Time domain inter-turn protection method and system for reactor based on impedance parameter identification

Abstract

A time-domain inter-turn protection method and system for reactors based on resistance and inductance parameter identification is proposed. This method obtains the instantaneous values ​​of the three-phase currents at the beginning and end of the reactor within a sliding window. A current matrix is ​​constructed using the instantaneous values ​​of the three-phase currents at the beginning and their rate of change. The instantaneous voltage across the neutral point reactor is calculated based on the inductance value of the small reactor at the neutral point and the rate of change of the instantaneous value of the self-generated zero-sequence current at the end of the reactor within the sliding window. A voltage vector is constructed using the voltage difference between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the small reactor at the neutral point. The equivalent resistance and equivalent inductance of the reactor are calculated using the current matrix and voltage vector. When the equivalent resistance is greater than a resistance threshold and the equivalent inductance is less than an inductance threshold, and this condition persists for a set duration, an inter-turn fault triggers the protection action. The protection method exhibits high sensitivity and is reliable even when the reactor core is saturated, the line distributed capacitance is high, or the reactor oscillates, without malfunctioning. It is also unaffected by new power systems.

Description

Technical Field

[0001] This invention belongs to the field of power system relay protection technology, and relates to reactor protection, and particularly to a high-sensitivity time-domain inter-turn protection method and system for reactors based on impedance and inductance parameter identification. Background Technology

[0002] Reactors are crucial reactive power compensation devices in power systems. Inter-turn faults, a typical internal fault of reactors, present significant challenges when large fault currents occur locally. Externally measurable electrical characteristics are weak, making fault diagnosis difficult. If inter-turn faults are not cleared promptly, they can lead to reactor fires and damage. Currently, zero-sequence directional protection principles are widely used, but these principles lack sensitivity for small inter-turn faults in reactors. Furthermore, with the rapid development of new power systems, internal faults in reactors are affected by power supply characteristics, resulting in higher system harmonic content in the fault current compared to conventional power systems. This poses a risk of incorrect operation for traditional phasor-based reactor protection principles.

[0003] In existing technologies, the inter-turn protection method for high-voltage shunt reactors based on parameter imbalance detection is established on a time-domain parameter model. It uses the electrical quantities at the end of the high-voltage reactor to calculate the electrical parameters of each phase in the least-squares sense. Based on the premise that it is impossible for three phases of a high-voltage shunt reactor to experience inter-turn short-circuit faults simultaneously, it identifies whether an inter-turn short-circuit fault has occurred by constructing a comprehensive criterion for parameter imbalance detection. This method only uses inductance parameters for fault judgment and does not use resistance parameters, resulting in insufficient reliability when the reactor core is saturated, the line distributed capacitance is present, or the reactor oscillates. The shunt reactor protection method based on parameter identification includes the following steps: First, system information is collected in real time to construct the parameter identification equation for the zero-sequence equivalent impedance. Then, the least-squares parameter estimation method is used to calculate the inductance parameter sequence and resistance parameter sequence of the zero-sequence equivalent impedance at the corresponding time, obtaining the corresponding estimated values ​​of phase angle and amplitude parameters. Finally, the corresponding direction and amplitude criteria are used to determine whether an internal fault has occurred in the shunt reactor. This method still uses zero-sequence quantities for judgment. In practical applications, to prevent the accuracy of direction and amplitude judgment criteria from being affected by the small zero-sequence electrical quantity, zero-sequence current and voltage thresholds are often set, resulting in insufficient sensitivity of such criteria to small inter-turn faults in reactors. In the inter-turn fault detection method of ultra-high voltage parallel reactors based on equivalent resistance changes, the resistance value calculated by the full-wave Fourier method is used to identify inter-turn faults in reactors, without using inductance values. Therefore, it is easily affected by the power supply characteristics of new power systems. When the reactor core is saturated, the line distributed capacitance is high, and the reactor oscillates, the reliability of the identification results is not high. Summary of the Invention

