Out-of-step splitting detection method and system based on line measurement impedance

Abstract

The invention discloses an out-of-step splitting detection method and system based on line measurement impedance, and relates to the technical field of power system automatic processing, and the method comprises the steps: setting an out-of-step count value as 0; collecting power frequency phasor values of the three-phase voltage and the three-phase current; calculating positive-sequence components of the three-phase voltage and the three-phase current; calculating measured positive sequence impedance, and extracting a real part and an imaginary part of the measured positive sequence impedance; calculating the change rate of an impedance real part; detecting whether the impedance real part has a zero crossing point; judging whether out-of-step oscillation occurs or not according to the zero crossing point detection result and the impedance change rate; and executing out-of-step separation operation according to whether the out-of-step oscillation frequency reaches a set threshold value. According to the out-of-step splitting detection method based on the line measurement impedance provided by the invention, the impedance is tested on the basis of the installation position of the out-of-step splitting device, so that the judgment that the voltage is smaller than a certain threshold value is not directly used, and the risk that the out-of-step splitting device might be operated at the tail end of a long line in an oscillation center is avoided; therefore, different out-of-step splitting devices can be matched with each other.

Description

Technical Field

[0001] The present invention relates to the technical field of power system automation processing, and in particular to a method and system for detecting out-of-step disconnection based on line impedance measurement. Background Art

[0002] When the power system is operating normally, the generators in the system keep running synchronously, that is, the rotors of the generators rotate at the same speed. When the system is subjected to a large disturbance, the speed of the generators will be different and may not be able to keep running synchronously. At this time, in order to maintain the stability of the system, relevant measures need to be taken to keep the generators in the system at the same speed. If the speed of the generators still cannot be kept the same, out-of-step oscillation will occur between the generators in the system, resulting in a large-scale power outage in the system. In order to avoid this situation, out-of-step decoupling should be implemented in the power system. Out-of-step decoupling of the power system means that when the power system loses step, a suitable decoupling location is selected to divide the generators with different speeds into different power islands, so that the generators in the same island keep the same speed. Therefore, each power island can still operate independently, preventing the accident from further expanding in the system. Therefore, an out-of-step decoupling device is generally installed in the power system, and its function is to detect whether the specified out-of-step oscillation occurs. If the specified out-of-step oscillation occurs, the corresponding components (units, lines, etc.) are disconnected according to the out-of-step decoupling rules. Summary of the invention

[0003] In view of the above-mentioned problems, the present invention is proposed.

[0004] Therefore, the technical problem solved by the present invention is: in view of the problem that the oscillation center is at the end of a long line and the action results of a multi-stage out-of-step decoupling device may be confused, out-of-step oscillation detection is performed based on the test impedance at the installation location of the out-of-step decoupling device.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for detecting out-of-step disconnection based on line impedance measurement, comprising:

[0006] Set the out-of-step count value to 0;

[0007] Collect the power frequency phasor values ​​of three-phase voltage and current;

[0008] Calculate the positive sequence components of three-phase voltage and current;

[0009] Calculate the measured positive sequence impedance and extract its real and imaginary parts;

[0010] Calculate the rate of change of the real part of the impedance;

[0011] Detect whether the real part of impedance passes through zero;

[0012] Determine whether out-of-step oscillation occurs based on the zero-crossing detection result and the impedance change rate;

[0013] The out-of-step disconnection operation is performed according to whether the number of out-of-step oscillations reaches the set threshold.

[0014] As a preferred solution of the out-of-step decoupling detection method based on line impedance measurement described in the present invention, wherein: the positive sequence component is expressed as,

[0015]

[0016] in, Represents the three-phase voltage phasor, represents the three-phase current phasor, t represents time, α is a complex number, i is the imaginary number symbol, i 2 =-1.

[0017] As a preferred solution of the out-of-step decoupling detection method based on line measurement impedance described in the present invention, wherein: the positive sequence impedance is expressed as,

[0018]

[0019] The real part is denoted as R M (t), the imaginary part is recorded as X M (t).

