The Electrical Power transformer of agricultural power needs to select and configure partial discharge positioning facilities and heating and drying equipment.
In order to reduce the interference of noise and other external factors, the ultrasonic array signal processing model is used to complete the local positioning of the multi-target discharge.
The uniform heating and drying of the transformer by the short-circuit heating method significantly improves the heating efficiency and drying level, and reduces the possibility of damage to the insulating material.
A new part of the dielectric window is added to the partial discharge detection, which improves the detection sensitivity and the accuracy of electromagnetic signal reception.
Analyzed and studied the parameters of each part of the existing transformers on the market.
Mainly aimed at the positioning system of the transformer partial discharge, the heating and drying system, and the partial discharge detection method of the transformer.
The design is more suitable for the construction of agricultural power engineering.
Transformer, and conducted research and analysis on its installation and operation process.
The electrical equipment required in the construction of electric power projects is large in quantity and variety, so the transformer must be able to achieve local and multiple target positioning and the multiple positioning of the power supply is the prerequisite basis for multiple target positioning.
At present, the methods for local multi-target positioning of the power supply generally include electrical positioning, ultrasonic positioning, etc., but these methods are difficult to perform precise positioning at the same time in different time periods or in different areas.
According to the characteristics of agricultural power engineering construction, the basic transformer has been partially transformed. The transformed Electrical Power transformer uses array signal processing technology, which can use multiple ultrasonic sensors to achieve local multi-target discharge positioning in the range space.
Before the Electrical Power transformer performs multi-target positioning of local discharge sources, the number of discharge sources must be determined first.
First, the staff is required to estimate a rough quantity range of the transformer discharge source based on the work equipment and work requirements.
Second, select the transformer of the corresponding performance level, place it in an appropriate position, turn on the ultrasonic sensors in each position in the scene, and collect the signals in the spatial range.
The information returned by the sound wave signal is screened to meet the target requirements for the placement of the power source, and then all the location information is integrated and fed back so that the staff can obtain accurate information about the amount of the power source.
The determination of the position of the discharge source is similar to the steps of determining the quantity, except that the array sensor needs to be activated when the ultrasonic sensor is collecting signals from the surrounding environment.
The operating program model of the array sensor composing the signal into a planar array is as follows: X(t)=A(z,φ)S(t)+N(t) (1) In the formula (z,φ) represents the direction of signal emission angle, S (T) represents the incident signal vector, X(t) represents the received signal vector, and N(t) is the sensor interference factor vector.
Based on the operating program model, the array sensor can form a planar array of the collected ultrasonic signals, and transmit the array information to the internal processing system of the transformer. The transformer selects an appropriate number of target positioning points for the optimal discharge source according to the distribution of the received signal array.
The Electrical Power transformer multi-target discharge source is a passive and passive positioning mode, which cannot actively obtain relevant data like radar system equipment. The designed Electrical Power transformer introduces a data processing system.
Multiple sensors transmit signals to each other to obtain the intersection of the intersecting signal measurement line.
According to the repeated intersection, the false target point is eliminated, and the source position of the true target point of the data signal is determined, and the relevant data measurement of the positioning target can be carried out autonomously.
Generally, there are many power lines in large-scale transformers, and the external insulation materials are easily affected by moisture, which can cause changes in current, voltage, and resistivity, which have great safety hazards, and even serious personal safety accidents.
Therefore, the moisture-proof and moisture-proof of the Electrical Power transformer during installation are very important.
At present, the heating and drying process of large-scale transformers in our country generally adopts the traditional oil filter hot oil circulation method, which uses hot oil to heat the transformer in a cycle.
This method is more restricted by the performance of the oil filter and the external ambient temperature conditions, and the drying effect is generally not very satisfactory.
A suitable heating and drying device has been developed for agricultural development and transformation of Electrical Power transformers. The device adopts a short-circuit heating method to generate heat inside the insulator so that the heating is more uniform and the temperature control is more flexible.
The research results show that the heating efficiency of this method is higher, the damage to the equipment itself is also less, and the treatment effect of heating and drying is more ideal.
