A Comprehensive Load Flow Approach for Grid-Connected and Islanded AC Microgrids

A Comprehensive Three-Phase Step Voltage Regulator Model with Efficient Implementation in the Z-Bus Power Flow

“…The equation system (8) is then solved with the implicit ZBUS method, as described in [5] and [6]. Selecting a sufficiently large value of , the compensating currents in (9) are adequately small to ensure the convergence of the power flow.…”

Efficient Integration of Three-Phase Step Voltage Regulators in the Z-Bus Power Flow Method

“…The equation system ( 8) is then solved with the implicit ZBUS method, as described in [5] and [6]. Selecting a sufficiently large value of , the compensating currents in (9) are adequately small to ensure the convergence of the power flow.…”

“…However, these approaches are not applicable to the Z-Bus power flow method since the SVR equations of [2]- [4] are not compatible with the formation of YBUS matrix. The Z-Bus power flow approach is a fixedpoint iterative method, which is widely applied in distribution network applications, due to its high robustness, fast convergence, ease of implementation and low computation time [5]- [9]. Therefore, accurate and computationally efficient modelling of SVRs is significant in order for the Z-Bus method to maintain its superior characteristics.…”

A Three-Phase Weather-Dependent Power Flow Approach for 4-Wire Multi-Grounded Unbalanced Microgrids with Bare Overhead Conductors

“…In Islanded mode, the DGs operate in droop control to equally share the active and reactive power determined by the P-f and Q-V droop curves, as follows [10]: B) The concept of Virtual Slack node [10] In the absence of a real slack node in islanded MGs, a virtual slack node is assumed to be connected in the network so that the formulation of power flow equations is the same as in grid-connected mode. The only difference is that in islanded mode, the voltage of the virtual slack node is not constant but equalized in each iteration k+1 with the voltage of its adjacent node as it was calculated in the previous iteration k. More specifically, assuming the islanded network of Figure 1, the voltages of the virtual slack node (e.g , , , , ) are equalized with their adjacent voltages according to Equation (3).…”

“…In islanded mode, is equalized in each iteration with its adjacent node, according to Equation (3). Further details about this power flow algorithm are provided in [10], while its applicability is extended in [17]- [19] to hybrid AC/DC networks and to networks containing voltage regulating devices e.g step voltage regulators (SVR) or on-load tap changer transformers (OLTC).…”