Abstract
Legislation defined to protect domestic and non-domestic customers from long durations of interruptions includes additional requirements to system's reliability-related performance that distribution network operators (DNOs) must consider in planning the operation and maintenance process of power supply systems. DNOs are required to restore the supply to interrupted customers that fall into "unprotected" customer class within a given period of time, otherwise penalties are applied. In order to meet these requirements, comprehensive strategies must be defined based on upfront analyses. Accordingly, this paper proposes a deterministic algorithm for estimating DNOs' risk of experiencing interruptions with durations above imposed targets. Besides the Regulator-defined legislation, security of supply requirements are engaged in the development of the proposed methodology. Failure analysis of network components is used to identify interrupted customers that are grouped into power demand classes such that the duration of interruptions can be addressed following the security of supply requirements. Moreover, the penalty times defined by the Energy Regulator are engaged in the analysis and used as thresholds to quantify the penalty risk that DNOs are exposed to. The proposed methodology is applied to a typical UK distribution system, whose average reliability performance is also considered in the analysis. © 2013 Elsevier Ltd. All rights reserved.

Abstract
This paper is part one of a two-part series discussing how Regulator requirements for continuity of supply could be incorporated in the reliability analysis of existing electricity networks and future 'smart grids'. The paper uses examples of overall and guaranteed standards of performance from the UK and Italy, specifying requirements that network operators should satisfy with respect to excessively long and/or too frequent supply interruptions. Besides the relevant Regulator requirements, this paper presents input data, parameters and models required for comprehensive reliability assessment, while Part 2 paper presents scenarios and results for test network based on both analytical and probabilistic reliability procedures.

Abstract
This is the second paper in a two-part series discussing how Regulator requirements for continuity of supply could be incorporated in the reliability analysis of existing electricity networks and future 'smart grids'. Part 1 paper presents input data, parameters and models required for a comprehensive assessment of system reliability performance, including an overview of the overall and guaranteed standards of performance in the UK and Italy. This paper presents scenarios and results of both analytical and probabilistic reliability assessment procedures for the test network introduced in Part 1 paper.

Abstract
This paper, which can be divided into two main interrelated studies, firstly describes the generic modelling of a sub-transmission network model to serve as a UK variant of the original IEEE 14-bus test system. The revised model, based on the actual/realistic power components found both in the UK and in European grids, provides an updated and complete technical description, ready for use in a variety of power system studies, in which the 14-bus test system is one of the most commonly used in the literature. Afterwards, this paper categorises the typical demand characteristics of the residential load sector in the UK, by providing a wider range of reference demand values and loading conditions for the planning and modelling studies of distribution networks, dividing them into four generic residential load subsectors. Different 'after diversity demand' values are therefore provided per residential load subsector, classes of customers and seasonal variations of annual power consumption.

Abstract
This study presents an integrated approach for reliability planning and risk estimation in active distribution systems. By incorporating the use of accurate reliability equivalents for different medium voltage/low voltage networks and load subsectors, a probabilistic methodology is proposed to capture both power quality and reliability aspects in power system planning, which potentially avoids the underestimation of system's performance at bulk supply points. A 'time to restore supply' concept, based on security of supply legislation, is introduced to quantify the effect of different network functionalities such as the use of backup supply or automatic/manual reconfiguration schemes. The range of annual reliability indices reported by 14 network operators in the UK is also used for the validation of reliability results, which allows estimating the risk of interruption times above the regulator-imposed limits. Accordingly, conventional reliability assessment procedures are extended in this study by analysing a meshed urban distribution network through the application of a time-sequential Monte Carlo simulation. The proposed methodology also acknowledges the use of time-varying fault probabilities and empirical load profiles for a more realistic estimation of customer interruptions. A decision-making approach is shown by assessing the impact of several network actions on the accuracy of reliability performance results.

Abstract