Implementable Three-Phase OPF Formulations for MV-LV Distribution Networks: MILP and MIQCP

Gutierrez‐Lagos, Luis; Liu, Michael Z.; Ochoa, Luis F.

doi:10.1109/isgt-la.2019.8895008

Cited by 24 publications

(52 citation statements)

References 9 publications

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“…The authors of [29] employ the SDP relaxation for distribution systems with neutral cables and fixed ZIP loads. The work [30] proposes linear and quadratic simplifications of an MI optimization problem that addresses different operating conditions between MV and LV systems (exponential ZIP load). Aside from the simplifications, these formulations are not entirely practical in representing the behavior of realistic distribution networks.…”

Section: B Literature Reviewmentioning

confidence: 99%

“…The EV can only interact with the grid when the resident is home (28). The EV must "conclude" the optimization horizon under the same status that its owner originally intended (29)- (30), where n c , n d are the charging and discharging efficiencies. Constraint (32) dictates the technical limits of the EV's charging/discharging behaviour.…”

Section: Device Modellingmentioning

confidence: 99%

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A Comprehensive Multi-Period Optimal Power Flow Framework for Smart LV Networks

Avramidis

Capitanescu

2021

IEEE Trans. Power Syst.

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This paper presents an extensive multi-period optimal power flow framework, with new modelling elements, for smart LV distribution systems that rely on residential flexibility for combating operational issues. A detailed performance assessment of different setups is performed, including: ZIP flexible loads (FLs), varying degrees of controllability of conventional residential devices, such as electric vehicles (EVs) or photovoltaics (PVs), by the distribution system operator (DSO) (adhering to customer-dependent restrictions) and full exploitation of the capabilities offered by state-of-the-art inverter technologies. A comprehensive model-dependent impact assessment is performed, including phase imbalances, neutral and ground wires and load dependencies. The de-congestion potential of common residential devices is highlighted, analyzing capabilities such as active power redistribution, reactive power support and phase balancing. Said potential is explored on setups where the DSO can make only partial adjustments on customer profiles, rather than (as is common) deciding on the full profiles. The extensive analysis can be used by DSOs and researchers alike to make informed decisions on the required levels of modelling detail, the connected devices and the degrees of controlability. The formulation is computationally efficient, scaling well to medium-size systems, and can serve as an excellent basis for building more tractable or more targeted approaches.

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Section: B Literature Reviewmentioning

confidence: 99%

Section: Device Modellingmentioning

confidence: 99%

A Comprehensive Multi-Period Optimal Power Flow Framework for Smart LV Networks

Avramidis

Capitanescu

2021

IEEE Trans. Power Syst.

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“…Furthermore, the technical feasibility of the proposed ramping behavior (i.e., in Fig. 3) is ensured through both constraint (22) and the fact that inverter-interfaced devices typically can fully ramp up/down in the seconds scale [20].…”

Section: Remarks On the Proposed Adaptationsmentioning

confidence: 99%

“…It is adapted from the authors' previous works [21,22], which uses the branch flow model (BFM) [23] for the power flow equations. Specifically, the threephase formulation presented in [22] is extended with additional constraints to cater for the operating characteristics of controllable devices. For completeness, the linearization process and the usage of estimated values is outlined in the Appendix.…”

Section: Three-phase Ac Opfmentioning

confidence: 99%

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On the Implementation of OPF-Based Setpoints for Active Distribution Networks

Liu

Ochoa

Low

2021

IEEE Trans. Smart Grid

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In the context of active distribution networks, AC Optimal Power Flow (OPF) has shown great potential to calculate setpoints for controllable devices. Although considerable literature exists, temporal aspects that may affect the actual execution of these setpoints are rarely investigated. Due to the diverse operating characteristics of controllable devices (i.e., delays, ramp rates and deadbands), when these setpoints are executed by multiple devices without adequate considerations, the resulting outcome can differ drastically from what is expected; leading to violations of network constraints and excessive control actions. Therefore, this work proposes a series of necessary adaptations within the controllers of existing devices as well as in the OPF formulation to cater for the diversity in operating characteristics, ensuring that calculated setpoints are adequately implemented by controllable devices. This involves the direct control of conventional devices and enforcing a new ramping behavior for inverter-interfaced devices. Furthermore, a linear, mixedinteger formulation is proposed to handle discrete devices and improve scalability in large networks. Co-simulation results (using a UK test network with the objective of maximizing renewable energy production and considering 1s time-step) demonstrate that, by catering for the operating characteristics of controllable devices, the expected outcome from OPF-based setpoints can be achieved. Index Terms-Active distribution network, distributed generation, optimal power flow (OPF), implementation NOMENCLATURE Sets DG plants. Buses/nodes. Phases (electrical). ⊂ Sources. Lines. OLTC-fitted transformers. Π Tap positions of OLTCs. Constants/Parameters ̅ Rated capacity of DG plants.

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Quantifying the effects of medium voltage–low voltage distribution network constraints and distributed energy resource reactive power capabilities on aggregators

Gutierrez‐Lagos

Petrou²,

Ochoa

2021

IET Generation Trans & Dist

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Distributed energy resources (DER), such as, photovoltaic systems and batteries, are becoming common among households. Although the main objective is reducing electricity imports (bills), they could also provide system-level services via an aggregator. However, the more DER provide services, the more important is ensuring that the corresponding operation does not result in network issues. To help DER aggregators understand the implications of network constraints, an AC optimal power flow-based methodology is proposed to quantify the effects that three-phase low voltage (LV) and medium voltage (MV) network constraints can have on the volume of services that can be provided for a given horizon, and the potential benefits from using DER reactive power capabilities. Using a convex multi-period formulation that avoids binary variables for batteries and incorporates voltage-dependent load models, the methodology maximizes DER exports (services) for service-related periods and household self-consumption for other periods (reducing bills). Different service periods are assessed to explore the extent of services throughout the day. Results using a realistic UK MV-LV network with 2400+ households, show that aggregator services can be highly overestimated when neglecting MV-LV network constraints, are influenced by voltage-demand load characteristics, and that exploiting DER reactive power capabilities can significantly unlock further services.

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Implementable Three-Phase OPF Formulations for MV-LV Distribution Networks: MILP and MIQCP

Cited by 24 publications

References 9 publications

A Comprehensive Multi-Period Optimal Power Flow Framework for Smart LV Networks

A Comprehensive Multi-Period Optimal Power Flow Framework for Smart LV Networks

On the Implementation of OPF-Based Setpoints for Active Distribution Networks

Quantifying the effects of medium voltage–low voltage distribution network constraints and distributed energy resource reactive power capabilities on aggregators

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