Generator Operation Mode Research Articles

Modelling and Simulation of MEMS Electret Vibration-Driven Energy Harvesters

To solve the problem of feeding the remote microsystems the electret microgenerators powering by the energy of ambient micro vibrations were analyzed. The numerical modeling of all the operation modes of these generators was performed not taking into account the certain design of mechanical part of their operation. This approach allows one to analyze generator operation in the full range of possible parameters, such as generation frequency, load, capacitance modulation depth and electret polarization value. The cases of out-of-plane vibrations as well as the lateral (in-plane) shift of the capacitor plates were investigated. Basing on the results of numerical modeling of all the operation modes of electret generators the analytical expressions for maximum generated power were derived. The performed analysis has shown that for the range of low frequency vibrations (10-100 Hz) the power density could be increased by two orders of magnitude compared with known prototypes

Emission characteristics of GTL fuel as an alternative to conventional marine gas oil

The study examine the gaseous, smoke and particulate matter emission characteristics of a turbocharged heavy-duty diesel engine operated on conventional marine gas oil and gas-to-liquid Fischer–Tropsch fuel under modes of propulsion and generator operation. The gas-to-liquid showed average reductions up to 19% in nitrogen oxides, 25% in carbon monoxide, 4% in carbon dioxide and 30% in smoke with slight increase in unburned hydrocarbon emissions. Particulate number concentrations for gas-to-liquid were up to 21% higher, whereas particulates mass showed a 16% decrease at medium and high loads, while increasing by 12–15% under lower load conditions. Very low aromatic content of gas-to-liquid fuel and nearly zero sulfur level are responsible for particulate reduction.

Modélisation forward-backward des machines synchrones à pôles saillants en régime stationnaire

This paper presents a diphase analytical modelling of salient pole synchronous machines aiming at studying 'accurately' the operating of these structures. Based on the Park transformation and the concept of forward and backward currents, the proposed model differs from usual approaches by the fact it introduces the e.m.f. into the different relations. This model is then used to study different motor and generator operating modes of salient pole synchronous machines and buried permanent magnet synchronous machines. The results confirm known practical results and also show a certain number of non trivial features.

1101 分散型電源システムの分散協調制御(制御)

In this paper, we focus on distributed generation systems composed of power generators such as gas-turbines and communication channels. For the systems, we consider determining operation modes (on/off modes) of generators based on distributed cooperative optimization. We first show a distributed cooperative control algorithm. Then, we verify the effectiveness of the algorithm by several numerical simulations.

Electrically controlled generator of micron and submicron water aerosol

A generator of micron and submicron water aerosol of combination (condensation and electrogasdynamic) type is described. In this generator, a steam-gas jet flowing via horizontal capillary from a container with supersaturated steam is subjected to the effect of corona discharge. Attention is called to the importance of taking into account the orientation of the capillary and position of the corona electrode relative to the steam-gas jet. It is found that the parameters of aerosol particles during the condensation of steam-gas jet significantly depend on the intensity of corona discharge. An explanation of observed phenomena is given within the assumption of competition between the forms of condensation in the steam-gas jet, namely, homogeneous condensation, heterogeneous condensation on ions of corona discharge, and heterogeneous condensation on water film fragments formed at the capillary exit section under the effect of electric field. The prevailing forms of condensation are determined in various modes of generator operation depending on the ambient temperature and the intensity of corona discharge.

Instructional training system for turbogenerator control

A computerized training system for instruction of personnel on the control of turbogenerators during excitation and synchronization of the generator is described; the system is intended for: familiarization with the theoretical bases of generator-operating modes, study of the principles of generator control, improvement of the understanding of the physical bases of instructions regarding control, analysis of possible consequences of errors and violations of instruction requirements, study of emergency modes and the development of anti-emergency measures, and acquisition of experience with generator excitation and synchronization. A basic characteristic feature of the training system is the fact that it includes a complete course of instruction, which covers study of theory, and practical control adjustments under normal and emergency conditions on a trainer, and the knowledge of instructees is tested, and final results are evaluated. The system can be used both in special educational institutions, and also directly at electric power stations in a self-preparation mode.

D204 大規模乱流中に置かれた円柱周りの流れの可視化

In order to understand mechanism of aerodynamic noise generation in large turbulent flow fields, vortex structures of flow around a circular cylinder were visualized by using an active turbulence generator (ATG). To reduce the noise level of the active turbulence generator, passive silencers and low noise operation mode were developed. Therefore the aerodynamic noise from the developed ATG was only 10 dB larger than that of the conventional wind tunnel. It is well-known that small holes were used to reduce aerodynamic noise radiated from a circular cylinder. Noise reduction effect of the holes was estimated in the large-scale turbulent flow filed. The experimental result showed that the noise reduction effect of the small holes was decreased when the cylinder was placed at strong turbulent flow field. In the case of the laminar flow, small holes make the impinging jets just behind the cylinder. The jets destroy the Karman vortex and reduce the aerodynamic noise. On the other hand, the velocity of the impinging jets was reduced by uniform turbulent flow. Then, the noise reduction effect of the holes was reduced in a large-scale turbulent flow field.

Optimization of Parallel-Series Self-Testing for Discrete Devices

Parallel-series self-testing process is optimized for test time and hardware costs. A procedure for forming tests inside the generator chip with standard and minimal imbedded hardware is designed. Generator operation mode is optimized so that it is “advantageous” in testing both large and small parts of an integral circuit.

