Causality analysis in phasor measurement unit algorithms

In order to compensate for the group delay, existing phasor measurement unit (PMU) algorithms usually shift time stamps backward. Such schemes make PMU output dependent on past samples, and thus these PMUs are defined as noncausal PMUs in this chapter. The main drawback of noncausal PMUs is that they may result in high latency that will impair performance of PMU applications. For this, in this chapter, we introduce a novel group delay compensation method without shifting time stamps, and the PMUs using such group delay compensations are defined as causal PMUs. We also investigate the impact of causality on performance of PMU algorithms. We firstly analyze how causal and noncausal PMUs compensate for the group delay caused by digital filters and it is found that causal PMUs normally reduce latency by the group delay while noncausal PMUs will not. Then, the impact of causality is investigated by using the Hydro Quebec Research Institute (IREQ) PMU model and the IEEE PMU model.