scholarly journals Three-Port Series-Resonant DC/DC Converter for Automotive Charging Applications

Electronics ◽  
2021 ◽  
Vol 10 (20) ◽  
pp. 2543
Author(s):  
Jannik Schäfer ◽  
Johann Walter Kolar
Keyword(s):  
Power Density ◽  
Power Flow ◽  
Low Voltage ◽  
Circuit Complexity ◽  
Operating Conditions ◽  
Modulation Scheme ◽  
Distribution Grid ◽  
Arbitrary Power ◽  
Series Resonant ◽  
Electrical Loads

In the energy distribution grid of electric vehicles (EVs), multiple different voltage potentials need to be interconnected, to allow arbitrary power flow between the various energy sources and the different electrical loads. However, between the different potentials, galvanic isolation is absolutely necessary, either due to safety reasons and/or due to different grounding schemes. This paper presents an isolated three-port DC/DC converter topology, which, in combination with an upstream PFC rectifier, can be used as combined EV charger for interconnecting the single-phase AC mains, the high-voltage (HV) battery and the low-voltage (LV) bus in EVs. The proposed topology comprises two synergetically controlled and magnetically coupled converter parts, namely, a series-resonant converter between the PFC-sided DC-link capacitor and the HV battery, as well as a phase-shifted full-bridge circuit equivalent in the LV port, and is mainly characterized by simplicity in terms of control and circuit complexity. For this converter, a simple soft switching modulation scheme is proposed and comprehensively analyzed, in consideration of all parasitic components of a real converter implementation. Based on this analysis, the design of a 3.6kW, 500V/ 500V/ 15V prototype is discussed, striving for the highest possible power density and as low as possible manufacturing costs, by using PCB-integrated windings for all magnetic components. The hardware demonstrator achieves a measured full-load efficiency in charge mode of 96.5% for nominal operating conditions and a power density of 16.4kW/L.

scholarly journals A Unified Controller for Multi-State Operation of the Bi-Directional Buck–Boost DC-DC Converter

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7921
Author(s):  
Gabriel R. Broday ◽  
Gilney Damm ◽  
William Pasillas-Lépine ◽  
Luiz A. C. Lopes
Keyword(s):  
Feedback Linearization ◽  
Power Flow ◽  
Negative Impact ◽  
Input Voltage ◽  
Operating Conditions ◽  
Modulation Scheme ◽  
Control Loops ◽  
Variable Control ◽  
Wide Range ◽  
The Right

DC grid interfaces for supercapacitors (SCs) are expected to operate with a wide range of input voltages with fast dynamics. The class-C DC-DC converter is commonly used in this application because of its simplicity. However, it does not work if the output voltage (V2) becomes smaller than the input voltage (V1). The non-isolated bi-directional Buck–Boost DC-DC converter does not have this limitation. Its two half-bridges provide a means for controlling the power flow operating in the conventional dual-state mode, as well as multi-state, tri, and quad modes. These can be used for mitigating issues such as the Right Half Plane (RHP) zero that has a negative impact on the dynamic response of the system. Multi-state operation typically requires multi-variable control, which is not easy to realize with conventional PI-type controllers. This paper proposes a unified controller for multi-state operation. It employs a carrier-based modulation scheme with three modulation signals that allows the converter to operate in all four possible states and eight different modes of operation. A mathematical model is developed for devising a multi-variable control scheme using feedback linearization. This allows the design of control loops with simple PI controllers that can be used for all multi-state modes under a wide range of operating conditions with the same performance. The proposed scheme is verified by means of simulations.

scholarly journals Integrated Techno-Economic Power System Planning of Transmission and Distribution Grids

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2091 ◽  
Author(s):  
Ulf Philipp Müller ◽  
Birgit Schachler ◽  
Malte Scharf ◽  
Wolf-Dieter Bunke ◽  
Stephan Günther ◽  
...  
Keyword(s):  
Power System ◽  
High Voltage ◽  
Power Flow ◽  
Optimal Power Flow ◽  
Low Voltage ◽  
Distribution Grid ◽  
Power System Planning ◽  
System Planning ◽  
Transmission And Distribution ◽  
And Storage

