The QCLNG Curtis Island project is the first LNG project in the world to convert coal seam gas into liquefied natural gas (LNG). The project is being constructed by Bechtel Oil, Gas & Chemicals.
The ConocoPhillips Optimized Cascade Process uses gas turbines to drive compressors in the liquefaction process. In addition, gas turbine generators are used to provide power to the LNG plant.
The black start power for the gas turbine generators is provided by essential generators. In determining the function of the essential generators, the system designer has many factors to consider including:
· The method for the black start, considering the fuel e.g. diesel or natural gas
· The bus configuration
· The synchronizing points
· The automation sequences of operation
· Live bus transfer for transfer to plant and transfer to essential diesel generators
· Import / export control
· Essential and non-essential load control
· Load shedding
· Exercising of the generators
· Protection, inter-trips and interlocking systems
Case Study - The Consequence of System Failure - Sayano-Shishenshaya Hydroelectric Power Station Accident.
In many cases, the consequences of a system failure in a power station, can result in a station black out. Careful attention to the design of the various systems in the power station can be rewarded with a failure which does not cause any equipment damage or any injury.
Sometimes, the consequences of failure can be catastrophic. Unfortunately, this happened in the Sayano-Shushenskaya Hydroelectric Power Station accident.
An investment in the design of the power station systems is effectively an investment in reducing the risk of a future system failure. On a monetary basis, the investment is not large when compared with the operating cost of a station. The return on investment can be considerable, compared with the cost of system failures.
Advanced Automatic Generation Control Systems and Operating Philosophies for Islanded Power Stations.
Electricity Grid Schematic
The reliability of transmission and distribution networks is typically measured with industry standard indices such as:
· SAIFI (System Average Interruption Frequency Index)
· SAIDI (System Average Interruption Duration Index)
· CAIDI (Customer Average Interruption Duration Index)
· ASAI (Average Service Availability Index)
For Islanded Power Stations, the reliability of the power generation can have a significant impact on the reliability indices for the distribution network.
Modern control systems are generally automatic for efficiency and reliability. Key factors in reliable power generation are the determination of the operating philosophy and the design of the generation control systems.
The operating philosophy is tailored to the application. It has an impact on the design of both the electrical power network, the protection system and the control system.
Factors and challenges, which can influence the design of the control system and the determination of the operating philosophy, are typically:
· The reliability required for the application e.g. mining, utility, industrial, critical power
· The intended method of operation, level of sophistication
· The power station outputs
· Type and number of generator units
· The fuel system to be used
· Integration of renewable energy sources and distributed generation
· Integration of energy efficiency e.g. waste heat recovery
· Legacy power stations, if the station is being restructured or expanded
· Frequency and voltage regulation
· Import / export control with inter-connected power stations