CN116679108A - Method, device and storage medium for monitoring short-circuit current of power system - Google Patents

Abstract

The application provides a method, a device and a storage medium for monitoring short-circuit current of a power system, wherein the method comprises the following steps: acquiring voltage values at all monitoring points in the power system, wherein each monitoring point corresponds to a uniquely determined monitoring number; obtaining a voltage change proportion at each monitoring point at the current moment according to the voltage values obtained in the last two times every time, judging whether at least one voltage change proportion exceeds a preset change proportion, and if so, obtaining a change monitoring number corresponding to the monitoring point with the voltage change proportion exceeding the preset change proportion; obtaining a reference monitoring number corresponding to the maximum voltage change proportion from all the change monitoring numbers, and obtaining an associated monitoring number related to the reference monitoring number according to the reference monitoring number; and acquiring a sub-power system model formed by the reference monitoring number and the associated monitoring number, and acquiring short-circuit current by using the sub-power system model. The application can improve the efficiency of monitoring the short-circuit current of the power system.

Description

Method, device and storage medium for monitoring short-circuit current of power system

Technical Field

The present application relates to the field of power system analysis technologies, and in particular, to a method, an apparatus, and a storage medium for monitoring short-circuit current of a power system.

Background

The short circuit fault can destroy the normal operation of the power system, and the main hazards comprise that currents which are many times higher than normal values exist in branches near the fault point, and in consideration of the electrodynamic effect of the currents, great mechanical stress is generated between conductors, so that the fault is further developed into an accident; for longer short-circuit durations, the device may be damaged by heat; the system voltage is greatly reduced during short circuit, so that a user with high power quality requirements can be greatly influenced, and even load low-voltage tripping and the like can be caused. When the short-circuit current is detected to be abnormal, the power system can make corresponding actions in time to protect equipment and circuits in the power system. Therefore, in order to reduce the damage caused by the occurrence of the fault, it is necessary to monitor the short-circuit current in the power system.

Currently, in the prior art, the voltage variation and the power variation of a bus at an nth sampling time point are determined by measuring the voltage vector and the power of the lower network at the nth sampling time point of the bus to be monitored and the voltage vector and the power of the lower network at an (n+1) th sampling time point, so that the short-circuit current of the bus at the nth sampling time point is calculated according to the voltage variation and the power variation. Therefore, although the short-circuit current can be determined by only collecting the voltage vector and the off-grid power in the local information of the bus to be monitored, the short-circuit current calculation is not needed on the basis of global information such as power flow of the power system and system parameters.

However, the bus in the power system is only located between the connection of the voltage distribution devices at each level in the substation, and between the connection of the electrical equipment such as the transformer and the corresponding distribution devices, and the transmission line is adopted in the long-distance power transmission process. There is a possibility that a short circuit occurs in either the bus bars or the power lines in the power system. Therefore, when the power system is short-circuited, the actual short-circuit current generated at the position where the short circuit occurs cannot be accurately represented only by calculating the short-circuit current of the bus.

Disclosure of Invention

In order to improve the efficiency of monitoring the short-circuit current of a power system, the embodiment of the application provides a method, a device and a storage medium for monitoring the short-circuit current of the power system.

In a first aspect, the present embodiment provides a method for monitoring a short-circuit current of a power system, the method including:

acquiring voltage values at all monitoring points in the power system, wherein each monitoring point corresponds to a uniquely determined monitoring number;

obtaining a voltage change proportion at each monitoring point at the current moment according to the voltage values obtained in the last two times every time, judging whether at least one voltage change proportion exceeds a preset change proportion, and if yes, obtaining a change monitoring number corresponding to the monitoring point with the voltage change proportion exceeding the preset change proportion;

Obtaining a reference monitoring number corresponding to the maximum voltage change proportion from all the change monitoring numbers, and obtaining an associated monitoring number related to the reference monitoring number according to the reference monitoring number;

and acquiring a sub-power system model formed by the reference monitoring number and the associated monitoring number from a preset power system model, and acquiring short-circuit current generated by short-circuit by using the sub-power system model.

In some of these embodiments, obtaining an associated monitoring number from the reference monitoring number that relates to the reference monitoring number comprises:

obtaining a reference monitoring point corresponding to the reference monitoring number, obtaining an associated monitoring point positioned at a higher stage and/or an associated monitoring point positioned at a lower stage of the reference monitoring point according to a preset power system model, and determining the monitoring number corresponding to the associated monitoring point as an associated monitoring number related to the reference monitoring number.

In some of these embodiments, obtaining a short circuit current generated by the occurrence of a short circuit using the sub-power system model includes:

obtaining a sub-tide flow calculation formula corresponding to the sub-power system model and related to solving current according to the connection relation and the impedance information in the sub-power system model;

Acquiring known parameters required by the sub-tidal current calculation formula, and substituting the known parameters into the sub-tidal current calculation formula to obtain a current value on each branch in the sub-electric power model;

obtaining current difference values between any two current values in the current values according to the current values, judging whether the values of all the current difference values do not exceed a preset current difference value, and if not, adding all the current values to obtain short-circuit current generated by short-circuit;

and if at least one of the two current values exceeds the preset current difference value, determining the current value with the large value in the two current values corresponding to the preset current difference value as a short-circuit current generated by short-circuit.

