Online detection apparatus and method for turn-to-turn short circuit in injection generator outlet pt

Abstract

Disclosed are an online detection apparatus and method for a turn-to-turn short circuit in an injection generator outlet PT. The apparatus comprises a voltage source, a band-pass filter, a switch, a resistance voltage divider, a current transformer and a microcomputer system, wherein the voltage source is connected to a secondary side of a generator outlet PT through the band-pass filter and the switch in sequence; the resistance voltage divider is connected in parallel to the secondary side of the generator outlet PT; the current transformer is connected in series to a power source loop; and the microcomputer system is connected to outputs of the resistance voltage divider and the current transformer, and is used for processing and analyzing data, determining whether there is a fault in the outlet PT, and raising an alarm. The present invention solves the problem in existing detection methods for the insulation state between PT turns of generators necessarily being shut down, which is not conducive to the timely and effective detection of insulation defects, and thus the efficiency is low and the accuracy is poor.

Description

An online detection device and method for inter-turn short circuit of a PT at the outlet of an injection generator. Technical Field

[0001] This invention belongs to the field of power detection and protection technology, and specifically relates to an online detection device and method for inter-turn short circuit of a power supply transformer (PT) at the outlet of an injection generator. Background Technology

[0002] The generator outlet PT (Potential Transformer) plays a crucial role in metering, excitation, and protection of the generator outlet voltage. However, due to factors such as operating environment and manufacturing processes, unplanned generator shutdowns caused by inter-turn short circuits in the generator outlet PT occur frequently. Literature review results indicate that between 2010 and 2020, more than 50 inter-turn short circuit faults occurred in the primary winding of generator outlet PTs in several provinces. Therefore, researching online detection technology for inter-turn short circuits in generator outlet PTs can improve the detection effect of insulation faults in generator outlet PTs, significantly reduce the risk of abnormal generator shutdowns, and is of great significance for ensuring safe power production and the economic benefits of power generation enterprises.

[0003] Existing methods for detecting inter-turn short-circuit faults in generator outlet PTs mainly include DC resistance measurement, no-load current measurement, and induced withstand voltage testing. While these traditional methods are adequate for detecting main insulation defects in the generator outlet PTs, they suffer from poor sensitivity in detecting inter-turn short-circuit faults. Furthermore, the inspection of the inter-turn insulation condition of the generator outlet PTs must be performed after the generator is shut down, which is detrimental to the timely and effective detection of insulation defects, resulting in low efficiency and poor accuracy.

[0004] Chinese Patent Publication No. CN112526306A discloses a generator outlet-side voltage transformer insulation status monitoring system, comprising: sensors for detecting the power frequency current signal of each winding, the high-frequency current signal of the primary winding, and the power frequency output voltage signal of the winding; a data conditioning module for conditioning the sensor signals and converting them into an AD input voltage range; a data acquisition module for simultaneously acquiring the conditioned sensor signals through different channels; and a data analysis and processing module for monitoring the insulation status of the generator outlet-side voltage transformer based on the change in excitation current and the change in the phase angle difference between the excitation current vector and the power frequency output voltage vector. This invention involves multiple sensors and modules, including a data conditioning module, a data acquisition module, and a data analysis and processing module. This complexity may lead to high design, installation, and maintenance costs; and when the phase angle difference between the excitation current and the power frequency output voltage is small, it may lead to misjudgment of the fault type. Summary of the Invention

[0005] This invention provides an online detection device and method for inter-turn short circuit of a PT outlet in an injection-type generator, aiming to solve the problems of existing detection methods for the inter-turn insulation status of PTs requiring generator shutdown, which is not conducive to timely and effective detection of insulation defects, and is characterized by low efficiency and poor accuracy.

[0006] To solve the above-mentioned technical problems, the present invention provides an online detection device for inter-turn short circuit of a PT at the outlet of an injection generator, comprising a voltage source, a bandpass filter, a switch, a resistor divider, a current transformer, and a microcomputer system.

