CN-114050542-B - Method and device for determining abnormal sampling point in power system

CN114050542BCN 114050542 BCN114050542 BCN 114050542BCN-114050542-B

Abstract

The invention provides a method and a device for determining abnormal sampling points in a power system, wherein the method comprises the steps of continuously obtaining sampling points of target quantity of the power system, wherein a curve of the target quantity is a periodic curve under the condition that the power system is not interfered, the number of the sampling points included in the curve of each period is N, judging whether the variation amplitude of u (N) meets a preset condition, if so, determining a difference value a between u (N) and u (N-N), determining a difference value b between u (N-1) and u (N-1-N), judging whether a is more than or equal to deltau+b or a is less than or equal to-deltau+b, wherein deltau is a preset threshold value, and if so, determining the sampling point corresponding to u (N) is the abnormal sampling point.

Inventors

SUN CHANGYUAN
SHI KANG
XU RENAN
ZHU ZHENGWEI

Assignees

西门子电力自动化有限公司

Dates

Publication Date: 20260505
Application Date: 20211116

Claims (8)

1. The method for determining the abnormal sampling points in the power system comprises the steps of continuously obtaining the sampling points of the target quantity of the power system, wherein the curve of the target quantity is a periodic curve under the condition that the power system is not interfered, and the number of the sampling points included in the curve of each period is N; Characterized in that the method further comprises: Judging whether the variation amplitude of u (n) meets a preset condition or not; If the judgment result is yes, determining a difference value a between u (N) and u (N-N), wherein u (N) represents the value of an nth sampling point, u (N-N) represents the value of an nth sampling point, and N is a positive integer; determining a difference b between u (N-1) and u (N-1-N), wherein u (N-1) represents the value of the N-1 th sampling point and u (N-1-N) represents the value of the N-1-N th sampling point; Judging whether the following formula is satisfied: a is more than or equal to Deltau+b or a is less than or equal to minus Deltau+b, wherein Deltau is a preset threshold value; if the judgment result is yes, determining the sampling point corresponding to u (n) as an abnormal sampling point; the preset condition is one of the following conditions: Condition one: determining whether u (n+1) -u (n) is greater than or equal to a first preset threshold, wherein u (n+1) is the current value of the n+1th sampling point; determining whether u (n) -u (n-1) is less than or equal to a second preset threshold; if the determination results are yes, judging that the variation amplitude of u (n) meets the preset condition; Condition II: determining whether u (n+1) -u (n) is less than or equal to a third preset threshold, wherein u (n+1) is the current value of the n+1th sampling point; Determining whether u (n) -u (n-1) is greater than or equal to a fourth preset threshold; If the determination results are yes, it is judged that the variation amplitude of u (n) meets the preset condition.
2. The method of claim 1, wherein n is a sampling point at a peak or a sampling point at a trough on the curve.
3. The method according to claim 1, wherein the first preset threshold is equal to Deltau and the second preset threshold is equal to-Deltau, or The third preset threshold value is equal to-delta u, and the fourth preset threshold value is equal to delta u; Or alternatively The target amount is a voltage or a current.
4. An apparatus for determining an abnormal sampling point in a power system, comprising: An acquisition unit, configured to continuously acquire sampling points of a target amount of the power system, where a curve of the target amount is a periodic curve when the power system is not interfered, and a number of sampling points included in the curve of each period is N; Characterized in that the device further comprises: A first judging unit for judging whether the variation amplitude of u (n) meets a preset condition, if yes, triggering a first determining unit; the first determining unit is used for determining a difference value a between u (N) and u (N-N), wherein u (N) represents the value of an nth sampling point, u (N-N) represents the value of an nth sampling point, and N is a positive integer; a second determining unit configured to determine a difference b between u (N-1) and u (N-1-N), where u (N-1) represents a value of an N-1 th sampling point and u (N-1-N) represents a value of an N-1-N th sampling point; a second judging unit for judging whether the following formula is satisfied: a is more than or equal to Deltau+b or a is less than or equal to minus Deltau+b, wherein Deltau is a preset threshold value; if the judgment result is yes, triggering a third determining unit; The third determining unit is used for determining the sampling point corresponding to u (n) as an abnormal sampling point; The first judging unit is specifically configured to judge that the variation amplitude of u (n) meets a preset condition according to one of the following conditions: Condition one: determining whether u (n+1) -u (n) is greater than or equal to a first preset threshold, wherein u (n+1) is the current value of the n+1th sampling point; determining whether u (n) -u (n-1) is less than or equal to a second preset threshold; if the determination results are yes, judging that the variation amplitude of u (n) meets the preset condition; Condition II: determining whether u (n+1) -u (n) is less than or equal to a third preset threshold, wherein u (n+1) is the current value of the n+1th sampling point; Determining whether u (n) -u (n-1) is greater than or equal to a fourth preset threshold; If the determination results are yes, it is judged that the variation amplitude of u (n) meets the preset condition.
5. The apparatus of claim 4, wherein n is a sampling point at a peak or a sampling point at a trough on the curve.
6. The apparatus of claim 4, wherein the first predetermined threshold is equal to Deltau and the second predetermined threshold is equal to-Deltau, or The third preset threshold value is equal to-delta u, and the fourth preset threshold value is equal to delta u; Or alternatively The target amount is a voltage or a current.
7. Apparatus for determining an abnormal sampling point in a power system, the apparatus comprising: at least one memory for storing instructions; at least one processor for performing the method for determining an outlier sampling point in a power system according to any one of claims 1-3 according to the instructions stored by the memory.
8. A readable storage medium having stored therein machine readable instructions which, when executed by a machine, perform the method for determining an anomaly sampling point in a power system according to any one of claims 1-3.

