The representation of shunt elements in fast decoupled power flows

This paper discusses the representation of shunt elements in fast decoupled power flow methods. Two major problems have long been recognized as critical to the convergence of decoupled methods: the first one is the well known effect of high r/x ratios; and the second, not so popular, is the effect the representation of shunt elements in the B" matrix. For the first problem there is at least one adequate approach available in the literature. This paper analyzes the second type of problem, gives a mathematical explanation to its causes, proposes a robust version, and illustrates its behavior with a variety of examples. Test results supporting the basic theory are reported. Tests have been conducted in difficult real-life systems, varying from a 308-bus, 208 V distribution grid to a 1663-bus transmission network with voltage levels ranging from 69 kV to 750 kV