한국해양대학교

Detailed Information

Metadata Downloads

비선형 PID 제어기의 설계 및 LNG 연료 선박기관의 열교환기 시스템에 응용

DC Field Value Language
dc.contributor.advisor 진강규 -
dc.contributor.author 소건백 -
dc.date.accessioned 2019-12-16T03:00:51Z -
dc.date.available 2019-12-16T03:00:51Z -
dc.date.issued 2018 -
dc.identifier.uri http://repository.kmou.ac.kr/handle/2014.oak/11778 -
dc.identifier.uri http://kmou.dcollection.net/common/orgView/200000105271 -
dc.description.abstract Excessive use of fossil fuels resources is adding several types of greenhouse gases which make the earth warmer. Emissions from ship's exhausts contribute to global climate change, too. The International Maritime Organization (IMO) has adopted regulations to reduce the emission of air pollutants from international shipping, such as major air pollutants, carbon dioxide (CO2), nitrogen oxides (NOx), and sulphur oxides (SOx) under Annex VI of the 1997 MARPOL protocol. Likewise, as regulations on the emission of major air pollutants have become internationally strict, the development of environmentally friendly vessels and engines is required. One of the globally accepted means of reducing emission gases is the use of more eco-friendly fuel, LNG (Liquefied Natural Gas). LNG as a marine fuel reduces air pollutants as referred compared to traditional heavy fuel oil (HFO). Recently, large engine manufacturers are developing LNG-fuelled marine engines. In order to use this cryogenic LNG as a fuel, it is necessary to change it back to a gaseous state. A heat exchanger is used to regasify LNG. The heat exchange takes place between LNG and glycol on the primary loop, and heat exchange occurs between glycol and steam on the secondary loop. These series of processes are called LNG regasification. To control the temperature of the heat exchanger, it is necessary to model the heat exchanger. However, it is not easy to obtain an accurate mathematical model because the heat exchanger has non-linearity and time-varying characteristics. In addition, a fixed-gain controller is bound to have a limitation in its function if parameters of the heat exchanger are changed. Thus, various techniques have been studied to improve the adaptability and robustness of the controller. Recently, there has been using nonlinear PID (NPID) controller for the controlled system which have highly nonlinear and time-varying characteristics during operation. Therefore, this thesis proposes two types of the nonlinear proportional, integral, derivative (NPID) controllers to control the glycol temperature of the regasification system for LNG-fuelled marine engines. The Fully-Nonlinear PID (F-NPID) controller has a structure that the error between the set-point (or reference input) and output (or the measured output) is scaled nonlinearly, and input into the controller to derive proportional, integral, and derivative controllers. The Partial-Nonlinear PID (P-NPID) controller uses the conventional linear PD controller and only I controller uses the method of F-NPID controller. In this case, the nonlinear functions are implemented by the Fuzzy model of Takagi-Sugeno (T-S) type. In addition, the error is continuously scaled so that outstanding control performance can be maintained even when the operating environment is changed, thereby improving the swiftness and the closeness of responses. Also, the parameters of the two proposed controllers are optimally tuned in terms of minimizing the integral of the absolute error (IAE) objective function based on the genetic algorithm (GA). Meanwhile, it is necessary to examine the stability of overall feedback system that can be caused by introducing nonlinear functions during controller design. For this, the stability of the overall feedback system is analyzed by applying the circle stability theorems, which is often used for stability analysis of nonlinear problems. The proposed controllers are verified their performances which are the set-point tracking, robustness against noise and parameter changes, disturbance rejection performances by comparing with two conventional PID controllers and a conventional NPID controller. -
dc.description.tableofcontents Chapter 1. Introduction 1 1.1 Research background and trends 1 1.2 Research content and composition 6 Chapter 2. LNG-fuelled Marine Engines 8 2.1 Changes of LNG-fuelled marine engines 8 2.2 Fuel injection of LNG-fuelled marine engines 10 2.3 Fuel supply system of LNG-fuelled marine engines 13 Chapter 3. Modeling of LNG Regasification System 17 3.1 Heat exchanger 17 3.2 LNG regasification system 18 3.3 Modeling of the secondary loop heat exchanger of LNG regasification system 19 3.3.1 Model of an I/P converter 19 3.3.2 Model of a pneumatic control valve 20 3.3.3 Model of a heat exchanger 23 3.3.4 Model of a disturbance 27 3.3.5 Model of a RTD sensor 28 3.3.6 Model of a time delay 29 3.3.7 Open-loop control system 30 Chapter 4. Surveys of Existing PID Controllers 32 4.1 Linear PID controller 32 4.1.1 Structure of the conventional PID controller 32 4.1.2 Characteristics of control actions 33 4.1.3 Effects of PID controller gains 36 4.2 Gain tuning of the conventional PID controller 37 4.2.1 Ziegler-Nichols tuning method 37 4.2.2 Tyreus-Luyben tuning method 40 4.3 Practical PID controller 41 4.4 Existing nonlinear PID controllers 44 4.4.1 Seraji’s NPID controller 45 4.4.2 Korkmaz’s NPID controller 48 Chapter 5. Suggestion of the Proposed Nonlinear PID Controllers 52 5.1 Fully-nonlinear PID controller 52 5.1.1 Nonlinear P block 53 5.1.2 Nonlinear D block 57 5.1.3 Nonlinear I block 57 5.1.4 Relationship between  and  60 5.2 Partially-nonlinear PID controller 62 5.2.1 Linear PD block 63 5.2.2 Nonlinear I block 63 5.3 Feedback control systems 63 5.3.1 Modified F-NPID control system 63 5.3.2 P-NPID control system 66 5.4 Tuning of the controller parameters 68 5.4.1 Genetic algorithm 68 5.4.2 Optimal tuning of the controller parameters 73 Chapter 6. Stability Analysis 75 6.1 System description 75 6.2 Basic definitions and theorems 76 6.3 Stability of the NPID control systems 86 6.3.1 Sector condition of nonlinear block 86 6.3.2 Stability analysis of F-NPID control system 87 6.3.3 Stability analysis of P-NPID control system 88 Chapter 7. Simulation and Discussion of Results 90 7.1 Controller parameter tuning 90 7.2 Reponses to set-point changes 91 7.3 Reponses to noise rejection 94 7.4 Reponses to system parameter changes 95 7.5 Reponses to disturbance changes 97 Chapter 8. Conclusion 99 References 101 -
dc.language eng -
dc.publisher 한국해양대학교 해양과학기술대학원 -
dc.rights 한국해양대학교 논문은 저작권에 의해 보호받습니다. -
dc.title 비선형 PID 제어기의 설계 및 LNG 연료 선박기관의 열교환기 시스템에 응용 -
dc.type Dissertation -
dc.date.awarded 2018-08 -
dc.contributor.alternativeName So, Gun Baek -
dc.contributor.department 해양과학기술전문대학원 해양과학기술융합학과 -
dc.description.degree Doctor -
dc.subject.keyword Circle criterion, Nonlinear PID controller, Regasification system, Temperature control, T-S fuzzy model -
dc.title.translated Design of Nonlinear PID Controllers and Their Application to a Heat Exchanger System for LNG-fuelled Marine Engines -
dc.contributor.specialty 해양선박플랜트 -
dc.identifier.holdings 000000001979▲200000000563▲200000105271▲ -
Appears in Collections:
해양과학기술융합학과 > Thesis
Files in This Item:
비선형 PID 제어기의 설계 및 LNG 연료 선박기관의 열교환기 시스템에 응용.pdf Download

Items in Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse