scholarly journals The Comparative Analysis of Phase Shifting Transformers

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4347
Author(s):  
Paweł Albrechtowicz ◽  
Jerzy Szczepanik
Keyword(s):  
Power Systems ◽  
Simulation Model ◽  
Power Flow ◽  
Renewable Energy Sources ◽  
Real Life ◽  
Work Conditions ◽  
Phase Shifting ◽  
Matlab Simulation ◽  
The Real ◽  
High Flexibility

Phase shifting transformers (PSTs) are currently widely used in power systems to control power flow. In this manuscript, the results of the asymmetrical PST (APST) with the in-phase PST (called asymmetrical controllable PST-ACPST) were compared, allowing to control both longitudinal and quadrature voltage. The MATLAB simulation model of the ACPST was built to obtain influence of PST in selected models for selected parameters. Then the 30A laboratory PST device was built in the laboratory. The parameters of the MATLAB model were then adjusted to parameters of the real life PST model. This allowed verifying the results of the real life and computer simulations. Based on the ACPST simulation model, the APST model was built; for the given work conditions, the influence of both PSTs were compared. APST construction always resulted in higher output voltage than the input one. ACPST achieved the same power transfer for the lower output PST voltage, which is its main advantage. This dependency is a result of the greater ACPST angle compared to the classical APST. The ACPST also allowed adjusting longitudinal and quadrature voltages; therefore, this PST type can be installed in places where high flexibility is required, especially in systems with high renewable energy sources penetration.

scholarly journals Predicting AC Optimal Power Flows: Combining Deep Learning and Lagrangian Dual Methods

2020 ◽  
Vol 34 (01) ◽  
pp. 630-637 ◽  
Author(s):  
Ferdinando Fioretto ◽  
Terrence W.K. Mak ◽  
Pascal Van Hentenryck
Keyword(s):  
Deep Learning ◽  
Power Systems ◽  
Power Flow ◽  
Optimal Power Flow ◽  
Large Scale ◽  
Renewable Energy Sources ◽  
Electrical Power ◽  
Practical Applications ◽  
Fundamental Building Block ◽  
Optimal Power

The Optimal Power Flow (OPF) problem is a fundamental building block for the optimization of electrical power systems. It is nonlinear and nonconvex and computes the generator setpoints for power and voltage, given a set of load demands. It is often solved repeatedly under various conditions, either in real-time or in large-scale studies. This need is further exacerbated by the increasing stochasticity of power systems due to renewable energy sources in front and behind the meter. To address these challenges, this paper presents a deep learning approach to the OPF. The learning model exploits the information available in the similar states of the system (which is commonly available in practical applications), as well as a dual Lagrangian method to satisfy the physical and engineering constraints present in the OPF. The proposed model is evaluated on a large collection of realistic medium-sized power systems. The experimental results show that its predictions are highly accurate with average errors as low as 0.2%. Additionally, the proposed approach is shown to improve the accuracy of the widely adopted linear DC approximation by at least two orders of magnitude.

scholarly journals Dynamic Analysis for VSG-Based Power Flow Control Applied to DG Systems

2021 ◽  
Author(s):  
THIAGO FIGUEIREDO DO NASCIMENTO ◽  
ANDRES ORTIZ SALAZAR
Keyword(s):  
Power Systems ◽  
Dynamic Analysis ◽  
Power Flow ◽  
Control Strategies ◽  
Renewable Energy Sources ◽  
Dynamic Performance ◽  
Synchronous Generator ◽  
Power Flow Control ◽  
Grid Impedance ◽  
Impedance Parameters

The integration of distributed generation (DG) systems based on renewable energy sources (RES) by using power converters is an emerging technology in modern power systems. Among the control strategies applied to this new configuration, the virtual synchronous generator (VSG) approach has proven to be an attractive solution due providing suitable dynamic performance. Thus, this paper presents a dynamic analysis of gridtied converters controlled by using VSG concept. This analysis is based on a dynamic model that describes the DG power flow transient characteristics. Based on this model, the grid impedance parameters variation effects on the VSG controllers dynamic performance are discussed. Simulation results are presented to evaluate the effectiveness of the theoretical analysis performed.

