107 research outputs found
The Smart Grid: Adapting the Power System to New Challenges
No full textThis book links the challenges to which the electricity network is exposed with the range of new technology, methodologies and market mechanisms known under the name "smart grid." The main challenges will be described by the way in which they impact the electricity network: the introduction of renewable electricity production, energy efficiency, the introduction and further opening of the electricity market, increasing demands for reliability and voltage quality, and the growing need for more transport capacity in the grid. Three fundamentally different types of solutions are distinguished in this book: solutions only involving the electricity network (like HVDC and active distribution networks), solutions including the network users but under the control of the network operator (like requirements on production units and curtailment), and fully market-driven solutions (like demand response). An overview is given of the various solutions to the challenges that are possible with new technology; this includes some that are actively discussed elsewhere and others that are somewhat forgotten.Linking the different solutions with the needs of the electricity network, in the light of the various challenges, is a recurring theme in this book.</p
Voltage quality monitoring, dips classification and responsibility sharing
No full textCEER and EURELECTRIC cooperation in the field
of quality of electricity supply, involving joint meetings and the
participation at the relevant CENELEC Technical Committee,
contributed to the results attained in the recent publication of the
EN 50160:2010 edition that includes a new voltage dips
classification table allowing harmonisation at European level on
voltage dips data collection. The generalisation of voltage quality
monitoring data publication all over Europe will allow the
definition of responsibility sharing between the different involved
stakeholders and the evolution of voltage quality regulation
applied at national level. Examples from Sweden and Italy are
briefly presented in this paper
The Novel Method for Voltage Transient Detection and Characterization
No full textThis paper proposes a novel method for voltage transient detection and characterization using space phasor model (SPM) of the three phase-to-neutral voltages as basis. A Gaussian model based anomaly detection technique is used to extract transient samples as anomalous samples. The proposed method introduces and calculates a set of 'single-transient characteristics'(STC) for voltage transient events. This facilitates quantification of transients, leads to additional information about transient origin, and enables comparing different transients. The proposed method is not sensitive to shallow harmonic distortion particularly in deal with oscillating transients.A number of transients measured at distribution or transmission level have been applied to the proposed method. The simulation results support the effectiveness of the SPM for voltage transient analytics.</p
Impact of uncertainties on resonant overvoltages following transformer energization
No full textA number of changes in the power system have increased the risk for more serious resonances in the harmonic frequency range. The changes also result in an increased uncertainty with regard to the frequency and damping of those resonances. Uncertainties could be related to variations with time, uncertain future developments in the grid, and the modelling of individual components. This article investigates uncertainties affecting resonant overvoltages caused by transformer energization. Several study cases investigating the impact of different uncertainties on resonances and resonant overvoltages, performed in PSCAD, are presented. The results show that some uncertainties may have a significant impact on the resulting impedance characteristics and on the resulting overvoltage levels.</p
Uncertainty analysis of stochastic dynamic line rating
No full textThis paper presents an uncertainty analysis of lines equipped with dynamic line rating (DLR) that are exposed to operational overloading. Multiple sources of uncertainties are taken in to account to model the line rating probabilistically. The superiority of dynamic rating above static rating is confirmed in this paper. However, it is shown in this paper that when the uncertainties in line rating are not considered, DLR can result in a high probability of undetected overloading. Based on assumptions for the uncertainties in relevant weather parameters, the probability of overloading is calculated for three different loading profiles of a line, for each hour during an eight-year period. Guaranteeing a low probability of overloading, with a deterministic dynamic rating, will require a large margin and result in many hours during which unnecessary measures against overloading will be taken. A stochastic dynamic rating, as introduced in this paper, allows for a more transparent and hour-by-hour trade-off between failure to take measures and unnecessary measures against overloading.</p
Impact of modelling of MV network and remote loads on estimated harmonic hosting capacity for an EV fast charging station
No full textThe ability of the distribution network to host electric vehicle (EV) charging might be limited by the harmonic voltages due to their harmonic emission. Network harmonic impedance seen from the point of connection of the charging station plays an important role in harmonic voltage calculation. In this paper, the hosting capacity is estimated for a fast charging station close to a distribution transformer considering different scenarios in terms of network modelling. Data from a typical Swedish distribution network is used, together with a one-month measurement of the emission from state-of-the-art EV charging. The hosting capacity using harmonic voltage limits is compared with the hosting capacity using the transformer rating. A stochastic approach is used for both. This paper shows that harmonic hosting capacity studies are needed; it shows that details of the distribution network must be included to get an accurate estimation of the harmonic hosting capacity; it also shows that a stochastic approach is needed for estimating the harmonic hosting capacity.Validerad;2023;Nivå 2;2023-04-11 (hanlid);Funder: Umeå Energi; Göteborg Energi research foundation</p
Impact of Uncertainties on Resonant Overvoltages
No full textA number of changes in the power system have increased the risk for more serious resonances in the harmonic frequency range. The changes also result in an increased uncertainty with regard to the frequency and damping of those resonances. Uncertainties could be related to variations with time, uncertain future developments in the grid, and the modelling of individual components. In this article, a distinction is made between discrete and continuous stochastic uncertainties. This article further investigates uncertainties affecting resonant overvoltages. Several study cases investigating the impact of different uncertainties on resonances and temporary overvoltages, performed in PSCAD, are presented. The results show that some uncertainties may have a significant impact on the resulting impedance characteristics and potentially on the resulting overvoltage levels.</p
Characterizing three-phase unbalanced dips through the ellipse parameters of the space phasor model
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