The operating principle of the short-circuit method is to apply alternating current from the two sections of the transformer’s high-voltage winding and low-voltage winding at the same time. The higher voltage current makes the internal load of the transformer higher and generates heat, and the heat generated by the circuit loss is used to heat the insulating part.
This method does not require additional heating materials, the heat is generated inside the transformer itself, the temperature is easier to adjust, and the operation process is simpler.
This short-circuit method requires higher voltage and current during heating and requires higher power supply capacity. Therefore, this short-circuit method heating device is more suitable for large-scale transformers.
It is also very suitable for UHV transformers. Its heating and drying ability can be changed according to the performance of the transformer. The applicability is very strong and the use effect is also very good.
However, when using the short-circuit method for heating, the following issues need to be paid attention to:
In addition to the basic Electrical Power transformer, additional equipment such as voltage regulators, intermediate transformers, and compensation power supplies are all relatively large in size and weight, which greatly hinders the transportation and handling process of the heating device.
Therefore, in the next study of the short-circuit heating device, we should focus on how to simplify the heating device, reduce its volume, enhance its convenience, and realize the movable operation of the heating device.
Detection For the partial discharge detection of large transformers, the UHF detection method is commonly used, which has higher sensitivity and strong anti-interference ability.
UHF devices are generally equipped with built-in or external sensors to receive and detect partial discharge electromagnetic waves. The built-in sensors are flexible and have strong receiving capabilities, but they are difficult to maintain and repair.
The external sensor is less interfered by the magnetic field, which is convenient for adjustment and maintenance, but the detection sensitivity is poor, so there are many difficulties in the operation of the UHF detection device.
A dielectric window attached to the variable pressure tank is designed. When the UHF electromagnetic wave performs partial discharge, the electromagnetic signal transmitted and received passes through the dielectric window, which further improves the detection sensitivity and accuracy.
Select and adjust the size of the medium window according to the size of the agricultural transformation transformer. Choose a UHF sensor device with a basic capacity of 240 MVA and a rated voltage of 220/110/35 kV. After the internal seal, install the sensor on the outside of the Electrical Power transformer tank. Install 4 on both sides of the low voltage to form a combined sensor array to realize real-time monitoring of the local multi-directional discharge of the transformer.
When performing partial discharge, adjust the frequency of the debugging power supply to 180 Hz, and adjust the test voltage to 1.1 times and 1.5 times of the rated voltage, respectively, and turn on the Electrical Power transformer and sensor for testing.
At this time, the sensing information obtained by UHF partial discharge is 1.6 V and 1.8 V, and the electromagnetic wave frequency distribution is uniformly undulating, and the fluctuation is denser when it is interfered by noise, but the impact is not very large, indicating that the noise interference on the UHF sensor signal acquisition The impact is small.
The partial discharge positioning of Electrical Power transformers used in agricultural development is also done by UHF sensors.
Make the 4 sensors on the low-voltage winding side of the Electrical Power transformer detect local electromagnetic signals, and the sensors on the high-voltage side receive and read the signal information, and realize the positioning of the discharge source coordinates after the data processing program is calculated. The calculation model of the data processing program is as shown in formula (2) Show: (x-xi)2+(y-yi)2+(z-zi)2=v 2T2
In the formula: (x, y, z) is the coordinate positioning of the target of the discharge source, (xi, yi, zi) is the coordinate of the sensor, v is the speed at which the electromagnetic wave radiation reaches the sensor, and T is the UHF electromagnetic wave The time it takes to reach the sensor.
Under 1.5 times the voltage, the sensor receives about 50 sets of UHF electromagnetic signals, and performs hyperboloid equation calculations based on the variance of the received time difference and each set of peak values to obtain specific signal positioning, which can realize the coordinates of the local multi-target discharge source position.
When implementing agricultural power transformation projects in power engineering construction, transformers need to be studied.
Starting with the selection and installation of transformers, according to the specific characteristics of agricultural power, the selection methods and installation methods of transformers are analyzed, and the device selection and installation proposed greatly improve the working efficiency of transformers. At the same time, safety and stability are enhanced, which has certain reference significance for the construction of agricultural power.
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