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This research presents a high frequency-based algorithm for zonal protection of meshed Multi-Terminal high voltage Direct Current (MTDC) systems. Discrete wavelet transform (DWT) is used to capture high frequency current transients from one end of each line. The faulty line is identified by analyzing two distinct high frequency bands form the captured transients. The characteristics of these current transients during normal condition are different from faulty condition. A four-terminal meshed MTDC model is used to test the performance of the protection algorithm. Various faults with different fault scenarios were simulated using four-terminal meshed MTDC model. The simulation results showed success of the algorithm in identifying internal faults. Moreover, the high frequency algorithm showed robustness against other abnormal conditions such as AC faults and sudden change of wind power.

Due to the large variety of renewable power sources, power electronics play an important role in energy conversion. Different power converter topologies are used to interface distributed power generation systems (DPGS) with the utility network. Introduction of power electronics for DPGS provide several advantages such as energy optimal operation by employing a control algorithm to extract the maximum available power. In addition, load control, reduced noise, controllable active and reactive power and improved power quality. These achievements are further improved by digital control systems. The analysis presented in this paper shows the relations of how the stability margins and the transient response criteria are related to the sampling frequency, computational delay and controller gains. The procedure followed can be applied to any filter order with any number of samples of control delay at any sampling frequency. This gives a straightforward method for optimal tuning of the stationary frame AC current controllers with the required stability margins and transient response characteristics. The concluded assumptions were simulated & verified through Matlab/Simulink.

Due to the large variety of renewable power sources, power electronics play an important role in energy conversion. Different power converter topologies are used to interface distributed power generation systems (DPGS) with the utility network. Introduction of power electronics for DPGS provide several advantages such as energy optimal operation by employing a control algorithm to extract the maximum available power. In addition, load control, reduced noise, controllable active and reactive power and improved power quality. Using a LCL filter to ensure that high quality power is delivered comes at the expense of degraded stability unless mitigation procedures are followed. In this paper, a stationary frame current control for inverter-based distributed generation (IBDG) with sensorless active damped LCL filter is proposed. The Kalman filter sensorless-based technique not only mitigates the stability problem regarding the resonance of the LCL filter, but it improves the overall stability margins. The concluded assumptions were simulated through Matlab/Simulink and verified experimentally with a laboratory prototype.

Due to the rapid growth of the electric energy demands, the necessity of involvement of distributed generation (DG) to overcome this demand became a must. When distributed generation renewable energy sources are coupled to the grid through a DC-AC inverter, the injected currents to the grid should be characterized by high quality and low distortion. Many factors play an important role to produce high quality output beginning with the order of the passive filter used, type of controller used and last but not least the presence of distortions in the grid. This paper demonstrates the evaluation of performance, in normal and abnormal grid conditions, between single and dual loop control for the three phase inverter tied to the grid through a LCL passive filter and controlled with discrete proportional resonant (PR) controller, taking into account how filter parameters, control gains and sampling frequency would affect the dynamics of the system as well as its stability in order to perform adequate tuning. The concluded assumptions were simulated & verified through Matlab/Simulink.

The fact distribution generation (DG) importance is growing rapidly in the recent years where the coupling between DG sources and the grid is done through inverters where exporting low distorted currents and high quality output power that copes with IEEE standards are main concerns. This paper demonstrates the regulation of the inverter current using proportional resonant (PR) controller that adapts to the grid voltage frequency to ensure reliable operation. Also to improve the quality of the output, an LCL passive filter is used as well as a demonstration of an alternative easier approach to achieve virtual damping of the resonance effect of the filter and construct an inner control loop improving robustness and stability simultaneously. The proposed concept has been simulated using Matlab Simulink for a 4KW IBDG.

Mechanical gearboxes are typically employed with doubly-fed induction generator-based wind turbines. The main drawback of this solution is the gearbox's reliability and maintenance. Using magnetic gearbox in conjunction with the doubly-fed induction generator is an emerging alternative being promoted by the research community which maintains the reduced size doubly-fed machine and overcomes the mechanical gearbox problems reported by field experience. This paper proposes a novel magnetic gearbox configuration in which a conventional planetary magnetic gearbox is equipped with n-phase coils fitted around the ferromagnetic pole-pieces to extract output electrical power. The turbine mechanical power is thus divided into mechanical power to drive the electrical generator and extra electrical power that can be diverted into a storage system to perform the power leveling function. The proposed configuration can also be used to freely modify the power-speed characteristic as seen by the electrical generator, a highly needed feature for grid frequency support.

The Inter feeder Power Flow Regulator (IFPFR) proposed in this paper consists of several voltage source inverters with common dc bus; each inverter is connected in series with one of different independent distribution feeders in the power system. This paper is concerned with how to transfer power between the feeders for load sharing purpose. The power controller of each inverter injects the power (for sending feeder) or absorbs the power (for receiving feeder) via injecting suitable voltage; this voltage injection is simulated by voltage drop across series virtual impedance, the impedance value is selected to achieve the concept of power exchange between the feeders without perturbing the load voltage magnitude of each feeder. In this paper a new control scheme for load sharing using IFPFR is proposed.