[0020] As a preferred solution of the out-of-step decoupling detection method based on line impedance measurement described in the present invention, wherein: the change rate is expressed as,

[0021]

[0022] Among them, △t is the sampling time step of the out-of-step decoupling device.

[0023] As a preferred solution of the out-of-step decoupling detection method based on line impedance measurement described in the present invention, wherein: the determination of whether out-of-step oscillation occurs includes: M (t)*R M (t-△t)<0Detection R M The zero crossing point of (t);

[0024] When t x R is detected at all times M (t) crosses zero, then detect t x -N△t to t x +N△t△R M (t) Is the absolute value less than △R? set .

[0025] As a preferred solution of the out-of-step decoupling detection method based on line impedance measurement described in the present invention, if t x -N△t to tx +N△t△R M (t) absolute value is less than △R set , the out-of-step oscillation is determined; at this time, if X is satisfied M (t x ) <X set , it means that the oscillation center is within the monitoring range of the out-of-step decoupling device, and the out-of-step count value M is set. x =M x +1.

[0026] As a preferred solution of the out-of-step disconnection detection method based on line impedance measurement described in the present invention, wherein: the out-of-step disconnection operation includes: x Greater than or equal to M set , indicating that the number of out-of-step oscillations has reached the set number of out-of-step oscillations, and the out-of-step decoupling operation is executed.

[0027] Another object of the present invention is to provide an out-of-step and parallel-connection detection system based on line measurement impedance, which can solve the problems of poor real-time performance and high probability of misjudgment in existing out-of-step and parallel-connection detection methods by constructing an out-of-step and parallel-connection detection system based on line measurement impedance, and effectively avoid the error of out-of-step oscillation judgment through precise positive sequence impedance analysis and change rate detection, thereby improving the accuracy and timeliness of out-of-step and parallel-connection operations.

[0028] To solve the above technical problems, the present invention provides the following technical solutions: a system for detecting out-of-step and disconnection based on line impedance measurement, comprising: a counting initialization module, a data acquisition module, a positive sequence calculation module, an impedance calculation module, a change rate calculation module, a zero-crossing detection module, an oscillation judgment module and a disconnection operation module; the counting initialization module is used to set the count value of the number of out-of-step times to 0; the data acquisition module is used to collect the industrial frequency phasor values ​​of the three-phase voltage and current; the positive sequence calculation module is used to calculate the positive sequence components of the three-phase voltage and current; the impedance calculation module is used to calculate the measured positive sequence impedance and extract its real part and imaginary part; the change rate calculation module is used to calculate the change rate of the real part of the impedance; the zero-crossing detection module is used to detect whether the real part of the impedance crosses a zero point; the oscillation judgment module is used to judge whether an out-of-step oscillation occurs according to the zero-crossing detection result and the impedance change rate; the disconnection operation module is used to perform an out-of-step and disconnection operation according to whether the number of out-of-step oscillations reaches a set threshold.

[0029] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the out-of-step decoupling detection method based on line impedance measurement are implemented.

[0030] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the out-of-step decoupling detection method based on line impedance measurement as described above.

[0031] Beneficial effects of the present invention: The out-of-step decoupling detection method based on line measurement impedance provided by the present invention is based on the test impedance at the installation location of the out-of-step decoupling device, avoiding the direct use of the judgment that the voltage is less than a certain threshold, and avoiding the risk of the out-of-step decoupling device refusing to operate that may occur when the oscillation center is at the end of a long line. M (t) <X set The method can determine the distance between the oscillation center and the out-of-step decoupling device, so that different out-of-step decoupling devices can cooperate with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0033] Figure 1 An overall flow chart of an out-of-step disconnection detection method based on line impedance measurement provided by an embodiment of the present invention.

[0034] Figure 2 A flowchart of out-of-step oscillation detection of an out-of-step decoupling detection method based on line impedance measurement is provided in accordance with an embodiment of the present invention.

