RDecay time constant, T, of short-circuit current DC component for faulty busdcf.NIs the rated dc component decay time constant of the circuit breaker.
And S3, calculating the short-circuit current provided by the new energy power station in the power grid.
Specifically, it may be determined first whether each new energy power station is connected to the main grid via boosting, for example, whether each new energy power station is connected to the main grid via boosting to a voltage level of 500kV (750kV) by a 220kV (330kV) photovoltaic power generation collection system.
If a new energy power station is connected to the main power grid through boosting, the preset injection current is used as the short-circuit current provided by the new energy power station. In an embodiment of the present invention, the preset injection current, that is, the short-circuit current provided by the new energy power station connected to the main power grid via boosting is:
wherein, IREiRepresents the short-circuit current, U, provided by the ith new energy power stationiIs the bus voltage value of the ith new energy power station, INiThe rated current of the ith new energy power station.
If a new energy power station is not connected to a main power grid through boosting, calculating the maximum short-circuit current of the new energy power station at the action moment of a circuit breaker, calculating the impedance between the new energy power station and a short-circuit point and the system impedance of the short-circuit point, and calculating the short-circuit current provided by the new energy power station according to the maximum short-circuit current of the new energy power station at the action moment of the circuit breaker, the impedance between the new energy power station and the short-circuit point and the system impedance of the short-circuit point. In one embodiment of the invention, the maximum short-circuit current of the new energy power station at the action moment of the circuit breaker is generally the maximum working current of the new energy power station rated full-power normal operation multiplied by an overload coefficient of 1.1-1.2 times. The short-circuit current provided by the new energy power station which is not connected into the main power grid through boosting is as follows:
IREi＝IREi,max×Xsysi/(Xsysi+Xfi)
wherein, IREi,maxThe maximum short-circuit current X of the ith new energy power station at the action moment of the circuit breakerfiIs the impedance between the ith new energy power station and the short-circuit point, XsysiAnd the system impedance is the system impedance of the short circuit point corresponding to the ith new energy power station.
And finally accumulating the short-circuit currents provided by all the new energy power stations in the power grid to obtain the short-circuit current sigma I provided by the new energy power station in the power gridREi。
And S4, calculating the short-circuit current provided by the flexible direct current in the power grid.
Specifically, the maximum short-circuit current of each flexible direct current at the action moment of the circuit breaker can be calculated, and in one embodiment of the invention, the maximum short-circuit current of the flexible direct current at the action moment of the circuit breaker is generally the maximum working current of the normal operation of the rated full power of the flexible direct current multiplied by an overload coefficient of 1.1-1.2 times.
Then, it is determined whether each of the flexible direct currents emits reactive power during the fault. If a certain flexible direct current does not generate reactive power during the fault, the increment of the flexible direct current to the system short-circuit current does not need to be considered. If a certain flexible direct current generates reactive power in a fault period, calculating the impedance between the flexible direct current and a short-circuit point and the impedance of a short-circuit point system, and calculating the short-circuit current provided by the flexible direct current according to the maximum short-circuit current of the flexible direct current at the action moment of the breaker, the impedance between the flexible direct current and the short-circuit point and the impedance of the short-circuit point system. The short-circuit current provided by the reactive flexible direct current during the fault is:
IVSCj＝IVSCj,max×Xsysj/(Xsysj+Xfj)
wherein, IVSCjDenotes the short-circuit current, X, supplied by the jth flexible DCfjIs the impedance between the jth flexible DC and the short-circuit point, XsysjAnd the system impedance is the short-circuit point corresponding to the jth flexible direct current.
Finally, all the flexibilities in the power gridShort-circuit current provided by the direct current is accumulated to obtain short-circuit current sigma I provided by the flexible direct current in the power gridVSCj。
And S5, judging whether the on-off capability of the breaker meets the requirements or not according to the AC short-circuit on-off capability of the breaker after considering the DC component, the basic short-circuit current, the short-circuit current provided by the new energy power station in the power grid and the short-circuit current provided by the flexible DC in the power grid.
It should be understood that the short-circuit current provided by the new energy power station and the short-circuit current provided by the flexible direct current are superposed with the basic short-circuit current to form a total short-circuit current. Therefore, whether the breaking capacity of the breaker meets the requirement can be judged by comparing the alternating current short-circuit breaking capacity of the breaker after considering the direct current component with the total short-circuit current.
