scholarly journals Characterization and Modeling of LV Cables Considering External Parameters for Distribution Networks

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7849
Author(s):  
Ferréol Binot ◽  
Trung Dung Le ◽  
Marc Petit

In response to the climate emergency, new uses are plugged to low voltage (LV) electrical networks. The development of self-consumption complicate the LV grid operation, and force distribution system operators (DSOs) to better model and characterize their networks. DSOs mainly use a three-conductor model (3 CM) to compute power flows, and consider error margins of 2% for voltage profiles to reflect their model inaccuracy. The characteristics of the future LV grids call into question these margins, and the models used. In this paper, a four-conductor model (4 CM), and an additional model named 4 CMext, that considers external parameters (i.e., cable temperature, ground electrical resistivity, and value/number of the earthing resistances) are proposed. The best model for cable characterization and voltage profile calculation is chosen; the 4 CMext is more adapted for the characterization, and corresponds with the finite element model, with an error margin of 4%, experimental measurements of 15%, and French cable manufacturer data of 0.5%. For the voltage profile, the 4 CMext provides a more detailed view of the critical cases that could lead to a violation of the limits of the EN 50160 standard than 3 CM and 4 CM. Violations of high or low voltages are underestimated by two to six times by the 3 CM and 4 CM. Not considering external parameters can lead to a voltage profile error of above 3%. In this paper, we recommend that DSOs use the 4 CMext to represent LV networks, which would allow LV networks to be used closer to their physical limits, and avoid or postpone network reinforcements.

The main aim of the distribution system is delivery the power to the consumers. Because of, aging of electrical infrastructure, old control mechanism, increased power demand causing exploitation of the present electrical networks leads to low voltage profile, more active and reactive power loss with various power quality related issues causing poor network operation. In this method maximization of voltage profile with energy loss minimization is carried using network reconfiguration along with optimal siting of the distributed generation (DG). The proposed methodology is carried out on five bus system. The obtained results are impressive interms of voltage stability and power loss reduction.


2018 ◽  
Vol 61 ◽  
pp. 00012
Author(s):  
Guillermo Domínguez-López ◽  
Pol Paradell-Solà ◽  
José Luis Domínguez-García ◽  
Jacob Rodríguez-Rivero ◽  
Jorge Sánchez-Cifuentes

Future power systems with high penetration of distributed energy resources (DER) and information and communication technology (ICT) will allow increasing the controllability and observability of the grid. However, new challenges for low voltage distribution networks has arisen where the increasing DER is mainly photovoltaic (PV) installed on the roofs of buildings. This type of generation is variable and generates disturbances in the network. Islands are ideal to experience and install new technologies since are weak grids and the penetration of PV will lead to bidirectional power flows at distribution level, thus a smart control will be required. This article aims to present and innovative tool for the distribution system operators (DSOs) to monitor and manage grid operation. In near future, both DER and client’s flexibility will increase. New monitoring and control tools for DSOs are essential. Furthermore, the grid operation optimization is needed to accommodate the expected DER installations and the active participation of consumers’ flexibility services in markets ensuring system efficiency. This tool is tested on “La Graciosa” grid, one of the Canary Islands, to show its benefit. The grid studied includes a hybrid energy storage system (HESS), PV generators, controllable/uncontrollable loads and equipment to monitor power flows.


Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5516
Author(s):  
Filip Relić ◽  
Predrag Marić ◽  
Hrvoje Glavaš ◽  
Ivica Petrović

In the modern power system, Flexible Alternating Current Transmission System (FACTS) devices are widely used. An increased share of the distributed generation (DG) and the development of microgrids change the power flows in the existing distribution networks as well as a conventional power flow direction from the transmission to the distribution network level which may affect the overall stability aspects. The paper shows the FACTS devices’ implementation influence on the performance of the distribution network with integrated renewable energy sources (RES) observing the aspects of the oscillatory stability and the low-voltage motor starting. The FACTS devices, in particular the static var compensators (SVC), have been allocated according to a novel algorithm proposed in the paper. The algorithm uses an iterative process to determine an optimal location for implementation and rating power of SVC considering active power losses minimization, improvement of the voltage profile and maximizing return of investment (ROI) of FACTS devices. Novel constraints—transformer station construction constraint, SVC industrial nominal power value constraint and the constraint of distribution system operator (DSO) economic willingness to investment in the distribution network development are considered in the proposed algorithm. The analysis has been performed on 20 kV rural distribution network model in DIgSILENT PowerFactory software.


Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4451
Author(s):  
Ricardo Silva ◽  
Everton Alves ◽  
Ricardo Ferreira ◽  
José Villar ◽  
Clara Gouveia

Power systems rely on ancillary services (ASs) to ensure system security and stability. Until recently, only the conventional power generation resources connected to the transmission grids were allowed to provide these ASs managed by the transmission system operators (TSOs), while distribution system operators (DSOs) had a more passive role, focused on guaranteeing distribution capacity to bring power to final consumers with enough quality. Now, with the decarbonization, digitalization and decentralization processes of the electrical networks, the growing integration of distributed energy resources (DERs) in distribution grids are displacing conventional generation and increasing the complexity of distribution networks’ operation, requiring the implementation of new active and coordinated management strategies between TSOs and DSOs. In this context, DERs are becoming potential new sources of flexibility for both TSOs and DSOs in helping to manage the power system. This paper proposes a systematic characterization of both traditional and potentially new ASs for TSOs, and newly expected DSO local system services to support the new distribution grid operation paradigm, reviewing, in addition, the main TSO-DSO coordination mechanisms.


Author(s):  
Mehrnoosh Vatani

<p>Adding distributed Generators (DGs) to the passive electrical networks causes major changes in the specifications of the network including voltage profile, short circuit level and transient stability. In this paper, the effect of DGs switching transient in network is considered. The DGs location are changed in different buses. Two types of DGs are used (i.e. wind and synchronous DGs). Switching transient signals are time variant. It has a continuous spectrum of frequency. Fast Fourier and Wavelet transform methods are used for transient analysis. The proposed method is applied to IEEE-13 Bus distribution system.</p>


Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4133
Author(s):  
Alessandro Bosisio ◽  
Matteo Moncecchi ◽  
Andrea Morotti ◽  
Marco Merlo

Currently, distribution system operators (DSOs) are asked to operate distribution grids, managing the rise of the distributed generators (DGs), the rise of the load correlated to heat pump and e-mobility, etc. Nevertheless, they are asked to minimize investments in new sensors and telecommunication links and, consequently, several nodes of the grid are still not monitored and tele-controlled. At the same time, DSOs are asked to improve the network’s resilience, looking for a reduction in the frequency and impact of power outages caused by extreme weather events. The paper presents a machine learning GIS-based approach to estimate a secondary substation’s load profiles, even in those cases where monitoring sensors are not deployed. For this purpose, a large amount of data from different sources has been collected and integrated to describe secondary substation load profiles adequately. Based on real measurements of some secondary substations (medium-voltage to low-voltage interface) given by Unareti, the DSO of Milan, and georeferenced data gathered from open-source databases, unknown secondary substations load profiles are estimated. Three types of machine learning algorithms, regression tree, boosting, and random forest, as well as geographic information system (GIS) information, such as secondary substation locations, building area, types of occupants, etc., are considered to find the most effective approach.


Vestnik MEI ◽  
2021 ◽  
pp. 91-99
Author(s):  
Ivan M. Kazymov ◽  
◽  
Boris S. Kompaneets ◽  

The aim of the study is control of commercial losses in electrical grids, especially in low voltage grids, which is one of the priority lines of activities conducted by electric network companies. The complexity of solving this problem is stemming from the difficulty of exactly locating the commercial loss occurrence place under the conditions of extensively branched low and medium voltage electrical networks. Various methods are currently used to determine the commercial loss occurrence places. However, no effective methods have been created for determining the fact and place of unaccounted electricity consumption in networks under the conditions of performing remote analysis of networks based on the data from modern electricity meters used in the automated fiscal electricity metering system. These difficulties can be overcome by developing a model of voltage distribution and change of current in distribution networks of the 0.4--35 kV nominal voltage levels. A model of voltage distribution and changes of current for a network containing unaccounted electricity consumption is proposed. The effectiveness of using the proposed model has been theoretically substantiated; its applicability limits are defined, and the accuracy of the obtained results is estimated. Graphical representation of the proposed model, which is one of the electrical network digital imaging forms, can be used to analyze electrical networks for revealing if there is unaccounted electricity consumption in them. By using the proposed model of voltage distribution and change of current in the network, it is possible to represent the electrical network as a set of electrical parameters to analyze electrical networks for the presence of commercial losses.


