Method for detecting health state of GIS insulation gas based on MEMS fiber sensor

Abstract

The application discloses a GIS insulating gas health state detection method based on a MEMS optical fiber sensor and belongs to the detection field. First, a MEMS optical fiber sensor is used to obtain the reference value of SF6 in each GIS gas chamber; then, the real-time detection is carried out on the SF6 state parameters in each GIS gas chamber to obtain real-time working values; the real-time working values and the reference values are corresponded one by one respectively, and the difference operation is carried out to realize the "vertical comparison" of each state parameter; the change amount of each SF6 state parameter corresponding to the difference value is obtained; the change amount of the same SF6 state parameter between different GIS devices or between different gas chambers of the same GIS device is compared horizontally to obtain the abnormal device gas chamber or interval. The application can realize the operation health state monitoring of the GIS device by giving the fault early warning for the health state of the GIS insulating gas and judging whether the gas insulation performance and arc extinguishing performance meet the standards or not through the detection of the gas components.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of detection, and particularly relates to an online monitoring method for health state of SF6 gas in a closed combined electrical device GIS. BACKGROUND

[0002] In recent decades, gas insulated switchgear (GIS) has been widely applied to power systems of various voltage levels due to low maintenance cost and small volume. GIS is a reliable power transmission and transformation device in which busbars, circuit breakers, disconnectors, voltage transformers, current transformers, bushings, arresters, cable termination boxes, grounding switches and other electrical components are sealed in several compartments filled with SF6 gas and combined in a certain manner. The insulating medium in the closed space is 0.3-0.4 MPa SF6 gas, which is the best arc-extinguishing and insulating medium recognized worldwide, so its insulation and arc-extinguishing performance are particularly stable compared with traditional insulating oil. Due to this excellent characteristic, power systems in various countries have been widely applied.

[0003] Due to high reliability and safety of GIS devices and small occupied area, the GIS devices are very suitable for construction of substations in large cities and industrial areas.

[0004] Research on monitoring technology of insulation performance (health state) of SF6 gas filled / pumped in GIS devices can help staff eliminate hidden troubles that can cause performance degradation of SF6 gas in time, and timely issue corresponding alarms, which has important significance for stable and reliable operation of power systems.

[0005] However, the current detection method is mostly offline monitoring method, and the detection result has periodicity, which cannot realize real-time detection of health state of insulating gas in GIS devices, and brings adverse effects on safe and stable operation of GIS devices.

[0006] The invention patent with the authorization announcement date of June 8, 2016 and the authorization announcement number of CN 103698478 B discloses a "GIS room SF6 gas concentration three-dimensional distribution monitoring system", which comprises a plurality of detection modules, the detection module comprises a plurality of pipelines and a control platform, and a detection device, a gas pump and a gas valve group connected with the control platform respectively, the gas valve group comprises a plurality of gas valves, the gas valves are installed on each pipeline, and each pipeline is connected with the gas pump; the detection device is also connected with a host computer arranged outside the GIS room; the plurality of detection modules are uniformly arranged on the preset detection surfaces of each layer in the GIS room; the control platform is used for controlling the opening and closing states of each gas valve and controlling the gas pump to be turned on, so that the gas in the GIS room is pumped into the detection device through the pipeline, and the detection device is used for outputting the concentration of the SF6 gas detected from the gas in the GIS room to the host computer. The technical scheme can realize real-time monitoring of the SF6 gas concentration in the GIS room.

[0007] However, in the technical scheme, the control platform is used for controlling the working state of the gas valve, only one gas valve is in the conducting state at the same time, and the remaining gas valves are in the off state, the mixed gas in the area covered by the selected conducting pipeline is pumped into the detection device through the gas pump, the mixed gas that has been detected is pumped out at the same time as the detection gas is pumped in, and new detection gas is pumped into the detection area, the gas detection result of the same area is calculated according to the number of times of pumping in detection test, the detection time of a single gas loop is determined according to the detection accuracy requirement; after the detection loop completes the detection, the control platform controls the gas valve to switch to the next detection loop.

[0008] Obviously, the technical scheme is to sequentially pump the mixed gas at different sites or positions into a detection device through different corresponding pipelines for analysis, and the analyzed gas is discharged at the same time. This mode needs to lay a large number of site gas pipeline on the one hand, and the equipment needs to be constructed on site, which is prone to cause the collected gas to be polluted or diluted in the transmission process due to poor sealing of the pipeline, directly affecting the accuracy of the test result; and the mixed gas at different sites can only be collected and analyzed one by one (see the drawing 2 in the specification), so the working efficiency is low, the analysis operation workload of the workers is large, the degree of automation is low, and the technical scheme cannot be applied to the monitoring of the insulation performance of the SF6 gas filled / pumped in the GIS device, and cannot adapt to the development trend and working requirements of "unattended" and "intelligent guard".

