Application Cases

Experimental Name: Experimental Validation of Scaled Transformer Models and Field Testing of Ultra-High Voltage Converter Transformers

Research Direction:
Ultrasonic detection and localization technology for partial discharge (PD) in power transformers, focusing on the inversion of multi-path propagation characteristics of ultrasonic waves within the complex internal structure of transformers and the application of digital twin modeling.

Experimental Objectives:

1. Validate the accuracy of the ray-tracing model: Verify the effectiveness of the proposed three-dimensional multi-path tracing simulation method through scaled model experiments and field tests on actual converter transformers.

2. Analyze multi-path propagation characteristics: Investigate the refraction, reflection, diffraction, and scattering mechanisms of ultrasonic waves inside transformers to clarify their impact on the reliability of PD detection.

3. Optimize sensor placement: Provide a theoretical basis for ultrasonic localization of PD in transformers and improve detection accuracy.

Testing Equipment:

1. Scaled Transformer Model Experiment
   (1) Ultrasonic simulation emission system: Composed of a signal generator, high-voltage amplifier, and ultrasonic transducer. Experimental block diagram (see Figure 1).
   (2) Receiving equipment: Magnetic ultrasonic sensors and oscilloscope.
   (3) Model structure: Single-phase three-column scaled model (1.6 m × 1.2 m × 0.9 m), including windings, core, clamps, etc.

   
   

Figure 1: Experimental Platform for Ultrasonic Propagation Characteristics in Transformers

Figure 2: Sensor Placement Positions

2. Ultra-High Voltage Converter Transformer Test
   (1) Sensor placement: Two ultrasonic sensors installed on the top surface (see Figure 2).
   (2) PD detection system: Used to capture discharge waveforms.

Experimental Procedure:

Scaled Transformer Model Experiment

1. Model Setup: Construct a single-phase three-column scaled transformer model (1.6 m × 1.2 m × 0.9 m) including windings, core, clamps, and other structures.

2. Acoustic Source and Sensor Placement:
   (1) Acoustic source placed externally or internally to the windings.
   (2) Sensors positioned at the center of the front and rear surfaces of the oil tank.

3. Ray Emission and Tracing: Use fixed interval or golden spiral methods to emit rays (2,592 rays) and iteratively trace their propagation paths (step size: 30 mm). Record the number of rays reaching the sensors and their propagation times.

4. Data Acquisition and Analysis: Receive ultrasonic signals via sensors, classify propagation times using the K-means clustering algorithm, and compare simulated and measured waveform arrival times.

Ultra-High Voltage Converter Transformer Test

1. Sensor Placement: Install two ultrasonic sensors on the top surface at coordinates (3580, 308, 4200) mm and (2722, 1820, 4200) mm.

2. PD Signal Detection: When the grid-side voltage is increased to 0.4Um/√3, PD ultrasonic signals are detected, and sensor waveforms are recorded (see Figure 3).

3. Model Inversion: Based on the PD source coordinates (6650, 220, 3800) mm, use the golden spiral method to emit 2,000 rays, trace propagation paths, and calculate arrival times.

4. Result Validation: Compare simulated arrival times with measured data and analyze sources of error.

   
   

Figure 3: PD Waveforms Captured by Sensors

Experimental Results:

1. Scaled Model

• Multi-path phenomenon: Ray clusters align with measured pulse arrival times (e.g., front sensor: 207 μs, 384 μs, 1047 μs).

• Error analysis: Relative error between simulated and measured arrival times ≤ 6.57%, validating model accuracy.

2. Converter Transformer

• Path inversion: Successfully identified longitudinal waves, transverse waves, and reflection paths (see Figure 4), though some pulse paths were not fully inverted.

• Error sources: Differences between empirical wave velocities and actual medium parameters.

  
  

Figure 4: Ray Tracing Results for the Converter Transformer Model

Product Recommendation: ATA-7000 Series High-Voltage Amplifier

Figure: ATA-7000 Series High-Voltage Amplifier Specifications and Parameters

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