Συμβολή Στο Σχεδιασμό Επέκτασης Και Στην Κατανομή Του Κόστους Συστημάτων Μεταφοράς Ηλεκτρικής Ενέργειας
21/12/2007 - 10/07/2013
The deregulation of electricity markets has resulted in the separation of electricity transmission systems from the former vertical integrated utilities. In the deregulated environment, pricing of this natural monopoly should promote the economic and secure power system and market operation, allocate in a fair way the regulated revenue of the transmission owners to network users and provide the right economic signals for new transmission, generation and energy efficiency investments. The main objective of transmission system expansion planning in deregulated electricity markets is to provide competitive and non-discriminatory market conditions to all market participants while maintaining power system reliability and security to acceptable levels.
The subject of this thesis is: i) the implementation and evaluation of various transmission fixed cost allocation methods to network users and ii) the development of new methods and optimization tools to address the uncertainties involved in power system transmission expansion planning problem in deregulated electricity markets. In this thesis, the implementation of various approximate power flow tracing techniques and transmission fixed cost allocation methods is initially examined in a pool-based electricity market. Subsequently, a new method for allocating the annual fixed cost of each transmission facility is developed based on an optimal (smallest possible in terms of N-1 security) transmission facility capacity approximate use. The use of each facility is calculated using the generalized distribution factors for that system snapshot that requires the maximum optimal transmission facility capacity over an annual system operation. The proposed method can identify and charge accordingly the main beneficiaries of the existence of new and existing transmission facilities in various power system operating conditions. At the end of the thesis, the proposed transmission fixed cost allocation method is compared and implemented in parallel with marginal pricing of transmission considering either the whole network’s annual cost or only the fixed cost of the new installed facilities.
In the second part of the thesis, an improved harmony search algorithm is initially implemented and evaluated in the mixed integer static transmission expansion problem. A new formulation of the probabilistic transmission expansion problem is then proposed by introducing an upper limit to possible load shedding during system peak. This probabilistic problem is solved by using Benders decomposition technique along with Monte Carlo simulation for modeling input data uncertainty (peak load forecast, transmission facilities availability and wind farms production). Finally, two different cost-benefit formulations for the objective function of the transmission expansion planning problem in deregulated electricity markets are proposed depending on whether the final solution of the transmission expansion problem will be implemented as merchant investment or as an investment that aims to improve the economic operation and reliability of the system.
These two problem formulations are addressed by applying the proposed improved harmony search algorithm using marginal pricing of transmission that incorporates the cost of N-1 security in system locational marginal prices (LMPs) and considering the optimal capacity of network facilities as a criterion for selecting the candidate branches for expansion.