[0009] With the continuous development of power system, GIS equipment is widely used. In order to ensure the safe, stable and reliable operation of the equipment, the health status of GIS equipment, especially the detection of the insulating gas in it, is also increasingly concerned. However, since the GIS equipment is fully enclosed and filled with SF6 gas at a certain pressure, it is difficult to diagnose and repair the fault, so how to effectively judge the GIS fault is very important.

[0010] How to conveniently realize the real-time monitoring of the insulating performance (also known as the health status of insulating gas) of the SF6 gas filled / pumped in multiple GIS devices, adapt to the development trend and working requirements of "unattended" and "intelligent guard", is an actual technical problem to be solved in actual operation and maintenance. SUMMARY

[0011] The technical problem to be solved by the present application is to provide a GIS insulating gas health status detection method based on a MEMS optical fiber sensor. A MEMS switching module is arranged at the gas filling port / gas outlet port / gas valve port of the GIS, and an (or a group of) built-in MEMS optical fiber sensor is arranged on the switching module. The GIS insulating gas health status is monitored in real time and online without changing the structure and physical properties of the GIS. The state quantities such as temperature, pressure, CO gas content and SO2 gas content in the GIS are monitored online. The online detection of the SF6 component change in the GIS device is realized. Whether the gas leakage occurs in the GIS gas chamber is judged. Whether the gas insulating performance and arc extinguishing performance meet the standards can be judged through the detection of the gas component. The fault warning of the GIS insulating gas health status is realized according to the change of various physical quantities monitored by the GIS insulating gas, and the operation health status monitoring of the GIS equipment is realized.

[0012] The technical solution of the present application is to provide a GIS insulating gas health status detection method based on a MEMS optical fiber sensor, characterized by:

[0013] 1) After the installation and debugging of the GIS equipment are completed or before the GIS equipment is put into operation, the SF6 state parameters in each GIS device are detected by using the MEMS optical fiber sensor. The basic information values of SF6 in each GIS gas chamber are obtained. The basic information values at least include the temperature, pressure, water content and various gas contents of SF6 in the GIS gas chamber. The values of these state parameters are saved and set as the reference values.

[0014] 2) After the GIS equipment is put into operation, the SF6 state parameters in each GIS gas chamber are detected in real time by using the MEMS optical fiber sensor. The real-time working values are obtained.

[0015] 3) Real-time working values of SF6 state parameters are corresponded to reference values one by one, and difference operation is carried out to obtain difference values of each SF6 state parameter, realizing "vertical comparison" of each SF6 state parameter;

[0016] 4) Change amounts of each SF6 state parameter corresponding to the difference values are obtained;

[0017] 5) Change amounts of the same SF6 state parameter between different GIS devices or between different gas compartments of the same GIS device are compared horizontally, and the device gas compartment or interval with abnormality is obtained;

[0018] 6) The health state of GIS insulating gas is fault warned by adopting "vertical comparison" and "horizontal comparison" of each SF6 state parameter, realizing operation health state monitoring of the GIS device.

[0019] Specifically, the MEMS optical fiber sensor is connected with the gas inlet / gas outlet / gas valve port gas path of the GIS through a MEMS switching module.

[0020] Further, the GIS insulating gas health state detection method improves the reliability of system discrimination by adopting "vertical comparison" and "horizontal comparison" of each SF6 state parameter.

[0021] Specifically, the MEMS optical fiber sensor at least includes a MEMS pressure sensor, a MEMS humidity sensor, a MEMS gas sensor and an integrated product thereof.

[0022] Further, the MEMS optical fiber sensor at least includes a refractive index module, a pressure module, a temperature module and CO and SO2 modules.

[0023] Specifically, the basic information of SF6 at least includes state amounts such as temperature, pressure, CO gas content and SO2 gas content.

[0024] Further, the GIS insulating gas health state detection method selects gas CO and SO2 as insulating gas health state discrimination indexes in addition to temperature, pressure and micro water indexes, and judges the insulating state inside the GIS through real-time monitoring of the CO content.

[0025] Specifically, the gas type and allowable value corresponding to each defect type are defined as the pre-limit value of a certain insulating performance index.

[0026] When the "vertical comparison" is carried out, the case that the real-time detection value of the SF6 insulating gas related parameter exceeds the pre-limit value is taken as the logical action condition of the output alarm signal;

[0027] Or, in the process of the "lateral comparison", the real-time detection value of SF6 insulation gas related parameters exceeds the pre-limit value, which is taken as the logic action condition of outputting the alarm signal.

