Method and system for monitoring breathing resistance of transformer breathing system

Abstract

The invention provides a transformer respiratory system respiratory resistance monitoring method. The transformer respiratory system respiratory resistance monitoring method comprises the following steps: step (1), calculating the average oil temperature of a transformer; (2) calculating the volume of breathing gas of the transformer; (3) calculating the breathing gas flow of the transformer; (4) calculating the gas flow rate of the transformer; step (5), gas flow and flow velocity error calculation; and (6) evaluating smooth breathing of the respiratory system. The invention provides a transformer respiratory system respiratory resistance monitoring method and system. The health state of a transformer respiratory system can be diagnosed according to the gas respiratory capacity and respiratory rate of a transformer.

Description

Technical Field

[0001] The present invention belongs to the technical field of substation equipment condition monitoring, and particularly relates to a method and system for monitoring the breathing resistance of a transformer respiratory system. Background Art

[0002] At present, large transformers in China are mainly oil-filled transformers. The volume of transformer oil changes under different temperature conditions and is connected to the outside through an oil conservator. On the one hand, the oil conservator bears the thermal expansion and contraction of the transformer oil, and on the other hand, it is also the channel for the internal pressure of the transformer to contact the external environment. The normal breathing of the gas inside the oil conservator is extremely important for the operation of the transformer. When the breathing is unobstructed, it will cause the gas on the oil surface of the transformer to be unable to be discharged in time, resulting in an increase in the internal pressure of the transformer body. In the lightest case, it will cause oil leakage, and in the most serious case, it will cause the pressure relief valve to act or the heavy gas to act and trip, which is crucial for the stable operation of the power system.

[0003] Therefore, it is necessary to determine a method and system for monitoring the breathing resistance of a transformer respiratory system to realize the real-time monitoring of the health status of the transformer respiratory system. Summary of the Invention

[0004] To solve the above problems, the present invention provides a method and system for monitoring the breathing resistance of a transformer respiratory system, which can diagnose the health status of the transformer respiratory system according to the gas breathing volume and breathing rate of the transformer.

[0005] Specifically, the present invention is a method for monitoring the breathing resistance of a transformer respiratory system, and the method for monitoring the breathing resistance of the transformer respiratory system includes the following steps:

[0006] Step (1): Calculating the average oil temperature of the transformer;

[0007] Step (2): Calculating the breathing gas volume of the transformer;

[0008] Step (3): Calculating the breathing gas flow rate of the transformer;

[0009] Step (4): Calculating the gas flow velocity of the transformer;

[0010] Step (5): Calculating the errors of the gas flow rate and flow velocity;

[0011] Step (6): Evaluating the breathing smoothness of the respiratory system.

[0012] Further, the method for calculating the average oil temperature of the transformer in step (1) is:

[0013] Method 1: The average oil temperature T = ((T D -T0 - T C ) / 1.2) + T0, where T is the average oil temperature, T D is the top oil temperature, T C: Temperature rise correction value, T0: Ambient temperature, T C Take 5K;

[0014] Method 2: Arrange temperature sensors vertically and equidistantly on the surface of the transformer tank. Here, it is calculated with N sensors (the number of sensors should not be less than 6). The calculation method of the average temperature of the tank The top oil temperature is T1, and the temperature at the highest point of the tank is T2. Calculate the temperature loss of the tank wall ΔT = T1 - T2, and calculate the average oil temperature of the transformer

[0015] Furthermore, the calculation method of the volume of the breathing gas of the transformer in step (2) is as follows:

[0016] The total oil quantity m of the equipment is provided by the transformer manufacturer. Calculate the total volume of the transformer oil at 20°C. According to the thermal expansion coefficient of the transformer oil of 0.07%, the total volume of the transformer oil at 20°C is V = m / 0.895, and the volume change is:

[0017] ΔV = 0.0007 * ΔT1 * V

[0018] In the formula, ΔT1 is the temperature difference between time t1 and time t2, and the calculation formula is ΔT1 = T1 - T2, where T1 is the average oil temperature at time t1 and T2 is the average oil temperature at time t2. The average oil temperature is recommended to use Method 2, and when conditions do not permit, Method 1 is adopted.

