Abstract
One of the challenges that generation companies having hydro stations are facing corresponds to build the most adequate bids to send to day-ahead markets, maximizing their profit and taking into account the expect inflows, market prices and the interdependency between hydro plants in cascades. As a contribution to address this problem, this paper describes a short-term optimization model to build one-week schedules for a set of hydro power plants so that the outputs can be used to bid in the day-ahead market. This model is coordinated with a medium-scale (one year) model that inputs the value of using the water in the short-term problem. The developed model considers the non-linear relationship between the electric power, the net head and the turbine discharge and it takes in consideration pumping as well. The solution approach is based on an under-relaxed iterative procedure based on the algorithm described in [1] and the players are considered as price-takers, so that market prices are input variables. To solve the medium-term problem we propose a similar model that sends information about the final week volumes of each power plant to the short-term problem. On the other hand, we conducted a scenario analysis regarding market prices and inflows to internalize uncertainty. Finally, the model was successfully applied to a real size Portuguese cascade and the paper includes several results to illustrate the application of the developed models.

Abstract
Transmission expansion planning corresponds to a very relevant issue that should not be forgotten in the scope of the implementation of market mechanisms in the electricity sector. This paper describes a multicriteria model to perform transmission expansion planning exercises that combines probabilistic models to represent the reliability of system components with fuzzy models to incorporate the uncertainty on load evolution along the planning horizon. This formulation also outputs long-term marginal prices that can be used to compute the Marginal Based Remuneration. The paper includes a case study based on the Portuguese 400/220/150 kV transmission network.

Abstract
This paper describes the research under development regarding the integration of several types of micro-source in LV distribution networks. This research is financed through an EU R&D project and tackles several scientific and technological related problems in the fields of micro-source electrical modelling, power system LV operational impact analysis, monitoring and control, power quality and network reliability, protection coordination and personnel safety, communications, economical and electrical market driven procedures and definition of new interconnection standards. In particular, in this paper we describe an approach to schedule micro-source generation and to validate that dispatch from a technical point of view using a lineraized optimization problem. The paper includes results from a case study developed in a LV test network used in the scope of the referred project.

Abstract
Ancillary Services play an important role in power systems since they are crucial to ensure the security and quality of operation. However, this issue is sometimes forgotten and power systems tend to be analysed only from the point of view of electricity markets to schedule active power. In several countries, active and reactive dispatches were decoupled but in fact this causes several inefficiencies and technical difficulties since their schedules is not independent and the two of them determine the operation conditions of power systems. This paper describes an active / reactive dispatch model that retains the competitive aspects currently in force in power systems. It is based on an initial pool dispatch and on adjustment bids used to change generation or load values namely to accommodate losses or to curtail load if that is required to meet operation or technical constraints. This certainly contributes to clarify the roles of the Market and System Operators and to turn the decisions from the System Operator more robust and justifiable from a technical point of view.

Abstract
This paper addresses the problem of transmission expansion-planning in the context of the re-regulation and liberalization of power systems. The transmission expansion-planning problem is formulated as an integer problem and it is solved keeping that characteristic using Simulated Annealing. In the scope of the access to the transmission networks and the corresponding payments for Use of Networks, the paper discusses the advantages and drawbacks from adopting several cost methods and, more specifically, short-term and long-term nodal marginal prices. Long-term marginal prices are computed in the framework of the Simulated Annealing algorithm and led to the calculation of the Marginal Based Remuneration to the transmission company. The paper includes case studies based on the Portuguese 400/220/150 kV network and on a didactic 6-bus system. © 2003 IEEE.

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.