Protection action method and system for preventing abnormal AC circuit

Abstract

The present invention relates to the technical field of relay protection of power systems, and provides a protection action method and system for preventing abnormal AC circuits, wherein the method comprises: a relay protection device samples the AC circuit at a fixed sampling frequency, and records the instantaneous sampling value of each sampling point into a sampling array; calculates a protection action fixed value conversion value; based on the sampling array, performs a two-point differential calculation on the instantaneous sampling value of the sampling point to obtain a differential array of the sampling point difference; performs a square calculation on the differential array to obtain a first sampling point cache array; calculates the square of the sampling point difference of two sampling points, and sums the obtained two square values ​​to obtain a second sampling point cache array; converts the protection action time fixed value into the number of sampling points; performs a protection action logic judgment on each sampling point based on the second sampling point cache array, the protection action fixed value conversion value and the number of sampling points, and executes the protection action according to the judgment result. The present invention can avoid protection misoperation without affecting the protection speed.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection of power systems, and in particular to a protection action method and system for preventing abnormalities in an alternating current circuit. Background Art

[0002] In recent years, in the power system industry, domestic relay protection devices have been tested. During the test run, incorrect actions of domestic devices often occur due to abnormalities in the AC circuit. The main components of the AC circuit are CT and AD chips. When these two main chips are abnormal, the relay protection device often produces incorrect actions. Now relay protection manufacturers have strengthened the quality inspection of CT and AD chips to improve the pass rate of CT and AD chips and reduce the non-action of relay protection due to hardware problems.

[0003] At present, relay protection usually adopts dual AD sampling to improve the reliability of relay protection devices, which increases the hardware cost of relay protection devices. However, the CT circuit is still one. When the CT circuit is abnormal, the dual AD sampling will also be abnormal, which may also lead to incorrect action of the relay protection device. In addition, the relay protection device adopts the method of adding starting elements to increase the reliability of the protection device. The commonly used starting methods are sudden start and delayed start. The sudden start criterion is relatively sensitive, but its anti-interference ability is weak, which reduces the reliability of relay protection; the delayed start time is usually determined by avoiding the calculation cycle time of the protection calculation amount. When the calculation cycle is longer, the protection starts slower, which reduces the speed of relay protection. Summary of the invention

[0004] The purpose of the present invention is to solve at least one technical problem in the background technology and to provide a protection action method and system for preventing abnormalities in an AC circuit.

[0005] To achieve the above object, the present invention provides a protection action method for preventing abnormal AC circuit, comprising:

[0006] The relay protection device samples the AC circuit at a fixed sampling frequency and records the instantaneous sampling value of each sampling point into the sampling array f[n];

[0007] Calculate the protection action setting conversion value F set ;

[0008] Based on the sampling array f[n], the instantaneous sampling values ​​of the sampling points are calculated by two-point difference to obtain the difference array f1[n] of the sampling point difference values;

[0009] Performing square calculation on the difference array f1[n] to obtain the first sampling point cache array f2[n];

[0010] Calculate the square of the sampling point difference between two sampling points, and sum the two square values ​​to obtain the second sampling point cache array f3[n];

[0011] The protection action time constant is converted into the sampling point number T;

[0012] Based on the second sampling point cache array f3[n], the protection action setting conversion value F set The protection action logic judgment is performed on each sampling point based on the number of sampling points T, and the protection action is executed according to the judgment result.

[0013] According to one aspect of the present invention, the fixed conversion value F is derived by using the sine wave characteristics and trigonometric function formulas. set is a constant value: F set = 4I set 2 *(1-cosβ), where I set To protect the constant value, β is the angle difference between the two sampling points.

[0014] According to one aspect of the present invention, the difference array f1[n] is: f1[n]= f[n]-f[n-n1], where n1 is the n1th point before the current sampling point n.

[0015] According to one aspect of the present invention, the first sampling point cache array f2[n] is: f2[n]= f1[n] *f1[n].

[0016] According to one aspect of the present invention, when the sum of the square of a sampling point difference value of a sampling point and the square of a sampling point difference value of another sampling point corresponding to the sampling point with a difference value of 90° is a constant value, the two square values ​​are summed according to this condition to obtain the second sampling point cache array f3[n], and the formula is: f3[n]= f2[n] + f2[n-n2], where the sampling point n2 is a sampling point with a difference value of 90° from the nth point.

