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Power quality performance analysis for Nonlinear Loads

Power quality performance analysis for Nonlinear Loads

In this blog, we will perform a power quality performance analysis for non-linear loads using MATLAB. This experiment involves creating a symbolic diagram, building a Simulink model, and analyzing the total harmonic distortion (THD) of the source current

Step 1: Create a Folder

  1. Open MATLAB and create a new folder in a convenient location (e.g., Documents/MATLAB).

  2. Copy the folder location.

Step 2: Change MATLAB Directory

  1. Change the MATLAB directory by pasting the copied location.

  2. This ensures that MATLAB looks for and saves files in the correct folder.

Step 3: Open Simulink and Create a Model

  1. Open Simulink and create a new blank model.

  2. Save the model with an appropriate name (e.g., "PowerQualityNonLinearLoads").

Step 4: Build the Simulink Model

  1. In the Simulink Library Browser, navigate to Simscape > Power Systems > Specialized Technology > Fundamental Blocks.

  2. Add a Three-Phase Voltage Source block, Current Measurement block, Voltage Measurement block, and Universal Bridge block to the model.

Step 5: Add Non-Linear Load

  1. Add a diode and series RLC branch to represent the non-linear load.

  2. Connect the diode to the current source and connect the load.

Step 6: Measure Voltage and Current

  1. Add a Scope block to measure the voltage and current.

  2. Connect the Voltage Measurement block to measure source voltage and the Current Measurement block to measure source current.

Step 7: Add Simscape Power GUI Block

  1. To execute the power system block, add a Simscape > Specialized Technology > Fundamental Blocks > Simscape Power GUI block.

Step 8: Simulate the Model

  1. Simulate the model for a specified duration (e.g., 0.4 seconds).

Step 9: Analyze Total Harmonic Distortion (THD)

  1. Open the Simscape Power GUI block to visualize results.

  2. Measure THD using FFT analysis:

  • Go to Continuous > Simscape > Tools > FFT Analysis.

  • Configure properties, unlock data to workspace, and set format to structure with time.

  • Measure THD for both voltage and current.

Step 10: Interpret Results

  1. Check THD values for voltage and current.

  2. THD for voltage should be less than 5% (as per IEEE standards).

  3. If the THD for current is high, it indicates poor power quality due to harmonic distortion.


By following these steps, you have successfully performed a power quality performance analysis for non-linear loads using MATLAB. This experiment helps in understanding the impact of non-linear loads on source current quality and allows for effective power system analysis.

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