scholarly journals Nanocrystalline and Silicon Steel Medium-Frequency Transformers Applied to DC-DC Converters: Analysis and Experimental Comparison

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2062 ◽  
Author(s):  
Dante Ruiz-Robles ◽  
Jorge Ortíz-Marín ◽  
Vicente Venegas-Rebollar ◽  
Edgar L. Moreno-Goytia ◽  
David Granados-Lieberman ◽  
...  
Keyword(s):  
Power Systems ◽  
Smart Grids ◽  
High Performance ◽  
Renewable Energy Sources ◽  
Real Life ◽  
Silicon Steel ◽  
Core Material ◽  
Experimental Comparison ◽  
Medium Frequency ◽  
Wind Power Systems

High performance, highly efficient DC-DC converters play a key role in improving the penetration of renewable energy sources in the context of smart grids in applications such as solid-state transformers, built-in power drives in electric vehicles and interfacing photovoltaic and wind-power systems. Advanced medium-frequency transformers (MFTs) are fundamental to enhance DC-DC converters and determining its behavior, therefore MFT design procedures have become increasingly important in this context. This paper investigates which type of core material, between nanocrystalline and silicon steel, has the best properties for designing MFTs for distinct applications. Unlike to other proposals, in this work, two 1 kVA-120 V/240 V-1 kHz lab MFT prototypes, with a different type of core material, are developed for the purpose of comparing its physical characteristics, behavior, and performance under real-life conditions. A final section, the experimental results show that the nanocrystalline MFT has greater power density and efficiency. The results of this work introduce nanocrystalline MFTs as an option in a wider range of applications in niches in which other materials are currently used.

scholarly journals High-Resolution PV Forecasting from Imperfect Data: A Graph-Based Solution

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5763
Author(s):  
Rafael E. Carrillo ◽  
Martin Leblanc ◽  
Baptiste Schubnel ◽  
Renaud Langou ◽  
Cyril Topfel ◽  
...  
Keyword(s):  
High Resolution ◽  
Power Systems ◽  
Signal Reconstruction ◽  
Real Life ◽  
Congestion Management ◽  
Ar Model ◽  
Weather Data ◽  
The Real ◽  
Pv Systems ◽  
Imperfect Data

Operating power systems with large amounts of renewables requires predicting future photovoltaic (PV) production with fine temporal and spatial resolution. State-of-the-art techniques combine numerical weather predictions with statistical post-processing, but their resolution is too coarse for applications such as local congestion management. In this paper we introduce computing methods for multi-site PV forecasting, which exploit the intuition that PV systems provide a dense network of simple weather stations. These methods rely entirely on production data and address the real-life challenges that come with them, such as noise and gaps. Our approach builds on graph signal processing for signal reconstruction and for forecasting with a linear, spatio-temporal autoregressive (ST-AR) model. It also introduces a data-driven clear-sky production estimation for normalization. The proposed framework was evaluated over one year on both 303 real PV systems under commercial monitoring across Switzerland, and 1000 simulated ones based on high-resolution weather data. The results demonstrate the performance and robustness of the approach: with gaps of four hours on average in the input data, the average daytime NRMSE over a six-hour forecasting horizon (in 15 min steps) and over all systems is 13.8% and 9% for the real and synthetic data sets, respectively.

scholarly journals Load restoration methodology considering renewable energies and combined heat and power systems

2018 ◽  
Vol 7 (2.6) ◽  
pp. 130 ◽  
Author(s):  
Hayder O. Alwan ◽  
Noor M. Farhan
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Flow ◽  
Renewable Energy Sources ◽  
Control Variable ◽  
Combined Heat And Power ◽  
Renewable Energies ◽  
Economic Consequences ◽  
Interconnected Power System ◽  
Power System Restoration

Outages and faults cause problems in interconnected power system with huge economic consequences in modern societies. In the power system blackouts, black start resources such as micro combined heat and power (CHP) systems and renewable energies, due to their self-start ability, are one of the solutions to restore power system as quickly as possible. In this paper, we propose a model for power system restoration considering CHP systems and renewable energy sources as being available in blackout states. We define a control variable representing a level of balance between the distance and importance of loads according to the importance and urgency of the affected customer. Dynamic power flow is considered in order to find feasible sequence and combination of loads for load restoration.

