Gas volume monitoring method in gas relay

Abstract

The invention discloses a method for monitoring the volume of gas in a gas relay, and relates to the field of transformer state monitoring and fault diagnosis. A quantitative relation curve between different transformer oil liquid level heights and Raman signal intensity and a relation curve between the internal volume and height of the gas relay are established, the quantitative relation between Raman detection signals and the internal gas of the gas relay is finally achieved, and effective monitoring of the volume value of the light gas in the gas relay is achieved.

Description

Technical Field

[0001] The invention relates to the field of transformer state monitoring and fault diagnosis, and in particular to a method for monitoring gas volume in a gas relay. Background Art

[0002] Transformers are basic equipment for power transmission and distribution, and are widely used in industries, agriculture, transportation, urban communities, and other fields. Transformers occupy a very important position in power transportation, and ensuring the normal operation of transformers is the primary task to ensure the normal transportation of power. Gas relays are a type of transformer protection device, installed on the pipeline between the transformer oil pillow and the transformer body. When defects or faults occur inside the transformer, the gas or oil flow generated will cause the gas relay to operate, send out an alarm signal, or trigger protection to disable the transformer.

[0003] In recent years, with the continuous development of power grid equipment, the number of transformers has been increasing, and the number of transformer defects and abnormal problems has also been gradually increasing. When a general fault occurs inside the transformer oil tank, the generated gas accumulates on the upper part of the gas relay, causing light gas action. However, the existing gas relay can only perform light gas action and send out corresponding alarm signals after the gas accumulation reaches a certain specific value through a half-cup or float, and cannot monitor the gas volume in the gas relay in real time. The operation and maintenance personnel can know that the transformer has a fault based on the alarm signal, but the time of the fault, the type of fault, the cause and severity of the fault need to be quickly organized. Substation operation and inspection personnel need to conduct on-site inspections of the gas accumulation in the gas relay. If there is a false alarm, a lot of manpower and material resources will be wasted. According to incomplete statistics, from 2014 to 2024, the false alarm rate of light gas transformers with a voltage level of 110 kV and above was about 17.6%. Among them, in 92.8% of the light gas false alarms, the gas volume in the gas relay is far from reaching the alarm value (currently, a light gas alarm signal is issued only when the gas in the gas relay reaches the specified volume threshold). Therefore, how to obtain the real volume of gas in the gas relay in real time has always been a technical problem that troubles transformer operators. Summary of the invention

[0004] In order to overcome the deficiencies of the above technologies, the present invention provides a method for monitoring gas volume in a gas relay, which can compare the gas volume value with the set volume alarm threshold value, and is convenient for quickly judging whether light gas is falsely reported. The technical solution adopted by the present invention to overcome the technical problems is:

[0005] A method for monitoring gas volume in a gas relay, comprising:

[0006] S1. The Raman fiber sensor is inserted from top to bottom into the gas relay of the transformer. The Raman fiber sensor is vertically arranged with its bottom located at the lower end of the lower float of the gas relay. A temperature sensor is installed at the fiber probe of the Raman fiber sensor.

[0007] S2. Insert the Raman fiber sensor into the gas relay to measure m different liquid levels of transformer oil at 1435cm -1 The Raman signal intensity at

[0008] S3. Calculate the temperature correction coefficient W t ;

[0009] S4. Using the temperature correction factor W t Correction of Raman signal intensity;

[0010] S5. Draw the transformer liquid level - Raman signal intensity curve according to the liquid level and the corrected Raman signal intensity;

[0011] S6. Add deionized water to the gas relay, measure the liquid level and gas height in the gas relay, and draw a volume-height curve inside the gas relay;

[0012] S7. After the Raman fiber optic sensor detects the Raman signal intensity, it obtains the corresponding liquid level according to the transformer liquid level-Raman signal intensity curve, and uses the obtained liquid level to obtain the corresponding gas volume inside the gas relay according to the gas relay internal volume-height curve.

