Application of linearised load flow method for droop‐controlled DCMGs

Abstract

In this study, the authors present a linear power flow method for droop-controlled DC microgrids (MGs). Traditional power flow techniques do not apply to droop-controlled DCMGs owing to the power and voltage flexibility capability of the droop-controlled dispatchable generation units. Therefore, new power flow techniques embodying the droop-control operation philosophy were developed by the researchers. The existing methods are time-consuming since they involve iterative solutions of a set of non-linear equations. The proposed linear power flow method is accurate, simple, and gives faster results in comparison to the existing methods. The power flow model applies to all load types (constant power, constant current, and constant resistance) and works for both radial and non-radial system configurations. The linear power flow can be applied for convex optimisation, optimal power flow, and network reconfiguration problems. The proposed method is validated on five test systems. A comparison with a modified Newton–Raphson power flow demonstrates that the proposed linear power flow technique provides accurate results. The maximum error in voltage calculation is not more than 0.0812%. The performance of the proposed method is also acceptable for heavy loads and high line resistances. The computational time reduces significantly with the proposed method.