Role of Reactive Power Source on Power Quality of Three-Phase Self-Excited Induction Generator (original) (raw)
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As a promising renewable alternative, the wind power is one of the significant sources of generation. Reactive power compensation and harmonic reduction in a low voltage distribution networks for integration of wind power to the grid are the main issues addressed in this paper. This paper proposes a control scheme based on instaneous Pq theory for compensating the reactive power requirement of a three phase grid connected wind driven induction generator as well as the harmonics produced by the non linear load connected to the PCC using STATCOM. The proposed control scheme is simulated using MATLAB/SIMULINK. The Simulation results are presented in this paper.
Energies, 2014
Incentives, such as the Feed-in-tariff are expected to lead to continuous increase in the deployment of Small Scale Embedded Generation (SSEG) in the distribution network. Self-Excited Induction Generators (SEIG) represent a significant segment of potential SSEG. The quality of SEIG output voltage magnitude and frequency is investigated in this paper to support the SEIG operation for different network operating conditions. The dynamic behaviour of the SEIG resulting from disconnection, reconnection from/to the grid and potential operation in islanding mode is studied in detail. The local load and reactive power supply are the key factors that determine the SEIG performance, as they have significant influence on the voltage and frequency change after disconnection from the grid. Hence, the aim of this work is to identify the optimum combination of the reactive power supply (essential for self excitation of the SEIG) and the active load (essential for balancing power generation and demand). This is required in order to support the SEIG operation after disconnection from the grid, during islanding and reconnection to the grid. The results show that the generator voltage and speed (frequency) can be controlled and maintained within the statuary limits. This will enable safe disconnection and reconnection of the SEIG from/to the grid and makes it easier to operate in islanding mode.
Abstract— An induction generator or asynchronous generator is a type of AC electrical generator that uses the principles of induction motors to produce power. Induction generators operate by mechanically turning their rotor faster than the synchronous speed, giving negative slip. A regular AC asynchronous motor usually can be used as a generator, without any internal modifications. Induction generators are useful in applications such as mini hydro power plants, wind turbines, or in reducing high-pressure gas streams to lower pressure, because they can recover energy with relatively simple controls. An induction generator must be excited with a leading voltage; this is usually done by connection to an electrical grid, or sometimes they are self excited by using phase correcting capacitors.
IET Renewable Power Generation, 2021
The paper presents the performance analysis-based reliability estimation of a self-excited induction generator (SEIG) using the Monte-Carlo simulation (MCS) method with data obtained from a self-excited induction motor operating as a generator. The global acceptance of a SEIG depends on its capability to improve the system's poor voltage regulation and frequency regulation. In the grid-connected induction generator, the magnetizing current is drawn from the grid, making the grid weak. In contrast, in the SEIG standalone operation, an external capacitor arrangement is implemented to render the reactive power support. This capacitor arrangement is connected across the stator terminals during the stand-alone configuration of SEIG. The capacitor serves two purposes, which include voltage build-up and power factor improvement. Therefore, the paper deals with obtaining the minimum capacitor value required for SEIG excitation in isolated mode applications, including stand-alone wind power generation. The SEIG performance characteristics have been evaluated for different SEIG parameters. The simulation and experimental results are then compared and found satisfactory. Then, SEIG reliability is estimated considering the MCS method utilizing SEIG excitation's failure and success rates during experimental work in the laboratory. Finally, the SEIG reliability evaluation is performed considering different wind speeds. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Three Phase Self-Excited Induction Generator for Renewable Energy Generation
Renewable energy generation has emerged as a thrust area in energy technologies in the recent times. Amongst various generation systems based on renewable sources, wind electricity generation has proved to be most beneficial. One of the most important aspects for such applications is choice of generator. The self excited induction generators (SEIGs) are considered to be most suitable generating devices for wind and mini/micro hydro generation due to their rugged and maintenance free construction. This paper presents steady state analysis of a three phase self excited induction generator for wind energy application. The simulations are carried out by generating programs in MATLAB Mfile to obtain various performance characteristics of the developed three phase SEIG model. A detailed discussion is carried out on different operational aspects of these machines on the basis of reported results.
