In remote areas such as islands, power grids cannot be linked to large interconnected networks. As a result, power generation is typically local and fossil fuel based. There are numerous disadvantages to this solution, including the high cost of transportation from importing oil and coal, high greenhouse gas emissions, high dependency on oil-producing countries, and thus exposure to geopolitical risks and vulnerability to price increases.
For these types of remote regions, adding wind power to the energy mix greatly reduces these disadvantages. Wind and solar power are permanent, local resources that are both efficient and environmentally friendly. In addition, they have a beneficial effect on public finances, reducing the energy bill while attracting carbon credits.
The difficulty arises from the intermittence of these resources. Demand and production of electricity have to be balanced at all times. While a 24-hour electricity consumption profile (heating requirements, cooling requirements, industrial and commercial facilities, lights at night), can be known and therefore predictable, the electricity produced from wind and PV can fluctuate greatly during a single day and from one day to another. On “almost infinite” interconnected networks, the number of wind and PV plants disseminated on a wide area limits these variations, easily absorbable by the grid. On small grids, lack of wind, excess wind, or even unexpected clouds can significantly impact much of the area and unbalance the entire network.
Consequently, utility companies limit the penetration of wind and PV produced energy in the energy mix to avoid overloads and blackouts. (For example, there is a 30% max of the nominal power for French overseas islands.) In order to maintain higher penetration levels in the energy mix, renewable energy production needs to become more predictable.
To that end, the first step can be accomplished at the Utility level using macro algorithms to estimate the production based on historical production data and centralized energy storage. For example, in La Réunion Island in the Indian Ocean, the Utility EDF-SEI calculates each day the daily estimated wind turbine production for the following day based on a moving average over the past 30 days. In addition, EDF-SEI is testing a Sodium–sulphur (NaS) 1MW battery to evaluate how it will absorb wind and PV energy production variations.
EDF-SEI (R&D Energy conference – La Réunion 07 April 2011)
The second step in the equation is to maintain stable, predictable and guaranteed production from each wind power plant. Until now, no single integrated product to forecast wind power and wind energy storage has existed.
Vergnet GEV HP 1MW, the answer to specific needs of complex sites and small grids
For the past 20 years, we have installed wind turbines in the most inaccessible sites, particularly on islands. Widely renowned and proven, our solutions are based on the following key principles:
- Turbines must be easy to transport and install,
- Electrical designs must work with weak grids,
- Operating systems must allow output to be regulated to adhere to demand.
As a significant advancement of our long-proven Farwind® technology, GEV HP 1MW addresses the specific needs of complex sites so utilities can now consider installing powerful 1MW wind turbines in almost any location.
The Full Scale Drive performs electronic filtering of torque and power variations. This advanced technology offers many benefits including yield-optimized control, high-quality current, and fault ride-through capability even in severe voltage drops. Additionally, an IGBT inverter and harmonics filters feed the grid with a pure sine-wave signal. By neutralizing peak loads, it reduces mechanical stress on the wind turbine components.
The Full Scale Drive also allows the generator to perform at variable speed, which allows fine-tuning of reactive power compensation. This feature helps maintain voltage grid stability by supplying or accepting reactive power in case of grid failure. The PLC (Programmable Logical Controller) constantly monitors all the necessary parameters: wind data, wind turbine parameters, and grid parameters including voltage, current and frequency. This keeps the wind turbine within operating limits and ensures maximum output under any weather conditions while avoiding malfunctions and reducing mechanical stress.
With Vergnet GEV HP 1MW, the wind energy is not intermittent anymore
Directly coupled to the Full Scale Drive and the PLC, we have developed fully integrated and innovative solutions to predict wind power production to support the grid in case of frequency drop and to guarantee production at the predicted level.
Thanks to a unitary storage solution included in the electrical cabinet, each wind turbine is able to automatically deliver to the grid 100 kW during 15 minutes (10% primary reserve) in case of frequency drop detection.
The Vergnet SCADA system includes a prediction model for each wind turbine on the wind farm. Based on the energy production forecast by Metnext (a joint endeavour between Meteo France and NYSE), the model constantly learns from actual wind conditions measured on site by met masts or running turbines. As a result, we are able to predict and automatically send to the Utility production levels for the next day 24 hours in advance. We can even transmit this information up to 72 hours in advance.
Thanks to the storage solution and GEV HP 1MW Full Scale Drive, it is also possible to guarantee a constant production over a 30 minute period, with an error margin lower than 15%.
An already operational revolution
By combining storage and production forecasts, the Utility can plan the following day’s output, while optimizing the operation and production capability of the electrical grid. This not only makes the grid stronger, the Utility receives a production guarantee over ranges of 30 minutes thanks to a primary power reserve distributed in each wind farm installation. Now, because of the Vergnet system, wind energy is no longer intermittent and is therefore more attainable and reliable as an alternative energy solution.
In French non-interconnected islands (the national market of Vergnet, where 100% of existing wind farms are composed of Vergnet wind turbines), the French government has issued ambitious plans for increasing wind power. By 2020, the goal is to have 50% of all electricity on the islands sourced from renewable energy.
The first tender for 90 MW (Guadeloupe, St Martin, Martinique, French Guyana, La Réunion, Corse) has been issued for onshore wind turbines with storage/prediction solutions. A government decision is expected within the next several weeks with construction slated for later this year.
To learn more about Vergnet wind turbines as well as the energy forecasting and storage solutions, please visit contact us.
