Faultlocation Research On Distribution Network With DGs Based On Sufficient Criterion

The interconnection of distributed generations (DGs) has changed distribution network from traditional single supply radial network to multi-supply network with DGs, which brings new challenges to the protection of distribution network. Due to the lack of practical protection methods, isolating all DGs when any network fault is detected is still taken as the protection method for distribution network with DGs. Thus development of renewable energy technology is hindered. The fault location of distribution network with DGs is faced with many practical difficulties. On one hand, there are various kinds of DGs and complicated controlling strategies. On the other hand, objective factors such as insufficient protection configuration for distribution network and simple communication condition still exist. A sufficient principle is proposed which aims to make full use of limited information in distribution network to form a sufficient fault detection condition so that a better fault location performance is achieved without a large scale upgrading and reconstruction of protection configuration for distribution network.Firstly, the sufficient strategy is discussed and analyzed in depth. The definition of fault feature sufficiency is explained and compared with fault feature used by traditional strategy. The characteristics of sufficient strategy is elaborated.A sufficient differential fault location scheme is proposed and its reliability is validated by analyzing sufficient fault features used by the scheme. A new way to obtain the phase difference between the fault line ends is presented and its calculation method used in the fault location procedure is analyzed. The method calculates the fault current included angle information needed in differential protection indirectly, which avoids traditional synchronization error influence and is fairly practicable.In addition, a sufficient fault location scheme based on voltage is proposed which uses the voltage relation of limited nodes to realize the recognition of fault area. On the basis of nodes type division, fault related area is divided, then the protection selectivity in different fault related area is analyzed, voltage search fault location scheme is put forward. After that, a more simple lowest voltage fault location scheme applying matrix to store system information is presented.Matlab/Simulink platform is applied to prove the existence of sufficient fault features and the feasibility of sufficient fault location scheme of distribution network. Results show that sufficient strategy is very adaptive in the distribution network with DGs and the scheme is safe and reliable.