The European Physical Journal Applied Physics, 2008
A considerable number of communities throughout the world, most of them isolated, need hybrid energy solutions either for rural electrification or for the reduction of diesel use. Despite several research projects and demonstrations which have been conducted in recent years, wind-diesel technology remains complex and much too costly. Induction generators are the most robust and common for wind energy systems but this option is a serious challenge for electrical regulation. When a wind turbine is used in an off-grid configuration, either continuously or intermittently, precise and robust regulation is difficult to attain. The voltage parameter regulation option, as was experienced at several remote sites (on islands and in the arctic for example), is a safe, reliable and relatively simple technology, but does not optimize the wave quality and creates instabilities. These difficulties are due to the fact that no theory is available to describe the system, due to the inverse nature of the problem. In order to address and solve the problem of the unstable operation of this wind turbine generator, an innovative approach is described, based on a different induction generator single phase equivalent circuit.
2014
Incentives, such as the Feed-in-tariff are expected to lead to continuous increase in the deployment of Small Scale Embedded Generation (SSEG) in the distribution network. Self-Excited Induction Generators (SEIG) represent a significant segment of potential SSEG. The quality of SEIG output voltage magnitude and frequency is investigated in this paper to support the SEIG operation for different network operating conditions. The dynamic behaviour of the SEIG resulting from disconnection, reconnection from/to the grid and potential operation in islanding mode is studied in detail. The local load and reactive power supply are the key factors that determine the SEIG performance, as they have significant influence on the voltage and frequency change after disconnection from the grid. Hence, the aim of this work is to identify the optimum combination of the reactive power supply (essential for self excitation of the SEIG) and the active load (essential for balancing power generation and demand). This is required in order to support the SEIG operation after disconnection from the grid, during islanding and reconnection to the grid. The results show that the generator voltage and speed (frequency) can be controlled and maintained within the statuary limits. This will enable safe disconnection and reconnection of the SEIG from/to the grid and makes it easier to operate in islanding mode.
State modelling of self-excited induction generator for wind power applications
Wind Energy, 2006
The increase in wind power production with self-excited induction generators (SEIGs) has led to new kinds of protection and stability problems. Suitable state models of a wind plant with SEIGs must accurately simulate balanced and unbalanced transient phenomena for adequate calibration and control of protection devices. However, the SEIG models currently available are unable to simulate the neutral current following unbalanced faults for forecasting the SEIG insulation and protection needed against some network stresses. In addition, the saturation model commonly used is not flexible when deriving a state model. This article presents an effective electromechanical state model for transient analysis of a saturated SEIG for wind power applications. A neutral connection through impedance is included for exact modelling of a Park wye-connected SEIG. Simple-shunt and short-shunt (series) configurations are explored. A comparative analysis of the effects of these two types of configuration on the steady state and transient performances of an SEIG is presented. Numerical and experimental data obtained with a 380 V, 5•5 kVA, 11•9 A, 50 Hz induction generator are presented to attest to the effectiveness of the proposed SEIG modelling framework. Among the results obtained, simulations show that the simple-shunt configuration produces poor voltage regulation, possible voltage collapse and inherent protection against short-circuit faults, while the short-shunt connection provides better voltage variation but needs to be well protected against short-circuit faults.
2017
Wind turbines convert wind energy into electrical energy. Variable speed wind turbines are most used wind turbines now a days due to its advantages. Different types of generators are used in the wind turbine systems (WTS). The comparative study of different types of generators in wind turbines are briefly explained in this paper. Today more and more wind farms are connected into the power grid. The active power at the output of wind farms is variable and intermittent due to the changeable wind speed, which affects the voltage stability problems in power grids. More reactive power is demanded to maintain the voltage when it drops. The doubly-fed induction generator (DFIG) is widely used in wind farms because it has many advantages. The reactive power control is mainly achieved by two modes, i.e. power factor control and voltage control.
Performance improvement of three-phase self-excited induction generator feeding induction motor load
TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES, 2015
In this paper, the transient and steady-state performances of an isolated self-excited induction generator driven by a wind turbine and feeding power to a dynamic load such as a three-phase induction motor are analyzed. Mathematical modeling and simulation study of the whole system, including the wind turbine, induction generator, capacitor, pulse width modulated voltage source inverter, and dynamic load, are carried out with closed-loop voltage and frequency controller. The complete system is modeled in the stationary d−q frame and validated by comparing simulation and experimental results at no-load. The same mathematical model is then used to study the transient performance of the self-excited induction generator supplying to a dynamic load. When the induction motor is connected to the induction generator without any voltage and frequency controller, it causes severe transients in electrical and mechanical variables of the generator. Due to the large starting-current requirement of the induction motor, there is a collapse of the terminal voltage of the generator. A bidirectional pulse width modulated source inverter with DC link battery is connected with the generator and operated in closed-loop control mode to maintain voltage and frequency and to operate the induction motor successfully with variable wind speed and mechanical load.