In some of these embodiments, obtaining a short circuit current generated by the occurrence of a short circuit using the sub-power system model further comprises:

obtaining the upper and lower relation between each associated monitoring number and the reference monitoring number in the sub-power system model according to the connection relation in the sub-power system model;

acquiring an associated voltage value and an associated power value at each associated monitoring number in a sub-power system model, and a reference voltage value and a reference power value at each reference monitoring number, and sequentially acquiring a power difference value between each associated power value and the reference power value and a voltage difference value between each associated voltage value and the reference voltage value from an upper level to a lower level based on the upper-lower level relation, wherein each power difference value corresponds to a uniquely determined voltage difference value;

Obtaining a current value according to each voltage difference value and a corresponding power difference value, obtaining a current difference value between any two current values in the current values according to the current values, judging whether the values of all the current difference values do not exceed a preset current difference value, and if so, adding all the current values to obtain a short-circuit current generated by short-circuit;

and if at least one of the two current values exceeds the preset current difference value, determining the current value with the larger value in the two current values corresponding to the exceeding preset current difference value as a short-circuit current generated by short-circuit.

In some embodiments, the obtaining, according to a preset power system model, the associated monitoring point located at a level above the reference monitoring point and/or the associated monitoring point located at a level below the reference monitoring point includes:

judging whether the numerical value of the reference monitoring number is minimum in all the monitoring numbers, if so, acquiring an associated monitoring point positioned at the next stage of the reference monitoring point according to a connection relation in a preset power system model;

if not, judging whether the numerical value of the reference monitoring number is maximum in all the monitoring numbers, and if so, acquiring an associated monitoring point positioned at the upper stage of the reference monitoring point according to the connection relation in a preset power system model;

And if the relation is neither the maximum or the minimum, acquiring the associated monitoring point positioned at the upper stage of the reference monitoring point and the associated monitoring point positioned at the lower stage according to the connection relation in the preset power system model.

In some of these embodiments, the method further comprises:

and if all the voltage change ratios do not exceed the preset change ratio, continuing to wait for obtaining the voltage values at all monitoring points in the power system.

In some embodiments, the sub-power system model is used to obtain a short-circuit current generated by the short-circuit, and then the alarm signal corresponding to the reference monitoring number one to one is generated.

In a second aspect, the present embodiment provides an apparatus for monitoring short-circuit current of a power system, the apparatus comprising: the device comprises a voltage acquisition module, a processing module, an association acquisition module and a monitoring module; wherein, the liquid crystal display device comprises a liquid crystal display device,

the voltage acquisition module is used for acquiring voltage values at all monitoring points in the power system, wherein each monitoring point corresponds to a uniquely determined monitoring number;

the processing module is used for obtaining a voltage change value at each monitoring point at the current moment according to the voltage values obtained in the last two times every time, judging whether at least one voltage change value exceeds a preset change value, and if yes, obtaining a change monitoring number corresponding to the monitoring point with the voltage change value exceeding the preset change value;

The association acquisition module is used for acquiring a reference monitoring number corresponding to the maximum voltage change value from all the change monitoring numbers, and acquiring an association monitoring number related to the reference monitoring number according to the reference monitoring number;

the monitoring module is used for acquiring a sub-power system model formed by the reference monitoring number and the associated monitoring number from a preset power system model, and obtaining short-circuit current generated by short circuit by using the sub-power system model.

In some of these embodiments, the apparatus further comprises an alarm module; wherein, the liquid crystal display device comprises a liquid crystal display device,

the alarm module is used for obtaining short-circuit current generated by short-circuit by using the sub-power system model and then generating alarm signals corresponding to the reference monitoring numbers one by one.

In a third aspect, the present embodiment provides a computer readable storage medium having stored thereon a computer program executable on a processor, the computer program implementing a method of monitoring short circuit current of an electrical power system as described in the first aspect when executed by the processor.

By adopting the method, the voltage change proportion of each monitoring point at the current moment is obtained by acquiring the voltage values of all the monitoring points in the power system and according to the voltage values acquired by each monitoring point twice recently; and comparing the voltage change proportion with a preset change proportion, if at least one voltage change proportion exceeds the preset proportion, indicating that the power system has a short circuit, and continuously acquiring a change monitoring number corresponding to a monitoring point with the voltage change proportion exceeding the preset change proportion. And continuously obtaining a reference monitoring number corresponding to the maximum voltage change proportion according to all the change monitoring numbers, wherein the position corresponding to the reference monitoring number is near the position of the short circuit of the power system, so that an associated monitoring number related to the reference monitoring number is obtained according to the reference monitoring number, a sub power system model formed by the reference monitoring number and the associated monitoring number is obtained from a preset power system model, and the short circuit current generated by the short circuit is obtained by using the sub power system model. Compared with a preset power system model, the sub-power system model is simpler, so that the short-circuit current generated by short-circuit is monitored by using the simpler sub-power system model, and the short-circuit current of the power system can be monitored more quickly and efficiently.

