Articles written in Sadhana
Volume 42 Issue 12 December 2017 pp 2099-2112
Conventionally, two AC side current sensors are needed in vector control of grid side converter for AC–DC bidirectional power conversion. The present paper proposes a technique where the control can be achieved with the use of only one AC side current sensor. The control principle utilises the information of unsensedsecond current sensor for its estimation, which is embedded and readily available in conventional control technique itself. In the proposed method, the grid side d–q axis reference currents of the current controllers are used for estimation of b-axis component of grid current, while the a-axis component of grid current is calculated by one AC side current sensor. Effect of voltage unbalance on the control is also studied in this paper. The proposed control is validated with detailed simulation and experimental observations for both steady-state andtransient conditions. The proposed control gives satisfactory performance.
Volume 43 Issue 6 June 2018 Article ID 0085
The presence of diode rectifier in standalone Doubly Fed Induction Generator-Direct Current (DFIGDC) system leads to considerable current, voltage and torque harmonics and requires reactive power from the machine. A unique shunt active filter arrangement is proposed for addressing these requirements. The DC Link ofDFIG-DC itself acts as input to shunt active filter and there is no requirement of creating and regulating a separate one. Since the stator flux reference frame is known in FOC of DFIG-DC system; the same can be used as PLL for thegeneration of current references for harmonics and reactive compensation in active filter control scheme. Hence, the AC voltage sensing is not needed in the proposed active filter control. In this paper, it is shown that current, voltageand torque harmonics are reduced with the help of shunt active filter, which have lower rating compared to the rotor side converter. The proposed scheme is verified by detailed experiments on a 5.5 kW slip-ring induction machine.