Abdul Sattar Larik

A Novel Approach for the Control of Dual-Active Bridge DC-DC Converter

During these days high frequency dc-dc converters are frequently used in high Power Electronic applications. It is well known fact that the size of the passive components, such as inductors, capacitors and power transformers decreases as the frequency increases. It is well known that high-voltage converters in the power range of 1-10MW have excessive switching losses at the switching frequencies higher than 4 kHz. The favorable DC-DC converter is realized to be the Dual-Active Bridge when a bi-directional power flow is demanded; however the most important problem is to design an appropriate controller for this type of converter. Switch-mode power supplies represent a particular class of variable structure systems (VSS) and have advantage of non-linear control techniques developed for this class of systems. The sliding mode control can handle large power supply and load variations and provides good dynamic response and simple implementation. The sliding mode controller design has become famous choice for non-linear dynamic systems having class of uncertainties. Moreover, it is maximally robust to all unmatched uncertainties. In this paper the sliding mode control is reviewed and its applications to dc-dc converters are discussed.

Analyzing the Impacts of Distributed Generation Integration on Distribution Network: A Corridor Towards Smart Grid Implementation in Pakistan

Renewable power generation sources used as distributed generations (DGs) are increasing rapidly all around the world. Apart from environmental advantages, DGs result in reduction of power losses, improvement of bus voltages, increased system reliability, stability, power quality and ease of operation. In this work, the impacts of DG on power losses, bus voltages and short circuit level of the power system are investigated with different case strategies of DG interconnections. With every strategic case, the DG impacts on power system are analyzed by network simulation through Power System Simulator Siemens Network Calculator software (PSS SINCAL). Significant power losses and voltage improvement were observed depending on size and strategic locations of DG interconnections. Slight increase in network short circuit levels is observed within permissible limits of protection devices. The communication prospects of DG and Smart Grid Integration are also discussed to enable the monitoring, control of interconnected DG units with a two-way electricity and information flow to develop an automated distributed energy network. Finally, an attempt is made to strategize a simple and gradually applicable model of controlling the network conditions through the integration of DGs. Using the state of art of DG integration models, the gradually implementable smart grid system is proposed for under developed countries, like Pakistan.

Wind Power Performance Improvements Using Artificial Neural Network Controller for DC–DC Converter

Pakistan is nowadays facing serious energy crises, especially in power sector due to increase in load demand. To bridge the gap between load demand and generation of electricity, the wind power is a cheapest indigenous solution. Wind power these days is gaining popularity as a growing renewable energy source in the world because of its environmentally clean and safe usage. For generation of wind power, the trend is to install large wind farms either onshore or offshore. These wind farms consist of a large number of wind turbines. Onshore wind farms cover large areas of land but an interesting option is to build offshore wind farms because of higher average wind speeds at sea. In wind power generation, power electronics converters are widely used because of their manifold advantage. DC–DC topologies are most commonly used in wind farms because of their high efficiency and compact size. A single-active bridge (SAB) converter being simple in topology has recently drawn attraction of many researchers. Such converter despite its simple design and number of attractive features produces oscillations. Therefore, it is imperative to design an appropriate controller to minimize the oscillations. The artificial neural network is proposed for the SAB converter and it is believed to handle oscillations.