Gas relay heavy gas action identification method based on pressure difference and heavy gas signal

Abstract

The invention discloses a gas relay heavy gas action recognition method based on pressure difference and heavy gas signals. The method comprises the following steps that a gas relay transient mechanical response test bed is built; the influence of oil flow fluctuation on the front pressure intensity and the rear pressure intensity of the gas relay is monitored every delta t, and meanwhile the corresponding data pressure difference value delta P is recorded; heavy gas action signals of the double-floating-ball gas relay are monitored every delta t, and corresponding data potential values S are recorded at the same time; judging the size relation between the collected pressure difference value delta P and a set threshold pressure difference delta PS and the potential value of the heavy gas action signal S; the working state of the gas relay is output according to the judgment result; the output working state of the gas relay is monitored and recorded in real time; if the output result is the heavy gas refusal action, re-judgment needs to be carried out at the next delta t, and if delta P is larger than or equal to delta PS and S is equal to 0, the output signal is the heavy gas refusal action; otherwise, entering step 4; according to the invention, a malfunction tripping accident caused by abnormal vibration of the transformer is solved.

Description

Technical Field

[0001] The invention relates to the technical field of oil-immersed transformer gas relay protection, in particular to a gas relay heavy gas action identification method based on pressure difference and heavy gas signal. Background Art

[0002] Buchholz relays are key components in transformer protection, used to monitor internal faults and initiate power outages. Industry regulations require that oil-immersed power transformers of 66 kV and above be equipped with Buchholz relays and heavy-duty gas trip contacts. These relays react quickly to oil flow and gas surges caused by severe faults, triggering protection. However, the operating characteristics of conventional relays fail to fully account for the impact of operating conditions and fault modes, potentially leading to inaccurate protection action and reducing transformer protection reliability.

[0003] Double-float gas relays are widely used in existing technology. Their dual-float structure allows for more accurate detection of oil surges and gas accumulation. Their operating principle is as follows: A fault within the transformer tank can cause gas to precipitate and the insulating oil to decompose. The gas rises and accumulates on the top of the gas relay, causing the oil level to drop and the upper float to activate. When the gas volume reaches a preset value, a minor gas alarm is issued. A serious fault, such as overheating or a short circuit, can cause large amounts of gas to form, forcing the oil to flow into the oil pillow. This impacts the gas relay's baffle, causing it to flip, triggering the major gas contacts and generating a trip signal.

[0004] Currently, malfunctions and failures of heavy gas protection devices are common. In recent years, hundreds of such incidents have occurred in my country due to faults outside the transformer gas protection zone, abnormal vibration of the transformer housing, and short circuits in gas relays. For double-float gas relays, significant vibration acceleration can cause the baffle to overcome its magnetic force and separate from the frame, resulting in a loss of magnetic force and abnormal operation of the gas relay. Under low flow rates or other disturbances, the baffle's rotation triggers the reed switch, leading to a false heavy gas alarm. To prevent these vibration-induced false heavy gas alarms and improve the vibration resistance of the gas relay's heavy gas operation, this study investigated the pressure differential characteristics across the gas relay when transient oil flow impacts the baffle (a significant oil pressure differential exists), as well as the pressure differential characteristics across the gas relay under vibration (a very small oil pressure differential exists due to the low oil flow and vibration). A gas relay heavy gas operation identification method based on pressure differential and heavy gas signals was proposed. Summary of the Invention

[0005] In order to solve the existing technical problems, the present invention proposes a method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal, which can effectively identify abnormal heavy gas action, solve the false operation and tripping accidents caused by abnormal vibration of the transformer, improve the accuracy and reliability of the gas relay, and ensure the stable operation of the gas monitoring system.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal comprises the following steps:

[0008] Step 1: Build a gas relay transient mechanical response test bench to simulate the action signal of the double-float gas relay under transformer failure conditions;

[0009] Step 2: When the transformer is in a fault state, monitor the impact of oil flow fluctuations on the pressure before and after the gas relay every Δt, and simultaneously record the corresponding data pressure difference value ΔP;

[0010] Step 3: When the transformer is in a fault state, monitor the heavy gas action signal of the double-float gas relay every Δt and simultaneously record the corresponding data potential value S;