[0007] The voltage source is connected to the secondary side of the generator output PT via a bandpass filter and a switch in sequence; the resistor divider is connected in parallel to the secondary side of the generator output PT; the current transformer is connected in series in the power supply circuit of the voltage source; the microcomputer system is connected to the output of the resistor divider and the current transformer, and is used to process and analyze data, determine whether there is a fault in the output PT and issue an alarm.

[0008] Preferably, the bandpass filter is a passive filter with the same center frequency as the voltage source, a bandwidth requirement of 29~31Hz, and an out-of-band rejection ratio requirement of greater than -20dB / octave.

[0009] Preferably, the measurement frequency range of the resistor voltage divider is DC~1kHz, the voltage range is 0~100V, the voltage division ratio is 20:1, and the accuracy is greater than 0.1%.

[0010] Preferably, the current transformer has a measurement frequency range of 0.1Hz to 10kHz and an accuracy greater than 0.1%.

[0011] Preferably, the microcomputer system is a processing system based on STM32F103, with a sampling frequency of 7.15MHz and a sampling resolution of 1mV.

[0012] On the other hand, the present invention provides an online detection method for inter-turn short circuit of a PT at the outlet of an injection generator, comprising the following steps:

[0013] S1: Connect the generator outlet PT inter-turn short circuit online detection device in parallel to the secondary winding of the generator outlet PT.

[0014] S2: The microcomputer system collects and measures the power frequency voltage amplitude after the generator terminal voltage is converted by the PT through the resistor voltage divider, and determines whether the generator terminal voltage is the rated voltage. If the requirements are met, the switch is closed.

[0015] S3: The microcomputer system acquires and measures the AC voltage signal of the power supply circuit through a resistor divider. The power supply circuit current signal is collected and measured through a current transformer. .

[0016] S4: The microcomputer system calculates the power supply circuit impedance value based on the collected voltage and current signals. If the power supply circuit impedance Less than the set value If this occurs, the microcomputer system will issue a short circuit alarm signal between the generator outlet PT turns.

[0017] Preferably, the set value The specific calculation formula is as follows:

[0018]

[0019] In the formula, The impedance value is calculated from the primary winding of the generator outlet PT to the secondary side. This is the secondary load impedance; This is the reliability coefficient.

[0020] In another aspect, the present invention also provides an electronic device, the electronic device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the online detection method for inter-turn short circuit of the injection generator outlet PT as described in any embodiment of the present invention.

[0021] In another aspect, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the online detection method for inter-turn short circuit of the injection generator outlet PT as described in any embodiment of the present invention.

[0022] Compared with the prior art, the present invention has the following technical effects:

[0023] The online detection device and method for inter-turn short circuit of the generator outlet PT provided by the present invention can realize online detection of inter-turn short circuit of the generator outlet PT, and has a simple structure and high detection sensitivity, which can meet the needs of online detection of power equipment. Attached Figure Description

[0024] Figure 1 is an overall structural diagram of the online short-circuit detection device for inter-turn short circuit at the outlet PT of the injection generator described in this invention.

[0025] Figure 2 is an equivalent schematic diagram of the short circuit between turns of the generator outlet PT as described in this invention.

[0026] In the diagram: 1. Voltage source; 2. Bandpass filter; 3. Switch; 4. Resistor voltage divider; 5. Current transformer; 6. Microcomputer system. Embodiments of the present invention

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present application and with reference to the accompanying drawings.

[0028] Example 1

[0029] This embodiment provides an online detection device for inter-turn short circuit of a PT at the outlet of an injection generator, as shown in Figure 1. It includes a voltage source 1, a bandpass filter 2, a switch 3, a resistor divider 4, a current transformer 5, and a microcomputer system 6.

[0030] The voltage source 1 is connected to the secondary side of the generator output PT via a bandpass filter 2 and a switch 3. The secondary side of the generator output PT converts the high-voltage side voltage to the low-voltage side and supplies it to the measurement, protection and monitoring system. The resistor divider 4 is connected in parallel to the secondary side of the generator output PT. The current transformer 5 is connected in series in the power supply circuit of the voltage source 1. The microcomputer system 6 is connected to the output of the resistor divider 4 and the current transformer 5 and is used to process and analyze data, determine whether there is a fault in the output PT and issue an alarm.

