Efficient and Risk-Aware Control of Electricity Distribution Grids

This article presents an economic model predictive control (EMPC) algorithm for reducing losses and increasing the resilience of medium-voltage electricity distribution grids characterized by high penetration of renewable energy sources and possibly subject to natural or malicious adverse events. The proposed control system optimizes grid operations through network reconfiguration, control of distributed energy storage systems (ESSs), and on-load tap changers. The core of the EMPC algorithm is a nonconvex optimization problem integrating the ESSs dynamics, the topological and power technical constraints of the grid, and the modeling of the cascading effects of potential adverse events. An equivalent (i.e., having the same optimal solution) proxy of the nonconvex problem is proposed to make the solution more tractable. Simulations performed on a 16-bus test distribution network validate the proposed control strategy

Achieving the Dispatchability of Distribution Feeders through Prosumers Data Driven Forecasting and Model Predictive Control of Electrochemical Storage

We propose and experimentally validate a control strategy to dispatch the operation of a distribution feeder interfacing heterogeneous prosumers by using a grid-connected battery energy storage system (BESS) as a controllable element coupled with a minimally invasive monitoring infrastructure. It consists in a two-stage procedure: day-ahead dispatch planning, where the feeder 5-minute average power consumption trajectory for the next day of operation (called \emph{dispatch plan}) is determined, and intra-day/real-time operation, where the mismatch with respect to the \emph{dispatch plan} is corrected by applying receding horizon model predictive control (MPC) to decide the BESS charging/discharging profile while accounting for operational constraints. The consumption forecast necessary to compute the \emph{dispatch plan} and the battery model for the MPC algorithm are built by applying adaptive data driven methodologies. The discussed control framework currently operates on a daily basis to dispatch the operation of a 20~kV feeder of the EPFL university campus using a 750~kW/500~kWh lithium titanate BESS.Comment: Submitted for publication, 201

Monitoring and Fault Location Sensor Network for Underground Distribution Lines

One of the fundamental tasks of electric distribution utilities is guaranteeing a continuous supply of electricity to their customers. The primary distribution network is a critical part of these facilities because a fault in it could affect thousands of customers. However, the complexity of this network has been increased with the irruption of distributed generation, typical in a Smart Grid and which has significantly complicated some of the analyses, making it impossible to apply traditional techniques. This problem is intensified in underground lines where access is limited. As a possible solution, this paper proposes to make a deployment of a distributed sensor network along the power lines. This network proposes taking advantage of its distributed character to support new approaches of these analyses. In this sense, this paper describes the aquiculture of the proposed network (adapted to the power grid) based on nodes that use power line communication and energy harvesting techniques. In this sense, it also describes the implementation of a real prototype that has been used in some experiments to validate this technological adaptation. Additionally, beyond a simple use for monitoring, this paper also proposes the use of this approach to solve two typical distribution system operator problems, such as: fault location and failure forecasting in power cables.Ministerio de Economía y Competitividad, Government of Spain project Sistema Inteligente Inalámbrico para Análisis y Monitorización de Líneas de Tensión Subterráneas en Smart Grids (SIIAM) TEC2013-40767-RMinisterio de Educación, Cultura y Deporte, Government of Spain, for the funding of the scholarship Formación de Profesorado Universitario 2016 (FPU 2016

Ancillary Services in Hybrid AC/DC Low Voltage Distribution Networks

In the last decade, distribution systems are experiencing a drastic transformation with the advent of new technologies. In fact, distribution networks are no longer passive systems, considering the current integration rates of new agents such as distributed generation, electrical vehicles and energy storage, which are greatly influencing the way these systems are operated. In addition, the intrinsic DC nature of these components, interfaced to the AC system through power electronics converters, is unlocking the possibility for new distribution topologies based on AC/DC networks. This paper analyzes the evolution of AC distribution systems, the advantages of AC/DC hybrid arrangements and the active role that the new distributed agents may play in the upcoming decarbonized paradigm by providing different ancillary services.Ministerio de Economía y Competitividad ENE2017-84813-RUnión Europea (Programa Horizonte 2020) 76409

