Asymmetrical fault analysis on distribution feeders with inverter interfaced distributed generators

Whole‐line fault analysis method for unbalanced distribution networks with inverter interfaced distributed generators

“…The boundary conditions are the fault currents and voltages equations seen from the faulty ports, which have been presented in the earlier research work in [27], and the fault matrix Ya,b,c f shown in expression (10) is used to avoid predefining the boundary conditions according to the fault type. The fault type can be easily defined through Z on and Z g without predefining the boundary conditions [27]. For instance, the fault matrix Ya,b,c f can be set as (10) and ( 11) for single-line-ground (SLG) fault and L-L fault, respectively.…”

“…Based on the PQ control strategy and FRT requirements, the IIDG can be modelled as a voltage‐control current source. The positive sequence of the IIDG coupling voltage is sampled to inject the positive‐sequence current during the fault, which can be presented as [27] $$\begin{equation}\left\{ \def\eqcellsep{&}\begin{array}{l} {I_{\rm{q}}} = {\rm{0 }}U{\rm{ > 0}}{\rm{.9}}{U_{\rm{N}}}{\rm{ }}\\[5pt] {I_{\rm{q}}} = {\rm{2}}(0.9 - U/{U_{\rm{N}}}){I_{\rm{N}}} \ {\rm{ 0}}{\rm{.2}}{U_{\rm{N}}} \le U \le {\rm{0}}{\rm{.9}}{U_{\rm{N}}}\\[5pt] {I_{\rm{q}}} = 1.05{I_{\rm{N}}} \ U{\rm{ < 0}}{\rm{.2}}{U_{\rm{N}}}{\rm{ }} \end{array} \right.\end{equation}$$ $$\begin{equation}\left\{ \def\eqcellsep{&}\begin{array}{l} {I_{\rm{d}}} = \min \left( {P/U,\sqrt {I_{\max }^2 - I_{\rm{q}}^2} } \right)\\[7pt] {{\dot I}^1}_{{\rm{DG}}} = \left( {{I_{\rm{d}}}\cos \theta + {I_{\rm{q}}}\sin \theta } \right) + j\left( {{I_{\rm{d}}}\sin \theta - {I_{\rm{q}}}\cos \theta } \right) \end{array} \right.\end{equation}$$where I d and I q are the active current value and reactive current value, respectively. P is the active power of IIDG.…”

“…It can be seen from Figure 2 that Based on the PQ control strategy and FRT requirements, the IIDG can be modelled as a voltage-control current source. The positive sequence of the IIDG coupling voltage is sampled to inject the positive-sequence current during the fault, which can be presented as [27]…”

A fast fault current calculation method for distribution networks connected with inverter interfaced distributed generators

“…The calculation time of the conventional bus-oriented methods depends on the scale of the network [3 , 4] and it is not suitable for electrical engineering. To simplify the calculation process and reduce the calculation time, a new fault current calculation method was proposed, based on the composite-sequence network analysis [5] .…”

Relay protection sensitivity integrated optimal placement and capacity of inverter interfaced distributed generators in distribution networks

“…The DG connection into the distribution network (DN) can reduce the carbon emission, diminish the fuel consumption, lower power transmission loss, elevate the voltage profile to improve the power quality, and enhance the power system reliability and security [ 3 , 4 ]. Nonetheless, the DG connection alters the power flow and fault analysis [ 5 , 6 ], challenging the DN planning strategies.…”