[0013] Furthermore, in step S1, the contact surface between the Raman optical fiber sensor and the gas relay is sealed using oil-resistant rubber.

[0014] Furthermore, the optical fiber probe of the above Raman optical fiber sensor has a plurality of holes evenly distributed along the circumferential direction from top to bottom, and the diameter of the holes is 4 nm.

[0015] Furthermore, under the condition of 25° C., the Raman fiber optic sensor was inserted into the gas relay at different liquid level heights, and the height difference between every two adjacent liquid levels was 1 mm.

[0016] Further, step S2 includes the following steps:

[0017] S21. Insert the Raman fiber sensor into the gas relay to measure m different liquid levels of transformer oil at 1435cm -1 The Raman signal intensity at the kth measurement point is X k , k∈{1,...,m}; S22. Insert 10 insertion points between the kth measurement point and the k+1th measurement point, and use the formula X ki =X k +i*(Xk+1 -X k ) / 10The liquid level at the i-th insertion point, i∈{1,2...,10}; S23. The signal strength detected by the Raman fiber optic sensor at the k-th measurement point is Q k , the signal strength detected by the Raman fiber optic sensor at the k+1th measurement point is Q k+1 , insert 10 insertion points between the kth measurement point and the k+1th measurement point, and use the formula

[0018] Q ki =Q k +i*(Q k+1 -Q k ) / 10-(Q k+2 -(Q k +(Q k+1 -Q k ) / (X k+1 -X k )*(X k+2 -X k )))

[0019] / (Q k+2 -Q k )*(10.5-i+RAND()) / 10*(Q k+1 -Q k )

[0020] The signal strength Q of the i-th insertion point ki , i∈{1,2...,10}, RAND() is a random number between 0 and 1.

[0021] Furthermore, in step S3, the formula

[0022] W t =((Q5-Q 5t ) / Q5+(Q 10 -Q 10t ) / Q 10 +(Q 15 -Q 15t ) / Q 15 +(Q 20 -Q 20t ) / Q 20 ) / 4 to calculate the temperature correction coefficient W at temperature t t , t∈{0℃,...,40℃}, where Q5 is the signal intensity detected by the Raman fiber sensor when the liquid level is 5cm at 25℃, Q 10 is the signal intensity detected by the Raman fiber optic sensor when the liquid level is 10 cm at 25 degrees Celsius, Q 15is the signal intensity detected by the Raman fiber optic sensor when the liquid level is 15 cm at 25 degrees Celsius, Q 20 is the signal intensity detected by the Raman fiber optic sensor when the liquid level is 20 cm at 25 degrees Celsius, Q 5t is the signal strength detected by the Raman fiber optic sensor when the liquid level is 5 cm at temperature t, Q 10t is the signal strength detected by the Raman fiber optic sensor when the liquid level is 10 cm at temperature t, Q 15t is the signal strength detected by the Raman fiber optic sensor when the liquid level is 15 cm at temperature t, Q 20t The signal intensity detected by the Raman fiber optic sensor when the liquid level is 20 cm at temperature t.

[0023] Further, step S5 includes the following steps:

[0024] S51. Through the formula Q k ′=W t *Q k Calculate the signal strength Q of the kth measurement point detected after correction at temperature t k ′;

[0025] S52. Through formula Q ki ′=W t *Q ki Calculate the signal intensity Q of the ith insertion point after correction at temperature t ki ′;

[0026] S53. Using the liquid level heights at m measuring points and the liquid level heights at all insertion points as the horizontal axis coordinates, and using the signal strengths detected at the m measuring points and the signal strengths at all insertion points as the vertical axis coordinates, a transformer liquid level height-Raman signal strength curve is obtained.

[0027] Further, step S6 includes the following steps:

[0028] S61. Add deionized water to the gas relay in sequence with Pml as the single measurement, and use the laser rangefinder to measure the liquid level H after the i-th water addition. i , i∈{1,...,n}, n is the number of times deionized water is added;

[0029] S62. Through the formula Calculate the gas volume inside the gas relay after the i-th water addition, where V is the total volume inside the gas relay;

[0030] S63. Draw a gas relay internal volume-height curve with n liquid level heights as the horizontal coordinate and n gas volumes inside the gas relays as the vertical coordinate.

