Change In Terminal Voltage Research Articles

Genetic Algorithm-Based Fuzzy Controller for Improving the Dynamic Performance of Self-Excited Induction Generator

This paper introduces a new hybrid controller using artificial intelligence (AI) techniques to improve the dynamic performance of the self-excited induction generator “SEIG” driven by wind energy conversion scheme “WECS”. The hybrid AI compromises a genetic algorithm (GA) and fuzzy logic controller (FLC). The role of the GA is to optimize the parameters of the fuzzy set to ensure a better dynamic performance of the overall system. The proposed controller is developed in two loops of the WECS scheme under study. The first loop is used to regulate the terminal voltage, by adjusting the self-excitation. This controller represents the reactive power control. In this case, the FLC will utilize the error and its change in terminal voltage to regulate the duty cycle of the capacitor bank. The second loop is used to adjust the mechanical power, by adapting the blade angle of WECS. Here, the FLC uses the frequency error and its change to adjust the blade angle of the wind turbine to control the active power input. The simulation results, which cover a wide range of electrical and mechanical disturbances, depict the effectiveness of the proposed controller compared with other AI techniques.

Research on Small Synchronous Generator Excited System Based on Fuzzy Control

This article describes the small synchronous generator excitation control device characteristics and working principle is proposed based on fuzzy control of excitation regulator device on-site test method. Phase compound excitations with voltage corrector by the way of magnetic amplifier were used in excitation devices. The generator terminal voltage, load current and power factor and other parameters were adjusted by fuzzy control through automatic control phase compound excitation transformer. For separate generator, the major factor of terminal voltage change was caused by the change of reactive current, in order to keep constant voltage generator excitation current mast be adjusted. At the end of the paper the problems and countermeasures in the course of debugging process were analyzed.

Characteristics of optimum power extraction in a MHD generator with subsonic and supersonic inlets

Analytical expressions for optimum power extracted in a MHD generator with constant channel width and constant electrical conductivity proposed by Neuringer was investigated for a range of subsonic and supersonic inlet Mach numbers. Characteristics of fluid-dynamical variables, optimum power extracted and the voltage drop in the external load were studied for a range of Mach numbers and interaction parameters. It was observed that the characteristics of voltage drop across the load with the interaction parameter differed significantly for subsonic and supersonic inlet Mach numbers. For each subsonic inlet Mach number, there exists a critical value of interaction parameter beyond which there is an abrupt change in terminal voltage, and fluid-dynamic variables. Also beyond this critical interaction parameter, the flow at the exit plane is choked. Supersonic inlets do not display the presence of such a critical interaction parameter or choking at the exit plane.

State-of-Charge Determination From EMF Voltage Estimation: Using Impedance, Terminal Voltage, and Current for Lead-Acid and Lithium-Ion Batteries

State-of-charge (SOC) determination is an increasingly important issue in battery technology. In addition to the immediate display of the remaining battery capacity to the user, precise knowledge of SOC exerts additional control over the charging/discharging process, which can be employed to increase battery life. This reduces the risk of overvoltage and gassing, which degrade the chemical composition of the electrolyte and plates. The proposed model in this paper determines the SOC by incorporating the changes occurring due to terminal voltage, current load, and internal resistance, which mitigate the disadvantages of using impedance only. Electromotive force (EMF) voltage is predicted while the battery is under load conditions; from the estimated EMF voltage, the SOC is then determined. The method divides the battery voltage curve into two regions: 1) the linear region for full to partial SOC and 2) the hyperbolic region from partial to low SOC. Algorithms are developed to correspond to the different characteristic changes occurring within each region. In the hyperbolic region, the rate of change in impedance and terminal voltage is greater than that in the linear region. The magnitude of current discharge causes varying rates of change to the terminal voltage and impedance. Experimental tests and results are presented to validate the new models.

Intelligent particle swarm optimized fuzzy PID controller for AVR system

In process plants like thermal power plants, biomedical instrumentation the popular use of proportional-integral-derivative (PID) controllers can be noted. Proper tuning of such controllers is obviously a prime priority as any other alternative situation will require a high degree of industrial expertise. So in order to get the best results of PID controllers the optimal tuning of PID gains is required. This paper, thus, deals with the determination of off-line, nominal, optimal PID gains of a PID controller of an automatic voltage regulator (AVR) for nominal system parameters and step reference voltage input. Craziness based particle swarm optimization (CRPSO) and binary coded genetic algorithm (GA) are the two props used to get the optimal PID gains. CRPSO proves to be more robust than GA in performing optimal transient performance even under various nominal operating conditions. Computational time required by CRPSO is lesser than that of GA. Factors that have influenced the enhancement of global searching ability of PSO are the incorporation of systematic and intelligent velocity, position updating procedure and introduction of craziness. This modified from of PSO is termed as CRPSO. For on-line off-nominal system parameters Sugeno fuzzy logic (SFL) is applied to get on-line terminal voltage response. The work of SFL is to extrapolate intelligently and linearly, the nominal optimal gains in order to determine off-nominal optimal gains. The on-line computational burden of SFL is noticeably low. Consequently, on-line optimized transient response of incremental change in terminal voltage is obtained.