[0028] Specifically, the MEMS switching module is a mechanical structure switching module with a three-way gas path structure, which is provided with a gas inlet end, a detection end and a gas outlet end on the body, and is internally provided with a three-way gas channel.

[0029] A sealing connection structure corresponding to / matching the GIS valve port is arranged on the outer periphery of the gas inlet end.

[0030] A sealing connection structure corresponding to / matching the optical fiber sensor is arranged on the outer periphery of the detection end.

[0031] A connection structure identical to the gas valve port of the GIS device is arranged on the outer periphery of the gas outlet end, so as to maintain the function of the original GIS device gas valve port.

[0032] The gas inlet end of the MEMS switching module is connected with the gas valve port of the GIS.

[0033] The detection end of the MEMS switching module is connected with the MEMS optical fiber sensor.

[0034] The gas outlet end of the MEMS switching module serves as a new gas charging / discharging end, and realizes the corresponding function of the original gas valve port.

[0035] Further, the GIS insulation gas health state detection method can realize online detection of the change of SF6 components in the GIS device, judge whether the gas leakage occurs in the GIS gas chamber, and judge whether the gas insulation performance and arc extinguishing performance meet the standards through the detection of the gas components, and can realize the operation health state monitoring of the GIS device.

[0036] Compared with the prior art, the advantages of the present application are:

[0037] 1. The technical scheme of the present application can directly qualitatively and quantitatively measure, realize full-range and high-precision real-time online detection of the CO, SO2 and other component contents in SF6 in the GIS device, and the pressure and temperature parameters, and can realize online detection of the abnormal state of the gas caused by insulation deterioration and faults of the GIS device, fault early warning and diagnosis without taking the gas from the gas chamber of the running device.

[0038] 2. By setting the MEMS switching module between the GIS gas valve port and the MEMS optical fiber sensor, the connection structure and sealing mode between the GIS and the MEMS optical fiber sensor produced by different manufacturers can be standardized or adapted, the connection mode can be unified, the sealing effect can be maintained, and the corresponding functions of the original gas valve port can be maintained;

[0039] 3. By adopting real-time monitoring of the CO content, the insulation state in the GIS is judged, and whether the gas insulation performance and arc extinguishing performance meet the standards is judged by detecting the gas components, which not only conforms to the relevant provisions of the existing national standard, but also meets the needs of the health state monitoring of the GIS equipment operation;

[0040] 4. The optical fiber is used as a transmission line, and the relative position of the measuring instrument and the measured object does not need to be considered, which is especially suitable for occasions where electrical sensors are not suitable, remote measurement and control are realized, the anti-impact overload capacity is good, the failure rate is extremely low, and the subsequent maintenance is free;

[0041] 5. The technical scheme of the present application improves the reliability of system discrimination by comparing the changes of the temperature, pressure and gas content of SF6 insulation gas in the horizontal and vertical directions twice. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1a It is a three-dimensional structure schematic diagram of the MEMS optical fiber sensor;

[0043] Figure 1b It is a side view structure schematic diagram of the MEMS optical fiber sensor;

[0044] Figure 1c It is a top view structure schematic diagram of the MEMS optical fiber sensor;

[0045] Figure 2a 、 Figure 2b and Figure 2c It is a structure schematic diagram of one embodiment of the MEMS switching module of the present application;

[0046] Figure 3a 、 Figure 3b and Figure 3c It is a structure schematic diagram of another embodiment of the MEMS switching module of the present application;

[0047] Figure 4 It is a block schematic diagram of the horizontal difference-longitudinal difference algorithm of the present application;

[0048] Figure 5 It is a schematic diagram of the GIS insulation gas health state detection method of the present application.

[0049] In the figure, A is a measurement end, A1 is a sensor, B is an external thread, C is a fastening nut, D is an optical cable connector, and E is a signal transmission optical cable;

[0050] 1 is a body, 2 is an air inlet end, 3 is a detection end, 4 is an air outlet end, 5 is a nut, 6 is an external thread, 7 is a MEMS optical fiber sensor, 8 is a sealing end face, 9 is a connecting short tube, and 10 is a flat flange. DETAILED DESCRIPTION

[0051] The application will be further described below in combination with the drawings and examples.

