Small Biogas Plant Stability Prediction Model

In this paper stability prediction for a small biogas plant in islanded mode depending on local consumers energy consumption growth is given. Biogas plant with two cogeneration facilities and local consumers is tested for on grid and islanded operation and thus represents a microgrid. Generator and regulator modelling as well as surrounding electrical grid modelling in software package Power World Simulator are described. Expected consumption growth through the period of 20 years in microgrid area is simulated. All generator important variables, i.e. voltage, frequency, real and reactive power in case of islanded mode are examined and explained. Finally, stability prediction analysis of biogas plant and surrounding consumers for 20 years period is given

Exploring the Possibilities of Adjusting Gensets to NATO Requirements

Stationary and mobile gensets are used in the Armed Forces of the Republic of Croatia. In this research, priority was given to mobile gensets which have a variety of uses. In addition to being used in the Republic of Croatia, the mobile gensets are also used in international military operations in various modes of operation. Therefore, it is necessary to be very familiar with their characteristics and the possibility of adjusting them to NATO requirements. For the purpose of the adjustment, a test was performed on a P-B40.R1 genset. A model that simulates the genset behaviour with different tested fuels was developed. The investigated genset, together with some others, was introduced into the Armed Forces pursuant to the Product Quality Protocol that was in force during the 1990s. The Protocol did not cover all requirements and recommendations for the genset operation in an international military environment. Therefore, research was conducted, which has resulted in the adjustment of the equipment and in the harmonisation of the Product Quality Protocol with the ISO standard and NATO requirements. When adjusting the materiel, special emphasis is given to defining certain genset types that are able to use the modified F-34 kerosene-type fuel instead of diesel fuel. The F-34 fuel is obtained from kerosene used in aviation; this fuel can be easily obtained in international military operations where the tendency is to use the same type of fuel for airplanes, vehicles, and diesel engine equipment. When F-34 is used as the genset fuel, the quality of the generated electrical energy might be reduced. For the purpose of bringing the output characteristics of the generator within prescribed limits, simulations were performed both with and without the tuning of the regulation parameters

Detection of Failures on the High-Voltage Cage Induction Motor Rotor

In recent years, problems of increasing energy efficiency and stability in the work of electric motor drives, are becoming more and more important. Reducing costs of production in many industries should necessarily modernize our technological processes, the introduction of modern electronic devices should raise the level of automation and modern methods of management and protection. Motor efficiency has been significantly increased per volume unit by improving the technology of motor production, which means that less volume per motor power decreases the thermal time constant; therefore, warming-up is faster under abnormal conditions. Advanced HV cage induction motors are constructed for high powers, dimensioned for precisely defined load, also with very low permissible overload. There are many different factors which influence operation of induction motors, and any deviation of some of those factors could cause damage to the motor. This paper will discuss the issues of failures on the high-voltage cage induction motor rotor, the causes of failures and their detection

Modelling of an Expert System for Diagnosing the Operational Status of a Diesel Genset

The modelling of an expert system for diagnosing the operational status of a diesel genset represents the final stage of the research undertaken so far on military gensets. The research was undertaken in several stages on a large number of gensets, and the results obtained at specific research stages were published at scientific-expert conferences. For the purpose of modelling an expert system, a knowledge base was compiled based on detailed observation of the genset operational status, interviews with experts with many years of experience in maintaining military gensets and also on a breakdown of the occurred faults archived in the overhaul documentation.The paper uses only that one segment of the knowledge base that is necessary for modelling a simplified form of the Bayesian network for fault detection in assembled condition. In addition to input probabilities, the results of diagnostic tests and simulations carried out in the Matlab Simulink program package are also entered in the Bayesian network. Fault detection represents a complex process so the application of an expert system significantly reduces the time needed for fault detection, resulting in optimized maintenance. It is especially significant in military and similar organizations which apply a large number of technical resources. The Bayesian network is processed in the GeNIe program package

Optimization of Maintenance and Use of Gensets in the Armed Forces

The Armed Forces use a great number of various types of gensets. The aim is to reduce this large number of diverse genset types, that is, to standardize the equipment used with the aim of simplifying maintenance and modes of use. For this reason, tests are conducted which should provide factual conclusions as to the types of gensets which are both most favourable for use and maintenance and also meet the conditions required by international military operations. One of these requirements is the possibility of using the kerosene fuel F-34 for diesel engines. It is well known that diesel engines running on kerosene fuel develop less power, which can result in the direct reduction of generator rotation speed at rated loads. Therefore, we conducted tests on one type of electric genset by using resistor load. The additional goal was to conduct tests on other types of electric motors by using different types of loads. It was particularly important to conduct the tests during the acceleration of an asynchronous motor since gensets are also used in technical workshops to run compressor units and in these instances asynchronous motors often turn on. So, in order to facilitate conductivity, we also developed mathematical models and computer simulation

Teeth Losses in Induction Machines

Izvedene su formule za proračun gubitaka vrtložnih struja u pravokutnim zubima. Pokazano je da se, uz pretpostavke da su permeabilnost i vodljivost lima konstantni, ukupni gubici vrtložnih struja mogu računati kao zbroj pulzacijskih i površinskih gubitaka. Date su upute kako se mogu računati ukupni gubici u zubima za sve oblike zuba uzimajući u obzir potiskivanje toka u limovima, prigušenje toka u zubima, te faktore obrade lima i paketa limova.Formulas that have been derived are used for calculation of eddy current losses in square teeth. It is shown that, assuming that permeability and conductivity of iron are constant, the overall eddy current losses can be calculated as the sum of pulsation and surface losses. Directions have been given on how to calculate the overall teeth losses for all forms of teeth taking into consideration skin effect of flux in lamination, damping of teeth flux and factors of iron sheet and core processing

Adaption of genetic algorithm for more efficient minimization of active power losses in power network

U radu je prikazano optimiranje razmještaja kondenzatorskih baterija u stacionarnoj električnoj mreži primjenom genetskog algoritma. Razmještanje kondenzatorskih baterija obavljeno je s obzirom na najmanje djelatne gubitke u vodovima mreže za slučaj postojećih kondenzatorskih baterija, tj. za slučaj kada nema troška nabave kondenzatorskih baterija. Predloženi genetski algoritam prilagođen je navedenom problemu optimiranja. Prilagodba genetskog algoritma obavljena je učinkovitijim definiranjem kodiranja jedinki, jednostavnijim izborom načina selekcije i sinergijom genetskih operatora križanja i mutacije.A presentation of genetic algorithm for solving the optimization problem of capacitor banks displacement in the power network has been given. Optimal displacement of capacitor banks is obtained using the criterium of minimal active power losses in network lines for existing capacitor banks. The proposed genetic algorithm has been adjusted for the optimization problem. An adaption of genetic algorithm has been done by more efficient individuals coding, by simplifying the selection type and by synergy of genetic crossover and mutation operators