scholarly journals Investigating the Converter-Driven Stability of an Offshore HVDC System

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2341
Author(s):  
Matthias Quester ◽  
Fisnik Loku ◽  
Otmane El Azzati ◽  
Leonel Noris ◽  
Yongtao Yang ◽  
...  
Keyword(s):  
Wind Farm ◽  
Short Circuit ◽  
Impedance Measurement ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Response Analysis ◽  
Offshore Wind Farms ◽  
The North ◽  
Ac Transmission

Offshore wind farms are increasingly built in the North Sea and the number of HVDC systems transmitting the wind power to shore increases as well. To connect offshore wind farms to adjacent AC transmission systems, onshore and offshore modular multilevel converters transform the transmitted power from AC to DC and vice versa. Additionally, modern wind farms mainly use wind turbines connected to the offshore point of common coupling via voltage source converters. However, converters and their control systems can cause unwanted interactions, referred to as converter-driven stability problems. The resulting instabilities can be predicted by applying an impedance-based analysis in the frequency domain. Considering that the converter models and system data are often confidential and cannot be exchanged in real systems, this paper proposes an enhanced impedance measurement method suitable for black-box applications to investigate the interactions. A frequency response analysis identifies coupling currents depending on the control system. The currents are subsequently added to the impedance models to achieve higher accuracy. The proposed method is applied to assess an offshore HVDC system’s converter-driven stability, using impedance measurements of laboratory converters and a wind turbine converter controller replica. The results show that the onshore modular multilevel converter interacts with AC grids of moderate short-circuit ratios. However, no interactions are identified between the offshore converter and the connected wind farm.

scholarly journals Investigating the Converter-Driven Stability of an Offshore HVDC System

2021 ◽  
Author(s):  
Matthias Quester ◽  
Fisnik Loku ◽  
Otmane El Azzati ◽  
Leonel Noris ◽  
Yongtao Yang ◽  
...  
Keyword(s):  
Wind Turbine ◽  
System Analysis ◽  
Short Circuit ◽  
Impedance Measurement ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Offshore Wind Farms ◽  
Stability Margins ◽  
The North

Offshore wind farms are increasingly built in the North Sea and the number of HVDC systems transmitting the wind power to shore increases as well. To connect offshore wind farms to adjacent AC transmission systems, onshore and offshore modular multilevel converters transform the transmitted power from AC to DC and vice versa. Besides, modern wind farms mainly use wind turbines connected to the offshore point of common coupling via voltage source converters. However, converters and their control systems can cause unwanted interactions, referred to as converter-driven stability problems. The resulting instabilities can be predicted by applying an impedance-based analysis in the frequency domain. Considering that the converter models and system data are often confidential and cannot be exchanged in real systems, this paper proposes an enhanced impedance measurement method suitable for black-box applications to investigate the interactions. The proposed method is applied to assess an offshore HVDC system’s converter-driven stability, using impedance measurements of laboratory converters and a wind turbine converter controller replica. The results show that the onshore modular multilevel converter’s interactions with AC grids of moderate short-circuit ratios can lead to instabilities. The offshore system analysis reveals that considering the offshore grid topology is crucial for assessing interactions between the wind turbine controllers and the offshore modular multilevel converter. It is shown that different stability margins result from varying offshore grid layouts.

scholarly journals A Spatial Analysis of the Potentials for Offshore Wind Farm Locations in the North Sea Region: Challenges and Opportunities

2020 ◽  
Vol 9 (2) ◽  
pp. 96 ◽  
Author(s):  
Gusatu ◽  
Yamu ◽  
Zuidema ◽  
Faaij
Keyword(s):  
Protected Areas ◽  
North Sea ◽  
Water Depth ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
The North ◽  
Challenges And Opportunities ◽  
The North Sea