[0052] For the application status of SF6 gas monitoring of a transformer substation, it is mainly divided into distributed and centralized. The distributed is by setting multiple collection nodes on the site, each node is provided with a device for detecting SF6 gas, and then each device transmits the measurement signal to the background through a cable. At present, the mainstream device in this mode is to collect gas concentration by directly using a sulfur hexafluoride gas sensor, and a functional perfect on-site collection device is built on this basis. The advantage is that it can be placed flexibly according to the situation, and the price is low, but the measurement accuracy is generally low, and a large amount of wiring is required on site, which greatly increases the work difficulty. The centralized is mainly the detection device based on the laser infrared detection principle, for example, the infrared laser imaging SF6 gas positioning system of LIS in the United States. This positioning system can not only locate the gas leakage point, but also accurately measure the concentration value, but it is too expensive, and the device is relatively large, and the measurement point is not as random as the distributed.

[0053] The technical scheme of the application adopts a MEMS switching module at the gas inlet / gas outlet / gas valve of GIS, a (or a group of) built-in MEMS optical fiber sensor is arranged on the switching module, the health state of the insulating gas in the GIS is monitored in real time and on line without changing the structure and physical properties of the GIS, the state quantities such as temperature, pressure, CO gas content and SO2 gas content in the GIS are monitored on line, the on-line detection of the SF6 component change in the GIS device is realized, it is judged whether the gas leakage occurs in the GIS gas chamber, and it can be judged whether the gas insulation performance and arc extinguishing performance meet the standards through the detection of the gas component; a fault discrimination algorithm is adopted, the health state of the GIS insulating gas is prewarned according to the change of various physical quantities monitored by the GIS insulating gas, and the operation health state monitoring of the GIS device is realized.

[0054] The specific technical details involved in the technical scheme will be described below.

[0055] I. MEMS optical fiber sensor:

[0056] MEMS (Micro-Electro-Mechanical System) fiber sensor belongs to passive sensor, which does not need external power supply during installation and use, and is simple to operate and convenient to use. The transmission signal of MEMS fiber sensor is optical signal, and the transmission line adopts optical cable. Therefore, whether it is fiber sensor or optical transmission cable, the interference of environmental electromagnetic field has no effect on it, and it is more suitable for installation on power equipment than active sensor. MEMS fiber sensor is made of micro-electromechanical technology, which is easy to mass-produce and effectively reduces manufacturing cost. The transmission signal is transmitted by optical fiber, and the transmission line has long service life and low operating cost. The response time of MEMS fiber gas sensor based on infrared spectrum absorption theory is short, and the sensor can be directly installed on GIS through a specific device without taking gas, so that real-time online monitoring can be realized.

[0057] In Figures 1a to 1c , a structural diagram of MEMS fiber sensor is given, which includes a measuring end A with external thread B and fastening nut C. A plurality of different types of sensors A1 are arranged at the front end of the measuring end. An optical cable connector D is arranged at the rear end of the measuring end. The optical cable connector is connected with a signal transmission optical cable E. The signal transmission optical cable outputs the detection result of the MEMS fiber sensor.

[0058] The fiber sensor has a plurality of classification methods. According to the sensing principle, it can be divided into functional sensor and non-functional sensor. The functional fiber sensor is also called sensing fiber sensor, in which the fiber directly serves as a sensitive element. The non-functional fiber sensor is also called light transmission fiber sensor, in which the fiber only serves as a medium for transmitting optical signal, and other light-sensitive elements are needed to sense the change of external environment.

[0059] In the technical solution, in order to detect the health status of the insulating gas in GIS, MEMS pressure sensor, MEMS humidity sensor, MEMS gas sensor and their integrated products can be used to meet the technical requirements of combined detection required by the technical solution.

[0060] II. Selection of SF6 basic information index

[0061] According to the existing relevant national standards of GIS and SF6, such as GB / T 7674 rated voltage 72.5kV and above gas insulated metal enclosed switchgear, GB / T 8905 gas management and detection guide in SF6 electrical equipment, GB / T 11022 common technical requirements of high voltage switchgear and control equipment standard, GB / T 28537 use and processing of SF6 (SF6) in high voltage switchgear and control equipment, etc., the related indexes for judging the health status of GIS insulating gas are obtained. As shown in Tables 1, 2 and 3.

[0062] Table 1 SF6 decomposition products specified by state standard

[0063]

[0064] Table 2 Other important SF6 decomposition products

[0065] Characteristic gas General value Maximum value SOF2 (sulfuryl fluoride) ≤ 1 μL / L None CO (carbon monoxide) ≤ 100 μL / L ≤ 200 μL / L SO2F2 (sulfuryl fluoride) ≤ 1 μL / L None

[0066] Table 3 Gas species generated by different defect types

[0067]

[0068] Considering that H2S is generally not detected and is a characteristic product of high-energy partial discharge, HF is a strong acid substance and will react with equipment and insulation materials to generate stable substances, so it will gradually decrease. Therefore, in addition to temperature, pressure and micro water, the technical solution additionally selects two gases, CO and SO2, as the health state discrimination of the insulation gas. SO2 is a main stable product of SF6 discharge and will be generated in all partial discharges, and CO is a carbon-containing product, and the main source of carbon elements is the internal insulation material of GIS. The internal insulation state of GIS can be judged by real-time monitoring of the CO content.

