Abstract

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.

Abstract
This paper addresses the short-term allocation of active/reactive power supplies in transmission systems in a market environment. The basic issue addressed by most papers is related to market mechanisms involving active power either in terms of a pool or by bilateral contracts. However, in several countries Volt/Var control 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 mathematical formulation for the active power dispatch using bids from market agents and inherently taking into account the local nature of Volt/Var control by considering an AC model for the network. The discrete operation of several components as transformer taps and capacitor sections are accurately taken care by 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.

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.

Abstract
In this paper we describe a multiobjective formulation for the long term planning of distribution networks considering a number of important features. The model admits fuzzy representations for loads and evaluates nodal long term marginal prices. It integrates a number of criteria related to investment, operational and reliability costs, risk index measuring the ability to accommodate load uncertainties and the remuneration collected using long term marginal prices. After using a Simulated Annealing approach to identify efficient expansion plans, it is finally conducted a decision analysis in order to select the most adequate plan. At a final section, we illustrate the formulation with a case study based on a Portuguese distribution network.

Abstract
In this paper we describe a new approach to identify the combination of tap transformer positions, capacitor bank steps together with the minimum amount of toad to be shed that assures one to obtain a specified security degree of a power system. The basic approach is designed to identify the most adequate actions to be taken for a given contingency. This identification procedure uses Genetic Algorithms given their adequacy to model discrete actions. However, Genetic Algorithms are known for their usually large computation time. In order to address this issue and having in mind the objective of developing a real time tool, we incorporated a classification procedure based on Neural Networks. The paper includes results obtained using the developed approach both to evaluate the quality of the solutions for a number of contingencies and the quality of the overall performance when using the Neural Network tool. Results obtained for a reduced version of the Brazilian Mate Grosso transmission system are presented and discussed.