[0019] Furthermore, the calculation method of the breathing gas flow rate of the transformer in step (3) is as follows:

[0020] The diameter of the breathing pipeline of the transformer is d, and the gas flow velocity at time t is v c (monitored in real time by a flow velocity meter), calculate the net gas flow between time t1 and time t2:

[0021] Furthermore, the calculation method of the gas flow velocity of the transformer in step (4) is as follows:

[0022]

[0023] Furthermore, the calculation method of the gas flow rate and flow velocity error in step (5) is as follows:

[0024] δ1 = (ΔV - ΔV1) / ΔV1

[0025] δ2 = (ν - ν c ) / ν c .

[0026] Furthermore, the evaluation method of the smooth breathing of the respiratory system in step (6) is as follows:

[0027] Evaluation method:

[0028] Unobstructed breathing: δ1 < 0.1 and δ2 < 0.1;

[0029] Obstructed breathing: δ1 > 0.5 and δ2 > 0.5;

[0030] Respiratory system blockage (obstructed breathing): Others.

[0031] Furthermore, the present invention also proposes a monitoring system for the breathing resistance of a transformer respiratory system. The monitoring system for the breathing resistance of the transformer respiratory system includes a temperature acquisition system, an oil conservator, a gas pipe, a gas flow rate sensor, and a breather.

[0032] Compared with the prior art, the beneficial effects are as follows:

[0033] Currently, there is no effective means for monitoring the breathing resistance of a transformer respiratory system in the market. Some maintenance-free breathers have a function of monitoring air pressure, but no evaluation method for pressure changes is proposed, and this pressure monitoring is absolute pressure, without detecting the rate of change of air pressure, and without monitoring according to the actual situation of the change of the transformer oil level. Strictly speaking, it cannot realize the online diagnosis of the transformer respiratory system. The monitoring method and system of the present invention comprehensively consider the absolute value of air pressure and the rate of change of air pressure, and combine the actual operating conditions of the transformer, and give a specific evaluation method for the respiratory system, which can realize the online monitoring and evaluation of the state of the transformer respiratory system. Description of the Drawings

[0034] Figure 1 is the working flow chart of a monitoring method for the breathing resistance of a transformer respiratory system according to the present invention;

[0035] Figure 2 is a schematic diagram of the layout of transformer temperature sensors;

[0036] Figure 3 is a flow monitoring system for a transformer respiratory system.

[0037] Where 1 - transformer oil surface temperature sensor, 2 - transformer box surface temperature sensor, 3 - transformer box, 4 - gas pipe, 5 - gas flow rate sensor, 6 - breather, 7 - transformer oil conservator Detailed Embodiments

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates in detail a monitoring method and system for the breathing resistance of a transformer respiratory system according to the present invention with reference to the accompanying drawings and implementation cases. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not used to limit the invention.

[0039] As Figure 1 shown, the monitoring method for the breathing resistance of the transformer respiratory system of the present invention includes the following steps:

[0040] Step (1): Calculation of the average oil temperature of the transformer

[0041] Step (2): Calculation of the volume of the breathing gas of the transformer

[0042] Step (3): Calculation of the flow rate of the breathing gas of the transformer

[0043] Step (4): Calculation of the gas flow velocity of the transformer

[0044] Step (5): Calculation of the errors of the gas flow rate and flow velocity

[0045] Step (6): Evaluation of the smooth breathing of the respiratory system

[0046] The method for calculating the average oil temperature of the transformer in step (1) is as follows:

[0047] Method 1: The average oil temperature T = ((T D - T0 - T C ) / 1.2) + T0, where T is the average oil temperature, T D is the top oil temperature, T C is the temperature rise correction value, and T0 is the ambient temperature. Take T C as 5K;

