Electrical distribution utilities have been dealing with the problem of estimation of distribution network load diagrams, either for operation studies or in forecasting models for planning purposes. Load curve assessment is essential for an efficient management of electric distribution systems. However, the only information available for most of the loads (namely LV loads) is related to monthly energy consumptions. The general procedure uses measurements in consumers to construct inference engines that predict load curves using commercial information. This paper presents a new approach for this problem, based on Kohonen maps and Artificial Neural Networks (ANN) to estimate load diagramsfor the portuguese distribution utilities. A method for estimating error bars is also proposed in order to provide a high order information about the performance of load curve estimation process. Performance attained is discussed as well as the method to achieve confidence intervals of the main predicted diagrams.

A new method for distribution access via uniform pricing for the remuneration of distribution networks is presented. The proposed approach merges in a unified framework the investments, the optimal network operation requirements, the effect of the price elasticity of demand, and the application of hourly pricing for demand side management purposes. Hourly uniform marginal prices-understood as tariffs of use of the network-are obtained from maximum social welfare condition sending efficient signals to the utility and consumers, related to the optimal operation of the grid and use of the energy at peak and valley hours. This method is used in the context of a Performance Based Ratemaking regulation to get model companies from operational optimized real networks. Capital fees are integrated in the marginal tariff of use, by means of the New Replacement Value concept, broadly used in yardstick competition. The model is stated as a mixed-integer linear optimization problem suitable to be solved through well-known linear programming tools. The methodology has been successfully tested in a 42-bus test distribution network. Index Terms-Distribution access pricing, power system economics, tariffs of use, yardstick competition. I. INTRODUCTION T HE REGULATION of the electrical distribution activity based in the traditional paradigm of the Cost of Service/Rate of Return relation (CoS/RoR) engrosses or merges two distinct activities in the distribution function: distribution and retailing. The distribution utility is considered as a natural monopoly and end-user tariffs designs are usually based on the independent application of capacity and energy charges to deal with well-known revenue reconciliation problem [1]. Other types of regulation such as performance based ratemaking (PBR), have been applied in order to incentive distribution companies to be more efficient [2]. The distribution network activity remains considered as a natural monopoly and the retailing activity is open to the market. Different regulation schemes for distribution utilities as price caps, revenue caps, and yardstick competition have been developed and applied Manuscript

The implementation of market mechanisms to remunerate distributed generation should take into account a nondiscriminatory access to distribution networks. In consequence, power losses of distribution network must be fairly allocated among the all distributed generators and consumers. Several methods for power loss cost allocation have been proposed in the literature, divided basically into two groups. Firstly, methods as postage stamp, mw-mile, circuit based and proportional sharing have been supported on an arbitrary allocation of power losses between consumers and generators, typically 50-50%. More recently, a modified proportional sharing procedure has been proposed based on the allocation of the entire losses to consumers disregarding the influence of distributed generators using the basic proportional sharing principle and reallocate avoided or produced losses among distributed generators. Secondly, marginal procedures have been extensively proposed in order to send efficient economical signals to the market agents. Marginal methods require a slack bus designation and do not assign arbitrarily power losses among producers and consumers. This paper presents a comparative study of different loss allocation procedures taking into account different levels of penetration of renewable sources in distribution networks. Results are obtained and discussed from a test distribution network.

In this paper we present a model to identify optimal operation strategies of electric distribution networks considering that one wants to minimize active power losses. This objective can be achieved by adequately selecting transformers taps and sections of capacitor banks that are in operation. In order to turn the model more realistic the developed application admits the specification of admissible voltage ranges for each node and maximum branch currents for each line and transformer. The integer nature of this problem virtually turned it impossible to be solved for real sized networks given its combinatorial nature, its complexity and thus the involved calculation time. In this paper we describe the use of a meta-heuristic-Simulated Annealing-to this problem in order to address the difficulties just referred. The use of the developed application will be illustrated using a IEEE test network and a realistic network having 645 nodes based on a Portuguese distribution system.