[0069] Specifically, the technical solution of the present application selects the following optical fiber sensing module in the optical fiber sensor:

[0070] The refractive index module: the Fabry-Perot (F-P) interference principle is used, and the different density refractive indexes of the gas affect the cavity length change of the F-P sensitive cavity inside the sensor. Under the action of the gas, the F-P cavity length changes accordingly, so that the incident light is modulated. By demodulating the light output signal containing pressure information, the refractive index of the gas can be obtained.

[0071] The pressure module: the Fabry-Perot (F-P) interference principle is used to convert the pressure change into the cavity length change of the F-P pressure sensitive cavity inside the sensor. The F-P pressure sensitive cavity is composed of two parallel planes with a certain reflectivity, and the light beam is reflected multiple times between them to form a multi-beam interference. Under the action of pressure, the F-P cavity length changes accordingly, so that the incident light is modulated. By demodulating the light output signal containing pressure information, the pressure value can be obtained, and the accurate height of the measured liquid can also be calculated.

[0072] The temperature module: the FBG grating is adopted, and the temperature sensitive effect of the FBG grating is used to accurately measure the ambient temperature by linearly changing the wavelength with temperature.

[0073] CO and SO2 module: using Lamber-Beer law and infrared spectrum absorption principle, when a continuous wavelength parallel infrared light passes through a certain gas, the vibration frequency or rotation frequency of a certain group of gas molecules is consistent with the frequency of the infrared light, the gas molecules will absorb energy and jump from the ground state energy level to the higher energy level, the infrared light at the frequency will be absorbed to form an absorption peak, and the characteristic gas content is obtained through the absorption peak of CO and SO2 at the characteristic infrared wavelength.

[0074] The refractive index module and the pressure module are both sensitive to pressure and gas characteristics by using the reflected optical spectrum of the MEMS fiber F-P sensor, and the input light source excitation / output optical spectrum analysis of the MEMS fiber F-P sensor is completed by the internal function modules of the fiber sensing analyzer, and the pressure and gas refractive index information of each monitoring point are given in digital form.

[0075] In addition, the optical fiber is not only a sensitive element, but also an excellent low-loss transmission line, so it is almost unnecessary to consider the relative position of the measuring instrument and the measured object, and it is particularly suitable for occasions where electrical sensors are not suitable. It can be combined with optical fiber remote sensing technology to realize remote measurement and control. It has good anti-shock overload capacity, extremely low failure rate, maintenance-free follow-up, and can accurately measure for a long time. It has more obvious advantages in application occasions where installation and operation are not convenient and maintenance is difficult.

[0076] III. MEMS switching module:

[0077] The MEMS switching module is used to monitor the health status of the insulation gas in the GIS without changing the structure and physical properties of the GIS.

[0078] The MEMS switching module is a mechanical switching module, which has three connection ends, namely the gas inlet end 2, the detection end 3 and the gas outlet end 4, and a three-way gas channel in the interior. A sealing connection structure corresponding to and matching the GIS gas inlet / outlet / gas valve port (hereinafter referred to as gas valve port) is arranged on the outer periphery of the gas inlet end, a sealing connection structure corresponding to and matching the optical fiber sensor is arranged on the outer periphery of the detection end, and a connection structure identical to the gas valve port of the GIS device is arranged on the outer periphery of the gas outlet end to maintain the function of the original gas valve port of the GIS device.

[0079] The gas inlet end of the MEMS switching module is connected to the gas valve port of the GIS, the detection end is connected to the MEMS optical fiber sensor 7, and the gas outlet end serves as a new gas charging / discharging end to realize the corresponding function of the original gas valve port.

[0080] Because the gas valve port structures of GISs of different manufacturers are different, the structures of the gas inlet end and the gas outlet end of the MEMS switching module in the technical solution are also different, so as to be matched with the gas valve ports of the corresponding manufacturers' GISs.

[0081] Specifically, as shown in Figures 2a to 2c For the gas valve port using the threaded connection structure, the MEMS switching module in the technical solution is provided with a nut 5 with an internal thread at the gas inlet end 2 and a gas valve port with an external thread 6 at the gas outlet end.

[0082] As shown in Figures 3a to 3c For the gas valve port using the flange connection structure, the MEMS switching module in the technical solution is provided with a flat flange 10 with a sealing end face 8 at the gas inlet end 2 and a flat flange with a connecting short pipe 9 at the gas outlet end.