The energy transition towards renewable and more distributed power production triggers the need for grid and storage expansion on all voltage levels. Today’s power system planning focuses on certain voltage levels or spatial resolutions. In this work we present an open source software tool eGo which is able to optimize grid and storage expansion throughout all voltage levels in a developed top-down approach. Operation and investment costs are minimized by applying a multi-period linear optimal power flow considering the grid infrastructure of the extra-high and high-voltage (380 to 110 kV) level. Hence, the common differentiation of transmission and distribution grid is partly dissolved, integrating the high-voltage level into the optimization problem. Consecutively, optimized curtailment and storage units are allocated in the medium voltage grid in order to lower medium and low voltage grid expansion needs, that are consequently determined. Here, heuristic optimization methods using the non-linear power flow were developed. Applying the tool on future scenarios we derived cost-efficient grid and storage expansion for all voltage levels in Germany. Due to the integrated approach, storage expansion and curtailment can significantly lower grid expansion costs in medium and low voltage grids and at the same time serve the optimal functioning of the overall system. Nevertheless, the cost-reducing effect for the whole of Germany was marginal. Instead, the consideration of realistic, spatially differentiated time series led to substantial overall savings.

scholarly journals Integration of Electric Vehicles in Low-Voltage Distribution Networks Considering Voltage Management

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4125
Author(s):  
Miguel Carrión ◽  
Rafael Zárate-Miñano ◽  
Ruth Domínguez
Keyword(s):  
Power Systems ◽  
Electric Vehicles ◽  
Power Flow ◽  
Optimal Power Flow ◽  
Low Voltage ◽  
Distribution Network ◽  
Planning Horizon ◽  
Distribution Networks ◽  
Mixed Integer ◽  
Distribution Grid

The expected growth of the number of electric vehicles can be challenging for planning and operating power systems. In this sense, distribution networks are considered the Achilles’ heel of the process of adapting current power systems for a high presence of electric vehicles. This paper aims at deciding the maximum number of three-phase high-power charging points that can be installed in a low-voltage residential distribution grid. In order to increase the number of installed charging points, a mixed-integer formulation is proposed to model the provision of decentralized voltage support by electric vehicle chargers. This formulation is afterwards integrated into a modified AC optimal power flow formulation to characterize the steady-state operation of the distribution network during a given planning horizon. The performance of the proposed formulations have been tested in a case study based on the distribution network of La Graciosa island in Spain.

scholarly journals Integrated techno-economic power system planning of transmission and distribution grids

2019 ◽  
Author(s):  
Ulf Philipp Müller ◽  
Birgit Schachler ◽  
Malte Scharf ◽  
Wolf-Dieter Bunke ◽  
Stephan Günther ◽  
...  
Keyword(s):  
Power System ◽  
High Voltage ◽  
Power Flow ◽  
Optimal Power Flow ◽  
Low Voltage ◽  
Distribution Grid ◽  
Power System Planning ◽  
System Planning ◽  
Transmission And Distribution ◽  
And Storage

The energy transition towards renewable and more decentral power production triggers the need for grid and storage expansion on all voltage levels. Today's power system planning focuses on certain voltage levels or spatial resolutions. In this work we present an open source software tool eGo which is able to optimize grid and storage expansion throughout all voltage levels in a developed top-down approach. System costs are minimized by applying a linear optimal power flow considering the grid infrastructure of the extra-high and high-voltage (380 to 110 kV) level. Hence, the common differentiation of transmission and distribution grid is partly dissolved, integrating the high-voltage level into the optimization problem. Consecutively, optimized curtailment and storage units are allocated in the medium voltage grid in order to lower medium and low voltage grid expansion needs, that are consequently determined. Here, heuristic optimization methods using the non-linear power flow were developed. Applying the tool on future scenarios we derived cost-efficient grid and storage expansion for all voltage levels in Germany. Due to the integrated approach storage expansion and curtailment can significantly lower grid expansion costs in medium and low voltage grids and at the same time serve the optimal functioning of the overall system. Nevertheless, the cost-reducing effect for the whole of Germany was marginal. Instead, the consideration of realistic, spatially differentiated time series lead to substantial overall savings.

scholarly journals A Phase Generation Shifting Algorithm for Prosumer Surplus Management in Microgrids using Inverter Automated Control

2021 ◽  
Author(s):  
Ovidiu Ivanov ◽  
Bogdan Constantin Neagu ◽  
Mihai Gavrilaș ◽  
Gheorghe Grigoraș
Keyword(s):  
Power Flow ◽  
Low Voltage ◽  
Distribution Networks ◽  
Green Energy ◽  
Operating Conditions ◽  
Local Market ◽  
Main Concern ◽  
Automated Control ◽  
Real Distribution ◽  
Active Power Losses

