WO2020224536A1 - 变压器数字式瓦斯保护与油流涌动监测一体化装置及方法 - Google Patents

变压器数字式瓦斯保护与油流涌动监测一体化装置及方法 Download PDF

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WO2020224536A1
WO2020224536A1 PCT/CN2020/088306 CN2020088306W WO2020224536A1 WO 2020224536 A1 WO2020224536 A1 WO 2020224536A1 CN 2020088306 W CN2020088306 W CN 2020088306W WO 2020224536 A1 WO2020224536 A1 WO 2020224536A1
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module
oil flow
digital
protection
transformer
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PCT/CN2020/088306
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English (en)
French (fr)
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闫晨光
朱述友
周贤
罗宝锋
张保会
高琰
徐雅
周贤武
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北京中瑞和电气有限公司
西安交通大学
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Publication of WO2020224536A1 publication Critical patent/WO2020224536A1/zh

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  • the invention belongs to the field of electric power systems, and relates to an integrated device and method for transformer digital gas protection and oil flow surge monitoring, and is used for reliably, quickly and sensitively identifying internal faults in the oil tank of an oil-immersed power transformer.
  • the transformer occupies a pivotal position in the power system. Its stable operation is an important prerequisite to ensure the reliable transmission, flexible distribution, and safe use of the entire power system.
  • the transformer body may be damaged due to the internal fault pressure impact, and even cause an explosion or fire accident; on the other hand, once the protection device is in a non-internal fault condition If there is a malfunction in the next stage, the economic loss caused by the power outage will be inevitable.
  • transformer protection With high reliability, fast action speed and high sensitivity.
  • the internal fault process of the transformer is accompanied by three main characteristics: phase current increase, differential current increase, and fault gas generation.
  • relay protection workers have designed over-current protection, differential protection, and non-electricity protection.
  • the subsequent changes in non-electric characteristics such as oil flow, temperature, and pressure in the transformer during the generation of faulty gas are the specific manifestations of the conversion of faulty electrical energy into internal energy, kinetic energy, potential energy and other forms of energy.
  • For weak internal faults of the transformer due to the small fault power, it is often difficult to distinguish sensitively only by power protection.
  • non-electricity characteristics such as oil flow surging, temperature rise, and pressure increase inside the transformer tank.
  • transformer protection is often more sensitive than electric quantity protection.
  • power transformers are expensive equipment that integrates windings, cores, insulation, fuel tanks, switches, coolers and other components.
  • the failure form is often manifested as overheating failures of various components: such as overheating between the core silicon steel sheets, burning of windings, melting or burns of tap changer contacts; or mechanical failures: loose core structure, mechanical deformation or collapse of windings, The transformer tank is cracked and leaking.
  • electrical quantity protection is often difficult to reliably distinguish, while non-electric quantity protection based on characteristics such as flow rate, temperature, and pressure can more comprehensively and directly reflect the fault status of the transformer.
  • the German transformer expert Max Buchholz invented the Buchholz relay and installed it on the connecting pipe between the transformer main tank and the oil pillow. It is mainly suitable for those with oil pillows and no gas space on the top of the tank.
  • Large-scale oil-immersed transformer to protect various types of internal faults outside the sensitive area of electrical energy protection, to make up for the shortcomings of electrical energy protection.
  • the gas protection device based on the generation of fault gas inside the transformer broadens the existing ideas of relay protection research, and is widely used in oil-immersed power transformers by virtue of its sensitivity advantages.
  • the oil-filled pressure regulating switch should be equipped with gas protection. When a slight gas or oil level drops in the shell, it should act on the signal instantaneously; when a large amount of gas is produced, it should act to open the circuit breakers on each side of the transformer.
  • relay protection is to screen the fault through the protection criterion after the fault occurs, and send a trip signal to quickly remove the fault, so as to avoid further damage to the system or equipment. Therefore, relay protection action to remove faults is a passive security defense method for power systems and power equipment. Unlike this, the online monitoring device of power equipment can monitor, analyze, and calculate the physical quantities that characterize the operating state of the transformer before a fault occurs, thereby assessing the health status of the equipment, thereby determining whether maintenance operations need to be scheduled, and preventing problems Yu Weiran's role in avoiding equipment failure is an active defense method to improve the safety of transformer operation.
  • the purpose of the present invention is to provide an integrated device and method for transformer digital gas protection and oil flow surge monitoring, which can reliably, quickly and sensitively identify internal faults in the oil tank of an oil-immersed power transformer, and through the monitoring and analysis of transient oil flow In order to evaluate the operating status of the transformer, the integration of protection and online monitoring can be realized.
  • Transformer digital gas protection and oil flow surge monitoring integrated device including: transient oil flow characteristic quantity measurement module, switch input module, signal conditioning and acquisition module and digital core module; among them, transient oil flow characteristic quantity measurement
  • the module is connected with the signal conditioning and acquisition module, and the signal conditioning and acquisition module, switch output module, external communication interface module, man-machine dialogue module, switch output module and data storage module are all connected with the digital core module;
  • the transient oil flow characteristic quantity measurement module is used for real-time and high-speed measurement of the transient oil flow change characteristics inside the transformer oil conservator connection pipe, and output the corresponding analog voltage/current signal;
  • the signal conditioning and acquisition module is used to receive the analog voltage/current signal obtained by the transient oil flow characteristic measurement module, and convert it into a standard digital signal that the digital core module can recognize, and then output the standard digital signal;
  • the switch input module is used to collect the relevant switch signals that need to be ascertained, and output them as high level 1 or low level 0 as the input digital quantity of the digital core module;
  • the digital core module is used to perform protection and monitoring operations after receiving standard digital signals and input digital quantities, complete digital signal processing tasks, and realize the integrated functions of relay protection and online monitoring.
  • a further improvement of the present invention is that the transient oil flow characteristic quantity measurement module is composed of an externally bundled high-frequency ultrasonic flowmeter, a flowmeter transmitter and a communication cable, and the externally bundled high-frequency ultrasonic flowmeter is installed in the transformer oil pillow connection On the pipe, the externally bundled high-frequency ultrasonic flowmeter is connected with the flowmeter transmitter, and the flowmeter transmitter is connected with the communication cable.
  • the further improvement of the present invention is that the measurement frequency of the externally bundled high-frequency ultrasonic flowmeter is above 100 Hz, the measurement error is less than 1%, the working temperature is -30 to 80°C, and the flow rate range is -20 to 20 m/s.
  • the signal conditioning and acquisition module is composed of wiring terminals, a signal conditioning circuit, a low-pass filter, a signal sampling circuit, and an analog-to-digital A/D conversion circuit; the wiring terminals are connected to the signal conditioning circuit, and the signal conditioning circuit is connected to the signal conditioning circuit.
  • the low-pass filter is connected, the low-pass filter is connected to the signal sampling circuit, the signal sampling circuit is connected to the analog-to-digital A/D conversion circuit, and the analog-to-digital A/D conversion circuit is connected to the digital core module; the terminal block is also connected to the communication cable .
  • the digital core module is composed of a bus, a central processing unit, a timer/counter, a random access memory, and a control circuit;
  • the bus includes a data bus, an address bus and a control bus to realize data exchange and operation control;
  • the central processing unit Use single-chip microprocessor, general-purpose microprocessor or digital signal processor to realize digital signal processing;
  • timer/counter is used to provide timing sampling trigger signal, form interruption, protection delay action timing function;
  • random access memory is used to temporarily store temporary Data includes the data information input by the signal conditioning and acquisition module, and the intermediate results of the calculation process;
  • the control circuit realizes the connection and coordination of the entire digital circuit through a complex programmable logic device or a field programmable gate array.
