Induction Generators

ARTICLEINFO ABSTRACT Cyber-and sophistication of cyber adversaries grow, so too must the US power system's defenses, situational awareness, and response and recovery strategies. Tra dedicated communication channels to large generators and utility connectivity in today's industrial entities, including electrical utilities, has exposed many digital communication and c improvements including smart grid, smart meters and other advancements are considered, security is of foremost concern. In fact, governments around the world have recognized the existing v and need to protect the grid infrastructure. To solve the problem, regulations and standards are being developed to ensure that the proper security steps are taken. In addition, cyber attackers have targeted crude oil and natural gas (O&G) com impact as the industry employs ever more connected technology. But the industry's cyber maturity is relatively low, and O&G boards show generally limited strategic appreciation of cyber issues. research paper documents the current spread throughout US, highlights required security enhancements and recommendations to foster Cyber

—Recently, strong improvements have been made in the applicability of harmonic modeling techniques for electrical machines with slotted structures. Various implementations for permanent magnet motors and actuators have been investigated and applied in design and optimization tools. For the slotted structure of induction motors (IMs), however, the method has not been investigated very extensively yet. The main reasons for this are the complexity involved with modeling the large number of stator and rotor slots and the issues arising with the calculation of the induced rotor bar currents. In this work, a slotted harmonic model is implemented for a benchmark IM topology and a method to calculate the induced rotor bar current is investigated. The calculation results are validated by comparison to Finite Element simulations. It is shown that a good agreement is obtained for unsaturated operating conditions.

Abstract: - Traditional wind turbines are equipped with induction generators. Induction generators are preferred because they are inexpensive, rugged, and require very little maintenance. Unfortunately, induction generators require reactive power from the grid to operate and/ ...

Implementations of mini hydro schemes with conventional hydraulic, electrical equipment's and controllers have proven very expensive and uneconomical. Many developing countries that are in need of rural electrification have encountered economical problem when setting up these mini hydro schemes. To address this problem, alternative options and new designs of these equipment's have been explored by many researchers around the world. The application of these new designs would reduce the overall cost of mini hydro development and would help in making it a cost effective technology. These new designs will also help developing countries to provide electricity to rural areas or remote regions where interconnection of transmission line from the electrical grid is uneconomical. The new designs can also be an enabling factor in boosting up electricity generation using a renewable energy source. This paper provides survey of all these alternative options and new designs in the controller, hydraulic turbine and generators that have been implemented in different countries of the world.

Self-excited induction generator offers certain advantages over a conventional synchronous generator as a source of isolated power supply. Main advantages are reduced cost, less maintenance, self protection from short-circuit or overload condition, and brush less rotor. It is used as variable speed generator for different applications such as wind energy conversion, micro hydropower generation. Therefore, it is now a key interest to develop an efficient and viable Generator for harnessing the energy from renewable sources. To develop an efficient, viable, economic and controllable induction generator, we must know the steady-state performance of the generator. Using steady state equivalent circuit model excluding iron losses, steady state performance analysis has been done. Experimental investigations under steady state condition have been done in the laboratory. I. INTRODUCTION Electrical energy is the basic necessity of any country for its overall development. Fossil fuels (Coal, Oil, and Diesel) are the main sources of electrical energy (about 60% in our country). Fast depletion of fossil fuels results insecurity of availability of fossil fuels, subsequent increase in energy cost, the environmental pollution and above all the global warming. This has brought the worldwide attention in reducing the pollution and conservation of the limited conventional fuels by encouraging more and more use of the energy available from the non-conventional/renewable sources such as the wind, the biogas, the tidal waves and the small hydro power stations on the running canals and rivulets etc. The potential of the energy available from the small hydro and the wind sources seems to be quite promising to meet the future energy demands, especially in the remote and isolated areas. However, these systems will become more viable if their cost is reduced to the minimum. Therefore, the squirrel cage rotor induction generators are receiving much attention for such applications due to its low cost and robust construction[1-4]. The Self-Excited Induction Generators (SEIGs) are receiving increased attention from the utilities over the world to obtain the energy from renewable/non-conventional sources for remote and isolated areas. The main problems in the use of induction machine as a generator are related to the varying voltage and frequency, the loss of self-excitation, the overloading of the machine, the transient over voltages due to the capacitance switching or the load loss. But, the robust construction of induction machine specially squirrel cage type rotor, offers maintenance free operation and the least cost of the generating system. This has motivated to facilitate the use of the induction generator in isolated mode with suitable low cost control which could ensure the reliable supply of good quality. Also, such system for power generation could be made efficient and cost effective to compete with the other conventional energy sources[2-5]. The main objectives of this work are as follows:

