A three phase load flow algorithm for Shipboard Power Systems

Abstract

Load Flow (Power Flow) is the determination of the steady state operating conditions for the system. This is a very important tool utilized by many real time applications in power systems. Traditional load flow methods, which incorporate Gauss-Seidel and/or Newton Raphson techniques, were primarily developed for transmission system analysis. Distribution load flow analysis must incorporate its unique characteristics such as unbalanced loads, distributed loads, radial network structure, and one, two, or three phase lines. Also, there are a variety of components included in distribution systems such as switches, transformers, voltage regulators, and distributed generators. Therefore, the traditional methods cannot be directly applied to distribution systems since the assumptions made for transmission systems are not valid for the unique characteristics of distribution systems. A Shipboard Power System (SPS) is a finite inertia electric power system. The generation, transmission, and distribution systems in SPSs are tightly coupled. In reality, the transmission system consists of the lines that interconnect the generator buses in a ring configuration. The distribution system consists of lines, transformers, and loads connected in a radial configuration. When analyzing a SPS, its distinct characteristics must be taken into consideration. Therefore, just as transmission and distribution systems have unique methods of analysis, SPSs also need a unique method of analysis. A load flow algorithm for a SPS must consider its distribution system characteristics as well as the unique characteristics of SPSs. The work presented in this thesis discussed a load flow algorithm developed for Shipboard Power Systems and terrestrial wye and delta connected radial distribution systems. The issues in developing a load flow algorithm for a SPS are addressed and the solution is presented. This solution combines three methods that addressed the issues of multiple sources, ring configuration, and radial load flow. This algorithm was tested on the IEEE 37 Bus Radial Distribution Test Feeder and a simplified Shipboard Power Test System developed by researchers in the Power System Automation Laboratory. The results produced minimal percent error when compared to the actual output results.