Sarsing Gao

A Novel MATLAB Graphical User Interface Based Methodology for Analysis, Design and Capacitor Estimation of Self Excited Induction Generators

The steady state analysis of self excited induction generator (SEIG) is vital for proper implementation of induction machine operation as a generator in a stand alone mode through appropriate modeling. This paper presents a user friendly software based solution for complete evaluation of steady-state behavior of SEIG and a design tool to estimate the capacitance requirement under different operating conditions. It can also predict the performance of SEIG with different types of prime movers such as oil / bio engines, wind and small hydro turbines. The mathematical modeling of the machine is carried out and then simulated in MATLABs Graphical User Interface (GUI) environment and active windows are created with these models. As a basis for developing an attractive and easy to use design tool, some of MATLABs GUI operations are implemented in creating an active link with these models. The simulation results obtained through the presented methodology are validated through relevant experimental verification.

Self excited induction generator for renewable energy applications to supply single-phase loads in remote locations

This paper explores methodologies to use a three-phase self excited induction generator (SEIG) for providing single phase power using appropriate renewable energy sources with suitable prime movers. It presents the general operating principle and steady-state analysis of a three-phase self excited induction generator (SEIG) having star/delta connected stator winding feeding three-phase balanced/unbalanced and single-phase loads. An approach based on symmetrical component theory is employed to derive the performance equations. Analyses are carried out on different capacitor topologies to establish their suitability for single-phase operation of the three-phase SEIG. The “fsolve” optimization tool of Matlab is used to obtain the excitation frequency and saturated magnetizing reactance. The theoretical analyses and simulations are validated by experimentation on a 7.5 kW, 415 V, 14.5 A, 50 Hz, four-pole, three-phase induction machine working as SEIG. The analyses brings out the comparison between different terminal capacitor connections and highlights the merits of one scheme over the other for making right choice while feeding single-phase loads. The strategies to be adopted for different sources in using SEIG for 1- phase loads are explained.

Analysis of self excited induction generator using MATLAB GUI methodology

The steady state analysis of self excited induction generator (SEIG) is vital for proper implementation of induction machine operation as a generator in a stand alone mode through appropriate modeling. This paper presents a user friendly software based solution for complete evaluation of steady-state behavior of SEIG under different operating conditions. The mathematical modeling of the machine is carried out and then simulated in MATLABs Graphical User Interface (GUI) environment and active windows are created with these models. The simulation results obtained through the presented methodology are validated through relevant experimental verification.

Power quality analysis of hybrid renewable energy system

Abstract An hybrid renewable energy sources consisting of solar photovoltaic, wind energy system, and a microhydro system is proposed in this paper. This system is suitable for supplying electricity to isolated locations or remote villages far from the grid supply. The solar photovoltaic system is modeled with two power converters, the first one being a DC-DC converter along with an maximum power point tracking to achieve a regulated DC output voltage and the second one being a DC-AC converter to obtain AC output. The wind energy system is modeled with a wind-turbine prime mover with varying wind speed and fixed pitch angle to drive an self excited induction generator (SEIG). Owing to inherent drooping characteristics of the SEIG, a closed loop turbine input system is incorporated. The microhydro system is modeled with a constant input power to drive an SEIG. The three different sources are integrated through an AC bus and the proposed hybrid system is supplied to R, R-L, and induction motor loads. A static compensator is proposed to improve the load voltage and current profiles; it also mitigates the harmonic contents of the voltage and current. The static synchronous compensator is realized by means of a three-phase IGBT-based current-controlled voltage source inverter with a self-supporting DC bus. The complete system is modeled and simulated using Matlab/Simulink. The simulation results obtained illustrate the feasibility of the proposed system and are found to be satisfactory.

Modeling and power quality analysis of integrated renewable energy system

This paper presents modeling and power quality analysis of an integrated renewable energy system (RES) aimed at supplying electrical power to communities residing at remote locations, far from the grid supply. A decentralized power generation in the form of integrated system is proposed comprising of a solar photovoltaic (PV) system, a wind energy system (WES) and a micro hydro system (MHS) to supply required electric loads. The PV system is modeled with a dc-dc converter for regulating dc output voltage; a maximum power point tracking system (MPPT) is incorporated in order to achieve a reliable power output. The WES is modeled with a variable speed wind-turbine set with fixed pitch angle and the set drives a capacitor excited asynchronous generator (CAG). The CAG, in turn, is modeled with a closed loop turbine input system to account for the drooping characteristics of the asynchronous generator. The MHS consists of a constant power CAG. The three different sources are integrated and connected to a common ac bus and the performances of the system under varying loads are presented. A static synchronous compensator (STATCOM) is proposed in this work for reactive power compensation which, in turn, is expected to improve the power quality of the integrated system. The STATCOM is realized by means of a three-phase IGBT based current controlled voltage source inverter (CC-VSI) with a self-supporting dc bus. The complete system is modeled and simulated using Matlab/Simulink. The results obtained are presented and they are found to be satisfactory.

