Dual Indexed Modified Passive Islanding Detection Technique for Microgrids Employing Unscented Kalman Filtering /

Abstract

The variable demand creates a burden on the power system that causes challenges for consumers as well as generating stations. To meet the fluctuating demand of consumers and to make the system more efficient, penetration of distributed generators (DGs) has increased from the past recent years. But, apart from providing an advantage, it creates the major challenge of unintentional islanding into the system. To prevail over this complication, a dual islanding detection index (𝐷𝐼2) based modified passive islanding detection technique has been proffered in the thesis using the Unscented Kalman Filter (UKF) signal processing scheme. Primarily, a three-phase voltage signature is extricated at the PCC bus (𝑉𝑃𝐶𝐶) and fed into the 12-bit ADC Filter. The filter has built in feature of noise removal using the Bessel Filter in addition to a low pass filter holding a breakpoint frequency (𝑓𝑐𝑢𝑡𝑡) of 1.6kHz to discard the turbulence present in the signal. The ADC Filter & implicit Bessel low pass filter work simultaneously to filter out the signal & to convert 𝑉𝑃𝐶𝐶 to a digital signal at a switching frequency (𝑓𝑠𝑤𝑖) 3.6kHz. The RMS value of the digitalized ADC signals of all three phases (𝑉𝑟𝑚𝑠𝐴𝐷𝐶_𝑎, 𝑉𝑟𝑚𝑠𝐴𝐷𝐶_𝑏,𝑉𝑟𝑚𝑠𝐴𝐷𝐶_𝑐 ) has been given to UKF having sampling time (𝑡𝑠𝑎𝑚) 1/3600sec, to extract the features using sigma points of the signals separately. Ultimately, the UKF output is fed to SSSV and CTHD indices to discern between the planned and un-planned conditions/situations. Accomplishment of recommended UKF strategy is manifested using the IEEE-13 Node Test system simulated on MATLAB/Simulink version 2023a. Various test results reveal that the suggested scheme is highly efficient and precise, having an accuracy of 98%, and can perceive the islanding events within 0.05ms. Moreover, the efficacy of the presented technique has been highlighted by the comparative analysis of the various operating signal processing and other techniques in the literature presented.