Iman Rahmati

Short circuit current is one of the major threats for power system stability. Power system should have the ability to detect and clear these faults within a specified time. The protection system can clear the faults only if the interruption capability of the circuit breakers is higher than the fault level. Expansion of the grid and installation of new power

Considering the fact that restructuring in power systems brought up the subject of energy pricing as a very important issue in electricity markets, market designers in some countries and regions decided to pay generating units for their available generating capacities and producing electrical energy separately. Based on this design, the capacity payment guarantees the fixed costs of the generating units to be recovered because it is paid for their capacities regardless of their electricity production. In Iran electricity market, all generating units are paid for their produced energy and their available generating capacities. In this paper, a new algorithm to calculate the capacity payment is proposed and is tested on Iran electric network. Results show that the proposed method is effective and produces proper signal to value the unit available capacity through the different hours during a year.

ABSTRACT Most of countries have started restructuring process as the salvation route of electricity industry. In the new environment, competition is a fundamental key and it is well known that in any competition, fairness is the major concern of the players. Generally, competition in power system has been started from generation sector, and winners of this competition are chosen via Unit commitment procedure which is supposed to be fair. In Iran central market, Unit Commitment procedure is an optimization problem constrained by some technical limitations including unit operational limitations, grid limitation and reliability requirements. This paper discusses how in Iran Electricity Market the unit constraints affect Unit Commitment result and argues whether these constraints are dealt in a fair manner or not.

Restructuring brought about gross change to the electricity industry and the vertical integrated structure of three major sectors, Generation, Transmission and Distribution has been broken down. In this new environment each sector is supposed to be a separate business which should be managed economically. Competition in Generation and Distribution sector have been emerged applicable and most countries use competition structure