Four-wire low voltage microgrids supply one-phase consumers with continuously changing electricity demand. For addressing climate change concerns, governments implemented incentive schemes for residential consumers, encouraging the installation of home PV panels for covering self-consumption needs. In the absence of sufficient storage capacities, the surplus is sold back by these entities, called prosumers, to the grid operator or in local markets, to other consumers. While these initiatives encourage the proliferation of green energy resources, and ample research is dedicated to local market designs for prosumer-consumer trading, the main concern of distribution network operators is the influence of power flows generated by prosumer surplus injection on the operating states of microgrids. The change in power flow amount and direction can greatly influence the economic and technical operating conditions of radial grids. This paper proposes a metaheuristic algorithm for prosumer surplus management that optimizes the power surplus injections using the automated control of three-phase inverters, with the aim of improving the active power losses and balancing the phase voltage profiles. A case study is performed on two real distribution networks with distinct layouts and load profiles and the algorithm shows its efficiency in both scenarios.

scholarly journals Storage Placement and Sizing in a Distribution Grid with High PV Generation

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 303
Author(s):  
Benjamin Matthiss ◽  
Arghavan Momenifarahani ◽  
Jann Binder
Keyword(s):  
Renewable Resources ◽  
Power Flow ◽  
Low Voltage ◽  
Optimal Placement ◽  
Voltage Distribution ◽  
Distribution Grid ◽  
Reinforcement Measures ◽  
Pv Generation ◽  
Pv Penetration ◽  
Grid Reinforcement

With the increasing penetration of renewable resources into the low-voltage distribution grid, the demand for alternatives to grid reinforcement measures has risen. One possible solution is the use of battery systems to balance the power flow at crucial locations in the grid. Hereby, the optimal location and size of the system have to be determined in regard to investment and its effect on grid stability. In this paper, the optimal placement and sizing of battery storage systems for grid stabilization in a small low-voltage distribution grid in southern Germany with high PV penetration are investigated and compared to a grid heuristic reinforcement strategy.

scholarly journals Theoretical and Experimental Study to Determine Voltage Violation, Reverse Electric Current and Losses in Prosumers Connected to Low-Voltage Power Grid

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4568 ◽  
Author(s):  
Torres ◽  
Negreiros ◽  
Tiba
Keyword(s):  
Distributed Generation ◽  
Challenging Behavior ◽  
Power Flow ◽  
Low Voltage ◽  
Electricity Consumption ◽  
Reverse Current ◽  
Operating Conditions ◽  
Photovoltaic System ◽  
Electricity Cost ◽  
The Impact

The impact of PV generation distributed in a low voltage transmission line depends on many factors: The distribution lines and PV generators characteristics, its location, operational control, local meteorological conditions, electricity consumption profile, and the electricity cost variation. An atypical and challenging behavior of photovoltaic distributed generation (DG) insertion in consumer units (CUs), implies in some circumstances, as the reverse directionality of the power flow between the load equipped with a photovoltaic system generator and the electrical grid, when a CU contains a distributed generation and low power consumption, the power flow will be directed to the power electric grid. In this work, the modeling of a low-voltage real feeder was performed, setting the variables of the system under real operating conditions. As result, voltage levels variability throughout the feeder, the electrical losses, and the asymmetry between the phases were observed. Through simulation scenarios, the occurrence of voltage increase under different penetration scenarios of distributed generation was verified and there was a 10% increase in reference voltage as well as the occurrence of higher electrical losses by reverse current, reaching 1200% more with a DG penetration, in the massive presence of the photovoltaic generator. The mitigatory action used in this work was able to attenuate the negative impacts to the feeder circuit, ensuring the integrity grid and the consumer unit.

scholarly journals A Phase Generation Shifting Algorithm for Prosumer Surplus Management in Microgrids Using Inverter Automated Control

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2740
Author(s):  
Ovidiu Ivanov ◽  
Bogdan-Constantin Neagu ◽  
Mihai Gavrilas ◽  
Gheorghe Grigoras
Keyword(s):  
Power Flow ◽  
Low Voltage ◽  
Distribution Networks ◽  
Significant Loss ◽  
Green Energy ◽  
Operating Conditions ◽  
Local Market ◽  
Main Concern ◽  
Automated Control ◽  
Three Phase