[0011] Step 4: Determine whether the collected pressure difference ΔP is equal to the set threshold pressure difference ΔP. S The size relationship, as well as the potential value of the heavy gas action signal S;

[0012] Step 5: Outputting the working status of the gas relay according to the judgment result;

[0013] Step 6: Monitor and record the working status of the output gas relay in real time. If the output result is a serious gas misoperation, it is necessary to make another judgment in the next Δt. If ΔP<ΔP S And when S=1, the output signal is heavy gas misoperation; otherwise, go to step 4;

[0014] Step 7: If the output result is a heavy gas rejection action, it is necessary to make another judgment in the next Δt. If ΔP≧ΔP S And when S=0, the output signal is heavy gas rejection action; otherwise, go to step 4.

[0015] Preferably, the working process of the gas relay transient mechanical response test bench in step 1 includes: instantaneous release of high-pressure gas inside the air cannon, the generated pressure wave pushes the pipeline oil flow to impact the gas relay baffle, causing the gas relay to operate heavily.

[0016] Preferably, the constructed gas relay transient mechanical response test bench includes 7 major parts: an air cannon, a pulsating flow generating chamber, a pipeline to be tested, a gas relay, a bellows, a butterfly valve, and a capsule oil pillow.

[0017] Preferably, an air cannon is used as the external excitation source of the test platform to simulate internal faults of the transformer; a pulsating flow generating chamber provides space for the expansion of compressed air to generate pulsating oil flow; a test sensor is installed on the pipeline to be tested; a gas relay detects the gas signal under the impact of the pulsating flow and simulates the action during a fault; a bellows is used for pipeline connection, deviation correction and vibration suppression; a butterfly valve controls the on-off of the pipeline to simulate changes in pipe diameter; and a capsule-type oil pillow is used for oil storage and replenishment.

[0018] Preferably, in step 2, when measuring the pressure difference before and after the gas relay during the test, two PCM300 pressure transmitters are used, with a measurement range of 0-0.4 MPa, a resolution of 0.001 MPa, and a diaphragm made of 316s stainless steel.

[0019] Preferably, the pressure difference before and after the gas relay and the heavy gas signal of the gas relay are collected and analyzed by a dynamic signal data acquisition instrument.

[0020] Preferably, in step 4, the threshold pressure difference ΔP is set S It is the maximum pressure difference before and after the gas relay baffle is actuated.

[0021] Preferably, the time interval Δt refers to the duration from the start of the action to the end of the action of the Buchholz relay baffle.

[0022] Preferably, the working state of the gas relay is output according to the judgment result in step 5: when the pressure difference before and after the gas relay is greater than or equal to the set threshold and the heavy gas signal is high, that is, ΔP≧ΔP S And S=1, it is confirmed that it is a heavy gas action; when the pressure difference before and after the gas relay is less than the threshold but the heavy gas signal is still high, that is, ΔP<ΔP S If S=1, it is determined that the heavy gas malfunction has occurred and the heavy gas action will not be executed; when the pressure difference before and after the gas relay is greater than or equal to the threshold and the heavy gas signal is low, that is, ΔP≧ΔP S And if S=0, it is judged as a heavy gas rejection action.

[0023] Compared with the existing technology, the advantages presented by the present invention are:

[0024] The method of the present invention can effectively identify abnormal heavy gas operation, solve the false operation and tripping accidents caused by abnormal vibration of the transformer, and thus improve the accuracy and reliability of the gas relay; the method significantly improves the fault identification ability and stability of the gas relay system, reduces the risk of misoperation due to excessive vibration, enhances the reliability of the gas relay in the protection of power equipment, and ensures the stable operation of the gas monitoring system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A model diagram of a gas relay transient mechanical response test bench provided by the present invention;

[0026] Figure 2 Design diagram of the heavy gas signal response experimental platform for the double-float gas relay provided by the present invention;

[0027] Figure 3 The present invention provides a double-float gas relay heavy gas signal synchronous acquisition flow chart;

[0028] Figure 4 A diagram showing the geometrical model of the gas relay structure provided by the present invention;

[0029] Figure 5 The present invention is a flow chart of a method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0031] Example 1: Figure 1 As shown in the figure, a gas relay transient mechanical response test bench is built to simulate the action signal of the double-float gas relay under transformer fault conditions. The main principle is: the instantaneous release of high-pressure gas inside the air cannon generates a pressure wave that pushes the oil flow in the pipeline to impact the gas relay baffle, causing the gas relay to operate heavily.

