A Novel Modified Decoupled Newton-Raphson Load Flow Method with Distributed Slack Bus for Islanded Microgrids Considering Frequency Variations

Microgrid load flow studies have recently attracted a lot of attention due to the introduction of independent microgrids with decentralized sources. These microgrids can be operated in grid-connected mode as well as in islanded mode. But the islanded mode operation of microgrids has some inherent limitations that cannot be addressed by conventional load flow approaches. Recent research has suggested some modifications to the traditional methods by treating system frequency as a variable parameter and leaving out the concept of slack bus. In this respect, a novel load flow method has been presented for microgrids that operate as droop-regulated distributed generations (DGs) employing distributed slack bus. The Jacobian matrix has been modified, which leads to improved convergence. Further, a comparison of the modified decoupled Newton Raphson and the modified Newton Raphson load flow techniques has been presented. Several case studies for 6-bus and 38-bus test systems, demonstrate the feasibility of the proposed load flow approach.