This paper presents a reduced component count power converter for the medium voltage induction motor drive (MVIMD). For critical applications, a compact size, less complex drive system is developed, which satisfies the power quality standard at the ends of the drive system. The proposed drive system is designed such that it has the least number of windings in the multi-winding transformer for a 36-pulse AC-DC converter and the least number of semiconductor switches for the five-level multilevel inverter as compared to the conventional topologies. Hence, the main concerns of this drive system are the reduction in the component count, weight, and losses of the system with excellent harmonics performance. The operational aspects of the topology such as circuit structure, design, and indirect field-oriented control (IFOC), and modulation technique (modified pulse width modulation technique) are explained. To guarantee the high reliability of the presented drive system, the drive model is developed in the Matlab/Simulink 2018b, whereas the simulated results are analyzed in steady-state and in dynamic states for a 298.4kW, 4kV medium-voltage induction motor.
The technological developments in the control strategy cause optimal coordination of conventional energy resources and renewable energy sources and increase the popularity of the AC microgrid (MG). This paper proposes a seamless mode transfer capability of MG to achieve optimal coordination between solar photovoltaic (PV)/battery/utility grid/diesel energy sources. The MG is controlled in such a way that the maximum power demand is fulfilled from a solar PV array; thereby, the optimum use of a clean energy source is targeted. Battery storage at the DC link manages the power variations from the solar PV array during the varying solar irradiations. In GC mode, the MG is synced to the three-phase power grid and thereby, the excess power generation is being fed to it, or the power deficiency is taken from it. Moreover, the MG is synchronized to a diesel engine generator (DEG) set as a standby energy source. The MG is synchronized to it only when the utility grid is not available, the battery state of charge (SOC) is under the lower limit and where PV array power is lower than the load power demand. In this way, the MG is controlled such that optimal coordination of various energy sources is performed in this paper. An improved second-order generalized integrator-frequency locked loop with DC offset rejection capability (SOGI-FLL-WDCRC) is developed in this paper for enhancing the quality of power injected to the utility grid even under abnormal grid conditions and mitigating the power quality (PQ) issues due to the connected nonlinear loads.
This paper presents the grid interactive wind-solar-diesel generator (DG) based microgrid at unpredictable weather conditions with improved reliability of power supply. With the enhanced reliability, the loads are powered continuously during both on-grid and off-grid modes. In view of sensitive loads, the DG is used in the system on the grounds of its dispatchability, which is lacking in the wind-solar power generation. However, the DG is controlled to consume minimum fuel during its operation. The wind power is captured by using a doubly fed induction generator (DFIG), which is coupled to the wind turbine. Moreover, a battery bank is connected in the system for energy storage and to deliver when its need arises. Modified controls are presented for converter on rotor side (CRS) and converter on load side (CLS) of DFIG to make the microgrid flexible for on-grid and off-grid operations. An adaptive step change incremental conductance based maximum power point tracking (MPPT) technique is utilized for acquiring the peak power from the solar photovoltaic (PV) array. Moreover, a modified adaptive step change based perturb and observe (P&O) wind MPPT strategy is incorporated in the control of CRS for improved power capturing as compared to the conventional fixed step methods. Results are presented to evidence the microgrid performance during on-grid and off-grid modes, at fluctuating wind speeds and solar irradiances. Moreover, the comparison of wind turbine efficiency is presented between the modified and conventional wind MPPT techniques.
High Voltage (HV) Pulsed Electric Field (PEF) has been extensively used for the treatment dairy products and juices to inactivate microbes. The present work suggests HV PEF to disinfect the effect of microbes commonly found in water and milk. The PEF of the order of 1.2 microsecond rise time to 50 microsecond tail time in parallel plate static chamber has been applied to get microbes’ free water and milk. For microbial inactivation by PEF the field intensity was varied from zero to 180kV/cm and number of pulses has been varied from zero to 100. In first case field intensity was kept constant and numbers of pulses were varied while in another case numbers of pulses are kept constant and field intensity was varied. In both the cases survival ratio of microbes has been calculated. This experiment's objective was to find out the survival ratio of five kinds of bacteria namely Enterobaracter Aerogenes, Escherichia coli, Listeria Monocytogene, Staphylococcus Aurous, and Acetobacter commonly found in water and milk. The survival ratio of some of microbes were observed very low 0.000001, at 40kV and 40 pulses and some other microbes has also very low survival ratio at more 40kV and number of pulses more than 40. E. coli was completely inactivated at 80kV whereas L.monocytogenes reduced by only two orders of magnitudes at 140kV.It has been found that the bacteria were destroyed due to field-induced at the protecting wall of microbes and not due to ohmic heating.
This paper presents a photovoltaic (PV) system interfaced to a non-ideal grid. The grid is susceptible to have unequal and non-sinusoidal voltages. The control of the system makes it robust against these maladies, and the waveforms of the grid currents are controlled to be sinusoidal with equal magnitude in each phase. The control also prevents the ill-effects of unbalanced nonlinear load currents from deteriorating the grid currents. The current in the grid neutral feeder is also suppressed, thereby reducing the losses. For linking a battery energy storage (BES) to the system DC link, the system uses a bi-directional DC-DC converter. The BES is used as a buffer to maintain the desired power flow to the grid. This removes the unpredictable power injection associated with the PV generation units, thereby helping the utility with the power management and keeping the distribution network stable. Moreover, the BES is utilized to increase monetary returns by keeping the power flow dependent on the utility tariff rates. The continuous revision of the DC link voltage ensures that the peak power is drawn from the PV array. The behavior of the system at several testing circumstances is presented.