  • a further improvement of the present invention is that it also includes an external communication interface module, a man-machine dialogue module, a switch output module and a data storage module connected to the digital core module;
  • the external communication interface module is used to provide an information channel with a computer communication network and a remote communication network to realize information interaction, data sharing, remote operation and remote maintenance functions;
  • the man-machine dialogue module is used to establish the information connection between the digital protection device and the user, so that the operator can manually operate and debug the protection device and obtain information feedback;
  • the switch output module is used to output the 0 or 1 state to control the on or off of the trip circuit and alarm circuit;
  • the data storage module is used to store data.
  • the external communication interface module includes an IEC 61850 communication interface and a dedicated communication interface for protection functions;
  • the man-machine dialogue module includes a compact keyboard, display, indicator lights, buttons and printer interface;
  • the switch output module is composed of a photoelectric isolation device and an export relay. One end of the photoelectric isolation device is connected to the digital core module, and the other end is connected to the export relay;
  • the data storage module is composed of a main flash memory and a secondary flash memory; the primary and secondary flash memories are used as the main memory and backup memory of the device.
  • a method based on the above-mentioned integrated device for transformer digital gas protection and oil flow surge monitoring includes the following steps:
  • the transient oil flow characteristic quantity measurement module measures the transient oil flow change characteristics inside the transformer oil conservator connection pipe in real time; outputs the corresponding analog voltage/current signal;
  • the signal conditioning and acquisition module receives the analog voltage/current signal obtained by the transient oil flow characteristic measurement module, converts it into a standard digital signal that can be recognized by the digital core module, and then outputs the standard digital signal;
  • the switch input module is used to collect the relevant switch signals that need to be ascertained, and output them as high level 1 or low level 0 as the input digital quantity of the digital core module;
  • the digital core module uses formula (1) to calculate the oil flow action quantity v op (t) at the current time t:
  • T is the length of the data window
  • f is the signal sampling frequency of the acquisition module
  • k re is the protection reliability coefficient
  • v th.1 is the digital gas protection threshold
  • step 5 Determine the size of the operating oil flow v op (t) and the over-current alarm threshold v th.2 . If the operating oil flow is greater than or equal to the over-current alarm threshold v th.2 , that is, equation (4) is established, a transformer over-current warning will be issued , Go to step 7; if the operating oil flow is less than the overcurrent alarm threshold v th.2 , that is, formula (4) is not established, go to step 6;
  • step 8 Perform running self-check in running state, if no device failure is found, return to step 1, re-read the oil flow data velocity v ms (t+1) at the next moment; if a device failure is found, an alarm signal will be issued and the entire device will be locked , Wait for the technician to troubleshoot and reset manually.
  • a further improvement of the present invention is that in formula (2), the starting threshold v st is 0.5 to 0.6 m/s;
  • the protection reliability coefficient k re is 1.2.
  • step 5 the overcurrent alarm threshold v th.2 is 0.4-0.5m /s;
  • step 6 the quasi-overcurrent warning threshold v th.3 is 0.3 to 0.4 m/s.
  • the present invention has the following beneficial effects:
  • the present invention uses digital oil flow information to form protection to identify transformer internal faults. Compared with the previous mechanical gas protection and current differential protection, it has the following advantages: First, although the transformer internal, external, and disturbance conditions will cause a certain amplitude However, due to the essential difference in the mechanism of the oil flow surging, the digital oil flow information can be used to distinguish the different operating states of the transformer. Second, the present invention uses an externally bundled high-frequency ultrasonic flowmeter to realize digital real-time measurement of the oil flow inside the oil confinement connecting pipe without damaging the existing structural integrity of the transformer. Different from the spring structure of traditional mechanical Buchholz relay soaked in insulating oil for a long time, the ultrasonic flowmeter does not directly contact the insulating oil.
  • the indirect measurement method will not cause the loss of the kinetic energy of the flow rate; And the sludge generated by the deterioration of the insulating oil will not adhere to the measuring device, so the device of the present invention has higher flow velocity measurement accuracy, sensing sensitivity, and long-term operation reliability and stability.
  • the common advantage of non-electricity protection is that it is more sensitive to weak faults. From the perspective of energy conversion, electrical network failures will accompany the conversion of faulty electrical energy, while non-electrical physical quantities are often direct representations of different forms of energy, and at the same time have cumulative effects in nature.
  • the present invention overcomes the traditional mechanical non-electricity protection. Although tens of thousands of oil-immersed transformers have been successfully protected in the course of nearly a hundred years of use, but due to theoretical modeling difficulties, principle defects, threshold values based on experience, and mechanical Problems such as insufficient structural performance are increasingly difficult to meet the higher requirements of current large-capacity, high-voltage power transformers. At the same time, system power outages and transformer explosion accidents caused by protection refusal and misoperation accidents occur from time to time, which seriously affect the safe and reliable operation of the power system, and seriously threaten the life and property safety of substation operators and the surrounding people.
  • the present invention adopts a high-frequency ultrasonic flowmeter to realize real-time measurement of the oil flow inside the oil pillow connecting pipe without damaging the existing structural integrity of the transformer.
  • the on-line monitoring integrated device of the present invention is independent of the power network, the measurement of oil flow characteristics and signal transmission suffer less interference, and it does not inject harmonics into the power system; the data acquisition components and the oil flow calculation analysis components can fully meet the requirements of fast, Real-time processing of multi-channel, high-frequency data requirements.
  • the present invention uses a flow meter with a measurement frequency of 100 Hz or more, a measurement error of less than 1%, a working temperature of -30 to 80°C, and a flow rate range of -20 to 20 m/s for measurement.
  • the meter can realize real-time measurement of the oil flow velocity without destroying the structural integrity of the transformer oil pillow connecting pipe.
  • the high-frequency ultrasonic flowmeter can meet the high temperature and strong electromagnetic environment requirements of the power transformer body in terms of accuracy and range of use. .
  • the device of the present invention is composed of a transient oil flow characteristic quantity measurement module, a switch input module, a signal conditioning and acquisition module, and a digital core module.
  • the online monitoring integrated device is controlled to realize the protection of the protection device.
  • the invention uses the transient change characteristics of the oil flow inside the oil pillow connection pipe and the difference in flow velocity under different operating conditions to screen the internal faults of the transformer oil tank, and improves the mechanical gas protection based on experience and feeling to quantitative analysis and high reliability.
  • the new stage of performance determination and digitization will adapt to the current and future requirements of large-capacity, high-voltage power transformers for the "four characteristics" of gas protection.
  • the invention overcomes the problem that the traditional Buchholz relay can only sense the flow rate through a mechanical spring device and can only output switch information. A single flow rate amplitude often cannot correctly distinguish the internal and external faults of the transformer, resulting in protection malfunction or refusal to operate. .
  • the invention obtains the action oil flow that can completely characterize the average kinetic energy of the transformer oil flow through filtering and integral calculation of the transient oil flow data inside the transformer oil pillow connecting pipe, and the preset start threshold, overcurrent alarm threshold and quasi-overcurrent The alarm threshold is compared to realize real-time monitoring and evaluation of the oil flow level inside the transformer.
  • the present invention organically combines online monitoring and relay protection functions.
  • the application of the present invention has important engineering practicality for transformer operators to obtain real-time, accurate and reliable transformer transient oil flow data, evaluate transformer operation status, and improve transformer safety operation level. significance.
  • Figure 1 is a schematic diagram of the structure of the present invention.
  • Figure 2 is a logic flow diagram of the present invention.
