화력발전소 터빈 바이패스 밸브 협조제어를 통한 보일러 드럼수위 동특성 안정화 = Stabilization of the Dynamic Characteristics of Boiler Drum Water Level through Cooperative Control of Turbine Bypass Valve in Thermal Power Plant

다국어 초록 (Multilingual Abstract)

Recently, the electric power industry is developing with economic growth, and the demand for electric power is increasing with the development of society. The development of industrial technology increases consumer power demand and with various load power characteristics is required. Power plants must be able to satisfy consumers' demand for electricity with stably supplying high-quality and efficient of energy.
Control of the drum level is an important factor for efficient operation and reliable operation of a power plant. If the drum level exceeds the controllable range due to disturbances such as transients or sudden load fluctuations during the start up or shut down of the power plant, the power plant could be shut down for boiler protection.
This is a factor that hinders the economic and efficient operation of the power plant by delaying the start up time of the power plant and lowering the utilization rate of the power plant. Therefore, it is very important to keep the drum level at a constant set value regardless of disturbances. It is difficult to accurately measure the drum water level due to the variable density characteristics of water. In addition, due to the dynamic characteristics of the drum, the drum level and the drum level control valve is operated in the wrong direction. It makes the operation and judgment of the operator difficult.
In general, the drum level control consists of one element control and three element control. The one element control only considers the drum level. It is usually applied during the start up of power plant. The 3-element control is applied steam flow, water flow and drum level as controller inputs during normal operation. If the drum water level is controlled by applying only one- and three-element control, it is not effective to suppress dynamic characteristics such as swelling and shrinking of the drum. The drum level does not directly indicate the amount of water in the drum.
In the drum, it exists as a mixture of water and steam depending on the operating conditions of the boiler. The volume of the mixture is related to the pressure in the drum. When the steam flow rate is increased by increasing of load, the pressure in the drum is decreased and the specific volume of water is increased. As a result, it is indicated in the direction in which the drum level is increased. Conversely, when the steam flow rate is decreased by decreasing of load, the pressure in the drum is increased and the specific volume of water is decreased. The water level in the drum is decreased. Due to the dynamic characteristics, when the steam flow rate is increased, the feed water flow rate is decreased. Thus, it is difficult to control the drum level with only the drum level control valve.
In this paper, it is propose to apply the cooperative control of the drum level control valve and the turbine bypass valve to the drum level control as a method to reduce dynamic characteristics such as swell and shrink of the drum.

목차 (Table of Contents)

• 1. 서 론 1
• 1.1. 연구배경 및 필요성 1
• 1.2. 연구개요 및 논문 구성 2
• 2. 이론적 배경 3
• 2.1. 적용대상 발전소 개요 3
• 2.2. 드럼수위 제어 5
• 2.2.1. 개요 5
• 2.2.2. 드럼수위 측정 8
• 2.2.3. 드럼 동특성 11
• 2.2.4. 드럼수위 제어 13
• 2.3. 터빈 바이패스 제어 20
• 2.3.1. 개요 20
• 2.3.2. 터빈 바이패스 제어 21
• 3. 터빈 바이패스 밸브 협조제어를 통한 드럼 동특성 억제방안 23
• 3.1. 1요소 및 3요소 제어를 통한 드럼 동특성 확인 23
• 3.2. 드럼수위 동특성을 고려한 터빈 바이패스 밸브 협조제어 26
• 4. 결 론 33
• 참고문헌 34
• Abstract 35