[0004] To address the technical problem of insufficient sensitivity to minute inter-turn faults within reactors, this invention discloses a time-domain inter-turn protection method and system for reactors based on resistance and inductance parameter identification. Based on Ohm's law and the least squares method, it utilizes a current matrix and voltage vector to calculate the equivalent resistance and equivalent inductance of the reactor. The equivalent resistance and equivalent inductance are compared with threshold values ​​simultaneously to determine whether the reactor protection should operate. This reactor protection method exhibits high sensitivity, capable of identifying extremely minute inter-turn faults, and is reliable and does not malfunction even when the reactor core is saturated, the line distributed capacitance is high, or the reactor oscillates. It is also unaffected by the power supply characteristics of new power systems.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] This invention proposes a time-domain inter-turn protection method for reactors based on resistance-inductance parameter identification, comprising:

[0007] Obtain the instantaneous values ​​of the first-phase three-phase current and the last-phase three-phase current within the sliding window of the reactor;

[0008] Construct a current matrix using the instantaneous values ​​of the three-phase current at the beginning and the rate of change of the instantaneous values ​​of the three-phase current at the beginning;

[0009] The instantaneous value of the self-generated zero-sequence current at the end of the reactor is calculated using the instantaneous value of the three-phase current at the end.

[0010] Based on the inductance value of the neutral point reactor and the rate of change of the instantaneous value of the self-generated zero-sequence current at the end of the reactor within the sliding window, calculate the instantaneous voltage value across the neutral point reactor within the sliding window.

[0011] A voltage vector is constructed using the voltage difference between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the neutral point reactor.

[0012] Based on Ohm's law and the least squares method, the equivalent resistance and equivalent inductance of the reactor are calculated using the current matrix and voltage vector.

[0013] When the equivalent resistance value is greater than the resistance threshold value and the equivalent inductance value is less than the inductance threshold value, and this condition is maintained for a set duration, the reactor inter-turn fault triggers the protection action.

[0014] The length of the sliding window is preferably half a power frequency cycle. The sliding window contains M+1 discrete sampling times, and the time interval between two adjacent sampling times is Δt.

[0015] Based on the current sampling time k, the sliding window is [kM, k+1], and the current matrix A is as follows:

[0016]

[0017] In the formula, This represents the instantaneous value of the three-phase current at the beginning of the sliding window. This represents the rate of change of the instantaneous values ​​of the three-phase currents at the beginning of the sliding window.

[0018] Using the instantaneous values ​​of the three-phase current at the beginning of the sampling point at two sampling points adjacent to sampling point kj, the rate of change of the instantaneous value of the three-phase current at the beginning of the sampling point kj is calculated, satisfying the following relationship:

[0019]

[0020] In the formula, Δt is the time interval between two adjacent sampling times.

[0021] 3i0=i la +i lb +i lc

[0022] In the formula, 3i0 is the instantaneous value of the self-generated zero-sequence current at the end of the reactor, i la i lb i lc These are the instantaneous values ​​of the phase currents A, B, and C at the end of the reactor, respectively.

[0023] The instantaneous value of the three-phase current at the end of the reactor within the sliding window is i l (k+1),i l (k), i l (k-1), ..., i l (k-M+1), i l (kM), the instantaneous value of the zero-sequence current generated at the end of the reactor within the sliding window is 3i0(k+1), 3i0(k), 3i0(k-1), ..., 3i0(k-M+1).

[0024] Using the instantaneous values ​​of the self-generated zero-sequence current at the reactor terminal at two sampling times adjacent to sampling time kj, the rate of change of the instantaneous value of the self-generated zero-sequence current at the reactor terminal at sampling time kj is calculated, satisfying the following relationship:

[0025]

[0026] In the formula, 3i′0(kj) is the rate of change of the instantaneous value of the self-generated zero-sequence current at the end of the reactor at sampling time kj, 3i0(k-j+1) and 3i0(kj-1) are the instantaneous values ​​of the self-generated zero-sequence current at the end of the reactor at two adjacent sampling times kj, respectively, and Δt is the time interval between the two adjacent sampling times.

