Abstract

Abstract
In this paper, we present a prototype of a DMS -Distribution Management System - using Object Oriented technology and a modular distributed multitask client-server architecture. The DMS is supported by an Object Oriented model in which the power system components are considered objects grouped in several classes according to their characteristics. The power system applications are software modules within this base platform that is physically located in a WEB server and are implemented in Java or C++. The users should connect to an HTML page in the server, download the desired applet to the client's machine establishing communication, interfaces and requesting services to the main system. The paper gives a global overview of the system, describes its architecture, gives details about the Database organization and describes the main characteristics and features of some power system applications as Topology Processor, Single Phase Power Flow and Symmetric Short Circuit. © 2001 IEEE.

Abstract
In the scope of a consultancy study conducted by the Power Systems Unit of INESC Porto, the yearly regulated remuneration of the Portuguese transmission provider was allocated to the network users considering an approach based on power-flow embedded methods. The tested cost allocation methods were the MW.mile, the Modulus and the Zero Counterflow. The application of that approach lead to geographically discriminated Tariffs for Use of Transmission Networks. This study must be considered as a contribution to the revision process of the current regulations when the first regulatory period is about to end. It should be emphasized that it was not the purpose of this study to question the current Cost of Service/Rate of Return strategy in force in the Portuguese transmission sector and to calculate the adequate yearly remuneration of the transmission provider. The only objective of this study was to simulate the application of alternative cost allocation approaches, given that the whole amount to allocate is fixed by current rules. In this way, we think it is possible to contribute to a more technically sounded discussion about the advantages and drawbacks of several approaches. © 2001 IEEE.

Abstract
In the scope of the revision of the Portuguese Tariff Regulation, the Power Systems Unit of INESC Porto concluded a consultancy study aiming at estimating the remuneration that could be obtained by the Portuguese transmission provider using Short Term Marginal Prices. This paper describes the main principles behind the regulation of the transmission sector in force in Portugal, details the model used to compute the nodal marginal prices in the transmission network, presents a comprehensive set of results for some scenarios in which the year was organized as well as the estimate of the referred remuneration. The data of the scenarios that were used is publicly available in [l] and we adopted typical values for generation costs of different thermal plants. At the end, the paper includes some conclusions as well as some ideas of hture work aiming at improving the quality of the estimate of the marginal based remuneration. © 2001 IEEE.

Abstract
In the scope of the reregulation process of the electric sector, both competitive pool markets and contract mechanisms at the generation and commercialization levels have been emerging. At the wholesale level, and apart from Pool structures and Bilateral Contracts, there are hybrid models in which these two types of structures coexist. In any case, the dispatch coming from the Pool Market Operator, prepared according to the buying and selling offers, together with the bilateral contracted powers must be analyzed from a technical point of view by an independent entity - System Operator. The System Operator aims at checking if the scheduled injected powers do not lead to a decrease of the security standards of the system. Taking in account this concern, in this paper we describe several models to perform the technical validation of sets of electricity schedules, namely trying to minimize the financial impact of the required changes on pre-scheduled generations and loads. This objective is modelled in terms of maximizing the satisfaction degree felt by the participants in the market. The developed application uses Simulated Annealing to solve the corresponding optimization problems. In Section IV of this paper we will include results obtained from several simulations in order to illustrate and demonstrate the interest of the referred models. © 2001 IEEE.

Abstract
In this paper we present a Monte Carlo based application to evaluate estimates of nodal marginal prices leading to target prices of transmission congestion contracts. The application integrates an optimization model to evaluate nodal marginal prices for each sampled state including an estimate of transmission losses. This formulation is integrated in a Monte Carlo simulation in order to deal with the probabilistic nature of component outages and to allow the user to represent load behavior using Load Duration Curves. The computational performance of the Monte Carlo simulation is enhanced by adopting a variance reduction acceleration technique based on a regression function. At a final section the paper includes results from a case study to illustrate the application of the model and to evaluate the efficiency of the referred acceleration technique. © 2001 IEEE.