1,131 research outputs found

    Topology assessment for 3 + 3 terminal offshore DC grid considering DC fault management

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    Offshore DC Grids as an Interconnection of Radial Systems : Protection and Control aspects

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    Development and implementation of a LabVIEW based SCADA system for a meshed multi-terminal VSC-HVDC grid scaled platform

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    This project is oriented to the development of a Supervisory, Control and Data Acquisition (SCADA) software to control and supervise electrical variables from a scaled platform that represents a meshed HVDC grid employing National Instruments hardware and LabVIEW logic environment. The objective is to obtain real time visualization of DC and AC electrical variables and a lossless data stream acquisition. The acquisition system hardware elements have been configured, tested and installed on the grid platform. The system is composed of three chassis, each inside of a VSC terminal cabinet, with integrated Field-Programmable Gate Arrays (FPGAs), one of them connected via PCI bus to a local processor and the rest too via Ethernet through a switch. Analogical acquisition modules were A/D conversion takes place are inserted into the chassis. A personal computer is used as host, screen terminal and storing space. There are two main access modes to the FPGAs through the real time system. It has been implemented a Scan mode VI to monitor all the grid DC signals and a faster FPGA access mode VI to monitor one converter AC and DC values. The FPGA application consists of two tasks running at different rates and a FIFO has been implemented to communicate between them without data loss. Multiple structures have been tested on the grid platform and evaluated, ensuring the compliance of previously established specifications, such as sampling and scanning rate, screen refreshment or possible data loss. Additionally a turbine emulator was implemented and tested in Labview for further testing

    Impact of Multi-terminal HVDC Grids on Enhancing Dynamic Power Transfer Capability

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    Power balancing and dc fault ride through in DC grids with dc hubs and wind farms

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    Acknowledgment This project was funded by European Research Council under the Ideas program in FP7; grant no 259328, 2010.Peer reviewedPostprin

    HVDC transmission : technology review, market trends and future outlook

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    HVDC systems are playing an increasingly significant role in energy transmission due to their technical and economic superiority over HVAC systems for long distance transmission. HVDC is preferable beyond 300–800 km for overhead point-to-point transmission projects and for the cable based interconnection or the grid integration of remote offshore wind farms beyond 50–100 km. Several HVDC review papers exist in literature but often focus on specific geographic locations or system components. In contrast, this paper presents a detailed, up-to-date, analysis and assessment of HVDC transmission systems on a global scale, targeting expert and general audience alike. The paper covers the following aspects: technical and economic comparison of HVAC and HVDC systems; investigation of international HVDC market size, conditions, geographic sparsity of the technology adoption, as well as the main suppliers landscape; and high-level comparisons and analysis of HVDC system components such as Voltage Source Converters (VSCs) and Line Commutated Converters (LCCs), etc. The presented analysis are supported by practical case studies from existing projects in an effort to reveal the complex technical and economic considerations, factors and rationale involved in the evaluation and selection of transmission system technology for a given project. The contemporary operational challenges such as the ownership of Multi-Terminal DC (MTDC) networks are also discussed. Subsequently, the required development factors, both technically and regulatory, for proper MTDC networks operation are highlighted, including a future outlook of different HVDC system components. Collectively, the role of HVDC transmission in achieving national renewable energy targets in light of the Paris agreement commitments is highlighted with relevant examples of potential HVDC corridors

    DC Line-to-Ground Fault Analysis for VSC Based HVDC Transmission System

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    Voltage Source Converter based HVDC (VSC- HVDC) transmission technology as a kind of new dc transmission, is attracting more and more research. VSCs are susceptible to transmission line to line fault and line to ground fault. This paper focuses on the transient characteristics of electrical quantities in a VSC-HVDC system after the occurrence of line to ground fault. Equivalent circuit and equation is given to calculate the voltage and current in transmission line. Simulations are undertaken in PSCAD. The behaviors of DC voltage and DC current in faulty transmission line after the line to ground fault is studied. According to the characteristics of the fault current circuit when the line to ground fault occurs, the three stages of fault process were presented in detail. Firstly, DC-side capacitor discharge stage and the voltage of capacitor were derived. Secondly, the state equation of grid-side current feeding stage. Thirdly, the distribution of DC-side capacitor voltage in voltage recovery stage was analyzed. This paper also present a propose protection scheme for transmission line in VSC - HVDC system
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