Four-wire low-voltage microgrids supply one-phase consumers with electricity, responding to a continuously changing demand. For addressing climate change concerns, national governments have implemented incentive schemes for residential consumers, encouraging the installation of home PV panels for covering self-consumption needs. In the absence of adequate storage capacities, the surplus is sold back by these entities, called prosumers, to the grid operator or, in local markets, to other consumers. While these initiatives encourage the proliferation of green energy resources, and ample research is dedicated to local market designs for prosumer–consumer trading, the main concern of distribution network operators is the influence of power flows generated by prosumers’ surplus injection on the operating states of microgrids. The change in power flow amount and direction can greatly influence the economic and technical operating conditions of radial grids. This paper proposes a metaheuristic algorithm for prosumer surplus management that optimizes the power surplus injections using the automated control of three-phase inverters, with the aim of reducing the active power losses over a typical day of operation. A case study was performed on two real distribution networks with distinct layouts and load profiles, and the algorithm resulted efficient in both scenarios. By optimally distributing the prosumer generation surplus on the three phases of the network, significant loss reductions were obtained, with the best results when the generated power was injected in an unbalanced, three-phase flow.

scholarly journals Model-Free Power Control for Low-Voltage AC Dispatchable Microgrids with Multiple Points of Connection

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6390
Author(s):  
Geovane dos Reis ◽  
Eduardo Liberado ◽  
Fernando Marafão ◽  
Clodualdo Sousa ◽  
Waner Silva ◽  
...  
Keyword(s):  
Power Flow ◽  
Low Voltage ◽  
Hierarchical Control ◽  
Control Technique ◽  
Distribution Grid ◽  
Multiple Points ◽  
Model Free ◽  
Narrow Bandwidth ◽  
Three Phase ◽  
Power Loss Reduction

This paper proposes a modified version of the power-based control (MPBC) applied to microgrids (µGs) with multiple points of connection (i.e., utility grid itself or any other neighboring µG). Using the MPBC, single-phase distributed energy resources (DERs) arbitrarily connected between the phases share the amounts of balanced power, while the unbalanced and homopolar power are steered only to the line-to-neutral inverters. The control technique is based on a three-level hierarchical control using narrow bandwidth, low data rate communication that properly coordinates the DERs connected to three-phase four-wire µGs. The MPBC allows the DERs to steer power flow at any of the multiple points of common coupling of a multi-PCC dispatchable µG. The modified control proposed herein is evaluated through simulation results using MATLAB/SIMULINK considering a real urban distribution grid with typical operational elements and conditions. When compared to the original power-based control (PBC), results show that a meshed µG may reach power benchmarks with accommodation time 80% lower when applying MPBC. Moreover, it may also lead to significant power loss reduction (about of 5%) in some studied cases.

scholarly journals Stratified Control Applied to a Three-Phase Unbalanced Low Voltage Distribution Grid in a Local Peer-to-Peer Energy Community

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3290
Author(s):  
Bharath Varsh Rao ◽  
Mark Stefan ◽  
Roman Schwalbe ◽  
Roman Karl ◽  
Friederich Kupzog ◽  
...  
Keyword(s):  
Power Flow ◽  
Optimal Power Flow ◽  
Low Voltage ◽  
Local Energy ◽  
Voltage Distribution ◽  
Distribution Grid ◽  
Optimal Power ◽  
Three Phase ◽  
Control Scheme ◽  
Energy Community

This paper presents control relationships between the low voltage distribution grid and flexibilities in a peer-to-peer local energy community using a stratified control strategy. With the increase in a diverse set of distributed energy resources and the next generation of loads such as electric storage, vehicles and heat pumps, it is paramount to maintain them optimally to guarantee grid security and supply continuity. Local energy communities are being introduced and gaining traction in recent years to drive the local production, distribution, consumption and trading of energy. The control scheme presented in this paper involves a stratified controller with grid and flexibility layers. The grid controller consists of a three-phase unbalanced optimal power flow using the holomorphic embedding load flow method wrapped around a genetic algorithm and various flexibility controllers, using three-phase unbalanced model predictive control. The control scheme generates active and reactive power set-points at points of common couplings where flexibilities are connected. The grid controller’s optimal power flow can introduce additional grid support functionalities to further increase grid stability. Flexibility controllers are recommended to actively track the obtained set-points from the grid controller, to ensure system-level optimization. Blockchain enables this control scheme by providing appropriate data exchange between the layers. This scheme is applied to a real low voltage rural grid in Austria, and the result analysis is presented.

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