PERMANENT MAGNETS GENERATORS FOR
WIND AND WATER PLANTS
This paper presents some particularities in the construction of synchronous generators for wind and hydro-plants and low power generators with permanent magnets with a simplified construction. Also, a comparison between variants of generators with electromagnetic excitation and permanent magnets is done.
The advantages of the use of supermagnete from rare earths, Neodim Iron Bor (NeFeB), especially the increase of the efficiency of these generators, are highlighted, and finally the maximization of efficiency is mentioned by replacing the conductive materials (copper, aluminium) with superconducting ceramic materials at ambient temperature.
Keywords: wind power, electrical generators, supermagnete
Cuvinte cheie: energie eoliană, generatoare electrice, supermagnet
PERMANENT MAGNETS GENERATORS FOR
AUTONOMOUS MICRO-HDYRO POWER PLANT BEHAVIOR ON WATER THREAD OR WATER DIVERSION
This work presents the requisites for a micro hydro power plant located on a water thread or on the water branch, where the water flow determines the speed of and, implicitly, the power supplied by the synchronous tri-phased generator with self-excitation. Such a micro hydro power plant functions depending on the water flow capacity and water fall given by the penstock. The low-voltage electric energy produced by this plant is transported to the consumer through an underground power cable. The command and control of the micro hydro power plant can be automated, the sole human intervention being the opening and the close of an intake valve.
Keywords: micro-hydro power plant, synchronous generator, electrical energy, consumer
Cuvinte cheie: microhidrocentrală, generator sincron, energie electrică, consumator
DETERMINING THE OPTIMAL LINIAR CURRENT
DENSITY VALUE FOR SYNCHRONOUS
This work presents the way linear current density values influences the dimensions, costs, and performances of some synchronous generators. The studied generators, with various rated speed, were designed following classic and optimal methods in order to determine the linear current density optimal value depending on a specific optimization criterion. The optimal design has been realized with the Simplex algorithm where the objective function aims total cost reduction for the synchronous generator. The linear current density value has been determined for both the classical design and for the optimized solution. Comparing the two results we analysed the impact these variable has on the synchronous generator’s dimensions, mass, losses, on the generator’s efficiency, costs, and flask currents. We draw conclusions referring to the optimal value tendency for the linear current density depending on its variation interval and on the generator’s rotation speed.
From the analysis we observe that to achieve a cost-optimal synchronous generator, the linear current density value must be chosen close to the upper limit of the variation interval.
Keywords: the objective function, the optimal design, synchronous generator, current blanket
Cuvinte cheie: funcţie obiectiv, proiectare optimală, generator sincron, pătura de curent
A RAPID METHOD FOR DETERMINING THE NET
POWER OF AN ASYNCHRONOUS MACHINE
This work presents a method to rapidly determine the net power of an
asynchronous machine running as a motor. For this we read a minimal set of
engine speed values, excitation winding current values, power factor values
when we know the nominal values of the tested engine. The find the net power
values we use the phases in drawing up the circle diagram for an electrical
machine. This method can easily used to find the electric energy balance of
various industrial units.
Keywords: net power, asynchronous motor, energy balance, circle
Cuvinte cheie: puterea utilă, motor asincron, bilanţ electroenergetic,
STABILITY STUDY FOR A TURBINE-SELF EXCITED
SYNCRONOUS GENERATOR HYDRAULIC GROUP OF A
This work aims to determine the stability of a self-excited synchronous
generator, which works in the autonomous mode, based on the link between
the hydraulic turbine–synchronous generator aggregate, the internal
aggregate’s generator angle, which depends on its load, and the opening angle
of the unit director. To verify the correctness of the relations presented in this
work the designed aggregate has been tested with sudden loads and various
resistive and inductive loads. The aggregate behaved as expected, remaining
stable following the transitory processes.
Keywords: static and dynamic stability, self-excited synchronous
generator, micro hydro power plant, self-adjustable drive
Cuvinte cheie: stabilitate statică şi dinamică, generator sincron
autoexcitat, microhidrocentrală, acţionare autoreglabilă
INFLUENCE OF CURRENT BLANKET FROM THREE-PHASE
WINDING OF SYNCHRONOUS GENERATOR ON
REACTANCES OF ITS
In the optimal design of synchronous generator is necessary to
analyze the influence of different important sizes (current blanket, A, induction
of the air gap, Bδ, the stator inner diameter, D, air gap width, δ, etc.) on the
external parameters (dimensions, mass, cost, efficiency, etc.) or internal
(reactance, currents, time constants, etc.) of the synchronous generator. In this
paper we analyze the influence of the current blanket reactance synchronous
generator. Analysis was performed using an optimization program written in
Keywords: Blankets current, synchronous generator, design, optimization,
Cuvinte cheie: pătura de curent, generator sincron, proiectare, optimizare,
INFLUENCE OF SIZE AIR GAP A THREE-PHASE
SYNCHRONOUS GENERATOR THE TOTAL COST OF ITS
The total cost of a three-phase synchronous generator, containing the
cost of manufacturing and operating costs throughout its life, depends on the
size of the generator and its air gap. The air gap is size with a small value
compared with dimensions of synchronous generator, but is strongly influenced
by electromagnetic requests. In this paper we aimed to analyze the influence of
air gap variation on overall dimensions, mass of active materials, loss of these
and implicitly on the total cost. This analysis was possible after writing a
program for optimal design of synchronous generator using MathCAD software.
Cuvinte cheie: întrefier, generator sincron, optimizare, cost total
Keywords: air gap, synchronous generator, optimization, total cost