Power Electronics and Drive Systems (MMH623585) TriA 2021-2022 Coursework 1- PART1 Matlab/Simulink simulation case studies- Power Electronics Theme   This brief provides details of PART1 ONLY of CW1 which consists of TWO mandatory parts: PART1- Power Electronics Theme (50 marks) PART2- Drive Systems Theme (50 marks)   This is an individual-based assessment where you must submit a report with maximum word limit 1300 words

Power Electronics and Drive Systems (MMH623585) TriA 2021-2022

Coursework 1- PART1

Matlab/Simulink simulation case studies- Power Electronics Theme

This brief provides details of PART1 ONLY of CW1 which consists of TWO mandatory parts:

• PART1- Power Electronics Theme (50 marks)
• PART2- Drive Systems Theme (50 marks)

This is an individual-based assessment where you must submit a report with maximum word limit 1300 words. Concise presentation is encouraged.

Weighting and pass mark:

This part of CW1 contributes 50 marks, out of 100 marks allocated for CW1. 

Timelines:

Issued to students: Week 4 on Wed 20/10/2021

Hand in: Week 7 on Wednesday 10/11/2021 by 23.59 hrs (UK time) (electronic submission via Turnitin)

Further instructions:

1. No extensions will be given other than for very exceptional circumstances and only if requested and agreed in advance from the Module Leader.
2. Word limit: 1300 words 
3. Use the CW cover sheet provided separately as the main cover sheet on your submission and include all your details on it.

ATTEMPT ALL QUESTIONS

Question 1:                                                                                                                                       [30 marks]

Load the following Simulink-ready example by typing power_hvdc in the MATLAB command window then pressing Enter. 

The model shows a HVDC Transmission system using AC/DC 6-pulse thyristor-based rectifier as shown in Figure 1.

Figure 1: 6-pulse HVDC Transmission System

You are a Power Electronics Engineer working at this substation and you are part of a team tasked with upgrading the system design to a 12-pulse rectifier to improve the substation performance.

You are required to produce a full design specification for this upgrade, given that all system current and voltage rated values are to remain unchanged. When you are performing this design upgrade, you should consider upgrading:

• Rectifier connection and control                                                                              
• Transformer design/connection                                                                                 
• AC line filter                                                                                               

Your answer should include:

• New Simulink model with detailed diagrams of any sub-blocks or sub-systems.                    [5]
• Detailed account of design calculations, mathematical analysis and verbal reasoning behind all choices.                     [10]
• Results comparing 6-pulse and 12-pulse systems to validate your design. Results should include time-domain waveforms from scopes, rectifier gate pulses and FFT analysis of AC side line currents before and after AC line filter. Discuss the comparative system performance highlighting advantages of each of the two designs.          [15] Question 2:                                                                                                                [20 marks]

Load the following Simulink-ready example by typing power_2and3LevelVSC in the MATLAB command window then pressing Enter. 

The model shows Two-Level and Three-Level Inverters as shown in Figure 2.

Figure 2: Two-Level and Three-Level Inverters

1. Considering the 2-level inverter only, compare between SPWM and THI modulation techniques by plotting a chart of inverter line-line voltage RMS voltage vs modulation index (including sufficient over-modulation). Discuss your results comparing between both techniques, and support your discussion with appropriate analysis.                                      [10]

Hint: It is recommended to untick the “internal generation of reference signals” inside the PWM generator block and make the generation of SPWM and THI reference signals using external signals that you generate.

2. Considering both 2-level and 3-level inverters, and using SPWM only, compare between both inverters’ performance by plotting a chart of load line-line voltage THD vs modulation index (including sufficient over-modulation). Discuss your results comparing between both inverters, and support your discussion with appropriate analysis.                                         [10] Hint: You will need to use FFT analysis tool under powergui block to obtain Total Harmonic Distortion (THD).