Generator Excitation System
The THYRIPOL 520/1800 R excitation system is one of the main strategic systems in power plants used in gas and steam units. It is manufactured by MECO under SIEMENS license for medium and large-scale generators.
To achieve redundancy (2×100%) and increase the system reliability, two separate working channels including two AVR controllers and two rectifiers have been used. In case of an error or at operator command, while maintaining the normal system operation and without changing the machine terminal voltage, one channel replaces the other immediately and without interruption.
In the power circuits, two AC switches are provided to isolate the excitation system panel from the input which results in easy system maintenance.
In implementation of excitation control system based on the generator physical limitations and customer needs, many control functions and limits such as over-excitation and under-excitation limiters, along with stator current limiter, voltage per Hz, PSS power system stabilizer, reactive power controller and power coefficient controller are taken into account.