[0035] Figure 3 A schematic diagram of an out-of-step disconnection configuration of an out-of-step disconnection detection method based on line impedance measurement provided by an embodiment of the present invention.

[0036] Figure 4 A schematic diagram of phase angle φ crossing of an out-of-step decoupling detection method based on line impedance measurement provided by an embodiment of the present invention.

[0037] Figure 5 An electric power system structure and power flow distribution diagram of an out-of-step disconnection detection method based on line impedance measurement provided by an embodiment of the present invention.

[0038] Figure 6 A voltage amplitude collected during out-of-step disconnection in an out-of-step disconnection detection method based on line measurement impedance provided by an embodiment of the present invention.

[0039] Figure 7 A voltage phase collected during out-of-step decoupling of an out-of-step decoupling detection method based on line measurement impedance provided by an embodiment of the present invention.

[0040] Figure 8 A current amplitude collected by an out-of-step disconnection detection method based on line measurement impedance provided by an embodiment of the present invention.

[0041] Fig. 9 A current phase angle collected during out-of-step decoupling of an out-of-step decoupling detection method based on line impedance measurement provided by an embodiment of the present invention.

[0042] Fig.10 A method for detecting out-of-step disconnection based on line impedance measurement provided by an embodiment of the present invention is provided. M , X M curve.

[0043] Fig.11 A method for detecting out-of-step decoupling based on line impedance measurement provided by an embodiment of the present invention is provided. M , X M curve.

[0044] Fig.12 A method for detecting out-of-step disconnection based on line impedance measurement provided by an embodiment of the present invention is provided. M , ΔR M curve.

[0045] Fig.13 A method for detecting out-of-step decoupling based on line impedance measurement provided by an embodiment of the present invention is provided. M , ΔR M curve.

[0046] Fig.14 An overall structural diagram of an out-of-step and disconnection detection system based on line impedance measurement provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0048] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0049] Example 1

[0050] Reference Figure 1-Figure 4 , as an embodiment of the present invention, provides a method for detecting out-of-step disconnection based on line impedance measurement, comprising:

[0051] At present, the out-of-step decoupling device mainly adopts the following methods to determine whether there is out-of-step oscillation: Figure 3 If the two-generator system shown in the figure has out-of-step oscillation, the phase angle between the voltage and current measured by the out-of-step decoupling device will be Figure 4 The phase angle plane shown in the figure crosses the I~VI zones according to a certain rule. If the oscillation center falls in the positive direction of the device installation (i.e., between MB), and point M is at the sending end, the phase angle increases from 0° to 180° during the out-of-step process, that is, it changes periodically within the range of quadrants I and II; and when point M is at the receiving end, the phase angle decreases from 180° to 0°, that is, it changes periodically within the range of quadrants II and I. If the oscillation center falls in the opposite direction of the device installation (i.e., between AM), and point M is at the receiving end (power flows from M to B), the phase angle decreases from 360° to 180° during the out-of-step oscillation process, that is, it changes periodically within the range of quadrants IV and III; and when point M is at the sending end (power flows from B to M), the phase angle increases from 180° to 360°, that is, it changes periodically within the range of quadrants III and IV. If the oscillation center happens to fall near the device installation, the phase angle flips back and forth between the two states of 0° and 180°.

[0052] The out-of-step decoupling device detects that the phase angle meets a certain rule and crosses, and it is considered that out-of-step oscillation has occurred. In order to prevent erroneous operation, the out-of-step decoupling device also introduces bus voltage as an auxiliary criterion, that is, when out-of-step oscillation is detected, the bus voltage needs to be lower than a certain threshold, which is a standard value, generally 0.65. Figure 3 When the middle line is long and the center of the out-of-step oscillation occurs near the end of the line, the voltage measured at the head end of the line is high, which does not meet the conditions for out-of-step decoupling action, resulting in refusal to operate; Figure 3 When both the A and M points in the circuit are equipped with out-of-step decoupling devices, when the center of the out-of-step oscillation is near the M point, both devices can detect the out-of-step oscillation and will act at the same time (in practice, only one device is expected to act), causing confusion in the out-of-step decoupling results. This patent is based on out-of-step oscillation detection based on the test impedance at the installation location of the out-of-step decoupling device, which can effectively solve the above problems.