[0017] According to one aspect of the present invention, the sampling frequency of the relay protection device is S sampling points in 1 second, and the protection action time constant is converted into the number of sampling points T=S*t set , where t set It is the setting value of protection action time.

[0018] According to one aspect of the present invention, based on the second sampling point cache array f3[n], the protection action constant conversion value F set The protection action logic is judged for each sampling point based on the number of sampling points T, and the protection action is executed according to the judgment result, including:

[0019] When f3[n]≥F setWhen the current sampling point meets the protection action condition, the protection action delay count t automatically increases by 1; when the protection action delay count t is greater than or equal to T, the protection action is executed;

[0020] When f3[n]<F set When the current sampling point does not meet the protection action conditions, the protection action delay count t is directly set to 0, and the protection action is not executed.

[0021] To achieve the above object, the present invention further provides a protection action system for preventing abnormal AC circuit, comprising:

[0022] The sampling value recording module, the relay protection device samples the AC circuit at a fixed sampling frequency, and records the instantaneous sampling value of each sampling point into the sampling array f[n];

[0023] Protection action set value conversion value calculation module, calculates the protection action set value conversion value F set ;

[0024] The difference array calculation module performs two-point difference calculation on the instantaneous sampling values ​​of the sampling points based on the sampling array f[n] to obtain the difference array f1[n] of the sampling point difference values;

[0025] A first sampling point cache array calculation module performs square calculation on the difference array f1[n] to obtain a first sampling point cache array f2[n];

[0026] A second sampling point cache array calculation module calculates the square of the sampling point difference between two sampling points, and sums the two square values ​​to obtain a second sampling point cache array f3[n];

[0027] Sampling point conversion module, which converts the protection action time constant into the sampling point number T;

[0028] The protection action determination execution module is based on the second sampling point cache array f3[n] and the protection action fixed value conversion value F set The protection action logic judgment is performed on each sampling point based on the number of sampling points T, and the protection action is executed according to the judgment result.

[0029] To achieve the above objectives, the present invention also provides an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the protection action method for preventing AC circuit abnormality as described above.

[0030] To achieve the above object, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the protection action method for preventing AC circuit abnormality as described above is implemented.

[0031] According to the solution of the present invention, the present invention utilizes the characteristic of filtering out DC quantity by differential calculation, and can avoid protection malfunction caused by abnormal AC circuit generating a large constant DC component or a DC component with a long attenuation.

[0032] The present invention utilizes the sine wave characteristics and trigonometric function formulas to derive a short window calculation formula, and utilizes this formula to perform point-by-point logical judgment on the data of each sampling point. When continuous multi-point data meets the action conditions, the protection is actuated. This method can avoid protection malfunction caused by intermittent abnormal points in the AC circuit without affecting the protection speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A flowchart schematically showing a protection action method for preventing abnormality of an AC circuit according to an embodiment of the present invention;

[0034] Figure 2 A flowchart schematically shows the protection action method for preventing AC circuit abnormality according to the first embodiment. DETAILED DESCRIPTION

[0035] The present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the present invention, rather than implying any limitation on the scope of the present invention.

[0036] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0037] Figure 1 The flowchart schematically shows a protection action method for preventing abnormal AC circuit according to an embodiment of the present invention. Figure 1 As shown, in this embodiment, the protection action method for preventing AC circuit abnormality includes:

[0038] The relay protection device samples the AC circuit at a fixed sampling frequency and records the instantaneous sampling value of each sampling point into the sampling array f[n];

[0039] Calculate the protection action setting conversion value F set ;

[0040] Based on the sampling array f[n], the instantaneous sampling values ​​of the sampling points are calculated by two-point difference to obtain the difference array f1[n] of the sampling point difference values;

[0041] Performing square calculation on the difference array f1[n] to obtain the first sampling point cache array f2[n];

[0042] Calculate the square of the sampling point difference between two sampling points, and sum the two square values ​​to obtain the second sampling point cache array f3[n];

[0043] The protection action time setting value (the time setting value to realize the protection function, which is set in advance) is converted into the number of sampling points T;

[0044] Based on the second sampling point cache array f3[n], the protection action setting conversion value F set The protection action logic judgment is performed on each sampling point based on the number of sampling points T, and the protection action is executed according to the judgment result.

[0045] Further, according to an embodiment of the present invention, the fixed conversion value F is derived by using the sine wave characteristics and the trigonometric function formula. set is a constant value: F set = 4I set 2 *(1-cosβ), where I set To protect the constant value, β is the angle difference between the two sampling points.

