Variable-speed Prime Mover Research Articles

Steady state and dynamic performance of self-excited induction generator using FACTS controller and teaching learning-based optimization algorithm

PurposeThe paper aims to present an application of teaching learning-based optimization (TLBO) algorithm and static Var compensator (SVC) to improve the steady state and dynamic performance of self-excited induction generators (SEIG).Design/methodology/approachThe TLBO algorithm is applied to generate the optimal capacitance to maintain rated voltage with different types of prime mover. For a constant speed prime mover, the TLBO algorithm attains the optimal capacitance to have rated load voltage at different loading conditions. In the case of variable speed prime mover, the TLBO methodology is used to obtain the optimal capacitance and prime mover speed to have rated load voltage and frequency. The SVC of fixed capacitor and controlled reactor is used to have a fine tune in capacitance value and control the reactive power. The parameters of SVC are obtained using the TLBO algorithm.FindingsThe whole system of three-phase induction generator and SVC are established under MatLab/Simulink environment. The performance of the SEIG is demonstrated on two different ratings (i.e. 7.5 kW and 1.5 kW) using the TLBO algorithm and SVC. An experimental setup is built-up using a 1.5 kW three-phase induction machine to confirm the theoretical analysis. The TLBO results are matched with other meta heuristic optimization techniques.Originality/valueThe paper presents an application of the meta-heuristic algorithms and SVC to analysis the steady state and dynamic performance of SEIG with optimal performance.

Analysis of wind driven self-excited induction generator supplying isolated DC loads

This paper presents the analysis, modelling and simulation of wind-driven self-excited induction generator (SEIG). The three-phase SEIG is driven by a variable-speed prime mover to represent a wind turbine. Also, the paper investigates the dynamic performance of the SEIG during start-up, increasing or decreasing the load or rotor speed. The value of the excitation capacitance required for the SEIG is calculated to give suitable saturation level to assure self-excitation and to avoid heavy saturation levels. Matching of the maximum power available from the wind turbine is performed through varying the load value. The effect of AC–DC power conversion on the generator is investigated. The system simulation is carried out using MATLAB/SIMULINK toolbox program.

Capacitive VAr requirements for wind driven self-excited induction generators

Abstract This paper presents the capacitive VAr requirements of a three phase pole changing self-excited induction generator and a single phase self-excited induction generator, used as isolated power sources by a constant speed or a variable speed prime mover, to obtain the desired voltage regulation at various values of load and speed. Different performance criteria such as constant terminal voltage or constant air gap flux have been considered. The developed mathematical model using nodal analysis based on graph theory is quite general in nature and can be used for any combination of the unknown variables such as magnetizing reactance (XM) and frequency (F) or capacitive reactance (XC) and frequency (F) or capacitive reactance (XC) and speed (υ). The proposed model completely avoids the tedious and erroneous manual work of segregating the real and imaginary components of the complex impedance of the machine for deriving the specific model for each operating modes. Moreover, any element, like the core loss component, can be included or excluded from the model if required. Next, to obtain the capacitive VAr requirements of a three phase pole changing self-excited induction generator and a single phase self-excited induction generator, a fuzzy logic approach is used for the first time to find the unknown variables using the above model. The results are presented in a normalized form so that they are valid for a wide range of machines and would be useful for the design of voltage regulators for such generators.

Matlab Simulink Based DQ Modeling and Dynamic Characteristics of Three Phase Self Excited Induction Generator

In this paper, DQ-modeling approach for Transient State analysis in the time domain of the three- phase self-excited induction generator (SEIG) with squirrel cage rotor is presented along with its operating performance evaluations. The three-phase SEIG is driven by a variable-speed prime mover (VSPM) such as a wind turbine for the clean alternative renewable energy in rural areas. Here the prime mover speed has been taken both as fixed and variable and results have been analyzed. The basic Dynamic characteristics of the VSPM are considered in the three-phase SEIG approximate electrical equivalent circuit and the operating performances of the three-phase SEIG coupled by a VSPM in the Transient state analysis are evaluated and discussed on the conditions related to transient occurs in the system and speed changes of the prime mover. The whole proposed system has been developed and designed using MATLAB/SIMULINK.

