scholarly journals Fault-Ride-Through Approach for Grid-Tied Smart Transformers without Local Energy Storage

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5622
Author(s):  
Justino Rodrigues ◽  
Carlos Moreira ◽  
João Peças Lopes
Keyword(s):  
Energy Storage ◽  
Renewable Energy Sources ◽  
Computational Simulation ◽  
Low Frequency ◽  
Voltage Sags ◽  
Distribution Grid ◽  
Power Electronic Converters ◽  
Dc Distribution ◽  
Fault Ride Through ◽  
Distribution Grids

The Smart Transformer (ST) is being envisioned as the possible backbone of future distribution grids given the enhanced controllability it provides. Moreover, the ST offers DC-link connectivity, making it an attractive solution for the deployment of hybrid AC/DC distribution grids which offer important advantages for the deployment of Renewable Energy Sources, Energy Storage Systems (ESSs) and Electric Vehicles. However, compared to traditional low-frequency magnetic transformers, the ST is inherently more vulnerable to fault disturbances which may force the ST to disconnect in order to protect its power electronic converters, posing important challenges to the hybrid AC/DC grid connected to it. This paper proposes a Fault-Ride-Through (FRT) strategy suited for grid-tied ST with no locally available ESS, which exploits a dump-load and the sensitivity of the hybrid AC/DC distribution grid’s power to voltage and frequency to provide enhanced control to the ST in order to handle AC-side voltage sags. The proposed FRT strategy can exploit all the hybrid AC/DC distribution grid (including the MV DC sub-network) and existing controllable DER resources, providing FRT against balanced and unbalanced faults in the upstream AC grid. The proposed strategy is demonstrated in this paper through computational simulation.

scholarly journals A Two-Step State Estimation Algorithm for Hybrid AC-DC Distribution Grids

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1967
Author(s):  
Gaurav Kumar Roy ◽  
Marco Pau ◽  
Ferdinanda Ponci ◽  
Antonello Monti
Keyword(s):  
State Estimation ◽  
Distribution System ◽  
Renewable Energy Sources ◽  
Estimation Algorithm ◽  
The State ◽  
Second Step ◽  
Distribution Grid ◽  
Dc Distribution ◽  
Attractive Option ◽  
Distribution Grids

Direct Current (DC) grids are considered an attractive option for integrating high shares of renewable energy sources in the electrical distribution grid. Hence, in the future, Alternating Current (AC) and DC systems could be interconnected to form hybrid AC-DC distribution grids. This paper presents a two-step state estimation formulation for the monitoring of hybrid AC-DC grids. In the first step, state estimation is executed independently for the AC and DC areas of the distribution system. The second step refines the estimation results by exchanging boundary quantities at the AC-DC converters. To this purpose, the modulation index and phase angle control of the AC-DC converters are integrated into the second step of the proposed state estimation formulation. This allows providing additional inputs to the state estimation algorithm, which eventually leads to improve the accuracy of the state estimation results. Simulations on a sample AC-DC distribution grid are performed to highlight the benefits resulting from the integration of these converter control parameters for the estimation of both the AC and DC grid quantities.

scholarly journals Progresses in Analytical Design of Distribution Grids and Energy Storage

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4270
Author(s):  
Gianpiero Colangelo ◽  
Gianluigi Spirto ◽  
Marco Milanese ◽  
Arturo de Risi
Keyword(s):  
Renewable Energy ◽  
Power Flow ◽  
State Of The Art ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Distribution Grid ◽  
Mathematical Methods ◽  
Power Generators ◽  
Bidirectional Power Flow ◽  
Distribution Grids

In the last years, a change in the power generation paradigm has been promoted by the increasing use of renewable energy sources combined with the need to reduce CO2 emissions. Small and distributed power generators are preferred to the classical centralized and sizeable ones. Accordingly, this fact led to a new way to think and design distributions grids. One of the challenges is to handle bidirectional power flow at the distribution substations transformer from and to the national transportation grid. The aim of this paper is to review and analyze the different mathematical methods to design the architecture of a distribution grid and the state of the art of the technologies used to produce and eventually store or convert, in different energy carriers, electricity produced by renewable energy sources, coping with the aleatory of these sources.

scholarly journals An Overview of Bidirectional AC-DC Grid Connected Converter Topologies for Low Voltage Battery Integration

2018 ◽  
Vol 9 (3) ◽  
pp. 1223 ◽  
Author(s):  
Kaspars Kroics ◽  
Oleksandr Husev ◽  
Kostiantyn Tytelmaier ◽  
Janis Zakis ◽  
Oleksandr Veligorskyi
Keyword(s):  
Energy Storage ◽  
High Efficiency ◽  
Low Voltage ◽  
Renewable Energy Sources ◽  
Storage System ◽  
Distribution Grid ◽  
Battery Energy Storage ◽  
Battery Energy Storage Systems ◽  
Converter Topologies ◽  
Battery Energy

