Nowadays installation of submarine transmission cable interconnections around the world is a valuable asset for the offshore wind, gas and oil industry. There is a worldwide focus on environmental issues. Governments and power suppliers are supporting renewable energy sources, such as wind power, and oil/gas companies are substituting less efficient and CO2 emitting gas-turbine generation on platforms with power supplies from the mainland. This has led to an increasing world-wide demand for submarine cable solutions with less environmental impact. Submarine cables have been increasingly used for power transmission in recent decades. Requirements are increasing regarding more effective use of available energy resources like wind power. We are equipped both with resources and skills to meet any future demands for higher voltages, higher power, deeper water and longer distances.
Indian scenario
The country’s first ever offshore wind power project is set to come up in Gujarat. While on one hand, the Central government is roping in public sector undertakings, on the other hand, Suzlon is conducting a techno-commercial feasibility study for offshore wind power project in Gujarat.
The Ministry of New and Renewable Energy (MNRE) has recently signed a Memorandum of Understanding (MoU) with a group of public sector undertakings and others to setup a joint venture company for an offshore wind power project in Gujarat. The consortium for the 100 MW wind power plant project comprises of National Institute of Wind Energy (NIWE), and consortium of partners consisting of National Thermal Power Corporation (NTPC), Power Grid Corporation of India Ltd (PGCIL), Indian Renewable Energy Development Agency (IREDA), Power Finance Corporation (PFC), Power Trading Corporation (PTC) and Gujarat Power Corporation Ltd (GPCL).
Part of MRNE’s initiatives towards offshore wind power development also include announcement of draft National Offshore Wind Energy Policy and preparation of draft Cabinet note on National Offshore Wind Energy Policy. Once promulgated, the proposed National Offshore Wind Energy Policy will provide a conducive environment for offshore wind energy. In this, experts believe, Gujarat has natural advantage over other states in leveraging on its offshore wind power capabilities. India currently adds about 2,500 MW of wind energy capacity every year. The new government plans to increase annual capacity addition to as high as 10,000 MW. This endeavour would involve tapping sites that are slightly less conducive to wind energy generation and using state-of-the-art wind turbine technology to boost generation.
The government is expected to launch a National Wind Energy Mission soon to achieve this target. It needs to be mentioned here that globally around 7.5 GW of offshore wind power projects have been installed in countries like China, UK, Denmark, Germany, Netherlands, Sweden and Belgium.
Advantages
To take advantage of the steadier winds, offshore turbines are also bigger than onshore turbines and have an increased generation capacity. Offshore turbines generally have nameplate capacities between 2 MW and 5 MW, with tower heights greater than 200 feet and rotor diameters of 250 to 430 feet. The maximum height of the structure, at the very tips of the blades, can easily approach 500 feet, and turbines even larger than 5 MW are being designed and tested for future use.
The three largest offshore wind farms currently under construction are as follows:
Limitation
Problematic for the system stability is load shedding or a step-like increase of load by the multiphase pump. In order to investigate if there is really a problem in practice, the load characteristics of the multiphase pump have to be included into the model and simulation in more detail. It is well known that torque pulses can occur. Further, the range of load change must be defined in more detail. Using this information, the control system can be optimised.
Future scope
Another area for future investigations is the question about the quantities that are really required for system control. The current design requires the currents of all three phases into the machine as well as the rotation speed. However, the system gets simpler if some of these quantities need not to be measured.
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