Ion Tristiu - Academia.edu (original) (raw)

Papers by Ion Tristiu

Energies, 2019

Microgrids are about to change the architecture and the operation principles of the future power ... more Microgrids are about to change the architecture and the operation principles of the future power systems towards smartness and resiliency. Power electronics technologies are key enablers for novel solutions. In this paper we analyze the benefits of a “microgrid by design” architecture (MDA), using a solid-state transformer (SST) as a low-voltage grid-former and inverter-based generation only. In this context, the microgrid stability is maintained with the help of “electrostatic energy inertia” that can be provided by the capacitor connected to the DC busbar behind the SST inverter topology. This happens in a natural way, alike the mechanical inertia in power systems with synchronous machines, however without depending on frequency and without the need of a rotational inertia. This type of microgrid always operates (both fully connected to the main grid or in islanding mode) with all the necessary mechanisms needed to maintain the microgrid stable—no matter of the perturbations in th...

2022 International Conference and Exposition on Electrical And Power Engineering (EPE)

2019 54th International Universities Power Engineering Conference (UPEC)

Distribution power networks represent an essential sector of electric power systems, due to the r... more Distribution power networks represent an essential sector of electric power systems, due to the role, volume and spread of its components. The electric line ratio of lengthwise parameters specific to transmission system is different than the one specific to distribution system. For this reason, some hypothesis cannot be considered on voltage stability analysis. The aim of this article is to do a theoretical analysis concerning voltage instability condition of distribution network. For a radial electrical network with a single load, the domain of stable operating regime is deduced analytically and the instability limits for different cases are analyzed.

2019 International Conference on ENERGY and ENVIRONMENT (CIEM)

The optimal reactive power dispatch (ORPD) problem represents one of the crucial issues that a po... more The optimal reactive power dispatch (ORPD) problem represents one of the crucial issues that a power system faces in terms of operation and control. Including various regulation actions, such as generators reactive power output, transformer tap settings and shunt compensation devices control, the ORPD is a non-linear optimization problem aiming to minimize the active power losses, while maintaining the voltage deviation within permissible limits. The particle swarm optimization (PSO) method was approached in this paper to solve the ORPD problem, for its capability to generate accurate solutions within a short computational time.

2020 12th International Conference on Electronics, Computers and Artificial Intelligence (ECAI)

This paper presents a practical implementation of a modern DCS in energy sector, applicable for e... more This paper presents a practical implementation of a modern DCS in energy sector, applicable for electric power transmission and distributions substations.When dealing with aging infrastructure the reward from investing in modern automation solution can be substantial, with benefits such increasing productivity, cost savings, safety operations, scalable solution and a better integration in the modern IT facilities.The modern DCS systems evolved into a flexible and scalable automation solutions, which make them mandatory in the actual competitive energy business environment. Comparing to PLCs and traditional DCS, the modern DCS systems are designed to provide automation solution in a safe, reliable and cost-effectively manner.The main goal of this article is to present and suggest an optimal DCS design and functional solutions taking into consideration customer requirements, international and customer applicable norms, budget constraint, hardware and software limitations, integration of existing equipment, cybersecurity and low impact of the monitored and controlled process for extension and future growth.The principles presented in this paper can be found implemented in Romania mainly in the electric power transmission substations, owned by Romanian Transmission and System Operator CNTEE Transelectrica SA.

2021 IEEE 19th World Symposium on Applied Machine Intelligence and Informatics (SAMI), 2021

The aim of this paper is to improve the automation processes of electrical power substations base... more The aim of this paper is to improve the automation processes of electrical power substations based on IEC 61850 standard, with the focus on data management related to data structure, path, and communication model. When modelling substations items a simple and clear approach is necessary to effectively match binary or analog data from the switchyard with the IEC 61850 data object model. The study is made by simply transforming data from a single line diagram and its functionalities into object model by explaining its hierarchy structure and how to use it to create an operational process interface. This possible through the three key components of the IEC 61850 standard: Client-Server based on TCP/IP MMS (Manufacturing Messaging Specification) which perform the monitoring and control functions, GOOSE (Generic Object-Oriented Substation Event) protocol used in applications between IEDs (Intelligent Electronic Device) like interlocking signals and trip messages and Sampled Values (SV) protocol used for fast transmission of analogue values over the network.

