Engineering Commons^™

Numerical And Experimental Study Of The Trichel Pulses In Needle-Plane Geometry, Peyman Dordizadeh Basirabad

Electronic Thesis and Dissertation Repository

One of the unique aspects of the negative corona discharges in the air is the regular train of pulses that form the discharge current, called Trichel pulses. These pulses are the result of the combination of several phenomena such as the avalanche ionization of the neutral molecules by the impact of the energized electrons, formation of the cloud of positive ions close to the cathode, and formation of the cloud of negative ions at a farther distance from the corona electrode compared to their positive counterparts. In this thesis, the results of a detailed numerical investigation of the formation of …

Analysis And Mitigation Of Temporary Over-Voltage (Tov) Phenomenon In Unintentionally Islanded Grid-Connected Photovoltaic (Pv) Inverters, Md Maruful Islam

Electronic Thesis and Dissertation Repository

Grid-connected photovoltaic (PV) solar systems, like other inverter-based distributed generators, can cause temporary over-voltages (TOVs), especially subsequent to faults and unintentional islanding incidents, and can damage equipment and customers within the host distribution network. Thus, this thesis aims to study the phenomenon and propose corrective measures for it. Thus, the thesis first presents detailed models for a conventional single-stage PV system and a modified single-stage PV system. The conventional system uses a Δ/YG isolation transformer, whereas the modified system, proposed in the literature, assumes a Y/YG isolation transformer that is effectively grounded by an additional half-bridge leg energized by the …

Optimal Scheduling Of Energy Storage For Energy Shifting And Ancillary Services To The Grid, Hadi Khani

Electronic Thesis and Dissertation Repository

This thesis is mainly focused on developing optimization-based models for scheduling of energy storage units. At first, a real-time optimal scheduling algorithm is developed seeking to maximize the storage revenue by exploiting arbitrage opportunities available due to the inter-temporal variation of electricity prices. The electricity price modulation is proposed as an approach to competitively offer incentive by the utility regulator to storage to fill the gap between current and a stable rate of return. Subsequently, the application of large-scale storage for congestion relief in transmission systems as an ancillary service to the grid is investigated. An algorithm is proposed for …

State Space Modeling Of Smart Pv Inverter As Statcom (Pv-Statcom) For Voltage Control In A Distribution System, Sridhar Bala Subramanian

Electronic Thesis and Dissertation Repository

The grid integration of photovoltaic (PV) systems in distribution networks is facing challenges such as transient changes in voltage due to fluctuations in generated real power and tripping of PV systems. Smart PV inverters with functions such as dynamic reactive current injection and low voltage ride through are available to mitigate these challenges. This thesis shows that a better stable performance can be obtained if these functions are implemented using the novel patent-pending technology of PV system as a dynamic reactive power compensator (PV-STATCOM). A linearized state space model of PV-STATCOM is developed to show the benefits of PV-STATCOM controls …

Sensorless Rotor Position Estimation For Brushless Dc Motors, Iram G. Raza

Electronic Thesis and Dissertation Repository

Brushless DC motor speed is controlled by synchronizing the stator coil current with rotor position in order to acquire an accurate alignment of stator rotating field with rotor permanent-magnet field for efficient transfer of energy. In order to accomplish this goal, a motor shaft is instantly tracked by using rotating rotor position sensors such as Hall effect sensors, optical encoders or resolvers etc. Adding sensors to detect rotor position affects the overall reliability and mechanical robustness of the system. Therefore, a whole new trend of replacing position sensors with sensorless rotor position estimation techniques have a promising demand.

Among the …