Over the last decade, the accelerated transition towards cleaner means of producing energy has been clearly prioritised by the European Union through large-scale planned deployment of wind farms in the North Sea. From a spatial planning perspective, this has not been a straight-forward process, due to substantial spatial conflicts with the traditional users of the sea, especially with fisheries and protected areas. In this article, we examine the availability of offshore space for wind farm deployment, from a transnational perspective, while taking into account different options for the management of the maritime area through four scenarios. We applied a mixed-method approach, combining expert knowledge and document analysis with the spatial visualisation of existing and future maritime spatial claims. Our calculations clearly indicate a low availability of suitable locations for offshore wind in the proximity of the shore and in shallow waters, even when considering its multi-use with fisheries and protected areas. However, the areas within 100 km from shore and with a water depth above –120 m attract greater opportunities for both single use (only offshore wind farms) and multi-use (mainly with fisheries), from an integrated planning perspective. On the other hand, the decrease of energy targets combined with sectoral planning result in clear limitations to suitable areas for offshore wind farms, indicating the necessity to consider areas with a water depth below –120 m and further than 100 km from shore. Therefore, despite the increased costs of maintenance and design adaptation, the multi-use of space can be a solution for more sustainable, stakeholder-engaged and cost-effective options in the energy deployment process. This paper identifies potential pathways, as well as challenges and opportunities for future offshore space management with the aim of achieving the 2050 renewable energy targets.

scholarly journals A Multi-Terminal HVdc Grid Topology Proposal for Offshore Wind Farms

2020 ◽  
Vol 10 (5) ◽  
pp. 1833
Author(s):  
Ali Raza ◽  
Muhammad Younis ◽  
Yuchao Liu ◽  
Ali Altalbe ◽  
Kumars Rouzbehi ◽  
...  
Keyword(s):  
High Voltage ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Offshore Platforms ◽  
Offshore Wind Farms ◽  
Dc Fault ◽  
Grid Side

Although various topologies of multi-terminal high voltage direct current (MT-HVdc) transmission systems are available in the literature, most of them are prone to loss of flexibility, reliability, stability, and redundancy in the events of grid contingencies. In this research, two new wind farms and substation ring topology (2WF-SSRT) are designed and proposed to address the aforementioned shortcomings. The objective of this paper is to investigate MT-HVdc grid topologies for integrating large offshore wind farms with an emphasis on power loss in the event of a dc grid fault or mainland alternating current (ac)grid abnormality. Standards and control of voltage source converter (VSC) based MT-HVdc grids are defined and discussed. High voltage dc switch-gear and dc circuit topologies are appraised based on the necessity of dc cables, HVdc circuit breakers, and extra offshore platforms. In this paper, the proposed topology is analyzed and compared with the formers for number and ratings of offshore substations, dc breakers, ultra-fast mechanical actuators, dc circuits, cost, flexibility, utilization, and redundancy of HVdc links. Coordinated operation of various topologies is assessed and compared with respect to the designed control scheme via a developed EMTDC/PSCAD simulation platform considering three fault scenarios: dc fault on transmission link connecting the wind farm to mainland power converters, dc fault within substation ring of VSC-HVdc stations, and ultimate disconnection of grid side VSC station. Results show that 2WF-SSRT is a promising topology for future MT-HVdc grids.

scholarly journals Use of an INLA Latent Gaussian Modeling Approach to Assess Bird Population Changes Due to the Development of Offshore Wind Farms

2021 ◽  
Vol 8 ◽  
Author(s):  
Raul Vilela ◽  
Claudia Burger ◽  
Ansgar Diederichs ◽  
Fabian E. Bachl ◽  
Lesley Szostek ◽  
...  
Keyword(s):  
North Sea ◽  
Wind Farm ◽  
Population Decline ◽  
Wind Farms ◽  
Offshore Wind ◽  
High Concentration ◽  
Offshore Wind Farms ◽  
The North ◽  
Marine Habitats ◽  
Spatio Temporal

The utilization of marine renewable energies such as offshore wind farming leads to globally expanding human activities in marine habitats. While knowledge on the responses to offshore wind farms and associated shipping traffic is accumulating now at a fast pace, it becomes important to assess the population impacts on species affected by those activities. In the North Sea, the protected diver species Red-throated Diver (Gavia stellata) and Black-throated Diver (Gavia arctica) widely avoid offshore wind farms. We used an explicit spatio-temporal Bayesian model to get a robust estimate of the diver population during the spring season between 2001 and 2018, based on a set of aerial surveys from long-term monitoring programs within the German North Sea. Despite the erection of 20 offshore wind farms in the study area and marked responses of divers to wind farms, model results indicated that there was no population decline, and overall numbers fluctuated around 16,600 individuals, with average annual 95% CI ranging between 13,400 and 21,360 individuals. Although, avoidance behavior due to wind farm development led to a more narrowly focused spatial distribution of the birds centered in the persistent high concentration zone in the Eastern German Bight Special Protection Area, the results provide no indication of negative fitness consequences on these long-lived species. However, more research is needed on habitat use and food availability in this regard.

