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This paper presents iterative EMT algorithms for Surge Arrester, also commonly named Metal Oxide Varistors, within 2 different simulation solvers; the State-Space-Nodal solver of ARTEMiS and the nodal admittance method of HYPERSIM. The proposed algorithm, based on fixed-point iteration, allows precise simulation of nonlinear models with minimal extra simulation time cost. Cases are presented in the...
The article presents the models of transformers with specially connected windings for supplying catenary systems of high-speed rail. Using the symmetrical components method and equations describing the relationship between voltages and currents on the primary and secondary sides of the transformer one can derive equations describing the value of the voltage unbalance factor Eu depending on the transformer...
Time domain reflectometry (TDR) applied to live cables is hampered by the absence of a clear reflection from the far end. Instead, location of partial discharge (PD) can be extracted from small structures in recorded patterns arising from any impedance variation along the signal propagation channel. This paper explores two approaches for a single-sided PD location system. The first method compares...
This paper presents a novel approach to deal with the synchronization of microgrids to the main grid. It is based on the use of a power electronic device derived from the original concept of the SSSC (Static Synchronous Series Compensator). The proposed scheme considers the connection of this device at the point-of-interconnection (POI) of the microgrid to the low voltage side of the substation transformer...
Monte Carlo (MC) sequential simulation is capable of providing system chronological information. It is a very useful tool for power system reliability analysis and planning, especially for systems involving time-dependent sources. In this paper, a new sequential simulation approach is proposed for reliability evaluation of composite power systems. The main idea is to apply Latin Hypercube sampling...
Advanced multifunctional distance protection Intelligent Electronic Devices (IEDs) are complex systems with a multi-level functional hierarchy. Their integration in modern IEC 61850 based substation protection, automation and control systems requires good understanding of their functionality and the IEC 61850 principles of object modeling. The goal of this paper is to present a hierarchical object...
The Load Serving Entity (LSE) requires, for its power procurement portfolio management, accurate peak load forecast in medium term (upto six months ahead). A complete description of the random variable, i.e., load, is provided by probability density function. Hence, we consider the problem of forecasting probability density function of hourly peak load during a month. First, we propose a non-parametric...
Many regions in Russia are not connected with the centralized electric system because of their remote geographic location. Therefore, Isolated Micro Grids (IMG) solutions were adopted in the past to generate and supply electric power to these areas. These IMG generally have used conventional power generators to supply both the electric as well as the thermal power. Recently, generators based on Renewable...
Controlled islanding has been widely proposed as a last resort action to prevent blackouts from spreading when usual methods fail in the three-defence-line scheme. In view of global blackouts, these happened largely due to cascading outages, which could lead to transient instability and system collapse. Therefore, transient stability assessment is an important issue for islanding. In order to tackle...
Ultra high voltage (UHV) AC system operates at 1000kV or above and is characterised with having a large transmission capacity (5000MW or above per single circuit) and long transmission distances. It is capable of producing over 4 times more reactive power gains than a conventional 500kV transmission line, and also absorbing a significant amount of reactive power when power flow across the line is...
Nowadays, it is a common practice in power generation utilities to monitor the generation units using Digital Fault Recorders (DFRs). In general, the disturbance records are stored at the utility central office or control center, leading to a substantial amount of data that in practice is not analysed in its totality. This paper describes a methodology to deal with this problem by proposing a fuzzy...
The rapid growth in demand of electricity combined with renewable energy sources (RESs) are presenting serious challenges for the optimal network operation. The future perspective of the dramatic increase in RESs, such as wind and solar energy, may lead to severe problems related to the load dispatch. Other important aspect is the reduction of controllable resources yielding concerns about the reliability...
The major part of disturbs in electrical systems occurs in transmission lines. These disturbs are in most cases single-phase and transitory and mainly caused by atmospheric electrical discharges. In this paper, the voltage-current cross relation characteristic of the secondary arc was investigated using open air experimental data. With more than 500 artificially generated long electrical arcs, a methodology...
Uncertain and variable characteristics of renewable energy resources introduce challenges to power system operation. A normal operating point might be drifted towards an unreliable operating point due to stochastic outputs od renewables. This paper proposes a novel method for estimating critical time to unreliable operating point with steady-state constraints. In this work, a stochastic differential...
For complex power transfer interfaces or load areas with multiple in-feeds, we present a method for phasor-measurement-based calculation of voltage stability margins. In the case of complex transfer paths with multiple injections, a radial system approach may not be sufficient for voltage stability analysis. Our approach provides voltage stability margins considering the full fidelity of the transfer...
This paper proposes a new approach for slow coherency identification in large multi-machine power systems based on inter-area oscillation analysis and electrical proximity. To identify the oscillation modes, the participation factors of the state variables are analysed. The proposed method is applied to a real 1475 bus power system with 50 generators.
In recent years, distributed generators (DG) with renewable energy (RE) are introduced to electric power systems for saving CO2 emission. Installation of DGs in user-side leads to the local demand and supply system, called microgrids (MGs). Since the some of DGs work in DC, advantages of DC supply system over the AC might be emphasized The authors are investigating the merits of DC microgrid (DCMG)...
In this paper we investigate the use of equivalent networks to reduce variable and constraint spaces of medium-term hydro-thermal scheduling problems with variable head cascaded reservoirs and transmission constraints. We take advantage of the fact that in DC power flow formulations, which are suitable for these problems, the Ward equivalent yields exact equivalent networks as far as topology is concerned...
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