24 research outputs found
Performance Analysis and Application of Superconducting Magnetic Energy Storage in a Power System
No full textDelivering an adequate amount of power to electrical equipment is being a tough job due to the continuous upgradation and technological advancement in the equipment. One of such familiar challenging technology adapted nowadays in power system for some specific applications is termed as pulsed power technology. The electrical grid with pulsed power loads is of the significant interest in aerospace and marine applications. Keeping in the mind of pulsed power applications, especially in defence sectors, the Superconducting Magnetic Energy Storage (SMES) system is proposed for a smooth and reliable power flow in the grid. In SMES system, the PCU interfaces the SMES magnet and the AC system in order to give an efficient power exchange and high quality power flow. Power Converter Unit (PCU) of the SMES system consists of a bidirectional DC-DC converter and a three-phase Voltage Source Inverter (VSI) coupled with a common DC-link capacitor. The control schemes employed for both the VSI and DC-DC converter is intended to maintain a constant DC-link voltage. Particularly, the voltage across the DC-link capacitor is tightly regulated using a Dynamic Evolution Control (DEC) strategy instead of a PI controller for the DC-DC converter. Consequently, the DC-link voltage is maintained almost constant with a voltage regulation well below ±10% during a Pulsed Power Load (PPL) condition.
Initially, the performance of the SMES system using a Leaky Least Mean Square (LLMS) control algorithm is compared with that using a Synchronous Reference Frame (SRF) control technique. The comparison is presented to show the effectiveness of the SMES system for power quality improvement. Henceforth, the control scheme for the VSI is proposed based on the Modified SRF (MSRF). Similarly, DEC or PI control strategy is employed to generate appropriate switching pulses for the DC-DC converter. It has been observed that the PI in the inner loop of MSRF is found sluggish during the PPL. Thus, PI is replaced by the DEC scheme to provide a fast response to the PPL. Also, the DC-DC converter employs the DEC instead of a PI in order to achieve a less rippled coil current and uniform voltage distribution across the SMES coil irrespective of load profile. Consequently, it ensures a reduced and acceptable AC loss across the SMES system, and a symmetric voltage distribution across the coil. Moreover, the control performance of the DEC scheme is compared with that of the Proportional-Integral (PI) control technique.
A uniform source current and power with minimum variations is maintained irrespective of the pulsed power load. A detrimental high rating stress on the system due to the load is substantially reduced by the proposed system. The DEC scheme is implemented for tight error regulation of the controlling parameters. The system supply current is found almost balanced, and its Total Harmonic Distortion (THD) is found well below 5%. An effective PPL compensation and a symmetric and uniform voltage distribution across the SMES coil, are achieved due to the precise solid-state control. Nevertheless, it has been seen that the SAPF is incompetent under high PPL demands whereas the SMES system has shown excellent performance under such load conditions. Moreover, a comparative analysis has been made between the conventional SAPF and the SMES system under PPL and Nonlinear Load (NL) conditions, to check the effectiveness of the SMES system. The performance of the proposed system is presented by using Sim Power System (SPS)/MATLAB Simulink, and real-time digital simulator (i.e. Opal RT-Lab/ dSPACE-1104)
Design and modelling of vacuum experimental set-ups
No full textThis thesis deals with study, modelling and designing of some laboratory apparatus in Cryogenics Engineering and Vacuum Technology field. The project is totally educational oriented. Project's aim is to give a clear idea about vacuum technology and modelling of such vacuum experimental set-ups which can serve as the laboratory experiments for both undergraduate and post graduate students. This project work is broadly classified into three parts:-- (i) Study, selection techniques and designing of some vacuum components. (ii) Modelling and operation of vacuum experimental set-ups. (iii) Making bills of materials for the proposed experimental se-ups. The experiments to be done are namely; (i) Study & Calculation of pumping speed of diffusion pump. (ii) Study & Calculation of pumping speed of roots pump. (iii) Study & Calculation of pumping speed of vacuum ejector pump. (iv) Study & Calculation of pumping speed of cryopump. (v) Calibration of vacuum gauges using primary gauges. (vi) Study and calculation of boil-off rate & heat transfer characteristics of vacuum insulation. Design of various components is done like vacuum chambers, thickness and length of pipe lines etc. So many calculations are done like calculation of pumping speed & flow rate of rotary pump, diffusion pump, roots pump and cryopump. Also calculation of boil-off rate of LN2 in vacuum insulation experiments is carried out. Constant volume method and constant pressure methods are used for pumping speed calculation. Vacuum insulation is studied in three ways one is with plain vacuum, second is with powder vacuum and the third one is with multilayer insulation
Mid-point capacitor type VSC based DSTATCOM with a supercapacitor for power quality improvement under unbalanced loading condition
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