Time Synchronized Low-voltage Measurements for Smart Grids

Smart grids are a new trend in electric power distribution, which has been guiding the digitization of electric ecosystems. These smart networks are continually being introduced in order to improve the dependability (reliability, availability) and efficiency of power grid systems. However, smart grids are often complex, composed of heterogeneous components (intelligent automation systems, Information and Communication Technologies (ICT) control systems, power systems, smart metering systems, and others). Additionally, they are organized under a hierarchical topology infrastructure demanded by priority-based services, resulting in a costly modeling and evaluation of their dependability requirements. This work explores smart grid modeling as a graph in order to propose a methodology for dependability evaluation. The methodology is based on Fault Tree formalism, where the top event is generated automatically and encompasses the hierarchical infrastructure, redundant features, load priorities, and failure and repair distribution rates of all components of a smart grid. The methodology is suitable to be applied in early design stages, making possible to evaluate instantaneous and average measurements of reliability and availability, as well as to identify eventual critical regions and components of smart grid. The study of a specific use-case of low-voltage distribution network is used for validation purposes.

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Incremental Heuristic Approach for Meter Placement in Radial Distribution Systems

Energies ◽

10.3390/en12203917 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3917 ◽

Cited By ~ 2

Author(s):

Giovanni Artale ◽

Antonio Cataliotti ◽

Valentina Cosentino ◽

Dario Di Cara ◽

Salvatore Guaiana ◽

...

Keyword(s):

Radial Distribution ◽

Power Distribution ◽

Smart Grids ◽

Distribution Systems ◽

Low Voltage ◽

Distribution Network ◽

Load Flow ◽

State Variables ◽

Medium Voltage ◽

Meter Placement

The evolution of modern power distribution systems into smart grids requires the development of dedicated state estimation (SE) algorithms for real-time identification of the overall system state variables. This paper proposes a strategy to evaluate the minimum number and best position of power injection meters in radial distribution systems for SE purposes. Measurement points are identified with the aim of reducing uncertainty in branch power flow estimations. An incremental heuristic meter placement (IHMP) approach is proposed to select the locations and total number of power measurements. The meter placement procedure was implemented for a backward/forward load flow algorithm proposed by the authors, which allows the evaluation of medium-voltage power flows starting from low-voltage load measurements. This allows the reduction of the overall costs of measurement equipment and setup. The IHMP method was tested in the real 25-bus medium-voltage (MV) radial distribution network of the Island of Ustica (Mediterranean Sea). The proposed method is useful both for finding the best measurement configuration in a new distribution network and also for implementing an incremental enhancement of an existing measurement configuration, reaching a good tradeoff between instrumentation costs and measurement uncertainty.

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An Analysis of the Systematic Error of a Remote Method for a Wattmeter Adjustment Gain Estimation in Smart Grids

Energies ◽

10.3390/en12010037 ◽

2018 ◽

Vol 12 (1) ◽

pp. 37 ◽

Cited By ~ 4

Author(s):

Robertas Lukočius ◽

Žilvinas Nakutis ◽

Vytautas Daunoras ◽

Ramūnas Deltuva ◽

Pranas Kuzas ◽

...

Keyword(s):

Systematic Error ◽

Power Factor ◽

Smart Grids ◽

Low Voltage ◽

Voltage Drop ◽

Estimation Method ◽

Data Communication ◽

Pattern Search ◽

Error Monitoring ◽

Worst Case

Smart energy meters supporting bidirectional data communication enable novel remote error monitoring applications. This research targets characterization of the systematic worst-case error of the previously published remote watthour meter’s gain estimation method based on the comparison of synchronous measurements by the reference and meter under test. To achieve the research aim a methodology based on global maximization of the systematic error objective function assuming the typical low voltage electrical distribution network operation parameters ranges as defined by the standard recommendations for network design. To cross verify the reliability of the assessed solutions the suggested error analysis methodology was implemented utilizing two stochastic global extremum search techniques (genetic algorithms, pattern search) and the third one utilizing nonlinear programming solver. It was determined that the wattmeter adjustment gain worst-case error does not exceed 0.5% if the remote wattmeter monitored load power factor is larger than 0.1 and a network is designed according to the recommendation of the acceptable voltage drop less than 5%. For a load exhibiting power factor larger than cos φ = 0.9 the worst-case error was found to be less than 0.1%. It is concluded therefore that considering the systematic worst-case error the previously suggested remote wattmeter adjustment gain estimation method is suitable for remote error monitoring of Class 2 and Class 1 wattmeters.

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A novel low voltage grid protection component for future smart grids

2016 51st International Universities Power Engineering Conference (UPEC) ◽

10.1109/upec.2016.8114141 ◽

2016 ◽

Cited By ~ 1

Author(s):

Wolfgang Hauer ◽

Michael Bartonek

Keyword(s):

Smart Grids ◽

Low Voltage

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Effect of Individual Volt/var Control Strategies in LINK-Based Smart Grids with a High Photovoltaic Share

Energies ◽

10.3390/en14185641 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5641

Author(s):

Daniel-Leon Schultis ◽

Albana Ilo

Keyword(s):