Drawings

Fig. 1 is a block diagram of a method for monitoring short-circuit current of a power system according to an embodiment of the present application.

Fig. 2 is a schematic diagram of monitoring numbers corresponding to all monitoring points in the power system according to the embodiment of the present application.

Fig. 3 is a block diagram of obtaining an associated monitoring point located at a higher level and/or an associated monitoring point located at a lower level above a reference monitoring point according to a preset power system model according to an embodiment of the present application.

Fig. 4 is a block diagram of a short circuit current generated by using a sub-power system model to obtain a short circuit according to an embodiment of the present application.

Fig. 5 is a block diagram of a short circuit current generated by using a sub-power system model to obtain a short circuit according to another embodiment of the present application.

Fig. 6 is a block diagram of an apparatus for monitoring short-circuit current of a power system according to an embodiment of the present application.

Detailed Description

The present application will be described and illustrated with reference to the accompanying drawings and examples for a clearer understanding of the objects, technical solutions and advantages of the present application. However, it will be apparent to one of ordinary skill in the art that the present application may be practiced without these specific details. It will be apparent to those having ordinary skill in the art that various changes can be made to the disclosed embodiments of the application and that the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the application. Thus, the present application is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the scope of the application as claimed.

Embodiments of the application are described in further detail below with reference to the drawings.

The power system is an electric energy production and consumption system which is composed of links such as a power plant, a power transmission and transformation circuit, a power supply and distribution station, electricity consumption and the like. The system has the functions of converting primary energy in nature into electric energy through a power generation power device, and supplying the electric energy to each user through power transmission, transformation and distribution.

A short circuit refers to a situation in which two points of different potential in a normal circuit are incorrectly directly touched or turned on by a conductor of very small impedance (or resistance). Short circuit current is the current that flows when an abnormal connection (i.e., a short circuit) occurs between phases or between phases and ground (or neutral) in operation of the power system. The value may be much greater than the rated current and depends on the electrical distance of the short-circuit point from the power supply.

Fig. 1 is a block diagram of a method for monitoring short-circuit current of a power system according to an embodiment of the present application. As shown in fig. 1, a method for monitoring short-circuit current of an electric power system includes the following steps:

step S100, voltage values at all monitoring points in the power system are obtained, wherein each monitoring point corresponds to a uniquely determined monitoring number.

The power system sequentially passes through a power plant link, a transmission line link, a power supply and distribution station link and a power utilization link to transmit electric energy generated by the power plant to users through various carriers capable of carrying electric quantity, wherein the carriers comprise, but are not limited to, transmission lines, buses and the like. The electric quantity transmission path from the beginning power plant link to the last user power utilization link of the power system needs to be split and collected for a plurality of times, so that each split or collection can form a corresponding node, and each node is a monitoring point in the power system.

Sequentially numbering each node from small to large according to the sequence from a power plant link to an electricity utilization link of the power system, so that each monitoring point corresponds to a uniquely determined monitoring number; or sequentially numbering each link from large to small according to the sequence from the power plant link to the power utilization link of the power system, so that each monitoring point corresponds to a uniquely determined monitoring number. Only the monitoring numbers corresponding to all monitoring points in the power system are required to be different, namely each monitoring point corresponds to a uniquely determined monitoring number. According to the application, each node is numbered in sequence from small to large according to the sequence from the power plant link to the power utilization link of the power system, so that each monitoring point corresponds to a uniquely determined monitoring number.

Fig. 2 is a schematic diagram of monitoring numbers corresponding to all monitoring points in the power system according to the embodiment of the present application. As shown in fig. 2, in the power system, the monitoring points are sequentially numbered from small to large in the order from the power plant link to the user power consumption link. When at least two nodes are obtained through shunting, the positions of people are used as reference points, and the monitoring numbers corresponding to the nodes are obtained by numbering in sequence from far to near; when a node is obtained after the shunting, adding an operation to obtain a monitoring number corresponding to the node obtained after the shunting on the basis of the largest monitoring number obtained by the shunting before; when a plurality of nodes are obtained through shunting after shunting, the position of a person is still taken as a reference point, the largest monitoring number obtained through shunting in the front is taken as the basis, and the monitoring numbers corresponding to each node are obtained through numbering in sequence from far to near.

The voltage values at each monitoring point in the power system may be measured simultaneously using the WAMS system or other measurement system to obtain the voltage values at all monitoring points in the power system. The time interval for acquiring the voltage values at all monitoring points in the power system in two adjacent times can be determined directly according to the measurement frequency of the WAMS system or other measurement systems. Therefore, the voltage values at all monitoring points in the power system can be obtained in time, and the condition that the voltage values are obtained by leakage is reduced.