scholarly journals Temporal patterns in offshore bird abundance during the breeding season at the Dutch North Sea coast

2021 ◽  
Vol 168 (10) ◽  
Author(s):  
Jens A. van Erp ◽  
E. Emiel van Loon ◽  
Kees J. Camphuysen ◽  
Judy Shamoun-Baranes
Keyword(s):  
Breeding Season ◽  
North Sea ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Bird Abundance ◽  
Offshore Wind Farms ◽  
The North ◽  
The North Sea

AbstractThe expanding development of offshore wind farms brings a growing concern about the human impact on seabirds. To assess this impact a better understanding of offshore bird abundance is needed. The aim of this study was to investigate offshore bird abundance in the breeding season and model the effect of temporally predictable environmental variables. We used a bird radar, situated at the edge of a wind farm (52.427827° N, 4.185345° E), to record hourly aerial bird abundance at the North Sea near the Dutch coast between May 1st and July 15th in 2019 and 2020, of which 1879 h (51.5%) were analysed. The effect of sun azimuth, week in the breeding season, and astronomic tide was evaluated using generalized additive modelling. Sun azimuth and week in the breeding season had a modest and statistically significant (p < 0.001) effect on bird abundance, while astronomic tide did not. Hourly predicted abundance peaked after sunrise and before sunset, and abundance increased throughout the breeding season until the end of June, after which it decreased slightly. Though these effects were significant, a large portion of variance in hourly abundance remained unexplained. The high variability in bird abundance at scales ranging from hours up to weeks emphasizes the need for long-term and continuous data which radar technology can provide.

scholarly journals Temporal Patterns in Offshore Bird Abundance During the Breeding Season at the Dutch North Sea Coast

2021 ◽  
Author(s):  
Jens Auke van Erp ◽  
E. Emiel Loon ◽  
Kees J. Camphuysen ◽  
Judy Shamoun-Baranes
Keyword(s):  
Breeding Season ◽  
North Sea ◽  
Wind Farm ◽  
Wind Farms ◽  
Offshore Wind ◽  
Marine Policy ◽  
Bird Abundance ◽  
Offshore Wind Farms ◽  
The North ◽  
Bird Density

Abstract The expanding development of offshore wind farms brings a growing concern about the human impact on seabirds. To assess this impact a better understanding of offshore bird abundance is needed. The aim of this study was to investigate offshore bird abundance in the breeding season and model the effect of predictable environmental factors. We used a bird radar, situated at the edge of a wind farm (52.427827°N, 4.185345°E), to record hourly aerial bird abundance at the North Sea near the Dutch coast between May 1st and July 15th in 2019 and 2020.The effect of sun position, week in the breeding season, and astronomic tide on hourly bird abundance was evaluated using generalized additive modelling. Sun position and week in the breeding season had a modest and statistically significant (p<0.001) effect on bird abundance, while astronomic tide did not. Predicted abundance was higher during the day than during the night, with highest abundance in the morning. Abundance increased throughout the breeding season until the end of June, but decreased again in July. In total the model explained 18.5% of deviance in bird abundance, indicating offshore bird abundance is partially dependent on predictable external factors. The high variability in bird abundance at scales ranging from hours up to weeks emphasizes the need for long term and continuous data which radar technology can provide. The findings of this study can help improve offshore bird density estimations and provide context on the temporal fluctuations in bird abundance for marine policy making.

scholarly journals Economic Feasibility of Floating Offshore Wind Farms in the North of Spain

2020 ◽  
Vol 8 (1) ◽  
pp. 58 ◽  
Author(s):  
Laura Castro-Santos ◽  
A. Rute Bento ◽  
Dina Silva ◽  
Nadia Salvação ◽  
C. Guedes Soares
Keyword(s):  
Wind Farm ◽  
Net Present Value ◽  
Wind Farms ◽  
Economic Feasibility ◽  
Offshore Wind ◽  
Offshore Wind Farms ◽  
The North ◽  
Wind Structure ◽  
Cost Of Energy ◽  
North Of Spain

