Power boundaries in multifunctional converter control for three-phase four-wire systems

It has been established that a voltage source converter when used as a power quality compensator can be used for bidirectional active power exchange across the dc bus, simultaneously. However, it may not be possible to execute all the tasks together to their fullest requirements, if the converter operation is restricted within a specified kVA rating. To ensure the safety of the semiconductor devices and the filter components, the converter operation is always restricted within the maximum specified apparent power. While performing one type of task completely, the other tasks may have to be limited. Therefore, it is a challenging and essential task to study the limits of multifunctional converter operation in terms of the power boundaries. The paper deals with a study of power boundaries in multifunctional operation of the voltage source converter using the instantaneous p-q-r theory. The case studies for the multifunctional compensator operation with the most common linear/non-linear loads on a three-phase four-wire power system are presented. The operation boundaries are plotted with the help of power quality indices.