Protection schemes for decentralized power generation

In accordance with international trends, decentralized power generation is increasing, not only in number, but also in size. It includes renewable energy sources such as wind turbines or small water power plants, combined power and heat generation (combined cycle plants) and emergency generation in larger companies. Especially the generation of electrical energy by wind power has increased dramatically caused by special infeed-laws. Changing of loadflow direction, starting conditions of the protection and possible power swing problems depend on whether the major generation is centralized or decentralized. This is the context in which design and setting of protection schemes have to be considered. These general problems will be presented with help of three examples.