Unified power flow algorithm of transmission and distribution network

Conventionally power flow of transmission and distribution network is calculated separately. With the increasing penetration level of distributed generation (DG), such as photovoltaic and wind power, voltage and power characteristics of tie bus become complicated. The tight coupling problem appears between transmission and distribution network. As a consequence, the power flow calculation must be processed simultaneously. This paper proposes a unified power flow calculation algorithm of transmission and distribution network considering the effect of DGs. Based on the Newton-Raphson (NR) algorithm, the parallel calculation technique is used by dividing the whole problem into several sub-problems. The case study demonstrates the effectiveness of the proposed method.