Fuzzy based coordinated controller for power system stability and voltage regulation

This paper deals with the design of a fuzzy based coordinated controller to prevent an electric power system losing synchronism after a large sudden fault and to achieve good post-fault voltage level. The developed controller has a fuzzy logic unit (FLU) which, accepts change in terminal voltage and speed deviation as its inputs and generates the required weightage for the transient controller and voltage controller. The performance of the proposed controller is compared with those existing control switching coordinate controller. The simulation study is carried out for the configuration of a single machine infinite bus power system.

DYNAMIC BEHAVIOR OF VARIABLE SPEED PUMP STORAGE UNITS IN THE GERMAN ELECTRIC POWER SYSTEM

This paper reports about simulation studies carried out in connection with the new pump storage power plant Goldisthal of the German power company VEAG. Two units are equipped with double fed induction machine drives and thus they are able to vary the speed. A simulation model was developed to investigate the dynamic behavior of the units in interaction with the power system. As a result of a systematic multivariable controller design active and reactive power control channels are decoupled. The controller used in this study shows a Dead-Beat-behavior. A special feature of the controller is its ability to compensate terminal voltage changes. Simulation results in a model of the German and European Interconnected Power System demonstrate the control capabilities of the variable speed units.

ANN Based Power System Stabilizers for Large Synchronous Generators

This paper presents an artificial neural network based power system stabilizer (ANNPSS) for excitation control for a large synchronous generator. The generator operates over a wide range of operating conditions and is subjected to different types of disturbances and emergency states. A 300 MW turbogenerator is used to generate appropriate training data for the ANN controller. Off-line simulations using a suitable conventional PSS to control the generator for different working conditions are used to generate training input-output pairs. A multi-layered back propagation (BP) ANN is utilised to design the ANN based controller where speed error deviation and the incremental change in machine terminal voltage are fed to the ANNPSS controller. The proposed ANNPSS and conventional PSS are compared and test results indicate that the ANN based controller is more adaptive and flexible than conventional stabilizers and show a good performance over a wide range of operating conditions and disturbances.

Self-detection characteristics of the Sagnac frequency shift in a mechanically rotated semiconductor ring laser

Self-detection of the frequency difference between the two counter propagating oscillation frequencies in a mechanically rotated semiconductor ring laser (SRL) was successfully demonstrated. An SRL used for experiments consisted of a pig-tailed laser diode amplifier module. Detection characteristics of an SRL as an optical gyroscope were investigated and discussed. Beat frequency, which was detected by the terminal voltage change of an SRL without branching the circulating optical power, was measured as a function of the rotation rate, changing the loop radius for investigating the loop radius dependence on the detection sensitivity. The measured detection sensitivity characteristics coincided well with the theoretical prediction based on the Sagnac effect, and it was found that SRLs could be operated as optical gyroscopes. Furthermore, we verified that lock-in phenomenon was one of the most dominant noise sources in the S-RLG.

Fundamental characteristics of semiconductor ring laser gyroscopes

Semiconductor ring lasers have many capabilities of realizing new functional devices. In this paper, we propose a novel optical inertial rotation sensor using a semiconductor ring laser. If a semiconductor ring laser operates as an optical inertial rotation sensor, a very small and simple optical gyroscope can be realized. To our knowledge this is the first demonstration of a semiconductor ring laser gyroscope (S-RLG). Experimental results are as follows. (1) The Sagnac frequency shift can be detected as a beat note by the terminal voltage change of the semiconductor ring laser without branching the circulating optical power. Therefore, the S-RLG system can be constructed very simply as compared with already proposed optical gyroscopes. (2) The detected beat frequency between two counterpropagating lasers in the S-RLG is directly proportional to the applied rotation rate. (3) Furthermore, we present data demonstrating the injection locking phenomenon around low rotation rate. These results verify that the proposed S-RLG operates as an optical inertial rotation sensor based on the Sagnac effect. © 2000 Scripta Technica, Electr Eng Jpn, 132(4): 73–78, 2000

Experimental investigation of a semiconductor ring laser as an optical gyroscope

Fundamental characteristics of a semiconductor ring laser (SRL) as an optical inertial rotation sensor were reported. An SRL used for experiments had a small semiconductor gain block in a fiber external cavity. Beat frequency was measured by the terminal voltage change of an SRL as a function of the rotation rate, changing the loop radius of an SRL and the turn number of the fiber loop for investigating the detection characteristics. Detection sensitivity was proportional to the loop radius, and was independent of the turn number of the fiber loop. These experimental results verified that SRL's were operated as active ring laser gyroscopes based on the Sagnac effect. Furthermore, we verified that lock-in phenomenon was one of the most dominant noise sources.

