Review of DC System Technologies for Large Scale Integration of Wind Energy Systems with Electricity Grids


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Sheng Jie Shao and Vassilios G. Agelidis of the School of Electrical and Information Engineering, University of Sydney have published a new paper titled „Review of DC System Technologies for Large Scale Integration of Wind Energy Systems with Electricity Grids.“  The paper addresses the fact that ever increasing development and availability of power electronic systems is the underpinning technology that enables large scale integration of wind generation plants with the electricity grid. As the size and power capacity of the wind turbine continues to increase, so is the need to place these significantly large structures at off-shore locations. DC grids and associated power transmission technologies provide opportunities for cost reduction and electricity grid impact minimization as the bulk power is concentrated at single point of entry. As a result, planning, optimization and impact can be studied and carefully controlled minimizing the risk of the investment as well as power system stability issues. This paper discusses the key technologies associated with DC grids for offshore wind farm applications.

The introduction to this interesting article reads:

Over the last twenty years, wind energy has become the fastest developing renewable energy technology. The size of wind turbines has increased from a few tens of kWs in the 1980’s to multi-MW size today. With the development of wind turbine and power electronics technologies, large scale wind farms of hundreds of MWs of power are being developed in many countries around the world. More and more of these farms are proposed to be located offshore, due to large space requirements. Compared with the onshore wind farms, the offshore wind farms have access to significantly better wind energy resources and hence offer larger energy generating capability.

Meanwhile as the power capacity of the offshore wind farms increases, the adequacy of the wind farm electrical system design becomes critical. The overall purpose of designing the electrical system is to collect the energy from individual wind turbines, transmit it to the shore and convert it to appropriate voltage level to enable electricity grid interconnection. Electrical systems layouts aim to maximize the overall energy generation.

The ever increasing penetration level of wind power with the electricity grid also presents many challenges to modern power systems. In the past, it was common practice to disconnect a wind farm from the grid in the event of a network fault. However, as the generation capacity of wind farms has increased significantly and will continue to do so, the regulation of the technical management of the grid is necessary. New power electronic technologies must meet the technical requirements so that the large amounts of electricity generated by the wind can be injected into the grid at varying power level and from a range of wind farm locations.

A large number of wind farms necessitate the development of DC transmission and distribution technologies. DC technologies offer a number of advantages such as low power losses, no connection distance limitation, no resonance etc. They also have major disadvantages concerning control and switching actions. High voltage alternating current (HVAC) subsea transmission schemes maybe used for offshore wind farms. However due to the limitation of the transmission distances, high voltage direct current (HVDC) transmission schemes are preferred. As a consequence, subsea power cables and DC circuit breakers (CBs) are a critical component of an HVDC transmission system used in any offshore electrical power scheme. Considering the interconnection of offshore wind farms, technologies of DC transmission cables and CBs need to be understood.

This paper is organized as follows. Section 2 provides a discussion of existing offshore wind farm power generation schemes. Section 3 describes different electrical system configurations for offshore wind farms. Section 4 summarizes the existing interconnection requirements which mainly include active power, frequency, reactive power voltage quality and fault ride-through requirement. The Section also discusses in detail the operation and control methods of large wind farms in case of electricity grid disturbances and faults. The technical issues associated with DC cables and DC (CBs) are discussed in Section 5. Finally, conclusions are summarized in Section 6.

Read the full paper here in PDF format.

Citation: Shao, Sheng Jie;Agelidis, Vassilios G. 2010. “Review of DC System Technologies for Large Scale Integration of Wind Energy Systems with Electricity Grids.” Energies 3, no. 6: 1303-1319.

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  1. […] This post was mentioned on Twitter by txtgreen, Professor Paul. Professor Paul said: Review: Large Scale Integration of #Wind #Energy Systems with Electric Grids #Sustainability #Green […]

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