[0032] like Figure 2 As shown in the figure, the gas relay transient mechanical response test bench includes 7 parts: air cannon, pulsating flow generating chamber, pipeline to be tested, gas relay, bellows, butterfly valve, and capsule oil pillow.

[0033] The air cannon serves as the external excitation source of the test platform to simulate internal faults of the transformer; the pulsating flow generating chamber provides space for the expansion of compressed air, generating pulsating oil flow; test sensors, such as pressure sensors, are installed on the pipeline to be tested; the gas relay detects the gas signal under the impact of the pulsating flow, simulating the action during a fault; the bellows are used for pipeline connection, deviation correction and vibration suppression; the butterfly valve controls the on-off of the pipeline, simulating changes in pipe diameter; and the capsule oil pillow is used for oil storage and replenishment.

[0034] like Figure 3 As shown, this embodiment discloses a method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal, and the specific steps are as follows:

[0035] Two PCM300 pressure transmitters with a measurement range of 0-0.4 MPa and a resolution of 0.001 MPa, made of 316S stainless steel diaphragms, were selected to measure the pressure differential across the gas relay during the test. The gas relay transmitted a heavy gas actuation signal via a heavy gas line. A dynamic signal data acquisition instrument collected the 0-5 V voltage signals of the gas relay's pressure signals and the heavy gas signal.

[0036] like Figure 5 As shown, the method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal of this embodiment has the following specific steps:

[0037] Step 1: Start simulating the action signal of the double-float gas relay under the condition of transformer failure;

[0038] Step 2: When the transformer is in a fault state, monitor the impact of oil flow fluctuations on the pressure before and after the gas relay every Δt, and simultaneously record the corresponding data pressure difference value ΔP;

[0039] Step 3: When the transformer is in a fault state, monitor the heavy gas action signal of the double-float gas relay every Δt and simultaneously record the corresponding data potential value S;

[0040] Step 4: Determine whether the collected pressure difference ΔP is equal to the set threshold pressure difference ΔP. S The size relationship, as well as the potential value of the heavy gas action signal S;

[0041] Step 5: Output the working status of the gas relay according to the judgment result; when the pressure difference before and after the gas relay is greater than or equal to the set threshold and the heavy gas signal is high, that is, ΔP≧ΔP S And S=1, it is confirmed that it is a heavy gas action; when the pressure difference before and after the gas relay is less than the threshold but the heavy gas signal is still high, that is, ΔP<ΔP S If S=1, it is determined that the heavy gas malfunction has occurred and the heavy gas action will not be executed; when the pressure difference before and after the gas relay is greater than or equal to the threshold and the heavy gas signal is low, that is, ΔP≧ΔP S And S=0, it is judged as heavy gas rejection action;

[0042] Step 6: Monitor and record the working status of the output gas relay in real time. If the output result is a serious gas misoperation, it is necessary to make another judgment in the next Δt. If ΔP<ΔP S And when S=1, the output signal is heavy gas misoperation; otherwise, go to step 4;

[0043] Step 7: If the output result is a heavy gas rejection action, it is necessary to make another judgment in the next Δt. If ΔP≧ΔP S And when S=0, the output signal is heavy gas rejection action; otherwise, go to step 4.

[0044] The threshold pressure difference ΔP mentioned in the method of this embodiment is set S It is the maximum pressure difference before and after the baffle of the gas relay is actuated. The time interval Δt refers to the duration from the start to the end of the action of the gas relay baffle.

[0045] The method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal proposed in this embodiment can accurately distinguish between heavy gas action, false action caused by excessive vibration, and refusal to act by real-time monitoring of the front and rear pressure difference and heavy gas signal of the gas relay, thereby significantly improving the fault identification capability and stability of the gas relay system, reducing the risk of misoperation due to excessive vibration, and improving the accuracy and reliability of the gas relay.