[0083] Four, online monitoring method:

[0084] As shown in Figure 5 After the completion of the connection of each hardware, the technical solution of the application detects the health state of the insulating gas of the GIS according to the following steps:

[0085] 1) After the installation and debugging of the GIS equipment are completed or before the equipment is put into operation, the SF6 state parameters in each GIS equipment (referred to as gas chamber or interval) are detected using the MEMS optical fiber sensor, and basic information values of SF6 including temperature, pressure and gas content in the GIS gas chamber are obtained. These values are saved and set as reference values.

[0086] 2) After the GIS equipment is put into operation, the SF6 state parameters of each GIS gas chamber are detected in real time using the MEMS optical fiber sensor. The real-time data measured by the MEMS optical fiber sensor are counted, and at any time during the operation of the GIS equipment, the temperature, pressure and gas content information of each interval gas chamber at the current time can be obtained. These real-time values are corresponded one by one with the above-mentioned reference values and subjected to "difference" operation, and the obtained difference values are saved. This process is referred to as "vertical comparison".

[0087] 3) The difference value corresponds to the change amount of the SF6 insulating gas including the temperature, pressure and gas content values of the gas.

[0088] Although the measured reference values of different gas chambers may have deviations, the above-mentioned change amounts are the same.

[0089] 4) By comparing the change amounts of the SF6 insulating gas in different gas chambers, the equipment gas chamber or interval with abnormality can be clearly obtained. This process is referred to as "horizontal comparison".

[0090] 5) Through the transverse and longitudinal comparison twice, improve the reliability of system identification.

[0091] 6) The health state of GIS insulation gas failure warning, realize the operation health state monitoring of GIS equipment.

[0092] Regarding the "longitudinal comparison" and "transverse comparison" of SF6 insulation gas related parameters in the technical solution, see Figure 4 .

[0093] Obviously, in the technical solution, the "longitudinal comparison" refers to the comparison between the reference value and the real-time detection value of the SF6 insulation gas related parameters, which can know the deviation between the real-time detection value and the reference value, and be used for identifying the development trend and development direction of the real-time detection value; In the technical solution, the "longitudinal comparison" refers to the comparison of SF6 state parameters between different GIS devices or each GIS gas warehouse, which belongs to the comparison of a certain same SF6 state parameter between different GIS devices or each GIS gas warehouse. It can conveniently find out the abnormality or deviation of the specific SF6 state parameter, and can clearly obtain the abnormal device gas warehouse or interval.

[0094] Further, if the gas type and allowable value corresponding to each defect type in the foregoing table 3 is expressed as a pre-limit value of a certain insulation performance index, the real-time detection value of the SF6 insulation gas related parameters exceeding the pre-limit value can be used as the logical action condition of the "longitudinal comparison" output alarm signal.

[0095] Or, when performing "transverse comparison", the change amount corresponding to a certain index of SF6 insulation gas exceeding a pre-limit value of a certain insulation performance index is used as the logical action condition of the "transverse comparison" output alarm signal.

[0096] The SF6 state parameters are compared twice in the transverse and longitudinal directions, which helps to improve the reliability of system identification.

[0097] 1) Installation of MEMS integrated optical fiber sensor:

[0098] The multi-state MEMS optical fiber sensor is installed at each GIS gas valve interface.

[0099] The MEMS optical fiber sensor is installed by the manufacturer before leaving the factory and is sealed for testing.

[0100] 2) MEMS adapter module installation:

[0101] The MEMS adapter module is installed by the GIS manufacturer before leaving the factory and is sealed for testing.

[0102] MEMS tail fiber (i.e. optical fiber) is connected to the monitoring screen cabinet through the secondary cable of GIS equipment.

[0103] 3) Photoelectric conversion system screen cabinet installation:

[0104] The photoelectric conversion system screen cabinet is composed of multiple MEMS signal receiving / transmitting units, and is built in a standard cabinet together with the server.

[0105] The cabinet is placed in the main control room, and the bottom is fixed by channel steel welding or other methods according to the inherent regulations of the site.

[0106] 4) GIS equipment detection terminal interface:

[0107] The photoelectric conversion system demodulates the optical signals obtained by each MEMS integrated optical fiber sensor, and transmits the demodulated electrical signals to the server in the main control room cabinet, and completes the online monitoring and fault warning of the GIS equipment insulating gas in the main control room.

[0108] In the server, a background centralized monitoring software is provided, including state monitoring, event recording, historical data, system configuration, communication configuration and other functions.

[0109] In the technical scheme of the application, the state monitoring function is mainly used to realize real-time monitoring and fault warning of the temperature, pressure, refractive index, CO and SO2 concentration of each GIS equipment.