Specifically, it can be judged whether or not S is presentRf＞If0+∑IREi+∑IVSCjWherein, If0Based on short-circuit current, ∑ IREiAccumulated value of short-circuit current, sigma I, provided by all new energy power stations in the power gridVSCjThe accumulated value of short-circuit current provided for all flexible direct currents in the power grid; if so, the breaking capacity of the circuit breaker meets the requirement, otherwise, the breaking capacity of the circuit breaker does not meet the requirement.
In an embodiment of the present invention, a specific flow of the method for verifying the breaking capability of the circuit breaker of the grid bus is shown in fig. 2.
According to the method for verifying the on-off capacity of the circuit breaker of the power grid bus, disclosed by the embodiment of the invention, the on-off capacity of the circuit breaker of the fault bus is verified by calculating the attenuation time constant of the direct-current component of the short-circuit current of the fault bus, calculating the alternating-current short-circuit on-off capacity of the circuit breaker after considering the direct-current component based on the attenuation time constant of the direct-current component of the short-circuit current of the circuit breaker, calculating the short-circuit current provided by a new energy power station and the short-circuit current provided by flexible direct current in the power grid, and judging whether the on-off capacity of the circuit breaker of the fault bus meets the requirement or not based on the short-circuit current and the alternating-current short-circuit on-off capacity of the circuit breaker after considering the direct-current component based on the basic short-circuit current and the alternating-current short-circuit on-off capacity of the circuit breaker after considering the direct-current component, so that the short-circuit current power supply of the new energy power station and the flexible direct-current transmission are superposed on the alternating-circuit short-circuit current on-circuit capacity of the traditional network, so that the obtained short-circuit bus is more real and accurate, the obtained breaking capacity of the circuit breaker is more real and accurate, and whether the breaking capacity of the circuit breaker meets requirements or not can be judged more accurately.
In an embodiment of the present invention, a local power grid (voltage class 750kV/330kV) in a certain area shown in fig. 3 is taken as an example, a flexible direct-current basic three-phase short-circuit current I without a new energy power stationf055.0kA, the faulty busbar is a 330kV busbar of a 750kV substation S1. Calculating the attenuation time constant T of the short-circuit current DC component of the fault busdcf.R151.7 ms. Minimum breaking time t of circuit breakermin40ms, circuit breaker rated DC component decay time constant Tdcf.NRated breaking capacity S of the circuit breaker for the faulty busbar f, 45msfNThe calculated breaking capacity S of the breaker after considering the direct current component is 63kAfR＝49.4kA。
In the area, 1 new energy power station is connected to a transformer substation S1-5 through a 110kV voltage class, and short-circuit current sigma I provided by the new energy power station is calculatedREi＝IREi0.2 kA. In the area, 1 flexible direct current converter station is connected to the 330kV side of the substation S1 in total, reactive power is considered to be generated in the fault period, and short-circuit current sigma I provided by flexible direct current is calculatedVSCj＝IVSCj3.2 kA. Final comparison SRf49.4kA and If0+∑ IREi+∑IVSCj58.4kA, the latter being large, the breaker breaking capability of the faulty busbar is not satisfactory.
In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (8)
1. The method for verifying the breaking capacity of the breaker of the power grid bus is characterized by comprising the following steps of:
calculating the basic short-circuit current of a fault bus of a power grid without a new energy power station and flexible direct current;
calculating a short-circuit current direct-current component attenuation time constant of the fault bus, and calculating the alternating-current short-circuit on-off capacity of the breaker after the direct-current component is considered according to the short-circuit current direct-current component attenuation time constant of the fault bus and the shortest on-off time of the breaker of the fault bus;
calculating short-circuit current provided by a new energy power station in the power grid;
calculating short-circuit current provided by flexible direct current in the power grid;
and judging whether the on-off capability of the breaker meets the requirements or not according to the AC short-circuit on-off capability of the breaker after the DC component is considered, the basic short-circuit current, the short-circuit current provided by the new energy power station in the power grid and the short-circuit current provided by the flexible DC in the power grid.
2. The method for verifying the breaking capability of the circuit breaker of the power grid bus according to claim 1, wherein the alternating-current short circuit breaking capability of the circuit breaker after considering the direct-current component is calculated according to the following formula:
wherein S isfRFor the AC short-circuit breaking capability of the circuit breaker after taking into account the DC component, SfNRated breaking capacity, t, of the circuit breakerminIs the minimum breaking time, T, of the circuit breakerdcf.RDecay time constant, T, of short-circuit current DC component of said faulty busdcf.NA decay time constant for a rated dc component of the circuit breaker.