  • Figure 3 shows the field test verification results of the digital gas protection device for power transformers.
  • the integrated device for transformer digital gas protection and oil flow surge monitoring including: transient oil flow characteristic measurement module, switch input module, signal conditioning and acquisition module, digital core module, external communication interface module, Man-machine dialogue module, switch output module and data storage module.
  • the transient oil flow characteristic quantity measurement module is connected with the signal conditioning and acquisition module.
  • the signal conditioning and acquisition module, the switch output module, the external communication interface module, the man-machine dialogue module, the switch output module and the data storage module are all connected with the digital Core modules are connected;
  • the transient oil flow characteristic quantity measurement module is composed of an externally bundled high-frequency ultrasonic flowmeter, a flowmeter transmitter and a communication cable.
  • the externally bundled high-frequency ultrasonic flowmeter is installed on the connecting pipe of the transformer oil pillow.
  • the high-frequency ultrasonic flowmeter is connected with the flowmeter transmitter, and the flowmeter transmitter is connected with the communication cable.
  • the externally bundled high-frequency ultrasonic flowmeter is used to measure the characteristics of the transient oil flow changes in the transformer oil pillow connecting pipe in real time and high speed, and the flowmeter transmitter and the communication cable are used to output the corresponding analog voltage/current signal.
  • the measurement frequency of the high-frequency ultrasonic flowmeter must be above 100Hz, the measurement error must be less than 1%, the operating temperature must reach -30 ⁇ 80°C, and the flow rate range must reach -20 ⁇ 20m/s.
  • the switch input module collects the relevant switch signals that need to be known, and outputs them as high level “1” or low level “0" through the photoelectric isolation device, as the input digital quantity of the digital core module.
  • the signal conditioning and acquisition module is composed of wiring terminals, signal conditioning circuits, low-pass filters, signal sampling circuits and analog-to-digital (A/D) conversion circuits.
  • the connection terminal is connected to the signal conditioning circuit, the signal conditioning circuit is connected to the low-pass filter, the low-pass filter is connected to the signal sampling circuit, and the signal sampling circuit is connected to the analog-to-digital A/D conversion circuit; the connection terminal is also connected to the communication cable,
  • the analog-to-digital A/D conversion circuit is connected to the digital core module.
  • the signal conditioning and acquisition module is used to receive the analog voltage/current signal obtained by the transient oil flow characteristic measurement module and convert it into a standard digital signal that the digital core module can recognize.
  • the digital core module is used to receive the standard digital signal output by the signal conditioning and acquisition module and the input digital value output by the switch input module, perform protection and monitoring operations, complete digital signal processing tasks, and realize the integrated function of relay protection and online monitoring .
  • the digital core module is composed of bus, central processing unit (CPU), timer/counter, random access memory (RAM), read-only memory (ROM) and control circuit.
  • the bus includes a data bus, an address bus, and a control bus to realize data exchange and operation control.
  • the central processing unit (CPU) is the command center of the digital core module. It can use single-chip microprocessors, general-purpose microprocessors, and digital signal processors (DSP) to quickly realize digital signal processing in real time.
  • the timer/counter is used to provide functions such as timing sampling trigger signal, forming interrupt, and precise timing of protection delay action.
  • Random Access Memory (RAM) is used to temporarily store a large amount of temporary data that needs to be exchanged quickly, including data information input by signal conditioning and acquisition modules, and intermediate results of calculation processing.
  • Read-only memory is used to store data.
  • the control circuit can realize the effective connection and coordination of the entire digital circuit through a complex programmable logic device (CPLD) or a field programmable gate array (FPGA).
  • CPLD complex programmable logic device
  • FPGA field programmable gate array
  • the digital core module is used to realize data exchange and operation control, complete digital signal processing tasks, direct the normal operation of connected modules, and realize the integrated functions of relay protection and online monitoring.
  • the external communication interface module is composed of an IEC 61850 communication interface and a dedicated communication interface for protection functions. It is used to provide information channels with computer communication networks and remote communication networks to realize functions such as information exchange, data sharing, remote operation and remote maintenance.
  • the man-machine dialogue module includes compact keyboard, display screen, indicator light, printer interface and debugging communication interface. It is used to establish the information connection between the digital protection device and the user, so that the operator can manually operate the protection device, debug and get information feedback.
  • the switch output module is composed of a photoelectric isolation device and an outlet relay. It controls the “on” or “off” of the trip circuit and the alarm circuit through the output "0" or “1” state, so as to realize the reliable action of the protection.
  • the data storage module is composed of primary and secondary flash memory (Flash Memory). Flash memory is used for data storage, as the main memory and backup memory of the online monitoring system.
  • transformer digital gas protection and oil flow surge monitoring integrated device is as follows:
  • the transient oil flow characteristic quantity measurement module measures the characteristics of the transient oil flow changes in the oil conservator connection pipe of the transformer in real time and at a high speed, that is, reads the current oil conservator connection pipe oil flow data v ms (t); output the corresponding analog voltage/current signal;
  • the signal conditioning and acquisition module receives the analog voltage/current signal obtained by the transient oil flow characteristic measurement module, converts it into a standard digital signal that can be recognized by the digital core module, and then outputs the standard digital signal;
  • the switch input module is used to collect the relevant switch signals that need to be ascertained, and output them as high level 1 or low level 0 as the input digital quantity of the digital core module;
  • the digital core module After receiving the standard digital signal and the input digital quantity, the digital core module uses formula (1) to calculate the oil flow movement quantity v op (t) at the current time t.
  • T is the length of the data window.
  • f is the signal sampling frequency of the acquisition module.
  • the starting threshold v st can be selected within the flow rate range of 0.5 to 0.6 m/s according to the diameter of the oil conservator connecting pipe.
  • k re is the protection reliability coefficient, usually 1.2.
  • v th.1 is the threshold value of digital gas protection, which can be selected according to the pipe diameter of the oil conservator connecting pipe with reference to the national or industry standards for heavy gas protection of mechanical Buchholz relays.
  • v th.2 7Judging the magnitude of the operating oil flow v op (t) and the overcurrent alarm threshold v th.2 , v th.2 can usually be set to 0.4 ⁇ 0.5m/s.
  • the overcurrent alarm threshold v th.2 is based on The pipe diameter size of the oil pillow connecting pipe is selected within the flow rate range of 0.4 ⁇ 0.5m/s. If the operating oil flow is greater than or equal to the over-current alarm threshold v th.2 , that is, equation (4) is established, an over-current warning of the transformer is issued; if the operating oil flow is less than the over-current alarm threshold v th.2 , that is, equation (4) is not established, Then enter step 8.
  • V th.3 can usually be set to 0.3 ⁇ 0.4m/s.
  • the quasi-overcurrent warning threshold v th. 3 According to the pipe diameter size of the oil pillow connecting pipe, select within the flow rate range of 0.3 ⁇ 0.4m/s. If it is greater than or equal to the quasi-overcurrent warning threshold, that is, formula (5) is established, a transformer quasi-overcurrent warning is issued; if it is less than the quasi-overcurrent warning threshold v th.3 , that is, formula (5) is not established, it indicates that the transformer oil flow velocity is normal .
  • step 10 Carry out running self-check and self-check on the running status. If no device failure is found, return to step 3, re-read the oil flow data velocity v ms (t+1) at the next moment; if a device failure is found, an alarm signal will be issued and Lock the entire device and wait for technicians to troubleshoot and reset manually.
  • the invention can realize the functions of system monitoring, fault processing, man-machine dialogue, communication, self-inspection, accident recording and analysis report and debugging of the device.