[0027] The instantaneous voltage across the neutral point reactance satisfies the following relationship:

[0028] u0(kj)=L0·3i′0(kj),j=0,1,…,M-1

[0029] In the formula, u0(kj) is the instantaneous voltage across the neutral point reactance at sampling time kj, and L0 is the inductance of the neutral point reactance of the reactor.

[0030] The voltage vector is as follows:

[0031]

[0032] In the formula, Δu(k), Δu(k-1), ..., Δu(k-M+1) are the voltage differences between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the neutral point reactor.

[0033] The voltage difference at sampling time kj satisfies the following relationship:

[0034] Δu(kj)=u(kj)-u0(kj),j=0,1,…,M-1

[0035] In the formula, u(kj) is the voltage difference at sampling time kj.

[0036] The equivalent resistance and equivalent inductance of the reactor are as follows:

[0037]

[0038] In the formula, R m L m These are the equivalent resistance and equivalent inductance values ​​of the reactor, respectively. A is the current matrix, and B is the voltage vector.

[0039] Resistance threshold R set The inductance threshold L is the equivalent resistance value of the reactor during normal operation multiplied by the reliability factor. set The equivalent inductance value of the reactor during normal operation is multiplied by the reliability coefficient, which ranges from [0.7, 0.9]; the set duration ranges from (10, 100) ms.

[0040] This invention also proposes a reactor time-domain inter-turn protection system based on resistance-inductance parameter identification, comprising:

[0041] The current matrix module is used to obtain the instantaneous values ​​of the first-phase three-phase current and the last-phase three-phase current within the sliding window of the reactor; and to construct the current matrix using the instantaneous values ​​of the first-phase three-phase current and the rate of change of the first-phase three-phase current.

[0042] The voltage vector module is used to calculate the instantaneous value of the self-generated zero-sequence current at the end of the reactor using the instantaneous value of the three-phase current at the end; to calculate the instantaneous value of the voltage across the neutral point reactor within the sliding window based on the inductance value of the neutral point reactor and the rate of change of the instantaneous value of the self-generated zero-sequence current at the end of the reactor within the sliding window; and to construct a voltage vector based on the voltage difference between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the neutral point reactor.

[0043] The resistance and inductance parameter identification module is used to calculate the equivalent resistance and equivalent inductance of the reactor based on Ohm's law and the least squares method, using the current matrix and voltage vector.

[0044] The inter-turn protection module is used to determine that an inter-turn fault in the reactor triggers protection action when the equivalent resistance value is greater than the resistance threshold value and the equivalent inductance value is less than the inductance threshold value, and this condition is maintained for a set duration.

[0045] The present invention is also a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to perform operations according to the instructions to execute the steps of the method.

[0046] The present invention is also a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method.

[0047] The beneficial effects achieved by this invention include at least the following: This invention calculates the equivalent resistance and equivalent inductance of the reactor by collecting instantaneous values ​​of the reactor terminal voltage, first-terminal current, and last-terminal current. It determines whether an inter-turn fault has occurred by comparing the equivalent resistance value with a threshold value and simultaneously comparing the equivalent inductance value with the threshold value. This invention implements high-frequency current change rate analysis, and by fitting key parameters using the least squares method, it can identify microsecond-level current distortions, thereby improving the sensitivity of reactor protection for minor inter-turn faults. Furthermore, high-frequency current change rate analysis can promptly identify core saturation and oscillation, ensuring the reliability of inter-turn fault identification and protection when the reactor core is saturated, the line distributed capacitance is high, and the reactor oscillates. This invention proposes an inter-turn protection method based on time-domain criteria, unaffected by new power systems. Attached Figure Description

[0048] Figure 1 The present invention presents a flowchart of a high-sensitivity time-domain inter-turn protection method for reactors based on resistance-inductance parameter identification. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, other embodiments obtained by those skilled in the art without creative effort are all within the protection scope of this invention.

