Evolutionary combinatorial optimisation for energy storage scheduling, and web-based power systems analysis using PHP

Agamah, Simon (2016). Evolutionary combinatorial optimisation for energy storage scheduling, and web-based power systems analysis using PHP. (Unpublished Doctoral thesis, City, University of London)

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Two research areas are covered in this thesis: the formulation of a novel evolutionary combinatorial optimisation algorithm for energy storage system (ESS) scheduling, and web-based power systems analysis (WBPSA) using PHP programming. An increase in electricity demand usually calls for reinforcement of the network equipment to handle the new load and network operators sometimes postpone or avoid this reinforcement by using ESS to store electrical energy when network usage is low and release it to be used in the grid during periods of high demand. The ESS operation must be scheduled to be effective and there are several scheduling methods that depend on energy generation data, flexible time-of-use tariffs or closed loop set-points. This thesis proposes a method that uses only historic or forecasted demand data which is also a requirement for other methods. The methodology formulates an electricity demand profile and ESS as a combination of the one-dimensional bin packing problem and the subset sum problem and solves them heuristically with specific modifications and transformations to obtain viable schedules. The schedules may then be optimised further using genetic algorithm optimisation. Comparative analyses with other algorithms and case studies using real-world data are used for verification. The algorithm is shown to be effective and has some advantages when compared to other existing algorithms; hence it can be used in scenarios where other methods are not applicable. On the second topic the thesis explores web-based power systems analysis platforms and shows that most use a web server primarily as an interface for exchanging requests and results between a front-end web browser and specialised back-end computation software written in a general programming language. A web server runs programs written in scripting languages such as PHP, which is the most popular web server programming language. Recent versions of web scripting languages have the computational capabilities required for power systems analysis and can handle the task of modelling networks and analysing them. This provides an opportunity for a slimmer 2-tier framework in which the web server also acts as the computation layer. The requirements for general power systems modelling are discussed and a methodology for realising web-based simulation using PHP programming is developed. Some of the modelling functions are handled natively in PHP and some require the use of extensions. The results show that using PHP for simulations can result in simpler access to power systems analysis functions in websites and web applications. The memory consumed by the PHP library developed is seen to be low and the computation time for reasonably large networks is in the millisecond range.

Item Type: Thesis (Doctoral)
Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Divisions: School of Engineering & Mathematical Sciences
URI: http://openaccess.city.ac.uk/id/eprint/15837

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