Control Analysis with Python for Grid Connected Converters

Course Overview

In this course, you will learn how to use Python to represent a converter connected to a grid as a closed-loop transfer function. Using Python packages, controllers can be designed and the behavior of the final closed-loop system can be analyzed for steady-state performance and stability. Analytical results will be verified using simulations performed using Python. This course is primarily for power electronics engineers who have been struggling to implement controllers for their converter systems as most of the controls courses do not have any specific relevance to power electronics. This course is a controls course created by a power electronics engineer for other power electronics engineers. All software used in the course is free and open-source and therefore students do not need to purchase any software licenses after enrolling in the course. The course will describe in-depth the Python functions and packages that can be used for control systems design and analysis.

To make this course useful for students of every background, including working professionals, the mathematical content in the course has been kept to a bare minimum and the focus is on providing solutions that can be used in projects. The course will describe theory using simple examples as far as possible in order to make the theory behind all analyses easily understandable.

What you'll learn

Basic grid computations such as frequency estimation
Basic control theory
Introduction to python-control package
Transfer function representation for a system
Closed-loop systems, feedback paths and controllers
Using Bode plots to interpret system transfer functions
Stability analysis through Bode plots
Reference frame transformation
Controller design through Bode plots
Simulation of controlled systems using Python
Basics of single-phase converters
Switching control strategies for single phase converters
Controller design for a grid connected converter

Projects Involved in this Course

Design and analysis of proportional, integral, and proportional-integral controllers for single-phase grid-connected converter in the stationary reference frame

Project 1
Stability analysis techniques for closed-loop systems

Project 2
Design and analysis of proportional-integral controller for single-phase grid-connected converter in the synchronous reference frame

Project 3

Course Notes

Course name	Control analysis with Python for grid connected converters
Start & end date	Open for enrolment anytime
Mode of delivery	Online, recorded video lessons & self-paced
Software used	Python, Numpy, Scipy, Matplotlib, Python-control & Python Power Electronics
Course pre-requisites	Basic electrical engineering network laws, Laplace transform and frequency response of systems, simulating power electronic circuits with control loops in Python Power Electronics, basic Python, Numpy and Matplotlib
Applicable for	Students, Faculties, or Industry professionals from the background of Electrical & Electronics engineering.
Certification by & Host details	Decibels Lab Pvt Ltd (Recognised as Start-up by Department for Promotion of Industry and Internal Trade Ministry of Commerce & Industry Government of India) (Certificate Number: DIPP45372)
Course duration	33 hours
Course access duration	90 days
Doubt clarification	It's 100% practical & self-paced, provided with a step-by-step guide to achieve the learning. To address any of the queries in person, we have a Discussion feature, where you can directly interact with the course author.

