N. Sorrentino

Purchase-Bidding Strategies of an Energy Coalition With Demand-Response Capabilities

The implementation of demand-response programs (DRP) has gained interest as a means to alleviate energy consumption during peak-hours. Two explanations account for the success of such programs which involve both utilities and electricity consumers, with the latter often organized into coalitions: the system operator meets its goal of reducing the load peak; simultaneously, electricity consumers achieve economic benefits when reducing consumption during peak hours. In this paper, a Monte Carlo-based algorithm has been proposed for the formulation of multiple purchase offers in the day-ahead energy market (DAEM) by coalitions in which consumers vary in their sensitivity to DRP, manifesting different responsiveness to hourly tariffs based on the hourly market clearing prices. Being able to monitor how coalition members use air-conditioning in the presence of variable hourly energy tariffs, the coordinator can then define a purchase-bidding strategy, depending on how price-sensitive the coalition is. Simulation results show that the presence of a price-sensitive demand leads not only to a subsequent reduction in energy prices during peak-hours but also leads to a decrease in their inter-hour volatility.

Energy Management System for an Energy District With Demand Response Availability

During recent years the electricity supply chain (electricity production, consumption, distribution, storage, and load management) has changed. In this context a new term appears: the prosumer, that is both a consumer and producer of energy in the same entity. In the paper, an energy management approach of several prosumers aggregated in a coalition, the energy district (ED), and coordinated through a central control entity, the coalition coordinator, is proposed. The aim of the coalition coordinator is to maximize the coalition utility also reducing in this way the reverse energy flows at the point of delivery by an appropriate demand response program. The application on an Italian residential housing area is illustrated. The numerical results demonstrate the effectiveness and attractiveness of the proposed energy management scheme.

An incremental conductance method with variable step size for MPPT: Design and implementation

In this paper the authors propose a novel method for tracking the maximum power point of a PV array. This method is derived by the well known incremental conductance method and the novelty consists in varying the duty cycle of the dc-dc switching converter used as MPPT tracker using a variable step size instead of a fixed step size. A practical way to determine the minimum and the maximum values of the variable step size is explained in detail. The laboratory results demonstrate the effectiveness of the proposed method both in terms of speed in MPP tracking and accuracy in the MPP individuation.

In the future Smart Cities: Coordination of micro Smart Grids in a Virtual Energy District

In the future Smart City, new information and communication technologies will enable a better management of the available resources. The Smart Grid infrastructure is emerging as a complex system where fine-grained monitoring and control of energy generating and/or consuming entities within the electricity network is possible. This will result to better approaches that will boost energy efficiency. To make real this vision, (open) platforms providing access to the smart meter data as well as potential management and value-added functionalities are needed. These will offer basic energy services that can be commonly used by application developers. In this context, this paper proposes a new market platform in order to coordinate the energy exchanges among several micro Smart Grids aggregated in a Virtual Energy District. Some numerical results in Matlab/Simulink environment are presented to validate the proposed platform.

A new method for SSSC optimal location to improve power system Available Transfer Capability

In recent years, an increased interest was devoted to the problem of flexible AC transmission system devices location. In literature, most of proposals consist in iterative analyses, exhaustively looking for the branch that maximizes or minimizes an objective, such as least transmission losses or best power transfer capability. In this paper, attention is particularly focused on the static synchronous series compensator and a method is proposed to determine the device best location that maximizes the power system available transfer capability measured as the maximum system load increase before any operating limit is reached. The proposed method always performs an exhaustive analysis although conducted by modelling the transmission network by means of the simplified DC load flow equations embedded within an opportune optimisation model. Tests carried on networks modelled also by means of the AC load flow representation have demonstrated the validity of the proposed DC load flow based method

Grid-interfacing active power filters to improve the power quality in a microgrid

This paper proposes the application of the strategy control approach used for the shunt active power filter previously proposed by the authors to the inverter interface of each single micro-sources present in a Microgrid. In particular the attention has been focused on the power quality and var supporting issues. The main advantage of the proposed strategy control approach lies on the fact that all sensitive loads connected to the Point of Common Coupling (PCC) are immunized from the power quality problems. Moreover, the proposed control approach requests only local information. The effectiveness of the proposed control strategy approach applied to a Microgrid is illustrated.

Management of storage systems in local electricity market to avoid renewable power curtailment in distribution network

The increase of small size generation systems may cause congestions, hitherto unexpected, on the distribution network. To reduce the impact of congestions, the use of storage systems is one of the main countermeasure. In the paper, a storage management strategy based on a local energy market is proposed, in order to maximize the utility of an users community in which local market takes place. The numerical results obtained and shown in the paper demonstrate the effectiveness of the proposed management strategy2.

An hybrid PV-wind supply system with D-Statcom interface for a water-lift station

In the last years the photovoltaic and wind power generation has been increased significantly. This paper proposes the use of a D-Statcom as inverter interface of each single micro-sources (PV and wind) present in the supply system for a water lift station situated in Marina of Strongoli (KR- Italy) for the reactive compensation to regulate PCC voltage. The power circuit topology and the network are modeled by using ATP/EMTP software. The description of power system model, of the strategy control, of the Phase Locked Loop, and of the measurement system, are derived and presented. Some numerical results are illustrated.

Iterative harmonic and interharmonic analysis in multiconverter industrial systems

The problem of analysing harmonic and interharmonic distortion in multiconverter industrial power systems is considered. An useful updating of the iterative harmonic analysis algorithm to include interharmonics, based on automated EMTP simulations of nonlinear loads, is presented and its capabilities are discussed, also in the perspective of utilisation in a distributed computing environment.

Reliability studies of a PV-WG hybrid system in presence of multi-micro storage systems

In the last years, distributed generation (DG) and microgrid (MG) technologies have been used to moderate the stress due to main stream utility grid electricity demand increase. The dispatch of renewable distributed energy sources at present is performed in such a way that, when implemented at very large scale, their intermittency can impact on the grids, what leads to concerns in terms of power quality and of reliability of supply. In this paper the attention is focused on MG reliability. On this subject the authors have proposed, in previous papers, opportune configuration schemes of MG constituted by a photovoltaic plant, a Wind plant and an Uninterruptible Power Supply. The goal of this paper is to evaluate the reliability improvements of load supply against network congestions adopting the proposed hybrid configurations in presence of storage systems for each energy source proposing an opportune operating strategy for the energy control system. In particular, the reliability estimation is performed in terms of the number of the critical loads interruptions and in particular of the charge state of storage systems, over a certain period of time by using the Monte Carlo simulation method.