[0031] Preferably, the value of P is 5.

[0032] Furthermore, it also includes step S7 of obtaining the gas volume inside the gas relay and determining whether it exceeds a light gas alarm value, wherein the alarm value is 250 mL. If it exceeds the value, an alarm signal is issued.

[0033] The beneficial effects of the present invention are:

[0034] 1) Raman fiber optic sensor is used to detect the liquid level inside the gas relay using the Raman signal intensity of transformer oil. A non-destructive sensing method for fast and efficient liquid level detection is proposed.

[0035] 2) The quantitative relationship curves between the oil level height of different transformers and the Raman signal intensity, and the relationship curves between the internal volume and height of the gas relay were established. Finally, the quantitative relationship between the Raman detection signal and the gas inside the gas relay was realized, and the effective monitoring of the light gas volume value inside the gas relay was realized. Instead of the traditional single value action light gas volume value determination method, the problem of being unable to judge whether it is a false alarm when the light gas action of the oil-immersed transformer is in progress can be solved. It can provide data support for the operation and maintenance personnel to grasp the real operating status of the equipment and formulate targeted operation and maintenance strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a structural diagram of the Raman optical fiber sensor of the present invention;

[0037] Figure 2 A position diagram of the Raman optical fiber sensor of the present invention;

[0038] Figure 3 is a flow chart of the method of the present invention;

[0039] Figure 4 The transformer liquid level-Raman signal intensity curve diagram of the present invention;

[0040] Figure 5 The internal volume-height curve of the gas relay of the present invention;

[0041] In the figure, 1. Fiber optic signal transmission line 2. Fiber optic probe 3. Gas relay 4. Bottom float ball. DETAILED DESCRIPTION

[0042] The following is combined with Figure 1 , Attachment Figure 2 , Attachment Figure 3 The preferred embodiments of the present invention are described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0043] In the description of the present invention, it should be noted that the embodiments described in the present invention are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention. The terms "first", "second", etc. in the specification and claims of this article and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of this article described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment. A method for monitoring gas volume in a gas relay, comprising:

[0044] S1. Insert the Raman fiber sensor from the top to the bottom of the gas relay 3 of the transformer. The Raman fiber sensor is set vertically, and its bottom is located at the lower end of the lower float 4 of the gas relay 3. Figure 2 As shown, the Raman optical fiber sensor is placed vertically and installed at 90 degrees to the bottom plane of the gas relay 3. A temperature sensor is configured at the position of the optical fiber probe 2. The temperature sensor is used to detect the oil temperature inside the gas relay 3.

[0045] S2. Insert the Raman fiber sensor into the gas relay 3 to measure m different liquid levels of transformer oil at 1435cm -1 The Raman signal intensity at .

[0046] S3. Calculate the temperature correction coefficient W t .

[0047] S4. Using the temperature correction factor W t Correct the Raman signal intensity.

[0048] S5. Draw the transformer liquid level - Raman signal intensity curve according to the liquid level and the corrected Raman signal intensity;

[0049] S6. Add deionized water to the gas relay 3, measure the liquid level and gas height in the gas relay 3, and draw a volume-height curve inside the gas relay;

[0050] S7. After the Raman fiber optic sensor detects the Raman signal intensity, it obtains the corresponding liquid level according to the transformer liquid level-Raman signal intensity curve, and uses the obtained liquid level to obtain the corresponding gas volume inside the gas relay according to the gas relay internal volume-height curve.

[0051] In one embodiment of the present invention, in step S1 , the contact surface between the Raman optical fiber sensor and the gas relay 3 is sealed using oil-resistant rubber.