[0046] Specifically, in this embodiment, (A) since the AC waveform is a sine wave, it can be expressed as Isinɑ, I is the effective value of the sine wave, and ɑ is the angle of the sine wave.

[0047] (B) The difference between two sampling points of the sine wave is as follows:

[0048] F1= Isinɑ- Isin(ɑ-β), where: ɑ is the angle of the sine wave at the current sampling point, and β is the angle difference of the sine wave between a sampling point and the current sampling point;

[0049] (C) The difference value corresponding to the angle θ with ɑ is as follows:

[0050] F2= Isin(ɑ-θ)- Isin(ɑ-β-θ), where: θ is the angle difference of the sine wave between another sampling point and the current sampling point;

[0051] (D) Calculate the sum of the squares of the sampling point differences of two sampling points as follows:

[0052] F=2*(Isinɑ-Isin(ɑ-β)) 2 +2*(Isin(ɑ-θ)-Isin(ɑ-β-θ))2 , decompose and classify the formula to obtain formula 4:

[0053] F=2I 2 *((((sinɑ) 2 +(sin(ɑ-θ)) 2 )+(((sin(ɑ-β)) 2 +(sin(ɑ-β-θ)) 2 )-2(sinɑ*sin(ɑ-β) + sin(ɑ-θ)*sin(ɑ-β-θ)));

[0054] (E) Using the trigonometric function relationship sin(ɑ-90°)= -cosɑ, assuming θ=90°, we can simplify Formula 4 to obtain Formula 5:

[0055] F=2I 2 *((((sinɑ) 2 +(cosɑ) 2 )+(((sin(ɑ-β)) 2 +(cos(ɑ-β)) 2 )-2(sinɑ*sin(ɑ-β) +cosɑ*cos(ɑ-β)));

[0056] (F) Using trigonometric functions (sinɑ) 2 +(cosɑ) 2 =1 and cos(ɑ-φ)=cosɑ*cos(ɑ-φ)+sinɑ*sin(ɑ-φ), further simplifying formula 5 to obtain formula 6: F=4I 2 *(1-cosβ).

[0057] From the derivation process of Formula 1 to Formula 6, it can be concluded that the sum of the squares of the differences of the angles of 90° on the sine wave (the sum of the squares of the differences of the sampling points of two sampling points) is a constant value, which is related to the difference angle and the amplitude of the sine wave.

[0058] The setting value of relay protection is generally set according to the effective value of the sine wave. Then the setting value is converted using formula 6, and the conversion value is F set = 4I set 2 *(1-cosβ), whose value is used as the judgment threshold of the sum of squares of the subsequent differences.

[0059] Further, according to an embodiment of the present invention, the difference array f1[n] is: f1[n]= f[n]-f[n-n1], where n1 is the n1th point before the current sampling point n.

[0060] Further, according to an embodiment of the present invention, the first sampling point cache array f2[n] is: f2[n]= f1[n] *f1[n].

[0061] Further, according to an embodiment of the present invention, when the sum of the square of a sampling point difference value of a sampling point and the square of a sampling point difference value of another sampling point corresponding to the sampling point with a difference value of 90° is a constant value, the two square values ​​are summed according to this condition to obtain a second sampling point cache array f3[n], and the formula is: f3[n]= f2[n] + f2[n-n2], where the sampling point n2 is a sampling point with a difference value of 90° from the nth point.

[0062] Further, according to an embodiment of the present invention, the sampling frequency of the relay protection device is S sampling points in 1 second, and the protection action time constant is converted into the number of sampling points T=S*t set , where t set It is the fixed value of protection action time. At this time, T is the number of points that need to be judged continuously.

[0063] In this embodiment, it can be seen from Formula 3 that the present invention uses 4 sampling point data for judgment (the 4 points are the current sampling point, the point with a difference of β angle from the current point, the point with a difference of θ angle from the current point and the point with a difference of β+θ from the current point. These 4 points are transformed by the relevant trigonometric relationship through Formulas 1-6. The sum of the squares of the differences of the angles of 90° on the sine wave (the sum of the squares of the differences of the sampling points of the two sampling points) is a constant value, that is, the sampling point first performs a two-point difference calculation, and then squares the difference calculation result, and adds the square of the difference of the current point to the square of the difference before 90° corresponding to obtain the calculation result, that is, it is performed on 4 sampling points.), when one of the 4 sampling points is abnormal, it can affect the judgment of the 4 sampling points, and in order to meet the reliability of the protection device, when T<4*k, T=4*k, k is the reliability coefficient (k>1); when T≧4*k, the T value remains unchanged.

