New Wind Power Technology For Stable Power

Research Will Make Turbine Generated Electricity More Practical

Apr 15, 2009 Thomas Kelly

Electricity from wind turbines is erratic, making power grids unstable. New batteries with voltage control are being tested to make wind energy more available.

A major technological development in wind turbines promises to overcome an obstacle preventing wind power from achieving its maximum efficiency. This obstacle is the fluctuation in wind speed and power, and the inevitable times when the wind drops.

Problems With Wind Turbine Electricity

These fluctuations and interruptions can cause instability of the power grid.

Electricity transmission and distribution grids are complex interconnected circuits. A drop in power at one point can cause power surges elsewhere. This can cause switches to trip to compensate for the surges, which can result in blackouts, according to The Industrial Physicist published by the American Institute of Physics.

Wind fluctuations also cause problems for industrial plants and other facilities equipped with their own wind turbines to generate their own power. It is necessary to keep power constant despite inconstant wind. When the wind drops a plant must switch to utility power or back-up power, such as diesel generators. It is necessary for them to minimize any disruptions and ensure the power is smooth.

Wind Power Control Technology

Current research by a trio of companies is aimed at minimizing disruptions and interruptions of wind power. The technology combines switching and stabilizing circuitry developed by the Swedish firm ABB with high-voltage lithium-ion (Li-ion) batteries developed by the French firm Saft. It is being tested in Norfolk, England, on a power grid of EDF Energy, an electrical utility that provides power to one quarter of the population of the United Kingdom.

The installation in Norfolk is using the world's first high-voltage Li-ion battery system for dynamic energy storage combined with dynamic voltage control.

Wind Energy Stabilization

A large bank of rechargeable Li-ion batteries stores power. High-speed electronic switching and stabilizing circuitry -- referred to as Static Var Compensation technology (or SVC Light) -- controls the voltage to compensate for fluctuations in power. It controls the flow of power to the grid and converts the DC power from the batteries to AC power for the grid.

The batteries assist in the stabilization of power. They store surplus energy from wind farms, level out peaks in power on the grid and can provide voltage during interruptions.

Wind Generation Technology Test

The effectiveness for stabilization of a grid is being tested in Norfolk, which is an area well-supplied with wind turbines and hence susceptible to fluctuations in wind.

The technology also holds promise for industrial plants and other facilities fitted with wind turbines. It smoothes out fluctuations in power from varying wind. The batteries can hold the AC power up for long enough to allow a plant or facility to operate during a windless period or to enable an orderly switch to auxiliary power or the utility grid.

The battery system consists of eight Li-ion modules each of which is rated for 646V. The eight modules are connected in series to produce a nominal voltage of 5.2kV. It can deliver 200kW for an hour and 600kW for 15 minutes.

Li-ion batteries can operate for more than 20 years over temperatures of -30 to +60 degrees C. They hold their charge well -- if not discharged, they lose less than 5% of their voltage per year.

The dynamic voltage control equipment has been made compact with the use of high-power transistors (IGBT or insulated gate bipolar transistors).

An Advance Of Green Power

This is a major development that promises to advance the use of wind turbines as a source of environmentally-responsible 'green' power.

It will help to make the power grid less dependent on fossil fuel generators.

It will also help to advance the use of wind power turbines installed in or on industrial plants and facilities such as hospitals, educational establishments, commercial buildings and shopping malls.

Associated environmental reading: Alternative Green Energy Source From Tidal Power

The copyright of the article New Wind Power Technology For Stable Power in Engineering is owned by Thomas Kelly. Permission to republish New Wind Power Technology For Stable Power in print or online must be granted by the author in writing.