[0031] In a preferred embodiment of this invention, the voltage source 1 is a sinusoidal AC power supply with a frequency of 30Hz and an amplitude of 5V. The switch 3 is a controllable element, controlled by the microcomputer system 6 to turn on and off.

[0032] In a preferred embodiment of this invention, the bandpass filter 2 is a passive filter with the same center frequency as the voltage source 1, a bandwidth requirement of 29~31Hz, and an out-of-band rejection ratio requirement of greater than -20dB / octave, in order to increase the signal-to-noise ratio and improve the accuracy of the measurement.

[0033] In a preferred embodiment of this invention, the resistor voltage divider 4 has a measurement frequency range of DC to 1 kHz, a voltage range of 0 to 100 V, a voltage division ratio of 20:1, and an accuracy greater than 0.1%.

[0034] In a preferred embodiment of this invention, the current transformer 5 has a measurement frequency range of 0.1Hz to 10kHz and an accuracy greater than 0.1%.

[0035] In a preferred embodiment of this invention, the microcomputer system 6 is a processing system based on STM32F103, with a sampling frequency of 7.15MHz and a sampling resolution of 1mV.

[0036] Example 2

[0037] Accordingly, this embodiment provides an online detection method for inter-turn short circuit of the PT at the outlet of an injection generator. The method is based on the online detection device for inter-turn short circuit of the PT at the outlet of the injection generator described in Embodiment 1, and includes the following steps:

[0038] S1: Connect the generator outlet PT inter-turn short circuit online detection device in parallel to the secondary winding of the generator outlet PT, wherein the secondary winding of the generator outlet PT refers to the circuit part that converts high voltage to standard low voltage (such as 100V).

[0039] S2: The microcomputer system 6 collects and measures the power frequency voltage amplitude of the generator terminal voltage (i.e., the voltage at the generator output terminal, usually the voltage across the generator stator winding) through the resistor voltage divider 4 and after PT conversion, and determines whether the generator terminal voltage at the generator outlet is the rated voltage. If the requirements are met, the switch is closed.

[0040] S3: The microcomputer system 6 acquires and measures the AC voltage signal of the power supply circuit through the resistor voltage divider 4. The current signal of the power supply circuit is collected and measured through current transformer 5. .

[0041] S4: The microcomputer system 6 calculates the power supply circuit impedance value based on the collected voltage and current signals. If the power supply circuit impedance Less than the set value Then, the microcomputer system 6 issues a short-circuit alarm signal between the generator outlet PT turns. The circuit impedance value... The specific calculation formula is as follows:

[0042]

[0043] In the formula, The signal is the AC voltage signal of the loop. This is the loop current signal.

[0044] This embodiment further explains the online detection method for inter-turn short circuits of the generator outlet PT. As shown in Figure 2, after an inter-turn short circuit occurs at the generator outlet PT, the calculated circuit impedance value is viewed from the secondary winding. The theoretical value consists of three parts connected in parallel: the impedance value of the primary winding referred to the secondary winding. Secondary load impedance The impedance value after referring the inter-turn short circuit portion of the primary winding to the secondary side The impedance value of the primary winding referred to the secondary winding. Secondary load impedance The impedance value after referring the inter-turn short circuit portion of the primary winding to the secondary side These are inherent parameters of the power system.

[0045] As a preferred embodiment of this example, the set value The specific calculation formula is as follows:

[0046]

[0047] In the formula, The impedance value is calculated from the primary winding of the generator outlet PT to the secondary side. This is the secondary-side load impedance; This is the reliability coefficient.

[0048] Due to the impedance value of the inter-turn short circuit section of the primary winding of the generator outlet PT Very small, the calculated value of the loop impedance after the generator outlet PT inter-turn short circuit. It is much smaller than the set value. This triggers the microcomputer system 6 to issue a short-circuit alarm signal between the generator outlet PT turns.

[0049] It should be noted that: to prevent false triggering of the generator outlet PT inter-turn short circuit alarm signal, the set value is... The reliability factor needs to be considered during the calculation. Generally, the reliability factor is... The value range is 0.5 to 0.7.