[0050] This invention proposes a highly sensitive time-domain inter-turn protection method for reactors based on resistance-inductance parameter identification, such as... Figure 1 As shown, the protection methods include:

[0051] Step 1: Obtain the instantaneous values ​​of the first-phase three-phase current and the last-phase three-phase current within the sliding window of the reactor;

[0052] Specifically, the length of the sliding window is preferably half a power frequency cycle, and the sliding window contains M+1 discrete sampling times, with a time interval of Δt between two adjacent sampling times;

[0053] Specifically, based on the current sampling time being k, and the sliding window being [kM, k+1], the instantaneous value of the three-phase current at the head end of the reactor within the sliding window is... The instantaneous value of the three-phase current at the end of the reactor within the sliding window is i l (k+1),i l (k), i l (k-1), ..., i l (k-M+1), i l (kM).

[0054] Step 2: Construct the current matrix A using the instantaneous values ​​of the three-phase currents at the beginning and the rate of change of the instantaneous values ​​of the three-phase currents at the beginning, as follows:

[0055]

[0056] In the formula, This represents the instantaneous value of the three-phase current at the beginning of the sliding window. The rate of change of the instantaneous values ​​of the three-phase currents at the beginning of the sliding window;

[0057] The rate of change of the instantaneous value of the three-phase current at the beginning of the sampling point is calculated using the instantaneous values ​​of the three-phase current at the beginning of the sampling point kj from two sampling points adjacent to sampling point kj, satisfying the following relationship:

[0058]

[0059] In the formula, Δt is the time interval between two adjacent sampling times;

[0060] In this embodiment, the current matrix is ​​shown below:

[0061]

[0062] Step 3: Calculate the instantaneous value of the self-generated zero-sequence current at the end of the reactor using the instantaneous values ​​of the three-phase currents at the end, as follows:

[0063] 3i0=i la +i lb +i lc

[0064] In the formula, 3i0 is the instantaneous value of the self-generated zero-sequence current at the end of the reactor, i la i lb i lc These are the instantaneous values ​​of the phase currents A, B, and C at the end of the reactor, respectively.

[0065] Specifically, the instantaneous values ​​of the zero-sequence current generated at the end of the reactor within the sliding window are 3i0(k+1), 3i0(k), 3i0(k-1), ..., 3i0(k-M+1).

[0066] Step 4: Calculate the instantaneous voltage across the neutral point reactor within the sliding window based on the inductance value of the neutral point reactor and the rate of change of the instantaneous value of the self-generated zero-sequence current at the reactor end within the sliding window.

[0067] Specifically, using the instantaneous values ​​of the self-generated zero-sequence current at the reactor terminal at two sampling times adjacent to sampling time kj, the rate of change of the instantaneous value of the self-generated zero-sequence current at the reactor terminal at sampling time kj is calculated, satisfying the following relationship:

[0068]

[0069] In the formula, 3i′0(kj) is the rate of change of the instantaneous value of the self-generated zero-sequence current at the end of the reactor at sampling time kj, and 3i0(k-j+1) and 3i0(kj-1) are the instantaneous values ​​of the self-generated zero-sequence current at the end of the reactor at two adjacent sampling times kj, respectively.

[0070] The instantaneous voltage across the neutral point reactance satisfies the following relationship:

[0071] u0(kj)=L0·3i′0(kj),j=0,1,…,M-1

[0072] In the formula, u0(kj) is the instantaneous voltage across the neutral point reactance at sampling time kj, and L0 is the inductance of the neutral point reactance of the reactor.

[0073] Step 5: Construct voltage vector B using the voltage difference between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the neutral point reactor, as follows:

[0074]

[0075] In the formula, Δu(k), Δu(k-1), ..., Δu(k-M+1) are the voltage differences between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the neutral point reactor.