Static VAR Compensator-Based Voltage Regulation for Variable-Speed Prime Mover Coupled Single-Phase Self-Excited Induction Generator

In this paper, the single-phase static VAR compensator (SVC) is applied to regulate and stabilize smoothly the generated output voltage of the single-phase self-excited induction generator (single-phase SEIG) driven by a variable-speed prime mover (VSPM) under the conditions of inductive load variations and prime mover speed changes. The conventional fixed gain PI controller-based feedback control scheme is employed to adjust the equivalent capacitance of the single-phase SVC composed of the fixed excitation capacitor (FC) in parallel with the thyristor switched capacitor (TSC) and the thyristor controlled reactor TCR. A PI closed-loop feedback voltage control scheme based on the SVC for the single-phase SEIG coupled by a VSPM prototype set-up is established. The closed-loop feedback output voltage responses in the single-phase SEIG coupled by a VSPM with different inductive load variations using the single-phase SVC with the PI controller are considered and discussed herein. Based on the SVC with the PI controller closed-loop feedback voltage regulation scheme, the experimental results for the single-phase SEIG driven by a VSPM are illustrated and proved its practical effectiveness in terms of the fast response and the high performances.

Static VAR compensator-based voltage control implementation of single-phase self-excited induction generator

A single-phase static VAR compensator (SVC) is proposed to regulate smoothly the output voltage of a single-phase self-excited induction generator (single-phase SEIG) driven by a variable-speed prime mover (VSPM) due to inductive load and prime mover speed variations. A PI feedback closed-loop voltage regulation scheme is presented to adjust the equivalent excitation capacitance of the single-phase SVC. The SVC is composed of a fixed excitation capacitor (FC), thyristor switched capacitor (TSC) and thyristor controlled reactor (TCR). The steady-state single-phase SEIG output voltage and the TCR triggering angle responses of the proposed scheme are simply evaluated and discussed. A small-scale single-phase SEIG voltage control prototype is designed in order to verify system viability and assess its performance. System dynamic operation is studied based on experimental results. Simulation and experimental results prove system practical effectiveness in terms of fast response and high performance.

Terminal Voltage Regulation Characteristics by Static Var Compensator for a Three-Phase Self-Excited Induction Generator

In this paper, the practical impedance approach steady-state analysis in the frequency domain for the three-phase self-excited induction generator (SEIG) with squirrel-cage rotor is presented along with its operating performance evaluations. The three-phase SEIG is driven by a variable-speed prime mover(VSPM) in addition to a constant-speed prime mover (CSPM) such as a wind turbine and a micro gas turbine for clean alternative renewable energy in rural areas. The basic steady-state characteristics of the VSPM are considered in the three-phase SEIG approximate equivalent circuit and the operating performance of the three-phase SEIG coupled with a VSPM and/or a CSPM are evaluated and discussed online under the conditions related to the speed changes of the prime mover and the electrical inductive load power variations with simple computation processing procedures. A three-phase SEIG prototype setup with a VSPM is implemented for small-scale clean renewable and alternative energy utilizations. The experimental performance results give good agreement with those obtained from the simulation results. Furthermore, a proportional-integral (PI) closed-loop feedback voltage regulation of the three-phase SEIG driven by the VSPM on the basis of the static var compensator (SVC) composed of the thyristor phase-controlled reactor in parallel with the thyristor switched capacitor and the fixed-excitation capacitor bank is designed and considered for the wind generation as a renewable power conditioner. The simulation analysis and experimental results obtained from the three-phase SEIG with SVC for its voltage regulation prove the practical effectiveness of the additional SVC with the PI-controller-based feedback loop in steady-state operation in terms of high performance with low cost.

THE DOUBLY-FED MACHINE WITH PASSIVE ROTOR SUPPLY IMPEDANCE OPERATING AS A VSCF GENERATOR-A SLIP DEPENDENT MATHEMATICAL MODEL

ABSTRACT The paper presents a mathematical model for a doubly-fed induction generator driven by a variable-speed prime mover. The primary circuit of the generator is supplied at rated frequency and output power is obtained from the secondary circuit. The components of power generated by the machine are presented. The steady-state stability limits of the generator are investigated. Comparison between the predicted and experimental results shows that although the model is simple, good agreement is obtained.

Wind-energy recovery by a static Scherbius induction generator

The paper describes a technique for controlling a doubly fed induction generator driven by a windmill, or other form of variable-speed prime mover, to provide power generation into the national grid system. The secondary circuit of the generator is supplied at a variable frequency from a current source inverter which for test purposes is rated to allow energy recovery, from a simulated windmill, from maximum speed to standstill. To overcome the stability problems normally associated with doubly fed machines a novel signal generator, which is locked in phase with the rotor EMF, controls the secondary power to provide operation over a wide range of subsynchronous and supersynchronous speeds. Consideration of power flow enables the VA rating of the secondary power source to be determined as a function of the gear ratio and online operating range of the system. A simple current source model is used to predict performance which is compared with experimental results. The results indicate a viable system, and suggestions for further work are proposed