[0052] In one embodiment of the present invention, as shown in the attached Figure 1 As shown, the optical fiber probe 2 of the Raman optical fiber sensor is evenly distributed with a number of holes along the circumferential direction from top to bottom, and the diameter of the holes is 4nm. The optical fiber sensor includes two parts: the optical fiber probe 2 and the optical fiber signal transmission line 1. Among them, the optical fiber signal transmission line 1 is made of high-purity, low-loss hollow-core silica optical fiber to ensure the stable transmission and measurement accuracy of the optical signal. The optical fiber probe 2 also uses high-purity, low-loss hollow-core silica optical fiber, but it punches holes on the surface of the optical fiber part inside the gas relay 3 or uses a porous optical fiber with a pore diameter of 4nm (see Figure 1 ), which can prevent transformer oil molecules from passing through but allow hydrogen, methane, ethane, propane, ethylene, acetylene, carbon monoxide, carbon dioxide and other gas molecules to pass through, and is also conducive to the transformer oil fully entering the hollow part inside the optical fiber, keeping the transformer oil level inside the optical fiber consistent with the external oil level.

[0053] Hollow-core optical fiber has a cavity enhancement effect on Raman signals, so as the transformer oil level in the hollow-core optical fiber changes, its Raman signal will also change accordingly. Therefore, in one embodiment of the present invention, at 25°C, a Raman optical fiber sensor is inserted into the gas relay 3 at different liquid level heights, and the difference between every two adjacent liquid level heights is 1 mm.

[0054] In one embodiment of the present invention, step S2 comprises the following steps:

[0055] S21. Insert the Raman fiber sensor into the gas relay 3 to measure m different liquid levels of transformer oil at 1435cm -1 The Raman signal intensity at the kth measurement point is X k , k∈{1,...,m}.

[0056] S22. Insert 10 insertion points between the kth measurement point and the k+1th measurement point, and use the formula X ki =X k +i*(X k+1 -X k ) / 10The liquid level at the i-th insertion point, i∈{1,2...,10}.

[0057] S23. The signal strength detected by the Raman fiber optic sensor at the kth measurement point is Q k , the signal strength detected by the Raman fiber optic sensor at the k+1th measurement point is Q k+1 , insert 10 insertion points between the kth measurement point and the k+1th measurement point, and use the formula

[0058] Q ki =Q k +i*(Q k+1 -Q k ) / 10-(Q k+2 -(Q k +(Q k+1 -Q k ) / (X k+1 -X k )*(X k+2 -X k )))

[0059] / (Q k+2 -Q k )*(10.5-i+RAND()) / 10*(Q k+1 -Q k )

[0060] The signal strength Q of the i-th insertion point ki , i∈{1,2...,10}, RAND() is a random number between 0 and 1.

[0061] In one embodiment of the present invention, in step S3, the formula

[0062] W t =((Q5-Q 5t ) / Q5+(Q 10 -Q 10t ) / Q 10 +(Q 15 -Q 15t ) / Q 15 +(Q 20 -Q 20t ) / Q 20 ) / 4 to calculate the temperature correction coefficient W at temperature t t , t∈{0℃,...,40℃}, where Q5 is the signal intensity detected by the Raman fiber sensor when the liquid level is 5cm at 25℃, Q 10 is the signal intensity detected by the Raman fiber optic sensor when the liquid level is 10 cm at 25 degrees Celsius, Q 15 is the signal intensity detected by the Raman fiber optic sensor when the liquid level is 15 cm at 25 degrees Celsius, Q 20is the signal intensity detected by the Raman fiber optic sensor when the liquid level is 20 cm at 25 degrees Celsius, Q 5t is the signal strength detected by the Raman fiber optic sensor when the liquid level is 5 cm at temperature t, Q 10t is the signal strength detected by the Raman fiber optic sensor when the liquid level is 10 cm at temperature t, Q 15t is the signal strength detected by the Raman fiber optic sensor when the liquid level is 15 cm at temperature t, Q 20t The signal intensity detected by the Raman fiber optic sensor when the liquid level is 20 cm at temperature t.

