A dry-type reactor turn-to-turn short circuit fault monitoring method and system

Abstract

The application discloses a kind of dry-type reactor turn-to-turn short-circuit fault monitoring method and system, method includes the following steps: S1, obtains the zero sequence voltage 3V0 on the bus of dry-type reactor;S2, obtains the evaluation current I0 of the loop where dry-type reactor is located diff ;S3, obtains the zero sequence current and negative sequence current of each phase of dry-type reactor, obtains the phase angle difference between each phase zero sequence current and negative sequence current;S4, according to zero sequence voltage 3V0, evaluation current I0 diff And phase angle difference judges whether each phase of dry-type reactor occurs turn-to-turn short-circuit fault.The application has the advantages of high fault monitoring sensitivity.

Description

TECHNICAL FIELD

[0001] The present application mainly relates to the technical field of dry-type air-core reactor, and particularly relates to a dry-type reactor turn-to-turn short-circuit fault monitoring method and system. BACKGROUND

[0002] The dry-type air-core reactor has the advantages of small loss, stable parameters and simple maintenance, and is more and more widely applied in power systems. As a component of reactive power compensation equipment, the dry-type air-core reactor is often used in outdoor environment. For the regions with complex operating environment, the dry-type air-core reactor may be subject to short circuit, fire and other faults under the action of multiple stresses. According to relevant data, most of the turn-to-turn short-circuit insulation faults of the reactor originate from the damage of the local insulation of the coil, which further causes the coil to be damp, the local discharge to be enhanced, the local overheating, and finally the coil insulation to be completely destroyed. Considering the outdoor hot and humid operating environment of the reactor, the surface insulation of the reactor will inevitably be deteriorated to a certain extent with the increase of service time, forming a small local discharge. With the development of the local discharge, the small local discharge may evolve into branch discharge, and then cause the turn-to-turn short circuit.

[0003] Compared with the oil-filled reactor, the dry-type air-core reactor does not have mechanical protection devices and gas monitoring to detect turn-to-turn short-circuit faults, but the dry-type air-core reactor does not have such protection devices and can only rely on simple directional grounding overcurrent to detect such faults.

[0004] The turn-to-turn short-circuit fault process of the dry-type air-core reactor develops rapidly and can cause great harm to the reliability of the power system, so fault diagnosis is very important. However, the current fault diagnosis methods for the dry-type air-core reactor at home and abroad still mainly rely on periodic power-off maintenance. These methods do not have timeliness and often lead to the emergence of the time of the fault state in advance or lag, causing waste of manpower and financial resources or leaving safety hazards. The research on the fault diagnosis of the dry-type air-core reactor is currently mainly divided into magnetic field detection, temperature detection and electrical quantity detection. The magnetic field and temperature detection methods are often greatly affected by the environment, rely on external facilities, and have poor sensitivity and stability. SUMMARY

[0005] In view of the technical problems in the prior art, the present application provides a dry-type reactor turn-to-turn short-circuit fault monitoring method and system with high sensitivity.

[0006] To solve the above technical problems, the technical scheme provided by the present application is as follows:

[0007] A dry-type reactor turn-to-turn short-circuit fault monitoring method, comprising the steps of:

[0008] S1, acquiring a zero sequence voltage 3V0 on a bus of the dry-type reactor;

[0009] S2, obtaining an evaluation current I0 of a loop where the dry-type reactor is located diff ;

[0010] S3, obtaining zero sequence currents and negative sequence currents of each phase of the dry-type reactor, and obtaining a phase angle difference between the zero sequence currents and the negative sequence currents of each phase;

[0011] S4, judging whether a turn-to-turn short circuit fault occurs in each phase of the dry-type reactor according to the zero sequence voltage 3V0, the evaluation current I0 diff and the phase angle difference.

[0012] Preferably, the evaluation current I0 diff in step S2 is calculated by the following formula:

[0013]

[0014] In the formula, CTR is a ratio of a current transformer; PTR is a ratio of a potential transformer; I0 is a zero sequence current of the measured reactor; V0 is a zero sequence voltage of the measured reactor; wherein R Lim is a calculation coefficient.

[0015] Preferably, the calculation coefficient R Lim is calculated by the following formula:

[0016]

[0017] In the formula, V0 ref is a voltage value of the reactor before the fault; I0 ref is a current value of the reactor before the fault.

