A Framework for Flexible Loads Aggregation

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Coordination of specialised energy aggregators for balancing service provision

In the present context of evolution of the power and energy systems, more flexibility is required on the generation and demand side, to cope with the increasing uncertainty mostly introduced by variable renewable energy resources. This paper presents a conceptual framework that encompasses different types of aggregators, including local network aggregators, demand-side general aggregators, specialised energy aggregators (SEAs), and energy community aggregators. In this framework, this paper focuses on the coordination of SEAs to provide balancing services to the system operator. Each SEA manages a specific type of load, so that these loads can be managed by exploiting their control capabilities in a detailed way considering response time, dynamics and available flexibility. Moreover, the presence of the SEAs increases the privacy protection of the users, as only the information on a specific type of user's load is sent to the SEA. The SEA Coordinator interacts with the Balancing Service Provider aimed at procuring frequency containment, frequency restoration and replacement reserve services. This paper contains the SEA Coordinator formulation, information exchange and control operation strategies. Case study applications are presented by using SEAs for three specific types of loads (thermoelectric refrigerator, water booster pressure systems and electric vehicle charging stations). The results show how the control algorithm of the SEA Coordinator is effective in providing balancing services at different timings with the different types of loads. Various scenarios are considered, comparing an ideal situation without command propagation delays with realistic situations that take into account the command propagation delays

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

A Real-Time Based Platform for Integrating Power-to-Gas in Electrical Distribution Grids

The high share of renewable energy sources in electrical distribution is posing several challenges in guaranteeing the proper distribution system operation. In fact, different issues can arise, affecting either the network constraints, or creating the inversion of the power flow. The latter problem (known as reverse power flow) impacts both on the effectiveness of the protection systems of the distribution grids and on the operation of the transmission system as well (due to its non-controllability). Currently, this issue is solved by cutting the renewable generation; however, this is not acceptable anymore in a vision based on the exploitation of green energy sources. In this article, the power-to-gas technology is considered as possible response on this problem. The technology has been integrated in a new distribution system tool based on the exploitation on a real-time simulation platform. The case study shows good results in terms of network performance (in terms of losses, reverse power flow, self-sufficienty and self-consumption)

Power-to-Gas in gas and electricity distribution systems: A comparison of different modeling approaches

Power-to-Gas (P2G) has been one of the most frequently discussed technologies in the last few years. Thanks to its high flexibility, it can offer services to power systems, thereby fostering Variable Renewable Energy Sources (VRES) and the electricity demand match, mitigating the issues related to VRES overproduction. The analysis of P2G systems used at the distribution level has only been dealt with in a few studies: however, at this level, critical operation conditions can easily arise, in both the electrical infrastructure and in the gas infrastructure. The choice of appropriate modeling approaches for a P2G plant, as well as for the electricity and gas distribution grids is necessary to avoid overestimating or underestimating the potential flexibility that P2G plants connected to distribution networks can offer. The study presents a methodological analysis on the impact of different simulation approaches when P2G is installed at a distribution system level. The aim of this paper has been to understand the impact of different modeling approaches in order to determine whether, and under what conditions, they could be adopted. An illustrative case study has been developed to perform this analysis. The results show that the flexibility of the P2G technology can also be used at the distribution level; nevertheless, a correct modeling approach is necessary to properly evaluate the potential of this solution. The placement of P2G systems within the electricity network can affect the performance of the plant to a great extent. Therefore, it is necessary to use a model that takes into account the topology and energy flows of the electrical network. It was found, in the analyzed case study, that the use of an inappropriate electricity network model can lead, depending on the conditions, to either an overestimation or an underestimation (of 50 % and 40 %, respectively) of the ability of P2G plants to absorb VRES over-generation. The accuracy of the gas network and of the P2G plant models also plays an important role. In conditions of low gas consumption, it is necessary to consider the gas flows and the line-pack potential of the gas network, as well as the interactions between the components of the P2G plant in order to avoid underestimating the flexibility of the entire system. In the analyzed case study, the use of a simplified model of the gas network led to an underestimation of the accumulation potential of the overgenerations of VRES of about 30 %, while the use of a simplified model for the simulation of P2G plants led to a 10 % underestimation of the storage potential

Cardiac myosin activation with omecamtiv mecarbil in systolic heart failure

BACKGROUND The selective cardiac myosin activator omecamtiv mecarbil has been shown to improve cardiac function in patients with heart failure with a reduced ejection fraction. Its effect on cardiovascular outcomes is unknown. METHODS We randomly assigned 8256 patients (inpatients and outpatients) with symptomatic chronic heart failure and an ejection fraction of 35% or less to receive omecamtiv mecarbil (using pharmacokinetic-guided doses of 25 mg, 37.5 mg, or 50 mg twice daily) or placebo, in addition to standard heart-failure therapy. The primary outcome was a composite of a first heart-failure event (hospitalization or urgent visit for heart failure) or death from cardiovascular causes. RESULTS During a median of 21.8 months, a primary-outcome event occurred in 1523 of 4120 patients (37.0%) in the omecamtiv mecarbil group and in 1607 of 4112 patients (39.1%) in the placebo group (hazard ratio, 0.92; 95% confidence interval [CI], 0.86 to 0.99; P = 0.03). A total of 808 patients (19.6%) and 798 patients (19.4%), respectively, died from cardiovascular causes (hazard ratio, 1.01; 95% CI, 0.92 to 1.11). There was no significant difference between groups in the change from baseline on the Kansas City Cardiomyopathy Questionnaire total symptom score. At week 24, the change from baseline for the median N-terminal pro-B-type natriuretic peptide level was 10% lower in the omecamtiv mecarbil group than in the placebo group; the median cardiac troponin I level was 4 ng per liter higher. The frequency of cardiac ischemic and ventricular arrhythmia events was similar in the two groups. CONCLUSIONS Among patients with heart failure and a reduced ejection, those who received omecamtiv mecarbil had a lower incidence of a composite of a heart-failure event or death from cardiovascular causes than those who received placebo. (Funded by Amgen and others; GALACTIC-HF ClinicalTrials.gov number, NCT02929329; EudraCT number, 2016 -002299-28.)