Voltage and Frequency Regulation with Load Leveling of a PMSG Based Pico-Hydro System Using SLMS Control Algorithm

This work deals with voltage and frequency control (VFC) of a permanent magnet synchronous generator (PMSG) based pico-hydro system with the load levelling. In this proposed system, a bi-directional DC-DC converter (BDC) with a battery energy storage (BES) is coupled to to voltage source converter (VSC). A bi-directional converter, whose input is BES, is used to control the DC-link voltage of the VSC. Along with the DC-link voltage, it also maintains active power balance in the system. The BDC enables to use a BES with reduced rating of 250V, while the DC-link voltage is always maintained at 380 V. The battery provides load leveling by charging during lightly loaded conditions. When the connected load exceeds more than PMSG based pico-hydro generation, then the excess power is delivered by the BES. The power quality improvement of the system along with VFC is realized using a VSC. The VSC along with VFC also takes care of other power quality problems like harmonics and load unbalancing. A sparse least mean square (SLMS) based control algorithm is used to estimate fundamental component of load currents and to generate reference source currents for VSC control.