[0018] Preferably, in step S3, the calculation formula of the phase angle difference is as follows:

[0019] θ fault = θ I0 - θ I2 (3)

[0020] In the formula, θ fault is the phase angle difference; θ I0 is a phase angle of the zero sequence current flowing through the A phase when a turn-to-turn short circuit occurs; and θ I2 is a phase angle of the negative sequence current flowing through the A phase.

[0021] Preferably, the specific process of step S4 is as follows:

[0022] When the zero sequence voltage 3V0 = 0, the evaluation current I0 diff is greater than a preset standard value I0 diff_ref , the phase angle difference is within a preset threshold, and the lockout 86 is in a locked state, it is judged that a turn-to-turn short circuit fault occurs in the corresponding phase.

[0023] Preferably, in step S4, the corresponding inter-turn short circuit fault signal is output after a preset time delay.

[0024] Preferably, the preset threshold value is -5 to +5 degrees.

[0025] The application further discloses a computer program product comprising a computer program which, when executed by a processor, performs the steps of the method as described above.

[0026] The application further discloses a computer readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of the method as described above.

[0027] The application further discloses a computer device comprising a memory and a processor connected to each other, wherein the memory has a computer program stored thereon, and the computer program, when executed by the processor, performs the steps of the method as described above.

[0028] Compared with the prior art, the application has the following advantages:

[0029] The neutral point current change-based dry-type air-core reactor inter-turn short circuit fault monitoring method of the application uses the current change flowing through the neutral point when the dry-type reactor is normally and faultly operated to identify whether a fault occurs; first, whether the zero sequence voltage 3V0 on the bus is zero is measured to determine whether the fault occurring at the moment is an internal fault; then, the evaluation current I0 diff is calculated, the evaluation current is compared with the pickup current, the phase angle difference between the zero sequence current and the negative sequence current is calculated, and finally, 3V0, the difference between the evaluation current and the pickup current, the phase angle difference between the negative sequence current and the zero sequence current, and the lockout86 are subjected to logical AND, and if the logical signal is true, it indicates that the fault is an inter-turn short circuit fault.

[0030] The fault detection method based on the neutral point current change has higher sensitivity than general methods, can escort the safe and stable operation of the dry-type air-core reactor, and is also applicable to the inter-turn short circuit fault monitoring of the dry-type shunt reactor. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a circuit diagram of the reactor and the bus of the application.

[0032] Figure 2 It is a Norton equivalent change diagram of Figure 1 .

[0033] Figure 3 It is a fault judgment logic diagram of phase A in the application.

[0034] Figure 4This is a flowchart of an embodiment of the dry-type reactor inter-turn short-circuit fault monitoring method of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 4 As shown, the method for monitoring inter-turn short-circuit faults in a dry reactor according to an embodiment of the present invention includes the following steps:

[0037] S1. Obtain the zero-sequence voltage 3V0 on the bus of the dry-type reactor; determine whether the fault is internal or external by checking if 3V0 equals 0; where 3V0 = 0 indicates an internal fault, and 3V0 ≠ 0 indicates an external fault.

[0038] S2. Obtain the evaluation current I0 of the circuit containing the dry-type reactor. diff By evaluating the current I0 diff Compared with the standard value I0 diff_ref (Experienced values) are compared to determine whether a fault has occurred;

[0039] S3. Obtain the zero-sequence current and negative-sequence current of each phase of the dry-type reactor, and obtain the phase angle difference between the zero-sequence current and negative-sequence current of each phase; determine which phase has a fault by comparing the phase angle difference with a preset threshold.

[0040] S4. Evaluate the current I0 based on the zero-sequence voltage 3V0. diff The phase angle difference is used to determine whether an inter-turn short circuit fault has occurred in each phase of the dry-type reactor; the combination of the above conditions is used to determine which phase of the reactor has a fault.

[0041] Specifically, Figure 1 This is the circuit diagram of the reactor and busbar. First, the zero-sequence voltage 3V0 on the busbar is used to determine whether the fault occurring is an internal fault of the dry-type reactor. This is because for an independently operating dry-type reactor, changes in 3V0 on the busbar are caused by changes in the external power system, not by small changes caused by an internal fault. This is because during an internal fault, 3V0 is 0, and current flows through R... Lim The current in the circuit and the current in the dry-type reactor are both I0. The relay resistance is not zero, but no current flows through it. The left power supply is open-circuited because 3V0 is zero. This is because, for a three-phase system, the zero-sequence voltage V0 on the bus only occurs due to three-phase imbalance, not due to minor internal faults in the reactor. Therefore, 3V0 can be used as a criterion for faults inside and outside the reactor. That is, for a three-phase system, Figure 2The left side of the power supply is 0, and the reason can only be that three-phase imbalance occurs outside the reactor, and will not be caused by internal small faults of the reactor (including turn-to-turn short circuit), for example, only when three-phase imbalance occurs outside the reactor, 3v0 will not be 0, and the rest will be 0.

