Power control for wind turbines in weak grids: Concepts development

Presently, high wind potentials in remote areas may not be utilized for electricity production due to limited grid transmission capacity and/or difficulties in matching the electricity production with the demand. The overall project objective is to help overcome these bottlenecks, i.e. to identify and analyze methods and technologies for making it viable to utilize more of the wind potential in remote areas. The suggestion is to develop a power control concept for wind turbines which will even out the power fluctuations and make it possible to increase the wind energy penetration. The main options are to combine wind power with a pumped hydro power storage or with an AC/DC converter and battery storage. The AC/DC converter can either be an “add-on” type or it can be designed as an integrated part of a variable speed wind turbine. The idea is that combining wind power with the power control concept will make wind power more firm and possible to connect to weaker grids. So, when the concept is matured, the expectation is that for certain wind power installations, the cost of the power control is paid back as added wind power capacity value and saved grid reinforcement costs. Different systems for controlling the power output from a wind farm connected to a weak grid have been investigated. The investigation includes development of different control strategies, use of different storage types, development of a framework for comparing different options and tools needed as part of the framework. The main issues in the assessment of the power control concept are the storage capacity and power rating compared to the installed wind power capacity. The model SimStore has been developed to assess that. The economic investigations have shown that for small systems where only small amounts of wind energy would otherwise have been dumped add-on PQcontrollers with battery storage can be the least cost option compared to grid reinforcement and dumping of energy. For larger systems pumped storage is attractive and worth considering, but for large systems the least cost option is grid reinforcement. Power control technology in combination with wind farms can also contribute to the development of remote regions because such technology will improve the infrastructure of the region and therefore increasing the conditions for local trade and industry ISBN 87-550-2549-3 ISBN 87-550-2550-1(Internet) ISSN 0106-2840 Information Service Department, Riso, 1999