[0110] The event recording function mainly realizes the storage, query and export of various warning states.

[0111] The historical data function mainly realizes the storage, program and export of historical data of each GIS equipment.

[0112] The system configuration function mainly realizes the setting of the name and warning value of each GIS equipment.

[0113] The communication configuration function mainly realizes the configuration of the communication parameters of the GIS equipment monitoring terminal and the detection of the communication data.

[0114] Since the implementation methods or approaches of the event recording, historical data, system configuration and communication configuration functions are all prior art, those skilled in the art can easily realize the corresponding functions according to the software settings of the database software and the operating system, so they will not be described in detail here.

[0115] In conclusion, in the technical solution of the present application, CO and SO2 sensors using light intensity reflection type sensors based on light intensity modulation as the basic sensing principle, pressure sensors and refractive index sensors based on Fabry-Perot as the basic sensing principle, and temperature sensors based on Bragg grating principle. Then, through MEMS technology, the optical fiber sensors of different principles are combined into a set of composite MEMS optical fiber sensors.

[0116] The MEMS optical fiber sensor is based on light intensity reflection type sensors based on light intensity modulation. Such sensors are made by different gas-sensitive materials producing different reaction mechanisms. The light of a specific wavelength is irradiated to the characteristic gas chamber, which absorbs a certain amount of light, resulting in a certain change in reflected light intensity. The change in characteristic gas content is obtained by demodulating the change in light intensity. The above sensors are all double-arm structures. The measurement arm is used to sense the change in light intensity, and the reference arm is used to monitor the environmental quantity and compensate the measurement arm for various environmental quantities. Two types of sensors are made by MEMS technology, and the CO and SO2 sensors are combined into one sensor.

[0117] Since the MEMS optical fiber sensor is mainly based on light intensity modulation and wavelength modulation, the corresponding demodulation unit is also divided into two parts. The CO and SO2 sensors based on intensity modulation are demodulated by an intensity modulation demodulator to obtain the physical quantity value of CO and SO2 in GIS. The refractive index, pressure, and temperature sensors based on wavelength modulation are demodulated by a wavelength modulation demodulator. Since the wavelength modulation type sensor is generally affected by the environment temperature, the corresponding pressure sensor and refractive index sensor are temperature compensated, making the corresponding physical quantities of pressure and refractive index more accurate and stable.

[0118] In the present technical solution, the CO and SO2 sensors are made and packaged by MEMS technology, and are calibrated. In order to complete the temperature compensation, two different sensors are packaged by MEMS technology—MEMS optical fiber temperature pressure sensor and MEMS optical fiber temperature refractive index sensor, which respectively complete the measurement of temperature, pressure and refractive index.

[0119] Through a series of verification tests such as sensitivity, calibration and long-term stability, the response speed of all sensors except the CO sensor is in seconds, and the response speed of the CO sensor is also in minutes. All types of sensors can meet the requirements of GIS online monitoring.

[0120] The technical scheme of the present application uses the MEMS optical fiber sensor to detect the GIS device, obtains basic information such as temperature, pressure, gas content, saves these values and sets them as reference values, statistically processes the real-time data measured by the MEMS optical fiber sensor, and at any moment during the operation of the GIS, obtains information such as temperature, pressure, gas content at the current moment, makes these values correspond to the reference values in the above one by one and performs difference operation, saves the obtained difference value, and this process is called longitudinal comparison.

[0121] The obtained values of different gas compartments of the GIS are the same in the above change amount, and under the same working environment, the change amount of the environment must be uniform. In addition, under the normal working state, the comparison of the change amount of the state quantity can clearly obtain the abnormal device, which is simple and clear, and this process is called horizontal comparison. Through the two comparisons of the horizontal and longitudinal directions, the reliability of the system judgment is improved.

[0122] Through the implementation of the technical scheme, real-time online detection of the change of the SF6 component in the GIS device can be realized, it can be judged whether the GIS gas chamber leaks, and whether the gas insulation performance and arc extinguishing performance meet the standards can be judged through the detection of the gas component, and high-precision online detection of the GIS gas can be realized.

[0123] After the technical scheme is adopted, a large amount of data collection can provide sufficient sample analysis for fault analysis of the GIS device, and further fault judgment and positioning of the GIS device in the power grid can be facilitated.

[0124] In addition, after the technical scheme is adopted, real-time early warning and diagnosis of the abnormal gas insulation of the GIS device can help to take corresponding repair measures in time, avoid economic losses caused by equipment replacement order cycle and extreme explosion accidents, and the like.