[0046] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be the technical solutions set forth in the claims, including equivalent alternatives to the technical features of the technical solutions set forth in the claims. In other words, equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal, characterized by: It includes the following steps: Step 1: Build a gas relay transient mechanical response test bench to simulate the action signal of the double-float gas relay under transformer failure conditions; Step 2: When the transformer is in a fault state, monitor the impact of oil flow fluctuations on the pressure before and after the gas relay every Δt, and simultaneously record the corresponding data pressure difference value ΔP; Step 3: When the transformer is in a fault state, monitor the heavy gas action signal of the double-float gas relay every Δt and simultaneously record the corresponding data potential value S; Step 4: Determine whether the collected pressure difference ΔP is equal to the set threshold pressure difference ΔP S The size relationship, as well as the potential value of the heavy gas action signal S; Step 5: Outputting the working status of the gas relay according to the judgment result; Step 6: Monitor and record the working status of the output gas relay in real time. If the output result is a serious gas misoperation, it is necessary to make another judgment in the next Δt. If ΔP<ΔP S And when S=1, the output signal is heavy gas misoperation; otherwise, go to step 4; Step 7: If the output result is a heavy gas rejection action, it is necessary to make another judgment in the next Δt. If ΔP≧ΔP S And when S=0, the output signal is heavy gas rejection action; otherwise, go to step 4.

2. The method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal according to claim 1, characterized in that: The working process of the gas relay transient mechanical response test bench in step 1 includes: the instantaneous release of high-pressure gas inside the air cannon, the generated pressure wave pushes the pipeline oil flow to impact the gas relay baffle, causing the gas relay to operate heavily.

3. The method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal according to claim 1, characterized in that: The constructed gas relay transient mechanical response test bench includes 7 major parts: air cannon, pulsating flow generating chamber, pipeline to be tested, gas relay, bellows, butterfly valve, and capsule oil pillow.

4. The method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal according to claim 3, characterized in that: An air cannon serves as the test platform's external excitation source, simulating internal transformer faults. A pulsating flow generating chamber provides space for compressed air to expand, generating pulsating oil flow. A test sensor is installed on the pipeline to be tested. A gas relay detects gas signals under the impact of pulsating flow, simulating its action during a fault. Bellows are used for pipeline connection, deviation correction, and vibration suppression. A butterfly valve controls the on / off of the pipeline, simulating changes in pipe diameter. A capsule-type oil pillow is used for oil storage and replenishment.

5. The method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal according to claim 1, characterized in that: In step 2, when measuring the pressure difference before and after the gas relay during the test, two PCM300 pressure transmitters are used, with a measurement range of 0 to 0.4 MPa, a resolution of 0.001 MPa, and a diaphragm made of 316s stainless steel.

6. The method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal according to claim 1, characterized in that: The pressure difference before and after the gas relay and the heavy gas signal of the gas relay are collected and analyzed by a dynamic signal data acquisition instrument.

7. The method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal according to claim 1, characterized in that: In step 4, the threshold pressure difference ΔP is set. S It is the maximum pressure difference before and after the gas relay baffle is actuated.

8. The method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal according to claim 1, characterized in that: The time interval Δt refers to the duration from the start to the end of the action of the Buchholz relay baffle.

9. The method for identifying heavy gas action of a gas relay based on pressure difference and heavy gas signal according to claim 1, characterized in that: The working state of the gas relay is output according to the judgment result in step 5. Specifically, when the pressure difference before and after the gas relay is greater than or equal to the set threshold and the heavy gas signal is high, that is, ΔP≧ΔP S And S=1, it is confirmed that it is a heavy gas action; when the pressure difference before and after the gas relay is less than the threshold but the heavy gas signal is still high, that is, ΔP<ΔP S If S=1, it is determined that the heavy gas malfunction has occurred and the heavy gas action will not be executed; when the pressure difference before and after the gas relay is greater than or equal to the threshold and the heavy gas signal is low, that is, ΔP≧ΔP S And if S=0, it is judged as a heavy gas rejection action.

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