2020 IEEE 14th International Symposium on Applied Computational Intelligence and Informatics (SACI), 2020

This paper presents the evolution and development trends of the distributed control systems (DCS)... more This paper presents the evolution and development trends of the distributed control systems (DCS) implemented in the Electrical Power Systems, highlighting the impact of the modern versus traditional DCS systems. The principles of the modern DCS systems presented in this paper can be found implemented in Romania in the Transmission and Distribution energy sector, implemented by the Romanian Transmission and System Operator CNTEE Transelectrica SA and, as well as the electricity distribution operators like Electrica, EoN and CEZ.

2017 International Conference on ENERGY and ENVIRONMENT (CIEM), 2017

This paper proposes modelling ranked load curves using algebraic polynomials. Starting from the a... more This paper proposes modelling ranked load curves using algebraic polynomials. Starting from the assumption of some characteristic parameters of load profiles: maximum power, minimum power and the energy consumption in a time period, characteristic coefficients of different types of algebraic polynomials such as: linear, parabolic and third-order are obtained. The modelling of real load profile has been tested on a small industrial consumer. For testing the modelling accuracy average power and the mean square power has been considered.

2019 International Conference on ENERGY and ENVIRONMENT (CIEM), 2019

The growing interest in mass integration of distributed generation (DG) raises new challenges in ... more The growing interest in mass integration of distributed generation (DG) raises new challenges in power systems operation and planning strategies. The DG units deployment in distribution networks affects their behavior and performance, leading to additional concerns regarding the voltage stability. Two indexes named Voltage Vulnerability Index (VVI) and Sensitivity of Voltage Vulnerability Index (SVVI) are developed in this paper for voltage stability evaluation and DG impact assessment on distribution networks. The proposed analysis procedure has been applied on IEEE 33- bus radial system. Additional to the voltage profile improvement, the power losses reduction is also evaluated during the study.

2017 International Conference on ENERGY and ENVIRONMENT (CIEM), 2017

The European Union's energy policy focuses on a continuous increase of the renewable sources ... more The European Union's energy policy focuses on a continuous increase of the renewable sources quota. By the year 2050, the renewable integration level is expected to reach 60–70 %. In order to reach this level, substantial investments are needed as the current tendency is to shift from large centralized power plants to distributed on-site renewable energy sources. By looking at the country of Romania, (especially the South-East part) it can be seen that it presents a huge energy potential (solar and wind power), wide land spreads used of agricultural purposes and a vast water catchment areas. The Ministry of Agriculture and Rural Development states that less than 3% of the total agricultural surface is efficiently irrigated. Due to the severe droughts, the agricultural productivity of this region has varied between 35–60 % in the past decade. The Romanian Energy Strategy (for 2016–2035) highlights the fact that in the energy mix, renewables will occupy a solid percentage, as the numbers of ‘prosumers’ is forecast to increase substantially. This paper aims to analyze an agricultural setup, in which renewable energy sources are integrated together with an efficient irrigation system, in order to increase the global productivity of crops. The goal is to evaluate both, the technical and economic feasibility of implementing the proposed system.

2021 10th International Conference on ENERGY and ENVIRONMENT (CIEM), 2021

2020 International Conference and Exposition on Electrical And Power Engineering (EPE), 2020

This paper performs an assessment of PV panels solutions under restricted area conditions, by con... more This paper performs an assessment of PV panels solutions under restricted area conditions, by considering tilt various angles and partial shading avoidance, also with focus on high self-production and increased resilience of the prosumer or of the energy community. It is proposed an algorithm using average price of energy used by building owner based on a mix between price obtained from PV panels and energy market price. Breakeven return of invest are highlighted, having PV panels technology price, energy market price and tilt angle variations as main parameters of the analysis. The analysis is made for locational conditions specific for Bucharest-Romania, while the results can be extrapolated also for regions with similar geographical situations.

