2004
Authors
Nunes, E; Matos, MA; Faria, J; da Silva, JP;
Publication
2004 INTERNATIONAL CONFERENCE ON PROBABILISTIC METHODS APPLIED TO POWER SYSTEMS
Abstract
Unbundling and liberalization of the electric sector has led in many countries, including Portugal, to the settlement definition of quality standards for the power distribution systems that give rise to penalties when those standards are not met. Also, penalties and rewards related to global reliability indices exist in some countries. Distribution companies must take this into account when planning there systems because the minimization of the net reliability cost is a main criteria when making investment decisions performing reliability studies to support investment decisions, and penalties (or rewards) become direct reliability costs (or benefits), regardless of any other consideration concerning the impact of the frequency and duration of the interruptions. Most of the time, standards are defined in terms of the sum of the interruption durations during a year. In this paper, the details of this discussion are addressed, in the framework of the investment decision-making process. A formal model for the problem is proposed, along with methodologies able to tackle it. The inadequacy of a markovian approach is discussed and illustrated, showing how bad investment decisions can be made due to incorrect evaluation of the reliability costs. The discussion will be illustrated with small numerical examples.
2004
Authors
Gouveia, EM; Matos, MA;
Publication
2004 INTERNATIONAL CONFERENCE ON PROBABILISTIC METHODS APPLIED TO POWER SYSTEMS
Abstract
Defining the needs of operating reserve in a power system has been always a subject of interest, leading to the development of deterministic rules (e.g. the percentage rule defined by UCTE in Europe or the well-known "largest unit" rule) and probabilistic methods like PJM (Pennsylvania-New Jersey-Maryland) and its enhancements, based on the concept of risk. However, the recent increase in the penetration of wind power generation changed the framework of this evaluation, due to the volatile nature of this kind of energy. In this paper, a detailed model of the unavailability of wind parks that accounts both for machine failures and different wind levels is combined with the modified PJM method, in order to build a consistent framework for the evaluation of the operational risk. The paper also shows how the proposed model can be used as a decision-aid tool for planning the operational reserve, either by performing multicriteria analysis on cost and risk or by stipulating an acceptable risk level.
2004
Authors
Papadogiannis, KA; Hatziargyriou, ND; Saraiva, JT;
Publication
ENGINEERING INTELLIGENT SYSTEMS FOR ELECTRICAL ENGINEERING AND COMMUNICATIONS
Abstract
This paper addresses the short-term allocation of active/reactive power supplies in transmission systems in a market environment. In many papers market mechanisms to allocate active power within a pool or by bilateral contracts are described. in several Countries Volt/Var control also started to be considered, at least partially, as a marketable service and so new methodologies are required to support this process. This paper presents an integrated multi-objective formulation for the active/reactive power dispatch based on bids from market agents. The local nature of Volt/Var control is provided by the AC power flow equations. The formulation also considers two more objective functions related to system operational efficiency and security. The operation of discrete components as transformer taps and capacitor sections is accurately considered using Simulated Annealing. The proposed methodology is applied on the 30-bus IEEE test system highlighting its advantages and demonstrating the feasibility of its use in real systems.
2004
Authors
Braga, ASD; Saraiva, JT;
Publication
2004 INTERNATIONAL CONFERENCE ON PROBABILISTIC METHODS APPLIED TO POWER SYSTEMS
Abstract
In this paper we present a multiyear dynamic transmission expansion planning formulation considering criteria related with reliability and investment and operation costs. This problem is solved using an interactive method that starts at a non-dominated solution identified by the epsilon-constraint method, in which all objectives except one are converted in constraints using aspiration levels. Afterwards, the decision maker can modify the initial aspiration levels to improve some specific criteria. As a final result, the algorithm determines long term marginal prices, reflecting both investment and operation costs. These prices are well suited to tariff the use of networks as they transmit economic signals to users while addressing the Revenue Reconciliation Problem, typical when using short term approaches. The described approach was used to identify the most adequate 6 year expansion plan for the Portuguese transmission system, the long term marginal prices and the percentage of cost recovery.
2004
Authors
Figueiredo, L; Machado, JAT; Ferreira, JR;
Publication
Conference Proceeding - IEEE International Conference on Networking, Sensing and Control
Abstract
This paper presents the Simulator of Intelligent Transportation Systems (SITS). The SITS is based on a microscopic simulation approach to reproduce real traffic conditions in an urban or non-urban network and considers different types of vehicles, drivers and roads. A dynamical analysis of several traffic phenomena is then addressed. The results of using classical system theory tools point out that it is possible to study traffic systems, taking advantage on the knowledge gathered with automatic control algorithms. In this line of thought, it was also presented a new modelling formalism based on the embedding of statistics and Fourier transform.
2004
Authors
Figueiredo, L; Machado, JAT; Ferreira, JR;
Publication
IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS
Abstract
The paper presents the simulator of intelligent transportation systems (SITS). The SITS is based on a microscopic simulation approach to reproduce real traffic conditions in an urban or nonurban network and considers different types of vehicles, drivers, and roads. A dynamical analysis of several traffic phenomena is then addressed. The results of using classical system theory tools notes that it is possible to study traffic systems, taking advantage of the knowledge gathered with automatic control algorithms. In this line of thought, a new modeling formalism based on the embedding of statistics and Fourier transform is also presented.
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