Robust Adaptive Position Observer for Multimode Wind-BES Based Microgrid Interfaced to Distribution Network

This paper presents a robust adaptive position observer (RAPO) for implementing encoder-less speed control for permanent magnet synchronous generator (PMSG). The PMSG is driven by a wind turbine. The basic structure of sliding mode observer (SMO) includes a discontinuous signum function and low pass filter, which introduces not only chattering but also delay in the estimated position. To deal with the issue of classical SMO, RAPO consisting of sigmoid function based continuous super twisting SMO (CSTSMO) followed by a multi-layered fourth order generalized integrator (MFGI) is used for this purpose. The CSTSMO is robust and with continuous switching function, it provides results with less chattering. The MFGI filters out the lower order dominating harmonics and determines the fundamental signal, which helps in calculating accurate position and speed of PMSG. This technique is implemented on a wind-BES based microgrid, which is operable in off-grid as well as in grid interfaced mode. Furthermore, the system is proficient to mitigate some of the power quality issues.