The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform
Noradin Ghadimi - One of the best experts on this subject based on the ideXlab platform.
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planning in microgrids with conservation of voltage reduction
IEEE Systems Journal, 2018Co-Authors: Milad Gheydi, Alireza Nouri, Noradin GhadimiAbstract:The main focus of this paper is to find an upgrade plan for a microgrid. This plan includes system lines’ upgrades, the place, and size of the new capacitors and DERs. As usual, the planning process is begun with the load forecasting. The main objectives include minimization of system upgrade cost, loss cost, loss cost in peak load, and finally demand cost. The last objective is realized here using the tap changer of the main Station Transformer and reactive power support of the sources available or planned for the future of the grid. This is always referred to as the conservation of voltage reduction. In order to consider the effects of bus voltages on the system demand, the ZIP model for the system loads is used. Particle swarm optimization is used to minimize the total cost. The line flow limits lower/upper bound on bus voltages and minimum/maximum producible active and reactive power from different sources are considered as the optimization constraints. The proposed algorithm is tested on the IEEE 69 bus test system and the results are discussed.
John Olav Tande - One of the best experts on this subject based on the ideXlab platform.
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Multivariate Analysis of Transformer Resonant Overvoltages in Power Stations
IEEE Transactions on Power Delivery, 2011Co-Authors: Bjørn Gustavsen, Arne Petter Brede, John Olav TandeAbstract:In this paper, cable-Transformer resonant overvoltages are studied on the low-voltage (LV) side of a 410-MVA generator step-up (main) Transformer, due to ground fault and energization. The Transformer is placed in a network configuration often found in Norwegian hydropower Stations. The overvoltages are calculated when systematically varying the length of the high-voltage (HV) side cable and that of the cable between the main Transformer LV side and the Station Transformer. This multivariate analysis is performed efficiently, using frequency-domain calculations and the inverse Numerical Laplace Transform. Time-domain simulations are used for analyzing the critical cases in detail. Both types of calculations make use of a blackbox, wideband model of the Transformer, and novel procedures are introduced for initializing computations from correct 50-Hz initial conditions. Among the findings are that extreme overvoltages can occur on the Station Transformer if current-limiting reactors are placed in series with the cable between the main Transformer LV side and the Station Transformer.
Hooman Dehbonei - One of the best experts on this subject based on the ideXlab platform.
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earthing subStation fire and Station Transformer customers supply transfer voltage issue
2016 Down to Earth Conference (DTEC), 2016Co-Authors: Hooman DehboneiAbstract:At midnight on 7 April 2010, a subStation fire cut power to 1500 residences and businesses. Main Roads and the Public Transport Authority responded to ensure that traffic lights and boom gates had generators installed ready to minimise impacts to the public and traffic. Investigations established that a fault in the area and failure of the earthing arrangement lead to the fire and damaged 11 kV indoor switchgear beyond repair. During the ensuing investigation, over 45 customers were identified as being supplied from the subStation Station Transformer, raising concerns amongst internal stakeholders about transfer voltage hazards to customers. A working group was established to respond urgently and considered various suggestions, such as installing a distribution pole-top Transformer or separated earth. It was noted that if the supply arrangement to the customer needed changing, other zone subStations with this particular setup would also need to be changed (significant cost implications); it was queried whether this is an unacceptable risk. Some key challenges during this project were identifying the causes of fire, realistic risk assessment, maintaining positive communication channels among stakeholders to manage risk, preventing unnecessary action and a lack of background technical information for this old subStation. This paper explains the systematic problem identification process to prevent future incidences in consultation with stakeholders and a special earthing design approach for subStation and distribution accompanied by field testing, which lead to a robust risk management strategy. This case illustrates that acceptable levels of people safety were in place and also the prevention of unnecessary actions, which can cost utilities and customers.
Milad Gheydi - One of the best experts on this subject based on the ideXlab platform.
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planning in microgrids with conservation of voltage reduction
IEEE Systems Journal, 2018Co-Authors: Milad Gheydi, Alireza Nouri, Noradin GhadimiAbstract:The main focus of this paper is to find an upgrade plan for a microgrid. This plan includes system lines’ upgrades, the place, and size of the new capacitors and DERs. As usual, the planning process is begun with the load forecasting. The main objectives include minimization of system upgrade cost, loss cost, loss cost in peak load, and finally demand cost. The last objective is realized here using the tap changer of the main Station Transformer and reactive power support of the sources available or planned for the future of the grid. This is always referred to as the conservation of voltage reduction. In order to consider the effects of bus voltages on the system demand, the ZIP model for the system loads is used. Particle swarm optimization is used to minimize the total cost. The line flow limits lower/upper bound on bus voltages and minimum/maximum producible active and reactive power from different sources are considered as the optimization constraints. The proposed algorithm is tested on the IEEE 69 bus test system and the results are discussed.
Bjørn Gustavsen - One of the best experts on this subject based on the ideXlab platform.
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Multivariate Analysis of Transformer Resonant Overvoltages in Power Stations
IEEE Transactions on Power Delivery, 2011Co-Authors: Bjørn Gustavsen, Arne Petter Brede, John Olav TandeAbstract:In this paper, cable-Transformer resonant overvoltages are studied on the low-voltage (LV) side of a 410-MVA generator step-up (main) Transformer, due to ground fault and energization. The Transformer is placed in a network configuration often found in Norwegian hydropower Stations. The overvoltages are calculated when systematically varying the length of the high-voltage (HV) side cable and that of the cable between the main Transformer LV side and the Station Transformer. This multivariate analysis is performed efficiently, using frequency-domain calculations and the inverse Numerical Laplace Transform. Time-domain simulations are used for analyzing the critical cases in detail. Both types of calculations make use of a blackbox, wideband model of the Transformer, and novel procedures are introduced for initializing computations from correct 50-Hz initial conditions. Among the findings are that extreme overvoltages can occur on the Station Transformer if current-limiting reactors are placed in series with the cable between the main Transformer LV side and the Station Transformer.