  • the invention realizes the real-time measurement of the oil flow inside the oil pillow connecting pipe through the external clamp type high frequency ultrasonic flowmeter without destroying the existing structural integrity of the transformer.
  • the clamp-on high-frequency ultrasonic flowmeter is independent of the power network, and the measurement of oil flow characteristics and signal transmission suffers less interference, and it does not inject harmonics into the power system; data acquisition components and oil flow calculation and analysis components can fully meet the requirements of fast, Real-time processing of multi-channel, high-frequency data requirements.
  • the present invention adopts an externally bundled high frequency ultrasonic flowmeter with a measurement frequency of 100 Hz or more, a measurement error of less than 1%, a working temperature of -30 to 80°C, and a flow rate range of -20 to 20 m/s.
  • the high-frequency ultrasonic flowmeter can meet the requirements of high temperature, oil pollution and strong electromagnetic environment inside the power transformer in terms of accuracy and range of use.
  • the action oil flow that can completely characterize the average kinetic energy of the transformer oil flow is obtained, and the preset start threshold, overcurrent alarm threshold and pass The flow alarm threshold is compared to realize real-time monitoring and evaluation of the oil flow level inside the transformer.
  • the present invention uses the transient change characteristics of the oil flow inside the oil pillow connecting pipe and the difference in flow velocity under different operating conditions to screen the internal faults of the transformer oil tank, and improves the mechanical gas protection based on experience and feeling to quantitative analysis,
  • the new stage of high-reliability determination and digitization so as to adapt to the current and future large-capacity, high-voltage power transformers' "four characteristics" requirements for gas protection, there are no relevant studies, reports and products at home or abroad.
  • the SFSZ8-40000/110 three-phase three-winding transformer was used as a test platform to conduct field tests to illustrate the effect of the present invention.
  • the main geometric structure and nameplate parameters of this type of transformer are shown in Table 1.
  • Figure 3 when the transformer is in normal operation (t ⁇ 0ms), the oil flow velocity inside the transformer oil pillow connecting pipe does not change significantly. At this time, the operating oil flow v op measured and calculated by this device is less than the protection start threshold v st , so the protection function is not activated.
  • the device of the present invention since the operating oil flow v op is less than the over-current and quasi-over-current threshold values v th.2 and v th.3 , the device of the present invention does not issue an over-current alarm, and externally shows that the oil flow velocity inside the transformer oil pillow connecting pipe is normal.
  • the oil flow action volume v op obtained by the device of the present invention measured and calculated is greater than the protection preset action threshold value v th.1 .
  • the device determines that the transformer has an internal fault and sends a trip signal to remove the faulty transformer.