Power quality and electromagnetic compatibility: special report, session 2

The scope of Session 2 (S2) has been defined as follows by the Session Advisory Group and the Technical Committee: Power Quality (PQ), with the more general concept of electromagnetic compatibility (EMC) and with some related safety problems in electricity distribution systems. Special focus is put on voltage continuity (supply reliability, problem of outages) and voltage quality (voltage level, flicker, unbalance, harmonics). This session will also look at electromagnetic compatibility (mains frequency to 150 kHz), electromagnetic interferences and electric and magnetic fields issues. Also addressed in this session are electrical safety and immunity concerns (lightning issues, step, touch and transferred voltages). The aim of this special report is to present a synthesis of the present concerns in PQ&EMC, based on all selected papers of session 2 and related papers from other sessions, (152 papers in total). The report is divided in the following 4 blocks: Block 1: Electric and Magnetic Fields, EMC, Earthing systems Block 2: Harmonics Block 3: Voltage Variation Block 4: Power Quality Monitoring Two Round Tables will be organised: - Power quality and EMC in the Future Grid (CIGRE/CIRED WG C4.24, RT 13) - Reliability Benchmarking - why we should do it? What should be done in future? (RT 15

Impact Analysis and Mitigation of Voltage Regulation Issues in PV Rich Low Voltage Residential Distribution Networks

Modern distribution networks are undergoing major changes with the increased uptake of rooftop photovoltaic (PV) units in low voltage (LV) residential distribution networks. These renewable based distributed energy resources (DERs) impose adverse effects which can propagate from LV to medium voltage (MV) and high voltage (HV) levels. Some of the major areas of concern to network operators include reverse power flow, voltage unbalance, voltage rise, increased harmonics, increased potential of islanding, and component and line overloading. These issues create both an operational mitigation requirement and a need for Distribution Network Service Providers (DNSPs) to adjust LV network design procedures. In Australia DNSPs are bound by strict regulation to provide supply to customers complying with several power quality standards. Australian Standard AS 61000.3.100 requires the voltage at the consumer point of supply to be within +10%, -6% of the 230 V nominal for single phase LV customers. Since residential peak load is typically observed during evening time and power generated from PV during daytime, rooftop PV does little to reduce peak demand. Increased numbers of rooftop PV systems in future LV feeders, combined with increased demand, means DNSPs need to invest in infrastructure to alleviate issues related to overgeneration or overloading and voltage regulation. Traditionally, voltage regulation devices such as on-load tap changers (OLTCs), regulators and capacitor banks have been sufficient to regulate voltage within mandated limits. Bidirectional power flow that arises as a result of DER in LV limits the ability of these devices, as LV voltage issues cannot be detected or do not propagate further up the network. Compared to HV/MV networks, residential LV networks experience more variable loads, have inherent unbalance due to the overhead 4-wire structure, and lack visibility with respect to operational states. This thesis aims to contribute new knowledge and understanding to the field of power distribution network voltage regulation. This includes investigation and analysis of different approaches to voltage regulation in power distribution networks in the literature, and to propose new methods and improvements to existing methods. Specifically, this thesis aims to highlight the shortcomings of the current voltage regulation techniques available to DNSPs in LV feeder. The case studies to be provided in this thesis presents 24 h time series simulation to investigate the performance with varying load and PV generation

Smart Vehicle to Grid Interface Project: Electromobility Management System Architecture and Field Test Results

This paper presents and discusses the electromobility management system developed in the context of the SMARTV2G project, enabling the automatic control of plug-in electric vehicles' (PEVs') charging processes. The paper describes the architecture and the software/hardware components of the electromobility management system. The focus is put in particular on the implementation of a centralized demand side management control algorithm, which allows remote real time control of the charging stations in the field, according to preferences and constraints expressed by all the actors involved (in particular the distribution system operator and the PEV users). The results of the field tests are reported and discussed, highlighting critical issues raised from the field experience.Comment: To appear in IEEE International Electric Vehicle Conference (IEEE IEVC 2014

Distribution system congestion management through market mechanism

Nowadays, the electricity industry has experienced essential changes compared to the past. The idea of distributed generations (DGs) in distribution networks replacing the bulk power plants traditionally connected to the high voltage levels is one of those changes. Irrespective of the positive aspects of the mentioned change, congestion is the problem that is increasingly occurring in distribution systems due to an upward trend in DGs’ penetration in distribution net-works. Methods to solve the congestion in distribution networks has received the attention of researchers and those who are working in the distribution network domain recently. The idea of the thesis is to solve the congestion in distribution networks through market mechanisms. To do so, a simulation environment is designed and implemented in order to ena-ble us to analyze and understand the features of various scenarios associated with congestion management with or without using market mechanisms. By using the simulation environment, five different scenarios are investigated, and the results show the congestion relief of the distri-bution network by linking the flexibility buyers (distribution system operators (DSOs)) to flexibil-ity providers (aggregators) through the local flexibility market (LFM) platform. Timing and fre-quency of operation are proposed for LFM in the thesis. Besides, the benefits of LFM for DSOs are investigated, and the impact of inaccuracy in predictive optimal power flow (OPF) on the real-time operation of the distribution system is studied as well