The need to develop efficient technologies in the domain of Distributed Generation (DG) for meeting the goal of sustainable development is addressed in this work. The Grid-Tied Inverter (GTI), which is the interface between the Distributed Energy Resource (DER) such as Photo-voltaic (PV) panel and the utility grid should be stable, robust to system variations, ensure smooth synchronisation and mitigate harmonic injection. While a higher-order filter for harmonic attenuation is critical, damping of the associated resonant oscillations is important for stability. In this thesis, a Three-Loop Control (TLC) is used for the control of GTI since its damping performance is better in comparison to various other existing methods as concluded by the different analyses presented. The robustness of TLC with respect to system parameter variations and with respect to the delay due to digital implementation are also evaluated in this study. Further, the TLC method also shows effective disturbance rejection property. A method for estimating the state variables for implementing TLC is proposed, which considerably reduces the sensor count. The estimation is found to be accurate even in the presence of noise, thus ensuring the feasibility and reliability of the method with a low cost of implementation. The proposed state variable estimation based TLC method is subjected to various studies using MATLAB/SIMULINK environment and the results are validated through hardware experiments. Further, in this work, a new active method of islanding detection is proposed. Islanding is the condition wherein the DG system, along with local load, operates as a separate entity isolated from the utility grid. The GTI should detect islanding phenomenon in view of many reasons such as the safety, prevention of damage to equipment and also to aid in the transitions from the grid-connected mode of operation to islanded mode. The proposed method achieves zero Non-Detection Zone (NDZ) thereby faring better in comparison to existing passive and active methods while also ensuring no false tripping. The proposed method does not inject specific harmonics into the system and hence does not degrade the harmonic index. It has also been adapted to operate in multiple DG operation with the help of a Global Positioning System (GPS) derived signal for synchronisation of power references across different DG units. The successful determination of islanding using the proposed method is shown by simulation and is further validated in hardware.