Valmet DNA system covers the control, monitoring and reporting of all processes in combined cycle power plant. Operation and monitoring of turbines are typically carried out through the Valmet DNA operator interface, and also performance monitoring and optimization applications are available in the same system.
Controls supporting both base load and changing load situations
Automatic generation control (AGC) takes care of the load control of one or several units based on a local or remote load target
Grid frequency support (primary and secondary frequency controls) and island mode operation
The operation modes of a combined cycle power plant vary from base load operation with constant rate power generation to the fast-cycling plant operation that follows the continuously changing load. Industrial power plants follow the electricity and steam consumption of the processes or their heat customers. Utility power plants may follow load targets from some remote load dispatcher and can participate in load stabilization and grid support with primary and secondary frequency control actions.
Due to the development of energy markets, there are increasing demands for faster and more frequent power plant startups. The so-called two-sifting operation mode means that the plant is started up in the morning when the energy demand is higher and disconnected from the grid in the evening. The startup should be automatic and as fast as possible, while considering thermal stresses and fuel consumption.
The island mode occurs when the power plant, or a part of the power plant, is isolated from the national grid. In island mode, it is important to rapidly balance the power consumption and power generation to avoid a forced shutdown due to a frequency deviation.
All different operation modes and optimized startups require a high automation level and coordinated control of the whole power plant.