[0064] Further, according to an embodiment of the present invention, based on the second sampling point cache array f3[n], the protection action constant conversion value F set The protection action logic is judged for each sampling point based on the number of sampling points T, and the protection action is executed according to the judgment result, including:

[0065] When f3[n]≥F set When the current sampling point meets the protection action condition, the protection action delay count t automatically increases by 1 (that is, the delay count t=t+1); when the protection action delay count t is greater than or equal to T, the protection action is executed;

[0066] When f3[n]<F setWhen the current sampling point does not meet the protection action conditions, the protection action delay count t is directly set to 0 (that is, delay count t=0), and the protection action is not executed.

[0067] According to the above scheme of the present invention, the present invention utilizes the characteristic of filtering out DC quantity by differential calculation, so as to avoid protection malfunction caused by abnormal AC circuit generating a large constant DC component or a DC component with long attenuation.

[0068] The present invention utilizes the sine wave characteristics and trigonometric function formulas to derive a short window calculation formula, and utilizes this formula to perform point-by-point logical judgment on the data of each sampling point. When continuous multi-point data meets the action conditions, the protection is actuated. This method can avoid protection malfunction caused by intermittent abnormal points in the AC circuit without affecting the protection speed.

[0069] Furthermore, the present invention also provides a protection action system for preventing abnormal AC circuit, comprising:

[0070] The sampling value recording module, the relay protection device samples the AC circuit at a fixed sampling frequency, and records the instantaneous sampling value of each sampling point into the sampling array f[n];

[0071] Protection action set value conversion value calculation module, calculates the protection action set value conversion value F set ;

[0072] The difference array calculation module performs two-point difference calculation on the instantaneous sampling values ​​of the sampling points based on the sampling array f[n] to obtain the difference array f1[n] of the sampling point difference values;

[0073] A first sampling point cache array calculation module performs square calculation on the difference array f1[n] to obtain a first sampling point cache array f2[n];

[0074] A second sampling point cache array calculation module calculates the square of the sampling point difference between two sampling points, and sums the two square values ​​to obtain a second sampling point cache array f3[n];

[0075] Sampling point conversion module, which converts the protection action time constant into the sampling point number T;

[0076] The protection action determination execution module is based on the second sampling point cache array f3[n] and the protection action fixed value conversion value F set The protection action logic judgment is performed on each sampling point based on the number of sampling points T, and the protection action is executed according to the judgment result.

[0077] Further, according to an embodiment of the present invention, the fixed conversion value F is derived by using the sine wave characteristics and the trigonometric function formula. set is a constant value: F set = 4Iset 2 *(1-cosβ), where I set To protect the constant value, β is the angle difference between the two sampling points.

[0078] Specifically, in this embodiment, (A) since the AC waveform is a sine wave, it can be expressed as Isinɑ, I is the effective value of the sine wave, and ɑ is the angle of the sine wave.

[0079] (B) The difference between two sampling points of the sine wave is as follows:

[0080] F1= Isinɑ- Isin(ɑ-β), where: ɑ is the angle of the sine wave at the current sampling point, and β is the angle difference of the sine wave between a sampling point and the current sampling point;

[0081] (C) The difference value corresponding to the angle θ with ɑ is as follows:

[0082] F2= Isin(ɑ-θ)- Isin(ɑ-β-θ), where: θ is the angle difference of the sine wave between another sampling point and the current sampling point;

[0083] (D) Calculate the sum of the squares of the sampling point differences of two sampling points as follows:

[0084] F=2*(Isinɑ-Isin(ɑ-β)) 2 +2*(Isin(ɑ-θ)-Isin(ɑ-β-θ)) 2 , decompose and classify the formula to obtain formula 4:

[0085] F=2I 2 *((((sinɑ) 2 +(sin(ɑ-θ)) 2 )+(((sin(ɑ-β)) 2 +(sin(ɑ-β-θ)) 2 )-2(sinɑ*sin(ɑ-β) + sin(ɑ-θ)*sin(ɑ-β-θ)));

