Search results for "AC power"
showing 10 items of 92 documents
An enhanced approach based on IEEE 1459 for the detection of disturbing loads in distorted and unbalanced three-phase power systems
2009
This paper presents an enhanced approach for the detection of disturbing loads in distorted and/or unbalanced three-phase power systems in both cases of three and four-wires. It is based on the IEEE Std. 1459-2000 effective apparent power resolution and it requires only the separation of the fundamental components of voltage and current from the remaining harmonic content. In the paper, the formulation of the novel approach is given and some simulation results are presented.
Disturbing loads identification in power systems: a single-point time-domain method based on IEEE 1459-2000
2009
This paper presents a single-point method for the identification of prevailing disturbing loads in power systems for both single-phase and three-phase applications downstream or upstream from the metering section. It is based on the simultaneous measurement of three nonactive power quantities, which are based on the IEEE Std. 1459-2000 approach. The proposed method is only based on the separation of the fundamental components from the harmonic content of voltage and current; thus, it does not require any spectral analysis of the voltages and current. In this paper, the formulation of the proposed method and its time-domain implementation are described; moreover, some simulation results are …
Mixed Harmonic Elimination Control for a Single-Phase 9 Level Grid-Connected Inverter
2018
The power quality requirements are increasingly stringent, due to the continuous growth of devices connected to the grid that introduce harmonics. These devices include DC to AC energy conversion systems, i.e. grid connected inverters. The design, control and operation of these systems must take into account the rules of interconnection to the electricity grid. To improve the quality of the output waveform of the grid-connected inverter, Multilevel Converters (MC) with selective harmonic elimination modulation technique can be used. This paper presents a single-phase nine level grid-connected inverter with DC/DC input stages. The obtained switching angles for THD minimization are independen…
A methodology for evaluation of operational zones for distributed generation based on DFIG
2017
This study developed a methodology to determine zones of acceptable voltage profiles for wind power generation connected to distribution systems. Three load profiles (residential, commercial and industrial) connected to the distribution network were analyzed considering the impact on voltage levels and steady-state stability for different wind speeds and wind generator control strategies. The wind generator model is based on doubly fed induction generator (DFIG) and were developed using Matlab/Simulink. The presented methodology can be used to map the impact on operation of different types of control, the time of day and the available wind speed and it is not limited only for DFIG. The resu…
Transitions from grid-connected to island operation of Smart Microgrids
2019
In this paper a control methodology is presented to perform a bumpless transition from the on-grid to the offgrid of a smart microgrid. The derived controller manages the internal production in order to get to zero the tie-line active and reactive power flows so that the opening of the tie line breaker does not produce significant perturbations. Experimental tests performed on the microgrid built at the Polytechnic University of Bari demonstrated the effectiveness of the proposed control strategy.
Transparency in transactive energy at distribution level
2017
A recent report from the German Energy Agency analyzes the possible introduction of the blockchain technology in energy transactions in power distribution. The issue deserves attention since the extensive digitalization of business models puts new challenges to utilities in the power sector. The German decision makers in the energy field claim that blockchain appears as a close perspective and, at the same time, the Gartner hypecycle puts this technology at the peak of inflated expectations in 2016. Diffuse perception however provides hints for further investigation on the topic. This paper provides insight into the problem of peer-to-peer energy exchange from a technical perspective, provi…
Effect of voltage deviations on power distribution losses in presence of DG technology
2015
Integration of distributed generation (DG) units in power distribution network has become increasingly attractive multi-faceted paradigm as economic and environmental factors drive new technologies to be more efficient and less polluting than their earlier counterparts. The installation of DGs impacts critically on the planning and operating characteristics of the distribution network. Type, location, number and capacity of DG are essential factors for studying the effect of DGs on the system behavior. In this paper the effect of DG on the power losses of a distribution network is investigated for different types of DG units. Also, the impact of DG on the voltage profile is demonstrated bef…
Exercise cardiac power and the risk of heart failure in men : A population-based follow-up study
2022
Background Little is known about exercise cardiac power (ECP), defined as the ratio of directly measured maximal oxygen uptake with peak systolic blood pressure during exercise on heart failure (HF) risk. We examined the association of ECP and the risk of HF. Methods This was a population-based cohort study of 2351 men from eastern Finland. The average time to follow-up was 25 years. Participants participated at baseline in an exercise stress test. A total of 313 cases of HF occurred. Results Men with low ECP (13.92 mL/mmHg, highest quartile), after adjusting for age. Low ECP was associated with a 1.96-fold risk (95%CI: 1.38 − 2.78, p < 0.001) of HF after additional adjustment for conventio…
Fuzzy logic controller and game theory based distributed energy resources allocation
2020
Energy management and demand control through conventional energy generation sources are challenging for energy providers. Distributed energy resources (DERs) allocation near load centers may provide a suitable solution. The main contribution of the paper improves the voltage profile and reduce the active and reactive power losses in the distribution network. DERs are integrated with IEEE 33 bus system using fuzzy logic controller (FLC) and game theory for two different cases with unity and 0.9 power factor (PF) and compares with conventional methods of integration (i.e., modified novel method, power loss sensitivity method, voltage sensitivity analysis method). The capacity of DERs is optim…
IEEE Std. 1459 power quantities ratio approaches for simplified harmonic emissions assessment
2018
The paper investigates the suitability of using power ratio parameters for harmonic emissions assessment at the point of common coupling (PCC). The study is carried out starting from the IEEE Std. 1459-2010 apparent power decomposition, where power factors are defined for evaluating line utilization and harmonic pollution levels. In addition, the study investigates the behavior of new parameters, which are expressed in terms of ratio between IEEE Std. 1459-2010 power quantities. The study is carried out for both single-phase and three-phase case, also considering the presence of capacitors. ? 2018 IEEE.