New Directive of the European Parliament and of the Council oil the promotion of the use of energy from renewable sources enables member states of European Union not only to initiate changes in legislation, but also to set the mandatory requirements for renewable energy sources. Therefore the number and capacity of renewable power sources, especially wind power plants, ill Lithuania tend to increase very fast. Beside the main advantages of wind power plants, related to environmental and climate changes requirements, softie drawbacks, concerning additional balancing and reserve, could be stated. A lot of questions arise, which are related to operation individualities of wind power plants during steady and fault conditions, influence of wind power plants oil the operation of transmission network, relay protection and automation.