Discrete time domain analysis and optimal design of stationary frame AC current controllers with active damped LCL Filter for high power applications

Due to the large variety of renewable power sources, power electronics play an important role in energy conversion. Different power converter topologies are used to interface distributed power generation systems (DPGS) with the utility network. Introduction of power electronics for DPGS provide several advantages such as energy optimal operation by employing a control algorithm to extract the maximum available power. In addition, load control, reduced noise, controllable active and reactive power and improved power quality. These achievements are further improved by digital control systems. The analysis presented in this paper shows the relations of how the stability margins and the transient response criteria are related to the sampling frequency, computational delay and controller gains. The procedure followed can be applied to any filter order with any number of samples of control delay at any sampling frequency. This gives a straightforward method for optimal tuning of the stationary frame AC current controllers with the required stability margins and transient response characteristics. The concluded assumptions were simulated & verified through Matlab/Simulink.