[0042] That is, for a three-phase system, the occurrence of zero sequence voltage (i.e. 3V0) on the bus is likely to be a single-phase ground fault, unbalanced load (usually, the zero sequence voltage caused by unbalanced load is small and can be ignored), transformer winding insulation damage, system configuration, etc. For a dry-type reactor running independently, internal turn-to-turn short circuit and other small faults will not cause zero sequence voltage on the bus. However, when a serious fault occurs on the bus, it may cause zero sequence current and zero sequence voltage inside the dry-type reactor. At this time, the reactor behaves the same as when a turn-to-turn short circuit occurs. Therefore, in order to distinguish whether the turn-to-turn short circuit inside the reactor is caused by external faults, a criterion for internal and external faults 3V0 is set.

[0043] In step S2, the circuit diagram of the reactor and the bus Figure 1 is changed to the Norton equivalent Figure 2 , and the calculation formula of the evaluation current can be obtained by analyzing the circuit. The evaluation current I0 diff can be calculated by Figure 2 , Figure 2 The leftmost current source in the circuit is open-circuited because 3V0 is zero, so the evaluation current can be calculated by the following formula:

[0044]

[0045] CTR is the ratio of the current transformer; PTR is the ratio of the potential transformer; I0 is the measured reactor zero sequence current; V0 is the measured reactor zero sequence voltage.

[0046] where R Lim is the calculation coefficient, and the calculation formula is as follows:

[0047]

[0048] V0 ref is the voltage value of the reactor before the fault; I0 ref is the current value of the reactor before the fault; and a standard value I0 diff_ref is set, which is usually an empirical value.

[0049] In step S3, when determining which phase the fault occurred in, the zero-sequence current of the reactor is independent of the reference frame, while the negative-sequence current changes depending on the reference frame. For example, if an inter-turn short circuit occurs in phase A, and the zero-sequence and negative-sequence currents are calculated with phase A as the reference frame, their phase angles will be approximately the same. However, when the fault occurs in phase B, if calculated using the same reference frame, the negative-sequence current deviates from the zero-sequence current by approximately 120°. Therefore, the formula for identifying the faulty phase is shown in Equation 3:

[0050] θ fault =θ I0 -θ I2 (3)

[0051] In the formula: θ fault The phase angle difference; θ I0 θ is the phase angle of the zero-sequence current flowing through phase A during an inter-turn short circuit. I2 The phase angle is the negative sequence current flowing through phase A.

[0052] Taking phase A as an example, when an inter-turn short-circuit fault occurs, the phase angle difference θ fault The value should be between -5 and +5 degrees. If the calculated value is within this range, it can be determined that the fault is occurring on phase A.

[0053] In step S4, as Figure 3 As shown, a logical AND operation is performed based on the comparison results of the evaluated current and the picked-up current, 3V0, the phase angle difference, and the lockout86 lockout signal. The result of this logical AND operation determines which phase is faulty. Lockout86 is the relay's own lockout signal, normally set to 0, to prevent false tripping due to relay malfunction. A time delay is introduced after the difference between the evaluated current and the picked-up current to allow the reactor's external fault protection function to activate first.

[0054] After a phase A fault occurs, the phase angle difference between the zero-sequence and negative-sequence currents is 0°±5°. 3V0 is measured from the bus to ensure that there is no external fault.

[0055] Taking an inter-turn fault in phase A of a reactor as an example, when the internal and external fault discrimination quantity 3V0 is 0, the difference between the assessed current and the pickup current is greater than the preset value, θ fault If the value is between -5 and +5 and lockout86 is in the locked state, it indicates that an inter-turn short circuit fault has occurred on phase A of the reactor. In other words, if all the above conditions are met simultaneously, a trip signal will be issued.