In addition, the time interval for acquiring the voltage values at all monitoring points in the power system in two adjacent times can be determined according to the measurement frequency of the WAMS system or other measurement systems and the time required for completing one short-circuit current. The method comprises the steps of determining the shortest time interval allowed by a WAMS system or other monitoring systems in theory for acquiring voltage values every time according to the measurement frequency, and taking the maximum value of the shortest time interval and the time required for completing monitoring of a short-circuit current as the time interval for acquiring the voltage values at all monitoring points in the power system in two adjacent times. Therefore, when the shortest time interval is smaller than the time required for completing monitoring of the primary short-circuit current, the time required for completing monitoring of the primary short-circuit current is determined as the time interval for determining the voltage values at all monitoring points in the adjacent two-time acquisition power system, so that the acquired voltage values can be timely utilized to determine the short-circuit current generated by the short circuit, and the situation that the acquired voltage values cannot be timely calculated because the time interval for acquiring the voltage values is smaller than the time interval for calculating the short-circuit current can be reduced. The embodiment of the application preferably determines the time interval for acquiring the voltage values at all monitoring points in the power system in two adjacent times directly according to the measurement frequency of the WAMS system or other measurement systems.

Step S200, each time a voltage value is obtained, the voltage change proportion at each monitoring point at the current moment is obtained according to the voltage values obtained in the last two times, whether at least one voltage change proportion exceeds a preset change proportion is judged, and if yes, a change monitoring number corresponding to the monitoring point with the voltage change proportion exceeding the preset change proportion is obtained.

And storing the acquired voltage values at all monitoring points in the power system every time the voltage values at all monitoring points in the power system are acquired, so that the voltage values at all monitoring points in the power system acquired every time can be obtained. Because each monitoring point corresponds to a uniquely determined monitoring number and each voltage value corresponds to a uniquely determined monitoring point, each voltage value also corresponds to a uniquely determined monitoring number. The last acquired voltage value of the same monitoring number is subtracted by the last acquired voltage value of the last but one time, so that the voltage change value at the monitoring point corresponding to the monitoring number can be obtained, the voltage change value is divided by the last but one acquired voltage value to obtain the voltage change proportion at the monitoring point corresponding to the monitoring number, the last but one acquired voltage value of the monitoring number is subtracted by the last but one acquired voltage value of the last but one time of the monitoring number in sequence to obtain the voltage change value at the monitoring point corresponding to the other monitoring number, and then each voltage change value is divided by the last but one acquired voltage value of the monitoring number to obtain the voltage change proportion at the monitoring point corresponding to the other monitoring number, so that the voltage change value at the monitoring point at the current moment is obtained.

The voltage proportion at each node does not fluctuate too much during normal power delivery of the power system. The preset change proportion represents the maximum proportion of the normal change of the voltage proportion at all nodes when the electric power system normally transmits electric quantity, and the numerical value of the preset change proportion can be specifically determined according to actual conditions. And subtracting the preset change proportion from each voltage change proportion in sequence to obtain a corresponding number of proportion differences, if all the proportion differences are not larger than zero, all the voltage change proportions are not larger than the preset change proportion, which indicates that no short circuit occurs in the power system, and then continuously acquiring voltage values at all monitoring points in the waiting power system.

If at least one of the ratio differences is greater than zero, at least one of the voltage change ratios exceeds a preset change ratio, indicating that a short circuit occurs in the power system, and further monitoring of the short circuit current is required. And adding a first keyword to the monitoring number corresponding to the voltage change ratio exceeding the preset change ratio, so that the monitoring number added with the first keyword represents that the voltage change ratio corresponding to the monitoring number exceeds the preset change ratio. Therefore, the change monitoring numbers corresponding to the monitoring points with the voltage change proportion exceeding the preset change proportion can be obtained by checking whether each monitoring number has the first keyword.

Step S300, obtaining the reference monitoring number corresponding to the maximum voltage change proportion from all the change monitoring numbers, and obtaining the associated monitoring number related to the reference monitoring number according to the reference monitoring number.

And sequencing the voltage change ratios corresponding to all the change monitoring numbers according to the sequence from small to large or from large to small to obtain the maximum voltage change ratio and the monitoring number corresponding to the maximum voltage change ratio, and adding a second keyword into the monitoring number corresponding to the maximum voltage change ratio, so that the monitoring number added with the second keyword represents the reference monitoring number corresponding to the maximum voltage change ratio in all the change monitoring numbers. Because the voltage is greatly reduced due to the occurrence of the short circuit, the place with the largest voltage change proportion is the place where the short circuit occurs, and any place in the power system is likely to be short-circuited, so that the monitoring point corresponding to the reference monitoring number is the monitoring point closest to the short circuit.

The point of the short circuit of the power system may be located at the upper stage of the monitoring point corresponding to the reference monitoring number, or may be located at the lower stage of the monitoring point corresponding to the reference monitoring number. In order to monitor the short-circuit current more accurately, on the basis of the reference monitoring number, the associated monitoring number related to the reference monitoring number is also considered, and the short-circuit current is monitored through the monitoring point corresponding to the reference monitoring number and the monitoring point corresponding to the associated monitoring number.

Wherein obtaining the associated monitoring number related to the reference monitoring number according to the reference monitoring number comprises: obtaining a reference monitoring point corresponding to the reference monitoring number, obtaining an associated monitoring point positioned at a higher stage and/or an associated monitoring point positioned at a lower stage of the reference monitoring point according to a preset power system model, and determining the monitoring number corresponding to the associated monitoring point as an associated monitoring number related to the reference monitoring number.

