Solar Photovoltaic (PV) systems have been in use predominantly since the last decade. Inverter fed PV grid topologies are being used prominently to meet power requirements and to insert renewable forms of energy into power grids. At present, coping with growing electricity demands is a major challenge. This paper presents a detailed review of topological advancements in PV-Grid Tied Inverters along with the advantages, disadvantages and main features of each. The different types of inverters used in the literature in this context are presented. Reactive power is one of the ancillary services provided by PV. It is recommended that reactive power from the inverter to grid be injected for reactive power compensation in localized networks. This practice is being implemented in many countries, and researchers have been trying to find an optimal way of injecting reactive power into grids considering grid codes and requirements. Keeping in mind the importance of grid codes and standards, a review of grid integration, the popular configurations available in literature, Synchronization methods and standards is presented, citing the key features of each kind. For successful integration with a grid, coordination between the support devices used for reactive power compensation and their optimal reactive power capacity is important for stability in grid power. Hence, the most important and recommended intelligent algorithms for the optimization and proper coordination are peer reviewed and presented. Thus, an overview of Solar PV energy-fed inverters connected to the grid is presented in this paper, which can serve as a guide for researchers and policymakers.

This paper proposes a standalone single stage PV fed PMSM drive for water pumping. The proposed system aims at reducing the switching losses and overall cost by using reduced switch inverter (RSI). The proposed system comprises of a PMSM drive, fed by PV source through an inverter employing reduced number of switches. The inverter uses only four switches whereas the conventional VSI utilizes six switches. Field oriented control scheme is employed to control the PMSM drive. Perturb and Observe (P&O) MPPT technique is used to generate a speed reference to PMSM drive. Simulation studies for the proposed PV fed PMSM driven water pumping system are performed using MATLAB platform and it is also experimentally verified through FPGA controller based 400 W laboratory prototype PMSM drive and results demonstrates the efficacy of the system.

This paper proposes simple and robust electromagnetic torque based MRAS speed estimator with cascaded Pseudo Derivative Feedback (PDF) controller is proposed for sensorless SMPMSM drive to improve its performance at standstill and low speed regions. The proposed estimator is formed using instantaneous and estimated electromagnetic torque. Using small signal modelling, the stability and sensitivity analysis are performed. Results show that, the estimator is stable over a wide speed region (including low speed regions) and exhibits robustness against uncertainties in machine parameters. The proposed estimator is implemented for 1.5 kW laboratory prototype SMPMSM drive using FPGA ALTERA cyclone II. Experimental results demonstrate the efficacy of the proposed scheme under different test conditions viz. over a wide adjustable speed range which include different low speed regions and standstill i.e. 157 to -157 rad/s at different load conditions with uncertainty in machine parameters.

In this paper, a multistage MRAS speed estimator is formulated based on stator flux and electromagnetic torque quantities is proposed for reduced switch inverter (RSI) fed sensorless PMSM drive. The proposed configuration aims to eliminate speed sensor and reduce the switching losses, overall cost of the system. The proposed MRAS speed estimator is developed by utilizing instantaneous value of electromagnetic torque and stator flux. The proposed speed estimator’s stability is verified using the small signal model technique. The experimental results demonstrate the performance of the proposed scheme for laboratory prototype 400 W PMSM drive. Further the machine parameter sensitivity is tested to show the robustness of the speed estimator. It is inferred that, estimated position and speed error are 5.1° and 3.8 rad/s during entire speed region at transient condition.

Grid integration of distributed energy resources (DER) has become a technical challenge in the distribution network operation due to the intermittent nature of renewable energy sources and their impact on grid voltage stability. Thus, a Dynamic Voltage Restorer (DVR) is installed in the distribution network system to reduce such grid voltage impact on sensitive loads. In this paper, a Pseudo Derivative Feedback (PDF) based voltage controller is implemented for effective operation of DVR under voltage disturbances. Response of DVR primarily depends upon its controller action. This paper address the issues in conventional P and PI multiloop controller with and without feedforward path then proposes PDF control strategy for DVR. Using proposed controller, dynamic performance of DVR is improved. The efficacy of proposed controller is illustrated by comparative study with conventional P and PI controller using time response and relative stability analysis. Finally, PSCAD simulation studies for a 10 kV medium voltage DVR and experimental results using a low voltage laboratory prototype DVR are presented to prove robustness of proposed controller for DVR under symmetric and asymmetric voltage sags.