3. The method for verifying the breaking capability of the circuit breaker of the power grid bus according to claim 2, wherein calculating the short-circuit current provided by the new energy power station in the power grid specifically comprises:
judging whether each new energy power station is connected to a main power grid through boosting;
if a certain new energy power station is connected to a main power grid through boosting, the preset injection current is used as the short-circuit current provided by the new energy power station;
if a new energy power station is not connected into a main power grid through boosting, calculating the maximum short-circuit current of the new energy power station at the action moment of the circuit breaker, calculating the impedance between the new energy power station and a short-circuit point and the system impedance of the short-circuit point, and calculating the short-circuit current provided by the new energy power station according to the maximum short-circuit current of the new energy power station at the action moment of the circuit breaker, the impedance between the new energy power station and the short-circuit point and the system impedance of the short-circuit point;
and accumulating the short-circuit current provided by all the new energy power stations in the power grid.
4. The method for verifying the breaking capability of the circuit breaker of the power grid bus as claimed in claim 3, wherein if a new energy power station is connected to the main power grid through boosting, the short-circuit current provided by the new energy power station is:
wherein, IREiRepresents the short-circuit current, U, provided by the ith new energy power stationiIs the bus voltage value of the ith new energy power station, INiThe rated current of the ith new energy power station.
5. The method for verifying the breaking capability of the circuit breaker of the power grid bus as claimed in claim 4, wherein if a new energy power station is not connected to the main power grid via boosting, the short-circuit current provided by the new energy power station is:
IREi＝IREi,max×Xsysi/(Xsysi+Xfi)
wherein, IREi,maxThe maximum short-circuit current, X, of the ith new energy power station at the action moment of the circuit breakerfiIs the impedance between the ith new energy power station and the short-circuit point, XsysiIs the ith new energyAnd the system impedance of the short circuit point corresponding to the power station.
6. The method for verifying the breaking capability of the circuit breaker of the grid bus according to claim 5, wherein calculating the short-circuit current provided by the flexible direct current in the grid specifically comprises:
calculating the maximum short-circuit current of each flexible direct current at the action moment of the circuit breaker;
judging whether each flexible direct current generates reactive power during a fault period;
if a certain flexible direct current generates reactive power in a fault period, calculating the impedance between the flexible direct current and a short-circuit point and the impedance of a short-circuit point system, and calculating the short-circuit current provided by the flexible direct current according to the maximum short-circuit current of the flexible direct current at the action moment of the circuit breaker, the impedance between the flexible direct current and the short-circuit point and the impedance of the short-circuit point system;
and accumulating the short-circuit current provided by all the flexible direct currents in the power grid.
7. The method for verifying the breaking capability of the circuit breaker of the grid bus according to claim 6, wherein if a certain flexible direct current generates reactive power during a fault, the short-circuit current provided by the flexible direct current is as follows:
IVSCj＝IVSCj,max×Xsysj/(Xsysj+Xfj)
wherein, IVSCjDenotes the short-circuit current, X, supplied by the jth flexible DCfjIs the impedance between the jth flexible DC and the short-circuit point, XsysjAnd the system impedance is the short-circuit point corresponding to the jth flexible direct current.
8. The method for verifying the on-off capability of the circuit breaker of the power grid bus according to claim 7, wherein the step of judging whether the on-off capability of the circuit breaker meets the requirement according to the ac short-circuit on-off capability of the circuit breaker after considering the dc component, the basic short-circuit current, the short-circuit current provided by the new energy power station in the power grid, and the short-circuit current provided by the flexible dc in the power grid specifically comprises the steps of:
judging whether S existsRf＞If0+∑IREi+∑IVSCjWherein, If0For the basic short-circuit current, ∑ IREiAccumulated value, sigma I, of short-circuit current provided by all new energy power stations in the power gridVSCjThe accumulated value of the short-circuit current provided for all the flexible direct currents in the power grid;
if so, the breaking capacity of the circuit breaker meets the requirement, otherwise, the breaking capacity of the circuit breaker does not meet the requirement.
Priority Applications (1)
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| CN114779069A (en) * | 2022-06-21 | 2022-07-22 | 国网江西省电力有限公司电力科学研究院 | Method and system for checking breaker short-circuit current direct-current component breaking capacity |
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| CN114779069A (en) * | 2022-06-21 | 2022-07-22 | 国网江西省电力有限公司电力科学研究院 | Method and system for checking breaker short-circuit current direct-current component breaking capacity |
| CN114779069B (en) * | 2022-06-21 | 2022-10-11 | 国网江西省电力有限公司电力科学研究院 | Method and system for checking breaker short-circuit current direct-current component breaking capacity |
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