[0053] Step 1: Set the out-of-step count value M x is 0.

[0054] Step 2: The out-of-step decoupling device collects the power frequency phasor values ​​of the three-phase voltage and current at its installation location. The three-phase voltage phasor is recorded as The three-phase current phasor is recorded as t represents time.

[0055] Step 3: Calculate the voltage and current positive sequence components, voltage positive sequence component Voltage positive sequence component Where α is a complex number, i is the imaginary number symbol, i 2 =-1.

[0056] Step 4: Calculate the out-of-step disconnection device and measure the positive sequence impedance The real part is denoted as R M (t), the imaginary part is recorded as X M (t).

[0057] Step 5: Take the measured positive sequence impedance The real part R M (t), calculate R M (t) rate of change △t is the sampling time step of the out-of-step decoupling device.

[0058] Step 6: Through R M (t)*R M (t-△t)<0Detection R M The zero crossing point of (t).

[0059] Step 7: When t x R is detected at all times M (t) crosses zero, then detect t x -N△t to t x +N△t△R M (t) Is the absolute value less than △R? set If t x -N△t to t x +N△t△R M (t) absolute value is less than △R set , then it is considered that out-of-step oscillation has occurred; at this time, if X M (t x ) <X set , it means that the oscillation center is within the monitoring range of the out-of-step decoupling device, and the out-of-step count value M is set. x =M x +1. Otherwise, go to step 2.

[0060] Step 8: If M x Greater than or equal to M set , indicating that the number of out-of-step oscillations has reached the set number of out-of-step oscillations, then the out-of-step decoupling operation is executed, otherwise go to step 2.

[0061] Step 9: End.

[0062] Example 2

[0063] Reference Figure 5-Figure 13 , which is an embodiment of the present invention, provides a method for detecting out-of-step disconnection based on line impedance measurement. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0064] Will be Figure 5 The system shown is analyzed as an implementation example, and the feasibility of the above method is verified through simulation. Figure 5 In the figure, "Generator 2" transmits electricity to "Substation 2" and "Substation 1" through a double-circuit line with the same parameters, and "Generator 1" transmits electricity to "Substation 1" through a single-circuit line. An out-of-step decoupling device is installed on the "Generator 2 side" of the "Generator 2-Substation 2" double-circuit line, and an out-of-step decoupling device is installed on the "Substation 2 side" of the "Substation 2-Substation 1" double-circuit line. Considering that the parameters of the double-circuit lines of "Generator 2-Substation 2" and "Substation 2-Substation 1" are the same, the out-of-step decoupling detection process is explained here using "Generator 2-Substation 2 II" and "Substation 2-Substation 1 II". The out-of-step decoupling device of "Generator 2-Substation 2 II" is called "decoupling device A", and the out-of-step decoupling device of "Substation 2-Substation 1 II" is called "decoupling device B". The relevant settings of decoupling device A and decoupling device B are shown in Table 1. Among them, △R set Desirable |△R M (t)|10% of the maximum value, X set Take 1.1 times the line reactance value (the line reactance from generator 2 to transformer 2 is about 15Ω, and the line reactance from transformer 2 to transformer 1 is about 60Ω), M set It is usually 1 or 2, and N is usually 2.

