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Publications

Publications by Ignacio Gil

2019

Evaluation of customer-oriented power supply risk with distributed pv-storage energy systems

Authors
Ndawula M.B.; De Paola A.; Hernando-Gil I.;

Publication
2019 IEEE Milan PowerTech, PowerTech 2019

Abstract
The valuation of whether network operators meet users' expectations in ensuring a continuous supply to their premises is important in determining their willingness-to-pay (WTP) for electricity. Distributed resources such as photovoltaic (PV) systems will dominate future networks, and thus customers' WTP will vary dynamically, both spatially and temporally. Whereas system-wide indices are typically used to assess network performance, there is a requirement to complement these with customer-based indices to accurately quantify the risk of outages to affected and worst-served customers. This paper presents an enhanced Monte Carlo simulation technique, which performs reliability assessment of a typical MV/LV urban distribution network. Two smart grid scenarios considering controllability of PV and energy storage (ES) are designed to improve network performance. Customerbased reliability indices, measuring the frequency and duration of interruptions, and energy not supplied are thoroughly assessed. Results demonstrate the potential of hybrid PV-ES in reducing power supply risk for worst-served customers.

2019

Optimal home energy management under hybrid photovoltaic-storage uncertainty: A distributionally robust chance-constrained approach

Authors
Zhao P.; Wu H.; Gu C.; Hernando-Gil I.;

Publication
IET Renewable Power Generation

Abstract
Energy storage and demand response (DR) resources, in combination with intermittent renewable generation, are expected to provide domestic customers with the ability to reducing their electricity consumption. This study highlights the role that an intelligent battery control, in combination with solar generation, could play to increase renewable uptake while reducing customers' electricity bills without intruding on people's daily life. The optimal performance of a home energy management system (HEMS) is investigated through a range of interventions, leading to different levels of customer weariness and consumption patterns. Thus, the DR is applied with efficient and specific control of domestic appliances through load shifting and curtailment. Regarding the uncertainty associated with the photovoltaic generation, a chance-constrained (CC) optimal scheduling is considered subject to the operation constraints from each power component in the HEMS. By applying distributionally robust optimisation, the ambiguity set is accurately built for this distributionally robust CC (DRCC) problem without the need for any probability distribution associated with uncertainty. Based on the greatly altered consumption profiles in this study, the proposed DRCC-HEMS is proven to be optimally effective and computationally efficient while considering uncertainty.

2019

Reliability enhancement in power networks under uncertainty from distributed energy resources <sup>†</sup>

Authors
Ndawula M.B.; Djokic S.Z.; Hernando-Gil I.;

Publication
Energies

Abstract
This paper presents an integrated approach for assessing the impact that distributed energy resources (DERs), including intermittent photovoltaic (PV) generation, might have on the reliability performance of power networks. A test distribution system, based on a typical urban MV and LV networks in the UK, is modelled and used to investigate potential benefits of the local renewable generation, demand-manageable loads and coordinated energy storage. The conventional Monte Carlo method is modified to include time-variation of electricity demand profiles and failure rates of network components. Additionally, a theoretical interruption model is employed to assess more accurately the moment in time when interruptions to electricity customers are likely to occur. Accordingly, the impact of the spatio-temporal variation of DERs on reliability performance is quantified in terms of the effect of network outages. The potential benefits from smart grid functionalities are assessed through both system- and customer-oriented reliability indices, with special attention to energy not supplied to customers, as well as frequency and duration of supply interruptions. The paper also discusses deployment of an intelligent energy management system to control local energy generation-storage-demand resources that can resolve uncertainties in renewable-based generation and ensure highly reliable and continuous supply to all connected customers.

2020

Deterministic and Probabilistic Assessment of Distribution Network Hosting Capacity for Wind-Based Renewable Generation

Authors
Fang, D; Zou, M; Harrison, G; Djokic, SZ; Ndawula, MB; Xu, X; Hernando-Gil, I; Gunda, J;

Publication
2020 International Conference on Probabilistic Methods Applied to Power Systems (PMAPS)

Abstract

2020

Two-Stage Distributionally Robust Optimization for Energy Hub Systems

Authors
Zhao P.; Gu C.; Huo D.; Shen Y.; Hernando-Gil I.;

Publication
IEEE Transactions on Industrial Informatics

Abstract
Energy hub system (EHS) incorporating multiple energy carriers, storage, and renewables can efficiently coordinate various energy resources to optimally satisfy energy demand. However, the intermittency of renewable generation poses great challenges on optimal EHS operation. This article proposes an innovative distributionally robust optimization model to operate EHS with an energy storage system (ESS), considering the multimodal forecast errors of photovoltaic (PV) power. Both battery and heat storage are utilized to smooth PV output fluctuation and improve the energy efficiency of EHS. This article proposes a novel multimodal ambiguity set to capture the stochastic characteristics of PV multimodality. A two-stage scheme is adopted, where 1) the first stage optimizes EHS operation cost, and 2) the second stage implements real-time dispatch after the realization of PV output uncertainty. The aim is to overcome the conservatism of multimodal distribution uncertainties modeled by typical ambiguity sets and reduce the operation cost of EHS. The presented model is reformulated as a tractable semidefinite programming problem and solved by a constraint generation algorithm. Its performance is extensively compared with widely used normal and unimodal ambiguity sets. The results from this article justify the effectiveness and performance of the proposed method compared to conventional models, which can help EHS operators to economically consume energy and use ESS wisely through the optimal coordination of multienergy carriers.

2021

Stochastic Planning and Operational Constraint Assessment of System-Customer Power Supply Risks in Electricity Distribution Networks

Authors
Kisuule, M; Hernando-Gil, I; Serugunda, J; Namaganda-Kiyimba, J; Ndawula, MB;

Publication
Sustainability

Abstract
Electricity-distribution network operators face several operational constraints in the provision of safe and reliable power given that investments for network area reinforcement must be commensurate with improvements in network reliability. This paper provides an integrated approach for assessing the impact of different operational constraints on distribution-network reliability by incorporating component lifetime models, time-varying component failure rates, as well as the monetary cost of customer interruptions in an all-inclusive probabilistic methodology that applies a time-sequential Monte Carlo simulation. A test distribution network based on the Roy Billinton test system was modelled to investigate the system performance when overloading limits are exceeded as well as when preventive maintenance is performed. Standard reliability indices measuring the frequency and duration of interruptions and the energy not supplied were complemented with a novel monetary reliability index. The comprehensive assessment includes not only average indices but also their probability distributions to adequately describe the risk of customer interruptions. Results demonstrate the effectiveness of this holistic approach, as the impacts of operational decisions are assessed from both reliability and monetary perspectives. This informs network planning decisions through optimum investments and consideration of customer outage costs.

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