Fig. 3 is a block diagram of obtaining an associated monitoring point located at a higher level and/or an associated monitoring point located at a lower level above a reference monitoring point according to a preset power system model according to an embodiment of the present application. As shown in fig. 3, obtaining the associated monitoring point at the upper stage and/or the associated monitoring point at the lower stage above the reference monitoring point according to the preset power system model includes the following steps:

step S201, judging whether the numerical value of the reference monitoring number in all the monitoring numbers is minimum, if so, obtaining the associated monitoring point positioned at the next stage of the reference monitoring point according to the connection relation in the preset power system model.

Step S202, if not, judging whether the numerical value of the reference monitoring number in all the monitoring numbers is maximum, and if so, obtaining the associated monitoring point positioned at the upper stage of the reference monitoring point according to the connection relation in the preset power system model.

And step S203, if the relationship is neither maximum nor minimum, obtaining the associated monitoring point of the upper stage and the associated monitoring point of the lower stage positioned above the reference monitoring point according to the connection relation in the preset power system model.

The preset power system mode refers to a power system model corresponding to the whole power system. After the power system is built, the preset power system model is determined. The preset power system model has corresponding input ends, output ends and internal connection relation. The power plant link is an input end, the user electricity consumption link is an output end, and the connection relationship between the power plant link and the user electricity consumption link is internal. The order from the input to the output is the order from the upper stage to the lower stage. If the numerical value of the reference monitoring number in all the monitoring numbers is minimum, the reference monitoring point corresponding to the reference monitoring number is the monitoring point of the power plant and is the input end of the preset power system model, at the moment, no associated monitoring point is positioned at the upper stage of the reference monitoring point, and only the associated monitoring point is positioned at the lower stage of the reference monitoring point. Similarly, if the numerical value of the reference monitoring number in all the monitoring numbers is the largest, the reference monitoring point corresponding to the reference monitoring number is the monitoring point of user power consumption, and is the output end of the preset power system model, at the moment, no associated monitoring point is located at the next stage of the reference monitoring point, and only the associated monitoring point is located at the previous stage of the reference monitoring point. If the numerical value of the reference monitoring number in all the monitoring numbers is neither maximum nor minimum, at the moment, the reference monitoring point is associated with the relevant monitoring point at the upper stage of the reference monitoring point, and the reference monitoring point is associated with the relevant monitoring point at the lower stage of the reference monitoring point.

The connection relationship indicates that each monitoring number is in direct level relationship with which monitoring numbers located at the upper level of the monitoring number, and each monitoring number is in direct level relationship with which monitoring numbers located at the lower level of the monitoring number. After the position relation between the associated monitoring point and the reference monitoring point is determined, the upper-stage associated monitoring number which belongs to the direct-stage relation in the upper stage with the reference monitoring number and the lower-stage associated monitoring number which belongs to the direct-stage relation in the lower stage with the reference monitoring number are determined through the connection relation. Then the associated monitoring point corresponding to the upper associated monitoring number is the associated monitoring point of the upper stage, and the associated monitoring point corresponding to the lower associated monitoring number is the associated monitoring point of the lower stage. If the numerical value of the reference monitoring number in all the monitoring numbers is minimum, the reference monitoring number is not associated with the upper-level monitoring number which belongs to the direct-level relation in the upper level; if the reference monitoring number is the largest in all the monitoring numbers, the reference monitoring number is not associated with the next stage of the direct stage relation in the next stage.

Step S400, a sub-power system model formed by the reference monitoring number and the associated monitoring number is obtained from a preset power system model, and short-circuit current generated by short-circuit is obtained by using the sub-power system model.

The preset power system model is specifically an equivalent circuit model obtained by equivalent of equipment or wires in the power system into corresponding impedance. And marking a monitoring number corresponding to each monitoring point in a preset power system model. All wires connected with the reference monitoring points corresponding to the reference monitoring numbers and the associated monitoring points corresponding to one associated monitoring number in the power system model form a sub-power system model, so that the sub-power system model formed by the reference monitoring numbers and the associated monitoring numbers is obtained. The sub-power system model is only a part of a preset power system model, and the connection relation among all monitoring points in the sub-power system model still keeps the connection relation in the preset power sub-system model. The sub-power system model comprising the short-circuit position is obtained from the preset power system model, and compared with the preset power system model, the sub-power system model is simpler, so that the short-circuit current generated by short-circuit is monitored by using the simpler sub-power system model, and the short-circuit current of the power system can be monitored more quickly and efficiently.

Fig. 4 is a block diagram of a short circuit current generated by using a sub-power system model to obtain a short circuit according to an embodiment of the present application. As shown in fig. 4, a method for obtaining a short-circuit current generated by a short-circuit using a sub-power system model includes the steps of:

Step S401, obtaining a sub-tidal current calculation formula corresponding to the sub-electric power system model and related to solving current according to the connection relation and the impedance information in the sub-electric power system model.