  • the field test results show that the device of the present invention can capture the sudden change of oil flow in the oil confinement connecting pipe of an oil-immersed power transformer in a very short time, and obtain the oil flow action quantity that can characterize the swell intensity of the oil flow inside the transformer by calculation. , According to the comparison with the preset protection criterion, the internal arc fault of the transformer is correctly screened, and the fault is removed reliably, sensitively and quickly.
  • Table 1 The main geometric structure and nameplate parameters of SFSZ8-40000/110 transformer

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Abstract

变压器数字式瓦斯保护与油流涌动监测一体化装置及方法，该装置包括：瞬态油流特征量测量模块、开关量输入模块、信号调理与采集模块以及数字核心模块；其中，瞬态油流特征量测量模块与信号调理与采集模块相连，信号调理与采集模块以及开关量输出模块均与数字核心模块相连。

Description

变压器数字式瓦斯保护与油流涌动监测一体化装置及方法 技术领域
本发明属于电力系统领域，涉及变压器数字式瓦斯保护与油流涌动监测一体化装置及方法，用于可靠、快速、灵敏甄别油浸式电力变压器油箱内部故障。
背景技术
作为一种关键的电力主设备，变压器在电力系统中占有举足轻重的地位，它的稳定运行是保证整个电力系统电能可靠传输、灵活分配、安全使用的重要前提。当变压器发生内部故障时，如果继电保护装置拒动或者不能及时动作，变压器本体可能因内部故障压力冲击而发生损坏，甚至引发爆炸、起火事故；另一方面，一旦保护装置在非内部故障条件下发生误动作，因停电造成的经济损失将不可避免。尤其对于高电压等级、大容量的枢纽变压器，由于自身造价昂贵、结构复杂，且带有大量负荷，无论发生保护拒动或是误动，都将严重影响电力系统的安全稳定运行。因此，研究和探索可靠性高、动作速度快且灵敏度高的变压器保护具有十分重要的意义。
变压器内部故障过程伴随有三个主要特征：相电流增加、差电流增加以及故障气体的产生。针对这三个显著特征，继电保护工作者们设计了过电流保护、差动保护以及非电量保护等。故障气体产生过程中变压器内部油流、温度、压力等非电量特征随之发生变化是故障电能转化为内能、动能、势能等其他形式能量的具体表现。对于变压器内部弱故障而言，由于故障功率较小，仅凭电量保护往往难以灵敏甄别。但是，通过一段时间的故障能量累积，变压器油箱内部将出现较为明显的油流涌动、温度升高、压力增大等非电量特征变化。因此，利用非电量特征构建变压器保护往往较电气量保护具有更高的灵敏度。此外，作为电力系统中重要的集中元件，电力变压器是集绕组、铁心、绝缘、油箱、开关、冷却器等多个组件为 一体的昂贵设备。其故障形式往往表现为各组件发生过热性故障：如铁心硅钢片间过热、绕组烧断、分接开关触头融化或灼伤；或是出现机械性故障：铁心结构松动、绕组机械形变或坍塌、变压器油箱开裂漏油等。当面对非电气网络故障时，电气量保护往往难以可靠甄别，而基于流速、温度、压力等特征非电量保护则能够更为全面、直接的反应于变压器故障状态。
因此，早在1921年，德国变压器专家Max Buchholz便发明了瓦斯继电器，并将其安装在变压器主油箱与油枕之间的连接管上，主要适用于带有油枕且油箱顶部无气体空间的大型油浸式变压器，以保护电气量保护灵敏区外的各种类型的内部故障，弥补电气量保护存在的不足。基于变压器内部故障气体产生的瓦斯保护装置拓宽了继电保护研究的既有思路，凭借灵敏度优势广泛应用于油浸式电力变压器。规程《电力设备的继电保护和自动装置设计规范》明确规定：容量为0.4MVA及以上的车间内油浸式变压器、容量为0.8MVA及以上的油浸式变压器，以及带负荷调压变压器的充油调压开关均应装设瓦斯保护，当壳内故障产生轻微瓦斯或油面下降时，应瞬时动作于信号；当产生大量瓦斯时，应动作于断开变压器各侧断路器。
目前广泛使用的瓦斯继电器依然沿用百年前Buchholz继电器的基本原理与机械结构，但随着数十年来电力系统的高速发展，现有机械式瓦斯保护越来越难以满足大容量、高电压等级电力变压器对其保护性能的更高要求。近年来频发的变压器因内部故障发生爆炸、起火事故或因外部短路故障而发生误动跳闸事故表明，传统机械式瓦斯保护主要存在原理性缺陷、凭经验取门槛值以及机械结构动作性能低下等问题，其保护性能越来越难以满足目前大容量、高电压等级电力变压器的更高要求。因此，迫切需要开发一种数字式瓦斯保护装置，将从前凭经验和感觉构成的机械式瓦斯保护提高到定量分析、高可靠性判定、数字化实现的新阶段。
另一方面，继电保护是在故障发生后，通过保护判据甄别故障，并发出跳闸信号快速切除故障，以免造成系统或设备的进一步损坏。因此，继电保护动作切除故障是对电力系统和电力设备的被动安全防御方式。与此不同，电力设备的在线监测装置能够在故障发生前，通 过对表征变压器运行状态的物理量进行监测、分析、运算，从而评估设备的健康状态，从而确定是否需要安排维护作业，起到防患于未然的作用，避免设备的故障，是一种提高变压器运行安全性的积极主动防御方式。
传统机械式瓦斯保护利用浮球、弹簧、挡板等机械结构感应气体产生及油流涌动，主要存在两方面问题：其一，弹簧机构仅能反应油流流速的大小，一旦超过预设门槛就发出跳闸信号，没有测量、分析油流涌动变化特征信息，因此保护可靠性较低；其二，机械结构长期浸泡在绝缘油中，氧化物脱落以及绝缘油劣化而产生的油泥将附着在继电器挡板、浮子或者弹簧等机械构件上，严重影响其动作的准确性和灵敏性。
发明内容
本发明的目的是提供变压器数字式瓦斯保护与油流涌动监测一体化装置及方法，能够可靠、快速、灵敏甄别油浸式电力变压器油箱内部故障，且通过对瞬态油流的监测与分析以评估变压器的运行状态，实现保护与在线监测的一体化。
为实现上述目的，本发明采用如下的技术方案：
变压器数字式瓦斯保护与油流涌动监测一体化装置，包括：瞬态油流特征量测量模块、开关量输入模块、信号调理与采集模块以及数字核心模块；其中，瞬态油流特征量测量模块与信号调理与采集模块相连，信号调理与采集模块、开关量输出模块、外部通信接口模块、人机对话模块、开关量输出模块以及数据存储模块均与数字核心模块相连；
瞬态油流特征量测量模块用于实时高速测量变压器油枕连接管内部瞬态油流变化特征，输出与之相对应的模拟电压/电流信号；
信号调理与采集模块用于接收瞬态油流特征测量模块得到的模拟电压/电流信号，并将其转换为数字核心模块能够识别的标准数字信号，再输出标准数字信号；
开关量输入模块用于采集需要确知的相关开关量信号，并将其输出为高电平1或低电平 0，作为数字核心模块的的输入数字量；
数字核心模块用于接收标准数字信号与输入数字量后，执行保护与监测运算，完成数字信号处理任务，进而实现继电保护与在线监测一体化功能。
本发明进一步的改进在于，瞬态油流特征量测量模块由外捆式高频超声波流量计、流量计变送器以及通信线缆组成，外捆式高频超声波流量计安装在变压器油枕连接管上，外捆式高频超声波流量计与流量计变送器相连，流量计变送器与通信线缆相连。
本发明进一步的改进在于，外捆式高频超声波流量计的测量频率为100Hz以上，测量误差小于1％，工作温度为-30～80℃，流速量程为-20～20m/s。
本发明进一步的改进在于，信号调理与采集模块由接线端子、信号调理电路、低通滤波器、信号采样电路以及模数A/D转换电路组成；接线端子与信号调理电路相连，信号调理电路与低通滤波器相连，低通滤波器与信号采样电路相连，信号采样电路与模数A/D转换电路相连，模数A/D转换电路与数字核心模块相连；接线端子还与通信线缆相连。
本发明进一步的改进在于，数字核心模块由总线、中央处理器、定时器/计数器、随机存储器以及控制电路组成；总线包括数据总线、地址总线以及控制总线，实现数据交换和操作控制；中央处理器利用单片微处理器、通用微处理器或数字信号处理器实现数字信号处理；定时器/计数器用来提供定时采样触发信号、形成中断、保护延时动作计时功能；随机存储器用于暂存临时数据，包括信号调理与采集模块输入的数据信息、计算处理过程的中间结果；控制电路通过复杂可编程逻辑器件或现场可编程门阵列实现整个数字电路的连接和协调工作。