This paper assesses the economic feasibility of offshore wind farms installed in deep waters considering their internal rate of return (IRR), net present value (NPV), and levelized cost of energy (LCOE). The method proposed has three phases: geographic phase, economic phase, and restrictions phase. The purpose of the geographic step is to obtain the input values, which will be used in the economic phase. Then, the economic parameters are calculated considering the inputs provided previously. Finally, the bathymetric restriction is added to the economic maps. The case study focused on the Cantabric and North-Atlantic coasts of Spain, areas that have not been studied previously in economic terms regarding floating offshore wind technology. Moreover, several alternatives have been considered, taking into account the type of floating offshore wind structure and the electric tariff. Results indicate which is the best floating offshore wind structure with respect to LCOE, IRR, and NPV, and where is the best location for the connection of a floating offshore wind farm in the region selected.

Sea-Keeping Analysis of an Offshore Wind Farm Installation Vessel During the Jack-Up Process

2014 ◽  
Author(s):  
Philip H. Augener ◽  
Hannes Hatecke
Keyword(s):  
Wind Farm ◽  
Wind Farms ◽  
Weather Conditions ◽  
Offshore Wind ◽  
Shallow Waters ◽  
Offshore Wind Farm ◽  
Offshore Wind Farms ◽  
The North ◽  
The North Sea ◽  
Jack Up

Offshore wind farms are not planned in sheltered and shallow waters any longer. Especially in the North Sea there exist many approved offshore wind farm projects at water depth between 30 and 50 meters. In particular the installation process of these projects is strongly influenced by weather conditions and the sea-keeping capabilities of the installation vessels. For reliable planning of the entire project, not only the weather statistics, but also the vessel’s sea-keeping capabilities need to be known accurately. For this purpose different kinds of sea-keeping analyses can be conducted. In this paper a sea-keeping analysis is presented, where the focus is upon the jack-up process. For the numerical computation the sea-keeping code E4ROLLS is applied. The results of this sea-keeping analysis are operational limitations for the jack-up process, caused by two different criteria derived from jack-up classification requirements.

Simulated Onshore-Fault Ride through of Offshore Wind Farms Connected through VSC HVDC

2008 ◽  
Vol 32 (2) ◽  
pp. 103-113 ◽  
Author(s):  
A. Arulampalam ◽  
G. Ramtharan ◽  
N. Caliao ◽  
J.B. Ekanayake ◽  
N. Jenkins
Keyword(s):  
Wind Farm ◽  
Reactive Power ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Offshore Wind Farm ◽  
Offshore Wind Farms ◽  
Grid Connection ◽  
Fault Ride Through

Effective Onshore-Fault Ride Through was demonstrated by simulation for a Fixed Speed Induction Generator (FSIG) offshore wind farm connected through a Voltage Source Converter HVDC link. When a terrestrial grid fault occurs, power through the onshore converter reduces and the DC link voltage increases. A control system was then used to block the offshore converter. The offshore AC network voltage was reduced to achieve rapid power rejection. Reactive power at the onshore converter was controlled to support the AC network voltage according to the GB Grid Code requirements. Two cases, a 200 ms terrestrial fault and a 50% retained voltage fault of duration 710 ms, at the grid connection point were studied. The simulation results show that power blocking at the offshore converter was effective and the DC link voltage was controlled.

Modeling and Simulation of Modular Multilevel Converter Based-HVDC Connecting to Offshore Wind Farms

2014 ◽  
Vol 905 ◽  
pp. 421-426 ◽  
Author(s):  
Seung Hyun Kim ◽  
Woo Cheol Jeong ◽  
Eel Hwan Kim
Keyword(s):  
Wind Farm ◽  
Reactive Power ◽  
Control Method ◽  
Wind Farms ◽  
Offshore Wind ◽  
Voltage Source ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Offshore Wind Farms ◽  
Hvdc System

Modular multilevel Converter (MMC) is a new type of voltage source converter (VSC) topology. The use of this converter in a high-voltage direct current (HVDC) system is called by a MMC-HVDC system. The MMC-HVDC has the advantage in terms of scalability, performance, and efficiency over two-and three-level VSC-HVDC. In this paper, the MMC-HVDC system is used to connect between main grid in Jeju Island and virtual offshore wind farms. The aim is to transfer the power from offshore wind farm to the main grid and to compensate reactive power for the main grid. The simulation is carried out by using PSCAD/EMTDC program, and the results will confirm the effectiveness of the proposed control method.

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