Step S402, obtaining known parameters required by the sub-tidal current calculation formula, and substituting the known parameters into the sub-tidal current calculation formula to obtain the current value of each branch in the sub-electric power model.

Step S403, obtaining the current difference value between any two current values in the current values according to the current values, judging whether the values of all the current difference values do not exceed the preset current difference value, and if not, adding all the current values to obtain the short-circuit current generated by short-circuit.

In step S404, if at least one of the two current values exceeds the preset current difference value, determining the current value with the larger value as the short-circuit current generated by the short-circuit.

The individual impedance information in the sub-power system model, and the connection relations in the sub-power system model, have been shown in the sub-power system model. Firstly, determining the topological structure of the sub-power system model, wherein the topological structure comprises connection relations of monitoring points, branches, equipment and the like. And then, for each monitoring point, listing equations such as kirchhoff current law, kirchhoff voltage law and the like based on the impedance information to form a sub-tidal current calculation formula for solving the current. Then according to the sub-tidal current calculation formula for solving the current, which known parameters are needed in addition to the current parameters are obtained, so that a WAMS system or other monitoring systems are used for monitoring the known parameters, and all the obtained known parameters at the same moment are substituted into the sub-tidal current calculation formula for solving the current. And finally, converting a sub-tidal current calculation formula for solving the current into a matrix form, and solving the current value on each branch in the sub-electric power system model by using a Gaussian-Jordan elimination method or LU decomposition method and the like.

As short circuits may occur on the main road in the sub-power system model, they may also occur on the branch road in the sub-power system model. If the main circuit is short-circuited, the current values of all the branches in the sub-power system model are expanded to the same extent, and the difference value of the current values of all the branches is not changed excessively. Therefore, by subtracting the current values on all the branches from each other and obtaining the absolute value, the current difference between any two current values in the current values on the branches can be obtained. The preset current difference represents the maximum value of the normal current differences among different branches in the sub-power system model, the specific value of the preset current difference can be determined according to actual conditions, and the preset current difference is not limited any further in the embodiment of the application. If the values of all the current differences do not exceed the preset current differences, which indicates that short circuit occurs on the main circuit in the sub-power system model, the short circuit current generated by the short circuit of the power system can be obtained by adding the current values of all the branches in the sub-power system model.

Similarly, if the value of at least one current difference exceeds the preset current difference, it indicates that a short circuit occurs on a certain branch in the sub-power system model, and the current on the branch is rapidly increased due to the occurrence of the short circuit, so that all the current values with larger values out of the two current values corresponding to the exceeding preset current difference are short circuit currents generated by the power system. In this way, compared with the method for determining the current calculation formula for solving the current by using the whole power system model of the power system, the method for solving the short-circuit by using the sub-tidal current calculation formula for solving the current in the power system model of the power system determines the approximate position of the short-circuit in the whole power system model, and splits the sub-power system model containing the position of the short-circuit from the whole power system model, so that the sub-tidal current calculation formula for solving the current is determined according to the sub-power system model, and is simpler than the current calculation formula, and after all, the current calculation formula for solving the current and the sub-tidal current calculation formula are nonlinear complex calculations, so that the short-circuit current of the power system can be monitored more efficiently by using the simpler sub-tidal current calculation formula.

Fig. 5 is a block diagram of a short circuit current generated by using a sub-power system model to obtain a short circuit according to another embodiment of the present application. As shown in fig. 5, another method for obtaining a short circuit current generated by a short circuit using a sub-power system model includes the steps of:

step S401', obtaining the upper and lower relation between each associated monitoring number and the reference monitoring number in the sub-power system model according to the connection relation in the sub-power system model.

Step S402', obtaining an associated voltage value and an associated power value at each associated monitoring number in the sub-power system model, and a reference voltage value and a reference power value at each reference monitoring number, and sequentially obtaining a power difference value between each associated power value and the reference power value and a voltage difference value between each associated voltage value and the reference voltage value from the upper level to the lower level based on the upper-lower level relation, wherein each power difference value corresponds to a uniquely determined voltage difference value.

Step S403', obtaining current values according to each voltage difference value and the corresponding power difference value, obtaining current difference values between any two current values in the current values according to the current values, judging whether the values of all the current difference values do not exceed the preset current difference value, and if so, adding all the current values to obtain short-circuit current generated by short-circuit.

In step S404', if at least one of the two current values exceeds the preset current difference value, determining the current value with the larger value as the short-circuit current generated by the short-circuit.

Since the connection relationship in the sub-power system model has shown that each monitoring number is in a direct level relationship with which monitoring numbers located at the upper level of the monitoring number and each monitoring number is in a direct level relationship with which monitoring numbers located at the lower level of the monitoring number. The upper and lower level relationship of each associated monitoring number in the sub-power system model with the reference monitoring number can be obtained by looking at the relationship of the associated monitoring number with which monitoring numbers are in the upper level and the relationship of the associated monitoring number with which monitoring numbers are in the lower level.