Adaptive and Intelligent Systems for Generator Monitoring and Protection Purposes

New adaptive scheme for signal parameter measurement for generator monitoring and protection is presented. The algorithm is based on the orthogonal components of currents and voltages obtained with adaptive orthogonal filters. The filter data window length and coefficients are adapted according to coarsely estimated signal frequency. As a result, the measurements can be performed with high accuracy in wide frequency band conditions, i.e. also for generator start-up, etc. The measured signals are further used for training of artificial neural networks with the aim to design a robust and effective classifier of generator operation mode. The main attention is paid to the phenomena accompanying pole slipping and out-of-step conditions.

Control of feeding movements in the freshwater snail Planorbis corneus. III. Organization of the feeding rhythm generator.

(1) Neurons of different groups (for group classification, see Arshavsky et al. 1988a) have been polarized through an intracellular recording microelectrode in Planorbis corneus buccal ganglia during feeding rhythm generation. Group 1 neurons, active in the quiescence (Q) and in the protractor (P) phases of the cycle, and also group 2 and 4 neurons, active in the retractor (R) phase, have proved to be "influential", i.e., altering the rhythm generator operation. (2) Injection of a depolarizing current into group 1 neurons caused an increase of the rate of depolarization that neurons of this group exhibit in the Q- and P-phases of the feeding cycle. As a result, Q-phase shortened, the P-phase became longer, and the feeding rhythm accelerated. Opposite effects occurred when a hyperpolarizing current was injected into group 1 neurons. In some of the experiments, the hyperpolarization of group 1 neurons resulted in cessation of both their activity and the activity of all other protractor neurons. As a result, the P-phase of the cycle disappeared, i.e., the rhythm generator transited from A mode of operation to B mode. (3) With hyperpolarization of individual group 2 or 4 neurons, excitation of the R-phase neurons was delayed and the feeding rhythm phase shifted. This delay was accompanied by the enhanced activity of protractor neurons. (4) A generator model is considered in which two groups (1 and 2) of endogeneously active neurons are coordinated by the excitatory effect of group 1 on group 2 and the inhibitory action of group 2 on group 1. (5) Evidence is given that the different modes of rhythm generator operation (A, B and C, see Arshavsky et al. 1988a) are determined by different tonic inflow to group 1 neurons.

Dynamic Measurement And Analysis Of Air Gap Variations In Large Hydroelectric Generators

This paper presents the development and application of a new fibre-optics instrumentation system for accurate measurement and analysis of the dynamic air gap behaviour of large hydroelectric generators. The system uses a passive reflective fibre-optics sensor which is immune to EMI and functions correctly on an excited operating generator. Air gap tests were performed on four 184 MV. A, 15.6 m stator bore diameter generators with 16 radial stator support rods. One of these units at B. C. Hydro's Peace Canyon Project suffered rotor-stator contact damage during commissioning in November 1979. Thirty-two air gap measurements were made around the stator during consecutive revolutions, at precisely repeatable points at, and midway between, the noted support rods. These measurements were used to produce a series of polar coordinate air gap maps which facilitated very fine trend analysis of the critical modes of generator operation. These tests and the interpretation of the data, which assisted in the solution of specific problems, are presented.

Steady State Modelling of Regeneration and Self-Excitation in Induction Machines

Six modes of source-connected and self-excited induction generator operation including both voltage (VSI) and current (CSI) inverter systems are reviewed and compared. Equivalent circuits to represent each mode are presented and the use of the circuits to model steady state performance is illustrated. The analysis clearly shows the fundamental importance of main flux saturation in the self-excited cases as compared to its secondary importance in source-connected systems. General properties of regeneration and self-excitation are derived to illustrate the basic similarities and differences between the various modes. Experimental results which support the validity of the models used in the study are included.

SMALL SIGNAL DYNAMIC ANALYSIS OF REGENERATION AND SELF-EXCITATION IN INDUCTION MACHINES

ABSTRACT Small signal stability and dynamic response is examined and compared for six modes of source-connected and self-excited induction generator operation including both voltage (VSI) and current (CSI) inverter systems. It is shown that conventional small signal machine modelling is incapable of yielding any information whatsoever concerning the stability of self-excitation at constant speed. A recently introduced small signal model which includes main flux saturation overcomes these difficulties and is employed to study the stability properties of all six modes. General stability and dynamic response properties of each mode are summarized and compared, especially with respect to the influence of saturation. The capacitive self-excited case is shown to require special treatment because of the phase freedom inherent in this mode. Experimental confirmation of some of the results is included.

Induced field-system transients in synchronous generators having unidirectional forms of excitation supply

Synchronous-generator excitation supply systems that are based on a.c. exciters operating in conjunction with rectifiers, as is now widely the practice, give rise to particular modes of generator operation that do not occur when d.c. exciters are used. In the case of a d.c. exciter, the field current can reverse, if it is required so to change by stator operating conditions, whereas an a.c. exciter and a rectifier system provide an essentially unidirectional form of supply. A preclusion of field-current reversals by the rectifiers introduces a constraint into the interaction between the rotor and stator circuits of the generator for which the excitation system provides a supply. For a wide range of generator operating conditions, the constraint is inactive, and so no adverse effects arise, but credible circumstances can combine to cause the constraint to become active. When this is the case, the transition of the constraint from inactive to active is accompanied by a pulse of induced voltage in the field system. The paper reports a study of field-system overvoltages that might be generated in this way for the particular conditions encountered in synchronising. A mathematical model suitable for use in computer studies in this area of applied analysis in power systems is summarised, and the validity of the model is checked by comparing computer study results with those available from fullscale tests on a 120 MW turbogenerator unit. Numerous synchronising studies have been based on this model, and representative results from them are collected together in the paper, together with the synchronising conditions that can give rise to overvoltages. When synchronising is achieved within the close limits typical of British practice, the hazard of induced field voltages of substantial magnitude should be avoided altogether, but the continuously recurring nature of synchronising generator units with a parent system suggests a general study of the conditions. It is a general study of this kind to which the paper is devoted.