SIM 5800 Combined Cycle Power Plant (CCPP)

Model Description

SIM 5800 operates by first combusting biogas, driving a gas turbine connected to a generator. Heat is recovered from the hot exhaust gases in a Heat Recovery Steam Generator (HRSG) to generate steam. This steam drives a second turbine, sharing the generator shaft with the gas turbine, providing additional power to the generator, resulting in a high overall efficiency.

A clutch connects the steam turbine and generator, allowing for quicker startup times and maintenance. The feedwater used to produce steam is deaerated and demineralised to prevent equipment damage. The process can be fully shut down and restarted and is coupled with an Emergency Shutdown (ESD) system presented with a standard cause and effect matrix. 

Operational Modes: 

• Power Generation Mode: Biogas supplies energy to the gas turbine, and the exhaust heat from combustion is used to generate steam which powers the steam turbine. The shaft driving the generator is coupled to both the gas turbine and the steam turbine via a clutch. 
• Grid Stability Mode: When the gas turbine is ‘off,’ i.e. no fuel is being burned to generate power, the rotating mass of the generator is used to aid stability of the grid. Regardless of the mode, CCPG adds inertia to the grid, enhancing overall stability and reliability. 

CCPGs are used for their fast startup times, flexibility in load following, and reduced carbon emissions compared to coal-fired plants. Fast ramp times allow grid energy demand to be met during periods of low renewable energy generation. The feed to the gas turbine is biogas, co-fired with hydrogen, both of which are renewable fuels. Furthermore, integration with carbon capture technologies would reduce the plant’s carbon footprint. 

The CCPP simulation model covers the key components and operational aspects of a combined cycle power plant, including: 

• Deaerator: Steam stripping process to remove dissolved oxygen from water, preventing corrosion in the system. 
• HRSG – Heat Recovery Steam Generator: A cascade of heat exchangers, including attemperators, optimising heat recovery from exhaust gases. 
• Steam Turbine: Comprised of two sections—High Pressure (HP) and a combined Medium Pressure (MP) and Low Pressure (LP) stage. 
• Condenser: Facilitates condensation of exhaust steam, improving system efficiency. 
• Clutch (SSS Clutch): A synchronous self-shifting clutch allowing for flexible operation and faster startup times. 
• Generator: The core component converting mechanical energy into electrical power. 
• Switchgear & Droop Control: Ensures safe power distribution and load balancing. 
• Gas Turbine: Provides primary power generation using fuel gas, with exhaust heat utilised for steam generation. 

Learning Areas

The simulation model enables users to: 

• Understand the working thermodynamic principles behind CCPG. 
• Analyse the role of heat recovery in improving efficiency. 
• Gain insights into electrical load balancing and integration with the power grid. 
• Monitor key performance parameters such as efficiency, exhaust gas temperature, and steam pressure. 
• Understand startup and shutdown procedures—ignition, synchronisation, and load ramp-up. 
• Evaluate the economic feasibility of running the system with or without the steam turbine. 
• Calculate overall plant efficiency, considering ambient temperature, fuel composition, and load changes. 
• Explain the integration of a CCPG plant with renewable energy sources and grid stability considerations. 
• Learn how rotating mass dampers enhance grid stability when turbines are not generating power. 
• Comprehend the principles of CCPP and its role in modern power generation. 
• Evaluate CAPEX and OPEX considerations for CCPG plants. 
• Monitor NOx emissions under varying operating conditions. 
• Explore the impact of ambient conditions (air temperature and pressure) on performance. 

This simulation serves as an essential tool for engineers, researchers, and educators looking to deepen their knowledge of efficient power generation and grid stability