2020 International Conference and Exposition on Electrical And Power Engineering (EPE), 2020

This paper presents a practical laboratory for student education purpose in Distributed Control S... more This paper presents a practical laboratory for student education purpose in Distributed Control Systems, with focus on applications for high voltage transmission substations. The monitoring, control and protection part is realized with a software platform and IED devices manufactured by AREVA T&D France, while the primary equipment, like circuit breakers and disconnectors are simulated with latched relays. The system architecture and communication network are reproducing a real one usually used in transmission substations. The implementation of this laboratory, both through specific laboratory works and experiments, makes the theoretical part to be supported by a practical experience, resulting in future graduates with added value in the electric power industry.

Abstract—This paper address the issue of future smart grids resilience, by assessing the impact ... more Abstract—This paper address the issue of future smart grids resilience, by assessing the impact of distributed generation on the existing electrical distribution systems from the reliability point of view. A central point in the reliability analysis performed in this work is the probabilistic characterization of the random variables involved in the reliability calculations, as time to failure, duration of service restoration and re-closure time. The reliability assessment has then been performed both for traditional distribution systems and for distribution systems containing distributed generation, by means of different types of analysis KeywordsContinuity of supply, electric distribution system, power quality, smart grids

2018 International Conference on Applied and Theoretical Electricity (ICATE), 2018

Due to high renewables penetration, Active Distribution Networks are becoming a reality for every... more Due to high renewables penetration, Active Distribution Networks are becoming a reality for every DSO. During previous years sustained effort was spent to accommodate the distribution network operational requirements to new challenges. Some topics about the DER impact on MV distribution network such as unwanted islanded operation or optimal penetration degree were covered in various studies. This paper continues the analysis of the Active Distribution Networks challenges in a case study with three micro hydroelectric power plants connected to a medium voltage distribution network. The analysis is focusing on the use of new smart meter design and of new phasor measurement unit (PMU) and power quality analyzers, in order to perform necessary observability and to enable new strategies needed to optimize the network operation or to detect and perform islanding measures in the case of networks with high renewable penetration.

2021 10th International Conference on ENERGY and ENVIRONMENT (CIEM), 2021

Accomplishing the aspirations of electrical power engineering consists, nowadays, in accurately d... more Accomplishing the aspirations of electrical power engineering consists, nowadays, in accurately determining the operating modes. Knowing the parameters of network elements is imperative for accurate solving the power flow regimes. This paper addresses unitarily the calculation of longitudinal resistance of three windings transformers and autotransformers, considering its rated parameters, and discussing the validity of relations demonstrated in detail.

2018 International Symposium on Fundamentals of Electrical Engineering (ISFEE), 2018

In this paper we analyzed the brake energy recovery solution as well as the energy use solutions ... more In this paper we analyzed the brake energy recovery solution as well as the energy use solutions for powering an advanced tram station. We have also identified an additional technical solution for mobile electrical storage, placed at the end of the tram line. The research effort was directed in two main ways. First was identifying the receiver assembly and the functionality of the modern tram station and modeling its operating cycles. The solution was subjected to an economic analysis to identify the feasibility of implementing this solution in a smart city. The second was to identify the optimal brake energy recovery solution as well as the energy efficiency of this technology chain. This approach was supported by a team of engineers from RATB, with whom we kept constant contact and validated (or invalidated) the various technical solutions originally proposed.

2018 International Conference and Exposition on Electrical And Power Engineering (EPE), 2018

Current translation of electrical power systems towards smart grids is encompassing a fundamental... more Current translation of electrical power systems towards smart grids is encompassing a fundamental change in their structure, as well as operation. These coordinates are setting the paths to be followed by the hardware and software embedded in electrical power systems, as well as technology adaptation to the “open-source” customers’ needs and consumption patterns. This paper is following the evolution of energy sector, accompanied by constant improvements of technology, which is providing increasingly complex hardware, which embeds power quality improvement devices, for an efficient operation of electrical power assets. A comprehensive survey of continuous advances of renewable energy sources and storage technology will be presented, which have started the transformation of end-users into energy efficient and clean prosumers, underlining the subsequent energy markets support of peer-to-peer energy trading through novel technologies as blockchain.