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Summer 2012 Blog - Katherine He

Katherine He is spending eight weeks at the Indian Institute of Technology, Kharagpur.

August 2, 2012

I’ve spent the last four weeks writing, rewriting, and debugging my Matlab program. This was my first experience using Matlab, so simple tasks like combining (concatenating) matrices were initially puzzlingly complex to me. The code writing process included multiple iterations of increasingly complex code. Over the past month, I have progressed from a remedial Matlab blunderer to a reasonably competent Matlab user.

My first task was to calculate the instantaneous power of distributed generation machines using Matlab. I translated equations that I learned in ER 100, Energy and Society, into Matlab code. Energy and Society is an undergraduate/graduate course that uses interdisciplinary knowledge to investigate the technical, economic, and social opportunities and impacts of worldwide energy systems. Here are some examples of my work, theoretically and translated into code:

Instantaneous power of a photovoltaic array:

power = η* A * Ee
η = array electrical efficiency
A = array area (m2)
E= insolation (W/m2)

arraylength = 0.155;
arraywidth = 0.128;
arrayefficiency = 0.18;

insolation = 170;
arrayarea = arraylength*arraywidth;
pvpower = arrayarea * arrayefficiency * insolation / 1000;

Instantaneous power of a photovoltaic array:

power = 0.5 * ρ * A * V3 * Cp
ρ = air density (kg/m3)
A = swept area (m2)
V = wind speed (m/s)
C= coefficient of power
windpower = 0.5 * airdensity * sweptarea * (windspeed.^3) * powerfactor /  1000;

I then integrated these calculations into a larger program I wrote that includes temporally varying values for insolation, wind speed, and load. This program calculates the total renewable power generated per hour, compares it to the hourly load, and calculates how much nonrenewable energy and grid energy would be required to satisfy the load. The program then aggregates renewable energy, nonrenewable energy, and grid energy used over the given time period. In terms of priority, the modeled Microgrid preferentially consumes renewable energy over nonrenewable energy and prioritizes nonrenewable energy over grid energy. The nonrenewable energy sources (e.g. steam turbines, natural gas boilers, fuel cells) are also ranked by a priority system that is determined by the user.

The last step in writing my code was to calculate the manufacturing and operating emissions and cost. Manufacturing costs/emissions are based on the installed capacity of all machines (i.e. max power of wind turbines, photovoltaic arrays, gas turbines, etc.).  Operating costs/emissions are based on the energy produced in a given time period.

As my time in the lab nears its end, I’ve realized that there are many capabilities that I will not have time to incorporate into my program. These include the addition of batteries for intermittent power storage and a graphic user interface for individuals who are not familiar with Matlab. Mindful of these future additions, I have made my code as well documented and simple as possible to facilitate incorporation of these elements.

Having finished writing the program, I am now modeling emissions and costs of static versus varying loads. Next, I will use my program to model emissions of real-world installations of Microgrids. In the next two weeks, I will write a paper that details my methods, provides a user’s manual of my code, and presents a flowchart that explains the inner workings of my program. All of these results will be presented at a symposium of projects from participants of the IIT-UC Berkeley program (including the IIT students that interned at UC Berkeley for the summer). A last, ongoing task is to create a database of emissions factors and cost coefficients of different types of distributed generation sources.


June 29, 2012


Sir Ashutosh Mukherjee Hall

The first week of my internship was occupied by cramming power systems knowledge, creating a powerpoint of my skills and project ideas, and presenting the powerpoint to Binoy and Sir Bajpai (people here refer to those higher in the educational hierarchy as “sir” and “madam” – you’ll hear master’s students using this term to address Ph.D candidates). After the presentation, Sir gave me some directions to explore as possible project ideas (e.g. adding to an energy audit of the IIT Kharagpur campus performed by undergraduate students, researching carbon footprints, doing something related to microgrids).

During my second week, I met with Sir Bajpai again to discuss my project. I reported the results of my academic wanderings, and he suggested a project that fits perfectly with the expertise I have and the skills I would like to develop – I will create a program using Matlab that calculates the carbon footprint of a microgrid installation. This project combined the opportunity to learn Matlab, an extremely useful program, with the opportunity to familiarize myself with microgrids, a research focus that will be integral to designing an environmentally sustainable electricity grid.


The Electrical Engineering Power Systems Lab

Since then, I’ve been conducting literature searches on microgrid technology and the carbon footprint of distributed generation components. I’m using a reference matrix I designed in excel to organize the papers I’ve read and the values calculated in the papers.  And I am starting to conceptually frame my model by outlining what the nature of the inputs and outputs of my program will be.

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