Tuesday 25 January 2011

Programming

Last week I took 'time out' from my PhD to code a BAE Logistics simulator. I made some quick skeleton code with basic functionality to show BAE so that they could come up with a proper set of requirements. I will finish the coding in the coming weeks but will only be working on it part time.

Since the coding I have been working on my PhD again. I am currently testing some CPLEX code I have written. It works out the generator output that minimises the carbon emissions of the generators, subject to thermal limits of the power lines. The plan is to code in some sort of ordering on the generators such that generators that have been connected to the power grid the longest are curtailed last. I am also looking at refining my mathematical model of the problem, however I am having difficulties with specifying an ordering on a set in mathematical form. I have taken a few abstract set theory books out of the library, so hopefully they will help

Friday 14 January 2011

Need to get back into the habit of blogging!

I have been familiarising myself with a few techniques that are used in the paper "The use of constraint programming for the autonomous management of power flows":

  • back tracking search - Search the tree by starting at the root and traversing in a depth first manner. At a particular node C, checks whether a valid solution can be computed from C, if not whole subtree is pruned. Obviously the hard part using a good approximation function that can calculate whether a valid solution exists.
  • best first - explores the tree by expanding the most promising node chose according to a specific rule. A* search is an example.
I have implemented the DC power flow equations in matlab, they use considerably less code then the java implementation. Hopefully this matlab implementation will be used by CPLEX, a constraint optimisation solver, so that it can calculate the flow, however I am still working on expressing the problem in CPLEX language. 

In parallel to this I have been describing the model and the problem in mathematical terms, I have written a one page mathematical explanation of the constraints, the network and the variables defining their domains and bounds. This in theory will allow me to then translate it into any coding environment in order to implement it.

A selection of papers that I have read:

1. Dam KH van, Houwing M, Lukszo Z, Bouwmans I. Agent-based control of distributed electricity generation with micro combined heat and power: cross-sectoral learning for process and infrastructure engineers. Computers & Chemical Engineering. 2008;32(1-2):205-217. 

2. Taylor P, Xu T, McArthur S, et al., others. Integrating voltage control and power flow management in AuRA-NMS. In: SmartGrids for Distribution, 2008. IET-CIRED. CIRED Seminar.; 2008:1-4.

3. Pipattanasomporn M, Feroze H, Rahman S. Multi-agent systems in a distributed smart grid: Design and implementation. In: Power Systems Conference and Exposition (PSCE 2009).; 2009:1-8. 

4. Dolan MJ, Davidson EM, Ault GW, McDonald JR. Techniques for managing power flows in active distribution networks within thermal constraints. In: Electricity Distribution-Part 1, 2009. CIRED 2009. 20th International Conference and Exhibition on.; 2009:1-4.

I have implemented the same network as the one in the paper "The use of constraint programming for the autonomous management of power flows". However it does not specify any of the loads, and therefore I will not be able to recreate the exact experiments without them.

Next week I am putting the PhD on a one week hold to code full time on a project for BAE systems.

Tuesday 4 January 2011

Back in Southampton

Back in Southampton now here is a summery of what I have been doing:
I have been focusing my attention on achieving a good understanding of how the electricity system works by reading a variety of books including 

1. Galvin R, Yeager K, Stuller J. Perfect power: how the microgrid revolution will unleash cleaner, greener, and more abundant energy. 1st ed. McGraw-Hill Professional; 2008.

2. Weedy BM, Cory BJ. Electric Power Systems. 4th ed. John Wiley & Sons; 2004.

3. Gonen T. Electric power distribution system engineering. 2nd ed. McGraw-Hill New York; 2007.

4. Chard FDLC. Electricity Supply: Transmission and Distribution. 1st ed. Longman Group Limited; 1976.

I have also been studying the paper:

1. Davidson EM, Dolan MJ, McArthur SDJ, Ault GW. The use of constraint programming for the autonomous management of power flows. In: 15th International Conference on Intelligent System Applications to Power Systems (ISAP 2009).; 2009:1-7.

with the intention of first recreating the results found in the paper and then applying a decentralised way to calculate power flow analysis. By the end of January the goal is to have a mathematical model of the various constraints and equations used and a set of experiments and results written up in a small two column style paper.