scholarly journals Testing Smart Grid Scenarios with Small Volume Testbed and Flexible Power Inverter

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 428
Author(s):  
Milosz Krysik ◽  
Krzysztof Piotrowski ◽  
Krzysztof Turchan
Keyword(s):  
Smart Grid ◽  
Power Flow ◽  
Small Volume ◽  
Power Converters ◽  
Renewable Energy Sources ◽  
Real Life ◽  
Energy Sources ◽  
Huge Number ◽  
Islanded Mode ◽  
Test Scenarios

The growing penetration of Renewable Energy Sources (RES) due to the transition to future smart grid requires a huge number of power converters that participate in the power flow. Each of these devices needs the use of a complex control and communication system, thus a platform for testing real-life scenarios is necessary. Several test techniques have been so far proposed that are subject to a trade-off between cost, test coverage, and test fidelity. This paper presents an approach for testing microgrids, by developing an emulator, with emphasis on the micro-inverter unit and the possibility of flexible configuration for different grid topologies. In contrast to other approaches, our testbed is characterized by small volume and significantly scaled-down voltages for safety purposes. The examination is concentrated specifically on the inverter behavior. The test scenarios include behaviors in case of load changes, transition between grid-tied and islanded mode, connection and removal of subsequent inverters, and prioritization of inverters.

Performance Characterization of the Novel Topology for High-Frequency Isolation Bi-Directional DC/DC Converter

2013 ◽  
Vol 273 ◽  
pp. 305-309 ◽  
Author(s):  
Peng Hui Jing ◽  
Cong Wang ◽  
Jun Wang ◽  
Feng Zhao
Keyword(s):  
High Frequency ◽  
Power Flow ◽  
Control Strategies ◽  
High Reliability ◽  
Input Voltage ◽  
Phase Shifting ◽  
Matlab Simulation ◽  
High Input ◽  
The Cost ◽  
Bidirectional Power Flow

A novel topology of high-frequency isolation bi-directional DC/DC converter used in high-Input low-output system was proposed, which has not only the advantages, such as enabling bidirectional power flow, ease of realizing soft-switching control, galvanic isolation, high reliability and so on, but also can be used in high-input voltage application and apparently decreases the stress of the switches, which reduces the cost of the converter, improves power density and the efficiency of the converter. According to the different work condition, two control strategies are analyzed in this paper: the traditional phase shifting control (TPC) and PWM plus phase shifting control (PPC), which further improves the overall efficiency of the converter. The MATLAB simulation has been done to verify the feasibility of the proposed DC/DC converter and accuracy of the criterion.

scholarly journals Modeling and real time digital simulation of microgrids for campuses Malta and Jordan based on multiple distributed energy resources

2021 ◽  
Vol 21 (2) ◽  
pp. 657
Author(s):  
Sidahmed Khiat ◽  
Abdelkader Chaker ◽  
Lazaros Zacharia ◽  
Ahmed Onen
Keyword(s):  
Energy Storage ◽  
Real Time ◽  
Power Flow ◽  
Renewable Energy Sources ◽  
Digital Simulation ◽  
Storage System ◽  
Energy Storage System ◽  
Valuable Insight ◽  
Test Bed ◽  
The Real

<p>This paper presents the modeling and real-time digital simulation of two microgrids: the malta college of arts, science and technology (MCAST) and the german jordan university (GJU). The aim is to provide an overview of future microgrid situation and capabilities with the benefits of integrating renewable energy sources (RES), such as photovoltaic panels, diesel generators and energy storage systems for projects on both campuses. The significance of this work starts with the fact that real measurements were used from the two pilots, obtained by measuring the real physical systems. These measures were used to plan different solutions regarding RES and energy storage system (ESS) topologies and sizes. Also, the demand curves for the real microgrids of MCAST and GJU have been parameterized, which may serve as a test bed for other studies in this area. Based on actual data collected from the two pilots, a real-time digital simulation is performed using an RT-LAB platform. The results obtained by this tool allow the microgrid manager to have a very accurate vision of the facility operation, in terms of power flow and default responses.  Several scenarios are studied, extracting valuable insight for implementing both projects in the future. Eventually, the proposed models would be a blueprint for training and research purposes in the microgrid field.</p>

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