[0065] Table 1 Related settings of decoupling device A and decoupling device B

[0066]

[0067] When a three-phase symmetrical fault occurs in the I circuit of the two circuits (I and II) between substation 2 and substation 1 within 0.1 seconds, the voltage amplitudes of the second busbar of the generator and the second busbar of the substation measured by the decoupling device A and the decoupling device B are as follows: Figure 6 As shown in (considering that the three-phase voltage amplitudes are the same, only the value of phase A is given); the voltage phase angles of the second busbar of the generator and the second busbar of the transformer measured by the decoupling device A and the decoupling device B are as follows Figure 7As shown (considering that the phase angle of the three-phase voltage differs by 120°, only the value of phase A is given); the current amplitude of the "generator 2 ~ transformer 2 Ⅱ" line and the current amplitude of the "transformer 2 ~ transformer 1 Ⅱ" line measured by the decoupling device A and the decoupling device B are as shown Figure 8 As shown in (considering that the three-phase voltage amplitudes are the same, only the value of phase A is given); the phase angles of the line current of "Generator 2 ~ Substation 2 II" and "Substation 2 ~ Substation 1 II" measured by the decoupling device A and decoupling device B are as shown in Fig. 9 As shown (considering that the phase angles of the three-phase voltages differ by 120°, only the value of phase A is given). That is, the decoupling device A and the decoupling device B respectively collect the three-phase voltage phasors at their respective installation locations: With three-phase current phasor

[0068] Using the formula

[0069]

[0070] Calculate the measured positive sequence voltage and current of decoupling device A and decoupling device B respectively. Due to the three-phase symmetrical fault, the measured positive sequence voltage amplitude and phase angle are the same as the A phase voltage, and the measured positive sequence current amplitude and phase angle are the same as the A phase current.

[0071] Using the formula Calculate the measured positive sequence impedance of the decoupling device A and the decoupling device B respectively. The real part of the positive sequence impedance R measured by the decoupling device A is M , imaginary part X M Curve like Fig.10 As shown, the real part of the positive sequence impedance R measured by the decoupling device B M , imaginary part X M Curve like Fig.11 shown.

[0072] Decoupling device A and decoupling device B are based on the formula Calculate R M (t) rate of change △R M (t). Fig.12 △R calculated for the decoupling device A M With R M In contrast, Fig.13 △R calculated for the decoupling device A M With R M For the convenience of display, Fig.12 , Fig.13 △R shown in M It is 0.01 times the true value.

[0073] Take the decoupling device A and decoupling device B as examples: M (t)*R M(t-△t)<0 detects R M The zero-crossing time of (t) x ,t x The bus positive sequence voltage amplitude at time t x Time X M ,t x -N△t to t x +N△t time△R M As shown in Table 2 and Table 3. As can be seen from Table 2, the decoupling device A has detected the out-of-step oscillation, but because it does not meet the X M <X set , the out-of-step oscillation is not within the monitoring range and will not act. As can be seen from Table 3, the decoupling device B has detected the out-of-step oscillation and meets X M <X set When the number of out-of-step oscillations reaches the set value, the device will operate. Figure 5 It can be seen that the voltage of the second busbar of the substation is always greater than 0.65PU, and the existing out-of-step decoupling method cannot work correctly.

[0074] Table 2 Related measured values ​​and operation of the decoupling device A

[0075]

[0076] Table 3 Related measured values ​​and operation of disconnection device B

[0077]

[0078]

[0079] Example 3

[0080] An embodiment of the present invention is different from the first two embodiments in that:

[0081] If the functions are implemented in the form of software functional units 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, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0082] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0083] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0084] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0085] Example 4

[0086] Reference Fig.14 , which is an embodiment of the present invention, provides a system for detecting out-of-step disconnection based on line impedance measurement, comprising:

[0087] Count initialization module 100, data acquisition module 200, positive sequence calculation module 300, impedance calculation module 400, change rate calculation module 500, zero crossing detection module 600, oscillation judgment module 700 and decoupling operation module 800;

[0088] The counting initialization module 100 is used to set the out-of-step count value to 0;

[0089] The data acquisition module 200 is used to collect the power frequency phasor values ​​of the three-phase voltage and current;

[0090] The positive sequence calculation module 300 is used to calculate the positive sequence components of the three-phase voltage and current;

[0091] The impedance calculation module 400 is used to calculate the measured positive sequence impedance and extract its real part and imaginary part;

[0092] The change rate calculation module 500 is used to calculate the change rate of the real part of the impedance;

[0093] The zero-crossing detection module 600 is used to detect whether the real part of the impedance crosses a zero point;

[0094] The oscillation judgment module 700 is used to judge whether out-of-step oscillation occurs according to the zero-crossing point detection result and the impedance change rate;

[0095] The decoupling operation module 800 is used to perform a decoupling operation according to whether the number of out-of-step oscillations reaches a set threshold.

