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This paper addresses the problem of voltage rise mitigation in distribution networks with distributed generation. A distributed automatic control approach is proposed to alleviate the voltage rise caused by active power injection. The objective of the proposed approach is not to control bus voltage but to guarantee that generator injections alone do not cause significant voltage rise: a solution in which distribution network operators (DNOs) are kept to their traditional task of voltage regulation for load demand. The approach is discussed in the perspective of effectiveness and adequacy. Its consequences to DNO control effort are evaluated. Illustration is provided for a single feeder with stochastic generation and transformer on-load tap-changing voltage regulation. Index Terms--Dispersed storage and generation, power distribution, power quality, risk analysis, voltage control.

The reimbursement for violation of customer quality standards such as maximal interruption frequency and duration is at the basis of modern quality of service regulation. In order to satisfy quality standards, distribution operators periodically reconfigure the network so as to minimize the risk of reimbursement. Reconfiguration relies upon reliability analysis of an 'average year' and usually neglects the risk induced by failure variance. This is because the assessment of risk represents a considerable burden for real-scale systems. In this paper, we study the decision error induced by analyzing 'average years' and investigate the evolution of this error with the periodicity of reconfiguration. Examples are given for illustrating the main results. Index Terms--Network reconfiguration, optimization, power distribution, quality of service, risk assessment.

The traditional design of distribution networks does not target the satisfaction of individual quality standards such as maximal frequency and duration of customer interruptions. Yet, standards on individual quality are at the basis of most modern quality of service (QoS) regulations. In this paper, we use a matured evolutionary-based application to search for the optimum tradeoff between individual QoS and system reliability. Tradeoff results are presented to compare the traditional with the modern regulation designs and to illustrate that system optimum reliability must be decreased in order to improve individual quality at constant investment. The tradeoff sensitivity to the standards is then illustrated to discuss regulation effectiveness. Index Terms--Optimization methods, power distribution planning, quality of service, regulation, reliability.

In this paper, the issue of the capacity credit provided by wind energy conversion systems (WECS) is addressed. A chronological method of post-evaluation of the capacity credit is presented and compared with a pre-evaluation probabilistic method. The proposed chronological approach is based on the computation of the WECS capacity factor (ratio between average and total output) over some relevant time period. An appropriate choice of the time interval, for instance the peak load hours, will lead to a closer approximation of the capacity credit. The comparison is illustrated with two case-studies, concerning the Portuguese electric system. The analysis of the theoretical background of both methods and the results obtained allow the conclusion that chronological methods are best designed to assist system operators, whereas probabilistic methods, which are developed within the logic of the public system avoided resources, are a helping tool for system planners. Index Terms--Capacity credit, chronological methods, power systems operation, power systems planning, power systems reliability, probabilistic methods, wind power generation.