本发明进一步的改进在于，还包括与数字核心模块相连的外部通信接口模块、人机对话模块、开关量输出模块以及数据存储模块；
外部通信接口模块用于提供与计算机通信网络以及远程通信网的信息通道，实现信息交互、数据共享、远方操作以及远程维护功能；
人机对话模块用于建立数字式保护装置与使用者之间的信息联系，以便运行人员对保护装置的人工操作、调试以及得到信息反馈；
开关量输出模块用于输出的0或1状态来控制执行跳闸回路、告警回路的通或断；
数据存储模块用于存储数据。
本发明进一步的改进在于，外部通信接口模块包括IEC 61850通信接口和保护功能专用通信接口；
人机对话模块包括紧凑键盘、显示屏、指示灯、按钮以及打印机接口；
开关量输出模块由光电隔离器件以及出口继电器组成，光电隔离器件一端与数字核心模块相连，另一端与出口继电器相连；
数据存储模块由主闪存存储器与副闪存存储器组成；主、副闪存存储器作为装置的主存储器及备用存储器使用。
一种基于上述的变压器数字式瓦斯保护与油流涌动监测一体化装置的方法，包括以下步骤：
①瞬态油流特征量测量模块实时测量变压器油枕连接管内部瞬态油流变化特征；输出与之相对应的模拟电压/电流信号；
信号调理与采集模块接收瞬态油流特征测量模块得到的模拟电压/电流信号，并将其转换为数字核心模块能够识别的标准数字信号，再输出标准数字信号；
开关量输入模块用于采集需要确知的相关开关量信号，并将其输出为高电平1或低电平0，作为数字核心模块的的输入数字量；
②数字核心模块接收标准数字信号与输入数字量后，利用式(1)计算当前t时刻的油流动作量v op(t)：
Figure PCTCN2020088306-appb-000001
式(1)中，T为数据窗长度；f为采集模块的信号采样频率；
③执行保护启动判据，判断保护是否启动；比较当前t时刻油流流速v ms(t)与保护启动门槛v st之间的幅值大小关系，即通过判断式(2)是否成立来决定数字式瓦斯保护是否启动，若式(2)成立，进入步骤④；若式(2)不成立，进入步骤⑤；
v ms(t)-v st≥0   (2)
④比较当前t时刻的油流动作量v op(t)与保护门槛值v th.1之间的幅值大小关系，即判断式(3)是否成立来甄别变压器油箱内部故障；若式(3)成立，则发出跳闸信号，整套保护复归，等待人工复位；否则进入步骤⑤；
v op(t)/k re≥·v th.1   (3)
式(3)中，k re为保护可靠系数，v th.1为数字式瓦斯保护门槛值；
⑤判断动作油流v op(t)与过流报警门槛v th.2的大小，若动作油流大于等于过流报警门槛v th.2，即式(4)成立，则发出变压器过流警示，进入步骤⑦；若动作油流小于过流报警门槛v th.2，即式(4)不成立，则进入步骤⑥；
v op(t)-v th.2≥0   (4)
⑥判断动作油流v op(t)与准过流预警门槛v th.3的大小，若大于等于准过流预警门槛，即式(5)成立，则发出变压器准过流预警，进入步骤⑦；若小于准过流预警门槛v th.3，即式(5)不成立，则显示变压器油流流速正常；
v op(t)-v th.3≥0   (5)
⑦存储测量得到的油流数据，并将数据通信至总站；
⑧在运行状态下进行运行自检，若未发现装置故障，返回步骤①，重新读取下一时刻油流数据流速v ms(t+1)；若发现装置故障则发出告警信号并闭锁整个装置，等待技术人员排除故障、人工复位。
本发明进一步的改进在于，式(2)中，启动门槛v st位0.5～0.6m/s；
式(3)中，保护可靠系数k re为1.2。
本发明进一步的改进在于，步骤⑤中，过流报警门槛v th.2为0.4～0.5m/s；
步骤⑥中，准过流预警门槛v th.3为0.3～0.4m/s。
与现有技术相比，本发明具有的有益效果：
本发明利用数字式油流信息构成保护以甄别变压器内部故障相较于以往的机械式瓦斯保护、电流差动保护具有以下优势：其一，虽然变压器内部、外部以及扰动情况均会导致一定幅值的油流涌动，但是由于产生油流涌动的机理存在本质区别，因此利用数字式油流信息能够实现对变压器不同运行状态的区分。其二，本发明利用外捆式高频超声波流量计在不破坏变压器现有结构完整性的前提下实现了对油枕连接管内部油流的数字式实时测量。与传统机械式瓦斯继电器的弹簧结构长期浸泡在绝缘油中不同，超声波流量计并不直接与绝缘油接触，一方面，间接式测量方式不会造成流速动能的损失；另一方面，氧化物脱落以及绝缘油劣化而产生的油泥并不会附着在测量装置上，因此本发明装置具有更高的流速测量精度、感应灵敏度以及长期运行可靠性和稳定性。其三，相较于电气量保护在面对单匝或小匝数短路等一些低能量故障发生时表现出灵敏度不足的问题，非电量保护共有的优点在于更高灵敏反应弱故障。从能量转化的角度分析，电气网络故障将伴随着故障电能的转化，而非电气物理量往往是不同形式能量的直接表征，同时本质上具有累积效应。本发明克服了传统机械式非电量保护在近百年的使用过程中虽然成功保护了数以万计的油浸式变压器，但由于存在理论建模困难、原理性缺陷、凭经验取门槛值以及机械结构动作性能不足等问题，越来越难以满足当前大容量、高电压等级电力变压器的更高要求的问题。同时，因保护拒动、误动事故引起的系统停电、变压器爆炸事故时有发生，严重影响到电力系统的安全、可靠运行，严重威胁变电站运行人员及周围人民群众生命财产安全的问题。
进一步的，本发明通过采用高频超声波流量计，在不破坏变压器现有结构完整性的前提下实现对油枕连接管内部油流进行实时测量。本发明的在线监测一体化装置独立于电力网络，油流特征的测量和信号传输所受干扰较小，亦不向电力系统注入谐波；数据采集元件、油流运算分析元件完全能够满足快速、实时处理多通路、高频数据的要求。
进一步的，本发明通过采用测量频率为100Hz以上，测量误差小于1％，工作温度为-30～80℃，流速量程为-20～20m/s的流量计进行测量，外捆式高频超声波流量计可以在不破坏变压器油枕连接管结构完整性的前提下实现对油流流速的实时测量，同时，无论从精度还是使用范围高频超声波流量计都能满足电力变压器本体高温、强电磁环境要求。
本发明的装置由瞬态油流特征量测量模块、开关量输入模块、信号调理与采集模块以及数字核心模块组成，按照保护原理及功能要求对在线监测一体化装置进行控制，实现对保护装置的系统监控、故障处理、人机对话、通信、自检、事故记录与分析报告以及调试功能。本发明利用油枕连接管内部油流的瞬态变化特征及在不同运行条件下出现的流速差异甄别变压器油箱内部故障，将以往凭经验和感觉构成的机械式瓦斯保护提高到定量分析、高可靠性判定、数字化实现的新阶段，从而适应当前及未来大容量、高电压等级电力变压器对瓦斯保护“四性”的要求。本发明克服了传统瓦斯继电器只能通过机械弹簧装置感应流速大小且只能输出开关量信息，单一流速幅值往往无法正确区分变压器的区内、外故障，从而导致保护误动或者拒动的问题。本发明通过对变压器油枕连接管内部瞬态油流数据的滤波及积分运算，获取能够完整表征变压器油流平均动能的动作油流，通过与预设启动门槛、过流报警门槛以及准过流报警门槛进行比较，实现对变压器内部油流水平的实时监测和评估。本发明将在线监测与继电保护功能进行有机结合，本发明的应用对于变压器运行人员实时、准确、可靠获取变压器瞬态油流数据、评估变压器运行状态、提高变压器安全运行水平具有重要的工程实用意义。
附图说明
图1为本发明的结构原理图。
图2为本发明的逻辑流程图。
图3为电力变压器数字式瓦斯保护装置现场试验验证结果。
具体实施方式
下面结合附图对本发明进行详细描述。
参见图1，变压器数字式瓦斯保护与油流涌动监测一体化装置，包括：瞬态油流特征量测量模块、开关量输入模块、信号调理与采集模块、数字核心模块、外部通信接口模块、人机对话模块、开关量输出模块以及数据存储模块。其中，瞬态油流特征量测量模块与信号调理与采集模块相连，信号调理与采集模块、开关量输出模块、外部通信接口模块、人机对话模块、开关量输出模块以及数据存储模块均与数字核心模块相连；