[0076] The voltage difference at sampling time kj satisfies the following relationship:

[0077] Δu(kj)=u(kj)-u0(kj),j=0,1,…,M-1

[0078] In the formula, u(kj) is the voltage difference at sampling time kj.

[0079] In this embodiment, the voltage vector is shown below:

[0080]

[0081] Step 6: Based on Ohm's law and the least squares method, using the current matrix and voltage vector, calculate the equivalent resistance and equivalent inductance of the reactor, as follows:

[0082]

[0083] In the formula, R m L m These are the equivalent resistance and equivalent inductance values ​​of the reactor, respectively.

[0084] In the above formula, (A T ·A) -1 ·A T These are key parameters in the least squares method of parameter estimation theory. Therefore, through the above steps, the equivalent resistance and equivalent inductance of the reactor can be calculated using the least squares method. This invention realizes high-frequency current change rate analysis. By fitting key parameters using the least squares method, it can identify microsecond-level current distortion, thereby improving the sensitivity of reactor protection in the event of minor inter-turn faults. Moreover, high-frequency current change rate analysis can promptly identify core saturation and oscillation, ensuring the reliability of inter-turn fault identification and protection when reactor core saturation, line distributed capacitance, and reactor oscillation occur.

[0085] Step 7: When the equivalent resistance value is greater than the resistance threshold value and the equivalent inductance value is less than the inductance threshold value, and this condition persists for a set duration, the reactor inter-turn fault triggers the protection operation; where the resistance threshold value R... setThe preferred value is the equivalent resistance of the reactor during normal operation multiplied by the reliability coefficient, and the inductance threshold value L. set The preferred value is the equivalent inductance value of the reactor during normal operation multiplied by the reliability coefficient, with the reliability coefficient ranging from [0.7, 0.9]; the set duration ranges from (10, 100) ms.

[0086] In new power systems, wind / solar power is connected to the grid via inverters, reducing system inertia and limiting the amplitude of fault currents. Traditional overcurrent protection is not sensitive enough and may fail to operate. The current change rate of reactors is controlled by the inverter's limiting strategy, masking transient characteristics. Power electronic equipment induces sub- / supersynchronous oscillations, and the spectrum of fault current and oscillation current are mixed, making frequency domain protection prone to misjudgment. Therefore, this invention proposes an inter-turn protection method based on time domain criteria, which is unaffected by new power systems.

[0087] The present invention will be further described below with reference to the accompanying drawings, taking a 1% inter-turn fault in phase A of the reactor as an example. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and should not be used to limit the scope of protection of the present invention. The reactor has a rated capacity of 180MVA, a rated voltage of 550kV, a PT ratio of 530kV to 100V, a CT ratio of 300A to 1A at both the beginning and end, and a neutral point reactance of 704Ω.

[0088] Collect the instantaneous voltage u across phase A of the reactor. a Instantaneous value of phase A current at the start of the reactor i a Instantaneous values ​​of phase A, B, and C currents at the reactor terminals i la i lb i lc ; 20 sampling points were collected continuously; detailed data are shown in Tables 1 and 2:

[0089] Table 1 Detailed Data (Current unit: A, Voltage unit: V)

[0090]

[0091]

[0092] Table 2 Detailed Data (Current unit: A, Voltage unit: V)

[0093]

[0094] The zero-sequence current of the small reactance of the reactor was calculated, and the results are detailed in Tables 3 and 4:

[0095] Table 3 (Current unit: A)

[0096]

[0097] Table 4 (Current unit: A)

[0098]

[0099] Calculate the equivalent resistance and equivalent inductance of the reactor, where Δt is the sampling interval, which is the reciprocal of the sampling frequency and is 1 / 2000, and L0 is the neutral point reactance, with a primary value of 704Ω and a secondary value of 39.85Ω.