"alah satu  sumber  energi  yang  cocok  untuk  dikembangkan  di  daerah-daerah  terpencil  di wilayah  Indonesia  adalah  Pembangkit  Listrik  Tenaga Mikrohidro  (PLTM).  Generator yang
banyak  digunakan  di  PLTM  adalah  generator  induksi  tiga fasa karena  harganya  murah, konstruksi  rotor  yang  kuat,  serta  mudoh  diperoleh  di pasaran.  Tetapi pada daerah-daerah
terpencil  umumnya  suplai  daya  yang  dibutuhkan  cukup satu fasa, sehingga  perlu  dicarikan alternatif  unluk  pengoperasikan  generator  tiga fasa untuk  suplai  satu fasa tanpa memerlukan
biaya  yang  mahal tetapi  handal.  Adapun  kelemahan  utama  generator  induksi adalah tegangan  yang  tidak  konstan. Perubahan  beban  pada  generator  dapat  menyebabkan perubahan  pada  tegangan  dan frekuensi keluaran.

Tujuan penelitian ini adalah,melakukan  pengujian dan perhinngan  untuk menentukan  nilai kapasitor  minimum  yang  dibutuhkan  unnk  mengubah  motor  induksi  tiga fasa sebagai
generator  induksi  tiga fasa untuk suplai  daya  satu fasa, dengan daya  keluaran  800 Watt, tegangan  220  Volt dan frekuensi 50  Hz.dan merencanakan  dan  merealisasikan  alat pengontrol tegangan  terminal  generatol  dan  dummy  load,  untuk memperkccil ketidakseimbangan  tegangan  antar belitan fasa pada  generalor  akibat  pembebanan  satu fasa yang  dapat  mengakibatkan  pemanasan  dan  kerusakan  pada  generator.

Kata  Kunci: Generdor  Induksi,  Pengontrol  Tegangan,  Mikrokontroler,  Dummy load"

The self excited induction generators have been receiving attention for last decades as the most suitable power solution for remote areas. These have voltage and frequency regulation problems that stand against their spreading. This paper presents two simple voltage and frequency regulation methods for such stand-alone induction generators. The first and desired method, based on stepped capacitor uses programmable logic controllers (plc) in order to maintain constant values of the terminal voltage at different loads while frequency under different loads is regulated by regulating the prime mover speed by the same plc. The second method was developed by using an external resistance in series with the terminal capacitor while frequency under different loads is regulated by regulating the prim-mover speed .both methods were experimentally verified using a 1.5 kw squirrel cage induction generator supplying resistive loads. A computer simulation model depending on the generator steady state performance was developed. The experimental data show good agreement with computed results. La version autonome générateurs d'induction d'avoir l'attention de ces dernières décennies que la solution d'alimentation la plus appropriée pour les zones rares. Mais ils ont un problème de régulation de tension et de fréquence qui se dresse contre leur propagation. Cet article présente deux de tension et de méthodes simples régulation de fréquence pour les générateurs d'induc-tion autonome. La première méthode souhaitée sur la base intensifié condensateur a utilisé des contrôleurs logiques programmables (PLC) afin de maintenir des valeurs constantes pour les deux tensions aux bornes et la fréquence sous différentes charges. La seconde méthode obtenue en utilisant une résistance externe en série avec la borne du condensateur. Les deux méthodes sont expérimentalement vérifiées à l'aide de 1,5 kW à induction à cage d'écureuil générateur alimentant des charges résistives. Un modèle de simulation informatique dépend de la performance de l'État générateur soutenu produit. Les résultats expérimentaux montrent un bon accord avec les résultats calculés.