[0048] Method 2: Arrange temperature sensors vertically and equidistantly on the surface of the transformer box. Here, it is calculated with N sensors (the number of sensors should be no less than 6). The method for calculating the average temperature of the box The top oil temperature is T1, and the temperature at the highest point of the box is T2. Calculate the temperature loss of the box wall ΔT = T1 - T2, and calculate the average oil temperature of the transformer oil

[0049] The method for calculating the volume of the breathing gas of the transformer in step (2) is as follows:

[0050] The total oil quantity m of the equipment is provided by the transformer manufacturer. Calculate the total volume of the transformer oil at 20°C. According to the thermal expansion coefficient of the transformer oil of 0.07%, the total volume of the transformer oil at 20°C is V = m / 0.895, and the volume change is:

[0051] ΔV = 0.0007 * ΔT1 * V

[0052] In the formula, ΔT1 is the temperature difference between the t1 moment and the t2 moment, and the calculation formula is ΔT1 = T1 - T2. T1 is the average oil temperature at the t1 moment, and T2 is the average oil temperature at the t2 moment. It is recommended to use Method 2 for the average oil temperature. When the conditions do not allow, Method 1 is adopted.

[0053] The method for calculating the flow rate of the breathing gas of the transformer in step (3) is as follows:

[0054] The diameter of the breathing pipeline of the transformer is d, and the gas flow velocity at the t moment is vc (Monitored in real time by a current meter), calculation of the net gas flow between time t1 and t2:

[0055] The calculation method of the gas flow rate of the transformer in step (4) is as follows:

[0056]

[0057] The calculation method of the gas flow rate and flow rate error in step (5) is as follows:

[0058] δ1 = (ΔV - ΔV1) / ΔV1

[0059] δ2 = (ν - ν c ) / ν c .

[0060] The evaluation method of the respiratory system patency in step (6) is as follows:

[0061] Evaluation method:

[0062] Respiratory patency: δ1 < 0.1 and δ2 < 0.1;

[0063] Respiratory obstruction: δ1 > 0.5 and δ2 > 0.5;

[0064] Respiratory system blockage (respiratory obstruction): Others.

[0065] A respiratory resistance monitoring system for a transformer respiratory system according to the present invention has a system composition as Figure 2 、 Figure 3 shown,

[0066] The temperature acquisition system includes Figure 2 the transformer oil surface temperature sensor 1 and the temperature sensors 2 arranged vertically and equidistantly on the surface of the transformer box body 3 in Figure 2 . Among them, the transformer oil surface temperature sensor 1 collects the top oil temperature of the transformer, and the temperature sensors 2 arranged vertically and equidistantly on the surface of the box body collect the temperature of the surface of the transformer box body 3. The average oil temperature and the oil temperature change rate of the transformer are calculated through the temperatures collected by the temperature sensors.

[0067] Figure 3 includes an oil conservator 7, a gas pipe 4, a gas flow rate sensor 5, and a breather 6 in Figure 2 . When the internal temperature of the transformer changes, the transformer oil expands or contracts, and external gas enters and exits the oil conservator 7 through the breather 6 and the gas pipe 4. The total volume of the gas entering and exiting the oil conservator 7 and the gas inlet and outlet rate at a certain moment are monitored by the gas flow rate sensor 5 installed in the breather. The background machine calculates and analyzes in real time according to the temperature, gas flow rate, and flow rate, and gives the evaluation result of the transformer respiratory system.

[0068] Finally, it should be noted that the technical solutions of the present invention are only illustrated in combination with the above embodiments and are not limited thereby. Those of ordinary skill in the art should understand that those skilled in the art can modify the specific embodiments of the present invention or make equivalent replacements, but such modifications or changes are all within the scope of protection of the claims pending for approval.

Claims

1. A method for monitoring the breathing resistance of a transformer respiratory system, characterized in that, The transformer breathing system breathing resistance monitoring method comprises the following steps: Step (1): Calculation of average oil temperature of transformer; Step (2): Calculation of transformer breathing gas volume; Step (3): calculation of transformer breathing gas flow rate; Step (4): Calculation of transformer gas flow rate; Step (5): Calculation of gas flow rate and flow velocity error; Step (6): Evaluation of respiratory system patency.