Course Curriculum

1. Overview of the course
2. Course requirements
3. How to use this course
4. How to use Discussions option
5. Course access duration
6. Piracy & infringement warning
1. Introduction
2. An overview of power system grids
3. Grid voltage waveforms
4. Downloading Python Power Electronics
5. Videos on installing Python Power Electronics
6. Installing Python Power Electronics
7. Simulating a single phase voltage source
8. Modeling the grid feeder
9. Calculating the feeder impedance
10. Simulating a grid with a feeder
11. Conclusions
1. Introduction
2. Peak and RMS calculation concept
3. Implementation of peak calculation
4. Peak calculation during grid events
5. Implementation of RMS calculation
6. RMS calculation on non-sinusoidal waveform
7. The need for frequency estimation
8. Simulation of a system with multiple frequencies
9. Introduction to Phase Locked Loop
10. Coding the simplified PLL logic
11. Performance of the basic PLL
12. Frequency response characteristics of the PLL PI controller
13. Improved performance of the PLL
14. Offsets during numerical integration
15. Simulating the integration offset
16. Removal of the integration offset
17. Design of a Low Pass Filter
18. Coding the low pass filter
19. Performance of the low pass filter in a simulation
20. Operation of the PLL with the low pass filter
21. PLL operation when grid frequency changes
22. PLL operation when grid voltage has harmonics
23. Summing up the PLL control loop
24. Conclusions
1. Introduction
2. Control basics
3. Control definitions
4. Control objectives in grid connected systems
5. System representation of a grid connected converter
6. Model of the plant
7. Linear time invariant systems
8. LTI systems and controllability
9. Conclusions
1. Introduction
2. Laplace transform and frequency domain representation
3. Basics of stability
4. Characteristic equation of a system
5. Examples of stability
6. Installing the python-control package
7. Creating transfer functions in Python
8. The transfer function object produced by python-control
9. Transfer functions in series
10. Transfer functions in parallel
11. Calculating the transfer function of the closed loop system
12. Synthesizing a non-standard transfer function
13. Impulse response of a system
14. Convolution integral
15. Bode plots
16. Generating Bode plots using Python
17. Using Bode plots to predict simulation results
18. Analyzing the simulation results with Bode plots
19. Summing up with Bode plots
20. Conclusions
1. Introduction
2. Approach to control
3. Setting up the simulation
4. Converter as a controllable voltage source
5. Open loop regulation of converter voltage
6. Closing the loop with a unity gain controller
7. Analyzing the performance of the unity gain controller
8. Bringing in the proportional (P) controller
9. Requirements of a controller
10. Analyzing the forward transfer function with the proportional controller
11. Discrete-time control
12. Mathematical model of sampling
13. Modified transfer functions with sampling delay
14. Bode plots with sampling delay
15. Simulating the discrete-time controller
16. Coding the transfer function between grid voltage and current
17. Analyzing the impact of the grid voltage
18. Effect of proportional controller gains on control performance
19. Verifying analytical results in a simulation
20. Poles of the closed loop system
21. Gain margin and phase margin
22. Stability margins on a Bode plot
23. Analytical design process for the proportional controller
24. Design and analysis of a Proportional-Integral controller
25. Simulation of the PI controller
26. Summing up the control design effort
27. Conclusions
1. Introduction
2. Definition of a moving reference frame
3. Example of the use of a moving reference frame
4. Rotating reference frame in electrical engineering
5. Theory of synchronously rotating reference frame transformation
6. Setting up a simulation to implement transformations
7. Transformed grid voltages
8. Explaining the errors in the simulation
9. Transformation with a non synchronous rotating reference frame
10. Another look at the PLL control strategy
11. System model in the rotating reference frame
12. Control approach in the rotating reference frame
13. Impact of the rotating reference frame on system transfer functions
14. Coding the rotating frame transfer functions in Python
15. Computing closed loop system poles
16. Plotting closed loop poles for arrays of controller gains
17. Dividing the plot into separate Python objects
18. Defining user events on the plot window
19. Interpreting data related to a mouse moving over the plot
20. Mapping controller gains to a particular pole on the plot
21. Displaying controller gains on the plot next to a pole
22. Using the plot to understand how controller gains affect system stability
23. Analyzing system stability
24. Setting up simulation for verifying control analysis
25. Transforming ac variables to the rotating reference frame in the simulation
26. Implementing the PI controller in the rotating reference frame
27. Connecting the PI controller to the circuit voltage source
28. Analyzing controller variables
29. Debugging the controller
30. Basic current tracking performance of the controller
31. Improving the performance of the controller
32. Suggestions for examining performance of the control system
33. Conclusions
1. H-bridge converter topology
2. Connecting a LC filter and load to converter output
3. Editing the parameters of the converter and test circuit
4. Generating the carrier waveform for Pulse Width Modulation (PWM)
5. Sine triangle comparison in PWM
6. Open loop operation of the H bridge converter
7. Redesigning control gains for converter interconnection to grid
8. Setting up the simulation with converter and grid
9. Analyzing simulation of grid connected converter
10. Examining oscillations in the waveforms
11. Adjusting the filter of the power converter
12. Concluding remarks and suggestions
1. Conclusions
1. Instructions to generate your certificate
2. Leverage your certificate to get Internship or Job

About this course

₹2,999.00
145 lessons
33 hours of video content

Shivkumar Iyer

Instructor profile

I did my Master's and PhD in power electronics after which I spent several years working for both big companies like ABB and GE as well as a number of start-ups. I specialized in the field of power converter control and smart grids and have published prolifically in high impact international journals and conferences besides also being the author of two books. I started programming at the age of 14 and over the past 20 years have programmed in several languages - C, C++, Python, JavaScript. I started taking a keen interest in open source software after I became a Linux user when I was a graduate student. My expertise in electrical engineering and programming therefore resulted in me creating open source software for electrical engineers. I use open source software for teaching electrical engineering to students and practicing engineers with the typical theme of my courses being the application of programming to solve engineering problems.