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Power Flow Solution on MultiTerminal HVDC Systems: Supergrid Case
"... Abstract. High Voltage Direct Current (HVDC) systems offer distinct advantages for the integration of offshore wind farms to inland grid system. HVDC transmission system based on Voltage Source Converter (VSC) enables multiterminal use HVDC for the integration of largescale wind power in the North ..."
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Abstract. High Voltage Direct Current (HVDC) systems offer distinct advantages for the integration of offshore wind farms to inland grid system. HVDC transmission system based on Voltage Source Converter (VSC) enables multiterminal use HVDC for the integration of largescale wind power in the North Sea. That network requires a special formulation for power flow analysis as opposed to the conventional method employed on AC networks. This paper presents a sequential AC/DC power flow algorithm, which is proposed for the analysis of multiterminal VSC HVDC (VSCMTDC) systems. This sequential power flow method can be implemented easily in an existing AC power flow package and is very flexible when compared with unified methods. GaussSiedel is used to solve DC power balance equations, as it offers two keys advantages: very fast and simple computational implementation, and errors do not accumulate
Charalambous, "Solution of ac/dc power flow on a multiterminal HVDC system: Illustrative case supergrid phase I
 in Universities Power Engineering Conference (UPEC), 2012 47th International, 2012
"... Abstract This paper presents an algorithm for the sequential solution of the ac/dc power flow, which is proposed for the analysis of multiterminal HVDC systems (MTDC). This sequential power flow algorithm can be implemented easily in an existing ac power flow package and is very flexible when it c ..."
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Abstract This paper presents an algorithm for the sequential solution of the ac/dc power flow, which is proposed for the analysis of multiterminal HVDC systems (MTDC). This sequential power flow algorithm can be implemented easily in an existing ac power flow package and is very flexible when it compared with unified methods. GaussSiedel algorithm is used to solve dc power balance equations, it offers two keys advantages: very fast and simple computational implementation, and errors do not accumulate during the calculation. The algorithm is tested using the WSCC 3machine, 9bus system with a 3terminal MTDC network and results compared with those obtained from DIgSILENT ® PowerFactoryTM demonstrating the validity of the proposed algorithm. As aggregate value, a representative test case of the projected scheme for the phase I of the Supergrid project on the North Sea is presented, the proposed approach presented in this paper is used to calculate DC power flows for some scenarios.
1HVDC Feeder Solution for Electric Railways
"... Abstract—The railway power supply systems in many sparsely populated countries are relatively weak. Weak railway power supply systems causes problems with power quality, voltage drops, and high transmission losses. For AC railway power supply systems with a different frequency than the public grid, ..."
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Abstract—The railway power supply systems in many sparsely populated countries are relatively weak. Weak railway power supply systems causes problems with power quality, voltage drops, and high transmission losses. For AC railway power supply systems with a different frequency than the public grid, highvoltage AC (HVAC) transmission lines are common, connected to the catenary by transformers. In this paper an alternative design based on an HVDC feeder is suggested. The HVDC feeder is connected to the catenary by converters. Such an HVDC line would also be appropriate for DCfed railways and ACfed railways working at public frequency. The converter stations between the public grid and the HVDC feeder can be sparsely distributed, in the range of 100 km or more, whereas the converters connecting the HVDC feeder to the catenary are distributed with a much closer spacing. Their ratings can be lower than substation transformers or electromechanical converters, since the power flow can be fully controlled. Despite a relatively low power rating, the proposed converters can be highly efficient due to the use of medium frequency technology. The HVDCbased feeding system results in lower material usage, lower losses and higher controllability compared to present solutions. Simulations of the proposed solution show clear advantages regarding transmission losses and voltages compared to conventional systems, especially for cases with long distances between feeding points to the catenary, and when there are substantial amounts of regeneration from the trains.
Utility Grid
, 2016
"... Power flow analysis for droop controlled LV hybrid ACDC microgrids with virtual impedance ..."
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Power flow analysis for droop controlled LV hybrid ACDC microgrids with virtual impedance
unknown title
, 2013
"... Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lis ..."
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Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.”
ETH Zurich
, 1417
"... The goal of this master thesis is the development of an algorithm for solving the nonlinear Optimal Power Flow (OPF) and Security Constrained Optimal Power Flow (SCOPF) problems for combined AC and MutiTerminal DC (MTDC) grids. Both grids are modeled using the nonlinear power flow equations. Gri ..."
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The goal of this master thesis is the development of an algorithm for solving the nonlinear Optimal Power Flow (OPF) and Security Constrained Optimal Power Flow (SCOPF) problems for combined AC and MutiTerminal DC (MTDC) grids. Both grids are modeled using the nonlinear power flow equations. Gridlevel models for AC/DC converters are developed based on the Voltage Source Converter (VSC) design with nonlinear power throughput constraints and currentdependent losses. A new model for DC/DC converters is proposed based on modern high power low ratio converter designs. Such devices are used to improve the OPF solution for combined AC/MTDC grids by controlling the DC power flows. The formulation of the SCOPF problem is such that it works for preventive OPF where no corrective actions are allowed after the contingency, as well as for corrective OPF with adjustable actions limits. A contingency filtering approach to reduce the SCOPF problem size, is also developed and its impact on the convergence speed and accuracy is investigated. Several case studies are performed to test both the new SCOPF algorithm and the developed models. Both the OPF and SCOPF solutions are used for a benefit analysis of a proposed MTDC grid expansion. In another study, the impact of DC/DC converters as power flow regulators on MTDC grids is found to correlate strongly with the DC line lengths. A sensitivity analysis of the corrective actions limits on the generation cost is also performed. Generator and converter limits impact is investigated separately and the results are compared.
Digital Object Identifier: tba
"... Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting / republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighte ..."
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Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting / republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.