2. The respiratory resistance monitoring method of a transformer respiratory system according to claim 1, characterized in that The calculation method for the average oil temperature of the transformer in step (1) is: Method 1: The average oil temperature T = ((T D - T0 - T C ) / 1.2) + T0, where T is the average oil temperature, T D is the top-layer oil temperature, T C is the temperature rise correction value, and T0 is the ambient temperature. Take T C as 5K; Method 2: Arrange temperature sensors vertically and equidistantly on the surface of the transformer tank. Here, N sensors are used for calculation, and the calculation method for the average temperature of the tank The top oil temperature is T1, and the temperature at the highest point of the tank is T2. Calculate the temperature loss of the tank wall ΔT = T1 - T2, and calculate the average oil temperature of the transformer 3. A method for monitoring the breathing resistance of a transformer respiratory system according to claim 2, characterized in that, The calculation method for transformer breathing gas volume in step (2) is: The transformer manufacturer provides the total oil volume m of the equipment, and calculates the total volume of the transformer oil at 20°C. According to the thermal expansion coefficient of the transformer oil of 0.07%, the total volume of the transformer oil at 20°C is V = m / 0.895, and the volume change is: ΔV=0.0007*ΔT1*V Where ΔT1 is the temperature difference between time t1 and time t2, and the calculation formula is ΔT1=T1-T2. T1 is the average oil temperature at time t1, and T2 is the average oil temperature at time t2. Method 2 is recommended for the average oil temperature. When conditions do not permit, use method 1.

4. A method for monitoring the breathing resistance of a transformer breathing system according to claim 3, characterized in that, The calculation method of transformer breathing gas flow in step (3) is: The diameter of the breathing pipeline of the transformer is d, and the gas flow velocity at time t is v c , Calculation of the net gas flow between time t1 and t2:

5. A method for monitoring the breathing resistance of a transformer respiratory system according to claim 4, characterized in that, The calculation method of transformer gas flow rate in step (4) is:

6. A method for monitoring the breathing resistance of a transformer breathing system according to claim 5, characterized in that, The calculation method of gas flow rate and flow velocity error in step (5) is: δ1=(ΔV-ΔV1) / ΔV1 δ2 = (ν - ν c ) / ν c .

7. A method for monitoring the breathing resistance of a transformer respiratory system according to claim 6, characterized in that, The method for evaluating the smooth breathing of the respiratory system in step (6) is: Evaluation method: Breathing is smooth: δ1<0.1 and δ2<0.1; Shortness of breath: δ1>0.5 and δ2>0.5; Respiratory system obstruction (difficulty breathing): Other.

8. A breathing resistance monitoring system for a transformer breathing system monitors the breathing resistance of the transformer breathing system by using the method for monitoring the breathing resistance of a transformer breathing system according to any one of claims 1-7, characterized in that, The transformer breathing system breathing resistance monitoring system comprises a temperature acquisition system, an oil storage cabinet, an air duct, a gas flow rate sensor, and a respirator.

9. The respiratory resistance monitoring system for a transformer respiratory system according to claim 8, wherein, The temperature acquisition system includes a transformer oil surface temperature sensor and temperature sensors arranged vertically and equidistantly on the surface of the transformer box, wherein the transformer oil surface temperature sensor collects the top oil temperature of the transformer, and the temperature sensors arranged vertically and equidistantly on the surface of the box collect the temperature of the surface of the transformer box. The average oil temperature of the transformer and the oil temperature change rate are calculated based on the temperature collected by the temperature sensors.

10. The respiratory resistance monitoring system for a transformer respiratory system according to claim 8, characterized in that, When the internal temperature of the transformer changes, the transformer oil expands or contracts, and the external gas enters and exits the oil conservator through the respirator and the air duct. The gas flow rate sensor installed in the respirator is used to monitor the total volume of gas entering and exiting the oil conservator and the gas inlet and outlet rate at a certain moment. The background computer uses the temperature and gas flow rate and flow rate to calculate and analyze in real time according to the monitoring method, and gives the evaluation results of the transformer breathing system.

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