Impact of unbalanced electric vehicle charging on low-voltage grids

Helm, Sebastian; Hauer, Ines; Wolter, Martin; Wenge, Christoph; Balischewski, Stephan; Komarnicki, Przemysław

doi:10.1109/isgt-europe47291.2020.9248754

Cited by 15 publications

(11 citation statements)

References 12 publications

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“…Such power quality issues that relate to harmonic frequencies are not addressed here. Furthermore, voltage imbalance can be an issue in LV grids due to an uneven assignment of single phase consumers or generators [11]. Although our controller does not actively balance the voltage, the three-phase monitoring included in the operation management allows to detect voltage imbalances.…”

Section: Grid Topology and Operational Constraintsmentioning

confidence: 99%

“…To avoid the drawbacks of a feedforward optimization, we utilize an online feedback-based algorithm to solve (11). Within one control cycle, it computes an incremental update towards the optimum instead of solving (11) until convergence.…”

Section: Online Feedback-based Optimization Algorithmmentioning

confidence: 99%

“…Our algorithm is based on the projected gradient method proposed in [4]. It aims to solve the dual problem associated with the optimization problem (11), where DER power level constraints (3)-( 4) are enforced by projection. Thus, Lagrange multipliers λ − , λ + ∈ R N and μ ∈ R |ε| are introduced for the lower and upper voltage and current constraints (1) and (2), respectively, to formulate the (partial) Lagrangian…”

Section: Online Feedback-based Optimization Algorithmmentioning

confidence: 99%

“…Now, we intend to evaluate how close the OnOpt-SE gets to the MP result in terms of the overall utility, i.e. the target function value tot according to (11), The MP value is considered as the "gold standard" that could theoretically be achieved.…”

Section: Overall Utilitymentioning

confidence: 99%

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Utility-based operation management for low voltage distribution grids using online optimization

Ipach

Fisser

Becker

et al. 2021

Elektrotech. Inftech.

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We present an operation management controller for low voltage (LV) grids that coordinates a multitude of distributed energy resources (DER) in real time to maximize the utilization of renewable energy production. It utilizes an LTE radio network that connects the DERs to the distribution system operator. In our approach, utility functions are assigned to the DERs, and the utility maximization is formulated as an optimization problem. The optimization problem is solved by an iterative algorithm that performs incremental updates of the DER power set values to achieve the optimum. In order to take the state of the grid in the optimization process into account, the state of the grid is estimated. During the simulation of a use case, we demonstrate the applicability and identify the benefits of our approach compared to an established optimal power flow (OPF) method. Particular emphasis is put on evaluating the communication delay and feasibility of the required communication network, as the iterative approach leads to a high communication load.

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Section: Grid Topology and Operational Constraintsmentioning

confidence: 99%

Section: Online Feedback-based Optimization Algorithmmentioning

confidence: 99%

Section: Online Feedback-based Optimization Algorithmmentioning

confidence: 99%

Section: Overall Utilitymentioning

confidence: 99%

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Utility-based operation management for low voltage distribution grids using online optimization

Ipach

Fisser

Becker

et al. 2021

Elektrotech. Inftech.

View full text Add to dashboard Cite

show abstract

“…Stochastic investigations of the relationship between PV penetration and voltage unbalance are conducted in [3,4]; it reported that unacceptable voltage unbalance can occur depending on the PV penetration and placement. In [5,6], uncoordinated charging of EVs adversely affects voltage Energies 2021, 14, 2997 2 of 18 balances are showed. The increase in voltage unbalances lead to induction motor failures, increased losses, and additional cost of increasing a particular phase of the distribution line capacity.…”

Section: Introductionmentioning

confidence: 99%

Unbalanced Voltage Compensation with Optimal Voltage Controlled Regulators and Load Ratio Control Transformer

et al. 2021

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Penetration of equipment such as photovoltaic power generations (PV), heat pump water heaters (HP), and electric vehicles (EV) introduces voltage unbalance issues in distribution systems. Controlling PV and energy storage system (ESS) outputs or coordinated EV charging are investigated for voltage unbalance compensation. However, some issues exist, such as dependency on installed capacity and fairness among consumers. Therefore, the ideal way to mitigate unbalanced voltages is to use grid-side equipment mainly. This paper proposes a voltage unbalance compensation based on optimal tap operation scheduling of three-phase individual controlled step voltage regulators (3φSVR) and load ratio control transformer (LRT). In the formulation of the optimization problem, multiple voltage unbalance metrics are comprehensively included. In addition, voltage deviations, network losses, and coordinated tap operations, which are typical issues in distribution systems, are considered. In order to investigate the mutual influence among voltage unbalance and other typical issues, various optimization problems are formulated, and then they are compared by numerical simulations. The results show that the proper operation of 3φSVRs and LRT effectively mitigates voltage unbalance. Furthermore, the results also show that voltage unbalances and other typical issues can be improved simultaneously with appropriate formulations.

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Evaluation of Voltage Unbalance Definitions for Voltage Control in Distribution Systems with Photovoltaic Penetration

Nakadomari,

Krishnan,

Furukakoi

et al. 2024

IEEJ Transactions Elec Engng

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This paper examines the impact of different voltage unbalance definitions on voltage control in unbalanced distribution systems. Traditional voltage regulation methods for unbalanced systems rely on a single voltage unbalance definition with inconsistent adoptions. In such a situation, voltage control performance can vary between definitions, and improper choice leads to control failures. In this study, we perform numerical analysis and simulations to investigate the impact of different definitions. In the numerical analysis, two definitions quantifying negative and zero sequence components are used as reference definitions, and the theoretical error range of the remaining definitions is identified. The results are further verified by the simulations on the IEEE 123 node test system with phase‐by‐phase controlled three‐phase step voltage regulators and smart photovoltaic inverters. The control of the devices is optimized to minimize or limit a specific definition. The results show that the values of each definition at the same voltage condition can differ significantly, and inappropriate definitions may lead to significant uncertainty in the voltage control. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

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Impact of unbalanced electric vehicle charging on low-voltage grids

Cited by 15 publications

References 12 publications

Utility-based operation management for low voltage distribution grids using online optimization

Utility-based operation management for low voltage distribution grids using online optimization

Unbalanced Voltage Compensation with Optimal Voltage Controlled Regulators and Load Ratio Control Transformer

Evaluation of Voltage Unbalance Definitions for Voltage Control in Distribution Systems with Photovoltaic Penetration

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