[0086] (E) Using the trigonometric function relationship sin(ɑ-90°)= -cosɑ, assuming θ=90°, we can simplify Formula 4 to obtain Formula 5:

[0087] F=2I 2 *((((sinɑ) 2 +(cosɑ) 2)+(((sin(ɑ-β)) 2 +(cos(ɑ-β)) 2 )-2(sinɑ*sin(ɑ-β) +cosɑ*cos(ɑ-β)));

[0088] (F) Using trigonometric functions (sinɑ) 2 +(cosɑ) 2 =1 and cos(ɑ-φ)=cosɑ*cos(ɑ-φ)+sinɑ*sin(ɑ-φ), further simplifying formula 5 to obtain formula 6: F=4I 2 *(1-cosβ).

[0089] From the derivation process of Formula 1 to Formula 6, it can be concluded that the sum of the squares of the differences of the angles of 90° on the sine wave (the sum of the squares of the differences of the sampling points of two sampling points) is a constant value, which is related to the difference angle and the amplitude of the sine wave.

[0090] The setting value of relay protection is generally set according to the effective value of the sine wave. Then the setting value is converted using formula 6, and the conversion value is F set = 4I set 2 *(1-cosβ), whose value is used as the judgment threshold of the sum of squares of the subsequent differences.

[0091] Further, according to an embodiment of the present invention, the difference array f1[n] is: f1[n]= f[n]-f[n-n1], where n1 is the n1th point before the current sampling point n.

[0092] Further, according to an embodiment of the present invention, the first sampling point cache array f2[n] is: f2[n]= f1[n] *f1[n].

[0093] Further, according to an embodiment of the present invention, when the sum of the square of a sampling point difference value of a sampling point and the square of a sampling point difference value of another sampling point corresponding to the sampling point with a difference value of 90° is a constant value, the two square values ​​are summed according to this condition to obtain a second sampling point cache array f3[n], and the formula is: f3[n]= f2[n] + f2[n-n2], where the sampling point n2 is a sampling point with a difference value of 90° from the nth point.

[0094] Further, according to an embodiment of the present invention, the sampling frequency of the relay protection device is S sampling points in 1 second, and the protection action time constant is converted into the number of sampling points T=S*t set , where t set To protect the action time. At this time, T is the number of points that need to be judged continuously.

[0095] In this embodiment, it can be seen from Formula 3 that the present invention uses 4 sampling point data for judgment (the 4 points are the current sampling point, the point with a difference of β angle from the current point, the point with a difference of θ angle from the current point and the point with a difference of β+θ from the current point. These 4 points are transformed by the relevant trigonometric relationship through Formulas 1-6. The sum of the squares of the differences of the angles of 90° on the sine wave (the sum of the squares of the differences of the sampling points of the two sampling points) is a constant value, that is, the sampling point first performs a two-point difference calculation, and then squares the difference calculation result, and adds the square of the difference of the current point to the square of the difference before 90° corresponding to obtain the calculation result, that is, it is performed on 4 sampling points.), when one of the 4 sampling points is abnormal, it can affect the judgment of the 4 sampling points, and in order to meet the reliability of the protection device, when T<4*k, T=4*k, k is the reliability coefficient (k>1); when T≧4*k, the T value remains unchanged.

[0096] Further, according to an embodiment of the present invention, based on the second sampling point cache array f3[n], the protection action constant conversion value F set The protection action logic is judged for each sampling point based on the number of sampling points T, and the protection action is executed according to the judgment result, including:

[0097] When f3[n]≥F set When the current sampling point meets the protection action condition, the protection action delay count t automatically increases by 1; when the protection action delay count t is greater than or equal to T, the protection action is executed;

[0098] When f3[n] <F set When the current sampling point does not meet the protection action conditions, the protection action delay count t is directly set to 0, and the protection action is not executed.

[0099] According to the above scheme of the present invention, the present invention utilizes the characteristic of filtering out DC quantity by differential calculation, so as to avoid protection malfunction caused by abnormal AC circuit generating a large constant DC component or a DC component with long attenuation.

[0100] The present invention utilizes the sine wave characteristics and trigonometric function formulas to derive a short window calculation formula, and utilizes this formula to perform point-by-point logical judgment on the data of each sampling point. When continuous multi-point data meets the action conditions, the protection is actuated. This method can avoid protection malfunction caused by intermittent abnormal points in the AC circuit without affecting the protection speed.

