title: Fractional-order PI based STATCOM and UPFC controller to diminish subsynchronous resonance.
abstract: This research article proposes a powerful fractional-order PI controller to mitigate the subsynchronous oscillations in turbine-generator shaft due to subsynchronous resonance (SSR) with flexible AC transmission system devices such as static synchronous compensator (STATCOM) and unified power flow controller (UPFC). The diminution of SSR is achieved by the raising of network damping at those frequencies which are proximate to the torsional mode frequency of the turbine-generator shaft. The increase of network damping is obtained with the injection of subsynchronous frequency component of current and both current and voltage into the line. The subsynchronous component of current and voltage are derived from the measured signal of the system and further the same amount of shunt current is injected with STATCOM and simultaneous injection of current and voltage with UPFC into the transmission line to make the subsynchronous current to zero which is the prime source of turbine shaft oscillations. The insertion and proper tuning of Fractional-order PI controller in the control scheme, the subsynchronous oscillations are reduced to 92 % in case of STATCOM and 98 % in case of UPFC as compared to without controller and 14 % as compared with the results of conventional PI controller. The IEEE first benchmark model has adopted for analyze the effectiveness and speed of the proposed control scheme using MATLAB-Simulink and the corresponding results illustrates the precision and robustness of the proposed controller.
authors.affiliation: Department of Electrical Engineering, VNIT, Nagpur, Maharashtra India.
authors.forename: D
authors.initials: D
authors.lastname: Koteswara Raju
authors.affiliation: Department of Electrical Engineering, VNIT, Nagpur, Maharashtra India.
authors.forename: Bhimrao S
authors.initials: BS
authors.lastname: Umre
authors.affiliation: Department of Electrical Engineering, VNIT, Nagpur, Maharashtra India.
authors.forename: Anjali S
authors.initials: AS
authors.lastname: Junghare
authors.affiliation: Department of Electrical Engineering, VNIT, Nagpur, Maharashtra India.
authors.forename: Mohan P
authors.initials: MP
authors.lastname: Thakre
authors.affiliation: Department of Electrical Engineering, VNIT, Nagpur, Maharashtra India.
authors.forename: Rambabu
authors.initials: R
authors.lastname: Motamarri
authors.affiliation: Electrical and Electronics Engineering Department, Aditya Engineering College, Kakinada, Andhrapradesh India.
authors.forename: Chaitanya
authors.initials: C
authors.lastname: Somu
keywords: Fractional-order PI controller; STATCOM; Torque amplification; UPFC; Voltage source converter