半導体リングレーザジャイロスコープの基本特性

Semiconductor ring lasers have many capabilities of realizing new functional devices. In this paper, we propose a novel optical inertial rotation sensor using a semiconductor ring laser. If a semiconductor ring laser operates as an optical inertial rotation sensor, a very small and simple optical gyroscope can be realized. To our knowledge this is the first demonstration of a semiconductor ring laser gyroscope (S-RLG). Experimental results are as follows. (1) The Sagnac frequency shift can be detected as a beat note by the terminal voltage change of the semiconductor ring laser without branching the circulating optical power. Therefore, the S-RLG system can be constructed very simply as compared with already proposed optical gyroscopes. (2) The detected beat frequency between two counterpropagating lasers in the S-RLG is directly proportional to the applied rotation rate. (3) Furthermore, we present data demonstrating the injection locking phenomenon around low rotation rate. These results verify that the proposed S-RLG operates as an optical inertial rotation sensor based on the Sagnac effect. © 2000 Scripta Technica, Electr Eng Jpn, 132(4): 73–78, 2000

Proposal of a semiconductor ring laser gyroscope

We proposed a novel optical inertial rotation sensor using a semiconductor ring laser (SRL). The frequency difference between the two counter propagating oscillation frequencies was automatically generated in a mechanically rotated SRL, which consisted of a pig-tailed laser diode amplifier module. And the Sagnac frequency shift could be detected at the first time as a beat note by the terminal voltage change of the SRL without branching the circulating optical power. These experimental results verify that an SRL operates as an optical inertial rotation sensor based on the Sagnac effect.

Optical inertial rotation sensor using semiconductor ring laser

A novel optical inertial rotation sensor using a semiconductor ring laser (SRL) is proposed. The Sagnac frequency shift was detected for the first time as a beat note by the terminal voltage change of an SRL without branching the circulating optical power. These results show the feasibility of very small, simple optical gyroscopes.

Self-detection of lasing characteristics for semiconductor ring laser diodes

A novel method of measurement of lasing characteristics for a ring laser diode is proposed without branching of the optical lasing power. The lasing power and the linewidth as a function of the injection current have been measured by detecting the RF power by the terminal voltage change of a ring LD. The linewidth is estimated to be 55 kHz atl=1.75lth.

Longitudinal Mode Competition and Asymmetric Gain Saturation in Semiconductor Injection Lasers. I. Experiment

Longitudinal mode competition in transverse-mode-controlled laser diodes has been experimentally investigated. A careful examination of the output power change associated with both random mode switching and hysteretic mode jumping has revealed a peculiar feature of mode competition in laser diodes; in most devices, the output power is decreased as the lasing mode jumps from a shorter to a longer wavelength mode, which it is increased at mode jumping toward shorter wavelengths. The peculiar feature has been interpreted in terms of an asymmetry in gain saturation, which was experimentally observed. A terminal voltage change associated with mode jumping has also been measured. In some devices, a small shift of the beam profile was observed at mode jumping.

Optical self-routing switch using integrated laser diode optical switch

A 2*2 optical self-routing switch using integrated laser diode optical switches is proposed. The switch is composed of a Benes network, which can perform large-scale switching functions using less hardware than a crossbar switch. The path each data stream takes through the interconnection network is determined by the binary bits of its destination address, and self-routing is accomplished by monitoring terminal voltage changes in gain guides induced by input optical signals which are injected into a p-n junction. Concentrated control is not necessary, and large optical multistage switches can be easily constructed because complicated electrode patterns are not necessary. >

An expert system for voltage and reactive power control of a power system

A methodology called the sensitivity tree, which can be easily used to form an expert system for real-time control, is proposed. Based on this methodology, an expert system for the control of voltage and reactive power of a power system is developed. The main objective of this expert system is to help the operator detect buses experiencing abnormal conditions, select the most effective control measures, and calculate the control actions required to overcome the voltage violation. The control measures used to alleviate the voltage problem are capacitor compensation, transformer tap changes, and generator terminal voltage changes. By keeping the bus voltage in the entire system within limits, system security is increased. The expert system is written in the PROLOG language. Simulation studies with this expert system applied to a 30-bus power system show satisfactory results. >

A microcomputer based adaptive regulator for power system applications

The paper presents the design of an adaptive regulator for excitation control of a synchronous generator connected to an infinite bus through a double-circuit transmission line. The regulator, which is derived by simplification of the well known minimum-variance self-tuning controller, uses a variable forgetting factor stochastic approximation variant of the recursive least-square parameter estimator. This low order self-tuning algorithm is based on 3-parameter identification and is suitable for implementation with a single-chip microcomputer having restricted processing power, limited on-chip program storage and limited on-chip data storage capabilities. Simulation results are presented for a sample power system which is subjected to disturbances such as 3-phase short circuits, changes in terminal voltage and stochastic load variations. Tests using an LSI-11/23 microcomputer show acceptable performance in eliminating steady state errors and adapting rapidly to any changes in system operating conditions.

Signal-monitoring characteristics for laser-diode optical switches

Signal-monitoring characteristics of terminal voltage change across laser-diode optical switches (LDSW) have been studied. The terminal voltage changes are caused by the photovoltaic effect in the OFF state and by the quasi-Fermi level change in the ON state. The baseband frequency response characteristics are analyzed by small-signal analysis and coincide well with the measured characteristics. The 6-dB down frequency response bandwidths are verified to be very wide in both the ON and OFF states.