[0101] Furthermore, the present invention also provides an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the protective action method for preventing abnormal AC circuit as described above is implemented.

[0102] Furthermore, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the protection action method for preventing abnormality of an AC circuit as described above is implemented.

[0103] Based on the above solution of the present invention, the solution of the present invention is described in detail in the following in combination with the accompanying drawings in the form of a specific embodiment.

[0104] Example 1

[0105] A protection action method to prevent abnormal AC circuit, such as Figure 2 As shown, including:

[0106] Step S1, the relay protection device performs sampling at a constant frequency of 2400 Hz, that is, collects instantaneous values ​​of 2400 sampling points in 1 second, and stores the sampling values ​​in the sampling value array f[n];

[0107] Step S2: Calculate the protection action fixed value conversion value F set :

[0108] The relay protection device samples 2400 sampling points in 1 second. According to the 50Hz AC system, the number of sampling points per cycle of the AC system is 48 (2400 / 50 = 48). Since the AC voltage is a sine wave, the total angle of each cycle of the sine wave is 360°, so the angle difference between two adjacent sampling points is 7.5° (360 / 48 = 7.5).

[0109] The number of sampling points with a 90° interval difference is 12 (90 / 7.5=12);

[0110] The setting value of the protection device is I set , the sampling point difference is calculated as the current point minus the corresponding second point before, and the corresponding angle is 15° (7.5*2 = 15). This 15° is the difference angle, corresponding to the formula F set = 4I set 2 *(1-cosβ) is used for setting conversion, and the protection action setting conversion value is F set = 4I set 2 *(1-cos15°)=0.13629669*I set 2 ;

[0111] Step S3: perform two-point differential calculation on the sampling point value to obtain the corresponding cache data f1[n]:

[0112] In step S2, when setting the value, the conversion is performed at intervals of one sampling point, and the two-point difference calculation is performed at intervals of one sampling point, and the calculation formula is: f1[n]= f[n]-f[n-2];

[0113] Step S4, calculate the square of the difference value to obtain a new cache array f2[n], the formula is:

[0114] f2[n] = f1[n]* f1[n];

[0115] Step S5, calculate the difference sample value square sum array f3[n]:

[0116] In step 2, the relative angle between the two sampling points is calculated to be 90°, which corresponds to the 12th point before the current point. The square sum formula of the difference is: f3[n]= f2[n]+ f2[n-12];

[0117] Step S6: Convert the protection action time constant into the number of sampling points T:

[0118] The protection action time is generally set according to the delay. In this embodiment, each sampling point needs to be judged, so the protection action time needs to be converted into the number of sampling points corresponding to the protection action time;

[0119] In this embodiment, the sampling frequency is 2400 Hz, the protection action time is t1, and the protection action time is converted to the number of points for judging the sampling points T=2400*t1;

[0120] This embodiment uses data from four sampling points for determination. When data from one of the four sampling points is abnormal, it may affect the determination of the four sampling points. Therefore, T must be at least greater than 4.

[0121] In this embodiment, to meet the reliability of the protection device, k is set to 3, and the calculated minimum T value is 12 (4*3). When the delayed sampling point count T<12, T is forced to be 12;

[0122] Step S7: Compare the square sum of the difference value f3[n] and the protection fixed value conversion value F at each sampling point set Make logical judgment on protection action:

[0123] When f3[n]≥F set When the current sampling point meets the protection action condition, the protection action delay count t automatically increases by 1; when the protection action delay count t is greater than or equal to T, the protection action is executed;

[0124] When f3[n]<F set When the current sampling point does not meet the protection action conditions, the protection action delay count t is directly set to 0.

[0125] Those skilled in the art will appreciate that the modules and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0126] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and equipment can refer to the corresponding processes in the aforementioned method implementation methods, and will not be repeated here.

[0127] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0128] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0129] In addition, each functional module in the embodiment of the present invention may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0130] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the energy-saving signal sending / receiving method of each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical disks.

[0131] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

[0132] It should be understood that the size of the serial numbers of each step in the content of the invention and the implementation methods of the present invention does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation methods of the present invention.

