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Publications

Publications by CPES

2014

Theoretical interruption model for reliability assessment of power supply systems

Authors
Ilie I.; Hernando-Gil I.; Djokic S.;

Publication
IET Generation, Transmission and Distribution

Abstract
This study introduces a new theoretical interruption model for assessing more accurately the moment in time when interruptions of electricity customers are likely to occur. Recordings of short and long interruptions from two power supply systems are analysed and the similarity between their patterns is identified and then used to introduce a general interruption probability distribution model, defined in stages as multi-zone theoretical curves. The effectiveness of the proposed theoretical interruption model is firstly verified for a basic test system supplying an aggregate load point whose power profiles (residential, commercial, industrial and mixed load) are engaged in assessing the energy not supplied, and afterwards for a typical UK power supply system consisting of about 15 000 electricity customers. The results show that a correct representation of the moment of interruption performed with the proposed model leads to completely different results than those obtained based on the conventional assumption that the time when interruption occurs is given by a known probability distribution. Moreover, comparisons against reported figures of reliability indices determine the most suitable probability distribution that shall be used to model the initial conditions of the Monte Carlo simulation and accompany the proposed theoretical model throughout the simulation process. © The Institution of Engineering and Technology 2014.

2014

Risk assessment of interruption times affecting domestic and non-domestic electricity customers

Authors
Ilie I.; Hernando-Gil I.; Djokic S.;

Publication
International Journal of Electrical Power and Energy Systems

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.

2013

A multi-energy modelling, simulation and optimization environment for urban energy infrastructure planning

Authors
Page, J; Basciotti, D; Pol, O; Fidalgo, JN; Couto, M; Aron, R; Chiche, A; Foumie, L;

Publication
Proceedings of BS 2013: 13th Conference of the International Building Performance Simulation Association

Abstract
Tins paper presents a multi-energy modelling environment developed to simulate and optimize urban energy strategies, with a focus on urban energy infrastructure planning. A multi-scale approach is applied for modelling urban energy networks, considered as the backbone of urban energy infrastructure. This is complemented by the modelling of energy demand (to consider the costs and impacts of demand-side measures. The model is also linked to a set of optimization techniques in order to provide answers to urban energy infrastructure planning issues. Two case study applications follow the presentation of the chosen modelling principles to illustrate the type of answers that can be provided by the proposed modelling and optimization approach. Copyright © 2011 by IPAC'11/EPS-AG.

2013

A multi-scale optimization model to assess the benefits of a smart charging policy for electrical vehicles

Authors
Chammas, M; Chiche, A; Fournie, L; Nuno Fidalgo, JN; Couto, MJ;

Publication
2013 IEEE GRENOBLE POWERTECH (POWERTECH)

Abstract
The recent development of electric vehicles (EVs) has brought a new set of problems regarding their integration in power networks, particularly in terms of the potential growth of peak load. The peak growth leads to the increase of losses and braches charging and to voltage drops. Conversely, optimizing EV charging policy creates new opportunities for both network safety and energy trading through the markets. This paper presents a multi-level framework combining two representations of a medium voltage (MV) network in order to optimize the EV charging policy. A minimizing cost approach is set, modeling day-ahead markets, and taking into account losses. The proposed methodology is tested on a typical MV network.

2013

Application of probabilistic wind power forecasting in electricity markets

Authors
Zhou, Z; Botterud, A; Wang, J; Bessa, RJ; Keko, H; Sumaili, J; Miranda, V;

Publication
WIND ENERGY

Abstract
This paper discusses the potential use of probabilistic wind power forecasting in electricity markets, with focus on the scheduling and dispatch decisions of the system operator. We apply probabilistic kernel density forecasting with a quantile-copula estimator to forecast the probability density function, from which forecasting quantiles and scenarios with temporal dependency of errors are derived. We show how the probabilistic forecasts can be used to schedule energy and operating reserves to accommodate the wind power forecast uncertainty. We simulate the operation of a two-settlement electricity market with clearing of day-ahead and real-time markets for energy and operating reserves. At the day-ahead stage, a deterministic point forecast is input to the commitment and dispatch procedure. Then a probabilistic forecast is used to adjust the commitment status of fast-starting units closer to real time, on the basis of either dynamic operating reserves or stochastic unit commitment. Finally, the real-time dispatch is based on the realized availability of wind power. To evaluate the model in a large-scale real-world setting, we take the power system in Illinois as a test case and compare different scheduling strategies. The results show better performance for dynamic compared with fixed operating reserve requirements. Furthermore, although there are differences in the detailed dispatch results, dynamic operating reserves and stochastic unit commitment give similar results in terms of cost. Overall, we find that probabilistic forecasts can contribute to improve the performance of the power system, both in terms of cost and reliability. Copyright (c) 2012 John Wiley & Sons, Ltd.

2013

Demand Dispatch and Probabilistic Wind Power Forecasting in Unit Commitment and Economic Dispatch: A Case Study of Illinois

Authors
Botterud, A; Zhou, Z; Wang, JH; Sumaili, J; Keko, H; Mendes, J; Bessa, RJ; Miranda, V;

Publication
IEEE TRANSACTIONS ON SUSTAINABLE ENERGY

Abstract
In this paper, we analyze how demand dispatch combined with the use of probabilistic wind power forecasting can help accommodate large shares of wind power in electricity market operations. We model the operation of day-ahead and real-time electricity markets, which the system operator clears by centralized unit commitment and economic dispatch. We use probabilistic wind power forecasting to estimate dynamic operating reserve requirements, based on the level of uncertainty in the forecast. At the same time, we represent price responsive demand as a dispatchable resource, which adds flexibility in the system operation. In a case study of the power system in Illinois, we find that both demand dispatch and probabilistic wind power forecasting can contribute to efficient operation of electricity markets with large shares of wind power.

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