[0096] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for detecting out-of-step disconnection based on line impedance measurement, characterized in that: include: Set the out-of-step count value to 0; Collect the power frequency phasor values ​​of three-phase voltage and current; Calculate the positive sequence components of three-phase voltage and current; Calculate the measured positive sequence impedance and extract its real and imaginary parts; Calculate the rate of change of the real part of the impedance; Detect whether the real part of impedance passes through zero; Determine whether out-of-step oscillation occurs based on the zero-crossing detection result and the impedance change rate; The out-of-step decoupling operation is performed according to whether the number of out-of-step oscillations reaches the set threshold.

2. The out-of-step disconnection detection method based on line impedance measurement according to claim 1, characterized in that: The positive sequence component is expressed as, in, Represents the three-phase voltage phasor, represents the three-phase current phasor, t represents time, α is a complex number, i is the imaginary number symbol, i 2 =-1.

3. The out-of-step disconnection detection method based on line impedance measurement according to claim 2, characterized in that: The positive sequence impedance is expressed as, The real part is denoted as R M (t), the imaginary part is recorded as X M (t).

4. The out-of-step disconnection detection method based on line impedance measurement according to claim 3 is characterized in that: The rate of change is expressed as, Among them, △t is the sampling time step of the out-of-step decoupling device.

5. The out-of-step disconnection detection method based on line impedance measurement according to claim 4, characterized in that: The determination of whether out-of-step oscillation occurs includes: M (t)*R M (t-△t)<0Detection R M The zero crossing point of (t); When t x R is detected at all times M (t) crosses zero, then detect t x -N△t to t x +N△t△R M (t) Is the absolute value less than △R? set .

6. The out-of-step disconnection detection method based on line impedance measurement according to claim 5, characterized in that: If x -N△t to t x +N△t△R M (t) absolute value is less than △R set , the out-of-step oscillation is determined; at this time, if X is satisfied M (t x ) <X set , it means that the oscillation center is within the monitoring range of the out-of-step decoupling device, and the out-of-step count value M is set. x =M x +1.

7. The out-of-step disconnection detection method based on line impedance measurement according to claim 6, characterized in that: The out-of-step decoupling operation includes: x Greater than or equal to M set , indicating that the number of out-of-step oscillations has reached the set number of out-of-step oscillations, and the out-of-step decoupling operation is executed.

8. A system using the out-of-step decoupling detection method based on line impedance measurement as claimed in any one of claims 1 to 7, characterized in that: include: A counting initialization module (100), a data acquisition module (200), a positive sequence calculation module (300), an impedance calculation module (400), a change rate calculation module (500), a zero-crossing point detection module (600), an oscillation judgment module (700), and a decoupling operation module (800); The counting initialization module (100) is used to set the count value of the number of out-of-step times to 0; The data acquisition module (200) is used to collect the power frequency phasor values ​​of the three-phase voltage and current; The positive sequence calculation module (300) is used to calculate the positive sequence components of the three-phase voltage and current; The impedance calculation module (400) is used to calculate the measured positive sequence impedance and extract its real part and imaginary part; The change rate calculation module (500) is used to calculate the change rate of the real part of the impedance; The zero-crossing detection module (600) is used to detect whether the real part of the impedance crosses a zero point; The oscillation judgment module (700) is used to judge whether out-of-step oscillation occurs according to the zero-crossing point detection result and the impedance change rate; The decoupling operation module (800) is used to perform a decoupling operation according to whether the number of out-of-step oscillations reaches a set threshold.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the out-of-step disconnection detection method based on line impedance measurement according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the out-of-step disconnection detection method based on line impedance measurement according to any one of claims 1 to 7 are implemented.

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