—Fault ride-through (FRT) is a common requirement to abide by grid code all over the world. In this paper, to enhance the FRT capability of fixed speed wind generator system, a modified configuration of bridge-type fault current limiter (BFCL) is proposed. To check the effectiveness of the proposed BFCL, its performance is compared with that of the series dynamic braking resistor (SDBR). A harmonic performance improvement by the proposed method is also analyzed. A three-phase-to-ground (3LG) fault was applied to one of the double circuit transmission lines connected to the wind generator system. Simulation was carried out by using MATLAB/Simulink software. Simulation results show that the proposed BFCL is a very effective device to achieve the FRT and suppress fault current that eliminates the need for circuit breaker replacement. Also, the BFCL improves the harmonic performance and helps follow harmonic grid code. Moreover, it was found that the BFCL works better than the SDBR and has some distinct advantages over the SDBR. Index Terms—Bridge-type fault current limiter (BFCL), fault ride-through (FRT), fixed speed wind turbine (FSWT), grid code, series dynamic braking resistor (SDBR), total harmonic distortion (THD).

- This paper describes a real-time simulator of wind turbine generator system suitable for controller design and tests. The simulated generator is a grid-connected doubly fed induction machine with back-to-back PWM voltage source vector control at the rotor. The simulator ...

— Capacitor-excited induction generator offers certain advantages over a conventional synchronous generator as a source of isolated power supply. Main advantages are reduced cost, less maintenance, self protection from short-circuit and overload condition. It is used as variable speed generator for different applications such as wind energy conversion, micro hydropower generation. Therefore it is now a key interest to develop an efficient and viable generator for harnessing the energy from renewable sources. Steady state analysis is important for the design and control point of view to develop an efficient, viable economic and controllable induction generator; we must know the overall performance of the generator. In this work, the steady-state performance of a capacitor excited induction generator driven by an unregulated turbine is analysed both incuding and excluding the iron-losses. The speed is considered as a variable for the unregulated turbine case. The steady-state equivalent circuit is solved using the node admittance method, and the shaft torque is expressed in terms of the rotor current. The newton raphson method is used to solve the system nonlinear equations. For the present investigation, a linear speed-torque characteristic is considered, but the method of analysis applies equally well to nonlinear characteristics.

The paper presents analysis of distribution system connected with distributed generations. The study addresses aspects related to optimal sizing and location of DG units for losses minimization and voltage stability improvements. Many cases have investigated to highlight the relationship between the optimum size and location for losses minimization and the optimum size and location for stability improvements. The student version of the AMPL software is used in the proposed study. The objective function is formulated with full consideration of both quality and inequality constraints. On the other hand, the stability index criterion is used for calculating the best location and size for system stability improvements. The 90 bus test system from the literature is used for the different studied cases. The results show that calculating minimum system losses is not necessary to achieve coherence improvement for the voltage stability problem.

In this paper, we propose a Wind Energy Conversion System (WECS) at variable speed using a Doubly Fed Induction Generator (DFIG) controlled on the rotor side through converters. A Flywheel Energy Storage System (FESS) is connected to the studied wind generator at the DC bus in order to evaluate its capacity to participate to the ancillary services. We study the improvement of the active and reactive power quality produced by the wind generator and its effect on the load voltage regulation connected to the wind generator. For that, a fuzzy logic supervisor is established to control the FESS operation and the DC bus voltage in order to smooth the active power fluctuations due to the random wind speed variations. A control law is also described to smooth the reactive power at the connection node to the grid.

Το άρθρο που ακολουθεί παρουσιάζει τη μετατροπή μαθηματικού μοντέλου τριφασικής ασύγχρονης μηχανής βραχυκυκλωμένου δρομέα σε σύστημα διαφορικών εξισώσεων κανονικής μορφής. Μερικά στοιχεία σχετικά με την αριθμητική επίλυση και το πρόγραμμα προσομοίωσης που βασίστηκε στο προαναφερθέν μοντέλο
παρουσιάζονται επίσης, καθώς και σχετικά διαγράμματα και σχόλια.