Description

Method and device for determining abnormal sampling point in power system Technical Field The invention relates to the field of power systems, in particular to a method and a device for determining abnormal sampling points in a power system. Background If the power element in the power system or the power system itself fails, the relay protection device can send out an alarm signal in time or directly send out a tripping command to the controlled breaker. As such, the relay protection device needs to continuously sample the voltage or current of the power system to determine whether a failure has occurred in a power element of the power system or the power system itself. However, if a lightning strike or an over-voltage occurs, the sampling of the relay protection device is disturbed, and an erroneous sampling point, i.e. an abnormal sampling point, is generated, as shown in fig. 4, wherein the sampling point 501 is an abnormal sampling point. At this time, the power system does not have any fault, but the abnormal sampling point may cause misoperation of the relay protection device. Therefore, the abnormal sampling point needs to be identified. Disclosure of Invention In view of this, the invention proposes a method for determining abnormal sampling points in an electric power system, comprising continuously obtaining sampling points of a target quantity of the electric power system, wherein a curve of the target quantity is a periodic curve under the condition that the electric power system is not interfered, and the number of sampling points included in each periodic curve is N; The method further comprises the steps of: Judging whether the variation amplitude of u (n) meets a preset condition or not; If the judgment result is yes, determining a difference value a between u (N) and u (N-N), wherein u (N) represents the value of an nth sampling point, u (N-N) represents the value of an nth sampling point, and N is a positive integer; determining a difference b between u (N-1) and u (N-1-N), wherein u (N-1) represents the value of the N-1 th sampling point and u (N-1-N) represents the value of the N-1-N th sampling point; Judging whether the following formula is satisfied: a is more than or equal to Deltau+b or a is less than or equal to minus Deltau+b, wherein Deltau is a preset threshold value; if the judgment result is yes, determining the sampling point corresponding to u (n) as an abnormal sampling point. According to the method described above, optionally n is the sampling point at the peak or the sampling point at the trough on the curve. According to the method as described above, optionally, the preset condition is one of the following conditions: Condition one: determining whether u (n+1) -u (n) is greater than or equal to a first preset threshold, wherein u (n+1) is the current value of the n+1th sampling point; Determining whether u (n) -u (n-1) is less than or equal to a second preset threshold; if the determination results are yes, judging that the variation amplitude of u (n) meets the preset condition; Condition II: Determining whether u (n+1) -u (n) is less than or equal to a third preset threshold, wherein u (n+1) is the current value of the n+1th sampling point; determining whether u (n) -u (n-1) is greater than or equal to a fourth preset threshold; If the determination results are yes, it is judged that the variation amplitude of u (n) meets the preset condition. According to the method described above, optionally the first preset threshold is equal to Deltau and the second preset threshold is equal to-Deltau, or The third preset threshold value is equal to-delta u, and the fourth preset threshold value is equal to delta u; Or alternatively The target amount is a voltage or a current. The invention also provides a device for determining an abnormal sampling point in a power system, comprising: An acquisition unit, configured to continuously acquire sampling points of a target amount of the power system, where a curve of the target amount is a periodic curve when the power system is not interfered, and a number of sampling points included in the curve of each period is N; The apparatus further comprises: A first judging unit for judging whether the variation amplitude of u (n) meets a preset condition, if yes, triggering a first determining unit; the first determining unit is used for determining a difference value a between u (N) and u (N-N), wherein u (N) represents the value of an nth sampling point, u (N-N) represents the value of an nth sampling point, and N is a positive integer; The second determining unit is used for determining a difference value b between u (N-1) and u (N-1-N), wherein u (N-1) represents the value of an N-1 th sampling point, and u (N-1-N) represents the value of an N-1-N th sampling point; The second judging unit is configured to judge whether the following formula is satisfied: a is more than or equal to Deltau+b or a is less than or equal to minus Deltau+b,