Claims

1. A protection action method for preventing abnormal AC circuit, characterized in that: include: The relay protection device samples the AC circuit at a fixed sampling frequency and records the instantaneous sampling value of each sampling point into the sampling array f[n]; Calculate the protection action setting conversion value F set ; Based on the sampling array f[n], the instantaneous sampling values ​​of the sampling points are calculated by two-point difference to obtain the difference array f1[n] of the sampling point difference values; Performing square calculation on the difference array f1[n] to obtain the first sampling point cache array f2[n]; Calculate the square of the sampling point difference between two sampling points, and sum the two square values ​​to obtain the second sampling point cache array f3[n]; The protection action time constant is converted into the sampling point number T; Based on the second sampling point cache array f3[n], the protection action setting conversion value F set Perform protection action logic judgment on each sampling point based on the number of sampling points T, and execute the protection action according to the judgment result; The fixed conversion value F is derived through the sine wave characteristics and trigonometric function formula. set is a constant value: F set =4I set 2 *(1-cosβ), where I set To protect the constant value, β is the angle difference between the two sampling points; Based on the second sampling point cache array f3[n], the protection action fixed value conversion value F set The protection action logic is judged for each sampling point based on the number of sampling points T, and the protection action is executed according to the judgment result, including: When f3[n]≥F set When the current sampling point meets the protection action condition, the protection action delay count t automatically increases by 1; when the protection action delay count t is greater than or equal to T, the protection action is executed; When f3[n]<F set When the current sampling point does not meet the protection action conditions, the protection action delay count t is directly set to 0, and the protection action is not executed.

2. The protection action method for preventing AC circuit abnormality according to claim 1, characterized in that: The difference array f1[n] is: f1[n]= f[n]-f[n-n1], where n1 is the n1th point before the current sampling point n.

3. The protection action method for preventing AC circuit abnormality according to claim 1, characterized in that: The first sampling point cache array f2[n] is: f2[n]= f1[n] *f1[n].

4. The protection action method for preventing AC circuit abnormality according to claim 1, characterized in that: When the sum of the square of the sampling point difference of a sampling point and the square of the sampling point difference of another sampling point corresponding to the sampling point with a difference of 90° is a constant value, the two square values ​​are summed according to this condition to obtain the second sampling point cache array f3[n], and the formula is: f3[n]= f2[n] + f2[n-n2], where the sampling point n2 is the sampling point with a difference of 90° from the nth point.

5. The protection action method for preventing abnormal AC circuit according to claim 1, characterized in that: The sampling frequency of the relay protection device is S sampling points in 1 second, and the protection action time constant is converted into the number of sampling points T=S*t set , where t set It is the setting value of protection action time.

6. The protection action system for preventing abnormal AC circuit is characterized by: include: The sampling value recording module, the relay protection device samples the AC circuit at a fixed sampling frequency, and records the instantaneous sampling value of each sampling point into the sampling array f[n]; Protection action set value conversion value calculation module, calculates the protection action set value conversion value F set ; The difference array calculation module performs two-point difference calculation on the instantaneous sampling values ​​of the sampling points based on the sampling array f[n] to obtain the difference array f1[n] of the sampling point difference values; A first sampling point cache array calculation module performs square calculation on the difference array f1[n] to obtain a first sampling point cache array f2[n]; A second sampling point cache array calculation module calculates the square of the sampling point difference between two sampling points, and sums the two square values ​​to obtain a second sampling point cache array f3[n]; Sampling point conversion module, which converts the protection action time constant into the sampling point number T; The protection action determination execution module is based on the second sampling point cache array f3[n] and the protection action fixed value conversion value F set Perform protection action logic judgment on each sampling point based on the number of sampling points T, and execute the protection action according to the judgment result; The fixed conversion value F is derived through the sine wave characteristics and trigonometric function formula. set is a constant value: F set =4I set 2 *(1-cosβ), where I set To protect the constant value, β is the angle difference between the two sampling points; Based on the second sampling point cache array f3[n], the protection action fixed value conversion value F set The protection action logic is judged for each sampling point based on the number of sampling points T, and the protection action is executed according to the judgment result, including: When f3[n]≥F set When the current sampling point meets the protection action condition, the protection action delay count t automatically increases by 1; when the protection action delay count t is greater than or equal to T, the protection action is executed; When f3[n]<F set When the current sampling point does not meet the protection action conditions, the protection action delay count t is directly set to 0, and the protection action is not executed.

7. An electronic device, characterized in that The invention comprises a processor, a memory and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, the protection action method for preventing abnormal AC circuit as described in any one of claims 1 to 5 is implemented.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the protection action method for preventing AC circuit abnormality according to any one of claims 1 to 5 is implemented.

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