Mitigation of unbalanced currents in three-phase asynchronous generator supplying single-phase nonlinear load

When a three-phase asynchronous generator (AG) feeds a single-phase load, using any one of the known single-phase operation modes, the currents and voltages are grossly unbalanced. The unbalances become more prominent when the machine is feeding single-phase nonlinear loads. In this paper, analysis of a STATCOM based unbalance mitigation technique has been presented which successfully eliminates the unbalances, especially on the current waveforms. This is an encouraging result as the current unbalances are more severe compared to that of voltage unbalances as the former would otherwise lead to overheating of the machine windings which will eventually cause puncture of the insulation and accelerate ageing of the machine. The STATCOM is designed based on calculating the direct-axis and quadrature-axis components of reference currents which are converted to three-phase reference source currents with the help of Inverse Park Transformation and then compared with the actual machine currents to generate the required pulses to trigger the IGBTs of the Voltage Source Inverter (VSI). A single-phase rectifier based load is considered. The scheme is modeled using Matlab/Simulink PSB and the simulation results are presented.

A new method to determine saturated magnetizing reactance and frequency of a single-phase self excited induction generator towards steady state analysis

Steady state analysis of single-phase self excited induction generator is almost always carried out using the concepts of symmetrical components and the rotating field theories. The machine is modeled through its positive and negative sequence circuits with appropriate parameters pertaining to forward and backward fields. The final expression obtained through these analyses is a complex nonlinear equation with magnetizing reactance and frequency as two unknown quantities. Once the equation is solved and the values of magnetizing reactance and frequency precisely evaluated, the analysis of the machine performance becomes straight forward. This paper presents the use of “fsolve” optimization tool of Matlab in solving this complex equation yielding magnetizing reactance and frequency which, finally helps in the complete steady state analysis of the single-phase self excited induction generator. The method is found to be elegant and user-friendly.

Performance Analysis of a Self Excited Induction Generator with Digitally Controlled Electronic Load Controller for Micro Hydel Power Generation

This paper presents the analysis of dynamic and steady state performance of a self excited induction generator (SEIG) with digitally controlled electronic load controller (ELC) feeding single phase loads. The excitation capacitors, electronic load controller, 1-phase load in conjunction with the d-q model of the 3-phase induction machine taking into account the saturation effect are used to predict the dynamic behavior of the SEIG. The digital control is realized by means of PIC18F252 microcontroller which provides a better performance with increased operational flexibility. Both simulation and hardware results have been presented for the digitally controlled ELC, which is more compact, reliable and cost effective for providing effective voltage regulation for field applications.

Single phase power for remote area using Savonius rotor based hydropower generation

In this paper the feasibility of using Savonius rotor for hydropower generation is presented. A detailed investigation for possible generation of single phase power using the same coupled to an asynchronous generator is carried out. The complete system is modeled in MATLAB/Simulink environment, one without using any power converter and the other using an AC-DC-AC converter. The control algorithm of the system is worked out. Comparison of the performances of both the systems is presented. In order to achieve single-phase power output the three-phase 3-wire system is converted to three-phase 4-wire system using a transformer with turns-ratio of 1:1. An LCL filter is used to smoothen the ac output.

Harnessing hydroelectric power using Savonius rotor coupled with asynchronous generator connected to grid

The present investigation is aimed at exploring the feasibility of using vertical axis turbine which, otherwise, is ideally suited for wind energy conversion system (WECS), for hydropower generation. River water currents are potentially significant and reliable source of power generation and currently no significant work has been carried out to tap this source of energy. Electrical energy can be efficiently extracted from these free running rivers using vertical axis rotors that are similar in design and function to wind turbines but extract energy through hydrodynamic rather than aerodynamic mechanism. This paper presents possible generation of electrical power using Savonius rotor by coupling it with asynchronous generator, connected directly to grid. The model of each part such as Savonius rotor, asynchronous generator, and transmission line is proposed using MATLAB/Simulink. The model is tested for different velocities of river water and results are presented.