Examples of PLL in a sentence
Advantages of virtual impedance are also pointed out such as provision of damping.o The naming of the two operation modes has changed from linear and nonlinear mode to normal and withstand mode.• The use of PLL software for grid-forming is discussed and is not allowed for voltage control when operating below the current limitation.• Modelling and simulation methods (EMT, HIL) for verifying the requirements are discussed.DiscussionThe document provides input to the GBGF-I requirements.
The restrictions towards the use of PLL software and the avoidance of the use of a virtual impedance is too restrictive.Moreover, some of the requirements in this document will mandate a special control implementation strategy for GFM control, which should not be dictated to manufacturers.
Furthermore, the document discusses whether PLL software is allowed for grid-forming.
It is demonstrated that the inner current loop and the PLL are not the only control elements responsible for the inverter instability at low SCL.The maximum time for the voltage response to bring out this GFM behavior can be specified in the interconnection requirements.The performance of five different control strategies of GFM are evaluated and the results show the possibility of similar dynamic behavior through parametrization and tuning.
One implementation uses a PLL and therefore only meant for strong grids and the other one avoids using PLL and therefore suitable for weak grids as well.