[0063] In one embodiment of the present invention, step S5 comprises the following steps:

[0064] S51. Through the formula Q k ′=W t *Q k Calculate the signal strength Q of the kth measurement point detected after correction at temperature t k ′.

[0065] S52. Through formula Q ki ′=W t *Q ki Calculate the signal intensity Q of the ith insertion point after correction at temperature t ki ′.

[0066] S53. The liquid level heights at the m measuring points and the liquid level heights at all insertion points are used as the horizontal axis coordinates, and the signal strengths detected at the m measuring points and the signal strengths at all insertion points are used as the vertical axis coordinates to obtain the following. Figure 4 As shown, the transformer liquid level-Raman signal intensity curve.

[0067] In one embodiment of the present invention, step S6 includes the following steps:

[0068] S61. After removing the upper cover of the gas relay, stagger the position to ensure that the float action mechanism is still inside the gas relay housing, and weigh the total weight of the gas relay. Specifically, add deionized water to the gas relay 3 in sequence with Pml as the single measurement, and use a laser rangefinder to measure the liquid level H after the i-th water addition. i , i∈{1,...,n}, n is the number of times deionized water is added.

[0069] S62. Through the formula The gas volume inside the gas relay 3 after the i-th water addition is calculated, where V is the total volume inside the gas relay 3 .

[0070] S63. With n liquid level heights as the horizontal coordinates and n gas volumes inside the gas relay 3 as the vertical coordinates, plot as shown in the attached figure. Figure 5 The internal volume-height curve of a gas relay is shown.

[0071] In this embodiment, the value of P is 5.

[0072] In one embodiment of the present invention, it is also included in step S7 to determine whether the gas volume inside the gas relay 3 exceeds the light gas alarm value, the alarm value is 250mL, and if it exceeds, an alarm signal is issued. If it does not exceed, it can prompt the operation and inspection personnel that there is a false alarm of the light gas alarm.

[0073] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for monitoring gas volume in a gas relay, characterized in that: include: S1. The Raman fiber sensor is inserted from top to bottom into the gas relay of the transformer. The Raman fiber sensor is vertically arranged with its bottom located at the lower end of the lower float of the gas relay. A temperature sensor is installed at the fiber probe of the Raman fiber sensor. S2. Insert the Raman fiber sensor into the gas relay to measure m different liquid levels of transformer oil at 1435cm -1 The Raman signal intensity at S3. Calculate the temperature correction coefficient W t ; S4. Using the temperature correction factor W t Correction of Raman signal intensity; S5. Draw the transformer liquid level - Raman signal intensity curve according to the liquid level and the corrected Raman signal intensity; S6. Add deionized water to the gas relay, measure the liquid level and gas height in the gas relay, and draw a volume-height curve inside the gas relay; S7. After the Raman fiber optic sensor detects the Raman signal intensity, it obtains the corresponding liquid level according to the transformer liquid level-Raman signal intensity curve, and uses the obtained liquid level to obtain the corresponding gas volume inside the gas relay according to the gas relay internal volume-height curve.

2. The method for monitoring gas volume in a gas relay according to claim 1, characterized in that: In step S1, the contact surface between the Raman optical fiber sensor and the gas relay is sealed using oil-resistant rubber.

3. The method for monitoring gas volume in a gas relay according to claim 1, characterized in that: The optical fiber probe of the Raman optical fiber sensor is evenly distributed with a plurality of holes along the circumferential direction from top to bottom, and the diameter of the holes is 4 nm.

4. The method for monitoring gas volume in a gas relay according to claim 1, characterized in that: At 25°C, the Raman fiber optic sensor was inserted into the gas relay at different liquid level heights, and the difference between every two adjacent liquid level heights was 1 mm.

