Application of Trust-Region Method in Load Flow Solution of Distribution Network Embedded with DREG

It has been acknowledged that integration of DREG into electrical distribution system will increase the complication of the system load flow analysis. Therefore, development of reliable and efficient solution method to the DSLF problem is crucial so that the steady-state operation of distribution system, including the DREG, can properly be evaluated. In this paper, application of trust-region method in finding load flow solution of modern distribution network containing DREGs is investigated and presented. Trust-region method is a constrained optimization-based technique for solving a set of nonlinear equations. Trust-region method has successfully been applied in load flow analysis of conventional distribution systems (i.e. distribution systems without DGs). Unlike the forward/backward-based method, particular treatments such as branch/bus renumbering/ reordering are not needed in the trust-region method. These special treatments can be difficult to be carried out especially for large distribution networks. Moreover, since optimization method is used in the solution updating process, trust-region computation algorithm is quite robust. This feature is important in distribution system applications, particularly when the system is ill-conditioned. Validity of the proposed trust-region method is confirmed by the results obtained on three representative distribution networks, i.e. 12-bus, 33-bus networks, and 69-bus networks. In addition, the effect of DREGs installation on distribution system steady state performances is also investigated in this paper. Results of the investigation show that the system performances improve when the DREGs installed in the system.