[0100] The equivalent resistance value R of phase A is calculated. m The Ω is 5.44Ω, and the equivalent inductance value L is... m It is 0.2H.

[0101] Compare the equivalent resistance value of 5.44Ω with the equivalent resistance threshold value R. set Size, R set The equivalent resistance is 3.91Ω, which is greater than the equivalent resistance threshold. The calculated equivalent inductance value of 0.2H is compared with the equivalent inductance threshold value L. set Size, L set The value is 0.27H, which is less than the equivalent inductance threshold.

[0102] Continuously calculate R using the above calculation method for the data from the previous 20 sampling points at each time step. m L m When R is continuously satisfied m >R set And L m <L set The protection mechanism will activate when the time reaches 20ms to 80ms.

[0103] This invention also proposes a reactor time-domain inter-turn protection system based on resistance-inductance parameter identification, comprising:

[0104] The current matrix module is used to obtain the instantaneous values ​​of the first-phase three-phase current and the last-phase three-phase current within the sliding window of the reactor; and to construct the current matrix using the instantaneous values ​​of the first-phase three-phase current and the rate of change of the first-phase three-phase current.

[0105] The voltage vector module is used to calculate the instantaneous value of the self-generated zero-sequence current at the end of the reactor using the instantaneous value of the three-phase current at the end; to calculate the instantaneous value of the voltage across the neutral point reactor within the sliding window based on the inductance value of the neutral point reactor and the rate of change of the instantaneous value of the self-generated zero-sequence current at the end of the reactor within the sliding window; and to construct a voltage vector based on the voltage difference between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the neutral point reactor.

[0106] The resistance and inductance parameter identification module is used to calculate the equivalent resistance and equivalent inductance of the reactor based on Ohm's law and the least squares method, using the current matrix and voltage vector.

[0107] The inter-turn protection module is used to determine that an inter-turn fault in the reactor triggers protection action when the equivalent resistance value is greater than the resistance threshold value and the equivalent inductance value is less than the inductance threshold value, and this condition is maintained for a set duration.

[0108] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0109] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0110] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0111] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A time-domain inter-turn protection method for reactors based on resistance-inductance parameter identification, characterized in that, include: Obtain the instantaneous values ​​of the first-phase three-phase current and the last-phase three-phase current within the sliding window of the reactor; Construct a current matrix using the instantaneous values ​​of the three-phase current at the beginning and the rate of change of the instantaneous values ​​of the three-phase current at the beginning; The instantaneous value of the self-generated zero-sequence current at the end of the reactor is calculated using the instantaneous value of the three-phase current at the end. Based on the inductance value of the neutral point reactor and the rate of change of the instantaneous value of the self-generated zero-sequence current at the end of the reactor within the sliding window, calculate the instantaneous voltage value across the neutral point reactor within the sliding window. A voltage vector is constructed using the voltage difference between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the neutral point reactor. Based on Ohm's law and the least squares method, the equivalent resistance and equivalent inductance of the reactor are calculated using the current matrix and voltage vector. When the equivalent resistance value is greater than the resistance threshold value and the equivalent inductance value is less than the inductance threshold value, and this condition is maintained for a set duration, the reactor inter-turn fault triggers the protection action.

2. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 1, characterized in that, The length of the sliding window is half a power frequency cycle, and the sliding window contains... Each discrete sampling time.

3. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 2, characterized in that, Based on the current sampling time The sliding window is The current matrix A is as follows: In the formula, , ... This represents the instantaneous value of the three-phase current at the beginning of the sliding window. , ... This represents the rate of change of the instantaneous values ​​of the three-phase currents at the beginning of the sliding window.

4. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 3, characterized in that, Utilization and sampling time The instantaneous values ​​of the three-phase current at the beginning of two adjacent sampling times are used to calculate the sampling time. The rate of change of the instantaneous values ​​of the three-phase currents at the beginning of the circuit satisfies the following relationship: ， In the formula, The time interval between two adjacent sampling times.

5. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 1, characterized in that, In the formula, This is the instantaneous value of the zero-sequence current generated at the end of the reactor. , , These are the instantaneous values ​​of the phase currents A, B, and C at the end of the reactor, respectively. The instantaneous value of the three-phase current at the end of the reactor within the sliding window is , , ... , The instantaneous value of the zero-sequence current generated at the end of the reactor within the sliding window is... , , ... , .

6. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 5, characterized in that, Utilization and sampling time Calculate the instantaneous value of the self-generated zero-sequence current at the reactor terminal at two adjacent sampling times. The rate of change of the instantaneous value of the self-generated zero-sequence current at the end of the reactor satisfies the following relationship: ， In the formula, Sampling time The rate of change of the instantaneous value of the self-generated zero-sequence current at the reactor terminal. , Sampling time The instantaneous values ​​of the self-generated zero-sequence current at the reactor terminal at two adjacent sampling times. The time interval between two adjacent sampling times.

7. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 6, characterized in that, The instantaneous voltage across the neutral point reactance satisfies the following relationship: ， In the formula, Sampling time The instantaneous value of the voltage across the neutral point reactance. This is the inductance value of the neutral point reactance of the reactor.

8. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 7, characterized in that, The voltage vector is as follows: In the formula, , ... It is the voltage difference between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the neutral point reactor.

9. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 8, characterized in that, Sampling time The voltage difference satisfies the following relationship: ， In the formula, Sampling time within the sliding window The voltage difference between the instantaneous voltage across the reactor and the instantaneous voltage across the neutral point reactor. Sampling time within the sliding window The instantaneous value of the voltage across the reactor. Sampling time within the sliding window The instantaneous value of the voltage across the neutral point reactance.

10. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 1, characterized in that, The equivalent resistance and equivalent inductance of the reactor are as follows: In the formula, , These are the equivalent resistance and equivalent inductance values ​​of the reactor, respectively. A is the current matrix, and B is the voltage vector.

11. The reactor time-domain inter-turn protection method based on resistance-inductance parameter identification according to claim 1, characterized in that, Resistance threshold The equivalent resistance value of the reactor during normal operation is multiplied by the reliability factor, and the inductance threshold value is... The value is the equivalent inductance of the reactor during normal operation multiplied by the reliability factor, where the reliability factor ranges from [value missing]. The set duration value range is: ms.

12. A time-domain inter-turn protection system for reactors based on resistance-inductance parameter identification, used to implement the time-domain inter-turn protection method for reactors based on resistance-inductance parameter identification as described in any one of claims 1 to 11, characterized in that, include: The current matrix module is used to obtain the instantaneous values ​​of the first-phase three-phase current and the last-phase three-phase current within the sliding window of the reactor; and to construct the current matrix using the instantaneous values ​​of the first-phase three-phase current and the rate of change of the first-phase three-phase current. The voltage vector module is used to calculate the instantaneous value of the self-generated zero-sequence current at the end of the reactor using the instantaneous value of the three-phase current at the end; to calculate the instantaneous value of the voltage across the neutral point reactor within the sliding window based on the inductance value of the neutral point reactor and the rate of change of the instantaneous value of the self-generated zero-sequence current at the end of the reactor within the sliding window; and to construct a voltage vector based on the voltage difference between the instantaneous voltage across the reactor within the sliding window and the instantaneous voltage across the neutral point reactor. The resistance and inductance parameter identification module is used to calculate the equivalent resistance and equivalent inductance of the reactor based on Ohm's law and the least squares method, using the current matrix and voltage vector. The inter-turn protection module is used to determine that an inter-turn fault in the reactor triggers protection action when the equivalent resistance value is greater than the resistance threshold value and the equivalent inductance value is less than the inductance threshold value, and this condition is maintained for a set duration.

13. A terminal, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1-11.

14. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1-11.

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