Gemi dizel motorlarının bilgisayar ile kontrolu

Abstract

Bu tezde sunulan çalışma, Gemi Dizel Motorlarının ve bunlara bağlı sevk sistemlerinin bilgisayar aracılığı ile kontrolünü sağlayacak bir program ve sistemin oluşturulmasıdır. Geliştirilen bu model Donanmamızda mevcut DOĞAN sınıfı Hucumbotlardaki ana tahrik sistemini oluşturan, MTU 16 V 956 Tb 91 dizel makina ve buna bağlı MTU KSS 60 Şanzumanm kontrolünü gerçekleştirmektedir. Birinci bölümde giriş, ikinci bölümde kaynak araş tırması verilmiştir. Üçüncü bölümde; Kontrolü istenen Ana Tahrik Siste minin ana hatları açıklanmış, devre şemaları ve sistemin çalışma parametreleri verilmiştir. Dördüncü bölümde; Kontrol ihtiyaçları, nedenleri ve program procedürleri verilmiştir. Beşinci bölüm sistemde kullanılacak olan sensörler hakkında bilgileri içermektedir. Altıncı bölümde interface komputeri tanıtılmakta dır. Yedinci bölüm; Similasyon programını içermektedir. Similasyon programı ana tahrik sistemi sensörlerinden alınacak olan dataları içeren bir dosya ile çalış maktadır.

Over the last decade a lot of effort has been devoted to the improvement of performance of the Diesel Engine and ship-board Main Propulsion systems. The utilisation of digital computer technology and the use of extremly sophisticated CAD/CAM programs have enabled the mechanical engineers to design and develop nearly perfect engine models. As the research work in this field continues, an urgent need to command and control such complex engines has become apparent. It is given that the power output from an engine depends upon the amonunt of fuel that can be usefully burnt inside the engine cylinder. However, engine control mechanism which manages all the action taking place inside a Diesel, is the prime element that controls the effective power output from the system. It has been proven that a Computer controlled gavorner system can handle the speed of a Diesel engine much more effectively than a classical mechanical control system. This may be basically due to the very high process speed and storage capabilities of a digital computer which is used in the control system. For instance, a digital computer may store a Diesel engines power curves and a wide variety of engine control parameters in its memory and use those values during the control process effectively. The mechanical engineering has been considering the computer control methods of a Diesel engine in order to meet the requirements of a complex control system. The use of complex computer techology may result in very efficient, reliable, secure and minimum personnel controlled propulsion systems. Vlll The work presented in this thesis, is concerned with the computer modelling of the real-time control mechanism of a main propulsion system. The study involves a computer program which simulates a real Diesel engine and a development of a total control and monitoring system. In this thesis, an MTU 16 V 956 TB 91 Diesel engine and a MTT KSS 60 reduction gear have been chosen as the real main propulsion system model. The model has been studied and analysed completely. Using the results of this work the control parame ters and control requirements are determined. It has been proven that the following requirments are sufficient for controlling a main propulsion system; a)- A safe pre-start sequence check procedure 1- Lubricating oil level control 2- Fresh water level control 3- Start air pressure control k- Control air pressure check 5- Reduction gear position control 6- Engine status check 7- Emergency stop value check B- Engine fresh water temperature check b)- Start sequence procedure 1- Control of the start button 2- Start of the oil priming pump 3- Control of the oil pressure k- Control of the air start value 5- Control of the engine speed 6- Activation of the alarm circuits IX c)- System monitoring and control sequence 1- Control of the engine speed and power curve 2- Control of the system reduction gear 3- Observation of the system parameters k- Emergency stop and Alarm procedures The developed engine control model is composed of a main control computer, an interface computer and the main propulsion system sensor block. : But in fact, interface computer and the sensor block have been modeled as part of the main control computer and simulated by the developed engine control program. The developed simulation program is composed of several functional modules. Each module performs independent tasks, to fulfill the requirements of the overall control system. At the commencement of the control program, sensor parameters and system status data is read by ah input module from the file named "VERİ DAT". The file veri. dat contains the required system parameters and system sensor outputs in order to initiate a pre-start sequence. The functional module "STARTHAZIR" checks and analyses the prepared system status tables to make sure that system is ready to start safely. After this process, start sequence procedure is activated by the module START. The modele START is responsible for the completion of the start sequence until the engine comes to the idle speed. All of the critical system parameters are sampled and abserved continously by the start module. The engine speed is assumed as the most critical parameters to be checked until the system exceeds the nominal idle speed. In fact, the main program continously call for the modules "EMERGENCY" and "ALARM" in any instant of the program execution. The module "EMERGENCY" checks the important real time system parameters and decides on that they are in safe operation limits. If the module detects any case in which safe operation limits are exceeded, the main engine is shutdown right away. The second degree system parameters are observed and checked by the "ALARM" module. In case of any failure, audio alarms are generated and message are displayed on the computer panel. an execution control module "icra» continausly monitor the position of the gas control levers. The module "ICRA" is able to engage or disengage the reduction gear clach and to control the speed of engine through the use of the position of gavorner step motor. A very important task is here to prevent the engine from being overloaded which may be due to the misalignment of the mainpropulsion system. The module "ICRA" acts just like a real-time servo-control mechanism during the operation of the overall system. The module "ICRA" arranges the data block which will be transmitted to the interface computer. The data block are prepared to comply with the requirement of the main propulsion system one of the important tasks of the module "ICRA" is to provide the communication between the main system computer and the interface computer. The commonds from the main control computer are transfered to the interface computer and the system status information and system sensor outputs are read back via interface computer. The module "ICRA" is responsible for the execution of the normal stop procedures which are ordered by the operator. In this engine control model, an interface computer is used to provide the communication between the main control computer and the propulsion system. The interface computer is a separete unit that can connect sensorjdata and commands as a real-time between system computer and main propulsion system. A very high performance computer board and a sophisticated sensor interface electronic are the principal parts of the interface computer. The data transfer is carried out using a very high rate XI bidirectional and secure serial link. The interface computer is also capable of detecting abnormal working conditions and taking action in case of emergencies. This computer continuously checks the operation of the serial data link from the main control computer. In case of any communication failure, the program of the interface computer is expanded outomatically in order to enable it to take over the overall control system. This aspect of the interface computer increases the system security to an important degree. In this control model main propulsion system has been provided with a wide variety of control sensors. These include pressure, temperature, speed and several position sensors. The structure and location of the sensors are chosen in such a way that the overall propulsion system parameters are sampled and checked completely. The speed sense procedure is assumed to be the most critical part of the sensor block and a special care has to be taken to control it in the real time. The sensor outputs are fed in to a sensor inter face electronic board. In this board, sensor outputs are signal conditioned by using the appropriate techniques in such a way that interface computer can read digital sensor data. This electronic board is also capable of transfering serial commands to the main propulsion system. These include engine start and stop, gavorner speed control and reduction gear control commands. This thesis basically considers a simulation program which models a main propulsion control system. Several algorithms are derived and tested according to the actual system parameters. The important system parameters such as engine power curve has been loaded on the computer memory. The developed computer program has been run and the results are analysed. This work has been proven that a computer controlled main propulsion system may be very effective and reliable. This research may be expanded in such a way that real system may be designed to see the results of this thesis. In order to achieve this an interface computer board has to be supplied and computer program developed. This board should also include the necessary hardware in order to implement the sensor interface electronic circuits. Finally proper sensor utilisation and setup on the real engine is required for overall system tests and experiments.