[0050] Example 3

[0051] This embodiment provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the online detection method for inter-turn short circuit of the injection generator outlet PT as described in any embodiment of the present invention.

[0052] Example 4

[0053] This embodiment provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the online detection method for inter-turn short circuit of the injection generator outlet PT as described in any embodiment of the present invention.

[0054] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent the existence of A alone, A and B simultaneously, or B alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, at least one of a, b, and c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0055] Those skilled in the art will recognize that the units and algorithm steps described in the embodiments disclosed herein can be implemented using electronic hardware, computer software, or a combination of electronic hardware and software. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0056] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0057] In the several embodiments provided in this application, any function, if implemented as a software functional unit and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0058] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An online detection device for inter-turn short circuit of a PT at the outlet of an injection generator, characterized in that, It includes a voltage source (1), a bandpass filter (2), a switch (3), a resistor divider (4), a current transformer (5), and a microcomputer system (6); The voltage source (1) is connected to the secondary side of the generator outlet PT in sequence through the bandpass filter (2) and the switch (3); the resistor divider (4) is connected in parallel to the secondary side of the generator outlet PT; the current transformer (5) is connected in series in the power supply circuit of the voltage source (1); the microcomputer system (6) is connected to the output of the resistor divider (4) and the current transformer (5) to process and analyze data, determine whether there is a fault in the outlet PT and issue an alarm.

2. The online detection method for inter-turn short circuit of the PT at the outlet of an injection generator according to claim 1, characterized in that, The bandpass filter (2) is a passive filter with the same center frequency as the voltage source (1). The bandwidth requirement is 29~31Hz, and the out-of-band rejection ratio requirement is greater than -20dB / octave.

3. The online detection method for inter-turn short circuit of the injection generator outlet PT according to claim 1, characterized in that, The measurement frequency range of the resistor voltage divider (4) is DC~1kHz, the voltage range is 0~100V, the voltage division ratio is 20:1, and the accuracy is greater than 0.1%.

4. The online detection method for inter-turn short circuit of the injection generator outlet PT according to claim 1, characterized in that, The current transformer (5) has a measurement frequency range of 0.1Hz to 10kHz and an accuracy greater than 0.1%.

5. The online detection method for inter-turn short circuit of the PT at the outlet of an injection generator according to claim 1, characterized in that, The microcomputer system (6) is a processing system based on STM32F103, with a sampling frequency of 7.15MHz and a sampling resolution of 1mV.

6. A method for online detection of inter-turn short circuit in the outlet PT of an injection generator, characterized in that, The method is implemented based on the online inter-turn short circuit detection device for the injection generator outlet PT according to any one of claims 1-5, and includes the following steps: S1: Connect the generator outlet PT inter-turn short circuit online detection device in parallel to the secondary winding of the generator outlet PT; S2: The microcomputer system (6) collects and measures the power frequency voltage amplitude after the generator terminal voltage is converted by the PT through the resistor voltage divider (4), and determines whether the generator terminal voltage at the generator outlet is the rated voltage. If the requirements are met, the switch (3) is closed. S3: The microcomputer system (6) collects and measures the AC voltage signal of the power supply circuit through the resistor divider (4). The power supply circuit current signal is collected and measured through the current transformer (5). ； S4: The microcomputer system (6) calculates the power supply loop impedance value based on the collected voltage and current signals. If the power supply circuit impedance Less than the set value Then the microcomputer system (6) will issue a short circuit alarm signal between the generator outlet PT turns.

7. The online detection method for inter-turn short circuit of the injection generator outlet PT according to claim 6, characterized in that, The set value The specific calculation formula is as follows: In the formula, The impedance value is calculated from the primary winding of the generator outlet PT to the secondary side. This is the secondary load impedance; This is the reliability coefficient.

8. An electronic device, the electronic device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, when the processor executes the computer program, it implements the online detection method for inter-turn short circuit of the injection generator outlet PT as described in any one of claims 6 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the online detection method for inter-turn short circuit of the injection generator outlet PT as described in any one of claims 6 to 7.

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