After the upper-lower relation between each associated monitoring number and the reference monitoring number in the sub-power system model is obtained, the associated voltage value and the associated power value at each associated monitoring number, and the reference voltage value and the reference power value at each reference monitoring number in the sub-power system model are obtained by using a WAMS system or other monitoring systems. The power difference between the associated power value and the reference power value is obtained by subtracting the reference power value located at the lower stage from the associated power value located at the upper stage, or the power difference between the associated power value and the reference power value is obtained by subtracting the associated power value located at the lower stage from the reference power value located at the upper stage. Similarly, the voltage difference between the relevant voltage value and the reference voltage value is obtained by subtracting the relevant voltage value at the upper stage from the reference voltage value at the lower stage, or the voltage difference between the relevant voltage value and the reference voltage value is obtained by subtracting the relevant voltage value at the lower stage from the reference voltage value at the upper stage. Each power difference value corresponds to a uniquely determined voltage difference value, and each voltage difference value also corresponds to a uniquely determined power difference value, namely, the power difference value corresponds to the voltage difference value one by one.

The value of the current on each branch or main is determined using the formula of the short circuit value= |power difference/(voltage difference + voltage difference x conjugate of voltage difference). Next, the implementation manners of the step S403 and the step S404 are used to implement the step S403 'of obtaining the current difference between any two current values of the current values according to the current values, determining whether the values of all the current differences do not exceed the preset current difference, and if they do not exceed the preset current difference, adding all the current values to obtain the short-circuit current generated by the short-circuit, and the step S404', which will not be described herein again. Therefore, short-circuit current calculation based on global information such as power flow of the power system and system parameters is not needed, short-circuit current can be determined by only collecting voltage and power of reference monitoring points and associated monitoring points in the sub-power system model, and short-circuit current in the power system is monitored more simply and rapidly.

In addition, the generation of the short-circuit current generated by the short-circuit by using the sub-power system model comprises the generation of alarm signals corresponding to the reference monitoring numbers one by one, so that workers can know the position section where the short-circuit occurs in time, and the position section can be quickly maintained, so that the damage of the short-circuit to the power system can be effectively restrained.

Fig. 6 is a block diagram of an apparatus for monitoring short-circuit current of a power system according to an embodiment of the present application. As shown in fig. 6, an apparatus for monitoring short-circuit current of a power system includes: the device comprises a voltage acquisition module, a processing module, a correlation acquisition module and a monitoring module.

The voltage acquisition module is used for acquiring voltage values at all monitoring points in the power system, wherein each monitoring point corresponds to a uniquely determined monitoring number. The processing module is used for obtaining the voltage change value at each monitoring point at the current moment according to the voltage values obtained in the last two times every time, judging whether at least one voltage change value exceeds a preset change value, and if yes, obtaining a change monitoring number corresponding to the monitoring point of which the voltage change value exceeds the preset change value. The association acquisition module is used for acquiring a reference monitoring number corresponding to the maximum voltage change value from all the change monitoring numbers, and acquiring an association monitoring number related to the reference monitoring number according to the reference monitoring number. The monitoring module is used for acquiring a sub-power system model formed by a reference monitoring number and an associated monitoring number from a preset power system model, and obtaining short-circuit current generated by short circuit by using the sub-power system model.

In addition, the device for monitoring the short-circuit current of the power system further comprises an alarm module, wherein the alarm module is used for obtaining the short-circuit current generated by the short-circuit by using the sub-power system model and then generating alarm signals corresponding to the reference monitoring numbers one by one.

Other functions executed by the voltage acquisition module, the processing module, the association acquisition module, the monitoring module and the alarm module and technical details of each function are the same as or similar to corresponding features in the method for monitoring short-circuit current of the power system, so that the description is omitted here.

The embodiment of the application also provides a computer storage medium, on which a computer program is stored which, when run on a computer, enables the computer to perform the steps of a method of monitoring short-circuit current in an electrical power system as described above.

It should be understood that, although the steps in the flowcharts of the figures are shown in order as indicated by the arrows, these steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited in order and may be performed in other orders, unless explicitly stated herein.

The foregoing is only a partial embodiment of the present application, and it should be noted that it will be apparent to those skilled in the art that modifications and adaptations can be made without departing from the principles of the present application, and such modifications and adaptations are intended to be comprehended within the scope of the present application.

Claims (10)

1. A method of monitoring short circuit current in an electrical power system, the method comprising:

acquiring voltage values at all monitoring points in the power system, wherein each monitoring point corresponds to a uniquely determined monitoring number;

obtaining a voltage change proportion at each monitoring point at the current moment according to the voltage values obtained in the last two times every time, judging whether at least one voltage change proportion exceeds a preset change proportion, and if yes, obtaining a change monitoring number corresponding to the monitoring point with the voltage change proportion exceeding the preset change proportion;

obtaining a reference monitoring number corresponding to the maximum voltage change proportion from all the change monitoring numbers, and obtaining an associated monitoring number related to the reference monitoring number according to the reference monitoring number;

and acquiring a sub-power system model formed by the reference monitoring number and the associated monitoring number from a preset power system model, and acquiring short-circuit current generated by short-circuit by using the sub-power system model.