5. The method for monitoring gas volume in a gas relay according to claim 1, characterized in that: Step S2 includes the following steps: S21. Insert the Raman fiber sensor into the gas relay to measure m different liquid levels of transformer oil at 1435cm -1 The Raman signal intensity at the kth measurement point is X k , k∈{1,...,m}; S22. Insert 10 insertion points between the kth measurement point and the k+1th measurement point, and use the formula X ki =X k +i*(X k+1 -X k ) / 10The liquid level at the i-th insertion point, i∈{1,2...,10}; S23. The signal strength detected by the Raman fiber optic sensor at the kth measurement point is Q k , the signal strength detected by the Raman fiber optic sensor at the k+1th measurement point is Q k+1 , insert 10 insertion points between the kth measurement point and the k+1th measurement point, and use the formula Q ki =Q k +i*(Q k+1 -Q k ) / 10-(Q k+2 -(Q k +(Q k+1 -Q k ) / (X k+1 -X k )*(X k+2 -X k ))) / (Q k+2 -Q k )*(10.5-i+RAND()) / 10*(Q k+1 -Q k ) The signal strength Q of the i-th insertion point ki , i∈{1,2...,10}, RAND() is a random number between 0 and 1.

6. The method for monitoring gas volume in a gas relay according to claim 1, characterized in that: In step S3, the formula W t =((Q5-Q 5t ) / Q5+(Q 10 -Q 10t ) / Q 10 +(Q 15 -Q 15t ) / Q 15 +(Q 20 -Q 20t ) / Q 20 ) / 4 to calculate the temperature correction coefficient W at temperature t t , t∈{0℃,...,40℃}, where Q5 is the signal intensity detected by the Raman fiber sensor when the liquid level is 5cm at 25℃, Q 10 is the signal intensity detected by the Raman fiber optic sensor when the liquid level is 10 cm at 25 degrees Celsius, Q 15 is the signal intensity detected by the Raman fiber optic sensor when the liquid level is 15 cm at 25 degrees Celsius, Q 20 is the signal intensity detected by the Raman fiber optic sensor when the liquid level is 20 cm at 25 degrees Celsius, Q 5t is the signal strength detected by the Raman fiber optic sensor when the liquid level is 5 cm at temperature t, Q 10t is the signal strength detected by the Raman fiber optic sensor when the liquid level is 10 cm at temperature t, Q 15t is the signal strength detected by the Raman fiber optic sensor when the liquid level is 15 cm at temperature t, Q 20t The signal intensity detected by the Raman fiber optic sensor when the liquid level is 20 cm at temperature t.

7. The method for monitoring gas volume in a gas relay according to claim 5, characterized in that: step S5 includes the following steps: S51. Through the formula Q k ′=W t *Q k Calculate the signal strength Q of the kth measurement point detected after correction at temperature t k ′; S52. Through formula Q ki ′=W t *Q ki Calculate the signal intensity Q of the ith insertion point after correction at temperature t ki ′; S53. Using the liquid level heights at m measuring points and the liquid level heights at all insertion points as the horizontal axis coordinates, and using the signal strengths detected at the m measuring points and the signal strengths at all insertion points as the vertical axis coordinates, a transformer liquid level height-Raman signal strength curve is obtained.

8. The method for monitoring gas volume in a gas relay according to claim 1, characterized in that: Step S6 includes the following steps: S61. Add deionized water to the gas relay in sequence with Pml as the single measurement, and use the laser rangefinder to measure the liquid level H after the i-th water addition. i , i∈{1,...,n}, n is the number of times deionized water is added; S62. Through the formula Calculate the gas volume inside the gas relay after the i-th water addition, where V is the total volume inside the gas relay; S63. Draw a gas relay internal volume-height curve with n liquid level heights as the horizontal coordinate and n gas volumes inside the gas relays as the vertical coordinate.

9. The method for monitoring gas volume in a gas relay according to claim 8, characterized in that: The value of P is 5.

10. The method for monitoring gas volume in a gas relay according to claim 1, characterized in that: The process also includes obtaining the gas volume inside the gas relay in step S7 and determining whether it exceeds a light gas alarm value, wherein the alarm value is 250 mL. If the value exceeds the light gas alarm value, an alarm signal is issued.

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