Local Control ◽

Smart Grids ◽

Reactive Power ◽

Low Voltage ◽

Control Strategies ◽

Load Flow ◽

Electric Power System ◽

Mobility Control ◽

Holistic View ◽

Voltage Limit

The increasing share of distributed energy resources aggravates voltage limit compliance within the electric power system. Nowadays, various inverter-based Volt/var control strategies, such as cosφ(P) and Q(U), for low voltage feeder connected L(U) local control and on-load tap changers in distribution substations are investigated to mitigate the voltage limit violations caused by the extensive integration of rooftop photovoltaics. This study extends the L(U) control strategy to X(U) to also cover the case of a significant load increase, e.g., related to e-mobility. Control ensembles, including the reactive power autarky of customer plants, are also considered. All Volt/var control strategies are compared by conducting load flow calculations in a test distribution grid. For the first time, they are embedded into the LINK-based Volt/var chain scheme to provide a holistic view of their behavior and to facilitate systematic analysis. Their effect is assessed by calculating the voltage limit distortion and reactive power flows at different Link-Grid boundaries, the corresponding active power losses, and the distribution transformer loadings. The results show that the control ensemble X(U) local control combined with reactive power self-sufficient customer plants performs better than the cosφ(P) and Q(U) local control strategies and the on-load tap changers in distribution substations.

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Flexible Active Power Control for PV-ESS Systems: A Review

Energies ◽

10.3390/en14217388 ◽

2021 ◽

Vol 14 (21) ◽

pp. 7388

Author(s):

Xiangqiang Wu ◽

Tamas Kerekes

Keyword(s):

Energy Storage ◽

Solar Energy ◽

Power Control ◽

Smart Grids ◽

Low Voltage ◽

Storage Systems ◽

Distribution Networks ◽

Active Power ◽

Energy Storage Systems ◽

Active Power Control

The penetration of solar energy in the modern power system is still increasing with a fast growth rate after long development due to reduced environmental impact and ever-decreasing photovoltaic panel cost. Meanwhile, distribution networks have to deal with a huge amount and frequent fluctuations of power due to the intermittent nature of solar energy, which influences the grid stability and could cause a voltage rise in the low-voltage grid. In order to reduce these fluctuations and ensure a stable and reliable power supply, energy storage systems are introduced, as they can absorb or release energy on demand, which provides more control flexibility for PV systems. At present, storage technologies are still under development and integrated in renewable applications, especially in smart grids, where lowering the cost and enhancing the reliability are the main tasks. This study reviews and discusses several active power control strategies for hybrid PV and energy storage systems that deliver ancillary services for grid support. The technological advancements and developments of energy storage systems in grid-tied PV applications are also reviewed.

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Energy Losses Estimation in Low Voltage Smart Grids by using Loss Maps

WEENTECH Proceedings in Energy ◽

10.32438/wpe.5218 ◽

2019 ◽

pp. 247-258

Author(s):

Jose Angel Velasco ◽

Keyword(s):

Smart Grids ◽

Low Voltage ◽

Energy Losses

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Predictive Voltage Control: Empowering Domestic Customers With a Key Role in the Active Management of LV Networks

Applied Sciences ◽

10.3390/app10072635 ◽

2020 ◽

Vol 10 (7) ◽

pp. 2635

Author(s):

Micael Simões ◽

André G. Madureira

Keyword(s):

Distribution System ◽

Smart Grids ◽

Low Voltage ◽

Voltage Control ◽

Distribution Networks ◽

Active Management ◽

Storage Devices ◽

Home Energy Management ◽

System Operator ◽

Home Energy Management System

In order to avoid voltage problems derived from the connection of large amounts of renewable-based generation to the electrical distribution system, new advanced tools need to be developed that are able to exploit the presence of Distributed Energy Resources (DER). This paper describes the approach proposed for a predictive voltage control algorithm to be used in Low Voltage (LV) distribution networks in order to make use of available flexibilities from domestic consumers via their Home Energy Management System (HEMS) and more traditional resources from the Distribution System Operator (DSO), such as transformers with On-Load Tap Changer (OLTC) and storage devices. The proposed algorithm—the Low Voltage Control (LVC)—is detailed in this paper. The algorithm was tested through simulation using a real Portuguese LV network and real consumption and generation data, in order to evaluate its performance in preparation for a field-trial validation in a Portuguese smart grids pilot.

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Review of Voltage and Reactive Power Control Algorithms in Electrical Distribution Networks

Energies ◽

10.3390/en13010058 ◽

2019 ◽

Vol 13 (1) ◽

pp. 58 ◽

Cited By ~ 6

Author(s):

Daiva Stanelyte ◽

Virginijus Radziukynas

Keyword(s):

Smart Grids ◽

Reactive Power ◽

Low Voltage ◽

Distribution Networks ◽

Power Grids ◽

Renewable Energy Resources ◽

Distribution Grid ◽

Harmonic Compensation ◽

Distributed Power Generation ◽

Control Devices

The traditional unidirectional, passive distribution power grids are rapidly developing into bidirectional, interactive, multi-coordinated smart grids that cover distributed power generation along with advanced information communications and electronic power technologies. To better integrate the use of renewable energy resources into the grid, to improve the voltage stability of distribution grids, to improve the grid protection and to reduce harmonics, one needs to select and control devices with adjustable reactive power (capacitor batteries, transformers, and reactors) and provide certain solutions so that the photovoltaic (PV) converters maintain due to voltage. Conventional compensation methods are no longer appropriate, thus developing measures are necessary that would ensure local reactive and harmonic compensation in case an energy quality problem happens in the low voltage distribution grid. Compared to the centralized methods, artificial intelligence (heuristic) methods are able to distribute computing and communication tasks among control devices.

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