Adaptive Current Protection Scheme with Distributed Generation Connected to Distribution Network

The access of a large number of power electronics leads to the change of fault characteristics of the distribution network, which makes the traditional current protection no longer applicable. To improve the adaptability to the connection of inverter-interfaced distributed generator(IIDG) under distribution networks, this paper first considers the current limiting characteristics of IIDG and the requirements of low voltage ride through(LVRT) control, establishes the mathematical model of the grid-connected system of inverter distributed generator under the condition of unbalanced grid voltage, and constructs its equivalent model. Combined with the fault characteristics of interphase short circuit in distribution network with IIDG, the calculation method of the current protection setting the value of the distribution network with IIDG access in different fault types is studied. An adaptive current protection scheme for distribution network with the communication function of smart terminal unit(STU) is proposed, which considers different fault types and different outputs of distributed generation. Finally, PSCAD and MATLAB simulations show that the adaptive current protection is more accurate and reliable than the traditional current protection.