瞬态油流特征量测量模块由外捆式高频超声波流量计、流量计变送器以及通信线缆组成，外捆式高频超声波流量计安装在变压器油枕连接管上，外捆式高频超声波流量计与流量计变送器相连，流量计变送器与通信线缆相连。利用外捆式高频超声波流量计实时高速测量变压器油枕连接管内部瞬态油流变化特征，利用流量计变送器和通信线缆输出与之相对应的模拟电压/电流信号。为保证保护装置的可靠性、速动性以及灵敏度，高频超声波流量计的测量频率需达到100Hz以上，测量误差需小于1％，工作温度需达到-30～80℃，流速量程需达到-20～20m/s。
开关量输入模块采集需要确知的相关开关量信号，并通过光电隔离器件将其输出为高电平“1”或低电平“0”，作为数字核心模块的输入数字量。
信号调理与采集模块由接线端子、信号调理电路、低通滤波器、信号采样电路以及模数(A/D)转换电路组成。接线端子与信号调理电路相连，信号调理电路与低通滤波器相连， 低通滤波器与信号采样电路相连，信号采样电路与模数A/D转换电路相连；接线端子还与通信线缆相连，模数A/D转换电路与数字核心模块相连。信号调理与采集模块用于接收瞬态油流特征测量模块得到的模拟电压/电流信号，并将其转换为数字核心模块能够识别的标准数字信号。
数字核心模块用于接收信号调理与采集模块输出的标准数字信号以及开关量输入模块输出的输入数字量，执行保护与监测运算，完成数字信号处理任务，进而实现继电保护与在线监测一体化功能。
数字核心模块由总线、中央处理器(CPU)、定时器/计数器、随机存储器(RAM)、只读存储器(ROM)以及控制电路组成。总线包括数据总线、地址总线、控制总线，实现数据交换和操作控制等。中央处理器(CPU)是数字核心模块的指挥中枢，可以利用单片微处理器、通用微处理器以及数字信号处理器(DSP)等器件实时快速实现数字信号处理。定时器/计数器用来提供定时采样触发信号、形成中断、保护延时动作精确计时等功能。随机存储器(RAM)用于暂存需要快速交换的大量临时数据，包括信号调理与采集模块输入的数据信息、计算处理过程的中间结果等。只读存储器(ROM)用于保存数据。控制电路可以通过复杂可编程逻辑器件(CPLD)或现场可编程门阵列(FPGA)等实现整个数字电路的有效连接和协调工作。数字核心模块用于实现数据交换及操作控制，完成数字信号处理任务，指挥相连模块的正常运行，进而实现继电保护与在线监测一体化功能。
外部通信接口模块由IEC 61850通信接口与保护功能专用通信接口组成，用以提供与计算机通信网络以及远程通信网的信息通道，实现信息交互、数据共享、远方操作以及远程维护等功能。
人机对话模块包括紧凑键盘、显示屏、指示灯、打印机接口以及调试通信接口等。用于建立数字式保护装置与使用者之间的信息联系，以便运行人员对保护装置的人工操作、调试 以及得到信息反馈等。
开关量输出模块由光电隔离器件以及出口继电器组成，通过输出的“0”或“1”状态来控制执行跳闸回路、告警回路的“通”或“断”，实现保护的可靠动作。
数据存储模块由主、副闪存存储器(Flash Memory)组成。闪存存储器用于数据的存储，作为在线监测系统的主存储器及备用存储器使用。
参见图2，按照保护与监测原理及其功能要求对一体化装置进行控制，包括对一体化装置的系统监控、故障处理、人机对话、通信、自检、事故记录与分析报告以及调试等功能。技术上述变压器数字式瓦斯保护与油流涌动监测一体化装置的方法按照如下步骤：
①一体化装置在合上电源(简称上电)或硬件复位(简称复位)后，首先执行初始化，使整个一体化装置处于正常工作状态。
②执行上电后的全面自检，对自身的工作状态进行正确性、完整性检测，若发现装置缺陷则发出告警信号并闭锁整个装置，等待技术人员排除故障、人工复位。
③若通过自检，执行数据采集初始化，瞬态油流特征量测量模块实时高速测量变压器油枕连接管内部瞬态油流变化特征，即读取当前t时刻油枕连接管油流数据v ms(t)；输出与之相对应的模拟电压/电流信号；
信号调理与采集模块接收瞬态油流特征测量模块得到的模拟电压/电流信号，并将其转换为数字核心模块能够识别的标准数字信号，再输出标准数字信号；
开关量输入模块用于采集需要确知的相关开关量信号，并将其输出为高电平1或低电平0，作为数字核心模块的的输入数字量；
④数字核心模块接收标准数字信号与输入数字量后，利用式(1)计算当前t时刻的油流动作量v op(t)。
Figure PCTCN2020088306-appb-000002
式(1)中，T为数据窗长度。f为采集模块的信号采样频率。
⑤执行保护启动判据，判断保护是否启动。比较当前t时刻油流流速v ms(t)与保护启动门槛v st之间的幅值大小关系，即通过判断式(2)是否成立来决定数字式瓦斯保护是否启动，若式(2)成立，进入步骤⑥。若式(2)不成立，进入步骤⑦；
v ms(t)-v st≥0   (2)
式(2)中，启动门槛v st可根据油枕连接管的管径尺寸在0.5～0.6m/s流速范围内选取。
⑥比较v op(t)与保护门槛值v th.1之间的幅值大小关系，即判断式(3)是否成立来甄别变压器油箱内部故障。若式(3)成立，则发出跳闸信号，整套保护复归，等待人工复位；否则进入步骤⑦。
v op(t)/k re≥·v th.1   (3)
式(3)中，k re为保护可靠系数，通常取1.2。v th.1为数字式瓦斯保护门槛值，可根据油枕连接管的管径尺寸参照机械式瓦斯继电器重瓦斯保护的国家或行业标准进行选取。
⑦判断动作油流v op(t)与过流报警门槛v th.2的大小，v th.2通常可设定为0.4～0.5m/s，具体的，过流报警门槛v th.2根据油枕连接管的管径尺寸在0.4～0.5m/s流速范围内选取。若动作油流大于等于过流报警门槛v th.2，即式(4)成立，则发出变压器过流警示；若动作油流小于过流报警门槛v th.2，即式(4)不成立，则进入步骤⑧。
v op(t)-v th.2≥0   (4)
⑧判断动作油流v op(t)与准过流预警门槛v th.3的大小，v th.3通常可设定为0.3～0.4m/s，具体的，准过流预警门槛v th.3根据油枕连接管的管径尺寸在0.3～0.4m/s流速范围内选取。若大于等于准过流预警门槛，即式(5)成立，则发出变压器准过流预警；若小于准过流预警门槛v th.3，即式(5)不成立，则显示变压器油流流速正常。
v op(t)-v th.3≥0   (5)
⑨存储测量得到的油流数据，并将数据通信至总站。
⑩进行运行自检，对运行状态进行自检，若未发现装置故障，返回步骤③，重新读取下一时刻油流数据流速v ms(t+1)；若发现装置故障则发出告警信号并闭锁整个装置，等待技术人员排除故障、人工复位。
本发明能够实现对装置的系统监控、故障处理、人机对话、通信、自检、事故记录与分析报告以及调试功能。
本发明通过外夹式高频超声波流量计在不破坏变压器现有结构完整性的前提下实现对油枕连接管内部油流进行实时测量。外夹式高频超声波流量计独立于电力网络，油流特征的测量和信号传输所受干扰较小，亦不向电力系统注入谐波；数据采集元件、油流运算分析元件完全能够满足快速、实时处理多通路、高频数据的要求。进一步的，本发明采用测量频率为100Hz以上，测量误差小于1％，工作温度为-30～80℃，流速量程为-20～20m/s的外捆式高频超声波流量计，外捆式高频超声波流量计无论从精度还是使用范围都能满足电力变压器内部高温、油污、强电磁环境要求。
进一步的，通过对变压器油枕连接管内部瞬态油流数据的滤波及积分运算，获取能够完整表征变压器油流平均动能的动作油流，通过与预设启动门槛、过流报警门槛以及准过流报警门槛进行比较，实现对变压器内部油流水平的实时监测和评估。同时，本发明利用油枕连接管内部油流的瞬态变化特征及在不同运行条件下出现的流速差异甄别变压器油箱内部故障，将以往凭经验和感觉构成的机械式瓦斯保护提高到定量分析、高可靠性判定、数字化实现的新阶段，从而适应当前及未来大容量、高电压等级电力变压器对瓦斯保护“四性”的要求，在国内、外未见相关研究、报道及产品。
以SFSZ8-40000/110三相三绕组变压器为测试平台进行现场试验，说明本发明效果，该型变压器主要几何结构及铭牌参数如表1所示。如图3所示，当该变压器正常运行时(t＜0ms)， 变压器油枕连接管内部油流流速并未出现显著变化，此时本装置测量计算得到的动作油流v op小于保护启动门槛v st，故保护功能不启动。同时，由于动作油流v op小于过流、准过流门槛值v th.2与v th.3，本发明装置不发出过流报警，对外显示变压器油枕连接管内部油流流速正常。
