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EEEE4122 - MATLAB & SIMULINK Test (2022/23)

(Electrical and Electronic Engineering Fundamentals for MSc students - Autumn)

IMPORTANT NOTES

· This piece of coursework is worth 20% of the final module marks.

· You are provided with an excel sheet entitled “ExcelSHEETforQUESTION3.xlsx” and an answer template (YourID&Name_EEEE4122_Matlab&Simulink_ANSWERSheet) in word.

· You must submit your work using the answer template provided and into the submission link entitled “SUBMISSION LINK FOR SOFTWARE TEST: MATLAB and Simulink”.

· Ensure that you put your name and student ID on the filename.

· Deadline for submission: No later than 3PM (UK time) Wednesday, 23rd November 2022. NO late submission will be accepted without an approved EC and that the University standard penalty of 5 marks per day after the stated deadline will apply.

· Details of what is an EC (Extenuating Circumstance) can be found in this link: https://www.nottingham.ac.uk/studentservices/services/extenuating-circumstances.aspx  

· NOTE: This is an individual assignment. Submitted work will be compared with other students' work to detect collusion or plagiarism. If identified, students will be subjected to an academic misconduct hearing.

Question 1

A typical steel reheating furnace requires temperature measurements via the use of thermocouples, which tend to have long leads before these signals are fed into a PID controller in order to regulate the supply of gas to an array of burners.

1-a) Name two sources that can potentially contribute to the presence of unwanted high frequency noise in the thermocouple’s electrical signal?

[3 Marks]

1-b) Briefly describe the operating principles of a “low-pass” R-C filter in attenuating low amplitude high frequency signals and allowing the stronger low frequency component to pass through.

[6 Marks]

1-c) In normal operating conditions, controlled furnace temperatures tend to fluctuate in the order of 1 cycle over 10 to 15 minutes. What would be a suitable cut-off frequency in this case and explain your choice. The figure below shows the Bode plots of a 1^st order low-pass filter.           [3 Marks]

Figure for Q 1-c: Bode Plots (Gain and Phase) for a 1^st Order RC Circuit. 

1-d) Using Simulink (i) create the following circuit using the appropriate blocks or elements from Simscape. Take the R-value to be 10MΩ and by assuming an appropriate cut-off frequency that is consistent to Question 1-c, calculate the required value of the capacitor to provide the required noise attenuation. (ii) Run a simulation for the tabled input sinusoidal signals and determine the maximum amplitude of the filtered output.

[(i) 12 Marks]

Figure for Question 1-d: R-C Circuit

Table for Question 1-d

[(ii) 4 Marks]

1-e) Consider a furnace with a production rate of 127 Metric Tonnes/ hour where steel bars enter at 20°C and leave at 1100 °C, with an energy profile described by the Sankey diagram shown in Fig 1-e below. What is the annual cost saving potential if the enhanced plant instrumentation and control can yield up to 5% reduction in fuel consumption, assuming continuous operation over a full year? Take that the UK cost for wholesale gas to be £39.50p/GJ and the specific heat capacity at constant pressure (C) of mild steel at the stated discharge temperature to be 667 J/kg K.

[6 Marks]

Figure for Q 1-e: Sankey Diagram for a Typical Modern Steel Reheating Furnace

Source: Y.K. Hua, C.K. Tan et al., “Development of a first-principles hybrid model for large-scale reheating furnaces”, Applied Energy, 173 (2016) 555–566. Used with permission

Total for Question 1 = 34 Marks

Question 2

2-a) Briefly describe (i) the basic working principles of a Dc-Dc boost converter circuit and subsequently (ii) derive an expression for the duty cycle of the MOSFET by considering the change in the current across the inductor during the ON and OFF configurations in terms of the V_in and V_out of the said circuit.

[(i) 3 + (ii) 3 = 6 Marks]

Figure for Q 2-a: Basic Topology of a DC-DC Boost Converter Circuit

Source: Principles of the Dc-Dc Boost Converter Operation - https://learnabout-electronics.org/PSU/psu32.php - Retrieved 1st Oct 2020

2-b) The power versus voltage potential plot at a constant solar irradiance of 1000 W/m² at 3 temperatures for a typical photovoltaic solar panel is shown in the figure Q 2-b below. For a typical ambient air temperature at midday in the month of July for the area of your choice (for example where you are living now or where you grew up), (i) estimate the panel’s voltage at maximum power. You may linearly interpolate or extrapolate between the said temperatures.

[(i) 2 Marks]

Figure for Q 2-b: Typical Power versus Voltage Plot of a PV Solar Panel for 3 Cell Temperatures (deg C).

(ii) With the V_in and corresponding maximum power for a single module shown in Figure for Q 2-b above, design and model a Dc-Dc boost converter in Simulink to meet the following requirements:

Target output voltage, V_out of 120V. Acceptable input current ripple of between 30 to 40% and output voltage ripple of between 1 to 3%. Take the switching frequency for the MOSFET to be 50kHz. You need to state the magnitude of your chosen current and voltage ripples from the given ranges, and any assumption in your component sizing (inductor, capacitor, and resistor) calculation. Provide a screen shot of your final circuit.

[Design (10) + Model (10) = 20 Marks]

In addition, provide: (iii) the plot of inductor current (A) versus time (mS) to clearly show the lower and upper limits of it’s linear variation and (iv) a plot of V_out (V) versus time (s).

[(iii) 3 + (iv) 2 = 5 Marks]

Total for Question 2 = 33 Marks

Question 3

The data used in this question originated from the work of McLoughlin et al. of the Technological University Dublin on their paper entitled “Analysing Domestic Electricity Smart Metering Data Using Self Organising Map” which was presented in the CIRED Workshop, Lisbon, Portugal in 2012.

3-a) Explain the working principles of how a Self-Organising-Map (SOM) learns to identify potential patterns in the input matrix.

[9 Marks]

3-b) Import the data contained in “ExcelSHEETforQUESTION3.xlsx” into the Matlab workspace using the XLSREAD function or the “Import Data” GUI and clearly explain your steps. The data set relates to 9 examples, each with 4 attributes or features. Provide the screen shot of your syntaxes/ steps taken and the imported data in your answer template.

[8 Marks]

3-c) Normalise the imported data between 0 and 1. Provide a screen shot of your steps in the Matlab workspace and the normalised matrix in your answer template.

[8 Marks]

3-d) Based on the normalised input data, build a 1-dimensional Self Organising Map (SOM) with 6 output neurons. Calculate the output of the trained network and comment on the results (for example the similarity between the sample groups).

[8 Marks]

Total for Question 3 = 33 Marks