2. The method of claim 1, wherein obtaining an associated monitor number from the reference monitor number that relates to the reference monitor number comprises:

obtaining a reference monitoring point corresponding to the reference monitoring number, obtaining an associated monitoring point positioned at a higher stage and/or an associated monitoring point positioned at a lower stage of the reference monitoring point according to a preset power system model, and determining the monitoring number corresponding to the associated monitoring point as an associated monitoring number related to the reference monitoring number.

3. The method of claim 2, wherein obtaining a short circuit current generated by the occurrence of a short circuit using the sub-power system model comprises:

obtaining a sub-tide flow calculation formula corresponding to the sub-power system model and related to solving current according to the connection relation and the impedance information in the sub-power system model;

acquiring known parameters required by the sub-tidal current calculation formula, and substituting the known parameters into the sub-tidal current calculation formula to obtain a current value on each branch in the sub-electric power model;

obtaining current difference values between any two current values in the current values according to the current values, judging whether the values of all the current difference values do not exceed a preset current difference value, and if not, adding all the current values to obtain short-circuit current generated by short-circuit;

And if at least one of the two current values exceeds the preset current difference value, determining the current value with the large value in the two current values corresponding to the preset current difference value as a short-circuit current generated by short-circuit.

4. The method of claim 2, wherein obtaining a short circuit current generated by the occurrence of a short circuit using the sub-power system model further comprises:

obtaining the upper and lower relation between each associated monitoring number and the reference monitoring number in the sub-power system model according to the connection relation in the sub-power system model;

acquiring an associated voltage value and an associated power value at each associated monitoring number in a sub-power system model, and a reference voltage value and a reference power value at each reference monitoring number, and sequentially acquiring a power difference value between each associated power value and the reference power value and a voltage difference value between each associated voltage value and the reference voltage value from an upper level to a lower level based on the upper-lower level relation, wherein each power difference value corresponds to a uniquely determined voltage difference value;

obtaining a current value according to each voltage difference value and a corresponding power difference value, obtaining a current difference value between any two current values in the current values according to the current values, judging whether the values of all the current difference values do not exceed a preset current difference value, and if so, adding all the current values to obtain a short-circuit current generated by short-circuit;

And if at least one of the two current values exceeds the preset current difference value, determining the current value with the larger value in the two current values corresponding to the exceeding preset current difference value as a short-circuit current generated by short-circuit.

5. The method according to claim 2, wherein the obtaining, according to a preset power system model, the associated monitoring point located at the upper stage and/or the associated monitoring point located at the lower stage of the reference monitoring point comprises:

judging whether the numerical value of the reference monitoring number is minimum in all the monitoring numbers, if so, acquiring an associated monitoring point positioned at the next stage of the reference monitoring point according to a connection relation in a preset power system model;

if not, judging whether the numerical value of the reference monitoring number is maximum in all the monitoring numbers, and if so, acquiring an associated monitoring point positioned at the upper stage of the reference monitoring point according to the connection relation in a preset power system model;

and if the relation is neither the maximum or the minimum, acquiring the associated monitoring point positioned at the upper stage of the reference monitoring point and the associated monitoring point positioned at the lower stage according to the connection relation in the preset power system model.

6. The method according to claim 1, wherein the method further comprises:

And if all the voltage change ratios do not exceed the preset change ratio, continuing to wait for obtaining the voltage values at all monitoring points in the power system.

7. The method of claim 1, wherein obtaining a short circuit current generated by the occurrence of the short circuit using the sub-power system model includes generating an alarm signal in one-to-one correspondence with the reference monitor number.

8. An apparatus for monitoring short circuit current in an electrical power system, the apparatus comprising: the device comprises a voltage acquisition module, a processing module, an association acquisition module and a monitoring module; wherein, the liquid crystal display device comprises a liquid crystal display device,

the voltage acquisition module is used for acquiring voltage values at all monitoring points in the power system, wherein each monitoring point corresponds to a uniquely determined monitoring number;

the processing module is used for obtaining a voltage change value at each monitoring point at the current moment according to the voltage values obtained in the last two times every time, judging whether at least one voltage change value exceeds a preset change value, and if yes, obtaining a change monitoring number corresponding to the monitoring point with the voltage change value exceeding the preset change value;

the association acquisition module is used for acquiring a reference monitoring number corresponding to the maximum voltage change value from all the change monitoring numbers, and acquiring an association monitoring number related to the reference monitoring number according to the reference monitoring number;

The monitoring module is used for acquiring a sub-power system model formed by the reference monitoring number and the associated monitoring number from a preset power system model, and obtaining short-circuit current generated by short circuit by using the sub-power system model.

9. The apparatus of claim 8, further comprising an alarm module; wherein, the liquid crystal display device comprises a liquid crystal display device,

the alarm module is used for obtaining short-circuit current generated by short-circuit by using the sub-power system model and then generating alarm signals corresponding to the reference monitoring numbers one by one.

10. A computer readable storage medium having stored thereon a computer program executable on a processor, characterized in that the computer program, when executed by the processor, implements a method of monitoring a short circuit current of an electrical power system according to any of claims 1 to 7.