[0056] The neutral point current change based dry-type air-core reactor turn-to-turn short circuit fault monitoring method of the application uses the current change flowing through the neutral point of the dry-type reactor in normal and fault operation to identify whether a fault occurs; first, whether the zero sequence voltage 3V0 on the bus is zero is measured to determine whether the fault occurring at this time is an internal fault; then, the evaluation current I0 diff and the pickup current are compared; the phase angle difference of the zero sequence current and the negative sequence current is calculated; finally, 3V0, the difference between the evaluation current and the pickup current, the phase angle difference of the zero sequence current and the negative sequence current, and the lockout86 are logically ANDed, and if the logic signal is true, it indicates that the fault is a turn-to-turn short circuit fault.

[0057] The fault detection method based on neutral point current change of the application has higher sensitivity than general methods, can escort the safe and stable operation of the dry-type air-core reactor, and is also suitable for turn-to-turn short circuit fault monitoring of dry-type shunt reactors.

[0058] The application further discloses a computer program product comprising a computer program which, when executed by a processor, performs the steps of the above method. The application further discloses a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the above method. The application further discloses a dry-type reactor turn-to-turn short circuit fault monitoring system comprising a memory and a processor connected to each other, wherein the memory stores a computer program which, when executed by the processor, performs the steps of the above method. The product, medium and system of the application correspond to the above method and have the same advantages as the above method.

[0059] The present application can realize all or part of the processes in the above-mentioned embodiment methods, and can also be completed by computer program instruction related hardware. The computer program can be stored in a computer readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned method embodiment can be realized. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms, etc. The computer readable storage medium includes any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc. The memory is used to store computer programs and / or modules. The processor realizes various functions by running or executing the computer programs and / or modules stored in the memory, and calling the data stored in the memory. The memory can include high-speed random access memory, and can also include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one magnetic disk storage device, flash memory device, or other volatile solid-state storage device, etc.

[0060] The above is only the preferred embodiment of the present application, and the protection scope of the present application is not limited to the above-mentioned embodiment. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that some improvements and refinements made by ordinary skilled in the art without departing from the principles of the present application shall be considered as the protection scope of the present application.

Claims

1. A method for monitoring inter-turn short-circuit faults in a dry-type reactor, characterized in that, Including the following steps: S1. Obtain the zero-sequence voltage 3 on the busbar of the dry-type reactor. ; S2. Obtain the evaluation current of the circuit containing the dry-type reactor. ; S3. Obtain the zero-sequence current and negative-sequence current of each phase of the dry-type reactor, and obtain the phase angle difference between the zero-sequence current and negative-sequence current of each phase; S4, based on zero-sequence voltage 3 Evaluation of current The phase angle difference is used to determine whether an inter-turn short circuit fault has occurred in each phase of the dry-type reactor; Evaluation current in step S2 The calculation is performed using the following formula: （1） In the formula: The ratio of current transformers; The ratio of the potential transformers; The zero-sequence current of the reactor under test; The zero-sequence voltage of the reactor under test; where To calculate the coefficients; The calculation coefficients The calculation formula is as follows: （2） In the formula: The reactor voltage value before the fault; This is the reactor current value before the fault.

2. The method for monitoring inter-turn short-circuit faults in dry-type reactors according to claim 1, characterized in that, In step S3, the formula for calculating the phase angle difference is: （3） In the formula: This is the phase angle difference; The phase angle is the zero-sequence current flowing through phase A during an inter-turn short circuit. The phase angle is the negative sequence current flowing through phase A.

3. The method for monitoring inter-turn short-circuit faults in dry-type reactors according to claim 1, characterized in that, The specific process of step S4 is as follows: When the zero-sequence voltage 3 is satisfied =0, Evaluate current Greater than the preset standard value If the phase angle difference is within the preset threshold and lockout86 is in the locked state, then it is determined that an inter-turn short circuit fault has occurred in the corresponding phase.

4. The method for monitoring inter-turn short-circuit faults in dry-type reactors according to claim 3, characterized in that, In step S4, the corresponding inter-turn short-circuit fault signal is output only after a preset delay time.

5. The method for monitoring inter-turn short-circuit faults in dry-type reactors according to claim 3, characterized in that, The preset threshold is -5 to +5 degrees.

6. A computer program product, comprising a computer program, characterized in that, The computer program is executed by the processor to perform the steps of the method as described in any one of claims 1-5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program, when run by a processor, performs the steps of the method as described in any one of claims 1-5.

8. A dry-type reactor inter-turn short-circuit fault monitoring system, comprising a memory and a processor interconnected, wherein the memory stores a computer program, characterized in that, The computer program, when run by a processor, performs the steps of the method as described in any one of claims 1-5.

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