Mathematical Modelling of Grid Connected Fixed- Pitch Variable-Speed Permanent Magnet Synchronous Generators for Wind Turbines

This project develops the mathematical model of a 10kW permanent magnet synchronous generator (PMSG), which is designed for a fixed-pitch variable-speed wind turbine, and its corresponding simulation model for the control of the PMSG for grid connection using MATLAB/Simulink. The model includes sub-modules, such as a model of the wind speed, a model of the PMSG, a model of the rectifier circuit, a model of the boost chopper circuit, a model of the space vector pulse width modulation (SVPWM) inverter, and a model of the power grid voltage sag detection for low voltage ride through (LVRT). The rectifier is a 3-phase uncontrolled diode full-bridge circuit. The boost chopper circuit offers a direct current (DC) power supply with constant voltage for the inverter. Sampled signals of instantaneous 3-phase voltage (from the power grid) to obtain the phase angle, frequency and amplitude, are used to generate SVPWM signals to control the inverter’s output. In the model of the power grid voltage sag detection, a novel direct-quadrature (DQ) transformation is introduced to detect the voltage sag of the power grid. This thesis systematically analyses the mathematical model along with its sub-modules, and creates simulation models using MATLAB/Simulink. The simulation results demonstrate that both the mathematical model and simulation model are correct, and the parameters of the generator output are synchronised with the main grid

An improved bipolar-type AC-AC converter topology based on non-differential dual-buck PWM AC choppers

A novel single-phase pulse width modulation (PWM) direct ac-ac converter based on two-level non-differential dual-buck ac chopper legs with inverting and non-inverting operations is first proposed in this paper. It has the ability to resolve both voltage sag and swell problems at the same time when used as distributed flexible voltage conditioner (DFVC).Compared to the traditional ac-ac converter, it has much enhanced system reliability thanks to no shoot-through problems even when all switches of each ac chopper legs are turned on, and therefore, the PWM dead-time is not needed leading to improving the utilization of the duty cycles. Only half of the switches in the proposed converter are switched at high frequency during a switching period at most, which significantly reduces the total switching loss. In particularly, the converter has two greatest advantages that it retains the common sharing ground of the input and output and has the same buck/boost operation process for non-inverting and inverting modes. In order to fully testify the performance of the proposed converter, a 500W experimental prototype is built and tested at different conditions

Study of integrated solar PV and municipal energy storage-based power generation system in residential user’s context

Now a days, renewable energy technologies bring revolutionary changes in power systems to meetup electricity load demand to the diverse user levels (i.e. industrial, commercial and residen-tial). Moreover, off-grid PV plants have added a new dimension in energy systems specially in residential user level to serve small scale load demand. Integration of energy storage facilities is helping to bring sustainability by ensuring safe operation of energy technologies, stocking and delivering high performance power generation units to the consumer level with less interruption and fault conditions. Additionally, residential buildings are becoming futuristic energy generation facility by integrating such sustainable energy harvesting technologies. In this thesis, our primary objective is to study on Solar PV integrated building energy infrastructure with the integration of municipal energy storage facility to meet sufficient load demand in residential user level and to test the operation of such systems in different conditions. Moreover, generate optimized models and perform economics analysis for the model. Our plant model has been tested and analyzed for multiple countries aspects which covers developed countries like Finland and developing countries like Bangladesh. This thesis will cover all the necessary analysis for kW range off-grid PV and battery energy-based plants and will help to get insights before projects validation and Initialization

Feasability demonstration of the Vienna type excitation system for synchronous generators

The operation of the Vienna rectifier has been analyzed and relevant literature on the rectifier has been reviewed. Furthermore, the Vienna rectifier in scope of rotating power electronics in brushless excitation has been discussed and found to be an viable option. The Vienna Rectifier have been simulated with the parameters from the Svante testrig in Matlab Simulink with satisfactorily results. A re-connection of the main windings is necessary. Also demagnetizationstrategies and necessary modification to the Vienna Rectifier has been discussed and simulated. A demonstration of the Vienna Rectifier were build, but experimental results are remain qualitative due to practical issues with the demonstration rig. The control were designed in LabView Instruments and the workings of the control-scripts were confirmed. The main challenge is comes from dealing with the large inductance from the mains winding on the rotating exciter, but this challenge may be overcome. Additional circuitry consisting of a chopper on the output and demagnetization resistor and switch should be added to ensure better controllability and demagnetization-capability.M-M

Emerging Power Electronics Technologies for Sustainable Energy Conversion

This Special Issue summarizes, in a single reference, timely emerging topics related to power electronics for sustainable energy conversion. Furthermore, at the same time, it provides the reader with valuable information related to open research opportunity niches