当变压器在t＝0ms时刻突发内部电弧故障，由于故障能量的注入，故障气体产生导致油枕连接管内部绝缘油发生定向流动。t＝64.27ms时，本发明装置测量运算得到的油流动作量v op大于保护预设动作门槛值v th.1，此时本装置判定为变压器内部故障并发出跳闸信号，切除故障变压器。现场测试结果表明：本发明装置，能够在极短时间内捕捉到油浸式电力变压器油枕连接管内部油流突变特征，并通过计算得到能够表征变压器内部油流涌动强度的油流动作量，根据与预设保护判据进行比较，正确甄别变压器内部电弧故障，可靠、灵敏、快速切除故障。
表1 SFSZ8-40000/110型变压器主要几何结构及铭牌参数
Figure PCTCN2020088306-appb-000003
Figure PCTCN2020088306-appb-000004
以上内容是结合具体的优选实施方式对本发明所作的进一步详细说明，不能认定本发明的具体实施方式仅限于此，对于本发明所属技术领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干简单的推演或替换，都应当视为属于本发明由所提交的权利要求书确定专利保护范围。

Claims (10)

  1. 变压器数字式瓦斯保护与油流涌动监测一体化装置，其特征在于，包括：瞬态油流特征量测量模块、开关量输入模块、信号调理与采集模块以及数字核心模块；其中，瞬态油流特征量测量模块与信号调理与采集模块相连，信号调理与采集模块、开关量输出模块、外部通信接口模块、人机对话模块、开关量输出模块以及数据存储模块均与数字核心模块相连；
    瞬态油流特征量测量模块用于实时高速测量变压器油枕连接管内部瞬态油流变化特征，输出与之相对应的模拟电压/电流信号；
    信号调理与采集模块用于接收瞬态油流特征测量模块得到的模拟电压/电流信号，并将其转换为数字核心模块能够识别的标准数字信号，再输出标准数字信号；
    开关量输入模块用于采集需要确知的相关开关量信号，并将其输出为高电平1或低电平0，作为数字核心模块的的输入数字量；
    数字核心模块用于接收标准数字信号与输入数字量后，执行保护与监测运算，完成数字信号处理任务，进而实现继电保护与在线监测一体化功能。
  2. 根据权利要求1所述的变压器数字式瓦斯保护与油流涌动监测一体化装置，其特征在于，瞬态油流特征量测量模块由外捆式高频超声波流量计、流量计变送器以及通信线缆组成，外捆式高频超声波流量计安装在变压器油枕连接管上，外捆式高频超声波流量计与流量计变送器相连，流量计变送器与通信线缆相连。
  3. 根据权利要求1所述的变压器数字式瓦斯保护与油流涌动监测一体化装置，其特征在于，外捆式高频超声波流量计的测量频率为100Hz以上，测量误差小于1％，工作温度为-30～80℃，流速量程为-20～20m/s。
  4. 根据权利要求2所述的变压器数字式瓦斯保护与油流涌动监测一体化装置，其特征在于，信号调理与采集模块由接线端子、信号调理电路、低通滤波器、信号采样电路以及模数A/D转换电路组成；接线端子与信号调理电路相连，信号调理电路与低通滤波器相连，低通 滤波器与信号采样电路相连，信号采样电路与模数A/D转换电路相连，模数A/D转换电路与数字核心模块相连；接线端子还与通信线缆相连。
  5. 根据权利要求2所述的变压器数字式瓦斯保护与油流涌动监测一体化装置，其特征在于，数字核心模块由总线、中央处理器、定时器/计数器、随机存储器以及控制电路组成；总线包括数据总线、地址总线以及控制总线，实现数据交换和操作控制；中央处理器利用单片微处理器、通用微处理器或数字信号处理器实现数字信号处理；定时器/计数器用来提供定时采样触发信号、形成中断、保护延时动作计时功能；随机存储器用于暂存临时数据，包括信号调理与采集模块输入的数据信息、计算处理过程的中间结果；控制电路通过复杂可编程逻辑器件或现场可编程门阵列实现整个数字电路的连接和协调工作。
  6. 根据权利要求1所述的变压器数字式瓦斯保护与油流涌动监测一体化装置，其特征在于，还包括与数字核心模块相连的外部通信接口模块、人机对话模块、开关量输出模块以及数据存储模块；
    外部通信接口模块用于提供与计算机通信网络以及远程通信网的信息通道，实现信息交互、数据共享、远方操作以及远程维护功能；
    人机对话模块用于建立数字式保护装置与使用者之间的信息联系，以便运行人员对保护装置的人工操作、调试以及得到信息反馈；
    开关量输出模块用于输出的0或1状态来控制执行跳闸回路、告警回路的通或断；
    数据存储模块用于存储数据。
  7. 根据权利要求1所述的变压器数字式瓦斯保护与油流涌动监测一体化装置，其特征在于，外部通信接口模块包括IEC 61850通信接口和保护功能专用通信接口；
    人机对话模块包括紧凑键盘、显示屏、指示灯、按钮以及打印机接口；
    开关量输出模块由光电隔离器件以及出口继电器组成，光电隔离器件一端与数字核心模 块相连，另一端与出口继电器相连；
    数据存储模块由主闪存存储器与副闪存存储器组成；主、副闪存存储器作为装置的主存储器及备用存储器使用。
  8. 一种基于权利要求1-7中任意一项所述的变压器数字式瓦斯保护与油流涌动监测一体化装置的方法，其特征在于，包括以下步骤：
    ①瞬态油流特征量测量模块实时测量变压器油枕连接管内部瞬态油流变化特征；输出与之相对应的模拟电压/电流信号；
    信号调理与采集模块接收瞬态油流特征测量模块得到的模拟电压/电流信号，并将其转换为数字核心模块能够识别的标准数字信号，再输出标准数字信号；
    开关量输入模块用于采集需要确知的相关开关量信号，并将其输出为高电平1或低电平0，作为数字核心模块的的输入数字量；
    ②数字核心模块接收标准数字信号与输入数字量后，利用式(1)计算当前t时刻的油流动作量v op(t)：
    Figure PCTCN2020088306-appb-100001
    式(1)中，T为数据窗长度；f为采集模块的信号采样频率；
    ③执行保护启动判据，判断保护是否启动；比较当前t时刻油流流速v ms(t)与保护启动门槛v st之间的幅值大小关系，即通过判断式(2)是否成立来决定数字式瓦斯保护是否启动，若式(2)成立，进入步骤④；若式(2)不成立，进入步骤⑤；
    v ms(t)-v st≥0   (2)
    ④比较当前t时刻的油流动作量v op(t)与保护门槛值v th.1之间的幅值大小关系，即判断式(3)是否成立来甄别变压器油箱内部故障；若式(3)成立，则发出跳闸信号，整套保护复归，等待人工复位；否则进入步骤⑤；
    v op(t)/k re≥·v th.1  (3)
    式(3)中，k re为保护可靠系数，v th.1为数字式瓦斯保护门槛值；
    ⑤判断动作油流v op(t)与过流报警门槛v th.2的大小，若动作油流大于等于过流报警门槛v th.2，即式(4)成立，则发出变压器过流警示，进入步骤⑦；若动作油流小于过流报警门槛v th.2，即式(4)不成立，则进入步骤⑥；
    v op(t)-v th.2≥0  (4)
    ⑥判断动作油流v op(t)与准过流预警门槛v th.3的大小，若大于等于准过流预警门槛，即式(5)成立，则发出变压器准过流预警，进入步骤⑦；若小于准过流预警门槛v th.3，即式(5)不成立，则显示变压器油流流速正常；
    v op(t)-v th.3≥0  (5)
    ⑦存储测量得到的油流数据，并将数据通信至总站；
    ⑧在运行状态下进行运行自检，若未发现装置故障，返回步骤①，重新读取下一时刻油流数据流速v ms(t+1)；若发现装置故障则发出告警信号并闭锁整个装置，等待技术人员排除故障、人工复位。
  9. 根据权利要求8所述的方法，其特征在于，式(2)中，启动门槛v st位0.5～0.6m/s；
    式(3)中，保护可靠系数k re为1.2。
  10. 根据权利要求8所述的方法，其特征在于，步骤⑤中，过流报警门槛v th.2为0.4～0.5m/s；
    步骤⑥中，准过流预警门槛v th.3为0.3～0.4m/s。
PCT/CN2020/088306 2019-05-07 2020-04-30 变压器数字式瓦斯保护与油流涌动监测一体化装置及方法 WO2020224536A1 (zh)

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