<p>Battery energy storage systems are becoming more and more popular solution in the household applications, especially, in combination with renewable energy sources. The bidirectional AC-DC power electronic converter have great impact to the overall efficiency, size, mass and reliability of the storage system. This paper reviews the literature that deals with high efficiency converter technologies for connecting low voltage battery energy storage to an AC distribution grid. Due to low voltage of the battery isolated bidirectional AC-DC converter or a dedicated topology of the non isolated converter is required. Review on single stage, two stage power converters and integrated solutions are done in the paper.</p>

scholarly journals Online Parameter Estimation for Fault Identification in Multi-Terminal DC Distribution Grids

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5630
Author(s):  
Ting Wang ◽  
Liliuyuan Liang ◽  
Xinrang Feng ◽  
Ferdinanda Ponci ◽  
Antonello Monti
Keyword(s):  
Fault Location ◽  
Short Circuit ◽  
Fault Identification ◽  
Generic Model ◽  
Distribution Grid ◽  
Accurate Identification ◽  
Power Sources ◽  
Dc Distribution ◽  
Time Simulation ◽  
Distribution Grids

Fast and accurate identification of short-circuit faults is important for post-fault service restoration and maintenance in DC distribution grids. Yet multiple power sources and complex system topologies complicate the fault identification in multi-terminal DC distribution grids. To address this challenge, this paper introduces an approach that achieves fast online identification of both the location and the severity of faults in multi-terminal DC distribution grids. First, a generic model describing the dynamic response of DC lines to both pole-to-ground and pole-to-pole faults with fault currents injected from both line ends is developed. On this basis, a Kalman filter is adopted to estimate both the fault location and resistance. In the real-time simulation of various fault scenarios in a three-terminal DC distribution grid model with Opal-RT platform, the proposed method is proved to be effective with a short response time of less than 1 ms.

scholarly journals Impact of Control Loops on the Passivity Properties of Grid-Forming Converters with Fault-Ride through Capability

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6036
Author(s):  
Mebtu Beza ◽  
Massimo Bongiorno ◽  
Anant Narula
Keyword(s):  
Renewable Energy Sources ◽  
Experimental Tests ◽  
Power Electronic ◽  
Power Electronic Converters ◽  
Input Admittance ◽  
Factors Affecting ◽  
Control Loops ◽  
Fault Ride Through ◽  
Main Factors ◽  
The Impact

Due to the increasing integration of renewable energy sources (RES) and a corresponding reduction of conventional generating units, there is nowadays a demand from the power-electronic converters to provide grid-forming properties through proper control of the converter systems. This paper aims to evaluate the impact of various control loops in a grid-forming control strategy equipped with a fault-ride through capability on the passivity properties of the converter system. Through the analysis of the frequency-dependent input admittance of the converter, the main factors affecting the passivity properties are identified. A simplified analytical model is derived in order to propose possible control modifications to enhance the system’s passivity at various frequencies of interest and the findings are validated through detailed time-domain simulations and experimental tests.

scholarly journals Improved Efficiency Management Strategy for Battery-Based Energy Storage Systems

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1459
Author(s):  
Emilio Arnieri ◽  
Luigi Boccia ◽  
Francesco Amoroso ◽  
Giandomenico Amendola ◽  
Gregorio Cappuccino
Keyword(s):  
Energy Storage ◽  
Management Strategy ◽  
Storage Systems ◽  
Renewable Energy Sources ◽  
Storage System ◽  
Management Strategies ◽  
Distribution Grid ◽  
Energy Storage Systems ◽  
Efficient Management ◽  
Efficiency Increase

Battery-based energy storage systems are forecasted to have a rapid diffusion in the next future, because they can support the diffusion of renewable energy sources and can offer interesting ancillary services for the distribution grid. Consequently, energy management strategies for batteries and inverters present in storage systems will play a fundamental role in order to guarantee effective energy transfer processes between storage systems and the grid. This paper proposes an efficient management strategy which allows maximizing the overall energy efficiency of grid-connected storage systems taking into account the actual relationship between the efficiency and the charging/discharging power of the storage system. The effectiveness of the strategy is as shown by analysis results, the proposed strategy can allow a remarkable efficiency increase compared with strategies which are not aimed at the efficiency optimization.

scholarly journals Definition of Key Indicators to Identify Optimal Distribution Grid Restoration Strategies

2020 ◽  
Vol 209 ◽  
pp. 01001
Author(s):  
Christoph Strunck ◽  
Christian Rehtanz
Keyword(s):  
Power Plants ◽  
Large Scale ◽  
Renewable Energy Sources ◽  
Weather Conditions ◽  
Energy System ◽  
Indicator System ◽  
Distribution Grid ◽  
Restoration Strategies ◽  
Key Indicators ◽  
Distribution Grids

Due to significant changes in the power energy system and extreme weather conditions as a result of the increasing impact of climate change, large scale blackouts become more likely. With the rising penetration of renewable energy sources in distribution grids and the shutdown of large conventional power plants, the system inertia and therefore the resilience is decreasing. This will have a significant influence on the provision of ancillary services in the future. Especially for grid restoration processes, new concepts are necessary to assure an optimal integration of the distributed energy resources to resupply a grid after a blackout. However, to identify and assess the capability of distribution grids to restore the grid operation to resupply their grid independently of the transmission system key indicators are necessary for an analysis. Hence, this paper introduces a key indicator system, which has the goal to address several challenges of a distribution grid restoration.

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