A direction element using high frequency transient energy in distribution network with distributed generation

Abstract

The accessing of distributed generation resources to distribution network leads to a multi power grid structure. The direction of power flow changes with it. The photovoltaic (PV) generation contains a large number of power electronic devices and control links, which causes that the output responses and fault characteristics are significantly different from the synchronous machine. In consideration of the topological structure of the distributed distribution network, this paper analyses the differences of transient characteristics of AC distribution line with PV power supply between internal and external faults. Then, a new principle for constructing directional element using transfer and consumption characteristics of high-frequency transient energy is proposed. This directional element only uses high-frequency transient fault voltage and current in early stage, which can reliably distinguish the fault direction. What's more, the existence of transition resistance will be conducive to the judgement. Finally, corresponding simulation cases were carried out to verify the feasibility and superiority of the proposed directional element.