[0125] The technical scheme can comprehensively improve the level of multi-parameter GIS device detection technology, and provide a technical foundation and experimental means for further research on GIS device fault positioning and joint development of later-stage products.

[0126] The present application can be widely used in the field of operation state monitoring and fault monitoring of GIS.

Claims

1. A GIS insulating gas health state detection method based on a MEMS optical fiber sensor, characterized by: 1) After the installation and commissioning of the GIS device are completed or before it is put into operation, the SF6 state parameters in each GIS device are detected using a MEMS optical fiber sensor to obtain the basic information values of the SF6 in each GIS gas chamber, which at least include the temperature, pressure, water content, and various gas contents of the SF6 in the GIS gas chamber, save the values of these state parameters, and set them as the reference values; 2) After the GIS device is put into operation, the SF6 state parameters in each GIS gas chamber are detected in real time using a MEMS optical fiber sensor to obtain real-time working values; 3) The real-time working values of the SF6 state parameters are corresponded to the reference values one by one, and difference operation is performed to obtain the differences of each SF6 state parameter, realizing the longitudinal comparison of each SF6 state parameter; 4) The change amounts of each SF6 state parameter corresponding to the differences are obtained; 5) The change amounts of the same SF6 state parameter between different GIS devices or different gas chambers of the same GIS device are compared horizontally to obtain the abnormal device gas chamber or interval; 6) The longitudinal comparison and horizontal comparison of each SF6 state parameter are adopted to perform fault early warning on the health state of the GIS insulating gas, realizing the operation health state monitoring of the GIS device; Wherein, the MEMS optical fiber sensor is connected with the gas inlet, gas outlet, or gas valve port of the GIS through a MEMS adapter module; The MEMS adapter module is a mechanical structure conversion module with a three-way gas path structure built-in, which is provided with a gas inlet end, a detection end, and a gas outlet end on the body, and is provided with a three-way gas channel inside; A sealing connection structure matched with the GIS gas valve port is arranged on the outer periphery of the gas inlet end; A sealing connection structure matched with the optical fiber sensor is arranged on the outer periphery of the detection end; The same connection structure as the gas valve port of the GIS device is arranged on the outer periphery of the gas outlet end to maintain the function of the original GIS device gas valve port; The gas inlet end of the MEMS adapter module is connected with the gas valve port of the GIS; The detection end of the MEMS adapter module is connected with the MEMS optical fiber sensor; The gas outlet end of the MEMS adapter module serves as a new gas charging / discharging end to realize the corresponding function of the original gas valve port; The GIS insulating gas health state detection method sets a MEMS adapter module at the gas inlet, gas outlet, or gas valve port of the GIS, and sets one or a group of built-in MEMS optical fiber sensors on the adapter module, so as to realize real-time online monitoring of the health state of the insulating gas in the GIS without changing the structure and physical properties of the GIS.

2. The method of claim 1, wherein the method is characterized in that The MEMS optical fiber sensor at least includes a MEMS pressure sensor, a MEMS humidity sensor, a MEMS gas sensor, and an integrated product thereof.

3. The method of claim 1, wherein the method is characterized in that The MEMS optical fiber sensor at least includes a refractive index module, a pressure module, a temperature module, and CO and SO2 modules.

4. The method of claim 1, wherein the method is characterized in that The basic information of the SF6 includes at least state quantities such as temperature, pressure, CO gas content and SO2 gas content.

5. The method of claim 1, wherein the method is characterized in that The GIS insulation gas health state detection method selects CO and SO2 as insulation gas health state discrimination indexes in addition to temperature, pressure and water content indexes, and judges the insulation state inside the GIS through real-time monitoring of the CO content.

6. The method for detecting the health status of GIS insulating gas based on MEMS fiber optic sensors according to claim 1, characterized in that: The gas type and allowable value corresponding to each defect type are defined as the pre-limit value of a certain insulation performance index. In the longitudinal comparison, the case that the real-time detection value of the SF6 insulation gas related parameter exceeds the pre-limit value is taken as the logical action condition of the output alarm signal. Or, in the transverse comparison, the case that the real-time detection value of the SF6 insulation gas related parameter exceeds the pre-limit value is taken as the logical action condition of the output alarm signal.

7. The method of claim 1, wherein the method is characterized in that The GIS insulation gas health state detection method realizes online detection of the SF6 component change in the GIS device, judges whether the gas leakage occurs in the GIS gas chamber, judges whether the gas insulation performance and arc extinguishing performance meet the standards through detection of the gas component, and performs fault early warning on the health state of the GIS insulation gas according to the change of various physical quantities monitored by the GIS insulation gas, so as to realize the operation health state monitoring of the GIS device.

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