2021 ◽  
Vol 14 (3) ◽  
pp. 100-110
Author(s):  
I. V. Naumov

Analysis has been performed of the operation of electric distribution networks of ten branches of Oblkommunenergo (OKE) of Irkutsk Region [1]. Based on the data on the operation of these networks published in public media, algorithms and computer programs for the Matlab graphic editor are compiled, which are used for plotting time diagrams that characterize the operation of the electrical networks under consideration. The balance changes are shown in the transmission of electric energy into the OKE networks and from the OKE networks directly to consumers (high, medium and low voltage networks). The number of failures, the power supply interruption time and the amount of electricity undersupplied in each month of the year for each of the branches are considered. The months of the year are determined, in which the greatest and least damage occurs to the electrical networks of the OKE branches. Data are presented on the dynamics of annual wear of electric networks, planned activities and their annual implementation. The level of reliability is considered according to the established indicators of the average duration of interruptions in the transmission of electric energy in each calculated regulation period. It is shown that the combination of the main causes of failures largely depends on the natural-climatic and terrain specifics of the regions through which the routes of electric networks pass. As an example, data on the causes of failure in the electrical networks of one of the OKE branches are considered. The most and least damaged electrical networks of the considered OKE branches have been established. In conclusion, findings are formulated and recommendations are presented on minimizing outages based on the main types of failure causes for the purpose of increasing the operational reliability of the electrical networks under consideration.


SCITECH Nepal ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. 1-7
Author(s):  
Avinash Khatri KC ◽  
Tika Ram Regmi

An electric distribution system plays an important role in achieving satisfactory power supply. The quality of power is measured by voltage stability and profile of voltage. The voltage profile is affected by the losses in distribution system. As the load is mostly inductive on the distribution system and requires large reactive power, most of the power quality problems can be resolved with requisite control of reactive power. Capacitors are often installed in distribution system for reactive power compensation. This paper presents two stage procedures to identify the location and size of capacitor bank. In the first stage, the load flow is carried out to find the losses of the system using sweep algorithm. In the next stage, different size of capacitors are initialized and placed in each possible candidate bus and again load flow for the system is carried out. The objective function of the cost incorporating capacitor cost and loss cost is formulated constrained with voltage limits. The capacitor with the minimum cost is selected as the optimized solution. The proposed procedure is applied to different standard test systems as 12-bus radial distribution systems. In addition, the proposed procedure is applied on a real distribution system, a section of Sallaghari Feeder of Thimi substation. The voltage drops and power loss before and after installing the capacitor were compared for the system under test in this work. The result showed better voltage profiles and power losses of the distribution system can be improved by using the proposed method and it can be a benefit to the distribution networks.


Energies ◽  
2018 ◽  
Vol 11 (5) ◽  
pp. 1156 ◽  
Author(s):  
Nikoleta Andreadou ◽  
Evangelos Kotsakis ◽  
Marcelo Masera

The modernization of the distribution grid requires a huge amount of data to be transmitted and handled by the network. The deployment of Advanced Metering Infrastructure systems results in an increased traffic generated by smart meters. In this work, we examine the smart meter traffic that needs to be accommodated by a real distribution system. Parameters such as the message size and the message transmission frequency are examined and their effect on traffic is showed. Limitations of the system are presented, such as the buffer capacity needs and the maximum message size that can be communicated. For this scope, we have used the parameters of a real distribution network, based on a survey at which the European Distribution System Operators (DSOs) have participated. For the smart meter traffic, we have used two popular specifications, namely the G3-PLC–“G3 Power Line communication” and PRIME–acronym for “PoweRline Intelligent Metering Evolution”, to simulate the characteristics of a system that is widely used in practice. The results can be an insight for further development of the Information and Communication Technology (ICT) systems that control and monitor the Low Voltage (LV) distribution grid. The paper presents an analysis towards identifying the needs of distribution networks with respect to telecommunication data as well as the main parameters that can affect the Inverse Fast Fourier Transform (IFFT) system performance. Identifying such parameters is consequently beneficial to designing more efficient ICT systems for Advanced Metering Infrastructure.


Sign in / Sign up

Export Citation Format

Share Document